GB497724A - Improvements in or relating to film cutouts and methods of manufacturing the same - Google Patents

Abstract

497,724. Two-part couplings ; cut-outs. BRITISH THOMSON-HOUSTON CO., Ltd. March 18, 1937, No. 8009. Void. Convention date, March 18, 1936. [Class 38 (i)] A cut - out for short - circuiting a faulty lamp in series lighting comprises a disc of metal having a film of oxide on one side, shaped to fit over the centre contact of the lamp and having an extension to contact with the annular shell. The disc may take the form of a cone 13, Fig. 3, through which the centre contact 19 protrudes, and lateral strips 11, 12 that are forced into the screw threads of the shell 18 by the lamp holder to act as a film cut-out and locking device. Alternatively sinuous strips to engage the screw thread are soldered to a flat annular disc having an oxidized surface. If the cut out is to act also as a fuse a narrow strip 37, Fig. 10, is employed and may be soldered in a slot in the centre contact. It may also be made of a high resistance material to act as a substitute for the resistance of the lamp, or an insulated resistance wire may be connected between the strip and the shell in the screw threads of which the wire may be coiled. The disc-shaped cut-out may be stamped from an oxidized sheet which may be pressed to form the conical. contour of the discs before oxidation. The cut edges of the disc and its extensions are thus unoxidized and facilitate connection thereto, while the edge 14 of the conical disc may be rolled back to prevent direct metallic connection with the centre contact.