Abstract: An apparatus for detecting pre-pit information is disclosed, including an optical pickup, an optical-detecting section, a difference-detecting circuit, a first peak-value detecting circuit, a filtering circuit, a second peak-value detecting circuit, a differential potential-dividing circuit, and a comparator.

Abstract: The present invention relates to a signal shaping circuit which is capable of shaping a returning light signal of a modulated signal whose signal level and signal length are arbitrarily varied such that it can be demodulated. The shaped signal pattern generation circuit 15 has, in advance, variation pattern information with regard to a predetermined variation pattern to be applied on a returning light signal recorded therein. The counter 13 inputs a returning light signal, counts a signal length thereof and sends a count value to the shaped signal pattern generation circuit 15. An A/D conversion 14 detects a signal level of the returning light signal and sends the detected signal level to the shaped signal pattern generation circuit 15 in a similar way. The shaped signal pattern generation circuit 15 refers to the variation pattern information and calculates an optimum signal pattern corresponding to a signal length and a signal level of the inputted, returning light signal.

Abstract: An amplitude variation detection circuit that can reliably detect the mirror portion independently of the type of optical recording medium, as well as a type of information regenerating apparatus that contains said amplitude variation detecting circuit. Voltage division of top envelope signal Ste and bottom-hold signal Sbh of RF signal Srf is performed by voltage divider (16); then, after amplification by gain control amplifier (19) with a gain that corresponds to the type of optical disc (1), a prescribed offset is added by offset circuit (22) to the signal, and the resulting signal is input as mirror detection threshold signal Smt to comparator (24). The high-frequency noise component of bottom envelope signal Sbe of RF signal Srf is removed by low-pass filter (21); after amplification by gain control amplifier (20) with a gain that corresponds to the type of optical disc (1), the signal is input to comparator (24).

Abstract: A circuit and a method of detecting a mirror signal for an optical disc apparatus, the method includes detecting a bottom envelope from a radio frequency signal and providing a bottom envelope signal thereof, amplifying the bottom envelope signal according to a center level of the bottom envelope signal, and comparing the amplified bottom envelope signal with a predetermined comparison voltage to detect the mirror signal.

Abstract: A signal processing circuit, which extracts a signal superimposed on a reference signal and having a peak level higher than a level of the reference signal by a value greater than a given value, includes a first pulse generation part generating a first binary signal by binarizing a composite signal of the reference signal and the superimposed signal by using a given slice level, a noise elimination part eliminating noise from the first binary signal by using a cumulative length of time of each of polarities of the first binary signal, a second pulse generation part generating a second binary signal by binarizing the composite signal by using a slice level higher than the level of the reference signal by a value smaller than or equal to the given value, and a gate part outputting the second binary signal based on a signal output from said noise elimination part.

Abstract: A plurality of light receiving detectors receive a plurality of segments of a beam returning from an optical disc when a reading beam of light is radiated to the optical disc. An optical pickup assembly produces a plurality of signals from the beam segments in accordance with, for instance, optical intensities of the beam segments. A level adjusting circuit adjusts signal levels of these signals such that each of the signal levels of the signals becomes equal to a reference level. The reference level is determined from at least one of the signal levels of the received beam segments.

Abstract: A radio frequency ripple zero crossing signal calibration method for an optical disk reader undergoing a track following to track seeking transition is disclosed. The method utilizes sampling to obtain radio frequency ripple peak level during a track seeking operation and radio frequency ripple DC level during a track following operation and using their differences as a calibrated value. Through the calibrated value, the radio frequency ripple zero crossing slice level is modified so that a correct radio frequency ripple zero crossing signal is obtained during a track following to track seeking transition. In a track following to seeking transition, this arrangement prevents distortion of the radio frequency ripple signal and corresponding drift in the radio frequency zero crossing signal that may lead to errors in computing moving speed and counting tracks of the pickup head. Hence, search capacity of the optical disk reader is improved and the pickup head is better controlled.

