US2146876A - Intelligence transmission system - Google Patents

Description

Feb. 14, 1939. v, K. zwoRYKlN INTELLIGENCE TRANSMISSION SYSTEM Filed Jan. 4, 1957 3 Sheets-Sheet l BY 5 u 4 ATTORNEY lll" Feb. 14, 1939.

v. K. zwoRYKlN 2,146,876

INTELLIGENCE TRANSMISSION SYSTEM Filed Jan, 4, 1937 3 Sheets-Sheet 2 '7L o l ./I y

INVENTOR I VLADIMIR K.ZWORYKIN I IIJ UME ATTORNEY Feb. 14, 1939.

V. KA ZWORYKIN INTELLIGENCE TRANSMISSION SYSTEM 5 Sheets-Sheet 3 Filed Jan. 4, 1937 SAM/7007.1

INPUT v Fay. 8a

`/l/lU/l/ 70 Mom/mm@ 0F MMM/fm2 SOI/RCE INVENTOR vLAmMlR KJWORYKIN v ATTRNEY Patented Feb. 14, 1939 UNITED STATES.

2,146,876 m'rELLIGENcE TnANsMrssioN sYs'rEM Vladimir K. Zworykin, Philadelphia, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application January 4, 1937, Serial No. l119,026

21 Claims.

The present invention relates to television systems and is particularly directed to television systems wherein the pictorial action is transmitted with all accompanying sound indications which occur with and are coordinated with the pictorial representation.

This invention is a continuation in part of my copending application Serial No. 665,098, flied April 8, 1933, and entitled Intelligence transmission systems".

In sound motion picture work it is customary to produce a lm record on which there are a series of pictorial representations intermittently produced with which, and usually adjacent these pictorial representations, there is also a continuous record of the sound which accompanies the pictorial action. Such a sound record may be of various types such, for example, as the variable density or the variable width type recording, or

' the sound action may appear upon a separate record from which itv is mechanically or electrically reproduced. In such a case, however, the reproduction must be accurately coordinated with the lm in reproduction so that there is no observable lapse of time between the observation of the action and the hearing of the related sound.

Television, it has been found, is improved to a considerable degree where the observation of the reconstructed image of the object at the point of transmission is accompanied by a series of sound signals which serve to make the visual action more realistic.

It is with a view to producing a television system having characteristics of this general nature that the present invention is developed.

In the prior art, so far as I am aware, frequent endeavors have been made to transmit simultaneously both image and sound signals, as well as signals to synchronize both the image and the sound, but these previous endeavors usually involved transmitting the picture signals upon one carrier frequency and transmitting the sound signals upon another carrier frequency which is separated from the picture signal or television carrier by a predetermined separation, usually at least equal to the frequency separation corresponding to the highest modulation frequency of the television transmitter. -According to another system previously suggested in the prior art, as shown for example by `Goldsmith et al. Patent No. 1,770,205 assigned to Radio Corporation of America, it has been suggested to transmit the television signals as modulations of one carrier frequency and then` to modulate a second carrier 55 frequency by the sound signals and then, in turn, l

(ci. 17e-5.6)

to modulate the television carrier also by the sound modulated carrier frequency.

The present invention attempts to improve upon vthese systems of the prior art and has as its principal aim and object that of transmitting 5 both the television and sound signals, as well as. any desired synchronizing signals, upon the same carrier frequency so as to avoid thereby the necessity of generating independent carrier frequencies and providing more than a single modu- 10 lator for modulating the generated carrier by both the television and the sound signals. In

this system sight and sound transmission is so interlocked that the presence of one type of signal substantially assures the presence of the other. 15

In television transmission the frequency band required to transmit a satisfactory image representation is a function of the number of complete image transmission, that is, thevscanning frequency, as well as a function of the number of 20 image points into which each image is assumed to be divided for the purpose of transmission. In transmitting 24 complete image representations per second, for example, which are each assumed to be divided for transmission into 250 elemental strips, each composed of 300 individual elemental areas, for example, it can be seen that the frequency band required approaches 1 megacycle.

When recourse is had to the cathode ray tube as a transmitting and/or receiving instrumentality it is customary to use the cathode ray generated within the tube to scan an object or to reproduce an image of the scanned object for approximately 1% of the time available. This practice originates because of the fact that the cathode ray to scan or to reproduce a picture traverses -either the photo sensitive element of the scanning tube 0r the uorescentscreen of the receiving-tube at a relatively slow speed in one direction but at a rapid speed in the other direction lso vthat the o scanning or analyzing appears to occur always Y inpone direction. The 116 of the time lost from scanning or reproduction occurs during a reversal of the cathode ray beam from a maximum deection toa position of starting or minimum deflection.

This reversal of the cathode ray has commonly been termed the return line period and in this period it is customary to transmit a synchronizing signal-by which the synchronizing signal generators or oscillators at both the transmitter and receiver may be locked in step so as to cause the cathode ray beam at both the transmitter and the receiver to operate synchronously. Where the frequency band required is of the order of 54 1 megacycle it is seen that there is, in fact, a loss of substantially 100,000 cycles of intelligence transmission occasioned by the reversal of the cathode ray beam and this full loss cannot be compensated by the inclusion of the synchronous signal within the time period of reversal oi.' the cathode ray, since the synchronizing signal usually requires only substantially V2 oi.' the reversal period for transmission. Hence, it is in this time period which heretofore has been lost, so far as intelligence communication is concerned, that it is proposed to transmit the sound signals which accompany the picture action for each assumed elemental strip of the subject which is reconstructed by the cathode ray at the receiver in its slow transversal from one edge portion to the opposite edge portion of the uorescent viewingscreen.

Therefore, it is an object of the present invention to transmit a combined television and sound indication upon a single carrier modulated sequentially by television and sound signals and, where desirable, also modulated in the time space between the occurrence of the television signals and the sound signals by such synchronizing as may be necessary to frame and synchronize properly the reproduced images.

It is a further object of the present invention to provide ways and means by which sound and television signals may be transmitted upon a single carrier frequency without causingany interfering action one with the other.

