US2439886A - Lead-in construction - Google Patents

Description

April 20, 1948. R. DENMARK El AL LEAD-IN CONSTRUCTION.

Filed Aug.'l7, 194s a g M WWW n WNW WM 4 M. WW m a. p A. 00 k 15 7: x l m I\ 4H I 1 -i fl Patented Apr. 20, 1948 2,439,886 LEAD-1N CONSTRUCTION Robert Denmark, New York, N. Y., and Carson I H. MoWhirtcr, Westinghouse East Orange, N. J., assignors to Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 1'7, 1945, Serial No. 611,146

' 3 Claims. (01. 250-275) This invention relates to lead-in construction and more particularly for use in connection with the electronic art. I

In view of the constantly increasing use of glass or other ceramic bowls and the like as the base portion of an electronic device, it has become increasingly desirable to improve the leadin construction for electrical connections through the bowl. Exemplary of a prior art construction, reference is made to Patent 2,325,748 of August 3, 1943, setting forth an invention of Hampton J. Bailey and William J. Knochel. The present invention is an improvement thereover and for similar use in an electron discharge device.

The invention has for a primary object of broad scope, the mechanical improvement of the prior art structures with simplification of manufacture, construction and assembly thereof.

More specifically, an object of the invention is to secure accurate centering and alignment of the supporting pin or post with the thimble portion of the lead-in construction.

A further object of the invention is to enable the thimble to have a cup portion of one material and a prong of diiierent material.

Yet another object of the invention is to provide for use of strong material for attachment of the pin or post, heat responsive material expandablewith the glass where the junction with glass occurs, andhighly electrically conductive material for the prong.

Other objects of the invention will appear to those skilled in the art to which it appertains as the description proceeds, both by direct recitation thereof and by implication from the context,

Referring to the accompanying drawing in which like numerals of reference indicate similar parts throughout the several views:

Figure 1 is a sectional view of a portion of the base or bowl of an electron discharge device at the part thereof having the present invention applied, the same being shown in part in elevation and in part in longitudinal section;

Figure 2 is a cross-section on line-II-II of Fig. 1;

Figure 3 is an elevational sectional view similar to Fig. 1 and illustrating the invention in course of assembly;

Figure 4 is another sectional elevation similar to Fig. 1 but showing a modified embodiment of the invention; and

Figure 5 is a perspective view of the pin attaching member or nuts as used in Fig. 4.

In said drawing there is show a portion of a glass or other ceramic bowl comprising a part of the envelope of an electron discharge device added detail of which corresponds to the showing of Patent 2,325,748. The pin or post ll shown is both an electrical conductor to and a, mechanical support for an electrode in the device. It is usual practice to employ molybdenum as the material constituting the pin I I, and as molybdenum is both hard and rigid, it is desirable to require a minimum of machine work thereon and to anticipate no correction of location to be performed by bending the pin in place. It is essential that the pin be preformed and that it be exactly positioned when mounted and thus require no adjustment or bending.

Where lead-in connection is to be made, the bowl is provided with a reduced neck l2 at the outer rim of which is sealed the margin of a thimble l3. In Figures 1-3, said thimble is shown as comprising a cup portion or head M from which coaxially projects a reduced portion or prong 15. Within the head or cup I4 is an attaching member or nut I 6, preferably of steel. secured so as likewise to be coaxial to the cup. The end of the pin or post II is screw threaded, as at IT, and has threaded fit with the center hole of nut l6.

Describing the invention more in detail, it is preferable to utilize a material for cup l4 and a glass for bowl in which have substantially the same coefiicient of expansion. These materials may be and preferably are those defined in the patent to Howard Scott No. 2,062,335 of Decemher 1, 1936. The glass is known as boro-silicate glass and the metallic material is sold in commerce under the trade name of Kovar. The cup shown preferably has a cylindrical side wall or skirt and a solid or closed bottom wall perpendicular to the axis of the cylindrical wall. The perpendicularityof the bottom wall may be made very precise and providesa surface from Which accurate axial alignment of attached parts may be assured. Furthermore, bottom wall is fiat lends itself to securing a vacuum tight structure not likely to develop cracks, crevices or leaks.

