Abstract: Amplifier having input power protection. In some embodiments, an amplifier circuit can include an input node and an output node, and an amplifier implemented between the input node and the output node. The amplifier circuit can further include a bias circuit configured to provide a bias signal to the amplifier. The amplifier circuit can further include a protection circuit configured to generate a detected voltage representative of a peak of a radio-frequency signal present at the input node. The protection circuit can be further configured to enable a protection mode when the detected voltage is greater than a first threshold value and to disable the protection mode when the detected voltage is less than a second threshold value that is less than the first threshold value.

Abstract: Technology for improved data detection using machine learning may include a method in which an analog read signal comprising data read from a non-transitory storage medium of the data storage device is received. The analog read signal is processed into a plurality of digital samples. A digital sample from the plurality of digital samples is classified into a category from a plurality of categories using a machine learning algorithm for at least some of the plurality of digital samples. The plurality of digital samples is then decoded based on at least some of the predicted categories.

Abstract: Technology for improved data detection using machine learning may include a method in which an analog read signal comprising data read from a non-transitory storage medium of the data storage device is received. The analog read signal is processed into a plurality of digital samples. A digital sample from the plurality of digital samples is classified into a category from a plurality of categories using a machine learning algorithm for at least some of the plurality of digital samples. The plurality of digital samples is then decoded based on at least some of the predicted categories.

Abstract: An audio signal processing device includes an audio signal processing unit which performs signal processing on an audio signal, a sound volume setting receiving unit which receives a sound volume set value, and a sound volume measuring unit which measures a sound volume at a listening position. The audio signal processing unit performs a loudness correction which increases a level of the audio signal in a prescribed frequency range as the sound volume set value decreases. The sound volume measuring unit measures sound volumes corresponding to plural respective sound volume set values at the listening position. The audio signal processing unit sets a level adjustment amount to be used in performing the loudness correction based on the sound volume set value received by the sound volume setting receiving unit and the measurement sound volumes of the sound volume measuring unit.

Abstract: A system for digitally equalizing a data channel with heavily ISI-induced signals received after passing a data communication channel using a combination of a linear equalizer and a nonlinear equalizer, which comprises an ADC, for sampling a received signal and converting it to a digital form; a Linear Equalizer for pre-processing said received signal, said Linear Equalizer is adapted to pre-process a first group consisting of echoes/channel taps of the induced ISI, which are not equalized by said nonlinear equalizer, by eliminating the echoes/channel taps of said first group; pre-process a second group consisting of the combination of the entire echoes/channel taps of the induced ISI, by eliminating the echoes/channel taps of said second group; and a nonlinear equalizer for receiving the signals preprocessed by said Linear Equalizer and for further processing said preprocessed signals and eliminating the echoes/channel taps of the induced ISI to be equalized by said nonlinear equalizer, thereby compensating

Abstract: Systems and method relating generally to data processing, and more particularly to systems and methods for utilizing multiple data streams for data recovery from a storage device. As an example, a data processing system is discussed that includes a first read head and a second read head each operable to sense information on a storage medium. A synthesizer circuit is operable to determine a quality metric based upon a signal to noise ratio of a first preamble pattern compared with a signal to noise ratio of a second preamble pattern. A balancing circuit is operable to generate a composite output as a combination of a first data set derived from the first read head a second data set derived from the second read head based at least in part on the quality metric.

Abstract: An optical disk device includes an optical pickup that directs light beams onto a recording surface of an optical disk and receives reflected light, a signal generating unit that generates playback signals based on reflected light received by the optical pickup, an equalizer adjustment unit that performs equalizer adjustment of the playback signals, and an adjustment control unit. The adjustment control unit controls the equalizer adjustment unit so as to perform equalizer adjustment of the playback signals according to the playback signals based on reflected light from a management information area on a recording surface of the optical disk, the management information area including predetermined management information recorded thereon.

