GB308494A - Improved electric incandescent lamp fittings - Google Patents

Abstract

308,494. Andersson, R. P. A. April 14, 19'28. Multiple-filament lamps; holders.-In bulbs of the kind having a rotary switch in the cap for the selection of the filament, the switch is arranged to enable the bulb to be used in an ordinary holder, in which case the filament is selected by the said switch only, or in a special holder containing or connected to a distant selector switch. In the construction shown in Fig. 2, the filaments 3, 4 are both connected at one end to the shell of the cap and at their other ends to contacts 21, 22 with either or both of which a switch arm 19 can contact. The arm 19 is carried by a metal tube 18 rotatable by an external disc 27, which may be turned by means having a handle projecting through the bulbholder socket. A central pin 16 insulated from the tube 18 is connected by a conductor 23 to the contact 21. Before inserting the bulb into an ordinary holder a filament is selected by turning the arm 19, but when it is inserted in a holder which has three contacts connected to three supply leads, the arm 19 is engaged with the contact 22 so as to connect the corresponding filament to a contact in the holder, while the other filament is connected through the pin 16 to a central pin contact in the holder. The filament is then selected by a switch fitted in the holder or located at a distance. The parts shown may be modified for use with a bayonetcap bulb. In the construction shown in Figs. 5 and 6, a rotatable selector disc 56 may be engaged with either or both of two contacts 51, 52 to which the filaments are connected, these contacts being connected to concentric metal rings 53, 54 on the opposite face of the plate. These rings have a wiping contact with spring fingers in the holder, or the fingers may be mounted on the plate and the concentric rings in the bolder. In the construction shown in Fig. 3, the two contacts 65, 66 of the selector are embedded in the insulating end 64 of the cap and are engaged by an external radial finger 63 to which pressure is applied by a spring 61. A ring contact 67 is in permanent connection with one contact for use in a holder connected to an external selector switch.