US2263733A - Cathode ray oscillograph - Google Patents

Description

Nov. 25, 1941.l M. KNoLL 2,263,733

' CATHODE RAY OSCILLOGRAPH Original Filed Nov. 18,"1929 3 Sheets-'Sheet l INVENTOR.

` l Max Kwon. P165 A TTORNEY.

Nov. 25, 1941. M.\KN0L|.

v CATHODE RAY oscILLoGRAPH 3 Sheets-Sheet 2 INVENTOR. Max KNOLL .am .LEE 5%8 w A TTORNE Y.

Nov. 25, 1941. M. KNoLL CATHODE RAY bscILLoGRAPH 3 Sheets-Sheet 3 ATTORNEY.

Patented Nov. 25, 1941 oArnoDE RAY osoILLoGRAPH Max Knoll, Berlin-Charlottenburg,

Germany,

assignor to Radio Corporation of America, New York, N. Y., a corporation of Delaware Application February 5, 1935, Serial No. 5,136, now Patent No. 2,152,487, dated March 28, 1939, which is a division of application Serial No. 408,006, November 18, 1929, now Patent No. 2,036,532, dated April 7, 1936. Divided and this application February 25, 1939, Serial No. 258,528

(Cl. P18-7.2)

6 Claims.

This invention has for its object improvements in cathode-ray oscillographs, and is a division of my copending application,lSerial No.

5,136, led February 5, 1935, which issued as Patent No. 2,152,487 on March 28, 1939, and which was a divisional application of Patent No. 2,036,532, which issued April 7, 1936.

According to the invention special means are provided in order to keep the focus, so long as it is not moving at its great recording or scanning speed, diverted from the window or other electron beam receiving member. This may be `effected in a manner known per se, by diverting the electronic rays sideways by Vmeans of a constant magnetic or purely electrical eld, or a combination of both. Preferably a plate of beryllium or other substance of low atomic weight may be arranged, against which the rays strike during their diversion, in order to prevent as much as possible the generation of X-rays.

`For the further protection of the observer and of the photographic layer against X-rays this plate is in turn covered with an envelope of material of high atomic Weight, e. g. lead.

`According to the invention the protection of the window may be effected by intercepting the electron rays instead of diverting them, i. e. by arranging in the path of the electronic rays a beam intercepting means in the form of a boredthrough negatively charged stopping-electrode, the negative charge of which is let off at the beginning of the recording operation. As the cathode-ray oscillograph which is the subject of the invention is intended to be used for rendering visible or recording extraordinarily rapidly occurring phenomena, or for television purposes, the switching on or o of the diverting or stopping device has to be eifeeted in an extraordinarily short space of time, e. g. in 10-6 sec. 'Ihis problem may be solved by a purely electrical switching device with two stable positions of equilibrium, e. g. by the employment of electron tubes, glow-lamps or spark gaps. The invention provides for .this purpose a specially simple and, rapidly reacting electrontube device, which is actuated simultaneously with the start of the voltage to be recorded by the oscillograph. In this .way the voltage of the grid-potential of another valve (the so called dei-lector" tube) can at the same time be maintained at the same value, and its saturation current made to ow through a condenser connected in parallel with the controls, the voltage of which is thus varied proportionally with the time.,

With apparatus for picture-telegraphy or television in which the whole area of the picture both in transmitter and receiver is scanned by the focal spot in a zig-zag path consisting of upward and downward straight-line branches, one set of branches, say the upward, can be described at a constant relatively slow velocity, and the other set, the downward, at a constant relatively high velocity by suitably varying the control voltage, as by charging or discharging inserted condensers by means of a constant current, e. g. the saturation current of electron tubes. This must be eifectedby employing two different constant intensities of current. Thus only the one set of parallel branches is Valid for the chemical and physical effects, in contrast to the hitherto used sinusoidal records, in which, on each of both branches, the recording velocity and the distance from the neighboring branch are continually changing( The cathode-ray oscillograph forming the subject of this invention can be used in picturetelegraphy and television and also in the transmitting station for scanning the picture to be transmitted, and further for frequency multiplication for secret telegraphy and the like by scanning separated electrodes arranged in checker board fashion behind the window and easily exchangeable.

