| 摘要 |
PURPOSE:To obtain an optical scanner which has high dust-proof effect, outputs a flicker-free output image, and eliminates the need to adjust the optical axis when a component is replaced by arranging a light source, polarizer, image forming lenses, and horizontal synchronizing signal detecting means at specific positions in an optical box, and sealing the box with a cover. CONSTITUTION:Laser light projected from a semiconductor laser unit 11 illuminates a detection mirror through an image forming lens 4a, a polygon mirror 2, and image forming lenses 4b and 4c. Its reflected light scans on the incidence port of an optical fiber tube 5 horizontally and is converted into a horizontal synchronizing signal by a photodiode 34. The semiconductor laser unit 11 is driven by using a recorded information signal a specific time later after said synchronizing signal is detected, making a scan on a photosensitive drum 3. The lenses 4a-4c and polarizer 2 are arranged on the bottom surface 17a of the optical box 17 on a base 1a, a side plate 17b is fitted with the laser unit 11, etc., and the box is sealed with the cover 21 to obtain the optical scanner which has high dust-proof effect, outputs a flicker-free output image, and eliminates the need for optical-axis adjustment in the replacement of a component.
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