US2385435A

US2385435A - Electron discharge device

Info

Publication number: US2385435A
Application number: US559948A
Authority: US
Inventors: Leo C Werner; Willard A Laning
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1944-10-23
Filing date: 1944-10-23
Publication date: 1945-09-25
Anticipated expiration: 1962-09-25

Description

t. 25, 9 L. c. WERNER E'I'AL 0 2,385,435

ELECTRON DISCHARGE DEVICE Filed 001;. 23, 1944] Y AITORNEY Patented Sept. 25, 1945 Leo 0. Werner, Bloomfield, and Willard AL Laning'. Glen Ridge, N.J., assignorsto" Westinghouse "Electric CorporatiomgEast Pittsburgh, Pa., a

corporation of Pennsylvania Application October 23, 1944, Serial No. 559,948

Claims. (01. 250- 275) Thisinvention relates to electron discharge. de-

vices'and more particularly to suohdevices employing filamentary cathodes.

' The particular device of the present invention is a triode vacuum tube to be used in connection with such service as dielectric heating. equipment, and requiring high power output. A fundamental requirement, attainment of which is an object of the invention, is to provide a tube of reasonable size and yet with a cathode of sturdy construction, capable of producing high power output.

" A'further object of the invention is to adapt the structure to utilization of smaller conductors than heretofore required for tubes having corresponding power output.

Another object of the invention is toobtain extensive emission area but a relatively short over-all length of tube.

"Again, an object of the invention is to utilize readily made stampings for filament or cathode connections.

Another object of the invention isv to provide tensioning means for the filament strands of improved character and without material in.. crease of length of the device.

Yet another object is to simplify the dielectric spacing of thefilam'ent connections.

'Still'further objects of the invention will appear to those skilled in the art to which it appertains'as the description proceeds, both by direct recitation thereof and by implication from the context.

Referring to the accompanying drawing in whichlike numerals of reference indicate similar parts throughout the several views V Figure 1 is substantially an elevation of an electron discharge device, the bowl and anode ofwhich are broken away and the grid shown in longitudinal section;

Figure '2 is sectional view on line IIII of Fig. 1

Figure 3' is a sectional view on line'III-III of i Figure 4 is a sectional view similar to Fig. 2 but showing a neutral connector for use with M- type filament strands; and

Figure 5 is a sectional view on line V-V of Fig. 4.

In the specific embodiment of the invention illu'strated in said drawing, a part of an electron discharge device, generally identified as a transmitting or power tube, is depicted exemplifying the invention. It should be understood, however, that theinvention is applicableto other electromc devices than'the, particular transmitting or power tube here selectedfor illustrative purposes.

'The specific tube shown comprises a glass or other ceramic bowl or casing portion 10 here represented as part of an evacuated envelope,

' unified with appropriate posts, of which one post l2 leads'to and upwardly upon the axis of the device and other posts l3 are spaced therearound Within the basejportion'of the. envelope. At the upper rim of 'the' b'owl l0, there is sealed thereto a metallic cylindrical dome-like anode M, which, with said bowl constitutes a closed. and evacuated envelope.

Coaxially within the said anode andspaced in parallelism tothe'cylindrical'wall thereof is a grid IS, the upper end of'which has a trans- Verse supporting plate l5 as part thereof and the lower end of which hasa metallic flanged collar 11 integral therewith. One or more of said posts [3 are attached to the flange of said collar IT for rigidly mounting the said grid.

The filament or cathode, designated generally in Figures 1 to 3 by reference numeral [8, comprises a plurality of strands, the major portions of which are parallel and together constitute a cylindrical assembly coaxial to the .grid and anode. In the showing of Figures 1 to 3 the cathode is composed of a plurality of, hairs-pin sections each having two parallel legs or strands IS with the endstoward the bowl end of the device and the two strands. offeach section in electrical series. The several se'ctionsare" in electrical. parallel.

In the showing of Figures'4 and 5, the cathode 18a is composed of a plurality of M-type sections each having four parallellegs or strands 19a in electrical series and the several sections inelectrical' parallel. Both constru'ctionsprovide bi'ghts 2|] at the upper or remote part of the strands from the section ends, said bights having appropriate support .by which the strands are both held and tensioned. In the construction with the'hairpin' filament'sections, the bights are carried by a metallic plate 2!, the mid-portion whereof rests upon an insulating button 22 slidable upon the aforementioned axial post 12. With the M-typ'e filament sections-of.- Figs. 4 and 5, the plate it is insulativeor the two: upper bights of the M-filament are otherwise maintained electrically from, shorting acrossthe plate.

In any event, upward pressure upon the button 22 transmits through the plate to the filament bights and exerts tension on the several strands of the filament to keep them taut.