Since neither for transmission nor reception need any mechanical parts be moved, the new -cathode-ray oscillograph, especially for picturetelegraphy and television olers a number of such important advantages as to enable both these operations to be carried out with hitherto unattainable perfection.

The synchronization which must be maintained between transmitting and receiving apparatus, is obtained with the utmost ease and with absolute exactitude by simultaneously affecting the corresponding controls of the transmitter and the receiver by the voltage either directly by wire, or indirectly by wireless waves.

The recording velocity obtainable is so great that e. g. a picture of 6 x 6 cm. Ymay veasily be scanned in 1/1000 sec., or even in 1/10000 sec., and reproduced with suicient intensity. V i

If a picture-frequency of not-more than 16 pictures per second (which is adequate forf the human eye) is required, pictures of such intensity may be obtained, that they may be projected on a much enlarged scale on to a screen and made visible to a large company of spectators. A

Cinematographic lms can be copiedY by 'vvir'eless transmission at any distance.

The speed with which the pictures canbe scanned in the transmitter andreceiver makes it possible to scan, transmit, and reproduce in one continuous line pairs of stereoscopic pictures, so that either static 'or in-proces's-of-production plastic picture-telegraphy Yand plastic television are made possible in the simplest manner by one and the same apparatus.

The extraordinary speed with vwhich a picture can-be scanned at the transmitting ystation and recorded -atl thev reception station, and the possibili-tyl ofextremely rapid withdrawal of the -focusafter the -picture has been completely scanned; enable also the transmitting and reception devices to be used for super-speed recording of. slow motion pictures, in which case a much-greater number Aof pictures per second Acan easily be recorded, than has been possible with slow-motion apparatus hitherto used. If a very high number of picturesper second is to be obtained', it is, for'instance, only necessary, firstly,l in the receiving appartaus, to double the length of the' picture, that is to say the sum of the intervals between all the branches of the zigzag'pathyso that with a stationary photographic plate one would obtain a distorted picturedouble the width; and secondly, to run the receiving lm ,o

constantly at half speed. This gives the slow motion pictures,I the optical compensation otherlWiseTequired being here` replaced by the Yswift withdrawal of the focus.

The-invention is exemplied in the drawings.

Fig. 1 shows schematically a cathode-ray oscil- .log'raph; such as can be employed for the various above `mentioned purposes.

Fig. 2 shows on a larger Yscale'-"schematically drawn-an example of the window ofa cathode- A'ray oscillograph 'used for the transmission' of pictures-or for'televi'sion.

Figi 3 'shows a window ofthe same sort inthe receiving apparatus, for the photographic Arecord of the wirelessly transmitted picture.

Fig. 4 shows schematically, lhow `the'cathode'- ray tube of the transmitter'and the cathode-ray 'tube of the'receiver work together in picture telegraphy or television. Y

Fig. 5 shows'ona larger scale a vacuum-proof pliable device for shifting movable parts, such as,

duction vofoscillations with -linear variations of n voltage-as used especially for televisional or picture telegraphicI apparatus.Y

Fig. 9 shows the wave-shape of the linear oscillations prduced by means of such a connection.

In the cathode-ray oscillograph represented` in Fig. 1 the cathode-ray beam is produced in the metallic discharge-tube l, which serves at the same time as an anode, and into which the cathode 2 is introduced by means of the bushing 3. The cathode 2 is connected with'the feed-voltage by means of the rod 3 lodged in the bushing 3. The coil 4 serves to concentrate the ray beam before it passes through the narrow aperture of the diaphragm 5 into the actual diversionchamber 1 and onto the electron-permeable window 6.

