US2017549A - Electron discharge device - Google Patents

Description

15, 1935- B. SALZBERG I ELECTRON DISCHARGE DEVICE Filed March 6, 1935 INVENTOR BERNARD SALZBERG Patented Oct. 15, 1935 UNITED STATES- PATENT OFFICE 2,011,549 atroraon mscmmor nnvrcn Bernard Salzberg, East Orange,

by memo assignments, to Radio America, New York, N.

Delaware Application March 6, 1935,

4 Claims.

tional tube will operate is limited principally by a ing electrodes small,

interelectrode and interlead capacity and by the inductance of the leads to the electrodes because the inductance and capacity of the electrodes and leads form an electric system which determines the upper limit of frequency at which the tube will operate. While the interelectrode capacity may be decreased and the upper frequency limit at which a tube will operate increased by makmaking them short and bringing out the leads at different points of the bulb, such a tube is make because of special constructions and methods required for assembling such tubes. Where the electron discharge device is of the multi-grid type, it becomes diilicult to provide proper shielding between the various elements in the tube, particularly between the control grid lead and the anode. Shielding becomes important at the very high frequencies at which the tubes are intended to operate.

An object of my invention is to provide an electron discharge device which may be made commercially even in very small sizes and in which the interlead capacity and the inductance of the leads are considerably less than in the conventional type. Another object of my invention is to provide an electron discharge device of the type described in which the overall dimensions and interelectrode spacing is much less than is feasible with tubes constructed in the usual way. A still further object of my invention is to provide an electron discharge device of the type described in which the various elements and leads are properly shielded from one another.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following. description taken in connection with the accompanying drawing in which Figure 1 is a perspective view with parts broken away of the electrode mountassembly of an electron discharge device embodying my invention; Figure 2 is a vertical section of the electrode mount assembly shown in Figure 1; Figure 3 is a bottom plan view of the electrode mount assembly shown in Figure 2; and Figure 4 shows an electron discharge device made in accordance with my invention and mounted in a shielded type of socket.

The envelope ill of the tube shown in Figure 4 encloses and supports a unitary electrode mount assembly shown in detail in Figures 1 to 3 inclusive and comprising an indirectly heated cathode ll,'a control grid l2, a screen grid l3, suppressor grid 14 and an anode it, which may diflicult and expensive to N. 1., assignor, Corporation of 2., a corporation of Serial No. 9,543

' be a box-like structure made from sheet metal. The anode I5 is provided with a pair of flat side rods it which could be made integral with the plate and which have shoulders ii for supporting electrode spacers i8 and IQ of insulation such as mica and preferably in the form of plates or discs transverse to the longitudinal axis of the electrode mount. The shoulders I! are bent over onthe outside of and against the mica plate members and may lie in slots in the edges of the 10 plate members as shown to rigidly secure the spacers to the anode so as to provide a rigid and unitary electrode assembly.

In accordance with my invention described and claimed in my copending application Serial No. 732,028 filed June 23, 1934 and assigned to the Radio Corporation of America, radially positioned stifi conductors 20. which serve as lead-ins and mount support wires, extend thru an annular press 2! in the wall of the envelope "I as shown in Figure 4 and have secured to their inner ends, preferably by welding, U-shaped conductors 22 having one end threaded thru apertures 23 in the insulating disc or plate It to secure the conductors 2|! to the plate member as best shown in Figure 1, one end 24 of conductor 22 being formed to engage the bottom of the insulating plate l9 and the other end 25 being electrically connected to one of the electrodes mounted between the plates l8 and 19. The outer ends of the conductors 20 serve as tube contacts, as best shown in Figure 4, to be' received in a properly designed socket. This construction eliminates the need of the usual reentrant stem press and materially reduces the overall dimensions of the tube. It will be observed that the control grid lead 26, and the anode lead 21, are positioned to extend from opposite ends of the envelope to reduce interlead capacity and inductance and to separate the input and output leads as much as possible. The getter tab 28 is preferably secured to the upper end of the mount. It is formed to direct the getter against the side wall of the envelope.

