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: An apparatus for writing on and reading an overwritable optical disk comprises an identifier detector that identifies a recording condition in the sector to be overwritten, and a delay time controller circuit that sets a variation range of the start point for writing according to the recording condition. The record timing of the modulated data signal is changed at random within the set variation range when overwriting the sector of the optical disk.

Abstract: An information reproducing method includes the steps o of reading information from an information medium that is rotated, and determining a rotation velocity of the information medium on the basis of a data transfer rate based on a specification of a read request.

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: A modulation/demodulation method of a run length limited method and a modulation/demodulation apparatus relate to converting a bit stream of a recording data into a bit stream proper to a recording phase when recording a data onto an optical recording medium. In the present data modulation and demodulation method, modulation data consist of partly consecutive 0s or 1s which are quantized in length, satisfying the given minimum and maximum run lengths of RLL at the same time. Therefore, a reproducing error is checked and corrected based on whether the quantizing condition is violated or not during the demodulation. This error recovery capability makes it possible to enhance a recording density of a recording medium and to reduce a judgement error possibility due to a jitter component of a reproducing signal, so that provides a high reliability for high density recording medium compared to a conventional modulation method.

Abstract: In an optical recording medium, a groove G and/or a land L composing a recording track includes an interrupted portion of a predetermined length in a direction of the recording track, and the interrupted portion is a clock mark to obtain a clock signal. When (clock mark length C1)/(beam spot size D1)=CM, CM≦1.0. This reduces a region to record the control signal, thereby enabling high-density recording and reproduction, reproducing a control signal having a waveform free from distortion, and generating a clock signal in a state of little jitter.

Abstract: The present invention relates to a method for identifying a data area D,E or D,G, reserved in accordance with a first specification, as useful data area G in accordance with a second specification.

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: By adding a predetermined offset value which is not less than 0 to, to the value of a readout power at a time when readout power control operations are temporarily suspended, i.e., at a time when an optical head initiates a seek operation, with an adder, this latter value being stored in a readout power value storage circuit, because an optical recording medium readout apparatus makes it possible to cause the value of the readout power at the time when readout power control operations resume, i.e., at the time of completion of the seek operation performed by the optical head, to avoid abnormal power domains in which change in amplitude ratio with respect to change in readout power is not monotonically decreasing, it is made possible to avoid abnormal conditions such as occurrence of lag in response during readout power control operations.

Abstract: An information storage medium has a plurality of reference data recording areas that record reference data which is used in at least one of circuit constant adjustment of an information reproduction apparatus and characteristic evaluation.

Abstract: A method and apparatus to initialize a memory with random data, including a pseudo-random number generator to generate random data; a selection circuit to provide selected data in response to a fill signal during an initialization state. The present invention can be used to provide statistically unbiased random data for writing to the power calibration area (PCA) of an optical disc.

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 optical disc playback apparatus capable of signal processing so that the above-noted new jitter does not appear even when a waveform equalizer is used is provided. A trimmer is inserted before the waveform equalizer, the maximum amplitude in the positive direction of the playback signal waveform and the maximum amplitude in the negative direction are limited so that amplitude in the positive direction and amplitude in the negative direction are substantially equal. Jitter in the playback signal can be improved as a result.

Abstract: A recording medium includes first information selected from a plurality of information patterns and second information selected from another plurality of information patterns for the true-false judgement. A true-false judging device performs a statistic analysis when any coincidence is found between the readout combination of the first and second information and registered combination patterns, to identify an inspected recording medium as a forged product based on the result of the statistic analysis.

Abstract: A method protecting a header region formed in an optical disc when a signal is written on the optical disc and an apparatus therefor. The method protecting a header region of an optical disc write apparatus comprises detecting the header region from an RF signal detected from the optical disc through a pick up, generating a write clock, generating a write control signal whose state is inverted after the lapse of a predetermined clock by counting the write clock, generating a write stop signal when the write control signal is generated in the header region detected in the detecting of the header region, and controlling the intensity of the write laser beam corresponding to the write control signal. The generating of the write stop signal comprises feeding the write control signal back to the generating of the write control signal to control the write control signal.

Abstract: A system and method are disclosed for generating a transition in a laser control signal at a precise point in time. A write strategy processor is configured to input a sequence of data and to determine a transition in a laser control signal from the sequence of data. The transition is specified by a number of pulse clock units and a delay. A write pulse generator is configured to input the number of pulse clock units and the delay and to generate a transition by creating a signal having a transition at the time specified by the number of pulse clock units and delaying the transition by the specified delay.

