| 摘要 |
PROBLEM TO BE SOLVED: To connect a lot of monitor cameras without increasing the current capacity of a power unit when the monitor cameras are serially connected to one power line. SOLUTION: A current limiting part 13 supplies a power source current, which is supplied from the power unit through a power line 4, while limiting it into prescribed current value. A charging part 14 performs charging on the basis of the current supplied from the current limiting part 13. Actually, it is better to limit the current from 20 mA to 30 mA. Power is ordinarily supplied from the charging part 14 to a main control part 12 but no power is ordinarily supplied to an image pickup part 10. When sending a video signal, the main control part 12 instructs the supply of power to the image pickup part 10 to a power source control part 15. According to this instruction, the power source control part 15 supplies the power from the charging part 14 to the image pickup part 10. Thus, image pickup operation is started by supplying the required voltage and current to the image pickup part 10.
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