| 摘要 |
PURPOSE:To simplify the constitution of a position detecting device and to reduce its position detection error by controlling the quantity of light emission of a light emitting element that the quantity of photodetection of a semiconductor position detecting element is constant. CONSTITUTION:An objective 5 is fitted to a supporting member 10 and bobbins 13 and 14 wound with movable coils 11 and 12 are fixed to both surfaces of the supporting member. One-side arms of magnets 15 and 16 are surrounded with the bobbins 13 and 14. Further, a light shielding plate 18 in which an aperture 17 is bored is fitted on one surface of the member 10. A light emitting diode 19 and the semiconductor position detecting element 20 are arrange across it. When currents are flowed through the coils 11 and 12, the member 10moves in a tracking direction A with magnetic force produced between the magnets 15 and 16. Then, the light shielding plate 18 moves to shift the aperture 17 in position and the direction of luminous flux from the diode 19 changes. A light spot on the element 20, therefore, shift in position, so the direction and extent of movement of the lens 5 are detected fro the output of the element 20. |
