Abstract: The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce.

Abstract: An optical disc apparatus includes a laser diode for emitting a laser light, a beam splitter for dividing the laser light into a main beam and sub beam, a main photodetector for detecting the main beam to output a main push-pull signal, a sub photodetector for detecting the sub beam to output a sub push-pull signal, and a subtracter for calculating the main and sub push-pull signals to output a differential push-pull signal, in which an amplification degree of the sub push-pull signal is adjusted so that a DC offset on the differential push-pull signal is adjusted, even in the case where a laser intensity is varied.

Abstract: An optical disk recording method includes the steps of: providing a multi-pulse chain from a recording wave; independently changing the pulse rise timing and pulse fall timing (pulse width) of the first pulse in the multi-pulse chain in accordance with a preceding space length and a recording mark length; changing the pulse rise timing and pulse fall timing (pulse width) in accordance with a following space length and the recording mark length in a predetermined timing or in independence; and in relation to the smallest mark recorded by irradiation with mono pulse, changing the rise timing in accordance with the preceding space length and the recording mark length and the fall timing (pulse width) in accordance with the following space length and recording mark length, compensating various optical disks different in recording material without change of the fundamental waveform.

Abstract: The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce.

Abstract: An optical disk recording method includes the steps of: providing a multi-pulse chain from a recording wave; independently changing the pulse rise timing and pulse fall timing (pulse width) of the first pulse in the multi-pulse chain in accordance with a preceding space length and a recording mark length; changing the pulse rise timing and pulse fall timing (pulse width) in accordance with a following space length and the recording mark length in a predetermined timing or in independence; and in relation to the smallest mark recorded by irradiation with mono pulse, changing the rise timing in accordance with the preceding space length and the recording mark length and the fall timing (pulse width) in accordance with the following space length and recording mark length, compensating various optical disks different in recording material without change of the fundamental waveform.

Abstract: The present invention provides a read channel and a drive capable of suppressing deterioration in performance of a PLL and a Viterbi decoder by using a DC component eliminating means capable of higher-speed operation than hitherto. The location of an edge is determined by using differential of a read signal, and a DC component is detected from the midpoint level of the edge. Detection of a pseudo-edge due to a long mark or space signal is prevented by limiting the absolute value of a maximum or minimum of a differential coefficient when the location of the edge is determined from the differential coefficient of the read signal. Internal operation of a DC component detector is controlled according to the state of the PLL and the magnitude of the DC component.

Abstract: The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce.

Abstract: The present invention provides a read channel and a drive capable of suppressing deterioration in performance of a PLL and a Viterbi decoder by using a DC component eliminating means capable of higher-speed operation than hitherto. The location of an edge is determined by using differential of a read signal, and a DC component is detected from the midpoint level of the edge. Detection of a pseudo-edge due to a long mark or space signal is prevented by limiting the absolute value of a maximum or minimum of a differential coefficient when the location of the edge is determined from the differential coefficient of the read signal. Internal operation of a DC component detector is controlled according to the state of the PLL and the magnitude of the DC component.

Abstract: The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce.

Abstract: An object of the present invention is to improve a conventional DPD method having a problem that a tracking servo becomes unstable due to a reduction in the accuracy of detecting a phase difference between short mark signals at an edge, in a case where the amplitudes of the short mark signals are very small, or where a readout signal contains large noise. To this end, the present invention provides a method for increasing the contribution ratio of long mark signals to generate a tracking error signal by causing a phase difference pulse to include information on a phase difference, and by causing the area of the pulse to be weighted according to the length of a mark/space adjacent to a concerned edge.

Abstract: The present invention is to detect an envelope defect of a read signal due to a fingerprint on a surface of a disc, an inter-layer interference of a dual disc, or the like which is a factor of a read error of an optical disc, and is to improve a read capability of an optical disc drive while avoiding a read error by performing an appropriate processing. Means for detecting an envelope defect and means for counting the number of appearances of the envelope defect are included in the present invention. A read condition for factors of a read error is set at the time of a read retry, and a read condition suitable for the decoding of a readout signal containing an envelope defect is set at the time of detection of the envelope defect in the present invention.

Abstract: The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce.

Abstract: Since the conventional optical disk recording/reproducing apparatus cannot correctly measure a power of a main beam that is a part of the laser light outputted from an objective lens and is focused on a recording layer to contribute to recording/reproducing, it is difficult to accurately control a read power. A ratio of a proper read power to a threshold power of erasing is acquired beforehand. The read power is determined by measuring the threshold power of erasing and multiplying it by the ratio when learning of the read power is performed for each drive device. According to the read power learning method of this invention, it becomes possible to determine the proper read power regardless of performance variance of an optical pickup and sensitivity dispersion of a medium.

Abstract: An optical disk apparatus for correcting astigmatism that influences the read/ write. If there is astigmatism, and auto-focus and tracking control are in operation, then a push-pull signal amplitude and a 2T signal amplitude vary with the variation of an amount of spherical aberration, resulting in two cases. In one case, the amount of spherical aberration to give the maximum value of push-pull signal amplitude agrees with the amount of spherical aberration to give the maximum value of 2T signal amplitude, and in the other case the two amounts do not agree. If there is no astigmatism, two amounts agree each other. If there in no agreement, then correction is made by using an astigmatism correcting element until the agreement is reached between the two. In the case where two amounts agree, specification is made for the existence and angle of astigmatism, and correction is made by using focus error signals from adjacent tracks.

Abstract: In an optical recording medium having two information recording layers, a highly reliable recording can be conducted in one of the recording layers in the back regardless of the recording state of the other recording layer closer to the side of the disc on which light is incident. A first photodetector 115 detects reflected light from a recording layer 103 in the back when the light is focused thereon. A second photodetector 116 is disposed outside the periphery of the first photodetector 115 and detects reflected light from a recording layer 105 located in front. When recording in the recording layer in the back, the write power is controlled in accordance with the output level of the second photodetector.

Abstract: A frequency characteristics compensation method that can be applied to various waveforms (strategies). When determining the amount of frequency compensation, a deteriorated part by frequency characteristics is compensated for with respect to the difference between the pulse power to be compensated and the power level immediately before it. The present invention can also be applied to variations in the performance, aged deterioration, and temperature characteristics.

Abstract: The focus offset FE0 corresponding to minimum jitter is learned in advance. When performing spherical aberration adjustment for each disk, the spherical aberration is adjusted so that the jitter reaches a minimum, while maintaining the focus offset at FE0. The invention provides a method for performing high-precision adjustment of the focus offset and spherical aberration, even in the case of a disk which does not have data recorded on it.

Abstract: This optical pickup has a nonvolatile memory from which data can be electronically read out, and stores as data the difference between the spherical aberration when the readout signal jitter reaches a minimum, and the spherical aberration when the tracking error signal amplitude reaches a maximum. The positioning of an optical detector or detection lens is adjusted so that the focus error signal is almost zero when the readout signal jitter reaches a minimum. The invention provides a method for performing high-precision adjustment of the focus offset and spherical aberration, even in the case of a disk which does not have data recorded on it.

Abstract: The amount of focus offset and the amount of spherical aberration correction are adjusted with respect to a disk on which no data is recorded with high precision. The amount of focus offset and the amount of spherical aberration correction are adjusted on the basis of (1) a focus error signal amplitude, (2) a tracking error signal amplitude in a wide track pitch region, and (3) a rectangular waveform wobble signal envelop level.

Abstract: The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce.