LIGHTING DEVICE FOR DISCHARGE LAMP, BACK LIGHT UNIT, AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To appropriately control the lead wire current of a filament at the time of burst light control with a narrow preheating design range. SOLUTION: The lighting device for discharge lamp includes: an inverter circuit IV which converts a DC voltage Vdc into a high frequency voltage and lights a hot cathode lamp La; a control circuit 1 which receives a burst light control signal Sb and controls the inverter circuit IV by a frequency capable of lighting the lamp in a switch-on period and by a frequency that is higher than the frequency of the switch-on period and cannot maintain lighting in a switch-off period; a preheating circuit PH which outputs a preheating current according to the frequency of the inverter circuit IV and supplies continuously to a filament a preheating current with different actual values between the switch-on period and the switch-off period of burst light control; a detection circuit 2 which detects a lead wire current IL2 of the filament f2; and an error amplifier 3 which compares the detected signal of the detection circuit 2 and a reference signal corresponding to the burst light control signal level and outputs an error signal. The error signal output from the error amplifier 3 is feedback controlled only to the frequency of the switch-off period of the burst light control controlled by the control circuit 1. COPYRIGHT: (C)2010,JPO&INPIT