US2072528A - Impulse television system - Google Patents

Description

March 2, 1937.

A. M L. NICOLSON IMPULSE I TELEVISION, SYSTEM Original Filed June 25, 196 0 5 Sheets-Sheet 1 H MM INVENTOR AAsxanaer M lean Mao/son.

BYQLf W ATTORNEY oi'iginal F ile d June 25, 1930 5 Sheets-Sheet- 2 INVENTOR Akxander M Lean Nico/son.

QM/KM ATTORNEY 5 Sheets-Sheet 3 ATTORNEY INVENTOR March 2, 1937. A. M L. NICOLSON IMPULSE TELEVISION SYSTEM Original Filed June 25, 1950 Alexander M Lean N/co/son.

w W @W x W Y T. V- L P om mw mm March 2, 1937. A. M L. NICOLSON IMPULSE TELEVISION SYSTEM Original Filed June 25, 1930 5 Sheets-Sheet 4 INVENTOR flkxander M Lwm N/CO/sfln.

ATTORNEY March 2, 1937. A. M L. NICOLSON IMPULSE TELEVISION SYSTEM Original Filed June 25, 1930 5 Sheets-Sheet 5 vr k INVENTOR Alexander M- Lean Nico/son.

Patented Mar. 2, i 1937 UNITED STATES IMPULSE TELEVISION SYSTEM Alexander McLean Nicolson, New York, N. Y

assignor .to Communication Patents, Inc.. New York, N. Y., a corporation of Delaware Application June 25, 1930; Serial No. itascz Renewed July 29, 1936 13 Claims.

This inventidn relates to the transmission of intelligence in the form of images, and particularly to the transmission thereof on electric current impulsel.

An object or this invention is to transmit electrical'vibrations corresponding to the light and shade oi an object or picture thereof and the reproduction of the light and shade intensities at a distance. I

Another object of the invention is to transmit television electrical vibrations by the use of an electrical thermionic commutator which serves as a scanning and transmitting generator.

A further object of the invention is to obtain 15 perfect synchronization between the scanning medium and the receiving medium.

A still further object of the invention is the transmission of television currents and accompanying sound currents over the same apparatus.

The transmission of electrical currents obtained through the scanning of an object with light or otherwise, the currents being generated by a photoelectric cell receiving the varying light intensities, necessitates the use of a broad irequency transmission channel. This transmission is usually accomplished on carrier frequencies within a definite range and has, therefore, definite limitations from a capacity standpoint. in this invention the transmission oi the frequencies generated in the photoelectric cell is accomplished on positive half cycle impulses, the transmission irequency being, in fact, thescanning speed.

To obtain such a high scanning, speed, a thermionic commutator oi the type disclosed in my copehding application Ser. No. 460,806, tiled June id, 1930, is employed. This commutator has no mechanical parts whatever, and produces current impulses atsubstantially any speed desired up to the speed of light. These current impulses are used to produce a searching light ray while accompanying voice or sound may be transmitted on any one of the impulses not being used for scanning. Other signals of a monitoring nature the actuating impulses, although two commuta-.

tors operating at the proper speed difference will 5 reduce the number of tube elements to the arithmetical sum of the electrodes instead of the square thereof.

The details of the invention will be more fully understood from the accompanying drawings in which: Figures la and 1b are diagrammatic sketches of transmitting and'receivin'g apparatus, respec-" tively,.of a television system in accordance with tion.

In Fig. la a transmitting screen 5 of the type to be described hereinafter, scans an object 6. 25

Light projected through a pinhole 8 of a camera 9 is reflected upon a photoelectric cell iii. The currents generated in the cell it are impressed upon an amplifier ii connected to transmission apparatus ii. A generator-translator it sup- 30 plies the screen a with current impulses to produce the scanning light over conductors contained in cable it. A microphone i'i detects any sound produced by the object or objects being scanned, the electrical sound currents being im- 35 pressed upon an amplifieriB connected to the transmitter it. The generator-translator is shown connected to the transmitting apparatus it, for the transmission of synchronizing impulses and the sound modulated impulses. The 40 output of transmitter i2 is impressed upon antenna system hi) or wire conductors ii. The transmitter may comprise either amplifiers which ampliiy only the generator-translator impulses after modulation by the photoelectric cell currents, or may comprise a carrier frequency modulator. A modulator-oscillator system is not required when the impulses are generated at a sufilciently high frequency.

Referring to Fig. 1b', receiving antenna 25 or wire conductors 28 feed receiving apparatus 21 which is.oi.' the type depending upon the transmitter i2. An amplifier 28 amplifies the-received signals before impression on a generator-translator 29. The output of the generator-translator 29 is connected to a receiver screen 88 by a cable 8| containing the screen electrode conductors.

