Abstract: A control apparatus (105) includes a normalizer (400, 401) that performs normalization processing on a first signal and a second signal by using normalization coefficients related to the first signal and the second signal, respectively, a correlation calculator (402) that performs correlation calculation with respect to the normalized first and second signals, and a corrector (403, 800, 801) that corrects correlation data to cancel the normalization processing, and the correlation data is based on an output signal from the correlation calculator.

Abstract: An average servo control method is provided. A target level of at least a servo signal is first detected, which is corresponding to a present condition of the optical disc drive. The target level is then compared with a current level of the servo signal, and a average servo loop gain is adjusted based on the comparison result. A target level calibration may be performed before the gain adjustment. The target level calibration analyzes the servo signal to determine a plurality of preset target levels each corresponding to a different condition. The preset target levels and corresponding conditions are stored as a lookup table. In this way, the target level is acquired based on the lookup table and the present condition.

Abstract: Aspects of the disclosure provide a method for calibrating gains of an optical storage servo system having a plant. The method includes translating a first signal of the plant from a time domain effort signal into a frequency domain effort signal, translating a second signal of the plant from a time domain error signal into a frequency domain error signal, determining a first gain of the optical storage servo system based on the first signal and the second signal, comparing a third signal from an optical disk of the optical storage servo system with a predetermined threshold, and asserting a defect flag when the third signal drops below the predetermined threshold to avoid calibrating the first gain based on the first signal and the second signal.

Abstract: Method and device for generating a control voltage for a position actuator of a disk drive system for displacing a lens of a pick-up unit to a given X-position. The actuator is operated by an open loop control system. First, parameters of the control system are calibrated so that the control system produces a control voltage (Va) from an input position signal (Xact_setp). Then, the control voltage is processed in a feed forward system for generating a processed control signal (Va_p) which is fed to the position actuator for displacing said lens to the X-position. A Z-value corresponding to the axial distance of the lens from a calibrated axial position and a temperature of the pick-up unit are measured. The position actuator operates according to the formula: Xdc=Va—p*K(Temp,Z)/(R(Temp)*C(Temp,Z)).

Abstract: An optical disk reproducing device includes: a signal reproducing section configured to read and decode information recorded on an optical disk by an optical pickup unit, and reproduce the information, wherein the signal reproducing section includes a gain controlled amplifier circuit configured to amplify an radio frequency signal generated from a light receiving element, an automatic gain control circuit configured to control a gain of the gain controlled amplifier circuit, and a signal processing section configured to derive a part of an automatic gain control value generated in the automatic gain control circuit, and generate a control signal for adjusting one of an optical system path and a detection system path for controlling the optical pickup unit.

Abstract: An apparatus and a method for compensating periodic signal in an optical disc drive are described. The control apparatus includes an amplitude processing unit, a phase processing unit, a wave generator, a first switch module and a second switch module. The amplitude processing unit processes the amplitude of the input signal based on a reference signal for generating an amplitude signal. The phase processing unit processes the phase of the input signal based on the reference signal for generating a phase signal. The first switch module switches the amplitude signal to select one of the amplitude value and a predetermined amplitude value. The second switch module switches the phase signal to select one of the phase value and a predetermined phase value. The wave generator generates a compensated wave signal based on the selected amplitude value and the selected phase value, and outputs the compensated wave signal.

Abstract: An optical disc device including: a light source; an object lens to focus light emitted from the light source on an information recording surface of an optical disc; a movable lens that is arranged on an optical path between the light source and the objective lens and arranged such that position thereof is adjustable along a direction of a light axis; a lens moving portion to move the movable lens along the direction of the light axis; a tracking servo system which makes a beam spot that is formed of the light from the light source through focusing by the objective lens keep on track of the optical disc; and a control part which controls gain of a servo loop of the tracking servo system is made temporarily larger when the movable lens is moved by the lens moving portion in comparison with a case where moving of the movable lens by the lens moving portion is not performed.

