US2158391A - System and apparatus for facsimile telegraphy - Google Patents

Description

R. J. WISE SYSTEM AND APPARATUS FOR FACSIMTLE TELEGRAPHY 6 Sheets-Sheet l INVENTOR R. J. WISE ATT RNEY Filed June 12, 1936 May 16, 1939. R. J. WISE 2,158,391

SYSTEM AND APPARATUS FOR FACSIMILE TELEGRAPHY Filed June 12, 1936 e Sheets-Sheet 2 INVENTOR R. J. wl'ss A ORNEY R. J. WISE May 16, 1939.

SYSTEM AND APPARATUS FOR FACSIMILE TELEGRAPHY GSheets-Sheet 3 Filed June 12; 1936 m n n R.J. WISE MIML 5% RN EY R. .1. WISE 2,158,391 SYSTEM AND APPARATUS FOR FACSIMILE TELEGRAPHY May 16, 1939.

Filed June 12 1956 6 Sheets-Sheet 4 FIG.5

INVENTOR R J. was

SYSTEM AND APPARATUS FOR FACSIMILE TELEGRAPHY Filed June 12, 1956 s Sheets-Sheet 5 I. I I E! INVENTOR 1 R. J.W|SE

III i 1 ms i 21% m $2 mi May 16, 1939. R J. WISE SYSTEM AND APPARATUS FOR FACSIMILE TELEGRAPHY Filed June 12, 1936 FIG. 9

6 Sheets-Sheet 6 INVENTOR RJ. WISE mg A ORNEY Patented May 16, 1939 UNITED STATES PATENT OFFICE SYSTEM AND APPARATUS FOR FACSIMILE TELEGRAPHY Application June 12, 1936, Serial No. 84,935

18 Claims.

The present invention relates to telegraphy and more particularly to improvements in apparatus for transmitting and receiving messages, pictures and other subject matter in facsimile.

A primary object of the present invention is to provide simplified apparatus of a compact nature capable of serving either as a facsimile transmitter or receiver.

In accordance with the present invention a picture, message or other subject matter is transmitted from or received upon a subject matter sheet which is carried by interchangeable copy holders which can be readily placed in operative position in the combined transmitter-recorder or 15 removed therefrom and in the preferred form of the invention, tubular picture or message sheets are carried by interchangeable cylinders. Accordingly, another important object is to provide a facsimile transmitter and receiver having novel means for readily and conveniently supplying messages or pictures in succession for transmission, or message blanks in succession for reception.

A further object is to provide a novel arrangement of the parts of an optical scanning device.

A still further object is to provide a novel wiring system for interconnecting the amplifiers of a combined facsimile transmitter and receiver.

The foregoing and other objects of the invention will appear from the following description of an illustrative embodiment of the invention.

In the drawings:

Fig. l is a front elevational view of a facsimile transmitter-recorder embodying the present invention;

Fig. 2 is a top plan view of the apparatus disclosed in Fig. 1;

Fig. 3 is a sectional elevation taken on line 3-3 of Figs. 1 and 2 as viewed in the direction of the 40 arrows;

Fig. 4 is a sectional elevation taken on line 4-4 of Figs. 1 and 2 as viewed in the direction of the arrows, certain of the parts of the apparatus being shown in non-operating position;

45 Figs. 5, 6 and 'l are fragmentary sectional views taken on the lines indicated in Figs. 1 and 2 to illustrate the arrangement of details of the optical scanning device;

Fig. 8 is a fragmentary detail view in side ele- 50 vation of the scanning stylus;

Fig. 9 is a wiring diagram illustrating the interconnection of the amplifiers and the switching means for connecting the amplifiers in circuit for sending or receiving; and

55 Fig. 10 is a perspective view of a message sheet rolled into a tube for use in the sender or receiver of the present invention.

