US2634384A - Thermal structure for electron discharge devices - Google Patents

Description

April 7, 1953 G. T. FORD ET AL THERMAL STRUCTURE FOR ELECTRON DISCHARGE DEVICES Filed Dec. 1, 1950 3 Sheets-Sheet l INVEN TORS f a. r FORD L E. J. WALSH FIG l 1U /Gu Emu 4225427 8 0 ATTORNEY April 7, 1953 G. T. FORD ET AL 2,634,384

THERMAL STRUCTURE FOR ELECTRON DISCHARGE DEVICES Filed Dec. 1, 1950 3 Sheets-Sheet 2 FIG. 3

G. 77FORD uvvavroes El WALSH ATTORNEY April 7, 1953 G. T. FORD ET AL 2,634,384

THERMAL STRUCTURE FOR ELECTRON DISCHARGE DEVICES Fil'e d D60. 1, 1950 3 Sheets-Sheet I5 FIG. 5

i1: 88 4 76 75 f 87 9 I l i I G TFO/PD INVENTORS EJ WALSH BY ATTORNEY Patented Apr. 7, 1953 UNITED STATES ATENT OFFICE THERMAL STRUCTURE FOR ELECTRON DISCHARGE DEVECES Application December 1, 1950, Serial No. 198,598

12 Claims. 1

This invention relates to electron discharge devices and, more particula ly, to an envelope and lead-in structure for such devices.

In high gain, broad-band electron discharge devices operable at high frequencies, such as are employable in mobile radio equipment, it is desirable to reduce the lead inductance of each internal element to a minimum. This allows for more efficient operation of the device. It is also desirable to have sufficient capacitance between certain of the individual elements of the device to provide advantageous by-pas condenser action.

Thus, in the operation of such devices, one electrode of the device may be connected. to ground. If the device is a tetrode, the cathode may advantageously be grounded; and, similarly, if the device is a triode, it may advantageously be employed with grounded-grid circuits. In order to attain efdcient and stable operation, is advantageous to have a certain minimum capacitance between certain of the various internal elements of the device and the grounded electrode.

Priorly, minimum by-pass capacitances have been obtained by external circuit elements or by internal elements which are relatively large and cumbersome. In minute electron discharge devices, space becomes of importance, and large bypass capacitance elements internal of the tube envelope become objectionable. However, it is difficult, if not impossible, to attain these capaci" tances in prior art structures without consuming a considerable amount of valuable space.

Further, in certain electron discharge device applications, it desirable not only to have a certain minimum value for these capacitances between the elements of the device but, in fact, to predetermine the capacitance within well-defined limits.

It is, therefore, one object of this invention to reduce the inductance of the leads of elements of electron discharge devices.

It is another object of this invention to provide greater than a minimum capacitance between certain of the elements of the device, thereby defining by-pass condensers between these elements.

It is a further object of this invention to simplify the construction of electron discharge devices of the above-mentioned type.

It is a further object of this invention to improve the envelope of electron discharge devices and to provide an envelope easily positioned in and electrically connected to a mating socket or holder.

It is a still further object of this invention to improve the operation of electron discharge devices.

These and other objects of this invention are achieved in accordance with one specific embodiment of this invention in which the envelope of an electron discharge device comprises a plurality of discs accurately positioned adjacent each other but insulated from each other. Each of the discs is internally connected to an element of the electron discharge device.

In one particular illustrative embodiment of this invention, a tetrode, such as may advantageously be employed in grounded cathode operation, comprises a large cathode lead-in disc which extends through and constitutes a portion of the envelope of the device. Seriately closely adiacent thereto but insulated from each other are similar low inductance lead-in discs for the two cathode heater leads and for the screen electrode. By-pass capacitances are thus defined by the lead discs extending through and comprising a portion of the envelope of the device between the cathode heater leads and the screen electrode to the grounded cathode.

In this specific illustrative embodiment of this invention, the low inductance lead-in discs, which both define oapacitances and are themselves the terminals of the device, are of decreasing size, thereby enabling the device to be facilely seated in a cooperating socket which makes connection to the discs and thereby to the various internal elements of the device.

