| 摘要 |
PROBLEM TO BE SOLVED: To provide an induction-heated fixing device for which a high- responsiveness countermeasure with respect to abnormally high temperature is taken by utilizing the change of a coil voltage changed at the same time when the temperature of a body to be heated is changed, quickly detecting abnormally high temperature of the body to be heated by detecting the maximum value of the coil voltage and stopping a high frequency power source circuit supplying an AC current to the coil. SOLUTION: A necessary calorific value (heating output) is decided based on the temperature detected by a thermistor 6 arranged on the outside circumferential surface of the upper part of a fixing roller by a control means 50 as a control system for making a high-frequency current flow to the coil 9 of a fixing device. Then, a control signal is outputted and the high-frequency current flowing to the coil 9 is impressed. At this time, when the temperature of the fixing roller becomes abnormally high, a signal outputted from a maximum coil voltage detection circuit 55 becomes a level Lo and an inverter circuit 60 is immediately stopped. As the result, the fixing roller is prevented from being excessively heated. |
