US2595617A - Color television by multielement glow lamp screen - Google Patents

Description

May 6, 1952 P. M. G. TOULON COLOR TELEVISION BY MULTIELEMENT GLOW LAMP SCREEN 6 Sheets-Sheet 1 Filed Nov. 18, 1948 May 6, 1952 P. M. G. TOULON 2,595,617

COLOR TELEVISION BY MULTIELEMENT GLOW LAMP SCREEN Filed Nov. 18, 194B 6 Sheets-Sheetl 2 May 46, 1952 P. M. G. TOULON COLOR TELEVISION BY MULTIELEMENT GLOW LAMP SCREEN Filed Nov. 18, 1948 6 Sheets-Sheet 3 A TToR/VS VS May 6, 1952 P. M. G. TOULON COLOR TELEVISION BY MULTIELEMENT GLOW LAMP SCREEN Filed Nov. 18, 1948 6 Sheets-Sheet 4 May 6, 1952 P. M. G. TOULON COLOR TELEVISION BY MULTIELEMENT GLOW LAMP SCREEN 6 Sheets-Sheet 5 Filed NOV. 18, 1948 m I l- -t l. :a I -.----.:f-.---

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May 6, 1952 P. M. G. TOULON 2,595,617

COLOR TELEVISION BY MULTIELEMENT GLOW LAMP SCREEN Filed Nov. 1s, 1948 e sheets-sheet e "a A from/5 ys Patented May 6, T952 COLOR TELEVISION BY MULTIELEMENT GLOW LAMP SCREEN Pierre Marie Grabriel Toulon, Neully-sur-Seine,

France, assignor to Products & Licensing Corporation, New York, N. Y., a corporation of Delaware Application November 18, 1948, Serial No. 60,668 In France November 29, 1947 20 Claims. 1

The invention relates to the screens made out of a very large number of elements brought together, each one of them receiving the electric impulses by which pictures are transmitted at a distance, and converting them into visual impulses whicli are to be observed on a plane wall or partition constituted by the said elements, on which the transmitted picture appears. The invention mostly .concernsmthe screens intended for the high definition television, in which use must be made of a Very large number of elements.

It has not, till now, been possible to build such screens, either because the elements of transformation which were thought of did impose prohibitive dimensions and costs, or because the production of such elements, which must fulll very severe working conditions, had not met with satisfactory practical solutions.

rifhe new type of screen, which is the object -of my invention, makes use of elements `which permit, on the one hand to receive the high definition pictures on relatively small and relatively plane surfaces, Wherefrom results .the possibility to use it even at home; the said elements being, on the other hand, .apt to be practically built by the means presently disposed of in electrical industry.

According to the invention, the elements of the screen, that will be designated in the following description as electro-optical elements, are constituted by electrical discharge columns juxtaposed in a rarefied ionized atmosphere (called positive columns). 'Those columns are started up in synchronism with, the transmission of the electric video picture signals and are modulated by the said signals. 'They act upon the part of the element forming the surface on which appears the picture. The vsaid action can` preferably be direct, and in that case the positive columns will excite a fraction, corresponding thereto in the space, of a layer of fluorescent salts or of any other substance apt to become luminous by the effect of the `said column.

The surface on which the picture will be observed Will then offer a smooth aspect. That action could also be indirect and have for effect the variation of the potential vapplied 4permanently to the part of the element belonging to the surface ci observation divided up (or nfrag-mentated) and which, through the effect of that variation, changes its optical characteristics and thus gives birth to a visual impulse.

The production of such a screen raises the questions (or problems) which are unseparable from thestarting up of those columns, of their supply, of their modulation, of their separation so as to avoid any interaction, and of the mechanical production of the tight enclosure of the apparatus wherein a low pressure must exist. The invention has for object method and means permitting to solve industrially the said problems.

According to the invention, all the columns are supplied by a common compartment in which, by means of an appropriate local discharge, is created a reserve of ionized gas or vapor forming a kind of plasma and which will be hereafter designated by that expression. That gaseous reserve will fill the duty of Va common cathode. The discharge Will be preferably created by a thermo-ionic cathode associated with several anodes distributed judiciously in that compartment. Some means are provided for securing a uniform distribution of plasma in that space.

According to the invention, all the electrooptical elements are connected in parallel on that compartment; they will be periodically locked and unlocked by the action of one or several individual grids permitting to the plasma to penetrate Within the element and to form a kind of an individual cathode.

According to the invention, the starting and the maintaining of the positive columns' will be controlled by another individual grid receiving the picture signal and by an individual anode receiving unidirectional voltage impulses varying progressively. The conjugated actions of .those two modulating devices have for effect to control the duration of the ionic discharge (which, generally, once it is started, does not admit of being modulated by the grid potential in function of the intensity of the signal), and to thus produce a luminous'impulse the duration .of which will be proportional tothe intensity.

The visual impulse will be, under those conditions, function of the latter and the picture will be faithfully reproduced.

According to the invention, and in order to simplify the Wiring land' to reduce the number of the current conductors passing through the tight sealed envelop of the apparatus, the screen elements will be distributed into groups, the modulation voltages will be unlocked and applied simultaneously to all'` the elements of the group; this will have for effect the operation, in the same time of all the columns of a group.

According to the invention, and for avoiding the mutual action between those columns, they will be insulated electrostatically by means of grids located between them and carried to suitable potentials; those grids will thus serve to exactly localize each one of the columns.