Abstract: A method and device for determining frequency error to extend the pull-in range of a timing recovery circuit for a storage device such as an optical disc drive. A code associated with a storage format of the storage device is detected, and the distance between occurrences of the code is determined. The calculated distance is compared with the expected distance to determine the difference. Based on the difference, the frequency error is determined.

Abstract: A frequency detection apparatus and method for generating a stable clock signal synchronized with an input signal and a signal boost filter used in the frequency detection apparatus and method, the frequency detection apparatus includes a signal boost filter filtering out the high frequency component of an input signal and boosting the high frequency component, and a frequency detector receiving an input signal with the boosted high frequency component and a clock signal, detecting a frequency difference between the input signal and the clock signal, and producing a control voltage corresponding to the frequency difference. Accordingly, even when there is a big difference between the frequency of the input signal and an oscillating frequency, a frequency error can be stably detected. Thus, a stable clock signal can be obtained.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is discussed that includes a summation circuit, a data detector circuit, an error feedback circuit, and an error calculation circuit. The summation circuit subtracts a low frequency offset feedback from an input signal to yield a processing output. The data detector circuit applies a data detection algorithm to a derivative of the processing output and provides an ideal output. The error feedback circuit includes a conditional subtraction circuit that conditionally subtracts an interim low frequency offset correction signal from a delayed version of the derivative of the processing output to yield an interim factor. The error calculation circuit generates an interim low frequency offset correction signal based at least in part on the interim factor and a derivative of the ideal output.

Abstract: An audiocassette adapter (10) for coupling a mobile wireless communication station (20) to an audiocassette player, including a cassette head coupling device (12), a cassette adapter insertion detect switch (14), a mobile wireless communication station coupling device (50) having a mobile wireless communication station audio input coupled to the cassette head coupling device, the mobile wireless communication station coupling device having an insertion detect signal output (54) coupled to the cassette adapter insertion detect switch.

Abstract: To determine the optimum amplitude of high frequency signal for the loaded disc with a simple configuration to achieve stable playing performance, there is provided an optical disc device comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling amplitude of the high frequency signal to be superimposed on the drive signal for the light source; the optical disc device being configured to read data on an optical disc loaded therein by a signal outputted from the detector, wherein the controller determines the amplitude of the high frequency signal to be superimposed on the drive signal based on asymmetry of the signal outputted from the detector.

Abstract: A reproducing apparatus includes the following elements. A reproducing head unit irradiates an optical disk with a laser beam to obtain a reproduced signal. An offset cancellation circuit cancels an offset element of the reproduced signal. An automatic gain control circuit adjusts the amplitude of the reproduced signal processed through the offset cancellation circuit. A band switching control unit detects a fingerprint period during which the reproduced signal is affected by a fingerprint on the surface of the optical disk and, for the fingerprint period, switches a frequency band in which the offset cancellation circuit and the automatic gain control circuit function to a higher frequency band than that associated with a non-fingerprint period. A decoding unit decodes the reproduced signal processed through the automatic gain control circuit to output binary data. A data reproduction processing unit performs reproduction processing on the binary data to obtain reproduced data.

Abstract: The invention provides for a method, and related apparatus, of producing a Land Pre-Pit signal during playback of an optical disc and including the steps of obtaining an output signal from an optical detector and from which the Land Pre-Pit signal is to be derived, scaling the said output signal responsive to a determined amplitude of a high frequency crosstalk signal arising during reading of the disc and in a manner so as to increase the said output signal when the Land Pre-Pit identified as corresponding to a mark on the disc, and so as to decrease the output signal when the Land Pre-Pit is identified as corresponding to a space on the disc.

Abstract: Quantization noise due to analog-to-digital conversion may be larger than a noise component of an input signal, and therefore sufficient performance may not be obtained.

