US3364379A

US3364379A - Aligned-grids electron discharge device and method and apparatus for manufacture thereof

Info

Publication number: US3364379A
Application number: US315920A
Authority: US
Inventors: James C Munday; Junius B Neale
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1963-10-14
Filing date: 1963-10-14
Publication date: 1968-01-16
Anticipated expiration: 1985-01-16
Also published as: DE1906110U; GB1071109A

Description

3,364,379 ETHOD Jan. 16, 1968 .1. c. MUNDAY ETAL ALIGNED-GRIDS ELECTRON DISCHARGE DEVICE AND M AND APPARATUS FOR MANUFACTURE THEREOF 5 Sheets-Sheet 1 Filed Oct. 14, 1963 FIG. I

INVENTORS JAMES C. MUNDAY JUNIUS B. NEALE BY THEIR A ORN Y Jan. 16, 1968 J. c. MUNDAY ETAL 3,3

ALIGNED'GRIDS ELECTRON DISCHARGE DEVICE AND METHOD ARATUS FOR MANUFACTURE THEREOF AND APP 5 Sheets-Sheet 2 Filed Oct. 14, 1963 JAMES C. MUNDAY JU NIUS B. NEALE fig, I

THEIR TOREY Jan. 16, 1968 J. c. MUNDAY ETAL 3,364,379

ALIGNED-GRIDS ELECTRON DISCHARGE DEVICE AND METHOD AND APPARATUS FOR MANUFACTURE THEREOF 5 Sheets-Sheet 5 Filed Oct. 14. 1963 INVENTORS JAMES C. MUNDAY JUNIUS B. NEALE BY THEIR A TOR EY Jan. 16, 1968 .J. c. MUNDAY ETAL 3,354,379

ALIGNEDGRIDS ELECTRON DISCHARGE DEVICE AND METHOD AND APPARATUS FOR MANUFACTURE THEREOF Filed Oct. 14, 1965 5 Sheets-Sheet 4 FIG. 4

INVENTORS JAMES C. MUNDAY JUNIUS B. NEALE Jan. 16, 1968 J. c. MUNDAY ETAL 3,364,379

ALIGNED-GRIDS ELECTRON DISCHARGE DEVICE AND METHOD AND APPARATUS FOR MANUFACTURE THEREOF Filed Oct. 14, 1963 5 Sheets-Sheet 5 l4 l3 I3 l4 10' W //IO' 3 7 N!!! ,34 3g I VIE 33 6 33a U 33a 340, I 340.

F IGQ 5 INVENTORS JAMES C. MUNDAY JUNIUS B. NEALE BY United States Patent 3,364,379 ALIGNED-GRIDS ELECTRGN DISCHARGE DE- VICE AND METHOD AND APPARATUS FOR MANUFACTURE. THEREOF James C. Munday and Junius B. Neale, Owensboro, Ky., assignors to General Electric Company, a corporation of New York Filed Oct. 14, 1963, Ser. No. 315,920 4 Claims. (Cl. 313-350) This invention relates to aligned-grids electron discharge devices, and more particularly to such devices and grids thereof. The invention relates further to a method of, and apparatus for, aligning and mounting grid electrodes in the manufacture of an aligned-grids electron discharge device.

In an aligned-grids electron discharge device, two or more grid electrodes are positioned in the path of electron fiow between the cathode, or electron-emitting electrode, and the anode, or electron-receiving, electrode. The grid electrodes are frequently of the type in which a helix of wire is wound about a pair of parallel support rods and fastened thereto by some suitable technique, such as by welding, or by cutting and swaging 0f the support rods. The grid thus constructed provides a plurality of parallel lateral wires, vertically displaced in accordance with a predetermined pattern and extending between the support rods, the lateral wires being positioned in a direction generally transverse to the path of electron flow from the cathode to the anode.

