US2503806A

US2503806A - Thermionic valve element assembly

Info

Publication number: US2503806A
Application number: US735444A
Authority: US
Inventors: Diggle Harry
Original assignee: Hivac Ltd
Current assignee: Hivac Ltd
Priority date: 1946-03-21
Filing date: 1947-03-18
Publication date: 1950-04-11
Anticipated expiration: 1967-04-11

Description

April 11, 1950 H. DIGGLE 2,503,806

THERMIONIC VALVE ELEMENT ASSEMBLY Filed March 18, 1947 Y 3 Sheets-Sheet l April 1 1, 1950 H. DIGGLE THERMIONIC VALVE ELEMENT ASSEMBLY 3 Sheets-Sheet 2 Filed March 18, 1947 April 11, 1950 H. DIGGLE 'rHEEMIoNIc vALvE ELEMENT ASSEMBLY 3 Sheets-Sheet 3 Filed March 18, 194'? Patented Apr. l1, 1950 'rHERMIoNIo VALVE ELEMENT AssEMBLY- Harry Diggle, Harrow-on-the-Hill, England, as-

signor to Hvac Limited, Harrow-on-the-Hill, England, a British company v Application March 18, 1947, Serial No. 735,444v

In Great Britain March '21, 1946 v' The present invention concerns improvements in or relating to the manufacture of thermionie valves.

In manufacturing thermionic valves, particularly small type miniature or midget valves it is usual to space the electrodes by supports therefor passing through holes in spaced mica discs. This has the disadvantage that as the demand for smaller and smaller valves and the'requirement for valves with more and more `electrodes grow, the diiiiculties increase of getting suiiicient holes in the space available for assembling the various grids and getting the filament in position.

An object of the present invention is to provide a method of construction and assembly whereby these diiiiculties are overcome inv a simple manner.

According to one feature of the present invention all the electrodes are substantially planar.

According to another feature of the present invention the electrodes are assembled in a stacking process with suitable spacers such as ranged on the outer sides of the grids having extensions arranged to embrace the assembly so as to hold it together.

According to a fifth feature of the invention `the electrodes are of V- or U-shape and are assembled by a simple stacking process one within the other with interleaved insulating pieces `for spacing and insulating purposes where necessary.

The elements of a valve essentially consist of .a filament, one or more grids and one or more anodes. l In one form the fllament is mounted across an opening in a flat frame which may take the form vof a bridge-piece of mica -orlike material so that the filament and support lie-substantially in a plane. The grid or grids are also-planar conveniently .being constructed as described 4in my co-pendingapplication No. 735,445... The anodes maybev plain rectangular stampings, whilesep- :a1-ating pieces may be providedjjconsisting of '1 claims. (o1. 25o-27.5)

rectangular'mica frames, that is to say rectangular stampings of mica with rectangular holes.

The grids and the anodes may be provided with lugs situated differently from each element. To assemble the electrode structure all that is necessary is to .insert the elements one .by one in a jig with interposed separating pieces just as may be desired. For instance, for a simple three lelectrode valve one would insert firstly an anode element, a separator, a grid element, the iilament, a separator, a second grid element, a separator and a second anode element. Appropriate tags would be weldedA respectively to the lugsv oftheanodes and the grids. The anode tagsjoining the-two anodes would serve to'hold the assembly in place although other means could 'readily be provided so that the assembly could be secured in position in a tube.

'It' will be readily appreciated that for envelopes requiring two valve systems with a'com'- mon iilament the combination might be sim'- ilar to that just described except that separate terminals would be required for the two anode elements and the two grid elements. For a pentode or tetrode valve all that is necessary is to add the appropriate grids or other electrodes with separators in the appropriate place. It is not necessary however that all the elements should be flat, the grids consisting of spaced wires ona rectangular frame stamping may be bent to havea U-shaped section into which the iilament maybe slipped sideways or vice versa. The supports in such a case might be interposed bridge separators or spaced mica discs as hitherto but in this case, for instance Where a number of gridsv were required the supports not requiring to be on a line can be suitably separated.

.The assembly in an envelope may follow any known method, forinstance a glass pinch for gripping the tags may be sealed as a re-entrant into a glass envelope or the mica distance pieces may be provided with toothed edges so as to form aglass fit yinto the envelope which could be `pinched -on to -theexible-leads extending from the electrodes or the respective tagsmay be sealed `in a-'glassbutton -which is in turn sealed into `the end of the glass envelope. vAvpreferred embodiment of the invention wil be described With reference to the accompanying draw-ings which show. the embodiment on `an Figure 2 is a side elevation of the electrode assembly mounted in its glass envelope.