Abstract: In an optical disk apparatus, for reproducing information recorded on a recording surface of an optical disk, by setting such a focus condition that a tracking servo-error level comes to be maximum with a reflection light from the recording surface, while irradiating a light beam of a semiconductor laser, within a signal processor portion 300 for amplifying a RF signal reproduced from the optical disk is provided an equalizer 330 for lifting up high-frequency region of the RF signal, wherein an optimal control is made on an amount of lifting (i.e., EQ Boost Value) by the equalizer, depending upon a difference (?AF) between a focus offset amount at which the RF signal reproduced comes to be maximum and a focus offset amount at which jitter of the RF signal reproduced come to be minimum.

Abstract: A signal processing circuit for adjusting an input signal and generating a corresponding digital output signal in an optical disk driver is provided. The signal processing circuit includes an attenuator for receiving and attenuating the input signal and then generating an attenuated output signal; a gain controllable amplifier for receiving and amplifying the input signal and then generating an amplified output signal; a control unit providing a control signal and a select signal, the control signal is directed to the attenuator and the gain controllable amplifier for enabling/disabling the attenuator and the gain controllable amplifier and for controlling their gains such that one of the attenuator and gain controllable amplifier is enabled at a time; and a waveform adjuster circuit for adjusting the amplified/attenuated output signal delivered from the gain controllable amplifier or the attenuator so as to generate the digital signal related to the input signal.

Abstract: The present invention relates to a frequency detection method for an optical disc bit data reproduction apparatus. The frequency detection method uses the optical disc bit data reproduction apparatus including an Analog to Digital Converter (ADC), an interpolator, an asymmetry compensator, a digital bit and successive bit length detector, a frequency detector, a phase detector and a Digital Controlled Oscillator (DCO). In the frequency detection method includes the primary frequency detection step and the secondary frequency detection step. In the primary frequency detection step, status of input RF digital bit data frequency versus sampling frequency is determined and the sampling frequency is corrected so as to allow the sampling frequency to be rapidly adjusted to the frequency of the RF digital bit data, thus primarily detecting frequency.

Abstract: A reproduction apparatus is capable of reproducing information recorded on information recording media including at least a super RENS recording medium. The reproduction apparatus includes: an optical head that receives laser light that has been reflected or transmitted by the information recording medium and photoelectrically converts the laser light to an electric signal; a signal processing circuit that extracts an AC component from the electric signal and attenuates the AC component by a predetermined attenuation; an amplitude controlling circuit that controls an amplitude of an electric signal outputted from the signal processing circuit so as to become a predetermined amplitude; and a reproduction circuit that reproduces information recorded on the medium based on an electric signal outputted from the amplitude controlling circuit. An information recording medium testing apparatus includes the reproduction apparatus and a test information generating circuit that generates test information.

Abstract: A PLL circuit having an analog-to-digital converter; a phase error detecting circuit; and an oscillator, in which the phase error detecting circuit includes: phase error detecting means detecting a phase error from a data stream signal and a data stream signal 1 clock cycle earlier; absolute value comparing means detecting an absolute value of the phase error detected exceeding a predetermined threshold; holding means holding a polarity of the phase error, as of a timing of the detection by the absolute value comparing means, for a period of the detection; anticoincidence detecting means detecting anticoincidence between the polarity held by the holding means and a polarity of the phase error detected by the phase error detecting means; and polarity inverting means that provides the phase error detection signal by inverting the polarity of the phase error in detection of anticoincidence, or without inverting the polarity in detection of no anticoincidence.

Abstract: A correlation receiver, among other functions, detects peaks of a correlation signal. The correlation receiver includes a master peak detector for determining whether an amplitude of a pulse of the correlation signal exceeds by at least a first delta an amplitude of a prior peak. If so, the master peak detector designates the pulse as a peak and sets an amplitude of the peak as the amplitude of the prior peak increased by a second delta. The master peak detector may also determine whether the amplitude of the correlation signal pulse falls below an amplitude of the prior peak less a droop value; and, if so, the master peak detector does not designate the pulse as a peak.

