Patent ID: 6147462
Filing Date: 2000-11-14
Classification: H05B,Y02B,Y10S

Abstract:
A ballast for parallel operation of discharge lamps, comprising:an inverter including a plurality of line branches, each line branch having a respective switching element controlled via a control input, at least two of the plurality of line branches being individually assigned to a respective one of the discharge lamps;a drive circuit which is connected to the control inputs of the switching elements and switches the switching elements on and off; anda monitoring circuit for monitoring the voltages of the discharge lamps independently of one another to determine whether a starting voltage is present across the discharge lamps for longer than a preset time interval, and if a voltage detected across one or more of the discharge lamps at an instant of time after a given ignition time overshoots an operating voltage of the one or more of the discharge lamps, blocking, via the drive circuit, the driving of only the switching elements arranged in line branches assigned to the one or more of the discharge lamps.