CA2079851A1 - Automated hand-held keratometer - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An automated portable keratometer includes a hand held housing and is battery powered. A projection system projects collimated light sources at equal converging angles to an optical axis which extends outside the housing. A camera, including an imaging device, and telocentric objective lens are aligned along the optical axis in the housing. The projection system projects a known pattern of collimated light sources onto a patient's eye.
The reflected images of these light sources is captured by the camera and imaging device. Derivation of the distances between certain reflected images can be converted by known algorithms into radii of curvature of the eye. Alignment leveling, and other features can be included with the keratometer. The device can also be used to measure other curved surfaces.

Description

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I. BACKGROUND OF THE INVENTION
A. Field of the Inve~tion This invention relates to keratometers, and in particular, to an automated ~eratometer, including one that is relatively small in size, and hand-held.

B. Problems in the Art 1. Definition of Keratometer A keratometer is an instrument utilized to measure the radius of curvat~lre of a curved surface; generally that of an eye. Readings are usually taken of the radius of curvature of ~wo different axes, 2s well as the angle of those two different axes. The results are utilized to estimate the dioptric power along each axis, which can then be used to estimate refractive power and/or shape of the particular eye being tested.
The primary readings taXen by the keratometer are the curvature along the axis of maximum curvature, the curvature along the axis of minimum curvature, and the angles of the two curvature axes with respect to the horizontal axis. These types of readings 2re used to fit eye glasses or contact lenses.

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' 2979~1 ~ccuracy is therefore important. This is particularly true for contact lenses which are placed in direct contact with the surface of the eye.
Keratometers are also used to examine the pathology of the cornea for such things as keratoconus, dystrophies, and stigmatism, corneal problems, and abnormal curvature. It is usually a standard piece of equipment for an optometric o~
ophthalmic examination.
2. Manual Keratometers Xeratometers originally were all manually operated optical devices. They continue to be used today. A manual keratometer requires the patient's head to be accurately positioned and maintained in position with respect to the device. Manual dials are then turned by the operator to create some optically perceivable condition in the device. Some manual keratometers require the operator to align several circles in a particular orientation while viewing the patient's eye. A reading is then taken from the dials or, in the earliest versions, a chart is ; consulted to obtain the readings. These readings must then be manually transcribed.
; ~anual keratometers represent a substantial investment, and require substantial space in an office for the patient and operator to complete the procedure. Perhaps the most significant problems of manual keratometers are the amount of time required to take the appropriate readings and the amount of training and expertise needed by the operator to achieve reliable results.

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Operation of these devices requires some level of advanced skills and knowledge. They generally must be operated by ophthalmologists, optometrists, or perhaps opticians. Some judgment and experience on a rathex high level is needed to take and interpret the readings and create the conditions needed to ensure the readings will be generally accurate and reliable.
Kanual operation includes potential for human error. The operator must ta~e significant care in the procedures and may need to retake the measurements to double check original measurements. Sometimes interpretation of results is needed, requiring substantial expertise.
Manual keratometers generally allow apical measurements only, and do not allow peripheral cornea measurements. New sur~eries and treatment techniques require accurate peripheral measurements. ~lanual keratometers also have a number of moving parts and rely on expensive high precision optical elements.
Calibration and the maintenance of calibration is therefore very important. All of Lhe above discussed problems leave room for improvement in this field.

3. Automated Keratometers In an attempt to meet these needs, automated keratometers have been developed. These devices generally utilize some electro-optical combination to provide keratometric readings ~hich can be displayed, stored, or sometimes printed. Major deficiencies of present automated systems are as follows.
Many of these devices require a substantial amount of manual operation. Some require that the operator align the instrument - , ..
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to the eye by viewing and aligning images in the keratometer optical system. One requires alignment of lights and geometric figures. This requires the operator to subjectively determine whether a certain somewhat subjective condition exists, introducin~ an element of error risk.
These systems require the user s head to be fixed with respect to the machine. Normally this will include a chin or head brace and necessitates constant vigilance to ensure that the head is kept in a fixed position.
Most automated keratometers take up a substantial amount of space. Many consume the better part of a medium sized table.
The operator sits on one side of the machine, while the patient sits on the other. It might also require associated equipment, taking even more room.
It is to be understood that the size of some automatic keratometers is so large that it must be put in a separate room, or at least a room outside of the normal examination room. This requires additional patient shuffling from the waiting area to tne examination room, to the room for the keratometric readings, and so on. This further complicates and is an obstacle to efficiency of patient processing. It can create a bottle neck if all the patients need to go to a separate room, have keratometric readings taken, and then return to the examination room.
Auxiliary equipment such as motorized tables and chairs is sometimes utilized with the automated keratometer to accurately . .
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position the patient. This adds significantly to the cost and to the space needed for operation. These machines tend to be heavy and their inner contents somewhat fragile. ~ost also require precise optical components. They are also extremely costly as compared with manual keratometers.
Automated keratometers therefore include potential errors associated with the requirement of human verification or subjective determinations. They also rely on precise, costly optical components which must be maintained in precise alignment and calibration.
They also require a high level of operator training and expertise. The added cost and space required for these devices may therefore offset any improvement they provide in time or accuracy.

4. Size and Space Considerations Xeratometers are generally utilized in the offices of ophthalmologists and optometrists. They may also be utilized by opticians. Xeratometric measurements are often taken for each patient`s visit. This is especially true for those who wear contacts. The keratometer measures the curvature of the eye.
The contact, to be fitted properly, is placed directly adjacent to the eye. Most ophthalmologists and optometrists set up "lanes" in each examination room. Patients are called from the waiting room and moved through a series of equipments or stations in the lane during eye examinations.

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Much consideration is given into maxirnation of patient flow o~ turnover. Several patient rooms with completely furnished lanes are therefore utilized. While one patient is put through the measurements in the lanes, another patient can be brought into another room and prepared. A third patient who has finished with measurements can then be readied for completion of the exam while the ophthalmolo~ist or optometrist ~oes to another room and/or another patient.
Time and space are primary factors in improving the efficiency of patient flow. More time to perform the keratometric measurements, translates into less time available to do other things. More room for the keratometer, translates into less room for other equipment, or a reduced number of patient rooms; which translates into more square footage and more costly office space. Less costly and smaller manual keratometers, are more time consuming to operate. Automated keratometers, take up much more room and are more cumbersome.
With current keratometers it is not possible to delegate the taking of keratometric reaàings to staff members. They require either substantial training and/or substantial expertise, knowledge,,and skill to operate. ~hese traits may not be readily available in staff members. At a minimum, there is a requirement of extensive or long training and experience. Otherwise accuracy and reliability may suffer substantially.

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While automated keratometers are generally much more costly than manual keratometers, the trend is to purchase and use automated keratometers. There is a perception, perhaps primarily by patients, that automated, higher technoloqy equipment is a necessity for competent and successful ophthalmological and optometrist practice.

5. Needs in the Art Although automated keratometers are available, their problems and deficiencies are readily apparent as discussed above. A need therefore exists for an automated keratometer which is small in size, takes all keratometric readings quickly, accurately and reliably, and is easy for staff workers or technicians to operate.
There is also a need for a portable automated keratometer that need not be placed on a table nor require constraint of the patient's head. There is also a need for an automated keratometer which is less costly than current automated keratometers.

6. Objects It is therefore a principal object of the present invention to provide an automated keratometer which solves the problems or improves over the deficiencies in the art.
Another object of the present invention is to provide an automated keratometer which is substantially automatic and eliminates substantially the margin of human error in its operation.

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A still further object of the present invention is to provide an automated keratometer which can be hand held, is easily maneuverable, light weight, and can even be battery powered.
A still further object of the present invention is to provide an automated keratometer which does not requlre fixed positioning of the patient's head or eye with respect to the device.
Another object of the present invention is to provide an automated keratometer which has an automated alignment system to ensure alignment during measurement.
~ nother object of the present invention is to provide an automated keratometer which helps patients fix on a target to eliminate possible measurement errors caused of loss of fixation or movement of the eye.
Another object of the present invention is to provide an automated keratomeler which automatically processes, displays, and stores or prints keratometric readings.
Another object of the present invention is to provide an automated keratometer which allows the user to simultaneously view the patient's eye.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.

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I I . SUMMARY OF THE INVENTI ON 2 ~ 7 ~ ~ 5 ~
The invention is an automated keratometer which is portable and hand held. It is freely and easily movable into a position near a patient's eye and does not require the patient to have his/her head fixedly secured.
A portable housing contains a projector system and a camera system. The projector system includes a plurality of collimated light sources which project out of the housing onto the patient's eye. The housing is moved to a position where the projected light sources circumferentially surround the optical axis of the eye. The position of the housing is also adjusted so that the optical axis of the eye is made generally co-linear with an optical axis through the Xeratometer through the camera means.
The camera means is positioned telecentrica'ly along the optical axis. It captures the reflected image of the projected light sources on the eye. A processing means then determines the -elative spatial locations of the reflected light sources and derives radii of curvature measurements according to an algorithm in the processing means.
The invention includes optional features and enhancements such 2S alignment means for automatically indicating alignment along the optical axis. A fixation means is also provided to assist the patient in fixing his/her eye during measurement. A
leveling means can also be incorporated to automatically indicate the housing is in a level position.
The keratometer can be battery powered and optionally can be rechargeable. It can include a display so that the calculated ~ ~ .
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~eratomet~ic measurements can be observed by the operator. It can also store those measurements to be printed out or otherwise documented.
The invention therefore will completely free the operator and patient of the requirement of dealing with a table top device ta~ing up substantial space, and will take quick and accurate readings. Its level of automation reduces potential for error and its combination of components xeduces the cost to manufacture, assemble, and therefore retail the device.

III. BRIEF DESCRIPTION OF TH~ DRAWINGS
Fig. 1 is a perspecti~e view of a preferred embodiment of the invention.
Fig. 2 is a slightly enlarged side elevational and partial sectional view of Fig. 1.
Fig. 3 is a still further enlarged sectional view taken along line 3-3 of Fig. 1.
Fig. 4 is a partial section, partial cutaway view, taken generally along line 4-4 of Fig. 3.
Fig. 5 is an enlarged front elevational view of Fig. 1.
Fig. 6 is an enlarged bac~ elevational view of Fig. 1.
Fig. 7 is a still further enlarged sectional view taken along line 7-7 of Fig. 6.
ig. 8 is still a further enlarged sectional view taken generally along line 8-8 of Fig. 7.
Fig. 9 is an isolated partial sectional side elevational view of the optic system of the preferred embodiment of the present invention.

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Fig. 10 is a bottom plan view of Fig. 9.
Fig. 11 is an isolated enlarged depic-tion of two pro~ection means according to Figs. 9 and 10 and the preferred embodiment of the invention.
Fig. 12 is a diagrammatic view of the optical system of the preferred embodiment of the invention.
Figs. 13A-D are diagrammaticaL depictions of an eye and keratometric measurements generally taken with a keratometer.
Figs. 13A and 13B depict radii of curvature measures cen-tered on the cornea. Figs. 13C and 13D depict the same but centered off the cornea.
Figs. 14A-G are diagrammatical representations of various status conditions during operation of the keratometer as viewed through the eye piece of the preferred embodiment of the keratometer.
Fig. 15 is a diagrammatic representations of Fig. 14G as captured by a camera means according to the preferred embodiment of the present invention.
Figs. 16A-16C are diagrammatic depictions of a flow chart of software operation of the preferred embodiment of the present invention.
Fig. 17 is the general block diagram of the electrical circuitry of the preferred embodiment o~ the present invention.
Fig. 18 is a more detailed partial schematic partial block diagram of the input/output section of Fig. 17.
Figs. l9A-C (sometimes referred to collectively as Fig. 19) are a detailed electrical schematic of the input/output section of Fig. 18.

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Fig. 20 is a partial schematic, partial block diagram of the main board of Fig. 17.
Fig. 21 is a detailed electrical schematic of the CCD driver section of Fig. 20.
Fig. 22 is a detailed electrical schematic of the power supply circuit of the preferred embodiment of the present invention.
Fig. 23 is a detailed electrical schematic of the microprocessor of Fig. 20.
Fig. 24 is a detailed electrical schematic of the image processor of Fig. 20.
Fig. 2~ is a block diagram of the overall circuit for the preferred embodiment of the invention.
Fig. 26 is a block diagram of the image processor gate array of Fig. 25.
Fig. 27 is an internal block diagram for the gate array.
Figs. 28-29 are electrical schematics for a printer driver that can be used with the preferred embodiment of the invention.
Fig. 30 is an electrical schematic of a projector printed circuit board that can be used with the preferred embodiment of the invention.
Figs. 31-32 are electrical schematics for circuitry that can be used with the base of the preferred embodiment of the invention.
Fig. 33 is an electrical schematic of a Mire ring printed circuit board that can be used with the preferred embodiment of the invention.

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Figs. 34~-34B are diagrammatical charts of the different main function states for the software of the preferred embodiment of the invention.
Figs. 35-38 are electrical schematics of the circuitry associated with imaqe processing for the preferred embodiment of he invention.

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V. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
One preferred embodiment of the invention will now be described to assist in providing a more complete understanding of the invention. The description of this embodiment will be in detail including various features and advantages which may accompany this embodiment. The invention is capable of ta~ing on many different forms and embodiments. This is but one of those forms, and is the preferred form.
This description will first give a broad overview of the embodiment and its structure. A more specific discussion of the structure will then follow. A description of the optical system of the embodiment will be set forth including examples of its operation. Finally, discussion of the electronic circuitry involved in the embodiment will be set forth referring to block dia~rams and-schematics.
This description is made in conjunction with the drawings.
Reference numerals are sometimes utilized in the drawings to indicate specific parts and loca~ions in the drawings. The same reference numerals will indicate the same parts or locations throughout all of the drawings, unless otherwise noted.
A. Overview -- Fiq. 1 ~ ig. 1 depicts in perspective keratometer 10 according to the present invention. Keratometer 10 includes a hand grip 12 at one end, and a projection portion 14 at the other end. An intermediate portion 16 exists between hand grip 12 and projection portion 14.

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Fig. 1 illustrates keratometer lO mounted in a base 18.
Base 18 serves as a support stand for keratometer 10, and can also provide a connection to recharging circuitry to recharge the batteries which power keratometer lO. Further, as diagrammatically depicted in Fig. l, base 18 can include connection means to auxiliary devices such as printer 20 or computer 22.
Hand grip 12, projection portion 14, and intermediate portion 16 comprise a housing 24 for keratometer 10. Dimensions of housing 24, for the preferred embod-ment, are generally about 10-12 inches long, 3-1/2 inches at its widest point, and about 3-1/2 inches deep. It weighs only about 24 ounces. By gripping hand grip 12 (5 inches tall by l-1/16 inches width and depth) and removing keratometer 10 from base 18, the keratometer 10 can be easily manipulated and moved with the operator. It also can be o-iented easily in a number of different ways. This ability differs drastically from state of the art and is extremely adv2ntageous.
Base 18, Iherefore, is only several inches long and wide.
It takes up a very small ~footprint~ on a table or 2 cabinet top in comparison to present automated keratometers. It provides a secure and stable resting or storage place for keratometer lO, and allows the user to easily and quickly grab keratometer 10 and move it where the patient is, instead of requiring the patient to come to the machine and be manipulated into position.
Printer ~0 allows readings obtained by keratometer 10 to be ?rinted in hard copy. Printer could optionally be incorporated ~: :

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lnto base 18. The readings can then be preserved, for example, by immediately placing them in a patient's file. Computer 22 can be utilized to store measurernents obtained by keratometer 10, or to program the operation of ~eratometer 10. Buttons 26 and 2~ on the top face of base 18 can be utilized to control various operations as desired.
Fig. 1 also shows the basic structure of keratometer 10.
This will be described further below, hand grip 12 would enclose a substantial amount of the electrical circuitry for keratometer 10. Intermediate portion 16 includes external control buttons 30 and display 32. Display 32 is a liquid crystal display (LCD) which is a reliable yet low power display.
Intermediate portion 16 and projection portion 14 contain most of the optical components for keratometer 10. Fig. 1 shows eye piece 34 which allows the user to view directly through projection portion 14 and out a projection window 36 on the opposite side. The user or operator of ~eratometer 10 would then hold housing 24 so that the projection window 33 is in front of and within a few inches of a patient s eye, while the users~ eye is moved directly up to eye piece 34. This arrangement is easily facilitated by the shape and configuration of housing 24, including hand grip 12. The user's thumb can easily push any of the control buttons 30 or fingers on the other hand of the user can also do the same. The user does not have to move very much tO check the display window 32.

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-- Fig. 2 Fig. 2 shows ~eratometer 10 and base 18 from a different angle in a slightly enlarged form. A socket 38 exists in base 18 to receive end 40 of hand grip 12. A mating connection 42 inside base 18 allows electrical communication between keratometer 10 and base 18 to in turn facilitate connection to recharger, printer 20, or computer 2 2 .
A spine 44 extends from the rear of base 18 vertically upwardly. An extension 46 consisting of a bent rod extends from spine 44 outwardly and upwardly to a top end 48. A notch 50 in the underside of projection portion 14 of keratometer 10 is configured to matingly settle on top end 48 when keratometer 10 is ?laced on base 18 as shown in Fig. 2. This securely and stably holds keratometer 10 in place.
Base 18 includes a circuit board 52 (see Figs. 30A ~ 30B) which can contain the interface between keratometer 10 and printer 20 or computer 22. Base 18 could contain an LED light or lights 54, if desired, to indica~e recharging or printer in use, or other matters, as desired.
B. Overview of Operation A basic simplified description of operation of keratometer 10 will now be described with reference to Figs. 1 and 2.
~eratometer 10 is used to measure at least two radii of curvature of a patient s eye. These radii of curvature are usually taken along axes which are perpendicular to one another and which intersect at or near the optical center of the eye (generally the center of the cornea). If these radii of curvature are known, - . . . .. . . . ~: ~

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he diopter power or refractive power of the eye can be calculated. ~eratometer 10, therefore, basically is measuring the refractive power of the eye. It is a diagnostic tool to understand what type of correction the eye miyht need in the form of eye glasses or contacts or the type of fitting needed. It also may be used to discern any deformities or other problems with the eye.
The preferred embodiment of keratometer 10 allows the user to easily and quic~ly pick up keratometer 10, move it up to the patient's eye, align the keratometer, and take the appropriate measurements. When the readings are complete, they are stored and can be displayed on display 32. They can then be printed out to printer 20 when keratometer 10 is replaced to base 18.
In very simplistic terms, the measurements are taken as follows. TAe user brings keratometer 10 into position a few inches or centimeters from the patient's eye. The user then looks through eye piece 34 and can clearly see the patient s eye.
The user then tries to center keratometer 10 with respect to the patient's eye by estimation but is assisted in this because eye 34 is positioned directly along an axis which becomes co-linear with an optical axis extending through eyepiece 34 and projection window 36. In other words, if a line were drawn through the center of eye piece 34 and out the center of projection window 36, the user would try to put that line directly on the middle of the cornea of the patient's eye (or some other aiming point on the eye).

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Keratometer 10 includes automated methods to confirm centering of the keratometer 10, as well as to make sure that it is not too far away or too close to the patient~s eye. A
significant advantage of the present invention is that it does not require exact axial positioning of ~eratometer 10 with respect to the patie~t's eye but only requires that it be within a certain ran~e of positions which can be verified by the machine.
Alignment is facilitated by projecting a pattern of collimated light sources onto the eye. The pattern is configured so that the operator, by viewing the reflection of the pattern .hrough the eye piece can tell if keratometer 10 is within correct range from the patient's eye.
Once alignment is within an acceptable range, the actual measurements are taken generally as follows. A light is projected along the optical axes out the center of the projection window 36 onto the patient's eye.
This light serves as a fixation target f~r the patient to hold his/her eye steady. This fixation light is also visible by the user through eye piece 34 to assist in aligning the fixating light onto the patient's eye.
The next step is the projection of four highly collimated light sources onto the eye. These basically thin lines or beams of light converge at angles towards the optical axis and intersect the curved surface of the eye at points surrounding the fixation light along the optical axis.

