| 摘要 |
PURPOSE:To stabilize a tracking servo loop, and to obtain a recording and reproducing signal with high quality, by setting the guide track depth of an optical disk memory medium within a prescribed range. CONSTITUTION:Between continuous guide tracks 1, an address pit having a depth of lambda/16<d2<=lambda/2 (lambda: wavelength of information signal reproducing light source, d2: optical depth of pit string) is provided. At this time, the optical depth d1 of the groove of a track 1 is assumed as lambda/4<d1<lambda/2. In this way, it is possible to inverse a tracking differential output signal compared with a time when the guide track depth is set at 0-lambda/4, and therefore, to obtain a tracking signal output by which polarity change on and between the grooves (on a land) at the time when the guide track depth is set at 0-lambda/4, can be canceled, in an area having a groove depth of lambda/4-lambda/2. Therefore, it is possible to keep the polarity of the tracking signal output, and to stabilize a servo characteristic. |