Upward pressure is applied to said button by a coaxial sleeve 23 slidably mounted on the axial post I2.- Preferably -the inside diameter of said sleeve exceeds the outside diameter or said post so as to be out of contact and to avoid introduction of frictional resistance to movement of the sleeve. Caps 24 are fitted over the ends of said sleeve, said caps having holes which substantially fit the post and since the caps are preferably sheet metal, the edges of the holes are of limited area and thus have minimum contact with the post and interfere to no appreciable degree with free sliding on the post, but maintain the sleeve substantially coaxial to the post. The upper cap 24 provides a fiat bearing surface against button 22 distributing pressure of the end edge of the sleeve over a more extensive area of the button than would occur with direct engagement of the sleeve against the button.

The lower cap 24 is interposed between the lower edge of sleeve 23 and the upper end of a coil spring 25 mounted on said post I2. Said spring is under compression, its lower end engaging a shoulder 26 of a fixed collar 21 carried by the post. As shown, said fixed collar has, below the shoulder, a lower end portion which is of equal internal diameter to the exterior diameter of the post and welded, soldered orotherwise permanently afiixed to the post. Above the said shoulder, said fixed collar has an upper portion having a larger internal diameter than the external diameter of the cap and spring so as not to interfere with free operation of either and receives the spring therein. Said upper portion extends well above the cap and has an outwardly directed flange 28 at its upper end.

An inverted metallic cup 29 coaxial with said sleeve is welded, soldered or otherwise secured to said flange. Preferably said sleeve projects through the transverse wall of said cup so that the said wall of the cup is at the under side of the flange. The peripheral side wall of the cup depends from said transverse wall, is cylindrical in character and at a distance from the sleeve, thereby providing an insulator-receiving downwardly open pocket or hollow. The lower edge of the cylindrical side wall of said cup is provided with a plurality of ears 30 in a sequential circular series aroundthe cup. From each ear to the next in sequence is left a considerable space for purposes hereinafter related. The ears have their basal portions in continuation of the cylindrical wall parallel to the axis and have an intermediateportion which bends radially outward and an end portion which is bent to again continue parallel to the 'axis but further therefrom radially than the basal portion. The radially extending intermediate portions of the ears accordingly define a transverse plane which is ofiset in an axial direction from the plane defined by the lower edge appearing between the ears of the peripheral wall of the cup. Description thus far given of the inverted cup and its ears is equally applicable to all figures of the drawing. However, in Figures 1 to 3 the recurrence of ears in the sequence is more frequent than in Figures 4 and 5. I

Below the inverted cup, entirely out of contact therewith, is a lower cup 3|, the hollow of which is directed upwardly or toward the hollow of the upper or inverted cup. This lower cup has a hole or opening 32 centrally of its transverse or bottom wall, which is larger than the outside diameter of aforementioned fixed collar 21. The hollows of the two

cups

29 and 3| are of substantially the same size and shape and receive an annular insulator or other ceramic 33, the ends ofwhich are in engagement with the transverse walls of the cups and the length of which is proportioned to the depth of the two cups so that ears 34 of the lower cup which extend first upwardly and then outwardly have the said outwardly directed portions thereof in the same plane as the outwardly directed portions of the aforementioned ears of the upper cup 29. The said ears of the lower cup project from an edge of the lower cup, which is below or offset in a direction axially of the device from the said plane of the outwardly projecting portion of said ears so as to make no contact with the upper cup or its ears. The ears of the lower cup are, like the ears of the upper cup, in a sequential annular series'around the cup, and the ears of one cup alternate between ears of the other, andsuccessive ears are spaced from 'each other in a direction peripherally of the cups.

In the showing of Figures 4 and 5, the ears of the upper and lower cups are grouped as pairs, and between pairs a considerable gap is provided and in these gaps are radially projecting portions of ears 35 on a washer-like neutral plate 36, these ears being shown as double the width of the cup ears and forming therewith a continuous sequential series of ears having portions projecting radially from the insulator or ceramic. Figures 4 and 5 show the insulator as divided longitudinally on the plane of the projecting portions of the ears and washer-like neutral plate 35 into two sections 3%, so that said plate is mechanically mounted from but is electrically separated from the said cups. The outer ends of all ears are directed downwardly and together define a cylindrical surface interrupted peripherally by the recurring gaps between successive ears. The foot portions or ends of the filament or cathode sections depend next the downwardly directed end portions of the ears, one end of each cathode section being secured, as by welding, to an ear from one cup and the other end being secured to an ear of the other cup. In Figures 4 and 5 utilizing an M-type filament, the intermediate legs or strands are both secured to the depending portion of a double wide ear of the neutral plate 35.

It is now appropriate to observe that upward displacement of the cups and insulator assembly in both structural showings of the drawing, is prevented by overlying flange 28 of fixed collar 27, and that downward displacement is prevented by the tension of the filament strands attached to the ears of the lower cup. As fixed collar 21 is rigid with respect to post [2, and as ceramic 33 substantially fits upon that collar and within the cups, lateral displacement is prevented.

