| 摘要 |
PURPOSE:To simultaneously measure the parallelism of respective sensitive body and an exposure device by providing plural detection means in a direction nearly perpendicular to the proceeding direction of a transfer belt. CONSTITUTION:A picture signal for pattern generation means for forming a pattern image for measuring every color on the transfer belt 21, the detection means 27a and 27b for detecting the passing of the respective color pattern image, a detection timing counting means by the detection means 27a and 27b, a comparison arithmetic means for comparing the counted value obtained by the detection timing counting means with a set value and operating the shear quantity in need and an each color write timing signal generation means which can be set and altered according to the output value from the arithmetic means are provided in a titled device. And plural detection means 27a and 27b are provided in the direction nearly perpendicular to the proceeding direction of the transfer belt. If the pattern is read by two sensors 27a and 27b and corrected with a previously stored time difference, for example, it can be measured whether or not the optical system and the sensitive body are parallel with a reference line on the belt.
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