US2082692A - High speed telepicture system - Google Patents

Description

June 1, 1937. I w. e. H. FINCH 2,082,692

HIGH SPEED TELEPICTURE SYSTEM Filed March 9, 19156 2 Sheets-Sheet 1 i 66 63 21 62--@ l0 OAMPLIFIERY: v l'l'l'l'l'l'fil'l'l'F- Q 7 5 4 54 56 I AMPLiFlER 14 15 15 20 AND M 15 4 I MODULATOR MODULATOI% IZRANSMITTE W 10 32 42 2 26 4s 33 T V v 68 LINEAR A.F. R42 27 355; I OSCILLATOR 05CILLATOR V'VOLTS INVENTOR W/zU/JM 6. H. F/NCH ATTORNEY June 1, 1937. w. ca. H. FINCH 2,082,692

HIGH SPEED TELEPICTURE SYSTEM Filed March 9, 1936 2 Sheets-Sheet 2 MARGINAL RECEIVER l y QSFOAMPLIFIER f 6" OOSCILLATOE Q2227)! ,103

110 INVENTO I/V/ZZMJM 61H F/IVOL/ BY g 2 1 I ATTORNEY 1'. e. Ml)

li'ntcnted dune Iii This invention. relates to teiepic'ture sys' more particularly, relates b9 high speed ture communication by elec ronic scannin Ecctrical telepicture signals, prior syste s employed mechanical scanning operations whereby a narrow beam of light was traced over the pioture elements and. corresponding variations in the light beam intensity were converted to telepicture signals by photoelectric means. In some systems the picture record was mounted upon a drum; in other systems the picture sheet was successively advanced past an oscillating scanning means which moved transversely with respect to he sheet whereby successive transverse scanning operations were perfected. Corresponding scanning operations were produced at the receiving station in synchronism with the transmitter scan ner for composing a telepicture reproduction. I

The speed of operation of prior telepicture systems was limited by the mechanical scanning op erations and the requirements for maintaining the transmitter and receiver scanning mechahism in perfect phase synchronization. The ineria of the moving mechanical components and the mechanical synchronizingoperations have limited these systems to speeds of the order of 100 to 150 lines per minute for quality reproduction. I contemplate eliminating substantially all of the mechanical scanning and synchronizing elements in a telepicture system, which permits much higher transmission speeds.

In carrying out my present invention, a cathode ray tube is used to generate a scanning beam which is focused upon a picture film. The beam is caused to oscillate across the film so as to successively traverse the picture elements whereby a photoelectric cell may be actuated. The film is automatically advanced by an amount equal to the width of a scanning line at the end of each scanning operation. A synchronizing impulse is simultaneously generated for advancing a corresponding receiving film at a remote station. Each successive line of the receiving film is exposed to a cathode ray image of the telepicture signals from the transmitting station in a manner to be described in detail hereinafter. A telepicture reproduction is had with either a half tone or con-- tinuous tone shading as will be set forth.

Accordingly. an object of my invention is to provide a novel telepicture system.

Another object of my invention is to provide a novel telepicture system utilizing electronic scanning and synchronization operations.

Still another object of my invention is to pro vide a novel electronic high speed. telepicture sys- A further object of my invention is to provide a novel continuous high speed telepicture system.

These and other objects of my invention will become apparent in the following description in connection with the drawings in which:

Figure 1 is a schematic illustration of a preferred embodiment of an electronically scanned telepicture system in accordance with my present invention.

Figure 2' is a characteristic curve of the linear sweep oscillator voltage output.

FigureB is a schematic representation of the scanning operation of the picture film during transmission.

Figure is a perspective illustration of a preferred photoelectric tube for translating the scanhing beam picture impulses to corresponding telepicture signals.

Figure 5 is a graphical illustration of a typical telepicture signal for a single line of scanning.

Figure 6 is a schematic diagram of an electronically scanned receiving telepicture system for translating the telepicture signals of the transmitter in Figure 1.

Figure 7 is a representation of the scanning operation during the reception of the telepicture signals.

