| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that an error of losing information occurs, and drawing-in of focusing and tracking becomes unstable, when both a low-density disk and a high-density disk are reproduced and recorded. <P>SOLUTION: A DSP34 makes a light source of longer wavelength emit light to discriminate the type of the loaded disk 12, based on a signal from an amplitude detection means when a convergent lens 10 is driven for approaching a disk 12 and then receding from it. When the light source of the wavelength is discriminated, a filtering operation signal is supplied to a feedback loop. When it is not discriminated, the DSP34 instructs light emission of a light source of shorter wavelength. <P>COPYRIGHT: (C)2007,JPO&INPIT |
