Abstract: An apparatus for controlling recording or reproduction includes a maximum likelihood decoding section for performing maximum likelihood decoding of a digital signal having a waveform thereof rectified and generating a first binary signal representing a result of the maximum likelihood decoding; a reliability calculating section for calculating a reliability of the result of the maximum likelihood decoding based on the digital signal having the waveform thereof rectified and the first binary signal; a jitter detection section for detecting jitter; and a parameter setting section for setting a value of a prescribed parameter which is a recording parameter or a reproduction parameter. The parameter setting section calculates a first optimum value of the prescribed parameter based on the reliablilty, calculates a second optimum value of the prescribed parameter based on the jitter, and sets the value of the prescribed parameter between the first optimum value and the second optimum value inclusive.

Abstract: A method and an apparatus which adjusts a signal read from an optical disc in order to obtain stable binary data. The signal adjustment method comprises (a) detecting a period of an input signal of a predetermined code; (b) determining whether the detected period is smaller than a predetermined value; and (c) if the detected period is determined to be smaller than the predetermined value, adjusting the input signal so that its period equals the predetermined value, and outputting the input signal. The signal adjustment method and apparatus of the present invention reduce errors and improve system performance, when a signal input to the binary processor does not meet its code feature.

Abstract: A processing scheme for digital storage media using multi-user detection to separate tracks of data or remove interference from neighboring tracks. In one embodiment, data is written on a plurality of tracks positioned sufficiently close together so that multiple tracks are detected simultaneously by the read access sensor. Upon scanning the surface for data, the read element simultaneously receives the data signals from a plurality of tracks. Joint detection signal processing resolves the interference and data bits from the multiple sensed tracks, enabling closer packing of data with minimal guard space.

Abstract: A system and method for reading and writing in a multilevel optical data system is disclosed. The system provides control signals for timing acquisition, level calibration, DC control, AGC, equalizer training and data synchronization. The user data is ECC protected and optionally convolutionally encoded before being combined with the control signals in an information block. The multilevel information block can be written to an optical disc as a series of multilevel marks. The optical disc may also contain an Address in Pregroove signal (AIP) to facilitate synchronization during writing of an information block. The AIP signal has an integer number of address frames per information block.

Abstract: A data estimating circuit outputs estimation data which estimates input data at a time earlier by a predetermined bit cycle than the input data based on decoded data series outputted from a path memory. A target value computing circuit corrects the target value with a difference between the estimation data and input data as a target value error and outputs obtained plural first target values to a branchmetric operating circuit as plural target values. Because the branchmetric operating circuit can conduct branchmetric operation based on plural first target values near plural averages having the highest incidence (having peaks in histogram), decoding performance can be improved more as compared to using fixed target values.

Abstract: A clock generator in a recorded information reproduction apparatus for reproducing recorded information from a recording medium includes a pickup that produces a reading signal by reading a recording track of the recording medium. The reading signal is sampled by a sampling circuit at timing corresponding to a clock signal to produce a reading sample value sequence. A crosstalk removing circuit removes crosstalk components which are present in recording tracks adjacent to the recording track read by the pickup from the reading sample value sequence and produces a crosstalk-removed reading sample value sequence. A phase detecting circuit detects a phase error existing in the reading signal based on the crosstalk-removed reading sample value sequence. A clock signal generating circuit generates the clock signal based on the phase error.

Abstract: 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.

Abstract: Disclosed herewith is an information reproducing method for realizing significant expansion of disk capacity and processing signals having different minimum run lengths, as well as an optical disk drive that uses the method. To achieve the above objects, a PRML method is used. According to the method, a compensation value is added to an initial target value decided by a convolution operation of NN bits according to a bit array consisting of N bits (N>NN) to obtain a new target value, which is then compared with each of reproduced signals sequentially to select a bit array in which the error between the reproduced signal and the target signal is minimized most likely, then the selected bit array is binarized.

