| 摘要 |
PURPOSE:To compensate the output of a signal detector with an output of wave detection, by recording a bit of a specific depth which is prewobbled based on a fixed rule, detecting the reproduced waveform of the bit based on a wobble rule and sampling and holding the output of wave detection. CONSTITUTION:It is supposed that a lead light spot passes over a dotted line with the spot center shifted to either one side not the center 210 of a track to a bit train 300 which is prewobbled up to lambda/4 depth (lambda: wavelength of reproduced light). In such a case, a lead waveform is obtained as shown by (b). The lead waveform has an amplification difference DELTA to a shift amount delta from the center of the track. The synchronous wave detection is given to the amplification difference with reference timing as shown by (c) to obtain a DC signal corresponding to an amplitude difference DELTA. Both the reference timing of (c) and a gate signal can be easily produced from a synchronous signal. A gate signal of (d) is used as a control signal to extract a prewobbled region. This process can give an integrated compensation to an offset contained in an optical system of an electric system of a 2D circuit. |