Figure 8 is a diagrammatic representation of a preferred light filter or screen at the telepicture receiver.

Referring to Figure 1, the cathode ray tube It) generates an electron beam II which is caused to traverse a fluorescent screen l2 at one end of the tube id. The generation of the electron beam ill is familiar to those skilled in the electronic art and is diagrammatically illustrated. The cathods i3 is heated by the heater M which is connected to a suitable battery supply, not shown. The first anode i5 concentrates the emitted electrons into an electron beam. The high voltage anode it accelerates the electrons of the beam it which. passes between the electrostatic defleeting plates Ei-ifi and ISL-2U, to the fluorescent screen l2. A high voltage direct current potential source 2! supplies the operating potentials for the electrodes of the cathode ray tube ID. A potentiometer 22 is connected across the battery 2i. The high voltage anode I6 is connected to the positive end of the potentiometer 22, which end is also connected to ground potential in my preferred embodiment. The first anode I5 is connected to a suitable intermediate positive potential by variable contact 23. The control grid l deflecting plates sweep characteristic curve 5 across screen I2.

-right to left of the beam Na.

25 is suitable negatively biased by tap 24 on the potentiometer 22. Deflecting plates I! and I9 are directly connected to ground potential and accordingly assume the same potential as anode I6. Deflecting plate I3 is directly connected to ground. The deflecting plate 20 is connected to ground through a high resistance 26. All the deflecting plates I! to 20 accordingly have a common static potential which is at ground potential, an operating expedient commonly employed.

The output of a linear sweep oscillator 21 is connected to deflecting plate 20 by a connection lead 23. The deflecting plates I9 and 20 deflect the electron beam II horizontally; the vertical III8 are both at ground potential and are ineffective in deflecting the beam. The linear sweep oscillator 21 causes the electron beam II to periodically sweep horizontally across the fluorescent screen I2. Figure 2 is the linear illustrating how the voltage applied between deflecting plates I3 and 20 varies with time. The linearly rising portion III of the curve corresponds to the constant rate at which the beam II is transversely moved The return portion 3I of the curve corresponds to the rapid return of the beam to the opposite end of the screen I I after the completion of its periodic traverse. The time interval represented by intercepts a--b of Figure 2 corresponds to the time in which beam II is uniformly swept horizontally across the fluorescent screen I2. The shorter time intercept bc represents the rapid return interval of the beam for its periodic excursion.

The electron beam II produces a spot of light upon the fluorescent screen I2. The light beam 32 generated at the fluorescent screen I2 is usd as a scanning light beam for the picture film 33 to be transmitted. The light beam 32 is focused by a lens. system 34 upon a narrow portion or line segment of the film 33. The fllm 33 alters the intensity of the light beam 32 passing thru it according to the shading of the picture elements being transmitted. A photoelectric cell 35 intercepts the beam 32 and generates electrical signals varying in accordance with the elemental shading of the film 33.

Figure 3 is a schematic illustration of the manner in which the electronic scanning is performed in accordance with my present invention. The film 33 is somewhat narrower than the diameter of the face I2 of the cathode ray tube I0. Dashed line Ila represents the excursion, transverse to the film 33, of the electron beam II across the fluorescent screen I2. It will be understood that the trace of the electron beam Ila upon the fluorescent screen I2 will be visually evidenced as a brilliant line of light. The excursion a--b' of the path IIa from right to left, corresponds to the time interval a-b of Figure 2. The return sweep represented by the time interval b-c corresponds to the return sweep b--a, from The portion ac' of the beam Ila corresponds to the electronic scanning period for the picture film 33. The

portion c-b' of beam Ila corresponds to the synchronizing period to be hereinafter described in detail.

The fluorescent screen I2 is designed to have a low persistence so that the excursion of the electron beam across the path I I a will not produce a continuous line of light but rather a moving point so that the beam of light 32 projecting through the film 33 will correspond to the elemental shading of the picture intercepted by the path of the beam. The moving should be brilliant diameter.

