| 摘要 |
PURPOSE: To prevent the generation of arc or current leak by stopping power supply by exactly detecting the disconnection of printed wiring foil caused by the crack of a printed wiring board. CONSTITUTION: Printed wiring foil B for detection is provided along main printed wiring foil A having high possibility to generate arc or current leak because of disconnection when the printed wiring board is cracked, its one end is connected to ground, and the other end is connected through a resistor 4 to a DC power source 10 and connected through a resistor 5 to the ground. A power source opening/closing relay 7 for opening/closing power feeding from the DC power source 10 to the main printed wiring foil A and a microcomputer 6 for controlling that relay are provided and when the printed wiring foil B for detection is disconnected and a potential at a common junction C of the resistors 4 and 5 gets higher than a ground potential, the microcomputer 6 inputs that potential change and stops power supply to this main printed wiring foil A by driving the power source opening/closing relay 7. |
