US2164922A - Cross field control tube - Google Patents

Description

y 1%9. H. E. HOLLMANN CROSS FIELD CONTROL TUBE Filed Dec. 3, 1936 aim alalalalalalal Mama INVENTOR HANS ERICH HOLLMANN Patented July 4, 1939 UNITE CROSS FIELD CONTROL TUBE tion of Germany Application December 3, 1936, Serial No. 114,003 In Germany December 3, 1935 5 Claims.

This invention relates to electron discharge devices, and more particularly to tubes of the electron beam type in which the beam is deflected by a transverse or cross control field.

The principal object of the invention is to provide a cross field control tube of the beam type which has a large output current and in which the entire emission of a filamentary or indirectly heated cathode may be utilized. Another object is to provide such a tube in which very high amplification may be obtained. Still another object is to provide a compact and symmetrical tube construction. A further object is to provide a tube of this type suitable for use in ultra short wave work.

In accordance with the invention, a new cross field control tube is so made that the electron beam is lenticular or in the form of a disc, at the center of which the cathode is situated. The new tube has the great advantage in accordance with this beam shape, that the entire electrode mounting becomes cylindrically or rotationally symmetrical and that very high amplification factors may be obtained. The disc-shaped or lenticular beam is produced by an annular cylindrical lens system coaxially arranged with respect to the cathode whereby the said beam is deflected by an annular cross field, or controlled transversally, and finally impinges on anodes likewise annular and which are loaded with any desired outer resistances. The rotationally symmetrical construction assures the utilization of the entire emission of the axial cathode in the disc-shaped beam, i. e. the concentric arrangement of all eieatrodes enables all the electrons leaving the cathode in different radial directions to be uniformly accelerated and concentrated, and furthermore, as in the case of modern amplifier tubes, a favorable symmetry of the system is assured during manufacture and during use. Finally, border disturbances unavoidable in case of the band-shaped beam are entirely eliminated by the disc beam which is closed on itself. The new tube can be built with a uniform disc-shaped beam and uniform annular electrodes in which case the beam is uniform throughout its entire peripheral extent, and becomes identical to two space charge tubes connected in push pull as regards its action, or the tube may be divided into several sector like individual tubes through radial or diametrical splitting of the entire structure, whereby the various individual tubes may have difierent functions assigned to them, or they may be connected in series or cascade.

In producing ultra-short wave oscillations with a tube of this construction, considerable disturbances may appear due to the comparatively high capacity of the annular deflection plates as well as due to the annular anodes which, for the pur pose of obtaining a suflicient deflection sensitivity, must be of comparatively large diameter. In trying, for instance, to make up a resonance circuit with the anode rings of rather large dimensions by connecting them to a short Lecher wire system or by joining them to a bent wire, then at the respective high frequencies the excitation conditions could not be the same over all the circumference of the cross field tube, since the annular electrodes as such represent a line with distributed capacity and induction, thus making quasi-stationary conditions impossible.

This disadvantage of the tube for ultra-short wave work is avoided in accordance with the invention by extending the rotational symmetrical structure of the cross field tube also to the excited resonance system in the plate circuits, so that the excitation conditions for this system are uniformly distributed over the entire circumference. To this end, the anode rings are connected to metallic hemispheres situated on the ends of the cathode axis, so that a resonance circuit is obtained having the shape of a hollow body with the disc-like ray taking its course in the center plane of said hollow bodied resonance circuit. The feed back is obtained in the simplest manner by galvanic connections in which the defiection rings are joined at several places to suitable points in the interior of the metal hemispheres and have applied tothem all or part of the oscillatory potentials.

Illustrative examples of cross field tubes made in accordance with the invention are shown in cross section in the accompanying drawing, in which Figure l is a longitudinal section along a vertical plane of one form of'tube; Figure 2 is a 40 cross-section along a horizontal plane of a modiflcation, and Figure 3 is a longitudinal section along a vertical plane of a form of tube suitable for ultra-short wave work.