33. tures are to be scanned If the transmitted picwith a detail correspond ingto lines per inch, then the diameter of the focused scanning point upon film 33 will correspondingly be one-hundredth of an inch. It is important that the persistence of the fluorescent screen I2 be low so that an effective moving scanning point or beam 32 is projected through film 33 to insure the generation of telepicture signals in accordance with the elemental shading of the picture.

The photoelectric tube 35 which I prefer to employ is illustrated in Figure 4. Tube 35 comprises two photo-sensitive cathodes 36 and 31. The cathode 36 responds to the light beam projecting through the film 33 corresponding to the portion a'-c of Figure 3 and represented thereon by the dotted section 36. The photosensitive cathode 31 is shorter in length and is represented by the dotted section 3'! in Figure 3 and corresponds in length to the portion c'-d of the light beam Ila. Photoelectric tube 35 has a common anode 3B.

The telepicture signals generated between the electrodes 36-38 of tube 35 are conducted to an amplifier and modulator stage 40 by loads 4 I--42 (Figure 1). An audio frequency oscillator 43 is impressed upon amplifier-modulator stage 40 by leads -45. The frequency of oscillator 43 may for example be 3000 cycles. The type of modulator at stage 40 which I prefer to employ is commonly termed screen grid modulation. As will be understood by those skilled in the art, signals at the output 46-4I of stage 40 will be at a minimum intensity when a dark picture segment is being transmitted and a large signal intensity will correspond to a light picture segment. Figure 5 is a graphical representation of a typical signal which may be produced at the output 46-4'I of stage 40. The time interval a"-c of Figure 5 represents one scanned line of the picture on film 33. The ordinate E is the relative voltage intensity of the telepicture signal.

The alternating current curve 50 represents the audio frequency carrier of the signal, namely 3000 cycles. Figure 5 is a schematic illustration and is accordingly not drawn to scale. The envelope SI of the carrier 50 represents the telepicture modulations superimposed upon the audio carrier 50. The envelope to the horizontal axis as will be evident to those skilled in the art. I sented by 52-52 corresponds to a white picture element; the zero intensity 53 corresponds to a black picture element. Intermediate picture shadings produce intermediate amplitudes.

The output 46-41 of stage 40 may be transmitted to a remote receiving stage along wire lines or by radio transmission. In Figure 1, I illustrate a radio transmission system for the telepicture signals. The signals are impressed upon a radio frequency modulator stage 54 by leads 46-4l. A radio frequency oscillator 55 produces a carrier wave which is modulated by the audio frequency telepicturc signals in stage 54. The radio frequency transmitter 56 amplifies the signals from modulator stage 54 for transmission by antenna 51.

It is to be understood that the continuous record film 33 is stationary during the scanning 5i is symmetrical with respect The maximum intensity repre (ill aoaaooa Y 3 operation and is periodically advanced past the scanning beam 32 in a predetermined manner. The film 33 is contained in a roll 90 and is automatically advanced by the stepping mechanism 6| upon the take-up roll 92. For a scanning operation of 100 lines per inch, the stepping mechanism Bl moves film 33 past beam 32 one-one hundredth of an inch at the completion" of each scanning operation. When the scanning beam moves to the segment cd' (Figure 3) the beam 32 will impinge upon the photo-sensitive cathode" 31 and produce a signal in the formof an impulse upon amplifier 93 through leads 64-65. The output 66-61 of amplifier 93 is connected to the automatic advancing mechanism schematically represented at 9|. Mechanism 9i may for example be well known electro-magnetic periodic advancing means which is actuated by the electrical impulses produced at the end of each scanning excursion Ila of the electron beam II as will be understood. The film 33 is accordingly advanced the proper amount during this interval so that the adjacent line may be scanned during the next cycle of operation.

