| 摘要 |
PROBLEM TO BE SOLVED: To reduce the consumption of current of a power-on device which determines whether the power should be on according to an input signal. SOLUTION: The input of a composite image signal including a negative vertical synchronous signal is detected by a transistor Q11 and a current detecting circuit 23 and thereby a source of current 26 is driven and then a source of current 28 is turned off by reversing the output of a hysteresis comparator 29 and thereby a source of voltage 30 is driven to supply power. When a signal which does not include a negative vertical synchronous signal is input, the source of current 26 is turned off and the source of current 28 is turned on and thereby the input of the hysteresis comparator 29 becomes a low level and therefore the source of voltage 30 does not operate and does not supply power, either. |