According to the invention, the sealed enclosure, of a preferably flat shape, of the screen, will be protected against the atmospheric pressure, by means of partitions disposed in the cathodic compartment and by giving a mechanically resistance shape, namely an undulated one, to the support of the surface on which the picture appears. The use of a fluorescent surface and the possibility, by the choice of the coating substance, to alter the tint, makes th'at screen more particularly applicable to the color television, and the invention has for object a picture receiver in which the screen is divided up into uorescent strips offering various colours, which will be excited by columns distributed to that effect.

All the other characteristics of the invention which bear on the screen itself and on the diagrams of its scanning connections, will be exposed in the following description.

For a better understanding of the invention, reference will be made to the appended drawings, given by way of example and not limitatively:

The Figure l shows a perspective View, in a very schematic and simplified way, of the `outline aspect of the screen.

The Figure 2 represents, in a perspective view, a mode of industrial production of the screen comprising a fluorescent surface.

The Figure 3 shows the details of construction of the feeding anode belonging to the plasma compartment.

The Figure 4 an enlarged sectional view of the screen along the plane a. of the Figure 2.

The Figure 5 shows the complete scanning and modulating diagram of the electro-optical elements of a screen for the colour television comprising a very much reduced number of elements.

The Figure 6 reproduces some graphic data enabling the reader to better understand the working operation of the said diagram.

The Figure 7 represents a variant of the scanning diagram permitting to reduce the wiring, and nally,

The Figure 8 shows a variant of the screen, based on the indirect action of the positive column on the part of the element converting the electric signals into visual impulses.

In the Figure 1 has been shown, very schematically and in a very simplified manner, the screen which is the object of the invention. It is composed of a compartment 5, in which is produced the plasma supplying the positive columns; of a compartment 2, in which those columns are produced. which encloses the unlocking and modulating grids, and it will be designated as distribution compartment; and the compartment 6, whichv ends in a plane surface S on which the picture is observed, and it will be designated as the transformation compartment. All those compartments form parts of a sealed enclosure filled with a gas or a vapor at a low pressure (namely Hg vapor, hydrogen or helium).

The height of the screen has been exaggerated and, in practice, it affects a much flatter shape.

By closing the circuit of the battery B, an electro-ionic discharge is established between the emissive (direcly heated) cathode l and an anode 3 protected by a resistance 4. In reality the said compartment contains several other anodes, such as 3 and resistances 4 which can cooperate with a single cathode.

That discharge creates a ionized atmosphere, called plasma, lling the whole of that compartment, which thus serves as a supply tank. The distribution compartment 2, assumed to be filled with an insulating substance, offers a series of openings OI-O2, located face to face and communicating together through a channel C I, shown in dotted lines.

In the figure are represented the channels or tubes, CI, C2, C3, forming a first line, and the channels C4, C5, and C6, forming a second line of the picture. Two grids, Gl and G2, are disposed in each one of the channels. The grid Gl is normally polarized negatively, and locks its channel. By annulling the said polarization, it is done in such a way that the said grid unlocks the channel, and the plasma penetrates into the latter and creates within a virtual cathode. The modulation grid G2 receives the picture signal, and the anode A, disposed in the transformation compartment 6, receives a positive tension which varies progressively. The combined action of those two tensions, as explained later in connection with the Figures 5 and 6, has for effect that a discharge column, called positive columns, established itself between Ol and O2, and by crossing through the channel, penetrates into the compartment 6 wherein` it reaches the wall 6.

The latter is coated with a layer of a iluorescent substance which, excited by the column (this latter communicating to it a part of its energy), produces at the place of impact a luminous spot. That positive column is maintained during a determined time, by the intensity of the received signal, as will ,be explained further on, and consequently the degree of the brightness of the fluorescent point will appear, to the human eye, as a function of that signal. By blocking or locking up, by means of the grid Gl, the column OI O2, and by unlocking by means of an equivalent grid Gl a neighbouring element, there is created, in turn, a virtual cathode. By acting upon its equivalent modulation grid GZ and on its anode A there is produced a positive column, the duration of which will be proportional to the signal of the corresponding point of the line, which will be reproduced by the spot S, and so on For localizing and insulating the various columns, the anodic compartment will be provided with electrostatic screens (shown in dotted lines), carried to a negative tension with regard to the cathode, with this result that to each electric picture impulse will correspond on the screen a well deiined spot having very reduced dimensions.

The Figure 2 shows, in perspective view, the essential pieces which compose the new screen. For the clarity of the figure, it has been assumed that the pieces were not yet assembled and they have been placed the ones above the others. The screen essentially comprises (Fig. 2) two glass flanges I6 and l1 separated by a small interval in which all the assembly mounting is installed. Along the rear face I6, the plasma tank, or cathodic supply compartment, is composed of a metallic honeycomb frame comprising horizontal and longitudinal beams 6, 6', 6, and crossbeams 1, l', 1".

The dimensions of each cell of the honeycomb measure, for instance, 2 cm. by 4 cm. and 2 cm. in height. The crossbeams of each largely cut out toward thetop in o rder to permit to the ionizalself may be used as a common cathode.

tion to be propagated step by step from one cell to the following one.

The ionization (plasma) is permanently produced thanks to the presence in each cell of an anode carried to a positive tension. Those anodes themselves are made out by means of special conducting wires S, 8', 8, suitably coated, in an alternate manner, with insulating and semi-conducting layers, as will be explained in connection with the Figure 3. The anodic wires 8 are maintained in the hollowing of the crossbeams by means of insulating pieces 9.

