GB225166A - Improvements in or relating to electric heating devices disposed within an enclosingenvelope - Google Patents

Abstract

225,166. Naamlooze Vennootschap Philips' Gloeilampenfabrieken. Nov. 22, 1923, [Convention date]. Low-pressure metallic-vapour apparatus; vacuum tubes.-Relates to a device for heating a conductive body in an enclosing envelope by means of at least one metal electric heating element which is in direct contact with the body to be heated, the leading-in wires to the heating element being sealed in a glass or like portion of the envelope and the heat transmission being effected by direct conduction of heat across the contacting surfaces of the conductive body and the heating element, and consists in arranging the conductive body and the heating element in such electrical and physical contact at a plurality of points that there is substantially no fall of potential throughout the conductive body. The heat is generated in those parts of the heating element between the conductive body and the leading-in wires, and the heating element may. be formed to support the body to be heated. In Fig. 1 a copper cathode 1 for a discharge tube is in direct contact with a nichrome, tungsten or molybdenum wire 2 supplied with current by wires 3, 4. The cathode has a head 5 which may be covered with a substance emitting electrons at low temperatures, such as one or more oxides of alkaline earth metals. Dimensions of the wire 2 and cathode are given. In Fig. 3 a platinum or molybdenum vessel 6, which may contain a metal to be vaporised or some substance which developes a required gas, is in direct contact with heating wires 7, 8. In Fig. 5 a cathode 11 is supported by heating wires 12, 13. The cathode has a separate leading-in wire 16. An anode 14 and grid 15 are arranged as shown. Specifications 207,514 and 213,605 are referred to.