US3579020A

US3579020A - Electron discharge device with electrode spacer having integral electron vibration dampening member thereon

Info

Publication number: US3579020A
Application number: US783543A
Authority: US
Inventors: William F Cullen; Othmar E Ringeman
Original assignee: General Electric Co
Current assignee: General Electric Co; INDIANA NATIONAL BANK
Priority date: 1968-12-13
Filing date: 1968-12-13
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18

Abstract

An insulative electrode spacer member is provided for an electron discharge device, which spacer comprises a disc of natural mica provided with a cathode dampening arm as an integral part of the spacer. A hole is formed in the mica spacer adjacent the dampening arm for the insertion of a cathode which is properly engaged by a free end of the dampening arm which is positioned on the top of the cathode. The cathode may be notched at the top and the arm so positioned with respect thereto that the arm only engages the bottom of the notch when the cathode expands due to normal operational heating.

Description

United States Patent William F. Cullen [72] Inventors Philpot, Ky.; Othrnar E. Ringeman, St. Meinrad, Ind. [2]] Appl. No. 783,543 [22] Filed Dec. 13, 1968 [45] Patented May 18, 1971 [73] Assignee General Electric Company [54] ELECTRON DISCHARGE DEVICE WITH ELECTRODE SPACER HAVING INTEGRAL ELECTRON VIBRATION DAMPENING MEMBER THEREON 4 Claims, 5 Drawing Figs.

[52] US. Cl 313/269, 313/250, 313/257, 313/289 [5i] Int. Cl H013 1/18, H01 j 19/12 [50] Field of Search 313/289, 269, 257, 256, 250

[56] References Cited UNITED STATES PATENTS 2,494,853 1/l950 Alma 313/269X FOREIGN PATENTS 246,656 5/1963 Australia 313/169 258,368 5/1963 Australia 313/169 Primary Examiner-John W. Huckert Assistant Examiner-Andrew J. James AttorneysNathan J. Cornfeld, John P. Taylor, Frank L.

Neuhauser and Oscar B. Waddell ABSTRACT: An insulative electrode spacer member is provided for an electron discharge device, which spacer comprises a disc of natural mica provided with a cathode dampening arm as an integral part of the spacer. A hole is formed in the mica spacer adjacent the dampening arm for the insertion of a cathode which is properly engaged by a free end of the dampening arm which is positioned on the top of the cathode. The cathode may be notched at the top and the am so positioned with respect thereto that the am only engages the bottom of the notch when the cathode expands due to normal operational heating.

Patented May 18, 1971 3,579,020

F|G.2. Fl (5.3.

mks:

1c I2 mm IN V ENTORS:

WILLIAM F. CULLEN OTHMAR E. RINGEMAN,

THEIR ATTORNEY.

ELECTRON, DISCHARGE DEVICE WITH ELECTRODE SPACER HAVING INTEGRAL ELECTRON VIBRATION DAMPENING MEMBER THEREON IMPROVED ELECTRON DISCHARGE DEVICE HAVING IMPROVED ELECTRODE SPACER BACKGROUND or THE INVENTION This invention relates to electron discharge devices and more particularly to an electrode and electrode spacer arrangement whereby the electrode spacer is provided with a cathode-dampening arm used to preclude microphonics due to cathode vibration.

It has been found that one of the most common causes of v microphonics in electron discharge devices is the excessive vibrative movement of a cathode mounted within a surrounding insulative spacer member, such as a mica disc. Currently used cathodes are somewhat more sophisticated and fragile than earlier cathodes and, consequently, the problem of cathode movement and dampening has become somewhat aggravated by this fragile nature. If a cathode is secured too tightly by a spacer, it has a propensity to either deform when heated (resulting in interelement shorts or shifts in the electrical characteristics of the electron discharge device) or to even collapse due to excessive moments applied about the base of the cathode mounting. Another problem encountered in mounting a cathode within an electron discharge device is an excessive heat drain from the cathode due to a very tight cathode-to-mica fit, which heat drain results in unsatisfactory electron discharge performance at reduced heater voltages.

