US2383263A - Tube and base structure - Google Patents

Description

. Aug. 21,; 1945. w. P, KRUGER 2,383,263

TUBE AND BASE STRUCTURE Filed Feb.c12.' 1944 I Patented Al1g 21, 1945 I IUNITED gSTATE S PATENT OFFICE I TUBE AND BASE STRUCTURE William P. Kruger, New York,` N. Y., assignor to Electrons, Inc., Newark, N. J., a corporation of Delaware Application February 12, 1944, SerialNo. 522,170

` 2 claims. (c1. 17e- 32) This invention relates to the mounting of a glass bulb in a supporting base, and particularly to such a combination in an electronic tube.

The object of the invention is to provide a bond between the bulb and the base which willbe permanently secure and unaffected by handling and by the variations in heating and cooling of the tube in service. In the accompanying drawing illustrating the invention in connection with an electron tube Fig. 1 is an elevational view with a part of the base broken away; I Fig.I 2 is a view on enlarged scale of the bulb and base inverted and prepared for assemblyb Fig. 3 is a similar view showing the bulb and Ibase bonded together and Figs. 4 and 5 are transverse sectional views` taken onthe line 4-4 of Fig. 3, Fig. 5 illustrating on exaggerated scale the eect of temperature changes. I

In the specific example shown in the drawing, the glass bulb ID has an outer or upper cap terminal III and inner or lower terminal wires I2,

the'base end I3 of the tube being 'reduced in die ameter and providing the slightly tapered or inclined annular surface I4 at the area of attachment to the base I I5. In assembled positionthe wire terminals extend into and are fastenedto the contact pins I6 of the base. I

The base I is hollow with inner-chamber walls `l'IIgenerally cylindrical and terminating in an` `annular edge 1I8 the bulb I0.

at the point of attachment to In the tube of this invention the bond between the base and bulb is provided by anumber of separated areas of cement 2l).` I

`These separate masses of softcement are prefn Ierably applied within the base edge I8 as shown and enough in amount to fill in rbetween the base wall and the bulb surface I4 (Fig. 3) when the base I5 (Fig. 2) is lowered into place over the end of the bulb I0 (Fig.` 3).

` The parts are retained in this inverted position until the cement has hardened, for instance by setting under heat as with aBakelite cementtype No, BC-2360. This cement is a mixture of finely I ground marble dust with phenol-formaldehyde thermo-setting plastic and with the addition of expansion (generally higher) than that of the glass of the bulb and the cracking of the glass'` bulb in service is believed to be often due to the stresses resulting from the greater contraction during cooling of' the cement bond extending around the full or a large portion of the periphery of the bulb.

In the construction of this invention,I such contraction stresses are avoided and the parts are relatively free to expand and contract without thedevelopment of excessive stresses. In Fig. 4 the parts are shown expanded by heating of the tube` and in Fig. 5 the parts have contracted upon cooling, the effects being intentionally exaggeratedin the figures of the drawing. During this cooling any tendency of the base to contract I `more or less than the bulb may-'be in part relieved by` slight distortions of the base I5, mainly between the areas of cementing as indicated in Fig. 5 for relatively greater contraction of the base. At the same time the contracting of the cement masses 20 imposes substantially no stresses on the base or bulb leaving `the parts free 0f any interaction tending to crack the bulb or weaken the bond between the Ibulb` and the base.

'I'his construction also permits partialresidual I setting of the cement 2i? under the heating of the I tube in service where, as is sometimes the case,

some shellac, the precise proportions not being critical. Preferably the heating is carried tothe point of permanent polymerization and setting of the cement so that subsequent heating of the and very firm bonds to the base I the heating during assembly has not been carried toIcomplete setting or polymerization. :The tube of this invention thus has the bulb and the base permanently secured together in a manner which unaffected by variations in the heating and cooling of the tube during manufacture and in" service and maintains a rm bond under all conditons.,` I

I Iclaini: I I

1. A bulb and base comprising a glass bulb Ihaving an annular surface for attachment to a base, a base of material of different coefcient of expansion from the glass of said bulb and having a hollow formation with a deformable edge adapted for attachmentl to said annular surface of said bulb, and a plurality of individual masses of cement between said bulb and base spaced. to leave intermediate open uncemented spaces and bond-` ed to the bulb and bnase surfaces to form separated' anchorages firmly attaching said edge to said annular surfaces while maintaining relatively extensive intermediate surfaces of said bulb and :base unattached and freeto shiftrelatively without overstressing the bulb under variations in heating and cooling of the Itube.

2.`A bulb and base structure as set forth in claim 1 in which the masses of cement are fully set and hardened in place between the bulb and ibase so that further heating under service conditions does not cause any substantial further setting and hardening. t

I I WILLIAM P. KRUGER.

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