In the Figure 3 are shown, in perspective, above the honeycomb, 3 anodic wires with their support. There are also represented, in dots and dashes, the wire 8 and its supports in the position of work, assuming them in the first row. The plasma tank or cathodic compartment (3 in the Figure 1) is separated from the front part (or transformation compartment 6 of the Fig. 1) by a partition with many rows of small openings in it, which represent the distribution compartment (compartment 2 of the Figure 2). On the Figure 2 that partition is assumed not to be yet mounted and it has been shown in perspective above the honeycomb 6, l. That partition is in fact made out of many several insulating layers Ii), EI, I2, I3, I4, I5 between which are installed some electrodes (blocking grids and modulating grids), as well as the wiring use for feeding them. The flank I5, etc. which are used for securing mechanical rigidity to the tube, pass through those insulating layers IB I5, by passing through the slots 2I and preventing the front and rear glass I'I and I6 to be crushed down the one against the other by the effect of the atmospheric pressure.

Above those insulating layers is installed an accordion I8. For a better understanding of the drawing there has been represented, also in perspective, on the Figure 2, the said accordion' before assembly. In the small lcells of that accordion are installed anodes I9, which receive a saw-tooth tension by means of a generator 23. They are obtained by depositing Vin succession on the accordion insulating layers and semiconducting layers according to the technique 'which will be described in connection with the Figure 3. In certain cases also, for simplifying and under certain reserves, the accordion it- The front shutting glass plate I1 is coated on the inside with the fluorescent substance 33.

In the Figure 3 has been shown the new process of production of the anodic wire 8 according to the invention: on a conducting wire 24 are deposited in succession insulating layers of short length 25, 25.` 2'5"', etc. The parts left uncovered, 28, serve as starting points for resistances made out of semi-conducting deposits 26, 26', etc. (aquadag of metallisaton under vacuum). The end of each one of those resistances 23, 23', constitutes an anode. The dimensions of the said anode are localized by means of new insulating deposits 21, 2l', 21". A complex wire may thus be made out in an entirely automatic way, and it is suicient to x it on the supports 9 for obtaining the anodes 3 of the Figure 1, installed in the ionized chamber (5 of the Figure l).

The Figure 4 represents, in sectional view at an enlarged scale, one half of one of the cells of the Figure 2: on the left can be seen, in section, one of the longitudinal beams 6 which pre- ,vent the two glass flanges, the front one I1 and 6 the rear one I8, to be crushed one against the other under the effect of the atmospheric pressure, and pieces one can also see, in front view in 1, one of the cross; one can easily see the insulating support 9 which keeps in place the anodic conductor 8 (shown in detail in the Figure 3). One can also see, in sectional view, the insulating sheets I0, II, I2, I3, I4, I5, between which are mounted the control electrodes. There has been represented in 29 a vertical row of modulation grids; there has been shown, in 3i] and 3I, some rows of unlocking grids. Those grids permit the static scanning of the surface, as will be explained in principle on the following figures.

On the front side is installed a nickel sheet I3, folded in accordion shape (Fig. 2), receiving the insulating and the conducting deposits I9 composing the anodes (the nickel sheet I8 is electrically insulated from the longitudinal beams 6 by an insulating sheet). Lastly, in contact with the glass partition, is placed a fluorescent paint 33, which constitutes the fundamental element of the electric-optical transformation. When the plasma of the positive column arrives locally into the fluorescent substance, it provokes therein a strong light and it permits to thus restitute each one of the televised picture points. The ionized plasma which exists continually in the cathodic compartment "5 can extend itself in each one of the holes, only if the corresponding blocking electrodes 30 and 3l, and also the modulating electrode 28, are all carried to a positive tension.

On account of the presence of the walls 6 passing through the slots 2| (Fig. 2), it is not always possible to installa single conductor in the plan of the grids: it is therefore necessary to produce it by sections, and, for uniting those sections, use must be made of the slots 22, provided for along the wall 6 (and to be seen in perspective view in the Figure 2-). Thus have been shown, in 28 and 32, some wirings disposed on the neighbouring insulating sheets and which permit to effect the said connection.

The Figure 5 is a general diagram of the electrical connections, which permits to understand the working of the apparatus, and more especially the function of the distribution compartment (2, in the Figure l).

The very short radio Waves which carry the television are collected, as is usual, by a receiver 38 which amplifies and detects (rectified) the signals. Those latter then pass in through a selecting device 39, which separates the video impulses from the end-of-line-signals and from the end-of-picture-si'gnals. The video impulses are amplified again in 40, and they serve to feed a distributing device 36, called high speed device. The said device comprises at the inlet a single circuit (common channel) and it comprises at the outlet as many circuits (multiple channels) as there are of vertica1 lines in the televised picture (29, 30, 3i, 32, 33, 34). In the Figure 3 has been shown symbolically that distribution system, in the shape of a brush 36, driven by a small synchronous motor 4l, synchronized with the line signals. Here again it must be understood that the indication is purely symbolical in what regards the diagram, since, in fact, the distribution is effected in an entirely static manner, according to the process already described by the inventor in at least one of his prior patents, namely U. S. Patent No. 2,201,066, and by making use of valves fed by means of current distributors having' frequencies which are submultiples the ones of the others and synchronized on the end-of-line-impulses, and as described in his British Patent No. 506,877.

The end-of-line signals are used also for synchronizing three relaxators (frame 91), giving saw-tooth tensions, the function of which will be explained later. On their part, the end-ofpicture signals serve to secure the synchronism of a, distributing device 46, shown also symbolically by a brush driven by a small synchronous motor 28.