The fiat structure of bottom wall of the cup [4, bounded by its cylindrical wall, is conducive to readily mounting the same in a fixture during fabrication of the device and applying a prong l5 in end abutment thereagainst in the fixture to be welded, soldered or brazed on said cup fiat wall in precise axial alignment with the cup. Preferably said prong is copper and being machined with a fiat end perpendicular to its axis,

the fact that the.

preferred that the nut engage tightly within the cup with the said edges between facets of the nut having substantially line engagement with the cylindrical wall of the cup and thereby securing both an accurate centering of the nut coaxial with the cup and a frictional retention. of the nut within the cup. The bottom face of. the nut is;

forced into intimate juxtaposition to the flathottom face of the cup and thereby assures precise axial alignment of the nut and cap. The nut may be welded in place, or otherwise retained as by soldering or brazing. By virtue of the central threaded hole in the nut, the threaded pin may be applied to the nut and will necessarily be coaxial to the cup and perpendicular to the bottom flat. wall thereof. The regions between the facets of the nut and thecurved wall of the cup afford cavities which will receive solder or brazing material l8. If desired, solder rings may be applied in the cup, one next the cylindrical and one next the pin and the assembly heated to melt the solder and obtain the desired retention of the nut and pin in place in the cup. At the same time, a similar use of a solder ring on the prong next its engagement with the cup may be employed for completing the unification thereat between those parts.

Inevent a one-piece copper feather edged nipple is preferred such as shown in said Patent 2,325,748 and duplicated in Fig. 4. hereof, advantage may be taken of the hollow interior of the cup and prong and the internal taper of the cup wall. As may be seen in the. drawing, cup I40. of this. showing is integral with a hollow prong, both preferably being copper, but with a flat shoulder disposed perpendicular to the axis at the junction of cup and pron and for purposes of this invention constituting the flat end wall of the cup. The inside surface of the cups cylindrical wall tapers or flares to larger diameter toward the rim .of the cup. In this instance we have shown the attaching member or nut 16a as having a frusto conical disc-like head portion I9 the peripheral face whereof engages the tapered inside surface of the cup and obtains a frictional and centering engagement therewith. The under side of head 18 is flat next the periphery and engages flatwise against the shoulder or flat wall of the cup, therebyassuring coaxial alignment of cup and attaching member. Said attaching member is preferably of steel for purposes of rigidity. Furthermore, in this instance a central stem 20 depends from the underside of head IQ of the attaching member, this stem projecting coaxially within the hollow prong and preventing the prong from becoming bent in use. The attaching member has a central threaded hole 2| therein for reception of the threaded end 11 of pin or post H. As before, the attaching member may be soldered or brazed to the cup and the pin soldered or brazed to the attaching member.

In both forms of the invention shown, the assembly is readily accomplished and coaxial alignment is assured. The method employed as well as the assembled parts are conducive to a strong lead-in construction, and one of low electrical resistance for both direct current and radio frequency. The use of expensive, complicated brazing fixtures is avoided and yet concentricity or coaxial alignment is simply and effectively obtained, The problems of strength, conductivity,

sealing and alignment have been so coordinated as to avoid sacrifice of one to achieve another,

. and thus. all have been satisfactorily solved resulting. in afar greater percentage of successful devices produced'with less spoilage and failures than in the. prior art construction.

We claim 2.

' l. A lead-in construction comprising a cup portion having an outer cylindrical wall with an open end and having a transverse flat wall re mote from said open end, an attaching. member secured in said cup portion and centeredby said cylindrical wall and coaxially aligned by engagemerit against said flat wall, and a post carried by and projecting coaxially from said attaching member and projecting from the said open end of the cylindrical wall.

2. A lead-in construction comprising a cup portion of material effectually sealed to glass, said cup portion having a cylindrical wall and a fiat wall perpendicular to the axis of the cylindrical wail, an attaching member of material of greater strength than said cup portion, said, attaching member having centering en a ement at its periphery with said cylindrical wall and having fiatwise engagement with said fiat wall and coaxially aligned with and secured in said cup portion, and a prong projecting from said flat wall of the. cup portion at the opposite side thereof. from said attaching member.

3. A- lead-in construction comprising a cup portion having a cylindrical wall with an open end and having an integral fiat wall perpendicular to the axis of thecylindrical wall remote from the said open end, an attaching member secured within said. cylindrical wall having centering engagement therewith and flatwise engagement with said flat wall, said attaching.

member having a coaxial threaded hole therein, and a post having a threaded end engageable in and coaxially supported by said attaching member and projecting from the said open end of the cylindrical wall.

ROBERT DENMARK. CARSON H. MCWHIRTER.

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

UNITED STATES PATENTS Number Name Date 2,332,090 Knochel et al Oct. 19, 1943 2,343,522 Bergman .d Mar. 7, 1944 2,366,459 Rosa Jan. 2, 1945 FOREIGN PATENTS Number Country Date 541,952 Great Britain Dec. 18, 1941

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