Abstract: A data reproduction apparatus for adjusting filter coefficients of an equalizer including a digital filter, and connected before a Viterbi detector and a method therefor. A level of the output value of the equalizer is detected based on a reference level set in the Viterbi detector, and a level error of the detected level with respect to a predetermined reference value is detected. The filter coefficients of the equalizer are adjusted such that the level error is minimized, thereby improving the detection performance of the Viterbi detector.

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 the case of a method of detecting a signal edge in a signal with temporally successive signal edges, there are performed, after triggering by an interrupt signal (IS) generated in an analog/digital converter (13), detection of a rise-representing rise value between two detected amplitude values with subsequent assessment of the rise value together with detection of signal edge direction information and signal edge occurrence information. Further use of this signal edge information is dependent on an additionally detected and assessed signal strength value, which signal strength value is formed from a sum of further amplitude values.

Abstract: In an optical disk of the invention composed of two substrates bonded to each other, the level of double refraction is set to 60 nm or less in a read-only disk, to 60 nm or less in a write-once type disk, and to 40 nm or less in a rewritable type disk, respectively.

Abstract: An optical disk data decoder generates estimates of serial input signal values by slicing them into samples. The data sequences contained in each sample are detected. Successive samples are compared and used to increase or decrease the estimates. Such permits the center bit in a string of identical bits to be detected after subsequent bits have already been received and are being processed.

Abstract: A selective disturbance compensating apparatus for use in reproduction from an optical recording medium, and a 3T-correcting method. A DC offset canceller extracts a DC offset from a reproduction signal to cancel the DC offset. An equalizer equalizes the offset-cancelled signal. A switching unit selects between the offset-canceled signal and the equalized signal according to whether distortion caused by asymmetry of the signal is above or below a predetermined reference level. A 3-T correcting unit corrects asymmetry of the selected signal. In another embodiment, a second switching unit selects between the 3-T corrected signal and a Viterbi corrected signal.

Abstract: An optical disc reproducing apparatus including a viterbi detector for an optical disc in which digital data is stored includes an optical pick-up for reading digital data stored in the optical disc and for generating a high frequency signal, an analog-to-digital converter for sampling and quantizing the high frequency signal, and a viterbi detector for decoding a quantized signal output from the analog-to digital converter and reproducing an eight to fourteen modulation (EFM)/EFM+signal. The viterbi detector includes a branch metric calculator for receiving a signal constituted of n bits, for comparing the signal with previously set three variables, and for calculating a branch metric with respect to the input signal. A path metric update and storage unit receives the branch metric, adds the branch metric to values stored therein, compares the error content of all the possible paths with each other, and stores a metric with respect to the path having the smallest amount of errors.

Abstract: A data reproduction apparatus that employs an expected value generation unit that employs a maximum likelihood decoding algorithm, thereby an expected value is correctly determined from a histogram of sampled values of a signal to be reproduced, even when an offset arises in the signal to be reproduced, the offset being removed from the sampled values used in generating a histogram that is used to determine the expected value.

Abstract: Domain bloom, also known as asymmetry, is a systematic imperfection caused by the writing process in optical discs. During disc read-out it causes signal transitions to shift with respect to their nominal positions. State-of-the-art equalization and detection methods suffer significant performance losses if directly applied to replay signals with asymmetry. A non-linear model for replay signals with asymmetry is used for new equalization and detection techniques that are applicable to signals in the presence of asymmetry. Modifications are described of the threshold bit-detector, the run-length pushback bit-detector, and the PRML sequence detector, which have significant performance benefits. These benefits come at almost no additional cost with respect to existing detectors.

Abstract: A system and method are disclosed for reading a multilevel signal from an optical disc. The method includes reading a raw analog data signal from a disc using an optical detector and adjusting the amplitude of the raw analog data signal. A timing signal is recovered from the amplitude adjusted analog data signal and correction is made for amplitude modulation of the raw analog data signal by processing the raw analog data signal and the timing signal.

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: An address reproduction circuit for reproducing address information based on a reproduction signal which is read from an optical disc including a guide groove having a wobbling shape which represents modulated address information. The address reproduction circuit includes an A/D conversion section for converting an analog wobble signal included in the reproduction signal into a digital wobble signal; and a maximum likelihood decoding section for generating an address signal representing address information having maximum likelihood from the digital wobble signal based on a state transition rule defined by a modulation rule of the modulated address information.