Abstract: Without waiting for the rotational speed of an optical disk reaches a rotational speed (Vb) for a reproduction process, a cutoff frequency (Fca) of an RF signal and a boost amount (Bt) for an equalizer circuit are detected, and, with using the rotational speed (Va) of the optical disk at this detection, the cutoff frequency (Fc) by which jitter of the RF signal is optimized when the optical disk is rotated at the rotational speed (Vb) for the reproduction process is calculated by the equation of Fc=Fca+k(Vb?Va), and then set. Therefore, the time between the timing when the user conducts an input operation for starting reproduction, and that when reproduction is actually started can be shortened, and the usability can be improved.

Abstract: In a slew rate limiter, a slew rate is limited so as not to pass a signal varying more abruptly than a wobble signal included in a difference signal generated by a differential amplifier, and this limited slew rate is used to process the difference signal to be outputted. That is, the slew rate limiter removes a signal varying more abruptly than a wobble signal included in a difference signal DIFO, and then outputs only the wobble signal. A DAC generates an offset voltage. An adder is used to add this offset voltage to the wobble signal from the slew rate limiter. The signal obtained by this addition as a slice level is compared by a comparator with the difference signal, thereby reproducing an LPP signal.

Abstract: A disk type record playback device having a wobble signal extracting bandpass filter for controlling a filter's center frequency according to a frequency follow-up control loop including a dummy filter identical in configuration to a filter to be controlled, and a phase comparator is capable of controlling the center frequency of the bandpass filter with satisfactory accuracy. A frequency variable lowpass filter is provided in a preceding stage of the phase comparator constituting a frequency follow-up circuit and supplies a signal obtained by eliminating harmonic components from a frequency follow-up clock signal to the phase comparator. A cutoff frequency of the lowpass filter is changed in cooperation with a center frequency of the bandpass filter, based on a signal outputted from the frequency follow-up control loop.

Abstract: The present invention has an object to stably reproduce wobble signals of all disks of CD-R/RW, DVD-R/RW and DVD-RAM by one wobble signal reproducing circuit. In the wobble signal reproducing circuit, an AGC (AUTOMATIC GAIN CONTROL) circuit for equating a push-pull circuit output of a wide range and an RF amplitude of an optical detector output of two systems obtained by push-pull, and an AGC (AUTOMATIC GAIN CONTROL) circuit for making a wobble amplitude uniform are provided with a function to hold a gain or to change over a response time constant, and at the time of reproduction of the DVD-R/RW, a land pre-pit region is detected by the push-pull output to hold AGC (AUTOMATIC GAIN CONTROL) or change over a response time constant. Besides, in an address information recording region (PID region) at the time of reproduction of the DVD-RAM, the AGC (AUTOMATIC GAIN CONTROL) is held or the response time constant is changed over.

Abstract: An apparatus for reproducing information that has been digitally recorded on a storage medium includes first and second waveform equalizers. The first waveform equalizer equalizes a read signal, corresponding to the information read out from the storage medium, thereby outputting a first equalized signal. The second waveform equalizer has an equalization characteristic different from that of the first waveform equalizer, outputs a second equalized signal and is selectively used to extract a read clock signal.

Abstract: A defect protecting circuit and a method for data slicer in an optical drive is disclosed. As a defect occurs in a disk, the gain of the data slicer is switched to a high gain. After the defect does not occur further, the gain is switched back to a normal gain. Therefore the slicing level can return back to a correct slicing level for reducing incorrect data after the defect terminates, and the jitter in the output data is also reduced.

Abstract: An apparatus and method for generating a radio frequency (RF) signal and control signals are provided. In an apparatus for generating a radio frequency (RF) signal and control signals in which the current output from a plurality of light receiving elements is converted into voltage signals and the RF signal and the control signals are generated in response to the voltage signals, the apparatus includes an input data processing unit, a digital filter, a servo signal generating unit, a digital RF data generating unit, and a reference comparator. The input data processing unit performs time-sharing sampling on the voltage signals and converts the voltage signals into first digital signals in response to an analog/digital conversion clock signal having a predetermined period and a sequentially applied selection signal. The digital filter filters each of the first digital signals to modify the shape of the waveforms of the first digital signals and outputs the modified waveforms as second digital signals.