Abstract: Multi-pulse trains of a forward laser beam are applied to an optical disc to record mark areas thereon. The multi-pulse trains correspond to the mark areas respectively. The multi-pulse trains represent information to be recorded. Detection is made as to an intensity of a reflected laser beam which results from reflection of the forward laser beam by the optical disc. The detected intensity is divided by a setting intensity to get a division result. A condition of recording of each of the mark areas is detected in response to the division result. An amplitude of each of the multi-pulse trains is controlled in response to the detected condition.

Abstract: An information recording apparatus and a method therefor which can form a beam guide groove in the shape of highly accurate rectangle having abrupt edges. A recording mark is formed by exposing a recording medium with a recording beam having a beam diameter smaller than the beam guide groove, while periodically vibrating the recording beam in a direction perpendicular to a recording track on the recording medium, or in both horizontal and vertical directions of the recording track.

Abstract: A method of recording information on an information medium, especially on an optical recording medium with light. It has been hard to determine optimum power accurately due to the influence of the linearity and the mark length dependence on rewrite deterioration when a write parameter calibration on a phase change optical disk is performed by a conventional asymmetry method prior to information recording. According to the present invention, a single pattern or a random pattern is recorded on an information medium, and the difference between the clock and the data edge is detected using a reproduced signal. On the basis of this difference, the threshold power of the recording is determined and multiplied by a constant to optimize the recording power.

Abstract: An optical disk device that records and reproduces information on/from a recordable optical disk is provided.

Abstract: A method and an apparatus establish manufacturer-specific test writing parameters for writing of a writable optical storage media in accordance with the media manufacturers, which are experimentally determined and stored into a certain storing unit; determine an optimum writing light power based on the determined optimum writing parameters; and write an input signal into the user's data region of the optical disk.

Abstract: In recording dots corresponding to the data to be recorded in the record transmission path, the dots are recorded optically readably so that the recorded data may be reproduced by using two-dimensional interference from the adjacent dots. In reproducing data, after the code image has been processed by equalization in the PR-equalization portion, and simultaneously based upon the reading point position information detected in the reading point calculation portion, the values in the reading points are judged, and in the decoding portion, these read data are judged and decoded based upon the predetermined decoding rules, and they are converted into the original data.

Abstract: The present invention relates to a disk recording medium such as a CD or a DVD in which data is recorded in high-density, and method and apparatus for reproducing data recorded in the high-density disk recording medium. The data reproducing method and apparatus according to the present invention converts a high-frequency signal reproduced from the disk into a plurality of binary signals through comparing the reproduced signal with two or more slicing levels which are different each other, selects one of the plurality of binary signals or a periodic pulse signal based on the difference magnitude between the plurality of binary signals, synchronizes a reference clock with the selected signal, and restores the selected signal into bit stream using the synchronized reference clock.

Abstract: An optical disc 1 has spiral grooves GR formed on a data recording surface thereof and in which information is written to, and read from, both a land between the grooves and the grooves as tracks. Each track has a plurality of address areas AR1 and user areas AR2 formed thereon, and each of the address areas AR1 has embossed pits for a groove header GRH and embossed pits for a land header LH. Each of the address areas AR1 has provided in a leading part thereof a header mark area HM formed from a mirror finished surface. That is, this optical disc is of an on-land/in-groove recording type. An offset taking place in a tracking error signal and focus error signal is removed to accurately control the tracking and focus of an optical head.

Abstract: The method and apparatus for copy protecting an optical disk records test data, including modified first signals, on an optical disk such that, when reproduced, random ones of these modified first signals are reproduced as second signals. Both the first and second signals represent data having at least two zeros between successive ones. The method and apparatus for optical disk authentication and reproduction creates a statistical version of the test data through repeated reproduction of the test data. If the test data matches references data, possibly recorded on the optical disk as well, the optical disk is authenticated. Once authenticated, reproduction of the optical disk is permitted. If the test data forms part of the data for reproduction, then the statistical data is output as the reproduced data.

