US2175573A - Electron beam converter - Google Patents

Description

. @et i0, i939. F. scHR-rER I 2,175,573

ELHcTRoN BMM coNvBRTExR Filed March 20, '193 2 Sheets-Sheet 1 fyi FRITZ svcu o'TER BY M I W0 ATTQRNEY F. 'scHR'n-:R 2,175,573 ELncTnoN BEAM CONVERTER Filed March 20, 1936 2 Sheets-Sheet 2 INVEN-roR FRITZ S ROTER BY v AToRNEY Gm. W, i939.

Patentes oci. 1o, `1939 v 2,175,573

UNHTED STATES PATENT OFF-ICE'` ELECTBON BEAM CONVERTER Fritz Schrter, Berlin, Germany, assigner to Telefunken Gesellschaft fr D htlose Telegraphie m. b. ll., Berlin, Germany, a corporatonof Ge Application March 2o, 193s, serial No. 69,821 in his, less The object of this invention is to provide an sweep over the row of constituent cells, while inertialess electron-beam converter of the kind the intensity thereof is at the same time moduespecially adapted'for use in intelligence translated by the video signal to be transmitted by mission. This converter utilizes the motion or means of a control electrode, this will result in Vi5 sweep Ain vacuo of one or several independent charging of the cells. By properly choosing the 5 inertialess cathode-ray pencils .in such a way operating potentials of the tube, the charging that the pencil electrons, in quantities controlled process occurs due to secondary emission from in a way being either constant or variable with the cells in a positive sense. It will be apparent time, are consecutively caused to strike or imto those skilled in thel art that optimum potenpinge upona number of insulated capacitive contial values should be chosen in operating the 'l0 ductors which conductors are incidentally caused tube. 'Ine distribution of the charges correto give oi secondary electrons proportional to 'spending to the modulation of the cathode ray the incidence of the primary electrons. 'I'he conbeam will be preserved for a `certain length of ductors thus acquire corresponding charges, and time on the cells, and the length of time depends l5 by virtue of their uniform capacity in reference on the particular cells used and, of course, the to a joint or common coat or plate are adapted characteristic curve of these cells that charge also for the storing of modulator actions of the thereon plotted against time. Il. then, a cathodecathode-ray pencil in the form of an undisray pencil is again caused to sweep over the row of torted distribution of potential. these cells, at a constant intensity, although aczo In the iconoscope known in the prior art and coi-ding to the desired purpose the direction or which is used for television scanning, the picture the velocity of the pencil sweep or motion may to be televised is thrown, as a whole upon a tarbe varied, the secondary emission eiiect will again get plate which consists of a multiplicity of be varied at the rhythm and rate of the accumumicroscopic elementary condensers possessing" lated modulation. In the said second scan or photoelectric activity and being capable oi secsweep, therefore, the original modulation curve 25 ondaiy electron emission. The charges caused will be picked up and obtained, as may be deby light actions accumulated thereonare perisired, in the same or in inverse sequence, and odically evaluated by a scanning cathode-ray penwith increased, constant, or reduced velocity and cil by means of secondary electron emission. The incidental levelling of the potential. This, thereso-called plate of the iconoscope thus acts as a lfore, constitutes a convenient means for frequen.. 8G

