| 摘要 |
PURPOSE:To reduce the number of parts of a pedal rotational frequency detector and to simplify the mechanism by providing a device which detects the number of teeth of a gear or a pulley with a light emitting device and a photodetector and detecting the pedal rotation number with this detected result. CONSTITUTION:A light emitting element 9 and a photodetector 10 are provided to face each other on both sides of a certain position 7 on the outside circumferential part of a gear 8 in the rear part. That is, the light emitting element 9 and the photodetector 10 face each other with teeth 11 of a rear gear 8 between them. Thus, according as the rear gear 8 is rotated, teeth 11 intercept the light from the light emitting element 9 to detect the pedal rotation number. Though the gear 8 is used in this example, a pulley having teeth is also usable. |
