US1979463A - Television system - Google Patents

Description

NOV. 6, 1934. R GOSHAW I 1,979,463

TELEVISION SYSTEM Filed May 11, 1932 ElE l TO AMP.

TO SCREEN. TO AC. 3 5/ 1 INVENTOR II'l H. Gnshaw AMP.

Patented Nov. 6, 1934 1,979,463 TELEVISION (SYSTEM,

Irl R. Goshaw, Nutley, N. J., 'assignor to Wired Radio,Inc., New York, N. Y., a corporation of Delaware Application May 11, 1932, Serial No. 610,546

7 Claims. (Cl. 178-6) This invention'relates to television systems and particularly to such systems of the non-mechanical type wherein no mechanical movements are employed although such movements may be substituted for non-mechanical elements if desired.

An object of the invention is to transmit images of objects with electrical currents. V Another object of the invention is to generate and transmit currents. corresponding to the light and shade densities of an object and to translate such currents into light images'of said objects at. a distant point. I e

I A'further object of the invention is to transmit light images of objects with a system employing g non-mechanical movements. V.

A still further object of the invention is to provide a television-system for transmitting imagesbytransmitting only certain portions of an image characterized by a certain light density.

In the usual type of television transmission system, an object or image thereof isscanned by a flying light spot orfelectron streamto analyze the object or image into .unitv areas ,for serial transmission to similar apparatus for building up the image in the same. or an,.-equivalent man.-

ner. These systems have. many'disadvantages such as the frequency limitation of theapparatus.

the .difiiculty of synchronizing moving elements at. the transmitterand receiver, the difiiculty in obtaining suflicient detail and good definition because of the rapid movement and short duration .of a unit light area, and, where mechanical moving elements are employed, the vlimitation'by speed and size to a small picture area.

,35 The television system disclosed hereinafter requires a less efficient line then the present type since the linecarries lessload for the same detail as now obtained while the size of thepicture' is not limited because no mechanical movements are employed for analyzing or building up-the images.

' Synchronization is natural in that the house supply current may supply the transmitterand receiver directly, or synchronization may be obtained by simple tuning as in a radio receiver.

It is to be understood that mechanical elements may be substituted for certain electrical elements,

these mechanical elements being of so simple a nature that they may be taken bodily from present pictureprojection systems nowin general use.

The chief principle of. the invention is the electrical delay of currents so that a serial re- .lationship isproduced from a plurality of generators operatingsimultaneously. For instance,

@a composite cathode of a photoelectric cell is employed, .thecathode being formedqf many inthe output I of the transmitter; and, 'Fig: 5 is acircuit element which may be sub- PATENTMOFFICE} dividualcells having a common anode, each cell employed in which a picture is obtained by voltageflashes, at the proper rate of speed modified byv the incoming picture currents.

The invention will be more fully understood from the following description read in conjunction with the accompanying drawing in which: .Fig. 1 is a diagrammatic view of the transmission system Fig. 2 is a detailed-plan view of a cathode of the photoelectric cell: 7 I

Fig. 31s a diagrammatic view of the receiving apparatus:

Fig. 4 is a graph of the television currents in stituted for a portion of Fig. 3.

Referring specifically to Fig. 1, an object. 0 is illuminated withintermittent light from a lamp 5 supplied by an alternator 6 or from the house supply source. The image of the object so produced is focussed by a lens 8 upon a composite cathode 9 of a photoelectric cell having an anode 10.. The projecting lamp produces on the cathode 9 intermittentlight'images which occur at double thefrequencyof the source 6. Intermittent images may also be produced on the cathode with a constant illumination of the object 0 but which is broken up by a shutter 12 operated byany means welll znown in the art.

In Fig. 2 a plan View of the cathode 9 of the photoelectric cell shows'a cathodedivided up into a pluralityof sections which are insulated from one another by thin insulatingpartitions such as lavite or mica. The .back of the cell is formed of sections of conducting material insulated from oneanother but which-have deposited thereon the 1 photosensitive material. This construction forms many individual photoelectric cells independent of one another electrically but which have a common anode 10. To each cell unit is connected a conductor and as shown in Fig. 1 they are brought out to a common lead or busbar 14. In all conductors but one there are inserted delay elements 16, such as inductances of graduated values which have the proper amount of distributed capacity to produce a smalldifference in delay in each circuit. To'maintain the direct current impedances in eachcircuit constant there is also inserted in the conductors a graduated series of pure resistances the direction of. graduation being the re- .y e rse of {the delay element 16. As stated above.

the conductors terminate in a busbar 14 connected to the input of an amplifier 20, the other input lead being connected to the anode 9 of the photocell by conductor 21. The output of the amplifier is fed into a transmitter 22, from which it may be broadcast over an antenna 23, or wire conductors 24.

