US2413006A - Electrode assembly for discharge tubes - Google Patents

Description

Dec. 24, 1946. L, E E 2,413,006

ELECTRODE ASSEMBLY FOR DISCHARGE TUBES Filed Dec. 17, 1941 Patented Dec. 24, 1946 stso'rn'ons ASSEMBLY FOR DISCHARGE TUBES Percy L. Spencer, West Newton, Mass, assigncr,

by m'esne assignments, to Baytheon Manufacturing Company, a corporation of Delaware Application December 17, 1941, Serial No. 423,308

8 Claims.

Thi invention relates to an electrical space discharge device in which the dimensions of the device are reduced to relatively small values. This invention also relates to the method of constructing the same. v

In an electrical space discharge device employed in high frequency circuits it has been found advantageous to employ electrodes of relatively small dimensions. Where such tubes are designed for high amplification it has been desirable that the electrodes be arranged relatively close together. In such a device the assembly of the electrodes on a' mass production basis presents various difficulties because of the relatively small size and close spacing thereof. Moreover since such a spacing oi the electrodes in a high gain, high frequency device of the character described is relatively critical, the further difliculty of achieving accurate spacing between the electrodes, so as to produce electrical space discharge device of uniform operating characteristics, is encountered when using standard methods of manufacture and standard types of construction.

When devices of the character described are subjected to extreme shock, as for example when they are located in rapidly acceleratingbodies, a still further difficulty is encountered. Because of the relatively mall size of theelements and the necessity for close spacing thereof,-it has proven diflicult to construct them sturdily or to assemble them in a relatively shock-proof construction.

t is of course obvious that While I have mentioned difliculties encountered in the manufacture and in the structure of high frequency, high gain electrical space discharge devices ofrelatively small dimensions, these difiiculties are also present to a greater or lesser degree in all types of electrical space discharge devices having relatively small dimensions.

An object of this invention is to provide a novel method of constructing and a novel arra'ngement of the electrode assembly whereby the electrodes may be easily and quickly assembled and thereafter handled as an integral unit, this novel method and arrangement being adapted for mass production.

Another object of this invention is to provide a novel method for construction and a novel arrangement of the electrode assembly whereby the electrodes are automatically accurately spaced from each other. Despite the r elatively small dimensions of the" elements included in the electrical assembly it is feasible to employ the or- 2 dinary operatorin manufacturing in accordance with this invention. No unusual skill is necessary to assure accuracy in the spacing of the electrodes. g V y A furtheri mportant objector the present invention is to provide a method of construction and a novel arrangement of the electrode assembly whereby said assembly is capable of withstanding relatively severe shocks without damage thereto.

Other" objects and advantages of this invention willbecome apparent and the foregoing ob- J'ects will be best understood from the iollqwin description of an exemplification thereof, reference-being had to the accompanying drawing wherein: W I

Fig. 1 is an enlarged cross-sectional new of a tube embodying my invention, said new being taken along line l i of Fig. 2 h

Fig. 2 is enlarged cross se'ctional'vie'w taken along line 2-2 of Fig. 1; V

Fig. 313 an enlarged exploded view or the ele merits illustrated in Figs. 1 and'Z; the glass enve'lope and lead-in wires beingomittd; and

Fig. 4 is an enlarged perspective View of part of the electrode assembly illustrated in" the prior figures," the anjodesb'eing omitted'and'the lead-in wires and-eathode-supporting spring being shown fragmentarily.

The electrode space" discharge device illustrated is a tube I having an envelope 2 of som suitablematerial such as glass. 7

A directly heated filamentary cathode 3' is formed in the shapeof an'inverted V; It is suspended in theassembly from its apex 4, the free ends 5 thereof being connected as will bedescribed hereinafter. i

When assembled with the other electrodes the cathode is arranged so that 'it is substantially flat and lies in a lane substantially parallel to the planes in whichthe other electrodes lie.