Asl electron-permeable substances the same materials may in general be used as were formerly employed for the Lenard tubes already mentioned. These are, first of all thin metal foils, e. g., aluminiurn, chromium-nickel, steel alloys, beryllium. Also-foils of insulating material, Celluloid, Cellophane, cellulose products, etc. may be used. Porous materials, such as paper, can also be used the pores of which are just ne enough to oppose to the passage of gases a relatively high, and to that of electrons a relatively low, resistance. In the -latter event the slight quantity of gas admitted through the pores must of course be constantly drawn off by an air-pump. Owing to their comparatively low atomic weight, glasses may also be used, especially such with components of particularly low atomic weight, as for example the Lindemann glass so often employed 'forrX-ray tubes, consisting of beryllium, lithium and boron.

In general it will be necessary to reinforce the thin foil required for the purpose described by a framework to sustain the outer atmospheric pressure. This-framework may, for instance, consist of a Wire-netting, which may in its turn be reinforced by means ol" a bearing cross, supporting grid or the like. For the reinforcement of -the foil it is possible also to employ a thin metal plate `perforated plentifully with small-holes. For the making of such a plate, appropriately perforated, a new process had to be devised. The purpose of the framework as employed in the invention is to make -it possible to use, for the window, foil of extremest thinness, in order thereby to insure that the window shall be permeable to the electrons to a corresponding maximum degree. Further, in the framework, the ratio of the total area of the perforations or apertures-of admission` to the total area of the non-perforated nonpermeable portion of the framework has to-be as great as possible. Furtherl also the apertures-of admission must lie as densely as possible together and be -of such small size, that the focal spot covers simultaneously several adjacent apertures.

The making of such plates involves special'diculties. To make such perforated plates the present invention employs a process similar to that used in autotype printing -ior the making of the printing-blocks. As is known, it is possible, by means of stippling-prccess photography,- to engrave upon a surface adjacentlyat extraordinarily minute intervals, dots of any desired form'-squar'e, for instance, the ratio of the Width of the dots to the width of-the lines of the networkof clear spaces between the dots depending upon `the degree of illumination ofl thephotographed surface. It is possible thus to cover a surface with an extremely dense network of dots of uniform size. Whereas, however in the making of a printing-block the network of lines is etched into the block, in making a perforated plate for-the purpose here in -view the network-o1" lines is imprinted or copied on tothe -plategv-and the dot-surfaces etched through the plate. A'The line-work can also be engraved into the plate, the

lines of engraving covered with a protecting layer,

and the dot-surfaces lying between the lines etched through the plate.

The thin foil forming the window can also, instead of being reinforced subsequently by the grid, be made directly upon the outer surface of the grid. For this purpose the holes of the perforated plate forming the grid can be lled in with a substance which may be later on removed (for instance, wax, parain), and a thin layer, e. g. of beryllium, iron, or silicum, deposited galvano-plastically or by cathode-sputtering over the entire outer surface of the plate. A thin layer of some acid-proof substance such as gold, for instance, can be deposited on the `plate previous to perforation and the holes then etched out in the manner already described. In this way are obtained an extraordinarily intimate vacuum-proof connection between foil and grid, perfect reinforcement, and `the maximum abduction of heat. The thickness of the foil can be reduced to as little as 1/1o,ooo mm. So thin a foil would, unless by so uniting it with the grid, be extraordinarily difficult, or practically impossible to mount. Windows made in this way are permeable to electrons to a degree hitherto never even remotely approachable; they are, further, owing to the effective abduction of the heat, not liable to be burnt through; they are easy to make and to use; and thanks to their perfectly plane form enable sharply dened photographs to be taken with ordinary plates or films.

