Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Shinichi Konishi

Takeshi Nakajima

Harumitsu Miyashita

Toshihiko Takahashi

Yuji Hisakado

Atsushi Nakamura

Youichi Ogura

Toshiya Akagi

Mitsuaki Oshima

Takashi Ishida

Mamoru Shoji

Yoshiho Gotoh

Kenji Koishi

Junichi Minamino

Mitsurou Moriya

Yoshinari Takemura

Shin-ichi Tanaka

Norio Miyatake

Motoyoshi Murakami

Hironori Deguchi

Yukihiro Yamasaki

Haruo Yamashita

Shunji Ohara

Takashi Yumiba

Yuuichi Kuze

Masatoshi Yajima

Yoshito Aoki

Fumiaki Ueno

Yoshiyuki Miyabata

Akihiko Nishioka

Teruhiko Izumi

Tsumoru Fukushima

Yoshiteru Namoto

Dai Ichiryu

Shinichiro Takigawa

Hiroaki Hayashi

Ariaki Ito

Yumiba: Takashi

Motoyuki Fujino

Takamasa Sakai

Yasuhiro Honda

Shin-Ichi Tanaka

An optical disc device includes: an optical pickup including a first laser light source that emits laser light, an objective lens that focuses the laser light emitted from the first laser light source onto an optical disc, and a light receiving element that receives reflected light from the optical disc, and performs photoelectric conversion on the reflected light received to output a received-light signal; an FS signal generator that generates an FS signal indicating the light amount of the reflected light from the optical disc, based on the received-light signal from the light receiving element; and a dirt determiner that determines that dirt is present in the optical pickup, when the peak level of the FS signal is less than a dirt determination threshold, and controls the light receiving element to increase the peak level of the received-light signal from the light receiving element.

Optical disc device and recording and reproduction device

An optical disc drive device includes a spindle motor that rotates an optical disc, an OPU, a first controller that causes the spindle motor and the OPU to read recorded data from the rotating optical disc, and an transmitter that transmits the read recorded data to a signal processing device disposed external to the optical disc drive device. The recorded data transmitted by transmitter is stored in a buffer provided in the signal processing device. The first controller decreases the rotational speed of the optical disc based on free space information indicating the free space of the buffer.

Optical disc drive device and playback device

After a playback RF signaldetected from an optical disc mediumis waveform-shaped, it is converted into a digital RF signalwith a sampling clockhaving a cycle twice as long as a channel clock. Thereafter, a first offset correction circuitcorrects an offset fluctuation in a high frequency band, and a digital adaptive equalizerperforms adaptive equalization, and then a second offset correction circuitcorrects an offset component that remains after the offset correction by the first offset correction circuit, thereby demodulating a digital binary signal. Therefore, even when high-speed playback is carried out and an asymmetry depending on the recording quality is large, a reduction in power consumption can be realized while maintaining high-performance playback. Consequently, it is possible to provide an optical disc playback apparatus which can realize sufficient playback performance at low power consumption.

Optical disc playback apparatus

An optical disc recording/playback apparatus is provided with a first AD converterfor shaping a push-pull signaldetected from an optical disc mediumby a light difference signal shaping circuit, and converting the signal into a digital sampling signalusing a sampling clocksynchronized with a channel frequency; a series of means for detecting wobble amplitude informationduring recording from the digital sampling signal; a series of means for detecting address polarity informationand address position information during playback; and a recording laser power control circuitfor controlling a recording laser power to a power suited for recording on the basis of the wobble amplitude information.

Optical disc recording/playback apparatus

An optical disk device is provided with a first analog-to-digital converter for converting a push-pull signal detected from an optical disc medium into a digital sampling signal according to a sampling clock in the vicinity of a channel frequency. The optical disk device also includes an address polarity information detection circuit for detecting address polarity information from the digital sampling signal, and an address position information detection circuit for detecting address position information from the digital sampling signal while maintaining continuity.

Optical disk device

In a jitter detection apparatus, a playback RF signaldetected from an optical disc mediumis subjected to waveform shaping, and thereafter, converted into a digital RF signalwith a sampling clock having a cycle twice as long as a cycle of a channel clock. Thereafter, an offset variation in a high-frequency band is corrected by an offset correction circuit, and data that are missing in the time direction are restored by a Nyquist interpolation filter. Then, positions where jitter is to be extracted are selected from an output signal of the Nyquist interpolation filter, by a jitter detection preprocessing circuit, according to the playback speed of the optical disc mediumand the arithmetic capacity of a digital signal operation circuit, whereby highly accurate jitters can be extracted by using the digital signal operation circuit

Jitter detection apparatus

An optical disk that includes main information and write-once information recorded on the optical disk. The write-once information is recorded as information unique to the optical disk, and the write-once information stores at least watermark production parameters for producing a watermark.

