| 摘要 |
PROBLEM TO BE SOLVED: To always acquire a stable, high quality gradation image. SOLUTION: A pulse signal according to input multivalued image data is formed based on a prescribed forming condition by a PWM width table 43 and a PWM circuit 44, and then a semiconductor laser device 49 is lighted on or off according to the pulse signal. The pulse width of a continuing time period of lighting of a light emitted from the semiconductor laser device 49 is detected by means of a photodiode 50, a pulse width detector 47 and the like. A data converter 46 converts the pulse width to a digital data. A comparison computing section 45 detects a difference between the digital data and the input multivalued image data and changes the prescribed forming condition according to the difference. COPYRIGHT: (C)2006,JPO&NCIPI
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