Abstract: The optical disk device includes a generation means and a LC servo means. The generation means generates a lens error signal based on an electrical signal output from a pickup head. After amplifying the lens error signal with a predetermined gain, the generation means outputs the lens error signal. The LC servo means performs lens center servo control based on the lens error signal. The optical disk device further includes a measurement means which measures, before the lens center servo control, a first and a second amplitude values of the lens error signal. The measurement means calculates a current gain based on the first and second amplitude values, the latest gain which is currently set, and a predetermined target amplitude value. Then the measurement means sets the current gain to the generation means.

Abstract: When a focus error signal (FE signal) is detected with an astigmatic method, a track crossing component leaks into the FE signal. Another detection method for the FE signal would reduce the leaking signal, but is not applicable when the light use efficiency decreases. An optical crosstalk correction amount determination unit (1000) determines a correction amount to correct an output of a tracking error detection unit (120) based on optical crosstalk from a TE signal to an FE signal occurring in reflection light from an optical disc (102) when a spot crosses a track. An output of the tracking error detection unit (120) is multiplied by the determined correction amount, and added to an output of the focus error detection unit (118). A focus control unit (138) executes focus control based on the addition result. This effectively reduces a TE signal component that leaks into the FE signal due to optical crosstalk.

Abstract: Disclosed herein is an optical disk playback apparatus including: a signal playback device configured to read and decode information recorded to an optical disk through an optical pickup unit in order to reproduce the information; the signal playback device including a signal generation circuit, a first signal processing device, a second signal processing device, a modulator, a switch, an analog to digital converter, and a third signal processing device.

Abstract: A signal processing device for optical disks includes a reflected light process section configured to convert reflected light received by an optical pickup into an electric signal based on a first gain, wherein the optical pickup emits laser light to an optical disk and receives reflected light from the optical disk; a servo signal generation section configured to generate a servo signal by using the electric signal generated by the reflected light process section; a servo signal control section configured to control the servo signal so that a change in the amplitude of the servo signal, in response to an increase or decrease of the amount of the reflected light from the optical disk, is suppressed using an attenuator that attenuates the servo signal generated by the servo signal generation section by a factor of a second gain; and a gain setting section configured to set the first gain to the reflected light process section and the second gain to the servo signal control section substantially simultaneously.

Abstract: In a device for controlling a focus to an optical disc having a land section and a groove section, the control is performed so as to avoid a focus step difference at a land-area/groove-area switching point. When performing write-in or readout of data to an optical disc on which a land area and a groove area are continuously formed, using an optical pickup, there are provided a land learning unit (1) for determining a focus position in the land area, a groove learning unit (2) for determining a focus position in the groove area, and a focus position calculation unit (3) for determining a focus position in an area where the land area and the groove area are switched, and the focus position of the optical pickup is moved so that it is located at the third focus position when the switching signal is inverted according to the switching between the land area and the groove area.

Abstract: A method of reducing power dissipation in a variable-gain photo-detector circuit is described. The variable-gain photo-detector circuit has an output to output a main spot signal and at least one side spot signal. The main spot (M) and the side spot (Si or S2) are formed by separating a light beam into a main beam and at least one side beam and focusing the main beam on the main spot (M) and the side beam on at least one side spot (Si or S2) on an optical record carrier The method processes the main spot signal with a first averaging circuit having a first cut-off frequency. The side spot signal is processed with a second averaging circuit having a second cut-off frequency. The second cut-off frequency is lower than the first cut-off frequency. The above technique reduces power dissipation in the variable-gain photo-detector circuit and is useful for all optical devices.

Abstract: A method for enhancing the optical initializing operation comprises: sending a radial error signal from an optical pick-up unit to a radial error signal calibration unit; sending the radial error signal from the optical pick-up unit to an offset adjuster; sending a calibrated radial error signal from the radial error signal calibration unit to the offset adjuster and a gain adjuster; sending a radial actuator (RA) signal from the radial error signal calibration unit to activate a radial actuator during an initialization or a period for calculating RE signal calibrating parameters.

