| 摘要 |
PROBLEM TO BE SOLVED: To obtain a power source circuit capable of preventing destruction of an element and properly detecting generation of a short-circuit. SOLUTION: When an output terminal S1 is short-circuited while a DC voltage V1 is being supplied to a CCD imager, terminal voltage of a resistor R10 changes from a high level to a low level. As a result, output of an EXOR circuit 16a shows a high level, a transistor T6 is changed from an off state to an on state. Then, voltage to be provided in a short-circuit detecting circuit 20 is remarkably lowered and thus, the short-circuit is detected. When the short- circuit is detected, a controi circuit 18 is promptly disabled by the short-circuit detecting circuit 20. As a result, output of a control pulse is interrupted and the off state is continuously taken by the transistor T3. Namely, input of a battery Vs is interrupted. When the short-circuit is generated in the output terminal S1, the transistor T3 is promptly turned off, therefore, a transistor T1 is not destroyed.
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