8, 8 are the deflector plates, which can be adjusted under a high vacuum with the help of elastic bodies 9 or membranes I8 by means of Y screws II, which are lodged in supporting tubes I2. `I5 is a spy-hole, through which the oscillogram to be recorded can be observed also while the photographic record is being taken, provided that the inner side of the electron-permeable layer 6 or parts of the grid 19 are overlaid with a phosphorescent substance. The photographic layer V(plate or film I4) is situated during the taking of the record in the shutter I3.

Fig. 2 shows on an enlarged scale in section an example of a photoelectric-cell arrangement for taking pictures. Close behind the electron-permeable window 6, which is also held by the grid 19, is situated the photo-electric mosaic plate' 8l, which is subdivided by means of insulation-layers indicated in Fig. 2 by the short vertical lines, into as many small fields or photo-electric cathodes as picture-stippling points are desired. These small photo-electric cathodes forming the plate 8I are scanned successively by the electronic beam passing rapidly across them, with the result that a current of varying intensity flows through the cathodes to the common grid anode 82. VThus across each element is developed a potential having a value according to the resistance effective at any given moment dependent on the exposure of the cell in question. The developed potential between the anode 82 and ground is supplied to the amplifier |06' as shown in Fig. 4.

Instead of a photo-electric cell an exchangeable electrode arrangement of any desired formation can also be xed on the recording apparatus behind the electron-permeable window, enabling a definite succession of current impulses to be sent out for'whichthe receiving apparatus must be arranged accordingly.

A simple method of transmitting pictures also consists in rstcopying the picture according to a Vcertain process onto a metal plate in such a manner that definite conductivity-values at different points of the surface of the metal plate correspond to the varying intensities of light on dierent parts of the picture. For example, the picture on the metal plate may be a photographic reproduction in carbon or other` resistance substance, or a print made with resistance substance. Some forms of printing ink may havey sucient electrical resistance for the purpose. The electronic beam passing through the electron-permeable window and the resistance image to the plate can excite directly fluctuations of current in the ampliiier |96 (Fig. 4) which will serve to vary the intensity of the cathode-ray in the receiver.

A further possible method of application of the Ainvention to picture-telegraphy consists e. g. in

utilizing the travelling point of light produced outside the transmitter-tube on the fluorescent screen over a system of lenses for scanning the picture to be transmitted and having the reflected rays gathered up by one single large photoelectric cell.

Fig. 3 shows on an enlarged scale in section an example of the construction of an electronpermeable layer 6 for cathode-ray oscillagraphs with a supporting grid 19 of metal strips placed edgewise. `The electronic beam when not in use falls behind one of the aluminum blades 83; the X-rays then generated are screened off by a lead mantle 84. The oscillogram or picture appears on a iiuorescent layer fixed onto the exterior side of the electron-permeable foil 6. If photographic records have to be made, the light sensitive film or plate I4 is pressed closely onto the electronpermeable window E by means of the light-proof shutter I3.

Fig. 4 shows an example of an arrangement for a cathode-ray oscillograph in accordance with the invention, applicable for picture telegraphy and television, a denoting the receiver arrangement, b the transmitter arrangement; both are, wireless transmission being pre-supposed, connected with each other by way of antennae 9| and 9|. For sending and receiving there serve respectively the cathode- ray oscillographs 92 and 92 with hot- cathode discharge devices 93 and 93 respectively, pairs of deflector plates 94', 95 and 94, 95 for producing a scanning movement of the cathode-ray beams of the respective oscillographs and electron- permeable windows 6 and 6. The pairs of deflector plates 94', 95', and 94, 95 respectively shown in the diagram for the sake of clearness as parallel lie in the actual apparatus in each tube in planes at right angles to each other. The feed voltage for the discharge tubes lies at points 91', 98', and 91, 98 respectively.

