Nec Corporation

Kabushiki Kaisha Toshiba

Toshiaki Iwanaga

Masaki Nakano

Yutaka Kashihara

Masatsugu Ogawa

Akihito Ogawa

Chosaku Noda

Yuji Nagai

Yutaka Yamanaka

Shuichi Ohkubo

Hiromi Honma

Kinji Kayanuma

Shuichi Ookubo

Naoki Morishita

Shigeru Shimonou

Mitsuya Okada

Masashi Kubota

Tatsunori Ide

Hideaki Ohsawa

Satoshi Sugaya

Masaaki Matsumaru

Hideki Tanabe

Hiroharu Sato

Yoshinori Sasaki

Takeharu Shibatoko

Tutomu Ichimura

Yuuji Nagai

Yutaka Toshiba Corporation Kashihara

Masaaki Toshiba Corporation Matsumaru

Akihito Toshiba Corporation Ogawa

Chosaku Toshiba Corporation Noda

Reproduced signals are equalized by the least square technique by using a predetermined number of data samples binarized by a Viterbi decoder. Even when data written on an optical disk is unknown, the data can be equalized in a stable manner and can be reproduced at a low error rate without instability factors such as divergence due to interference.

Reproduced signal equalizing method for optical information media and optical information reproducing/recording apparatus

Optical information recording and reproducing mediumhas two recording layers of first and second recording layersand, from a laser beam incident surface side. In each control area, recording layer management information containing at least information indicating recording states of a plurality of areas into which the inside of data recording areaof each recording layer is divided is recorded. When recording or reproducing is performed on the second recording layer, the recording layer management information is checked, and a laser beam output is changed based on a recording state of an area corresponding to the first recording layer

Optical information recording and reproducing medium

In an optical disk system using a PRML identification system, a method for deriving an optimum recording wave in a short period of time is provided. Parameters of the recording wave are adjusted by using an evaluation value obtained by a signal evaluation method which is suitable for the PRML identification system as an index. In this case, as a parameter adjusting method, a plurality of adjusting methods are utilized.

Optical disk recording/reproducing method, optical disk recording/reproducing apparatus and optical disk

Reproduction signals include patterns for which recognition errors are likely. With respect to such patterns, probable error patterns are prepared. Tables showing correct patterns and error patterns are prepared, and evaluation values accurately representing signal quality are calculated. In an apparatus using a PRML method, discrimination data and a plurality of predetermined bit sequence pairs are examined to detect matching. A bit sequence and corresponding two ideal responses are calculated. Euclidean distances between the two ideal responses and equalization signals are obtained, and the difference between the Euclidean distances is further obtained. A quality evaluation value of a reproduction signal is calculated based on a mean value, a standard deviation, an appearance probability of the predetermined bit sequence, and a Hamming distance between the predetermined bit sequence pairs.

Signal evaluation method, information recording/reproducing apparatus, information reproducing apparatus, and information recording medium

An optical disc including one or more than one recording layers has land areas () and groove areas () as recording tracks, wherein a data recording area of at least one of the recording layers is divided into a plurality of zones in a radial direction. In each of the divided zones, one or more than one prepits () with predetermined data are disposed in a track so that each header area is disposed at ever other boundary among the boundaries between the land areas and the groove areas. Each header area is shifted in the circumferential direction from other header areas apart from the each header area by two boundaries without overlapping in the radial direction.

Optical disc and recording/producing method therefor

In order to stably carry out reproduction of information in an optical disc medium () using a PRML (partial-response maximum-likelihood) method for reproducing the signal, the optical disc medium () has not only a data recording area () where data is recorded at high density but also a system information recording area () where information is recorded at low density and binary equalizing/reproducing can be easily made. Information required to circuit setting is recorded in the system information recording area.

Optical disc medium having a system information recording area of low recording density

A test pattern including a first test mark which is one unit-record-length longer than a shortest mark among modulating codes and a second test mark which is two or more unit-record-lengths longer than the shortest mark is recorded under a plurality of recording conditions (step S). The recorded test pattern is reproduced (step S), and based on a plurality of reproduced signals thus obtained, recording conditions allowing the first test mark and the second test mark, respectively, to be suitably recorded are selected (step S). A recording condition for the shortest mark is determined by inference based on the recording conditions of the first test mark and the second test mark.