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secause the angl~s of these light beams is known with respect to the optical axis, measurement of the spacing of the light point images reflected from the cornea can be used to derive the radii of curvature and major and minor aY~is angles of the cornea.
Measurèment of these distances is accomplished automatically. The reflection of the projected lights is received back through the projection window 36 and reflected along an optical axis to a camera which includes what is called a CCD imager. The imager is basically a matrix of picture elements (pixels) of very small size. Each pixel produces an electrical signal proportional to the intensity of light incident upon it and therefore basically replicates the reflection of the eye as it is received. The spacial positions of each pixel are known and correlated in memory and therefore distances between the reflected images of the projected lights can be derived electronically. The processor within keratometer 10 controls and calculates these measurements and converts them into readings which are displayed on display 32 and stored in memory.
Not only is keratometer 10 easy to handle, maneuver and use, it also facilitates ~uick and reliable accurate readings which can be preserved. The whole measurement proce~s, including positioning of the patient, takes only a matter of seconds. It is fast enough that several readings can be taken and averaged to increase accuracy.
The structure and form of housing 24, along with its light weight, make it very ergonomic, in addition to providing the many .
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~ ' 2~7~8~, advantages discussed. The operator can quickly a~d easily bring the ~eratometer to the patient, align it with automatic and automated assistance, verify the patient ls fixated, and take the measurement automatically. This in turn makes it much easier for ~eratometric readings to be routinely taken by staff, which would require much less training and expertise than existing devices.
C. Detailed Structure -- Fiq. 3 Figure 3 shows a still further enlarged form keratometer 10 in elevated section (and without base 18). The specific structure of the interior of housing 24 is shown. Projection window 36 is a plat glass disc (Rolyn Optics, Part X55.1258, 47.6mm dia., 3.lmm thick). Behind window 36 are a ring of red LEDs 56 (see also Figure 4) around the outer circumferential edge OI window 36. These LEDs are angularly oriented in converging fashion and when powered simultaneously project a ring of red light onto a patient's eye (depicted at 58 in ~igure 3). The ring of light is called a mire ring which when projected on eye 58 allows the user (see user's eye 60 in Eig. 3) to look through eye piece 34, and see-the ring on eye 58 to subjectively determine ii there are any abnormalities in the curvature or roundness of the eye.
Also behind window 36 are the four projectors 62 which project the thin collimated light beams onto the eye. Each projector consists of an LED 64 (Hewlett-Packard Part ~HLMP-Q101, , 2 ~ 7~

T 1 3/4 red tinted diffused LED) behind a pinhole card 66 (lmm pinhole) and a compound collimating lens 68 (Edmund Scientific B32, 719 Achromat, 30mm focal length, 15 mm dia. -t/- .lmm).
These components are held in projector tubes 70 which are each oriented at 21.5 (~/- 1 ) with respect to optical axis 72 as shown in Figure 3. Projector 62 therefore projects a point source of light along axes 74 so that they intersect with optical axis 72. By referring to Figure 4, it can be seen that each projector tube 70 is spaced an equal radial distance from optical axis 72 and at 90 from one another circumferentially around optical axis 72. As can be appreciated in Figure 3, the patient-s eye 58 must therefore be positioned in front of the point of intersection of axes 74 with optical _xis 72 so that each point of light from projectors 62 will be spaced apart on the front surface of eye 58. However, it is to be understood that there is a range of positions for eye 58 along axis 72 which ~llow reliable readings to be taken and therefore exact positioning is not required.
The optical axis of keratometer 10 consists of portion 72a extending through eye 58 and originating inside housing 24.
Portion 72b reflec~s off beam splitter 76 downwardly in Fig. 3 to camera means 78. Camera means 78 includes a compound lens 80 (Edmund Scientific Part ~B32, 312 Achromat Objective ~ens, 35mm ~.1., 12.5mm dia, ~/- .lmm), a pinhole device 82 (telocentric aperture pinhole -0.36mm dia., C.A.), and an imaging device 84 - ' ' 2 ~ 7~

(Texas Instruments TC 245, CCD Image Sensor). Camera means 78 captures the image of eye 58 and any projected beams onto eye 58 and electronically records those images. In the preferred embodiment, imaging device 84 is a CCD photo sensitive electronic area imager, such as is lnown in the art.
Figure 3 shows that portion 72c of optical axis 72 allows light to pass through beam splitter 76 and beam splitter 86 into eye piece 34. The user can then directly view the patient's eye 58 along the optical axis 72. Eye piece 34 includes a lens 88.
Figure 3 also shows additional optical components of preferred embodiment 10. A fixation LED 90 directs light from aperture 92 onto beam splitter 86. Beam splitter 86 allows some of the light to travel directly downward along axis 94 to a mirror 96. The light is then reflected back to beam splitter 86 which reflects some of the light along axis 72c to the user's eye 60. Beam splitter 86 directs another portion of the light from ixation LED 90 along axis 72c between beam splitter 86 and 76, tn-ough beam splitter 76 along axis 72a to the patient's eye 58.
The fixation LED 90 therefore presents a perceivable image along optical axis 72 for the patient to fixate on. This means the patient will concentrate on looking directly at the light, not moving the eye, and not moving the head. Additionally, the projection of fixation LED 90 a distance down axis 94 to mirror 96 and back to eye piece 34 is done for the following reasons.
The optical path distance between LED 90 and eye piece 34 is .. , ., :, ; :

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generally equ~l to the distance from the patient's eye 58 to eyepiece 34. The user will therefore perceive the image of the LED 90 to be approximately superimposed upon user~s eye 60. The patient will perceive the LED image to be approximately lOcm in front of his/her eye 58. Therefore, this arrangement gives the user a virtual image of LED 90 directly along the appropriate optical axis so that keratometer lO can be accurately positioned with respect to the patient's eye 58.
A leveling system is incorporated into the keratometer lO to automatically indicate the housing 24 is being held generally vertically straight up and down. A small rectangular sealed container 98 is filled partially ~ith fluid such as oil (for example, baby oil~. An LED 102 illuminates the oil in container '~8, essentially bac~-lighting the container 98 and oil lO0, including the meniscus formed at the top of the fluid in the container. The image of container 98 can travel along axis 104 portions a, b and c reflecting off of mirror 106 traveling through beam splitler 76 to camera means 78. By discerning the meniscus line between the top of oil lO0 and the rest of container 98, it can be determined if housing 24 is correctly vertically positioned. It does not indicate whether housing 24 is tilted too far towards or away from the patient's eye 58, however. This alignment problem is solved by other means which will be discussed later.

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Figure 3 also shows how housing 24 contains a printed circuit board 108 which extends virtually from the lower end 40 of housing 24 through handle grfp 12, intermedlate portion 16, and into projection portion 14. The battery compartment 110 is also shown. In the preferred embodiment, four AA batteries are utilized to power keratometer 10. An interfac~ between battery compartment 10 and circuit board 108 (denoted by number 112) is also shown. Contacts 114 between circuit board 108 and the end 40 of hand-grip 12 are shown which provide the communication between base 18 and keratometer 10.
-- Fiq. 4 ~ igure 4 generally depicts the side of keratometer 10 which is positioned in front of patient's eye 58. Axis 72 is directed toward the center of patient's eye 58, and the ends of projector tube 70 will issue the collimated light sources onto patient's eye 58. Aperture 116 is formed in a support 117 in housing 24, and represents the opening through which the reflection from the patient~s eye 58 returns along optical axis 72 into keratometer 10 .
-- Fi~. 5 Figure 5 depicts the side of keratometer 10 which includes eye piece 34 and control buttons 30. Display 32 is also shown along with connection 42 at the lower end of hand-grip 12.
Control buttons 30 can be for different desired functions or operations. In the preferred embodiments, buttons 30 relate to : ~ . - , :: ~ . : :~

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such things as selection of right or left eye of a patient, or measurement and storage of readings.
-- Fiq. 6 Figure 6 shows the opposite side of ~eratometer 10, similar to figure 4.
-- Fiq. 7 Figure 7 is a sectional view of the interior of projection portion 14. It shows in more detail each projector 62 according to the present invention. In particular, it shows each projector tube 70 is slightly adjustable along projector base 118. This allows a slight adjustment of lens 68 with respect to pinhole card 66 and LED 64. It is also noted that internal support 117 OI housing 24 include apertures 122 along axes 74 to allow passage of the collimated light source from projector 6~.
Still further, Figure 7 illustrates that additional LEDs 124 and 126 (Hewlett-Packard Part ~HLMP-7040 Green tinted, low current) can be positioned on opposite sides of LED 64 in each projector 62. Because LEDs 124 and 126 are basically in thie same plane as LED 64, but are on either side of LED 64, the collimated light beams from these LEDs reaching the patient s eye 58 will cross the optical axis 72 at different angles and distances than the beam from LED 64.
-- Fiq. 8 By referring to Figure 8, a front view of the projector 62 is shown, which reveals the positions of LEDs 64, 124, and 126.

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In the preferred embodiment, LEDs 124 and 126 are green LEDs, whereas LED 64 is red.
-- Fiqs. 9, 10, 11 Figures 9, 10 and 11 show the optical system of the present invention in more isolated fashion. Figure 9 is similar to Figure 3. Figure 11 is similar to Figure 7. Figure 10, however, shows how the imaging device 84 is positioned basically at a 45 angle to optical axis 74. Therefore, its basically rectangular pixel array is also rotated 45 with respect to the optic axis.
Note particularly how lines 140 from LEDs 126 and lines 142 from LEDs 124 in Fig. 11 show how collimated light from the different LEDs will intersect optical axis 72 at different points.
-- Fiq. 12 Figure 12 shows in diagrammatic form the optical system of the present invention including relative distances between components, and the effects of the various optical features on the optical pathways. In particular, Figure 12 illustrates how the collimated light sources 64, 124 and 126 project onto the patient s eye 58.
-- Fiq. 13 Figures 13A-D diagrammatically depict a patient's eye 58.
Eyeball 188 contains a cornea 190 which is generally circular in shape. The preferred embodiment of keratometer 10 imposes four LED collimated light beams 64 onto eye 58. The instrument is calibrated by measuring the position of the reflected images . , . . ~ :: . .
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(200a-d) from each collimated LED light beam using a reference sphere in place of the cornea. This calibration measurement as well as subsequent corneal measurements are made using the CCD
imager an~ its associated telocent:ric objective lens. The spot positions measured by reflection from the cornea and the calibration spot positions are used to compute the corneal curvature along the axis of maximum curvature, the corneal curvature along the axis of minimum curvature, and the angles that each curvature axis makes with respect to horizontal. The measurement can be made using a minimum of three spots. However, accuracy is increased when four spots are used. In addition, when four spots are used the instrument can detect that the corneal surface has a nontoric component of curvature. Figs. 13A
and 13s depict measurement where the spots 200a-d are centered at the center of the cornea for central corneal Keratometer readings. Figs. 13C and 13D show the spots 200a-d off the center of the cornea for peripheral ~eratometer readings.
-- Fiqs. 14A-G
Figure 14A-G depict diagrammatically various situations which can occur wiLh keratometer 10 as seen through eye piece 34.
Figure 14a shows how fixation beam 202 can be projected and housing 24 moved to center it on cornea 190. Fig. 14b illustrates first how LEDs 56 can impose the mire ring 57 of light on eye 58. It also shows that if all LEDs 64, 124 and 126 are turned on, as well as fixation LED 90, the type of pattern .

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that is shown on eye 58 if correctly aligned. It can be seen that red LED 64 spots 200a-d surround fixation LED spot 202.
It can be seen that the red LED's 64 ~orm a pat~ern surrounding the perimeter of the red fixation LED which is generally cenlered along optic axis 72. Note also that the green alignment LED s (spots 201a-d) form a similar pattern on a circle of larger radius, and green alignment LED's (spots 202 a-d) form a similar pattern on a circle of smallex radius.
Fig. 14C indicates keratometer 10 is too close to the patient's eye 58. It indicates that only the o-lter green LED's (spots 201a-d) can be seen and neither the red LED's 64 (spots 200 a-d) nor the inner green LED's (spots 202 a-d) can be seen.
Eig. 14D indicates keratometer 10 is too far from the patient`s eye 58. It indicates that only the inner green LED s (spots 202a-d) can be seen and neither the red LEDs 64 (spots 200a-d) nor outer green LEDs (spots 201a-d) can be seen.
Eig. 14E illustrates fixation point 202 off center.
Eig. 14~ shows when the patient is not fixating on the red fixation LED 202.
Fig. 14G is a depiction of operatlon of keratometer 10 once green and red LED spots have been used to align keratometer 10 with respect to the patient's eye 58 (as shown in ~ig. 14B). In the preferred embodiment, at this point, the control circuitry of keralometer 10 would turn off the green LEDs 124 and 126 (illustrated by "X"'s) leaving only the red LEDs 64 and the center red fixation LED 202.

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-- Fiq. 15 It is to be understood that the camera means would basically capture what corresponds to figures 14A through 14G.
It should be remembered that the basically rectangular matrix of pixel cells of the CCD imager of the camera means is rotated 45 with respect to optical axis 72. The images captured by the camera means therefore are rotated 45 to correspond with the images shown in Figs. 14A-G.
Fig. 15 depicts a centered pattern of red LEDs ready for measurement, corresponding to the pattern as shown in Fig. 14G.
As has previously been explained, the two dimensional capturing of the image of Fig. 15 allows the processor to know the relative distances between the four red spots 200 a-d; in turn allowing it to use algorithms calibration spot position data and mathematical calculations to derive the radii of curvature and axis angles previously explained.
-- Fiq. 16 ~ igs. 16A-lDC set forth a flow chart of the software operational steps of the preferred embodiment of the present invention.
-- Fiq. 17 Figs. 17-24 depict the main electrical circuitry of the preferred embodiment. This circuity exists inside housing 24 primarily on PC board 108.

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Fig. 17 shows block diagram of the two main sections of the circuit board 108 of keratomete.r 10, namely, the main board 302 and an input/output section 304.
-- Fiq. 18 Fig. 18 shows a partial diagrammatic and partial schematic view of the input/output section 304 circuit board 108, including the keyboard section 306 which relates to the control button the LED's of keratometer 10.
Fig. 17 shows that i/o section 304 includes an LCD display 308, the keyboard section 306 and LED outputs 310. Main board 302 includes a DC/DC Converter 312, micro processor 314, image processors 316, and CCD interface 318.
Fig. 18 more specifically shows that i/o section 304 contains the LCD display 308 and the driving circuitry for back light LEDs 320, to back light the LCD display. It also includes LE3 drivers 322 to drive the various LEDs to the system. A
Xeyboard interface 324 allows interaction of the actual keyboards which is 306 (see switches Sl-S15) with the circuitry.
Additionally a ~eeper driver 326 is used to operate a transducer which issues an audible signal to the operator, according to software.
Fig. 18 illustrates the inter connections it would have with other components, for example input/output connections 328 would communicate with the main board 302. Header 330 connects the LED
drivers 322 to the actual LEDs~

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-- Fiq. 20 Fig. 20 shows in block diagram form the contents of the main board 302.
It can be seen how micro processor 314 communicated with image processor 316, which in turn is communicated to CCD
interface 318. Fig. 20 also shows the inner connections of micro processor 314 with i/o section 304 at reference numeral 332.
Headers 334 and 336 comprise the communication between keratometer 10 and base 18. Header 338 communicates the image processor 316 and CCD interface 318 with the CCD imager 84.
-- Fig. 21 Fig. 21 shows in detailed electrical schematic CCD driver section 318 of the main board.
-- Fiq. 22 Fig. 22 shows in detailed electrical schematic the power supply circuit 312 for keratometer 10.
-- Fia. 23 Fig. 23 shows in detailed electrical schematic micro-processor 318 for the main board 318.
-- Fiq. 24 Fig. 24 shows in detailed electrical schematic the image processor circuit 316 of the main board 318.

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To allow a more complete understanding of the preferred embodiment of the invention, below is a detailed description of the electrical circuits previously identified and shown in the drawings, as well as the operation of that circuitry.
-- Fiq.25 Fig. 25 is a general block diagram of the overall circuitry of the preferred embodiment. Reference to Fig. 25 will assist in understanding the sections and interconnection of sections of the circuitry, as well as be a helpful reference when reading the detailed description of the operation of hardware and software, which follows.
-- Fiqs. 26-27 These figures are bloc~ diagrams of the imaging processing parts of the circuitry and will assist in an understanding of this part of the invention.
-- Fias. 28-33 These figures supplement the main electrical schematics and depict ~arious electrical circuits and boards that can be used with the preferred embodiment.
-- Fiqs. 34A-34B
This chart is helpful in understanding the software operation of the preferred embodiment. Figs. 34A and 34B are on a chart which should be read from bottom to top of Fig. 34A and then bottom to top of Fig. 34B.

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-- Fias. 35-38 These electrical schematics show details of the image processing circuitry and should be referenced particularly with Section F entitled "Image Processing Algerithm", and following Section G.
In the following section D, entitled 'IElectronic Circuit Operation", and Section E entitled "Keratometer Operation", references to sheets 1-8 corresponds as follows to Figures 17-24 of the drawings.
SHEET FIGURE

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~ TRODut:~TlON
1.1. Genor~l This document contains a techni~;a~ dcscription o~ the ~lectronic pan oS the ~cra~ometer. Th,e cl~ct~onie r~an of the Kcratome~cr, discusscd in this d,~c~mtn~, inc~ude ~o CirCUil Bc.~rds The 'l~ain ~oard', and ~he 'CCD lma~er Bo~d', bo~h located inside Ihe sarne enrlosurc, and are al-ach_d ~o ei~rl'~ o~her lo form a sin~ie a~s~mbl~c 1.~. Scope This docum~nt con~ains descripdon of the elertrc?l)ic circuils imp]emented on thcse t~ o boards. Thè d~scription relies on the Boar :Is' ~ieh~m:~tics, ~ha~ are alt~ched to this document. The levtl or dEtilils in this docllmenl is sufficienl to undersland the basic nclions and operations of the ~ ralomele.'s boards. _ 1.3. Schematics Structure and Conventlons The schEmancs of Ih~ Main Board are hitr~rchical~ structur~d in ~ s?lle~ts m~Tked ~s sheel I to sh-et ~, The CCD bo~d is confined w ithin onè shee.~. The M~in Boards' schem2tics sheel 1 includes onl~ two sub blocks: IOSEC and ~AIN, that ar~ detfliled on sheets r? and 4 s~_sprclive~. SheEt ? cont~tn some circuils and on~ sub-schematic detailed on sheel 3. The sch^maucs in shEel 4 contltns sub-sch~,matics à_~ailed on sh~e~s i, 6, and 7.
The elecurical COnneCTion betu~en schematic sheeLs is implemented using a lerminal (also calied 'modul~ port'~ design~ed with a uni4ue name, two identical names OT module ports on di~î,,sent schemllics ase connected lo~eLhes. Two identical names ulithin the same schematic sheel are fl150 connec~ed 10g~h~5, bUT h2v~ no meaning oUTsi,~ th~ she~i. For c?;ample, if we loo~ ~?t sheet 1 of the ~lain Board schematic~i, the bloc~ called MAl.~' hav~ S~n inpu~ called 'C.~LIB' which com_s fsom a por~ ca~ in~ the same nam~ in bl~cl; IOS~C, Lhe~e ~ nals ~re connecled loaeL})er. If w~ lool; S!~ shee~ 4 (~vhich con~in th~ comens OI bloc~; MA~7 on shee~ I ), u~e see ~he CALIB inp~l at Ihe top i~ft co~ner, and it is COnneCled 10 ~he MLP blocl; ~ hi^h is funher described in ~heet 6.

MAIN ~OARD SCHE VlATICS DESCRIPT10~1 2 ~. Main Board Sheet 1 She~l 1 cont~ins two sub blocks: TOSFC that consains mainly th~ input I outpu~
functions, and MATN that contains mainl~v Ihe signal processin~ parss OI^ Ihe ~eralometer~;. Both OI t}li~se are fur~her detailed on sh~els ~ and 4 r~sp~cti~ely.
2.2. ~Aain E3oarcl Sheet 2 Sh~et '~ cont~ins Ihe opera~ion31 pushbutton swilches! thc back light LFDs, th~
speaker~ the head~r îor ~he projecIion assembly and ~ modular blocl; of sub-sch~matic on sheets3.

