US2197526A

US2197526A - Support for electrodes

Info

Publication number: US2197526A
Application number: US252912A
Authority: US
Inventors: Kosack Hans
Original assignee: Fides Gesellschaft fuer die Verwaltung und Verwertung von Gewerblichen Schutzrechten mbH
Current assignee: Fides Gesellschaft fuer die Verwaltung und Verwertung von Gewerblichen Schutzrechten mbH
Priority date: 1938-06-10
Filing date: 1939-01-26
Publication date: 1940-04-16
Anticipated expiration: 1957-04-16

Description

April 16, w H. KosAcK SUPPORT FOR ELECTRODES Filed Jan. 26, 1939 INVENTOR ///V' .KUS/767K.

ATTO N EY Patented Apr. A16, 1940 UNITED STATES 2,197,526 SUPPORT Fon ELEo'rRonEs Hans Kosack, Berlin-Steglitz', Germany, assignor to Fides Gesellschaft fr die Verwaltung und Verwertung von Gewerblichen Schutzrechten mit beschrnkter Haftung, Berlin,Germany, a corporation of Germany Application January 26, 1939, SerialNo. 252,912 In Germany June 10, 1938 13 Claims.

The invention relates to discharge tubes and especially to the support for the electrodes of such discharge tubes.

I An object oi the invention is to maintain a fr' iixed distance between the electrode elements, es-

peclaily of the cathode and control electrodes.

Another object of the invention is to provide a support for electrodes which will not substantially change in size and form under the influence l of high temperature.

Other objects and advantages of the invention will be apparent from the following description and drawing, in which:

Fig. 1 is a cross-section through a preferred support ior the cathode and control electrodes.

Figs. 2 and 4 are cross-sections of two modications oi the invention as disclosed in Fig. 1.

Fig. 3 is a perspective view of an element of Fig. 2.

Fig. 5 is a perspective view of the modification in Fig. i with additional elements.

Certain types of discharge tubes such as high vacuum amplifier tubes require extremely Small distances between individual electrodes, especially the distance between the cathode and the control grid. The practical maintaining of such small distances to a constant value is extremely dinicult in tubes of the prior art because such electrodes consist oi' two separate elements which are fixed' in their position relative to one another only at their ends. With such constructions, it is often impossible to maintain the desired narrowtolerances or such narrow tolerances are only accomplished at the cost of a great deal of time and trouble.

The invention provides a construction for the electrodes and electrode support in electric dischargetubes whereby the small electrode distances areuaccurately maintained and the manuiacturi'ng and assembly of the electrode arrangement is accomplished in a more certain manner.

In particular, a common support of insulating material is used for the two or more several electrodes which require small distances between 15 them. This common support of insulating material guarantees the accurate maintaining of the electrode distances at least over the effective length of the electrodes and practically over their entire length. This common insulating support is preferably of ceramic material which not only has high heat resistance but also will maintain practically its same size and form under the iniiuence of the high temperature constantly present in the tube during operation.

.55 In Fig, l, the support l is of ceramic material and acts as a common support for both the cathode and the grid. This common support in the preferred embodiment illustrated, has preferably two parallel extending surfaces 2 and 3 having the cathode 8 and 9 thereon. This cathode pref- 5 erably comprises a base vmetal coating sintered onto the ceramic material as a metal coating. Such a coating may be of platinum, nickel, copper, silver, or other suitable materials. The emitting material is placed on top o the metal coat- 10 ing and may comprise the familiar electron emitting barium, strontium and calcium oxide. ,The ceramic material has preferably prolongations i,

5, 6, and l at the corners lateral to the cathode surface. These

projections

4, 5, 4(i, and l are pref- 15 erably provided with grooves in which the grid wires are placed. If the grid wires are wound suificiently tight, an absolutely sure and xed distance between the cathode and grid is assured.

A Suitable heating element I0 is preferably cen-I 20 trally arranged within the ceramic support. This heating element may, of course, comprise the usual heating coil. The heat which is produced in the heating element should be conducted mainly to the emitting surfaces 8 and 9 of the cath- 25 ode. The portion of the ceramic Supportadjacent the projections for the grid wires has means therein which make diicult the conduction of heat through the ceramic body from the heating element to' the projections. The means, illus- 30 trated in Fig. 1 by which the heat conduction to the projections is, reduced, are the hollow spaces or cavities II and I2. Y

If several grids are required and accurate spacing is desired, the projections of the ceramic sup- 35 portmay have slots of diiierent depths therein. One wire may be wound in slots of one depth and another in slots of another depth. For grid wires, molybdenum, iron, nickel alloys, and .the like, may be used. It is desirable, of course, that the wires 40 have an equal expansion to that of the ceramic material.