The signal impulse produced at electrodes 31- 39 is also used for the synchronizing impulse at the remote receiving station for automatically advancing the receiving record sheet in a manher to be described. This impulse is accordingly impressed upon the amplifier-modulator stage 49 by means of a unidirectional impedance'dev'ice 10 connected between leads 65 and 4| and conductive in the direction towards the amplifier stage 49. The unidirectional impedance 19 may be a buffer stage of thermionic amplification or a rectifier. A unidirectional impedance is used to prevent the picture signals generated at electrodes 36-39 from being impressed upon the amplifier 63. The magnitude of the impulse impressed upon amplifier 49 is greater than that of any corresponding telepicture signals so that the receiving station may selectively respond to this signal for operating the automatic film advancing mechanism.

Figure 6 is a schematic representation of the electronic telepicture receiving system to be used for translating the telepicture signals radiated from the transmitter of Figure l by the antenna 56. The radio receiver 1| amplifies the radio frequency signals impressed upon its antenna 12 and rectifies the modulated radio frequency carrier signals. The output 13-14 of receiver 1| corresponds in signal wave form to that atthe output 46-41 of amplifier-modulator stage 49 of the transmitter. The output 13-14 is the audio carrier modulated in accordance with the picture shading being transmitted, corresponding for example, to its graphical representation in Figure 5. Connection lead impresses the telepicture signals upon vertical deflecting plate 19. The opposite vertical deflecting plate 11 is connected to ground through lead 19. A high resistance 19 connects deflecting plate 19 to electrostatic ground potential. The plates 16-11 are accordingly at a common static potential with respect to the high potential anode 99, namely at ground potential. The receiver cathode ray tube BI is similar to the corresponding transmitter tube Ill. The electrode potential supply is from the potentiometer 92 connected across the high voltage supply 83, the positive terminal of which is connected to ground. The first anode 94 and the control grid 85 are connected to suitable potential points on the potentiometer 82. The electron beam 86 is generated at the cathode 81 and focused upon the fluorescent screen in the well known manner. The horizontal deflecting plates 99-99 are actuated by the linear sweep oscillator 9|. The output of sweep oscillator 9| is connected to the horizontal deflecting plate 39 by lead The frequency of linear sweep oscillator 9| is adjusted close to that of the frequency of the transmitter sweep oscillator 21. Oscillator 9l is impulse excited by the synchronizing signals so that is will have the exact frequency of the transmitter scanning frequency. The electron beam 96 will accordingly be oscillated horizontally across the center of the fluorescent screen 99 by deflecting plates 99-99. A marginal amplifier 93 is connected to the output 13-14 of the receiver 1! by input leads 94-95. Marginal amplifier 93 is suitably biased so as to respond only to a predetermined amplitude of input signals, namely to the amplitude of the synchronizing signals. Since the synchronizing signals are greater in amplitude than any of the telepicture variations, amplifier 93 will respond only to the synchronizing impulses as will beunderstood by those skilled in the art. The output 99-91 of marginal amplifier 93 will accordingly be periodically amplified impulses corresponding to the transmitted synchronizing impulses during scanning period c'-d' (Figure 3). The output 99-91 is connected to the linear sweep oscillator 9| by leads 99-99 to provide the frequency synchronization therefor in a well known manner. The horizontal scanning action of electron beam 98 will correspond to that of electron beam H at the transmitter. The phase adjustment of beam 96 is automatically provided by proper design of the impulse excited linear sweep oscillator 9| in relation to the predetermined occurrence of the periodic synchronizing impulse at the end of each scanning line.

The incidence of electron beam 89 upon fiuorescent screen 99 will produce a brilliant spot of light which is suitably focused by lens system I09 upon the receiving film NH. The continuous film lOl is contained upon take-up roll I92 and is automatically stepped past the scanning beam by stepping mechanism H13. Mechanism I93 is similar to the stepping mechanism 9| of the transmitter and is electrically actuated by the amplified synchronizing impulses from the output 96-91 of amplifier 93. Film I9i is advanced in the present example one one-hundredth of an inch at the end of each scanning line operation.

