Abstract: A servo system with a multi-track seek algorithm with a zero crossing detector is presented. The zero crossing detector indicates when the tracking error signal crosses zero. In some embodiments, a delay is executed between adjacent detections of zero crossings in the tracking error signal, for example half a cycle. In some embodiments, a zero crossing is detected when the tracking error signal passes through a range around zero, the range having a positive value above zero and a negative value below zero.

Abstract: A calibration for a tracking error signal gain in a tracking servo system of an optical disk drive is presented. The calibration determines the peak-to-peak tracking error signal when the tracking servo system is open, calculates a gain factor in response to the peak-to-peak tracking error signal, and calculates a new tracking error signal gain based on the tracking error signal gain and the gain factor. New tracking error signal gains are calculated until the gain factor is approximately one.

Abstract: A switch is turned on by a learning control start command from a master control unit, and the positional deviation at respective cycles is read in. Correction data read out from a learning memory is added to the positional deviation, and the result is filtered by band limiting filter and then stored in the learning memory as correction data. The correction data read out from the memory is compensated for phase delay, fall in gain, and the like, by a dynamics compensating element, and is added to the positional deviation and input to a positional control section. When the command pattern for the same shape is completed, and a learning control end command is output, whereupon the switch is turned off and learning control terminates.

Abstract: A method and apparatus for detecting a topographic feature on a media is described. More particularly, a light scatter detector is coupled to an atomic force microscope. The detector is used detect scattered optical energy reflected from the surface of the media to identify the topographic feature. The atomic force microscope may then be positioned in response to the topographic feature identified.

Abstract: A tracking servo system with a at least one second order digital filter is presented. The servo system calculates an error signal and offsets, amplifies, and filters the error signal before a control signal is calculated. The control signal is then utilized to position an optical pick-up unit which provides signals from which the error signal is calculated. Filters in the servo system can include a low-pass integrator, a phase lead filter, notch filters, or other filters. At least one of the filters is a second order digital filter.

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: An optical disc controller for controlling recording or reproduction of an optical disc includes: a rewritable memory for storing information necessary for recording or reproduction of the optical disc; a determination section for determining a class and type of the optical disc; a search section for searching for a region of the optical disc in which control information is recorded based on a determination result of the determination section; a reproduction section for reproducing the control information recorded in the region searched by the search section; and a memory control section for changing an arrangement of the memory based on at least one of the determination result and the control information reproduced by the reproduction section.

Abstract: A tracking servo system with a tracking skate detection algorithm is presented. The tracking skate detection algorithm receives a tracking error signal and, takes the absolute value of the tracking error signal and filters the absolute value with a low pass filter. If the filtered signal exceeds a threshold value for a number of cycles exceeding a maximum number, then a tracking skate condition is indicated.

Abstract: The invention is a modulation system that encodes symbols in accordance with a modulation code which, for a given communications channel, produces a signal that at the decoder includes maximized sample timing information in each encoded symbol. For systems that use PLLs to control a sample timing clock, the sample timing information is the average or squared slope. The modulation code used for a given system is selected based on the target response h(x) of the associated communications channel, such that h (x)*rk exceeds a predetermined threshold value, where “*” represents convolution and rk is a modulation code symbol. To reduce the bit overhead, or code rate, the inventive modulation system provides more modulation code symbols at the start of a data block, or sector, when system jitter is expected to be relatively high in response, for example, to the movement of a read head.

Abstract: A calibration method for a control device of an optical storage medium drive includes generating a calibration-driving signal by a signal generator and then generating a sensing signal by a sensor according to the calibration-driving signal, determining whether each period of the sensing signal is suitable, and comparing suitable periods of the sensing signal with corresponding periods of the calibration-driving signal to determine a phase difference between the sensing signal and the calibration-driving signal so as to adjust gain of a control device of the optical storage medium drive according to the phase difference. The calibration method is capable of preventing the influence of unstable sensing signals and promoting the performance of the optical storage medium drive.

