US1754491A - System for transmission and reception of television - Google Patents

Description

April 15, 1930. G WALD 1,754,491

SYSTEM FOR TRANSMISSION AND RECEPTION OF TELEVISION Filed March 18, 1929 5 Sheets-Sheet l III W e/776x? April 15, 1930. WALD 1,754,491

SYSTEM FOR TRANSMISSION AND RECEPTION OF TELEVISION Filed March 18, 1929 5 Sheets-Sheet 2 O O a O O D D O O 0 O 0 O O G O c Q 0 O o O O O O O O 0 O O O O o o o o O O D O O O O O o O O O O 0 O O 0 O O o 0 o O o o a o o o o o o o o o O O 0 O 0 O O O O o O D o o o 0 o 6 a 0 o o o o o o o o o o o o o o o c a o o 0 o o c o o o o o o c c o o c o o 0 o 0 o o o o a u o o 0 o o o o O D U O O C O O G. WALD April 15, 1930.

SYSTEM FOR TRANSMISSION AND RECEPTION OF TELEVISION Filed March 18 1929 5 Sheets-Sheet 5 SYSTEM FOR TRANSMISSION AND RECEPTION OF TELEVISION Filed March 18, 1929 5 Sheets-Sheet 4 An a/7% 620/576 7127 April 15, 1930. G. WALD 1,754,491

SYSTEM FOR TRANSMISSION AND RECEPTION OF TELEVISION Filed March 18, 1929 5 Sheets-Sheet 5 Patented 5, 1930 PATENT OFFICE GEORGE WALD, 0F IBELLEVILLE, ILLINOIS SYSTEM FOR TRANSMISSION AND RECEPTION OF TELEVISION Applicationfiled March 18, 1929. Serial No. 347,792.

This invention relates to improvements in a new system for transmission and reception of television.

An object of the invention is to provide a 5 complete system of transmission and reception of images by television in which the images are produced on a screen from a stationary receiving element energized by a plurality of circuits under the control of transmitting apparatus, in which the images are reproduced by a plurality of illuminated points produced by coordinated circuits.

The specific advantages and improvements will be apparent from the following detailed description taken in connection with the accompanying drawings, in which Fig. 1 is a diagrammatic view of the receiving element, in combination with the immediate circuits by which it is energized.

Fig. 2 is a side elevation of the cathode ray tube constituting the receiving element.

Fig. 3 is a diagrammatic view of the anode electrode holder and separator plate forming a part of the receiving element.

Fig. at is a. sectional View taken on the line 4-4 of Fig. 3.

Fig. 5 is a diagrammatic view of the cathode electrode holder of the receiving element.

Fig. 6 is a section of the assembled receiving element taken on a line such as 6-6 of Fi 5 Fig. 7 is a sectional view of the same element taken on the line 77 of Fig. 5.

Fig. 8 is a diagrammatic view showing the are formed by the line of holes in the separator between the anode and cathode elements as they are mounted in their holder.

Fig. 9 is a diagrammatic view of an apparatus forming a part of the transmitting apparatus and operating as a variable condenser.

Fig. 10 is another diagrammatic view of the a same device shown in Fig. 9.

Fig. 11 is a diagrammatic view of another apparatus constituting a part of the transmitting apparatus and controlling one of the circuits and operating as a variable condenser.

Fig. 12 is a diagrammatic view of the television transmitting apparatus for transmitting the image and controlling the television clrcuit.

Fig. 13 is a front view of the lens disc.

Fig. 14 is a diagrammatic view of the transmission end of the television circuit.

Fig. 15 is a diagrammatic view of a modified receiving circuit.

Fig. 16 is a diagrammatic View of an amplifier oscillator circuit in which is interposed a rotating condenser in parallel with a second condenser, said circuit producing a successive varyingfrequency.

Fig. 17 is a diagrammatic view of a circuit, similar to that shown in Fig. 16, for transmitting an amplifying oscillating circuit on two frequencies in the form of a carrying wave current.

