Abstract: The waveform equalizing device includes: an FIR filter for generating an equalized signal pattern y(i, n) on the basis of equalization of a waveform of the reproduced signal pattern u(i, n); a Viterbi decoding circuit for detecting a path metric difference s(n) between a correct path determined as a survivor path and an error path which fails to survive the correct path in Viterbi decoding based on the equalized signal pattern y(i, n); a target register for setting a target value ds for the path metric difference s(n); and a tap coefficients update circuit for adapting the equalization according to an error of the detected path metric difference from the target value. The tap coefficients update circuit adapts equalization properties so that the mean square error is minimized, thereby achieving a satisfactory result in lowering the error rate.

Abstract: In order to provide an optical recording condition setting method which reduces effects from uneven properties of a rewritable or recordable optical disk and an optical recording/reproducing device, and to provide an optical recording/reproducing device which executes the method, (i) a test writing is carried out with respect to an optical disk under various settings of recording-power parameters for use in forming a shortest record-mark (S1 to S3), (iii) a test pattern used in the test writing is reproduced (S4), and then (iv) recording-power parameters that result in a good quality of reproduced signals are selected (S5).

Abstract: An optical disk has a recording track constituted by sectors arranged in a concentric or spiral form. Each sector is divided into segments, and each segment includes a data field where data is recorded and a clock mark field having a different light reflectance from that of the data field. The data field in the sector has synchronization patterns S. Hence, a highly reliable optical disk, optical reproduction device, and optical recording device can be offered that are capable of performing recording and reproduction even if a clock mark is defective due to a flaw.

Abstract: A recording pulse condition for obtaining a reproduction result which fulfills predetermined signal quality is sought by performing testwrite and reproduction after uniformly changing predetermined recording pulse conditions corresponding to all mark lengths (S1, S2). If good result is not obtained, a recording pulse condition for obtaining a reproduction result which fulfills predetermined signal quality is sought by performing testwrite and reproduction after changing a predetermined recording pulse condition corresponding to at least one mark length (S4, S5). Then, a recording pulse condition is determined (S3). Thus provided are method and apparatus for efficiently setting such a recording condition that can reduce the influence of difference in characteristics of writable optical disks and difference in characteristics of optical recording and reproducing apparatuses, and to provide a recording and reproducing apparatus.

Abstract: An optical reproduction apparatus in accordance with the present invention has a gain control circuit for controlling a gain of an amplifier circuit which amplifies a reproduction signal in accordance with amplitudes of the reproduction signal from an optical recording medium. The amplitude is sent to a power control calculation circuit which controls the reproduction power of a light beam in accordance with the amplitude. The gain control circuit has a slower response speed than that of the power control circuit at least during a period when the power control circuit controls the reproduction power. This allows to provide an optical reproduction apparatus that can realize the stable reproduction power and automatic gain control even to the unevenness of the amplitudes of the reproduction signal.

Abstract: An optical disc and an optical disc drive for the optical disc are provided which are suitable for recording data with a high density. The optical disc D uses both lands and grooves as recording tracks. Each of the tracks consists of one address segment and forty five data segments. The address segment is wobbled at one side thereof. Each of the data segments is a DC groove. The address segment records an address information including a sync signal, frame address, track address and CRC, a tilt pattern and a clock mark. The clock mark is adapted to reflect laser beam in one amount before the mark and in another amount after the mark. The tilt pattern has a different track pitch from those in other areas. The data segments record data magneto-optically.

Abstract: In order to provide an optical disk of a small radius suitably used in recording/reproducing data at a high density and an optical disk apparatus capable of according/reproducing information into/from such an optical disk, the optical disk of the present invention uses both the grooves and lands as recording tracks. each recording track is divided into a plurality of sectors each including an address segments ASG 0 and ASG 1, and data segments DSG 0-DSG 52. The address segment 0 (ASG 0) and address segment 1 (ASG 1) respectively have wobbled areas in the opposite side walls, by which the address information is recorded. The data segments are non-wobbled DC grooves. Further, each segment is provided with a clock mark.

Abstract: A magneto-optical disk recording and reproducing device, which carries out recording and reproducing for a magnetic super-resolution magneto-optical disk including a recording layer and reproducing layer, has a recording data processing circuit which records long recording marks at different positions between adjacent tracks in a radius direction, each of the long recording marks being larger in diameter than an aperture formed on the reproducing layer by projecting thereon the light beam. According to this arrangement, it is possible to continuously reproduce a data recording area with high accuracy and optimum reproducing power without being affected by adjacent tracks.

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: In an optical reproducing device in accordance with the present invention, based on an error rate used in a test read for determining an optimal reproducing power, the value of an error rate corresponding to the maximum burst error which can be corrected by an error correction circuit is obtained. With this structure, an error caused when reproducing power deviates from the optimal reproducing power determined by the test read due to an control error can be corrected by the error detection circuit.