Abstract: A motor controlling device includes an acceleration detector for detecting an acceleration of a motor; a motor driver for supplying a driving current to the motor; a heat quantity calculator for calculating a heat quantity generated in the motor at least based on an output from the acceleration detector; and a motor controller for controlling the motor driver based on the heat quantity.

Abstract: The present invention provides a method and system for calibration of writing to an optical medium. The method includes: sampling marks in a calibration area of the optical medium; and converting the sampled marks into a digital format utilizing an ADC, the ADC also utilized by a servo control. The present invention provides a controller with an integrated servo and recording processor which allows a single ADC to be used for converting sample marks used in calibrating the writing to an optical media. No separate subsystem for converting sample marks is thus necessary. Less components are required, reducing the cost of manufacturing the controller. With less components, the risk of component failure is reduced as well.

Abstract: The present invention implements a servo system which can support changes of the higher resonance frequencies of the actuator with a simple configuration at low cost.

Abstract: In a focus control for following a focus position of light beam to be radiated to an optical disk to an optical disk surface, the technique is for shorten the memory length in the learning controller. The learning controller is provided to a focus feedback control system and updates the memory comprised of N numbers of memory cells with a shorter sample period than a time obtained by dividing the time required for one rotation of the disk by N numbers and outputs the learning results in the memory with the shorter sample period.

Abstract: A servo mark detector detects a servo mark from each servo information item detected by the servo detector. A counter measures a time period each time a servo mark is detected, thereby measuring a servo interval. A correction circuit corrects a time period T2 on the basis of the measured servo interval and an ideal servo interval. A determination circuit determines which one of the time period T2 and a time period T2? obtained by correcting the time period T2 should be used. A servo-sector-pulse-generating unit generates a servo sector pulse a time period T1 after the detection of each servo mark, and generates a pseudo servo sector pulse when the time period determined by the determination circuit has elapsed after the detection of each servo mark, if the next servo mark is not detected during the determined time period.

Abstract: Disclosed herein is a technology that enables stable and high-speed writing and/or reading in an optical disk apparatus. The optical disk apparatus has an optical head that includes a first circuit for driving a laser diode, a second circuit for sampling and holding analog electric signals that are based on reflected laser light from the optical disk, and a third circuit for converting said signals being sampled and held into digital signals. Signals digitized in the optical head are transmitted to the apparatus body side using time-division multiplexing. The first circuit, the second circuit, and the third circuit are constructed on a single substrate or in a single IC.

Abstract: A data storage device performs a re-read of data prior to a read inhibit for data recovery and validation. When misregistration of read/write heads occurs, as indicated by a sampled servo position, data read from a track of the data storage device is withheld from a host until a subsequent sampled servo position is verified to be within a read limit width of the track. Data blocks preceding the servo position that caused the posting of the read inhibit are re-read, once the read inhibit is cleared. If the read inhibit is not present following the re-read of the data, this re-read data can be released to the host.

Abstract: A tracking error detection device for an optical disk apparatus comprises a detecting unit which includes at least two detectors and detects a reflected light from a series of pits formed on an optical disk, a phase comparing unit which detects a phase difference of outputs of the at least two detectors, and a low-pass filter which smoothes an output of the phase comparing unit, a cut-off frequency of the low-pass filter being higher than a frequency at which a spectrum of a modulation code recorded in the optical disk becomes −10 dB and lower than a frequency at which the spectrum of the modulation code recorded in the optical disk becomes −5 dB.

Abstract: A positioning control device and method in which the relative position error in tracking is reduced by using the periodicity of position shift. The positioning control device comprises a position detecting unit for measuring the relative position error between the desired position of an objective member and a moving member, an adding unit for adding a position error signal output from the position detecting unit and a delay signal, a signal delay unit for outputting the delay signal which is obtained by delaying an output of the adding unit at a period corresponding to the position shift of the objective member, a drive unit for moving a moving member, and an inputting unit for inputting the signal of the sum of the position error signal and the delay signal to the drive unit and addition-inputting the delay signal to the drive unit through a filter having a predetermined frequency characteristic in a specific frequency range.