An electron discharge device employing a plurality of grid electrodes usually is constructed with the grid electrodes positioned intermediate the cathode and the anode electrodes, such as in a tetrode. In a tetrode, the-re usually is provided a generally rectangular-shaped cathode centrally located and vertically disposed within the device, the cathode being surrounded by a control grid electrode which, in turn, is surrounded by a screen grid electrode, the plane of the lateral wires of the grid electrodes being substantially parallel to the major surfaces of the cathode. In addition, an anode is positioned in a vertical plane surrounding the outermost grid electrode and generally parallel to both the lateral wires and the cathode major surfaces. Relative to the cathode potential, the control grid electrode generally is biased to a slightly negative potential and the screen grid electrode generally is biased to an equal, or more positive, potential. Therefore, the screen grid, if directly interposed in the path of electron flow, has a tendency to absorb the impinging electrons of the electron flow with the resultant creation of an undesirable current therein.

One of the most effective ways to shield certain grid electrodes, such as the screen grid electrode, from the electron flow, is to align the lateral wires of such grid electrodes with the corresponding lateral wires of the grid electrode closer to the cathode, the latter in some cases being the control grid electrode, although in pentodes or other multi-grid tubes the aligned grids can be any pair of grids, as desired. In this manner, the lateral wires of the electrodes intermediate the cathode and the anode will lie in a common alignment plane parallel to the path of electron flow and thus in the shadow of the corresponding lateral Wires closer to the cathode.

Various techniques have been practiced heretofore for mounting and aligning grid electrodes in the manufacture of aligned-grids electron discharge devices. Frequently, electrodes of the device are mounted vertically on a horizontally disposed insulating support member, commonly a mica plate. A second insulating support plate, similar to the first, is positioned in parallel relation therewith and vertically displaced therefrom for connection to the opposite ends of one or more of the electrodes.

In one known arrangement for mounting a plurality of grids in aligned relation on an insulating support plate, indexing projections are formed on the opposite ends of the support rods and the lateral wires are wound onto the support rods from a point located a measured distance from the indexing projections adjacent one end of the support rods. The grid electrodes are mounted on the support plate by inserting the support rods into apertures provided therefor in the insulating support plate, the in sulating support plate providing a common base or plane against which the indexing projections abut to assure alignment of the corresponding lateral wires of the plurality of grid electrodes. The other ends of the support rods are positioned within apertures provided in the second insulating support plate, the indexing notches at the other ends abutting the second insulating plate. An anode is mechanically joined to both of the support plates, the support plates thereby being fixed to secure the grid electrodes therebetween.

In this technique, manufacturing tolerances must be extremely exact to provide the alignment required. Further, in operation of the electron discharge device, the grid electrodes becomes heated and consequently tend to expand. The abutting relation of the indexing notches or projections with the support plates, however, prevents axial expansion of the support rods. The force created by the heating, therefore, tends to how the support rods in a lateral or horizontal direction with consequent distortion and misalignment of the grid electrodes.

Alternative prior art mounting techniques, such as welding of the support rods to metal clips provided in the support plates, are also unsatisfactory due to the undesirable heating of the grid electrodes caused by the welding, the heating again effecting distortion and misalignment of the lateral wires.

It is, therefore, an object of this invention to provide a method of and apparatus for aligning and mounting the grid electrodes of an aligned-grids electron discharge device in a precise, but simple and economical, fashion.

It is still another object of this invention to provide a grid mounting structure for an aligned-grids electron discharge device having improved structural characteristics.

It is still a further object of this invention to provide a mounting s-rtucture for an aligned-grids electron discharge device in which the grid electrodes remain in alignment and undistorted by temperature variations.

Further objects of this invention will become apparent as the following description proceeds and the features of novelty of this invention will be pointed out with particularity in the claims which are annexed to and which form a part of this specification.

In accordance with this invention, the vertical support rods of first and second grid electrodes are positioned within apertures provided in a generally horizontal insulating support plate, the support rods extending beyond the top and the bottom surfaces of the support plate. To align the corresponding lateral wires of the grid electrodes, one of the grid electrodes is displaced vertically relative to the other grid electrode by moving its associated support rods in a direction generally transverse to the plane of the support plate. Following the alignment, the support rods are deformed to provide integral projections on the support rods overlying both the top and the bottom surfaces of the support plate in contiguous relation therewith. The integral projections thus serve to mount securely the support rods on the insulating support plate and to maintain accurately in alignment the corresponding lateral wires of the plurality of grid electrodes. A second insulating support plate is positioned in parallel relation with the first insulating support plate and vertically displaced therefrom, the second insulating support plate being provided with a plurality of apertures therein through which the opposite ends of the support rods snugly, yet freely, extend. The first and second insulating support plates are joined mechanically, as by an anode electrode which extends therebetween and is joined to both of the insulating support plates.

