Patent ID: 8441204

Claim:
A power supply device comprising: a DC output generation module configured to receive AC power, convert the AC power into DC power, and output the DC power; a semiconductor light-emitting element configured to receive the DC power output from the DC output generation module, and to emit light; and a control module configured to receive a dimming signal, and to control the DC power output from the DC output generation module in accordance with the dimming signal, the control module controlling the DC output generation module to dim and turn on or off the semiconductor light-emitting element by canceling control of the DC power based on the dimming signal during a predetermined time period beginning immediately after the AC power is supplied, wherein the control module comprises: a generation circuit configured to generate a first control signal based on the dimming signal, a differentiating circuit comprising a resistor and a capacitor, wherein the differentiating circuit is configured to output a differentiated signal in response to supply of the AC power, a switching element, wherein the switching element is turned on in response to the differentiated signal during a time period shorter than the predetermined period and short-circuits the generation circuit, and a reset circuit configured to discharge the capacitor immediately after the AC power is supplied, wherein the differentiating circuit is configured to generate the differentiated signal after the capacitor is discharged.