Film I9! is placed opposite the fluorescent face 99 of tube 8| in a position corresponding to that of the transmitter represented by Figure 3. Points (1', c, and b of Figure 7 correspond to the similarly marked points of Figure 3. The interval a'-c' is equal to the width of the film HI, for example, six inches. The transmitter film 33 would also be six inches wide. The interval c-b' corresponding to the synchronizing impulse period may be one inch in length.

The vertical deflecting plates 19-11, actuated by the telepicture signals will superimpose upon the horizontally oscillated electron beam 89, a motion corresponding to the wave form 50 represented in Figure 5. The fluorescent image of the actuated beam 99 will appear upon screen 89 in the form represented by curve I93. The transmitter linear sweep oscillator 21 is electrically,

coupled to the audio frequency oscillator 93 by 1 iii lat'ir 4'3 il' y be tuned to .illl'lil cycles and the ator concl, iiilti to i.

v at

A light linings "1th,... .y signal all (.wcordingly not be ire-- hired upon film Hill and biaclt picture element will result thereon, A white picture element represented by the maxin'lum image width IDS-405 corresponds to the signal intensity representation 52--5Z in Figure 5. Focusing system I00 is dcsigned to recluccthe light image width IBIS-I06 to the width of the scanning line impressed upon film IOI, namely one one-hundredth of an inch. Intermediate picture shadings as hereinabove described, will be represented by intermediate light image widths on the fluorescent screen 88. The picture shading recorded on film IN is proportional to the width of the light image I04 opposite the particular element of the line during scanning thereof.

If the frequency of the picture carrier is relatively high, the image I04 thereof will be represented as a light area having an envelope c0rresponding to the picture shading modulation. A contihuous tone reproduction will accordingly resuit. On the other hand, if the picture carrier frequency is relatively low, a distinct sinusoidal wave form similar to the illustration I04 will result with a similarly shaped envelope I05. A discrete point by point or half-tone reproduction will result due to the non-contiguous light image. This effect may be increased by shielding the upper or lower half of the light image I04.

The persistence of fluorescent screen 88 should be low enough so that the light image I04 of each successive line scanned will disappear in the interval between scanning impressions, namely, during the synchronizing period c'-b' and the sweep return interval 3| (Figure 2). The important feature of my present invention resides in the representation of the picture shading by a corresponding electronically produced varying width light image which is focused to a narrow scanning light beam upon a sensitive picture film. To compensate for a non-linear picture shading translation, a light filter or screen I01 may be interposed between the signal Image I04 and the film IOI. Figure 8 illustrates a preferred shading for the light filter or screen I01. The outer portions I08 of screen I01 are transparent. A gradual reduction of light trans -mission is effected between the outer portions I00 and the central portion I013. The effectiveness oi the varying widths of light image I04 on screen 08 upon. the film |0I is accordingly predetermined by the light transmission character istic of the screen I01. In the illustrated screen I01, the portions of the light image I04 on screen 88 furthest away from the horizontal axis cz-b will be more effective than the portions nearer to axis a'-b as will be understood. By drawing a narrow opaque line IIO across the center of screen I01, the ineffective fluorescent section r a--b of screen 08 may be dispensed with so aosarniul or oi" present to those skilled l ctrouic V including means for generating an electron beam, and means for oscillating said boom in one direction at a pro-- determined rate transversely a picture film to be transmitted with one oscillation for each line of scanning; a photoelectric cell in operative relation with said scanner and said picture for generating teiepicture signals of individual lines of scanning in accordance with the shading of said picture as said scanner scans the picture; a source of carrier current; means for modulating said carrier current in accordance with said tclepicture signals; and a receiver comprising a corresponding electronic scanner including means for generating an electron beam, means for oscillating said receiver beam in one direction at said predetermined rate with one oscillation corresponding to each of said lines of scam ning, and means for simultaneously moving said receiver beam transverse to said oscillating direction in accordance with the received picture modulated carrier current whereby the width along any section of the image is proportional to the degree of picture signal modulation.