Abstract: Method for controlling a laser power used in recording on an optical disk includes: causing the laser to emit a test light emission pattern including a multipulse light emission interval and an at-bottom value continuous light emission interval; receiving the test light emission pattern of the laser to convert the pattern to an electric signal and to thereby obtain a light detection signal; calculating a detection value of a multipulse average value from the average value of the light detection signal, and calculating a bottom detection value from the light detection signal to obtain a light emission power characteristic of the laser on a supplied current based on the detection value of the multipulse average value and the bottom detection value; and controlling the current supplied to the laser based on the light emission power characteristic on the current supplied to the laser.

Abstract: In a method of controlling data reproduction in an optical disk drive, when a decoding error occurs, decoding is performed by changing a servo parameter. Thus, the decoding errors are reduced while playability is improved. The method of controlling data reproduction in an optical disk drive for reading data stored on an optical disk is performed by monitoring whether a decoding error occurred at a host part, if a decoding error occurred, changing a servo parameter for adjusting balance and/or offset of error signal which input to servo system, and rereading a portion on the optical disk medium where the decoding error occurred using the changed-servo parameter and performing decoding.

Abstract: Without waiting for the rotational speed of an optical disk reaches a rotational speed (Vb) for a reproduction process, a cutoff frequency (Fca) of an RF signal and a boost amount (Bt) for an equalizer circuit are detected, and, with using the rotational speed (Va) of the optical disk at this detection, the cutoff frequency (Fc) by which jitter of the RF signal is optimized when the optical disk is rotated at the rotational speed (Vb) for the reproduction process is calculated by the equation of Fc=Fca+k(Vb−Va), and then set. Therefore, the time between the timing when the user conducts an input operation for starting reproduction, and that when reproduction is actually started can be shortened, and the usability can be improved.

Abstract: A servo control apparatus of an optical pickup includes an extractor for extracting an error signal from the read signal; a driver for changing the servo position; an equalizer for equalizing the error signal to generate a drive signal; a calculator for calculating an integral value of the error signal for each predetermined angular section of rotation; a memory for storing each of the integral values for one rotation of the recording medium; a detector to detect an occurrence of a dropout; a calculator for calculating a variation by comparing the integral value for an angular section of rotation where the dropout occurred with a stored integral value for the identical angular section of rotation prior to the occurrence of the dropout; and a controller for changing an equalization characteristics of the equalizer in accordance with the variation.

Abstract: The present invention realizes stable and more proper data reproduction even when a reproduced signal varies locally due to a noise or includes a steady distortion. In a data reproduction control method and apparatus, and an optical disk unit that adjust sampled values, in sampling a signal reproduced from a recording medium recorded with data, the frequencies of the levels of quantized data are counted, a histogram of the frequencies of the levels is created based on the counting results, and more accurate reproduced data is obtained by means of a distribution of the frequencies of the levels in the histogram.

Abstract: A mark length selection apparatus is provided with a mark length measuring unit for measuring mark lengths of a signal which is read from an optical disc; a mark length selection unit for dividing one of continuous two mark lengths by the other mark length, which mark lengths are measured by the mark length measuring unit, and selecting some mark lengths from the mark lengths measured by the mark length measuring unit, on the basis of a result of comparison performed between a result of the division and a predetermined threshold value, and outputting the selected mark lengths; and a maximum mark length detection unit for detecting a maximum mark length that is the longest mark length among the mark lengths outputted from the mark length selection unit 120. Therefore, a maximum mark length can be detected while eliminating improper mark lengths which are caused by flaws or contamination on the optical disk.

Abstract: An apparatus, a method, and a computer readable recording medium thereof to update filter tap coefficients of an equalizer include a defect signal detection unit and a coefficient updating unit. The defect signal detection unit receives a sampled input signal reflected from an optical disc and/or a track jump signal, detects whether the input signal and/or the track jump signal are defective, and outputs an update stop signal indicative thereof. The coefficient updating unit stops the updating of the filter tap coefficients in response to the update stop signal and outputs current filter tap coefficients.

