GB190003A - Improvements in and relating to electric incandescent lamps - Google Patents

Abstract

190,003. Rohner, E., and Simic, E. Dec. 8, 1921. Multiple - filament lamps; caps; filaments. - A multi-filament lamp has a contact-making device removably inserted in a slot in the base of the lamp cap and comprising a contact piece with an integral or separate insulating piece such that it can make contact with the terminal of any selected filament and when it is removed from the slot it exposes contact pieces forming terminals of all of the filaments for connection in an ordinary screw socket lamp holder. The two filaments c, d have one common terminal in the screw cap e and separate terminals k, k<1> on the end of the cap separated by a slot in which fits the switching piece h and insulating member i. With the switch as shown, the contact k is insulated and the filament d is lighted via the terminals h, e. When the switch is removed and reinserted so as to insulate the terminal k<1> and bring the blade h into contact with the terminal k, the filament c is lighted, and when the switch is completely removed both contacts k, k<1> are connected to the socket terminal in parallel and both filaments are lighted. In an alternative form of switching piece, the member h is T-shaped, instead of L-shaped as shown, with one member of the cross bar of the T extending over the exposed limb of the insulating piece i. This is shown in connection with two sinuous filaments mounted one above the other in the bulb in the form of two cylinders of short axial length concentric to the lamp axis.