For the clarity of the figure, it has been assumed that the screen comprised three horizontal lines, each of which having only 3 points; it has been assumed that the screen was intended for the colour television and that this latter was obtained by means of two colours only, red and blue. It is fully obvious that, in the practice, the number of lines will really be much larger (a thousand or so, for instance), and that the number of points of each line will also be very high (of the order of 1200). In general also, use will be made of a trichrome system, but this does not change anything in the explanation of principle which will be given.

For a better understanding of the system, the figure represents by rotary mechanical commutators the various commutating devices. It is obvious that, in the practice, use could not be made of such commutators, on account of the unattainable speeds which would be necessary. The devices shown must therefore be considered only as symbolical.

In dotted lines have been shown the individual columns in which takes place the control of the passage of the ionized plasma. The rear of the screen is composed of the cathodic compartment 5, a vast enclosure of flat shape, evacuated and lled with an ionizable gas (or vapor). On that enclosure open out the many alined channels 56, 51-56', 51-56", 51- etc. composing the rst picture line. The second line is in the same way composed of other channels, to which has been given in the figure the index 1 (561, 511- 5SH, 51'1, etc. which receives the index 2.

The channels 56, with the corresponding fluorescent screen, are intended for the reproduction of the red colour, the channels 51 for the reproduction of the blue.

In each one of the said channels are installed in succession a first grid (a modulating one or 12) and a second grid (a blocking grid 1| or 13); and, opposite the outlet opening is an anode 68. all the channels of each one of the lines. Each one of the grids has received a designation comprising asterics for the various channels of each line and an index for identifying each one of the lines.

In the cathodic compartment at the rear are installed the emitting cathode l and several anodes 3 (in the angles of the screen) the function of which has already been explained in connection with the Figure 1. Each anode 3, 3', etc. is connected by a resistance 4, 4', etc. to a direct current distribution B. All the anodes located in the central part of the screen are connected (each one through a resistance) to a, common channel or line 43. All the anodes located in the right part of the screen are similarly connected (each one through a resistance) to a common line 44. There is applied, in turn, to each one of the said lines, 42, 43, 44, a progressively increasing tension of sawtooth shape, the duty of that tension is to cause,

and so on for the third line The same disposition is repeated for more or less tardively (according to the potential applied to the control grids) the illumination of the screen opposite the channel.

For feeding each one of the anode groups (conductors 42, 43, 44), use is made of the saw-tooth tensions which are shifted the ones with regard to the others in the course of time: there has been shown schematically, in the dotted frame 91, those various tensions, but their mode of production has not been shown in order not to overcharge the gure. A saw-tooth tension is, for instance, obtained in a classical way, by the use of a thyratron which discharges suddenly a condenser, this latter being progressively recharged through a large resistance.

For obtaining three saw-tooth tensions shifted in the time the ones from the others, use is made for instance of three independent thyratrons, each one of which supplying one of the saw-tooth tensions (the conductors 42, 43, 44 of each thyratron are connected to the terminals of each of the condensers, the other terminal of the condenser being connected to the cathode l through a battery), the grid potential of each of those thyratrons is modified in the course of time; for obtaining the flat portion of the tension curve, the grid of the thyratron is momentarily maintained at a positive tension: that makes it conducting and prevents the corresponding condenser from being charged. For obtaining the progressive rise of the tension, on

ythe contrary, the grid is carried to a negative potential, and that permits the condenser to be progressively charged. By carrying the thyratron grid to an alternating voltage, the amplitude and the absolute value of which with regard to the cathode of the thyratron are suitably chosen, the tube is caused for a certain time to be insulating, at each period of the control voltage and for a certain time the tube is caused to be conducting; then, for another time interval the tube is caused to be insulating; and thus is obtained one of the curves shown in the rectangle 91. For obtaining the shift in time between the saw-tooth curves supplied by the three thyratrons, it is sucient to use three grid control voltages, corresponding to the three phases of a three phase distribution supplied by a small auxiliary heterodyne. That heterodyne is synchronized on the end-of-line-impulses (arrow coming from the distributor 39).

The first modulation grids (10--12, etc. of all the elements corresponding to one same vertical line are connected together: thus the grids 10, 12, 101, 121, 102, 122, are connected to the first conductor 29. In the same way the grids 10', 12', 101, 122, are connected to the second conductor 30. The same disposition applies to the grids 10", etc. which are connected to the third conductor 3|, and so on for the conductors 32, 33, 34, corresponding to the 6 successive points of the horizontal lines. The conductors 29, 30, 3l, 32, 33, 34, designated by the general term vertical conductors of the screen, receive their modulation from a distributing device 36 (called high speed distributor). The connection is effected periodically, at each revolution of the main brush of the high speed commutator. The voltage distributed by the main brush maintains itself on each conductor for an appreciable time, thanks to the condensers 45, till an auxiliary brush connected to the "mass (or grounded) comes to discharge the condenser just before a new passage of the main brush.

The voltages of the locking grids 1|, 13, etc.

are controlled by a scanning device, herein shown in the shape of a rotary mechanical commutator 46. The grids of several tubes disposed on a same common horizontal line are connected together to one of the fixed studs of a rotary commutator. In the figure, the locking grids 1 I and 1|', which correspond to the red points of the rst third part of the rst line, are connected to the following stud 15. The locking grids to the stud 14. The blocking grids 1l and 1I"' corresponding to the red points of the second third part of the first line are connected to the following stud 15. The blocking grids 1l and 1I"" cf the third section of the first line are connected to the following stud 16.

