| 摘要 |
PURPOSE:To prevent unnecessary photoirradiation, to reduce the power consumption by a light emitting means and to save energy by providing the light emitting means whose lighting width is increased/decreased in accordance with the size of an original and irradiating the original with an optional irradiation width. CONSTITUTION:A light source unit 40 being the photoirradiation means of exposure device exposing a photoreceptor is provided with a flux distribution adjusting plate 44 having 1st to 7th exposure lamps 41a to 41g being plural light emitting means, provided with a reflector on its back surface and further uniformizing irradiation light quantity over the entire length of the 1st to the 7th exposure lamps 41a to 41g above. The original is irradiated corresponding to the size of the original in a state where only an exposure lamp necessary for irradiating the original is lighted and the unnecessary exposure lamps are unlighted among plural exposure lamps 41a to 41g, so that the number of the exposure lamps used at the time of exposing is reduced in the case of the small- size original. Therefore, the power consumption is reduced, the quantity of heat generated reduced and the power consumption required for cooling a peripheral device is reduced. |
