US3183815A - Illumination device - Google Patents

Description

BEiiO Qt'hl May 18, 1965 N. s. KAPANY ETAL ILLUMINATION DEVICE 2 Sheets-Sheet 1 Filed March 12, 1962 INVENTORS Norincler Sv Kopuny David F .Cupelloro Ralph G. Ostensen BY fla/w *W ATTORNEYS "Bl QB-IE y 1965 N. s. KAPANY ETAL 3,183,815

ILLUMINATION DEVICE Filed March 12, 1962 2 Sheets-Sheet 2 Light Source arawww/ma IN V ENTOR S Norinder S. Kupony David F.C0pel|or0 Ralph G.Ostensen ATTORNEYS United States Patent 3,183,815 ILLUMINATION DEVICE Narinder S. Kapany, Woodside, and David F. Capellaro,

Belmont, Calif., and Ralph G. Ostensen, Morton Grove,

Ill., assignors, by mesne assignments, to SCM Corporation, a corporation of New York Filed Mar. 12, 1962, Ser. No. 178,983 Claims. (Cl. 95-73) This invention relates to illumination devices and, in particular, to illumination devices for use in making photographic exposures or contact prints on photosensitive paper of image bearing sheets such as printed or typed pages. More specifically, this invention relates to illumination devices of the type described above incorporating edgelighted illuminating panels composed of light transmitting fibers.

Many types of photocopying exposure devices can be found on the market today but most are too cumbersome to be easily moved from one place to another and may include liquid developing baths which make moving the device a rather hazardous operation. A great number of these machines are equipped with inferior light distributing elements and, as a result, faded out areas and hot spots frequently occur on the copies, making good copy reproduction difiicult. The large size of their light distributing elements makes it awkward (and, occasionally, entirely impossible) to obtain an exposure of a page close to the binding of a heavily bound volume without permanent injury to its backing.

While edge-lighted, wedge-like prisms have been provided heretofore for illumination and photocopy purposes, in attempts to overcome the defects inhering in conventional photocopying devices as is shown for example, by United States Patent Nos. 2,247,737, issued July 1, 1941 to Weeks for Inspection Apparatus; 2,347,665, issued May 2, 1944 to Christensen et al. for Internal Reflection Lighting Means; and 2,511,102, issued June 13, 1950 to 'Clouser for Photocopy Device Having a Translucent Prism Support; such devices have not provided the uniformity of light distribution essential to a practical contact exposure device, but have invariably produced hot spots on the edge of the copy paper adjacent the light source and improperly illuminated, faded out areas along the other edges.

It was also known, heretofore, to employ a group formation of light transmitting fibers to transmit an optical image. United States Patents 1,848,814, issued March 8, 1932 to Allen for Image Forming, Transmitting, and Reproducing Apparatus; 2,122,750, issued July 5, 1938, to Nicholson for Line Television and 2,825,260, issued March 4, 1958, to OBrien for Optical Image Forming Devices are exemplary of the prior art structures proposed for this purpose.

This invention which includes an edge-lighted panel composed of a large number of light transmitting fibers combines the desirable features of edge-lighted panels and of light transmitting fibers and, as a result, provides an edge-lighted panel photocopier which is easily manufactured, has none of the disadvantages inherent in conventional hotocopiers, and has a uniformity of light distribution across the copying surface unattainable by the prior art photocopying devices.

The primary object of this invention is, therefore, the provision of a vastly superior light distributing element which will eliminate all faded out areas and hot spots on photosensitive paper when it is employed in a photocopying exposure device.

Another object of this invention is the provision of a relatively simple photocopying exposure device which is light in weight and comparatively inexpensive to manufacture.

Patented May 18, 1965 Still another object of this invention is the provision of a photocopying exposure device which-may be used to copy the pages of a book or other bound volume without injury to the backing of the book or volume.

These and other objects of the present invention will become more fully apparent from the appended claims and the descriptive text that follows.

Basically, the apparatus consists of a rectangular, and somewhat wedge-shaped light conductive prismatic element together with a support cover, a light box, and a timer. The material to be copied or exposed is inserted between a lateral face of the light conductive prismatic element and the cover along with a sheet of photosensitive paper. The cover is then closed and a timer control turned on. After a predetermined exposure time interval, the timer automatically shuts off the machine and the original and copy may be removed. The same procedure is used when copying the pages of a book except that the cover of the device is removed and the book is held down upon the light emitting surface of the light conductive element with the photosensitive paper between the page of the book and the element.

