| 摘要 |
PURPOSE:To reduce influence due to face run-out of a polyhedral mirror and to improve printing quality by scanning and exposing plural light beams projected from a laser oscillator and modulated by a modulator on a part on which an image is formed only by a single rotary polyhedral mirror. CONSTITUTION:Two beams (a), (b) projected from the laser 21 are made incident to the modulator 23 through a lens 22 and the 0-order diffraction beam is absorbed to a beam stopper 35. The projected 1st diffraction beam is made incident to modulators 29a, 29b through a lens 28, and after adding an electric video signal corresponding to printing information is applied to the beam, is made incident to the rotary polyhedral mirror 33 through a reparalleling lens 30, a cylindrical lens 31 and an optical element 32 and swept horizontally, so that the beam forms spots S1, S2 having a prescribed interval in the subscanning direction of a photosensing body 36 through an F-theta lens 34. The spots S1, S2 irradiate a part other than characters to be printed out on the photosensitive body and attenuate the potential to form a positive charge character pattern. Consequently, the influence due to face run-out of the polyhedral mirror is reduced and the printing quality is improved. |