Magneto-optical recording medium having watermark for preventing unauthorized copy

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

A tilt control apparatus includes an orthogonal shift detector () which detects an orthogonal shift by comparing a pair of a plurality of tap coefficients (C, . . . , C) of a FIR filter and generates an orthogonal shift signal, and an actuator varies the inclination of the optical axis of the light beam to correct the orthogonal shift, and a tilt controller () controls the drive of the actuator in accordance with the orhogonal shift signal to minimize the orthogonal shift. In the information recording operation, the orthogonal shift obtained based on a recording track is previously stored in a temporary storage portion and the stored orthogonal shift is used to conduct the tilt control.

Optical disk apparatus using tilt and aberration correction control system

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

A recording/producing device for writing data on a recording medium, or reading data from the recording medium, wherein data matching a recording pattern so specified as to include a plurality of mutually different sets of mark lengths and space lengths is written on the recording medium, and the data is then read to generate data signals. An edge shift detector uses data signals to measure the edge shift amount of a mark formed on a recording medium for each set of a mark length and a space length. A record controller sets a recording parameter for each set of a mark length and a space length based on the measured edge shift amount.

Recording/reproducing device

Hold registers receive a hold register enable signal. When reading one kind signal of header field data, the hold register enable signal is High and the registers store newly renewed values of filter coefficients, and when reading a different kind signal of recording field data, the hold register enable signal is Low and the hold registers hold the last stored header field contents of the registers. Then, when a header field of a next sector is detected, the contents held in the hold registers are taken and preset to the registers. Thus, even in a case where an intermittent reproduction signal having different kinds of formats is processed in playback, the continuous adaptive equalization can be realized over the different kinds of reproduction signals in quality.

Adaptive equalizer for use in information reproducing apparatus

A PRML detector includes a waveform equalizer for equalizing a waveform of a reproduction signal obtained by reproducing marks and non-marks recorded on a recording medium, and a decoder for generating binary-coded data of the reproduction signal based on the waveform equalized by the waveform equalizer. The decoder outputs a temporary data string which is obtained before the binary-coded data is obtained. The waveform equalizer includes an equalizer that includes a delay element that delays propagation of the reproduction signal, a plurality of multipliers that multiply predetermined coefficients by the reproduction signal and the delayed signal from the delay element, and an adder that adds outputs from the plurality of multipliers. A target value judger determines a target value for equalizing based on the temporary data string output from the decoder and a coefficient adaptive controller calculates the predetermined coefficients and adaptively updates the calculated predetermined coefficients for each of a plurality of multipliers.

PRML detector having a viterbi decoder outputting temporary judgement results

A waveform equalizer for equalizing a waveform of a reproduction signal. A delay element delays a propagation of the reproduction signal. A plurality of multipliers multiply predetermined coefficients by the reproduction signal and the delayed propagation reproduction signal. A detector detects an asymmetry of the reproduction signal arising from physical profiles of each of the marks and the non-marks, and outputs a detection signal representing an amount of asymmetry. A discriminator outputs a discrimination signal in response to a discrimination of the marks and the non-marks. A calculator calculates a first coefficient multiplied by the reproduction signal of the marks based on the outputted detection signal, and calculates a second coefficient multiplied by the reproduction signal of the non-marks. A selector selects either the first or second coefficient, based upon the outputted discriminating signal.

Waveform equalizer for a reproduction signal obtained by reproducing marks and non-marks recorded on a recording medium

An asymmetry detection apparatus includes: a clock signal generator for generating a clock signal based on a reproduced signal; an A/D converter for sampling the reproduced signal in synchronization with the clock signal; a determiner for determining whether a level of each of a plurality of sampled data obtained by the sampling operation is equal to or greater than a predetermined level; and a detector for detecting asymmetry in the reproduced signal by using predetermined ones of the sampled data based on an output from the determiner. A jitter detection apparatus includes: a clock signal generator for generating a clock signal based on a reproduced signal; an A/D converter for sampling the reproduced signal in synchronization with the clock signal; a determiner for determining whether a level of each of a plurality of sampled data obtained by the sampling operation is equal to or greater than a predetermined level; and a detector for detecting jitter in the reproduced signal by using predetermined ones of the plurality of sampled data based on an output from the determiner.

Asymmetry detection apparatus, jitter detection apparatus, and recording/reproduction apparatus

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Nara, Japan

Shinichi Konishi