US1706185A - Transmission of pictures and views - Google Patents

Description

7'0 WIRE 0/? RAD/0 TRANSMIT- TIA/6 AFFAfiATl/S.

March 1929- c. A. SABBAH 1,706,185

TRANSMISSIONOF PICTURES AND VIEWS I Original Filed May 2'7, 1925 IMAGE FORMED 01v mo WALL a A /z Fig. l.

IMAGE FORMD 0N SILK GAUZE DIS/f 38 Invent r: Camille A.Sabbah,

Hus Attorney.

Patented Mar. 19, 1929.

UNITED STATES PATENT OFFICE.

OAMILLE A. SABBAH, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEG TRIO COMPANY, A CORPORATION OF NEW YORK.

TRANSMISSION OF PICTURES AND VIEWS.

Application filed May 27, 1925, Serial No. 33,272. Renewed November 3, 1928.

My invention relates to the electrical trans- 1lSSlOl1 of pictures and views. An object f my invention is the provision of improved method and means for the rapid transmission of still pictures and views, and for the transmission of moving pictures and views. A further object of my invention is to provide apparatus for this purpose which shall have no moving material parts and which is thereby free from inertia effects.

Demonstrations with glass electron emission tubes have shown that those portions of the glass wall of the tube which arehit by a stream of electrons acquire charges which vary in degree in accordance with the amount of light falling upon them, the brighter the illumination the less the charge acquired thereby. In accordance with one form of my invention I make use of this phenomenon for the transmission of pictures and views by projecting upon the end wall of a cathode tube an image of the picture or view to be transmitted and cause the cathode ray rapidly to scan the image. \Vithin the tube and in front of the image I provide two perforated plates, the perforations being small and close together with a the perforations of the two plates in aliuement whereby the ray may pass through the perforations. The wall of the tube at the darker portions of the image having acquired charges which are greater than those at the lighter portions, the electrons coming to, the darker portions suffer a greater repulsion than those coming to the lighter portions. As a result the current collected by the plate nearest the image is less and the current collected by the other plate is greater when the ray falls upon a dark portion of the image than when it falls upon a light portion thereof. I connect both plates to the cathode to provide a return circuit for the collected electrons and in the circuit from the plate nearest the image I insert means for amplifying the current therein, the amplified current being transmitted by wire or radio to a distant receiving station.

' Referring to the drawing, Fig. 1 is a diagrammatic representation of one form of.

apparatus involving my invention; Fig, 2 shows one form of wave used for movlng the cathode ray; Fig. 3 shows the spiral path which the cathode ray is caused to take; 4 is a and Fig. 5 shows a modification of what is shown n Fig. 1.

In F 1g. 1 I have shown diagrammatically a cathode ray tube 1 having at one end the filament 2, which is'adapted to be heated by ture or View represented by' the arrow 10. 7

lVit-hin the tube and adjacent the end wall 6 are two similar thickly perforated metal plates 11 and 12. The plates are parallel and the perforations therethrough have their centers closely spaced, the spacing being of the order of one one-hundredth of an inch. The perforations of the two plates are also in alinement so as to permit free passage therethrough of the cathode ray. Instead of perforated plates gauze disks may be used if so desired. Circuit connections including wire 13 are provided from both plates back to the battery 5 and cathode 2, the connection from plate 11 including the resistance 14.

Within the tube 1 and arranged on opposite sides of the path of the cathode ray at a point preferably adjacent the anode are two pairs of spaced parallel plates 18 and 19, the one pair being placed at right angles to the other.

given to these pairs of plates the cathode ray which passes between the plates will be distorted or bent and that by suitably varying the charges on the two pairs of 95 plates relative to each other the ray can be made to follow any desired path. If the plcture or view to be transmitted is still, movement of the ray in scanning the image need only have such speedthat the move- 10 ment of the corresponding spot of light in the receiver may not be detected by the eyeof the observer. For the transmission of a moving picture or view the ray should scan modified form of wave, 55

at the op- 05 As is well understood by those skilled in the art, if charges are the entire image at least sixteen to twenty times er second to prevent the effect of flickering of the transmitted picture.