In another particular illustrative embodiment of this invention, a triode, such as may advantageously be employed in grounded-grid operaion, includes low inductance lead-in discs extending through and comprising a portion of the envelope and defining the terminals for the control electrode and the heater leads.

It is, therefore, one feature of this invention that the envelope of an electron discharge device comprise a plurality of closely spaced discs extending therethrough and to which elements of the device are electrically connected. Advantageously, the discs may, in fact, support and position certain of the elements within the device; In accordance with this feature, low inductance lead-in connections for the elements of the device are attained.

It is a further feature of this invention that the discs be closely positioned adjacent each other and insulated from each other, whereby interelement by-pass capacitances are defined. In accordance with this feature, the discs are advantageously spaced from each other by a di electric material which seals directly to the discs,

such as powdered glass. More specifically, it is a feature of this invention that the spacing between the discs be of the order of a few mils.

It is a further feature of this invention that the discs extending through the envelope and comprising a; portion of the envelope of an electron discharge device may be of decreasing diameter.

A complete understanding of this invention and of these and other features thereof can be attained from consideration of the following description and the accompanying drawing, in which:

Fig. 1 is a perspective view of an electron discharge device illustrative of one specific embodiment of this invention;

Fig. 2 is a sectional view of the device of Fig. 1 taken along plane 2-2 of Fig. 1;

Fig. 3 is a sectional view of the device of Fig. 1 along line 33 of Fig. 2;

Fig. 4 is a sectional view of the device of Fig. 1 along line 44 of Fig. 3; and

Fig. 5 is a sectional view of an electron discharge device illustrative of another specific embodiment of this invention.

Referring now to the drawing, the illustrative embodiment shown in Fig. 1 comprises an electron discharge device having an envelope including an upper stem or bulb portion It, a lower stem or bulb portion ll, and a plurality of discs l2, 13, M and I5 situated between the two stem portions I B and H. The uppermost disc l2, as best seen in Figs. 2 and 3, comprises two sections it and H. The discs are advantageously of different diameters, the diameter increasing progressively from the bottom disc [5 adjacent the lower stem portion H to the uppermost disc i2 adjacent the upper stem portion ill. A thin layer of an insulating and dielectric material [8, such as a powdered glass or glaze, is sealed between the discs [2, l3, I4 and lb. The accurate spacings of the discs from each other may be obtained by positioning insulating spacers between the discs, the spacers being of a material having an expansion characteristic campatible with that of the glass or glaze employed between the discs, as further disclosed in the application of E. J. Walsh, Serial No. 198,597, filed December 1, 1950. Ribs or support cores may also extend through apertures in the discs between the upper and lower stem portions l0 and H of the envelope to strengthen the seals between the discs, as is also more fully disclosed in the above-mentioned application.

An electrode terminal pin extends centrally through the lower glass portion II of the envelope of the device of Fig. 1, and an anode terminal pin 2! extends through the upper glass portion I B. An exhaust tabulation 22, as best seen in Fig. 2, is sealed in the glass portion it or the device may advantageously be exhausted through a hollow anode pin 2 I.

Within the envelope thus defined by the stem portions Ill and H and the discs [2, i3, is and I5, separated from each other and sealed to each other by the interposed insulating material 58, may be positioned the various electrodes and other elements of the electron discharge device. In the illustrative embodiment disclosed in Fig. 1, the electrodes constituting a tetrode are positioned within the envelope thus defined, but this invention is not to be considered in its broad aspects as limited to any particular number of electrodes or arrangement thereof. As best seen in Fig. 2, the electrode unit comprises a fiat hollow cathode as having a heater element 25 therein. The heater element 25 has tabs 26 and 2?, one at each end, just beneath the cathode 24. The cathode itself is supported between an upper insulating support 28 and a lower insulating support 29, both of which may advantageously be of mica and which are themselves advantageously supported in the device as explained further below. The cathode 2 also may have embossments 3! on its sides adjacent the lower support 23 to position the cathode 2 3 between the supports 28 and 2%, as is known in the art.

