| 摘要 |
PURPOSE:To execute the correct focus servo gain adjustment for a short time by oscillating an objective lens near a focus point position. CONSTITUTION:A focus error signal FE from a subtracter circuit 12 is supplied to a lens driving signal generating circuit 15. The generating circuit 15 inverts the polarity of a lens driving signal each time of a focus error signal is supplied. Thus, in one cycle period of a lens driving signal, since the objective lens passes through a focus point position plural times, plural focus error signals FE can be obtained, the level detection of the focus error signals FE can be correctly executed by an FE level detecting circuit 19 and consequently, the correct focus servo gain adjustment can be performed for a short time. |