In order to be assured of no angular or rotational displacement, dowel pins 31 may be secured to the transverse walls of the cups directed inwardly of the cups and into appropriate holes in the ceramic. With the interpositioning of plate 36 between ceramic sections as shown in Figure 5, another dowel. 38 may be provided through said plate and projecting at both ends into the ceramicsections.

The filament current is supplied through centralpost [2 to the fixed collar 21, and thence to the upper cup and one foot portion of the fila ment. Another lead-in connection 39 is soldered or welded to the bottom transverse wall of the lower cup 3|, the ears of which carry the other foot portion of the filament sections. Thus, while the filament may be tensioned by spring pressure, the necessary movement for such tensioning is at the bight portions of the filament sections and requires no movement at the lead-in or foot ends thereof, consequently enabling rigid and inflexible connections to be employed. The structure shown has a further advantage in that the ceramic or annular insulator 33 is physically interposed between the direct line of radiation of heat from the filament to the spring 25, and the ceramic accordingly functions both as an electrical and a heat insulator.

We claim:

1. An electron discharge device comprising a cathode assembly having a filament with a plurality of strands, said filament providing foot portions and a bight portion, a rod support, means slidable on said rod support and carrying said bight portion, a fixed collar on said rod support at the foot portions of the filament, said collar counteracting tension from said foot portions of the filament, and tension applying means interposed between said collar and bight portion.

2. An electron discharge device comprising a cathode assembly having a filament with a plurality of strands, said filament providing foot portions and a bight portion, a rod support, means slidable on said rod support and carrying said bight portion, a fixed collar on said rod support at the foot portions of the filament, said collar counteracting tension from said foot portions of the filament, a spring carried by said collar, and a sleeve around said rod support interposed between said spring and slidable means for applying tension to the bight portion of the filament from the said spring.

3. An electron discharge device comprising a fixed cylindrical and flanged member, a pair of hollow cups on said member, said cups having the hollows thereof directed toward each other, an annular insulator in said cups and around a part of said member, said cups having ears portions whereof project in a common plane radially outward from said annular insulator, and filament strands secured to said ears.

4. An electron discharge device comprising a fixed cylindrical and flanged member, a pair of hollow cups on said member, said cups having the hollows thereof directed toward each other and their edges separated from each other, an annular insulator in said cups maintaining said cups 1 aligned coaxially and said edges separated, said cups each having an annular sequential series of ears, the ears of one cup being situated between ears of the other out of contact therewith, and filament strands secured to said ears.

5. An electron discharge device comprising a fixed cylindrical and flanged member, a pair of hollow cups on said member, said cups having the hollows thereof directed toward each other and their edges separated from each other, an

6. An electron discharge device comprising a filamentary cathode of generally cylindrical form composed of a plurality of hairpin sections each having a pair of strands having foot ends, a

- means for mounting said foot ends and supplying electrical heating current thereto, comprising a pair of hollow cups coaxial with said cathode, said cups having the hollows thereof directed toward each other, an annular insulator in said cups maintaining said cups aligned coaxially, said cups having an annular sequential series of evenly spaced ears, the ears of one cup alternatin in the series with ears of the other cup and each of said ears being out of engagement with ears on both sides thereof in the series, and one ear of one cup having one foot end of one filament section secured thereto and an ear of the other cup having the other foot end of the filament section thereto, whereby said filament section is in electrical series from one cup to the other,

7. An electron discharge device comprising a filamentary cathode of generally cylindrical form composed of a plurality of strands grouped to form successive M-type sections, each strand having a foot end, a means for mounting said foot ends and supplying electrical heating current in series through the several strands forming an M section, comprisin a pair of hollow cups and an interposed washer-like plate coaxial with the cathode, an annular insulator having one section disposed in one cup and engaging one face of said plate and having another section disposed in the other cup and engaging the other face of said plate, said cups and plate having ears projecting radially in a common plane and in a sequential series peripherally of said means, the foot ends of the extreme strands of a M section of the filamentary cathode being connected respectively to ears of the two cups, and the intermediate strands of the M section both being connected to a single ear of the said plate.

8. Mounting means for foot ends of multistrand filaments comprising opposed axially aligned cups having hollows directed toward each other, an insulator in said cups holding the same apart and axially aligned, and ears at the facing edges of said cups, said ears having radially projecting portions, and the radially projecting portions of the ears of both said cups being in substantially a common plane.

9. Mounting means for foot ends of multistrand filaments comprising opposed axially aligned cups having hollows directed toward each other, cars on both cups at the facing edges thereof and having radially projecting portions, all of which are substantially in a common plane and of equal size, the ears of one cup alternating with ears of the other and equally spaced from each other.

10. Mounting means for foot ends of multistrand filaments comprising opposed axially aligned cups having hollows directed toward each other and having a plate interposed between said cups, insulator sections in said cups and engaging said plate at opposite faces thereof, said plate having ears with radially directed portions in the plane of the plate, and said cups having ears with radially directed portions in a plane common to the plane of said plate.

LEO C. WERNER. WILLARD A. LANING.