| 摘要 |
PURPOSE:To relax temperature stress with respect to a photosensitive body or a developer by controlling a heater so that the temperature of a photosensitive drum can be higher than the outside air temperature measured by an outside air sensor by the prescribed degree. CONSTITUTION:The thermister Rt1 (3) of a temperature control circuit 5 measures the surface temperature of the photosensitive drum 1, while a thermister Rt2 (6) measures outside air. A comparator COMP compares a voltage at a point (a) with that of at a point (b). When the former is higher than the latter, the voltage of an output at a point (c) is set to 'H'. Conversely, when the former is lower than the latter, the voltage at the point (c) is set to 'L'. When the voltage at the point (c) is at 'H', a heater drive circuit 4 turns on the heater 2, and controls it so that the voltages at the points (a) and (b) can be equal. By adjusting a variable resistance VR, the voltages at the points (a) and (b) are equalized when the temperature of the photosensitive drum 1 is higher than outside air in a range of several deg.C-20 deg.C. |
