US2830279A - Electron discharge tube mounting - Google Patents

Description

April 1958 A. WARSHER 2,830,279

' ELECTRON DISCHARGE TUBE MOUNTING Filed Feb. 16, 1954 F IGJ IN VEN TOR.

ADOLPH WARSHER HITOR/VE) ELECTRON DISCHARGE TUBE MOUNTING Adolph Warsher, Ridgewood, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application February 16, 1954, Serial No. 410,616 2 Claims. (Cl. 339-145 This invention relates to mountings for electron discharge tubes, and especially to mountings for subminiature tubes. This type of tube is made with relatively fine wire leads protruding directly from the glass stem forming the base of the envelope; and the connection of such tubes to circuit elements presents a numberof problems. One is the danger that the leads'may break olf at or near the glass surface; another is the care and time required to make satisfactory circuit connections.

A purpose of the invention is to provide a mounting for subminiature tubes of this type that will materially reduce the danger of lead breakage. Another object is to provide such a mounting that will facilitate the connection of such a tube to circuit elements. This is in general accomplished by providing a novel mounting unit readily mounted on the tube base and carrying relatively rugged connecting members each conductively connected to a tube lead. More specific objects'are to provide connecting members that can be inserted in' a tube socket, and members to which leads of substantial size can be easily connected without special care or delicate operations. a

An object is to provide a mounting that will facilitate ready and effective mounting of the tube on a support, such as a chassis or base of sheet insulation. A further object is to furnish a mounting especially adapted for ready and rapid connection of the tube leads to circuit elements carried by a sheet of insulating material or the like, and specifically to printed circuit elements on such a sheet.

Subminiature tubes are widely used in instrument and other electronic circuits carried by aircraft that operate at high altitudes and under widely varying conditions of pressure and temperature. With reference to temperature, the mounting of such tubes, especially when enclosed, may be subjected to temperatures above 250 C., including the heat generated by the tubes themselves during operation. On the other hand, at high altitudes the mountings may be exposed to temperatures .as low.

as 65 C. An object of the invention is to provide a mounting that will be satisfactory under these temperature conditions.

Tube mountings may be connected to the tube stemsby plastic or fluent material, and ordinarily some air bub-.

bles are' occluded. This can be-a' serious defect under the indicated conditions, owing to the tendency of the air pressure in the bubbles to drop at lowered temperatures and with the decrease in ambient pressure at high altitudes, resulting in a tendency to produce arcing. A purpose of the invention is to provide a sealed mounting that is free from this defect. The mounting may also be subjected to strain if the sealing material adheres to the glass, since unequal coefiicients of expansion will cause strains at the interface during temperature and pressure changes. An object of the invention is to provide a sealed mounting that is free from this defect.

The foregoing and other objects and advantages of ice Fig. 1 is a side elevation of a subminiature tube with: a mounting attached, the mounting being shown longitudinal section along line 11 of Fig. 2;

Fig. 2 is an end view of said mounting;

Fig. 3 is a side elevation of said tube and mounting, the tube being broken away, showing the mounting attached to a sheet of insulation carryingia printed cir-,

cuit; and r Fig. 4 is a face 'view of said sheet, showing the position of the printed circuit and tube connections thereto.

The subminiature tube 10 is provided with an annular series of wire leads 11 projecting from its base, the form illustrated having eight such leads. A lead retaining disk 12 is provided with an annular series of transverse passages 13, advantageously flared at their ends, registering with leads 11 and sufficiently large for ready insertion of the leads through the passages with ample clearance. The disk 12 is made of suitable insulating material, such as an appropriate synthetic resin, selected not only for its insulating qualities, but also for the other maintain its contour and position without serious change in dimensions or physical characteristics over the substantial variations for temperature and pressure set forth. It should have a low dielectric constantso as to introduce a minimum capacitance effect in the tube circuits, and should retain suflicient plasticity at very low temperatures to avoid a tendency to break under shock or vibration. It has been found that these characteristics are possessed by commercial forms of tetrafluorethylene, such as that marketed under the trademark Teflon, or tetrachlorethylene, such' as the form marketed under the trademark Kellefli.

The disk 12 is advantageously sealed to the base of tube 10 in such manner that no air pockets are formed, and the objectionable characteristics above enumerated are eliminated. For this purpose the seal 14, somewhat exaggerated in the illustration, is formed from material that will readily flow under practical conditions to fill any interstices between disk 12 and the base of tube 10, and also to fill passages13 around leads 11 without any gaps.

The sealing material must possess the characteristics already indicated, and in particular should be non-carbonizing, under high temperature conditions already indicated which tend to break down many otherwise suitable organic plastic materials. It has been found that silicone compounds of the type generally-known as silicone greases, of types having the indicated qualities, are suitable for this purpose. They maybe effectively applied to fill the spaces between the disk and the base of tube 10, as well as passages 13, by placing a suitable amount of the grease on the center of the inner face of disk 12 and then forcing the disk against the tube base, causing the grease to flow radially and also transversely through passages 13 to form a continuous seal free from air bubbles or pockets.