It is still a further object of the invention to provide a system for transmitting sound signals related to television image'signals in which the sound signals occurring within a relatively long time period may be transmitted within a relatively short time' period and then caused to become audible at the points oi.' reception during the same relatively long time period as they occurred at the point of transmission.

It is a further object of this invention to provide ways and means for condensing' the sound occurring within the time required to scan a single elemental strip of a subject 4of whichthe image is desired and then to transmit in .the interval between the periods of transmission oi.' signals representative of the successive elemental strips of the subject this condensed sound record which at the points of reception is again expanded and caused to produce audible signals reproducible simultaneously with the production of the next succeeding series of light values corresponding to the next succeeding elemental strip of the subject oi' which the image is being produced.

It is a further object of this invention to provide a system wherein a condensed sound record may be produced as a series of electrostatic charges occurring within a relatively long time period and then transmitted in inverse order during a relatively short time period, after which the transmitted sound signals produce at lall pointsof reception a similar electrostatic record in inverse order to that of the sound production and in condensed form from which it is then expanded so as to become audible during a time period corresponding to the time period required ior the production ci the original electrostatic record from which the sound signals are transmitted.

A further object of the invention is to provide a television system wherein appropriate control production of and the transmission of the electrostatic sound indications produced by voice or equivalent modulation.

Further objects and advantages of the invention are to provide a system for transmitting a combined television and sound record which is considerably simplied from the systems at present in use and in which no interference between sound and picture signals can arise; to provide a system which is simple in its construction and arrangement of parts; to provide a system which can be compactly arranged in a receiving instrumentality so as to adapt more easily the system to commercial use; and to provide a system for receiving television and sound signals which can be distributed and sold at retail at a minimum purchase price.

Still other and further objects of the invention will be pointed out in connection with the description of apreferred embodiment of this invention, while many other objects will naturally suggest themselves to those skilled in the art to which the invention is directed by reading the following speciication and claims in connection with the accompanying drawings wherein:

Fig. 1 is agraphical representation of the curve plotting the amplitude f the cathode ray deflection with respect to time and represents a single traversal of the cathode ray for example from right to left and left to right;

Fig. 2'illustrates in diagrammatic form a system for storing sound signals as electrostatic charger which later may be utilized to transmit an audible record;

Fig. 3 illustrates in conventional manner a suitable system for transmitting combined television and sound signals;

Fig, 4 illustrates a receiver system for cooperative use with the transmitter shown by Fig. l;

Fig. 5 illustrates in portion (a) the scanning and return line path of several traversals of either viewing screen of the receiver or light sen- 'sitive element of the transmitter, `and portion (b) indicates conventionally the signals representative of both picture synchronizing and sound for onesingle scanning line;

Fig. 6 diagrammatically represents the tube used to store as the electrostatic charges a series of sound signals' occurring within the scanning period of a single line of a subject of which the image is'being produced, and in this iigure the portion (a) represents a top portion looking down upon the tube shown, for example, by Fig. 2, and portion (b) indicates a lower view of the storing elements of the tube of Fig. 2, for example;

4 Fig. 7 diagrammatically illustrates a wave shaping circuit for producing saw-tooth current for use in the deecting circuits;

Figs. 8a, 8b andr 8c illustrate graphically voltage waves and a current wave as an aid to explaining the operation of the circuit'shown in Fig. 7, and

Fig. 9 shows in greater detail one of the embodiments which the system i'or storing sound illustrated in Fig. 2 may take.

To make' reference now to the drawings forming a part of this specication and disclosure, it can be seen, from the showing of Fig. 1,'that the time required to produce one single picture line or, in other words the time required to scan one single elemental strip into the subject of which the image is desired isi-assumed to be divided. can for purposes of illustration be regarded as, unity. This 'time period may then be assumed to be divided into two distinct portions desi- -nated as I and II. During the time period designated as I the curve of amplitude against time is seen to rise from substantially a zero value to a maximum, and during the time period II is seen to return again to a zero value. For purposes of further explanationv the time period I has been further identified as A and it is during this period that the cathode ray which may be assumed'to sweep from the left edge of either the light sensitive element or plate of the transmitter or the uorescent screen of the receiver. 'Ihis motion or deflection of the cathode ray pencil or beam occurs at a relatively slow rate. However, as soon as the cathode ray beam reaches its maximum amplitude of swing in one direction it must be returned rapidly to the starting position so as to be prepared to .traverse again the photo-sensitive plate of the transmitter or the uorescent screen of the receiver and it is this portion of the swing or deilection motion of the cathode ray'that is identied as the portion II of the curve of Fig. 1. During the period II nov pictorial intelligence can be transmitted and therefore, this time period, which amounts substantially'to 110 of the total time period available, is lost so far as pictorial intelligence trans- 'mission is concerned. It is, therefore, during this time period that it is proposed, according to the present invention, to transmit both the synchronizing and the sound signals. The return line period designated as II is, therefore, assumed to be divided into three'distinct periods or portions B, C, D. During the periods B and D synchronizing signals serving to synchronize the cathode ray beams at the transmitter and all receiving points may be transmitted, and during the portion C, which otherwise is not utilized for transmission, it is proposed to transmit all of the sound which occurred during the period A which represents the period pictorial intelligence transmission.

If it is assumed that the pictorial subject of which the image is desired is divided into 250 elemental strips, for example, and the rate at which complete pictorial representations are transmitted is 24, then it is seen that the total time required to move the cathode ray from a position of zero amplitude to a maximum and back to a zero amplitude is of the order of 143000 of a second and that the time period required to move the cathode ray from a position oi maximum to a minimum amplitude is of the order of 1450000 of a second. Therefore, it is during this $60000 of a second time period which otherwise cannot be utilized except to transmit the synchronizing signal that the sound signals occurring within the period designated as A or during 1% of each $0000 of a second time period should be transmitted.

