Patent ID: 8023362

Claim:
A hand position detecting device comprising: a first driving system in which a first driving motor transmits its rotation to a seconds wheel, which in turn drives a seconds hand; a second driving system in which a second driving motor transmits its rotation to a center wheel and an hour wheel, which in turn drive a center hand and an hour hand, respectively, wherein the seconds, center and hour wheels are rotatably attached on a same axis; and a detection unit, including light emission means, for detecting whether light emitted by the light emission means has passed through apertures provided in the seconds, center and hour wheels, respectively, to determine the respective rotational positions of the seconds, center and hour wheels when the seconds, center and hour wheels rotate; wherein the aperture in the seconds wheel comprises a first circular aperture provided at a reference position in the seconds wheel, and a second aperture and a third aperture spaced by first and second light blocking areas of different distances, respectively, in the driving and anti-driving directions of the seconds hand from a center of the first circular aperture; wherein the second and third apertures in the seconds wheel are arcuate and are provided substantially in opposed relationship on a same locus of rotation as the first circular aperture in the seconds wheel; and wherein the seconds wheel comprises a third light blocking area provided between the second and third apertures on a same diameter of the seconds wheel as the first circular aperture.