Title:
ELECTRON DISCHARGE DEVICE HAVING INCREASED HEATER-CATHODE BREAKDOWN VOLTAGE
United States Patent 3767958


Abstract:
A heater-cathode breakdown voltage above about 8,000 to 9,000 v. is provided for certain electron discharge devices such as damper tubes employed in color television receivers. The increase is achieved by isolating the heater within a metallic cylinder which in turn is concentrically mounted within a cathode sleeve.



Inventors:
Bingeman, Wilbur H. (Emporium, PA)
Grimone, Frank H. (Emporium, PA)
Kerstetter, Donald R. (Emporium, PA)
Application Number:
05/211237
Publication Date:
10/23/1973
Filing Date:
12/23/1971
Assignee:
GTE SYLVANIA INC,US
Primary Class:
Other Classes:
313/240, 313/356
International Classes:
H01J1/20; (IPC1-7): H01J1/00; H01J19/00; H01K/
Field of Search:
313/238,337,340,356
View Patent Images:
US Patent References:
2870366Electric discharge tube of the kind comprising a cathode of the indirectly heated type1959-01-20Van Tol
2757308Emissive cathode1956-07-31Katzberg
2757308Emissive cathodeJuly 1956Katzberg
1962427Thermionic translating device and system1934-06-12Claypoole
1897229Indirectly heated cathode1933-02-14Bohm



Foreign References:
DE1101628B1961-03-09
Primary Examiner:
Rolinec, Rudolph V.
Assistant Examiner:
Chatmon Jr., Saxfield
Claims:
We claim

1. In an electron discharge device having an evacuated envelope and containing an electrode cage mounted between upper and lower insulating members, said electrode cage comprising at least an anode, an indirectly heated cathode, and a heater for said cathode, means improving the heater-cathode breakdown voltage comprising: a hollow metallic sleeve containing said heater, said sleeve being concentrically mounted within a hollow cathode body and spaced therefrom throughout its entire length and presenting a substantially solid surface to the interior wall of said cathode, said sleeve further being electrically isolated from said heater, and means for maintaining said spacing between said heater containing said sleeve and said cathode, said last named means comprising upper and lower insulating members being provided with a substantially centrally located aperture of a size to frictionally engage said heater containing sleeve and said aperture is provided with a plurality of equidistantly spaced, radially extending slots, said cathode body having a similar plurality of tabs at either end thereof and said tabs being frictionally engaged in said slots.

2. In an electron discharge device having an evacuated envelope and containing an electrode cage mounted between upper and lower insulating members, said electrode cage comprising at least an anode, an indirectly heated cathode, and a heater for said cathode, means for improving the heater-cathode breakdown voltage comprising: a hollow metallic sleeve containing said heater, said sleeve being concentrically mounted within a hollow cathode body and spaced therefrom throughout its entire length and presenting a substantially solid surface to the interior wall of said cathode, said sleeve further being electrically isolated from said heater, and means for maintaining said spacing between said heater containing sleeve and said cathode, said last named means comprising pairs of upper and lower insulating members, the innermost of said members being provided with an aperture of sufficient size to frictionally engage said cathode body and the outermost of said members being provided with an aperture of sufficient size to frictionally engage said heater containing sleeve, said outermost members being spaced from said innermost members by means of a rigid wall which engages and secures together said upper and lower members.

3. In an electron discharge device having an evacuated envelope and containing an electrode cage mounted between upper and lower insulating members, said electrode cage comprising at least an anode, an indirectly heated cathode, and a heater for said cathode, means for improving the heater-cathode breakdown voltage comprising: a hollow metallic sleeve containing said heater, said sleeve being concentrically mounted within a hollow cathode body and spaced therefrom throughout its entire length and presenting a substantially solid surface to the interior wall of said cathode, said sleeve further being electrically isolated from said heater, and means for maintaining said spacing between said heater containing sleeve and said cathode, said last named means comprising a metallic member fastened to said insulating member and having a wall normal to said insulating members and an instanding flange parallel to said insulating member, said flange being provided with an aperture to receive said heater containing sleeve and having means for engaging said sleeve and maintaining the same in position and said insulating member being provided with an aperture for receiving said cathode body.

4. In an electron discharge device having an evacuated envelope and containing an electrode cage mounted between upper and lower insulating members, said electrode cage comprising at least an anode, an indirectly heated cathode, and a heater for said cathode, means for improving the heater-cathode breakdown voltage comprising: a hollow metallic sleeve containing said heater, said sleeve being concentrically mounted within a hollow cathode body and spaced therefrom throughout its entire length and presenting a substantially solid surface to the interior wall of said cathode, said sleeve further being electrically isolated from said heater, and means for maintaining said spacing between said heater containing sleeve and said cathode, said upper and lower insulating member being held in a spaced apart manner by the cooperation of slots therein which engage projecting lugs on said anode and said means for maintaining said spacing between said heater containing sleeve and said cathode body which comprises two pairs of Z shaped members, one of each of said pairs being affixed to one of said anode lugs and auxiliary upper and lower insulating members held in place by said lugs and resting upon said Z shaped members, said auxiliary upper and lower insulating members having an aperture to receive said heater containing sleeve and said upper and lower insulating members having an aperture to receive said cathode body.

Description:
BACKGROUND OF THE INVENTION

This invention relates to electron discharge devices and more particularly to damper tubes having an increased heater-cathode breakdown voltage. Prior designs of damper tubes have utilized an insulating coil surrounding the heater to provide a vacuum insulator between the cathode and heater. Such an arrangement provides a heater-cathode breakdown voltage above about 6,500 v., which is the rated potential difference between the heater and the cathode. Newly required tubes demand a heater-cathode breakdown voltage in excess of 8,000 v., a condition which cannot be consistently achieved in mass production with the prior design.