2~7~3~1 '7.~.1. Operation,~-il 5~ i~ches Shcel numb~r 2 cont,qin~ 1~ momenta~ pu,h-butlon tvpc sw ilcher, (deji~na~ed S l, S7, an~, S~ lo Sg) ~ hich we u~ed lo control the I~era~onie~er operalions. Th~st s~dtches are also coliecti\ el~ referrcd to as "the k~ board". ~ hen 2 push bu~on is pressed b~ the usor, on~ of Ihe inpu~s to l}lr ~0 ~JO.~: (n~si~naled ~ hrc)u~h ~7) i~
momenta~ shoned lo ~rour-d 0!10 the \'CC r)ol~nti,~ll d~pen~in~ on ~ sw ilch w irit~
rne swilche~' funelions _re~ d~ d b! ~ e sys~ern ~ofl~-are. Th~ microcontroller,~ avs r~ad:; the slarus o' rall s~ilches, thu~ fun~tional ~ssictnmen~ of th~sc cwilc}les is ~rbi :r,~.
is assj~led b~ ~he micro conuolier, the names, of these s~ ilcl-es arc: Selecl, Scroll, Ci~ar, RiC~ht E~c Lef~ E!~e, and ~ asllre. A mor~ det2ile~ descrip~ion of ~he function~ y of these s~itches ~ b~ pro~ided in Ihe ope.ational ch,~pt~r.
The ~vl~asure s~ eh is arl ~;c~ption. 1~ consis~s of ~ 5~ C}-es, a]l activaied to~ether bs~ a sin~ .. button, and are made of ~hJee groups: S6,S~(),57, and Sl^~ ar~ all atsached to circtlil pon ~i6, 'n~ inform ~he proces ;or lh tt the 1~1easure lie)~ was depressed.
The ~ec()nd group consis~s of S] 11 S9 and S13, and is wires to pon ~7, which provides intemlp~ to the microcon~roller (Sheet ~), need~d to ~ up the microcontrol~er from "siee~p mode", the power s tvin,~. mode. The Ihird group is rhe s\~ ch S~, u hich is wired to the sys~em's _RESET sign,al, lo be, used lo restarl rhe system if il h,as reached a deadlock for un~xpr,cted reasons. To 2void s~ slem xse~ everv rime ~he l\~easure bullon is depressed, S8 is qualified (i.~. r~Ceives r~round porenlial) by S]4 above, rhus on~ if bo~h S]4 (Scroll) and th~ M~2SUJ~ bunon are bolh d~pr~ssed, ~h~ s)~sl~m u~ill T~S~ nd ~il]
~alce pre~eàent of the o~her functions of thEse ~ 5.
Header JP9 The conn~clor-beaàcr 3P~ proYices all of the connections u~ith th~ ~arious LE~s mo~n~d on the opri~,l su~ ass~mbl~ of`the ~e.atomeler. The sicnals ~re desc;ibEd in the follou~in~. table.
Pin ~ am~ I IlO ¦ Descripti()n 1 ! RIG_~ ! - ! Tum o~ ricrh~ proieclionLED
_ ! ~OP _ ' Ou~ ¦ Turn 0~ IOP DroiecLion LED
3 1 I\IlRE I 0~ un ON MirE rinr~
' I BOTr ~ Oui i Turn 0.~' boitom proiection I Fn ' ! LE~rEl - ! ou~ ! Turl~ OnLEO toobser~ el 6 I LEFT ! oul ! Tum 0~ ft Proiuc~ion LEO
I c)nnected Groun~
I Connecled I _ I
! AlM I Ou~ I Turn~ 0~ AIM LED.
1 l ! P3 1 Out J Tums ON th~ four centr ~ t?roiu-c~ion LEDs.
. ~ ~_ I P~ _ I OU! I T ~ns 0~' follr of ~hc non-ccn~ra] DroiecTion LEDs.

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14 I P~ ¦ Out I ~urns 01~' oth~r follr of Ihe non-cen~ral projcction ~ I I LEDs. in conjuncnor. wi1h P2.
TP~]C 1: JP9 connec~ions '.~.3. Bacl;li~,ht LEDs Tne Li,~,hl Emitting Diodes (D1 through D14~ ar~ ph~sic~ loc~1ed behind th~
LCD (Liquid Crystal r)i5pl~)'), and are used ~o illumina~e the displ~ o allo~ rei~din~ in a dirn en\~ironment. Th~ Currenl ~h3~ dnv~s the bacl~ ,h~ LEDts is ~encraLed in sh~et 3, and con~olled b) ~he micro conlToller.
2.~.4. Sp~al;er The spe~ker (LS 1) i5 used for a~dib]e indicalion u iLh IWO a~ailab~t sound pitches. The ~t,enerarion of the si~nals ror Ihe spea};~r is detailed in sheel 3 of ~his board.

2.~. Main E~oard Sheet 3 Sheet ~ contains mosl Or th~ input output funclions of Iht Kcra~orne~er. It cont,~ins the LCD itself, the LCD clrivers, and the LCD con~rasl contlol, lh~ serial load 2nd read cirr~uitry, the push button kc~s read funclion, and ~he sound contTol.
.3.1. I.CD Dri~ers and Display The main ~o~rd conIains two LCD dri~er devices (~J], and U2). These de~ices ar~ lo~ded by th~ micro co,ntroller (see serial load control). The dri~ers pro~ide all the r~,quired sic,n~ls and volta,~s to the LCD (1.~2I~. Th~ voltages 10 the driver (~'LCDl, ~LCD'~, ~nd ~l,CD3) ar~ supplied b~ T~sislor voll:~ce di~id~ rs, and a contr2sl control (VLCD3) Ihat is d~cnbed separatel!~. The LCD c~n b~ resel b~ ~he micTo con~oll~r in pin 1~ of U] and U~. Tne micro COnLToi]er svnchroniz~s its access 10 tbe dri~er b)~
sensing ~he 'busy' line from al~ ~he driv~rs ~Din 11 on the drivers that is driven Io mo~iule 2~rt nam~d '_BVS~'`). Th~ LCD driver requires a clocl~ ~th a freauency of IOO ~Iz~ 2ne du~ dividerUIOprcvidt:s ~his cloc~ b~ di~idina the ~ main cr)~stal oscillator b~ IO
(~iIOA) and theD b5~ 8 (U19B), which provid^ the rtauired di~ision faclor of ~0. The I iquid Cr~ssal Displa)~ consisls of va~iol~s t~isual s~mbols. Th~ micro con2roller can acidress each s~mboI by s~nding a con2rol ~qu_nce ~o ei~hel Ul or U~. adàressing the a~sired s,vmbol. .
2.3.2. Serial L~ad Control Circuitry ~ ne serial load circuil is used 20 load mul2iple regislerS by the micro cont~oll~r, it provides a me~hod of sening con2ro~ v alues with minimum llse of outpu2s fiom the con~olltr. The circuit includes a destina2ion sel~c~or ~13 (left side of Ih~ sheet), which se]ects the device to be conlroll~d b)~ the micro contJoll~r, and loaain~, shift reOisters,U7, U6, and U5. These shif~ regis~ers are Joaded ~ith sever~l bits, each cont~olling tne operation of anotncr device, such a~; LED and spe~;er.

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Thc de~ices to be selte~d b!~ U3 ~lre de~ailed in lable 2. The serial load opera~ion of bits *om the micr(;~ controller includes the following SltpS, Ihe are shown also in ~ ~ -t ~ ~
I) Th~ miero eonLroll~r s~ls th~ elec~' inputs ~)f 1~'3 (s~l(), se'il, and s~ o thr T~quired d~:.clinati~n ~a'iuc (bt~,lwtt:~n 1, ?, (~T 7, s~e ~ibl~ ?), i) Th~ rni.ro eonLroll~r srl Ihe value ao be loadrd on il,c Ol~tpUt pon (modul~ p~
~ 10Sl, nel c~l]ed DATAI)~
3) rne micro conr~ller log~le~ ~ht serial c~ (module pol7 SCI~, nel c~l~ed SERcL~) lo high ~alue and Ihen lo~. This oper~tion c~-iu~e~ the data on Lht`
MOSl line lo be shifled in(o the stlifl rerisler.
~) Sleps '7 and 3 are repeated until all the bils a~re loaded lo ~he ~eleet~d d~viee.
5) The mier~ eontroll~J remo~ e~ the dnTa ~ alu~ from the l~OSI line.
6) Th~ miero eontroll~r sr,ts the seleclor inpuls lo valu~ 0 ~o~ no opi~r~ti(~n.
(~) SELECT ¦ SELEC~T VALUE _ DATA ¦DATA 1 1 DATA 2 ~LC~K

rii ~ e r a m 1 ,: Serial Loa~ Proeess Sai~ps O I Dlsabl~ ! Th- s~r~i! shif~ IDadJrr,ad is *sable,d.
! i LCD d~iver Ul I Defines Lh~ c'iis~l.l~ on Lh~
_ I LCD d~iv~r U ' I Dollnos Lh~ di~sD19V on Lilt LCD
¦ S~d~ch~s R-~d Enable ¦ Allows Lhc micro conuo~lcr Lo sc3n ~he 8 cx~crn~l push ! ! huLLon su~i~hes.
Y ¦ ~ oa~ Swilch~; ~ 'h-n s~ Led, ù e condiùon OL Ihe ~ push bul~n ~ S is ¦ - ! loaded ~ ~hc shifl re~sLcr.
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6 ~iot Used _ 7 ~ra~ome~er conLrols ~nciud~s ~hc conLrasl conuo~, LCD back li~h~ conuol, LCD
reseU cali~ration enab~e, sound control, and ~he projec~or . __ T rDs con~em - T.lhl~ S~ccl lDpUtS 10 th~ D~stin~tion Sel~cl~r .3.3. Push button };eys read function Tnt push bu~ton ke~s fvnctit)n is shown at ~hc bollom left pan o~ shccl 3 (thc k~s z~ ph~sic~liy Cir~tWn in sh~ ). Each of ~he kcys is an inpul ~o an eighl bi~ parallel .
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lo~d shifl r~ist~r (U ). Th micro controllcJ periodic~ re~ds ~he ~ush kut~ons to chcck whe~hcl a b~r~ton was pJ~sscd b) th~ uscr. Thc rc~d op_rauor is a s~ria~ rcsd which is similar lo Ih scr;.al load ^~d includes th ~ollo~in~ st p~:
I ) The micro controllcr scts ~h~ 3 sclrc; irlpuls ol ~ ~ (sc]0 ~c] l and sel ) ~o thc ~ a)uc of 3 hich c2usr Ihc ~ 3 o~ thc sci~c~o~ ) to bccomt acli c (lo~ ). Tnisoperation ]olrl5 Ihe stalt of Llli S~'iLCh~i tO Ihe shifl r~gi~l~r.
i) Tne micro conuol~er rcltas~s ~he conai~ion Or lo~d scrial ~y ~oadin~ 010 lhe Se]~ClOr, 3) Thr micro controlleJ 5~ he scleclor ~o ~lue 4 v~hich ~na~l~s Lhc scTi~ r~d operaLion (relc2~ thc clo~i; inhibil inpu~ of ~hc U~).
~) The mi_ro controliel rcads Ih alue at i~s inpul pon (mo~uie pon MOSO ne~
cal~d D.~TAOI :T).
S) Thc micro conuoll~r IL)~ylcs IhC serial clocl~ (mo~iul~ p t rl SC~ . nct called SERCLK~ lo hih ~Illue ~nd th~n low. This opcralion c~uscs th~ dat~ in thc shi~
T~islcr to muvc on~ cell and lo pres~nt thc ntxl s~ilch un ~h~ ~lOSO linc.
6) S~cps b and c ar~ r~pca~cd ~ times unriJ al] s~itch~s havc b_cn rcad.
7) The micro controll~r s IS thc Selt~C~OI inputs to ~ue 0 IOT no opcralion.
.3.4 LCD Contrast Con~rol Tnc user c~n ch~n~e th- cont~2s; of Ih_ LCD illumina~ion lo achi~ve maximum dis~la~- clarily. Thc change in cont ~st is achicvcd by ch n~ing the volt~c o~ ~ LCD3 (pin ~ij of the LCD dri ~e~s 1~ ! and IJ~. The v2riable volt~ge 10 \ LCD is Sel t-~ the loaàcd bi~s Qa lo Qd in U7. Thes- four bils pro id~ 16 steps of ~onh~su The alut Ih~l is lo~d to Qa Qb Q. and Qd is fcd tO ~ inveners (U~A~ U~B V~C~ and ~g3:)) tha~ ~
f~ing a resislor ne~wcsr~ (R 4 ~3; P~6 and R~7) forrnine 2 b~si. 4 bil D/.~ funclion.
.3~ Sound Control - rne ~ei~tomete; is e~ui~ll^d witr. 2 sm_ll spc~er tO provide auaibl~ incic?tion to thc user. Tne miclo con~oli~ ha;~e ~ bits to cont~ol the audibie ~ -rr.: (1) the so-:nd er.cbic ~hich st2r o_ne.2rion of a _onti~uo~-s tone and ( ) th~ High Pi~h bi- u-hen Ihis bit is s~i the sound is oene.2~ l hian- freouenc~c The ci~cuit con.~ir.s ~ bu.t~_r/
ir. erter US_ 2nd ? ~on' osCiliator (1,19). 1 he tone rle ~uerc ch- n e is acilieved b - chæn in-- th~ tim conslant o. tnt oscill~lo. tnrouah the ci od D2C. Th^ sound is cicliv_red tnrouah a 100 ohm rtsistor to tn_ moduie port o~si~na~^d SP~R thc speakc~
i-s^l~ is drau~n and mention_d on sheel 2 2.4. I~in Board Sheet 4 Shcet numbeJ ~ cont~uns th~ sub-sch~ma~c of .~ )C/DC conv~.~el (d~sc;i~ed in sne_l 5) that pJo ~idt:s mosl o~ the nec ssæ-~ v01l2- ~s used by th- ~cra~omal~; the conneelo~ JP6 (lefl top) is l~sed io. ~2ner~ eonneetion. th~ conneclor J~ is used lo Conneel th~ ~eXlOmet~r ~o its bas~ (expl~ned lal~r). The mi~ro proeessor also referr~d r~s micso eontroli~- ~desenb~d in shcct 8)~ Ih_ im~gc proe~s~or (àeseribèd in shctl 6) 2r d the CCD IrnP~es d~ivers 2r~ ~Iso de~erib~d h~re as sub schcmPIies~ Tt ~ h~r JP7 eonnee-s ~he main board wi~h Ih~ CC~ bo .

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2.4.1. CCD i~ er conn~c~or lb~ CCD ima~reJ cc)nnccto~ (JP7) is d~scribcd in the lab~c 3.
Pins I ?~`ame I 1/() I De~crintiun 1 ¦ C1 l 1n Scri~l CCD D~L2 linc (~ of 3) thal contain Lh~.
I ! piclL~e'~ da 2 l C~ ¦ ln Serial CCD DaL~ line (I of 3) ~hat con~ai~
l I !. piCtur~'s d~La.
3 ¦ C~ ln Serial CCD Dal~ line (l o~ ^.j Lha~ conl~in tne _ I . piclurc`s d~ra.
4 ¦ DPI Out Shift CCD im3~c LO Slora~ a lo~i~t~d on CCD
_ de~i~ bck~ im2F~ area S I D,4B I Ant~-bl~omin~ clo~; to imDJO~ CCD r~rforrn~ncc 6 I DPS ¦ I Shift ima~e from slo~acc alta on CCD lo th~ U-~tp I I r~isLcr.
7 ¦ DS~ ¦ ¦ One of Ihrec phas~; of imaC~ read-cl~; in CCD
l __ I ¦ dvvice.
8 ¦ DS~ I ¦ One of thr~ph~s~s o~ima~e lead-c]oc~n CCD
l ¦ ¦ devict.
g I DS1 ¦ ¦ One of thr~e phascs o~im2~- rcad-rloe,l~ n CCD
~ ice.
1 DT ¦ 7 Push tmG~e ro~ lo thJ~ ph~s~s o~imæ~e snift I _ I ! r~st~r J~ CCD devicc.
~ 7CC~ I 1 5 ~olrs su~]~
1~ I P1'~C ¦ OUI ¦ 1~ Volt~ SUDDi~ _ !3 _ I DAt~ _ ! out I DJA OU~D~ or tn~ CCD thr-~hold (bit 0) 1 ' I DA1 ! OUI ! DlA-ourDuI fo~ til~ CCD tl~sh~ld (tbi~ 1 ) 1~- _I D.~ I Ou~ ! D,/~ OU~DLII for Ih~ CCD thrrshoid (bi~
1~ !DA~ I Ou, ID,'.40llt?ut~o~lh-CCD~h~-sholdrDi!~) I J ! D~__ I Ou. 1 3/A ou;r~u! 'or Ih- CCD Ih~-sholc (bi~
l& I D.~ OUl I D!A our3u~.ro. th~ CCD Ihresnojd (bi~ ~) 1 I DA6 - I Ou~ I D/.~ ourDu~ for th~ CCD Ih~-shold (bii 6) _0 1 3A7 ! ou~ I Dl.~ ou~l~t foT the CCD th-~shold tbil 7 ) _] I ~-7.V I I -7 Volls su~lY
_2 1 ~ollJs d . _ _ TP~]e ~: CCD Imacer Conn~ctor (JP7) Batter~ conneclor Th~ batl_r)~ cor~c~ol (JP6) is us~d lo ConneCI IhC main bo2rd 10 Ih~ b~r~e~
h son~Iwo pir.sfor th~bal~ conn ~tion.
2.4.3. B~se cDnn~ctor -- ~o --, , , , ~ . , :.

. : . ' ~ -:: ~ ., ~ , ~
- :

2~7~5~

r~e base corL~)~c or (JP5) is used lo connccl ~he ~r~tom~L~r to its base. l he ba~e conncclor is dcscribcd in ~ablc 4.
Pins I .~ame ¦ 1!0 ¦ I)escrip~ion ] ~'BASE ¦ _n ! Provid~s v oit~P~ to char~e thr ~erd~o~ b~Lt:
2 SERI~' ln I Scria1 inpul àa;~ line (s~ communi~non shec~
. _ SEROù~ Oul j Serial ourpu~ da:a linr ~s~ s~nal communicati()n __ . I sh~
~ _ G!~D _ I Ground connec~ion T~hlr 4: Basc Conncclor (JP5) 2.5. Main Board Shee~ 5 ShccL numb~r ~ contains the ci~cuit of Lhc powcr supp]!~ thal includes Ihe voltaçe reculators~ thc tr~nsforTn~r, rh~ sY~ ilchinç m~ch~nism ~nd rhc sl~ep-mode con~ol.
2;.1. ~ oltage ~e~t~lator and Trans~orm~r Tne main IC ~na~ is used is Ih~ 'St~ p S~dlchincv Recularor' (V11). The purpoie of this IC is to provic~ an accurate AC sourcc ~or rh- transroImel Tl to ~en_rare Ihc ~arious requiTed vol~cs.The cu~cnl sourc- to th~ pow~r suppl~ is ~he b~tte?~ solrrce (V3AT), Yr~hich is ch !rg-d by volta~e ~)BASE fed rhrou~c~h D35. The inpuls volt2ca-Qi~-s Ull to swil~h tne FE~ Cca~ Qi and een~;2~c ~nc requi~ s4u~e wa~ AC sicvnalo ~e ~ansIormx prim~, sidc.
Tne s~co~ sid~ of Ihe transfo~ ener2les ~he vo~I~ges r-quired b~ vanous ?æ ts of tne ~Cer~lOmet~, some arc switchcd ~nà lurn-d on onl~ durAnD me~sur~mtnt.
Tne tollowinD is 2 list of ~he ~cn~rateà volæces:
.~ame _ I ~ okaoe (~'ol~ Commenls Pl~volts I cont~nuc;l!s~ ~xcep; d~inc Pl~CI -12~olls I s~im~hcd -~ ].~ ~o~s ~ch~d l~ O]LS ! ~u~itched 1~'9~ .5 volts I su~itched VCC ¦ ~5~olts -----T-~
~CCI I T`~'O~S ¦ ccntin~ s, fo~micio ----- ! I con~olieI _ . ~1CC2 _ I ~ volIs _¦ s~ ched ~: Vol~2g~s Gcnera~^d bv th~ DC to DC ConvcrLor 2.5 2. Power Suppl~ Re~ lati~n ' ~ '; ':

2~ 7~

n~e powcr 5uF~p~y rc~ul.ition is achiev~d t~ scnsinea iht VCC~ anc' lecdine i1 back ~o the re~7ula1or to pin \'~B (pin 7) of Id l l . Ir ~!CC is loo hi,~,h, ~h~ in~ of QS s~ops momenL~ri]~, unùl ~'CC r~lurns o Ihe d~sired level. ~1~ o.her vol~aecs arc also ~e~ulal~d inairccri~ Lh~ virtu~ of bcing ~ed fTom Ihc samc c.lnsformer rl 25 Lht rt~U~alt~d VCC
uindin~. ~hi s te_hniqu~ i5 u~c~ ~o ensurc Lhal al~ ~h~ vol~ecs ~ bc sct accur fo~lou inr Lhis ~ ol~a~c.
~,~,3. ~u jtchin,~ hnnislTLs.
Al1 tt1~ ~!o~a~es eener31ed ~ he con~ener can be shul off b~ ~}~e microproccssorUiLh Lhe 'siccp' in~u~ (bor~om lefl corner). This rnode is uscd durin~ ~ 1on~ p_riod o' nc)n operaLin~ rime. ln slecr mode, Irmsislor Qfi becomes high impcdanc~. lifrin R49 Irom ~round and causing th~ rc,~ul~or IJl I ~o s~op Lirivin~ QS~ ~hus ~hc cansform~r Tl is ina_rivc. The rnicroconcoll~r ncedri ~' supp~! e~en durin,~ alecp~ Ihus a p~>wcr line ~'CCl is fccdin~ the micro t:onLrollcr al~ a~ s. VCCl is conn~c~e~ ~o V~AT ~ia D42 u~nich tnsur~s powcr kvcl u~hen ~CC is ~tro.
~ s sho~ n in the ~bo~ able, al~ rhe. vollaes lo Ihc CCD lm2~1er can be swiuh~d off, thesc VOI~LgCS n~ ncccied for 2 shon pcriod o~ timc àuring rncasu~mcrlt on~Suilchinc tnc volta~7ts is pcrfo.med b~ Ihc PB line (~vp lef~ co.~-r) ~hat is ~neraltd by ~he L-na~7e Processo, Pnc s~a~s ac~ivc (hicn) du-in~, Ihe whole m~asurcmcnt cycle. Urn~n P~ iâ active, ~c_nsislor Q is ~urn-d or" u~hich ~-ns on ~ansis~or Q7, ~ha~ ra~ns on shc ' 12 VOl!S tO ~he ~m~.~ger. 7'his 12 VOI!S linc is ;~âO conneclcd lo thc ga~e of Ql3, ~hat lurns `: on il~ 1~ voJts, ând to the gate of Ql 1 th~t pulls dou~n terminal number S of thc transformcr Tl Iha~ causcs the n gative volr2R~,s -7 ,~nd - 9.~ vol~s ~o b~casn~ ac~
~CC~ which is th^ ~l~o"T . ~ VOlLâ ~:uppl~ (ai hc botlom nhl co~ncr) is also controlled b~ tbc 12 vo~ts tha~ acti~ z~es rhe gate of Q~.
Batter~ Monitor.
1-- the Ke-atomel~. is ove. ~sed ~ ithou~ ch7~ ba~ m~ d ain lo ai~nosi ze-o vol~. Thr lo~c a'' ~e of th~ ci~cui~ is unl~no~ r.~ ând i5 ii~ V to include c high-^~~.,nt consumprion mo.~e, such 2a R--S~I. This uili pre iude charc~ir.g the battc~
si;l^e rnosr of th_ Ch2rRing CU5~ be ronsurn~d b~ th~ circuit. I o avoid this e~ent, a ba~ moni,o.~ 1.,''2~ ic ?roviti-d. 1~ fD.C~S SL----? mo~1~ o~ r~ttcr~ ~o!._g~ go_s belo~
~', and has h~stercsis ri~ m,~r..ains sl~ep unlil ba~ has rea~h~d at ieas~ ~.3V.
.6. h~ain Board Sheet 6 Shcc~ ~ con~ins L~' main crvs~ os^illato2, tne image proctâsor anr; th~ rdndom accDss mDmos~ tn~ is ~s-d b~ t~ micro conso!l~r ~nd the imaRe pIOCCââOI.
2 6.1. G~s~ scillator Tn~ ~ l~lz cr~sta~ oscill2~02 (IJl~), t:q2 se~veâ botn Ihe image pro~,~ssor~ and th~
- 7 C3 ciocl: (d~s~ri~ed orl snee~ 3).
2,6.2. Ima"~ Pro~e~or Thcimâ~e prOCCSâOr ~U~2) iâ a fit~d prorzmmabl~.at~ ærrav ACrEL lO~0.
~ne con~en~ of ~h- irna ~ proocssor 2nd ~hc pro^cssing aigo~iLhm &r_ dS~aCllb-`d ' 1 ~ t ~ r _ 9~ _ 2~7~