Abstract: An optical disk device has reproduction signal detecting section, each of which detects a reproduction signal corresponding to a reflective wave of an optical disk, a first offset controller, which offsets the reproduction signal with a first offset value F1, an A/D converting circuit, which A/D converts the offset reproduction signal, and a second offset controller, which offsets the converted digital reproduction signal with a second offset value F2, and a decoder, which viterbi decodes the offset digital reproduction signal and outputs decoded data B. Because an offset is performed with each exclusive value to A/D conversion and viterbi decoding, it is possible to obtain high identification accuracy with nonlinear characteristic eliminated.

Abstract: A demodulator includes a wobble signal processor configured to convert a waveform of a wobble signal, and to generate a clock and a reference value based on a converted wobble signal. A sampling circuit is configured to sample the converted wobble signal by using the clock, and to generate a sampled signal. A viterbi decoder is configured to decode an auxiliary recording signal superposed on an optical disk by using the reference value and the sampled signal.

Abstract: A data reproduction apparatus for adjusting filter coefficients of an equalizer including a digital filter, and connected before a Viterbi detector and a method therefor. A level of the output value of the equalizer is detected based on a reference level set in the Viterbi detector, and a level error of the detected level with respect to a predetermined reference value is detected. The filter coefficients of the equalizer are adjusted such that the level error is minimized, thereby improving the detection performance of the Viterbi detector.

Abstract: A focus offset setting portion gives a predetermined quantity of offset to a focus control quantity used to reduce a focus error signal to zero based on the focus error signal generated by a focus error generation portion, and outputs a result. An adaptive equalizer including an adaptive control portion and an FIR filter subjects a reproduction signal RF provided from an optical pickup to waveform equalization based on a signal decoded by a Viterbi decoder. A controller obtains an optimum point of a focus offset by using a tap coefficient of the adaptive equalizer, and changes a set value of a focus offset setting portion.

Abstract: The present invention relates to a method for compensating asymmetry in a reproduction signal DRSO from an optical recording medium, and to an apparatus for reading from and/or writing to optical recording media using such method. It is an object of the invention to propose a method for compensating an offset in an asymmetric reproduction signal DRSO capable of compensating the offset even if the amplitude of the shortest run-length components is smaller than the asymmetry of the reproduction signal DRSO.

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 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: A signal can be detected based on a level slice system and detection delay time can be reduced by setting the recording density of a header field in a linear direction lower (coarse) than that of a user data recording field. Further, a signal can be detected based on the level slice system and detection delay time can be reduced by using a mark position form having a large detection margin as an information recording system of the header field. A readout error of a sector number due to a detection error is compensated for by recording address marks AM for attaining byte synchronization of the header field in both of a head portion and tail portion of information recorded in the header field.

Abstract: There are provided a modulation table, a selector, and a counter. The modulation table is used for creating a plurality of modulation data candidates with respect to a mixture of user data and training data. The selector selects modulation data candidates. The counter counts DSVs for the selected modulation data and controls the selector. The DSV output from this counter is set to a specified value by keeping a state in which the training data is input.

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 recording method includes the steps of generating recording data in such a manner that, when m-bit data is converted into a data symbol of n bits (m<n), and connection bits such that the summed value of DC components per unit time decreases are selected from among a plurality of connection bits and are added after the m-bit data symbol, the connection bits differing from connection bits which are added when the n-bit data symbol is a data symbol other than the special data symbol are added to generate recording data; and recording the generated recording data on a recording medium.

Abstract: To provide an asymmetry correcting circuit capable of canceling an asymmetry simultaneously with quantization in an ADC and utilizing the dynamic range of the ADC effectively, and also to provide an information reproducing apparatus using such a correcting circuit.

Abstract: An optical recording medium having a track on which data has been previously recorded, comprising on the track a plurality of data block regions each of which includes main data of a block which is divided into a predetermined number of main data pieces, each of which has data for identifying the main data, and linking regions each of which has pseudo data and is inserted between the data block regions. When the linking regions on said track are adjacent, recording patterns of the pseudo data of the adjacent linking regions are different from each other. Further provided is a recording apparatus forming the data block regions and linking regions on a recording medium.

