GB591440A - Improvements in electric switches for initiating the discharge in fluorescent tubular lamps and other gas discharge electric lamps - Google Patents

Abstract

591,440. Thermal switches. R E V O ELECTRIC CO., Ltd., and FELTON, A. E. June 27, 1945, No. 16385. [Class 38(v)] A switch for initiating the discharge in a gas discharge lamp comprises a bimetallic strip b<6> carrying a contact b<8> which normally engages a contact b<7> carried by a metal strip b<5>, the lower ends b<4>, b<3> of the strips projecting from the annular wall of an insulating base a. The position of the contact b<7> can be adjusted by means of a screw a<1>. Surrounding but insulated from the bimetallic strip b<6> is a heating coil d the ends of which are connected to a second pair of metal strips projecting from the base a. These strips and the strips b4, b<3> form the terminals for connection to the lamp circuit, the contacts b<7>, b<8> normally bridging the gas column in the lamp. To light the lamp, current is sent through the four terminals of the switch whereby the coil d and the thermionic electrodes of the lamp are heated till the strip b<6> bends sumciently to open the contacts b<7>, b<8> thus producing sufficient potential difference between the lamp electrodes to initiate the discharge. The screw a<1> is adjusted to ensure the necessary time lag between the flow of current and separation of the contacts b<7>, b<8>.