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: In a multilayer optical recording medium having at least three recording layers, an influence of interlayer crosstalk due to an unnecessary light is removed. Each of the recording layers includes an information recording area, and the recording layers other than the nearest recording layer and the farthest recording layer when viewed from a light incident side include a first annular area having uneven patterns formed thereon, and a second annular area having uneven patterns formed thereon, the first annular area being adjacent to an inner side of the information recording area, the second annular area being adjacent to an outer side of the information recording area.

Abstract: An object of the present invention is to achieve both low noise and fast response in an optical signal detecting circuit capable of providing all of three signals—a focus error signal, a tracking error signal, and an RF signal—with only a single detection system. A single current-to-voltage converter converts a current signal obtained by adding currents flowing through two photodiodes, into a voltage signal. Not only currents flowing into the photodiodes, but also currents flowing out from the photodiodes are taken out as the voltage signals. Moreover, by applying two different reference voltages to the current-to-voltage converters, a reverse bias voltage is applied between the terminals of each photodiode.

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: 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: Disclosed herewith is a data recording and reading equipment capable of reducing laser noise easily. At first, a laser beam source that can reduce the laser noise when reading data from a subject optical disk is obtained. A modulator capable of varying laser attenuation with a voltage is disposed so as to precede the laser, thereby the laser noise when reading data from the optical disk can be reduced without lowering the laser power when in writing.

Abstract: To make the adjustment of a write-pulse parameter on the basis of a phase error between a readout signal and a clock signal applicable also to high-density optical discs. The channel bit length during trial writing is made larger than that during user-data recording. Then, a write-pulse parameter adjusted by the trial writing is applied as it is or with a predetermined correction to user-data recording.

Abstract: A rewritable optical disk apparatus, optical information recording and reproducing apparatus or the like is allowed to automatically and properly adjust the optical system to the optimum focal condition regardless of the readout signal detector's positional error and the residual aberration in the optical system. The spherical aberration and defocus are coarsely adjusted using the amplitude (PP amplitude) of the tracking error signal and then finely adjusted using the amplitude (RF amplitude) of the readout signal. Since the spherical aberration can properly be adjusted, it is possible to raise the reliability of the readout signal.

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: Reproduction on an optical recording medium having plural information layers involves the problem of distortion occurring due to interlayer crosstalk and hence deterioration in the quality of a readout signal. At a predetermined radius, a correction coefficient for correcting the amount of fluctuation components is calculated from a readout signal with distortion due to the interlayer crosstalk, and then is stored. The stored correction coefficient is used to eliminate crosstalk components and to correct readout signal fluctuation during reproduction on a predetermined area. In this way, the original readout signal without interlayer crosstalk components can be obtained, so that good-quality reproduction characteristics can be achieved.

Abstract: Disclosed herewith is a data recording and reading equipment capable of reducing laser noise easily. At first, a laser beam source that can reduce the laser noise when reading data from a subject optical disk is obtained. A modulator capable of varying laser attenuation with a voltage is disposed so as to precede the laser, thereby the laser noise when reading data from the optical disk can be reduced without lowering the laser power when in writing.

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: Regarding a signal recorded with a first frequency in a recording area on a specific first recording layer and a signal recorded with a second frequency different from the first frequency in a recording area on a second recording layer which might cause interlayer crosstalk in relation to the first recording layer, a reproducing signal measurement method for a multilayer optical recording medium having at least three recording layers includes reproducing the signal recorded in the recording area on the first recording layer, separating signals recorded respectively with the first and second frequencies, discriminating signal amplitude of the first frequency and a maximum value in signal amplitude of the second frequency, and calculating a signal amplitude ratio between them to measure interlayer crosstalk contained in the signal reproduced from the recording area on the first recording layer. Thus, the interlayer crosstalk quantity caused by unnecessary light can be measured quantitatively.

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: 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: A rewritable optical disk apparatus, optical information recording and reproducing apparatus or the like is allowed to automatically and properly adjust the optical system to the optimum focal condition regardless of the readout signal detector's positional error and the residual aberration in the optical system. The spherical aberration and defocus are coarsely adjusted using the amplitude (PP amplitude) of the tracking error signal and then finely adjusted using the amplitude (RF amplitude) of the readout signal. Since the spherical aberration can properly be adjusted, it is possible to raise the reliability of the readout signal.

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: 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.