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Publication numberUS2036532 A
Publication typeGrant
Publication date7 Apr 1936
Filing date18 Nov 1929
Priority date12 Dec 1928
Publication numberUS 2036532 A, US 2036532A, US-A-2036532, US2036532 A, US2036532A
InventorsCarl Stoerk, Ludwig Schiff, Max Knoll
Original AssigneeKnoll, Schiff
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Cathode-ray-oscillograph
US 2036532 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

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M. KNQLL Er AL CATHODE RAY OSCILLOGRAPH Filed NOV. 18, 1929 s sheets-sheet 2 Patented Apr. 7, 1936 UNITED STATES 'CATHODE-RAY-OSCILLOGRAPH Max Knoll, Berlin-Lichterfelde, Ludwig Schiff,

Berlin, and Carl Stoerk, Berlin-Neukolln, Germany; said Stoerk assignor to said -Knoll and said Schiil' Application November 18, 1929, Serial No. 408,006 In Germany December 12, 1928 14 Claims. (C1. Z50-27.5)

'I'his invention relates to cathode-ray oscillographs. We may explain in general what cathode-ray cscillograph is.

A beam of electrons ejected from the cathode of a vacuum tube can, by various known methods (e. g. curvature of cathode surface, magnetic fields, or by ionic methods) be made to converge lnto a focus. The beam can also, by means of the effect exercised by electrostatic or mag- :u netic elds, be deflected in a direction perpendicular to the line of its path, and the focal point be made to describe a corresponding path on a surface perpendicular to the beam.

The electrons being without mass, and there l5 being no inertia to be overcome in their deflection, the velocity at which their deflection can take place, and consequently the recording-speed of 'the focal point, is practically unlimited.

On the other hand, owing to the fact that the 20 entire rays of a beam of cathode-rays are united in the focal point, the effect produced is sufcient, however extraordinarily high the recordingvelocity of the focal point, for instance to render the path of the point visible, to fix it photographi- 25 cally, or, by means of the charge conveyed by the electrons, to cause rushes of current, and so on.

The tubes which serve thus for the production of cathode-rays, for focussing them at a point, for moving the point, and for controlling the movement of the point, are termed cathode-ray oscillographs.

Cathode-ray oscillographs have found most varied and fruitful application not only for scientie, but also for practical purposes. 'Ihe effect :i5 of the cathode rays produced along the path of their focus can be utilized in various Ways. For instance, the energy of the rays may be transmuted partly into light-energy on a continuous fluorescent surface, and their path be thus made l.) directly visible to the eye; the path may be recorded upon a sensitive strip-surface; or the electric charge conveyed by the ray electrons may be transferred to a number of electrodes scattered over the Writing-surface and the rushes of current thereby produced further utilized. Mutually independent relays may be set in action, for example, or the rushes of current be passed through photo-electric cells whose resistance varies according to exposure.

'I'he following are a few of the applications feasible, which will give some idea of the great technical significance of the oscillograph, and of the number and variety of the domains in which it may be successfully turned to account.

In the case of electric overhead transmissionlines, the oscillograph is the only kind practicable for investigating the influences exercised by atmospheric electricity e. g. lightning discharges, or the surges of current caused in such systems by suddenly switching on or off the current, which, though usually they last only from one-hundredthousandth to one-millionth of a second, often destroy transformers, switches, and cables. By moans of oscillogram records it is possible to ascertain with the utmost exactness the moment when the surge of current occurred, its course and its amplitude. On the basis of the observations made, measures may be taken to prevent damage tothe plant. If the records are registered on a constantly moving strip of film, no attendance of the apparatus is needed, and any perturbances are recorded automatically as they occur. It is also possible, by the generation of travelling waves, to observe separately the behaviour, during the extraordinarily short period of duration of the surge, of each single piece of apparatus composing the plant, such as transformers, switches, insulators, etc., and thus to gather valuable data for the proper construction of such apparatus.

If when periodical oscillations of the focus of the electronic beam are produced by an electric or magnetic field of definite frequency, a number of electrodes are arranged in the path described by the focal point, and connected with a conducting Wire serving to draw off the charge carried by the electrons, a corresponding higher frequency is set up in that conducting wire. 'I'he cathode-ray oscillograph can thus be utilized as a frequency converter.