Referring to the drawings and for the present to Figs. 1 to 4 thereof. In indicates a base'which forms the principal support for the operating parts and driving mechanism of the apparatus and which rests upon a table II or other convenient sub-base. It will be apparent to those skilled in the art that the entire assembly of the apparatus may be readily arranged to lie wholly above the bottom of the base l0, thereby permitting the base l0 to rest directly upon the sub-base II. The base is provided with brackets l2 and I4 serving to support the longitudinal guide member I5, bracket l2 also serving to support one end of an additional guide member 16. The guide member l5, positioned at the rear of the apparatus, is supported between its ends and the guide member I6 is secured at one end to an additional bracket H, which in turn is secured to the base Ill. The guide members l5 and I6 slidably support the longitudinally movable scanning assembly which comprises the optical pickup system for sending messages and the independent stylus 51 which may be employed for r either transmitting or receiving.

The scanning assembly is mounted upon a suitable base member l9 (Figs. 1-4) which is provided with one or more bearing guide blocks 20, the apertures of which slidably engage the 0 guide member l5, and an additional recessed guide block 2| which rests upon the guide member IS. The apertured guide blocks 20 at the rear of the scanning assembly serve as pivot points about which the scanning assembly may be rocked for the purpose of arresting operation of the machine when desired. Movement is imparted to the scanning assembly by means of a rotatably mounted threaded rod 23 which is journalled in bearings carried by the brackets l2 and. H. The base IQ of the scanning assembly has secured thereto a member 24, Fig. 6, to which is connected a flexible arm 25 provided at its free end with an internally threaded half-nut 26, the latter adapted for engagement with the threads on the rod 23.

The subject matter to be scanned which may be messages or pictures, either for purposes of transmission or reception, is carried upon readily interchangeable copy holders preferably in the form of cylinders 28, one of which is illustrated in Fig. 1 of the drawings in the operative position. Each cylinder 28 may comprise an external barrel portion having an outside diameter which will cause it to be operatively engaged by either the transmitting or receiving scanning devices to be described hereinafter. Integral with or inserted within the barrel portion of each cylinder is a concentric shaft 29 which for convenience may be hollow, as shown. Adjustable sleeves 39 secured to the shaft 29 by suitable means, such as the set screws 39 serve to position the barrel axially of the shaft 29 in a desired position. A holder or cylinder 28 is supported prior to the beginning of a scanning operation and is brought into the operative position before the scanning devices by an arrangement which forms an important part of the present invention and which will now be described in detail.

Secured upon the base In and spaced apart a suitable distance, depending upon the desired axial length of travel of the scanning assembly, are two similarly shaped upright members 3| and 32, the essential details of member 32 being best shown by Fig. 7 of the drawings. Adjacent the upper end of each bracket is an upwardly inclined tapering notch 33, the lowermost edge 34 of which slopes rearwardly to cause a cylinder with its shaft 29 resting in these notches to roll rearwardly toward the scanning assembly, thereby ensuring that the cylinder will always be in proper position to be brought into the operative position when scanning is begun. When a cylinder is rotated for scanning subject matter on or attached to its peripheral surface, it is supported between centering points which engage the hollow ends of the shaft 29 to maintain the mandrel in a concentric position. One of these conical points or centers 35 is formed upon the end of a rod 36 which is mounted for reciprocation in a bearing provided at the top of a bracket 37, this style of mounting permitting both rotation and reciprocation of the rod. The rod 36 is urged toward the left as viewed in Fig. 1 by means of spring 38 which engages an upstanding pin 39 secured to the rod. The remaining end of the spring 38 is fixed in any suitable manner, as for example, to the bracket 32 as illustrated in the drawings. Movement of the rod 35 under the influence of the spring is limited by a collar 4! which is preferably adjustable longitudinally of the rod 36. The collar 4| engages the upright 31 to limit travel of the rod. A conical point 42 which is formed at the end of a driven shaft 43 is complementary to the conical point 35, and it is to be noted that as the rod 36 is permitted to move toward the left, the conical points 35 and 42 will enter the ends of the hollow shaft 29 of a cylinder in position in the notches 33. This will raise the cylinder from the notches 33 and position it accurately in alignment with the shaft 43 and the rod 36, and parallel with the path of movement of the scanning device. A resiliently carried friction member 3| (Fig. 4) engages the shaft 29 of a cylinder in position between the centers 35 and 42 and by exerting a slight drag on the shaft, takes up back lash in the gears and also ensures that a pin 5| extending from shaft 29 will remain in contact with a member 52 carried by shaft 43, thereby causing shafts 29 and 43 to turn together substantially as one shaft. A light spring 32' secured on the bracket 32 may serve if desired to ensure that the drum will be grounded to furnish a circuit from the stylus. The rod 36 is provided with a grip portion 44 and the previously mentioned pin. 39 cooperates with a slotted detent or latch member 45 (Fig. 2). The pin 39 moves in an elongated longitudinal slot 46 in the latch member 45 when a cylinder 28 is to be lifted from the brackets 32 and 33 by engagement of the tapered centers 35 and 42 with its shaft 29 into operative position for scanning. In order to hold the rod 36 in its retracted position after the cylinder has been released, the pin 39 may be caused to engage either of the edges 47? formed at or adjacent the end of the detent member 45, by rotating the rod 36 a small amount in either direction after the pin 39 has been withdrawn from the longitudinal slot 46.