The disk 12, when constructed and attached as described, may be used by itself, since it eifectively protects the vulnerable portions of leads 11 where they are connected to the base of tube 10, and permits an adequate but limited amount of lateral deflection and bending of the leads without producing damaging strains. This Patented Apr. 8, 1958;

is partly due to the ability of the leads to shift in the sealing material, and in part to the flared outer ends of passages 13, which cause the leads to form a rounded rather than a sharpbend at this point.

A featureof the invention isthe provision of a mounting member extending from disk 12 and provided with rugged circuit-connecting elements which permit the ready electrical connection of therelativ'ely delicate leads 11 to various types of. circuit elements without danger of dam-' age or breakage. lIn" the form il1u'strated,.the mounting member 15 is in the torn-'1' of aseparate cylinder'of suitable insulating material, preferably molded from a synthetic resin having a low dielectric constant and good insulating qualifies suchv as Teflon or Kelle'fif, and formed with a rabbet- 16 fitting over. the margin of disk 12. The cylinder is advantageously arranged so that its inner face 17 is'in alignment with passages 13, and therefore in proximity to the leads 11 projecting from said passages.

Suitable contact studs 18 are mounted on cylinder 15 in position for engagement with leads 11, and advantageously extend from the outer end of the cylinder. In the form illustrated, the studs 18 are molded in the cylinder, and their projecting port-ions are located in recesses 19 in the outer end of the cylinder, separated by lands 20. Each stud 18 comprises a shank 21 with an anchoring flange 22 at its inner end, and a lead connecting section 23 having a base 24 imbedded in the plastic material, a connection neck 25 of reduced diameter projecting preferably beyond the lands 20, and a contact pin portion 26. 'Pins 26 are advantageously proportioned and located so that they may be inserted in tube sockets. They are also advantageously formed with a central recess 27 and sidewalls 28, for reasons hereafter indicated.

Each lead 11 is brought into effective electrical contact with the neck 25 of a'stud 18, as by wrapping it around the neck and providing the requisite contact and mechani- I It has been found" cal strength by soldering or brazing. in practice that electrical welding and silver brazing. are especially efiective'. This engagement of the leads 11 with studs 18' likewise serves to hold the mounting member 15 securely inplace on disk 12.

in use, the tube assembly may be mounted on a socket as already indicated, or conductors of an external circuit may be connected to studs 18. An efiective soldered connection with a pin 26 maybe made by introducing an external lead wire into the recess 27 and soldering it in place; but if the lead wire or other connecting circuit element is too large for the recess, it may be wrapped around or soldered or brazed to the outer face of pin 26.

The tube assembly may likewise be mounted on a support of sheet insulating material, as shown in Figs. 3 and 4, by passing the hollow pins 26 through registering apertures in sheet and flanging the side walls 28against the opposite surface, the other face ofthe sheet bearing against lands 20. In this manner a plurality of tubes 10 maybe mounted in close proximity with sufiicient rigidity to withstand substantial shocks, and their leads may readi- 1y be connected in appropriate circuits by connections on the side of sheet 30 opposite to the tube. This arrangement is particularly adapted for the use of printed circuits, leads31 of which are illustrated. The arrangement is also adapted for circuit connections, either exclusive or additional, on the other side of sheet 30.

Although but one embodiment of the invention has been illustrated and described in detail, it is to be ex pressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention, as the same will now be understood by those skilled in the art.

1 claim:

1. A mounting including a subminiature electron discharge tube having anannular series of thin, readily bendable leads projecting from its base, comprising a disc of insulating material for protecting the tube leads and adapted to fit against the tube base and having apertures therein for receiving the tube leads, a member having a cylindrical vmounting wall receiving said disc and with its'inne'r surface substantially in alignment with the leads, and a'series of tube socket. engaging pins mounted axially on the outer end of the wall in position for insertion in a tube socket, said pins being hollow and provided with readily bendable side walls outwardly deformable into engagement. with a juxtaposed element.

2. A mounting including a subminiature electron discharge tube, having a plurality of thin, readily bendable leads projecting from its base, comprising a lead-supporting disc of insulating material separate from and fitted against the tube base and provided with lead passages registering with and substantially greater in diameter but shorter than the leads and having inner walls spaced from the leads and having a plastic insulating filler having a low dielectric constant and a high insulation coefficient and filling completely without air spaces, the passages and the space between said disc and the tube base so as to restrain the leads against lateral movement and bending at the junctions with the base beyond an extent limited by the diameter of the passages, a separate annular mounting section removably engaging the lead-supporting disc, and a series of connecting members mounted on the mounting section, the leads extending through but unattached to apertures in the supporting disc and through the interior of the annular mounting section into engagement with the connecting members and retaining the discs and mounting section in place on the base.

. References Citedin the file of this patent UNITED STATES PATENTS 2,278,392

Harrison Sept. 20,

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