| 摘要 |
PURPOSE:To prevent a user's shock fault (US fault) by stopping the operation of the flyback transformer when an abnormal heat is detected based on a difference between a power fed to the flyback transformer (FBT) and a high voltage output power of the PBT and on the result of detection of a high voltage output current. CONSTITUTION:When the FBT 30 reaches an abnormal heating state due to its internal heat and a voltage VBH exceeds a reference voltage Br1 corresponding to a fault detection level, an output of a comparator 4 changes from a low level to a high level. when the output of the comparator 4 reaches a high level, an output signal is inputted to a flip-flop 5 via an OR gate 6 and an output signal VQ of the flip-flop 5 reaches a high level and the signal VQ turns off a switch circuit 10 to interrupt the supply of B power supply to the FBT. Thus, the occurrence of the US fault is prevented. |