The threaded shaft 23 and the cylinder driving shaft 43 are driven from the motor 48, which is preferably some form of synchronous or speed regulated motor. Driving power from the motor is imparted to the shaft 43 through a speed reducing drive 49 of suitable character. The threaded shaft 23 is driven from a pinion 56 on the shaft 43 through a gear train composed of an idler gear 53' and pinion 59', the latter meshing with a gear 59" secured to the threaded shaft 23. The gear ratios of the gearing just described are selected so that the rate of longitudinal travel of the scanning assembly and the peripheral speed of rotation of the cylinder 28 cooperate to produce the desired helical scanning of the subject matter on the mandrel 28. Excellent results are secured in practice for message transmission by selecting these relative speeds so that as the mandrel rotates once, the scanning assembly will move longitudinally a distance of one one-hundredth of an inch.

To provide for a positive but automatically engageable driving connection between the driven shaft 43 and the cylinder 28, a resilient dog clutch is provided which comprises the radially extending pin 5| which projects from the shaft 29 of each cylinder 28 adapted for use in the device, and the driving member 52 pivoted to the shaft 43 (Fig. 2). The driving member 52 is urged against a stop 53 by means of a spring 54, the said spring for the sake of compactness of design partly encircling the shaft 43. It will be understood that the member 52 if rigidly secured to the shaft 43 may be of a yielding nature, thus making it unnecessary to use the spring 54. As the cylinder 28 is brought into its operative position between the centers 35 and 42, the end of the pivoted member 52 engages the pin 5| and ensures positive rotation of the cylinder 28. Shock of the sudden engagement of the arm 52 with the pin on the cylinder shaft is absorbed by the spring 54 which permits the arm to yield momentarily.

Each cylinder 28 is preferably provided with a mark located with respect to the pin 5| or other portion of the clutch so that the spaced or overlapped edges of a message blank can be positioned near this mark. With motors at both stations in synchronism, and in phase or isochronism, the message copy and the message blank will have the same angular position with respect to the sending and receiving scanners. This result is accomplished without use of complicated phase adjusting mechanism.

