| 摘要 |
PURPOSE:To surely display the switching state of a switching element by integrating a closing time of a mechanical switching element by an integration circuit, energizing a diode section of a photocoupler by the result of integration and outputting a terminal voltage of a transistor part of the photocoupler as a signal representing the switching state of the switching element. CONSTITUTION:An integration circuit 200 integrates the closing time or the open time of a switching element 100 end energizes a diode section 301 of a photocoupler 300 by a voltage corresponding to the result of integration. As a result, the transistor section 302 is set in the saturating state and a terminal voltage Vt is kept to a ground potential. On the other hand, a transistor section 302 of the photocoupler 300 transits from the saturating state into the cut-off state suddenly when a voltage is lover than a value with the voltage energizing the diode section 301 decreased. Thus, even when the terminal voltage Vt is inputted to an external circuit such as a TTL logic circuit, the disadvantage residing longer in the uncertain region is not caused and the closing state and the open state of the switching element 100 are displayed surely. |