If reference is now made to the showing in Fig. 2 sound signals which may be producible either by optically analyzing the sound record portion of a motion picture iilm record through appropriate light translating elements or which may originate through the mechanical or Aelectrical pickups from a phonograph type of record or which may be spoken, for example by the subject being televised, are caused to iniiuence and modulate a microphone I which is connected with an appropriate amplier 3. 'I'he output signals from the amplifier 3 are then caused to control and modulate a cathode ray 5 generated within the cathode ray tube I so as to control in amanner generally similar to the system for control of the cathode ray shown and described by patent to Nicolson No. 1,470,696 assigned to Western Electric Company, so as to permit the production of an electrostatic sound record in a manner to be hereinafter described." i

The cathode ray tube 'I is provided with the usual electron emitting cathode 9, a grid control element II and an anode I3. Instead of a iluorescent endwall, as shown by the above mentioned Nicolson patent, the cathode ray tube 'I is provided atits end portion opposite the electron source with a series o! storage or' condenser elements, generally designated at I5, which will be described more fully as to their construction in connection with the description oi. Fig. y6. In general it may be stated that the condenser elements I5 are formed from a conducting end plate Il adjacent to which is a layer of mica or other suitable insulating material I9 to the under side of which is a second conducting plate, generally designated at ZI. A carbonized material 23 coats independent sections of the plate 2l so as to form from the metallic layer 2| a member which has sections of different electrical properties s0 that there is a variance in the emission of secondary electrons over diierent portions of the plate or electrode area.

If now the cathode ray pencil 5 -generated within the cathode ray tube is modulated as suggested by the above named Nicolson patent, by the signals appearing in the output of the ampliiler 3 which are connected to the grid and cathode elements II and 9 of the tube I by way of conductors 25 and 21, the modulated cathode ray pencil will be capable of producing diierent electrostatic charges upon the individual condenser elements including the plates I 'l and 2| separated by the insulating layer I9. These varying charges represent the varying amplitude sound modulation frequencies appearing in the output circuit of amplier 3 during the scanning period A. As these varying charges are being produced the cathode ray pencil 5 is, according to the showing of Fig. 2, moved from right to left by means of varying voltages applied from a source (not shown here but illustrated' in Fig. 3) in accordance with the amplitude-time curve of Fig. 1 to the defiecting plates 29, 29' by way of conductors 3l and 38 of which thelatter is grounded at 35. or connected to the cathode element or the tube which is grounded at 35.

Suitable anode potential to cause the cathode ray to be projected from the cathode 9 to the condensers I5 is supplied between the anode element I3 and the cathode 9 by wayV of a battery or other suitable source 35, which in a commercial installation is usually the well known socket power unit serving to Supply all operating voltages from an alternating-current source.

Let it now be assumedthat the cathode ray pencil 5 is moved from its point of greatest deection tothe left of the position shown in Fig. 2 over to its maximum deflection at the right of Fig. 2, or that voltages have been supplied to the delecting plates 29, 29' as shown by-the portion o, a. of the curve I of the curve of` Fig. 1 so that the cathode ray is just ready to'move rapidly from right to left, or in other words from'maximum to minimum deflection, accordingto the portion of .l curve of Fig. 1 designated as-II. Y

the grid cathode circuit ot the cathode ray tube 1. The cathode ray pencil 5 is consequently.

free from intensity variations and is, therefore. at normal" intensity during the period when it sweeps from the right hand portion of the condensers I5 of Fig. 2 over to the left hand portion, and secondly, the charges which have been stored in the various individual capacity elements forming the condenser element l5 are discharged. These charges are then applied to the input circuit -of ampliiier 31. Amplifier 31, during the period when sound modulation frequencies are supplied to the grid-cathode circuit of the cathode ray tube 1 is biased to cut-off by the same variable biasing source now serving to bias the amplier 3 to' cut-oil'. Therefore, during the period of rapid traversal of the cathode ray across the several condenser elementsy I5 the sound signals which had been converted into electrostatic charges appear in the output circuit of the amplifier 31 which connects to the modulator of the transmitter (not shown ln this figure) in inverse order to that of their production. Thus, the sound signals are amplified and transmitted within a time period substantially no greater than 1,6 of the time period during which the sounds were produced.

As soon as cathode ray pencil 5 is returned to the plate at the extreme left hand edge portion of the tube 1, looking at Fig. 2, thevariable bias source serves tobias the amplitler 31 to cut-oi! but no longer aiects'amplifler 3. In this manner, amplifier 3 is again able to supply sound modulated signals to the grid electrode of the cathode ray tube and thus to charge again the various capacity elements to diilerent degrees for the purpose of producing an electrostatic record of the sound originating at the microphone i within the time period corresponding to the slow traversal of the cathode ray from left to right, after which the same sequnce of events hereinabove mentioned is repeated again and again until the entire picture and sound transmission is complete.

Reference may now be made to the showing in Fig. 3 of the drawings whichv illustrates, partly in schematic form, a complete television transmitting system provided with means for-transmitting related sound signals. In this arrangement, for convenience of illustration, it has been assumed that a motion picture film 4I is the subject of which the image is desired, although, of course, it is recognized that any type of subject or an indoor or outdoor scene may be substituted for the film without departing from the spirit and scope of this invention. If a film subject 4l is used as the subject from which visual intelligence is to be transmitted, this subject is moved, preferably intermittently, relative to the scanning device, such as the cathode ray tube 43, in the general direction shown by the arrow. Each frame portion of the film subject 4I is illuminated from an intense light source 45, such as an arc or other suitable type, which directs the issuing light therefrom through an appropriate optical system 41 through to the film. In.

accordance with the varying transparency of the lm light of proportionately controlled intensity is directed by means of a second optical system 48, which is'usually formed from a plurality of individual lens elements, so as to be focused upon the light sensitive electrode or plate 5i contained within the scanning tube 43. The scanning tube in the form herein illustrated may be of the samegeneral construction as was andere shown and described in my co-pending application Serial No. 574,772 iiled November 13,1931 and assigned to Radio Corporation of America (Docket #2000) wherein there is disclosed the screen structure 4l in the form of an insulating sheet upon one side of `which is a thin conducting nlm 50 and upon the other side of which is a uniformly distributed series of individual photosensitive elements 5|. These photosensitive elements may, where desired, be formed in the manner disclosed by Sanford F. llissigv in application Serial No. 594,779 filed February 24, 1932 (Docket RCA Victor 2059) and assigned to Radio Corporation of America.