The extraordinary facility with which the focal point may be guided and controlled, enabling it to describe quite easily, for instance, in onethousandth of a second, upon a surface 6 x 6 cm, a narrow zigzag 36 meters in length, correspond-A ing to a recording velocity of 36 kilometers per second, and further the possibility, even at nthis enormous speed, of obtaining the above-mentioned chemical and physical effects, render the cathode-ray oscillograph especially suitable for use for picture-telelgraphy and television, and equally well either for transmission or reception.

With cathode-ray cscillographs as hitherto employed it has been considered an essential requisite to let the focus work in a Vacuum tube.

This has involved great p-ractical diflculties. If i for instance an oscillogram had to be recorded photographlcally, the photographic plates had to be introduced into the vacuum and afterwards removed. Not only was this operation awkward to perform and accompanied by a loss of time,l

but the cathode-ray tube had to remain in connection with the air-pump, since it was necessary to destroy the vacuum after, and restore it before, every operation. To procure a continuous record, i. e. one of any considerable duration, upon a lengthy strip of film, was thus in practice extremely difficult.

These difficulties involved in the working of a ray focus in a vacuum have probably been the reason why the cathode-ray oscillograph has not been employed in the systems of picturetelegraphy and television hitherto put into practice, although it would appear to be predestined as just the device that pioture-telegraphy and television required.

The present invention consists in the fact, that the focus of the cathode-rays is made to work not within the vacuum tube, but outside it.

Means had already been devised for allowing the entire cathode-ray beam or a portion of the same pass through an aperture or egress through a window in the tube, in order to conduct scientific investigations as to the nature of electrons, or their physical and chemical influence upon various substances, and so on. In both cases however, the electrons exercised their effect only in their natural actual density, not however in concentrated form. The quantity of heat given off per unit of surface was thus comparatively small. Consequently, with such apparatus, operating as they did only with small electronic densities, the heat generated by which being dispersed was easily drawn off, and no difliculties occurred. At such small electronic densities, those physical and chemical effects which due to its power of focusing the ray-beam renders the cathode-ray oscillograph especially capable, cannot be obtained.

With cathode-ray oscillographs the rays assembled at the focal point had hitherto not been passed through such a window. This-despite the great and obvious inconveniences involved in working the cathode-ray focus inside the vacuum-is probably due to the following circumstances. On the one hand the window, through which the cathode-rays are to be allowed egress, must be kept extraordinarily minute in width. On the other hand, the path traversed by the cathode-rays outside the window must, owing to the strong dispersive action which promptly takes place, be of the shortest possible length. This means that the focus mast be moved practically within the plane of the window itself. The extremely intense effect generated by the focus, due to the highly concentrated density of the electrons, would thus swift'y burn or melt away and destroy the window. This destructive effect can, howeverand herein lies partly the basis of the invention-be prevented by the velocity of the recording operation made possible by the cathode-ray osciilograph, which is such, that no time is allowed at any point for the generation of heat in any apprecl able quantity.

It is further necessary, and the invention provides for this, to devise means to ensure that the focus, after the record has been made, is instantaneously and automatically diverted from the window.

The thin window, through which the cathoderays find egress, must be reinforced on the inside to enable it to withstand the excess of pressure from without; In the case of the abovementioned types of apparatus, for scientific purposes, means had already been devised. of reinforcing thewindow (the so-called Lenard window), for

instance with a hexagonal grid. In order to prevent this necessary reinforcement from having a detractive shading effect upon the beam, lt

. cathode-rays is enabled, by the means provided by this invention, to work outside the vacuum tube instead of within it, does away at one stroke with all the above-mentioned inconveniences hitherto imposed by the necessity of carrying on the operation in the vacuum. The affecting of photographic or fluorescent surfaces, fixed or moving record-strips, fluorescent screens, arrangements of electrodes and the like is vnow accomplished outside the vacuum in the atmospheric air. The working of the various parts of the apparatus, their observation and exchange can all be carried out without difficulty. As the vacuum does not require renewal when a record is taken or when a photographic surface is exchanged, the tube from the vacuum pump may in many cases be sealed off from the vacuum pump, thus permitting of extensive simplification of the whole apparatus required.