A first or control electrode 32 comprises a plurality of lateral wires 33 wound around a frame comprising two side rods 35 and end straps 38. The electrode 32, which may advantageously be fabricated in accordance with the application Serial No. 52,020, filed September 36, 1948, encompasses the cathode 25. The side rods 35, in the particular illustrative embodiment disclosed in the drawing, are secured to the terminal pin 28, as by being welded to a central surface 35 cut in the pin 29, as best seen in Fig. 3. The control electrode 32 is in turn encompassed by a screen electrode 3? also comprising a plurality of lateral wires 38 wound around two side rods 3%.

In accordance with features of this invention, the electrode mount may advantageously be supported by the discs extending through and forming a portion of the envelope of the device. Thus, in the embodiment disclosed in Fig. 1, as best seen in Fig. 2, the bottom disc :5 has formed integral therewith a plurality of fingers ii which are bent perpendicular to the plane of the disc I5 and extend axially in the device. These fingers ii are secured to and support a thin metal plate 42, having an aperture it therein through which the electrodes of the device extend. The lower support member 25, which is preferably of mica, is positioned on top of the plate 32 and secured thereto, extending across the aperture 43. As best seen in Fig. 2, the plate 32 has two fingers 35 depending therefrom, the side rods 3.? being secured thereto. The disc 15 is thus electrically connected to the screen electrode 3? through the plate 42 and defines a low inductance lead-in terminal therefor.

The upper insulator support 28 is similarly secured to a thin metal plate 56 which has a central aperture therein through which the cathode and electrodes extend. The upper plate at is supported from the lower plate 12 by two side rods 4? each secured to thin L-shaped metal tabs 2-8, in turn secured to narrow portions 69 and 55.! of the thin metal plates 42 and respectively, which are bent around the insulator supports 23 and 28, respectively, as best seen in Fig. 2 with respect to the upper plate 46 and insulator 26. The electrode mount, comprising the upper and lower insulators, cathode, heater, and electrodes can thus be entirely supported in accordance with this invention by one of the disc terminals extending through and forming a portion of the envelope of the device.

The screen electrode 31 in the specific embodiment of this invention illustrated in the device of Fig. 1 is electrically connected to the lowest disc l5 and the control electrode to the control electrode terminal pin 20 extending through the lower bulb portion II. The heater is advantageously connected to the disc terminals [3 and it as by tabs 52 and 53 extending from the short tabs 23 and 21, respectively, attached t the heater ends. As best seen in Figs. 3 and 4 the lower metal plate 42 has a wide open portion at one side thereof and the lower section I? or the upper disc I2 has a mating cut-out portion to allow the tabs 52 and 53 to be placed flat on the discs [3 and is, respectively. As best seen in d the disc l3 itself has a cut-out portion to allow passage of the tab 53 to the lower disc id.

The cathode is similarly secured by a tab 55 to the lower portion l! of the disc l2, the lower metal plate 42 also having a cut-out portion to allow passage of the tab to the disc. While not necessarily limited thereto, the tabs 52 and 53 and tab 55 are advantageously secured to their respective disc terminals at opposite sides of the device.

The anode 56 of the device may be a U- shaped plate having a central portion 51 secured to the anode terminal pin 2| and side portions 58 extending opposite the flat portions of the cathode 2d, the side or active portions 58 being spaced from the screen electrode 31, as best seen in Figs. 1 and 3. The central portion 5'! of the anode 56 is electrostatically shielded from the control electrode 32 by thin fiat integral eX- tensions B0 of the sides of the cathode 24 which are bent over between the upper ends of the control electrode side rods 34 and the central portion 51 of the anode 56, as best seen in Fig. 2.

A getter 61 is advantageously positioned in a trough 52 secured to one of the outer side rods 41.