By means of intercepting- electrodes 99 and 99 respectively, arranged between the hot-cathodes in the tubes 93 and 93 respectively, and the corresponding anode 91 and 91, the generation of electronic-rays during the pauses in the scanning movement as controlled by plates 94 and thereby the fusing of the window, is prevented in a manner to be hereinafter described. The electrons passing through the electron permeable layer 6 of the transmitter tube 92 fall upon a photo-electric mosaic of known construction |90, the photo-electrically active layer 8I of which is divided in a manner known per se (for example, as disclosed in Patent No. 1,691,329 to Zworykin dated November 13, 1928, and e Patent No. 1,780,364 to Reynolds dated November 4, 1930), into a large number of small separate areas shown enlarged in Fig. 2. On the photo-electric `layer .thereis formedbyzmeans of lenses lll-liaocording tothe :known laws ofoptics, a picturelof the .object t0-2 :to be reproduced, fso that :there Ifallsvupon eachof :the areasa .definite,.in,gen

reralvarying intensity. of light. Theillumination of leach farea takes :place vthrough `the widemeshed Mgrid y82, which .serves .as commonanode :for all the small .photo-electric cells. VThe'actual transmission is effectedlby means Lof the .highlfrequency*transmitter1123, of. any known .or suitable form' `for multiple signal transmissiongas :for example thatdescribed 1in the Zworykin ypatent Y.above referred to, and provided with .a common transmitting antennae "9 and modulated in known manner by the oscillators |04 .and |05 .as well as by the `luctuationso'l the photo-electric cells/8| conducted .bywayofiamplier |86.

.Both oscillators |04 fandflilproduce, byfrneans .of :a'device known per se, and represented dia- -grammatically in Fig. 8, oscillations with a'timeproport-ional voltage-variation ofthe vwave-shape sketched inFig. 9. In th-is manner there istinsured, in contrast to what happensnzthe case -,pair of delector plates 95 of the transmitter tube 92', and are transmitted by way ofthe Yhighfrequency transmitter |03, the .transmitting antenna'S'l, the receiving antenna 9|,` and theselective amplifier |05 operating in known man- .,ner Vas for example the selective amplifier lil- 1| vof the Zworykin patent above referred to,xto the pairfof platesif95 of the receiver tube :92. When oscillator |05 is alone working, the scanning sweep or loscillations of the electronic beam describe a .stationary line-equal 'to the height of thepictureto be transmitted, both inthe trans- -mitter .tube and receiver tube.

vIf-now the `deilecting or. sweep circuit oscillator |04 is `falso switched on (frequency ,about 103 per sec.), which effects thesecondgpair yof'deflector plates :94' standing at right angles'to 95 of the transmitter tube, theseoscillations aare transmitted `by .way of the same `path as those from oscillator'l, through a selective ampli- 'er |94, tothe pair of deectcr plates-S4 of the receivertube 532 and the original line -isonce again, transformed into a progressive'zig-zag record. If the frequency of the :oscillator |-04.is properly adjusted, the record produced has the Width of the Apicture transmitted. If rin Iaddition the sweep of theoscillator |05 is not great- -er than about the height ofthe line described by the focus spot, each point of .the picture being transmitted, both in the transmitter tubeand in vthe receiver tube, is :scanned simultaneously and ffor'an equalV period by the cathode-ray beam.

Theinterception of the electronic beam when .not being used is here effected by means of the intercepting electrodes 99 and 99 respectively by way-of -a--not here shown-tip-action electron- .tube device similar to that represented in Fig. 7,

which is controlled by means of the :oscillator l |04 and the amplier |84 -which latter two elements produce the scanning movement ofthe beams. As the cathode-ray beam on its Yway through the transmitter tube 92' meets with varying `degrees of resistance according to the CII conductivity of .the photo-.electric-.cell with which 4it happens to befin contact, uctuations .of `current take `place .corresponding to the occurring differences of intensity. .These iuctuations are vtransmitted by Way of the amplier |06', `the yhigh :frequency transmitter |03', the transmitting ,antenna ;9|', the receiving antenna 9|,.and

a selecting amplifier |96, onto the control grid '|11 `of the receiver tube'92, .there giving lrise to corresponding iiuctuations of the beam-intensity, which in turn cause the requisite fluctuations in intensity of the picture reproduced on the fluorescent screen 6.