As shown in Figure l, the tube comprises a highly evacuated envelope or bulb ill which encloses the electrodes and which has at the center a cathode ii, shown as of the indirectly heated type. The shape of the tube as a whole is that obtained by rotation of the cross section of Figure 1 about the cathode as an axis. About and concentric with this cathode are two pairs of annular beam forming electrodes of difierent diameters, such as a pair of metal rings M of equal diameters, and a second pair of rings '83, also of equal diameter, but larger than the rings 12, the adjacent edges of the rings of each pair being spaced to form two annular beam forming slots in registry. These pairs of annular beam forming or lens electrodes may be connected to be at dif ferent potentials so that the electrical field between them and the beam forming slots acts as an annular cylindrical lens, which concentrates the electron rays emitted by the cathode in all die rections, so that as a whole there is produced a disc-shaped beam which is lenticular orhas the form of a frustum of a double cone, such as indicated in cross-section in Figurev 1. At the point e! the intersection, or focal line of the radial elec-' tron rays, and in the median plane of the beam two annular anodes l4 and iiof equal diameter are mounted concentric with the cathode and spaced to leave a narrow slot it between their edges. Bysuitable adjustment of the lens electrode ,voltages the focal line of the electron beam or the circumference-of the symmetry, surface of the double cone beam may. be made to coincide with this slot Hi between the anodes.- In order to deflect the disc-shaped beam throughout its entire periphery toward one or the other anode deflection, or control rings I1 and I8 concentric with the cathode and in vertical alignment are disposed between the lens, electrodes and the anodes. Upon application of a potential difference between the rings l I and I8, for example through an input circuit I 9, there appears an annular cross field and in accordance with the direction of the latter, the disc-shaped beam will be deflected either towards anode M or towards anode l5 so that the electron current passes either to anode ll or to anode IS. The two anode rings may be loaded by any desired outer resistors 20 and may operate in push pull. In order to' at-v tain as great steepness of the characteristic as feasible, there will preferably be used on the one hand a deflection fleld with as high intensity'as feasible, 1. e. the radial width of the deflection rings will be chosen as large as possible, and their spacing will be adapted as much as possible to the shape of the disc-shaped beam while, on the other hand, the diameter of the anode rings will preferably be chosen just as large as the electron-optical focal distance of the cylinder lens system permits so as to obtain as large a geometrical ratio of movement of the beam to its circumference as feasible. Since the principle of the cross field control is applied to cathode ray tubes for television, and has been .suggested in various cases for use in amplifier-and-transmitter tubes, a further description of the functioning of the subject matter of the invention is unnecessary.

Figure 2 illustrates a modification of the invention utilizing a radial or diametrical division of the electrodes in such manner that two or severalssector-like cross ray tube systems are obtained in one bulb. This division need, of course, be made only in the deflection rings and the anode rings, while the cylindrical lens represented by the slots 'in the lens electrodes may remain a unit, or may be covered up at the most at the places of the radial separating gaps, so as to provide interspaces between the individual sector-like electron beams, whereby mutual influence is avoided- Such mutual influence will be completely suppressed, as indicated in Figure 2, if, in the separating spaces obtained in this way, radial sheet metal shields 2| extending lengthwise of the cathode and preferably connected to it are inserted. Obviously the individual cross field tubes thus produced are like individual tubes and may be used in various ways; for instance, one sector as transmitter, a second one as modulation stage, a third one or a still further one as preliminary amplifier, or a multiple stage receiver apparatus with high-frequency stages detector. and audio-frequency stages may be accommodated within a single multiple cross fleld tube. In this way a mixer tube can be obtained in which one sector is employed for the production of the intermediate frequency, and another one for the production of the local oscillation; if necessary, further sectors may be employed as preliminary or subsequently connected high-and-intermediate frequency amplifiers, or as second rectifier, etc.

The cascade-like series connection of such cross fleld tubes or of the individual sector stages of a multiple tube is considerably simplified as compared with ordinary space charge tubes in that no elements whatsoever for the blocking of the anode I voltagewith respect to the deflection plates are required. The anodes maybe connected directly with the deflection plates, or with segments of the following tube. In a cascade amplifier designed for sector-like individual stages the accommodation of the coupling resistors and coupling lines in the tube bulb is feasible and simple, as indicatedin Figure 2, where connections are made through load resistor 22 and condensers from one sector to the following sector, all the connections being inside the bulb.