The imP.~e proccssor s Icft side is basic~l3~ conneclcd lo Ihc micro proc~ssor with dat~ lines ~ldarcss lin~s and control~ thcse arc describcd with ~omt morc ~t~il~ in Lht~ micrD pr(,>~ts~or sCcion (shec~ ~). The irna~ prccessor grn~rdl~s al3 thc necessar~ ~iminC si nals to ~ht CCD (rirh~ bollom o~ U~). and rccci~es t~lc 3 serial inpuls ci~ and C3 th~ ac~u~3~ con-ain~ Ihe tlieil~l d~scripLion o~ th~ pic~urc.
Ihe sienaJs ~hal are ecnerated by thc im2 ~r processo ~nd arc uscc3 to drive t~eCCD ~ ia dri~ crs (Shccl 7) a!. foliou s:
~n 1 ABI3~ Anti-Bk)omin~ C~oc~
Pl ~ lmaF~r cloc3i PS _ I Sto-a~c Clo_3; __ T I rransrrrGa~ Cloc~:
GT_ i Ver~ica3 Rctrace S ] ~S2.S3 ! Seria.] Ima~e Jtad Ciocks PB I Power 01~ ~id-o cLrcuitr~

Thr. sign2~s ariving ~hc CCD GivtrS
2.6.3. Random Access ~lemor~
~ e imPo~ processor is 2~So connec~ o a R2ndom Acc ss Mcmor~ ) thz~
contains ~g by~cs o data. D~ine~ no~rn~l opcrauon~ ~he imagc proc~ssinC funcuon o~ thc imzg^ pro~essor is disabled and the micro conrroller c an access ~nc ~K b~es memory.
31~ring m~zsurem^Dt thar rcqu~rcs ca7~)~u inC of a picture Ihe im2ge prc~ssor t~l;es pnorin~ on the memDr~ and ur~cs unt pro^css^d im~nc data lo ~he mcmorS~. Ar thc end of uh- m-æsurerncnt~ ~he ima~e processor becomes inac~ive ag_in, 2nd tbe .~DtuJed dat2 in the merno~ is av2il~bl- to the ~nie~o conrroller.
.6.~ ibration Pro~isions 3uing ca~!Dr2tion o~ rhe CC~ ~s p~r~ o~ tht m~nu. ~c;urin~ pro_css, il is nec^ssarv lo b2ve a mernon~ tha~ is larg-r Lrl2n thc m mor~ p.o~id~ on boqrd. Fo. ~he ccIiD~arion pro_~ss, 2 speciPl IC cliD is ho~lced on tOp of the rn^morv d~vi^~ (111~), and connects to P spe~l bo~rd ~nat con~ains control ci.-cuit ~nd 6~ R~ . Pin numbè~ 1 Or Ui~ ~nicn is usua!l~ nD~ connecred ar- used bv thc micro con~rolltr lo clear ulecalibra~on conr. o] circuir. The calib:~rioD clip connects Din -~2 ~v~ rhc on b~ard ~AM
(Ul.~) tO ~round to disable the on bo2la memo;y chip. Dur nc ~hv c~libr~rion proress, Ihe micro con~olltr turns rhc irna~e proc_ssor also to i~s c21ib. alion mod~ and ~he d2ta .~pIure~ auTing tnes~ m~surements is ]oad~d to rhe Pvx~ern~l memo~-~ insIead of ~h~v on b~v2~d memo~ e~ ~he mePsu~vmenl, the micro conrrollel c2n r^sel c~;tem21 mcmo~ control and can r-ad al~ the~ ex~erno11~ stor~d dz~a in s~oucn~ia~ o.-dtn 2.~. Main Board Sheet 7 Shcet n~mbe~ 7 con~Lins th~ drivers lo thc CCI) imhccr, ~nd t~ ~ CC D v~llagc a~jus~ 5.

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2 ~ 7 ~

7.7.1. CCD Irrla~er Dri-~rs The CL'CUit cont~ins l~o sp~cific uc~iccs thal ar~ lailor~cl to fLrivc the Kcrztomcl~r~ CCD ima~er ~he pa~lcl ~jvcr (Ul:5) trans~at~ Ihé p~-~J~ nc pub.cs t -al dnvc thr CCD lo ar. ~o~7 ~olla 7es DAB DPI and DPS Ihal arc re4uircd h! t~-e CCD
s~ecif~c2r 0n~.
n-e se~ia] d.~ r (U~6) dri~es Ihc cio~;s ~ha- ~re pushint~ Lhc picture inlo thc scria] cl~ta 7in_s for re~àOUl. ~ 7ivin ~ si~rn~ls th~l cnler 7hc ~fl sid~ of th~ shett ar~
~eneraled b!~ thc im2~ p~ oc~s7o~ ~nd dcscribcd alonc ~itl) th~ i7nacc pJo~cssordescripuon ~n sht~; ~
'.7.~. CCD Im~er 701~at7e AdjusLJn~nt ~ hcrc 2r. 3 adjus~7rnent polcntiomtttrs thal sel the voi~agcs ~o th~ er V1~
du.in proJucion of tht ~er~tomc~ler in order to match the pcr~orrnance to thc sp~cir~c CCD that i5 insullc~ in Ihc ~ralomcl_r.
2.~. M~in Board Sheet ~
She ~ ~ cont.Jins the micro con7roll-r (U~n). tne nddress L~lch (lJi7) Ihe pro~2m memor~ ~19) thc D/A l.~tch (Ul~) an~ opLon.l~ 1 Il seri~l comrnl~nicsuon channel (JP8 and JP13).
'.8.1. Micro Controllf r ~ ne micro COI~Foli~r is Motolol 68~CI I u~hicn includ~s Ihe foIlowin l b~ic chæ-2cle~:istics:
';~'' bvtos R~
L~!? Byles ~ -~?~OM ( l~c- ic.l Ily Er- s2bi~ Re~.d O~ Memo~,~) Adcress D2-. and I/O lORTS e~io~ in acc~ss to ~x~rral memor~e ~ L.n2~Po~s ~i nint~ a! A/l:) Converl~r ContTo!s , .
r~e b2sic c~ock os.il!~tor is gen~ ret-d insid^ the rr.iclo conLrol~er usin L~
ex~ n~ .2 ~z CrVSI~ (Yl). rne miclo conrroll~ r can be resel ext~nall~ b~- the _R~S~T iine this JtS-t caus_s ~ COmpl~l~ ir~i~ ization of Lhe micro cont~oller as af~er pow-r ~p.
T~e fol~owirJa is a lis; o~ 21~ lhe c~:t~Lnal porls of th~ micro proctssor and their us_s ~n- 1;st of po~s c;~n ~ivc thc r~ad~r 2 b~rter uno~rs~andin~ of th~ avei~le con~ol anc s;alus. So;n~ of Ih~sc lines art explained on th- shcels wh~re us~

:' , ' , ':,.
;' ~

.,,. , : , 2~7~5~l . .
I .~ame 1/O D~scriplion Port l _----PA() i CF~ I I unuscd _ _ PAl ¦ h~D ¦ Inpu~ ¦ Scnse scrilll in aclivit! lo rc~d p in~
. . . ! I rvaues~ ~rom ba!;~
PA'` ! B~,'S~ n~u~ oni~oJ rv~ ess o~ L,CD dri~crs PA3 SeJee~0 Ou~pul The selPvrl lines ar~ us~d to contro~ whJ~h de~ ic is ,~. c~ssed ~) ~he s~ria~ load / r~ad mcchanism (e~:pl~in~d in d~tail~ in sh~
4) P~4 Sciec~] Outpul The selvct lin~s ar~ us~d ~o contTDI which de~ic~ is accts~;~d by tbc scnal load / rc~d mechanism (cxplaincd in dct~ils in shee~
__ . 4 ).
PA~ Sv~ OUIPU~ Thc scicct ]in-s arc used ~o control which de~icc is acccsscd bS~ thc 5erial load / r~vad . mcrhanism (cxplaine~ in ~e~ils in sh~et ) .
PA6 !PWM

PB0 - h~0- Outpul This Porl con~ains the~ ~ higher bits of Ihe PB7 M~7 16 available addrcss bils supporLed bv ~he _ micro conlro~le~.
PCO - D0 D7 anà Input / This port is mullipic~vd bcl~een the PC7 M,4L0 - OUIPUI lo~ bils of ~hc acid~ess bus and the MAl 7 a~,a bus (sve d~scripnon un~r Adàr~,ss L21rh) P~O ~ D ¦ lnput ¦ Se,ialU.~Trecei~elinc(ae~ilsinsh~t ! I l) DDl i ~"TX~ ¦ O"lpu; I S~ ART ransmit linr ~de~ils in P3~ MOSl lnpul Del-ln~d zs ~ inpul lo sample rho se-i~
reaa of the pL!sh bul-on s~Ai~h-s (Q~l~ils . .. . . . in tn~v chapt~r of the seri~l rvAd m~hanism sh~t . ) PD~ MOSO Outpu~ Defined ~s an ou~pu~ and used for u~e sev;ial ~oa~ a~a (d_~2i!s in the sv~i21 loo.d con~o] sheel ~) PDI SC~ OUIPUt Serial clccl; used b~ the seri~ loac and r~vad corltTol (~vt~ls in thv chapl~I of Ihe .. . senal read mechanism~ sheel 4) P S I SS I_ _ I

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~7~

¦ PD6 ¦ E ¦ Oulpul ¦ Con~inuous clorl~ frorn thè micro con~ollcr Ih~t ~imes ~he read / wr~le ¦ PD7 ~ ASI Outpul I Conrroi Si~na~ u~td l0 12Lch Lhc ~ou~tr adàr~ss lincs u~ith an ex~rna] i~h (see Ad~css Lalch dcscnDI~on cO I- ! Innu~ l Analor rnonilo~n~ of 12\! vt)ltae _ P~2 1l lnr~ut ! ~n~klE moniloinr o~ vo~laee P~- r - 1~ L I ~na~Or mOn;lOrinC O~ O]L2 _ ~ In~ Ana~o~ monilorin~ f ~ vo~La~
l I lnpuL I Ana~or rnOnilOrin~ of base v0]~2~C can _ _ I I indic2~è if k~ralomclcr D]u~r~d lo b~se PE I Inpul ¦ Analoc monilOring of batlcr~ volt~c PE~i _ -- ! lnpul I unused P~ n~U~ ~ ! unused Ta~-~ ?: Micro Controli_l Input / OUIPUI Pons '.8.2. Adclress Lalch Thc micro coDtro]lcr drives Ihe S lowcr bi~s (MAL() lo MAL7~ of ~h~ addres~ on the s2me lines Wi;h Ibe d~;2 bu~ DO ~o D7. ~Ih-n Ihc address lin~s are d~iven oul (on ~h~
lines d_signal~d s DO lo D~ in U~O) the mic~o contr~ r l~lso activa~s the AS si~nal ~I)in 4 of U~O) that cause Ihi~ da~ ~o b~ latched inl(~ ihe addscss lalch 1~ hen th~
control3cr can send d2;a on the d2ta lines lo ~he oesir~d ad~ess or r~cciv~ da~a throu h tnesc ]ines.
.8.3. I~ain Pr~gr2m l~lremor~
Tnc main pro~T.~rn memo~5~ i5 a 6~ b~tos . rasable Re~ Onlv ~cmorv EPROM

9). ~nis m~mor is conneered ci~ to L~- mi.ro comro!i~r and acc-ssed sole~ b~
r;he co.~;roI]~ 1ost o. Ih~ ~er2Tomeler so~ e is slored in this r~P~OI~
.~.4. DIA L ~ch Tnis lalch (~I~) is uscd ~() ho~d tn. ~ e o' Lh~ DiA Ih21 con~rol tbc CCD
Lr~re~hDlc Tne kLcb is corinect~;d lo ~n~ micro conlrolltr d~la b~s ~nd loaded hv z si~nal c!oco~_d in Ihe irnag_ processor, c211_d DAE3~T (mo.~ d-.~ls in Ihc CCD bo~rd.
d~s~p~on).
.8.~. TTL Serial Communication T~e sc~i21 co;nmunication iincs lo rccei~e and rransmil are norrnall~ roul_d lo Ihe convcno~ ~:xpl2in~d in she~t I), howevt:r. du:ing calibration or lest, mc maT~:a-turc~ c~ cc>nneci 2 Tn, seri~LI conn~C1ion Ihrough th~ he~ders JP~. JP13 is a 3ump~ lo Sët ~he se.i.al inpul. lf the dara source is ~ ~L ~ve3 si~n~L Ihe jump-r conn~c~s pins I~'', if rhe source is ~n exler,.al RS-232 signal, ~he~umPcr connec~s pins '~-:~ , ,. ' ~ , . ' , ' , . ~ :

2~7~5~ -_ ~D IMAGFF~ BOARD S~C~,E,~1hTI~!~; DESCRIPTIQN
~he CCD l~na~cr Board is loc~lc~ al ~hc tOp Or the ~;cratome~er7 il contains theCCD irn~cr d~ icc Lhe anslo~ amp]ifiers of th~ ~hrcc vidto chann~-ls. uht Lhr~shold circuit and the D/A Iht ~ SCLS tht sensitivit ~ levcl of Ih~ compar2~0rs.
3.1. Connectlon Header Th. ciectrical connection of lil~ imrlEer boa~d to lhe main bo.lrd is il~nd~_d Llrou~h Ihe head~r . ~ op i ft). This h~adcr is d~ led in ~heet numbcr 5. The ~round conntclion lo lh bulrd is Conn~ cted lhrou~h a separalt ji~e~; (~1) 3.2. The CCD Imag~r T~ irna~ r (U]) is the basic tiement of a idco ca-ntra il l~rv~idcs ~ fulJ picLure o~lhc reflcclcd lieht source ~l~routh L~e mcasurcd lens. The. ima~t re~ull ~ hich is tho ~ntcnsit~ of t~ch of Ih ima~er s^ns~ points is sllif~ed oul o~ the dt ~ ice ~rvu ~h tl~c outpuls ~O1 ~ 0~ and ~03. Th^se seria~ Iints ~rc acLual]!~ analog si~nals Lh~t represenl Lhc in~ns1t~ of cach pixel. Th_ s_ria] ~nalo~ out~ut froln Lhe im3ge. is amplified C?~ tha oporationa] ~rnp~if~ers U~ VG and V7 b~ a ~ctor ol ~boui ~ U, and then comDarcd lo a threshoid ~21ue b!~ tb- cornparalors U~A V4B ~nd V4C. For e~ch comPaA-alor i~ Lh~
arnp~ avd si~na~ ar the inpu~ lo Ine comp~rator (pin 1) is Jo.~_r than Lh~ Lhreshoid YalUe in pin ~ the output ol Lhe comp& alOr is ne~alive which means Lhat 2 t. ue si,~n21 ~as ~t~t_d.
3 3. Thresh~ld l)IA:
- lne threshoid i5 needed to a(ljl!s~ the s~nsiti~it~ o~ lhe re2ding ~ith r~E~rd to the specif1c ima er and ~he arnDien~ liEht condiùons. Th~ Kcralom-~Ar is adiustinc ~his valu aulomaticalIy. r~e lhresnold is a ùi~i~zl voltae~ lhat is nene.aled b~ the Digi~2~ ro f~n2~0 ~onvener (U~). The i~put ~o th^ convt-t~ is à 7 bi~ ~o~à from 2 12lCh (tlesC~iDe,~ in sheet es~ 7 DllS con~rol ~he outp~lt ana~or volt~ ~- in pin ~ of thc D/.~..
.Yollage reguJ~tor lne ~0~;2 e rt~ ulatoI (U~ ?.~ tl~_ botlom of Ihe D~e) is res~onsi' l~ tor rt "ulating tL~ n~ 72~ve VOILS IOr the ?~nplifAe.s and t;~_ co.-nparaiors i~ usts lhe nec2-iv~ olts 3 5 SO~

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2~79~1 E. i ~h~OMETE~ orE~ 10~;
1. IN~RC)DU~Tlt:)N
1.1. Genoral This ~ocumen~ describ~s ~l~ op^ralion of the K_Jatorne~er Circuit. Th~ reader mus~ be rarniliar uith Ihe circllit d~scriplion ~ li]ab]e p r e i ~u s I ~ . This docum_n~ ma~es direc~ r~fercnces ~o th~ }~era~oJr)eler and CCD Boards scl-ema~ics pa~es described in the circuit d~scription docum~l-t. ( S e c t i o n D ) 1.~. Scope ThP or)eration of th~ Ker~ome~er is contJoll~l b~ ~he sOr~w~Te residing in ~he EPR0~1 and b~ th~ har(~are exec~1~in~ il. rhis docuIncm descri~es Lhe hardware operation~ b~ means Or ~xamples.

~tartvp De~ ript_on When ~he batleries are first att~ched to tl~e Kers~ome~er ~ po~er-on resP~t occurs. The Vollàge Tecul~or lll I sheet 5 det~c~s k~w ~olta~e at pin 1 LBI since C50 is not ch~rged yet. This triggers pin 2 LBO of U11 ~o rese~ tho circuit. The micro controller U?O on Sh_l 8 senses the resel ~It pin 17 and ~oes ~o reset mode u~hich includes seL~ing all microcontroller s 1/0 ports as inputs. This includes IIO PA7 (pin 27) which conrrols sleep mo~e.
Since pin ~7 ~J20 is in input rric~de the signa~ _MSL~EP (top n-~h~ of sheet 8) is pulled HIGH by resislor R89 which commands the ~-s~em lo w~;e l~p. The signal _MSLEEP
- arrives in sh~t ~ where il c~uses U 1 l to operate a gain creating ~'CC ~d Pl2V
voltages. Th_ VCC ~oltag~ is sL~ppli_d to most of th~ Ker~tometPr locic including Ihe pro~am EPROI~ Ul9~
~ow? that th_re is po~er the rnicr~ontroller is able lo execu~e code from the EPROM.
Tnis co~ie (soft~are) initializes all desired recisl~rs in ~he s~s~em perforrns self lest e~c.
Exarnple of the self ~es~ is the reading of vol~aces aL the PE1 thru P~ porLS (U20) and ~e.-iS ing Lhat all of Lhese volla~e5 are within acceptable rango. At the end of this rese peri~d tho microconr~oller ~ its for ~scr s reyuests from the ke\~board and if none exisls i~ eXeCUleS Lhe sleep rouLine which forces U?O pin ~7 _SLEEP ~o become LOW
and tums off all powcr~ except ~>r VCCl for 7he microconlrolier iLself.

