Abstract: The present invention realizes stable and more proper data reproduction even when a reproduced signal varies locally due to a noise or includes a steady distortion. In a data reproduction control method and apparatus, and an optical disk unit that adjust sampled values, in sampling a signal reproduced from a recording medium recorded with data, the frequencies of the levels of quantized data are counted, a histogram of the frequencies of the levels is created based on the counting results, and more accurate reproduced data is obtained by means of a distribution of the frequencies of the levels in the histogram.

Abstract: A data signal processing apparatus is capable of reproducing original data with a small number of repetition times of an iterative decoding process, which is realized by likelihood information operating means that generate updated likelihood information, carry out a predetermined operation on a plurality of pieces of likelihood information corresponding to the original data obtained by the iterative decoding process, and reproduce the original data.

Abstract: The present invention realizes stable and more proper data reproduction even when a reproduced signal varies locally due to a noise or includes a steady distortion. In a data reproduction control method and apparatus, and an optical disk unit that adjust sampled values, in sampling a signal reproduced from a recording medium recorded with data, the frequencies of the levels of quantized data are counted, a histogram of the frequencies of the levels is created based on the counting results, and more accurate reproduced data is obtained by means of a distribution of the frequencies of the levels in the histogram.

Abstract: A data reproduction system, which determines reproduced data based on comparison results of path metrics calculated in accordance with a Viterbi algorithm based on branch metrics calculated from expected values and a sampled value of a readout signal, includes an expected value setting unit for variably setting the expected values used for a calculation of the branch metrics in order to perform a Viterbi detection process without being easily affected by the transient response, offset variation, phase error and nonlinear torsion component of the readout signal. The readout signal is obtained from a recording medium on which data is recorded in accordance with a recording signal of a partial response waveform, the expected values are determined by the partial response waveform, and the sampled value is obtained by sampling the readout signal at a predetermined frequency.

Abstract: A data reproduction device reproduces the data recorded on the recording medium by executing digital signal processing on the quantized data. The data reproduction device can share a single A/D converter and a single decoder used for reproducing recorded data based on clocks synchronous to a leading edge and a trailing edge of the recording pit.

Abstract: An optical disk recording method of recording data on an optical disk by applying laser light to a track of the optical disk, includes the steps of a) driving a plurality of laser light sources in sequence in a time division manner, and applying a light flux to one track of the optical disk successively, and b) producing a plurality of rows of record marks in the one track.

Abstract: A data readout device generates decoded data based on a decided data bit decided by performing a hard-decision on likelihood data, wherein the likelihood data is generated in accordance with an iterative decoding method corresponding to a turbo-coding process. The iterative decoding process is performed on a sampled value obtained by sampling a signal read out from a magneto-optical disk at a predetermined sampling period. The data readout device is made up of a reliability determination part and an error correcting decoder. The reliability determination part detects whether each obtained data bit was obtained from likelihood data within a predetermined range defined with respect to a histogram of log likelihood ratios. When it is detected that a data bit was obtained by a hard-decision on likelihood data within the predetermined range, the data bit is regarded as being obtained by a hard-decision whose reliability is not sufficient.

Abstract: Crosstalk cancellation is realized more accurately than ever by considering both magnitude and a phase difference of a crosstalk signal from a recording track adjoining a target track, in comparison with magnitude and a phase of a desired signal from the target track, which is implemented by providing a crosstalk amount detection means, a phase difference measurement means, and a crosstalk component generation means that generates a crosstalk component to be subtracted from a signal obtained by an optical scanning that includes the desired signal and the crosstalk.

Abstract: An information reproducing element formed by a plurality of transferring portions sandwiching magnetically insulatable regions is arranged so as to face an information recording medium. A plurality of record marks on the information recording medium are mutually insulatedly transferred onto the information reproducing element. A light beam is irradiated onto the information reproducing element. The record marks recorded by high density recording are then reproduced by magneto-optical reproduction or maximum-likelihood detection.

Abstract: A magneto-optic recording medium, which has a multilayered magnetic layer including a recording layer and a reproducing layer, is capable of reproducing a micro mark by utilizing a temperature distribution generated by laser beam irradiation for transferring a domain wall from the recording layer to the reproducing layer and by utilizing the movement of the domain wall. Each of the recording areas is arranged so that the recording area is adjacent to a magnetic partition area of a neighboring track. The recording areas and the magnetic partition areas are arranged alternately in one track, and an edge of a record mark is positioned in the recording area. Preferably, when reproducing information recorded on this magneto-optic recording medium, two neighboring tracks are irradiated with one laser beam for reproduction so that high speed transmission can be performed.