The invention will be more easily understood by referring to the following drawings wherein:

FIGURE 1 is a perspective view of a photocopy device embodying the principles of the present invention, showing it in the condition in which it is used to copy a single flat sheet;

FIGURE 2 is a sectional view of the photocopy device taken substantially along line 22 in FIGURE 1;

FIGURE 3 is a perspective drawing of the light conducting element as seen from above;

FIGURE 4 is a diagrammatic cross section of the light conducting element; and

FIGURE 5 is a sectional view of the light conducting element taken substantially along line 55 of FIGURE 3.

FIGURES 1 and 2 show a complete physical embodiment of the invention. An original 10 to be copied and a sheet of photosensitive copy paper 12 are inserted as a two-ply laminar assembly between a pivoted cover 14 and an upwardly facing, light emitting surface 15 of a light conductive element 16. Element 16 is a wedge-like prismatic body formed of a large number of slender, elongated fibers 17 (see FIGURE 5) of light transmitting material which, in itself or in cooperation with a coating material is totally internally reflective and in the preferred embodiment, is methyl methacrylate (or as it is commercially known, Lucite). Element 16 will hereinafter be referred to as a fiber wedge for simplicity. The invention is not, however, restricted to Lucite, as any rigid light conductive material such as glass, fused quartz or any of the transparent plastic compositions which, in themselves or when coated with a material whose index of refraction is significantly different than the fiber exhibits the phenomenon of total internal reflection.

With the original .10 and the photosensitive paper 12 in place, the top cover 14 is lowered until a compression pad 18 (see also FIGURE 2) of plastic foam or sponge rubber compresses sheets 10 and 12 against light emitting planar surface 15 of fiber wedge 16. Top cover 14 is then locked in place by latch 20 and timer 22, located in light box 24, is turned on.

As is most clearly shown in FIGURE 2, located inside of light box 24 is a tubular fluorescent lamp 26 which is covered by a vinyl sleeve 28 circumferentially lined with numerous graduated fine black circles (not shown) at predetermined axially spaced intervals. Sleeve 28 is of a conventional construction which is frequently used on tubular fluorescent lamps to insure that even light distribution is attained along the full length of the tube.

When timer 22 is turned on, fluorescent lamp 26 is instantly lighted. After the proper length of time necessary to expose the photosensitive paper 12 has elapsed, timer 22 automatically shuts off the machine and the exposed copy paper may be removed.

The machine may also be set up to copy a page of a book. In this operation top cover 14 is removed by lifting hinge pins 34 and 36 (FIGURE 1) out of slotted brackets 38 and 40. The photosensitive paper 12 is then placed on light emitting surface 52 of fiber wedge 16 and the page to be copied is placed thereon. Timer 22 is then turned on and, as in single copy reproduction, the automatically timed exposure of the photosensitive paper will result in a perfect copy. It may be helpful to press down firmly on the book to insure that the photosensitive paper 12 is absolutel flat, which it must be to avoid blurred edges and distortion in the reproduction of the printed matter closest to the page edge nearest the binding of the book. The fiber wedge 16, due to its relatively sharp edge, fits easily between the pages of the book closely adjacent the binding without injury to the backing.

Generally, the structure of the apparatus is simple. Light box 24 may be constructed of sheet or die cast metal or of wood, metal being preferred for a more sturdy construction. Top cover 14 and the support 44 for fiber wedge 16 may be made of the same material as light box 24. The wiring of the apparatus is very simple and follows standard methods. Electric power is supplied from an AC. outlet through a plug 45, a switch (not shown) controlled by timer 22, and a transformer 46 to the input terminals of lamp 26. Lamp 26, vinyl sleeve 28, transformer 46 and timer 22 are standard items and may be of any commercially available construction.

An important item to note at this point in relation to fluorescent lamp 26 is that the light emitting portion of the lamp should be longer than light receiving edge 47 of fiber wedge 16 and the diameter of the lamp should exceed the width of the edge to assure uniformity of light concentration over the entire surface of the edge and thereby prevent faded out areas on the portions of the copy paper overlying the light emitting surface of fiber wedge 16 adjacent its lateral outside edges 48.