Abstract: A disk drive apparatus reads information with high accuracy from an information read/write medium. Information recorded on the information read/write medium is optically read with a pickup, and in accordance with the read signal Sin, an RF signal generated by an RF signal generation circuit is supplied to a frequency characteristic compensation circuit to generate an RF signal having a compensated frequency characteristic. Here, the frequency characteristic compensation circuit 10 is an equalizer comprising a differential amplifier, fixed resistors, variable resistors, and variable capacitance element. Values of the variable resistors and the variable capacitance element are adjusted to variably adjust the frequency characteristic of the frequency characteristic compensation circuit.

Abstract: An information reproducing device for reproducing digital signals with an optical head from an optical disk includes a first equalizer for waveform-equalizing a reproduction signal, an adaptive learning device for renewing the equalization properties of the first waveform equalizer with an adaptation algorithm, a memory for storing a reproduction signal, a second waveform equalizer that reads signals from the memory and performs waveform equalization after an adaptive learning operation for the first waveform equalizer has been terminated, and a demodulator for demodulating the output of the second waveform equalizer. Thus, adaptive equalization processing can be performed with constantly superior equalization properties and without sacrificing data capacity.

Abstract: An optical disk drive apparatus includes an optical head that directs a laser beam onto information pits formed in an optical disk, and a phase synchronization system that generates a clock signal that is phase-synchronized with respect to the information reproduction signal obtained from a reflected laser beam. The optical disk drive apparatus includes a measuring arrangement that measures the frequency of the clock signal, and a setting arrangement for setting the gain in the phase synchronization system proportionally with the frequency.

Abstract: This optical receiving device for discriminating and recovering a data signal, which results from converting an optical signal input through a dispersion equalizer into an electrical signal and amplifying it to a pre-determined amplitude, by using a clock and data recovery circuit for discriminating a data signal at the decision point controlled to achieve the optimum position controls the dispersion characteristics of a dispersion equalizer so that the error count in the recovered data signal by using a clock and data recovery circuit will be minimized by controlling the eye pattern of the data signal which has been amplified to a pre-determined amplitude.

Abstract: An optical disc playback apparatus that performs appropriate waveform equalization according to a difference in characteristics of reproduced signals between land parts and groove parts in an optical disc to which high-density recording is performed using a land/groove recording method. The optical disc playback apparatus includes a reproduction means 102, an A/D conversion circuit 103 for sampling a reproduced signal to be converted into a multi-bit digital signal, a filter 105 for subjecting the multi-bit digital signal to digital equalization, a filter coefficient learning means 106 for adaptively controlling filter coefficients for the filter 105 corresponding to the land part and the groove part to minimize an equalization error, and a switch signal generation means 107 for generating a signal for switching between land and groove, thereby changing the filter coefficient adaptively to the land or the groove.

Abstract: An interface circuit that is suitable for use in a recording system and a system for manufacturing optical disks, which is provided with this interface circuit, have an analog-side interface circuit 100A and a digital-side interface circuit 100B, these interface circuits being optically linked, either acoustically, or electromagnetically, so as to enable mutual transmitting and receiving of a digital signal therebetween. The interface circuits 100A and 100B, which serve as a receiving side with respect to the other sides, detect the logic of the digital signal with a timing that does not include the jitter component that is included in the transmitted digital signal, the detected digital signal logic being used as the basis for generating a new digital signal.

Abstract: A disc reproducing apparatus is disclosed, that comprises an optical pickup for reading a signal from a disc, a level slice PLL circuit for reproducing data from the signal read by the optical pickup, a signal processing unit for reproducing data with the clock signal reproduced by the level slice PLL circuit, and a range changing circuit for changing a linear velocity range (namely, a capture range) of the level slice PLL circuit in a time period at least after an occurrence of a reproduction command until data is reproduced from the disc at a target linear velocity corresponding to the reproduction command. Thus, even in a transient state such as an accelerating/decelerating state of a CD-ROM or the like, data can be properly reproduced from the disc.

