GB548522A - Improvements in or relating to gaseous electric discharge devices - Google Patents

Abstract

548,522. Supply systems for space discharge apparatus. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Sept. 17, 1941, No. 11911. Convention date, Oct. 10, 1940. [Class 38 (iv)] [Also in Groups XL and XXXVII] A time delay circuit for use in the starting of a gaseous discharge lamp wherein the electrodes are given a preliminary heating includes in series with the electrodes a cathode glow switch 16 and a thermal switch 17 whose contacts 23, are normally closed. The two switches are mounted in a common casing and a radio frequency condenser 18 is connected across the glow swtich. This consists of an electrode in the form of a bimetallic element 20 carrying electrons emissive material 22, the element 20 moving into contact with the terminal 19 when heated by - a discharge ; the filling is neon argon or helium at 70 to 100 mm pressure. The heating of the element 20 maintains contact in the glow switch until current flow through this switch ceases and the element 20 cools. In the thermal switch 17 one of the elements 24 is a bimetal which is heated by the heater 25 when the starting circuit is closed and a discharge takes place in the glow switch 16 ; the heater 25 is designed to cause opening of the contacts 23 only after sufficient time has elapsed to allow the lamp electrodes to become sufficiently heated. Opening of the contacts 23 produces a transient surge from the ballast inductance to heat down the discharge gap. One of the contacts 23 may be of carbon to replace the heater 25 or the bimetallic element 24 may be used as the heater.