Fig. 18 is a diagrammatic view showing the current radio waves produced by the circuit illustrated in Fig. 16.

Fig. 19 is a diagrammatic view of the current radio waves produced by the circuit illustrated in Fig. 17, mounted on an ordinary radio-frequency Wave carrier.

Fig. 20 is a diagrammatic view showing the waves produced by the circuit shown in Fig. 17 in which the circuit shown in Fig. 14 is connected.

In the embodiment of the invention illustrated in the drawings the television transmission apparatus is shown as including a motor 1 that drives a shaft 2. The shaft 2 actuates the variable condenser 3 (Figs. 9 and 10), said shaft extending beyond the condenser and being provided with a pinion 4 that meshes with a gear 5 on the lens disc shaft 6. By interconnections, comprising a pinion 7 and a gear 8. the shaft 9 of the variable condenser 10 (Fig. 11) is operated, the shaft 6 rotating the lens disc 11. It is apparent, therefore, that the variable condensers 3 and 10 and the disc 11 are rotated in synchronism and at predetermined speeds as determined by the construction of the apparatus. The disc 11 is of known type, having in its face a non-concentric series of lens openin gs cooperatively arranged in the usual manner with the photo-electric cell 13 on one side of the disc and the object 14 on the opposite side of the disc, the photo-electric cell A manner.

controlling the television circuit in the usual The television circuit comprises the leads 15 and 16.

At this point it should be borne in mind that the present invention is not concerned with the development of the television signals and that the lens disc cooperating with the hoto-electric cell is shown merely as one linown method of producing the television si na-ls. The ir ention is equally applicable w mm the television signals are produced by a deflecting magnet, infra red rays, or a deflection by gas jet, or other known means.

The variable condenser 3 (Figs. 9 and 10) is of special construction designed to produce in the circuit controlled thereby a frequency of a wave band that continually varies from a predetermined minimum to a predetermined maximum. The circuit controlled by the variable condenser 3 energizes the cathode of the receiving element in the manner to be hereinafter more fully disclosed. It is important at this point to obtain an understanding of the construction of the condenser 3.

The condenser 3 has a rotary element comprising arms 17 and 18 of nonconducting material mounted to rotate on the shaft 2. At the extremity of each of the arms 17 and 18 are plates 19 and 20, respectively. lVithin a frame 21 of nonconductive material supported by a base 22 is a spaced series of electric1; .lly conductive plates 23 supported in the nonconductive ring 21. The plates '23 are electrically connected together and in series with a terminal 25. There are two commutator rings 26 and 27, the ring 26 having mounted therein a series of insulation segments 28, and the ring 27 having mounted therein a series of insulation segments 29. The ring 26 is connected to the plate 19, and the ring 27 is connected to the plate 20. The plates 19 and 20 are so disposed in respect of the plates 23 that when one or the other of the lates 19 or 20 is in conductive relation with the plate 23, the other one of said plates 20 or 19 will be disposed in the space between adjacent plates 23, and in nonconductive relation with the said plates 23.

The conductive connection between the respective plates 23 and plate 19 or 20 is completed by the commutator ring 26 or 27,

rushes 30 or 31 and terminals 25. The brushes are connected in )arallel to a terminal 32. As the arms 17 an 18 rotate the plates 19 and 20- are alternately cut in and out of the circuit, thereby alternating the frequency of the circuit from minimum to maximum in rogression but from maximum to minimum instantaneously. The capacity of the plates 19 and 20 is, therefore, alternately built up to maximum and, as the circuit shifts from one to the other of said plates, the capacity drops to minimum from w llCll it is again brought to maximum. This alternation occurs during sum of the insulating segments 28 and 29.

The terminals 25 and 32 are connected respectively with leads 33 and 34.

The variable condenser 10 (Fig. 11) is also of special construction and is designed to produce a predetermined frequency of a wave )and continuously varying from minimum to maximum, which circuit controls the anode units of the receiving element as will be hereinafter more fully described. The variable condenser 10 comprises a nonconductive ring frame supported on a base 36 and supports on its inner periphery a segmental electrically conductive plate 37.