Abstract: Deterioration of error rate at reproduction time is prevented even if a photodetector with a poor characteristic is included. An optical pickup unit (3) is provided with 4 photodetectors. A controller (13) obtains an error correction result of a reproduced signal, which is reproduced based on an RF signal generated while changing combination of the 4 photodetectors at startup time, and determines a combination at reproduction time in accordance with the obtained error correction result, to be given to an RF amplifier unit (10). The controller (13) is provided with a counter that counts for a fixed time period the error correction result per combination of the photodetectors, a comparator that compares a count result of the counter with a threshold set in advance, and an output controller that judges whether or not to use a combination of the photodetectors based on a comparison result of the comparator and performs change control of the combination of the photodetectors, of which there is a plurality.

Abstract: A method of adjusting gain balance of an optical transducer includes the following steps. First, two external gains are predetermined. Next, the projection position of a reflection spot is adjusted toward one side of the optical transducer, and the current output values of the optical transducer each corresponding to one of the external gains are measured, respectively. Next, the projection position of the reflection spot is adjusted toward the other side of the optical transducer, and the current output values of the optical transducer each corresponding to one of the external gains are measured, respectively. Then, a gain balance value of the optical transducer is adjusted, and is set as the external gain. Next, the projection position of the reflection spot is adjusted. Finally, the projection position of the reflection spot, where the current output value of the transducer is equal to 0, is locked to complete the adjustment rapidly.

Abstract: An information reproducing apparatus (1) is provided with: a detecting device (11) for irradiating an information. recording medium with laser light (LB) and detecting reflected light as a detection signal, the information recording medium including a first recording layer (L0) and a second recording layer (L1); a high pass filter (14) for performing a filtering process on the detected detection signal; and a reproducing device (15, 16) for performing a reproduction process of the filtered detection signal to reproduce the data, the high pass filter attenuates a fluctuation component of the detection signal, caused by a relative eccentricity between the first recording layer and the second recording layer, by a first attenuation amount (34dB) or more.

Abstract: In a signal reproducing device, for securing the stability in the steady state while enhancing the response of automatic gain control, a variable gain amplifier 109 adjusts the amplitude of a reproduction signal outputted from a head amplifier 108. A gain control section 112 increases/decreases the gain in the variable gain amplifier 109 by a predetermined change amount according to the large-small relationship of the comparison result outputted from a comparator 111. The gain change amount control circuit 113 controls the change amount of the gain in the gain control section 112 according to the frequency of inversion of the large-small relationship of the comparison result outputted from the comparator 111.

Abstract: A driver circuit for use with a variety of OPU circuits has both a single-ended input and a differential input. The single-ended input is coupled to a single-ended signal path having a variable gain stage and a variable level shifter. The differential input is coupled to a differential signal path having a variable gain stage and a variable level shifter. The single-ended signal path and the differential signal path may be selectively coupled to an output. The respective variable gain stages and variable level shifters can be adjusted so that an output signal at the output has a desired dynamic range.

Abstract: An optical disk apparatus includes a signal detection unit which detects a signal corresponding to a wobbling guide groove formed on an optical disk, a timing signal generating unit which generates first and second timing signals in accordance with an amplitude level of the signal detected, a photodetector which detects reflective light from the optical disk, and a wobble signal generating unit which outputs as a wobble signal a signal which is amplified with a low gain amount by the first timing signal in a case where an arithmetic signal, which is generated for the wobble signal on the basis of a signal detected by the photodetector, is at a high amplification level, and outputs as the wobble signal a signal which is amplified with a high gain amount by the second timing signal in a case where the arithmetic signal is at a low amplification level.

Abstract: An optical disk apparatus according to the present invention is capable of reading data from an optical disk 102 which has a plurality of information recording layers, including a first information recording layer whose distance from a disk surface is relatively small and a second information recording layer whose distance from the disk surface is relatively large. This optical disk apparatus includes: a focus control section 117 for causing a converging point of the light beam to be positioned on an arbitrary information recording layer of the optical disk 102; a tracking control section 118 for causing the converging point of the light beam to be positioned on a predetermined track of the information recording layer; and a gain switching section 108 capable of changing gain characteristics of at least one of the focus control section 117 and the tracking control section 118.