transducer to convert light or luminous actions cy conversionV of periodic, modulated, or noninto current or electrical actions. Contradistinct modulated currents, and for inversion of time therefrom, what is concerned in the present inmodulation actions for use in secrecy or coding Vention is a purely electrostaticcumulator Whose in telephony. Moreover, it aords a means elements are not acted upon by light. but which adapted to insure any desired signal accumula- 35 merely transmit and vary electrical actions. tion 0r storing in telegraphy work making use of The basic idea of the invention shall be illus' repetition. Since, furthermore, converter tubes Hated and explained eS fellOWS! Upon the an'. of this kind can be connected in parallel so that terior face of a tenuous insulation layer or sheet the incoming modulation may be impressed simu1- 4o 0f glass 01* mice are applied tiny silver areas taneously upon several cumulators, which may 40 0r patches insulated from 011e aIlOtheI. While then be scanned in sequence, this gives a chance, the rear face of the collective capacity is silverin picture telegraphy and television work, to vary Coated thrOushOut. The Silver Cells are renat will anygiven picture sequence each second, dered capable of secondary electron emission in a, feature which will be found valuable with a known manner in the vacuum 0f the cathodeview to reducing the bandwidth 1n certain trans- 45 ray tube by deposition 0f vapors of barium or mission channels. In other Words, the sequence of caesium. The cathode-ray pencil caused to scanning a picture may be varied due to the Sweep thereOVel iS Produced, as also known in fact that the same intelligence may be recorded the art, by a heated cathode opposite which are on several tubes, and the limitations accompany- .3odisposed a vcontrol electrode and one or several ingthe use of a single scanning system is avoidanOClS forming electron-Optic means. The co1- ed. The basic idea of this invention may morelective or common coat of the cell condenser is over be modied in such a way that the modulaat approximately anode potential. If, then, by tion cumulated by the recordingv cathode-ray the action of an electric or magnetic field the pencil, upon reproduction, may be scanned simul- QathOdS-I'ay pencil 1S deeted and caused t0 taneously by several independent cathode-ray 55 dil pencils acting in groups. For instance, a. singlechannel transmission may be divided between a Vplurality or" receiver means and channels acting in parallel, or vice versa. This may be valuable, for example, with a View to obtaining large and yet bright pictures, and in this connection, "necause of an increased optical representation, simultaneous control and representation of several picture units may be the proper solution of the diculties inherent in luminosity or illumination. It will be appreciated that where it is possible to divide a transmission which ordinarily takes place over a single channel between a number of parallel channels, each channel will carry a more narrow band of frequencies, and this is especially important in the transmission of video signals by Wire since the use of conductors with a limited frequency band of transmission range is often both desirable and necessary.

In building cathode-ray tubes of the kind used in this invention, recourse is had to the ways and means known from high-vacuum work, electron-optics, and hot-cathode manufacture, such as found in combination in :modern Braun tubes for the representation of television pictures, in the iconoscope, in the electronic microscope, etc. These tubes operate with a high vacuum, for it is only under such conditions that the secondary` emission and accumulation will proceed in a satisfactory manner. To 'deilect or move the cathode-ray pencil or pencils there are employed periodic fields of an electrostatic or magnetic nature which are set up by potentials or currents having the desired curve-shape. Rotational movements of the cathode-ray pencils are producible by crossed lelds ted with phase-displaced currents.

lvfy invention Will best be understood by reference to the figures of the drawings in which:

Fig. l is a screen arrangement,

Fig. 2 is one embodiment of my invention,

Fig. 3 is a combination of strip elements forming a screen, and

Fig. l is another embodiment of my invention.

Fig. l is a fundamental view of the construction of a linear electrode system adapted to accumulate charges produced by the scanning cathoderay pencil by virtue of secondary emission. The metallic strip i has a series of apertures which, with the interposltion oi dielectric substance 3 are filled with substance 2 capable of secondary electron emission. In this manner there results a series of tiny elementary condensers `Whose insulated coats 2 are dielectricallysaparated from the joint cin-operative coat l. If, then, the cathode-ray pencil is caused to sweep either at a constant or at a variable intensity over the anterior faces of the row of cells 2 care having to be taken, however, so that I will be safeguarded from the impact of pencil electrons, the said pencil will occasion constant or variable potential diferences between these cells and the collective or joint electrode i. It should be appreciated that-the drawings in the case are not differs therefrom, that is to say, that si ips of insulating material upon one face thereof are metallized throughout, while upon the opposite face metallization is in the form of tiny and separated areas or patches, whereupon the latter are rendered capable o secondary electron emission. This may be termed a double mosaic type or" structure.

Figs. 2 and 3 illustrate an exemplified embodirnent of the invention in connection with a scheine adapted to code- (or garhle) speech transmitted over telephonie channels. The twintype cathode-ray pencil converter tube here used is indicated by R. The cumulator system l which corresponds to the one shown in Fig. l is mounted in the center of the tube R. By shielding means care is taken so that secondary electrons released by a cathode-ray pencil will be drawn only towards the anode which lies on the impact side of the primary electrons. The two anodes which consist of a conducting wall coat are designated at ll and d. To produce the cathoderays im and 2l indicated by the broken arrows there are further provided electrode systems of a lrind well known in the art and comprising the first anodes t, the modulator electrodes 6 and d', and the heated cathodes l and l', the latter being preferably of the indirectly heated kind. To supply the working D. C.y potentials for tube R, there may be provided, for instance, a potentiometer t on which are tapped the various potentials by Way of resistorsS, il), I l, and I2. The common coat of system I shall be assumed to be grounded; also a suitable point of the potentlometer.