If the focus of the electronic beam has to affeet a fluorescent layer (for instance, in order to make visible records of oscillograms of rapid succession of occurrences or of telephotographs), the uorescent layer may be deposited directly on the narrow Window of egress and renewed as required; the luminous oscillogram or picture can be freely observed, without, as was previously the case, any partial absorption of the light or distortion of the picture being occasioned by the glass of the tube.

As 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. aluminium, 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 fine 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-Dump. 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 for X-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 of 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 ra.-

tio of the total area of the perforations or apentures of admission to the total area of the nonperforated non-permeable portion ofthe framework, has to be as great as possible. Further 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 difficulties. To make such perforated plates the present invention employs a process similar to that used in autotype printing for the making oi' the printing-blocks. As is known, it is possible, by means of stipplingprocess photography, to engrave upon a surface adjacently, at extraordinarily minute intervals, dots of any desired form-square, for instance, the ratio of the width of the dots to the Width of the lines of the network of clear spaces between the dots depending upon the degree of illumination oi the photographed surface, It is possible thus to cover a surface with an extremaly 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 of lines is imprinted or copied on to the plate, and the dot-surfaces etched through the plate. 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, paraffin), and a thin layer, e. g. of beryllium, iron, or silicium, deposited galvano-vplastically 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 outl 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 1/10,000 mm. So thin a foil would, unless by so uniting it with the grid, be extraordinarily diicult, 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 lms.

The focussing of the electron rays as required for the oscillograph according to the present 1nvention, can be eiected in the known manner, e. g. by magnetic elds. A new arrangement, especially convenient for the purpose in view, based on electrostatic effect, consists in fixing, at

'* certain intervals from one another, co-axially with, and symmetrically to, the electronic beam ejected by the cathode, pairs of electrodes of suitable form (e. g. alternately perforated metal cylinders with small, and washers with large, diameter), which are connected alternately with appropriate voltages. In this way there are produced divergent electric elds with a stress acting obliquely to the direction of the beam, in such a way as to compress the beam radially. If

the voltage is sufficiently high, one single pair, of electrodes may suffice to effect this concentra' tion. The divergent fields can be obtained by various types of electrode. If a controlling voltage is supplied to such a device, the intensity of the electrons in the beam, and thereby the intensity of the focal spot, can be varied without inertia. The especial advantages of this arrangement are: ease in construction and mounting, small weight, small dimensions, and avoidance of consumption of current.

In order to obtain a small focus, it is requisite thatthe electron rays be ejected from as small as possible a surface of the cathode, just as in an optical system the obtaining of a small focus is dependent upon the diameter of the source cf light. According to the invention, the electron rays are produced by autoelectronic discharge from a cold cathode in a high vacuum, by an eX traordinarilyhigh strength of electrical eld (e. g, one million volt/cm), being produced on the surface of the cathode. The most simple form oi arrangement of such a discharge-tube consists of a point with a very small radius of curvature as cathode, with an anode, for instance in the form of ahollow sphere, placed opposite to it at a short distance. Similar arrangements have already been proposed for X-ray tubes, but owing to the high intensity of current required with the more recent types of X-ray tube, have not yet been applied in practice. For cathode-ray oscillographs, however, the current therewith obtainable (amounting to about 0.001 amp.) is quite adequate. As the electron rays are emitted only from the outer end of the point, which has a diameter actually of only about 0.01 m/m, (i, e. only a triing fraction of those emitting surface which would exist, e. g. in the case of a hotcathode tube), the power of focussing the raybeam owing to such discharge-tubes, is extraordinarily great and increases the eiiiciency of the cathode-ray oscillograph considerably. With this arrangement the anode must be provided with a co-axial boring for. the passage of the electrons.

In many cases, e. g. for the photographic record of oscillograms or of pictures, it is well to be able to observe the path described by the focus of the electron rays on the window-surface, or to observe the oscillogram or photo itself while it is being recorded, in order to check the proper adjustment and functioning of the device. As the outer surface of the window is covered by the photographic plates, or-with a continuous recordby the photographic lm passing by, or by the shutter, the observation must take place from the inner side. The observation is rendered possible by'the foil being covered on its inner or outer side or on both sides with just a lm of luminescent layer. The observation can then take place in a customary manner through a glass side-window in the tube. If the luminescent layer is applied only on the outer side of the foil, the observation can be made through the foil, which, owing to its extreme thlnness is translucent or transparent. In some circumstances it may also suilce, instead of the foil to cover the grid with a luminescent substance.

