| 摘要 |
PURPOSE:To prevent continuous mischievous operations by a method in which a sensor to detect the opening or closing of an operator cover and a circuit to hold a switching circuit for a given time period after opening the cover are provided, and unlocking signals are allowed to output only during the output period of holding signal. CONSTITUTION:A switch 16 to detect the opening or closing of a cover 11a is provided to an operating board 12 on which ten keys are arranged. A timer circuit to be actuated by the opening signal of the switch 16 is provided, and a holding signal is output for a given time period to the switching circuit which send a recitation number input only during the output period of holding signal to the judging circuit of recitation number. When the recitation number coincides, unlocking signal is putput from an unlocking controller. Also, when time is up during operation, the sending of recitation number is stopped to forbid unlocing. Therefore, the same operation is made again. Illegal unlocing can thus be prevented without interrupting usual operations. |