Abstract: A signal of a run-length-limited code is reproduced from a recording medium. A transversal filter subjects the reproduced signal to a partial-response waveform equalization responsive to tap coefficients. Detection is made as to whether or not the reproduced signal corresponds to a peak point. Peak-point information is generated in response to a result of the detection. A delay circuit outputs at least three successive samples of the peak-point information. A temporary decision device operates for calculating a temporary decision value of the equalization-resultant signal on the basis of the successive samples of the peak-point information. A difference between the temporary decision value of the equalization-resultant signal and an actual value thereof is calculated, and an error signal is generated in response to the calculated difference. The tap coefficients of the transversal filter are controlled in response to the error signal so as to minimize the error signal.

Abstract: In a digital recorded data reproduction which applies PRML signal processing, it is an object to enhance a reproduction signal quality and a playability for an abnormal signal by an offset correction and a phase-interpolation-type digital phase-locked loop. A prescribed frequency band of a reproduction signal is emphasized by a waveform equalizing unit 2, and its output signal is sampled by an asynchronous clock at an analog/digital converter 3. After a sampling signal is subjected to the offset correction, PR equalization is performed by a transversal filter 6 and a tap weighting factor control unit 8 which applies LMS algorithm, and a signal of a regular sampling phase is reproduced from its output signal by a high-order interpolation filter 7 employing a digital phase-locked loop 11. The reproduced signal in a regular phase is demodulated by a maximum likelihood decoder 12, thereby to reproduce digital data recorded on a medium.

Abstract: In an information detecting circuit, an equalizer equalizes an output from an A/D converter as an A/D converting information. A first interpolation circuit generates an interpolating value. A delay circuit delays the A/D converting information with a delay quantity equivalent to an output delay quantity of the equalizer. A second interpolation circuit generates an interpolating value. An interpolating position generating circuit produces an interpolating position information for generating an interpolating value synchronized in phase with the channel clock and supplies the interpolating position information into the first interpolation circuit and the second interpolation circuit. A binary encoder converts the output of the first interpolation circuit. A tap coefficient controller generates a tap coefficient from interpolating value outputs of the first and second interpolations. A rate correcting circuit converts the tap coefficient to be fed-back to the equalizer.

Abstract: DVDs have currently the highest storage density among the optical discs of practical use. Due to the high storage density the reproduced signal is deteriorated by noise caused by inter-symbol interference, crosstalk, focus error, or mastering errors. A conventional threshold bit detector generates a high bit error rate in case of low SNR. For accurate reproduction of digital data from a DVD under low SNR conditions, a specific Viterbi detector is used which performs maximum likelihood sequence estimation.

Abstract: An apparatus, a method, and a computer readable recording medium thereof to update filter tap coefficients of an equalizer include a defect signal detection unit and a coefficient updating unit. The defect signal detection unit receives a sampled input signal reflected from an optical disc and/or a track jump signal, detects whether the input signal and/or the track jump signal are defective, and outputs an update stop signal indicative thereof. The coefficient updating unit stops the updating of the filter tap coefficients in response to the update stop signal and outputs current filter tap coefficients.

Abstract: An information recording and reproduction apparatus has a turbo decoder that decodes turbo encoded data. The turbo decoder has a number of likelihood ratio calculation units, forward direction path probability calculation units the number of which is less than the number of the likelihood ratio calculation units, and backward direction path probability calculation units the number of which is less than the number of the likelihood ratio calculation units. The likelihood ratio calculation units calculate in parallel the likelihood ratio for each of a plurality of data blocks. The forward direction path probability calculation units time-divisionally calculate probabilities of the forward direction paths for the data blocks. The backward direction path probability calculation units time-divisionally calculate probabilities of the backward direction paths for the data blocks.