It has been proposed to check excessive movement or vibration of the cathode by the addition of a second mica member anchored to the conventional mica spacer disc, which second member has a flexible arm for resting or pressing against the side of the cathode so as to damp cathode movement in an attempt to preclude microphonics.

This configuration of electron discharge spacer has worked with some success in reducing cathode microphonics, but it does have several weighty disadvantages in that it is quite costly and requires an additional mica member as well as addi- 1 tional intricate steps in the construction thereof. Likewise, the use of arms or tabs pressing on the side of a cathode in an electron discharge device does tend to deform many of the more fragile cathodes currently in use. During the heating and cooling of a cathode, considerable expansion and contraction results which, in turn, causes continual bending and deflection of the mica arm. Since natural mica, the preferred material used for electrode spacer discs, is brittle and since the fatigue limit of such a brittle material is rather low, it is quite possible for the mica cathode-dampening arm to break. Since the cathode is mounted with the effect of the moment resulting from the mica arm pressing against the side of the cathode taken into account for proper cathode placement purposes, if the mica arm is subsequently broken, the cathode within has a tendency to bend toward the arm and become misaligned from the proper position occupied before the break.

OBJECTS OF THE INVENTION Accordingly, one object of the present invention is to provide a spacer member and electrode arrangement for an electron discharge device which is of simple configuration, economical and easy to install.

Another object of the present invention is to provide a spacer member for an electron discharge device which will not deflect or apply a normal force to a cathode which is to be dampened in an effort to preclude microphonics.

It is still a further object of this invention to provide a spacer member for an electron discharge device which will not cause a cathode to misalign if it should be broken by shock or vibration forces.

SUMMARY OF THE INVENTION In carrying out the invention in a preferred form, a spacer member is provided for use in an electron discharge device which spacer includes a flexible arm resiliently flexed and positioned on top of a cathode projecting through an opening defined in the spacer member.

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in a concluding portion of this specification. The invention, however, both as to organization and method of practice, together with further objects and advantages thereof, may best be understood by a reference to the following description of the preferred embodiment taken in connection with the accompanying drawings in which:

FIG. 1 is an isometric view of the improved spacer member and electrode arrangement of the invention.

FIG. 2 is a section view taken along the line IIII shown'in FIG. 1.

FIG. 3 is a cross-sectional view of a preferred embodiment of the invention shown with the cathode in a cold condition.

FIG. 4 is a cross-sectional view of the embodiment of FIG. 3 showing the cathode in a heated condition.

FIG. 5 is a fragmentary top view of another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings on which like numbers are used to indicate like parts throughout the various views thereof, FIGS. 1 and 2 show an improved spacer member 10 comprising two

semicircular mica discs

14 and 16. Disc 14 is integrally formed witha cathode-dampening arm 12 projecting over a portion of disc 16. An opening 18 is defined within spacer l6 and is sized to allow the projection of a cathode 20 therethrough. It will be noted that in the illustrated embodiment the cathode is not centrally located with respect to the axis defined by the two semicircular spacers. This allows cathode-dampening arm 12 to be of relatively long length with respect to the diameter defined by the two semicircular discs without terminating at a point so close to the edge of disc 14 to structurally weaken the disc. This relatively long length allows arm 12 to properly flex upon thermal expansion of the cathode upon heating.

It should be noted that the cathode-dampening arm 12 of the invention is positioned to apply a force parallel and not normal to the vertical axis of the cathode and, as such, if the dampening arm 12 should break, the cathode would not tend to misalign. Likewise, the force of the arm 12 against the cathode will not distort or deflect the cathode upon heating as the arm is not applying a force in an unsupported direction normal to the axis of the cathode.

