| 摘要 |
PROBLEM TO BE SOLVED: To prevent the thermal deformation of a housing, etc., and dew condensation and to avoid the deterioration of optical scanning performance while preventing a device from getting larger and the cost from rising. SOLUTION: In a cold district, a rotary polygon mirror 101 is driven to be rotated by a rotating and driving part 112 at a revolving speed higher than that at the normal image forming time immediately after turning on the power source of an image forming device in the morning, thereby, heat generated from the driving part 112 is stirred in the housing 102A by the high speed rotation of the mirror 101. Thus, the housing 102A and component parts such as an fθ lens 105 and a cylindrical lens 107 housed in the housing 102A are rapidly warmed, so that the thermal deformation of the housing 102A and the component parts of an optical system is prevented and the dew condensation on the component part can be rapidly removed. |
