摘要:
A hard disk drive is disclosed in which the disk has tracks each divided into alternating data sectors and servo sectors, with the control data such as track addresses on the servo sectors being normally recorded more stably than the main data on the data sectors. In order to obtain read pulses representative of the peaks of the output waveform of a transducer, this waveform is directed on one hand into a differentiator circuit and thence into a wave shaping circuit for the provision of data pulses which rise and decay in synchronism with the peaks of the transducer output waveform. On the other hand, the transducer output waveform is sent into a gate pulse circuit, in which the waveform is compared with a reference signal in order to provide gate or window pulses. A logic circuit is provided for ascertaining whether the data pulses rise and decay within the durations of the gate pulses and, if they do, for producing read pulses indicative of the rises and decays of the data pulses. The duration of the gate pulses is made shorter for recovery of the control data than for main data recovery, with a view to more precise detection of the peaks of the transducer output waveform representative of the control data.
摘要:
A tilt detection system includes an optical disk having a series of data recorded therein, the series of data having a pulse width smaller than the minimum pulse width of data recorded in an ordinary optical disk; a reproducing part reproducing a signal from the optical disk by emitting a light beam onto the optical disk; and a tilt detecting part detecting a tilt of the light beam with respect to the optical disk based on a reproduced RF signal provided by the reproducing part when the series of data having the smaller pulse width is reproduced.
摘要:
An optical disk apparatus capable of adjusting a focus servo and the like by precisely detecting a jitter amount. Light reflected from an optical disk is converted into an RF signal in an optical pickup and amplified by an RF amplifier before being supplied to an equalizer. The boost amount of the equalizer is set to zero during adjustment and set to a predetermined finite value (e.g., +20 dB) during normal recording and reproducing. By first setting the boost amount to zero, the delay characteristics of the RF signal from 3T to 11T are flattened such that an accurate jitter amount can be determined based on the integrated value of the phase differences of 3T to 11T, thereby allowing the optical pickup to be adjusted so as to minimize the jitter amount.
摘要:
A tilt detection system includes an optical disk having a series of data recorded therein, the series of data having a pulse width smaller than the minimum pulse width of data recorded in an ordinary optical disk; a reproducing part reproducing a signal from the optical disk by emitting a light beam onto the optical disk; and a tilt detecting part detecting a tilt of the light beam with respect to the optical disk based on a reproduced RF signal provided by the reproducing-part when the series of data having the smaller pulse width is reproduced.
摘要:
An optical disk apparatus for enhancing time resolution of an RF sum signal. A reproduction sum signal (a signal A+a signal D) on the leading side and a reproduction sum signal (a signal B+a signal C) on the following side, which have been output from a four-quadrant photodetection section of an optical pickup, are supplied to first and second A/D converters. The first A/D converter samples a signal in accordance with a first clock signal CLK, and the second A/D converter samples a signal in accordance with a second clock signal CLK. The first and second clock signals CLK are out of phase with each other. By means of a phase difference between the clock signals, a phase difference between the leading-side reproduction signals and the following-side reproduction signals is compensated for. The phase difference between the first and second clock signals CLK is adjusted such that the quality of a reproduction signal, such as jitter, an error rate, or the like, is optimized.
摘要:
An optical disk drive sets optimum recording power responsive to recording linear speed. When data are recorded in an optical disk, data are managed for each recording unit block (RUB). An APC area is provided at the top of RUBs, and OPC is performed by use of the APC area, whereby optimum recording power responsive to recording linear speed is set. Tentative optimum recording power responsive to recording linear speed is set, and test data are written, for a try, in the APC area at recording power that is determined by increasing or decreasing the tentative optimum recording power by a trace amount. The optimum recording power is set in according with a β value obtained as a result of reproduction of the test data.
摘要:
A demodulation circuit accurately demodulates a wobble signal of an optical disk without being affected by a phase shift induced by crosstalk. An A-D converter subjects wobble signal reproduced from an optical disk to A-D conversion and feeds a result of conversion to a zero-crossing detection circuit. The zero-crossing detection circuit detects zero-crossing points of the wobble signal. A sinusoidal wave generation circuit generates a sinusoidal wave by means of sequentially connecting sinusoidal wave elements whose periods are each equal to a time interval between zero-crossing points. A multiplier multiplies an original wobble signal by a sinusoidal wave signal. A slicer detects an HMW-modulated portion of the wobble signal, and another slicer detects an MSK-modulated portion of the wobble signal.
摘要:
An optical disk apparatus for enhancing time resolution of an RF sum signal. A reproduction sum signal (a signal A+a signal D) on the leading side and a reproduction sum signal (a signal B+a signal C) on the following side, which have been output from a four-quadrant photodetection section of an optical pickup, are supplied to first and second A/D converters. The first A/D converter samples a signal in accordance with a first clock signal CLK, and the second A/D converter samples a signal in accordance with a second clock signal CLK. The first and second clock signals CLK are out of phase with each other. By means of a phase difference between the clock signals, a phase difference between the leading-side reproduction signals and the following-side reproduction signals is compensated for. The phase difference between the first and second clock signals CLK is adjusted such that the quality of a reproduction signal, such as jitter, an error rate, or the like, is optimized.
摘要:
A demodulation circuit accurately demodulates a wobble signal of an optical disk without being affected by a phase shift induced by crosstalk. An A-D converter subjects wobble signal reproduced from an optical disk to A-D conversion and feeds a result of conversion to a zero-crossing detection circuit. The zero-crossing detection circuit detects zero-crossing points of the wobble signal. A sinusoidal wave generation circuit generates a sinusoidal wave by means of sequentially connecting sinusoidal wave elements whose periods are each equal to a time interval between zero-crossing points. A multiplier multiplies an original wobble signal by a sinusoidal wave signal. A slicer detects an HMW-modulated portion of the wobble signal, and another slicer detects an MSK-modulated portion of the wobble signal.
摘要:
There is provided an optical disk device which quickly inspects the presence or absence of a defect in an optical disk in order to ensure that it can be played back on various types of optical disk devices. A detection unit uses signals supplied from a playback unit to detect defects from each of an RF signal, a focus error signal, and a tracking error signal. A CPU stores positions of the defects in a memory. The playback unit plays back data while degrading playback conditions at the positions of the defects . The detection unit detects an error rate of the played-back data, and finally determines whether the optical disk is “OK” or “NG”.