In the fabrication of the illustrative embodiment of this invention shown in Figs. 1 through 4, the device is advantageously assembled as three distinct units. These units are the electrode and cathode assembly, the lower stem portion and concentric discs, and the upper stem portion. The electrode and cathode assembly is secured to the lower stem portion by securing, as by brazing or welding, the fingers M of the disc to the L-shaped members 48 secured to the bottom plate 42 and to the outer side rods 41'. The tabs 52, 53 and 55 are then advantageously secured to their respective lead-in discs and the control electrode side rods 34 to the control electrode terminal pin 26 in the base of the lower stem portion H.

The upper stem portion ill is advantageously fabricated with the upper disc 15 of the cathode lead-in terminal l2 sealed thereto, as by being sealed to a circular ridge 63. After the electrode assembly is secured and connected to the lower stem portion and the disc terminals, the upper stem portion is placed over the lower stem portion, the disc to being on top of the disc ll, and the device sealed by securing the discs 55 and I! together, as by welding or brazing. The discs l6 and I! advantageously have mating cut-out portions in their peripheries forming a groove 5 in which a ring or rings of brazing solder 55 may be placed, the solder 55 sealing the discs together following the brazing operation. The device can then be evacuated and the exhaust tubulation 22 sealed.

An appreciation of the size of the particular illustrative embodiment oi this invention described above can be obtained from the following spacings:

Inches Between the cathode and control electrod .0025 Between the control and screen e1ectrode .0174 Between the screen electrode and anode .100

Further the thin layer iii of glass or other dielectric material capable of sealing to the disc terminals may advantageously be of a thickness of the order of a few mils or even less, depending on the by-pass capacitance desired.

In this particular illustrative embodiment of this invention, capacitances are thus defined between the cathode, which may advantageously be connected in the circuit to ground, and the heater leads and screen electrode. These capacitances are thus lay-pass condensers built into the envelope of the device and provide the desired capacitances between the elements of the device for proper, eiiicient, and stable operation. The particular internal elements to be connected to the various discs will depend primarily upon the circuit arrangement with which the device is in cooperable relationship. Thus in accordance with this invention the particular element to which the capacitances are referred, which in this case is the disc l2 and thus the cathode 24, and the seriate arrangement of the capacitances can be varied in various embodiments of this invention, in accordance with the circuit desiderata which make it desirable that certain inter-element capacitances are either of a certain predetermined value or above a certain minimum value. In each case, however, these inter-element capacitances are defined by seriately arranged discs, closely spaced adjacent each other but insulated from each other by a dielectric which seals the discs together, the discs forming a portion of the envelope of the device and eX- tending therethrough and the discs also providing the low inductance terminals for the internal elements of the device.

Further, in accordance with this invention, certain of the discs may be segmented, the segments thereof insulated from each other, each segment thus being connected to an internal element of the device and defining a by-pass capacitance between that element and another element within the device. Thus the specific illustrative embodiment of Figs. 1 through 4 may be varied by having but three disc terminals seriately arranged and comprising a portion of the envelope of the device, the middle terminal being in two equal segments, each of which is connected to one of the ends of the cathode heater.

In the particular illustrative embodiment shown in Figs. 1 through 4, the upper and lower stem or bulb portions 59 and It are both advantageously of glass, though other envelope materials or combinations of materials may be employed, as is known in the art. And the sides of the cathode 22d opposite the active anode portions 55 advantageously have coated thereon an electron emissive coating, such as of barium and strontium oxides.

Referring now to Fig. 5, there is shown another specific illustrative embodiment of this invention comprising a triodc such as may advantageously be employed in grounded grid or control electrode operation. The electron discharge device there illustrated comprises an upper bulb portion 55, advantageously of glass, having a metal cup 67 secured centrally thereto. An anode terminal pin 68 extends through the metal cup El, the pin having formed integrally therewith a U or horseshoe-shaped anode with side portions 69 extending into the device. A lower bulb portion II, also advantageously of glass, has a hollow metallic tubing 72 located centrally therein, the tubing being the exhaust tubulation of the device and also the cathode terminal pin. Positioned between the upper and lower bulb portions and comprising with them the envelope ofthe device are three metallic discs l3, l4 and 15 separated from each other by a thin layer 15 of an insulating material, such as a powdered glass or glaze. The disc 13 may be advantageously of a larger diameter than the disc 14 which in turn is advantageously of a larger diameter than the disc 75 to fit one particular mating socket that may be employed. However, the discs may also be of equal diameter.