For an understanding of the invention, reference may be had to the following detailed description and drawings of one illustrative embodiment of the apparatus of the invention and the completed structure produced in the practice of the method and by the operation of the apparatus of the invention, in which:

FIG. 1 is a fragmentary side elevational view, partially broken away, showing the grid electrodes as initially positioned and supported by the electrode mounting apparatus of the invention,

FIG. 2 is a perspective view, partially broken away, showing the deforming means and the integral projections formed on the support rods of the grid electrodes by the deforming means,

FIG. 3 is a view, partially broken away, taken along the line IlI--III, in the direction of the arrows of FIG. 1 showing the electrode elements as initially positioned and supported by the electrode mounting apparatus of the invention and the deforming means of the invention,

FIG. 4 is a fragmentary perspective view of a detail of our apparatus, and

FIG. 5 is a side elevational view of the aligned grids mounted in accordance with this invention.

In FIG. 1, there is shown base member 1 of the electrode mounting apparatus of the invention. The base is preferably a block of metal or other suitable material, and extending in a vertical direction through the horizontal mounting surface 2 of, and into the base member 1 are a pair of recesses 3 and a pair of threaded apertures 4, the threaded apertures 4 having screw members 5 received therein. The screws 5 are manually operable from the under side of the base 1. A support plate 6, formed of insulating material, such as mica or the like, is held in horizontal position on the mounting surface 2 of the base member 1 and maintained in an aligned position thereon by lugs 7 on the base member 1 which extend through apertures 8 in the support plate 6.

The support plate 6 further is provided with a first pair of apertures 9 and a second pair of apertures 10, the

apertures

9 and 10 being arranged for alignment with the pair of recesses 3 and the pair of threaded apertures 4, respectively. In addition, there is provided an aperture 11 in the base member 1 and an aperture 12 in the support plate 6, the aperture 12 being aligned with the recess 11.

In the perspective view of FIG. 2, there is shown a portion of the support plate 6 and portions of a first pair of parallel vertical support rods 13 and a second pair of parallel vertical support rods 14. A guide 15 is shown over which is positioned a cathode sleeve 15'. A grid electrode 16, formed on the support rods 13 in a prior manu facturing step, is supported by the support rods 13. The grid electrode 16 conveniently may be formed by winding a helix of wire about the support rods 13 and joining the wire to the support rods 13 at displaced locations along the sides thereof by a cutting and swaging operation, as indicated at the positions 17. The operative portion of the grid electrode 16 thus formed comprises a plurality of parallel lateral grid wires 16', 16", extending between the support rods 13 in a direction generally transverse to the path of electron flow, the path being generally normal to the major surface of the cathode 15'. In a similar fashion, a second grid electrode 18, formed on a pair of support rods 14 in a prior manufacturing step, is supported by the support rods 14. A helix of wire, here shown to be larger than that employed in forming the grid electrode 16, is wound about the support rods 14 and joined to the support rods 14 at displaced positions along the sides thereof by a cutting and swaging operation, as indicated at the positions 19, the displacement of the posi tions 19 being equal to that of the positions 17. The grid electrode 18 thus includes a plurality of lateral wires 18', 18", extending between the support rods 14 in a direction generally transverse to the path of electron flow.