Also connected to the generator-translator is a lustrate one terminal of a television system which may be used either for transmitting or receiving,

or for two-way transmission.

In Fig. 2 a portion 48 of a scanning or receiving screen is illustrated by a co-ordinate set of conductors, a certain proportion of which are connected up to energizing transformers to show the operation of the system. This screen may be of the, type disclosed in Fig. 6, or any type of screen which has a plurality of spark gaps or light producing points which, by energization from a voltage source in a certain order, will produce a searching beam of light. 'In the present drawing electrodes 4|,. 42 and 49 comprise a portion of one set of coordinates, ancl electrodes 44, 48 and 48 comprise a portion of the other set of co-ordinates. These electrodes may be of metallic conducting materials separated sufllclently to allow a certain voltage to produce a spark therebetween, and may be closed within an evacuated envelope or a gas filled tube,-although this is not necessary, since the essential object of the screen is to produce a visible light.

The above numbered electrodes produce in the present screen nine intersecting points. .These points have voltage supplied through line transformers 49 to 81, inclusive. To produce a spark at the intersection of the electrodes 4| and 44, a voltage impulse is impressed upon transformer 49 connected between the electrodes. To produce a spark between electrodes 42 and 44, a voltage impulse is impressed upon transformer 88 which is connected between these two electrodes, and so on for all the nine intersections. The voltage impulses are impressed upon the transformers in some definite serial order from an impulse generator shown in Fig. 3. Only a portion of this generator is shown but the. missing sections are inserted at the broken lines identical with those illustrated, and need not be shown in detail. The portion of the generator shown is composed of vacuum tubes 81 to 8|, inclusive. These tubes are interconnected .by delay circuits 88 to 88, inclusive, one element of each being a'variable condenser for controlling the rate of generation of the impulses, and consequently the scanning speed of the light produced at the intersections of the electrodes.

Such an impulse generator is disclosed in detail in my copending U. 8. application referred to above.

The filaments of these tubes are shown supplied by a filament battery 18, while the anodes thereof are supplied from the high potential source II. The grids are all biased from a'common grid potential source 12, which has in series therewith a resistance 18. This resistance, shunted by two-way rectifiers 89 and 99 in series with the secondaries oftransformers 88 and 98, is a synchronizing element for the commutator circuit. shunting the grid-biasing battery is a key 14 employed for the purpose of changing the starting impulse, and which may be used for framing the picture when the circuit is functioning as'a receiver. It is also useful for starting the original impulse which, after it is once initia'ted, is propagated through the tubes.

Each tube has aninput and output circuit coupled through respective transformers. For instance, tube 89 has an output transformer I8 feeding two conductors I1 connected to transformer 49, the voltage transmitted therethrough producing a spark or discharge at the intersection of electrodes 4| and 44. Likewise vacuum tube 8| through output transformer I 9 and over conductors 88 produces a voltage impulse in transformer 55, which initiates a spark between electrodes 4| and 48. The other electrode intersections are supplied in the same manner from tubes connected in the generator between tubes 88 and 59.

The output transformers of the various tubes have three windings, the third winding of which is connected in series with similar windings of the other transformer, as shown by -the series circuit 82. This circuit includes the primary of transformer 83 of the synchronizer, and the primary of a transformer 84 in the input of a modulator circuit 88. Each impulse produced, therefore, is impressed upon the input of the modulator system 88 comprising a'vacuum tube 81 and a second input transformer 88, as well as the rectifier 89 through transformer 83. The output of the modulator is connected through an output transformer 98 to a hybrid or separating transformer 9| well known in two-way telephone practice, which permits transmission of the out- .put to an antenna system 92 or wire conductors 98 chosen by means of a switch 94. A balancing network 88 is employed to balance the hybrid coil and prevent the output currents from reentering the system.

Returning to the generator system, the tubes have input transformers which are all connected in parallel and to'the, incoming line at the hybrid coil 9|. Any input impressedupon a tube when operative will be transmitted to the respective intersection of the electrodes in the manner above discussed. The incoming voltages are maintained at a level which is insufllcient to operate the tubes. In parallel with the incoming line is the primary of transformer 98, which impresses the incoming impulses upon the rectiher 88 which is polled reversely with respect to the rectifier 89.