Figure 3 is a front elevation of the electrode assembly mounted in its glass envelope.

Fig. 4 is an exploded View of the electrode assembly of a modication of the invention.

Fig. 5 is a side elevation of the electrode assembly of Fig. 4 mounted in its glass envelope.

Fig. 6 is a front elevation of the electrode assembly of Fig. 4 mounted in its glass envelope.

Referring first to Figs. l, 2 and 3 vfilament I is mounted across an opening in a flat mica frame plate 2: it is held at the bottom by an extension strip 3 on a nickel tag 4 which is attached to the frame plate 2 by being threaded through a pair of slots therein and ilattened over at each end. To the tag Il is attached one of the filament leads 5 (see Figure 3).

At the top the lament is at it, While the side limbs of the U-shaped part overlap the arms of the U-shaped grid, and are spaced away therefrom by the second pair of mica strips 2|. The lugs 24 are previously bent over so as to pass through the slots I9 in plate 2 and are then bent again so as to retain the Whole assembly together in a manner analagous to that of Figs. l, 2 and 3. Connecting

Wires

21, 28 are spot Welded to the grid lug 25 and anode lug 26 respectively to form the external connections; the filament connecting wires are shown as before at 5 and 9.

The assembly is then enclosed in its evacuated glass envelope 20 in the manner usual in the art.

may havel acommon cathode and be arranged on tached to a spring B which, in turn, is attached to a nickel tag which is held on the mica frame 2 by being threaded through a pair of slots therein and flattened over at each end as in the case of the tag 4. The tag 'I also Supports a frame 8 for the getter material and is connected to the second lament lead 9. A further description of the nlament mounting Will be found in Gouldings application No. 736,731, which issued on February 7, 1950, as Patent No. 2,496,530.

On either side the lament are mica frames I il. These frames are arranged to cover only about half of the lament mounting but so that the filament I is centrally disposed down the aperture in the frame.

Next on each side of the lament mounting are placed grids II the construction of which is described in detail in my co-pending application No. 735,445. These are lead out to the grid leads I2, I3 (see Figure 3).

Outside the grids are placed further mica frames Ill and nally nickel anodes I5 with eX- tension arms I6 and connected to the leads I1 and i8. On one side the extension arms pass through slots I9 in the mica plate 2. The ends of the extension arms I6 are bent down over the corresponding mica frame I4 at the opposite side of the lament mounting to hold the assembly secure.

- I''l'ie assembly is enclosed in its glass envelope 2n in the manner usual in the art. Referring now to Figs. 4, 5 and 6, in which corresponding parts are identified by the same reference numerals as in Figs. l, 2 and 3, a filament i is mounted across an opening in a flat mica plate 2 of similar construction to that already de scribed in connection with Fig. 1.

On either side of the plate 2 and adjacentthe slots i9 are placed mica strips 2I, arranged so as to leave the filament exposed at either side. A U-shaned grid 22 comprising a metal frame with attached transverse Wires and with a connecting lug 25 partially embraces the plate 2, the curved portion of the U-shape surrounding the filament I While the arms of the U are spaced away from the plate 2 by the engagement of the edges of the grid framev which lie along the free- 'endsoi the two limbs of the U-shaped part, with the' strips 2|. uts'ide this grid are placedtwo further mica strips 2i, one at eitherl side of the arms oi' the U and overlapping the first pair of strips 2l. Finally, a U-shaped anode '23 with a connecting lug` 2S, and four further lugs 24, whose purpose will become apparent later, is placed over' the grid so that the base ofthe U-s'riaped part embraces the base of the U-shaped grid without touching opposite sides of the lament or the various systems could be separated in any manner known in the art provided the separator was so shaped as to permit of it being stacked.

Other insulating materials such as ceramics may replace mica.

I claim:

l. An electrode assembly for thermionic valves in which the electrodes other than the lamnt are of substantially U-shape and are stacked one Within the other with interleaved insulating pieces for spacing and insulating purposes, the assembly being held together by bent over exten# sions on the anode, which pass through slots in filament mounting centrally inserted in the asf*- sembly.

