| 摘要 |
PURPOSE:To always attain optimum focus control by raising the gain of a focus control circuit corresponding to the gain lowering of a pickup itself continuously or by stages and correcting it. CONSTITUTION:An objective lens 6 to converge light to an information recording medium (disk) 4, a detecting means 8 to detect an error to a reference distance between the recording face of the disk 4 and the objective lens 6, means 10 and 11 to control the gain of a focus control circuit corresponding to a error quantity detected by the detecting means 8 are provided. When a focus control capacity is lowered, the servo gain of a focus is set high, the focus control capacity is raised, at the same time, when an offset is not large, the gain of a servo is raised more than it is needed, and a focus error and a tracking error by an oscillation and so on can be not caused. Thus, a device to always reproduce in an optimum gain condition can be realized. |