The grid 6 is formed in two sections l and 3; each of said sections consisting of a pair of P- shaped frames 9' of any suitable material such as nickel. having the edges of i a fine wire mesh It arranged therebetweeh along; the closed portions of the P, as illustrated in Fig. 3, and welded thereto and to each other. H

, In order to arrangethe grid so that it may be interposed between the cathode and anode I prefer to upset each of the sections 1 and 8 to forth therein relatively shallowv pans I! and I2 respectively. These pans H and l- 2 are then arrange'dopposite each other to form an opening l3 therebtween in which the cathodefi is arranged. To provide means for fastening the sections 7 and 8 together, flanges M are formed on opposite ends of each of the U-shaped pans H and i2. These flanges are thereafter welded together to thereby form a unitary grid electrode. The legs of the P-shaped frames 9 are thereby arranged against each other to form a tab l6 by which the grid 6 may be connected to its lead-in.

The grid 6 is substantially flat and when arranged in the assembly lies in a plane substantially parallel with the planes in which the other electrodes lie.

In order to separate the electrodes I prefer to provide insulating members I1, l8, and I9, said members being substantially flat and of predetermined thickness. These members may be made of any suitable insulating material, such as,

for example, mica. The insulating spacer member |9 may be a single spacer or, as shown, a plurality of spacers which when joined have the desired thickness, spacers I! and I8 together being preferably as thick as spacer l9. These members serve not only to insulate the electrodes from each other but also to provide accurate spacing thereof, the accuracy of the spacing depending solely on the accuracy with which the insulating spacing members are made. Since. however, accurate control of the thickness of such spacers is readily feasible in standard manufacturing processes, this offers no difilculty.

In order to permit the electronic discharge to pass unimpeded directly from the cathode to the anode I prefer to provide openings 20, 2|, and 22 in insulating spacer members l1, I8, and I8 respectively. The insulating spacer members is and I8 are arranged adjacent and abutting grid 6. In order that these spacers may be interlocked with the grid so 2,8 to prevent relative movement thereof the openings 2| and 22 are made of such dimensions so that the pans H and I2 of the grid 6 fit snugly within the openings 2| and 22, so the vertical portions 23 of spacers 8 and I9 abut the flanges 4.

It will therefore be seen that the grids and the insulating spacer members l8 and H) are thereby interlocked so as to prevent relative movement thereof in a vertical plane when said elements are arranged as shown in Fig. 1.

Spacer I! is especially designed so as to provide a convenient means for fastening the free ends 5 of the cathode 3. For this purpose the spacer |1 is preferably longer than the other spacers so that the lower horizontal portion24 thereof extends below the other spacers when the electrode assembly is completed, as can best be seen in Fig. 4.

The free ends 5 of the cathode 3 are preferably secured as by welding to metal straps 25, which straps may be arranged on horizontal portion 24 of spacer II. To secure the straps in position I prefer to provide vertical slots 26 in the horizontal portion 24, said slots being spaced and extending into opening 20.

The. straps 25 formed from a strip of a suitable metal, such as nickel, each have one end 21 thereof doubled over the horizontal portion 24 adjacent the slots 26 so that a portion of each strap lies within its corresponding slot. These straps are bent tightly around the horizontal portion 24 and the ends 2'! of each of these straps are welded to the main portion thereof, thereby fixing the straps in position. The free ends 5.

bly between the spacers 8 and I9, are bent over to the straps 25 and welded thereto.

Upon assembly when the cathode 3 is arranged within the grid opening I 3 the upper horizontal portions 28 and the lower horizontal portions 29 of the insulating spacer members l8 and I9 are immediately adjacent the cathode and the lower portion 29 of l8 abuts the same. These horizontal portions help to position the cathode within the grid opening I 3.

The anode 3D is preferably made of a pair of flat plates 3| upset to form channels 32 which are arranged opposite each other to provide an opening 33 therebetween within which opening the various elements are arranged.