The scanning assembly mounted upon the longitudinally movable base 59 comprises a photoelectric pickup arrangement cf the kind disclosed and claimed in the copending application of R. J. Wise, Ser. No. 57,019, filed December 31, 1935. In accordance with the present invention the elements of the apparatus disclosed in the application just referred to and other parts operating in conjunction therewith are compactly but accessibly assembled in a manner now to be described. A casing 55 mounted on the base plate I9 encloses the part of the amplifying apparatus and transformers diagrammatically shown in Fig. 9 which is enclosed in the dotted rectangle. The vertical plate 56 (Figs. 5 and 6), forming the wall of the casing, supports an independent stylus 51, as will be hereinafter described, and the principal parts of the optical scanning arrangement. The stylus 51 is available for transmitting or recording. A housing 58, provided with a section 59 hinged at 59 (Fig. 4) to afford convenient access to the parts of the optical scanning arrangement, encloses a part of the lens tube assembly 6| and the photo- cells 62 and 63. Details of the lens tube assembly are shown on an enlarged scale in Fig. '7. The entire housing 58 is connected to the plate 56 by a post 64 and may be removed bodily from the apparatus by unscrewing the thumb nut 68. A lamp 61 is enclosed in a housing 68, the latter being secured to the plate 56 by suitable means.

The scanning head 69 which is a part of the lens tube assembly previously mentioned, is detachably secured to the plate 56 by means of screws II or equivalent fastening means. The scanning head is provided with a detachable portion I2 having an arcuate face 13 which is substantially concentric with the centers 35 and 42. Other replacement portions 12 having arcuate faces of a different radius of curvature may be substituted when desired. A lens tube 14 contains two lenses I6 and I1 and an apertured plate 18 designed and positioned with respect to each other and the lamp 61 so that light from the lamp is concentrated in a spot on the periphery of the drum 28. The approximate configuration of the resulting pencil or beam of light is indicated by the dash lines on Fig. '7 of the drawings. It will be noted that the beam is focused on the aperture in the aperture plate I8 and on the surface of the drum 28. The telescoping sections of the tube ll provide for focus adjustments. A lens tube ill contains lenses 8! and 82 for directing the beam of light reflected from the periphery of the drum 28 onto an aperture 83 formed in the end of the cap 84 which telescopes over the end of the tube I9. Like the tube 14, the tube I9 is made up of telescoping sections which provide for focus adjustments. The photo-cell 62, which is supported from the base plate I9 on a suitable rigid pedestal or bracket, is surrounded by a shield 86 apertured as indicated at 81 to admit the reflected beam of light from the tube 19.

A light chopper 88, interposed between the photo-cell 62 and the aperture 83, is secured upon a rotatable shaft 89 which is driven through a resilient driving connection 9I by motor 92. The shaft 99 is journalled freely in a tubular shaft 94 which in turn is frictionally held in a divided bearing bracket made up of two like parts 96 (Figs. 3 and 4) secured to the plate 56. The secur ng screws 91 for the parts 96 also serve to secure the vertical flange of an elongated motor supporting bracket 98 to the plate 56. The motor 92 is secured to and rests upon the horizontal 'nP Q of the bracket 98. Clamping screws 99 permit adjustment of the frictional grip of the parts 96 upon the sleeve 94. For a purpose to be described, the sleeve 94 is provided with a conveniently disposed handle I80.

The light chopper 88 is in the form of a disc, as illustrated, having a series of equally spaced opening or notches IIII adjacent its outer edge. The number of notches in the disc and the speed of rotation of the disc may vary within wide limits, depending on the desired rate of scanning, the constants of the communication circuits employed between stations, and other factors. An auxiliary lamp I 02 for illuminating the previously mentioned photo-cell 63 is mounted in a housing I82 carried at the end of an arm I83 extending radially from the sleeve 94. The position of the auxiliary source I02 with respect to the chopper teeth or notches is adjustable by means of the handle I already described. In this manner the auxiliary source may be accurately positioned so that its light is cut off by the chopper 88 when the reflected beam from the light source 61 impinges upon the photo-cell 62.

In order that the device may be utilized for recording, the previously mentioned independent stylus 51 is so positioned that it may, when desired, be brought into contact with the surface of a cylinder 28 or a message positioned thereon. To support the stylus a bracket I04, Figs. 1 and 8, is secured to the plate 56. The horizontal flange of the bracket I84 is provided with threaded apertures in one of which is engaged a screw I06. The adjustable supporting base III! to which the s ylus is secured, pivots in a vertical plane about the shank of the screw I96 and its upward movement is y eldably and adjustably resisted by a spring I88 which surrounds a screw I09. Downward movement of the support I0! is limited by a screw III which is threadedly engaged in an aperture in the bracket Iiil.