Abstract: An optical disk device includes a optical pickup head which emits a laser beam to an optical disk and detects light reflected therefrom, a signal output unit which outputs at least a servo signal and RF signal in accordance with the detected light, a gain control unit which determines the type of the optical disk from identification information recorded thereon, and sets first and second adjusted gains for a data recorded region and data unrecorded region, when determining that the optical disk is of a type wherein a light reflectance is higher in the data recorded region than in the unrecorded region, and a gain adjustment unit including a memory storing the first and second adjusted gains, the gain adjustment unit adjusting the gain of the servo signal in the data recorded region, using the first adjusted gain, and in the data unrecorded region, using the second adjusted gain.

Abstract: A signal processing device for optical disks includes a reflected light process section configured to convert reflected light received by an optical pickup into an electric signal based on a first gain, wherein the optical pickup emits laser light to an optical disk and receives reflected light from the optical disk; a servo signal generation section configured to generate a servo signal by using the electric signal generated by the reflected light process section; a servo signal control section configured to control the servo signal so that a change in the amplitude of the servo signal, in response to an increase or decrease of the amount of the reflected light from the optical disk, is suppressed using an attenuator that attenuates the servo signal generated by the servo signal generation section by a factor of a second gain; and a gain setting section configured to set the first gain to the reflected light process section and the second gain to the servo signal control section substantially simultaneously.

Abstract: An automatic gain control (AGC) controls the signal amplitude at the input to an analog to digital converter (ADC) input by applying a gain that produces a desired overall amplitude resolution of the patterns actually presented by the signal delivered by the ADC converter. Short RLL patterns will have sufficient resolution for reliable extraction as a result of having sufficient overall amplitude, which thereby strengthens the ability of the read channel to correctly extract data. Moreover, the system determines correct AGC settings responsive to measurements of user data parameters. The system also detects and corrects for DC offsets in the signal whose gain is controlled.

Abstract: In order to cancel an offset caused by a variation of a signal inputted from an optical pickup, variations of elements in an integrated circuit, etc., a calibration circuit which generates and feeds back an offset adjustment amount that makes the offset zero by a comparison with a reference value, and an offset adjustment circuit that makes the offset zero using the fed-back control signal are provided in an analog front-end LSI. The offset adjustment by the calibration circuit is automatically done in response to commands supplied from a digital signal processing LSI, a host control device, etc. On the other hand, as for a signal on which arithmetic processing such as gain control, addition and subtraction, is performed, the offset adjustment is performed by sending the offset adjustment amount obtained by an arithmetic operation performed by software processing of the digital signal processing LSI to the analog front-end.

Abstract: An optical disk apparatus decides reading time parameters to be set in a tracking error signal generation part at the reading time by applying a laser light of record power to an optical disk. A state where the laser light of record power is applied to the optical disk is artificially produced based on the reading time parameters decided herein. In the state, the recording time parameters to be set in the tracking error signal generation part at the recording time are decided.

Abstract: The invention relates to a method for optimized tracking of an optical scanner along a track of an optical recording medium, the track having information markings arranged in dense succession, and also having fundamental changes in properties in significantly lower density. The method has the following steps: formation of a track error signal, detection of the occurrence of fundamental changes in properties of the track, formation of an offset value from the comparison of the value of the track error signal that occurs shortly before and shortly after the fundamental change in properties, formation of the track error signal, taking account of the offset value and repetition of the aforementioned steps.

Abstract: A Bemf detect circuit is configured for modeling Bemf error via calculation of time correlations associated with two or more different non-calibrated sense resistor gain values to derive a calibrated sense resistor gain value. A method is provided for calibrating a Bemf detector circuit by setting a sense resistor gain to a plurality of different gain values, observing Bemf sample values for each of the gain values, and deriving a calibrated gain value by non-iteratively modeling the relationship between the gain values and the associated Bemf sample values.