As shown in FIG. 1, the first pair of support rods 13 is positioned within the pair of apertures 9 in the support plate 6 and extends from the opposite, or the top and bottom surfaces thereof. An end portion of each of the support rods 13 projects through the apertures 9 and beyond the bottom surface of the support plate 6 for reception within recesses 3 in the base member 1. The pair of recesses 3 maintains the support rods 13 vertically disposed relative to the support plate 6. Similarly, the second pair of support rods 14 is positioned within the second pair of apertures 10 in the support plate 6 and extends from the opposite, or the top and bottom surfaces thereof. An end portion of each of the support rods 14 projects through the apertures 10 and beyond the bottom surface of the support plate 6 for reception within the threaded apertures 4 in the base member 1. The guide 15, shown prior to positioning the cathode sleeve 15 (FIG. 2) thereover, is mounted within the recess 11 in the base member 1 and extends in a vertical direction upwardly through the aperture 12 in the support plate 6. Sufli-cient space is provided between the guide 15 and the walls of the recess 11 in the base member 1 and the aperture 12 in the support plate 6 whereby the cathode sleeve 15 may he slid over the guide 15 and inserted through the aperture 12 in the support plate 6 and into the recess 11.

To exert vertical pressure on the grid side rods '13 and 14, thereby to ensure proper seating of the lower ends thereof in the

recesses

3 and 4, we employ a hold-down fixture 51 comprising a block of metal or other suitable material which is slidable in a vertical direction in a pair of grooves 53 provded in fixed supports 55. The fixture 51 is formed with two pairs of

parallel bores

57 and 59 which are spaced in accordance with the relative spacing of the

grid side rods

13 and 14. The

bores

57 and 59 carry spring

biased plungers

61, 63, respectively, which are suitably disposed in the bores and adapted to contact the free ends of the

side rods

14 and 13 to exert vertical pressure thereon to hold the grids firmly in position in the

recesses

3 and 4.

As noted earlier, it is essential for operation of the electron discharge device that corresponding lateral wires, such as the lateral wires 16 and 18' of the

grid elements

16 and 18, respectively, be aligned with one another in a common alignment plane. This, of course, requires that the

grid elements

16 and 18 be wound on their

related support rods

13 and 14 at an equal or common pitch, which may be visualized as the angular relation of the common alignment plane A-A to the horizontal plane of the support plate 6. Further, the vertical displacement of the successive lateral wires 16', 16", of the grid electrode 16 must be equal to the vertical displacement of the successive lateral wires 18', 18", of the grid element 18. This latter requirement is satisfied by making the displacement of the positions 17 equal to the displacement of the positions 19.

Inasmuch as the support rods 13 are fixed in position relative to the base member 1 by their reception within the recesses 3, which have a fixed depth within the base member 1, the common alignment plane A-A may represent the initial position of a given lateral wire of the grid element 16, such as the lateral wires 16', relative to the horizontal plane of the support plate 6. To align the lateral wires of the grid 18, .with those of grid 16, the screw members 5 are rotated in their threaded apertures by the respective knurled control knobs. Appropriate rotation of the control knobs varies the depth of the threaded apertures 4 and thus moves the support rods transverse to the support plate 6 to vary the vertical displacement of the support rods 14, whereby the axis of the lateral wire 18' is aligned with the common alignment plane A-A and concomitantly with the corresponding lateral wire 16 of the grid element 16. The use of two independent control knobs permits independent control of the vertical position of each one of the pair of support rods 14. It is apparent, however, that if the ends of the support rods 14 are precisely aligned in a horizontal plane, a single control for eifecting merely a common vertical displacement of both of the support rods 14 may be employed in place of the two independent control knobs. In addition, the recesses 3 may be designed in an identical fashion to the threaded apertures 4 and employ identical associated screw members 5 whereby the depth thereof may be adjusted.

Following alignment of the

grid electrodes

16 and 18, the

support rods

13 and 14 are joined to the support plate 6 by the apparatus shown in FIGS. 2, 3, and 4. This apparatus comprises a first pair of opposed dies 20 and 21 positioned contiguous the top surface of the support plate 6 and a second pair of opposed dies 22 and 23 positioned contiguous the bottom surface of the support plate 6, the dies 22 and 23 being received within channel 30 provided therefor on the base member 1. I

Referring to FIGS. 2 and 4, the die 20 includes

mirror image portions

20a and 20b separated by a central portion 20c.

U-shaped grooves

24 and 25 are provided in the die portions 20a and 2012 thereby to define tapered

lip portions

26, 27, and 28. The central portion 20c of the die 20 includes a large U-shaped recess 29 for straddling the position occupied by cathode 15 (which has been positioned over the guide 15) at the central portion of the support plate 6.