The following line (second line of the picture), is, on the contrary, connected to the blue points (so as to preferably effect an interlacing of the colours): the second blocking grids 131, 131 (blue), of the first third of the second line, are connected to the following stud 11. The same connections go on for the other grids of the second line of the picture on the studs 18, 19. The blocking grids (112, 112) which correspond to the red points of the third picture line are similarly connected to the following studs BEI, 8l, 82, etc. The scanning is continued with he following studs 83 to 90, that permits to eect a second scanning of the picture with complementary colours.

Each one of the commutator studs of the rotary commutator is normally carried to a negative voltage (thanks to a large individual resistance S5 and to a polarizing battery 99). The commutator brush 45 has for effect to momentarily carry each group of grids to a positive tension during a certain time interval. It is during that interval that the discharge can extend into the corresponding channels. That brush is driven by a motor 28, synchronized on the end-of-line impulses.

For modulating the light emitted by eachv one of the nourescent product (3 of the Fig. 4) disposed opposite-each channel, use is made of the principle of the modulation by phase shifting. The inventor has observed that, if in an ionic tube a progressively increasing tension in the course of time is applied, the tube did not light up immediately, but that it lighted up more or less tardily according to the value of the negative voltage applied to the control grid v(or recul of the grid). According to the invention, I supply the anodes (68, 69, etc. by using a sawtooth Voltage. The extension of the plasma in each channel thus takes place more or less tardily. The inventor has therefore the means of causing the duration of the lighting up in the course of a cycle. If the cadence of that cycle is rapid enough (cadence of the saw-tooth), the,

mean value of the brightness supplied (or of the current delivered by the anode) is a function of the negative tension applied to the control electrode; thus is obtained, by the means described, the intensity of the point to be reproduced.

The Figure 6 represents, as a function of the time, the voltages in the various circuits and permits to understand the working of the system.

On the first line of that figure are shown, in V1, V2, V3, V4, V5, Vs, Vi, Vz, etc. the successive values of the tension of the video signal coming in from the amplifier 40 and reaching the high speed distributor 36. That distributor has for effect to apply those successive values of the tension, respectively to the conductors (vertical conductors of the screen) v 29, 33, 3|, 32, 33, 34, and through them to the grids 10, 10', 10", 10"', 10, 10"". There has been, on the other hand, shown on the second line of the Figure 6 the potential applied in the course of time by the conductor 29 to the grid 1G. On the third line has been similarly shown the potential of the conductor 30 and of the grid 1'; and then on the following line the one of the conductor 3| and of the grid 10". On the following line, the one of the conductor 32 and of the grid 10"; on the next following line the one of the conductor 331 and of the grid 10, and finally, on the last line, the one of the conductor 34 and of the grid 10.

It is easy to realize, with no need of repeating the explanation, how one succeeds in modulating the channels of all the lines by means of the same process, and how it is possible to reproduce the whole of the televised picture.v

The control of the modulating grids 1El-12, etc. of the blocking grids 1|,13, etc. necessitates the passing of a very large number of conductors through the walls or partitions, and that involves a difficult problem of construction. Being given that the mean average value of the potential remains approximately constant in the course of a period and as it is only the phase of the positive tension which varies, it is possible to transmit the yalternating current which feeds those grids by capacity effect through the wall. To that effect are shown in the Figure 4 on the rear wall I6 (Fig. 4) the capacities represented by their internal and external armatures 14 and 15.

The three following curves represent the potential 'applied respectively to the blocking grids 1I-1I' simultaneously, 1l-1l, simultaneously, and 1I-1I"' simultaneously.

At last, on the third lines has been represented the saw-tooth voltage applied to the anodes: the anodes of the two first channels (on the left) correspond to the saw-tooth voltage V42, the anodes of the two next channels (in the middle) correspond to the saw-tooth voltage V43; the anodes of the two last channels (on the right) to the saw-tooth voltage V44.

The scale of those saw-tooth tensions has been so chosen that it is sufficient to take the values V1 Va from the rst line of the figure and to transfer them on the saw-tooth curve for determining the moment of the starting time of the wave; that moment takes place the more tardily as the higher is the amplitude of the tension applied to the modulation grid. The part of the curve from which each of the cells is expected to light up has been cross-hatched thus it is seen, for instance, from the figure, that the amplitude V3 was relatively very low and in the figure the saw-tooth is Iahnost entirely cross-hatched while, for instance, the amplitude Vs was very very low, the cross-hatched part is on the contrary very much reduced.

The amount of light supplied by the uorescent tube, as Ythe mean average value of the current delivered by the anode, corresponds appreciably to the surface of the cross-hatched part in each of the cases; thus the third point of the line (V3 being small) will give a bright light, while, on the contrary, the sixth point (Ve being very large) will give a very low amount of light. The curves of the Figure 4 show how it has been possible to successfully reproduce the first line of the televised picture.

The invention relates moreover also to an improvement and a simplification of the wiring,

namely the one which is used for feeding the blocking grids, and to a special disposition of the tube which permits that amplification. With the modern high denition screen (1,000 lines for instance) and used for colour operation trichrome process, the number of the conductors to provide for feeding the blocking grids is extremely high (3 times the number of lines for each one of the colour: i.e. 9,000), and that is a various difliculty.

