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: A recording waveform generation circuits processes a data signal in synchronization with a prescribed delay clock signal selectively output from a selector in order to generate a recording waveform signal. A selection control section controls selection operation of the selector not only when a record/non-record signal indicates a non-recording state, but also when the record/non-record signal indicates a data recording state as well as a mark space circuit detects a space period.

Abstract: An apparatus of forming an evaluation signal used in adjusting focus bias and adjusting skew of a disk drive in which phase error information between a phase of a read data signal and a phase of a clock signal formed in synchronism with the read data signal, is detected, the phase error signal is converted into an analog signal and is outputted as an evaluation signal having a signal level in accordance with the phase error amount and the evaluation signal is inputted after A/D conversion to a portion for carrying out signal quality evaluation by using the evaluation signal whereby pertinent signal evaluation can be carried out by a simple constitution.

Abstract: A device for demodulating position information that is recorded as track wobbling in a record medium by a BPSK scheme includes a carrier-wave-generation circuit which derives a carrier wave from a wobbling signal obtained from the record medium, a phase-adjustment circuit which generates a phase-comparison signal having a 90° phase difference relative to the carrier wave, a multiplier which multiplies the wobbling signal and the phase-comparison signal to supply a product signal, and a detection circuit which detects a phase error of the carrier wave introduced by the carrier-wave-generation circuit by detecting the phase error between the wobbling signal and the phase-comparison signal based on the product signal.

Abstract: An apparatus of forming an evaluation signal used in adjusting focus bias and adjusting skew of a disk drive in which phase error information between a phase of a read data signal and a phase of a clock signal formed in synchronism with the read data signal, is detected, the phase error signal is converted into an analog signal and is outputted as an evaluation signal having a signal level in accordance with the phase error amount and the evaluation signal is inputted after A/D conversion to a portion for carrying out signal quality evaluation by using the evaluation signal whereby pertinent signal evaluation can be carried out by a simple constitution.

Abstract: A receiving apparatus including a receiving circuit for receiving data synchronized with a predetermined clock signal; a data detection circuit, for detecting values of at least three bits of received data in a cycle defined by a period started from a desired position and corresponding to a cycle of the clock signal; and a selecting circuit for selecting from the received data with the detected values the received data with the least change of the value with respect to the received data of values detected immediately before and after substantially in each cycle and outputting the value of the received data.

Abstract: A disk is rotated by a spindle motor. The spindle motor is controlled such that the disk is rotated at a constant linear velocity (CLV) against a recording head. A signal read by a reproducing head is stored in a time-axis expansion and compression memory. When a signal is written into the time-axis expansion and compression memory and when a signal is read therefrom, the time axis of a signal read by the reproducing head is compressed or expanded according to the track position of the reproducing head so as to match the time axis obtained at a constant linear velocity.

Abstract: This invention prepares two control voltage to be input to a VCO circuit. The first control voltage is used to continuously change the oscillation frequency of the VCO circuit. The second control voltage is used to continuously change the first control voltage/oscillation frequency characteristics. The invention also includes a phase detecting circuit for comparing the phase of the data read from a disk with that of the output from the voltage-controlled oscillator, a frequency detecting circuit for comparing the frequency of the data read from the disk with that of the output from the voltage-controlled oscillator, a first filter circuit for equalizing signals representing the detection results obtained by the phase detecting circuit and the frequency detecting circuit, and a second filter circuit for extracting only a low-frequency component from the output from the first filter circuit. The output from the first filter circuit is used as the first control voltage.

Abstract: Address information indicative of a certain recording/reproduction position is recorded twice (first address, second address) in an optical disk. Second phase control means makes sampling timings for digitizing the first address have optimal phases. Third phase control means makes sampling timings for digitizing the second address have optimal phases. The second and third phase control means are formed with different circuits, respectively.

Abstract: Thermal stress is prevented from accumulating on a disk recording medium. Data to be recorded is divided into 32-kilobyte clusters, and a front link area and a back link area, whose lengths are randomly changed, formed of a total of 8 frames are added before and after the clusters. Then, the data is recorded on a predetermined area of a disk on the basis of address data prerecorded on the disk.

Abstract: An optical disc has a plurality of tracks for recording information represented as marks and spaces between the marks. The marks are formed by an optical beam modulated by a plurality of drive pulses (202) where a number of the drive pulses is determined according to a length of a mark part in the original signal to be recorded to the track. The optical disc has a control information recording area (2504) for storing a first pulse position Tu value indicative of rising edge of the first drive pulse for determining a start position of a mark to be recorded, and a last pulse position Td value indicative of falling edge of the last drive pulse for determining an end position of a mark to be recorded.