| 摘要 |
PURPOSE:To prevent the abnormal rise of internal temp. by controlling the calorific value of internal heating means according to the temp. differences of the inside and outside of an apparatus so that the calorific value is increased when said differences are large and is decreased when small. CONSTITUTION:The images of an original 4 are lighted by a halogen lamp 5, and are reflected by the 1st, 2nd mirrors 6, 7 so that they are formed on a photosensitive drum 10, which is rotating in an arrow direction, by way of a mirror lens 8 and the 3rd mirror 9. On the other hand, a heater 1 for preventing dewing which is heating means is disposed below the mirror lens 8. Thermistors are provided in order to detect the temp. T1 of the cold air in the apparatus and the temp. T2 near the heater 1 and outside the apparatus, whereby the temp. difference T2-T1 is detected and is converted to a control signal. If T2-T1 is large, the calorific value of the heater is increased by a phase circuit D and is decreased when small. |