Abstract: A system and method for controlling operation of a motor system that addresses the design challenges for the small form factor optical disk system. The control system can be operable to obtain digital feedback from a spin motor. The present invention includes detecting data representing a position on an optical medium and determining a detection rate; comparing the detection rate to a reference rate to provide an error rate; generating an output command in response to the error rate to provide a drive output which commands a voltage applied to a spin motor to adjust the spin speed of said spin motor.

Abstract: A method for counting a number of tracks of an optical disc in an optical disc system. The optical disc system includes an optical pickup, a light source, and a plurality of optical sensors. The method includes emitting a light beam to the optical disc from the light source, detecting light reflected from the optical disc by the optical sensors, and generating a tracking error signal according to detected signals of the optical sensors while the optical pickup moves along a radial direction of the optical disc. The method further includes generating a tracking error zero crossing signal according to the tracking error signal, generating a peak detecting signal according to the tracking error signal, generating a pseudo radio frequency zero crossing signal according to the peak detecting signal, and generating a track count signal according to the pseudo frequency crossing signal.

Abstract: An information readout apparatus and an information readout method can efficiently correct the change in the size of the aperture. An optical disk 1 having a recording layer and a readout layer is used and the information recorded on the recording layer of the optical disk 1 is read out by irradiating a light beam onto the optical disk form head 2 and opening a detection window smaller than the area irradiated by the light beam in the readout layer. The resolution detecting section 15 of the apparatus detects the isolated mark recorded in the optical disk 1 in advance and then detects the resolution on the basis of the quotient obtained by dividing the difference X between the sample value Y near the peak of said isolated mark and the sample value adjacent to said sample value Y by said sample value Y near the peak, or X/Y.

Abstract: The position of a light blocking object is detected not only within a display screen, but also outside the display screen. With the use of the function of detecting the position in a region outside the display screen, it becomes possible to provide virtual buttons in this region and detect dust around a light retro-reflector. Dirt on the light retro-reflector is detected based on the levels of light receiving signals of optical units.

Abstract: A tuned circuit is used to detect wobble clock inversions. The tuned circuit reacts to a wobble inversion with a change in amplitude that may be detected by a threshold detector. A bandpass tuned circuit is used to detect wobble clock inversions. The output of the bandpass tuned circuit is input to a saturating high-gain amplifier such as a comparator. The output of the saturating high-gain amplifier reacts to wobble inversions with a half-cycle that has an increased duration as compared to half-cycles without wobble inversions.

Abstract: In a signal detection circuit for an optical disk, a comparator converts an analog HF signal into a digital HF signal by using a slice level. A dropout detection circuit detects a dropout of the digital HF signal. A charge-pump circuit feeds back a slice-level control voltage to the comparator based on a result of the detection by the dropout detection circuit. A voltage follower holds and outputs a voltage stored in the capacitor. A switch is turned OFF when a dropout signal has been detected, and outputs to the voltage follower the voltage that has been stored in the capacitor during an ON state of the switch. A second switch is turned ON when a dropout signal has been detected, and applies an output of the voltage follower to the comparator.

Abstract: A circuit arrangement including means for determining a slicer level from incoming signal levels for slicing the incoming signal levels on the basis of the slicer level thus determined, includes a first and a second register circuit, which register circuits are connected to an output of a discriminator circuit. The discriminator circuit compares an incoming signal level with a set discrimination level and is adapted to apply an incoming signal level to the first register circuit if the incoming signal level is higher than the set discrimination level and to apply and incoming signal level to the second register circuit if the incoming signal level is lower than the set termination level. The first and the second register circuit are adapted to determine a register value of a least two different incoming signal levels consecutively applied to the register circuit. The circuit supplies a signal having a level which is a value determine from register values determined by the first and second register circuit.

Abstract: A data reproduction apparatus for adjusting filter coefficients of an equalizer including a digital filter, and connected before a Viterbi detector and a method therefor. A level of the output value of the equalizer is detected based on a reference level set in the Viterbi detector, and a level error of the detected level with respect to a predetermined reference value is detected. The filter coefficients of the equalizer are adjusted such that the level error is minimized, thereby improving the detection performance of the Viterbi detector.

