Patent ID: 8208348

Claim:
A hand position detecting device comprising: a hand wheel including at least a first light transmitting portion provided at a reference point and second and third light transmitting portions spaced from the first light transmitting portion by non-transmitting portions; a stepping motor including a coil, a stator and a rotor, the stepping motor being configured to (i) alternately switch a direction of a magnetic field generated in the stator when a drive current, a direction of which is alternately changed per pulse, is supplied to the coil, and (ii) rotate the rotor 180 degrees in one step to drive the hand wheel; a photo detector configured to emit light at every even-numbered second during rotation of the stepping motor and detect light passing through the first, second and third light transmitting portions; a data memory configured to store identification data indicative of a supply state of the drive current having been supplied to a winding start terminal and a winding end terminal of the coil; and a hand position detection controlling section configured to read the identification data from the data memory and control the photo detector to detect a position of the hand wheel based on the identification data; wherein the second light transmitting portion includes a first arcuate aperture which ranges from a point of 8 seconds to a point of 16 seconds of the hand wheel and a second arcuate aperture which ranges from a point of 20 seconds to a point of 28 seconds of the hand wheel, and the third light transmitting portion includes a third arcuate aperture which ranges from a point of 32 seconds to a point of 40 seconds of the hand wheel and a fourth arcuate aperture which ranges from a point of 44 seconds and a point of 50 seconds of the hand wheel.