One problem which may be encountered in the embodiment shown in FIGS. 1 and 2 is that of fatigue failure of the dampening arm 12 due to cyclic or intermittent heating and cooling of the cathode 20. If this should prove to be a problem in operation, the cathode may be configured with a notch 22 formed in the top thereof, as shown in FIG. 3. With this arrangement, cathode 20' contacts the arm 12 only when the cathode has expanded due to operational heating. Consequently, arm 12 is not subjected to severe deflections and fatigue failure of arm 12 is precluded. FIG. 4 shows cathode 20' heated and ex panded to meet dampening arm 12 as per the above discussion. It should be noted in FIGS. 3 and 4 that notch 22 in cathode 20' is tapered so that dampening arm 12 only makes point contacts (or line contacts) on either side of the notch so as to avoid excessive heat drain from the cathode through the mica dampening arm 12.

FIG. 5 shows another embodiment of the invention whereby the end of dampening arm 12 which contacts cathode 20 is itself formed with a notch 24 so that the arm engages cathode 20 only at two

point contacts

26 and 28. In this embodiment, excessive heat drain is also minimized by the minimum contact area between cathode 20 and dampening arm 12. However, in this embodiment, vertical access to the cathode from above is also permitted by the shape of the dampening arm 12. This has been found to be beneficial particularly when utilizing the invention with indirectly heated cathodes.

in accordance with the invention dampening arm 12 is formed integrally with the mica spacer disc. While the embodiment illustrated in FIG. 1 uses a two-piece spacer when the cathode is mounted in an offset position which is the preferred arrangement for use, for example, in multifunction tubes or the like, it is to be understood that the invention also contemplates the use of a unitary spacer disc with a centrally positioned cathode, particularly in larger tubes where formation of the arm integrally from a unitary mica spacer would not unduly weaken the spacer due to the larger diameter of the tube and corresponding spacer.

The embodiment shown in F108. 3 and 4 shows a notched cathode embodiment in which arm 12 is preconditioned so as to be disposed above the notch of the cathode in its relaxed state. Only when the cathode is heated and is thereby caused to expand does it contact dampening arm 12 and then the engagement is only at two point contacts. This arrangement thereby precludes failure of the dampening arm due to severe deflection travel and checks excessive dissipation of heat from the cathode to the arm. The notched dampening arm shown in FIG. is the reverse embodiment of the notched cathode and provides the same advantage of lessened heat dissipation by minimizing cathode/mica contact.

While the preferred embodiment of the applicants invention has been shown in the simplest form, it is of course understood that various modifications may be made therein without departing from the spirit and scope thereof, and it is therefore intended to cover in the claims appended hereto all such variations as fall within the true spirit and scope of the present invention.

We claim:

1. An improved electron discharge device comprising an electrode spacer said spacer having an opening defined therein and an electrode projecting therethrough, said spacer having a flexible arm integrally formed thereon and preconditioned to be disposed above and in contact with the top of said electrode said flexible arm being so positioned with respect to said electrode that when said electrode is operationally heated, said electrode expands and exert a pressure on said flexible arm, whereby said arm is caused to apply a force which is substantially solely parallel to the vertical axis of the electrode whereby movement of the electrode is dampened.

2. An improved electron discharge device including an electrode spacer, a cathode projecting through said spacer, an electrode dampening arm forming an integral part of said spacer, said cathode being formed with a tapered notch in the top thereof, said flexible arm preconditioned to be disposed above said notch when the cathode is in a cold condition, said flexible arm so positioned and said tapered notch so formed that when said cathode is operationally heated said cathode expands to engage said flexible arm at either side of said notch to apply a force parallel and not normal to the-vertical axis of the electrode.

3. The spacer as defined in claim 1 wherein said spacer comprises mica.

4. The spacer as defined in claim 2 wherein said spacer comprises mica.

Claims

2. An improved electron discharge device including an electrode spacer, a cathode projecting through said spacer, an electrode dampening arm forming an integral part of said spacer, said cathode being formed with a tapered notch in the top thereof, said flexible arm preconditioned to be disposed above said notch when the cathode is in a cold condition, said flexible arm so positioned and said tapered notch so formed that when said cathode is operationally heated said cathode expands to engage said flexible arm at either side of said notch to apply a force Parallel and not normal to the vertical axis of the electrode.

3. The spacer as defined in claim 1 wherein said spacer comprises mica.

4. The spacer as defined in claim 2 wherein said spacer comprises mica.