2. In a telepicture system, a transmitter com prising an electronic scanner including means for generating an electron beam, and means for oscillating said beam in one direction at a predetermined rate transversely of a picture film to be transmitted with one oscillation for each line of scanning; a photoelectric cell in operative relation with said scanner and said picture for generating telepicture signals of individual lines of scanning in accordance with the shading of said picture as said scanner scans the picture; a source of carrier current; means for modulating said carrier current in accordance with said telepicture signals; and a receiver comprising a corresponding electronic scanner including means for generating an electron beam, means for oscillating said receiver beam in one direction at said predetermined rate with one oscillation corresponding to each of said lines of scanning. and means for simultaneously moving said receiver beam at right angles to said oscillating direction in accordance with the received pic- .ure modulated carrier current whereby the width along any section of the image is proportional to the degree of picture signal modulation.

3. In a telepicture system, a transmitter comprising an electronic scanner including means for generating an electron beam, and means for oscillating said beam in onev direction at a pre determined rate transversely of a picture film to be transmitted with one oscillation for each line of scanning; a photoelectric cell in operative relation with said scanner and said picture for generating telepicture signals of individual lines of scanning in accordance with the shading of said picture as said scanner scans the picture; a source of carrier current; means for modulating said carrier current in accordance with said telepicture signals; a receiver comprising a corill light tracing along successive thin lines for re- 15 producing the transmitter picture on said record sheet.

4. In a telepicture system, a transmitter comprising an electronic scanner including a cathode ray tube having a fluorescent screen, means 20 for generating an electron beam and means for oscillating said beam in one direction at a predetermined frequency with one oscillation for I I each line of scanning across said fluorescent screen for generating a moving scanning point of 25 light transversely of a picture fllm to be transmitted, means for moving said picture at right angles to the line of oscillation of said beam oetween successive oscillations thereof; a lens system interposed between said fluorescent screen and said picture fllm for focusing said moving point of light on said picture film; a photoelectric cell in operative relation with said scanner and said picture for generating telepicture signals of individual lines of scanning in accord- 35 ance with the shading of said picture as said scanner scans the picture; means for generating an audio frequency carrier current which is a multiple of said oscillating frequency, means for producing a synchronizing impulse between successive lines of scanning, means for modulating said carrier current by said telepicture signals; a receiver comprising a corresponding electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam, means responsive to said synchronizing impulses for oscillating said receiver beam in one direction at said predetermined rate with one oscillation corresponding to each of said lines of scanning for generating a moving point of light on the screen transversely of a light sensitive record sheet, and means for simultaneously moving said receiver beam at right angles to said oscillating direction in accordance with the picture modulations of the received signals for pro- 55 ducing an' individual stationary light tracing corresponding to successive lines of scanning of the picture, the tracing of each successive line being generated in substantiallythe same area of said receiver screen.

5. In-a telepicture system, a transmitter comprising an electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam and means for oscillating said beam in one direction at a predetermined frequency with one oscillation for each line of scanning across said fluorescent-screen for generating a moving scanning point of light transversely of a picture film to be transmitted, means for moving'said picture at right angles to the line of oscillation of said beam between successive oscillations thereof; a lens system interposed between said fluorescent screen and said picture film for focusing said moving point of light on said picture fllm; a photoelectric cell 75 in operative relation with said scanner and said picture for generating telepicture signals of individual lines of scanning in accordance with the shading of said picture as said scanner scans the picture; means for generating an audio frequency carrier current which is a multiple of said oscil- -lating frequency, means for producing a synchronizing impulse between successive lines of scanning, means for modulating said carrier current by said telepicture signals; a receiver comprising a corresponding electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam, means responsive to said synchronizing impulses for oscillating said receiver beam along a single plane at said predetermined rate with one oscillation corresponding to each of said lines of scanning for generatingf'a moving point of light on the screen transversely of a' light sensitive record sheet, means for simultaneously moving said receiver beam at right angles to said plane in accordance with the picture modulations of the received signals for producing an individual stationary light tracing corresponding to successive lines of .scanning of the picture; and means for affecting said light sensitive sheet by said light tracing along successive thin lines for reproducing the transmitter picture on said record sheet comprising a lens system interposed between said fluorescent screen and said sheet.

