Kabushiki Kaisha Toshiba

Shintaro Takehara

Maho Kuwahara

Sumitaka Maruyama

Katsuo Iwata

Hideo Ando

You Yoshioka

Kazuo Watabe

Akihito Ogawa

Yutaka Kashihara

Kazuto Kuroda

A tracking error detection device for an optical disk apparatus comprises a detecting unit which includes at least two detectors and detects a reflected light from a series of pits formed on an optical disk, a phase comparing unit which detects a phase difference of outputs of the at least two detectors, and a low-pass filter which smoothes an output of the phase comparing unit, a cut-off frequency of the low-pass filter being higher than a frequency at which a spectrum of a modulation code recorded in the optical disk becomes &#x2212;10 dB and lower than a frequency at which the spectrum of the modulation code recorded in the optical disk becomes &#x2212;5 dB.

Tracking error detection device and tracking error detection method for optical disk apparatus

The present invention relates to an optical head device and an optical disk unit using the same. The optical head device includes a relay lens control unit to control at least one of lenses of a relay lens unit based on an output signal outputted from a first optical detector and a power control circuit to control an intensity of a light beam emits from a light source.

Optical disk unit capable of restraining changes in light quantity

An information reproducing apparatus has an equalizing filter which performs partial response equalization of a detection signal detected by a detecting section and which outputs an equalized signal, a variable gain amplifier which corrects the potential of the equalized signal in accordance with a correction amount determined in accordance with a plurality of reference levels that are used for maximum-likelihood decoding and a plurality of peak levels in a histogram of equalized signals corresponding to the plurality of reference levels, and a maximum-likelihood decoder which performs the maximum-likelihood decoding by referencing the reference levels, in accordance with the equalized signal that has been corrected. The apparatus controls the signal amplitude of the equalized signal to an appropriate value, thereby implementing high-reliable decoding processing.

Information reproducing apparatus and method with correction of equalized signal levels

An information storage medium according to an embodiment of this invention includes a wobble track whose wobble period is modulated by multi-frequency shift keying corresponding to playback control information, wherein the playback control information contains header data and address data, and the header data contains a VFO area formed from a predetermined frequency.

Information storage medium and information recording/playback apparatus

An information storage medium according to an embodiment of this invention includes a wobbled groove having a wobble period modulated by multi-frequency shift keying corresponding to playback control information.

Information storage medium with wobbled groove having wobble period based on multi-frequency shift keying

There is provided an information reproducing device which outputs an equalization signal P by applying equalization processing to a signal detected from a storage medium based on equalization coefficients Cto C, outputs a decoding signal d by applying maximum likelihood decoding processing based on reference levels Rto R, generates an ideal waveform signal I based on the equalization signal, and has a target waveform generator which generates a target waveform signal T by changing at least one level of the ideal waveform signal I, wherein erroneous decoding is reduced by optimizing reproduction processing parameters such as the equalization coefficients Cto Cor the reference levels Rto Rbased on the target waveform signal T and the information on the storage medium is stably reproduced.

Information reproducing device and information reproducing method

Optical disk unit for recording or reproducing information

The present invention relates to an optical head unit and an optical disk unit using the optical head unit. The head unit includes a wavefront transforming optical element control unit to controls a wavefront transforming optical element so as not to transform wavefront of a light beam focused on a recording layer by a focusing unit due to the thickness error of a light transmission layer positioned between the recording layer and the focusing unit based on an electrical signal outputted from a first light detector, and an output control unit that controls light amount of a light beam radiated by a light emitting unit based on the magnitude of the electrical signal outputted from the light detector.

Optical head device and optical disk unit capable of stable signal reproduction

There are comprised a laser light source for outputting a light beam, an optical disk having a recording/reproducing surface and a transparent substrate on the surface, an objective lens for gathering the light beam on the optical disk, a relay lens system comprising one or more lenses inserted between the laser light source and the objective lens, means for moving one or more lenses in the relay lens system toward its optical axis so as to correct sphere aberration in accordance with a thickness of the transparent substrate of the optical disk, and means for sustaining a diameter of an incident light on the objective lens when one or more lenses among the relay lenses move.

Optical head and optical disk apparatus

An optical disk device has reproduction signal detecting section, each of which detects a reproduction signal corresponding to a reflective wave of an optical disk, a first offset controller, which offsets the reproduction signal with a first offset value F1, an A/D converting circuit, which A/D converts the offset reproduction signal, and a second offset controller, which offsets the converted digital reproduction signal with a second offset value F2, and a decoder, which viterbi decodes the offset digital reproduction signal and outputs decoded data B. Because an offset is performed with each exclusive value to A/D conversion and viterbi decoding, it is possible to obtain high identification accuracy with nonlinear characteristic eliminated.

Optical disk device and information reproducing device performing maximum decoded offset process, and reproducing methods thereof

An optical disk includes land and groove tracks which are alternately arranged, a land portion which is substantially flush with the land track and separates the groove track, a set of embossed pits which is formed in a boundary between the land portion and one of the land tracks located on two sides of the groove track in which the land portion is formed, and a record/reproduction interruption portion which is formed in a record area formed on the land track located on a side on which the embossed pits are not formed and adjacent to the land portion and on/from which no data is recorded/reproduced. Data are recorded/reproduced in units of ECC blocks each having a plurality of sectors.

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Yokohama, Japan

Shintaro Takehara