| 摘要 |
PURPOSE:To separately indicate troubles of a heater for heat fixation processing, a semiconductor switch, etc., by watching the state of semiconductor switching element, etc. for controlling power supply to the heater with a microcomputer through a photocoupler, etc. CONSTITUTION:Triac 15 for forming a semiconductor switching element is triggered in accordance with the detection temperature of thermistor 17 through temperature controllers 18, 16, and AC power is supplied to heater 13 to heat fix a copied image. When triac 15 is conducting, current does not flow to a photocoupler connected in parallel to this, and only when triac 15 is not conducting, transistors PTr1, PTr2 forming the photocoupler conduct. These states are watched with microcomputer 18. On the other hand, ON and OFF signals of triac 15 are provided from controller 16 to computer 18, troubles of heater 13 of the semiconductor switch for controlling the heater are discriminated, thus separate trouble indication being made. |
