| 摘要 |
PURPOSE:To shorten a printing time when a narrow-width form is used as to the optical scanning device of the electrophotographic device which forms an electrostatic latent image on the photosensitive surface of a photosensitive drum by scanning the photosensitive surface with light. CONSTITUTION:The light which is made incident on a polygon mirror 2 from a light source is split by a half mirror 5 to optical paths A and B and the optical scanning device is equipped with a reflecting mirror 7 which makes the light of the optical path B incident on a polygon mirror 2 so that the photosensitive surface 4 begins to be scanned with the light of the optical path B at one end part 4a of the photosensitive surface 4 and the scanning is continued till the mid-point 4C when the light of the optical path A reaches the mid-point 4c between one end part 4a and the other end part 4b by continuing the scanning from the one end part 4a of the surface 4 while a shutter 6 provided on the optical path B is open. Consequently, the scanning time is shortened to half when the scanning width is <=1/2 time as wide as maximum scanning width and the printing time can be shortened to half. |