Within the scanning tube 43 there is generated by means of the co-operatlve action oi' a cathode 53 and an anode 55 a cathode ray pencil 51 which is adapted, when suitably deiiected in a vertical plane by the electrostatic deiiecting plates 50 and 59' and in a horizontal path by the electromagnetic deflecting coils Bi and 5I', to sweep the entire area ofthe light sensitive plate 5I. Whenever light from the nlm is projected upon elemental areas or sections of the light sensitive electrode or plate 5I the individual elements thereof emit electrons and take on positive charges corresponding in value to the light intensities to which they are subjected. Thus. an electrical image of the subject or object is developed over the surface of the screen structure.

In orderto utilize the electrical image to reproduce at a receiving station the electrostatic charges referred to are neutralized or discharged successively by causing the cathode ray pencil 51, to scan the photosensitive surface 5I under the influence oi the electrostatic deiiecting field produced between the deflecting plates 59 and 55' and by the electromagnetic deiiecting eld produced by the coils 8l and 8l'.

For the purpose of removing the electrons of the ray pencil 51 which are not required to neutralize the respective positive charges accumulated by the individual photosensitive elements I5, as well as the electrons emitted by these elements in taking on these charges, a suitable collector or anode 63, in the form of a screen, is supported in the proximity to the photosensitive surface of the screen structure and is maintained at a positive voltage through conductor 13 connecting to a suitable source 11, leading to ground at 61', as shown.

The successive discharges oi' the positive charges upon the individual lements 5|, as explained, causes corresponding current impulses or picture signals to4 be developed across the resistor 83 in the grid or input circuit of a suitable picture signal ampliiier 85, for which purpose the platinum film 50 is connected to this-circuit by a conductor 69 and one of the wire supports 52 carrying the screen structure 40.

The synchronizing signals for deflecting the cathode ray pencil 51 in a horizontal direction are generated in a synchronizing signal generator 11 which generates a wave of the saw-tooth type substantially as shown by Fig. 1. These signals are supplied to the horizontal deflecting coils 6l and 6I' by way of the conductors 19 and 19' and the shaping circuit |19. Similarly, the verandere higher frequencies, however, diculty arises in that the deflecting electrodes constitute a con denser and the upper harmonics present in a sawtooth wave are of such high frequency that the impedance of the condenser represented by the deflecting plates |51 virtualy short circuit these components and destroy the linearity of the sweep voltage with respect to time.

Accordingly, electromagnetic coils through whicha suitable voltage wave may be applied is desirable. It should be understood, of course, that to apply a saw-tooth voltage wave to such coils would also result in distortion since the impedance of the coils at highfrequencies discriminatesagainst high frequency current components. To overcome this difficulty, the saw-tooth wave is passed through a wave shaping circuit 119 which predistorts the voltage wave so that when the distorted voltage wave is applied to the deecting coils a truesaw-tooth current wave results. The saw-tooth current wave, therefore, produces an electromagnetic field which builds uplinearly with time. Such a wave shaping clrcuit is shown in Fig. 7 and is in form of the same type of circuit described in considerable detail in an application numbered 544,959 by Arthur W. Vance, entitled Intelligence transmission systems, which application was iiled June 17, 1931 and upon which application a British Patent No. 395,499 has been issued on July 30, 1933.

Referring now to Fig. 7, a saw-tooth wave as shown in Fig. 8a is applied to the input of the wave shaping circuit 119 across the resistor 205. This wave is amplified by the triode 20! and across the plate circuit of this tube there appears avoltage wave shown in Fig. 8b. The inductance 201 may be of the order of 100 henrys or more, so that it acts substantially as open circuit for the alternating current components but permits the D. C. plate current to be maintained constant. Connected in parallel with the inductance 201 is serially connected resistor 209 and condenser 2| l. The grid of the tube 203 is connected to the serially connected resistor and by suitable adjustment of the movable tap on the resistor 209 the proper wave shown in Fig. 8b can be obtained. This voltage wave isv linearly amplied by the tube 203 and the lconstance of the choke 213 and the condenser 2| 5 are so-chosen as to present a voltage wave across the terminals 2I1 which is substantially proportional to the voltage wave shown in Fig. 8b. This voltage wave applied to deflecting coils, for example, |61 and |63, then produces a saw-tooth current wave as illustrated in Fig. 8c. From the terminals 211 leads are likewise brought down to the amplifier bias source |29 for the reasons as will be pointed out more fully below. It will be understood that in accordance with the teachings of the Vance application and patent, the condenser 2H may have substituted for it an inductance, the choice oeng merely one of convenience.

The frequency of the horizontal synchronizing signals is equal to the number of elemental strips into which each image representation is assumed to be divided for purposes of analysis multiplied by the number of complete image representations per second.

As varying voltage drops are produced across the resistor 65 so' as to represent the varying light values reaching the light sensitive element 5i various potentials on the control grid of the ampliiier tube 85 produce proportionate output currents which are then transferred to a second amplifier 81, usually a multistage amplifier, whose output is connected. to the modulator 89. The oscillator 9i serves to generate the carrier frequency and connects with the modulator 59 which is in turn connected with the transmitter amplier 93 from which the energy output is -transmitted to various points of reception either by way of a radio transmission linlr from the antenna 95 or by way of a wire line' transmission link, where it is desired to send the television signals over a Wire line.

As was explained above in connection with Fig. 2, sound signals may be supplied directly to the microphone i or may be translated from the lm record 4| which is being explored for image' transmission purposes. The sound signals there l converted by the microphone or photocell into electrical signals are then supplied to the sound signal amplifier 3. As was also explained. in connection with Fig. 2, there sound signals appear across the grid cathode circuit of the vcathode ray tube 1 and serve to modulate the generated cathode ray pencil 5 within this tube. The

output signals which are produced from the electrostatic charges formed in the condenser elements I5 are Asupplied to the amplier 31. YTo each of the ampliers 3 and 31 there is connected an amplifier biasing source 91 controlled from the synchronizing signal generator 11 for horizontaldeilection of the cathode ray pencil which serves alternately to bias ampliers 3 and 31 to cut-ofi. The amplier biasing source 91 may be, for example, the device shown in co-pending application of H. Branson, Serial No. 644,417,

led November 26, 1932, and entitled Ainpli-r ers on the basis of which application British Patent No. 415,619 was accepted August 30, 1934, or the circuit shown and described in the Branson British Patent No. 834,891, accepted September 11, 1935, or the Shore Patent No. 2,005,111 issued June 18, 1935, and entitled Ampliers.

