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: It is an object of the present invention to provide a data reproducer in which the quality of a reproduction signal is improved. A data reproducer of the present invention includes a phase-difference detecting section which obtains the cross correlation value between the head pattern in a track to be reproduced and a reproduction signal, synchronous detectors which respectively obtain the cross correlation value between the head pattern of a track adjacent to the track to be reproduced and the reproduction signal, and crosstalk value detector which obtains the direction and ratio of crosstalk in accordance with these cross correlation values. The data reproducer has a correcting function which corrects the offset and gain of a reproduction signal in accordance with a phase difference and cross correlation value obtained by the phase-difference detecting section.

Abstract: A device inspects the performance of a perpendicular magnetic recording medium by separating the medium noise component of a perpendicular magnetic recording medium to decrease the error rate by accurately separating and detecting the medium noise component. Using correlation matrices, jitter noise and T50 noise which depend on the transition point of magnetization, and DC noise which is added to a DC component are separated and detected from the medium noise component of a perpendicular magnetic recording medium acquired from the reproducing waveform of a magnetic head. By adding a base matrix of the DC noise component to a linear separation expression for detecting the noise power from the medium noise component, the DC noise is detected using the least square method, separately from the other medium noise, which depends on the fluctuation of magnetization transition points.

Abstract: This invention is a holographic recording medium including a track in which position information to specify a recording position and a reproducing position of page data is formed. The position information of the track is formed of position detection patterns. The position detection patterns each including a first detection mark row including center pits arranged at predetermined intervals; and a second detection mark row including side marks arranged at the same intervals as the intervals of the center pits, the side marks having lengths substantially corresponding to integral multiples of the intervals of the center pits. The second detection mark row is arranged adjacent to the first detection mark row such that both ends of the side marks are arranged so as to correspond to the center pits in a track width direction, and page data is recorded and reproduced on the basis of positions of the center pits or positions of the ends of the side marks.

Abstract: A recording and reproducing apparatus includes a light source to emit a laser beam, an information light beam irradiation unit to irradiate a medium with an information light beam, a reference light beam irradiation unit to irradiate the medium with a reference light beam so as to form a specific speckle pattern on the medium. The reference light beam irradiation unit comprises a diffusion board provided in the way of a light path through which the laser beam is passed and generating the reference light beam, a rotation controller to rotate the diffusion board, and an identification information detector to detect identification information previously formed on a surface of the diffusion board. The diffusion board comprises a plurality of encode storage regions in which different identification information is formed and a plurality of diffusion pattern generation regions specified by the identification information.

Abstract: The present invention relates to a holographic recording apparatus that records on a multiple basis information on a holographic memory. An object of the present invention is to provide a holographic recording apparatus capable of avoiding problems of recording error of data and destruction of the existing data, which will occur when the medium of the specification shortages is used.

Abstract: This invention is a holographic recording medium including a track in which position information to specify a recording position and a reproducing position of page data is formed. The position information of the track is formed of position detection patterns. The position detection patterns each including a first detection mark row including center pits arranged at predetermined intervals; and a second detection mark row including side marks arranged at the same intervals as the intervals of the center pits, the side marks having lengths substantially corresponding to integral multiples of the intervals of the center pits. The second detection mark row is arranged adjacent to the first detection mark row such that both ends of the side marks are arranged so as to correspond to the center pits in a track width direction, and page data is recorded and reproduced on the basis of positions of the center pits or positions of the ends of the side marks.

Abstract: A recording and reproducing apparatus according to the present invention includes a light source for emitting a light beam, a spatial modulating part for modulating the light beam to create information light, using spatial information associated with page data A to be recorded on a holographic recording medium, an optical-path changing part for changing an optical path of the information light created by the spatial modulating part, a light detecting part for receiving the information light having the optical path changed by the optical-path changing part, and a diagnosis part for inspecting operations of recording and reproducing components including the spatial modulating part and the light detecting part, using the page data A and page data B obtained from the information light received by the light detecting part.

Abstract: The present invention relates to a holographic recording apparatus that records on a multiple basis information on a holographic memory. An object of the present invention is to provide a holographic recording apparatus capable of avoiding problems of recording error of data and destruction of the existing data, which will occur when the medium of the specification shortages is used.

Abstract: An MTR encoder includes convolution units that perform convolution of input data using additional bits, MTR encoding units that MTR-encode data obtained by the convolution units, RDS calculating units and on-bit sequence checking units that calculate RDSs and counts the number of sequential on-bits of the data MTR-encoded by the MTR encoding units, respectively, and a selecting unit that selects optimum data based on the RDSs and the number of sequential on-bits.