Abstract: An interface circuit that is suitable for use in a recording system and a system for manufacturing optical disks, which is provided with this interface circuit, have an analog-side interface circuit 100A and a digital-side interface circuit 100B, these interface circuits being optically linked, either acoustically, or electromagnetically, so as to enable mutual transmitting and receiving of a digital signal therebetween. The interface circuits 100A and 100B, which serve as a receiving side with respect to the other sides, detect the logic of the digital signal with a timing that does not include the jitter component that is included in the transmitted digital signal, the detected digital signal logic being used as the basis for generating a new digital signal.

Abstract: A reproducing and recording apparatus, a decoding apparatus, a recording apparatus, a reproducing and recording method, a decoding method and a recording method are provided in which a computation for changing acoustic characteristics of compressed digital data is effected on a scale factor of each divided band in the compressed digital data including spectrum data band-divided into a plurality of bands on a frequency axis and the scale factor of every divided band.

Abstract: There are provided a modulation table, a selector, and a counter. The modulation table is used for creating a plurality of modulation data candidates with respect to a mixture of user data and training data. The selector selects modulation data candidates. The counter counts DSVs for the selected modulation data and controls the selector. The DSV output from this counter is set to a specified value by keeping a state in which the training data is input.

Abstract: A reproducing and recording apparatus, a decoding apparatus, a recording apparatus, a reproducing and recording method, a decoding method and a recording method are provided in which a computation for changing acoustic characteristics of compressed digital data is effected on a scale factor of each divided band in the compressed digital data including spectrum data band-divided into a plurality of bands on a frequency axis and the scale factor of every divided band.

Abstract: A servo control apparatus of an optical pickup includes an extractor for extracting an error signal from a read signal; an equalizer including a phase compensator for equalizing the error signal to generate a drive signal; a driver for changing the servo position of the optical pickup in response to the drive signal; a dropout detector for extracting an envelope signal from the read signal to detect a dropout of the read signal; and a controller. The controller changes an equalization characteristics of the equalizer in accordance with an amplitude of the envelope signal during the period of time when the dropout occurs or in response to an occurrence of the dropout.

Abstract: A servo control apparatus of an optical pickup includes an extractor for extracting an error signal from the read signal; a driver for changing the servo position; an equalizer for equalizing the error signal to generate a drive signal; a calculator for calculating an integral value of the error signal for each predetermined angular section of rotation; a memory for storing each of the integral values for one rotation of the recording medium; a detector to detect an occurrence of a dropout; a calculator for calculating a variation by comparing the integral value for an angular section of rotation where the dropout occurred with a stored integral value for the identical angular section of rotation prior to the occurrence of the dropout; and a controller for changing an equalization characteristics of the equalizer in accordance with the variation.

Abstract: A disk drive apparatus reads information with high accuracy from an information read/write medium. Information recorded on the information read/write medium is optically read with a pickup, and in accordance with the read signal Sin, an RF signal generated by an RF signal generation circuit is supplied to a frequency characteristic compensation circuit to generate an RF signal having a compensated frequency characteristic. Here, the frequency characteristic compensation circuit 10 is an equalizer comprising a differential amplifier, fixed resistors, variable resistors, and variable capacitance element. Values of the variable resistors and the variable capacitance element are adjusted to variably adjust the frequency characteristic of the frequency characteristic compensation circuit.

Abstract: An optical disk drive apparatus drives an optical disk at a constant angular velocity (CAV). The optical disk is formatted under constant linear velocity (CLV). The phase error changes linearly from the inner most track to the outer most track. Tack pulse counter is provided to detect the radial position of the optical head on the optical disk. Calculators are provided to correct the phase error according to the radial position of the optical head.