Flanges 34 on either side of the channel 32 are provided, said flanges 34 being welded together to secure the plates together and thereby form the integral anode 30.

In order to prevent relative movement between the insulating spacer members and. the plates 3| of the anode, the horizontal portions 28 and 28 of insulating spacer members l8 and Hi and the horizontal portions 24 and 35 of insulating spacer member l which project above and below plates 3| are extended horizontally so as to form shoulders 36 between which the anode plates 3| are held.

As will be seen the plates 3| of the anode prevent the elements forming the electrode assembly from spreading in a horizontal plane, while the shoulders 36 which-interlock the spacers and the anode prevent displacement in a vertical plane. Since spacers 8 and I9 are also interlocked with the grid 6, the grid too is secured against such displacement of these shoulders.

To further insure a sturdy shock-proof structure the upper horizontal portions 28 of the insulating spacer members l8 and 9 and the upper horizontal portion 35 of spacer I"! are preferably provided with horizontal slots 3'! extending inwardly from the opposite ends of these portions. A metallic band 38 is passed through said slots 21 around said portions and the ends thereof are welded together.

To support the cathode 3, a spring member 39 is provided having at one end thereof a hook 48 on which the apex 4 of the cathode 3 is hung, the opposite end of said spring member 38 being welded to the band 38.

In constructing an electrode assembly it is preferred that a ring 4% of suitable getter material be joined to the assembly by arranging said ring above the electrodes and securing it as by welding to a supporting member 42 which may in turn be welded to the band 38.

Before the assembly begins the straps 25 are secured in' position on the lower horizontal portion 24 of spacer member i? and the grid sections are welded together. The anode plate 35 is arranged on a suitable supporting surface and spacer I9, grid 6, spacer I8, spacer i1, and the upper anode plate 3| are placed thereon successively in the order named. The anode plates are welded together. The band 38, which preferably has the spring 38 welded thereto as well as the supporting member 24 which in turn is welded to the getter ring 4|, is then arranged within slots 3'! and the ends thereof welded together.

' The cathode 3 may. next be inserted in opening I3 of the grid and the free ends. 5 thereof are bent.v

over towards the straps 25 and weldedthereto;

while the apexd is arrangedv over the hooklfl' and maintained undertension by the spring 38.-

It will be seen that I have here provided an integral electrode assembly which can be handled as a unit. It will be further seen that the electrodes and insulating spacer members of this unit which are arranged to lie substantially flat are stacked in layers lying in substantially parallel planes.

Lead-in wires for the electrodes maybe provided as follows: lead-in 43 may be connected to the flange 3d of the anode 3D; lead- ins 44 and 45 welded to straps and lead-in 46 to tab iii of the grid.

The assembly as herein above described is thereafter inserted within the glass envelope 2.

A press 41 is formed at the bottom of the envelope 2 and seals the lead-ins therein, thereby providing support for the electrode assembly. The electrodes are heated to drive off the occluded gases and the getter ring 4! is flashed to release the getter material while the tube I is being evacuated through the tip 48. The tip 48 is thereafter sealed.

It may be pointed out that the electrode assembly is a unit and can be handled as such in mass production. Since the accuracy of spacing is dependent solely on the dimensions of the spacers and electrodes, highly skilled operators are unnecessary despite the relatively small dimensions of the elements. By the method and arrangement hereinabove described I have been able to produce tubes of a very small size on a mass production basis. For example, tubes of the type hereinbefore described and made according to this method have been constructed on a mass production basis, the outside overall dimensions of said tubes being .275 inch thick, .365 inch wide,

and 1 inches long.

This arrangement has proved so sturdy that during tests in which the assembly has been placed in several glass tubes successively and the glass broken away, the only parts damaged were the getter ring and the cathode. Tubes made in accordance with this invention have been placed in a centrifuge and the Weight thereof increased from a few ounces to about one hundred pounds. Under these severe conditions, the tubes remained intact.

