GB474637A - Improvements in or relating to the manufacture of electric discharge devices - Google Patents

Abstract

474,637. Uniting metal to vitreous material by heat. M-O VALVE CO., Ltd., and SMITHELLS, C. J. May 29, 1936, No. 15240. [Class 36] [Also in Group XL] In the manufacture of electric discharge devices, more particularly thermionic valves, of the type wherein a substantial part of the envelope is of metal, and the leading-in wires pass through glass seals by which they are insulated from each other and from the metal part of the envelope, a metal member forming part of the envelope is pierced with a substantially circular hole, a glass ring is attached to the circumference of the hole, leading-in wires are arranged between the glass ring and the expanded end of a pumping-tube, and the glass ring and expanded end are heated so that they unite with each other, embedding the leading-in wires between them. In the example the metal member consists of an annulus having an outer rim 2 with an inner rim 1 of thin sheet metal secured thereto by welding, brazing or the like at the edge 3. A glass ring 4 is secured by fusion within the hole bounded by the rim 1, and the leading-in wires 5 are sealed between the ring and the flared end 6 of the pumping- tube 7, the parts being supported in known manner during the sealing. Pressure may be applied upon the flared end 6 by means of a mandrel to facilitate sealing. A metal case 8, which may form the anode is welded at its edge to the flange 2. Alternatively, wires 9 welded to the edge 3 may be used to support some or all of the electrode structure. Specifications 369,349 and 400,334, [both in Group XI], are referred to.