Abstract: Recording and reproduction are performed on an information recording medium at high density. Marks having front and rear edges deviated in M levels in accordance with multilevel data are recorded at predetermined mark intervals. In information reproduction, adjoining front and rear edges are read at the same time to generate read data in succession when a spot area of a reading light beam falls on mark reference positions and space reference positions. Approximate analysis such as Viterbi decoding is performed to compare the read data with predetermined expected value data. Based on the result, the deviations of the front and rear edges of each mark are determined to decode the multilevel data. Here, a row of reference marks having front and rear edges corresponding to combinations of M levels of deviation is recorded as if the foregoing marks are. The row of reference marks is read as if the foregoing marks are, so that the expected value data for the approximate analysis is obtained.

Abstract: A signal delay apparatus is provided with; a FIR filter for detecting a leakage signal, which is mixed in a digital detected signal, which is optically obtained from a main truck to be detected in association with the information recorded on a sub truck adjacent to the main truck to be detected, based n a filter coefficient; a coefficient setting unit for generating the above filter coefficient based on the digital detected signal, of which leakage signal is removed, and a digital detected signal, and outputting the generated filter coefficient to the filter; a CPU for controlling the delay amount in the delay with respect to any filter coefficient based on the change of the filter coefficient, which is generated in a predetermined time period and variable delay circuits and for delaying the digital detected signal and the digital detected signal by the controlled delay amount.

Abstract: An apparatus includes a multiple detecting unit having n detectors, and a controller which selects one of the n detectors and controls the selected detector to output a binary signal. In the apparatus, a plurality of detectors are used to detect a signal read from an optical storage medium, and the optimum detector is selected in consideration of a quality of the signal and detection conditions, thereby increasing the efficiency of a signal reproduction. The apparatus can selectively compensate for disturbance of a signal where data from the optical storage medium is reproduced. The apparatus may control a run length of the signal to be 3T.

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 multi-value data recording and reproducing device is provided that can accurately eliminate interference among codes through waveform equalization when reproducing information from a reproduction signal having levels multi-valued through modulation of the areas of recording marks on an optical information recording medium. This multi-value data recording and reproducing device is embodied by a multi-value data detecting circuit that varies the sizes of the recording marks in accordance with multi-value data (0, 1, 2, . . . , (m−1): m being an integer of 3 or greater) on the optical information recording medium, and detects the multi-value data through predetermined signal processing on signals obtained by scanning the recording marks with an optical spot.

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 signal can be detected based on a level slice system and detection delay time can be reduced by setting the recording density of a header field in a linear direction lower (coarse) than that of a user data recording field. Further, a signal can be detected based on the level slice system and detection delay time can be reduced by using a mark position form having a large detection margin as an information recording system of the header field. A readout error of a sector number due to a detection error is compensated for by recording address marks AM for attaining byte synchronization of the header field in both of a head portion and tail portion of information recorded in the header field.

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: There is provided an information reproducing device which outputs an equalization signal P by applying equalization processing to a signal detected from a storage medium based on equalization coefficients C0 to CN, outputs a decoding signal d by applying maximum likelihood decoding processing based on reference levels R0 to R6, generates an ideal waveform signal I based on the equalization signal, and has a target waveform generator which generates a target waveform signal T by changing at least one level of the ideal waveform signal I, wherein erroneous decoding is reduced by optimizing reproduction processing parameters such as the equalization coefficients C0 to CN or the reference levels R0 to R6 based on the target waveform signal T and the information on the storage medium is stably reproduced.

Abstract: An evaluation method for calculating an identification signal by using PRML, comprises a table storing true patterns and ideal signals thereof, false patterns corresponding to the true patterns and ideal signals thereof, and Euclidean distance between the true pattern and the false pattern, a calculating unit, when a recording signal synchronized with an identification signal coincides with any pattern of the table, calculates a distance between Euclidean distance between the ideal signal of the true pattern and a reproduction signal and Euclidean distance between the ideal signal of the false pattern and a reproduction signal, and an evaluation unit which evaluates an identification signal by using an average and standard deviation of difference. A table for patterns is created for a likely mistaken pattern, whereby calculating an evaluation value with high precision, of a signal quality, with a small amount of calculation.

Abstract: 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.