The most important part of this invention is the novel formation of the fiber wedge 16 which embodies a very special construction and arrangement of light reflecting and diffusing surfaces which, it has been discovered, gives a more uniform lighting over the entire copying surface 15 than any other design known to applicants. Referring now to FIGURES 3-5, Wedge 16 is formed from a large group of cylindrical, slender, light transmitting fibers 17, which are bound and sealed together by a binding material such as an epoxy base whose index of refraction is sufficiently different than the fiber to produce total internal reflection. A soda-lime glass coating may be provided about the cylindrical surface of each fiber to prevent light leakage between adjacent fibers. The diameter of the fibers 17 is preferably in the order of .001" to .002". This dimension per se is not critical but will depend upon the particular application of the invention. In no circumstance, however, should the diameter of the fibers 17 be so small as to approach the wave length of light.

Fiber wedge 16 is a wedge-like prism having four lateral planar faces 15, 47, 50 and 56. Faces 50 and 56 are parallel and are normal to the light receiving edge face 47 which they intersect at lines A and E, respectively. As is best shown in FIGURE 4, fibers 17 are actually elongated cylinders being of uniform transverse cross section, terminating, at one end, in elliptical end faces lying in the plane of light emitting face 15 and at their opposite ends in circular end faces lying in the plane of face 47. Face 15 intersects surface 50 at line D at a large obtuse angle and surface 56 at line C at an acute angle. It will be readily apparent that the acute angle formed by the intersection of surfaces 15 and 56 is sufliciently small to permit insertion of fiber wedge 16 be tween the pages of a book with the line of intersection C closely adjacent its binding without injury to the backing and, at the same time, is sufficiently large for structural strength and rigidity. The cylindrical walls of fibers 17 and their circular end faces lying in the plane of face 47 are all highly polished. The elliptical end faces of fibers 17 lying in face 15 are uniformly roughened, as by sand blasting, and therefore function as light diffusers.

FIGURE 4 illustrates the progress of four typical light rays a, b, c, and d, through four separate typical fibers 17a, 17b, 17c, and 17d of fiber wedge 16. The size of fibers 17 as shown in FIGURE 4 is greatly exaggerated to clearly show the path of the rays. Ray a enters fiber 17b through its circular end face lying in the plane of edge face 47 and passes to the interior of this typical fiber. Ray a is then reflected between oppositely disposed upper and lower peripheral surface portions of fiber 1712 until it reaches the roughened elliptical end face of fiber 17b lying in light diffusing surface 15 where it is broken up and emitted from surface 15 in a dispersed pattern.

Rays b and d follow paths in fibers 17a and 17d similar to that described above with reference to ray a. Ray c travels directly from edge 47 through fiber to light emitting face 15 where it is similarly broken up and scattered. Rays a, b and c are typical of the rays necessary for light to emerge from surface 15 in a uniform pattern.

It is important to note that each of the fibers 17 is optically independent. Thus, light entering edge 47 is trapped in the individual fiber and is transported without loss to the light emitting surface 15 of the wedge. As is readily apparent from FIGURE 4, the light entering edge 47 is, because it does not leak from one fiber to another, distributed over surface 15 in a highly uniform manner. The roughened surface 15, of course, breaks up the light and disperses light rays impinging on it and further increases the uniformity of light distribution. The uniformity of distribution achieved by a fiber wedge in accordance with the principles of the present invention is, in fact, of an order heretofore unattainable in an edgelighted panel.

The specific dimensions of one practical embodiment of fiber wedge 16 are shown in FIGURE 4.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

l. A book and document copying device, comprising:

(a) a wedge-shaped, light conductive prismatic element composed of a group of slender, elongated, internally reflective, rectilinear light transmitting fibers arranged in juxtaposed, parallel, side-by-side relationship to define a wedge-like prism having substantially planar, spaced apart, parallel, first and second faces, a third, substantially planar, light receiving face normal to and intersecting said first and second faces, and a fourth, substantially planar, light emitting, original and copy sheet supporting face intersecting said first face in an acute angle and said second face in an obtuse angle, a first end of each of said fibers terminating in a plane coinciding with said light receiving face and the second end of each of said fibers terminating in a plane coinciding with said light emitting face;

(1)) means for supporting said prismatic element with said fourth face oriented substantially horizontally;