It is desirable to maintain cut-0H bias on amplifier 31 for a relatively long time period, or in other words for a time period represented by the time period I of Fig. 1, and during this same Atime period I the amplifier 3 should be maintained in an operative state, whereas for the time period II (see Fig. l) the amplier 3 for sound signals should be rendered inoperative, or in other words biased to cut-o, whereas amplifier 31 should be operative. To produce this result the biasing action produced from the bias source 91 and eiective upon amplifiers 3 and.31 changes in accordance with the rate or frequency of the synchronizing signals generated so that the ampliers 3 and 31 are rendered alternately operative and inoperative for time periods corresponding to the above enumerated conditions.

vThe operation of the bias ampliiier 91 will now be described in detail. Referring nowto Fig. 9, there has been shown in detail the conventional ampliers for the microphone and for the sound channels 3 and 31 respectively together with the bias amplier 91 which, for purposes of illustration, is shown as the type of amplifier disclosed in the Shore Patent No. 2,005,111 referred to above. A voltage wave havingthe shape shown in Fig. 8b is derived from the .output of the wave shaping circuit |19 and fed to the input terminals 2|3. The tube 22| is normally biased t0 cut off by the battery 223 so that there appears Vacross the plate resistance 225 no voltage drop. The plate resistor 225 is also made part of thecathode grid circuit of tube 231 of the amplifier 31 and under vsuch conditions, voltages applied to the terminals 239 are linearly amplified through the tubes 231 and 233, the output of which is fed to the modulator of the transmitter. The tube 23| has its grid connected to the plate resistor 225 and is biased by the battery 233 to an appropriate value-so that current normally flows through the plate. resistor 235, under the conditions of tube 22| being biased to cut-off. The voltage drop across the resistor 235 is fed to the tube 221, in its cathode grid circuit, and'in such polarity as to bias the tube 221 to cut-oil and of such magnitude that any signal voltage applied from the microphone is insufficient to actuate the amplifier. A condenser 240 is connected from the plate resistor 235 to the grid of the tube 22| in accordance with the teachings of the Shore patent, referred to above. When the voltage wave of the form shown in Fig. 8b is applied to the terminals 2|9 current begins to flow in the plate circuit 225 of the tube 22|, producing a voltage drop, which is then amplified by the tube 23| and a portion of the energy fed back as positive regeneration to the input circuit of the tube 22|, which process repeats until saturation current flows in the tube 22|, 'under which conditions, tube 23| has so much negative voltage applied between its .grid and cathode by virtue of the voltage drop through the resistor 225 taking place, due to current flowing through tube 22|, that the tube is cut of! so that no plate current ows through the resistor 235. Under these conditions the voltage drop across the resistor 225 is now sufficient to cut 0E the tube 231 so that' there is no longer any voltage fed to the modulator of the transmitter. At the same time, since there'is no plate current flowing through the resistor 235, tube 221 is biased linearly by the battery 228 and signal voltage obtained from the microphone is linearly amplified and has its output passed on to the elements I I and 9 of tube 1. When the linearly increasing portion of the wave shown in Fig. 8b ceases. and the abrupt collapse takes place, the operation of tubes 22| and 23| are reversed, since the tube 22| goes back to its cut oi condition and thetube 23| begins to draw current. Under these conditions then, the amplifier 3 is rendered inoperative, and the amplifier 31 is rendered operative. It will thus be observed that the microphone amplier is operative during a relatively long period and the amplier 31 .operative only during a short period.

The horizontal synchronizing signal generator 11 which serves to move the cathode ray pencil 51 transversely in the scanning tube 43 is also connected by yway of conductors 3| to the deecting plates 29 and 29' of the tube 1 so as to cause the generated cathode ray pencil 5 to move back and forth across the tube in an appropriate manner.

The sound signal amplier 31 connects with the modulator 39 so that the. amplified sound signals serve also to modulate in modulator 39 the generated carrier frequency as generated by the oscillator 9|. The. sound modulated carrier frequency signals are likewise suitably amplified in the transmitter amplifier 93 andl transmitted from the antenna 35 or by way of a suitable wire line connection to all receiving points.

If the synchronizing signals are generated in the generators 11 and 3| are supplied to the modulator 33 in such manner as to be 180 out of phase with the picture 'signals transmitted to the modulator 39 by the amplifier 31 and the sound signals transmitted to "the modulator 39 by the amplifier 31 vthe synchronizing signals will correspond substantially to black signals, as has already been disclosed in the co-pending applicationof R. D. Kell, Serial No. 565,953 filed September 30, 1931 and assigned to Radio Corporation of' America (Docket #1607). y

In this manner the signals which are transmitted from the transmitter amplifier 93 follows the following sequence:rst, picture modulated signals which occur during a relatively long period of time designated as time period A; second, synchronizing signals occurring during a relatively short period of time designated as time period B; third, sound signals .which also occur during a relatively short period designated Vby the time period C; and then fourth. where suggested by Fig. 4. Where the transmission is by radio the signals may be received upon the antenna system 91 and suitably amplified and.

detected in a receiver detector amplifier 99 to which the output of the local oscillator |0| is sup-l plied. The resulting intermediate frequencies are then amplified in the intermediate frequency amplifier |03 from which the sound signals may be detected by the detector |05 and from which the picture and synchronizing signals may be detected in the detector |01.

The sound signals detected in detector |05 are then suitably amplied by the amplifier |09and are supplied to the cathode ray tube III across the grid and cathode elements I I3 and I I 5 respectively so that .the cathode ray pencil I|1 passing beyond the anode I I9 is controlled in intensity in proportion to the received sound signals. This intensity controlled cathode ray pencil |I1, which is synchronized in its motion with the cathode ray pencil 5 of the tube 1, then charges a series of capacity elements generally designated I2| during its rapid sweep or deection path from right to left to degrees proportionate ,to the received sound transmitted within the time period C shown by Fig. 1. In this manner an electrostatic record of the received sound signals is produced upon the capacity elements I2I and later, as will herein be pointed out, this electrostatic sound record may be utilized in inverse order to that of its production to cause at each receiving point an audible record of the sound which influenced the microphone or other form of pick-up device I f at the point of transmission.