The application of 'a phosphorescent layer,

especially on the outer side of the foil, oil'ers the further advantage, that the photographic eilect is i screens etc. in the evacuated vessel to be shifted and adjusted at will, these parts can be supported by pliable intermediate organs held in position to withstand the outer atmospheric pressure, e. g. elastic spring devices or membrances of metal, in such a manner as to allow free sliding or swinging movement.

Special means are provided in order to keep the focus-so long as it is not moving at its great recording 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 means 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 effect-ed by intercepting the electron rays instead of diverting them, i. e. by arranging in the path of the electronic rays a bored-through negatively charged stopping-electrede, the negative charge of which is led 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 oocurring phenomena, or for television purposes, the switching on or oi of the diverting or stopping device has to be eifected in an extraordinarily short space of time. e. g. in 6 sec. This problem may be solved by a purely electrical switching device with two stable positions oi' 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 electron-tube 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 deiiector tube) can at the same time be maintained at the same value, and its saturation-current made to iiow to 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 ol.' electron tubes. This must be effected by employing two different constant intensities of current. Thus only the one set oi 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 neighbouring branch are continually changing.

The cathode-ray oscillograph forming the subject o! this invention can be used in picturetelegraphy and television also in the transmitting station i'or scanning the picture to be transmitted, and further for frequency-multiplication ior secret telegraphy and the like by scanning separated electrodes arranged chess-boardwise 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 offers a number of such important advantages as to enable both these operations to be carried out with hitherto unattainable perfection.

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

'I'he advantages of a constant recording speed have already been pointed out above.

The recording velocity obtainable is so great that e. g. a picture of 6x6 cm may easily be scanned in 1/1000 sec., or even in 1/10,000 sec., and reproduced with suflicient intensity.

If a picture-frequency of not more than 16 pictures per second (which is adequate for 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.

Picture-telegraphy can be extraordinarily cheapened and its field of application extended beyond all anticipation.

For instance, the transmitting of a. picture, which hitherto required about ten minutes, can be reduced to 1/1000 of a sec. An entire newssheet, for instance, can be swiftly transmitted by picture-telegraphy, provided only the sheets to be transmitted and the receiving film are moved with sufficient velocity.

Cinematographic illms can be copied by wireless transmission at any distance.

'I'he speed with which the pictures can be scanned in the transmitter and receiver makes it possible to scan, transmit, and reproduce in one continuous line pairs of stereoscopic pictures, so that either static or in process of production plastic picture-telegraphy and plastic television are made possible in the simplest manner by one and the same apparatus.

The extraordinary speed with which a picture can be scanned at the transmitting station and recorded at the reception station, and the possibility oi' extremely rapid withdrawal of the focus after 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 of pictures per second can easily be recorded, than has been possible with slow motion apparatus hitherto used.

If a very high number of pictures per second is to be obtained, it is, for instance, only necessary, rsty, in the receiving apparatus, to double the length of the picture, that is to say the sum of the intervals between all the branches oi the zig-zag path, so that with a stationary photographic plate one would obtain a distorted picture double the width; and secondly, to run the receiving iilm constantly at half speed. 'I'his gives the slow motion pictures, the optical compensation otherwise required being here replaced by the swift withdrawal of the focus.

The invention is exemplied in the drawings.

Fig. 1 shows schematically a cathode-ray oscillograph, such as can be employed for the various above mentioned purposes.

Fig. 2 shows on a larger scale-schematically drawnan example of the window of a cathoderay oscillograph used for the transmission of pictures or for television.

Fig. 3 shows a window of the same lsort in the receiving apparatus, for the photographic record of the wirelessly transmitted picture.

In Fig. 4 is schematically represented, how the cathode-ray tube of the transmitter and the cathode-ray tube of the receiver work together in the pictureltelegraphy or television.

Fig. 5 shows on a larger scale a vacuumproof pliable device for shifting movable parts, such as, e. g., a deiiector plate.

Fig. 6 is the schematic representation of a tube for auto-electronic discharge with a cold cathode and supplied with electrostatic concentrating device.

Fig. '7 represents a thermionic cathode-ray tube with an intercepting electrode, the latter actuated by a tip-action electron-tube device.

Fig. 8 shows a connection scheme for the production of oscillations with linear variations of voltage, as used especially for televisional or picture-telegraphic apparatus.