According to an improved variant of the invention, in order to reduce the number of the conductors and to avoid that diiculty use is made no longer a single locking grid, but of several grids disposed in succession along each channel: the grids of each rank of a large number `of channels are connected together so `as to compose some groups, and it is simultaneously acted upon the potential of the said groups of each rank for effecting the scanning.

The Figure 7 shows the principle of that scanning. For clarifying the diagram and avoiding the crossing of the conducting wires, all the points of the screen have been assumed to be placed along one line only, but that does not change in any way the principle hereby exposed. There can be seen again the cathode I, the rear cathodic chamber 5 and the individual channels in which is eiected the control of the ionisation, but according to the present variant use is made, no longer of a single locking grid, but of two grids in cascade (|00, etc. |50, |5|. etc. The grids |00, etc. .of the successive channels are connected in turn to the 6 studs: |26, |21, |28, |29, |30, |3|, of a rst commutator |24.

In the case of the iigure, have been represented 24 channels, so that 4.- complete revolutions of the brush on the commutator |24 are needed for securing the total scanning. The grids |50, |13, are connected by groups, the number of the channel composing each group is equal to one half of the number of the studs of the rst commutator |24 (i. e. to three in the case of the ngure). Thus are composed 8 independent groups: |33, |34, |35, |36, |31, |38, |39, |40, each one of which feed 3 grids. Each one of the said groups, is connected to the studs of the second commutator |32. The studs of the various commutators are normally polarized negatively with regard to the cathode I, thanks to a large individual resistance 14| for the commutator |32 (a resistance |25 for the commutator E24.) and a battery |46 for the commutator |32 (and |43 for the commutator |24). When revolving on the commutator, each one of the brushes |24 or |32 carries momentarily the corresponding stud to a positive voltage, supplied by the battery |45 for the commutator |32 (and by the battery |44 for the commutator |24). One revolution of the brush on the commutator is suflicient for eiecting the whole scanning, or in other terms the brush on the commutator |32 revolves 4 times less rapidly than the brush of the commutator |24. The rotation of that brush 32 is synchronized on the end-of-picture-impulses.

The working of the system is easy to understand: the passage of the brush |32 on the first stud of the commutator is effective in unlocking the grids |50|5||52, of the rst stage of the channels of rank l, 2, 3. The passage of the brush on the iirst stud |26 of the commutator |24 has for eiTect to unlock in the same time the grids of the second stage of the channels of rank l, I3, I9. Therefrom results that the rst channel only is unlocked. Immediately after that, the brush revolving on the commutator |24 has for efrect to unlock the upper grid |0| of the second channel; but the brush on the commutator |03, |32 has not yet had time enough to revolve appreciably, and it is always the irst group which is unlocked.

The second channel only is thus unlocked. Immediately after that, as the brush continues to revolve on the commutator |24, the grid |02 is carried to a positive tension. It is the second channel which is then unlocked. Immediately after that, as the brush |24 continues to revolve, it reaches the stud |29, the grid |03 is carried to a positive tension, and it is the fourth channel which is unlocked. But meanwhile, the brush of the commutator |32 has revolved to an appreciable extent; it has come into contact with the next segment |34 which feeds the second group (grids |53|54|55 while keeping still in contact with the first one. The grids of the second group are thus unlocked in the same time as the ones of the first group, but this is not an inconvenience, since none of the upper grids of the channels of the rst group runs the risk to be unlocked, the brush of the commutator |24 having no possibility to reach them: its position does no longer enable it, in fact, to reach the studs |26, |21, |28, since it has already run past the stud |29. It is therefore the fourth channel only which is unlocked. Immediately after that, as the brush continues to revolve on the commutator |24, while the brush of the commutator |32 continues to unlock the second group, it is the 5th channel which is unlocked, and so on.

It can be seen that the gears which effect the transmission of the motion between the brushes of the commutators |24 and |32 do not need to be very accurate, thanks to that period of overlapping which leaves a certain tolerance. Of course, instead of mechanical commutators, use can be made of static distribution devices of electrical type, such as the ones already described by the inventor, which give out equivalent results: the period of overlapping explained in the Figure 7 permits to admit a certain tolerance in the accuracy in the frequencies of the two distributing devices which eiect statically the distributing in a very easy manner. The system` can be generalized.

With three commutators, comprising each 32 studs only, for instance, to be scanned:

active channels: i. e. 8,192 elements. In that case wherein are connected together the locking grids on 1/3 of the line, and is used a trichrome process of television, that corresponds to a picture having a number of lines equal to:

what is largely sufcient in practice. And there should not be anything more to provide than 3 32=96 conductors instead of more than 8,000, that is a great simplication.

Instead of making use of the iiux of electric charges lling each cell for acting locally upon the uorescent screen, it is possible also to use the variation of the anode potential, or else the intensity of the current of that anode for modulating electrostatically the optical element, and thus utilizing the impulses which have been distributed by the tube.

The Figure 8 represents the principle of that process: as previously shown in 5 the anodic compartment and in 2 the wall perforated with holes open, to the modulation channels. Along the said channels are installed the grids (or the grid) GB which effect the scanning, and the modulating grid GM which controls the ilux. Opposite each channel is disposed the anode Il'll, connected through a resistance H5 to the supply voltage |16 (of saw-tooth shape). That anode is fixed along the electro-optical element H1 (or else it is acted upon from a distance through a conducting wire) On the other face of the electro-optical element is disposed an armature |18 connected to the earth. The electro-optical element |11 thus receives an electrostatical tension, the mean value of which is a function of the modulation.