2. A method of constructing a thermionic valve which comprises the steps of forming each of the component electrodes as elements of planar sheet form including tivo anode-forming elements 'as at metal plates, providing extension lugs projecting from one pair of opposite side edges of each of said anode plates and forming the cathode element to include a nat sheet of insulating material of larger size than that of the other elec*- trodes, and providing apertures therein through Which at least some of said extension lugs are passed, assembling said electrodes by a stacking process of first laying an anode plate, then laying the remaining electrodes thereon in register and one upon the other in appropriate order and terminating with the other anode electrode ivith in'- terleaved spacing frames of sheet insulating' mai terial Whose thickness dimension determines the related inter-electrode spacing distance, and then securing the stacked assembly as a unitary 'struc'- ture by bending over the extremities of each of said extension lugs on to the opposite side of the stack of electrodes' so as to grip the thickness'dimension oi the stack. n

3. An electrode assembly for a thermionic valve comprising a filament mounting including a at sheet of insulating material having' an opening therein and a lament wire spanning such anerture, a spacing frame of sheet insulating material disposed in contact with one side of said sheet of said filament mounting and With the frame aperture aligned with said opening, a grid electrode in the form of a sheet metal frame with trans:i VerselydireCted grid Wires disposed in contact with the opposite surface of vsaid. spacing' frame andV with its aperture inalignmentwitntnat of said frame, a further spacing frame of sheet in'- sulating material disposed in contact with the other side of said grid electrode and with its aperl ture in alignmentwith that of said first spacing frame, anaode electrode in the forni o f a5 it metal sheet disposed in contact with the opposite surface of said further spacing frame, and integral extension lugs on opposite sides of said anode plate, said extension lugs being bent to lie adjacent the side edges of the assembled stack of electrodes and spacing frames and having their free ends bent over on to a surface of the stack on the side of the lament mounting which is opposite to that of the anode so as to grip and hold the assembly in clamped relationship.

4. An electrode assembly for a thermionic valve comprising a plurality of electrodes all of planar sheet form and including two anode-forming elements each constituted by ilat metal plates and a lament mounting constituted by a nat sheet of insulating material having an opening therein spanned by a iilament wire, a plurality of spacing frames of sheet insulating material, said electrodes being arranged in face-to-face relationship on each side of said filament mounting and with said spacing frames interleaved between adjacent electrodes to effect electrode spacing means and with one of said anodes as the outermost electrode on each side of said filament mounting, and extension lugs on each of said anodes, said lugs being bent to extend along the thickness dimension of the assembled stack of electrodes and spacing frame and having their free ends bent over on to the opposite side of the stack to form mechanical clamping means by which the parts are held secured in position.

5. An electrode assembly for a thermionic valve comprising a filament mounting of planar form and including two flat sheets of insulating material placed face-to-face and having aligned openings therein and with a ilament wire located in between said sheets and spanning said openings, two anode elements each in the form of a fiat metal plate and disposed one at each side of said lament mounting in parallel relationship therewith, at least one pair `of. grid elements each in the form of a sheet metal frame having spaced wires spanning the frame aperture and located one of each pair at each side of said larnent mounting intermediate the latter and the adjacent anode plate and parallel therewith, spacing frames of sheet insulating material disposed in between each of said grid and anode elements and said filament mounting with the thickness of said insulating sheet determining the inter-electrode spacing distances and integral extension lugs on each of said anode elements, said lugs being disposed in mutually staggered relationship, and

6. An electrode assembly for a thermionic valve of the type having a plurality of electrode elements each of planar form and comprising. an anode element in the form of a flat metal sheet, a lament mounting comprising a at sheet of insulating material having an opening therein and a filament wire spanning said opening, and a plurality of apertured frames of sheet insulating material, said electrodes being disposed in stacked face-to-face relationship with said frames disposed at least one between each adjacent pair of electrodes and forming the sole inter-electrode spacing means, said anode element being provided with extension lugs integral with said nat metal sheet, said lugs projecting from at least one pair of opposite edge regions of said sheet and being directed along the thickness edges of the stacky and having their free ends bent over on to the'opposite side of the electrode stack to form means for gripping the thickness dimension of such stack and said filament mounting sheet being of greater dimension on at least one side of said assembled other electrodes and having apertures at that side for the passage therethrough of said extension lugs of said anode elements.

7. An electrode assembly for a thermionic valve of the type comprising a plurality of electrode elements each of planar form, which includes an anode element consisting of a fiat metal sheet, and a plurality of apertured frames of sheet insulating material said electrodes being disposed in stacked face-to-face relationship with said frames disposed at least one between each adjacent pair of electrode elements and forming the sole inter-electrode spacing means, .said anode element having integral extension 'lugs projecting from one pair of opposite side edge regions of the sheet and having its dimension parallel with such side edges less than the similar dimension of the aperture of the adjacent spacing frame, said extension lugs being directed along the thickness edges of the stack and having their free ends bent over on to the opposite side of the electrode stack to form means for mechanically gripping the thickness dimension of the stack.

HARRY DIGGLE.

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

UNITED STATES PATENTS Great Britain July 23, 1925