Fig. 9 shows the wave-shape of the linear oscillations produced 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 I,.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. 'I'he coil 4 serves to concentrate the ray beam before it passes through the narrow aperture of the diaphragm 5 in to the actual diversion-chamber 1 and onto the electron-permeable window 6.

8, 8' are the deflector plates, which can be adjusted under a high vacuum with the help of elastic bodies 9 `or membranes I0 by means oi 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 (plate or film I4) is situated during the taking of the record in the shutter I3.

Fig. 2 shows on an enlarged scale in sectlon an example of a photoelectric-cell,arrangement for taking pictures. Close behind the electronpermeable window 6, which is also held by the grid 19, is situated the photo-electric plate 8|, which is subdivided by means of insulation-layers into as many small fields as picture-stippling points are desired. The small photo-electric cathodes of the plate 8i are then supplied successively with negative voltage by the electronic beam passing rapidly across them; the intensity of the current ilowing off over the common grid anode 92 and the amplier |06' (Fig. 4) is modiied then according to the resistance effective at any given moment dependent on the exposure of the cell in question. y

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

A simple method of transmitting pictures also consists in first copying the picture according to a certain process onto a metal plate in such a manner that denite conductivity-values at different points of the surface of the metal plate correspond to the varying intensities of light on different parts of the picture. The electronic beam passing through the electron-permeable window can excite directly fluctuations of current in the ampliiier |06' (Fig. 4) which serve to vary the intensity of the cathode-ray in the receiver.

A further possible method of application of the invention to picture-telegraphy consists e. g. in utilizing the travelling point of light produced outside the transmitter-tube on the uorescent screen over a system of lenses for scanning the picture to be transmitted and having the reected rays gathered up by one single large photo-electric cell.

Fig. 3 shows on an enlarged scale in section an example of the construction of an electronpermeable layer E for cathode-ray oscillographs with a. supporting grid 19 of metal strips placed edgewise. The electronic beam when not in use falls behind one of the aluminium blades 83; the X-rays then generated are screened off by a lead mantle 84. The oscillogram or picture appears on a uorescent layer fixed onto the exterior side of the electron-permeable foil 6. If photographic records have to be made, the light-sensitive lm or plate I4 is pressed closely onto the electronpermeable window 6 by means of the lightproof 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 9I. For sending and receiving there serve respectively the cathode-ray oscillographs 92 and 92 with hotcathode discharge devices 93' and 93 respectively, pairs of deflector-plates 94', 95', and 94, 95 and electron-permeable windows E' and 6. The pairs of deector 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. 'Ihe 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, and thereby the fusing of the window, is prevented. The electrons passing through the electron-permeable layer B' of the transmitter tube 92 fall upon a photo-electric cell of special construction |00, the photoelectrically active layer 8l of which is divided in a manner known per se into a large number of small separate areas (shown enlarged in Fig. 2). On the photo-electric layer there is formed by means TIS of lenses |0| a picture of the'object |02 to be reproduced, so that there falls upon each of the areas a definite, in general varying intensity of light. The illumination takes place through the wide-meshed grid 82, which serves as common anode for all the small photo-electric cells. The actual transmission is effected by means of the high-frequency transmitter |03, which is coupled directly with the transmitting antenna 9 I and in turn modulated by the oscillator |04 and |05' as well as by the fluctuations of the photo-electric cells 8| conducted by way of amplifier |05'. Both oscillators |04 and |05 produce. by means of a device known per se, represented in Fig. 8, oscillations with a time-proportional Voltage-variation of the Wave-shape sketched in Fig. 9. In this manner there is ensured, in contrast to what happens in the case of the sinusoidal oscillations frequently used for such purposes, a precisely timeproportional scanning of the picture to be transmitted.

The transmission of a picture from the transmitter to the receiver takes place in the following manner:

Oscillator |05' produces continuously oscillations of a definite frequency, about 105 per sec., which affect the pair of plates 95' of the transmitter tube 92', and are transmitted by way of the high-frequency transmitter |03, the transmitting antenna 9|', the receiving antenna 9| and the selective amplifier |05 to the pair of plates 95 o'f the receiver tube 92. When oscillator |05 is alone working, the oscillations of the electronic beam describe a stationary line equal to the height of the picture to be transmitted, both in the transmitter tube and receiver tube.