The rotor of the device is mounted on the shaft 9 and comprises two semi-circular plates 38 and 39 supported by arms 40 rotating with the shaft 9, said arms 40 being of nonconductive material. The plate 38 is electrically connected with a semicircular commutator segment 41 and the plate 39 is connected with a semicircular commutator segment 42, the segments 41 and 42 being insulated from each other by insulation 43. A commutator brush 44, having a terminal 45', is arranged to contact the commutator segments 41 and 42 al-. ternately as the device rotates. Therefore, the condenser will increase from minimum to maximum condensance across the commutator brush 44 to a terminal 46, the latter being connected electrically to the plate 38.

It will be convenient at this point to consider the circuit shown in Fig. 16 of the drawlng and to point out the influence on the circuit of the variable condenser 3, the construction of which has been described above. The circuit shown in Fig. 16 is an amplifier oscillator circuit in which the variable condenser 3 is connected in parallel with a fixed condenser 46, the connections being such as to cause the oscillator tube 47 to produce a frequency in the transformer 48 varying between predetermined limits. For the purpose of description it may be assumed that the frequency variation is between 360 and 400 kilocycles. The wave produced may be taken to be represented by the curve 121 (Fig. 18). It should be noted by reference to Fig. 16 that there are fixed condensers 50 and 51 in the circuit that remain constant.

A brief reference to the general influence of the variable condenser 10 on the circuit shown in Fig. 17 of the drawings will, at this point. tend to a general understanding of the function in the system of the condenser 10. The condenser 101s connected in parallel with a fixed condenser 52. As the condenser 10 rotates the oscillating tube 53 produces a frequency in the transformer 54 which variation, 1

it may be assumed, is from 160 to 200 kilocycles.

With this general understanding of the transmission mechanism and its general relationship to the system, it is convenient to turn to a description of the receiving element. The details of the receiving element are illustrated in Figs. 2 to 8, inclusive, of the draw m s.

The receiving element comprises a tube 55 having a base section 56 to be connected into a socket. In one wall of the tube 55 the ele ments comprising the receiving frame are fitted.

The receiving frame is made up of an anode holder 57, which comprises a rectangular plate of insulating material having a series of channels 58 arranged transversely of the plate and parallel with each'other. Lying Within the channels 58 areconductor elements 59 supported by the plate at one end and having independent terminals 60 at the opposite end. Each of the conductors 59 are arranged to be independently connected at their respective terminals 60 with a separate lead from the anode receiving element in the circuit. A separator late 61 is mounted over that face of the ano e holder 57 in which the anode conductors are mounted; The plate 61 has a plurality of openings 62 therein, said openings being arranged in transverse series and equally spaced apart. The series of spaced openings are arranged to overlie the separate anode conductors in the manner shown diagrammatically in Fig. 3 of the drawing.

' Each transverse series of openings 62 are disposed on a long arc; The relationship of each series of openings with its respective anode unit is illustrated in diagrammatic form in Fig. 8 of the drawing. The purpose of this arrangement is to coordinate the reception of the television signals With the sending disc of the television transmission apparatus, as will be more fully described hereafter.

Fitted over the separator plate 61 is a cathode holder 63, said cathode holder comprising a plate of translucent material, the

outer face of which may be ground to form a receiving screen; or a receiving screen, as a separate unit, may be placed over the outer face of said cathode holder. The cathode conductors 64 are mounted on the inner face of the cathode holder 63 in a spaced series of channels 65, said cathode elements 64 being connected through the holder at one end and to independent terminals 66 at the opposite end. The anode and cathode holders with the separator plate, are assembled in the relationship shown in Fig. 6 and constitute together the receiving frame which is set in one wall of the tube 55 and sealed.

