| 摘要 |
An image forming apparatus comprising a photosensitive body, a scanner including a laser light source for scanning the photosensitive body by a laser beam emitted from the laser light source, a modulation circuit for pulse-width-modulating or pulse-number-modulating the laser beam by an input digital image data which is synchronized to a clock signal, and a driving circuit for driving the laser light source by an output modulated image data of the modulation circuit. The modulation circuit includes a high-speed clock generator for generating a high-frequency clock signal which has a frequency higher than the clock signal, a counter for counting pulses of the high-frequency clock signal, a resetting circuit for resetting the counter when a counted value reaches a predetermined value, and a pulse signal generator for generating as the modulated image data a pulse signal having a pulse width or number dependent on the input digital image data and the counted value of the counter.
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