The dies 20, 21, 22., and 23 may, if desired, be identical in construction. Using identical, but primed numbers to indicate portions of the die 21 which are identical to those of the die 20, the die 21 similarly includes U-shaped grooves 24 and 25', a large U-shaped recess 29', and tapered lip portions 26, 27' and 28'.

The dies 22 and 23 are mirror images of the respectively vertically displaced dies 20 and 21. Although the dies 22 and 23 are hidden substantially from view, in FIG. 2,

the tapered lip portion 26a of the die 22, and the tapered lip portions 26a and 27a and the U-shaped recess 24a of the die 23 are shown.

In the side view of FIG. 3, the dies 20 and 21 are shown in opposed relation about the support rods, of which only rod 14 can be seen, and contiguous the top surface of the support plate 6, and the dies 22 and 23 are shown in opposed relation about the

support rods

13 and 14 and contiguous the bottom surface of the support plate 6 and within the channel 30 in the base member 1.

As shown more clearly in FIGS. 3 and 4, the dies 20, 22, and 2.1, 23 are similarly constructed and may be formed from integral blocks of suitable material which are machined or milled to provide tine-like cutting edges which are spaced apart by slots 71 and 73- a vertical distance sutficient to permit the support plate 6 to be interposed between the respective dies 20 and 22 and 21 and 23, respectively. The die blocks are further milled to provide a recess as at 75 and 77 to permit the dies to be reciprocated toward and away from the grid side rods in the channel 30 of base 1.

Reciprocation of the dies 20, 22 and 2.1, 23 is effected through a manually operable lever mechanism, which, as shown in FIG. 4, comprises a toggle 81 rotatably supported on a pivot 83 and having a centrally disposed hand bar 85.

Linkages

87 and 89 are pivotally carried at the ends of toggle 81, the

linkages

87, 89, in turn, being pivotally connected to

bent levers

91 and 93, respectively. The latter are pivoted at

points

95, 97 intermediate the ends of the

levers

91, 93, with the relatively shorter lever arms of the respective levers being coupled to the die blocks as at 99, 101. It will thus be seen that movement of hand bar 85 in a clockwise direction about pivot 83 causes simultaneous movement of the die blocks toward each other an amount depending on the angular displacement of the bar 85. Movement of the hand bar in the opposite or counterclockwise direction causes simultaneous movement of the die blocks away from each other an amount depending on the displacement of the bar 85.

Returning now to FIG. 2, it will be understood that the

support rods

13 and 14 and the associated

grid electrodes

16 and 18 are secure-d to the support plate 6 by a deforming operation performed upon the

support rods

13 and 14 by the dies 20 and 23. By movement of the hand bar 85 in a clockwise direction, the

levers

91, 93 are actuated to move the opposed dies 20 and 23 to the closed position. In the closed position, the tapered

lip portions

26 and 26 of the dies 20 and 21 engage and deform side portions of the side rods 14 to form integral projections 33 thereon. Similarly, tapered

lip portions

27 and 27 form integral projections 34 on support rods 14. Likewise,

integral projections

35 and 36 are formed on the support rods 13 by the tapered

lip portions

27 and 27 and the tapered lip portions 28 and 28', respectively. Preferably, the

integral projections

34 and 36 are diametrically opposed to the

integral projections

33 and 35, respectively. Due to the recessed

portions

24 and 25 and the opposed recessed portions 24' and 25 on the dies 20 and 21, respectively, central portions 37 and 38 of the

support rods

13 and 14, respectively, are substantially unaffected by the deforming operation.

As previously discussed, the dies 22 and 23 are identical in structure to the dies 20 and 21 and positioned in respective minor relationship thereto. Thus, in the closed position, the dies 22 and 23 engage and deform the

support rods

13 and 14 at diametrically disposed positions thereof contiguous the bottom surf-aces of the support plate 6. Thus, tapered end portions 26a and 26a engage and deform the support rod 14 to form integral projection 33a. Integral projection 34a on support rod 14 and integral projection 35a on support rod 13 are formed in a similar fashion. From FIG. 5 it is clear that the dies 22 and 23 form a complete set of integral projections 33a-36a on the

support rods

13 and 14 con- "tiguous the bottom surface of the support plate 6 in minor relation to the set of integral projections 33-36 formed on the

support rods

13 and 14 contiguous the top surface of the support plate 6 by the dies 20 and 21.