In some uses it maybe advantageous in the rotation symmetrical cross field tube to insert between the cathode and the cylindrical lens a suitable control electrode, for instance in the form of a grid 23 in order to control the amperage of the beam. In this manner there is obtained very simply the possibility of modulating a cross fleld transmitter with stable frequency, or of voluntarily or automatically controlling a cross fleld amplifier. Furthermore, with such an arrangement all circuits can beset up which were hitherto shown with hexodes.

A modification of the invention suitable for use in ultra-short wave work is shown diagrammatically in Figure 3, showing in cross-section a practieal construction of a disc beam transmitter with hollow resonance system."- In this structure the indirectly heated cathode II is an axial metal tube or sleeve containing a heating coil and having its central part covered with an oxide layer which emits electrons. The electron rays are then con- .centrated in accordance with the invention by the annular ring-shaped cylindrical electron lens, thereby producing a disc beam with slightly triangular cross-section, as indicated in the figure.

The deflection rings [1 and I8, by means of the ring-shaped cross field appearing between them, deflect the disc beam at its entire circumference to the anodes l4 and IS on which the disc beam impinges, either against the one anode or against the other anode.

In this modification the anodes are not narrow rings, as in Figure 1, but the edges of metal cups 24 shown .as hemispheres in this modification.

The hemispheres are mounted on the axial cathode tube and are insulated from it by small cylindrical insulators 25 so as to withholdthe plate potential from the cathode, and together with the said cathode sleeve form the inductance of the resonance system excited in push-pull whose capacity is formed by the opposite edges of the metal cups 24. This capacity may, if desired, be

increased by radial flanges 26 on the anodes. It

'is obvious that in place of the hemispheres any Q,16d,QQ2 1 it other cup-like shape, such as for instance conicalor-cylindrical cups may be employed.

In order to obtain a feed back whereby self excitation is produced it is necessary, as is known, to return a part of the oscillation potentials obtained at the hemispheres tothe deflector rings H and I8. In the example described this is accomplished. by several short connection wires 2'! connected from suitable points in the interior of the hemispheres 2% to the deflection rings. For the production of ultra-short waves a cross connection of these feed back lines, which must then be led through the disc beam, is not necessary, since it is possible in case of static feed back with phase "reversal to adjust to positive values the phase balance through suitable choice of the electron transit time, i. e. the beam acceleration potential. The other operating conditions do not require further elucidation.

Fundamentally, the arrangement is suitable for an inductive feed back, for instance in accordance with the scheme of the known Huth- Kuehn circuit. To this end it is only necessary to connect to the deflection rings smaller spherical cups inside and concentric with the hemispheres 24 to establish a secondary system in the interior of the anode system. Since in this case some dimeulties may be encountered as regards the exact tuning of the two circuits, the simple conductive coupling is generally preferable.

I claim:

1. An electron discharge device comprising a straight electron emitting cathode, annular electron lens electrodes coaxial with said cathode to concentrate the discharge from said cathode into a focused lenticular beam transverse to said cathode, an annular anode comprising two rings coaxial with. said cathode and spaced to provide between their edges an annular slot having the same median plane as said beam and at substantially the focal line of said beam, and two annular control electrodes surrounding and concentric with said electron lens electrodes and spaced to provide between them an annular slot having the same median plane as said beam, each of said annular electrodes having extending through it a plurality of radial slots to divide each annular electrode into a plurality of arcs, said slots being in radial alignment to divide the electrode system into a plurality of sectors, each containing an arc of a control electrode and anarc of the anode.

2. An electron discharge device as defined in claim 1 in which a radially positioned metal sheet in each slot extends through said electrodes to electrostatically shield each sector from the adjacent sectors.

3. An electron discharge device as defined in claim 1 in which the electrode system is divided by radial slots into a plurality of sector stages and comprising connections inside the bulb connecting said sector stages in cascade.

4. An electron discharge device as defined in claim 1 in which the electrode system is divided by radial slots into a plurality of sector stages, and comprising a load resistor for one of said stages mounted inside the bulb and connected to the control electrode of another stage.

5. An electron discharge device as defined in claim 1 in which only the anode and the control electrodes are divided by radial slots into sectors,

and the beam forming electrodes are circumferentially continuous.

- HANS ERICI-I HO

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