Abstract: A method and device of determining the slice level of a radio frequency ripple (RFRP) signal for performing a tracking operation in a tracking controller of an optical storage device. The optical storage device receives a tracking error (TE) signal, a radio frequency center (RFCT) signal, and the RFRP signal, and then outputs a TE_input signal related to the slice level. The method includes the following steps: a. obtaining a count value when the absolute value of the TE signal is smaller than a threshold value; otherwise, resetting the count value; b. executing step c when the count value is smaller than a predetermined count value; otherwise, outputting the TE signal as the TE_input signal; and c. outputting the TE signal as the TE_input signal when the RFRP signal is greater than the RFCT signal; otherwise outputting a peak value of the TE signal as the TE_input signal.

Abstract: The present invention is an optical detection system to detect various areas of an optical storage medium. The optical detection system comprises a pickup head, a signal adder and an adding comparator. The pickup head have a light source for providing an incident light beam to the data area and the header, and generating the corresponding reflective light beam. The pickup head detects the reflective light beam to generate left-side detection signals and right-side detection signals. The signal adder adds the amplitudes of the left-side detection signal and the right-side detection signal to generate an adding signal. The adding comparator compares the adding signal with a predetermined adding reference signal to generate a compared adding signal. According to the compared adding signal, the optical detection system can determine that the reflective light beam detected by the pickup head comes from the data area or the header.

Abstract: The present invention is applied to an optical disk apparatus which records data on and/or plays back data from one of a variety of DVD optical disks. The present invention generates a binarization threshold S3 by offsetting an envelope S2 of a playback signal RF by an offset voltage V1, and binarizes the playback signal RF (S4) according to the binarization threshold.

Abstract: An optical disk device reproduces an RF signal by projecting a light beam on an optical disk and detecting a reflected light therefrom. On the optical disk, information is recorded by forming a pit on a track determined according to a groove having a wobble signal recorded thereon. The optical disk device comprises a comparator comparing the RF signal with a threshold value so as to output a binary signal, a first band-pass filter filtering a frequency band of the wobble signal from the binary signal so as to extract a wobble signal component, and a first adder obtaining a value by adding the wobble signal component to a fixed reference value so as to supply the value to the comparator as the threshold value.

Abstract: There are provided a spindle motor 12, an optical head 20, a high-pass filter 31, low-pass filters 32 and 33, an adder 38, and a PLL 39. The spindle motor 12 rotatively drives an optical disk 11. The optical head 20 irradiates a laser beam onto a target track and both tracks adjacent to the target track on the optical disk 11 and detects a return light from each track. The high-pass filter 31 filters a high-frequency component in a signal used for detecting a return light from a target track in the optical head 20. Each of the low-pass filters 32 and 33 filters a low-frequency component in a signal used for detecting a return light from each of the adjacent tracks. The adder 38 operates output signals from the high-pass filter 31, and the low-pass filters 32 and 33. Based on a signal from the adder 38, the PLL 39 generates a reference signal used as a time reference for generating recording signals. An operation by the adder 38 nullifies a cross modulation component.

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 equalizer for producing an equalized signal from an input signal. The input signal has a DC component. The equalizer includes a programmable filter and equalizer. A detector for generating a threshold signal from a preprocessed signal. The preprocessed signal is generated from the equalized signal. A comparator for comparing the preprocessed signal to the threshold signal to produce an output signal. A tracking device for tracking the DC component from the output signal.

Abstract: A prepit detecting apparatus which uses an optical recording medium having information recording tracks on which information is recorded and guide tracks each of which guides a light beam to the information recording track and on which prepits for saving pre-information are formed such that the light beam is applied to the information track of the optical recording medium, the prepit detecting apparatus comprising: light receiving means divided into a first divided light receiving portion and a second divided light receiving portion divided along an optically parallel division line in a direction of tangent of the information tracks and arranged to receive reflected light of the light beam with which the optical recording medium has been irradiated; and a difference calculator for calculating the difference between a first read signal output from the first divided light receiving portion and a second read signal output from the second divided light receiving portion so that the prepit is detected in response

Abstract: An optical disk medium includes a track groove thereon. On the optical disk medium, information is recorded along the track groove on a block unit basis. The block unit has a predetermined length. The block unit having the predetermined length includes a number of sub-blocks that are arranged along the groove. A sub-block mark is provided within each of the sub-blocks and used to identify the sub-block.