The electrostatic field created between the two armatures |14 and |18 permits to cause the variation of the amount of light received from the outside or transmitted through the element |11.

According to a preferred disposition of the invention, use is made of a colloidal liquid polarizing the light, disposed opposite a white surface (inside face of the electrode IM), according to the process already described by the inventor. Thus is realized an element of surface which diffuses the light coming from the outside and which falls on it: the amount of diffused light is a function of the modulation applied to the tube object of the invention, which serves then as a distributing and modulating device (Without creating by itself, as above described, in connection with the preceding gures, the light by emission of a fluorescent material).

What I claim and desire to secure by Letters Patent of the United States is:

l. In combination, in a picture reproducing system, a reservoir of normally ionized gas, a iluorescent screen, a plurality of discrete gas lled passages extending between said reservoir and said screen, said passages being supplied with gas from said reservoir, means normally maintaining gas in said passages de-ionized, and means for ionizing gas in said passages in accordance with a predetermined time sequence pattern.

2. In combination, in a picture reproducing system, a plurality of discrete and mutually isolated columns of ionizable gas arranged physically in parallel and in substantial juxtaposition, the ends of said columns occupying substantially a predetermined plane area, a fluorescent screen occupying said plane area and in contact with said ends of said columns, means for selectively ionizing the gas content of said columns in accordance with a predetermined time sequence pattern, ionization of the gas con tent of each one of said columns establishing uorescence in a different area of said screen adjacent the end of said each one of said columns.

3. In combination, in a picture reproducing system, a reservoir of ionized gas, a plurality of discrete and mutually isolated passages for said ionized gas each of said passages communicating with said reservoir and forming a column of gas derived therefrom, the ends of said columns remote from said reservoir occupying substantially a predetermined plane area, a fluorescent screen occupying said plane area and in contact with said ends of said columns of gas, ionization of the gas content of any one of said columns establishing in an area of said fluorescent screen adjacent the end of said any one of said columns an area of fluorescence of said screen, means in each of said passages normally maintaining gas in all said columns de-ionized, and means for disabling said last named means in accordance with a predetermined time sequence pattern.

4. In combination, in a picture reproducing system, a reservoir of ionized gas, a visual screen, a plurality of discrete gas filled passages extending between said reservoir and said visual screen, said passages being lled with gas from said reservoir, means normally maintaining gas in said passages de-ionized, and means for ionizing gas in said passages selectively in a predetermined time sequence, and means for illuminating a portion of said visual screen in response to ionization of gas in each of said passages.

5. The combination in accordance with claim 4 wherein said visual screen comprises a iiuorescent coating.

6. The combination in accordance with claim 4 wherein said visual screen comprises a plurality of light valves.

7. In combination in a picture reproducing system, a column of gas, a first, a second and a third control electrode arranged in ionization controlling relation to said column of gas, means for connecting alternatively to said iirst control electrode an ionization preventing or a gas ionization enabling potential, means for applying to said second control electrode a signal potential of variable magnitude, and means for applying to said third control electrode a voltage varying in magnitude with time over a range of magnitudes adapted to establish ionization of said column of gas at times dependent on the magnitude of said signal potential, visual presentation means associated with said column and energized to provide an element of said picture in response to ionization of said column of gas.

8. In combination, in a picture reproducing system, a reservoir of ionizable gas, means for maintaining said ionizable gas ionized, a plurality of discrete and mutually isolated columns of gas deriving from said reservoir, said columns arranged physically in rows, the ends of said columns remote from said reservoir occupying a predetermined plane area, a rst, a second and a third control electrode arranged in ionization controlling relation to each of said columns, means for connecting to said rst control electrodes simultaneously a potential adapted to prevent ionization of gas in said columns, means for connecting to said first control electrodes in predetermined time sequence a potential adapted to enable ionization of said columns, a source of video signal, means for applying to said second control electrodes in predetermined order said video signal, and means for applying saw-tooth voltages to said third control electrodes in predetermined sequence.

9. In combination, in a picture reproducing system, a reservoir of ionizable gas, means for maintaining said ionizable gas ionized, a plurality of discrete and mutually isolated columns of gas deriving from said reservoir, said columns being arranged physically in rows, the ends of said columns remote from said reservoir occupying a predetermined plane area, a source of groups of successive video signals components, means for applying successive ones of each group of said components to diierent ones of said rows of columns to establish predetermined potentials in the gas content thereof, means normally maintaining all of said columns in de-ionized condition, means for disabling said last means in successive columns of each row successively at the termination of each of 'said groups, and means for applying to each column having a disabled means for normally maintainingv said column in de-ionized condition a substantially increasing potential, for the duration of disablement.

10. A color television system comprising a iiuorescent screen having a uorescent coating comprising a pattern of alternately different uorescent coating portions, said diierent iiuorescent coating portions providing when excited visual indications of different colors, a plurality of exciting means, one for exciting each of said coating portions, each of said exciting means comprising a discrete column of ionizable gas in contact with a coating portion and means for actuating said exciting means in a predetermined sequence, said last means comprising means for ionizing the gas in said discrete columns in said predetermined sequence.