Abstract: In a processing section 4, allowable gain-value range defining unit 41 measures a gain value k corresponding to a level ratio between an MPP signal and an SPP signal generated by a tracking error signal generating circuit 3 to define an allowable range of the gain value, and eccentricity measuring unit 42 measures an eccentricity of an optical disk. If the eccentricity is determined to be greater than or equal to a predetermined value by eccentricity determining unit 43, gain-value defining unit 44 selects a minimum value of the gain value k to define the minimum value as a gain value k of an amplifier 37. On the other hand, if the eccentricity is determined to be less than the predetermined value, the gain-value defining unit 44 selects a central value of the gain value k to define the central value as the gain value k of the amplifier 37.

Abstract: The address signal position detection apparatus comprises a photodetector, a first and second adders which generate, from the output signals from the photodetector, two signal sequences whose phases change from each other according to a tracking error of a light spot, a phase difference detection circuit for detecting the phase difference from the two signal sequences, and a phase difference signal processing unit which generates an address signal position using the phase difference signal detected by the phase difference detection circuit, and detects an address signal position by providing threshold values with respect to the detected phase difference, thereby enabling a stable detection of the address signal position even when a DC symmetry in a difference signal of a reproduced signal is imperfect in an optical disk using the land/groove recoding method.

Abstract: An optical disk system includes at least one photo detector connected with a variable gain amplifier, a slicer, and a generator which is in the feedback path between the slicer and amplifier. A differential time delay detector provides the output of the optical disk system. The generator is configured for controlling the amplifier non-linearly so that time constants of the control loop of the amplifier which depend upon the level of the input signals are compensated and the timing behavior of the control loop of the amplifier has a more continuous character. A capacitor forms part of an integrator for making the mean value of the output voltage signal of the slicer equal to zero.

Abstract: A tracking controller includes a tracking error detecting section and a tracking control section. The tracking error detecting section generates and outputs a tracking error signal that represents how much the focal point of a light beam has shifted from a target track on a storage medium. The tracking control section generates a drive signal in response to the tracking error signal so as to move the light beam such that the focal point of the light beam is located right on the target track. The gain of at least one of the tracking error signal and the drive signal is switched depending on whether or not the focal point of the light beam is located on a recorded area of the storage medium on which data has already been written.

Abstract: In a CLV(constant linear velocity) or MCLV(substantially constant linear velocity)-type optical disk apparatus, instability of servo at inner and outer circumferences of an optical disk is prevented by adjusting a servo-loop gain of tracking servo control or focus servo control in accordance with the radial-direction position of an optical spot, i.e., in accordance with the rotation frequency of the optical disk.

Abstract: An optical disk device includes a optical pickup head which emits a laser beam to an optical disk and detects light reflected therefrom, a signal output unit which outputs at least a servo signal and RF signal in accordance with the detected light, a gain control unit which determines the type of the optical disk from identification information recorded thereon, and sets first and second adjusted gains for a data recorded region and data unrecorded region, when determining that the optical disk is of a type wherein a light reflectance is higher in the data recorded region than in the unrecorded region, and a gain adjustment unit including a memory storing the first and second adjusted gains, the gain adjustment unit adjusting the gain of the servo signal in the data recorded region, using the first adjusted gain, and in the data unrecorded region, using the second adjusted gain.

Abstract: Comparators compare the amplitudes of a DPD tracking error signal indicating the phase difference between the detection signals supplied from a photodetector, and a PP tracking error signal indicating the level difference between the detection signals with the reference values, respectively. A gain control amplifier mutes a tracking error signal with the maximum amplitude smaller than a reference value.

Abstract: An offset adjusting circuit for an optical disc comprises a plurality of offset-adjustment differential operational amplifiers, each of the amplifiers having an input terminal to which an output signal of an optical pickup is input and another input terminal to which a control voltage is applied, an adding circuit that adds output signals of the offset-adjustment differential operational amplifiers, an A/D converter that outputs a digital signal based on an output signal of the adding circuit, and a control voltage adjuster that varies the control voltage applied to the offset-adjustment differential operational amplifiers based on the digital signal so as to remove an offset.

