| 摘要 |
PURPOSE:To simplify the circuit constitution by constituting a circuit applying detection of a layer short-circuit caused in a high voltage coil and its protection by a protection fuse connecting to a low voltage coil side, a primary side current detection circuit, a gate circuit and a voltage smoothing circuit. CONSTITUTION:The layer short-circuit detection protection circuit 14 consists of a protection fuse 32, a sensing resistor 33 as a primary current detection circuit, a thyristor 34 as a gate circuit and a smoothing capacitor 35 as a voltage smoothing circuit. Then if a layer short-circuit takes place in a high voltage coil 26 being a component of a flyback transformer 20, the primary current flowing to the low voltage coil 22 is increased rapidly. The increase in the primary current is detected by the primary current detection circuit 33 and when the detection current capacity exceeds a reference value, the gate of the gate circuit is opened and a blown current is fed to a protection fuse 32. The protection fuse 32 is blows by the blowing current and then the operation of the flyback transformer is stopped. Thus, the fault of layer short-circuit is detected with simple circuit constitution. |
