Abstract: 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”.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: HMW demodulation is effected more reliably with a simple configuration. A reproduced wobble signal is caused to pass through a BPF previously set to a center frequency 2fwob, to thus enhance a second harmonic component. The wobble signal having passed through a BPF is multiplied by a second harmonic signal. Subsequently, a peak envelope signal and a bottom envelope signal of the multiplied wobble signal are extracted. The peak envelope signal is discriminated from the first preset threshold value. A result of this discrimination becomes a signal used for detecting an HMW[1] wobble waveform. Similarly, a bottom envelope signal is discriminated from a preset second threshold value. The result of discrimination becomes a signal used for detecting an HMW[0] wobble waveform.

Abstract: 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”.

Abstract: An inspection apparatus for inspecting a phase modulated wobble track of an optical disk is provided. A radial push-pull signal (a wobble signal) of an optical disk is supplied to a low pass filter where a phase boundary portion of the wobble signal is smoothed, and then binarized by a binarizer and supplied to a time interval analyzer. The time interval analyzer analyzes a period of the binary wobble signal to extract two peak values T1 and T2 thereof. An operation device computes a difference value of the two periods T1 and T2 and a standard deviation of each peak, and compares each computed value to a threshold value for simultaneously evaluating CNR and a phase shift. The low pass filter and the binarizer may be incorporated into an optical disk apparatus for smoothing the phase boundary portion of the reproduced wobble signal.

Abstract: 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.

Abstract: 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.

Abstract: 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 ? value obtained as a result of reproduction of the test data.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: HMW demodulation is effected more reliably with a simple configuration. A reproduced wobble signal is caused to pass through a BPF previously set to a center frequency 2fwob, to thus enhance a second harmonic component. The wobble signal having passed through a BPF is multiplied by a second harmonic signal. Subsequently, a peak envelope signal and a bottom envelope signal of the multiplied wobble signal are extracted. The peak envelope signal is discriminated from the first preset threshold value. A result of this discrimination becomes a signal used for detecting an HMW[1] wobble waveform. Similarly, a bottom envelope signal is discriminated from a preset second threshold value. The result of discrimination becomes a signal used for detecting an HMW[0] wobble waveform.

Abstract: An optical disk device which performs data recording and reproduction with regard to an optical disk on which pre-pit information for specifying an address is formed. An optical disk is irradiated with a laser beam and return light from the optical disk is detected by two photodetectors which are disposed in the radial direction. After the levels of two signals from the photodetectors are limited, a difference between these signals is calculated. Due to the limitation of the levels, noise during the recording power period is removed so that pre-pit information during the reproducing power period, namely during the space period, is extracted. Further, by calculating a difference between the two signals from the photodetectors, pre-pit information during the recording power period is extracted.

Abstract: An inspection apparatus for inspecting a phase modulated wobble track of an optical disk is provided. A radial push-pull signal (a wobble signal) of an optical disk is supplied to a low pass filter where a phase boundary portion of the wobble signal is smoothed, and then binarized by a binarizer and supplied to a time interval analyzer. The time interval analyzer analyzes a period of the binary wobble signal to extract two peak values T1 and T2 thereof. An operation device computes a difference value of the two periods T1 and T2 and a standard deviation of each peak, and compares each computed value to a threshold value for simultaneously evaluating CNR and a phase shift. The low pass filter and the binarizer may be incorporated into an optical disk apparatus for smoothing the phase boundary portion of the reproduced wobble signal.

Abstract: 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.