GB551115A - Improvements in or relating to vacuum-tight or gas-tight seals in electric apparatus and methods of producing such seals - Google Patents

Abstract

551,115. Sealing metal to glass by heat. PHILIPS LAMPS, Ltd. (Naamlooze Vennootschap Philips' Gloeilampenfabrieken). July 29, 1941, No. 9660. [Class 36] In evacuated or gas-filled discharge apparatus or incandescent lamps, or electric apparatus enclosed in a gas-tight metal, ceramic or glass envelope, having one or more conductors of brass, Mo, &c. sealed into a glass body, at least five per cent, and preferably ten per cent, of this body consists of fine bubbles, or the specific weight of the glass is correspondingly lower than that of gas-free glass. In Fig. 1, glass powder 3 is placed in a mould 6 in which conductors 2 and an electrode construction 1 are mounted, the bulb 4 is placed in the powder, and the whole is heated in an oven or by a high frequency coil 7 ; an exhaust tube 5 may be provided either in the bulb or in the base. A substance which, under heat, evolves CO 2 &c. may be mixed with the glass powder. In Fig. 2, glass powder 11 is moulded to the desired shape by a binder, such as paraffin wax, which volatilizes under heat, and is arranged in a metal base 8 with a central guide pin 9 provided with a thickening 10. In a lamp, the conductors may be sealed into a pinch, or each conductor may be sealed into a disc of the glass, the discs being sealed into a glass base which is sealed to the body of the bulb. The glass body may take the form of a screw or bayonet cap.