Patent ID: 7449676

Claim:
An optical transducer device comprising: a sensor/emitter element that forms a sensor gap; a motor shaft having a uniform diameter; a printed circuit board; a hub; and an optical transducer element comprising: a pre-positioning opening for a preliminary position of the hub; a fine-adjustment opening for a centered fine-adjustment position of the hub, the fine-adjustment opening having a diameter corresponding to the diameter of the motor shaft; and a guide feature comprising a slot-shaped hole having a transfer guide that runs radially from the pre-positioning opening to the fine-adjustment opening, said slot-shaped hole having a width smaller than the diameter of the motor shaft and narrower in said transfer guide section than in either of the pre-positioning or fine-adjustment openings, wherein the printed circuit board is soldered prior to mounting the optical transducer element, the hub is mounted on the motor shaft, the motor shaft is positioned in the preliminary opening of the optical transducer element such that the peripheral edge is located outside said sensor gap, and slid along the transfer guide section so as to position the motor shaft in the fine-adjustment opening of the optical transducer element such that the peripheral edge at least partially reaches into the sensor gap; and the optical transducer device is pressed onto the hub.