| 摘要 |
PURPOSE:To prevent overheating accurately in a copying machine and a drier, by detecting a gas component produced from a body to be heated by heating, by a P type semiconductor gas sensor and a means of detecting its variation in resistance value. CONSTITUTION:A P type semiconductor gas sensor 1 is provided near copying paper 2 having charged toner which is a body to be heated. A resistance-value variation detector 3 is connected to the sensor 1 to detect the variation in resistance value of the sensor 1. A heating-power controller 4 is connected to the detector 3 and the controller 4 controls electric power for heating by a gas detecting signal from the detector 3 to control the heating temperature of the copying paper 2 by a heating means 5, thereby preventing the overheating of the copying paper 2. The P type semiconductor gas sensor 1 detects vapor produced from the body 2 to be heated or reducing gas such as carbon monomxide to control the heating of the body to be heated, thereby performing accurate overheating prevention which corresponds to the heating state of the body to be heated. |
