| 摘要 |
PURPOSE:To simplify the parts needed for focus control and at the same time to decrease the time delay of the focus control, by providing a lens function to a slider which can float up with shift or revolution of a recording medium. CONSTITUTION:A floating slider 8 incorporates a beam focusing lens 3' and the reflected beam given from an optical recording medium 7 arrives at a photodetecting element after passing through the lens 3'. The slider 8 can keep automatically a constant floating distance E from the optical recording medium. This distance E can be changed by controlling the form of the slider 8, the rigidity of a support part 9 of the slider 8 and the relative speed between the medium 7 and the slider 8. Thus it is possible to control the focus of the record signal with extremely small parts. Furthermore, the distance E can be controlled to the constant value by the slider 8 itself with no use of a complicated control circuit or a lens drive part. Therefore, it is possible to control a focal point assuredly despite the increase of the relative speed between the slider 8 and the medium 7. |
