| 摘要 |
PURPOSE:To ensure an accurate control of an objective lens, by sticking the permanent magnet to the objective lens in a body and the giving the electric conduction to the coil provided at a place near the permanent magnet. CONSTITUTION:An objective lens 11 is set opposite to the surface of a disk, and the information recorded to the disk is read. A shift is detected in the tracking and focus directions respectively by making use the reflected light given from the disk. An electric signal is delivered in accordance with the detected shift and then applied to the tracking control coils 24 and 25 as well as to the focus control coils 26 and 27 as a compensating current. Thus the permanent magnets 15 and 16 are driven in the tracking and focus directions respectively. As a result, the lengs 11 is shifted to an optimum position with its optical axis kept vertical to the disk at all times. |