It is obvious that all the tubes shown in the commutator circuit are not connected to the electrodes of the screen. These tubes, namely 51 and 88, are shown connected to a loud speaker I88 and a microphone pick-up device I8l through amplifiers I82 and I89, respectively. The output of tube 81 is connected to the loud speaker through output transformer I88, while the input of tube 58 is connected through input transformer II8 to the microphone. In Fig. 2

is also shown a photo-electric cell device I88.

connected to an amplifier I88 by means of conductors I81 and transformer 88 to the modulator system 88.

As a transmitter, the system operates as follows: The key 14 is closed shorting the grid potential '12, and permitting current impulses to through the pinhole 8 of camera 8 in Fig. 1a, and

onto an object. Reflected light from the ob- Ject will fall upon photoelectric cell I06, will be amplified by amplifier I and impressed upon the input of tube 01 of the modulator 06. The

' two tubes 51 and 50 of the generator are, preferably, placed in the circuit after each complete cycle of the sparks over the scanning screen, the rapidity of propagation causing no appreciable break between cycles in the scanning of the object. impulses from all the tubes, however, will be generated in the series circuit 82 and impressed on the input of modulator tube 81 through the transformer 84. At substantially the same instant that the photoelectric cell currents arrive at the transformer 88 in the modulator, the generator impulse will arrive at the transformer 84 in the same circuit. After passage of the impulse currents,'which are nonoverlapping half cycles, through the trans former 04, they are alternating current of high frequency which is the frequency of the rate of propagation of the impulse through the electrical impulse generator. This high frequency wave will constitute the carrier current necessary for transmission of the photocell currents which modulate it. These modulated picture currents will be transmitted to the'transformer 90 and to the antenna or wire conductors for transmission to a receiver. Each impulse, therefore, not only produces the scanning light, but the carrier cycle for transmitting the photoelectric cell currents produced by this light.

If the objects being scanned produce sound, such sound will be detected by microphone i0i, amplified in amplifier I03 and transmitted to the input of tube 58 through input transformer H0. when the rotating impulse of the generator has reached tube 58, this tube will be-,

come operative through removal of the heavy grid bias obtained from battery '12, and will transmit the sound during the time the im- Lation thereof as a receiver being as follows:

pulse has the bias removed. This impulse will be transmitted to the series circuit 82 and into *the modulator system 08 through transformer 84. Since this tube produces no light on the screen, there will be no photoelectric currents to interfere with the modulation of this cycle in the modulator 86, and the sound currents modulated in tube 58 will, therefore, be transmitted between photoelectric cell current modulations. Since the impulse occurs at the tube 58 at such a high rapidity, sufficient portions of the sound signal will be transmitted to constitute intelligent reception thereof at the receiver. A more detailed explanation of this operation will be foundin' my copending application referred to above. a

The impulses produced as described, are transmitted, and may be received on a system-identical with the one shown in Figs. 2 and 3, the oper- The impulses are received over'antenna system 92 or wire conductors 98 and transmitted through hybrid coil ill in the direction shown by the arrow arriving at the input circuits of all-the tubes simultaneously through respective input transformers. The same screen may be used as a receiver without the pinhole camera shown in Fig. la. As a receiving screen, an observer will see only a solidly lighted screen of one light intensity when no received currents are being transmitted to the screen. As the currents are received from the transmitter in the input circuits of the. tubes, the impulse transmitted to the screen is varied in intensity. That is, it may be of lesser brilliance or greater brilliance in accordance with the modulation thereof by the photoelectric cell currents at the transmitter. For instance, an impulse may be received in the tube I50 such that it will reduce the amplitude of the rotating impulse, and therefore, produce a lower voltage at the transformer 40. The discharge between electrodes ll and 44 is now of less intensity than that produced by the tube with the normal or local impulse. The reverse action occurs if the incoming impulse increases the local generating impulse. The reception, therefore, of varying strength signals or impulses at the various tubes at definite times, will produce a changing intensity of the light produced at the intersections and reproduce on the receiving screen the corresponding light and shade intensities of the object being scanned at the transmitter.

The transmitting and receiving impulses are kept in step and in the same order by the automatic synchronizer 13. The locally generated impulses are impressed through the transformer 03 on the rectifier 09, and produce a direct current voltage drop across resistance 83 which will alter the grid biasing voltage in a certain direction. The incoming impulses are impressed upon the rectifier 09 through the transformer 08, and produce a biasing potential in the reverse direction with respect to the impulses received through transformer 83. The amplitude of these impulses impressed on the rectiflers is adjusted so that when the systemis at synchronism, that is, the generators at the receiver and transmitter, are rotating at the same rate of speed, the impulses received will exactly neutralize each other and there will be no change in grid bias on the local tubes. However, should one or the other of the generators tend to stray from synchronization, a differential voltage will be obtained which, when rectified, will produce a bias, in the proper direction to speed up orslow down one or the other of the systems. The speed of rotation is controlled by the length of time an impulse takes tov pass through a tube, and is dependent upon the amplitude of the impulse. By reducing the amplitude of the impulse in each tube, a more rapid propagation may be obtained by a circulating impulse. Of course, any appreciable speed change is effected by the tuning elements of the delay circuits 63 to 06, inclusive, which may be mounted so adjustments may be made as a single unit.