While I have described my invention in specific detail it is obvious that these details may be considerably varied without departing from the spirit thereof. For example, the various steps may be performed in a different order. The tube may have additional grids and. anodes, the cathode may be indirectly heated, or it may be a cold cathode. The tube may be a high vacuum or gas or vapor-filled type. The getter ring may be omitted. These are but a few of the variations that would be apparent to anyone skilled in the art upon reading the disclosure hereof. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. In an electrical space discharge device, an integral electrode assembly arranged in layers and comprising a plurality of substantially flat electrodes and a plurality of substantially flat insulating spacer members interposed therebetween, said insulating spacer members lying in planes parallel to the planes in which said electrodes lie, a portion of each of said insulating spacer members projecting beyond the electrodes, and means cooperating with said projecting portions for preventing relative movement of said spacer members.

2. An electrode assembly for an electrical space discharge device comprising a plurality of electrodes, each lying in a plane substantially parallel to the planes in which the other electrodes lie, and a plurality of insulating spacer members interposed between the said electrodes and interlocked therewith, said insulating spacer members lying in planes parallel to the planes in which said electrodes lie, a portion of each of said insulating spacer members projecting beyond the electrodes, and means cooperating with said projecting portions for securing said insulating spacer members together.

3. An electrode assembly for electrical space discharge devices comprising a plurality of electrodes, a plurality of insulating spacer members of predetermined thickness interposed between said electrodes, said electrodes being separated by the thickness of said spacer members, said insulating spacer members and electrodes interlocking to thereby prevent relative movement along one plane and means for preventing movement along a plane perpendicular to said first mentioned plane.

4. An electrode assembly for an electrical space discharge device comprising a cathode, a grid surrounding said cathode, said grid having a substantially rectangular cross-section, a pair of flat insulating plates placed on opposite sides of said grid, each of said insulating plates having an opening of substantially the size and shape of the corresponding side of said grid to receive said side of said grid therein, each insulating plate having a total thickness greater than the depth of the grid extending into said opening, and an anode plate member supported in contact with the other side of each of said insulating plates.

5. An electrode assembly for an electrical space discharge device comprising a cathode, a grid surrounding said cathode, said grid having a substantially rectangular cross-section, a pair of flat insulating plates placed on opposite sides of said grid, each of said insulating plates having an opening of substantially the size and shape of the corresponding side of said grid to receive said side of said grid therein, said grid having a flange extending between said pair of insulating plates on opposite sides of said grid, each insulating plate having a total thickness greater than the depth of the grid extending into said opening, an anode plate member supported in contact with the other side of each of said insulating plates, and means for clamping said insulating plates together to clamp said flange and retain said grid firmly in place.

6. An electrode assembly for an electrical space discharge device comprising a cathode, a grid surrounding said cathode, said grid having a substantially rectangular cross-section, a pair of fiat insulating plates placed on opposite sides of said grid, each of said insulating plates having an opening of substantially the size and shape of the corresponding side of said grid to receive said side of said grid therein, said grid having a flange extending between said pair of insulating plates on opposite sides of said grid, each insulating plate having a total thickness greater than the depth of the grid extending into said opening, an anode plate member surrounding said grid and supported in contact with the other side of each of said insulating plates, abutments on said insulating plates engaging said anode plate member to prevent longitudinal movement thereof, and means for clamping said insulating plates together.

7. An electrode assembly for an electrical space discharge device comprising a plurality of electrodes, each lying in a plane substantially parallel to the plane in which the other electrodes lie, and a plurality of insulating spacer members interposed between the said electrodes and interlocked therewith, said insulating spacer members lying in a plane parallel to the plane in which the electrodes lie, a portion of each of the outer insulating spacer members projecting beyond the electrodes, and means cooperating with 10 said projecting portions for securing said insulating members together.

8. An electrode assembly for an electrical space PERCY L. SPENCER.

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