In accordance with my invention shielding is provided to shield the anode and its lead from the control grid and its lead. This shielding includes a top disc-like metal shield 3| provided with a rectangular aperture 32, as best shown in Figure 2, thru which the end of the cathode and the grid side rods extend, and issupported in spaced relationship with respect to the mica disc It by means of small pips 33 on the bottom of the disc. Attached to a collar 34 on the disc shield 3| is a box-like portion 35 which completely shields the end of the cathode and grid side rods from the plate lead 31. This shielding is out of contact with the plate side rods. This upper shield may be secured to the mount and connected by means of a pair of side rods 36, only one of which is shown, to a lower shield comprising an invertedcup-shaped metal member 31 provided with a rectangular aperture ,38 thru which the ends 01' the cathode and grid side rods extend. Other apertures which the ends 25 01' the fastening conductors 22 extend. This lower shield is insulated from the mount by means of intermediate insulating disc 40- which registers with the insulating disc l9 and is provided with an aperture 4|, thru which the end of the cathode and grid side rods extend. The ends 25 of the fastening conductors extend thru the mica disc 40 and the apertures 39 to be connected to the proper electrodes. The shields may be connected by means of a strap l2'to the cathode, which is usually at ground potential or may be provided with a separate lead. The upper and lower shields are, therefore, completely insulated from the electrode mount assembly and connected to the cathode, and with the screen grid and suppressor grid, which may be provided with a separate lead as shown, completely shields theanode and anode lead from the control'grid and, control grid lead.

The electron discharge devicemade in accordance with my invention may be mounted in a specially designed tube socket as best shown in Figure 4. The socket may include a shielding partition 43, having a ring 44 of insulating material upon which the clip type contacts 45 may be supported toreceive the terminals 20 of the electron discharge device.- It will thus be seen that by means of this arrangement the input circuit which is connected to lead 26 and the output circuit which is connected to lead 21 are completely shielded from each other.

A tube constructed in accordance with the above invention may easily be made of very small dimensions, is sturdy and reduces interelectrode capacity and inductance to a very small value, permitting operation of the tube at extremely high frequencies.

While I have indicated the preferred embodiment of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact i'orms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed-without departing from the scope oi my invention asset forth in the appended claims.

What I claim as new is:-

1. An electron discharge device including an envelope, a unitary electrode mount assembly positioned within the envelope and comprising a pair of insulating plate members and electrodes positioned between and secured to said members, still lead-in conductors extending thru the wall of the envelope and positioned around the periphery of one of said insulating plate members,

means at the inner ends of said still lead-in conductors securing the conductors to said one of said insulating plate members for supporting the mount within the envelope and for electrically connecting the conductors to the electrodes positioned betweenthe insulating plate members, and electrostatic shielding members positioned on opposite ends of the electrode mount assembly and secured to said insulating plate members out of contact withsaid electrode assembly.

2. An electron discharge device including an envelope, a unitary electrode mount assembly po- 89 are provided thru bers and secured sitioned within theenvelope and comprising a pair or insulating plate members, electrodes positioned between and secured to said members and having their ends extending thru said members, stifl lead-in the periphery of one of said insulating plate memto said one of said insulating plate members and electrically connected to said electrodes, a cup-shaped metal shield positioned on the outside of said mount adjacent'said' one 10 01' said insulating plate members and provided with an aperture thru which the ends 01' the electrodes extend, an insulating plate member positioned between said one of said insulating plate members and said shield to electrically insulate said shield from the electrodes in said mount and said stifi' lead-in conductors, and means for securing said shield to said mount.

3. An electron stiir-lead-in conductors positioned around the periphery of one or said insulating plate members and secured'to said one of said plate members and electrically connected to said electrodes.

the other end of said mount provided with a boxrods extending longitudinally of said mount thru said insulating plate members and secured to said the inner ends of said lead-in conductors. said second conductor having one end secured to' one or the insulating plate members andthe'other end electrically connected to an electrode in said electrode mount assembly whereby'said mount is supported within said tube bys'aid radially positioned lead-in conductors. a cup shaped shieldingmember secured to said one of the insulating platemembersand provided with an aperture thru which ends of said electrodes extend, an insulating plate member positioned between said shield and said one or said insulating plate memberst'oelectrically insulate said shield from saidilead-in conductors and said second eonductors and provided with apertures thru which said second conductors extend to be connected to the ends of said electrodes and means for securing said shield to said mount assembly.

amman conductors positioned around 5

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