| 摘要 |
PURPOSE:To achieve simplification of structure, easiness of regulation, and reduction of cost, by a method wherein a process is finished by a BD signal from one beam detector without detecting a second BD signal. CONSTITUTION:One cycle f of a BD signal is irradiation time while two faces of an even face and an odd face of a rotary polygon mirror are irradiated by a laser beam. A first video signal and a second vide signal are outputted as each data of a specific line of a photo sensitive drum to be emitted during a period f, and laser beams are emitted based on those video signals. After a time of DELTAt has elapsed from timing when the BD signal indicating detection of a first leser beam is outputted, the first video signal is outputted, and the first laser beam is emitted. Further, when elapsed time reaches (f/2)+DELTAt from timing when the BD signal is outputted, the second video signal is outputted, and the second laser beam is emitted. |
