| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce device cost and improve reliability by providing such a structure that a host device can detect the presence of connector falling-off and abnormality of power source voltage in a slave device connected to the host device by connector connection with a small using number of connector pins. SOLUTION: The phototransistor 5T of a photocoupler 5 is inserted in series to a connector falling-off detecting signal line 1 for connecting the pins P1, P2 of a connector CN2 within a slave device 02. When a power source voltage 2 is present, a current is carried to the photodiode 5D of the photocoupler 5 through a resistor 3 to continue the phototransistor 5T. Thus, if the power source voltage 2 is present, and the connector pins P1, P2 are inserted to a connector CN1 by the connection of the connectors CN1, CN2, the detecting circuit 9 of a host device 01 can detect a grounding potential 8 in the route of the pin P1→the signal line 1→the phototransistor 5T→the pin P2.</p> |