It will be understood that the tube 55 is gas-filled and, by the circuits and controls hereinafter more fully described, the intersections of the anode and cathode elements produce in the gas-filled tube a series of bright points on the cathode that evolve a series of rays that are projected in predetermined sequence onto the receiving "screen to produce the image. It will be understood that the image by a s stem of lenses may, if

desired, be projecte from the receiving frame to a screen, and that, through known systems of ligf litgcontrol, the image fromthe receiving frame may be reproduced on the screen in colors. I

From the above description of the receiving element it will be understood that the theory upon which it operates is that the anode and cathode elements are each independently energized from a separate power circuit. The anode and cathode units have intersecting points that register with the openings 62 in the separator plate. Each intersection produces a separate ray when the potential across the intersection reaches a predetermined point and causes the cathode elements to glow at such intersecting points. The central of the glow pointsis effected by a combination of circuits that impress the predetermined potential at the intersections selectively, the final degree of potential being impressed in response to the television signals. Thus a series of spaced points of light are thrown on the receiving panel in rapid sequence and, because of the known persistence of vision, the image is reproduced in response to the television signal sent out from the sending station.

No attempt has been made to illustrate in the drawings the full number of electrodes. The drawings, therefore, in that respect should be considered diagrammatic. For the purpose of the explanation of the operation it may be assumed that there are eighty vertical and eighty horizontal electrodes, each 1/80th of an inch in thickness and each separated from the other by the separator plate of non-infiammable and insulating material. As an electric potential is applied to an anode element and at the same time and While the respectiveranode elements remain energized, all of the cathode elements are energized in succession, a series of transverse points along the line of the anode element will glow successively tracing a line of the series of points, assuming a uniform strength of the televis on signal. When, however, there is a variation in the potential impressed on the cathode elements by the'television power circuit there will be a corresponding dim or dark spot at the intersection where the insufficient potential occurs.

Assuming a frame approximately 2 inches by 2 inches containing eighty anode and eighty cathode elements, the total number of points of intersection within the area of the cxactitude to the image scanned by the television sending station.

In Fig. 1 of the drawing there is illustrated,-

.of receiving devices.

For the anodes there is provided a primary coil 67 adapted to be tuned into a radio receiver and amplifier circuit, so that the secondaries (58 receive the radio signals at a variation from, for example, 160 to 200 kilocycl es. Assuming that there are 80 secondary coils, each independently connected with one ot the anodes, then the variation between ad acent coils would be one-half kilocycle.

It is apparent, therefore, that, durlng the period in which the broadcasting circuit that effects the anode receiving circuit broadcasts one complete change from 160 to 200 kilocycles, the plurality of secondaries connected with the independent anode conductors tune in for reception successively. Since, however, there is a constant variation in frequency in the circuit controlled by the variable condenser 10, only a single secondary m the receiving circuit will tune in to the maximumat the same time. It will be understood that this excitation serially of the anode units occurs during the period in which all of the cathode units receive impulses through the receiving circuit later to be described.

By reference to Fig. 1 it will be noted that one side of each secondary coil 68 connects through a lead 69 with the respective anode terminal 60. The opposite end of each of the coils 68 is connected into a lead 7 0 energized by a source of electrical power 71 through a fixed resistance 7 2 to prevent an overcharge on the anode, and the lead 7 0 terminates at the condenser 73, the opposite side of which is connected by a lead 7 4 to an amlifier tube filament circuit 75. The amplier tube filament actsas a by-pass to prevent interference between the receiving circuit for the anode units and. the receiving circuit for the cathode units.

In the cathode receiving circuit there is a primary coil 7 6 which is adapted to be tuned into a radio and amplifier circuit so that the secondaries 77 receive the radio signals at a variation from, for example, 360 to 400 kilocycles.

