Matsushita Electric Industrial Co., Ltd.

Yuji Hisakado

Takashi Ishida

Mamoru Shoji

Isao Satoh

Shigeru Furumiya

Yuji Takagi

Toshiya Akagi

Yukihiro Yamasaki

Shinichi Konishi

Shunji Ohara

Chikashi Inokuchi

Yoshito Aoki

Yoshiyuki Miyabata

Atsushi Nakamura

Motoshi Ito

Toshihiko Takahashi

Takeshi Nakajima

Harumitsu Miyashita

Takahiro Nagai

Hironori Deguchi

Atsushi Miyazaki

Yoshihisa Fukushima

Yasushi Azumatani

Hiroshi Hamasaka

Naoyasu Miyagawa

Yuichi Kamioka

Ariaki Ito

Yasuhiro Honda

Jun'ichi Minamino

A power control device for controlling a power of a light source of an optical beam directed to an optical medium. The power control device includes a reflected light detector for detecting reflected light from the optical medium when irradiated by an optical beam which is following a track; an arithmetic unit for calculating from the reflected light a transmissivity of light transmitted from a disk surface to a recording layer or an amount of directed light on the recording layer of the medium; and power control means for controlling the power of the light source for emission based on a calculation result produced by the arithmetic unit.

Laser power controller and optical disk device

An optical disk drive and recording power determination method determine the optimum power with consideration for the recording state of a base layer track when determining the optimum power by test recording before recording user data. After recording at a second recording power that is higher than a first recording power by a specific amount, recording is performed at a third recording power that is lower than the first recording power by a specific amount, and the first recording power is set to the recording power for data recording when a specified playback signal quality is achieved.

Optical disk device and recording power determining method

In a recording medium which is circular and has first and second recording layers, the first and second recording layers each include one or more first tracks extending concentrically or spirally and one or more second tracks extending concentrically or spirally, each of the one or more first tracks and the one or more second tracks includes a plurality of first sectors and a plurality of second sectors, each of the plurality of first sectors includes first and second regions, each of the plurality of second sectors includes third and fourth regions, first and second grooves are formed in each of the second and fourth regions, the first and second grooves extending concentrically or spirally and oscillating sinusoidally, oscillation of the first groove has a first oscillation characteristic at a first prescribed position in the second region, oscillation of the second groove has a second oscillation characteristic at a second prescribed position in the fourth region, and the first and second oscillation characteristics are different from each other.

Recording medium, method and apparatus for recording, and method and apparatus for reproducing

An optical disc drive usable with discs to which data is continuously recorded and discs having a sector format can quickly resume playback signal output after passing imperfection causing potential reading errors, and plays disc with few read errors. A detection signal generator detects DC level fluctuation in the playback signal read from the disc and generates a detection signal tracking the DC level fluctuation. A selector selects a detection signal or a null signal without valid polarity based on the detection signal generated by the detection signal generator and input to the selector. A clamping unit performs a clamping process to suppress DC level fluctuation in the playback signal based on the detection signal when the selection unit selects the detection signal, and does not perform the clamping process when the selection unit selects the null signal. A signal processor performs specific signal processes based on clamping unit output.

Optical disc device

Recording medium, method and apparatus for reproducing, and method and apparatus for recording

An optical disk is operated in a ZCLV system for generating a stable and precise clock and the operation proceeds with a speed change of a high-speed motor when data is stored with the motor accelerated or decelerated at a high speed to improve accessibility for data storage. The optical disk includes: a disk rotator for rotating the optical disk at an optional number of rotations; a rotation controller for controlling rotation of the optical disk; a wobble extractor for extracting wobbling on the track of the optical disk; a clock extractor for extracting a clock element from the wobbling; a speed detector for detecting a linear speed of the optical disk; and a response switch for switching a response of the clock extractor, in which the response of the clock extractor is switched depending on the linear speed of the optical disk.