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3. M~surement Oporatipn Descri~ion Assumin~ Ihat the E~eraaometor i~ in sieep mod~ . ~rh~n the Measure ke~ is . depressed (sbeet 2) a u~ake up siona~ _WA~iEVP is prop~-7ated vi~ sheet 3 and 4 ~o si_nal LCD 9-pin lg of U20 which indic~Les Lo ~he micsoconLroller lo res~me norrnal opo.a~ion. Pin PA7 _SLEEP is turned ON7 ~hich causes acLi-a~ion of Lhe DC/DC
converL r as describe~ above. The m;erocontroIlcl s sof~ware nou polls the keyboard opcra.~on lo u~ait for ~s~ s kG~s~ Suppo~;e tha~ the user presses ~hc RIGHT ~ E ~icy on t 2~7~5~

sh^-l 2. The si~nal ~4 ~ocs HlG~I, Icadin~ lo U~' a~ the bottom l~t of ~:hcct 3. The mi~roprooessor ou~puts a scri ~I cio^~ ~ ia pin PD-~ (1,''0 Shcct ~)~ u hich rcaohts ~
causin~ it to shift ~1] ci~ ht bits ~o th~ linc D~TAO~ T~ al~c caIlcd MlSO, u hich rcachcs the mioropro_csso.'s sèria] port PD ~-in ~. Th~ mi-ropro~s~or s~Gds thi~ b!ne~ ~nd th~
~Jc-r~ram detcc~s G HIGH in Ihr t)il ~ Dsition J~laLed lo RIGI ;T E~'E. ~his c:~uses th~
prorr~q2m to u~dale i~s c~n~cn~ in^luLunr upd2:inD ù)c LCD di~p!a! lo sho~ th~ ~mbo1 o' ~ n~hl e!~t. Thi~; displ~a\ upà;~lr is donc b~ sctline 1hr SEU~ thru SEL si~n~ls on pa~c (~ominr from Ihe miLro~ont~oller) near l,~ to bin3~ causin~ pin jL~ of U ~) 10 ~D LO~ an~ thu~; s~lec!in~ th~ ~CD d:i~c{. !io~ a Sequen~c of bits arri-~e~ fror.) lhc micro~onr~oller ~ i~ ti~e .~11SO lin~, which is ~A ritt~l) inlo U1. This bit strr~ incil~drs th~
~?propria~e command lo lurn O~' ~h~ LCD sc~mcnt on l_~i tha~ shows ~ n~ht r!~c s~m~o! ln adLlition, Ih~ ~ser rets a~l audibk b~cp to indicale lhal Ihe I e~ ha~ t~een rta~.
Tnis is donc b~ sendin~ ~ similar s ,ia] bit str~;~m lo Ihc shill rer~istcrs, comprisinr~ U
116, ~nd US, and sctLin,~ _SOUi~'D pin ~ Or l~7 1,0~ hich ac~ Ales Lhc sound ~ia 1 and U9, bDth al lhe top l~ft corncr of shcct ;. A~l of the olhe- bits Or U7~1J6, and l,'S ar~
,~so updatcd, bu~ since thert is no need to changc ~h~rn nou, the sof~ re ~nsule~ ~h.~ thc biL strcatn s~nt to them is id_n~ical to their prE~ ious Sl;~C, ?nd onl~ Ih~ sound is ac~ivatcd.
Af~vor brief period, ~otheT hit stlc:lm is scnt. this time to tuTn th sound QFF, so that onl~ ~ shoTi b~p is hcaId betwe~n th-sc two shi~t renist~r updales.
rn~ use. l~c^ps DTessing va~ious buLtons, causin~ Ihe pro~T~tm lo respond ~s D-~ae,d. EYentu2~ , the Mv2sure I~PY ma~ a~prcss~d, t:~u~inG Lhe st2n Or, m~suJ~m~nt pro_ss~
~ 'nen st ~ng th~, m^asur_mcnt proc~ss, th_ mocro conlTo!lel wrttcs to the im~
~r~csso~lJl'~ sh~-l 6~ v~hich is acr^sscd as a mvmor~ ~d~r-ss. lnside the im~P
t~ sso- th~r^ ?r~~ renisl::rs us^d for csrnm?ndlincuc2tion hæn~sh~l;c~ h th~
~ioro_3:ltrolie-. The snicrocont~oll_l u it~s tt~o co nm~nd io on: of thes^ registers lo r~n n~. pOW' ON~ u~hich SIS Ih sinnal P~ IJ17 pin3, Elrri~in~, on top let^l o, sh-et 5, ~hich u~s O!~; o!l pou~er sL~p~lies. At ~i5 ~irne~ th~ im2g~ processo~ ou~puts also ~11 shc c~rio~ic si~rn?ls nc_~ss~-~ to ~c~d ~he ~ o imag~, su^h ~5 Pl, PS, GT el^. and Ihe CCD
d is fu~ a~ e.Afl_s ~h. ~oit~c-s h~c s_ltled~ Ih_ mic~oproc~sso. s~cs 2 bi-s--eæ~n lo Ihe se~is~- U ~U3~ .S àiscuss-c`. aDo~e~ bu~ -.his time Ihe d~s*ed comDin_ion o~ proj~^tion 1 3s, iev-l :~nC rnile. 2~ lu~n_d 0~. Tn~ us~- Slt~ to ~ n tn_ ~e.a~om_ler n~ar Ihe pa~cnt~s c~ he mi--ooontToll-l ~rrit_s ;1 "~D irn2ne"
corr~and to the im20C pro~sso-. T hc im~_ pro~essor ~r~bs imaoes b~ Teaoing thc inT~u~,s Cl,C'',C~ (pins 6~ ,6~ Ul') sh~ l 6), ~:nd rlms thc in~crr~ buill imaocprocessino alco-ithm, discusscd in 2 S~'p -~ ciocumcnt. As US~IUI vi~co infoTma;ion is ~ie~ct_d, ~n^ im2g~ T-rocessor ~sit-s this ir~o ~m~lion lo Ihe imaoc RAM~ U 12 shcet 6.
Tnis inforrna~ion Tt;at-S lO thc lo^~tion and si~es of liVhl spo~s a~ d. ~'hen z full ~ideo fram^ Pro~rssin~ is cornDl~,~t, Ihe, im2~ ~ pro_essOJ indicat-s comt)iction SI~IUS ~ly chna~ein~ 2 bit in an inlem~ s;a~us st_ist"T, w nich is pvlled ~ th- micro comrollcT. Thc micr~con~roll~S now c~n read ~h~ RAlv~ ~ia the im~ce pro~esso-~ which acts at this ume me~ ' S 2 s~ilch~ t:onnecting Ine rnicror)To_cssor adclress anG dat~ buss_s ~lh ~h~
imo~c R~M busscs. Th~ ~AM is also used b) Ihe micro conlroller lo slore infonnation n~d~d iOI its pro,~mS, in m~mor~ ar~2s n~t used ~urrenu~ ior im2gt vrab~in". To , ': ' :
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2~79~1 assis; this ~pa~ation bclwcen inio-malion t)~peS, LhC ~AJ~ is ~rran~cd ~s ~ou~ ~,rcs of 2~ b!~tcs each, o~ hich oni~ on~ pa~e a~ 2 timr is ~scd for Ih~ ima~e ~rabbinc Tnt micrc- contro~Jcr Can sc! im2~.r p,oces~o. re~isl~rs ~ha; ~ ilJ lorc~ o slore L~IC ne irna~s at ~Ln!~ of thosc p~es, l~a~dnc t~)e olhcr three ~or e~nera] pur~cse slor~r~e.
cr an irn~e is ~rabbed anc proct~d h~ Ihe microconrro~l~,'s sofl~are, Lne mi^rocontrolier n~2! d-cid~ lo charl,~e 11~ ~ddeo Ihresl)okl lo ëcl 2 b~ r imaëc, which is ~one L~ ~itin~ lo Ih~ da~a ~lc}) L,!~, uhich is enabi~ onl~ b! u~riLin~ lo ~a{ircs5 ~80 h~ his ao(iress bein~ ùecod~ù inlern~ll) b!~ th~ im~ proctsso., u hich ou~uLs Int si~n~ _D~EN. ~ hich is ~cti\~c ~ h (slloll]d bc calJ~I DArN ), l~adin~ lo Ihe lalch U ] ~
pin i ]. rne D/A combinalion e\~n~ r.;~che~; Ihe CCV Bo;~d. ch~ncin~ Lhe lilr~sho]d.
The microconLr()Jiel a~S~ ChtCI~s ~0. imq,~e CCnl~rin~' and indicales corr~c~
posiLionin b~ ~n Du~iible lon~. Once s~ab~E readincs ~e r~d, IJ)- micr~onuol~r L~ ES
m-asuremen~, u~hich me3ns tun~inC OFF ~h~ mire Jincs and p~npheral proj~clion LEDs, and lurrLine~ ON onl~ th~ ~our cenlr~l proj~clion T EDs, ;~11 o~ ~he ~bo~c optr~lions are t one b~ modi~inE Ihe eonlel)t of Ihc shifl Tegisl~r ~7.U6~V5. l\~o~ Ih~ lasl imaC~ is ~abbt~ l~s conlcnl is pro_~ssed 2n~ lh~ d~sir~d corn~ p~r~rn~lvrs are c~lculaleù an~
disp12!~_d on ~hc LCD. Al Ih pro~sn~'s discJ~lion, s~eral such m~asur~m~nls can b~
t~];en, to averaC~e oul e rors. Th micro_onuoller r~lurns to L~e~ bo~Jd po]iin,C, rouli~e unli]
2notner ~e~ ~pression is reqd, o~ non_ fc~ u Ie~ momen~s, re~url) ~o S]t"p rnoàe.

~. Other ~pera~ions 3~no~ reader is fami~r ~ n Ll~e D~inci?le o~op~-~tion o~he CirCuil. Gen~ t tne rnic~orontrolle~r ~IS~S its La~ address bus LO ~ccess ~h~ ~r`PRo~ IO. P. o~r2m ir.s, u~;io~s, tne im2~ DrOC-ssOI ~o~ commanc~, SIZ~I~S~ 2nd RA~1 re~iin,~,. and l!sing s~r s~l po~ il cxn mo ~ tne s_;tinn o^ ~.n~ L ~3, me LCD, the spe~ r~ ~d r~qd rn~
ke~Joard. Th_ 2CIU?1 s ~?U_nce of ;~ oT7 r_~ion is thl!s simil~r ~o ti~ pr~sses àescribed abo~ ~2ere~r. ~il~ r,i^.r~_on~rol~e~, ~na-rp.ot~læm conaro!. ~_c~sses ~ne d-sir~d c~_vice, 2~7 F . ~mage Processing Algori~hm 1,_ Intr~du~licn ~ ccthatp~
by ~h5 Cc~ i~lla ~vl located a~ ~hc ~op of ~h~ Lens~me~c..

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~ n~ CCD im~e- c~n sc~n ar. erlr~ picure ~h21 co3t~ins ~u~o ,~e3~s: ~e I`~SI field _ r , ~ . . ~ : .

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r~

. f,,",~x ~v~

CCD r~

1) i a g r a m ~: Im~ r'~ PJ ocessing Al~onlhm ~ locl~ DiagTam ~. Irnaae Me,mQr~ M~
Tne processcd d~ta is writt-n by thc im2 ~e processo~ into a Random ~,cc~ss Mem2r)~
(R~M) according to id~ ntified evcnts in Ihc d~t~ strtnm An e~tnt is 2e~lned ~s a sin~le ligh~ spot that includ^s tht tr~nsition from d2rl to li~ht nnd thcn from Liht to dark. Thcse ~tsi~ions ~e s~mpleà 2fler the d~a has b-~n fiilertd thTou~h th- digit~l fill~, and the adaptivD filler (cxpl~intd lat~r)~ Tht memo.~ is ,~q~ngtd in ~soups of si); bvl~s, each ~oup a~scri~-s one ~vcnt and a~fin-d as fcllows:
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B~Yte in Grot~ nemonics I Description tP.~ of liVht. hiVh b~t St'-. Df li~ht~ IOU' b~te ? I ~ Rou~ Nu~nb~-~ hi~h b~e Rou ~ mb~ u~ t~
4 ! ~ n~ o'lirht hiCh b~te ~ 3L I -no oi l,Chl. lou~ bvte ~hl^ 1: ~ma~e Memor~ Cont~nt Since ~.he pi.tule is s^Snned in rou s, ever~ event wil~ st,~; ~n~ end on the s~me IOW, a comple~e li~ht spo~ t!suall~ be spread o~er a feu ~ines and represented b~
~ole th~n one gro~p in th_ m-rnory.

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2~7~

4. Innul Data ~tructure l he in~ut data is reccivcd b) the image l~rocessor as 3 serial lines scn~ Irom the ima~e. bo~rd (Cl, C2, and C3 in ~h~ bloei; dia~ram). Tnest dala lines con~ain strial dala m~!~ip]exed belu~cen Lhe ~ clines as sho~ n :in di~ram 2 .
Linc ~ ¦ O 1 3 1 6 Lint 2 ¦ ~ ¦ 4 Line 3 ¦ 2_ _ ¦ _ 5~
Di a g r a m ~: ]r~pul Data ~;rn~lure e d~l2 from th- imager is a]rtad~ diEilizcd ss c~:plained in Lhc ci~cuit dDscriplion of ~he CCD Im2gcr bo2rd I~ a ] is found it mcans Lh,lt lht poin~ had li~h~ in it, if it was 0, i: m-ans ~at Ihere ~2s no light at ~ha~ poin~

Serl~lizin~ ~he d~td ~tre~m T2~c first operarion of Ihe image pJOCCSSO- is to combine the thrcc input d ta lines in~o ~ single serial dat2 sLrc2m~ The seri21i~r samp]~s Lhe 2hrec input lin~s in a cyclic o.cicr (2s shDwn in figure :2) whi~t s~nchroni~ing Lhe sampling with lhe cio~s ~hal arc s~n; lo shift aat~ frorn tht imagel~

~5~ ' .
Thc digit21 filt~r proccss the da~2 stream ~hile se2rching for a single bil elemcnts ,natrep~esentnois-, o~-~n-smooth tranSiLion b-tween liCht and dzr~. Tn o~vit~l f1l~er . 21u~&~s dela~s the d2t~ stre2m, ~nd "lool~s" at thc conlrnt of Ihre~ consec~ e dat2 bits, Lf d~ling 2 ID,gic O streær., 2h~ data changes to 1, the digilal ~llter chec}:s tne neY~I dala bi!, if is Q, then trl" fi~st 1 is consid~red to b- noisc 2nd I~Dl~ccd U;th a 0. If ~h_ n_xt bil is i~~also 1, i2 m~ans tha~ this is ~ le~ei ch~n,e, and the firs! bi! is not changed. The foliowing tabi^ shows ~1~ the possible czses oi~ ~ conse uti~t bits and how the)~ ære process~d b~ the d!Ci~ ~ l (th- i-f~ bit is thc firs! ~o en-e. ~h- fille.):
~ . , . . _ 0~ cvinnint~ o~ t~ansition to 1~ or noisc, ha~ c lo ~it for n~xt bi~
010 1 ~3~ ¦ Nois- of I in r stlear~ of O
011 1 011 ! Nonna! O to I trPnsition _ _ : ~ o~ I No~nP1 1 lo 0 ~2nsilion _ _ lol !_ 111 I Nois^ of O in ç stleam of I
1 ID ! l lo I Be~rinnin~ o~ transjtion lo O or nois~ have lo w~it for next bi~.
111 _ I 111 ! srr~m of l, no ch~n~c X~: Di~it~l Filler Transf~r Fun~lion . -.

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2~3~1 :Z~ A~aF?ti~ç Filter The ~d~prive rlller is Ih- ne~;~ s~a~e 2flcr Ih~ cliL~il2.1 r~ . Acco~din~, ~o the memo~ dcscri~lion ~ove, uh~n ~n ~cnl is idenl.t~e~, lhcrt ~ ilc c~C]cs 10 thtmcmo.~ on Lhc darL lo li~hl r~-~nsilion (thc .~LrS: ~: ]002!iOnS), 2nd ~JI n two more u~ri~e c~cles for Lhc c~nsi(ion from liCh lo d~rk, ~hi.h ~ inEs the ~o:al o' m-mo.~ ~rilc c!~cl-s ior e~cr~ ~vent lo 6. The sho,~s; evènl ~ha: is allo~ed ~fl-r thc di~i~2~ rll~er conlain~ ~
li~hl bits, Ihc n xl c~!cn: can on]~ occur a~ler ~ ci~l: bils. il m-2ns Ih2~ in a l~le cxrr-me c~se of rcp_alin~ consccu~i~ c ') bi~s ~iehl fol30u ed ~ 2 bits of dar~, U~t h~vc OJI]~ 4 biî S~o1S a\ ailablè for ~2C}) c~ enl, Thc mcmo.~ ~ rite cYcle ta3:ts thc same limC as a sing3e bi~ hich means lha~ in this cxrrcme casc, ti~c infor~atjon can nol b. Wrillen accura~el to the mcmo~ w ithout loosin~ in~Ormalion. Under norma~ CirCumslances, Lne disLancc be2wcen lieh~ sourccs is Xnoun 2nd much lartc, Ih2n t~o bi2s, and ~ ilU~Iion i5 not supposed to hap?en. In ordcr to covcr an ex;rcm^ c~se lil e thc on~ dtscrib~d abo~c thc aaa2~tivt fil~r is constan~iy monitorin~ Lhe àat2 stleam 20 checl; ~hcther thtrt will bt enougn time lo u~ile ali thc iniorma2ion ~ithout loosin~ anvlhin~.
L' thc aQsptivc ~ nds a ~iol2uon lh~2 wili not ~llo~ 6 me:Dor)~ c)~cles io an event, it will siight~ chance Ihe bits in t`ne scqu-nce lo fol~ow lh~ 6 bit cells rule. Th~
~sicn P!SO contP1nS 2 2 bi~ crror counter ssso i~t_d u ith the adaptive fi]~_r (showr, in ,lcurc 1)~ When there is a ~ioiation o~ the 6 bil c~ll JLl]c, and lhe adapti~c fiiter hs~e ~o ch2ncce a d~t~ bit it 21s0 ine.esl:nts the con:~t of th- error counl^r. This coun~cr is desisned to be cieared 2t the b ginning oS th: m-2surcrDent, 2nd u~hen tl)- counler r ac}l_s 3 which is the ~ imu~3 possible v clu: fo. c 2 bits count--, it stavs ~s 3. Afl-r L'~ cort~pl~lion of ~ moi~st~-n_n" the Con~~n~ oS lh" erJOT count~- is ~ci!~bi- to tne ~ic. o c~ntrolif -~ ir tne ~ 2!1~^ is n~t 0, the con~ o~ler }~nou~s th~l a ~io!c!ion O^Curr~Q. .~s s2ià above under no;2 2~ circu~.s.anc~s this c~ . t_tion is n~ r ~ ted 2nd ;i~
~iOl.tiD:'I C2n. 0_- ~T un~-~ exrr~rn_ no~s_ o- d~ 2 ~hr_shold aclusrmenls.

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8. The Data Sam~lQr Tr~ d2ta s~.?~. is msponsible fo~ ~he s~m?3in~ 0' th_ d_l~, in_rmer.ti~ th~
~-rnor~ 2dQ~SS co~nt-., ænd se!ec~i~c tr.e sol~rce o' dat~ (~ znd ~r CDorQin21~S) tO be.
en lo the m;irnone ~ he s:~?!-r is "!oolir.,c,'' 2t ;nt d~c SlJ~2m arl^r Ine sdaptive lt_r whii-h er,sures L"l~; the~fv is æ]w2vs ~ 'o~ al lecs! 6 CyCl~S Or ~Cmo~ writes.
T nio folio~inO is a nore di :aiii d se~u_ni-^ o~ en: pe~o,~ed by thi s2mp~ g proo~ss:
~72i fo. ~sirion. f; o.~n Q2r~ to licrht, ~'hen foun~:
W,it~ ~' sdar_ss ~iC~h b~te (and in.rernen~ ~en,~o~ i~QQmf SS) W ile ~ ~dQr~ss lo~ bytc (zni~ inCJe~cnt ~r~ory add~ess) WnlC ~Lr ~daress hi~7h b~ l~

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2~7~8~

Writc ~ adQress low b~,~tc Y.'ail ~or transition from li~h~ to dark When ~ound:
~!rite X add~ss high b~re (and increment mc-nor~ address) ~'nte ~ addsess ~ow b~lc (and inCremenl memor~ address) Chec~; if address is at the mzximum a~]o~ed, if not: starl a~ain, if cnd of ~emor~: s~op s :mplin~.