Abstract: An optical reproduction apparatus includes a light source which irradiates irradiation light onto a recording medium, the irradiation light being reflected by the recording medium to produce reflection light, a modulator which repetitively pulse modulates the irradiation light to produce irradiation light pulses, a photodetector which detects reflection light from the recording medium at more than two timings during each of the irradiation light pulses, and outputs detection signals respectively representative of the reflection light detected at the more than two timings during each of the irradiation light pulses, and an operation circuit which performs an operation between the detection signals outputted from the photodetector during each of the irradiation light pulses.

Abstract: Device and method for detecting a non-writable region of an optical recording medium, wherein a read channel 1 signal and a read channel 2 signal are sliced at respective slice levels to produce header mask signals, and a header region which is a non-writable region is determined for the header mask signal taking the slice levels and written/unwritten regions ion the disk, whereby permitting stabilization of servos because servo error signals, such as a tracking error signal, and a focus error signal can be held exactly at a header region even if the servos are not stable, that prevents deterioration of a data quality in writing and reading, and permitting to shift an optical pickup to a desired position and accurate measurement of an amount of eccentricity because there is no influence of the header in a track jump and a disk eccentricity measurement.

Abstract: A recording apparatus generates a first pulse (EQEFM signal) in accordance with recording data such as an EFM signal. A second pulse (first overdrive pulse) to be combined with substantially the leading edge of the first pulse is generated. A third pulse (end overdrive pulse) to be combined with substantially the trailing edge of the first pulse is generated. The first, second, and third pulses are combined to synthesize a driving pulse, and the driving pulse is supplied to a laser unit. At least one of the first, second, and third pulses is controlled so that one of the level and the pulse duration thereof is varied in accordance with the length of formed pits and lands.

Abstract: A nonlinearity compensation circuit is disclosed which includes an inverse hyperbolic function generation circuit for converting differential currents corresponding to input signals in+ and in− into differential voltages which increase in proportion to an inverse hyperbolic function, an offset provision circuit for providing an offset corresponding to control signals c+ and c− to the differential voltages outputted from the inverse hyperbolic function generation circuit and a hyperbolic function generation circuit for converting the differential voltages to which the offset has been provided by the offset provision circuit into signals which increase in proportion to a hyperbolic function and outputting the resulting signals as output signals out+ and out−. Consequently, compensation for the nonlinearity such as second order distortion can be performed for the read signal from a recording medium.

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: An optical recording device comprises: a basic pulse generator 60 including a starting-end pulse generation circuit 2, a burst gate generation circuit 4, and an end pulse generation circuit 6; a data-length detector 61 including a front mark detector 40, a front space detector 41, a recording mark detector 42, a back space detector 43 and a back mark detector 44; a timing controller 62 including a starting-end pulse selecting circuit 14, a starting-end starting position setting circuit 15, a starting-end pulse delaying circuit 19, an end pulse selecting circuit 21, an end starting position setting circuit 35 and an end pulse delaying circuit 25; a pulse synthesizer 63 including an AND gate 27 and an OR gate 36; and a laser driver 64 including an erasing current source 32, a recording current source 33, and a switch 34.

Abstract: When a buffer underrun decision circuit decides that a buffer underrun is about to occur, data recording on the disk is interrupted by a recording control circuit. On the other hand, when the buffer underrun decision circuit determines that a buffer underrun situation has been avoided, data recording is resumed by the recording control circuit. At this time, data recording is resumed from a position of the disk which is continuous to data recorded by the time the data recording was interrupted, thereby recording new data continuous to the last recorded data.

Abstract: An information recording at a high density to an information recording medium and a proper reproduction of information which has been recorded on the information recording medium at a high density are realized. Optical characteristics of an information recording medium are measured and information regarding the measured optical characteristics is previously recorded in a proper area on the information recording medium. When an information recording system records information to the information recording medium on which the information regarding the optical characteristics has been recorded, the information regarding the optical characteristics is read and a proper information recording state is adjusted on the basis of the information regarding the optical characteristics, thereby allowing the information recording to be performed.

Abstract: The invention relates to an optical disc for recording data at a constant density, so called CLV (Constant Linear Velocity) or at zoned CLV. The disc has headers distributed along the disc on regular angular positions, a so called CAV (Constant Angular Velocity) pattern subdividing the track in track portions for recording an amount of data proportional to the radical position of the track portion concerned. Address information included in the headers is provided at the data density, which is CLV. The apparatus comprises header detection means for detecting the headers at the CAV locations, and for recovering position information from the headers at CLV density. Data sectors do not start at headers and are not fitted regularly between the headers, but start and stop at arbitrary positions which are calculated from the known amounts of data recordable in the track portion.