vThe arrangement schematically represented in Fig. vfi-both the transmitting and the reception apparatus-allows also in the simplest manner possible of transmitting stereoscopic pictures to any-,distance and likewise of stereoscopic television. .A .stereoscopic picture, as is well known, consists of a pair of-pictures side by side, representing respectively the right and left eye views of a scene or object. If the Window 6 :and 6 are made so long in one direction, e. g. ina direction perpendicular to the plane of the drawing, that a Ap-air of stereoscopic pictures can be scanned .adjacently and adjacently reproducedin the receiver, then both pictures may be scanned by the focal .spot in one continuous line in each of both apparatus. The stereoscopic transmission of pictures and stereoscopic television may be thus realized by simply transmitting as a single picture, apair of stereoscopic pictures side by side. The pair of stereoscopic pictures thus received side by side at the receiving station may be synthesized in known manner.

InFig. `5'is exemplied on -a larger scale the pliable device shown in Fig-.1 employed for shifting movable parts under a high vacuum. The

device here serves for the adjustment of the elec- Vtrostatic decctor-plate 8, by means of the pliable metal body V9 actuated by nut |01, pressing upon the carrier-bush 24. This vis joined by means of thr-ee screws 25, sliding in slots of the jacket 25,

with the guide-ring 2l, into which, lby means of an insulating washer 29, e. g. of Bakelite, is fixed `the supporting rod 28 of the deilector plate 8.

Then-pliable body 9 is joined in a vacuum-tight .manner at both ends with its guide-rings, and

likewise the insulating washer 29 with guide-ring 21; furthermore, the supporting rod 28 is guided by .another perforated insulating washer 30. The ring 3| `carrying washer -3EJ- is yixed directly into the jacket 1 of the cathode-ray tube.

yThe vtube 32 for auto-electronic discharge shown -in Fig. 6 containsan anode 33 andan intercepting electrode (auxiliary anode) 34 which during therelease of the `beam functions Ivas anvanode. The release is effected by two spark wardly therethrough, thus maintaining the condenser `43 charged-with the llower plate positive andthe upper plate negative. If the gaps 35 and .36 are properly adjusted, any sudden surge of voltage arising from the transmission line or antenna v44 andinducted from the .winding 45 according tothe .polarity of the surge, either onto the Iwinding 31 -or.38, .causes a sparking of `the gap 35 or 36, the dura-tion of which depends upon the value of the capacity 46 andthe resistance 41. By this the electrode 34, which has hitherto intercepted the beam, becomes an anode, and the extremely sharp point of the cathode 40 -ejects an electronic beam through the perforations in the electrodes 34 and 33, the intensity of the beam can further bevaried by means of the controlling electrode 33 by varying the angle of the coneshaped electronic beam. Y

In thelower part of Fig. 6 is shown schematicallyan electrostatic device forjconcentrating the electronic beam. It consists' of cylindrical metal tubes 48, sustained bysupports 49jin such a position asl to allow ofthe electronic beam passing freely through it, and of the metal ring washers 50 between the tubes 48. If the `washers 502 are charged negatively to the tubes 48,. divergentl electric fieldsl are formed, which exercise a force concentrating radially the beam. Thus an exceptionallyminute focal" spot is obtained. Adjustment of the voltage applied totheV tube and washer elements at the polarity indicated inthe diagram, and according to the spacing of the electron-permeable window will bring the' rays to a focus at the window, as will be understood by those skilled in-the a-rt.