6. In a telepicture system, a transmitter comprising an electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam and means for oscillating said beam in one direction at a predetermined frequency with one oscillation for each line of scanning across said fluorescent screen for generating a moving scanning point of lighttransversely of a picture fllm to be transmitted, means for moving said picture at right angles to the line of oscillation of said beam between successive oscillations thereof; a lens system interposed between said fluorescent screen and said picture fllm for focusing said moving point of light on said picture film; a photoelectric cell in operative relation with said scanner and said picture for generating telepicture signals of individual lines of scanning in accordance with the shading of said picture as 'said scanner scans the picture; means for generating an audio frequency carrier current which is a multiple of said oscillating frequency, means for producing a synchronizing impulse between successive lines of scanning-means for modulating said carrier current by said telepicture signals; a receiver comprising a corresponding electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam, means responsive to said synchronizing impulses for oscillating said receiver beam along a single plane at said predetermined rate with one oscillation corresponding to each of said lines of scanning for generating a moving point of light on the screen transversely of a light sensitive record sheet, means for simultaneously moving said receiver beam at right angles to said plane in accordance with the picture modulations of the received signals for producing an individual stationary light tracing corresponding to successive lines of scanning of the picture and means for affecting said light sensitive sheet by said light tracing along successive thin lines for reproducing the transmitter picture on said record sheet comprising a lens system interposed between said fluorescent screen and said sheet for focusing said light tracing plane at said predetermined rate upon said sheet along a thin line, and means responsive to said synchronizing impulse for advancing said record sheet between successive lines of scanning.

7. In a telepicture system, a transmitter comprising an electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam and means for oscillating said beam in one direction at a predetermined frequency with one oscillation for each line of scanning; across said fluorescent screen for generating a moving scanning point of light transversely of a picture fllm to be transmitted, means for moving said picture at right angles to the line of oscillation of said beam between successive oscillations thereof; a lens system interposed between said fluorescent screen and said picture fllm for focusing said moving point of current by said telepicture signals; a receiver comprising a corresponding electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam, means responsive to said synchronizing impulses for oscillating said receiver beam along a single with one oscillation corresponding to each of said lines of scanning for generating a moving point of light on the screen transversely of a light sensitive record sheet, means for simultaneously moving said picture modulations of the received signals for producing a stationary light with received picture modulated carrier current whereby the width along any section 'Of the im age is proportional to the degree of picture signal modulation.

9. In a telepicture system, a receiver comprising an electronic scanner including a cathode ray tube having a fluorescent screen, means for generating an electron beam, means for oscillating said beam in one direction at a prcdeter mined rate, with one oscillation corresponding to an individual line of scanning for generating a moving point of light on the screen transversely of a light sensitive record sheet, and means for simultaneously moving said receiver beam at right angles to said oscillating direction in accordance with received picture modulated carrier current whereby the width along any section of the image is proportional to the degree of picture signal modulation; and means for affecting 10. In a telepicture system, a receiver comprising an electronic scanner including a cathode tube having a fluorescent screen, means for posed between said fluorescent screen and said sheet.

11. In a telepicture system, a receiver comprising an electronic scanner including a cathode ray tube having a fluorescent screen, means for sheet, means for simultaneously moving said receiver beam at right angles to said oscillating direction in accordance with received picture modulated carrier current whereby the width along any section of the image is proportional to the degree of' picture signal modulation; and means for affecting said light sensitive sheet by said light tracing along successive thin lines for reproducing the transmitter picture on said record sheet comprising a lens system interposed between said fluorescent screen and said sheet for focusing said light tracing upon said sheet along a thin line, means for advancing said record sheet between successsive lines of scanning, and a light filter interposed between said tracing and said record sheet for predetermining the action of said light tracing on said record sheet.

WILLIAM G. H. FINCH.

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