| 摘要 |
A hand position detecting device capable of detecting the position of a center hand in a short time, preventing wrong recognition of the center hand position due to manufacturing errors, and determining an exact driving position of the center hand. It is determined whether light has passed through apertures (21, 28 and 30) in a seconds, a center and an intermediate wheel 20, 25 and 23 and a relevant one of apertures (29) in an hour wheel (27), thereby determining their respective rotational positions. When the center wheel (25) rotates one step at a time in a predetermined direction to such a position that the apertures (28) and (30) in the center and intermediate wheels (25) and (23) align and a detection unit (13) detects light which has passed thorough the apertures (28) and (30), the center wheel (25) is returned 12 steps or more from that position in the reverse direction. Then, the center wheel (25) is again rotated one step at a time in the predetermined direction to the position where the detection unit (13) detected light first. When the detection unit (13) again detects light at that position, this position is determined as the reference position in the center wheel (25). Thus, even when the center wheel (25) contains manufacturing errors, its reference position is specified accurately.
|
