DISCHARGE LAMP LIGHTING DEVICE AND IMAGE DISPLAY DEVICE

摘要

An A/D converter (10) reads the output of a load voltage detector (5), and a microcomputer (4) determines a reference value (Is) and a switching frequency. A switching frequency timer (8) outputs a SET signal to a drive controller (9) so as to have the determined switching frequency, and a switching element (Q) is turned on. A current detector (6) outputs a RESET signal to the drive controller (9) when the current flowing to the switching element (Q) and detected by a resistor (R) exceeds the reference value (Is) in a reference calculator (7), and the switching element (Q) is turned off. The reference value (Is) and the switching frequency are so set that the switching element (Q) is subsequently turned on next time in the timing when the regeneration current of a diode (D) becomes substantially zero. Thus, without causing an increase of the cost of a discharge lamp lighting device, while performing a turn-on control on the switching element in the timing when the regeneration current becomes substantially zero, the switching frequency is controlled according to the condition of the discharge lamp.