| 摘要 |
PROBLEM TO BE SOLVED: To reduce the driving current of a transistor and standby power by defeating a monitor sound output by using both the port control of a transistor circuit and the IIC control of an AVSW. SOLUTION: An AVSW1 selects a video audio signal to be inputted and performs main and monitor outputs. An IIC controlling part 2 outputs a signal controlling the output state of the AVSW and outputs a signal defeating a monitor sound signal in the case of a noise channel and when a power supply is on. A transistor circuit part 3 defeats a monitor sound output signal. A port controlling part outputs a signal controlling the part 3 and outputs a signal defeating the monitor sound output signal when a noise channel is switched and the power supply is on. The part 3 is driven by a defeat signal of the port controlling part 4, the monitor sound output signal is squeezed once, and a sound signal is completely defeated by a defeat signal of the part 2.
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