A more detailed View of a system embodying the use of the arrangement of Fig l is shown in Fig. 3. The screen or storing arrangement consists of two halves or members I', i which are elliptlcally or circularly curved, the said two halves being held together and assembled by short interposed pieces of insulation indicated at 2E and 23. The closed elliptical paths along I and i" are scanned by two cathode ray pencils 20 and 2i (see Fig. 2) at a deilnite phase in opposite sense, with a view to producing the effect hereinafter to be explained in more detail. The motion of the electron beam is provided by crossed magnetic fields which are set up by the schematically shown coils I8, I8 and I9, ISI',l Fig. 2.

Both pairs of coils are energized from dependent generators i5 and i'I-with snuous currents of like frequency, 'but dissimilar amplitude, and in such phase relations that the electron pencils 20, 2l, will run in opposition in the direction of the arrows shown in Fig. 3, and will meet at the neutral points 22 and 23 and cross each oth- Suppose that during this circular motion the electron ray or pencil 2| is modulated in intensity by the currents set up by microphone I4 and amplified by amplifier I5 so that across the terminalsof the resistance I3 voltage variation corresponding to the voice are set up, the said voltage variations being superimposed upon the potential or the modulator electrode 6'. The e1- liptic motion of the voice modulated pencil is indicated in Fig. 3 by the arrows Z. In this periodic circulation, the pencil modulation will be stored up continuously in the various cells 2 (see Fig. l) in the shape of locally varying charge potentials. At the same time, however, by the action of the oppositely sweeping electron pencil 20 from the rear there occurs a time inversed and complete pickup of the stored modulation,

in that peneu zu, es indicated in Fig. a, is eeusea to sweep along i' i" in the sense of the arrow A at the same cyclic frequency as 2l. The timev variations which the electron current reaching anode B experiences, occasion voltagevariations across the terminals of the resistance il which correspond to the transposed, that is to say,l

coded or garbled voice modulation and .which after proper ampliication, are used for secret telephonic transmision.

The fact that in the said manner a continuous and uninterrupted translation or coding of the speech takes place will be readily understood from a reference to Fig. 3. Suppose that the two pencils 2@ and 2i, at a given instant, are positioned at 22; mncil 2i would sweep the upper half of the elliptic path in the sense of the arrow Z and, after a half cycle or revolution, it would cross again pencil 2@ at the neutral point 23. It will be appreciated that the neutral points 22 and 23 may be -used for a number of purposes such, for instance, as the development o a synchronizing signal and the like. The upper path 122-23 of the elliptical 'shaped member which assumes an uncharged state from' the action o the beam of steady value will store up charges due to the action of the modulated beam which impinges thereon after the section has been neutralized. Pencil 2d which sweeping along the lower path has reached point 23 `will then be made to scan, upon the upper half, the recorded modulation, but in inverse sequence, while at the same time the pencil 2i travels along the bottom half from Q3 to 522 and thereby continues the modulation recording, seeing that the. said path had just previously been rendered into the state of quiescent potential by the pencil d@ sweeping in the contrary direction. Owing to the fact that this cycle recurs again and again, thereis brought about an inversion of the modulation frequencies during those periods when the cathode ray beams are continuously being deected. The small gaps at 22 and 23 will do no harm, provided that the distance between them are relatively long. However, recourse could be had to accessory means to the end of causing the pencils 2d and 2i to jump over or skip the said neutral zones 22 and 23 so rapidly that only supersonic interruption frequencies will result (Superposed auxiliary currents).

If at the receiving place a similar equipment is provided as in Figs. l and 3, the modulation coming in in inverted form can be restored to the original shape. The operation of such a decoding or re-converting arrangement will be perfectly clear from what has been explained above.

The cumulator arrangement shown in Fig. 3 is merely to be considered as a simplied embodiment given by way of example. Under practical conditions, short storing paths as here shown will ordinarily not be used, indeed, by the provision of longer cumulator paths or surfaces designed to accommodate more modulation, care will be taken so -that the interrupting frequencies caused by the inter-crossings at the points 22 and 2d, Fig. 3, will be rendered as low as possible. A limitation, of course, is imposed in this respect by the permissible lag in the garbled modulation in reference to the original modulation.

As has been pointed out, arrangements'bf the said sort and comprising suitably designed cumulator system could be used also in connection with telegraphic work using methods in which the same letter signal or impulse, with a view to neutralizing interference or fading or losses of signals, is repeated several times at certain time intervals, such repeated signals being stored up in the receiver, as known from the Verdan and the Siemens-Verden method, etc., as for instance as explained in U. S. 1,677,062.

