| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply device capable of preventing a lighting failure of LEDs caused when a total forward voltage of high output LEDs exceeds a power source voltage by correctly detecting such an abnormal state as a disconnection and a short circuit. SOLUTION: This power source device operates as the follows: a total forward voltage of a group of LEDs 6 is detected with a voltage detection circuit 5, and a forward current of the group of LEDs 6 is detected with a current detection circuit 7; an abnormal state of the group of LEDs 6 is detected by comparing the above detected voltage and current to a reference voltage value in a comparison circuit 9; and when an abnormal state happened, an abnormal information signal is output, thereby turning off a switch 2 and informing the abnormal state to the outside through an external information circuit 10. COPYRIGHT: (C)2007,JPO&INPIT |