Abstract: An information recording and reproducing apparatus performs information recording and reproducing on an optical disc having a recording track wobbled by a predetermined frequency, such as a DVD-RW.

Abstract: A tracking error detection apparatus comprises a photodetector comprising plural photoreceptor elements; zerocross detection circuits for detecting zerocross points at which two sequences of digital signals intersect the center levels of the respective digital signals, which digital signals are generated according to the amounts of light received by the respective photoreceptor elements and are outputted from the photodetector; a phase difference detection circuit for performing phase comparison using a distance between zerocross points of the two sequences of digital signals, and outputting a result of phase comparison; and a low-pass filter for performing band restriction to a signal outputted from the phase difference detection circuit, thereby to obtain a tracking error detection apparatus.

Abstract: A direction sensor in a tracking and focus servo system of an optical disk drive is presented. The direction sensor calculates a direction sum signal and a tracking error signal from side elements of detectors in an optical pick-up unit of the optical disk drive. A first direction can be indicates when the signs of a high-pass filtered sum signal and a high pass filtered tracking error signal are opposite and a second direction opposite the first direction if the signs are the same.

Abstract: A disturbance compensation module using learning control generates a control input to compensate for track position errors due to a periodic disturbance occurring in an optical recording medium in an optical recording medium drive servo system of an optical recording/reproducing apparatus. The module includes a first filter to filter the track position errors and a memory to store control inputs to compensate for a track control cycle in a corresponding address. A second filter filters the control inputs stored in the memory. An adder adds the filtered track position errors from the first filter to the filtered control inputs from the second filter and outputs a result to the memory, updating the control inputs to compensate for the track position errors.

Abstract: A digital servo system for controlling tracking or focus in an optical disk driver is presented. A servo system according to the present invention includes an optical pick-up with detectors providing optical signals, an analog processor receiving the optical signals and providing a digital signal, and digital processors receiving the digital signal and providing a control signal that controls the position of the optical pick-up unit. The digital processor executes an algorithm that calculates an error signal, provides amplification and biasing to the error signal, provides filtering for the error signal, and computes the control signal. The error signal can be the focus error signal or the tracking error signal.

Abstract: A method for deriving a tracking error signal based on a first analog detection signal and a second analog detection signal. The method includes summing the first analog detection signal and the second analog detection signal to generate an analog sum signal. An analog delay device is utilized to delay the analog sum signal to be a delay signal. The delay signal is digitalized into a digital delay signal. The first analog detection signal and the second analog detection signal are respectively transformed into a first digital detection signal and a second digital detect signal. The tracking error signal is then generated utilizing a comparing operation among the digital delay signal, the first digital detect signal, and the first digital detect signal.

Abstract: At least part of a light beam reflected from an optical disc is divided into first through fourth light areas in directions corresponding to the radial and tangential directions of the disc, and first through fourth detection signals are output from the light areas. The first through fourth light areas are ordered counterclockwise or clockwise. A phase difference is obtained between a first sum signal obtained by summing the first and third detection signals and a second sum signal obtained by summing the second and fourth detection signals and first and second phase difference signals are output based upon the phase difference. The phase difference signals are summed to generate an optical recording/reproducing system monitoring signal for system adjustment even for high density optical discs, the monitoring signal being proportional to the degrees of a radial tilt, tangential tilt, a defocus, or a detrack.

Abstract: A servo control apparatus is provided to a stable servo control even when delays occur in detecting defects. Based on reflected light of an optical beam from an optical disc, a defect resulting from dark spots, damages, or others on the optical disc is detected. Immediately before the detection, sample data of a control signal are memorized. The sample data are obtained during a predetermined interval of time that corresponds to a detection delay for the defects, which is dependent on a defect detecting device. Using the memorized sample data, a cancel signal is produced for canceling the influence of the control signal, which is owing to a pseudo error signal obtained during the predetermined interval of time. The cancel signal is outputted as the control signal immediately after the detection of the defect.

