Yamaha Corporation

Minoru Saito

Kazuhiko Honda

Kazunobu Fujiwara

Kei Tanaka

Toshihito Uchiyama

Push-pull signal is created on the basis of reflected-light detection signals output from four divided light receiving elements that receive a reflection of a recording laser light beam off an optical disk. The push-pull signal is sent to a gain variation circuit. The push-pull signal is normalized by setting the gain of the gain variation circuit to a low level in response to a mark forming section of a recording signal, but to a high level in response to a blank forming section of the recording signal. Wobble detection and pre-pit detection are performed on the basis of the normalized push-pull signal.

Optical disk recording apparatus having push-pull signal processing circuit, wobble extraction circuit and pre-pit detection circuit

Information recording area of an optical disk is divided radially into a plurality of recording areas with a boundary area interposed therebetween. The boundary area is formed as either a high-reflection area that presents a higher reflection light level than the divided recording areas or a low-reflection area that presents a lower reflection light level than the divided recording areas. When an instruction is given to move an optical head from a current point to the target point over the optical disk, a seek operation is performed up to the start point of one of the divided recording areas that contains the target point, while detecting, on the basis of a variation in the reflection light level, the boundary area located between another one of the divided recording areas that contains the current point and the divided recording area containing the target point. Then, a further seek operation is performed up to the target point by calculating a distance, from the start point of the divided recording area containing the target point, to the target point. With this arrangement, a method is provided which can perform an appropriate seek operation at high speed even on an optical disk that mixedly includes areas of different recording densities.

Seek operation on different recording density regions based on the reflection of a boundary area

CLV-type recordable optical disk includes a plurality of tracks which are formed in such a manner that 2&pgr;Tp/&lgr; substantially equals an even-number multiple of 0.5 where Tp is a track pitch and &lgr; is a wavelength of a track wobble. Each of the tracks is divided into a plurality of ECC blocks, and each of the ECC blocks is composed of 16 sectors. Each of the sectors is composed of 26 sync frames. In each of the sectors of the track, information recording areas are set normally in even-numbered sync frames. However, in each portion where there would occur overlap in the information recording area, in the radial direction of the disk, between the track and an adjoining track located inward of the track, the information recording areas are set in odd-numbered sync frames. One piece of address information is divided into a plurality of address information elements and recorded dispersedly in the sync frames across a plurality of the sectors. With such arrangements, the optical disk can minimize adverse influences that would result from cross-talk between wobble signals from the adjoining tracks.

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Hamamatsu, Japan

Minoru Saito