I The secondary coils 77 of the cathode receiving'circuit are independently connected through leads 78 with respective ones of the cathode conductors, said leads being connected to the terminals 66 of said cathode elements. The opposite ends of the secondary coils 77 are connected with a lead 78 having therein a secondary 7 9 of a television circuit, the opposite end of which is connected by a lead 80 into a power circuit energized at the source of electric energy at 71 and with the amplifying tube filament circuit 75 through a condenser 81; a variable resistance 82 being interposed between the source of power and tl a lead 80. The variable resistance 82 permits regulation of the amount of current delivered to the independent cathode elements and thereby regulates the degree of glow of the cathodes in the tube 55. Since the input on the primary 7 6 is from the circuit controlled by the variable condenser 3 the frequency of theinput will vary from 360 to 400 kilocycles. Therefore, each secondary coil 77 will tune into the circuit to the maximum on a half kilocycle interval and each cathode will be energized from the cathode receiving circuit in sequence during the period that a single anode is excited at maximum.

By adjustment of the variable resistance 82 the potential impressed on a selected intersection of an anode and cathode element, receiving maximum excitation from the anode and cathode receiving circuits, can be so controlled that the potential would be insutficient to cause a bright glow at the intersection. The additional voltage to cause a glow point at the intersection of the anode and cathode elements, receiving maximum impress of potential from their respective circuits, is supplied through the television input.

The primary 83 of the television input circuit receives impulses from the television transmission circuit. Therefore, the additional potential impress on the cathode elements is sufiicient to cause incandescence of the cathode unit at the point of intersection with an anode element that receives the maximum potential from the respective anode and cathode circuits. The television circuit, therefore, acts as a booster circuit and is directly responsive to the television signals. When the photo-electric cell 13 receives light from a bright surface the coil 79 will receive the maximum impulse and the particular intersection of the anode and cathode under maximum potential will, therefore, vary in brightness directly responsive to light shades reflected from the object broadcast from the television sending circuit.

In order to give a concrete example of the operation described it may be assumed that any one intersecting point between anode and cathode elements requires 100 volts to produce a ray of maximum glow. Of this voltage a selected coil 68 supplies a 3 volt potential, a corresponding coil 77 supplies a 2 volt potential and the coil 7 9 supplies a 2 volt potential when a dark surface influences the photo-electric cell. Then it may be assumed that the variable resistance 82 may be adjusted to deliver 88 volts across the condensers 81 and 73. The sum of the voltage thus delivered is 95 volts at the selected point of intersection across the anode and cathode units. If it be assumed further that a bright object influences the photo-electric cell, the coil 79 will deliver 7 volts or an increase in voltage to 100 volts across the selected point of intersection. At 95 volts the selected point of intersection may be assumed to produce a dim point of brightness of the cathode at the intersection, which is brought to a point of maximum brightness by the additional 5 volts supplied through the influence of the television circuits.

It should be remembered from a description of the television transmission apparatus that, because of the gear relationship between the variable condenser 10 and the scanning disc, when the first opening in the disc is on the image the capacity of the anode sending circuit is at minimum and that it increases progressively to'maximum until the last hole in the disc leaves the image. It is apparent, therefore, that while the scanning disc makes one revolution the secondary coils 68 have successively received maximum impulse and, therefore, the anodes 59 have re ceived the maximum potential successively.

The maximum charge, therefore, remains on each anode for an interval of 1/80 of a frame. Since there are a corresponding number of holes in the scanning discto the number of anode units, assumed to be 80, each anode remains charged for aperiod during which each of the holes in the scanning disc moves across the image.

The gear ratio between the condenser 3 and the scanning disc is such that when the scanning disc begins the frame the potential on the circuit controlled by the condenser 3 is at its minimum capacity and increases to maximum capacity when the initial opening in the scanning disc leaves the image. This variation in potential occurs for each of the openings in the disc. Therefore, each coil 7 7 receives maximum impulses while each opening in the scanning disc traces one line of the image, which is the distance betweentwo adjacent holes 12 in the scanning disc; the anode excitation remaining at maximum on one anode through this period.

It follows, therefore, that as the scanning disc traces the image from right to left and line by line from top to bottom, a maximum voltage point is traced on the receiving frame from right to left and from top to bottom. The sending apparatus is operated at aspeed to reproduce the image on the receiving screen ten frames per second, which is sulficient to reproduce an image observable by reason of the known characteristic of the per sistence of vision.