The thermionic cathode-ray tube l shown in Fig.` '1, isprovided withthe hot cathode-52, anode 53, andcontrol-grid 54 controlling the intensity of the electronsv in the beam while 4the latter is working. In order to prevent thev fusing ofthe window during periods when the focal spot is at rest, an intercepting electrode 55 is provided, actuated by a tip-action electron-tube device. This'device consists" of the electron- tubes 56, 51, and 58, the anodes of which are connectedl on the one hand by way of resistances` 56 and 60 with the positive pole of a storage battery, and on the other hand-crosswise-by way ofcondensers 6|, 62 with the grids of the tubes 56 andl 51. Thusfar the circuit arrangement isquite similar to the `well known multivibrator circuit. However, in the present system thecircuit is; intended to function not as a multivibrator, 4but as a trigger or` tip-acting device for releasing the blocking charge on the intercepting electrode 55. This change in the function is accomplished by substituting for the usual grid leak between grid and cathode, a battery 63, which by way of the high resistances 64, 65 keeps the condenser 6| charged to the potential of the battery 63 and the grid potential of the tube 56 at a lower level than the anode potential of tube 51, the amount of the diminution being about the same as the anode potential itself so as to bring the said grid potential to zero or negative. The potential between the grid and filament of tube 56 will be the algebraic sum of the potential of the anode of the tube 51 and the battery 63. If the grid of the tube 51, which tube is fully emitting during the interception of the cathode-ray beam, is affected by a surge of negative voltage issuing from the antenna or transmission line 66 by way of the resistances 61 or 68, and by way of the condenser 69, the arrangement tips over into its other position of stable equilibrium. In that case tube 51 is blocked. IIhe grid potential of tube 56 and therewith that of the intercepting electrode, hitherto negative, now receive the same potential as hot cathode 52, or a potential positive to it due to the rise in potential across the terminals of tube 51, and the cathode-raybeam is released. If the surges issuing from the antenna or line 66 are positive, the tube 58 acts in the same manner.

By means'ofresistfance 16, theA time of the tip# ping-over of the device back into the position of equilibrium corresponding to the period of interception of thecathoderay beam maybe adjusted at will", thus enabling the releaseto bemaintained for any length ottime desired.

Fig. 8 refersto adevice suitable for the production of oscillations with linear variation of voltage, s uchhas' is provided' for thel oscillators |04 and |05' in Fig; In Fig. 8', 1l and 1|" are triode valves, fedl bythe batteriesy 12 and 12. By the saturationecurrent ofl these valves', the condenser 13'is alternately charged and discharged by way ofthe-resistances 1"4and 14. The charging and discharging is automatically controlled by the gridsA 16 and 16"', the potential of which is maintained at a suitable level by means of batteries 15 and15". Byvarying the capacity of the condenser 13, the; required frequency may easily and swiftly be obtainedwhen working.

If'the saturation-currents'of the valves 1'I and 1H are Wselected ait/various` values, or the resist'- ancesj14 and 14" are given diierentA resistivities, the upward branches' 11 of the' oscillations taking place proportionally with the time (see Fig. 9)' becomeless steep-than the downward branches 16', whereby'both4 in the transmitter and in the' receiver-the eiect` of the downward branches is diminished* in comparison with that of the. upward branches;

If the batteries 15l and 1.5 shown in the connection-scheme` Fig'. 8A and' their connections are omitted the gridl 16' joined' with the hot cathode' of its tube, and the grid' 16 effected by the voltagev of a control ofv the cathode-ray oscillograph, e'. g. bytliievoltage of the oscillator |65 showny in Fig; then to accumulate a definite charge aftera given number of impulses from theoscillator' I'05, apositive dependence is obtained of the control' voltage 1.04' upon the Voltage of" theu control |05".V That is to say,` the lengthwise return ofthev focal spot occurs always after adeiinite number of transverse oscillations.

