PROBLEM TO BE SOLVED: To provide a light-emitting diode drive dimmer circuit capable of modulating light over a wide range, a light-emitting diode illumination device, a light-emitting diode backlight device, and a liquid crystal display device.;SOLUTION: An output voltage V1 applied to an LED row 9 is divided while the LED row 9 is turned on, with the result retained as a comparison reference voltage, and constant voltage control is exercised based on the comparison reference voltage while the LED row 9 is turned off, with the output voltage V1 referenced as constant voltage. Thus, a voltage during a turn-on period T1 during which the LED row 9 was turned on can be applied to the LED row 9 when it turns on again. That way, a delay time until a current IF flowing in the LED row 9 reaches a set current IF' can be minimized. Therefore, even when a duty cycle of a dimmer PWM signal is reduced, an LED drive dimmer circuit 1 can be maintained operative while the current IF flowing in the LED row 9 is in the sate of the set current IF'.;COPYRIGHT: (C)2012,JPO&INPIT
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