If now the oscillator |04 is also switched on (frequency about 103 per sec), which aects the second pair of deflector plates 94' standing at right angles to 95' of the transmitter tube, these oscillations are transmitted by way of the same path as those from oscillator |05', through a selective amplifier I 04,to the pair of deectorplates 94 of the receiver tube 92, and the original line is once again transformed into a progressive zigzag record. If the frequency of the oscillator |04' is properly adjusted, the record produced has the width of the picture transmitted. If in addition the width of the oscillator I 05' is not greater than about the Width of the line described by the focus spot, each point of the picture being transmitted, both in the transmitter tube and in the receiver tube, is scanned simultaneously and for an equal period by the cathode-ray beam.

The interception 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 electrontube device similar to that represented in Fig. '1, which is controlled by means of the oscillator I 04 and theV amplifier |04. As the cathode ray beam on its way through the transmitter tube 92' meets with varying degrees of resistance according to theconductivity of the photo-electric cell with which it happens to be in contact, fluctuations of current take place corresponding to the occurring differences of intensity. These fiuctuations are transmitted by way of the amplifier |06', the high frequency transmitter |03', the transmitting antenna 9|', the receiving antenna 9|, and a selective amplifier |06, onto the control grid I1 of the receiver tube 92, there giving rise to corresponding fiuctuations of the beam-intensity, which in turn cause the requisite fiuctuations in intensity of the picture reproduced on the fluorescent screen 0.

'I'he arrangement schematically represented in Fig. 4-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. If the windows 9' and 0 are made so long in one direction, e. g. in a direction perpendicular to the plane of the drawings, that both stereoscopic pictures in the transmitting apparatus can be scanned adjacently and adiacently reproduced in the receiver, then'both pictures are scanned by the focal spot in one continuous line in each of both apparatus. The stereoscopic transmission of pictures and stereoscopic television are thus realized.

In Fig. 5 is exemplified 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 electrostatic defiector-plate 8, by means of the pliable metal body 9 actuated by nut |01, pressing upon the carrier-bush 24. 'I'his is joined by means of three screws 25, sliding in slots of the jacket 26, with the guide-ring 21, into which, by means of an insulating Washer 29,'e. g. of Bakelite, is fixed the supporting rod 28 of the deflector plate 9. The pliable body 9 is joined in a vacuum-tight manner at both ends withv its guide-rings, and likewise the insulating washer 29 with guide-ring 21; furthermore the supporting rod 29 is guided by another perforated insulating washer 30. The ring 3| carrying washer 30 is fixed directly into the jacket 'I of the cathode-ray tube. l

The tube 32 for auto-electronic discharge shown in Fig. 6 contains an anode 33 and an intercepting electrode (auxiliary anode) 34 which during the release of the beam functions as an anode. The release is effected by two spark gaps or glow-lamps 35 and 36, connected by way of windings 31. 39 with the perforated intercepting electrode 34 and by way of a high resistance element 39 with the cold cathode 40. The high-tension continuous current required for feeding the tube is generated in the known manner by means of transformer 4|, valve 42, and condenser 43. If the gaps 35 and 36 are properly adjusted, any sudden surge of voltage arising from the transmission line orantenna 44 and inducted from the winding 45 according to the polarity of the surge, either onto the winding 31 or 38, causes a sparking of the gap 35 or 38, the duration of which depends upon the value of the capacity 46 and the resistance 41. By this the electrode 34, which has hitherto intercepted the beam, becomes an anode, and the extremely sharp point of the cathode elects an electronic beam through the perforations in the electrodes 34 and 33, the intensity of the beam can further be varied by means of the controlling electrode 33 by varying the angle of the cone-shaped electronic beam.

In the lower part of Fig. 6 is shown schematically an electrostatic device for concentrating the electronic beam. It consists of cylindrical metal tubes 49, sustained by supports 49 in such a position as to allow of the electronic beam passing freely through it, and of the metal ring washers 50 between the tubes 48. If the washers 50 are charged negatively to the tubes 48, divergent electric fields are formed, which exercise a force concentrating radially the beam. Thus an exceptionally minute focal spot is obtained.

The beam focusing arrangement described above and shown in the drawings for the sake of a complete disclosure is not claimed herein but forms the subject matter of, and is claimed in the copending application'of Max Knoll, Serial No. 5,136, filed February 5, 1935 for Cathode-ray oscillographs.

