Rotational position detection device, hand position detection device and clock using the hand position detection device

摘要

To provide a hand rotational position detection device with small possibility of generating erroneous operations which can be miniaturized and a watch having the hand rotational position detection device.A hand rotational position detection device of a watch includes a light emitting part, a reflection face which is formed on a second support body which faces a first support body in an opposedmannerwith a gap G definedtherebetween and on which light from the light emitting part is obliquely incident, a light receiving part which is mounted at a position spaced apart from the light emitting part so as to receive light obliquely reflected on the ref lection f ace, and a disc like rotary body which is arranged in the gap defined between the first and the second support bodies and includes an opening which opens an incident optical path Pi leading from the light emitting part to the reflection face and a reflection optical path leading from the reflection face to the light receiving part when the disc-like rotary body assumes a first rotational position with respect to the first support body, wherein when the disc-like rotary body is at the first rotational position, an imaginary line which connects the incident and the ref lection optical path parts in which the incident and reflection optical paths pass through in the opening extended in the direction which intersects the radial direction of the disc-like rotary body. <IMAGE>