The operation of the transmitter is as follows: Intermittent images at any desired rate such as twenty per second, which is the present transmission rate, or highen are impressed upon the cathode 9. At each image impression the unit areas receiving light above a certain density will simultaneously generate currents proportional to, the light falling thereon. The generated impulses will not arrive at the amplifier 20 simultaneously, however, but in a serial order, the time unit be. tween the first and last impulsedepending upon the delay inserted in each particular circuit. The amount of delay is determined by the period of illumination of the cathode and the number of unit cells or areas employed. With present standard television practice, the'number of individual cells would be'in the neighborhood of- 3600 and the intermittent illumination at the rate of twenty per second, making the delay in each circuit on the order of 1/72000 of a second. The amount of of the lightimpulses is immaterial as will'be seen later but a sharp' impression of the impulses'upon the cathode is required.

In Fig. 4 a time interval between the impression of light impulses is shown which may be an interval of 1/20 ofa second between 'd and b, the first and last impulse' respectively. The variation in the current arriving at the amplifier 2 0 is shown by this curve. The portion -ofleo current near the middle of the intervalis indicare f a ar a ea' hh hg a r ss the i l of the cathode sucn'a wquiaberdrmea by"tl'1 e object o with the delay graduated in' a'verti'al diy q ig eferring now to the receiving apparatus in Fig, 3, an antenna 3Q or wire conductors 31'impress incoming energy upon a receiver 32. After iduct-lion to the original" impulses in the receiver they are amplified in" an amplifier 34 is'conn'ectedtd'a busbar 35an'd'conductor 35. The receiving screen is in appearance similar to'the cathode of Fig. 2 but theelement'a'ry areas are formedof either individual neon lamps or incandescent lamps which haveeom'monelectrodes 3'7 and lOQ The otherelectredesor grids of the lamps are conneeted 't'dtlie busbar 35 through iilhy circuits 38" having var ing amounts of delay and pure resistancesf39 identicaltothe arrangement in'Fig. 1. H e wee the common electrode lead 36 and electrode 37 there isconnected'a sourceof direct potential ll shunted by a'variable condenser 42, a variable inductive element '43 and a'variable resistance 44; These three elements shown within the dotted lines serve as the trigger for the receiving screen and provide, in connection with the neon lamps, a relaxation oscillator systernj That is, a voltage from source il will build up to the poin of flash rs? and the di ch g of sie Eel #2 will li ht t e amps for an ihsthht This in val hf ope at on de e d upo t ihs .e the elem n 2 43 an an mar'be ar ed With n Wi d l mit th s laxat on eh b in wellkhowh in the art Fig- 5 shows a etailed irc i wh h may h h ii hted f th w ich O Fi 3 s w Within the d tted l ne ri oth werl l h rslhXhtion oscillator circuit. A source of direct'current potential is connected between the screen and amplifier through a contact 51 shunted for condenser 52 by protecting the contacts 51. The contacts 51 are operated by a relay 54 which may be connected to the ordinary cycle alternating current house supply. The relay may be made to operate the contacts 51, 6( times per sec- 0nd or 120 times per second by a direct connection to the house tap. The receiving screen when used with the circuit of Fig. 5 may be either individual neon lamps, incandescent lamps, or in fact, merely arc gaps across which a current will flow at the proper voltage.

The operation of the receiver is as follows: The train of impulses shown in Fig. 4 arrive at the busbar 35 and conductor 36 after detection and amplification. As the impulses arrive they are delayed in proportion to the amount of delay in each individual circuit which is the same as the delay in the circuits at the transmitter. If we assume an impulse a as the first impulse, that particular impulse will arrive at the receiving position a on the screen at a certain instant of time. That same impulse oi course, will arrive at the other light producing positions previous, to

.its arrival at the position a butwill b e dissiatch will the d dhh Want the oth Posit on rr r h Takin h r ceiving cell conductor that has no delay whatever, which in this case is impulse b orthe last impulse, all of the preceding impulses will arrive a he i h l men q e the as im and will'be dissipated, However, at a certain instant of time every impulse will be at its proper element, which, with the assurned f gures above. will be 1/20 of a second after the first impulse arrives at the busbar 35. At this instant 9. volt a w l b b l u f o the hhrc 1 su fic o as the n n m twe the elev e 3' nd 0., e volta e n ds det rm ni the light intensities of the unit areas, or the COD- tact 51 will be closed to connect the source 50 to the screen' Other sources of light such as incandesce a p and the cqo 'din te ys em f ar gaps are preferable with the circuit of Fig. 5.

The common voltage irnpresse dis suflicient to light all lamps with the same intensity but be.- cause of the supplementing of the common voltage with the incoming impulse voltages at the vario amps ach li ht will produce vary intensities corresponding to the light and shade densities of the object. When the lights are flashed by the common voltage an image will be observed on the screen corresponding to that projected on the cathode 9 at the transmitter. It is not necessary that the lamps be extinguished ior the dark portions of the object, as long as there is a variation between the elements so that the brighter ones cause the lighter ones to appear as darker portions.

