DENSHIFUKUSHAKINIOKERUBETAKUROBOSHISOCHI

摘要

PURPOSE:To enable constant quantity of light to be irradiated to a photosensitive surface over a long period of time by providing a solid black preventing light source between the final mirror and exposure width limiting slit in an optical housing. CONSTITUTION:A solid black preventing device 8 is constituted of small size solid black preventing electric bulbs 5 arrayed in plurality in the slit lengthwise direction and a substrate 7 which holds these bulbs 5 in a home position and are printed with supply wires for supplying electric source. When copying is started by turning on a switch, the solid black prevening electric bulbs 5 installed in the position as close to the photosensitive surface 3 as possible without interfering the exposure at the main exposure between the final mirror 2 and a slit 4 for limiting exposure width in the time for driving the scanning system light, whereby the required quantity of light is irradiated to the photoreceptor via the slit 4. Next, at the same instant when the scanning system starts driving, the electric bulbs 5 go off and the light source for main exposure goes on. Thereby, the constant quantity of light may be irradiated onto the photosensitive surface for a ling time.