Electroptical detector for determining the position of the time display mechanism of a timepiece

In a timepiece of the type comprising time display means, a gearworks including rotary wheel means for driving said display means, drive means for actuating said gearworks, and an optoelectrical detection means for detecting the time of day being displayed, the improvement wherein said optoelectrical detection means comprises beam directing means for directing at least one beam of radiation toward said wheel means, and sensor means positioned for receiving said at least one beam, said wheel means comprising a plurality of wheels disposed inbetween said beam directing means and said sensor means for intersecting said at least one beam ahead of said sensor means in order to normally block said at least one beam from said sensor means, said plurality of wheel each including an orifice arranged to be periodically aligned with said at least one beam to permit the latter to be received by said sensor means at a predetermined rotational position of said plurality of wheels to provide an indication of the time being displayed, said plurality of wheels being driven incrementally, the diameter of the orifice in the most rapidly rotating one of such plurality of wheels being no larger than the distance which such orifice is rotated during each rotational increment, said plurality of wheels intersecting said beam such that said orifices in said plurality of wheels must be aligned simultaneously with such beam to actuate said sensor means.