Abstract: An optical recording medium that permits high density recording and only needs a recording machine of simple structure, and a machine for reproducing recorded information from such optical recording medium. A track pitch of recording tracks is smaller than a diameter of a beam spot of a scanning laser beam, and tracking pits for tracking control are formed on the respective recording tracks. A certain number of neighboring recording tracks define a group, and in each group the tracking pits are spaced from each other in a recording track direction by a predetermined interval which is smaller than the diameter of the beam spot.

Abstract: An objective lens converges a shorter wavelength laser beam on a DVD having a protective layer, which is 0.6 mm thick, and a longer wavelength laser beam on a CD having a protective layer, which is 1.2 mm thick. A common region is defined on the objective lens. The common region provides a numerical aperture appropriate for converging the longer wavelength laser beam on the CD. Coma of the objective lens in the first region is compensated better in a case where the longer wavelength laser beam is converged on the CD than a case where the shorter wavelength laser beam is converged on the DVD.

Abstract: A servo system with a multi-track seek algorithm is presented. The multi-track seek algorithm detects zero crossings in a tracking error signal, counts the number of zero crossings to form a count, and calculates a reference velocity from the count. The algorithm also determines a time period between successive zero crossings, calculates a velocity from the time period, calculates a difference signal between the reference velocity and the velocity, and adjusts the control signal so that the velocity follows the reference velocity. The reference velocity can follow a velocity profile with acceleration portions, coasting portions, and deceleration portions which move an optical pick-up unit from a starting position to a target position.

Abstract: A circuit for tracking error signal detection on an optical storage medium, which has a plurality of digitizers, a plurality of logic comparators and a difference amplifier, is disclosed. The circuit involves summing the signals to be compared and obtaining a delay signal via a delayer. Therefore, the phase difference of the signals is detected via the delay signal to obtain the tracking error signal of the optical storage medium.

Abstract: A recording and/or reproducing apparatus for an optical disc having a pit area where data has been recorded and also having a grooved area where data is to be recorded includes an optical pickup, an error signal generating unit, a shift signal generating unit and a servo controller. The optical pickup includes an objective lens for converging a light beam on a signal surface of the optical disc, a photodetector for receiving the light beam reflected from the signal surface and an actuator for moving the objective lens in a direction perpendicular to its optical axis. The shift signal generating unit is responsive to the output signal of the photodetector to generate a lens shift signal corresponding to the amount of shift of the objective lens from its neutral position. The servo controller drives the actuator based on the lens shift signal or the error signal to move the objective lens along the radial direction of the optical disc.

Abstract: The present invention relates to an apparatus for reading from and/or writing to optical recording media, which has a tracking device, a four-quadrant detector, two summation points and a phase comparator for tracking in accordance with the differential phase detection method, and also various delay elements that can be set by a control device. The object of the present invention is to propose an apparatus of this type which exhibits the best possible compensation of the error in the track error signal and thus in the tracking signal, the said error being caused on account of the lens movement. To that end, the invention provides for analogue delay elements to be arranged upstream and digital delay elements to be arranged downstream of the summation points. The present invention is suitable for apparatuses for reading from and/or writing to optical recording media, such as CD, CDI, CD-ROM, DVD, CDR and others.

Abstract: A method, apparatus, and computer readable medium controlling a servo of a recording and/or reproducing apparatus, using a detected header field signal. An optical recording and/or reproducing apparatus includes a playback signal detector that detects a playback signal and a track error signal from information recorded on a DVD-RAM disc, as picked up by a pickup. A header field signal detecting circuit detects a header field signal by comparing a sampled playback signal for a signal representing the presence of a header field with a reference level and holding the comparison result for a predetermined period of time to generate the header field signal. Accordingly, a tracking servo can be stably controlled by using a tracking driving signal that is not affected by the presence of a header. Also, in a seek mode, the track error signal can be held based on the header field signal to generate a track count signal that is similarly not affected by the header.

