| 摘要 |
A backlight device that is not affected by offset voltage. Driving transistor (41) operates such that current flows in LED circuit (11), and the detection voltage generated by current detector (42) and the reference voltage are input alternately to first input transistor (30a) and second input transistor (30b) of amplifier (20). Brightness adjusting switch (43) operates such that when driving transistor (41) is turned OFF during the OFF period of LED circuit (11), for example, during the horizontal blanking interval or vertical blanking interval, the detection voltage and the reference voltage are swapped, so that the average voltage generated in current detector (42) is equal to the reference voltage, and the effect of the offset voltage can be eliminated.
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