Abstract: A recording-reproducing device includes a power control pattern generating circuit for generating a power control pattern to be used for control of a reproducing power of a semiconductor laser, a phase adjusting pattern generating circuit for adjusting a phase of a reproducing clock to be used upon reproduction of the power control pattern, a synchronous pattern generating circuit for generating a synchronous pattern to be recorded immediately before the phase adjusting pattern, and a recording data selecting circuit. The recording data selecting circuit consecutively selects an output of the phase adjusting pattern generating circuit, an output of the synchronous pattern generating circuit, and an output of the power control pattern generating circuit, and records these outputs in a front part of each sector of a magneto-optical disk.

Abstract: A signal evaluation device for evaluating a decoded signal of maximum likelihood decoding includes: a differential metric circuit for finding differential metrics; comparators for judging whether a difference of differential metrics exceeds a predetermined threshold; counters for counting respective output pulses of the comparators; and a controller for finding the probability of the differential metrics falling at or below the predetermined threshold, based on the number of measured samples and the number of samples counted by the counters, and processing the probability by arithmetic operations so as to obtain an index of signal evaluation. With this arrangement, signal evaluation devices for evaluating a recording medium or a recording medium driving device can have a simpler structure and can perform evaluations in a plurality of PR modes.

Abstract: A magneto-optical disk recording and reproducing device, which carries out recording and reproducing for a magnetic super-resolution magneto-optical disk including a recording layer and reproducing layer, has a recording data processing circuit which records long recording marks at different positions between adjacent tracks in a radius direction, each of the long recording marks being larger in diameter than an aperture formed on the reproducing layer by projecting thereon the light beam. According to this arrangement, it is possible to continuously reproduce a data recording area with high accuracy and optimum reproducing power without being affected by adjacent tracks.

Abstract: An optical reproducing device is provided with predetermined length mark signal measurement means which measures amplitude values of a 2T mark and an 8T mark, which are a short reproducing power control mark and a long reproducing power control marks, respectively, from information data recorded in an magneto-optical disk. Reproducing power of a light beam is controlled by a laser power control circuit, based on the amplitude values of the 2T mark and the 8T mark. The predetermined length mark signal measurement means detects a specific pattern including the 2T mark from a bit arrangement pattern of the information data, and measures the amplitude value of the 2T mark correponding only to the 2T mark included in the specific pattern. This structure can provide an optical reproducing device which can maintain the reproducing power at an optimum value and reduce the probability of reading errors, without reducing the utilization ratio of an optical recording 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: A magneto-optical disk reproducing device includes a clock producing circuit, which, on the basis of a reproducing signal from recorded marks recorded in a magneto-optical disk, produces a timing offset from peak positions of the reproducing signal; an A/D converter, which samples the reproducing signal in accordance with the timing, and outputs a reproducing signal quantity; and a short mark signal quantity averaging circuit and a long mark signal quantity averaging circuit, each of which averages a plurality of reproducing signal quantities. When projecting a light beam onto a magneto-optical disk, the magneto-optical disk reproducing device controls light quantity of the light beam on the basis of a ratio between the respective values outputted by the foregoing averaging circuits.

Abstract: An optical disc and an optical disc drive for the optical disc are provided which are suitable for recording data with a high density.

Abstract: A reproducing light quantity control method for an optical memory device includes the steps of (1) recording test data on an optical recording medium; (2) reproducing the test data recorded on the optical recording medium by changing a reproducing light quantity in a plurality of light quantity values; (3) measuring a quality value and a signal quantity of each of a plurality of reproducing signals from the test data; (4) selecting an optimum reproducing signal quantity from a plurality of reproducing signal quantities in accordance with quality values of the plurality of reproducing signals so as to decide a target value of reproducing signal quantity; and (5) recording the target value on a target value recording region of the optical recording medium. This method reduces the time required to obtain a target value of a reproducing signal quantity and speeds up an operation from installing of the optical recording medium to finishing of preparation for recording and reproducing.

Abstract: An optical recording device includes a recording condition determining section for determining recording conditions for a track by performing test writing with respect to the track which is, for example, either a land or a groove of a magneto-optical disk, a recording condition computing section for performing computation in accordance with computation-use information based on the recording conditions for the track so as to determine recording conditions for the other track, a track switch section for switching tracks to be used for test writing, and a computation-use information managing section for correcting the computation-use information based on respective results of test writing before and after the switch, thereby determining recording conditions for one of the tracks in short time by computation, while, because the computation-use information is corrected based on the results of test writing, improving accuracy in recording conditions obtained by computation.

Abstract: In an optical reproducing device in accordance with the present invention, based on an error rate used in a test read for determining an optimal reproducing power, the value of an error rate corresponding to the maximum burst error which can be corrected by an error correction circuit is obtained. With this structure, an error caused when reproducing power deviates from the optimal reproducing power determined by the test read due to an control error can be corrected by the error detection circuit.