Various methods may be employed for varying the field between the plates 18 and the plates 19 to cause the ray to cover the image on the plate 6 with the desired speed. Ono arrangement whereby the plates 18 and 19 may be energized in a manner to cause the ray to travel in spirals such as shown in Fig. 3 at the desired rate is shown diarammatically in Fi 1. A-well known orm of self-rectifying circuit is employed comprising the two pliotrons 20 and 21. lVhen the rectifying circuit is fed by the transformer 22 connected for example to a ten cycle source of alternating current, the current in the oscillation circuit 23, 24, 25, 26 may be of the form represented by 27 in Fig. 2, the high frequency oscillations being modulated by the ten cycle current. winding 28in inductive relation to the oscillation circuit is connected in circuit with an inductance 29 and resistance 30. One pair of plates, for example, plates 18, is connected across the inductance'29, the other pair of plates is connected across the resistance 30. By this arrangement the currents traversing the two pairs of plates are substantially in quadrature with each other and each has the .form illustrated by Fig. 2. The resulting effect upon the cathode ray is to cause it to trace upon the wall 6 spiral paths such as illustrated for example by 31 in Fig. 3. Every. small unit area of the image on the plate is thus covered many times per second by the ray. At this point of the description it is desired to point out that the drawing is purely diagrammatic in character and that no attempt has been made therein to show the various parts in their true or relative proportions. Likewise in the diagrams forming Figs. 2 and 3, as well as Fig. 4, to be described hereinafter, the high frequency wave and. the resulting pitch of the spiral 31 are not illustrative of actual conditions but rather have been shown having such values as is found most convenient in illustrating the idea.

The current impulses traversing the resistance 14 as a result of the cathode ray scanning the image and the repulsion of electrons by the negative charges on the wall 6 may be transmitted to a distant station either by wire or by radio. Two amplify- . ing pliotrons 32 and 33 are shown connected together by the transformer 34, the grid and filament of the first pliotron being connected with the resistance 14 and the plate of the second pliotron being connected through the transformer 35 with a suitable wire or radio transmitting apparatus not shown.

In usin the apparatus, the ten cycle current supp ied to the transformer 22 causes ing perforations in plates 11 and 12 rapidly scans the image formed on the'cnd wall 6 of the tube negative charges are acquired by the various small portions or unit areas of the end wall in proportion to the intensity oi the image at those areas. ()n light areas the charges are relatively small and the repulsion of the electrons due to the negative charges is accordingly relatively small; on dark areas the charges are relatively great and the repulsion of the electrons is accordingly relatively large. As a result, the number of electrons collected by the plate 11. will be less when the ray passes over dark portions of the image than when itpasses over light portions thereof. As the ray rapidly scans the image the current flow through the resistance 14 therefore varies in accordance with the degree of brightness of the various unit areas of the image. The current collected by the plate 12 also varies in accordance with the brightness of the image but in the opposite manner, the current being greater when the ray passes over dark portions of the image than when it passes .over light portions thereof. The variations in potential drop across the resistance 14- are amplified by the pliotrons 32 and-33 and the amplified current may then be transmitted to the distant receiver by wire. or radio transmitting apparatus not shown.

The ray may be made narrow enough and the turns of the spiral close enough to produce a picture having the desired sharpness. The entire image is thus covered twice during each half of the ten cycle current. \Vhile I have used terms such as light illumination and brightness in speaking of the image formed upon the plate 6, I desire. it to be umlerstood that I use these terms in their broadest sense to cover not only the visible portions of the spectrum but also the invisible portions thereof since the phenomenon described is not confined to those portions of the spectrum which are visible.

Instead of causing the cathode ray to cover the image by tracing spirals upon the plate (5. it may be caused rapidly to sweep up and down over the plate while advancing back and forth across it. thus tracing a path after the fashion of that illustrated by the line 37 in Fig. 4. In this way the entire image is covered during each horizontal traverse of the ray. For moving the ray in this manner the self-rectifying circuit il lustrated may be dispensed with and one pair of deflecting plates may be connected to a source of sustained high frequency while the other pair of plates may be connected to a source of lower frequency which may be of the order of sixteen or twenty cycles per second, or higher, if desired.

