Patent ID: 6515436
Filing Date: 2003-02-04
Classification: H01J,H05B,Y02B

Abstract:
A discharge lamp lighting apparatus, comprising:a discharge lamp provided with a discharge vessel filled with an inert gas-dominated discharge agent and a pair of electrodes at least one of which is placed on the outer surface of said discharge vessel; a high frequency generator provided with a switching device for generating a high frequency voltage with a high frequency switching operation and an output transformer for outputting the high frequency voltage, for lighting the discharge lamp by supplying to the discharge lamp through the pair of electrodes with the high frequency voltage induced across a secondary winding of said output transformer; a high frequency operation detector for detecting at least one of the high frequency voltage and the high frequency current and thus producing a high frequency operation detection signal; a controller responsive to the high frequency operation detection signal for controlling said switching device of the high frequency generator, that is, it carries out a feedback control to the switching of the switching device so that the high frequency operation detection signal becomes nearly a predetermined level during normal operation, while it controls the switching device to carry out protection when an abnormal discharge control signal is supplied; and a no-load detector for detecting a no-load condition of the secondary winding of the output transformer and forcefully changing the high frequency operation detection signal supplied to the controller to a second level.