Abstract: A PLL (phase-locked loop) circuit is configured with a phase-error detection circuit comprises the following: a provisional judge circuit for provisionally judging a data signal being input to an A/D converter into three levels of 1, 0, and −1; a pattern detector which, among data signals being input in accordance with a result of the provisional judgment, checks a transition pattern ranging from a data signal that precedes one clock cycle to the actually present data signal, and then, when a specific pattern is detected, instructs a selector to select output data from the A/D converter; and the selector which, in compliance with instruction from the pattern detector, selects phase-error data from data signals output from the A/D converter, and then converts the selected phase-error data into an electric current before externally delivering it as an error-current.

Abstract: The invention provides an optical disk medium having a recording spiral formed by connecting groove tracks and land tracks alternately, and permitting detection of a connecting point between a groove track and a land track reliably is provided, and a method of tracking the optical disk medium and an optical disk drive apparatus for driving the optical disk medium. One part of an identification signal area is shifted by a predetermined distance in one radial direction from the center of a groove, while another part of the identification signal area is shifted by the same distance in the opposite radial direction from the center of the groove. A land/groove polarity of a sector is determined by the polarity of a tracking error signal and the order of the polarities during reproduction of an identification signal.

Abstract: An optical disk drive reads and/or writes data from/on an optical disk on which a pre-pit has been formed on at least one side edge of a data recording track. The disk drive includes light-emitting element, photodetector section, subtractor and amplifier. The light-emitting element emits a light beam and irradiates the track with the light beam. The photodetector section receives and detects the light beam reflected from the track, thereby generating first and second detection signals, carrying information about shapes of the track at the one and the other side edges thereof, respectively, based on the reflected light beam. The subtractor generates a differential signal representing a difference between the first and second detection signals. The amplifier amplifies the differential signal, output from the subtractor, by a variable amplification factor. The optical disk drive detects the pre-pit in accordance with the amplified differential signal.

Abstract: The invention provides an optical disk medium having a recording spiral formed by connecting groove tracks and land tracks alternately, and permitting detection of a connecting point between a groove track and a land track reliably is provided, and a method of tracking the optical disk medium and an optical disk drive apparatus for driving the optical disk medium. One part of an identification signal area is shifted by a predetermined distance in one radial direction from the center of a groove, while another part of the identification signal area is shifted by the same distance in the opposite radial direction from the center of the groove. A land/groove polarity of a sector is determined by the polarity of a tracking error signal and the order of the polarities during reproduction of an identification signal.

Abstract: To finely remove an offset from a tracking-error signal which is processed in the digital form at the stage of tracking servo control, an apparatus and method of correcting the offset is provided. In the apparatus and method, an oscillating tracking-error signal used for positionally controlling an optical beam irradiated onto a storage medium to reproduce information recorded thereon is produced. The tracking-error signal is produced in an analog form, then converted into a digital form for use of control of the optical beam. First, set are a first adjustment amount to correct an offset included in the analog-form tracking-error signal as well as a second adjustment amount to correct a further offset included in the digital-form tracking-error signal in the digital form. The analog-form tracking-error signal is corrected with the first adjustment amount (i.e., coarse adjustment), then the digital-form tracking-error signal is corrected with the second adjustment amount (fine adjustment).

Abstract: An apparatus and method for controlling tracking for an optical recording/reproducing apparatus is disclosed. A track center level is determined at a point where a high width of a TE signal generated during free-running or traverse is equal to its low width. Alternatively, a TE detection level at a TZC point of the TE signal in which asymmetry is adjusted is determined as the track center level. The determined track center level is used for normal recording/reproduction, so that the tracking servo is activated at the actual track center position. Thus, initial stable tracking performance can be obtained, and bias of the tracking can be avoided during tracking control by estimating the exact track center value.