In operation with the stylus in contact with a message blank on the cylinder 28, gases may be evolved during a chosen recording process and to facilitate the r removal a conduit H2 is provided which has a suitable nozzle II3 positioned above the stylus. The conduit H2 is supported by the walls of the casing 55 and is placed in communication with an exhaust fan or other suction device by means of a suitable pipe or hose I I4.

In order to prevent axial movement of the base I9 when the machine is idle, the base and the parts thereon may be tilted bodily about the previously mentioned supporting bearing blocks 20. Thi is conveniently done by a handle H6 which extends forwardly into a position conveniently reached by an operator. A latch II! is adapted to engage any suitable or convenient projection H8 upon the base I" so as to retain the carriage in its tilted inoperative position.

Fig. 10 of the drawings illustrates a prepared message or a message blank made up of a suitable sheet of paper I28 formed into a tube which fits nicely over a cylinder 28. The seam of the tubular form is preferably gummed or otherwise adhesively joined so that blanks I28 may be made up in advance of their use. It is also within the scope of the present invention to apply message sheets or blanks in any other manner to the cylinders; for example. by elastic bands.

Fig. 9 of the drawings shows diagrammatically the wiring system for interconnecting the amplifiers of the combined transmitter and receiver. The line L, which may be any type of communication channel extending to a remote transmitter and/or receiving station, is connected to one set of contacts of a pair of double pole switches H9 and I2 I. The remaining points or sets of contacts of the switch IZI are connected by conductors I22 to a two-stage amplifier I23 which serves to amplify the output of the previously mentioned photo-cells of the scanning device. The movable switch arms of the switch IZI are connected to a push-pull amplifier I24 and the output circuit of this amplifier is connected to the switch blades of the switch lid. The remaining points of the switch 5 M are connected through a suitable coupling transformer to a push-pull amplifier I25, the output circuit of which is connected to a receiving transformer I26. It will be understood switches H9 and Hi may be combined in a single structure and that the switch blades thereof may be operated from a remote point by any suitable means known in the prior art. It is to be noted that with the switch blades of both switches occupying the positions shown in Fig. 9, the apparatus is ready for transmission. Transmission will then take place by way of the amplifier iZS, conductors I22, the switch ml, the amplifier i2 3 and the switch H9.

With the position of the switch blades reverse the apparatus is in condition for receiving messages from a distant point by way of line L, contact points of switch l2! marked R, amplifier 925 in cascade with the amplifier 925 and by way of conductors ifii to the receiving transformer The secondary of this transformer is in communication with the stylus 51. It will be understood, however, that the secondary of the transformer may be connected with a neon lamp or any other type of recorder which be used. Effective shielding of the coupling transformer i 23 and the amplifier 523 is provided by mounting these in the casing 55. Also, the necessity for long leads between the photo-cells and the amplifier is eliminated.

In operation of the apparatus described above assuming that it is desired to transmit a mesor series of messages, the message sheet as prepared is formed in the manner indicated in Fig. 10 and is applied to one of the cylinders 28 which is placed in the notches of the brackets and 32. Prior to this, motor 48 will have been started so that it is running in synchronism with a like motor at the distant station. The conical center is moved toward the left, as viewed on Fig. l, by releasing the pin 39 from the surface ll with which it is engaged, so that it can travel longitudinally in the slot $6. When this occurs, the mandrel shaft will be lifted from the brackets EZand the cylinder will be properly positioned with respect to the part 72 of the lens tube. Upon completion of transmission, the conical point 35 may be withdrawn by moving the rod 36 to the left and again engaging the pin 39 with the edge ll of the latching plate. lhe cylinder 28 may then be readily removed and another cylinder with a prepared message thereon may be quickly substituted. At this time or upon completion of scanning of the message, the carriage may be disengaged by raising the handle H6 which disengages the half-nut from the proscrew and permits the carriage to be returned to its left hand or starting position.