Abstract: A data reproduction device for sampling a signal reproduced from a recording medium based on a synchronization clock signal synchronized with the reproduced signal includes: an analog-to-digital conversion part converting the reproduced signal into a first digital signal based on a first clock signal; an interpolation part interpolating the first digital signal so that the first digital signal is equalized with a second digital signal sampled based on a second clock signal having a frequency n times the frequency of the first clock signal; an optimum phase detection part receiving the output of the interpolation part and detecting the phase error between the optimum point of the reproduced signal and the synchronization clock signal; a phase correction part correcting the phase of the reproduced signal based on the phase error; and an information data start detection part detecting the start of information data based on the phase error.

Abstract: A reproducing device performs error correction, detects a medium defect at an early stage and performs erasure correction. A reproducing device having an error correction circuit is provided with a medium defect detector. The medium defect detector computes a moving average value of the reproducing signal, slices this moving average value with a threshold Th, and detects a defect. A continuous amplitude drop can be detected accurately compared with a simple threshold detection, and deterioration of error correction capability due to a detection error can be suppressed. Also a defect can be detected in a previous stage of the error correction decoding, so a defect can be detected at an early stage, and erasure can be corrected at an early stage during error correction.

Abstract: A reproducing device performs decoding by propagating the reliability, and detects micro medium defects to correct the reliability information. The decoder has an internal decoder, external decoder and a defect detector which calculates a moving average value of a soft-input signal, acquires a scaling factor from this, and manipulates the reliability information of the internal decoder. Since micro-defects can be detected accurately and the reliability information of the internal decoder is manipulated, error propagation due to micro defects can be suppressed.

Abstract: An optical recording medium which comprises a holographic recording layer on which information is recorded by means of holography, a light shield member fixed to at least one of main surfaces of the holographic recording layer, a control electrode for controlling a light transmission state of the light shield member, wherein, the light shield member has a plurality of pixels obtained by dividing the light shield member on a recording unit region basis, and the light transmission state can be controlled pixel by pixel.

Abstract: An ECC decoder outputs, to a likelihood substituting unit, information on data in data blocks that is corrected to be valid. Based on the information, the likelihood substituting unit substitutes likelihood corresponding to the data corrected to be valid by the maximum value, and outputs it to an LDPC decoder. The LDPC decoder decodes user data with likelihoods partly substituted by the maximum value using LDPC parity, and calculates likelihood of data that constitutes the user data. The LDPC decoder outputs the calculated likelihood to a channel APP decoder as external data.

Abstract: A recording and reproducing apparatus includes a reproduction signal detection unit reproducing a two-dimensional pattern previously recorded on a holographic recording medium or user data recorded on the holographic recording medium, a reference pattern storage unit previously storing a reference pattern to be provided when the two-dimensional pattern is reproduced, a correction information generation unit comparing a reproduction reference pattern signal corresponding to the reproduced two-dimensional pattern with the stored reference pattern and removing fixed distortion contained in the reproduction reference pattern signal to generate correction information used for reproducing the reference pattern from the reproduction reference pattern signal, a correction information storage unit storing the correction information, and a distortion correction unit performing a correction calculation for a reproduction data signal using the correction information to generate corrected reproduction data from which the

Abstract: An MTR encoder includes convolution units that perform convolution of input data using additional bits, MTR encoding units that MTR-encode data obtained by the convolution units, RDS calculating units and on-bit sequence checking units that calculate RDSs and counts the number of sequential on-bits of the data MTR-encoded by the MTR encoding units, respectively, and a selecting unit that selects optimum data based on the RDSs and the number of sequential on-bits.

Abstract: A data storage medium includes a data area used for storing data, an address area used for identifying the data area, a first mark that is formed in the address area and represents a bit string corresponding to an address, and a second mark that is formed in a vicinity of the address area and indicates a position where each of all bits in the bit string corresponding to the address is arranged.

Abstract: A decoder decodes a code by selecting, based on a predetermined condition, a path out of paths representing a transition of each of states in a trellis diagram. A storing unit stores, when a path at time k is selected, information on a selection history of a path selected at time prior to time (k?(a constraint length of a code)+1). A path detecting unit detects a path to be excluded from a path selection candidate, based on the information stored in the storing unit and information on a state of a transition source when a state transition occurs from time k?1 to time k.

Abstract: An information sequence having a code length of N (N=K+M), where K is information length and M is parity length, is encoded into a code sequence by using an LDPC code. The LDPC code is generated based on a matrix H, with M rows and N columns. The matrix H includes a check matrix H2 and a check matrix H1. The check matrix H2 has M rows and M columns, it is a cyclic permutation matrix, and an inverse matrix exists for the check matrix H2, and its column weight is 3. The check matrix H1 has M rows and K columns.