| 摘要 |
PURPOSE:To make dots formed on a photosensitive body uniform in size and to eliminate an irregularity in density and the inversion of the density by varying the quantity of a laser beam according to the main-scanning-direction position of the laser beam projected on the photosensitive body. CONSTITUTION:The projection beam of a laser diode 1 is converged on the photosensitive body 5 through an ftheta lens 4 and scanned in a main scanning direction. Further, this beam is photodetected by a photodiode 7 through a mirror 6 prior or the main scan and sent to a control circuit 8. A beam spot formed on the photosensitive body 5 varies in main-scanning-directional diameter with the angle of the laser beam incident on the photosensitive body 5 and a control circuit 8 adjusts the time of beam irradiation per clock so that the beam diameter is constant. Thus, the quantity of the laser beam is varied corresponding to the main-scanning-directional position of the laser beam to uniform the size of dots, thereby eliminating the density irregularity and the inversion of the density.
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