1^. A transmission system comprising acathode ray oscillograph having meansto produce a beam of'A electrons, means" to deflect the beam of elec# trons, an electron permeable window lying in the path of said beam of electrons, means to direct the beam of electrons through said window, a picture area electrode behind said window outside of said oscillograph and immediately adjacent thereto, said electrode being adapted to be scanned by electrons passing through said window, means for deriving from said electrode electric potentials produced by the scanningelectrons which vary in accordance with the light and shades of the elemental areas of the picture area, a second cathode ray oscillograph having a focused beam of electrons, means to deiiect the focused beam of electrons of said second oscillograph synchronously with the deiiections of the beam of electrons of the first named oscillograph, and means to vary the intensity of the focused beam of electrons of said second oscillograph in accordance with the derived potentials from said picture area electrode.

2. A transmission system comprising a cathode ray oscilloscope having means to produce a beam of electrons, means to deect the beam of electrons, an electron permeable window lying in the path of said beam of electrons, means to direct the beam of electrons through said window, a light sensitive electrode behind said window outside of said oscilloscope and immediately adje,`

cent thereto, said electrode having a picture area and being adapted to be scanned "by electrons passing through said Window, andV means for deriving from said electrode electric potentials produced by the scanning electrons which vary in accordance with the lights and shades of the elemental areas of the picture area.

3. A transmission system comprising a cathode ray oscillograph having means to produce a beam of electrons, means to deflect the beam of electrons, an electron permeable Window lying in the path of said beam of electrons, means to direct the beam of electrons through said window, a metal plate electrode `having different conductivity values at different points corresponding to the varying lights land shades of a picture, said electrode being positioned behind said Window outside of said oscillograph and immediately adjacent thereto andfadapted to be scanned by electrons passing through said window, means for deriving from' said electrode electric potentials produced by the scanning. electrons. which vary in accordance .with the lights and shades of the points-of the picture, a second'cathode ray oscillograph having a focused beam of electrons, means to deflect the focused beam of electrons of said second oscillograph synchronously with the deiiections of the beam of electronsof the first named oscillograph, and means Vto vary the intensity of the focused beam of electrons of said second oscillographin accordance with the derived potentials of said metal plate electrode.

4. A transmission system comprising a cathode ray oscillograph, means to `produce a beam of electrons, an electron permeable Window lying in the path of said beam of electrons, means to direct the beam of electrons through said Window, means to deflect the beam of electrons over the area of said window, a plate having a picture formed of electrical responsive material on one surface of said electrode, said electrode beingr positioned behind said window outside of said oscillograph andimmediately adjacent thereto with the picture facing saidwindovv, said'picture being adapted to be scanned, by ffelectrons passing through said window, vmeans for deriving from said plate electricpotentials produced by the scanning electrons which vary in accordance with the lights and shades of the elemental areas of the picture, and an output circuit to receive the derived potentials.

5. A transmission system comprising a cathode ray oscillograph, means to produce a beam of electrons, an electron permeable Window lying in the path of said beam of electrons, means to direct the beam of electrons through said Window, means to deflect the beam of electrons over the area of said Window, aplate having a permanent image formed of electrical responsive material on one surface of said electrode, said electrode being positioned behind said Window outside of said oscillograph and immediately adjacent thereto with the permanent image facing said Window, said permanent image being adapted to be scanned by electrons passing through said window, means for deriving from said plate electric potentials produced by the scanning electrons which vary in accordance with the lights and shades of the elemental areas of the permanent image, and an output circuit to receive the derived potentials. Y

6. A transmission system comprising a cathode ray oscillograph, means to produce a beam of electrons, an electron permeable window lying in the path of said beam of electrons, means to direct the beam of electrons through said window, means to deiiect the beam of electrons over the area of said Window,.a plate having a predetermined optical image formed of electrical responsive material on one surface of said electrode, said electrode being positioned behind said window outside of said oscillograph and immediately adjacent thereto with the predetermined optical image facing said window, said predetermined optical image being adapted to be scanned by. electrons passing through said Window, means for deriving from said plate-V electric potentials produced by the scanning electrons which vary in accordance with the lights and shades of the elemental areas of the predetermined optical image, and an output circuit to receive the derived potentials. l Y y MAX KNOLL.'

Images