Abstract: A controller includes a servo-controller for performing nonlinear and linear control of the read/write position according to an error signal to drive an actuator for driving the pickup; a switch for switching the servo-controller from open-mode to closed-mode according to the error signal; and an adjuster for adjusting the gains of the nonlinear and linear control so that the nonlinear control component is larger than the linear control component at the time of switching and the linear control component is larger than the nonlinear control component after the elapse of a predetermined time from the time of switching.

Abstract: According to the present invention, an optical pickup device forms one main spot, a first subspot, and a second subspot by irradiation of light on an optical disk having a groove part and a land part. The optical pickup device includes operation circuits which indicate a deviation between each of the optical spots and a track, and ? detecting means for detecting such an ? value that a difference in absolute value between SPP1 and ?SPP2 falls in a preset range, where an AC amplitude of a push-pull signal of the first subspot is SPP1, and an AC amplitude of a push-pull signal of the second subspot is SPP2, wherein SPP1??SPP2 (? is a constant) is a land/groove discriminating signal. With this, in the optical pickup device for recording and reproducing information on/from the optical disk having a land/groove part, it is possible to generate a land/groove discriminating signal and a tracking error signal without an offset, thereby performing excellent tracking control.

Abstract: Regions A–F of photodetectors output electric signals a–f respectively, in accordance with an amount of reflected light from an optical disc 1. The electric signals a–f are input to A/D converters through an RF amplifier unit respectively. An arithmetic circuit subjects the electric signals a–f to arithmetic processing, so as to generate a focus error signal FE and a tracking error signal TE. A CPU measures a DC level of an output signal from the A/D converter, and transmits control signals OCa–OCf to a variable resistor in the RF amplifier unit so that a difference between the DC level and a median in a dynamic range of the A/D converter attains “0”. The CPU transmits control signals GCa–GCf to a variable resistor in the RF amplifier unit so that output amplitude of an output signal is within the dynamic range.

Abstract: An electronic circuit is provided which can autonomously handle an input current (Ii) having a relatively wide dynamic range without being overdriven. The electronic circuit comprises an amplifier stage (AMPST) having an input (IP) for receiving the input current (Ii) and an output (OP) for supplying an output current (Io), such that, during operation, the strength of the output current (Io) increases in response to an increasing strength of the input current (Ii) as long as the strength of the input current (Ii) has not exceeded an input reference level. The strength of the output current (Io) is kept approximately constant when the strength of the input current (Ii) has exceeded the input reference level but has not exceeded a further input reference level. The strength of the output current (Io) decreases in response to an increasing strength of the input current (Ii) when the strength of the input current (Ii) has exceeded the further input reference level.

Abstract: An optical disc device for changing intensities of light beams illuminated on an optical disc. The optical disc device comprises the following elements. A photo detecting device divided into a plurality of photo detectors is used for detecting the reflected light beams illuminated on an optical disc. A plurality of amplifiers is used for changing gains to respectively amplify the output signals of the photo detectors when recording and reproducing on/from the optical disc. A calculating device is used for calculating the output signals of the amplifiers to generate the servo signals. By adding the correction offset signals for correcting the offset voltages of the amplifiers and the photo detectors to the amplifiers, the correction offset signals are amplified. It is, therefore, not necessary to change the correction offset voltages even though the gain of the amplifier is changed and not necessary to change the offset voltage and is independent of the gain-switching of the amplifier.

Abstract: On an optical disk, a string of a plurality of pits having two different depths is formed. Quantity of light reflected from the pit string is detected by a photoreceptor element, and based on the detected quantity of reflected light, a pit depth detecting unit detects depth of each pit. Based on the detected quantity of reflected light, a servo signal generating unit generates a tracking servo signal. An output control unit supplies the generated tracking servo signal when a pit of such depth that is to be reproduced is tracked, and holds and supplies an immediately preceding tracking servo signal when a pit of different depth is being tracked, based on the result of detection by the pit depth detecting unit.

