Abstract: A control system including a filter module generates a filtered disturbance signal based on a disturbance signal and a transfer function of the filter module. A set point adjustment module generates an adjusted set point signal based on a set point signal and the filtered disturbance signal. A servo control module generates an error signal based on the adjusted set point signal and a position feedback signal. A filter adjustment module generates a filter adjustment signal based on the disturbance signal and the error signal. The filter adjustment signal adjusts the transfer function.

Abstract: An object of this invention is to measure the tilt quantity of, and perform a tilt control on, an optical disc accurately without depending on the rotation control method. An optical disc drive includes: a motor for rotating an optical disc; an optical system for irradiating the optical disc with a light beam; a moving mechanism for moving the optical system along the radius of the optical disc; a focus control section for controlling movement of the optical system perpendicularly to the optical disc based on drive values, thereby focusing the light beam onto a storage layer of the optical disc; and a tilt control section for measuring the tilt quantities of the storage layer at multiple different radial locations on the optical disc based on drive values for the respective radial locations when the focus control section focuses the light beam there.

Abstract: An optical disk apparatus driving an optical disk includes a tilt-angle adjusting unit configured to adjust a tilt angle indicating the tilt of an optical axis of laser light emitted from a pickup to detect an optimal tilt angle at which a traverse signal has the maximum amplitude and a storing unit configured to store information about the optimal tilt angle. When the optical disk has multiple recording layers on one side, the tilt-angle adjusting unit adjusts the tilt angle with respect to each of the multiple recording layers to detect the optimal tilt angle and the storing unit stores information about the optimal tilt angle with respect to each of the multiple recording layers. The tilt angle with respect to each of the multiple recording layers is controlled in accordance with the information about the optimal tilt angle with respect to each of the multiple recording layers.

Abstract: An optical disc apparatus varies a tilt angle of an optical pickup from inward to outward of an optical disc, and stores a then obtained TE (Tracking Error) signal in a memory of a control circuit. The control circuit extracts amplitude values of the TE signal at tilt angles at predetermined angular intervals from the TE signal stored in the memory, and temporarily stores the extracted amplitude values in the memory, and further uses the stored amplitude values to determine a cubic curve to approximate the extracted amplitude values based on the least squares method. After determining the cubic curve, the control circuit sets a tilt angle corresponding to a maximum point of the cubic curve as an optimum tilt angle. This makes it possible to obtain a proper optimum tilt angle even with a surface-vibrating optical disc which much vibrates in the thickness direction during rotation.

Abstract: An optical axis shift correcting device is provided in an optical information device including irradiation means (11) for applying a laser, an optical system (12, etc.) for guiding a laser applied to an optical disc (2) having a recording track, and a light reception element (17) for receiving the light from the optical disc generated by the guided laser via the optical system. The optical axis shift correcting device includes jitter acquisition means (191) for acquiring a jitter amount of a signal obtained according to the received light, optical axis modification means (201, etc.) for modifying the direction of the optical axis with respect to the light reception element, and control means (100, etc.) for controlling the optical axis modification means so as to reduce the shift when the acquired jitter amount exceeds a predetermined threshold value.

Abstract: An optical disc apparatus includes a first lens shift amount detection unit which detects a first lens shift amount for a objective lens, on the basis of a push-pull signal which is generated in a state in which a main body of the optical disc apparatus is horizontally disposed, a memory unit which stores the first lens shift amount which is detected by the first lens shift amount detection unit, a second lens shift amount detection unit which detects a second lens shift amount for the objective lens on the basis of the push-pull signal at a time of recording/reproduction on/from an optical disc, and an addition unit which constantly adds to a tracking actuator of the objective lens a lens shift corresponding to a difference between the first lens shift amount stored in the memory unit and the second lens shift amount.

Abstract: An aberration correction lens 4 is disposed in a space between a laser light source 3 and an objective lens 5, and a lens holder 10 is frictionally coupled to a drive shaft 7 via a frictional holding body 8. A piezoelectric element 6 is provided to one end of the drive shaft 7. The piezoelectric element 6 extends and contracts in response to an applied voltage. The lens holder 10 is moved relatively with respect to the drive shaft 7 in the drive shaft direction by varying a change rate when the applied voltage to the piezoelectric element 6 is increased and decreased.

