| 摘要 |
PURPOSE:To make a device thin without damaging the sensitivity by providing a insertion hole, through which the tip part of a yoke arranged on the inside of an objective lens holding body is inserted in the approximate axial line direction of a supporting shaft, in the ojbective lens holding body. CONSTITUTION:An objective lens holding body 23 is provided with the insertion holes 31A and 31B in the axial line direction of a supporting shaft 22, and yokes 20d and 20e are inserted through these holes. Since a focus coil 35 and tracking coils 36A and 36B have not a double constitution on a circumferential side wall 23c of the holding body 23 and the movable weight of the holding body 23 is not increased, the sensitivity of focusing is not damaged. Further, since the outside diameter of the holding body 23 is not made large, the sensitivity of tracking is not damaged. On the contrary, the sensitivity is improved by the insertion holes of the holding body 23. Meanwhile, since the overall width of the circumferential side wall 23c of the holding body in the direction of the supporting shaft 22 is placed in magnetic gaps 37A and 37B between yokes 20d and 20e and yokes 27A and 27B by insertion holes and can be used effectively for the focus coil 35 and tracking coils 36A and 36B, the holding body 23 is made thin furthermore. |
