| 摘要 |
PROBLEM TO BE SOLVED: To enable protecting circuit components in the case of a short mode failure of high impedance by detecting comprehensively an abnormal state of a power source unit and cutting off an AC input. SOLUTION: When a second switching element 3a of a power-factor improving circuit 3, a first switching element 4a of a switching regulator 4, and the like generate shortcircuit failure in the state that a circuit impedance is high, a temperature detector 9 detects temperature rise of the first and second switching elements 4a, 3a, transmits the information to an abnormality detecting circuit 11, and makes a breaking circuit 12 cut off an AC input. When an output voltage detecting circuit 7 and an output current detecting circuit 8 detect abnormality of an output voltage and an output current, the breaking circuit 12 cuts off the AC input through the abnormality detecting circuit 11. When fuming is generated by the other causes, the breaking circuit 12 cuts off the AC input through the abnormality detecting circuit 11 in the same manner as the above, at a time point when a smoke detector 10 detects the fuming state. |
