Patent ID: 6844682

Claim:
A gas discharge lighting system for regular and emergency lighting comprising: a gas discharge lighting device; a source of alternating current input power; an electronic ballasting circuit having a direct current requirement and coupled between said gas discharge lighting device and said source of input power comprising: an alternating current-to-direct current conversion means; a power regulator connected to said conversion means for converting the output of said alternating current to direct current conversion means to a regulated direct current required to operate said ballasting circuit; a controllable output direct current to alternating current inverter that operates with a substantially square wave output at a frequency above that of audible sound; an impedance network interposed between said inverter and said gas discharge lighting device to modify said substantially square wave output of said inverter to provide a proper operation of said gas discharge lighting device; a controlling device that controls the operation of said inverter and thus, via said impedance network, an amount of power delivered to said gas discharge lighting device; a connection between said source of alternating current input power and said controlling device to allow said controlling device to monitor a presence or an absence of said alternating current input power; and an external source of direct current input power coupled by an unidirectional current flow device to an input of said power regulator.