The manner in which the integral-projections on the

support rods

13 and 14 securely mount the

support rods

13 and 14 to the support plate 6 can be apprcciated'more completely by reference to FIG. 2. The

integral projections

35 and 35a on support rod 13 are shown in the immediate vicinity of the cut-away portions of the support plate 6,- and are seen to be axially aligned and respectively contiguous the top and the bottom surfaces of the support plate 6, thereby securely mounting support rod 13 on the support plate 6. In addition to the portions 37 and 38 left unaffected during the foregoing operation, generally circular portions 39 and 40 on the

support rods

13 and 14, respectively, having a thickness in the axial direction equalto the thickness of the support plate 6, will be partially unaffected by the deforming operation. However, the flow of the metal of the

support rods

13 and 14 in forming the various integral projections 33-36 and 33a-36a tends to expand the material of the support rods intermediate the aligned integral projections 33-3-6 and 33a-36a at the regions 41 and 42 on support rod 13 and the regions 43 and 44 on support rod 14. The expansion of the metal at the regions 41-44 provides an additional interlocking of the

support rods

13 and 14 to the support plate 6 by tightly wedging the

support rods

13 and 14 within the

apertures

9 and 10, respectively.

In FIG. 5, a second support plate 6' is shown provided at the opposite extremity of the

support rods

13 and 14 and is positioned in parallel relation to the support plate 6. Indicating elements of the support plate 6 which are identical to those of the support plate 6 by primed and otherwise identical members, the

support rods

13 and 14 extend freely through the apertures 9" and 10, respectively, in the support plate 6. Likewise, the cathode pass freely through the apertures 9 and 10', respectively,

the

support rods

13 and 14 are free to expand axially upon heating during fabrication and normal operation of the device. Thus, the

grid elements

16 and 18 may expand freely with the respectively associated

support rods

13 and 14; since the expansion occurs without constriction, the

grid electrodes

16 and 18 expand Without distortion and the precise alignment of the corresponding lateral wires is maintained. Similarly, upon cooling of the device, the 1

support rods

13 and 14 contract freely and without constriction or distortion.

Although the invention has been described in relation to the manufacture of an aligned-grids electron dis-- eXtends. u h. thags tliti t 1 P 95 9 1 959 1-- charge device employing frame or wound grid electrodes,

it is apparent that the invention is equally applicable to electron discharge devices employing any type of grid electrodes having lateral wires or conductgrs required to be aligned and support rods which are'to be joined to a support plate. Further; the number of grid electrodes which may be aligned and mounted in accordance with this invention is not limited to that of the embodiment. shown and described. In addition, the disposition of the various elements has been described with regard to hori-- zontal and vertical planes for clarity of description and by no manner in a limiting or restrictive sense.

Many modifications of the method, the apparatus, and the structure of this invention readily will be apparent to those skilled in the art and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the true spirit and scope of this invention;

WhatI claim and desire to be secured by Letters Patent of the United States is;

1. An aligned-grids electron discharge device having at least two grid electrodes supported between a cathode and an anode and a pair of support plates wherein each of saidwgrid electrodesincludes, oppositely disposed support Qr'ods with lateral wires extending therebetween and said support rods are positioned within apertures provided therefor in said support plates and extend from the "opposite surfaces of each of said support plates, said support rods being deformed at points on the sides thereof contiguous the opposite suffacespfenlypne of said supeludes oppositely dispos ed vertical support .rods nit MW lateral wir'es extending therebetween and each of said vertical support rods is posiiioned within vertically aligned apertures provided therefor in each of said horizontal support plates and extends from the opposite surfaces of each of said horizontal support plates, said vertical support rods being deformed to provide integral projections on the sides thereof overlying the opposite surfaces of only one of said horizontal support plates in contiguous relatiori'therewith to mount said grid electrodes thereon, :said integral projections being formed at points on said vertical support rods selected to position the corresponding lateral wires of said grid electrodes in respective common alignment planes, and the opposite ends of said vertical support rods being free to move within the respective apertures in the other of said horizontal support plates to allow axial expansion or contraction of said vertical support rods due to temperature variation in said device.