OBJECTS AND SUMMARY OF THE INVENTION

It is, therefore, an object of the invention to enhance the operation of damper tubes as well as other tubes requiring similar operating conditions.

It is a further object of the invention to increase the heater-cathode breakdown voltage of such tubes.

These objects are accomplished in one aspect of the invention by the provision of an electron discharge device which contains, in an evacuated envelope, an electrode cage comprised of at least an anode, an indirectly heated cathode and a heater therefor. The electrodes are mounted and maintained in their respective positions by upper and lower insulating members, as is conventional in the art. The improvement in the heater-cathode breakdown voltage is achieved by positioning the heater within a hollow metallic sleeve which in turn is concentrically mounted within the cathode body. The superior insulating qualities resulting from this structure achieve the desired result.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational sectional view of an electron discharge device;

FIG. 2 is a perspective view, with parts omitted, of an embodiment of the invention;

FIG. 3 is a plan view of the embodiment of FIG. 2;

FIG. 4 is an elevational sectional view, with parts omitted, of an alternate embodiment of the invention;

FIG. 5 is a plan view taken along the line 5--5 of FIG. 4;

FIG. 6 is a plan view of another embodiment of the invention;

FIG. 7 is an elevational sectional view taken along the line 7--7 of FIG. 6;

FIG. 8 is a plan view of yet another embodiment of the invention; and

FIG. 9 is an elevational sectional view, with parts omitted, taken along the line 9--9 of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims together with the above-described drawings.

Referring now to the drawings with greater particularity, there is shown diagrammatically in FIG. 1 an electron discharge device 10 such as a damper tube. The tube 10 comprises an evacuated envelope 12 which contains therein an electrode cage 14 mounted between upper and lower insulating members 16 and 18. The last named members generally are of mica. The electrode cage 14 has an anode 20, an indirectly heated cathode 22 and a heater 24, only the lower legs of which are visible in FIG. 1. The heater, which can be a conventional spade wound heater of tungsten or similar material having thereon an insulating layer of alumina, is positioned within a hollow metallic sleeve 26 which in turn is concentrically mounted within cathode body 22.

In FIGS. 2 and 3 there is shown means 28 for maintaining the spacing between sleeve 26 and cathode 22. Herein the upper and lower insulating members 16 and 18, only one of which is shown, are provided with a substantially centrally located aperture 30 of a size to frictionally engage the heater containing sleeve 26. The aperture 30 is provided with a plurality of equidistantly spaced, radially extending slots 32, in this instance three although more or less can be used. In this embodiment the ends of cathode 22 are provided with a like number of tabs 34 which are frictionally engaged in slots 32. This arrangement provides adequate support and reduces the possibility of leakage paths developing between sleeve 26 and cathode 22.

An alternate means 28a is shown in FIGS. 4 and 5. Means 28a comprises upper and lower pairs of insulating members of which only upper pair 36 is illustrated. The innermost member 38 of pair 36, i.e., the member which corresponds to member 16, is provided with an aperture 40 of sufficient size to frictionally engage the cathode 22. The outermost member 42 is provided with an aperture 44 to frictionally engage the sleeve 26 and is mounted above member 38 by means of a frame or wall 46 of substantially rigid construction. The top and bottom of the wall 46 are provided with tabs 48 and 50 respectively which engage slots 52 and 54 respectively in 42 52 and 38 to maintain the structure as a unit. Member 38 is further provided with slots 56 which engage tabs 58 on anode 20 for supporting the electrode cage and is generally also provided with elongated openings 60 to assist in ventilating the cage and breaking up leakage paths between the cathode and anode.

Yet another means of maintaining the spacing between sleeve 26 and cathode 22 is illustrated in FIGS. 6 and 7. Means 28b comprises a metallic member 62 having a wall portion 64 which is substantially normal to an insulating member 66 to which it is mounted by means of tabs 68 which extend from the bottom of the wall 64 and cooperate with slots 70 in member 66.

An instanding flange 72 projects from the top of wall 64 and is provided with an aperture 74 for engaging sleeve 26. The aperture is actually a raised boss 76 which forms a collar for sleeve 26 and the top of the boss is provided with tabs 78 for holding sleeve 26 in position. The insulating member 66, which is mounted upon the anode tabs as described above, is provided with an aperture 80 for receiving the cathode 22.

FIGS. 8 and 9 disclose still another means of maintaining the spacing between sleeve 26 and cathode 22. Means 28c comprises an innermost insulating member 82 which is held in position by lugs 58 of anode 20. The member 82 is provided with an aperture 84 for receiving the cathode 22. Positioned above member 82 is a second insulating member 86 which contains an aperture 88 to receive sleeve 26 and which is also mounted upon lugs 58 of anode 20. The requisite spacing between the members 82 and 86 is achieved by two substantially Z shaped elements 90 of metal or other suitable rigid material which have their central portions 92 conformed in configuration to the lugs 58 and are attached thereto inbetween members 82 and 86.

Thus, it will be seen that the invention described herein has many advantages over the prior art. The inner sleeve which contains the heater achieves heater-cathode breakdown voltages in excess of that regularly attainable by prior methods and the novel manner of mounting the sleeve and cathode to maintain the required spacing therebetween is both sturdy and economical.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.