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”.
摘要:
In an optical disk drive, running OPC (ROPC) is performed without fail, to thus enhance recording quality. ROPC is performed by use of a remaining portion of an area for APC operation within an APC area of a recording unit (RUB) in a next-generation optical disk such as a blu-ray disk. ROPC is performed by means of tentatively writing test data having a length of 50 T longer than a specified length of data to be recorded; and detecting level B of the amount of light reflected at that time. The APC area is formed from five wobble periods. APC is performed in periods of first two wobbles, and ROPC is performed in remaining three wobble periods.
摘要:
An A/D conversion circuit converts an asymmetric analogue signal into a digital signal. In an A/D conversion circuit of a parallel type, a central value of a reference voltage is adjusted by means of an average of an input analogue signal, such as a reproduced RF signal from an optical disk, or the like. The average value of the input analogue signal is detected by means of a low-pass filter (LPF). Respective comparators compare the input analogue signal with the reference voltage, and encodes a result of comparison by means of an encoder. An A/D conversion characteristic determined by voltage values from a maximum value Vref1 to an average value and another A/D conversion characteristic determined by voltage values from the average value to a minimum value Vref2 become nonlinear, thereby becoming able to address asymmetry of the input analogue signal.
摘要:
In an optical disk drive, running OPC (ROPC) is performed without fail, to thus enhance recording quality. ROPC is performed by use of a remaining portion of an area for APC operation within an APC area of a recording unit (RUB) in a next-generation optical disk such as a blu-ray disk. ROPC is performed by means of tentatively writing test data having a length of 50 T longer than a specified length of data to be recorded; and detecting level B of the amount of light reflected at that time. The APC area is formed from five wobble periods. APC is performed in periods of first two wobbles, and ROPC is performed in remaining three wobble periods.
摘要:
In this optical disk device, a reflected light of a light beam reflected from a pre-pit-formed side of a track wobbled on a disk is detected as a first detection signal. A reflected light of the light beam reflected from the other side of the track is detected as a second detection signal. The first detection signal and/or the second detection signal are/is amplified with a gain(s) so set that a peak value of a wobble signal component of the first detection signal coincides with a bottom value of a wobble signal component of the second detection signal.
摘要:
An optical disc apparatus provided with an automatic power control circuit which controls power of laser light by obtaining a difference between a value detected by a front monitor 6 and a target value individually for reproduction power and for recording power includes: a detector 7 for detecting light reflected from an optical disc, a sample-hold circuit 26 which performs on an output of the detector 7 a sample-hold operation at the timing of the reproduction power; and a microcomputer 29 which computes a reference value from the reflected light of the reproduction power at the timing just before the start of a recording operation after receiving a recording command until opening of a recording gate, and at the time of recording operation an intensity of reflected light on which a sample-hold operation is performed is compared with the reference value to correct a target value of the reproduction power.
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:
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.