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2~ 7~

G. l~.GE r~oc~ )r~c~lr~n t. INTRQC)UCTION
1.1. Gener~l and Scope Tl~ ima--~ rro~essor is desicned u~in~ ~ r]cld pro6ran n ~t)lc ~ale ~Lrr3). Tl~cdesig~l tecl llique is ~cr~ simi)ar lo ~ re~ular ~ocic desicn usin~ schem~lic ent~
SimulaLion~ )ell COn~piialion ~ rO~ alllmin~; illLO 1~)~ dt ~ jCr,. 'rl~`. im lCe ]~rOrtS!,Or Or L~lc ~'CralOmeler Corl~ins Ihrce b~sic r~ns: Ille miCro coJ)~rollel inlcr~aCe t~)~ CCD
rninC ~cnr ralor ancl t~lr. ilna~c proC~ssinc CirCuil. rl~i5 doculncnl conlains a d^scrirnio Ihat ~i~;s ~ uscr n ~ner~l ul dcrslrll dinc of ~l e ~ul clionali~! o~ d~Yic~

1.2. Schcmalics O~ganization ( Fig~s . 3'J-38) n~is à~scripLion rcljcs on 4 bas;c sc}lcm~tic p~cs tll~ lop k ~eJ Ihal conlains thlCt m~inbioclssd-si~rialc~as:~llCRO (Fig. 36 ), CCD_CONT(Fi~.3~ and ~AGE Fi ~ . 38 Each of ~h~se blocks rcprescn~s Lhc i~ Or detalls Ihat is d~sc~bed accoraing ~o the scope of ~his documen~.

2. ~'IICRO GO~TR3LLER li~!T-RFAC~ SECTII~N
The micro controlle~ inlcrlacc is r~sponsib]t rw ~e atl~l~css dec~dinc~ la~ching~ho lowe- b~te o. thc micro con~oller d -la bus ~Id inlerl;lcin~ Ih^ data and address b-tween the rnicro con~ollcs and ~h~ m~mor~.
2.1. Address Decoder (AD I;)ECODr- E3 l ock) rne ad~;.~ss d-coder scr~cs the ~hol~ ~eratomel_r circ ui~ ~nd noî just Lh~ imaC~e pro~essor il d~codes all the address-s ~hal ar- part Or li~ rnt-mor~ map o~ she micro con7l0ller T ho fun^Lions Lhal ar~ adcir-ssed ~re 25 fol]o~ s:
The proOr~m memor~ PRO~) u~l~ich conlains Lh pro~ram lo n7n Lho micro conLroller.
l na Ra~7dom Access M~mo ~ (P~AM) l17a~ slor~s operalional ~ ariables ne~d by îhe rr~icro controll r ~nd Ihe im~g~ prt)-essing resu!Ls~ also r~7'err-d ~s the lma ~ RAM..
The dl~iL~I to ~naloc convcrlor uscd as Lhresho]d for Lile CCD Imaoc . Processor * Th- command regis~r inlern:~l lo Ihis im~ge processor uhich conlrols th-op^raLion~! modes o~ îhe im2rrc processol.
Tne 1~720t: Proc~ssor sl~!rus sead a Ie~i.sl~r Lhal pro~ides stalus resulLs of .. Lhc imae- prcc~ss.
2.2. Image Processor Command Re~lsters (REG Block) Wh~r7 the mi~ro eorl~rc~ller wn~c~ lc) this r~is~er"l~ n~eas~lrem~nt op~r~tic)n bc~in~ ~ilh Lhe pa~I7eî~ rs Ihr~l art load~;d ~ lhc szrnc tim-. Th_ micro contro!l~r can se~
~he follo~ ing oper~lional paramelers: framt siz~ ~o b~ ~ nn~ id~ or na~Tow) whe~h~r .
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onl~ one field is scann~d OT ~ com}~lel~ fTr~mc ~A~hc~her il is a norma~ m~asurement o. a fac~or) calibration invcn ~h~ hl and dar~; s;~nals (if invened th~n t~e meaning of li~h ~nd dark is s~app~d).

2.3. Micr~ Controller Data S~lector (DSEL and CDBUF Blocks) The micro contrc)l~J ~la se]eclor a~ s the control~er lo readlun~e data in a fe~mo~s. DLrin~ normal optration ~ hen a measuremen~ is nol ~ at~d the n~icro control]er can use T;he RAM throu~h tne ima-~e processor and th~ im;~e prooessor is basicall~ ~ltsabled. Und~r sF-~ci~c sla~us RE~D command. tht selec~or pro~ ides the sla~us information to the micJ~ controlleJ on Ihe data bus. During the sl-orl period o~measu~Tcment time i.e. imag~ g~r~bbin the micro contJoller data bus is disabled to allou the image pro~essor to ~le to the R.~M ~nd ~o lo~d ti)t s~aLus regiSTers wTthcu int~rr. u~tion.

2~4. RAM Data S~lector (MDSEL and MDBUF BlDcks) The RAM can be re~d o. ~ritten bv the micro proctssor ~hen a measurement is not active at t`nat time the R.~M d~ta bus i5 COItneCt~d LO the micro conLroller ~henever the RAM is accessed. Durin~ me~suremenL~ Lhe micro processor path is disabled and Ihe image processor drives th~ cuordirlates of Lhe light SpOlS identified into the RAM the X
and ~ CounL~rs ~re rou~ed ~o the RAM data bus as ne~ded b~ th~ pro~es~; aloorithm (des. ribed in details as part of the imag~ proe~ssing alcorithm do; ument) 2.~. RAM Address Selectôr (RASEL E31ock) The RA~ a~dress se~ector similar]~ Io the RAM dala is connecled to the micro controller as long as m~asur~m~nt is nol arive. Du~in measuremenl the ima~
pro~essors address COunleriS conn~cted to the R~M to alicu~ increm~n~in~ aàdress 2S
ne~cied b\~ irn2ge p}o essin algorithm 2.6. L~w Address B~e Latch (LA I C~l blocl~) rne latch reo~ s th~ address I dal2 b~s al1d usin~ Ihe AS micro conrso!]er iin~ to !2tch the lower b~-le of ~ne ad~ss ~t h~ r. Thl ~me ÇÇ~ TIMI~'G GENE~ATOR SECT10N
rne CCD ~ning gener2tor provides all ~he riming si~)als neede~ b~ Ihe CCD
imager. the generalor conlains Ihe main X and ~ cvun~ers ~o~ the image sc~nin~ the ~ qin 5~ machine tha~ con2rols ~he who~ scanning cycle, and ~nree genesalors for the basic ~ive signals reauise~d b~ the CCD.

3.1, M~in Counter~MAlN CNT Bl~ck) The main coun~r prc.vid~s the horizon~al counl of Ihe s3mpling poin~s within e~ery IOU~, th~ counter provid~s th~ 7~6 sam~lin~ poin~s ~nd other taps that con~rols operaions in Ihe CCD~ The c:ol~n~r con~ains 21so a Y collnl~r of ^z~4 odd or e~en lines .
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(total of 8& lines). Dunn~ Ihe caplurc pr~cess of lhe pic~ue, ~h~ cvenl sampl~r uses thes~ v ~luP~ of ~;' and ~' tc~ s~ore in Ihe RAM 25 ~he cDordinal~s of the cvtnt.

3.2. Stnte Machlne (STATES block) rn~ s~at~ machin~ conuol~ the se41~ence o~ even~ dLIring a mea~u~eme,nt cvcle.
from the be,~innin~ of the opeAa~ion, IhC state machine ~oes ~hrough 'priming' pr~>cess of ~he CCD lm~ger and then Lhrough lhe scanninc of all Ille e~en and odd lines of Ihe pictur~. The s~ale machin~ receive~ si, nals ~rom the m~n counler indicating Ihe end o' scanning and chan~es i~s slale ~ccording lo ~h~ oàà. cven OJ oùher ser~ice c!~cies required b~ the CCD.

3.3. Vertlcal Signals Generator (VERT_GEN block) rnc verrical signa~s are required afler ~er~ field of 244 line~ ~ha~ is sc~nned, ~lis blocl~ is responsible ~o ~ener~e the requir~d timin~ for the od~ or even verrical sign~ls ~o al~ow proper operation of th~ CCD.

3.4. Horlzontal Region 1 generator (H1_GEN) ~ ver~ line thal is scanned in Ihe CCD is recluir~ lo hav~ a special si~nals al the begir~ninr~ of the horizontal scan before the piciure is a~ailable at th~ outputs of the CCD.
rn~s blo~l; gene,a~es the first 31 samples (firsl re~ion) of ~en~ scan that ~re ~ctuall~ not s~en as part of rhe pictur~ to ~llow proper operaùon of the re~l of the picture.
3.~. Horlzontal ~egion 2 generator (H2_~iEN) The second region genera~o; is respon~ible lo 'push' ~he piculre out ol the CCD, i pro~ides rhe e~:act number of puls~s r~quired o receive one line of Ihe picrure.
3.6. CCD nming Seleotor (V_H_SEL block) Tne C~) timing ~elector is responsib]e for selec~ino ~hich of rhe abo~e generate~ si~nals should b. sent at an~ ~ime lo Ihe CCD. Tne àecision is made by Lhe s.ate macnine thaI con~ois a s-, of ~:el.,ctors that route rhe appropriare generated si~n~ls IO t~le CcD. The lesulI is the ac~ua~ lin~s tha. ~re sent lo the CCD cri-~ers.

4. IMA~E PROCFSSII~C; SECTlON
This secrion of th~ imagc pl`OCeSSOI COVers the aCtu~] imaoe proc~ssing. for fillther understanding of the i~na~e process al~.orithm, it is r~commenaed ~o read ~ht Ln2ge Processing Algorithrr, document~ This section contains the processing conrrol, the event processing, the X ~alue la~ch, and Ihe imace countcr. 'rnere ~r rwo blocks Ihat we~e used lo accumul~te the X and Y values called SIG~AX' and SlG_~' that appe2rs in ~c schema~cs bul are nol used.

4.1. lma3e Prc~cessing Conlrol (HOR_SCAN block) ~ is blocl; is responsible for Ihe ac~ual picluré capl~ré, it e~ UaLéS Lhe rqu~remen~s iha~ ~re loaded b~ the micro controller ~h~th~r to sampl~ a sin~le fr~né or -- ~8 --2~7~
rhe whole pic~ure, and the ~crual frame size, and then cnables the data lo flow to the ~venl processor. This bloc~ also supports ~he incremen~s of Ihe memor~ coLlnler as rc~uire.d. ~'hen Lhc measu~emenl oF)cration is compl~d Lhis blnc~; flags ~hc micro conrroli~r tha~ Ihe operauc)n is complele.

4.2. Events Processing (EVENT block) The e~enl p~ocessin~ blocl; is di~id.d lo lhr~ consecuLi\~ suh bl~l;s: Lh~ di~ital hller, adaptive filLcr and the sarnr ler. Th~. o~eration o~ ~hese t locl;s is describ~d in det~ls as parl o~ Lhe ima~e prc~cessino al~,onLhm documc 4.3. The X Latch (X LATCH block) ~ ne X lalch is uscd to hold ~he ~alue or Lhe ~; cc~ordinate counler Lo ensure a s~able writin~ to th~ memor~ hile Ih~ picrure is process~d. The lil~chin~ of Ihe ~ ~alllc is rcquired since the ~riLe opel2Lion to Ihe memory re4nires 1~ o cons~cu~ve wrile opcraLions, ~nd the sccond pan of Ih~ writLen ~' is ~;epL lo prcvenL corruption of Lhe valuè, 4.4. Image Counter (IMADCNTR block) The ima~ counter is r~sponsib]e lo gc~erale Ihe add~ess lo tht R~M while the picture is processed. Al Ih~ ~nd of the process Lht count~r keeps the i~st ~Iress that was used and rhe conrroller can read this ~ UE and use it tt) know how m~ e~nts wer~proces~ed durin, Lhat c~cle.

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H. Software ~heory of Operation The following is a description of the software operation of the preferred embodiment of the invention. Reference should be taken to the flowchart at Figs. 16A-16B, Figs. 34A-34B, as well as the other Figures and description regarding the preferred embodiment.

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I. Pre~ace A. Keratometry i,~ General The function of the 1~ a,shase hand-held Keratometer is to measure the radius ofcurvature of 2 patients cornea quickly and accurately This curvature is calculated alona two ortnogonal meridians. The results can be expressed as corneal powers (units of diop~ers - abbreviation Dk), or radii of curvature (units of milli-meters).
B. Our Method The Keratome~er uses four equally-spaced light sources which project collimated iight onlo a patient's eye. The light is re~lected off o~ the eye and imaged, asspots~ onto a charge-coupled imaging device, or CCD. The scan data is then digitized, run-length encoded, and stored in a memory buffer. A microprocessor evaluates the data. Each run is grouped according to proximity to recreate the four spots. The center of each spot is calculated by averaging the position and length data of all runs in a group.
ll~e basic computation uses three'spots. The radii of curvature are calculated using the positions of three measured spots with respect to a set of known reference positions. Our implementation uses the positions of all four spots to create three "synthetic" spots. The "synthetic" spots are then used in the three-spat calculations.
Il. Plardware/Software Interface A. Micro-controller 1. General The sotware runs on a Motorol2 6BHC11 E1 8-bit micro-controller unit (MCU). The HC11 is a high-àensiry Cl~IOS component with sophisticated on-chip peripheral capabilities. These features include:
-> Serial Peripheral Interfa_e (SPI) -> Asynchronous Serial Communications Interiace (SCI) -> 512 bytes o~ EEPRO~
-> 512 bytes o~ s.atic RA~
-> Eight-channel, 8-bit Analog/Digital converter -> Real-time interrupt circuit -> Enhanced 16-bit timer system -> Power-saving STOP and WAIT modes -> Small 52-pin plastic leaded chip carrier (PLCC) -> 2 Mhz Bus speed -> 6~ Kby'le linear address range -> Full instruction set . .

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We operate the 68HC11 in expanded mode, using its external EPROM and scratch-pad memory.
2~ Pin Usage The functions of the HC11 I/O pins are:
Pin l!O DES l/O Name Description PAO Input no~ used N A Pulled LOW via ;0;~ ;esis10r PA1 Input PRINT Signal from base PA2 Input BUSY:LCD8 Busy iine from LCD controllers PA3 I!O Output SELO:LCD5 Peripheral select line PA4 Output SEL1:LCD6 Peripheral select line PA~ Output SEL2:LCD7 Peripheral select line PA6 Output P~'\JM:LCD4 LED PWM signal PA7 I/O Output SLEEP Power supply on/off Pbx N.A. [[[ Upper address byte in expanded mode ]]]
PCx N.A. [[[ Multiplexed address/data lines in expanded mode ]]]
PDO l/O Input RxD SCI: receive data PD1 I/O Output TxD SCI: transmit data PD2 I/O Input l/llso:LcDo SPI: master-in slave-out PD3 I/O Output MOSI:LCD1 SPI: master-out slave-in PD4 llO Output SCK:LCD2 SPI: serial clock PD~ l/O Output SS:LCD3 SPI: slave select P~O A. Input A. Input P12V Plus 12V supply test PEt A. Input A. Input P1V5 Plus 1.5V supply test ?-2 A. Input A. Input N7V Minus 7.0V supply test PE3 A. In?ut A. Input N9V~ Minus 9.::,V supply test PE~ A. Input A. Input SAS~ Monitor when in base PE~ A. Inpul A. Input VBAT Battery voltage test Pc6 A. Input not used N.A. Pulled tD ground via 10K
Pi-7 A. Input not used N.A. Pulled to ground via 10K
Note: PA3 is an outpul-only pin on the 68HC11A1/A8 part.

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3. ~emory Map The memory is mapp~d as:
Description Rance Bytes Notes Internal RA~vl0000- 01FF 512 details below Unused 0200 - OFFF 3584 68HC11 Registers1000- 103F 64 Unused 1040- 1FFF 4032 RAt~/l 2000 - 27FF 2048 4 overlapping pages, details below Unused 2800 - 3FFF 614~
IP Registers4000 - 4FFF 4096 redundant mapping Unused 5000 - 7FFF 1228B
EPROlvl 8000- B5FF 13824 EEPROM B600- B7FF 512 details below 0000 FFFF 65~36 Internal RAM Rance Byt;es Notes MATH11 FP regs0000 - 0009 10 floaling point accumulators ior mathl 1 .S07 lo_al varsOOOA - 005F 86 assembly routines local variable space HC11 RAM vars0060- 006F 16 non-volatile non-paged memory Unused 0070- OOFi- 144 spare direct-access memory Unused 0100- 017F 128 spare extended-access memory Slâ~.k SDac20180 01FF 128 program s~,ack area 0000- 01Fi- 512 E-3ROM Ranoe Bytes Notes CC varsB600 - B64F 80 camera calibration parms in REAL
format SC vars B650- B67C 45 spot calibration parms in REAL
format DA varsB67D - B6E5 105 pre-calculaled values in REAL
format P~ vars B6E6- B715 48 . parameterrecord-operationaldata Unused B716- B7FE 233 ChecksumB7FF - B7FF 1 EEPROM checksum _ B600- ~7FF 512 - ~ , - ,, ;~,~ . .
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B. ~"lemory 1. EPROM
a. Overview Program memory resides in a 27C256 one-time programmable (OTP) PRO~. The device provides 32 Kbyles o~ program storage and comes in a 32-pin PLCC
package.
b. Software Interface The program memory address range is 800û to FFFF hex. The exception vector table, or interrupt vector table, is located irom address FFD6 to FFFF hex, per ~lCU specifications. The 16-bit checksum ior this device is at address 8000:8001. Addresses B600 thru 67FF hex are unavailable due to conflicts with the MCU internal EEPROI~
2. R~!~
a. C)verview The RAM is composed ol iour 2 Kbyte sections, or pages. Each page resides at addresses 2000 to 27FF hex.
b. So',tware Interface Each paye has a designated use:
pageTr' usage 0 General variable s;oraoe Communication routines messages 2 VideG datâ page 1 3 Vibeo data page 2 The lower tWD bits of the imaae processor register RAM_CONFIG REGISTER
(û0/01/10/11 binary) determi"es whicn G, iour pages is accessed. The routine SwilchToPaoe() in ~ile PAG_.S07 does the pag& swilches.
To select page -1: SwiT_hToP^o^(1);
To selecl page -3: SwitchToPage(3);
I ne subroutine Fifo2C~lT() in FIFO2CMT.S07 circumvents this procedure by writing directly to the paoe register. This exception increases the instrument measurement speed.

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3. EEPROM
a. Overview The HC11 has 512 bytes of on-board non-volatile EEPROM. To program the EEPROM, the sot~ware writes out 10 hex to the block protecl (BPROT) register within 64 cycles o~ reset.
b. So~ware Interface The EEPROM memory is used to store calibration parameters, operational modes and user options The routine ProgramEEPROhllByte() in file AS~\AI.S07 does the actual programming. Examples:
Write data 3C hex tD B634: ProgramEEPROMByte(oxB634, 0x3C);
Write data F5 hex to B701: ProgramEEPROI,/lByte(0xB701, 0xF5);
The MCU can only program bits from ones to zeros. To change a bit from zero to one, the entire byte must first be erased (all bits set to one), then reprogrammed. Since the EEPROM has limited life, the routine checks the currently stored data against the data to program. If the data-to-write 1) equals the data already there, nothing is done, or 2) involves only programming more zeros, the byte is proarammed, or 3) requires any bit to change from a zero to aone, the byte is erased and reprogrammed.
An 8-bit checksum of the EEPROM is stored in address B7FF hex. The routine ChecksumEEPROM() in TESTING.S07, calculates the checksum. The routine CommitToErPROM() in MISC.C, stores the current checksum.
-> Camera calibration The camera calibralion parameters which characterize the optical system, are stored in the 68HC11 E~PROM during instrument manufacture. The parameters ~ _ .
ar_ .
xp,yp,f,l1 ,12~13~p1 ~p2~p3.~.xc,yc,zc,omega,kappa,phi They are referenced by the data structure detined in CC.H.
-> Spot calibratisn rne spot calibration values are also stored in the 68HC11 EEPROM
during instrument manufacture. T'nese values represent the spot positions obtained by projecting the red LED's onto a known power surface and recordir,3 spot positions. The data set also contains the diopter power o~ the calibra;ion lensJball. Items are:

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dkCalBall : Cali~r2lion power vi[0].hor,vi[Oj,ver: Spot 1 position vi[1).hor,vi[1].ver : Spot 2 position vi[2] hor,vi[2] ver : Spot 3 position vi~3].hor,vi[3].ver : Sp~t 4 position The~ are reierenced by the dala strus~re deiined in SC.H.
-> Pre-calculated values Some Terms of the computation depend only on the calibration values. To save process jng lime, these lerms are pre-calculated and stored in the 68HCi 1 EEPROM~ The terms are:
m11 ,m1 2,m1 3,m21 ,m22,m23.m31 ,m32,m33,m1 3z,m23~,m33z, x2b,y2b,x3b,y3b,twoA,tourA,quadZero,threshFactor,nonTorricVal They are referenced by the data structure defined in DA.H.
-> Operational values These values include various functions, from user selectable operational modes to reference anales and execution values. The values are stored in E_PROt~l in a dat2 structure defined in PR.H. During operation the values are used in the RAI~/I structure MO.H.
C. Imaging System l. Im2ger Our ima~er is a charged-coupled aevice (CCD) from Texas Instruments, part numb2r Tl-245. The optical area measures 8.0 mrn diagonally; 6.4175 mm wide by 4.7795 mm hiah. Th optical area is divided into 75~ columns by 484 rows.
Physically there are 242 rows of pixe!s, and eleclronic interpolation produces 484 e.,e^liverows. The interpalG~ion provi ies two "fielas": one even and the other odd.
The fields are imerleaved to make a frame. There is no space between pixels.
The pixel Sjz2 is 8.~ ,Lm wi~e by 9.&75 ,llm hiah (19.75 ~m hi~h, PHYSICAL pixel).
Hor,,ontally there are 11 /.6~70-3B pixels per mm, and vertically there are 101.26;~2~B pixe!s per mm.