'This is made possible by causing the cathode ray pencil |I1 to be swept back and forth from right to left and left to right over the capacity elements I2I by supplying varying voltages to the deflecting plates |23 and |23' from the source of horizontal synchronizing signals as generated in the synchronizing signal generator |25. 'I'hese controlling voltages are conveyed to the deflecting plates of the tube I I by way of conductors |21 and |21' so that the cathode ray pencil |I1 in the tube Il is synchronized properly with' the cathode ray pencil |49 of the viewing tube to be hereinafter described. y

As was pointed out in connection with the descriptin of Figs. 2 and 3, the sound signal ampli- -er was alternately biased to cut-ofi' and rennizing signal generator |25 so that during the time period of rapid motion of the cathode ray pencil 1| 1 within the tubey il the input sound signal amplifier |99 may be rendered operative and during the slow vmotion period, corresponding to the time period I of Fig. 1, the amplier |09 is biased to cut-oil or renderedinoperative. It will be noticed that the time period of operation of the i-nput sound signal amplifier |09 thus corresponds to the time period of operation ofthe sound output signal amplifier 31 of Fig. 3 and that the time period of inoperativeness of the amplifier |09 corresponds to the period of inoperativeness of the amplier 3 of Figs. 2 and 3.

As the cathode ray pencil H1 sweeps across the capacity elements |2| of the tube from right to left the amplier |99 is operative. In this way the cathode ray pencil i1 is modulated by the signals received and the capacity elements are charged to different degrees'y proportionate to the sound to be reproduced. During the period when the cathode raypencil H1 is reversed in direction so that it sweeps slowly across the capacity elements |2| of the tube the amplier |99 is inoperative from the amplifier bias source |29, and thus no sound signals can be supplied across the grid cathode circuit ||3 and of the tube which means that the cathode ray pencil I I'i is not variably controlled as to intensity but is, in other words, at full intensity. At this time period the full intensity uncontrolled intensity cathode ray pencil H1, which is now assumed to be moving from left to right within the tube iii will serve to discharge the sound signal charges stored on the capacity elements 12|. These discharge signals are than supplied to the sound signal amplifier |33 which is now rendered operative by the ampliler'biasing source |29 connected thereto by Way of conductors |35 and |35. 'Ihe amplied sound signals which appear in the output circuit of the amplifier |33 are now rendered audible by the sound reproducer |31. This period of audibility since it occurs during the time period designated by I in Fig. 1 corresponds, to the period of operativeness of the cathode ray pencil within the picture reproducing tube, to be hereinafter described. The relatively long time period of operativeness of the sound reproducer |31 coordinates the reproduced sound with the reproduced picture and, at.the same time, the manner of reproduction produces a reversal and expansion intime of the received sound signals so that the sound instead of being heard during the short time period at which it is recorded electrostatically within the tube becomes audible during a relatively long time period and in an order, of course, corresponding to the order of occurrence or pick-up at the microphone of Figs. 2 and 3. So arranged, it can be seen that the sound as it becomes audible is delayed by a. time period corresponding to that of scanning a single elemental strip of the picture, or in other words, if the sound occurred durl ing the period I oi the scanning cycle. designated in Fig. 1 and was transmitted during the time period II of the same scanning cycle, it will become audible during a similar period I of the following scanning cycle. This delay will be unobserved because the human ear isnot sufliciently sensitive to detect such a small time delay in the sound reproduction with respect toL the picture action. In fact, it has been noted that the human ear is usually substantially insensitive to time delays of as,A much as M0 of a second. In the present system the time delay of the reproduced v sound'accordlng to the above assumed conditions may occur with a delay of as little as 115000 of a second with a maximum delay period of one scanning cycle plus the $13000 of a second time period. Y

To reproduce now the picture portion of the transmitted intelligence, the picture signals which have been detected in the detector |91 after suitable amplification in the intermediate frequency amplier E93 are again amplified to a still further degree in the picture and synchronizing signal amplifier IM. So amplified these signals Y are impressed across the control circuit of the voltage relative to the cathode is supplied by way of a battery |53 or directly from the socket power unit. In order to provide for sharply focusing the cathode ray pencil |99 upon the fluorescent end Wall |55 of the tube M3, I have herein shown a system wherebythe beam may be focused*electrostatically as has already been disclosed in my copending application Serial No. 407,- 652, filed November 16, 1929, assigned to Westinghouse Electric @a Mfg. Co., (Docket 14,718) and also which has been disclosed by pending applications of Pierre E. L. Chevallier, Serial Nos. 489,- 957 and 630,397 iiled respectively on October 20, 1930 and August 25, 1932, assigned to Radio Corpoation of America, (Dockets Nos. 5860 and 67 3).

This focusing action upon the generated cathode ray pencil is provided lfor byarranging a second anode member |51 upon the inner tube wall and applying to the anode |51 (from a source of Voltage |59 orvdirectly from the socket power unit) a voltage of the order ofv four times that applied to the anode member l5'. The second anode member |51 extends from the cone-shaped portion of the tube inwardly toward the neck of the tube in the form of a conducting coating so that between the inner end o'f the second anode |51and the anode |5| an electrostatic eld is produced which tends to conne .the electrons forming the cathode ray pencil to a sharply dene'd spot upon the uore'scent screen |55. At the same time the higher voltage upon the sec'- ond anode |51 causes an acceleration of the electron stream after it has been deflected, for

synchronizing signal impulse fromrthe transmitter in accordance with the disclosure set forth in the above mentioned application of R. D. Kell.

Similarly, the cathode ray pencil is caused to move in a vertical direction, or in other words,

up and down across-the screen |55, looking at Fig. 4, by means of the vertical deecting coils IE5 which are connected with the vertical synchronizing signal generating source |61 to which is supplied the vertical synchronizing or framing signal transmitted from the point of transmission. The vertical synchronizing signal impulse serves to synchronize or frame the received image signals in a manner which has also been described and claimed in the above mentioned application of R. D. Kell.

