| 摘要 |
PURPOSE:To prevent dewdrops from being generated in an optical system and a photosensitive drum by detecting an internal temperature by a temperature sensor when an electric power source is turned on, and heating by a heater provided in the vicinity of the photosensitive drum for a constant interval of time when said temperature is below a prescribed temperature. CONSTITUTION:When an electric power source switch is turned on first in the morning, a switching circuit 32 is switched to a contact 34 from a contact 33 by a switching signal 31. A comparator 35 compares a signal from a temperature sensor 16 with a reference temperature signal from a reference voltage generating circuit 36, and outputs a driving signal 37 when a temperature of the former is lower than that of the latter. As a result, a timing circuit 38 outputs a driving signal 39 for a constant interval of time, a relaying circuit 13 is operated, a heater 11 generates heat, and dewdrops on the surface of a photosensitive drum 3 and an optical system 2 are prevented. On the other hand, a display controlling circuit 22 outputs a signal 41 by the driving signal 39, and turns on a display lamp 19 being in the course of erasing dewdrops. When the driving signal 39 rises, heating by the heater 11 is stopped, the lamp 19 is turned off by a signal 42, and a copiable display lamp 20 is turned on. |