However, for the practical utilization of this principle large-sized mechanical or electrostatic storing means have heretofore been required. The present invention discloses ways and means to solve the same problem in a simplied manner by the aid of microscopic charge accumulators capable of accommodating a large number of signals so that a greater variation in regard to amount of signals of repeating period and the speed of transmission is permissible.

The principles hereinbei'ore disclosed will be found of great value in connection with the con-1` version of television or video signals, for purposes hereinbefore explained in detail. The basic idea of such conversion is schematically illustrated in Fig. 4. Suppose the problem consists in dividing a normal single-channel television transmission into three simultaneously operating channels, say, for controlling three independent ture. The incoming modulation therefore corresponds to the usual scanning in which always only one elementary area of the picture is transmitted.- Conned inside the tube R are two groups each comprising three or a total of sin strip-shaped cumulators indicated at i". Along each strip is disposed an adequate number of microscopic condenser cells in order that a full line of the incoming single-channel modulation may be faithfully recorded. The six collective or joint coats (corresponding to coat i in Fig. l) are united with one another for RF energy by the capacities 28 so that they represent vfor RF modulation of the single-channel transmission a common coat. For the resultant modulation of 'reduced frequency are provided 2 3= 6 individual lines 29 or, in other words, three pairs.

The single-channel modthe three reproducer channels is eected byv three independent and constant cathode-ray pencils 25, 2t, 2l upon the rear of the system i'". By the ways and means known in modern art it will be readily possible to provide such multiple pencils in a way so that they will not mutually interfere. By synchronized deector systems working with ratchet or relaxation circuit organization, and by means of electrical equalizing means care is taken so that the pencil t will sweep consecutively over the six line cumulators of system i'" in normal line motion, while inside a length of time which must be short in contrast to the synchronizing pause at the end of each line, it will be made to fly lback to the beginning of the rst line. In the meanwhile, the three pick-up pencils 25, 2S, and Il, at a velocity which is only one-third of the other, and with the proper phase displacement, cover parallel to one another and in cyclic alternation the upper and the lower group of strips. The time shift infreference to pencil tl is so chosen that the scg sweep will start at the edge of the picture only after the whole area to be covered inside the period of one line has been finished by the pencil 24. The proper control of vthe three pencils 25, 26, 21,v is insured by the aid of relaxation oscillations which bear a rational 15 `picture units in the receiving or ire-created picfre'quencyrelation to the oscillations causing de- ,ilevction of the pencil 24. In this manner a perfectly continuous and complete change of the single-channel modulation into the three-channel modulation here chosen for the sake of argument is feasible, in fact, division into a greater number of channels is possible by simple means. In order that the simultaneously acting spots which, in the case here concerned, cause recreation of the incoming picture, may be modulatedA independently of one another, it will be necessary to include in the leads 2Q many cornmon coats of the system. i" separate resistances which act as input impedances of the three picture signal ampliers. Pairs of these corresponding to similar strips ci the upper and the lower group of three are (zo-ordinated to the same amp-liner. lihe drops of potential ci theseV three pairs of conjugate resistances may be brought to act alternately in balanced measure upon distinct control grids o1? the same input tube (hexode), or eise they may be brought to act, by Way of push-pull input tubes, alternately upon a single input impedance for each of the three picture-signal amplifiers.

Alternate transmission from a single amplier .of diiering impressed signals is known in the prior art.

What I claim is:

l. An intelligence transmitter comprising means for developing a plurality of independent cathode ray beams, means for accelerating each oi said beams, means'for modulating at least one of said beams in accordance with said intelligence to be transmitted, means for storing an electrostatic image of a portion of said intelligence, and means for translating said stored electrostatic image.

2. An intelligence transmitter comprising means for developing a plurality of independent cathode ray beams, means for modulating at least one 'of said beams in accordance with said intelligence to be transmitted, means for accelerating each of said beamsmeans for deecting each of said beams, means comprising a. plurality of discrete condensers for storing an electrostatic image of a portion of said intelligence, and means for translating said stored electrostatic image.

3. An intelligence transmitter comprising means for developing a plurality of independent cathode ray beams, means for modulating at least one of said beams in accordance with said intelligence to be transmitted, means for accelerating each of said beams, means fordeiectingeach of said beams, a plurality of discrete elements having a high secondary emission characteristic, said elements being arranged in the path of said beams, a. conductor common to all of said discrete elements and in capacitive relationship thereto,and means for translating the charge on each of said discrete elements sequentially.