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CCD o~tical area:
<-------- 6 . 4 1 ~ 5 mm -- ----_ _ _ _ _ _ --- -. 1 ~484 rcws I ' 8 . 00 mm diagonal 1 4 . 7795 mrn , 755 columns v Pixel si~e:
~-- r~. s um ---->

r 9.B75 um 2. Imaoe processor a. Overview Our image processor (IP) is implemented in an ACTEL A1020A ASIC
(Ap,~lication-Specific Inte~rated Circuit). It comes in a 68-pin PLCC
package. The regislers available to the MCU are:
COMMAND REGISTER: (write-only; address = 4000 hex) bit name description _ _ _ 7 IPRAM PAGE1 Selects current RAM page 6 IPRAI~ PAGE0 Selects current RAM page P3 (IP POWER) IP power on(1)/off(0) d INVERT Image(1)/normal image(0) 3 RrSET Device reset(0)/normal operation(1) 2 FRM/FLD Process frame(1)/process field(0) FRM SIZE1 Enable processing of top of image(1) 0 FRM SIZE3 Enable processing of bottom of image(1) RAM CONFIG REGISTER: (write-only; address = 4002 hex) bit name description 2 CALIB Calibrate mode(1 )/normal mode(0) MPRAM PAGE1 Selects fifo pa~e to store video data O IvlPRAM PAGE0 Selects fifo page to store video data .

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STATUS REGISTER: (rea~-only; addrer-s = 4000 hex) bit name description 7 A3 Lasi addre~s o~ vid~o data, 6 A2 Lower four bits A1 Lower 1Our bits 4 A0 Lower lour bits 3 unused 2 ER1 Error indicator bit ER0 Error indicator bit 0 CP Command-pending(1 ) DAC REGISTER: (write-only; address = 4004 hex) bit name description 7-0 input to D/A convertor, which is the image signal threshold voltage.
L~ST ADDRESS: (read-only, address = 4033 hex) bit name description 7-o last address, upper eight bits, combined with A3-A0 from abovê.
After processing a video field or frame~ video data entries reside in video pagememory starting at address 2000 hex. The imaae processor computes the "last address plus 1" of the video data. The Izst address is twelve bits wide, and is compcsed of the I~S~ ADD~ESS rzgisTer concatonated with bits A3-A0 of the STATUS REGISTER.
Please note that the video da~a is also referred to as 'Yifo" dala.
b. So~ware Interface The files IMAGER.C and IttlAGER.H contain drivers for the image processor. The;
r~utine GetFifo() commands the IP to take a field or frame of data, waits for the completion of the task, and retrieves the last address and error bits. The procedure DoubleFifoBurst() does .he same thing, but it takes two successive imagest increasing mezsurement through-put. Examples:
Take an imaae during measurement proces s and put the data into page 1:
GetFifo(MEASURlNG, FIFO1 PAGE):

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DoubleFifoBurst();
3. D/A Converter a. Overview The imaging system has a variable threshold using an &-bit DAC IC. Higher digital values increase the threshold so that more light is needed to turn a pixel 'on".Lowering the digital input lowers the threshold.
b. Sot~ware Intertace The routine SetlmagerThreshold() in files DRIVERS.C & DRIVERS.H sets the DAC
value When measuring eyes, the first two values of the mo.dacValue array are used; when measuring steel balls, the last two values of the mo.dacValue array are used.
D. Serial Peripheral Interface (SPI) The eight signals which comprise the Synchronous Serial Interface (SPI) system inciude (refer to paragraph II.A.2):
MISO : master-in slave-out data line MOSI : master-out slave-in data iine SCK : serial clock SS : command/ data signal to LCD drivers (uPD7225) SEi~ : select lines to enable particular device, S~L1 : e.g. LCD drivers, keypad shift register, or SEL0 : RCLK of 8-bit serial/parallel shifters _5USY : busy indicat3r ~rom LCD drivers The S~L~:SEL1 :SEL0 lines select which device is accessed via a 3-to-8 decoder 7 .HC138 (U3). The SS line indicates ~o the LCD drivers whether the incomming da~a is a comrnand or raw da.a. ~ne LCD drivers accept the daia, and hold BUSY low until they are ready tor another byte. The keypad is read via a 74HC16~ parallel-to-serial shif'. regisler (U4). The three 74HC595 serial-to-parallel snift reaisters (Ua/uD/u7) control the projector, alignment, fixation LED's, level LE3`s, mirel-backlight~ speaker, LCD contrâst, LCD driver reset~ and caiibrationRAI\~l pointer reset.
The files DRIVERS.C & DRIVERS.H contain the keypad and 74HC595 driver routines. The general purpose routine, ShiftOutDriver, controls the 74HC595 shift registers. The low level LCD drivers are in LCD.C & LCD.H, and the high level display drivers are in DISPLAY.C & DISPLAY.H.

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1. LCD Display a. Overview The LCD display is composed o~ 16~ se3ments including 19 seven-segment numbers and 32 individual icons. The drivers are configured as a master/slave combination of NEC UPD7225 ICs (U1 and U2). Each segment is individually controlled, and can blink at either o~ Iwo rates.
Segment Identification: Segment COI~l Connections:
(quadruple~ed) a O

dp ~ --Controller RAlvl allocation tor each segment:
n ~ 1: d:e:g:f n: dp:c:b:a Four outputs of shift register U7 comrol the contr2st of the LCD segments. All outputs set to ones gives maximum contrast.
For further information, refer to N.C UPD72 intelligent AlphaNumberic LCC
Controller/Driver Technical Manual ~stock ~ 500250), and NEC UPD7225 Applic2tion Note (stock-. 501102).
b. Software Interface The low level drivers Tor the LCD ar in files LCD.C & LCD.H. The procedure Icons() controls the 32 individual icons, and the procedure Digits() controls the seven-segment numbers. The icons are all single-segment items, such as the display units (Dk/mm), the display forma. (sphere/cyiinder/base curves), anri the angle reTerence (ground/handle). Exampies:
Turn the "Dk" icon on: Icon(lCON DK, LCD STEADY);
Turn the "mm" icon off: Icon(lCON Ml\il, LCD ALL OFi=);
Flash the 'i~" icon: Icon(lCON_PLUS, LCD FLASHING);
The 1~ digits are numbered leff~ to right, top to bottom. Examples:
Put a "1" in location ~15: Digit(DlGlT_15, '1', LCD DR ON);
Put a blank in location . 3: Digil(DlGlT_3, ' ', LCD ST-tADY) .
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To dlsplay a comple~e numerical value, call DisplayNumber(), Examples:
Display 42.57 in group 1 (top left):
DisplayNum~er(DlGlT GROUP_1, 42.57, LCD DR ON, TRUE);
Display 123 in oroup 5 (degrees place):
DisplayNumber(DlGlT GROUP_5, 123.0, LCD DR ON, TRUE);
The high level displa~ driver, Display() is in files DISPLAY.C & DISPLAY.H. The function displays a particular set oi segments based on the current operating mode and results. Examples:
Display current reference angle status:
Display(D ANGLE REF);
Display current results lormat:
Display(D RESULTS FORMAT);
The contrast is adjustable from 0 (no contrast) through 15 (maximum contrast).
Example:
Set contrast to 7: SetLCDContrast(7);
2. Projector LED`s a. Overview rne four red proje~tor LED's are oontrolled viâ â single line (QA) from shitt register U5.
b. So~are Interface Examples:
Turn projectors on: ShiftOu;Driver(SO M~AS LEDsl ON);
Turn them off: ShiftOutDriver(SO iVlEAS LEDs, OFt);
3. Alionment LE3's . Overview The eight green alignment LED's help the operator align the instrument during measurement. These are controlled by a single iine (QB) from shi~, register U5.
b. Soi~ware Interface Examples:
Turn alignment on: ShiftOutDriver(SO_ALlGN LEDS, ON);
Turn them off: ShiftOutDriver(SO_ALlGN LEDS, OFF);

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4. Fixation LED's a. Overview The five fixation L~D's: center, top, bottom, left and right, give the patient a point tc fixate on while a measuremenl is being taken. Each fixation LED is individually controlled via outputs QA through QE of shift register U6.
b. Software Intertace Examples:
Turn center fi?;âtion on: Shi~OutDriver(SO CEi`lTER_FlX LED, ON);
Turn top fix2tion off: Shi~OutDriver(SO_TOP FIX LED, OFF);
ire a. Overview The mire is composed of a ring of red LED's including the top, bottom, left and ri~ht fixation LED's. Together these form a complele circle which is projected onto the patients eye jusl prior to the measurement. The mire allows the operator to visually inspect the surtace of the eye for abnormalities. Mil-e control is provided Vi2 pins QA, C~, QC, and QD of U6.
b. Soflware Interface The high level iunction Turnl\Aire() controls the LED's. Examples:
Turn mire on: Turni~lire(ON);
Turn mire oft: Turnl\~lire(OFF);
6. Speaker a. Overview The beeper is a pie~o-elec;ric spe_ker driven by â LM5aa timer. The timer has ~wo comrol lines: one con~rols the pitch, the other is an on/off switch (U7 pin QE).
5. So,f~iare Intertace The high level funcTion Speaker() controls the beeper. Examples ~ urn speaker on high pil. h: Speaker(SPKR HIGHj;
Turn speaker oft: Speaker(SPKR OFF);
7. Level i ED's a. Overview The level LrD~s light a device used to determine the angle o~ the instrument with respect to ground. The LED`s shine through â liquid which is imaged as a line onthe CCD. The ~CU calculates the slope of this line and hence the angle of the instrument~ The level LED`s are controiled by a single output line (QF) on shittregister U6~

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b. So~ware Interface The high level function ReadLevelAngle() in file MEASURE.C turns on the level LED s~ commands the imaoe processor to collecl the data, and calls ProcessLevelFiio() which calculates the angle. ProcessLevelFifo(), in tile LEVEL.S07, uses two "poin~s" to compute the slope The two points are averages o~ 16 samples taken at lhe beginning and end of the image data.
8. Backlight a. Over~iew The backlight is an array of yellow LED's which illuminate the LCD to improve readability. The backlight is controlled by output pin (QG) on register U6.
b. So~ware Interface Examples:
Turn backlight on: ShiftOutDrivers(SO_BACKLlGHT, ON);
Turn backlight off: ShittOutDrivers(SO BACKLIGHT, OFF);
9. Keypad a. Overview The keypad has six keys: SELECT, SCROLL, CLEAR, RIGHT EYE, LEFT EYE, and MEASURE. Key closure is determined by polling the 74HC165 (U4) register.
b. Soflware Intertace The low level keypad driver ReadKeyboard() returns the current status of the keypad sense lines~ The high level routine CheckKeyboard() monitors key press, debounce~ and release. U?on release, it makes a key "click" s~und.
CheckKeyboard interprets pressing the MEASUi~E key as an ALIGN_KEY EVENT
and turns on the mire. CheckKeyb3ard interprets release of the MEASURE key as a MEASURE KEY EVENT and begins the measurement process.
0. Reset Lines a. Overview The LCD drivers can be reseT by pulling line (QG) of lJ7 low. The calibration RAM
poin~er is reset in the same rr,anner by (aH) Ot U7.
b. Software Interface Examples:
Reset LCD drivers: ResetLCD();
Reset cal RAI~ pointer: ResetCalRAl~lPointer();

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E. Serial Communications In~ertace (SCI) 1. Overview The two signals which comprise the SCI system are (reler to paragraph il.A.2):
RxD: Receive data line into MCU
TxD: Transmit data line out of MCU
This intertace outputs a ticket to the printer and communicates with the field test terminal/engineeri~g test solrware, or the l~letaphase PC system.
2. So~ware Interface The low level asynchronous communication module in files COMM.C ~ COMM.H
formats, receives, transmits, and extracts messages to/from the PC and sends ticket information to the system printer.
The high level driver which communicates with the PC resides in PCCOMM.C and PCCOMM.H. In PC-to-MCU mode, the PC initiates all communications with an ENQuire byte, then waits for the MCU to respond with an ACKnowlegde byte. The PC then sends a command and data (if any), and waits for the MCU to return a response and data (if any).
F. Calibration Module i3uring camera calibration, the Keratometer must store much more data than in normal operation. A calibration RAM module is used for this purpose. This module provides 32 Kbytes oi RAM storage for the fifo. The module is accessed sequentially, not randomly.
To start the process, the calibration R~M pointer is reset by the ResetCALRA~lPointer ( ) routine. Then the IP stores a frame of data in the RAMI
module. After the pointer is reset again, the data is retrieved by reading address 2000 hex. A write to address 2000 hex increments the address pointer, the process is repeated until all fifo data has been read.
111. So~are Organization A. Vendor Pack2ges 1. Archimedes C-compiler, assembler, Iinker and librarian 2. Sage Sof~vare Polymake dependency generator and make facility 3. NOHAU EMUL-6~ emulator control package B. File Descriptions 1. C source files, ~.C
aa) BORDER : defines active useful area on imager ab) CALIBRAT : control camera calibration functions ac) CM : deciare center of mass data ad) COMM : low level asynch serial communication module .' ' ' ' ' ~ ' ,, :: ; ... .

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ae) DISPL4Y : high level LCD display drivers af) DRIVERS : low level device drivers ag) DUMP : dumps test data out of the comm port ah) ERROR : handles system errors ai) FIELDTST : controls tield test terminal aj) GETPUT : C procedures getchar() and putchar() ak) GL : global data declaration al) HIDDEN : oplions hidden Irom normal user am) 11 : instrument info; copyright and date an) IMAGER : low level image processor driver ao) INIT : initialization and startup routines ap) LCD : low le~el LCD driver aq) MAIN : main program control module ar) MEASURE : controls the measurement process as) MISC : miscellaneous subroutines al) MO : mode variables; a copy o~ EI~PROM pr structure au) OPTIONS : user-selectable options av) PCCOMMl : PC serial communication interpreter/processor aw) PRINT : prints tickets ax) QU : results data declaration ay) RE : results data declaration a.) RESULTS : handles storing/saving/loading/restoring results ba) Si~LFTEST : hardware selftest routines bb) THRSHOLD : thresholds signal; not used now bc) VA : intermediate calculation variables data declaration 2. C header fiies, ~.H
aa) APPL : application-specific constant definitions ab) ASCII : ASCII constants ac) ASM : header ad) BORDER : header ae) CALC : header cf) CALI:,RAT : header ag) CC : camera calibration data definition ah) CM : center-of-mass da.a definilion ai) COMM . : header ai) COt~'ST . : cons;ants ak) DA : pre-calculated values data definiti~n al) DASM : header am) DISPLAY : hea3er an) DISTORT : heaber ac,) DRIVERS : header ap) DUMP : header aq) ERROR : header ar) FIELDTST : header ~ , -~

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2S) FIF02CI~T : header at) FILTERS : header au) GEi'~ERAL : system-wide header file a~) G~TPUT : header aw) GL : global variables data definition a~:) HC : 68HC1 1 RA~l variables dala definition ay) HIDDEN : header âZ) IDSPOTS : header ba) ll : header bb) IMAGER : header bc) INIT : header bd) lO : sys~em l/O definitions and addresses be) 106811 : 68Hc11-specific register addresses bf) LCD : header b3) LEVEL : header bh) MAlr~ : header bi) Mi-ASURE : header bj) MEMORY : header bk) MISC : header bl) MO : mode variables data definition bm) MOREASI~/I : header bn) OPTIONS : header bo) PAGE : header bp~ PAG~1 : comm messaoes data definition bq) PCCOMM : header br) Pi~ : parameter record data definition bs) PRINT : header bt) QU : que da~a definition bu) QUEUE : header bv) R~ : results dala definition bw) rsi-AL : REAL type defimion bx) Ri-~LCMS : header by) RESULTS - : header bz) SC : spot calibration data definition ca) SELFTEST : header cb) Ti_STlNG : header cc) THRSHOLD : header cd) TOSSBAD : header ce) VA : intermediate calculation variables data definition cf) VECTOR : header 3. Assembly source files, i.S07 aa) ASM : various assembiy language routines, incl. GoToSleep() ab) CALC : calculates base curves, axis, and torricity ac) CC : camera calibration data declaration ~ . .

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ad) CONSTANT : aefinition o~ REAL constants ae) CST~RTUP : C pro~ram star~ up and exception vectc~r table af) DA : pre-calculated data declaration ag) DASM : various math-related subroutines ah) DISTORT : converts image points to object points via lens correction ai) FlF02CMlT : convens image data to center-ol-mass table aj) FILTERS : area, radius and power filters ak) HC : 68HC11 RAM data declaration al) IDSPOTS : identifies spots am) LEVEL : determines level angle an) MATH11 : FAST floating p~int math library obtained Irom Motorola BBS
ao) MEMORY : C procedures memcpy() and memset() ap) MOREASM : tormatts results aq) PAGE : switches RAM pages ar) PAGE1 : comm messaaes data declaration as) PR : parameter record data declaration at) QUEUE : que handlers au) REALCMS : converts pixel data to floating point centers-o~-mass av) SC : spot calibration data declaration aw) TESTlNG : various self-test routines ax) TOSSBAD : removes bad spots 4. Assembly header files, ~.INC
aa) 6811REGS : 68HC11-specific register addresses ab) APPL : application-speciiic values ac) CC : camera calibration data header ad) CM : center-~-mass data header ae) CONSTANT : REAL type constants header afl DA : pre-calculaLed values data header aQ) DASM : header ah) FlrO2CMT : header ai) GL : olobal variables data header âj) HC : 68HC11 RAM data header ak) lO : system l/O definiTions and addresses al) MACROS : macro definitions am) MAT~11 : header an) MO :- mode variables data header ao) MOREASM : header 2?) PAGE : RAM paging header aq) OU : queue data header ar) RE : results data header 2S) Ri_AL : REAL type da;a header at) SC : spot calibration data header au) VA : intermediate calculation variables data header ~ . , ~ ~ 7~
5. I~,ake files a. ~AKE-lLr-.MAK
Th~s file controls the "make" or com~ile/assemble/link pro~ecs. Typin3 I~AKE
<CR> at the DOS promp~s executes lhe "M~KE". The code is generated and put in file MAIN.A07. It can then be do~nloaded into the NOHAU emulator. Typing MAKE EPROM <CR~ reates the output file EPROM.IJIOT, in the motorola S-record format accepted b~! an EPROM programmer The "MAKE" file can also u?date the MAKEFILE.~JI~K dependen~y when the user types ~ AKE DEPS <CR>
at the DOS prompt or 2) delete all 7.E~K files and execute Norton's directory sort (DS) command to arranoe the files when the user types MAKE CLEA~UP <CR>.
b. BUILTINS.MAK
This file tells Polymake how to invoke the Archimedes assernbler/compiler and what options to use.
C. 1~/5ain State Machine (Reference Figure 1) The main program control is handled in files I~AIN.C and MAIN.H, a finite state table sequences the procedures. The STATES are:
SL~EP : All power except I~ICU powers off, saves results in RAM.
HOLD : Results displayed on LCD, but turn backlight off, DISPLAY : LCD display and backlight both on, THi~ESHOLD: rnresholding algorithm ~not currently implemented), MEASURE : M2ke a me~surement O?TIONS : Select and scr~ll through the user selectable options, HIDDEN : Select and scroll through the hidden options.
The EV_NTS arE:
1. Keypad enlry evems ^. NO i~VENT : Nothin3 happened b. S_LECT KEY : Sêiêct k y dê~ressed c. SCROLL_KEY : S-roll k-y deprecsed -'. CL AR KEY : Cle^r key bepressed e. RlGH-I_t-Y_ KEY : RighT eye key depressed f. LEF EYE KEY : Lelt eye key depressed 9. ALIGN KEY : Me2sure key depressed h. ~EASURE KEY : Measure key released i. PRINT KEY : Print key depressed 2. Pr3cedure relurn S.alUS
2. C)K FLAG : Routine successfully executed b. REPEAT FLAG : Routine needs to try again c. FAILE3 FI~G : Routine ,ailed 3. PC 1vlESSAGE : PC sent an ENOuire byte 4. FIELD TEST TEF~MINAL :Terminal sent a CR byte .