11. A color television system comprising a iiuorescent screen having a fluorescent coating comprising a pattern of alternately different fluorescent coating portions, said diierent coating portions providing when excited visual indications of respectively different colors, a plurality of exciting means each comprising an ionizable column of gas in contact with one of said coating portions, said fluorescent coating portions being excitable each in response to ionization of its contacting column of gas, and means for ionizing said columns of gas in a predetermined sequence.

l2. In combination, in a picture reproducing system, means for ionizing a plurality of columns of ionizable gas in sequence, each of said columns corresponding with an element of said picture, said first means comprising a rst and a second control electrode arranged to control ionization of each of said columns, a rst commutator for applying to said first electrodes of successive groups of said columns simultaneously a first control potential, a second commutator for applying to successive ones said second electrodes of each of said groups of columns a second control potential during application to said first electrodes of said first potential, each of said columns of ionizable gas being ionizable only in response to simultaneous application tov said iirst and second control electrodes thereof of said rst and second control potentials, respectively.

13. In combination, in a picture reproduction system, a reservoir of ionized gas, a plurality of light valves each transferring light in correspondence with a control potential applied thereto, a plurality of discrete gas filled passages each extending between said reservoir and one of said light valves, means normally maintaining gas in said passages de-ionized, means for ionizing gas in said passages in accordance with a predetermined timing pattern, and means responsive to ionization of said gas in each of said passages for generating a control potential for application to its associated light Valve.

14. In combination, in a picture reproducing system, a reservoir of ionized gas, a plurality of discrete and mutually isolated passages for said ionized gas, each of said passages communicating with said reservoir and forming a column of gas derived therefrom, the ends of said columns remote from said reservoir occupying substantially a predetermined plane area, a plurality of light valves occupying said plane area each in association with one of said passages, means responsive to ionization of gas in any of said passages for controlling its associated light valve to transfer light, discrete means associated with each of said passages for normally maintaining said gas in all said passages de-ionized, and means for disabling said last means in time sequence.

15. In combination, in a picture reproducing system, a reservoir of ionized gas, a fluorescent screen, a plurality of discrete gas iilled passages extending between said reservoir and said screen, said passages being supplied with gas from said reservoir, means for enabling ionization of gas in each of said passages in sequence only, means for initiating ionization of gas in each of said columns during enablement of said ionization for a controllable portion only of the time of said enablement, a source of video signals, and means responsive to said video signals for controlling the duration of said portion.

16. In combination, in a picture reproducing system, a reservoir of normally ionized gas, a plurality of light Valves, a plurality of discrete gas iilled passages each extending between said reservoir and one of said light valves, means normally preventing ionization of gas in said passages, said passages being supplied with gas from said reservoir, each of said light valves actuable to pass light only in the presence of ionized gas adjacent thereto, means for enabling ionization of gas in each of said passages in sequence only, means for initiating ionization of gas in each of said columns, during enablement of ionization thereof, for a controllable portion only of the time of said enablement, a source of video signals, and means responsive to said video signals for controlling the duration of said portion.

17. In combination, in a picture reproducing system, a reservoir of ionized gas, a plurality of light sources, a plurality of discrete gas illed passages each extending from said reservoir substantially to one of said light sources, means normally preventing ionization oi' gas in said passages, said light sources actuable to produce light only in the presence of ionized gas adjacent thereto, means for enabling ionization of gas in said passages in sequence and each for a predetermined time, means for initiating ionization of gas in said columns during enablement of ionization, for a controllable portion only of said predetermined time, a source of video signals, and means responsive to said video signals for controlling the duration of said controllable portion.

18. In combination, a reservoir of normally ionized gas, a tube communicating with said reservoir of ionized gas and containing gas, means comprising a control electrode normally maintaining the gas in said tube de-ionized, means for varying the voltage of said control electrode suiciently to enable transfer of ionization from the gas in said reservoir to the gas in said tube for a predetermined time interval, a source of signal of variable amplitude, and means responsive to said signal of variable amplitude for accomplishing transfer of ionization from the gas in said reservoir to the gas in said tube for a duration representative of the amplitude of said signal of variable amplitude.

19. In combination, a container containing gas, a plurality of passageways for said gas leading from said container, means for normally maintaining ionized the gas in said container, means for normally maintaining de-ionized the gas in said passageways, a source of control signal of variable amplitude, and means responsive to said control signal for enabling transfer of ionization of gas from the gas in said container to the gas in said passageways in sequence and in each passageway for a duration determined by the amplitude of said control signal.

20. In combination, in a picture reproducing system, a reservoir of normally ionized gas, a Visual screen, a plurality of discrete gas filled passages each extending between said reservoir and a portion of said screen, each screen portion comprising means responsive only to ionization of gas in the passage between said reservoir and said each screen portion for providing a visual presentation, means for normally maintaining gas in said passages de-ionized, said last means comp-rising a rst control electrode in each of said passages, and means for maintaining said first control electrode in each of said passages biased negatively suiciently to prevent ionization of gas in said each of said passages. means for raising the potential of said first control electrodes in sequence to a value adequate to enable ionization of gas in said each of said passages in sequence, a second and a third control electrode in each of said passages, means for applying video voltages to said second control electrodes, means for applying saw-tooth voltages to said third control electrodes, the magnitudes of said video and saw-tooth voltages being selected to accomplish ionization of gas at a point in each saw-tooth voltage determined by the magnitude of the video signal, in each passage, when the potential of the rst 'control electrode in that passage is raised to said value adequate to enable ionization of gas in that passage.

PIERRE MARLJ GABRIEL TOULON.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,021,010 Jenkins Nov. 12, 1935 2,110,576 Karolus Mar. 8, 1938 2,296,908 Crosby Sept. 29, 1942 2,315,288 Knoop Mar. 30, 1943 2,461,515 Bronwell Feb. 15,*1949

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