4. An intelligence transmitter comprising means for developing a. plurality of independent cathode ray beams, means for modulating at least one of said beams in accordance with said intelligence to be transmitted, means for accelerating each f said beams, means for deflecting each of said beams, a plurality of individual screens containing discrete capacitive elements, said screens being arranged adjacent to ,and insulated from each other, and means for energizmg said beam deflecting means in such fashion that unmodulated beams impinge on said screens sequentially and in timed relationship to the modulated beams.

5. An intelligence transmitter comprising means for developing a plurality of independent cathode ray beams, means for modulating at least one of said beams in accordance with said intelligence to be transmitted, means for accelerating each of said beams, means for deecting each of said beams, means comprising a plurality of discrete condensers for storing an electrostatic image of a portion of said intelligence, and means for translating said stored electrostatic image in a fashion reversed with respect to the direction of storing of said image.

6. an intelligence transmitter comprising means for developing a plurality of independent cathode ray beams, means for modulating at least one oi said beams in accordance with intelligence to be transmitted, means ior accelerating each of said beams, means for deecting L each of said beams, a plurality of individual screens containing discrete capacitive elements, a conductor adjacent each screen and common to the capacitor elements thereof, said capacitive elements each being capable of secondarily emitting electrons, and means for simultaneously de fleeting said independent beams so as to maintain a definite relationship between said image recording and said image translation.

7. An intelligence transmitter comprising means for developing a'plurality of independent cathode ray beams, means for modulating one of said beams in accordance with intelligence to be transmitted, means for accelerating each of said beams, means for deflecting each of said beams, a plurality of individual screens containing discrete capacitive elements, a conductor ad' jacent each screen and common to the capacitor elements thereof, said capacitive elements each being capable of secondarily emitting electrons,

and means for simultaneously scanning all of individual screens so as to divide the complete intelligence pattern into groups of signals.

8. An intelligence transmitter comprising means for developing a. plurality of independent cathode ray beams, means for modulating at least one of said beams in accordance with intelligence to be transmitted, means for accelerating each of said beams, means for deflecting each of said beams, a plurality of individual screens containing discrete capacitive elements coated with a material having a high secondary emission characteristic, a conductor adjacent each screen and common to the capacitor elements thereof, and means for simultaneously -deflectng said independent beams so as to maintain a definite relationship between said image recording and said image translation.

9. An intelligence transmitter comprising means for developing a plurality of independent cathode ray beams, means for modulating at least one of said beams in accordance with intelligence to be transmitted, means for accelerating each of said beams, means for deflecting each of said beams, a plurality of individual screens containing discrete capacitive elements, a conductor adjacent each screen and common to the capacitor elements thereof, said conductor being adapted to be maintained substantially at anode potential, said capacitive elements each being capable of secondarily emitting electrons, and means for simultaneously deecting said independent beams so as to maintain a, definite relationship between said image recording and said image translation.

10. Anintelligence transmitter comprising means for developing a plurality of independent cathode ray beams, means for modulating one Lci said beams in accordance with intelligence tc be transmitted, meansfor accelerating each of said beams, means for deecting each of said beams, a plurality of individual screens containing discrete capacitive elements, a conductor ad-` jacent each screen and common to the capacitor elements thereof, said conductor being adapted to l so as to divide the complete intelligence pattern into groups of signals.

l1. An intelligence transmitter comprising means ior developing a plurality of independent cathode ray beams, means for modulating at least one oi said beams in accordance with intelligence to be transmitted, means for accelerating each of said beams, means for deecting each of said beams, a plurality ci individual screens containing discrete capacitive elements coated with a material having a high secondary emission characteristic, a conductor adjacent eacb screen and common to the capacitor element-s thereof, said conductor being adapted to be maintained substantially at anode potential, and means for simultaneously defiecting,r said independent beams so as to maintain a definite relationship between said image recording and said `image translation.

l2. An intelligence transmitter comprising means for developing a pair of independent cathode ray beams, means for modulating at least one of said beams in accordance with intelligence to be transmitted, means for accelerating each of -said beams, means for deflecting each of said beams, a pair of individual screens each containing a plurality of discrete conducting elements `insulated each from the other, said screens bethe elliptical shape of thev screens and to maintain a definite phase relationship between said independent beams.

FRI'IZ SCmOI'ER.

Images