(c) a tubular fluorescent lamp mounted closely adjacent the third light receiving face of said prismatic element, said lamp being so sized and so oriented pattern light rays impinging on .said second ends from relative to said third face that the projection of the interiorly of said fibers. light emitting surface of the lamp upon the plane of 4. The illuminating panel of claim 1 wherein the first said third face envelops said third face; and ends of said fibers and the peripheral surfaces of said (d) a timer operatively connected to said lamp, said 5 fibers are highly polished.

timer being selectively activatable to automatically 5. The book and document copying device defined in maintain said lamp energized for a predetermined, claim 1, together with a coating for said fibers, said coatvariable time interval to thereby expose a photosensiing having an index of refraction significantly different tive copy sheet on said fourth face for said predeterfrom the refractive index of the fibers to cause said fibers mined interval. 10 to have total internal reflection.

2. The book and copying device defined in claim 1,

together i References Cited by the Examiner (a) a cover pivoted to said support means and over- UNITED STATES PATEN S lying said fourth face;

(b) a resilient compression pad fixed to the lower side 15 gigg 22; Of Sald and 2,825,260 3/58 OBrien 88-1 (0) means for latching said cover to said support 3 043 910 7/62 Hicks means to thereby engage said compression pad with said fourth face to maintain in contact with said OTHER REFERENCES face a document to be copied and a copy sheet placed 20 Publication, RCA Technical Note No. 188, RCA Laboon said face. ratories, Princeton, NJ.

3. The illuminating panel of claim 1 wherein the sec- 0nd ends of said fibers are roughened to break up and EVON BLUNK Primary Examiner thereby emit to the exterior of said panel in a dispersed JOHN M. HORAN, Examiner.

Claims (1)

1. A BOOK AND DOCUMENT COPYING DEVICE, COMPRISING: (A) A WEDGE-SHAPED, LIGHT CONDUCTIVE PRISMATIC ELEMENT COMPOSED OF A GROUP OF SLENDER, ELONGATED, INTERNALLY REFLECTIVE, RECTILINEAR LIGHT TRANSMITTING FIBERS ARRANGED IN JUXTAPOSED, PARALLEL, SIDE-BY-SIDE RELATIONSHIP TO DEFINE A WEDGE-LIKE PRISM HAVING SUBSTANTIALLY PLANAR, SPACED APART, PARALLEL, FIRST AND SECOND FACES, A THIRD, SUBSTANTIALLY PLANAR, LIGHT RECEIVING FACE NORMAL TO AND INTERSECTING SAID FIRST AND SECOND FACES, AND A FOURTH, SUBSTANTIALLY PLANAR, LIGHT EMITTING, ORIGINAL AND COPY SHEET SUPPORTING FACE INTERSECTING SAID FIRST FACE IN AN ACUTE ANGLE AND SAID SECOND FACE IN AN OBTUSE ANGLE, A FIRST END OF EACH OF SAID FIBERS TERMINATING IN A PLANE COINCIDING WITH SAID LIGHT RECEIVING FACE AND THE SECOND END OF EACH OF SAID FIBERS TERMINATING IN A PLANE COINCIDING WITH SAID LIGHT EMITTING FACE; (B) MEANS FOR SUPPORTING SAID PRISMATIC ELEMENT WITH SAID FOURTH FACE ORIENTED SUBSTANTIALLY HORIZONTALLY; (C) A TUBULAR FLUORESCENT LAMP MOUNTED CLOSELY ADJACENT THE THIRD LIGHT RECEIVING FACE OF SAID PRISMATIC ELEMENT, SAID LAMP BEING SO SIZED AND SO ORIENTED RELATIVE TO SAID THIRD FACE THAT THE PROJECTION OF THE LIGHT EMITTING SURFACE OF THE LAMP UPON THE PLANE OF SAID THIRD FACE ENVELOPS SAID THIRD FACE; AND (D) A TIMER OPERATIVELY CONNECTED TO SAID LAMP, SAID TIMER BEING SELECTIVELY ACTIVATABLE TO AUTOMATICALLY MAINTAIN SAID LAMP ENERGIZED FOR A PREDETERMINED, VARIABLE TIME INTERVAL TO THEREBY EXPOSE A PHOTOSENSITIVE COPY SHEET ON SAID FOURTH FACE FOR SAID PREDETERMINED INTERVAL.

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