| 摘要 |
PURPOSE:To obtain an electronic switch restoring short-circuit automatically by providing a display device or the like placed on a rapid charging circuit of a trigger circuit, lighted at the detection of an object and also flickered at a period based on the difference between the charging current of the charge circuit and the holding current of a thyristor at short circuit to inform the short-circuit state. CONSTITUTION:It is supposed that an object approaches a proximity switch with a load L short-circuited. Then a sensor circuit outputs an NL output and a large current flows to a thyristor 6 and an FET7. Since a current and voltage given to the sensor circuit 10, however, are decided to a prescribed voltage by a constant voltage circuit 9, the short-circuit current is limited to a prescribed value by the constant current characteristic of the FET7. The power voltage of the sensor circuit 10 repeats rising/falling at a prescribed cycle and a light emitting diode 15 for operation display is flickered accordingly. The cycle is set to, e.g., 1.5sec by adjusting the resistance value of a resistor R22. Thus, the operation of a short-circuit protection circuit is informed to the user in this way. |