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5. TIMEOUT :No activity tor prescribed amount of~t~n7e~ ~3 51 Note that the measure key has two tunctions, one when pressed and another when released. The clear key has three functions. The iirst tirne it is pressed, the current results are cleared from the displa~. The second press clears all results. The third press ~uts the Keratometer into SLEEP mode.
JIeasurement Process (reference Figure 2) A. Align Instrument 1. Procedure a. Turn alignment LED's on b. Delay for 1.5 seconds c. Turn alignment LED's off 2. Equa~ions: NONE
3. Dala: NONE
4. Source 2. MEASURE.C
5. Errors: I~JONE
P. Take an Image 1. Procedure a. Turn red projector LED's on b. Se; first threshold (DAC) c. Command imager processor (IP) to take a frame of data d. Have IP store runs in imaoe data page 1 e. Read IP stalus bits and last address f. Set threshoid value 2 ~. Command IP to take another frame of data h. ~zve IP store runs in imace data page 2 i. Read IP sLatus bits and last address . Eouations: NONE
3. Dc;a a. RAM da.a The im2ge da;a is run lenoth encoded. Each run contains three pieces of information: beginning column (X), row (Y), and ending column + 1. Each item is two bytes long. Eaeh page is 2048 bytes deep, so the maximum number of runs a page can store is 2048/6 - 341. Each value recorded in the run sextet is shifted by a fixed value. The shi~s are 1 û3 for X data and 22 for Y data. The;
offsets are subtracted from every sextet term.
Note: When collecting fiio data, the IP sometimes records an ending X, which is less than the beginning X. In this case, the ending is set X to the maximum column (7~

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Source a. MEASURE C
b IMAGER.C
c. DRIVERS.C
. Errors 2. IP status bits indicate errors (see hardware explanation for error details).
b. Image memory buffer can overlow (i.e. tries ~o store more than 3~1 runs).
C. Gather Spots 1. Procedure a. Group all page 1 runs in~o a new center-of-mass (Cl~) table b. Group all page 2 runs imo f~xis~ing Cl~l table 2. Equations: NONE
3. Data a. C~ table The C~A table contains inlormation about each spot. The information includes:
horizontal and venical b2se posiIions, vertical weighted sum of runs, sum of all run lengths (area), floating point center-oI-mass (horizon.al ~ vertical), spot identifier, and bad spot indicator flag. The base positions are the horizontal and vertical positions of the first run tound for tha; panicular spo.. The vertical weighted sum o~ runs is computed by multiplying each run length by its row, and adding all ofthE terms together tor a given SpOt. See Clvl.H for the definition of the CM data type.
4. Source a. FIFO2CMT.S07 b. CM.H
. Errors G. Too manv spots in Cl~ table (more ~han 4) b. Too few spots (less than 4) D. Veriry 3asic Da.a S-, 1. Prooedure a. Remove all bad or ques;ioncbl- sj,ots b. Che^k that we have e~aetly four SpOTS
c. Check thaat the areas of all spo~s _!_ ~ithin set limi~s d. Check that no S~OIS are too cios- ,o the CCD edge 2. Equations: NON_ 3. Da,a: NONE
. Source c. TOSSBAD.S07 b. FILTERS.S07 c. BORDER.C
. Errors a. Number of spots not equal tO "
b. Spot areas exceed limits c. Spots too close to allowable border .

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E. Identify Spots 2 ~ 7 9 8 ~ ~
1. Procedure a. First spot in tabie is spot X1 b. Last spot in table is spol #4 c. Middle two spots based on horizontal p~sitions are #2 & X3.
-if second spot hor. < third spot hor., then okay else swap them 2. Equations: NONE
3. Da~a a. Gm[i].ident is set to values 1 tnrough 4, in that order 4. Source a. IDSPOTS.S07 5. Errors a. Unable to identify correctly F. Calculate Centers-of-l~,ass lor Each Spot 1. Procedure 2. Equations a. Hori~ontal (sum of all beg x and end x vaiues) horCI~lI = -------------^~~~~~~~~~~~~
(number of runs) ~ (2) ~ (horizontal pixels per mm) ~xample: beg X row end X
Run ~t: ;;4 ;;; ;29 Run ~'2: ~ 15 73 131 Run 7r'3: 113 72 132 Run ~ 114 77 128 Sum of all beg x and end x vzlues =
114 . 129-1 . 115,131-1 .113--. 132-1--114+128-1 = 972 Number of runs = 4 Yori~on~al pixels per mm = 117.6~70583 horC~ = 1.03275 mm NOT~: all runs have been corrected for offsets, (See IV.B.3.A) b. Vertical (sum of all (run rov~s i run lenyth)) verCM = ----------------------~~~~~~~~~~~~~~~
(sum of all run len3ths) ~ (vertical pixels per mm) . _ . . . ... . . ., _ . _ . _ _ . ... _ _ ~ 2~7~5:1.

Example: beg X row end X
Run X1: 123 92 149 Run #2: 120 94 151 Run #3: 121 96 150 Run X4: 122 98 150 Sum o~ all (run rows ~ run lenath) =
92~26+94~31 +96~29~98~28 = 10~34 Sum ol all run lenaths = 26 + 31 + 29 + 28 = 114 Vertical pixels per mm = 101.2658228 verCM = 0.93847149 mm NOTE: All run values have been corrected ~or offsets (see IV.B.3.A).
3. Data a. Cm[i~.realHor set to C~l horizontal position, in mm b. Cm[i].realVer set to CM vertical position, in mm 4. Source a RcALCMS.S07 5. Errors: NONE
G. Correct Spot Centroids ior Lens Distortions 1. Procedure a. Feed each image space CM pair through transform eaùation b. Obtain new CM object space pair 2. Equations The Keratometer uses a fourth-order lens correction. The parameters are derived durino a camera calibration procedure. Ths equation reauires an iterative solution pe,~ormed pr.numCCDlter (2) times. The ~eneral equation is:
(x-xp)- (x-xp)*(11 12*r~*2 13~r~
- + (p1~(r.~*2 2*xbar**2) 2*p2*xbar**2*ybar~2)*(1 ~ p3*r~*2) - ~* (m11 *(x-xc) + m12*(y-yc) . m13*(z-zc)) /
(m31*(x-xc) . m32*(y-yc) ~ m33*(z-zc)) = 0 wnere: xbar = x - xp ybar = y - xp r~2 = xbar~*2 + ybar**2 -This is solved for the x and y translormed (object) points.

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. Data a. Cm~i] realHor/realVer values are transtormed to object space.
4. Source a. DISTORT.S07 5. Errors: NONE
H. Calculate Base Curve Po~ers and Axis Angle 1. Procedure~ ONE
2. Equations The ~ollowing equations delermine the base curve powers and axis angle trom the spot centroids:
x1c = y1c = 0;
x2c = (cm ~1 ] . realHor-cm [0] .realHor) ~ (cm [3] .realHor-cm [2] . realHor);
y2c= (cm[1].realVer-cml0].realVer)+(cm[3].realVer-cm[2].realVer);
x3c= (cm[2].realHor-cml0].realHor)-(cm[3].realHor-cm[1].realHor);
y3c= (cm[2].realVer-cm[0].realVer)~(cm[3].realVer-cm[1].realVer);
bterm = -( (x2c ~ y3b) + (y3c * x2b) - (x3c * y2b) - (y2c * x3b);
cterm = (x2c * y3c) - (x3c ~ y2c);
sterm = bterm*bterm - 4*aterm*cterm;
if sterm close to 0, then set sterm = 0;
sterm = squareroot(sterm);
majorAxis = (-b - s)/(2 ~ a);
minorAxis = ( ~ b - s)/(2 * a);
if minorAxis < majorAxis, then swap the two;
baseCurve1 = dk of cal objec~ / majorAxis;
bas~Curve2 = dk of cal object / minorAxis;
i, sterm = 0, then axis = 0;
e!se Gxis = arctan(-(x2c - majorAxis~2b)/(y2c - majorAxis*y2b));
or âXiS = arctan(-(x3c- rr,ajorAxis~x3~)/(y3c- majorAxis~y3b));
if axis < 0~ then ZGd 180;
ii cylinder < 0.12~, then axis = 0;
3 Da;~
a. B-seCurve1, bas_Curv2 and axis b-termined; in re structure 4. Source a. CALC.S~7 5. Errors NON~ , I. Calculcte Torricity 1. Procedure 2. Equations Torri_ity = abs( ((cm~2].realHor-cm[0~.realHor)-(cm[3~.realHor-cm[1].realHor)) -((sc.vi[2~ .hor-sc.vi[0~ .hor) -(sc.viL3].hor-sc.vi[1].ho,)) ) +

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abs( ((cm[1).realVer-cm~0].realVer)-(cm[3] .realVer-cm[2] .realVer)) -((sc.vi~1 ).ver-sc.vil0) .ver) -(sc.vi~3].ver-sc.vi~2~.ver)) ) where; cm[0..3~ are the centers-of-mass o~ spots 1 through 4, respectively, and sc.vi[0..3] are the centers-oi-macs o~ the same spots from calibration.
if torricity > torric limit, then set torric flag in re structure 3. Data a. Va.torricity value c~mputed b. Re.nonTorric set if TRUE
4. Source a. CALC.S07 5. Errors: NONE
J. Check ~or Resonable Values 1. Procedure a. Test for base curves between 28 and 62 diopters b. Test tor cylinder less than 10 diopters 2. Equations: arithmetic comparisons from above 3. Data: NONE
4. Source a. FILTERS.S07 5. Errors a. Out-of-range error ii any test ~ails K. Que Results 1. Procedure 2. Keep the five most recent successful reiadings b. Take readings until thre~ are within pr.queueRanae c. When threo readinas are wi;hin ranoe, 2ver2ge them d. If any of the three is non-torric, mark reading non-torric 2. Equations a Base curv.es and axis angle are scalar averaged b. Angles may need manipula;ion be~ore combining 3. Da;a a. Re.spher2/.cylindGr/.2xis values calculated . Source a. QUELIE.S07 5. Errors: N3NE
L Read Level Angle 1. Procedure a. Turn projector and alignment LED's off b. Turn level LED's on -- ~4 --, .. . . .
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c. Set threshold value d~ Dummy com nand to IP and delay 30 msec for field soak e. Get a page ot image data f. Turn level LED's off g. Process level image data h. If angle ref is ground and level read oka~, then incorporate into results 2. Equations: NONE
3. Dala: NONE
4. Source a. I~EASURE.C
b. LEVEL.S07 5. Errors a. Image processor returned error bils b. Not enough image da~a c. Unable to process image data M. Store Results 1. Procedure a. Store base curves, axis angle, and stat into storage variable 2. Equations: NONE
3. Data a. OdResults[~/osResults[l, based on which eye and field measured 4. Source a. RESULTS.C
~. Errors: NONE
N. Display Results 1. Procedure 2. Load results into re structure b. Round to desired resolution (0.12~/0.01) c. Convert tO selec~e~ display form^-t (base curves/pos cyl/ne3 cyl) d. Convert results from MATH11 RtAL format to IE_E floatin~ point e. If unils = diopters, then display num~ers f. Display axis angle --5. If uni~s = mm, then display numbers h. If nc,n-torric, then light irregular cornea i_on i. Flash level/degree icons if handle selected or error reading level 2. Equations: NONE
3. Data: NONE
4. Source 2. DISPLAY.C
b. LCD.C
5. Errors: NONE

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It can therefore be seen that the present invention, in its preferred embodiment, achieves at least all the inventions stated objectives. The invention can ta~e many forms and embodiments.
The preferred embodiment is given by way of example only, and not by way of limitation to the invention. The true essence and spirit of this invention are defined in the appended claims, and it is not intended that the embodiment of the invention presented herein should limit the scope thereof.
As a primary example, the present invention can be utilized to determine the curvature of any curved surface which allows reflection to the extent needed for the image processing to function. The device therefore could be utilized to, for example, insure that field ball bearings are being manufactured to the required specifications.
Other uses are possible. Additionally, other features, ~dditions, and enhancements are possible.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1.

A keratometer means comprising:
a portable housing means including a hand grip section;
a projector means in the housing for projecting a pattern of collimated light sources onto a patient's eye;
an imaging means in the housing for capturing and recording received images, including reflection of the pattern of collimated light sources from the patient's eye; and processing means in the housing for analyzing the recorded received images to derive keratometric readings of the patient's eye.
2.
The keratometer means of claim 1 wherein the projector means comprises a plurality of projection assemblies each including a light source, a pin hole, and a lens.
3.
The keratometer means of claim 2 wherein the projection assemblies are positioned circumferentially around an optical axis and angled towards that axis.
4.
The keratometer means of claim 3 wherein each projector assembly is angled at the same angle with respect to the optical axis.

5.
The keratometer means of claim 1 wherein the imaging means comprises an area images consisting of a matrix of pixels, each pixels producing a signal proportional to the intensity of light received at the pixel.
6.
The keratometer means of claim 2 wherein each projection assembly includes a plurality of lights sources.

7.
The keratometer means of claim 6 wherein the plurality of light sources are aligned generally along a plane which is normal to an axis through the pin hole and lens.
8.
The keratometer means of claim 1 further comprising an alignment means for aligning the projector means with respect to the patient's eye, the alignment means including the eye piece for allowing the user of the keratometer means to view the patient's eye and the multiple collimated lights sources from the projector means.

9.
The keratometer means of claim 1 further comprising a fixation means for providing the patient with a light source upon which to fixate.

10.
The keratometer means of claim 1 further comprising a leveling means for automatically confirming whether the housing means is level with respect to a predetermined direction, the leveling means including a chamber at least partially filled with a fluid and a back-lighting source, the image of the fluid in the chamber being captured by the imaging means and the processing means analyzing whether the top level of the fluid is correctly positioned with respect to a frame of reference of the imaging means.

11.

The keratometer means of claim 1 further comprising a ring of one or more light sources which project a ring onto the patient's eye to allow testing of the nature of the eye.
12.
The keratometer means of claim 1 further comprising a display means for displaying information related to the keratometer means and keratometric readings.
13.
The keratometer means of claim 1 further comprising control means for selecting operational modes and functions for the keratometer means.
14.
The keratometer means of claim 1 further comprising battery power means for providing power to the projector means, imaging means, and processing means.

15.
The keratometer means of claim 1 further comprising connection means between a battery power means and a recharging means 16.
A hand held, battery powered keratometer comprising a housing having a hand grip portion, a projection window and a viewing window;
a plurality of projector means positioned in the housing, each projector means oriented to project a collimated light source in a converging mznner through the projection window to impose a predetermined pattern on a patient's eye under analysis;
a first beam splitter means positioned in the housing along the first axis for directing reflections of the pattern received along the axis lo a camera means aligned along a second axis;
the viewing window being a1igned along the first axis allowing a use of the keratometer to directly view the patient's eye through the first beam splitter and projection window;
a fixation means in the housing for projecting a fixation target to the patient's eye along the first axis through the projection window and to the user along the first axis to the viewing window;
control means for operating the projector means and fixation means; and ?rocessing means for deriving keratometric information from the pattern received by the camera means.
17.
The keratometer of claim 16 wherein the pattern is comprised of a center light source, and a plurality of spaced apart collimated light sources surrounding the center of the light source each having an equivalent radial distance from the center light source.
18.
The keratometer of claim 16 further comprising a leveling means for automatically indicating whether the housing is level with respect to horizontal.
19.
The keratometer of claim 16 further comprising a battery power means in the housing for powering the projector means.
20.
The keratometer of claim 1 further comprising a printer means in communication with the processing means to provide a print out of information from the processing means.
21.
The keratometer of claim 16 further comprising a readout means for displaying keratometric information.
22.
The keratometer of claim 16 further comprising a second beam splitter associated with the fixation means passing a light source to the patient's eye as well as directing the light source to the viewing window.

23.
The keratometer of claim 16 wherein the control means comprises one or more push buttons for selecting various functions of the keratometer.
24.
A keratometer means comprising:
one or more collimated light means for producing collimated light beams aimed to converge to a point on an optical axis, each light means located at a fixed distance from the point and from the axis;
a camera means positioned on the optical axis a fixed distance from the point LO receive reflections of the light beams from an object placed along the optical axis slightly nearer the keratometer than the point; and the point and camera means having a telocentric relationship which does not require precise positioning of the object on the optical axis for consistent sized images received by the camera means.
25.
The keratometer means o claim 24 wherein the camera means is a fixed distance from the light means.
26.
The keratometer means of claim 24 wherein the camera means includes an image capturing means for capturing the reflected image of each collimated light beam from the object, and including processing means which calculates the center of the reflected image of each collimated light beam.

27.
The keratometer means of claim 24 further comprising an eye piece positioned along an axis which at some point becomes co-linear with the optical axis 28.
The keratometer means of claim 24 further comprising a fixational light source which is directed along an axis which at some point becomes co-linear with the optical axis The keratometer means of claim 24 further comprising a processing means which analyzes the reflected images of the collimated light beams from the camera means and derives radius of curvature information regarding the object along at least two axes A photo optical means for measurement of the curvature of a curved surface comprising:
a projector means for projecting a pattern of generally identical collimated light sources to converge to an area along an axis, the pattern forming a predetermined geometric arrangement on the curved surface when the curved surface is placed near the point but towards the projector means;
a camera means for capturing the image of the curved surface and reflection of the light sources, the camera means being positioned telecentrically with the point and recording the reflections; and processor means for determining the relative positions of the reflections and calculating at least one radius of curvature of the curved surface from those relative positions.
31.
The photo-optical means of claim 30 wherein the curved surface comprises a convex surface.
32.
The photo-optical means of claim 30 wherein the curved surface comprises a concave surface.
33.
The photo-optical means of claim 30 wherein the curved surface comprises a part of a round object.
34.
The photo-optical means of claim 30 wherein the curved surface comprises a portion of 2 sphere.
35.
The photo-optical means of claim 30 further comprising a means to center the axis with respect to the curved surface.
36.
A method of keratometery comprising:
projecting a plurality of collimated light sources at generally equal converging angles onto an eye;
substantially centering the light sources ground an optical axis extending generally through the center of the cornea of the eye and generally normal to the eye;

apturing a reflected image of the light sources from the eye along the optical axes; and deriving keratometric information from the captured reflected image.
37.
The method of claim 36 wherein the collimated light sources are comprised of solid state light sources directed through a pin hole and a lens.
38.
The method of claim 36 wherein the light sources are positioned circumferentially around the optical axis.
39.
The method of claim 37 further comprising of plurality of solid state light sources which are projected through the pin hole and lens.
40.
The method of claim 36 wherein the capturing of the reflected image comprises capturing by a CCD imager.

41.
The method of claim 36 wherein the pattern includes a peripheral light sources.
42.
The method of claim 41 wherein the peripheral light sources are positioned an equal distances from one another.
43.
The method of claim 36 wherein the keratometric information s derived by calculating the distance between reflections of the light sources from the patient's eye..
44.
A method of deriving the curvature of a curved object comprising:
aligning a camera means along an optical axis in a portable housing, the optical axis extending out of the housing;
positioning collimated light sources to angularly intersect curved surface position along the optical axes outside the housing;
positioning the housing towards the curved surface so that the light sources converge on the curved surface and the optical axis is substantially centered on the curved surface;
aligning the light sources and optical axis toward the user and viewing along the optical axis to center the virtual image of the light source on the curved surface;
projecting collimated light sources onto the curved surface; and reflecting the light source along the optical axis to camera means.
45.
The method of claim 44 wherein the curved surface comprises an eye.
46.
The method of claim 44 further comprising a fixation collimated light source along the optical axis.
47.
The method of claim 44 further comprising an automatic eveling indicator by projecting the image of a fluid within a sealed container to the camera means.
48.
The method of claim 44 wherein the camera means includes an image processing means.
49.
A method of analyzing the curvature of a surface comprising:
capturing a reflected image of a plurality of collimated light sources imposed on a curved surface with a camera means utilizing a telocentric objective lens optical system;
storing the relative location of the center of intensity of each light source received by the camera means; and calculating characteristics of the curvature of the curved surface from the relationship of the locations of the reflected light sources in the image captured by the camera means.
50.
The method of claim 49 further comprising the step of calculating the alignment of a plurality of collimated light sources on the curved surface by analyzing the relationship of locations of the reflected light sources in the image captured by the camera means.
51.
The method of claim 49 wherein the characteristics of curvature of the surface are calculated along defined axes, and the angle between the axes is derived.

52.
The method of claim 49 further comprising the step of calculating the characteristics of curvature by an algorithm utilizing the relationship of the distance between reflected light sources and radii of curvature.
53.
A method of keratometery comprising:
positioning a collimated light source projection means and camera means in a hand held, portable, battery powered housing;
positioning the camera means telecentrically along a reflection pathway extending from the camera means out a projection window means in the housing;
projecting a plurality of collimated light sources at known angles and distances from the projection window out the projection window to converge to an area along the reflection pathway;
moving the housing to an approximate position in relation to the eye so that the projected collimated light sources intersect the eye;
adjusting the housing to more accurately place the reflective pathway generally along the optical axis of the eye;
capturing the reflected images of the collimated light sources with the camera means;
deriving the distance between some reflected images of the collimated light sources with other reflected images of the collimated light sources; and onverting the distances between these reflected images of the collimated light sources to radii of curvature of one or more axes of the eye.
54.
The method of claim 53 wherein the plurality of collimated light sources are converged to the reflection pathway at angles of approximately 21.5°, plus or minus 1°.
55.
The method of claim 53 further comprising converting the radii of curvature into diopter power information for the eye.
56.
The keratometer means of claims 1 whereas the imaging means comprises a CCD camera.
57.
The photo optical means of claim 30 whereas further comprising a hand-held housing substantially enclosing the projector means and camera means.
58.
The keratometer of claim 1 further comprising an alignment means for providing the user with a light source indicating the point at which the patient's eye should be positioned for correct up/down and left/right alignment.