Abstract: An optical disk recording and reproducing apparatus includes a focus unit that focuses an irradiation light beam on an optical disk having data recording layers and tracks; a drive unit that changes a direction of the beam by moving the focus unit; a tilt control unit that detects a tilt amount of the optical disk, computes a control operation amount in a band wider than a rotation frequency of the optical disk based on the tilt amount, and controls the drive unit to move the focus unit based on the control operation amount. The tilt control unit holds a control state of the control at an immediate pre-state of an inter-layer jump in which the beam is moved to a different data recording layer or a track jump in which the beam is moved to a different track during the inter-layer jump or the track jump.

Abstract: A hologram recording and reproducing apparatus minimizes reproduction errors by servo control on the tilting of a reference beam relative to a hologram recording medium. The apparatus includes an optical detector for servo control and an optical sensor for reproduction signal conversion. A pixel pattern generator generates, on a wave surface of the recording beam, a discretely distributed recording pixel pattern corresponding to the information to be recorded, and a specifically shaped and localized servo pixel pattern for the servo control. A beam splitter splits the reflected beam from the hologram recording medium into a reproduction beam directed to the optical detector for reproduction signal conversion and a servo beam directed to the optical detector for servo control. A servo controller controls the tilting of the reference beam relative to the hologram recording medium, based on an output signal from the servo control optical detector.

Abstract: For achieving an improvement on recording/reproducing quality of information, with enabling more adequate tilt adjustment, even for an optical disc to be used under a circumstance having a large temperature change, an optical disc apparatus for conducting recording or reproducing of video information onto/from the optical disc 2, through buffers 17 and 18, while conducting a tilt adjustment through a learning of a tilt amount, comprises a temperature sensor 4 for detecting temperature within an optical pickup 1, wherein it is determined on whether a relearning of the tilt amount of the optical pickup, upon basis of a change of temperature detected, a movement amount of the optical pickup between the time when a previous learning is done and the time when a present learning is done, and a remaining memory capacity of the buffers.

Abstract: An optical scanning device for scanning an information carrier. The device includes an array optical element arranged to generate an array of radiation spots from an incident radiation beam, for the scanning of the information carrier. The device further includes an aberration optical element arranged to apply a predetermined optical aberration to the radiation for correction of optical aberration in the radiation spots.

Abstract: A compatible optical pickup includes a light source which emits a first light beam having a wavelength for a first recording medium; a twin light source which emits second and third light beams respectively having wavelengths for second and third recording media; a first objective lens which condenses the first light beam to form a light spot for recording and/or reproduction of the first recording medium; a second objective lens which condenses the second and third light beams to form light spots for recording and/or reproduction of the second and third recording media; an actuator which drives the first and second objective lenses; a first photo-detector which receives the first light beam reflected from a recording medium to detect an information signal and/or an error signal; and a second photo-detector which receives the second and third light beams reflected from a recording medium to detect information signals and/or error signals.

Abstract: A rotation correcting apparatus has a tracking servo controller which generates a tracking signal to perform a tracking servo control for guiding an optical beam spot outputted from a pickup to tracks of an optical disk and a track jump control for moving the optical beam spot to a certain track; a feed motor controller which controls a feed motor for moving the pickup to radius direction of the optical disk; a storage which stores signal component with a prescribed frequency band including a rotation frequency of the optical disk, the signal component being included in an output signal of the tracking servo controller; and a combination unit which combines the signal component stored in the storage with the tracking signal to generate an ultimate tracking signal for the tracking servo control and the tracking jump control, wherein the feed motor controller controls the feed motor based on the tracking signal generated by the tracking servo controller without using the signal component stored in the storage.

Abstract: An optimizing of a gain in a servo control loop (21) of an optical drive is performed for the control of an actuator for focusing and tracking a laser beam (10) for reading or writing data from/to optical discs (1), wherein the actuator is controlled by a servo controller (20) in the control loop (21), by means of an algorithm performing the steps: predetermining a reference oscillation level for the servo control loop (21), iteratively checking if a power output from the control loop (21) used as an dissipation level value is less than the reference oscillation level, increasing the gain in the servo control loop in each iteration step until said dissipation level value is equal to or greater than the reference oscillation level and then decreasing the gain in the control loop by a margin value.

