GB472356A - Improvements in or relating to electric incandescent lamps - Google Patents

Abstract

472,356. Two part couplings. SOC. BELGE DES LAMPES A INCANDESCENCE LUXOR SOC. ANON. Oct. 9, 1936, No. 27453. Convention date, Oct. 11, 1935. [Class 38 (i)] Electric lamps, which may have a plurality of filaments, are provided with caps consisting of two coaxial members, one having contacts to which the ends of the filaments are connected, and the other contacts for connection with the holder. A contact device between the members allows them to be brought into electrical connection by relative rotation of the members. In Fig. 2, the central contact of a screw cap has attached to it a resilient strip 12, shaped as in Fig. 3. and bearing on the insulated base 6 of the bulb. One end of each of the filaments is connected to contacts 7 or 8 while the other ends are connected to a ring at the base of the bulb, which forms a sliding contact with the outer shell 9. This ring prevents the two members separating and acts as a guide so that the bulb and its cap 5 may be rotated in the outer shell 9. According to the position of contacts 7 and 8 relative to strip 12, either or both filaments may be switched on, or the lamp may be switched off. For a lamp using only one filament 2, the other filament 21 and its connecting wire 15 are omitted. The contact piece 12 is modified slightly for use with a bayonet lamp cap, Figs. 8 and 12, the contact piece 12 being fastened to one contact 19 while the common wire 4 is returned through the shell 16 to the other contact 18. An insulating ring may surround the lower part of the shell to reduce risk of shock when inserting the lamp in its holder.