| 摘要 |
PROBLEM TO BE SOLVED: To provide a fixing device equipped with a protective circuit which operates by detecting an AC power voltage applied to a fixing roller, even when an insulating layer of the fixing roller is in the middle of insulation deterioration. SOLUTION: In the fixing device equipped with a fixing roller 40 constituted by laminating a planar heating element 42 through an insulating layer 44 on the inside wall of a metal cylindrical body 43, and the protective circuit 51 for preventing overheating of the planar heating element 42 by a breakdown between the metal cylindrical body 43 and the planar heating element 42, the protective circuit 51 has a reference voltage generating circuit 36 which generates the reference voltage, a voltage detection circuit 34 which detects the voltage of the metal cylindrical body 43, an abnormality detection circuit 30 which outputs an abnormal detecting signal when a detection voltage exceeds the reference voltage by comparing a detection potential detected by the voltage detection circuit 34 and the reference voltage, and a cutoff circuit 22 which detects an abnormal detecting signal and intercepts an electric power supplied from a power source to the planar heating element 42. |