3. An aligned-grids electron discharge device as recited in claim 2 wherein said integral projections are formed in vertical alignment on each of said support rods on diametrically opposed portions thereof.

4. An aligned-grids electron discharge device comprising at least two frame grid electrodes,--each of said frame grid electrodes including a'pair of oppositely disposed vertical sgpport rods with a helix of wire of constant pitch Wound thereabout and attached thereto for "providing a plurality of lateral wires extending between port plates to mount said grid electrodes thereon; said,

points on the sides of said support rods being selected to position the corresponding lateral wires of said grid electrodes in respective common alignment planes, and the opposite ends of said support rods being free to move within the respective apertures in the other of said support plates to allow axial expansion or contraction of said support rods due to temperature variation in said device.

2. An aligned-grids electron discharge device having at least two planar grid electrodes supported in parallel between vertically disposed cathode and anode electrodes and a pair of parallel and vertically displaced horizontal support plates, wherein each of said grid electrodes in,

said vertical support rods, said frame grid electrodes having successively larger helices of wire wound thereabout for positioning in successive surrounding relation in order of said successively larger helices of wire between a centrally located and vertically disposed cathode and a vertically disposed anode, said anode surrounding said frame grid electrodes, a pair of horizontal and vertically displaced support pla es',each6i" said support plates having vertically aligned pairs of apertures therein corresponding to said pairs of said vertical support rods, said support rods being positioned within the corresponding ones of a said apertures in said horizontal support plates and extending from the opposite surfaces of each of said support plates, said vertical support rods being deformed to provide integral projections on sides thereof overlying the opposite surfaces of only one of said horizontal support plates in contiguous relation therewith to mount said frame grid electrodes thereon, said integral projections being formed at points on said vertical support rods selected to position the corresponding lateral wires of said frame grid electrodes in respective common alignment planes, and the opposite ends of said vertical support rods being'free toamo e itliin the respective apertures in the other of said horizontaT'support'platesato allow axial expansion or contraction of said vertical sup port rods due to temperature variation in said device.

, References Cited UNITED JOHN W. HUCKERT, Primary Examiner.

A. I. JAMES, Assistant Examiner.

Claims

1. AN ALIGNED-GRIDS ELECTRON DISCHARGES DEVICE HAVING AT LEAST TWO GRID ELECTRODES SUPPORTED BETWEEN A CATHODE AND AN ANODE AND A PAIR OF SUPPORT PLATES WHEREIN EACH OF SAID GRID ELECTRODES INCLUDES OPPOSITELY DISPOSED SUPPORT RODS WITH LATERAL WIRES EXTENDING THEREBETWEEN AND SAID SUPPORT RODS ARE POSITIONED WITHIN APERTURES PROVIDED THEREFOR IN SAID SUPPORT PLATES AND EXTEND FROM THE OPPOSITE SURFACES OF EACH OF SAID SUPPORT PLATES, SAID SUPPORT RODS BEING DEFORMED AT POINTS ON THE SIDES THEREOF CONTIGUOUS THE OPPOSITE SURFACES OF ONLY ONE OF SAID SUPPORT PLATES TO MOUNT SAID GRID ELECTRODES THEREON, SAID POINTS ON THE SIDES OF SAID SUPPORT RODS BEING SELECTED TO POSITION THE CORRESPONDING LATERAL WIRES OF SAID GRID ELECTRODES IN RESPECTIVE COMMON ALIGNMENT PLANES, AND THE OPPOSITE ENDS OF SAID SUPPORT RODS BEING FREE TO MOVE WITHIN THE RESPECTIVE APERTURES IN THE OTHER OF SAID SUPPORT PLATES TO ALLOW AXIAL EXPANSION OR CONTRACTION OF SAID SUPPORT RODS DUE TO TEMPERATURE VARIATION IN SAID DEVICE.