Abstract: Within a sub-code to be recorded in a recording medium, the physical characteristics of the recording medium are recorded. This enables a recording apparatus or a reading apparatus to easily and correctly determine the physical characteristics of the recording medium by reading the sub-code. The physical characteristic information includes information concerning the material, the disc type, the linear velocity, the track pitch, the moment of inertia, and the size/configuration of the recording medium. It is thus possible to easily and correctly determine the physical characteristics of the disc (or unit area) while maintaining the compatibility with known recording media.

Abstract: On an optical disk medium according to the present invention, address information is recorded along a wobbling track groove 2. The track groove 2 is made up of a plurality of unit sections 22, 23. Each of these unit sections 22, 23 has side faces that are displaced periodically in a disk radial direction. This displacement oscillates at a single period in a tracking direction. However, the displacement pattern differs depending on “each bit of address information (subdivided information)” allocated to each of the unit sections 22, 23.

Abstract: An optical disk includes a plurality of tracks that are arranged in a predetermined number of zones. Each track is divided into a plurality of sectors. The sector number is different in each zone. The sector increases in number moving outwardly on the disk. The optical disk also includes a format marking. The format marking includes a sector field for each sector. The format marking is erasably recorded.

Abstract: When recording marks having various lengths are recorded to represent information on a magneto-optical recording medium, a mark length-correcting circuit is used to correct a mark length nT with a mark length correction amount Lc determined for each mark length so that the recording is performed with a shorter mark length nT′=nT−Lc. When reproduction is performed on the magneto-optical recording medium, an appropriate reproducing light power and an appropriate reproducing magnetic field intensity can be easily selected for any recording mark having any length. Thus, the reproducing power margin is widened. The recording method is effective on a magneto-optical recording medium of the MAMMOS type comprising a recording layer and a reproducing layer, in which the light and the magnetic field are applied during the reproduction to transfer a magnetic domain from the recording layer to the reproducing layer in a magnified form.

Abstract: An optical disk unit presets a value &thgr;1 which prescribes an optimum recording pulse width of a light source for a case where the optical disk is rotated at a predetermined linear velocity on a track located at a predetermined radial position on the optical disk, and an optimum power ratio &Dgr;P of an extra pulse at a leading portion of the recording pulse where power is increased. Information is recorded on the optical disk while controlling a light emission waveform of the light source based on a value &thgr;1 (v) which prescribes the recording pulse width, a power ratio &Dgr;P(v) and an optimum recording power Pwo(v) which are successively calculated.

Abstract: Methods for the recording of data to an optical media are provided. In one example, a method includes the determining of the length of a single audio file. A test burn is then performed in which all of the operations required to record the single audio file to optical media are performed except the actual transfer of data to the optical media. During the test burn, the amount of time required to decode the single audio file is measured, and then a codec decoding factor is calculated. The codec decoding factor is equal to the length of the single audio file divided by the amount of time required to decode the single audio file. The codec decoding factor is used to set the recording speed of a selected optical recording device to avoid buffer under-run.

Abstract: An optical disc in a sample servo format applicable to high density recording in which a control track area is formed without reducing format efficiency of a rewritable track area and an optical disc device that can read out control information in a short time with a simple circuit configuration are provided. For this purpose, in the optical disc, a space of a predetermined length where emboss prepits do not exist is arranged for each segment in the control track area, following a data area where control data are recorded by emboss prepits as a clock mark, wobble marks and an address mark.

Abstract: A data storage system achieves improved bandwidth efficiency using a modulated recording signal, channel linearization, and a compressor circuit for compressing peak amplitude of the recording signal. In a preferred embodiment, quadrature amplitude modulation and demodulation is utilized. Another embodiment achieves improved bandwidth efficiency using a recording medium having a substantially rectangular magnetic flux versus magnetic field intensity hysteresis characteristic and a substantially rectangular Kerr rotation versus magnetic field intensity hysteresis characteristic. Yet another embodiment achieves improved bandwidth efficiency using a storage medium having a substantially abrupt flux transition.