By whichever method the ray is moved, it will be noted that the apparatus includes no material moving parts and hence no inertia effects have to be considered. The only moving element is the cathode ray and this is adapted to respond instantly to the deflecting force. A

For receiving the picture or view thus transmitted I may use a cathode ray tube having means similar to that already described for moving the ray and in which the voltage between anode and cathode is caused to vary in accordance with the impulses received from the transmitting station. The ray in this case may fall on a semi-transparent film of phosphorescent substance and the plate may be viewed through a suitable lens or eye-piece. Synchronization of the transmitting and receiving apparatus is obtained by employing oscillation circuits 23, 21L 25 and 26, in the transmitter and the receiver having the same frequency and by slight manual variations in the constants of the circuit maintaining the exact synchroni zation necessary to prevent distortion of the picture.

In the modification illustrated by Fig. 5 the end wall of the cathode tube, which may be of glass or quartz, is covered on the inside with a transparent film 37 of a conductor such as the semi-transparent silver layer in a Michelson interferometer. Instead of the plates 11 and 12 of the form shown in Fig. 1, I use a screen 38 of silk gauze made of single or double silk fibers spaced at about one two-hundredth of an inch and an electron collecting screen 39 of fine metal gauze. Circuit connections as in the preceding form are made between both film 37 and collecting screen 39 and the cathode 2, the resistance 14 being included in the connection from the film 37. The amplifying apparatus, the means for moving the ray and circuit connections are otherwise the same as that illust ated in Fig. 1.

In the operation of this form of the invention the image is formed on the silk gauze screen 38, the light rays passing through the film 37 on the end of the tube. As the cathode ray scans the image on the gauze screen 38 the negative charges acquired by the various small unit areas thereof depend upon the illumination or brightness of the image at those portions. Vhere the image is bright the negative charges and consequently the repulsion of the electrons are small, hence large numbers of electrons pass through the screen 38 to the film 37. Where the image is dark the ray encounters a greater repulsion due to the greater opposing negative charges at that point and zu-cordingly a less number of electrons will pass. The resulting variation in current passing the resistance in the return path to the cathode is amplified as in the preceding form before being transmitted to the distant receiving station.

In my copcndm application, Serial No. 33,270 filed May 2?, 1925, I have disclosed a different embodiment of my invention utilizing a cathode ray for scanning purposes, and have claimed in that application the broad features common to that case and the present application.

\Vhat I claim as new and desire to secure by Letters Patent of the United States is 1. In picture and view transmission the method which comprises forming upon a member an image of the picture or view to be transmitted, traversing elements of the image successively by a cathode ray, whereby electron repelling charges are formed on the member in accordance with the ima e, and collecting the electrons of the ray which are not repelled.

2. Apparatus of the character described comprising a member on which an image is adapted to be formed, means for causing a cathode ray to scan the member, whereby charges are acquired by the member depending upon the image, conductive means adjacent the member from which means electrons are repelled by said charges, means providing a return path for the electrons collected by said conductive means, and current responsive means arranged in said path.

3. Apparatus of the character described comprising an insulating member, means forming a cathode ray, means for causing the ray to scan the member, means for forming an image on the member whereby electrons comprising said ray are repelled in accordance with the dark portions thereof, and conducting means arranged adj acent the insulating member for receiving electrons not repelled. I

4. Apparatus for the transmission of pietures and views comprising a cathode ray ,tube having a non-conducting member toward which the cathode ray is directed, means for forming an image on the member, means for causing the ray to scan the image, a conducting member arranged adjacent to and parallel with the non-conducting member, circuit connections between the conduct ing member and the cathode of the tube, and current responsive means arranged in said circuit connections.

5. Apparatus for the transmission of pietures and views comprising a cathode ray tube having a non-conducting plate toward which the ray is directed, a pair of conducting plates adjacent to and parallel with the non-conducting plate, means for projecting an image of the picture or view to be transmitted on the non-conducting plate, means for moving the cathode ray to cause it rapidly to scan the image, means providing a return path for the electrons reaching the conducting plates, and means for amplifying the current flow in the return path from one of the conducting plates.

In witness whereof, I have hereunto set my hand this 26th day of May, 1925.

OAMILLE A. SABBAH.

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