Abstract: A method, circuit and system for selectively and adaptively effecting conditioning of selected samples of a read signal in storage technologies. A circuit embodying the present invention includes sample logic, arithmetic logic and conditioning logic. The sample logic receives samples and provides a main sample and one or more selected neighbor samples. The arithmetic logic compares the main sample to the neighbor samples toward determining satisfaction of selected conditioning criteria. If the selected conditioning criteria are satisfied, the conditioning logic selectively and adaptively effects level conditioning as to the main sample. Further, the level conditioning is combined with a rule compliance system to insure the read data is following the protocol of the data coding format being used.

Abstract: Information reproduction apparatus of the present invention is directed to realize data reproduction properly and reliably from an optical disk, including a wobble detection circuit (130) to detect a wobble signal read out by an optical head (500), a PLL circuit (150) to frequency-multiply the wobble signal to generate a synchronizing signal (SS0), a delay circuit (170) delaying a synchronizing signal (SS0) sequentially to generate a plurality of synchronizing signals (SS0-SS10) of different phases, a particular pattern detection circuit (190) to detect a particular pattern in a reproduced signal, and a switching unit (210) to select one synchronizing signal having a phase difference preset by a preset circuit (180) with respect to a detected particular pattern and supplying the selected synchronizing signal to a laser drive circuit (230) and to a signal demodulation circuit (90).

Abstract: In an apparatus and a method for correcting asymmetry in an optical disk reproduction system, an analog RF signal is received from an optical diode and an asymmetry-corrected signal is output as a digital EFM signal. The apparatus includes envelope detectors for detecting upper and lower envelopes of the RF signal, a level controller for controlling the level of the sum of the upper envelope and the lower envelope and for outputting signal having the controlled level, and a comparator for comparing the level of the signal output from the level controller with the level of the RF signal and for outputting the comparison result as the digital EFM signal.

Abstract: A disc player having a prepit detecting circuit which can correctly detect prepits even if phases or amplitude levels of a plurality of read signals read out from a recording disc are deviated from each other. A phase difference between a first read signal and a second read signal read out by first and second reading elements arranged in two regions divided along the direction of recording tracks of a recording disc is detected. A first phase correction read signal is obtained by adjusting the phase of the first read signal by an amount according to the phase difference. A differential value between the first phase correction read signal and the second read signal is outputted as a prepit detection signal.

Abstract: The present invention has an objective of providing a digital data reproduction apparatus and a method for correcting a reproduced signal digitization level in which the signal quality of a reproduced signal from a recording medium is kept high while ensuring the reproduction stability. The digital data reproduction apparatus includes: reproduced signal digitization means for digitizing a reproduced signal; synchronization means for producing a clock whose phase is synchronized with a leading edge and a trailing edge of the digitized signal produced by the reproduced signal digitization means; and jitter detection means for integrating and thereby converting absolute values of phase errors between the digitized signal and the clock to a voltage value. The apparatus further includes digitization level correction means for correcting a reproduced signal digitization level so as to minimize a signal produced by the jitter detection means.

Abstract: In an apparatus and a method for correcting asymmetry in an optical disk reproduction system, an analog RF signal is received from an optical diode and an asymmetry-corrected signal is output as a digital EFM signal. The apparatus includes envelope detectors for detecting upper and lower envelopes of the RF signal, a level controller for controlling the level of the sum of the upper envelope and the lower envelope and for outputting signal having the controlled level, and a comparator for comparing the level of the signal output from the level controller with the level of the RF signal and for outputting the comparison result as the digital EFM signal.

Abstract: A controller instructs a spindle motor to start rotating, and instructs a servo control section to start a focus servo control. When a light beam crosses information tracks on an optical disc with a rotation of the optical disc, an amplitude indicating signal generating section detects changes in the amplitude of a readout signal output from an optical pickup. A disc type identifying section identifies types of optical discs having different track pitches of the information tracks in starting the rotation of each optical disc based on the peak value and bottom value or the amplitude of the readout signal. Consequently, the types of optical discs having different information recording densities, particularly different track pitches, can be identified at an early stage without waiting for reproduction of information recorded on each optical disc. It is therefore possible to shorten the time for starting an optical disc device, or prevent an increase in the starting time.