An internal plate or disc 78 is positioned from the uppermost disc 73 by an insulator support is, but is electrically connected to the disc it, as by rivets, not shown, extending through the internal disc '18, the insulator support iii, and the envelope disc IS. The internal disc 13 in turn supports the control electrode 3! of the device, which may advantageously be an inverted U- shaped frame 82 having a narrowed central portion 83 to extend through an aperture in an upper insulator cathode support E l positioned between the two depending arms 69 of the anode. irans verse fins 85 may advantageously extend from the Ushaped electrode frame 82 to aid in cooling the electrode.

The cathode, not seen in Fig. 5, is advantageous ly a fiat hollow cathode similar to cathode 2d of the device of Figs. 1 through 4 and is positioned between the upper cathode support member 8 and the support member '19, both of which may advantageously be of mica, within the U- shaped electrode frame 82. The side portions of the cathode facing the depending arms 59 of the anode advantageously have coated thereon an electron emissive coating, as is known in the art. A flat tab 87 extends from the cathode into the exhaust tubulation T2, to which it is secured on the closing oil exhaust tubulation i2 following evacuation of the device.

A heater element, not shown, extends with in the cathode and has its two ends connected by 38 and as to the terminal discs is and iii. In this particular embodiment of this invention, the three terminal discs 13, i i and 15 thus provide low inductance leads for the heater and the control electrode and define by-pass capacitances between the heater ends and the control electrode, which may advantageously be grounded during the operation of the device.

It is to be understood that the above-described arrangements are illustrative of the application of the principles of the invention. Various other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. An envelope for an electron discharge device comprising an upper bulb portion, a lower bulb portion, a plurality of concentrically aligned annular disc-shaped terminals sealed between said upper and lower bulb portions, a thin layer or" a vitreous material interposed between said discshaped terminals and sealing said terminals in close proximity to each other, the spacing between said terminals being of the order of a few mils, whereby said vitreous material forms the dielectric of capacitances defined by said closely spaced disc-shaped terminals.

2. An electron discharge device comprising an envelope, a plurality of electrode elements with in said envelope, a plurality of fiat annular members comprising a portion of said envelope and extending therethrough, said elements being electrically connected to said fiat annular members, and vitreous sealing layers of a few mils thickness between said annular members, said annular members being closely adjacent each other and defining capacitances between said elements.

3. An electron discharge device comprising an envelope, means defining an electrode assembly including a plurality of electrical elements within said envelope, and a plurality of conducting annular members concentrically aligned and forming a portion or" said envelope, said elements being separately connected to said annular members, and a layer of insulation of less thickness than said members between said annular members and sealed thereto, said annular members defining capacitances between said elements.

a. An electron discharge device comprising an envelope, said envelope comprising an upper bulb portion, a lower bulb portion, a plurality of concentrically aligned disc-shaped lead-in terminals seriately sealed between said bulb portions, and insulating means between substantially all of the adjacent surfaces of said terminals and sealing said terminals in close prox, ty to each other, an electrode assembly within said envelope including a plurality of electrical elements, and means electrically connecting said elements to said lead-in terminals, said lead-in terminals defining capacitances between said elements.

5. An electron discharge device in accordance with claim 4 including means secured to one of said terminals and supporting said electrode assembly.

electron discharge device comprising an 0. upper bulb portion, a lower bulb portion, a plurality of concentrically aligned disc-shaped leadin terminals sealed between said bulb portions, insulating means between said terminals and sealing said terminals to each other in close proximity to each other, said bulb portions, terminals, and insulating means defining an envelope, an anode, cathode, cathode heater means, and electrode all within said envelope, and means electrically connecting said cathode, cathode heater means, and said electrode to said terminals, said lead-in terminals defining capacitances between said cathode, heater means, and electrode.

7. An electron discharge device in accordance with claim 6 wherein said insulating means is a thin layer of a vitreous material and the spacing between said disc-shaped terminals is of the order of a few mils.