Abstract: An optical disc has an information recording portion. The information recording portion has a spiral of a groove, and land portions located between portions of the groove which neighbor each other as viewed in a disc radial direction. Auxiliary information used when an information signal is recorded on and reproduced from the groove is previously recorded on the land portions. The auxiliary information is represented by pre-pits provided in the land portions. The information recording portion is divided into a plurality of zones as viewed in the disc radial direction. In each of the zones, at least one of two sides of the groove wobbles at a fixed frequency in accordance with a constant angular velocity system. In each of the zones, phases of wobbles of respective neighboring portions of the groove are equal to each other.

Abstract: An optical information recording apparatus, an optical information recording method, and an optical information recording medium that enable information signals to be recorded precisely by determining recording conditions such as recording power, edge positions of recording pulses, and the like suitably before recording information signals. An edge test signal generation circuit supplies a test signal for optimizing edge positions of recording pulses. In order to suppress the variation in intervals between edges due to mark distortion caused by overwriting, test recording is carried out using this test signal in a plurality of sectors on the optical information recording medium with a test recording start point being shifted at random in each sector by a recording start point shifting circuit.

Abstract: An optical information recording apparatus, an optical information recording method, and an optical information recording medium that enable information signals to be recorded precisely by determining recording conditions such as recording power, edge positions of recording pulses, and the like suitably before recording information signals. An edge test signal generation circuit supplies a test signal for optimizing edge positions of recording pulses. In order to suppress the variation in intervals between edges due to mark distortion caused by overwriting, test recording is carried out using this test signal in a plurality of sectors on the optical information recording medium with a test recording start point being shifted at random in each sector by a recording start point shifting circuit.

Abstract: An optical information recording apparatus, an optical information recording method, and an optical information recording medium that enable information signals to be recorded precisely by determining recording conditions such as recording power, edge positions of recording pulses, and the like suitably before recording information signals. An edge test signal generation circuit supplies a test signal for optimizing edge positions of recording pulses. In order to suppress the variation in intervals between edges due to mark distortion caused by overwriting, test recording is carried out using this test signal in a plurality of sectors on the optical information recording medium with a test recording start point being shifted at random in each sector by a recording start point shifting circuit.

Abstract: An information recording method, in which when new digital information is employed to update a part of old digital information that has been divided into ECC blocks and stored on an information recording medium, the latest update position for the old digital information that is to be updated is detected based on the volume of the data of the new digital information. A predetermined volume for the old digital information that has been stored sequentially following the latest update position detected is read, and then, at least a part of the old digital information that has been read is recorded after the new digital information is recorded, so that the destruction of data that should not be rewritten can be prevented at the portion whereat the old digital information is coupled with the new digital information. As a result, the deterioration of the error correction capability for the coupled portion can be reduced.

Abstract: An information recording apparatus for recording data by applying energy to a recording medium to form thereon local physical changes of the medium includes a space length discriminating unit for discriminating a space length of a space in a channel data sequence when data is recorded, and a recording energy irradiating unit for generating at least two recording waveforms when successive spaces having a same length in the channel data sequence are recorded, in accordance with results discriminated by the space length discriminating unit. The at least two recording waveforms may be at least two mutually different recording waveforms.

Abstract: An EET (“eight-to-ten”) method has been proposed for two-dimensional spatial encoding of information stored in two- or three-dimensional, in particular fluorescent optical carriers. The method specifically ensures the same writing density as DVD carriers with EFM (“eight-fourteen modulation”) modulation code but for 0.8×0.4&mgr; information pit (fluorescent mark), i.e. as in CD data carriers. The larger—as compared to the DVD format—pit size enables a simpler technology for manufacturing fluorescent multilayer carriers, for instance of ROM type, and a stronger fluorescent signal in reading. The high writing density is ensured through virtually 100% filling of the information layer area with fluorescent marks in a gap-free manner. In addition, this allows application of the parallel data reading procedure and a ten-fold higher reading speed than in DVD systems. Increasing the size of the channel bit to 0.4 &mgr;m—which is 1.

Abstract: A system and method are disclosed for generating a transition in a laser control signal at a precise point in time. A write strategy processor is configured to input a sequence of data and to determine a transition in a laser control signal from the sequence of data. The transition is specified by a number of pulse clock units and a delay. A write pulse generator is configured to input the number of pulse clock units and the delay and to generate a transition by creating a signal having a transition at the time specified by the number of pulse clock units and delaying the transition by the specified delay.