Abstract: Disclosed is a method and apparatus for controlling the record and reproduction of optical record medium in which plural non-record regions having different phase are arranged between recordable data regions for the distinction in the shape of the data region. The method and apparatus performs the servo using focus error signal and tracking error signal averaged by the low pass filter at the header region of the optical disc. Especially, the tracking servo is performed by holding a fixed DC off-set value at the header region existing on the L/G switching or holding the tracking error value of the previous same track region. As a result, the exact header region is detected, the track sliding phenomenon is removed, and the tracking servo is stabilized, resulting in preventing the degeneration of the record and reproduction characteristics.

Abstract: An eccentricity compensating apparatus of a disk drive servo system using frequency response characteristics of an actuator actuating a head to a position on a disk to read data on or reproduce data from the disk. The apparatus includes an error detector that detects a position error between a reference head position and an actual position of the head on the disk and a first compensation controller that receives the position error from the error detector and changes the actual position of the head to compensate for the position error.

Abstract: A recording and playback apparatus comprises, a drive unit configured to rotate an optical recording medium including a recording track, a recording and playback unit configured to irradiate a light beam on the recording track, and to perform recording and playback of an information detected a reflected light beam by an upside photo detection area and a downside photo detection area bisected in a tangential direction of the recording track, and a recording and playback controller configured to generate a position tracking signal based on the reflected light beam detected by the upside photo detection area and the downside photo detection area, and to compensate a level of the position tracking signal when the position tracking signal and a record mark on the recording track are detected.

Abstract: An optical system of an optical recording apparatus forms a main spot and sub-spots preceding and succeeding the main spot on a signal recording medium. The optical system is set such that the sub-spot is shifted from the main spot in the direction orthogonal to a signal track by a distance expressed by an expression (2k?1)P/4(k=natural number), in which P denotes a distance between adjacent signal tracks on the signal recording medium. Thus, the sub-spot succeeding the main spot can be used to effectively read the state of a signal recorded on the signal recording medium by the main spot.

Abstract: A method and device are provided for jitter enhancement in an optical disc system. The optical disc system generates a signal that includes an effective component having a first slew rate, and a pre-pit component having a second slew rate larger than the first slew rate. The signal is fed to a slew rate control module having a predetermined slew rate that is larger than the first slew rate and smaller than the second slew rate. The slew rate control module outputs a component of the signal having a slew rate not larger than the predetermined slew rate, and suppresses a component of the information signal having a slew rate larger than the predetermined slew rate.

Abstract: A method of adjusting the focus control for an optical storage system where light is reflected from a surface towards a lens. The method includes receiving a reflected light in the form of a spot, dividing the spot into a plurality of areas, generating an adjustment signal based on the relationship between the plurality of areas to determine the variation between the center point of the spot and a desired center point for the spot, combining the adjustment signal with an existing focus error signal to obtain a modified focus error signal, and utilizing the modified focus error signal to control the position of the sensor.

Abstract: The invention provides a method for adjusting a speed-detection device for an object lens in an optical pickup head. The invention provides an adjusted optical disc drive, wherein the optical pickup head is accelerated/decelerated and the speed-detection device outputs a standard signal level. Next, the optical pickup head of an unadjusted optical disc drive is accelerated/decelerated under the same condition, and the speed-detection device outputs a speed signal level. Finally, the gain of a programmable gain amplifier is adjusted until the speed signal is equal to the standard signal.

Abstract: An optical storage system includes a pickup head for picking up data from a storage medium. Firstly, the maxima of a tracking error signal and runout are obtained in a calibration procedure in a close loop formed by an optical pickup head, a pre-amplifier, a compensator, a band-pass filter and a maximum detector. A calibration factor is then defined and derived by using the obtained maxima and nominal factors of a power amplifier and the optical pickup head of the optical storage system. The path formed by the series-connected band-pass filter and maximum detector is then disabled, while the calculated calibration factor is then stored in the compensator. The optical storage system may operate in a close loop formed by the optical pick head, pre-amplifier, compensator, a power amplifier under a normal operation procedure so that the optical storage system may record or read data onto/from an optical disc under the compensation provided by the calibration factor.