| 摘要 |
PURPOSE:To eliminate the need for a transmission mechanism such as a rotary encoder by using a scale installed removably via a guide to a case and provided with a slit group so as to allow the scale to detect the speed in the subscanning direction in the same way as the detection in the main scanning direction. CONSTITUTION:The scale 6 provided with a slit S in the subscanning direction is arranged to the lower face of a case 8 via a guide 9, and the speed in the subscanning direction B-B when the case 8 is moved to the face of an original being a body to be radiated along the scale 6 is detected by the same method as the speed detection in the main scanning direction A-A. That is, the light from a light source 1 radiates the slit S of the scale 6 and the speed is detected by leading the reflected light to the end of a solid-state image pickup element 3 via a lens 2. Thus, a rotary encoder having been employed in a conventional reader is not required.
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