Patent ID: 7692909

Claim:
A power supply device comprising: a rectifying unit which receives an AC supply voltage and rectifies the AC supply voltage to output a DC voltage; a capacitor which receives the DC voltage output from the rectifying unit; a switch unit which is disposed between the rectifying unit and the capacitor, provides the DC voltage output from the rectifying unit if the switch unit is closed, and cuts off the DC voltage output from the rectifying unit to the capacitor if the switch unit is open; and an overvoltage sensing unit which compares a voltage from the capacitor with a specified reference voltage, and if the voltage of the capacitor is higher than the specified reference voltage, generates an overvoltage cutoff signal to control the switch unit; wherein the overvoltage cutoff signal is used to report a power supply cutoff state; and a control unit disposed between the switch and the overvoltage sensing unit, the control unit controls a state of the switch and receives the overvoltage cutoff signal from the overvoltage sensing unit and reports the power supply cutoff state to a display unit for a predetermined time before the power supply is cut off by the switch.