'I'he thermionic cathode-ray tube 5| shown in Fig. 7, is provided with hot cathode 52, anode 53 and ,control-grid 54 controlling the intensity of the electrons in the beam while the latter is working. In order to prevent the fusing of the 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 connected on the one hand by way of resistances 59 and 60 with the positive pole of a storage battery, and on the other hand crosswise by way of condensers 6|, 62 with the grids of the tubes 56 and 51. By means of a battery 63, which by way of the high resistances 64, 65 keeps the condenser 6I charged, the grid potential of the tube 56 is kept 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. If the grid of the tube 51 Which 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. The 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, and the cathode-ray beam is released. If the surges issuing from the antenna or line 66 are positive, the tube 58 acts in the same manner. By means of resistance 10, the time of the tipping-over of the device into the position of equilibrium corresponding to the period of interception of the cathode-ray beam may be adjusted at will, thus enabling the release to be maintained for any length of time desired.

Fig. 8 refers to a device suitable for the production of oscillations with linear variation of voltage, such as is provided for oscillators |04' and in Fig. 4. In Fig. 8, 1I and 1.I are triodevalves, fed by the batteries 12 and 12. By the saturation-current of these valves` the condenser 13 is alternately charged and discharged by way of the resistances 14 and 14. The charging and discharging is automatically controlled by the grids 16 or 16', the potential of which is maintained at a suitable level by means of batteries 15 and 15. By varying the capacity of the condenser 13, the required frequency may easily and swiftly be obtained when working.

If the saturation-currents of the valves 1| and 1 I are selected at various values, or the resistances 14 and 14' are given different resistivities, the upward branches 11 of the oscillations taking place proportionally with the time (see Fig. 9) become less steep than the downward branches 18, whereby both in the transmitter and in the receiver the eilect of the downward branches is diminished in comparison with that of the upward branches.

If the batteries 15 and 15 shown in the conncctiomscheme Fig. 8 and their connections are omitted, the grid 15 joined with the hot cathode of its tube, and the grid 16 affected by the voltage of a control of the cathode-ray oscillograph, e. g. by the Voltage of the oscillator 105' shown in Fig. 4, then a positive dependence is obtained of the control voltage |04' upon the Voltage of the control |05'. That is to say, the lengthwise return of the focal spot occurs always after a definite number of transverse oscillations.

We claim:

1. A cathode-ray oscillograph comprising, a bathode for producing a beam of electron-rays, a beam focusing member for bringing the rays to a focus, deflecting means to deflect the said focus sideways in lione direction, another deilecting means to deect the said focus transversely to the said direction, an electron-permeable window lying in the vicinity of the area in which the said focus is designed to move during its deflection in the said two directions, and means to automatically prevent the rays from striking the said electron-permeable window while one of the said focus deecting means is ineffective to maintain motion of the focus over the window.

2. A cathode-ray oscillograph according to claim 1, in combination with an adjusting means for the deilecting means within the vacuum, consisting in an elastic closure element supporting the deiiecting means.

3. A cathode-ray oscillograph according to claim 1, the said window being supported by a grid in the form of a plate having a plurality of small holes adapted to lie substantially in the focal spot of the beam.

4. A cathode-ray oscillograph according to claim 1, the said window being supported by a grid, the said grid comprising flat metal strips fixed edgewise against the window and forming with the window, at all points of contact with the window, diierent angles corresponding to the angles of. incidence of the electronic rays at said points of contact.

5. A cathode-ray oscillograph according to claim 1, the said window being supported by a grid consisting of a thin foil deposited directly on the outer surface of the said grid.

6. A cathode-ray oscillograph according to claim 1 in combination with electrodes in front of the window and outside thereof.

7. A cathode-ray oscillograph according to claim 1 in combination with a uorescent layer on the inside of the window.

8. A cathode-ray oscillograph according to claim 1, the said means to automatically prevent the rays from striking the window comprises a device for deiiecting the electron-rays by means of electrostatic forces while the focal spot is at rest.

9. A cathode-ray oscillograph according to claim 1, the said means to automatically prevent the rays from striking the window comprising a device for defiecting the electron-rays by means of magnetic forces.

