| 摘要 |
<p>A space S for housing an optical sensor 15 is formed between a detection gear 11 of a drive transfer gear and a frame 2 for supporting the detection gear. A detected part 11c shaped like comb teeth is formed integrally on inner walls of the detection gear 11. The optical sensor 15 is placed so that the detected part 11c passes through a space between a photo emitter 15a and a photo receptor 15b of the optical sensor 15. Since the detection gear 11 and the frame 2 protect the optical sensor 15 from stray light and interfering substances such as paper powder, or the like, a high-reliability, small-sized detection mechanism can be provided. <IMAGE></p> |
