| 摘要 |
PURPOSE: A dimming circuit for an inverter is provided to achieve improved luminance ratio and prevent a frequency interference by adopting both the burst dimming system and linear dimming system. CONSTITUTION: A dimming circuit(100) for an inverter(10), comprises a linear dimming circuit(110) for lowering the level of the dimming input voltage input from an external source and outputting the linear dimming voltage to an adder(19); a chopping wave generating circuit(120); a first comparator(130) having an input terminal connected to a line connected to the linear dimming circuit and the adder, the other input terminal connected to an output side of the chopping wave generating circuit, and an output terminal connected to an end of the adder, wherein the comparator compares signals in accordance with the control signal output from an external source and outputs the result of the comparison to the adder; a second comparator(140) having an input terminal connected to a dimming input terminal for outputting a dimming input voltage, the other input terminal connected to a ground, and an output terminal connected to a control terminal of the first comparator, wherein the second comparator compares the size of the dimming input voltage input from an external source with a reference voltage, and operates the first comparator by outputting a control signal to the first comparator when the dimming voltage is higher than the reference voltage; and a power switching circuit(150) connected between the output terminal of the second comparator and the control terminal of the first comparator, and which is switched by the signal output from the second comparator and operates the first comparator.
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