Abstract: A data reproduction device includes an A/D converter quantizing a reproduction signal read from data recorded on a recording medium to produce quantized data based on a sampling clock; a reproduction signal determination unit determining rising and falling parts of the reproduction signal based on the quantized data, and outputting a gate signal corresponding to a result of determining the rising and falling parts; a leading-edge clock generation unit generating a leading-edge clock signal synchronous to a leading edge indicating a rising part of the reproduction signal; a trailing-edge clock generation unit generating a trailing-edge clock signal synchronous to a trailing edge indicating a falling part of the reproduction signal; a signal switch unit generating the sampling clock by selecting one of the leading-edge clock signal and the trailing-edge clock signal based on a value of the gate signal; and a signal supply unit supplying the sampling clock to the A/D converter, wherein the data reproduction devi

Abstract: In a data recording apparatus, values of parity bits to be additionally provided every one predetermined length block in data obtained by demodulating the original data are determined so as to satisfy a part of or an entire the predetermined run length limitation rule in ranges of a current predetermined length block, the plurality of parity bits, and a next predetermined length block that is positioned next to the current block. The parity bits having the values are additionally provided to the current block.

Abstract: A defect detection device for detecting a defect of data recorded on a recording medium includes a waveform state detection part generating information representing a state of a waveform of a reproduced signal from the recording medium based on soft decision results obtained in process of reproducing the data in accordance with a maximum likelihood decoding algorithm corresponding to partial response, and a defect determination part determining the defect of the recorded data based on the information generated in said waveform state detection part.

Abstract: A clock adjustment device for a data reproduction apparatus includes an edge detection part detecting an edge of a reproduced signal corresponding to a predetermined synchronization pattern based on a state of change of sampled values obtained in synchronism with a clock signal from the reproduced signal, a timing signal output part outputting a timing signal in a given cycle determined by the synchronization pattern from a timing at which the edge of the reproduced signal is detected, and a phase adjustment part adjusting a phase of the clock signal when the edge of the reproduced signal is detected and every time the timing signal is output.

Abstract: In an apparatus for reproducing recorded data, a crosstalk signal is generated by converting adjacent data recorded on an adjacent track into a waveform of said reproduction signal and the crostalk signal is deducted from the reproduction signal. Then, the reproduction signal in which the crosstalk signal is eliminated is decoded in accordance with the predetermined algorithm and reproduced.

Abstract: A data reproducing method reproduces data corresponding to a state-transition pass selected as being most likely according to a Viterbi decoding algorithm from a reproduction signal supplied from a recording medium. The data reproducing method comprises the steps of detecting at least one state of the reproduction signal according to data used for selecting the state-transition pass, calculating an average value of the reproduction signal in the state detected by the step of detecting, and following a fluctuation amount of a direct current component of the reproduction signal according to the average value.

Abstract: An information recording method and an apparatus therefor, wherein a recording compensation controlling unit 1 receives data to be recorded and determines whether a pulse timing adjustment is to be performed or not, and instructs an APC 3 to adjust the timing thereby to advance the pulse start timing of laser light and/or to delay the pulse termination timing when the pulse timing adjustment is to be performed. The recording compensation controlling unit 1 determines the pulse timing adjustment corresponding to the presence or absence of a predetermined “space, record mark”, whereby the positional shift quantity of leading and trailing edges is reduced even for the marks having a fine dimension, and the jitter is reduced.

Abstract: In an apparatus for reading recorded data, the apparatus, a read signal is sampled from recorded data of a recording medium by synchronizing with a first clock signal. A sample value obtained by the sampling part is stored and also the sample value from the first storing part is retrieved by synchronizing a second clock signal different from the first clock signal and maximum likelihood data is detected by processing the sample value in accordance with a predetermined algorithm. The recorded data is read based on the detected data.

Abstract: According to the present invention, a data reproduction apparatus sampling, at a given rate, a reproduced signal obtained from a recording medium and complying with a partial response waveform, and reproducing data from sampled values of the reproduced signal in accordance with the Viterbi decoding algorithm includes difference value calculation means for calculating a difference between compared ones of path metric values in selecting paths, alternative path selection means for selecting a path different from a corresponding one of the paths, which are selected in accordance with a given rule, as an alternative path based on the difference between the compared ones of the path metric values, and reproduced data determination means for determining data to be reproduced based on the paths selected in accordance with the given rule and the alternative path.

Abstract: A recording device according to the present invention has a function (202, 206, 207) of dividing precoded record data into data blocks of a prescribed length to adjust to a magneto-optical disk (3) and adding an intrinsic pattern before and after the data blocks. As the intrinsic pattern, a pattern which reduces a decoding error of maximum likelihood decoding at an end of each data block is used. Therefore, even when data is inserted after preceding, code correlation of a precoded signal can be maintained at a location where division is performed.