| 摘要 |
PURPOSE:To always make the writing width in a reference number of pixels constant even when a scanning range extends and contracts, by measuring the position based on a predetermined clock pulse in place of the measurement of the time required in the scanning between two points. CONSTITUTION:For example, when one pixel interval V(t) becomes wide as compared with that at the time of assembling adjustment by some cause and V(e) becomes wide, the first beam lighting position G, an image writing position Q, an image writing finish position I and the second beam lighting position J are respectively shifted in a main scanning direction. The first beam lighting position and the second beam lighting position at this time are respectively detected by CCD 1(22alpha) and CCD 2 (22beta). The frequency (f) of an image clock is changed on the basis of detected positional shift quantity to perform control so as to obtain a predetermined one pixel interval. By this method, a definite one pixel interval, that is, the writing width in a reference number of pixels can be always made constant.
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