It should be understood that the input to the anode circuit and to the cathode circuit, as well as the television circuit, may be from separate sending stations or that the waves may be transmitted in multiplex from one transmitting station. Several sending transmission circuits have been illustrated in the drawings.

Fig. 16 will be recognized to be a known form of oscillator amplified circuit, iii-which the frequency, instead of bein adjustable manually, is automatically varie by the condenser 3.

For the sake of completeness it should be understood that the circuit illustrated in Fig. 16 comprises a grid circuit 85 having a source of electrical energy 86 and a fixed resistance 87, said circuit being connected with the grid 88 of an amplifying tube 89. The plate circuit 90 for the plate 91 of the tube has connected thereinto a source of electric energy 92 and an audio frequency choke coil 93. y

The circuit for the plate 94 of the oscillating tube 47 is connected into the circuit 95 and is energized from the same sources of electric energy and has interposed therein a radio frequency choke coil 95. The grid circuit for the tube 47 is completed through the circuit 96 which is the circuit described heretofore and in which is located the variable condenser 3. A separate source of electrical energy 97 is connected with the grid 98 of the tube 47, a grid leak 99 being interposed between the grid and the source of electric energy. The result of the circuit is the output onto the secondary of the transformer 48, said secondary being connected into a standard radio transmission carrier circuit that energizes, in the manner heretofore described, the anode receiving circuit.

The circuit for transmitting the higher frequency wave that influences the cathode receivlng circuit is similar in all respects to the circuit described in connection with Fig. 16 of the drawing and has not, therefore, been separately illustrated, but constitutes that circuit shown in Fig. 17 on the right of the line 17-17, certain "of the elements being designated by appropriate numbers in order to distinguish the circuit, otherwise the elements of the circuit have been indicated by reference numerals common to the circuit described.

Fig. 17 may be read as a diagram illustrating the transmission from a single sending station in which the lower frequency band is impressed upon the higher frequency band and together transmitted from the sending station.

The television transmission circuit is illustrated separately in Fig. 14 in which the television signals from the photo-electric cell are passed through an amplifier circuit 99 to a transformer 100, the secondary of the transformer being connected into the sending circuit. The television circuit may also be superimposed upon the circuit shown in Fig. 17 by substituting for the fixed resistance 87 the secondary of the transformer 100.

When it is considered that'the difference in frequency between the circuit controlled by the variable condenser 3 and the circuit controlled by the variable condenser 10 and the circuit controlled by the photo-electric cell is sufiicient to prevent interference at the receiving circuits, it is obvious that multiplex transmission on a carrier wave is practical, although it should be understood that I contem late both the use of separate sending stations as well as multiplex transmission.

With multiplex transmission the receiving circuits may be combined. as illustrated in Fig. 15 of the drawing, in which the combined waves are received on a radio frequency receiving circuit 101, passed through an intermediate frequency circuit 102 and passed directly to primaries 103 and 104. Primary 103 influences the cathode circuit represented by a secondary 105 having taps 106 leading to separate cathode elements, the secondary being connected across a condenser 107 and with the nower circuit 108 corresponding with the power circuit as described in connection with Fig. 1 of the drawing, and in which the elements are now given the same reference numerals already applied in connection with the description of Fig. 1.

The primary 104 influences the secondary 109 of the anode receiving circuit, said secondary having a series of taps 110 leading to the separate anode element and said coils are connected across a condenser 111 and are energized from the power circuit likewise similar in all respects to the description of Fig. 1 and in which corresponding elements have been given the same reference numerals.

It should be noted that the primaries 103 -and 104: each have a by-pass condenser connected across their respective terminals, and the primary 104 has an impedence connected in series with it to prevent higher frequency current of 103 from passing through it.

