GB317483A - Improvements in or relating to electric incandescent lamps - Google Patents

Abstract

317,483. General Electric Co., Ltd., (Assignees of Patent-Treuhand-Ges. f³r Elektrische Gl³hlampen). Aug. 17, 1928, [Convention date]. Addition to 297,833. Cut-out arrangements.- Cut - out devices as described in the parent Specification are applied to the caps of bulbs, intended to be used in series, by using the cap contacts as the outer metallic layers of the cut-out, the non- metallic layers forming a bridge between the contacts to short-circuit the bulb when its filament fails. The contacts are formed of, or coated with, lead or silver and are bridged by a layer consisting of or containing cuprous iodide or oxide. In the construction shown in Fig. 2, the centra contact b of a. screw cap is connected to the shell contact a by a number of strips e of cuprous iodide inserted in grooves in the insulating material of the cap. The iodide may be applied by mixing it with a binder of shellac solution, filling it into the grooves, and then evaporating the binder. Salts of easily fusible metals, such as cuprous or lead chloride may be added to the iodide paste so as to decompose and form a conductive metallic connection when the filament fails. In the construction shown in Fig. 3, a cap f coated with lead or silver is soldered to the centre contact b and extends nearly to the shell contact a, the iodide bridge g<1> being clamped in the intervening gap. The bridge may be formed by a lead wire coated with cuprous iodide, the lead serving to solder the parts a, f together when the bridge is pierced. The device may be similarly applied to bayonet-cap bulbs.