It will be noted that a third function of the generated impulses has now been described. That is, the impulses provide the scanning or image light, the carrier frequency for transmitting. the photocell currents, and the grid biasing voltage to control the speed of generation of the impulses which maintains synchronism between any two generators.

The sound which has been transmitting on the definite impulsecorresponding with tube 58 will be received in the input circuit of tube- 51, as these connections are reversed at the transmitter and transmitted through the output transformer. I00 to the loud speaker I00, the loud speaker being placed in an appropriate position with respect to-the screen, to reproduce the sound with the picture. The transmitting and receiving sound circuits are maintained separately by separate time channels by the generators operating in synchronism.

To accomplish two-way transmission it is only necessary to provide a function changing ele- 4 will serve.

ment which will change the function of the system from a transmitter to a receiver and vice versa at a super-audible rate such as not to interfere with the continuity of either function. A system of this type is disclosed in my copending application Ser. No. 397,826, filed October 7, 1929. I

In Fig. 4 a screen H5 has ten co-ordinate electrodes in either direction, which provides 100 intersections or light points. In the connections of the system of Figs. 2 and 3 such a screen requires 100 transformers which may increase the expense of such a system beyond practical limits, and prohibit its manufacture. To reduce this number of transformers, however, the system of Fig. In this system two commutators which operate at different rates of speed are provided. For instance, a commutator H6 rotates as rapidly as a commutator H1. Each of these commutators are generators of the same type as shown in Fig. 3, except they are connected in series and at different speeds. The segments of each generator shown represents the vacuum tube which has been connected up in accordance with the circuit of Fig. 3, the only element shown being the three winding output transformers. The serial connection of the third winding of these transformers is connected to both generators in serieshaving output terminals H8 which connect to a modulator system 86 and a synchronizer 13, such as shown in Fig. 3. This system operates on a combined voltage basis, that is, it requires the voltage generated by any one of the tubes of generator I I1 combined with the voltage generated by any one of the tubes H6 to produce a light or spark where an electrode I20 and an electrode I2I intersect as point I22. To produce a spark at this intersection, a voltage must be generated by tube I24 in series with tube I25 of generator I I1. That is, the circuit is from electrode I20 through the secondary of the output transformer of the tube I24 through the common conductor I26, the secondary of output transformer of tube I25 to electrode I2I. To produce a spark at the other intersections of the electrode I20, the generator H1 makes one complete cycle before the impulse passes through tube I24 of .the generator H6. In this manner light discharges are produced along electrode I20. As the impulse then changes from tube I24 to tube I28 for instance, light will be produced at all intersections along electrode I29, as an impulse rotates around the system I I1. In other words the system H1 is rotating ten times as fast as the system I I6.

Referring to 'Fig. 5, a chart is shown between time and amplitude of the generated impulses for this system. The generator H6 is generating a voltage shown by the three positive wave sections "a, b and 0, while superimposed thereon are the smaller amplitude impulses produced by the generator H1. The amplitude of the impulses a, b and c are insufficient to produce a spark unless augmented by the impulses produced by the generator H1. By the use of this arrangement, therefore, the amount of apparatus required is considerably smaller than that of the systems of sources I36 in the form of incandescent lamps. These light sources may be of any type, however, such as the co-ordinate electrodes abovedescribed or neon lamps. The tubes may be bent in various directions within the angle of refraction, to provide more space in the rear of the screen to accommodate the light sources. 'These lamps are ener.

gized from the output of a generator system parbe used in the two generator system of Fig. 4, each.

generator of which rotates at a speed commensurate with the number of light sources employed.

Any other suitable light producing means may be employed in this system, which can be enertially represented by the block sections I31 to I41, I

gized from current impulses produced in the manner disclosed. Furthermore, the system is adaptable to other embodiments of a television system, without departing from the spirit of the invention, and is to be limited only by the scope of the appended claims.

What is claimed is:

1. A television transmission system comprising means for producing rapidly occurring current impulses, a coordinate electrode system, means for impressing said impulses on said system in a serial order, means for scanning an object with a plurality of light beams generated between said electrodes by said impulses, means for transforming light from said object into said electrical currents, and means for mixing said impulses with said last-mentioned currents.