Optical disk device

A regenerated signal process circuit of an optical disk device is developed to solve the problem that a jitter margin is lowered without an optimum regeneration condition because, when data is regenerated independent of a transfer rate, a data frequency fluctuates against a set value of an AGC, a waveform equalization circuit, a binarization circuit, or the like. In a signal process circuit, a set value of the AGC (,), the waveform equalization circuit (,), the binarization circuit (,), or the like is controlled by referring to the amount of oscillation control current of the VCO (,) of a frequency synthesizer. The characteristics of the VCO of the data PLL (,) is set equal to the characteristics of the VCO (,) of the frequency synthesizer, and each set value is controlled by referring to the oscillation control current of each VCO. Then, the reference current is switched depending on the synchronization state of the data PLL (,). In addition, the gain of the charge pump (,) is adjusted based on the division ratio of the N divider (,) such that the frequency synthesizer has loop characteristics of constant and stable oscillation.

A method and a device of processing a signal to solve the problem that a multi-bit and high-speed A/D converter for converting an analog regenerated signal into a digital signal on an optical disk is costly. In the method of processing a signal using a sum signal (,) or a difference signal (,) of a plurality of electric signals detected by an optical detection unit (,), an ID signal and a recording signal contained in the sum signal or the difference signal are selected and time-multiplexed, the polarity of the ID signal is adjusted to the polarity of the recording signal, the DC levels of the polarity-adjusted ID signal and recording signal are controlled and maintained at a constant level, and a series of the polarity- and DC-level-adjusted signals are A/D converted. Thus, the dynamic range of the multiplexed signal is reduced, and both the sum and the difference signals are digitized by a single A/D converter having the minimum number of bits.

Optical disk signal processing method and optical disk device

An optical disk device of the present invention performs at least one of recording and reproduction of an optical disk in which a wobble signal is included along a data-recording track, by rotating the optical disk and by scanning the track on the optical disk using an optical head. The device includes: an extraction section for extracting the wobble signal of the optical disk from an output of the optical head; a synchronization clock generation section for generating a synchronization clock signal based on the wobble signal extracted by the extraction section; and a recording/reproduction section for performing at least one of recording and reproduction of data to/from the optical disk by the synchronization clock signal generated by the synchronization clock generation section.

Optical disk device with abnormal jump detection

There is provided an optical information recording/reproducing device for recording, reproducing, or erasing information on an optical information recording medium including information tracks formed on a disk substrate including alternating groove tracks and land tracks each including: a header region for recording identification data representing location information in pre-pits; and a data region for recording user data, the pre-pits being grouped into blocks, the blocks wobbling alternately toward an inner periphery or an outer periphery of the disk substrate along a radius direction from a center line of each information track by a distance which is substantially 1/2 of the information track pitch. The pre-pits are provided along the radius direction at a pitch twice as large as the track pitch. The device includes: an optical system for radiating a light beam as a converged beam spot on an information track; an optical detector including two light receiving portions divided in parallel to the track direction for receiving the light beam reflected from the recording medium; a signal generator for generating a differential signal and an addition signal of output signals respectively output from the light receiving portions; a header region detection circuit for determining whether the converged beam spot is tracing the header region or the data region using the differential signal; and at least one reading circuit for reading the identification data from the differential signal and for reading information recorded in the data region from the addition signal.

Optical information recording/reproducing device and method for

A two-layer optical disk has a first layer of a disk shaped recording medium for storing data and a second layer of a disk shaped recording medium placed over the first layer for storing data. Data blocks A, B, C are stored in the first layer in said order. Similarly, data blocks X, Y, Z are stored in the second layer in said order. When reading the data from the two-layer optical disk, the data blocks are read in the order of A, X, B, Y, C, Z.

Two-layer optical disk

An optical disk according to the present invention includes a first track having a spiral shape and a second track having a spiral shape, the first track and the second track adjoining each other, and information being recorded on or reproduced from the first track and the second track. The optical disk further includes an address region including: a first address block formed so as to be on both the first track and the second track adjoining the first track on an inner periphery side; and a second address block formed so as to be on both the first track and the second track adjoining the first track on an outer periphery side.

Growing community of inventors

Osaka, Japan

Yuji Hisakado