Abstract: An optical disc apparatus reads the address information from an optical disc which has tracks and track spaces formed between tracks. The apparatus has an optical head which irradiates the disc with light and includes tracking detectors, divided into a first detector and a second detector in a track direction, detecting the light reflected from the disc and outputting detection signals, an adjusting circuit which adjusts amplitudes of the first and second detection signals and outputs the signals at a position where the address information is recorded, a differential amplifying circuit which outputs the differential signal which is the difference between the adjusted first and second detection signals, and an address detecting circuit which detects the address information based on the differential signal. As a result, the optical disc apparatus accurately detects whether information is being recorded on a correct track and improves the reliability during recording.

Abstract: Playback signal amplitude drops and continuity of the signal track amplitude is lost at the beginning the data recording area when data is incrementally written to optical discs such as DVD-R or DVD-RW media. Feed-forward control quickly settles semiconductor laser recording power to the target power level immediately after an incremental recording starts. While recording continues, feedback control maintains laser power at a desired recording power level even when the required current supply varies due to the temperature characteristics of the semiconductor laser when recording lasts for an extended period of time. A semiconductor laser control method and semiconductor laser control device thereby maintain laser power at a stable target recording power level quickly and for as long as recording continues.

Abstract: Multi-pulse trains of a forward laser beam are applied to an optical disc to record mark areas thereon. The multi-pulse trains correspond to the mark areas respectively. The multi-pulse trains represent information to be recorded. Detection is made as to an intensity of a reflected laser beam which results from reflection of the forward laser beam by the optical disc. The detected intensity is divided by a setting intensity to get a division result. A condition of recording of each of the mark areas is detected in response to the division result. An amplitude of each of the multi-pulse trains is controlled in response to the detected condition.

Abstract: A semiconductor laser control circuit of the invention can modulate a light power level among a plurality of set levels including a first level, a second level lower than the first level, and a third level lower than the first level but higher than the second level.

Abstract: An apparatus operates for recording and reproducing information on and from a recording medium formed with a track and pre-pits. The track has a wobble. The pre-pits are in a predetermined phase relation with the wobble of the track. The apparatus includes a pickup for reproducing a signal from the recording medium. A limiter operates for limiting an amplitude of the signal reproduced by the pickup in response to a limiting level, and thereby processing the signal reproduced by the pickup into a limiting-resultant signal. A filter operates for suppressing components of the limiting-resultant signal, and thereby processing the limiting-resultant signal into a filtering-resultant signal. The components have specified frequencies, and are caused by the pre-pits. The limiting level for the limiter is generated in response to the filtering-resultant signal. A signal caused by the wobble of the groove is extracted from the filtering-resultant signal.

Abstract: Playback signal amplitude drops and continuity of the signal track amplitude is lost at the beginning the data recording area when data is incrementally written to optical discs such as DVD-R or DVD-RW media. Feed-forward control quickly settles semiconductor laser recording power to the target power level immediately after an incremental recording starts. While recording continues, feedback control maintains laser power at a desired recording power level even when the required current supply varies due to the temperature characteristics of the semiconductor laser when recording lasts for an extended period of time. A semiconductor laser control method and semiconductor laser control device thereby maintain laser power at a stable target recording power level quickly and for as long as recording continues.

Abstract: To accurately detect whether the information is being recorded on a correct track and improve the reliability during recording. The invention relates to an optical disc apparatus for reading the address information from an optical disc which has tracks and track spaces formed between tracks. The apparatus comprises an optical head which irradiates the disc with light and includes tracking detectors, divided into a first detector and a second detector in a track direction, detecting the reflecting light from the disc and outputting detection signals, an adjusting circuit which adjusts amplitudes of the first and second detection signals and outputting the signals at a position where the address information is recorded, a differential amplifying circuit which outputs the differential signal which is the difference between the first and the second detection signals adjusted, and an address detecting circuit which detects the address information based on the differential signal.

Abstract: An apparatus operates for recording and reproducing information on and from a recording medium formed with a track and pre-pits. The track has a wobble. The pre-pits are in a predetermined phase relation with the wobble of the track. The apparatus includes a pickup for reproducing a signal from the recording medium. A limiter operates for limiting an amplitude of the signal reproduced by the pickup in response to a limiting level, and thereby processing the signal reproduced by the pickup into a limiting-resultant signal. A filter operates for suppressing components of the limiting-resultant signal, and thereby processing the limiting-resultant signal into a filtering-resultant signal. The components have specified frequencies, and are caused by the pre-pits. The limiting level for the limiter is generated in response to the filtering-resultant signal. A signal caused by the wobble of the groove is extracted from the filtering-resultant signal.

Abstract: Multi-pulse trains of a forward laser beam are applied to an optical disc to record mark areas thereon. The multi-pulse trains correspond to the mark areas respectively. The multi-pulse trains represent information to be recorded. Detection is made as to an intensity of a reflected laser beam which results from reflection of the forward laser beam by the optical disc. The detected intensity is divided by a setting intensity to get a division result. A condition of recording of each of the mark areas is detected in response to the division result. An amplitude of each of the multi-pulse trains is controlled in response to the detected condition.