.i'issinning that it is desired to receive a message or series of messages, a prepared blank formed as shown in Fi g. 10 is placed upon a cylinder 28 in the same manner as for the transmission of messages. In the event that a plurality of messages are to received in succession, a plurality of cylinders will be supplied in advance with blanks. The stylus iii is adjusted so that it engages the surface of the blank when the cylinder is in position between the centers 35 and 42. The procedure just outlii d for transmission is then followed and as explained in connection with Fig. 9 of the drawings, switches H9 and I21! will be moved to their receiving positions.

From the foregoing complete description of the apparatus and its operation, it will be seen that a compact and efficient combined transmitter and receiver is provided by the invention for transmission and reception of messages in facsimile.

While the invention has been explained and described in detail in connection with an illustrative embodimet thereof, it is to be understood that the invention may be embodied in other forms and, therefore, the invention is not limited except as indicated by the terms and scope of the appended claims.

What is claimed is:

1. In apparatus for facsimile telegraphy, the combination of a copy holder having provision for receiving a blank in a given phase position thereon, a member operating continuously at a desired scanning speed, a movable support adapted to receive said holder, and driving means associated with said member and adapted to engage said holder when said holder is operatively received by said member and said support upon movement of the latter.

2. In apparatus for facsimile telegraphy, the combination of a subject matter holder, means to support said holder prior to a scanning operation, said holder having concentric. support engaging mcans, supports for supporting said holder during a scanning operation adapted to cooperate with said support engaging means on said holder to thereby remove said holder from said first named supporting means, and driving means including means adapted to engage said holder to impart driving movement thereto.

3. The combination defined in claim 2 wherein said subject matter holder is in the form of a cylinder removable from the said apparatus and interchangeable with like cylinders.

4. In apparatus for facsimile telegraphy, the combination of a removable message cylinder having provision for receiving a blank in a given phase position thereon, driving means including a member operating continuously at a desired scanning speed, a movable support for said cylinder, said driving means adapted for engagement with said cylinder when said cylinder is operatively received by said support upon movement thereof.

5. In apparatus for facsimile telegraphy, the combination of a removable message cylinder having provision for receiving a blank in a given phase position thereon, a member operating continuously at a desired scanning speed, supporting and driving means associated with said member, said driving means adapted to couple said cylinder to said member when said cylinder is operatively received by said supporting means.

6. In apparatus for facsimile telegraphy, the combination of a removable message cylinder, a stationary supporting means to receive said cylinder before and after a scanning operation, a member operating continuously at a desired scanning speed, driving means associated with said member and supporting means for holding said cylinder in position during a scanning operation, said driving means adapted to couple said cylinder to said member when said cylinder is operatively received by said second named supporting means in preparation for a scanning operation.

7. In apparatus for facsimile telegraphy, the combination of a removable message cylinder, a stationary supporting means to receive said cylinder before and after a scanning operation, a member operating continuously at a desired scanning speed, a clutch member resiliently mounted on said member, said member being formed at its end to support said cylinder in position during a scanning operation, and a clutch pin on said cylinder to cooperate with said clutch member when said cylinder is operatively supported by said first named member in preparation for a scanning operation.

8. A facsimile telegraph transmitter-receiver comprising message cylinder supporting and driving means designed to receive interchangeable message cylinders, a scanning device, guide means, said device being supported thereon in a manner to permit tilting movements thereof and movement in a direction longitudinally of a cylinder operatively positioned by said first named means, screw means to propel said scanning device, and a resiliently mounted screw threaded mermber secured to said scanning device and engageable with said screw means upon tilting of said device into its operative position.

9. In a facsimile telegraph transmitter, a supporting base, a photo-electric pickup device comprising a casing secured to said base and having a wall, a housing secured to said wall, a photosensitive device in said housing, an exciting lamp secured to said wall, a scanning head secured to said wall, and a pair of light conducting tubes extending from said scanning head to communicate with said exciting lamp and said photo-cell, respectively, a serrated light chopper within said housing and a driving motor for said chopper secured to said base.

