| 摘要 |
PURPOSE:To pull in automatically a signal read lens in a focus servo loop by moving a signal reader to a recording medium so that a read lens of the signal reader is placed in the focus servo loop with a focus error signal from the signal reader. CONSTITUTION:Just after the signal reader 10 is set, a drive section 13 approaches the reader 10 stepwise to an information recording medium 11. When the distance is within a prescribed value, the focus error signal from the reader 10 is inputted to a reference level generator 14 and a reference signal equal to a voltage of the focus error signal is inputted to a detection section 15. The absolute value and the absolute value of the focus error signal are compared by the detection section 15, and when the focus error signal is smaller, the detection section discriminates it that the read lens enters the focus servo loop to stop the signal reader 10 via the drive section 13. |
