| 摘要 |
PURPOSE:To detect the fault point of a heater for a fixing device and to enable the rapid repair by detecting the current of the heater and a switching element for driving the heater and deciding the fault by comparing the detected result with the presence or absence of heater driving signal. CONSTITUTION:A fixing device control circuit controls the surface temp. of a heater roller of the fixing device 14 to be at a prescribed temp. and detects the fault of the fixing device 14. The heater 14c disposed in the heat roller of the fixing device 14 is connected via a triac (switching element) 62 to a commercial power source 51. The presence or absence of the output of the heater driving signal is first judged after turning on the power source. Such a decision is made that the triac 62 is abnormally short-circuited if the signal is not outputted and the current flows to a current transformer 61. Such a decision is made that the triac 62 is abnormally open if the heater driving signal is held outputted and unless a photocoupler 65 is on. On the other hand, a disconnection of the heater 14c, etc., are decided if the photocoupler 65 is off and the current flows to the current transformer 61. |