It will be noted that the primaries 103 and 104 are in series and are likewise in series with an audio receiver 115 connected through an audi frequenc circuit 116. It should be noted that the circuit for multiplex transmission, in which the television transmission is included, is a modulated circuit for the audio frequency at 116.

It will clarify an understanding of the theory of the multiplex transmission to first consider the characteristic of the separate waves produced by the separate sending stations and then consider the modifications that result from the multiplex transmission.

When the circuit illustrated at the right of the line 1717 in Fig. 17 is considered as a single sending circuit the wave produced is that indicated by the curve 120 Fig. 19. The characteristic of this wave is as follows:

Its frequency changes uniformly and continuously from 160 to 200 kilocycles; its wave length varies approximately from $3 to fatmeters; it changes from 196 to i g instantaneously; its amplitude remains the same for all wave lengths.

The circuit shown in Fig. 16, which is duplicated to the left of line 17--17 of Fig. 17, will roduce a wave represented by the curve 121 ig. 18. Its characteristic is as follows:

Its frequency varies uniformly and continuously from 360 to 400 kiloc cles; its wave length varies approximately rom -3 to W meters; it changes from -gw to instantaneously; its amplitude remains the same independently of the wave length.

When these two circuits are combined in accordance with the diagram in Fig. 17 and the transformer 48 is connected with a radio transmission station the circuit produces a carrier wave current represented by the curve 122 Fig. 19. The amplitude of the carrier wave 122 is variable since the wave 120 acts as a modulating wave, the amplitude of the wave 120, however, remaining the same. WVhen the circuit illustrated in Fig. 17 feeds into a standard radio frequency amplifying circuit of shorter Wave length, the wave 122 acts as a modulating wave for the radio frequency wave 123.

Further, if it be assumed that, in the television circuit shown in the diagram 17, the secondary of the transformer 100 be substituted for the resistance 87, then impulse in the photo-electric cell 13 will increase or decrease the amplitude of the wave given out by the circuit controlled by the variable condenser 10 (Fig. 7), and the wave 120 will then also become a carrier wave for the photoelectric current, said photo-electric current wave acting as a modulator. Now let it be assumed that a dark object is moving into registration with the photo-electric cell 13 that reduces any light reflection. The signals in the television circuit reduce correspondingly. The resultof this reduction in current in the photo-electric cells is illustrated diagrammatically by the curve 120 (Fig. 20) which gradually reduces in amplitude. When a refiection from a bright object is in registration with the photo-electric cell 13 the amplitude will increase in the reverse direction and the transformer coil of the anode receiving circuit receives and reproduces the waves corresponding to curve 120 illustrated in Fig. 20, while the transformer connected with the cathode receiving circuit receives and reproduces the wave represented by the curve 122" (Fig. 20). From this it will be seen that the brightness of the moving spot describing the image on the receiving member is proportional to the voltage across each anode and each cathode which in turn is proportional to the amplitude of the respective curves 120 and 122, which waves are in turn proportional to the strength of the signals given out b the photo-electric cell. It follows, there ore, that the image received is at all tirlries proportional to theimage sent by the ce 13.

When the several circuits are sent in multiplex, as just described, the separate television input circuit, shown in Fig. 1 of the drawing and comprising the primary and secondary 83 and 79, is not required but the composite waves are directly received on the anode and cathode transformers in the manner just described.

From the foregoing description it will, therefore, be understood that the selected excitation of the anode and cathode elements in such a manner as to produce an image is effected through the simultaneous transmission of the several circuits effecting the potential across the anodes and cathodes; thatthe maximum potential at selected intersections is controlled directly by the photo electric cell and is, therefore, influenced directly from the television sending circuit. It is also clear that the transmission of the several circuits may be from independent sending stations operating on separated frequencies, or that the circuits of the several frequencies may be 1mpressed on a carrier wave and selectively received by the receiving circuits.

I am aware that the embodiment of the in- Vention may be greatly modified within the equivalent limits and I do not restr ct myself, therefore, to the exact apparatus, combination of circuits, and interrelationship of circuits except as defined by the following claims.

