GB427809A - Improvements in or relating to incandescent electric lamps of the multifilament type - Google Patents

Abstract

427,809. Multiple filament electric lamps. ISMAY & SONS, Ltd., J., Roden Street Works, and ISMAY, J., 10, Warwick Gardens, both in Ilford, Essex. Oct. 31, 1933, No. 30255. [Class 39 (ii)] In multi-filament electric lamps of the kind wherein a rotary split - ring surrounding the lamp cap is provided with radially projecting pins to engage a bayonet - joint type socket, and interlocking means between the cap and ring are provided whereby the position of the ring can be adjusted angularly so that different filament contacts can be brought into engagement with the contact pins of the socket, slots are formed in the lamp cap by piercing completely through the metal wall thereof to co-operate with a similarly formed projection in the split ring. In the example the lamp is provided with two filaments which have a common leading-in wire connected to one contact 7, Fig. 4, of the cap 8, each of the other leading-in wires being connected to a separate contact and the three contacts being spaced approximately 120‹ apart. Two vertical slots 9 are pierced through the cap wall to co-operate with an inwardly directed projection or flange 12 formed by two parallel cuts 11 in the edge of the split ring 10. One bayonet pin 14 is secured to the outside of the split ring adjacent to the projection 12, the other pin 14 being diametrically opposite to it. In a modification the inwardly directed projections are formed at the lower edge of the split ring to engage slots extending circumferentially of the cap. Alternatively the slots and interengaging projection may be at an angle to the axis of the cap. A flange 15 at the upper edge of the cap assists in retaining the ring in position. Specifications 6856/11 and 301,319, [both in Class 39 (ii)], are referred to.