| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a circuit for acquiring the switching status of a relay type power switch in which the reliability is enhanced by substituting a photocoupler for a monitor relay thereby preventing erroneous operation due to the difference of a lowest driving voltage or the counter electromotive force at the time of switching. <P>SOLUTION: A switch 8 is closed by applying a voltage to the internal power supply line/external power supply line. A power supply switching relay 1 is switched to the terminal 2 side by delivering a signal to a relay control line 6. Since +28V is applied to the input side of a photocoupler 7 through the external power supply line to a diode 5 to a power switch 4 to the terminal 2, the photocoupler 7 is turned on and a voltage monitor 9 has an LO level. When the power switch 4 is switched to the inner terminal 3 side by applying a signal of reverse polarity to the relay control line 6, the power supply line of an apparatus is connected with the internal power supply. Since the terminal 2 is opened and the photocoupler 7 is turned off, the voltage monitor 9 has a HI level. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