8. An electron discharge device comprising an upper bulb portion, an anode terminal pin extending through said upper bulb portion, a lower bulb portion, an electrode terminal pin extending through said lower bulb portion, a plurality of planar lead-in terminals sealed between said bulb portions, insulating means sealed between said lead-in terminals, said lead-in terminals being positioned closely adjacent each other, anode means supported by said anode terminal pin, a first electrode means supported by said electrode terminal pin, a cathode, cathode heater means, second electrode means, means supporting said cathode, cathode heater means, and second electrode means from one of said planar lead-in terminals, and means connecting said cathode, cathode heating means, and second electrode means to said planar lead-in terminals, said terminals defining canacitances between said oath ode, cathode heating means, and said second electrode means.

9. An electron discharge device comprising a lower bulb portion, a first disc-shaped lead-in terminal sealed to said lower bulb portion, an

upper bulb portion, a second disc-shaped lead-in terminal sealed to said upper bulb portion, a pair of disc-shaped lead-in terminals positioned between said first and second terminals, said terminals being concentrically aligned and being positioned closely adjacent each other, a thin layer of glass sealed between said terminals, a first terminal pin extending through said upper bulb portion, a second terminal pin extending through said lower bulb portion, insulating support means, means supporting said insulating support means from said first disc-shaped terminal, a fiat hollow cathode positioned by said insulating support means, a tab electrically connecting said cathode to said second disc-shaped terminal, a cathode heater within said cathode, tabs electrically connecting the ends of said heater to said pair of disc-shaped terminals, a first electrode encompassing said cathode, said electrode including side rods secured to said electrode terminal pin, a second electrode encompassing said first electrode, said second electrode including side rods, a plate secured to said insulating support means and electrically connected to said first disc-shaped terminal, said plate having dependent fingers, said second electrode side rods being secured to said fingers, a, U-shaped anode enveloping said second electrode and secured at the base of said U to said anode terminal pin and integral extensions of said flat cathode electrostatically shielding said anode, whereby said disc-shaped terminals define capacitances be tween said cathode, cathode heater, and second electrode.

10. An electron discharge device in accordance with claim 9 wherein said first disc-shaped terminal has the smallest diameter of said discshaped terminals and said diameters increase in ascending order until said second disc-shaped terminal and the spacing between said terminals is of the order of mils.

11. An electron discharge device comprising an upper bulb portion, a lower bulb portion, three disc-shaped lead-in terminals sealed between other of said terminal means, a control electrode electrically secured to one of said disc-shaped terminals, and a cathode heater electrically connected between the others of said disc-shaped terminals, said disc-shaped terminals defining capacitances between said control electrode and said heater.

12. An electron discharge device comprising an upper bulb portion, a U-shaped anode secured to said portion and extending therethrough, a lower bulb portion, a metal exhaust tubulation extending through said lower portion, three disc-shaped lead-in terminals sealed between said bulb portions, a thin layer of glass between said discshaped terminals and sealing said terminals to each other in close proximity to each other, the thickness of said layer being of the order of a few mils, a first insulating support member and an inner disc member secured to the uppermost of said disc-shaped terminals, a fiat hollow cathode supported by said first insulating support member and extending between the arms of said U-shaped anode, a tab electrically connecting said cathode and said exhaust tubulation, a U- 4. shaped electrode frame supported by said inner disc member and enveloping said cathode, the bottom of said U being flattened, a second insulating support member fitting over said flattened bottom and also positioning said cathode, a helical control electrode wound around said electrode frame, fins extending from the arms of said U- shaped electrode frame member, a cathode heater within said cathode, and tabs electrically connecting the ends of said heater with the other of said disc-shaped terminals, said disc-shaped terminals thus defining capacitances between said electrode and said heater.

GAYLON T. FORD.

EDWARD J. WALSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,043,733 Brasch et a1 June 9, 1936 2,428,661 Fitzmorris Oct. 7, 1947 2,460,141 McArthur Jan. 25, 1949

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