| 摘要 |
PURPOSE:To prevent a fixing failure, etc. by providing a zero crossing detecting circuit on an AC switch of an interlock switch, and inhibiting a copying operation when a zero crossing signal is not detected within a prescribed time after a DC switch of the interlock switch has been turned on. CONSTITUTION:An interlock switch 3 is provided in the vicinity of a front door of a copying machine body. The switch 3 consists of an AC switch 31 which becomes on when the door is closed, a switch 33 connected to a DC load, and a DC switch 32 which becomes on when the door is opened, and the switch 31 and the switch 33 are interposed between an AC power source 4 and a zero crossing signal detecting circuit 5, and between a DC power source 6 and a DC switch detecting part 7, respectively. Output sides of the circuit 5 and the detecting part 7 are connected to a controlling circuit 8 consisting of a microcomputer. When a zero crossing signal is not detected within a prescribed time after the switch 33 has been turned on, the circuit 8 displays interlock opening on an indicator 9 and also inhibits a copying operation. In this way, a fixing failure, etc. can be prevented. |