10. A photo-electric pickup device for a facsimile telegraph transmitter comprising two similar light sensitive cells and circuits joining said cells to an output circuit, a source of light and means for modulating said light in accordance with given subject matter, means for projecting said modulated light onto one of said cells, a rotary light chopper comprising a notched disc for interrupting light from said source, a second light source for intermittently illuminating the other of said cells through said chopper and means for supporting said last named light source, said supporting means permitting adjustment of said source circumferentially of said disc whereby the time of interruption of light from said sources may be varied with respect to each other.

11. A photo-electric pickup device for a facsimile telegraph transmitter comprising a pair of similar photo-electric devices and means to combine their output, a light source and means for directing picture modulated light from said source on one of said devices, an auxiliary light for illuminating the other device, a light chopper comprising a circular member having circumferentially spaced openings to intermittently transmit light from, said sources to said cells, a rotatable shaft on which said circular member is mounted, a support for said auxiliary light source sleeved on said shaft whereby to permit adjustment of said support circumferentially of said circular member.

12. In a system for facsimile transmission and reception, a message circuit, terminal apparatus utilizing said circuit comprising at each terminal station a pickup device and a recording device, means common to both said devices for producing scanning movement with respect to a message holder associated with said devices, a common amplifier for said devices, an additional amplifier for said receiving device, and switching means adapted to connect said message circuit to said pickup device through said first named amplifier for transmitting over said message circult and to connect said message circuit to said recording device through both said amplifiers for reception.

13. Facsimile telegraph apparatus comprising copy holder supporting means, a movable sup port and a scanning device on said support including photo-electric pickup means, means for moving said support to produce a scanning operation, a preamplifier carried by said support adjacent said pickup means and relatively short electrical conductors interconnecting said prev amplifier and said pickup means to thereby facilitate effective shielding and eliminate the necessity for long leads susceptible to interference.

14. In a system for facsimile transmission and reception, transmitters and receivers adapted for interconnection by communication circuits, said transmitters and receivers each comprising a movable member, a removable message holder and a scanning device associated therewith, said movable members operating continuously in phase at a desired scanning speed, and driving means associated with each of said members and adapted to engage its associated message holder in a manner to insure a fixed position of said holder with respect to said member whereby messages secured to holders throughout the system will occupy the same relative position with respect to an associated scanner.

15. Facsimile telegraph apparatus comprising means to support a message sheet bearing a color changing substance, means to scan said sheet, said means being adapted to effect removal of portion of said color changing substance during recording, and suction means disposed adjacent the scanning point of said scanning means on said sheet whereby to remove the substance released during scanning of the sheet.

16. In combination, a. recording blank treated with a substance capable of changing color upon application of an electrical potential, an electrically conductive support for said blank, a stylus adapted to cooperate with said blank, means for progressively changing the location of the stylus on said blank, means to supply said stylus with potentials representing scanned subject matter, a conduit having an opening adjacent said stylus, and an air exhausting device in communication with said conduit whereby to remove fumes released during scanning of the blank by the stylus.

17. Facsimile telegraph apparatus comprising means to support and move a message blank bearing a color changing substance, a stylus and means to cause said stylus to scan said blank, means to supply said stylus with potentials representing the scanning of transmitted subject matter, a conduit having an opening adjacent the point of contact of said stylus on said blank and an air exhausting device in communication with said conduit whereby to remove fumes released during scanning of the blank by the stylus.

18. Facsimile telegraph apparatus comprising a rotatable copy holder, a recording blank on said holder treated with a substance capable of changing color upon application of an electrical potential, a movable support and a stylus on said support to contact said blank, means for moving said support to produce a scanning operation, a conduit having an opening adjacent the point of contact of said stylus on said blank, and an air exhausting device in communication with said conduit whereby to remove fumes released during scanning of the blank by the stylus.

RALEIGH J. WISE.

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