Abstract: The invention provides an optical disc device and a method of determining an optimal laser power for data recording by trial recording before recording actual user data even when there are fingerprints in the test track area for the trial recording. The BER (Byte Error Rate) is detected in each recorded sector. If the BER is less than a particular threshold value, the sector is taken as OK (good). Otherwise the sector is taken as NG (no good). While the peak power level is gradually changed or decreased from the power level at which half or more of the plural reproduced sectors are OK, a boundary peak power at which half or more of the sectors become NG is found. Based on the found boundary power, an amount of the optimal peak power is determined.

Abstract: The laser drive device of this invention includes a laser, first and second current sources, a current amplifier, and first and second transistors. When the first transistor is OFF, a first current from the first current source is supplied to the current amplifier, where the current is amplified to generate a laser current to be supplied to the laser. Thus, the laser is turned ON. During this time, the second transistor is ON, allowing a second current to flow from a power supply node into the second current source. When the first transistor is ON, the entire or part of the first current flows into the second current source through the first transistor. This reduces the current supplied to the current amplifier and thus the laser current, resulting in turning OFF the laser. During this time, the second transistor is OFF. The values of the first and second currents are determined by a set current value.

Abstract: The laser drive device of this invention includes a laser, first and second current sources, a current amplifier, and first and second transistors. When the first transistor is OFF, a first current from the first current source is supplied to the current amplifier, where the current is amplified to generate a laser current to be supplied to the laser. Thus, the laser is turned ON. During this time, the second transistor is ON, allowing a second current to flow from a power supply node into the second current source. When the first transistor is ON, the entire or part of the first current flows into the second current source through the first transistor. This reduces the current supplied to the current amplifier and thus the laser current, resulting in turning OFF the laser. During this time, the second transistor is OFF. The values of the first and second currents are determined by a set current value.

Abstract: An optical disc drive usable with discs to which data is continuously recorded and discs having a sector format can quickly resume playback signal output after passing imperfection causing potential reading errors, and plays disc with few read errors. A detection signal generator detects DC level fluctuation in the playback signal read from the disc and generates a detection signal tracking the DC level fluctuation. A selector selects a detection signal or a null signal without valid polarity based on the detection signal generated by the detection signal generator and input to the selector. A clamping unit performs a clamping process to suppress DC level fluctuation in the playback signal based on the detection signal when the selection unit selects the detection signal, and does not perform the clamping process when the selection unit selects the null signal. A signal processor performs specific signal processes based on clamping unit output.

Abstract: A semiconductor laser control method and a semiconductor laser control apparatus allow an outgoing radiation power of a semiconductor laser to be accurately stabilized to a desired value even if a characteristic of the semiconductor laser changes due to temperature variations or deterioration of life. The characteristic of a semiconductor laser is measured by a semiconductor laser characteristic detection unit and a target value is corrected by a target value correction unit based on a threshold current and differential quantum efficiency obtained from the measurement result. A power control unit controls the semiconductor laser by comparing the corrected target value with the output of a power detection unit, making it possible to achieve a desired outgoing radiation power of the semiconductor laser with high accuracy even if the threshold current or differential quantum efficiency of the semiconductor laser changes due to temperature variations or deterioration of life.

Abstract: A semiconductor laser driving apparatus for directing light to an optical disc for recording a recording mark based on a recording current and reproducing the recording mark to generate a reproduction signal. The apparatus includes a reproduction current generation section; a high frequency current generation section for generating a current including a high frequency component for reducing semiconductor laser noise in the reproduction; a recording current generation section, the recording current including a pulse corresponding to the recording mark and including a plurality of multi-pulses; and a current driving section for amplification. The apparatus further includes a filter to attenuate the enhanced high frequency components in the high frequency current and in the enhanced high frequency component; and a switching section for switching the filter so that the enhanced component in the recording current is superposed on at least one of the multi-pulses.

Abstract: A laser power controller detects the temperature and current setting used for the recording power during initial learning or the previous recording operation. When a new recording operation starts, the controller detects the temperature again and compared the detected temperature with the temperature at initial learning or the previous recording to adjust the current setting used for the previous recording power setting and set the initial recording power current of the new recording operation.

Abstract: An optical disc drive usable with discs to which data is continuously recorded and discs having a sector format can quickly resume playback signal output after passing imperfection causing potential reading errors, and plays disc with few read errors. A detection signal generator detects DC level fluctuation in the playback signal read from the disc and generates a detection signal tracking the DC level fluctuation. A selector selects a detection signal or a null signal without valid polarity based on the detection signal generated by the detection signal generator and input to the selector. A clamping unit performs a clamping process to suppress DC level fluctuation in the playback signal based on the detection signal when the selection unit selects the detection signal, and does not perform the clamping process when the selection unit selects the null signal. A signal processor performs specific signal processes based on clamping unit output.

Abstract: The invention provides an optical disc device and a method of determining an optimal laser power for data recording by trial recording before recording actually user data even when there are fingerprints in the test track area for the trial recording. The BER (Byte Error Rate) is detected in each recorded sector. If the BER is less than a particular threshold value, the sector is taken as OK (good). Otherwise the sector is taken as NG (no good). While the peak power level is gradually changed or decreased from the power level at which half or more of the plural reproduced sectors are OK, a boundary peak power at which half or more of the sectors become NG is found. Based on the found boundary power, amount of the optimal peak power is determined.

Abstract: An optical disk is operated in a ZCLV system for generating a stable and precise clock and the operation proceeds with a speed change of a high-speed motor when data is stored with the motor accelerated or decelerated at a high speed to improve accessibility for data storage. The optical disk includes: a disk rotator for rotating the optical disk at an optional number of rotations; a rotation controller for controlling rotation of the optical disk; a wobble extractor for extracting wobbling on the track of the optical disk; a clock extractor for extracting a clock element from the wobbling; a speed detector for detecting a linear speed of the optical disk; and a response switch for switching a response of the clock extractor, in which the response of the clock extractor is switched depending on the linear speed of the optical disk.

Abstract: In a laser power controller, a part of laser beam emitted from a laser diode 1 is detected with a photodetector 2. The operational processor 3 controls a driver 5 so that the light-emitting power of the laser diode 1 has prescribed values, and the driver 5 drives the laser diode 1. The record powers are set beforehand in one or more gap sections existing between record areas, and the operational processor 3 stores the results of the operation in an external memory 4. On recording, the results stored in the external memory 4 are read by the operational processor 3 so as to set the record powers. Thus, the record powers can be set stably even for a fast recording rate.

Abstract: In an magneto-optic disk apparatus which carries out recording, playback, or erasing of data with a single laser beam, recorded data is read simultaneously with a recording or erasing operation to eliminate the time of waiting for the disk to make a turn. A signal separation circuit 7 is provided for a magneto-optic disk apparatus which carries out recording, playback, erasing of data by applying a laser beam through an optical head 2 to a spot on a magneto-optic disk 3. In a recording or erasing operation, a magneto-optic playback signal 6 obtained from reflected light of a recording or erasing beam is input to the signal separation circuit 7 to separate and output the recorded data signal 8 contained in the magneto-optic playback signal 6 to consequently reading a recorded data signal 10 simultaneously with carrying out a recording or erasing operation.