In order to maintain tight the grid wires id, there is disclosed a laterally inserted exible plate l5 in cross-section in Fig. 2 and in perspective in 45 Fig. 3.

There are, of course, various modiiications that may be made in the embodiment disclosed in Figs.

1 and 2. In Figs. 4 and 5, the projections of the ceramic body IB are so formed that the grid wires 50 lie on the narrow surfaces I'l, I8, I9, and 20, and these surfaces are separated from the main body by deep slots 2l, 22, 23, and 24. These slots have a further advantage in the fact that the vaporized emission material that might be given oi in activation or subsequentl operation can hardly reach inside these slots and so there is no danger of forming a conductive layer between the cathode and grid to provide a leak or short circuit between the electrodes. The

surfaces

25, 26, 21, and` 28 between the electrodes may be covered if desired with substances such as graphite which do not form conducting chemical compounds with the emissive material vaporized on them. from the electrode. Inserts 3l) and 3| of poorly heat 'con ducting material may be inserted between the heating element 29 and the portion of the insulating body extending towards the grid supporting projections I7, IB, I9, and 20. By one or more, or all of these means, the heat produced by the heatinglk element is conducted, for the -most part, to the

cathode coatings

32 and 33, and the time for heating the cathode to sufcient electron emitting temperature is shorter than it otherwise would be.

If it should be desired to cool the grid more effectively,

cross bands

34 and 35 of metal such as copper can be inserted on the ends and

cooling vanes

36 and 31 extend therefrom as illustrated in Fig. 5. A mica disc 38, as illustrated also in Fig. 5, serves to support the electrode arrangement.

The anode preferably consists of a separately supported element surrounding the cathode and grid or grids, but itis apparent the control grid may be wound on deep slots on the projections and the anode supported onthe outer ends of these projections.

In fact, various modications may be made in the preferred embodiment illustrated, and accordingly, only such limitations are intended upon the following claims as is necessitated by the spirit and scope of the following claims.

I claim:

1. An electrode structure for discharge tubes comprising an insulator having a fiat area, a coating of electron emitting material on said flat area, unitary projections on said insulator and grid wires wound on said projections.

2. An electrode struc-ture for discharge tubes comprising an insulator having a flat area, a coating of electron emitting material on said at area, unitary projections on said insulator and grid wires wound on said projections, and heating means for said electron emitting material enclosed by said insulator.

3. An electrode structure for discharge tubes comprising an insulator having a flat area, a coating of electron emitting material on said flat area, unitary projections on said insulator and a plurality of grid wires wound in slots of'different depth on said projections.r

4. An electrode structure for discharge tubes comprising an insulator substantially in the form of a polyhedron, a grid wound on said polyhedron, a depressed surface on said polyhedron and a coating of electron emitting material on said depressed surface.

5. An electrode structure for discharge tubes comprising an insulator having a substantially flat area, electron emitting material on said' flat area, integral insulator projections on at least two sides of said fiat area and grid wires wound on said projections.

6. An electrode structure for discharge tubes comprising an insulator having a substantially flat area, electron emitting material on said flat area, integral insulator projections on at least two sides of said at area and grid wires wound on said projections, and a slot between said projections and the electron emitting material on said flat area.

7. An electrode structure for discharge tubes comprising an insulator having a substantially iiat area, electron emitting material on said at area, integral projections on at least two sides of said iiat area, grid wires wound on said projections, and a thin wall extending from the portion of the insulator supporting said flat area to the portion of the insulator supporting said pro- J'ections.

8. An electrode structure for discharge tubes comprising an insulator having a substantially flat area, electron emitting material on said flat area, integral projections on at least two sides of said flat area, grid wires wound on said projections, and means keeping said grid wires tight.

9. An electrode structure for discharge tubes comprising a ceramic insulator, grid wires wound on said ceramic insulator, a surface on said ceramic insulator, spaced from said grid wires and a layer of electron emitting material on said surface.

10. An electrode structure for discharge tubes comprising a ceramic insulator, grid wires wound on said ceramic insulator, a surface on said in-` sulator spaced from said grid wires, a metal coating bonded to said surface and an electron emitting coating on said metal coating.

l1. An electrode support of ceramic material having a flat surface and projections lateral at an obtuse angle to said surface and having grooves in said projections.

12. An electrode support of ceramic material having a iiat surface and projections lateral of said surface and having grooves therein and a slot between said flat surface and said projections.

13. An electrode structure comprising an insulator member having two parallel surfaces, electron emitting material on said surfaces, projections lateral of said surfaces and a grid on said projections for each surface and spaced the same distance therefrom.

HANS KOSACK.