As image signals transmitted from the transmitter 95 within the time period I, as shown by and no resulting light spot appears.

' the curve of` Fig. 1 are received so as to be conreproducing tube |45 from the direction'shown by the arrow 'of Fig. 4 will observe light spots hav'ingjaryingl intensities which correspond to the varying intensities of light and shadow on .similarly coordinated elemental areas of the subject of Vwhich the image is to be produced.

The cathode ray tube |43 and the coordinated sound reproducer |31 may, where desired, be mounted within an appropriate cabinet, as has been disclosed and claimed in-my previously )granted U. S. Patent #1,870,702, with which arrangement it is possible to view the reconstructed image throughoutl a wide angle by observing the image in the lid of the cabinet within which the television image reconstructing tube and the sound reproduoer are located.

. By portion (a) Fig. 5 I have shown aiportion of the fluorescent screen |55 and thereon have indicated by the solid lines M the paths traced by intensity controlled cathode rays, and by the dotted paths S the interruption periodin the produced ray which occurs during theft return line period. The synchronizing signalslwhich,

.as above stated, assume the characteristics of maximum black signals,y cause, when they influence or act upon the control grid |45 of the image reconstructing tube |43, a complete absence or blocking of the cathode ray pencil so that the uorescent screen during the return line period is uninfiuenced by the `cathode ray By the portion (b) of Fig. 5 there is represented in conventional manner the wave form which may be transmitted throughout any one line scanning cycle. By this figure, portion I indicates the visual signals, whereas portion II indicates the synchronizing and sound signals. l

In Fig. 6 there is shown in more detail the 1 storing arrangement of the sound signals in tubes 1 and III. From Fig. 6a, which may be considered as constituting a view looking down on the top of the tube, it can be seen that the end portion of the tube is formed from a conducting plate I1 adjacent to which and immediately beneath which is an insulating plate or strip of mica or equivalent I9. Immediately beneath the mica layer `is the plate member 2| forming the other plate of the condenser I5. The plate member 2| is divided into three distinct sections by appropriately. carbonizing separated areas 23 thereof. These carbonizedareas are designated in Fig. 6b as the shaded areas 23 whereas the non-carbonized areas 2| are unshaded. With this arrangement the different sectionsv 2| and 23 have different properties so far as the emission of secondary electrons is concerned and, therefore, during the sweep path of the reversalof the cathode ray covers the various sections of the tube in the directions indicated by the arrows adjacent Fig. 6b different intensity electrostatic charges produced upon the vvarious condenser elements. may be utilized for transmission. Y

Having 'described my invention, what I claim is:

'1. The method of communicating intelligence which comprises electrostatically storing a series of electrical energy representations of the intelligence to be communicated during a.v

relatively long time period and scanning the stored electrical energy charges in inverse order to that of their production subsequent to the period of storing and during a relatively short period of time for transmission, the periods of storing and transmitting being of the order of at least six to one.

2. 'I'he method claimed in the preceding claim which includes, in addition, the step of repeating the storing and transmission periods at a rate substantially equal to the rate ,of scanning each elemental strip of a subject for image transmission to reproduce the entire image at a repetition frequency at least equal to the frequency of persistence of vision.

3. The method of transmitting intelligence which comprises producing a series ofelectrostatic charges each of values proportional to produced intelligence signals and utilizing an electron beam to apply the electrostatic charges to a transmission channel in inverse order to that of their production andduring a time period substantially less than the time period of their production. 4

4.v The method of communicating intelligence which comprises storing a series of electrostatic representations of the intelligence to be communicated and subsequently controlling an electron beam by the electrostatic charges for transmitting' electrical ,energy modulated in accordance with variations in the stored energy to utilization points in inverse order to that of its production. 1

5. The method of communicating intelligence whichffcomprises producing a series of variable electro, tatic charges representative of a message to be communicated during arelative long time period, and controlling an electron beam by the electrotatic charges for transmitting signals modulated in proportion to variations in the stored electrical energy and in inverse order to that of the production of the stored energy sub- 6. e method claimedin the preceding claimV which includes, in addition, the step of sequentially repeating the production of the electrostatic harges in an order inverse to that of the 7. The method of receiving transmitted intelligence signals which comprises receiving during a relatively short time period a series of sound signals in inverse order to that of generation,

producing an electric non-visible electrostaticv record of the received intelligence signals in the order of reception, and controlling a cathode ray pencil to produce from the electrostatic sound record in inverse order to that of its production electrical signal energy, and then converting the produced electrical signal energy into an audible record of the sound originating at the point of transmission of the signals.

8. In a system for transmitting intelligence, the method which comprises producing from a series of sound signals a series of electrostatic charges proportional to differential portions of the entire series of generated sound signals, controlling a cathode ray by the'electrostaticr signals t apply the signals to a transmission channelin inverse order to that of production and during a time period of the order of one-ninth of the v period during which the electrostatic signals were produced, receiving the signals applied to the transmission channel, producing from the received signals a series of electrostatic records representative of the generated intelligence and in inverse order to that of its production, controlling a cathode ray beam so as to produce electrical signal energy representive ofv the received electrostatic records in inverse order to their production and at a rate of the order of nine times slower than that of their production and translating the produced energy into audible intelligence.

9. A system for receiving intelligence signals transmitted in reverse order to that of production which comprises means for receiving during a relatively short time period a series of signals representative of the intelligence signals developed Within a relatively long time interval but in inverse order to that of the generation of the intelligence signal, means for producing an electrostatic record of the received intelligence signals in the order of reception, and an electrical commutating means for producing from the electrostatic intelligence signals record in inverse order to that of its production and audible record of the intelligence signals originating at the point of transmission of the signals.