"In the system above described, it is to be observed that by using the lamp source 5 connected to the alternating house supply, the object 0 may be illuminated 60 times a second by using a rectifier, or 120 times per second without the rectifier'. Thus illuminated there will be sent to the receiver a train of impulses 6Q and 120 times per second, respectively, each train comprising an image. The circuit of Fig. 5 is especially desirable at the receiver in this case, the relay 54 being similarly controlled to make contact ,60 or 12;) times per second by the ordinary house current sh ol ih th y chr n in P obl area uppli d om common p wer s s e ii- At t is 'rate, flicker is absolutely eliminated. In using the relaxation oscillator it is only necessary to vary the tuning of the elements making up the oscillators in a manner similar to the tuning of any radio receiver. The transmitting apparatus using the shutter type of light interrupter may be simply that of a moving picture camera or projector which can be operated manually or by a spring motor well known in the motion picture art. With the convenient tuning operation at the receiver, the manual or motor drive is easily synchronized. It is to be understood that the receiver may operate without a trigger system. That is, a constant voltage sufficient to energize the lamps to a certain brightness is applied to the screen and a shutter similar to the one at the transmitter or of the multiple opening type exposes the lamps to View at the instant the p p illuminating voltages are present at the lamp The invention has been described to emphasize such advantages as non-mechanical apparatus, simplicity of operation, the method of operation which provides positive detail for each individual element, and the efficient use of transmission lines since only the light portions of the object are transmitted. The scope of the invention is defined by the appended claims.

What is claimed is:

1. In an electrical transmission system for transmitting currents characterized by the li t and shade intensities of an object, the combination of means for simultaneously obtaining a plurality of currents proportional to the light intensities of unit areas of an image, electrical delay networks for distributing said currents in a transmission line in a serial order, and electrical delay networks for impressing said currents upon a plurality of light producing devices simultaneously.

2. An electrical transmission system for the transmission of currents corresponding to the light and shade intensities of an object, means for simultaneously producing currents corresponding to the light intensities of a plurality of unit areas of an object, electrical delay networks for delaying the transmission of said currents in a graduated order, means for transmitting said currents to a receiving point, a plurality of light producing elements at said receiving point, and electrical delay networks for delaying said currents in the reverse graduated order for simultaneously impressing on said light producing elements energy corresponding to the light intensities of the unit areas at said transmitter.

3. In a television system, a composite cathode comprising a plurality of individual unit sections, means for intermittently impressing an image thereon, an electrical delay network for impressing the currents generated from said unit section in serial order on a transmission line, a plurality of light producing elements at a receiving point at the terminal of said transmission line, and a plurality of individual circuits including electrical delay elements connected to said light producing elements for simultaneously impressing upon said elements the currents generated by the light affected sections of said composite cathode.

4. In a television system, the combination of a composite cathode having a plurality of individual light sensitive areas, an anode for all of said areas, means for impressing an image on said cathode intermittently for producing electrical impulses, a transmission line, an electrical delay network connected to said line for impressing the impulses from said cathode upon said transmission line at definite mutually exclusive instants of time, a receiver at the terminal of said transmission line, and a similar network at said receiver for re-arranging said impulses so that they appear simultaneously.

5. In a television system, means for simultaneously obtaining electrical impulses corresponding to the light intensities of a plurality of unit areas of an object, a single channel transmission line, an electrical delay network connected to said line for transmitting said impulses over said single channel transmission line while maintaining a separation between impulses, a plurality of light producing elements'corresponding to unit areas at said first means, and a similar network connected to said transmission line for simultaneously impressing said impulses on said light producing elements in accordance with their generation at said first means.

6. In a system for transmitting currents characterized by the light and shade intensities of an object, the combination of a plurality of photo sensitive means for producing electrical currents, means for illuminating said object from an alternating current source, a transmission line, an electrical delay network connected to said line for distributing the currents from said plurality of photo sensitive means in said transmission line in a serial order, a plurality of sources of light for reproducing an image of said object, an electrical delay network connected to said line and to said light sources for distributing said currents to said light sources simultaneously, and means connected to said plurality of light sources for actuating said light sources from an alternating current source.

7. An electrical transmission system for the transmission of currents corresponding to the light and shade intensities of an object, means for simultaneously producing current impulses corresponding to the light intensities of unit areas of an object, means for illuminating said object with light from a source energized from an alternating current source, an electrical delay network for distributing said impulses from said first mentioned means in a serial order between the nodes of the currents in said alternating current source, means for transmitting said currents to a receiving point, a plurality of light producing elements at said receiving point, an electrical delay network for distributing said impulses in reversed order on said light producing elements, and means connected to an alternating current source for controlling the actuation of said light producing elements, the production of said currents and the reproduction of the received image of the object being in synchronism, when said alternating current sources have the same frequency.

IRL R. GOSHAW.

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