Abstract: A repeatable runout compensator that allows a transducer of a servo system in a storage device employing rotating media to follow the eccentricity on the media is disclosed. In exemplary embodiments, the repeatable runout compensator utilizes error values generated by the servo system, which represent the radial and/or axial eccentricity of the media, to generate an output signal having a sinusoidal waveform that is approximately 180 degrees out of phase with the eccentricities and the harmonics of eccentricities on the media.

Abstract: Focusing balance adjustment of adjusting a servo mechanism is executed so that reproduction quality is optimum in a state where a focusing servo is active (#5). Thereafter, tracking balance adjustment of adjusting the servo mechanism is executed so that a tracking balance deviation is cancelled which is an amplitude difference between the upper side and lower side relative to a reference level of a waveform generated in a tracking error signal when the focal point of a light beam applied to the disk crosses a track of the disk (#7).

Abstract: An optical disc drive is used to read and/or write data from/on an optical disc having a data storage layer. The drive corrects electrical offset while reading and/or writing data. The drive updates a correction value based on an electrical offset detected at correcting operation or a value derived using electrical offset values that has been detected and stored, without detecting an electrical offset at correcting operation. Therefore, the optical disc drive can correct the electrical offset less often.

Abstract: In a disk drive for compensating the tilt between a disk including a first identification information area shifted radially outward by a predetermined distance from the center of a track, and a second identification information area shifted radially inward by the same distance, and a head for forming a light spot on the disk, there are provided a unit for determining a sum signal of an output signal from a photodetector obtained when the light spot traces the first identification information area and an output signal obtained when the light spot traces the second identification information area, and a tilt control unit for using the sum signal as an index to control the relative tilt between the disk and the head so as to cause the index to approach an extreme value.

Abstract: A recording information reproducing apparatus is disclosed for performing a searching operation. The recording information reproducing apparatus according to the invention is for reproducing recording information from a recording disc on which information data has been divided and recorded into a plurality of concentric zones. The apparatus selects a suitable one of a tracking servo by a sampled servo system and a tracking servo by a continuous servo system in accordance with a zone for reading information data.

Abstract: An optical disc drive includes: a light source; a focusing section; a focus shifting section for shifting the focal point of light by changing the position of the focusing section perpendicularly to a data storage layer of a given optical disc in accordance with a control signal; a light receiving section for receiving, at multiple areas, the light reflected from the data storage layer and generating light quantity signals; a signal generating section for generating a focus error signal based on the light quantity signals; and a control section for generating the control signal responsive to the focus error signal such that the focal point is transferred to a focus controllable range. The control section generates the control signal such that the focal point is decelerated at a first acceleration and then at a second acceleration. The absolute value of the second acceleration is smaller than that of the first acceleration.

Abstract: An optical information recording medium according to the present invention includes at least one groove track and at least one land track allowing information to be recorded on or reproduced from the groove track and the land track, the groove track and the land track adjoining each other. The optical information recording medium further includes: an identification signal region including a pre-pit array, the pre-pit array indicating identification information concerning the groove track and the land track; and a servo control region disposed ahead of the identification signal region along the groove track and the land track, the servo control region including wobble pits positioned so as to shift to opposite sides of a center line of either the groove track or the land track.

Abstract: Servo circuitry for counting tracks on an optical storage medium is disclosed. The servo circuitry is comprised of a differential phase detector and a digital phase-locked loop. The differential phase detector receives four signals from a quad-photodetector and correlates the four signals into a first correlation signal and a second correlation signal. The digital phase-locked loop receives an adjustable amplification value along with the positive correlation signal and the negative correlation signal. The digital phase-locked loop generates a track count signal based on the adjustable amplification value, the positive correlation signal, and the negative correlation signal. The track count signal represents track crossings on the optical storage medium. The digital phase-locked loop advantageously has an adjustable bandwidth based on the amplification value. The servo circuitry count tracks on both CDs and DVDs.

