Patent ID: 8107324

Claim:
A hand position detecting device comprising: an optical detection unit configured to detect passage or non-passage of light through a first light-passing aperture in a seconds hand unit, a second light-passing aperture in a minute hand unit, eleven third light-passing apertures in 1-12 o'clock positions of an hour hand unit except at a specified o'clock position, and a fourth light-passing aperture in an intermediate wheel; a hand position detecting unit configured to optically detect positions of the seconds hand unit, the minute hand unit, and the hour hand unit based on a transmitted state or a non-transmitted state of light detected by the optical detection unit; and a hand position detection stopping unit configured to optically detect the positions of the seconds hand unit, the minute hand unit, and the hour hand unit by the hand position detecting unit at a time which occurs several minutes before every hour and to stop hand position detection by the hand position detecting unit when a number of times that the hand position detecting unit has successively failed to detect the positions of the seconds hand unit, the minute hand unit, and the hour hand unit has exceeded a predetermined number of times, the hand position detection being stopped until a predetermined time.