Recording condition setting method and information recorder using same

A recording data string is composed of a plurality of synchronous frames each of which has synchronous data and coding data. Data items in the coding data contributed to creation of the same column of the error correction code are arranged at regular intervals of E in the recording data string. A data segment length L is obtained by adding an additional synchronous frame to the recording data string. Wherein, a physical segment length A satisfies the equation L=mA, m is a natural number. And A is set indivisible by E.

Optical disk medium and optical disk recording and reproducing apparatus

In order to evaluate the quality of a signal recorded on an optical recording medium, a target signal is obtained based on a predetermined data string and a predetermined partial response characteristic, and for each clock cycle, an equalization error is calculated that is a difference between the target signal and a signal reproduced each clock cycle. Further, the product of the equalization errors calculated at different times is obtained, and based on the obtained product, the quality of a signal is evaluated.

Optical disk, optical disk recording/reproduction apparatus, and optical disk signal quality evaluation method

In a code modulating method and a code modulating apparatus, a run length has an encoding rate of &#x2154; which is equal to that of (1, 7) modulation, and indicates the number of '0' bits between adjacent ones of '1' bits in the channel bit train. A data bit train is converted into the channel bit train so that the run length has a minimum value 1 and a maximum value 10. Further, upon converting any data bit train, the channel bit train does not include a pattern &#x201c;1010101010101&#x201d; in which the run length 1 is continuously repeated six times or more. The channel bit train has a DSV (Digital Sum Value) control bit which selects the &#x201c;0&#x201d; bit or &#x201c;1&#x201d; bit in accordance with a DSV. The channel bit train obtained by using random data for the data bit train is NRZI converted into a signal. A frequency component of the signal is reduced from a maximum value of the frequency component by 20 dB or less as a power density at a frequency of {fraction (1/10,000)} or less of a channel clock frequency.

Code modulating method and code modulating apparatus, demodulating method and demodulating apparatus, and information recording medium

An optical disk provided with a land region and a groove region that are formed on a substrate, the land region and groove region being used as a recording track that is the medium of the recording/playback of information signal, and a pre-pit region that is formed at the boundary part of neighboring land region and groove region and is disposed every other boundary part, the pre-pit region including specific information. Characteristically, the specific information's in neighboring pre-pit regions are not aligned in the radius direction of the optical disk.

Optical disk device

Optical disk and optical disk device

An optical disk recording device for conducting reading and recording of data through irradiation of laser beam on an optical disk medium comprises a photo detection circuit for receiving input of reflected light from an optical disk medium to detect a reproduced signal, a pre-amplifier for amplifying a reproduced signal from the photo detection circuit and outputting the amplified reproduced signal for monitoring, and a level shift circuit for shifting a level of a reproduced signal from the photo detection circuit increased with an increase of the amount of light in data recording operation to a preset value and outputting the level-shifted reproduced signal to the pre-amplifier.

Gain control of a reproduced signal amplifier for precise monitoring of

The magneto-optical disk recording device disclosed is for recording and reproduction using a one-beam optical head and includes a magneto-optical head, a reproduction amplifier, a recording data delay circuit, a recording state detection circuit, a data comparator circuit, and a record judging circuit. The reproduction amplifier amplifies a magneto-optical reproduction signal read out by the magneto-optical head during the recording. The recording data delay circuit delays a recording data for a predetermined period of time. The recording state detection circuit receives the reproduction signal from the reproduction amplifier and detects a reproduced signal state during the recording. The data comparator circuit receives and compares an output of the recording data delay circuit and an output of the recording state detection circuit, and outputs a record failure signal. The record judging circuit judges whether to skip a record failure region or to verify a recorded state of the data when the record failure signal is outputted from the data comparator circuit. The arrangement enables the verification operation during the recording to be made simple thereby enhancing a recording speed.

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Tokyo, Japan

Toshiaki Iwanaga