2. A television transmission system comprising a screen having coordinate electrodes separated from one another in two planes, means for producing a plurality of current impulses, means for causing said impulses to flow between said electrodes at a plurality of different positions to produce a plurality of light rays in a serial order, means for transforming said light into electrical currents, and means. for mixing said current im pulses with said last-mentioned currents.

3. In a television system, means for producing current impulses, a. plurality of distributed electrodes, said impulses and said electrodes producing a searching ray of'light for said system in the form of a series of electrical discharges, a photoelectric cell, and means for transmitting on said impulses the photoelectric cell currents.

4. A television system comprising means for producing rapidly occurring current impulses, means for impressing said impulses on a plurality of coordinate electrodes in a definite order to produce a plurality of light beams spatially disposed, a photoelectric cell for receiving changing light intensities 'caused by said current impulses, and means for combining said impulses and the currents generated by said photoelectric cell.

5. A television transmission system comprising a plurality of distributed electrodes, a transmitting impulse current generator' for producing a plurality of light beams at mutually exclusive intervals and spatially disposed between said 'plurality of electrodes in a definite order, means for transformingsaid light into corresponding electrical currents, a similar impulse generator for illuminating a receiving screen in synchronism with the light beams produced bysaid transmitting generator, means for combining said transaorasas formed electrical currents and the output current of said transmitting generator, means for transmitting said combined currents to said receiving.

said elements in a definite order at a rapid rate of speed, means for transforming said light modulated by objects being scanned into electrical currents, means for transforming the sound produced 2 Vby said objects being scanned into electrical currents, and means for successively combining said object modulated currents and said accompanying sound currents with the output currents of said generator in a predetermined order.

8. A television system comprising a transmitting station and a receiving station, means at said transmitting station for producing a scanning ray of light, said means including 'a tandem connected plurality of vacuum tubes generating cur- 30 rent impulses between electrodes, means for transforming said light into electrical current,

impulses characterized by the light and shade densities of an object, means for combining said last mentioned currents with said generated cur- 35 rent impulses. means at said receivingstation for producing light in synchronism with the production of said scanning ray, said means including a tandem connected plurality of vacuum tubes generating current impulses between similarly ar- 40 ranged electrodes, and means for transmitting said combination currents between said pluralities of'tubes to maintainsynchronism between said scanni g ray and said receiver light and to reproduce image of said object. f

45 9; Ina television transmission system in which current impulses characterized by the light and shade of an object are transmitted, a plurality of electrodes arranged to form a definite area, a photoelectric cell, a plurality of electronic de- 50 vices for producing said currentimpulses at a definite rate of speed for impressionon' said electrodes to produce a spatially disposed series of light beasnameans formixing said impulses with the currents from said photoelectric cell, and

'55 means for employing said impulses to control the rated generation of said impulses.

ments, a current impul'segenerator for energizing Y currents.

10. In a television system, a thermionic commutator producing rapidly occurring current impulses, means for impressing a majority of said impulses on a scanning screen for scanning an object, means for detecting sound accompanying the objects being scanned, and means for transmitting said sound on the impulses of said commutator not employed for producing scanning i a t.

'11. In a television transmission system, a plurality of electrodes disposed in parallel, a second plurality of electrodes disposed in parallel and normal to said first plurality of electrodes, a plurality of vacuum tubes arranged in tandem to transmit therethrough a current impulse in serial order, means for connecting the output of each of said vacuum tubes to electrodes 'at mutually ex-p elusive intersections, the output voltage from said tubes producing an electrical discharge between said electrodes at said respective intersections. means for transforming a portion of the light from said discharges into electrical currents, and means for combining-said current impulses and said last mentioned currents for transmission to a receiving point.

12. In a television transmitting system, a plurality of'electrodes disposed in parallel in one plane, a plurality of electrodes disposed in parallel normal to said first plurality of electrodes in a second plane equidistant from said first plane,-,

a. plurality of thermionic devices having their output circuits connected to said electrodes, said thermionic devices producing at respective intersections between said pluralities of electrodes discharges in a pre-arranged order, a modulating device, means for impressing on said modulating device the output of all of said thermionic devices,

means for transforming the light from-said electrical discharges into corresponding electrical currents, and means for impressing upon said modulator said transformed electrical currents for transmission as modulations of the output forming said light beams into corresponding electrical currents in accordance with the light and shade densities of said object, and combining the current impulses 'withlthe transformed electrical Amman McLEAN moor-eon.

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