Abstract: A data storage device is provided that is suitable for use under the environment where mechanical shock is frequently applied. The data storage device includes plural storage units as closed structures each of which houses a storage medium therein, the storage medium being capable of moving relative to a head for access, an external force detection portion for outputting signals corresponding to external forces applied to the storage units in plural directions, and a controller for controlling the storage units. The storage units are arranged in such a manner that the storage units are different from one another in a direction of relative movement between the storage medium and the head, and the controller selectively makes one or more of the storage units perform an access operation in accordance with the signal outputted from the external force detection portion.

Abstract: A method is provided for storing data by distributing the data into plural storage units that are accessible independently of one another. The method includes the steps of dividing data to be stored into plural data blocks, generating parity data corresponding to the data blocks, distributing the plural data blocks and the parity data into the storage units to let the storage units store the same, responding to a situation where any of the storage units becomes inaccessible, reconstructing data stored in the storage unit that has become inaccessible before the situation occurs based on data stored in the remaining storage units, dividing the reconstructed data into plural reconstructed data blocks, generating parity data corresponding to the reconstructed data blocks, and distributing the plural reconstructed data blocks and the parity data corresponding thereto into accessible storage units to let the accessible storage units store the same.

Abstract: In an apparatus for recording and regenerating data, a pass metric is calculated based on a likelihood converted from a previous calculation result iteratively until all pass metrics of the same data recorded many times on a recording medium are calculated, and then data recorded on the recording medium is decoded.

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: In an apparatus for recording and regenerating data, a pass metric is calculated based on a likelihood converted from a previous calculation result iteratively until all pass metrics of the same data recorded many times on a recording medium are calculated, and then data recorded on the recording medium is decoded.

Abstract: A recording/reproducing apparatus records and reproduces, over a partial response channel, a recording signal produced by encoding data according to a convolutional code and reproduces the data from a reproduction signal by iterative decoding using likelihood information. A burst error detector detects a burst error part in the reproduction signal. A substituting part substitutes, for a sampling value included in the burst error part, a predetermined value according to a detected result of the burst error detector.

Abstract: A holographic recording medium is a medium which records and reproduces data by irradiation with an information beam and a reference beam. This medium includes a user region for recording user data; and a calibration region for storing calibration data for calibrating an element which determines a recording and reproducing characteristic of a recording and reproducing apparatus for recording and reproducing data on/from the recording medium. The calibration data stored in the calibration region includes pattern information for measuring the element determining the recording and reproducing characteristic of the recording and reproducing apparatus.

Abstract: A reproducing apparatus for an optical recording medium, comprising: a reference beam irradiator for irradiating an optical recording medium on which information is recorded by holography with a reference beam to generate a reproduction beam; a two-dimensional image pickup device capable of being partially read, which receives the reproduction beam; a partial reading controller for controlling partial reading of information on the two-dimensional image pickup device; and an information processor for performing a predetermined process by using the information to be partially read.

Abstract: A recording and reproducing device includes: a reference light irradiating section; a spatial light modulating section for generating information light; an information light irradiating section for irradiating the same region as a region irradiated with the reference light, with the information light; a light detecting section for receiving reproduction light; a known data storage section; a defect examining section for examining a defective position of the spatial light modulating section or the light detecting section by irradiating the information light and the reference light to write the known page data to the holographic recording medium, and then irradiating the medium with the reference light to read the known page data written on the holographic recording medium from the reproduction light received by the light detecting section; and a reproducing control section for restoring and reproducing the original data of the defective position using information of the defective position detected by the defec

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: 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: A data recording method for calculating a digital sum value (DSV) corresponding to a proportion of positive data and negative data included in predetermined data ranges, selecting a resync pattern to be inserted between the data ranges according to the DSV, and inserting the selected resync pattern between the data ranges, has a step of selecting a resync pattern that minimizes differences in DSV between the data ranges.

Abstract: In a data reproduction method and apparatus of the present invention, a Viterbi detection unit is provided, the Viterbi detection unit having a plurality of detectors each providing a first partial response signal with a first constraint length from a first sequence of samples derived from a first readout signal. One of connection and disconnection of the plurality of detectors in the Viterbi detection unit is selected in response to a timing signal, wherein, when the connection of the plurality of detectors is selected, the Viterbi detection unit provides a second partial response signal with a second constraint length from a second sequence of samples derived from a second readout signal, the second constraint length being different from the first constraint length.

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: 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: 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: A clock adjustment apparatus for adjusting a phase of a clock signal based on a phase error thereof is provided in a data reproduction system which samples a readout signal from a recording medium in synchronism with the clock signal, and reproduces data in accordance with a Viterbi algorithm by using sampled values of the readout signal. The recording medium is recorded with the data modulated in accordance with a recording rule of a predetermined partial response characteristic. The clock adjustment apparatus includes a phase error calculation circuit which calculates the phase error of the clock signal based on the sampled values of the readout signal.

Abstract: A data format, a data recording/reproducing method, and a data recording/reproducing apparatus are provided for effectively correcting data errors caused by dust and scratches on a recording medium even with the use of a conventional ECC. The data recording/reproducing apparatus includes a generation unit that generates predetermined data units by dividing an ECC sector including error correction codes generated by an error correction encoder into prescribed data units and encoding the prescribed units into iterative encoded data units using an iterative encoder so that the predetermined data units may consist of the iterative-encoded data units, a recording unit, a reproducing unit, an iterative decoder for conducting iterative decoding on the predetermined data units, and an error correction decoder. The apparatus further includes a distribution unit for distributing the predetermined data units generated by the generation unit.

Abstract: In an apparatus for recording and regenerating data, a pass metric is calculated based on a likelihood converted from a previous calculation result iteratively until all pass metrics of the same data recorded many times on a recording medium are calculated, and then data recorded on the recording medium is decoded.

Abstract: In an apparatus for recording and regenerating data, a pass metric is calculated based on a likelihood converted from a previous calculation result iteratively until all pass metrics of the same data recorded many times on a recording medium are calculated, and then data recorded on the recording medium is decoded.