| 摘要 |
PURPOSE:To form an image with desired picture quality stably by setting a ratio of a luminous period to a non-luminous period of an exposed light by a luminous means depending on an environmental condition or a surface potential of a photo receptor or a density distribution state of an original image. CONSTITUTION:A printer head section 31 uses a read signal processing section 20 to control a luminous period of a semiconductor laser and a luminous duty ratio based on a discrimination result signal representing discrimination of a type of a picture in the processing block unit comprising a prescribed picture element matrix and on an environment (temperature and moisture) around a photo receptor. In the case of a binary picture such as a character, a laser beam whose luminous duty ratio is 100% is subject to intensity modulation. Thus, an image with high resolution is formed. Furthermore, in the case of a multi-value picture such as a photograph, the luminous period and the luminous duty ratio are revised depending on a change in the photo sensing characteristic of a photo receptor drum due to a change in an environment such as temperature and humidity. Thus, a pitch noise in the subscanning direction is not made distinct and a more excellent image is formed. |
