Patent ID: 6239556
Filing Date: 2001-05-29
Classification: H05B,Y02B,Y10S

Abstract:
Circuit arrangement for operating a high pressure discharge lamp having, during operation, an electrode which is in a cathodic phase, comprising:input terminals for connection to a supply voltage source,output terminals for connecting the high pressure discharge lamp, andmeans, coupled to the input terminals, for supplying an alternating lamp current having successive periods of opposite polarity to the high pressure discharge lamp, each period having a first part and a second part, the lamp current per period having a mean value Im, wherein at the start of each period the lamp current is lowered with respect to the mean value Im so as to allow for stable diffuse attack on the cathodic phase electrode, and the electric energy supplied to the discharge lamp in the second part of each period is greater than the electric energy supplied to the discharge lamp in the first part of each period.