10. A cathode-ray oscillograph comprising an electron-beam receiving member, a cathode for producing a beam of electrons, means for bringing the beam to a focus at the receiving member, beam deflecting means operable in response to electrical Variations to effect movement of the focus of the beam over the receiving member. and means to automatically prevent the beam from striking the receiving member while the said deflecting means is ineffective to maintain motion of the focus, comprising means for deflecting the beam beyond one edge of the receiving member, and a plate of material of low atomic weight juxtaposed to the edge of the receiving member to receive the beam when so deected.

11. A cathode-ray oscillograph comprising an electron-beam receiving member, a cathode for producing a beam of electrons, means for bringing the beam to a focus at the receiving member, beam deflecting means operable in response to electrical variations to effect movement of the focus of the beam over the receiving member, and means to automatically prevent the beam from striking the receiving member while the said deecting means is ineffective to maintain motion of the focus, comprising means for deilecting the beam beyond one edge of the receiving member, a plate of material of low atomic weight juxtaposed to the edge of the receiving member to receive the beam when sol deected, and a screening mantle for said plate composed of material of high atomic weight.

12. A cathode-ray oscillograph comprising in combination, a cathode for producing a beam of electron-rays, a beam focusing member for bringing the rays to a focus, an electron beam receiving member lying in the path of the beam, deecting means for moving the focus sideways uninterruptedly from side to side of the said receiving member, another deecting means for moving the said focus transversely to the said one direction uninterruptedly from end to end of the receiving member whereby the two deiecting means are capable of moving the focus over substantially the entire area of the receiving member, and means to automatically prevent the rays from striking the receiving member while one of said deilecting means is ineiective to maintain motion of the beam over the receiving member.

13. A cathode-ray oscillograph as claimed in claim 12 in combination with a iluorescent layer on the inside of the electron beam receiving member.

14. A cathode-ray oscillograph as claimed in claim 12 in which the said means to automatically prevent the rays from striking the electron beam receiving member comprises a device for deflecting the electron rays by means of electrostatic forces while the focal spot is at rest.

MAX KNOLL. LUDWIG SCHIFF. CARL STOERK.

I DISCLAIMER 2,036,532.-Ma Knoll, Berlin-Lichterfelde, Ludwig Schei, Berlin, and Carl Stoer/c,

Berln-Neukolln, Germany. CATHODE-RAY-OSCILLOGRAPH.

Patent dated April 7, 1936. Disclaimer filed February 13, 1939, by the patentees.

Hereby disclaim claim 12 as it appears in the patent exce l pt as 1t aiects clalm 14 which latter 1s appendant to clalm 12, and also d1sclaim from the patent claim 13.

[Oficial Gazette March 21, 1.939.]

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2424788 *1 Dec 194229 Jul 1947Gen ElectricElectron microscope
US2439504 *6 Mar 194513 Apr 1948Emi LtdFlat beam cathode-ray tube and circuit
US2489155 *30 Dec 194422 Nov 1949Allis Chalmcrs Mfg CompanyElectric control circuit
US2525832 *20 Feb 194617 Oct 1950Emanuel Sheldon EdwardTube with composite photocathode for conversion and intensification of x-ray images
US2533713 *27 May 194712 Dec 1950Eitel Mccullough IncVacuum condenser
US2536035 *12 Dec 19392 Jan 1951Cleeton Claud EMeans for producing a variable number of pulses
US2575726 *30 Jul 194920 Nov 1951Sprague Electric CoHermetically sealed adjustable device
US2577628 *27 Feb 19474 Dec 1951CsfTelevision system
US2610245 *18 Feb 19469 Sep 1952Rines Robert HElectret array sensitive to radio waves
US2802106 *14 Nov 19456 Aug 1957Page Robert MSignal converter system
US2839602 *9 Oct 195117 Jun 1958Julius Cato Vredenburg InglesbMethod of and apparatus for recording pictures
US3801848 *30 Aug 19712 Apr 1974Philips CorpTelevision camera tube with mounting assembly for grid adjacent photoconductor
Classifications
U.S. Classification315/379, 315/382.1, 327/600, 313/231.1, 348/844, 347/231, 347/230, 315/30, 313/147, 331/143
International ClassificationH01J35/18, H01J35/00, H01J29/06, H01J31/12
Cooperative ClassificationH01J31/121, H01J35/18, H01J29/06
European ClassificationH01J29/06, H01J35/18, H01J31/12B