WVhat I claim and desire to secure by Letters Patent is:

1. A system of television comprising a receiving element including a plurality of 1ntersecting anode and cathode elements enclosed in a gas-filled tube and adapted to produce, at selected intersecting polnts of varying brightness, circuits for receivlng impulses of separated frequencies connected respectively with the anode and cathode elements to impress thereon varying potentials, and a television input circuit whereby additional potential is impressed at selected intersections of the anode and cathode elements responsive to a television controlled sending circuit.

2. A system of television comprising a receiving element composed of intersecting anode and cathode elements in a gas-filled tube, separate receiving circuits for the anode and cathode elements for impression thereon varying potentials, separate sending circuits adapted to broadcast wave bands of separate frequencies, tuning devices for tuning the anode and cathode receiving circuits, respectively, with said sending circuits, and a television sending circuit adapted to constitute a booster circuit for increasing the potential across selected intersections of the anode and cathode elements responsive to television signals.

3. A system of television comprising a receiving element having intersecting anode and cathode units in a gas-filled tube and adapted to be energized in sequence and in timed relationship, a receiving circuit for each of said anode and cathode elements, sending circuits influencing separately said receiving circuits, a television sending circuit adapted to produce television signals responsive to light and shade, and means in rated in-degree of frequencies, a television,

sending circuit coordinating with the currents produced by said apparatus, and tuned receiving circuits for exciting the anode and cathode elements successively and in timed relationship to produce predetermined potentials at selected intersections of the anode and cathode elements responsive to television signals.

5. A system of television comprising a receiving element including a plurality of intersecting anode and cathode elements contained in a sealed tube and having a receiving frame upon which rays from glow points at the intersection of the anode and cathode elements are reproduced, sending circuits for separately energizing the anode and cathode elements in sequence and in timed relationship so that all of the cathode elements are energized during the period that each anode element is energized, and tuned receiving circuits for said anode and cathode elements for translating the impulses received from said sending circuits.

6. In a system of televison, the combination of an apparatus for scanning an object, and a transmission circuit controlled by the reflection from the object, with a pair of circuits adapted to transmit on varying wave band frequencies, a receiving element having a plurality of elements in opposite electrical relationship adapted to produce glow points responsive to potenitial thereon,and receiving circuits coordinated with said sendingcircuits to produce in said elements potentials across selected points in response to the sending circuits.

7. In a system of television the combination of an apparatus for scanning an object and a transmission circuit controlled by the reflection from the object, with a pair of circuits adapted to transmit on varying Wave band frequencies, a receiving element having a plurality of elements in opposite electrical relationship adapted to produce glow points responsive to otential thereon, receiving circuits to pro uce in said, elements potentials across selected points in response to the sending circuits, and tuning means in said receiving circuits to coordinate the receiving circuits with the sending circuits.

8. In a system of television the combination of an apparatus for scanning an object and a transmission circuit, a light responsive element in said circuit for varying the frequency thereof, a pair of independent circuits the bands of which are separated, adapted to transmit varying frequencies, a receiving element having electrodes in opposite electrical relationship adapted to produce glow points responsive to potential thereon, and receiving circuits coordinated with said sending circuits to produce in said elements potentials across selected points responsive to frequencies on said transmission circuits.

9. In a system of television the combination of an apparatus for scanning an object and a transmission circuit controlled by the reflection of light from an object, with a plurality of separate transmission circuits, devices in said separate transmission circuits operable coordinating with the apparatus for scanning the object for varying the frequencies of said circuits, a receiving element for reproducing an image from glow points evolved by potention impressed upon said elements, and receiving circuits for translating impulses from the transmission circuits to influence the potential on said elements.

10. In a system of television, the combination of a sending circuit responsive in frequency to shades of light vibration, a plurality of sending circuits, means for varying the frequencies of said last named sending circuits, a receiving element adapted to produce glow points responsive to potential thereon, and receiving circuits connected with said elements for translating the impulses from said sending circuits.

GEORGE WALD.

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