GB894812A - Projection lamp - Google Patents

Abstract

894,812. Projection lamps. SYLVANIA ELECTRIC PRODUCTS Inc. Dec. 15, 1960 [Jan. 21, 1960; Feb. 1, 1960], No. 43236/60. Class 39(2) A projection lamp comprises a sealed bulb enclosing a reflector and a filament supported by conducting wires, the coil having a stretched out turn near each end. A mandrel is inserted in each end of the coil, the turn of the coil at the inside end of. the mandrel being stretched out so that part only of it is in contact with the mandrel. The filament is designed to operate at between 20 and 23 volts preferably at 21À5 volts, with a wattage of 150 watts. The filament consists of a coiled-coil 29 having short coils 28 on each side, one turn 30, 31 on each side being pulled out and a mandrel 34 being inserted in the parts 32, 33 of the coil beyond the pulled turns to regulate accurately the length of the incandescent part of the filament and to facilitate its attachment to support wires 4, 5. The reflector 3 has an aperture in which is inserted a ceramic block 6 through which the wires 4, 5 pass being welded at the rear of the block to wires 12, 18 connected to two pins in the base of the lamp. The reflector may be parabolic with the filament at its focus or elliptical with the filament at the nearer forms. The reflector is supported by two tabs to which are welded supporting wires connected to two further pins in the base of the lamp. To avoid blackening these pins are not connected to either side of the voltage supply. The base is enclosed by a metal cap having locating projections and a sleeve extension enclosing the sealed exhaust tube, the extension having a key to facilitate aligning of the lamp in the socket which may be of the type described in Specification 807, 744.