10. In a system for transmitting intelligence, a source of sound signals, means for producing from the series of intelligence signals a series of 4electrostatic charges of values proportional to the generated intelligence signals, a transmission channel, electrically operating distributing means for applying the electrostatic charges to the transmission channel to produce a series of signals representative of the electrostatic charges, said signals occurring in inverse order to that of production of the charges and active during a time period at least no greater than one-ninth of the period during which the electrostatic charges were produced, means for receiving the signals applied to the transmission channel, means for producing from the received vsignals a series of electrostatic signal records representative of the generated sound and in inverse order to that of its production, and electrically operative distributing means for causing the electrostatic record produced at the receiver' means to become audible in inverse order to its production'and at a rate at least nine times slower than that of its produc- 11. 'I'he method of transmitting and receiving' television image signals and related intelligence signals transmitted upon a single carrier frequency which comprises converting a series of light values from a subject into proportional electric current values, generating a carrier current, modulating the generated carrier bythe produced electric currents, simultaneously converting in-Y telligence signals accompanying the representation of which the image is desired into a series of proportional electrostatic charges, simultaneously interrupting the image signal modulation of the carrier and modulating'the generated carrier byv the produced electrostatic signals in inverse order to that of production during a time period of the order of one-ninth the period of initial modulation by the image signals, repeating the sequence of each independent and separate modulation of the generated carrier at a rate per second at least equal to the highest intelligence frequency to be transmitted, receiving the modulated signals, producing from the image modulated received signal a series of light intensities representative of the various light values of the subject at the point of transmission, interrupting the production oi light values at time periods corresponding to the time periods of interruption of the light modulation at the point of transmission, producing during the period of light modulation interruption a series of electrostatic charges representative of sound in the order corresponding to the order of transmission and of an intensity proportionate to the intelligence signals at the point of transmission, repeating the production .of varying light values from received signals at a rate corresponding to the repetition rate of transmission, and producing during each repetition of light values an audible indication of the intelligence signals related to the next previously produced series of light values and for a time period identical to that required to produce each seriesof light values.

12. The method of sequentially transmitting and simultaneously reproducing a plurality of independent intelligence signals which comthe produced electrostatic signals in inverse order to that of production during a time period which is a fractional part only of the period of modulating the generated carrier by the produced electic current values, simultaneously converting the second of the signals into a series of proportional electrostatic charges, simultaneously interrupting the carrier modulation by the first signals and modulating the generated carrier by all of the produced electrostatic signals in inverse order to that of production during a time period which is a fractional. part of the period of modulation by the rst series of signals, repeating the sequence of each independent and separate modulation vof the generated carrier at a rate per second at least equal to the repetition frequency rate of persistence of vision, receiving the modulated signals, producing from one of the modlated received signals a series of responses representative of the rst series of signals originating at the point of transmission, interrupting the trostatic charges representative of sound in the ordercorresponding to the order'of'transmission and of an intensity proportional to the intelligence signals at the point of transmission, repeating the production of varying light values fromv received signalsat a rate corresponding to the repetition rate of transmission, and producing during each repetition of light values an audible indication of the intelligence related to the next previously produced series of light values and for a time period identical to that required to produceeach series of light values.

13. A system for communicating intelligence between a plurality of points which comprises means for electrically storing energy representative of the intelligence to be communicatedl andcommutating means for subsequently transmitting the stored electrical energy to utiliza-r tion points in inverse order to that of its production and prior-to the production of subseseries of electrical waves representing, in inverse order, the original intelligence subsequent to the period ofrstcring and means for repeating the operations continuously during relatively short periods of time of the order of the period of persistence of vision, the alternate periods of energy storing and re-conversion being of thel order of nine to'one.

15. In a system for transmitting sound energy, means for producing a series of electrostatic charges of values individually proportionate to instantaneously produced sound signals and a cathode ray device for neutralizing each of the electrostatic charges produced and thereby applying a signal representative thereof to a transmission channel in inverse order to that of Atheir production and during a time period of the order of one-ninth that oi the period of their .production.

16. The system claimed in the preceding claim which includes, in addition, means for 'sequentially repeating the alternate production of the electrostatic charges and the neutralization thereof at a repetition rate per second of the order of 24.

17. A system for reconverting transmitted signais distributed during short time intervals into audible signals of apparent long duration which comprises means for receiving during continually interrupted relatively short time periods a series kof signals representative of intelligence eil'ects in inverse order to that of generation, means for producing from the received signals an electrical non-visible record of the received signals in the same order of reproduction as the order of reception, and cathode ray means for producing from the electrical record formed an audible record of an order of occurrence inverse to that in which the electrical record is produced so as to represent the intelligence originating at the point of transmission of the signals.

l 18. In a system for transmitting intelligence signals, means for producing from a series of andere sound originating at a source an electrostatic record oi.' intensity proportionate to the generated sound signals, a cathode ray for applying the f electrostatic signals to a transmission channel in inverse order to that of production and during a time period of the order of one-ninth the period during which the electrostatic charges were produced, means for receiving the signals applied to the transmission channel, means for producing from the received signals a series of electrostatic recordings representative of the initially produced sound and in inverse order to that oi' their production, and electrically operating' distributing means for converting thesecond-named electrostatic record into a series of audible signals in inverse order to the production ci the electrostatic charges and at a rate of the order of nine times slower than the rate of production.

I9. 'Ihe system claimed in the preceding claim which includes, in addition, means at the point charges, cathode ray means for causing the gen.

erated carrier to be modulated by all of -the produced yelectrostatic signals in inverse order to that of the actual time of production, means for sequentially controlling the modulation so that the carrier frequency modulation is controlled at any instant by one of the produced signals only and the duration of each control period corresponds to periods of picture scanning and interruption.

21. A receiving system for receiving signals transmitted in accordance with claim which -comprises means for receiving modulatedy plctorial and intelligence signals, means for producing from the pictorially modulated received signals a series of lighty intensities representative of the l'ght values at the point of transmission, means for interrupting the production ot light values of time periods corresponding -to the time periodsof interruption of the light modulation at the point of transmission, a cathode ray device for producing during the period of light modulation interruption a series of electrostatic charges representative of intelligence inthe order corresponding to the order oi transmission and of an intensity proportional to the intelligence signals at the point of transmission, means ior causing a repetition of the production of varying light values and of stored intelligence indications from received signals at a rate corresponding to the repetition rate of transmission,

VLADIMIR K. ZWORYKIN.

Images