Matsushita Electric Industrial Co., Ltd.

Shunji O'Hara

Takashi Ishida

Kenzo Ishibashi

Tadashige Furutani

Toshio Satoh

Motoshi Ito

Takashi Inoue

Sadao Mizuno

Noboru Ito

A a recording method and apparatus for an optical disk employs a data format having a fixed pattern sync portion in which a minimum run length of zeros and the maximum run length of zeros are not adjacent to each other. As such temperature difference caused during recording the optical disk may be made smaller, thermal stress applied upon the medium may be reduced, the deterioration thereof may be restrained, and the repetitive frequency of the medium may be improved.

Recording method and recording and reproducing apparatus for optical disk

A recording method and apparatus for an optical disk employs a data format having a fixed pattern sync portion in which a minimum run length of zeros and a maximum run length of zeros are not adjacent to each other. As such temperature difference caused during recording the optical disk may be made smaller thermal stress applied upon the medium may be reduced, the deterioration thereof may be restrained, and the repetitive frequency of the medium may be improved.

A recording method and apparatus for an optical disk employs a data format having a fixed pattern sync portion in which a minimum run length of zeros and a maximum run length of zeros are not adjacent to each other. As such, temperature difference caused during recording the optical disk may be made smaller, thermal stress applied upon the medium may be reduced, the deterioration thereof may be restrained, and the repetitive frequency of the medium may be improved.

An optical head system designed to accomplish an information recording and/or reproduction from opposite disc surfaces of an optical disc with the use of a single light source. The optical head system comprises a source of light for providing a linearly polarized beam of light; a collimator lens for collimating the linearly polarized beam of light into a collimated beam of light; a polarizing direction rotating unit for arbitrarily varying a direction of linear polarization of said beam of light; a polarizing beam splitter for dividing the beam, whose direction of linear polarization has been varied, into first and second beam components; and objective lenses for focusing the first and second beam components into respective penciles of light which are projected onto first and second, opposite disc surfaces of an optical disc or one disc surfaces of respective first and second optical discs.

Optical head system and its optical disc

In an optical recording and reproducing apparatus which forms at least first and second light spots on a track of an optical recording medium to record, reproduce or erase information, a movable range of the second light spot is limited to less than one half of a track pitch, normal to the track, from the track to prevent tracks other than a target track from being miserased, misrecorded or misreproduced. When a deviation of the second light spot from the target track exceeds a predetermined amount, light emission of the second light spot is stopped to prevent a track other than the target track from being miserased, misrecorded or misreproduced. When the deviation of the second light spot from the target track exceeds the predetermined amount, the second light spot is returned to a neutral position to prevent a track other than the target track from being miserased, misrecorded or misreproduced.

Optical recording and reproducing apparatus having a plurality of light

A recording method and apparatus for an optical disk employs a data format having a fixed pattern sync portion in which a minimum run length of zeros and a maximum run length of zeros are not adjacent to each other. As such, temperature difference caused during recording the optical disk may be made smaller thermal stress applied upon the medium may be reduced, the deterioration thereof may be restrained, and the repetitive frequency of the medium may be improved.

Recording method and recording apparatus for optical disk

Data read from an optical disk includes an address period, an ALPC period and a data period, in which the ALPC period contains a no-signal state at opposite ends of a laser output signal. An ALPC period detector is provided for detecting the ALPC period. During the ALPC period, an automatic gain control circuit is suspended to hold the gain to the predetermined value. Alternatively, during the ALPC period, the signal applied to the automatic gain control circuit is reduced to ground level or is attenuated. Thus, since the automatic gain control circuit will not be adversely affected by the laser output signal and no-signal state in the ALPC period, the automatic gain control circuit will amplify the signal in the data period with an appropriate gain.

AGC circuit for optical disk data reproducing apparatus using ALPC

In an optical recording and reproducing apparatus which forms at least first and second light spots on a track of an optical recording medium to record, reproduce or erase information, a movable range of the second light spot is limited to less than one half of a track pitch, normal to the track, from the track to prevent tracks other than a target gtrack from being miserased, misrecorded or misreproduced. When a deviation of the second light spot from the target track exceeds a predetermined amount, light emission of the second light spot is stopped to prevent a track other than the target track from being miserased, misrecorded, or misreproduced. When the deviation of the second light spot from the target track exceeds the predetermined amount, the second light spot is returned to a neutral position to prevent a track other than the target track from being miserased, misrecorded, or misreproduced.

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Higashiosaka, Japan

Shunji O'Hara