Abstract: An optical disk in which tracks in which a header region at which positional information showing a recorded position is recorded and a user region at which user information is recorded are alternately arranged, and in which the user region is made to wobble in a direction perpendicular to the arranging direction are formed, and in which a first region in which at least one of a phase, a frequency, and an amplitude of a wobble is different from the other portions is formed at a portion a given length before the header region in playback order within the user region.

Abstract: An optical disc controller of the present invention servo-controls an optical disc device which comprises a disc motor rotating an optical disc and an optical head emitting a light beam for recording data on the optical disc and/or reproducing data from the optical disc. The optical disc controller comprises: a variable clock output section for outputting a plurality of clock signals of different frequencies, and a control section which receives from the optical head a signal indicating a deviation from a predetermined target value to servo-control the light beam of the optical disc device and performs an operation according to the signal indicating the deviation so as to obtain and output a signal indicating a control amount.

Abstract: A boundary crossing detector in a tracking and focus servo system of an optical disk drive is presented. A tracking error signal can be monitored as an optical pick-up unit of the optical disk drive is allowed to move across an optical media in the optical disk drive. If a peak-to-peak value of the tracking error signal changes by a threshold value, than the boundary crossing can be indicated.

Abstract: A disk apparatus has a head, a positional signal detection section that detects a track of a medium, a feedback control section which computes a control signal for moving the head from the location of a positional signal generated by a position signal detector, and a learning control section which generates and stores an unknown function for one disk rotation, which includes a periodic disturbance, in a memory which is comprised of N number of memory cells by a learning algorithm as an approximate function which is approximated by the height of each of several blocks in the medium. The learning control section reads the learning result of the two memory cells at locations which are moved forward for a predetermined amount of time, and interpolates the results so as to generate a periodic disturbance compensation signal.

Abstract: A process for a master optical disk of the present invention is a process for a master optical disk having a physical format in which in a groove-and-prepits-included rewritable optical disk, prepits not being on spirals identical to those of a groove, for example, prepits shifted outward and inward by a half-track pitch from the groove center, are recorded, wherein an acoustooptic-effect-used optical deflector or a field-optical-effect-used optical deflector 101 is disposed on an optical path of a mastering apparatus so that a single laser beam is deflected. This process makes it possible to use a single processing scan to perform laser processing for a plurality of arbitrary points, for example, the center of the groove, and positions shifting inward and outward by a half-track pitch from the center.

Abstract: There is provided an optical recording medium processing apparatus comprising: a carriage including a lens to guide a light beam to a recording medium for moving in a direction extending across tracks on the recording medium; a detector for detecting a TES; and a controller for moving the carriage across the tracks from an innermost circumferential position of the medium or its vicinity, for counting the number of tracks in accordance with a TZC pulse generated by the TES having a predetermined level or higher detected by the detector, and after the carriage has been moved for a predetermined period of time, for positioning the light beam spot on a target track in accordance with the counted number of the tracks. Therefore, the initial seek control process, whereby the carriage is moved from the innermost circumferential position of the medium or its vicinity to the center, can be performed without a position sensor.

Abstract: Track jumping on optical storage media whose address information items invalidate the track error signal (TE) at time intervals is intended to be configured more securely and more reliably. For this purpose, at the end of a coarse jump, one or more correction jumps are carried out if the optical scanner (1) is not presently sweeping over an address information area and the track change frequency of the tracks crossed by the scanner (1) falls below a predetermined value.

Abstract: The beam reflected by the mobile carrier is picked up by an optical pickup having several photodetectors. The elementary signals respectively delivered by the photodetectors are used to formulate two secondary signals, sampled and filtered by a low-pass filter having a cutoff frequency at most equal to a quarter of the sampling frequency. The mutual phase shift of the two secondary signals is representative of the positioning error TE of the beam with respect to the track. The determination of a value of the mutual phase shift comprises the selecting, for each secondary signal, of at least one pair of samples situated outside a predetermined amplitude range around a predetermined threshold. This makes it possible to tag, respectively for the two secondary signals, two transitions of these secondary signals with respect to the threshold and corresponding to one and the same direction of crossing of the threshold.