| 摘要 |
PURPOSE:To reduce the DC gain of a servo system by providing the titled system with a means for detecting that a recording medium reaches the focal position of an optical system, turning on the servo system, holding the output of a driving signal generating means and adding the held signal to a driving means of the optical system continuously. CONSTITUTION:At the start of automatic focusing servo operation, the automatic focusing servo system separates an optical system 6 once from the recording medium 1 while keeping the optical system in off-state. The servo system is provided with a means generating a driving signal bringing the separated optical system 6 gradually close to the recording medium 1 and the means for detecting that the recording medium 1 reaches the focal position of the optical system 6, turning on the servo system, holding the output of the driving signal generating means as a value at that time, and applying the held signal to an optical driving means. |