Abstract: A beam is irradiated to an information recording medium having land tracks and groove tracks alternately formed on a track formed in turn on an information recording surface thereof and pre-pits so pre-formatted as to deviate from the center of the track, a return beam of the irradiated beam is received by detectors split into two parts in a track direction to obtain a differential signal, the pre-pit is detected from this differential signal and control of recording and reproducing processings is executed by using the pre-pit detection signal so obtained as the reference.

Abstract: A tracking servo control apparatus for muting a tracking error signal when a mirror signal is generated, in an optical disk system, such as a compact disk player or a digital video disk, compensates for tracking gain and phase according to the tracking error signal. The apparatus includes a mirror setting unit for receiving the generated mirror signal and for generating a mirror signal by defining the mirror signal to predetermined minimum and maximum time intervals, a switch for outputting a muted tracking error signal while the defined mirror signal is activated, and otherwise, outputting the tracking error signal, and a tracking gain/phase compensator for receiving the output signal from the switch and compensating for the tracking gain and phase. Thus, the system can be stabilized by muting a tracking servo loop according to a mirror signal whose pulse width is defined to a predetermined window section.

Abstract: A waveform equalizer which can improve an S/N ratio without causing a jitter in a read signal read out from a recording medium. An amplitude level of the read signal read out from the recording medium is limited by a predetermined amplitude limitation value and, thereafter, is subjected to a filtering process.

Abstract: An amplitude detector for signals having a periodical character, recorded on a recording medium, including a first delay line and a second delay line, wherein an average maximum value of the detected signal is stored in the first delay line for each one of a predetermined number of detection instants within a detection period, and an average minimum value of the detected signal is stored in the second delay line for each one of the detection instants, means for determining an average level between the average maximum and minimum values for each detection instant on the basis of the output signals of the two delay lines, and means for comparing the current signal to be detected for a given detection instant with the average level for the detection instant so as to provide a detection signal.

Abstract: A defect detection circuit and method for detecting disk defects in an optical disc data reproduction system allows for correct detection of defects not only during operation in a constant linear velocity mode but also during operation in a constant angular velocity mode using a channel bit clock signal as a reference signal. The circuit includes a comparator for comparing an RF signal with a first compare voltage having a predetermined voltage level and a second compare voltage having a voltage level lower than the first compare voltage, and for generating a first comparison signal activated in response to the RF signal having a level higher than that of the first compare voltage and a second comparison signal activated in response to the RF signal having a voltage level lower than that of the second compare voltage.

Abstract: A method and apparatus for reducing the effect of inter-wave interference on signals read from a storage medium and to precisely digitize the read signals are described. An apparatus for digitizing a signal read from a storage medium according to an embodiment of the invention, comprises: a peak detector, for detecting a peak value for an amplitude of a signal read from the storage medium; a threshold value determiner, for employing the peak value obtained by the peak detector to determine a compensation value that is used for compensating for the effect of inter-wave interference on the signal, and for employing the threshold value calculated by the conventional method and the compensation value to determine a compensated threshold value; and a digitization circuit, for digitizing the signal by using the threshold value determined by the threshold value determiner. Optionally an interpolator may be used to obtain more accurate peak values which occur between sample points.

Abstract: The method and apparatus for testing the quality of an optical disk medium records test data in the outer area of an optical disk. This outer area of the optical disk is not used when manufacturing a prerecorded disk, and is also not used by users of write-once optical disks. The quality of the optical disk is judged based on the test signal produced from reproducing the test data in the outer area of the optical disk.

Abstract: The upper envelop signal generating unit detects the upper envelop of the detection signal to generate the upper envelop signal corresponding to the detected upper envelop, and the lower envelop signal generating unit detects the lower envelop of the detection signal to generate the lower envelop signal corresponding to the detected lower envelop. The slice signal generating unit divides the voltage difference of the upper envelop signal and the lower envelop signal using a predetermined division ratio to generate the slice signal. The averaging unit averages the slice signal to produce the average signal. The defect detecting unit compares the average signal and the upper envelop signal to produce the defect detection signal indicating the period in which the voltage of the upper envelop signal is lower than the voltage of the average signal. As a result, a very short defect like a wedge-shape defect can be reliably detected.