Abstract: The present invention provides an optical pickup device and an information recording/playback apparatus capable of correcting aberration of an optical beam in correspondence with a plurality of recording formats of optical disks while realizing miniaturization of the device and the apparatus and reduction in manufacturing cost. A collimator lens (161) is disposed on an optical axis in correspondence with a BD. By moving the collimator lens (161) in a direction parallel with the optical axis, spherical aberration is corrected in accordance with the BD. A collimator lens (162) is disposed on an optical axis in correspondence with a CD and a DVD. By moving the collimator lens (162) in a direction parallel with the optical axis, spherical aberration is corrected in accordance with the CD and DVD. The collimator lenses are integrally held by a lens holder (163). A step motor (164) moves the lens holder (163) so that the collimator lenses (161, 162) move in directions parallel with the optical axes.

Abstract: To obtain a construction in which unnecessary learning can be avoided and optimal and stable positioning control can be carried out upon introducing a repetition control method in an optical disc device. A defect detection unit (5), a disc position detection unit (9), and a disc rotation speed detection unit (10) are provided in a disc control device comprising a repetition control device to control storing to and reading from a memory unit (3) used as a learning memory and to vary the number of memory divisions of the memory unit (3) on the basis of detection by the detection units. When components having periodicity are apparently due to partial surface runout or partial eccentricity, they are stored in the memory unit (3) by increasing the resolution and microscopic noise components and noise components having no periodicity are not stored in the memory unit (3).

Abstract: An apparatus and a method removing offset of a Phase Lock Loop (PLL) circuit in a disc drive without using a disc when data playback is performed, the apparatus including an ENDEC module and a PLL circuit. The ENDEC module outputs a binary signal if an offset removal mode is set. The PLL circuit removes the offset of the PLL circuit by comparing a phase of the binary signal with a phase of a channel bit clock signal. Therefore, a time to remove the offset of the PLL circuit is reduced and the possibility not to remove the offset of the PLL circuit due to a damaged disc is prevented.

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: A system for tracking and segregating repeated defects on media disks as tabled data in disk drives is disclosed. The disks have the same defects as the sub-master from which they are formed. Likewise, the sub-masters have the same defects as the master from which they are formed which, in turn, are passed down to the disks themselves. This information is recorded in the disk drives to avoid read/write operations in the affected sectors of the disks. In addition, the order and production quantities of sub-masters and disks made are tracked since replication performance decays over time.

Abstract: An optical head apparatus of an optical information recording/reproducing apparatus is provided with a light source. An objective lens focuses an output light emitted by said light source on a disc optical recording medium for which a groove or a pit for tracking is provided. T photo-detector receives a reflected light reflected by said optical recording medium. A polarizing splitter unit splits said output light and said reflected light. A quarter-wave plate disposed between said polarizing splitter section and said objective lens. A birefringence compensating unit reduces a change in an amplitude of a track error signal caused by birefringence in a protective layer of said optical recording medium.

Abstract: An apparatus which stabilizes an operation of a disc driver in a mode conversion setting section includes a pickup which reads information from a disc that is inserted into the disc driver, a filter which performs a low-pass filtering of a servo error signal that is generated during an operation of the pickup, a selector which selects one of the servo error signal and the low-pass filtered servo error signal from the filter and outputs the selected servo error signal to drive the pickup using the selected servo error signal, and a control signal generator which generates a signal to control the selector to select the low-pass filtered servo error signal in a mode conversion setting section of the disc driver. Accordingly, a defocus and a detrack can be prevented in the mode conversion setting section of the disc driver.

Abstract: A method for reading data from a track (3) of a data carrier (2) comprises the following steps. During reading, a tracking quality parameter (Q) is determined, relating to a track portion (3Px) of the data carrier from which the data is being read. The tracking quality parameter is stored in a tracking performance memory (30) in relation to the corresponding track portion (3Px). If a jump back to a previously read track portion appears to be necessary, said tracking performance memory (30) is consulted to determine a target track portion (3P(x-n)) having a sufficient value of the tracking quality parameter (Q); then, a jump back (JB) to the target track portion (3P(x-n)) thus determined is performed.

Abstract: A method and apparatus for controlling the tilt between the optical axis of an optical pick-up head and an optical disc applied in an optical disc drive is provided. A trapezoidal-wave signal in a radio frequency signal is received, wherein the trapezoidal-wave signal includes a rising edge and a falling edge. And a slope sum is calculated and so is an amplitude or a time domain area of the trapezoidal-wave signal. Then, a tangential tilt control parameter is generated according to the slope sum, and a radial tilt control parameter is generated according to the amplitude or the time domain area of the trapezoidal-wave signal. Thus, the optical disc drive is controlled according to the tangential tilt control parameter and the radial tilt control parameter for the optical axis of the optical pick-up head to be perpendicular to the optical disc.

Abstract: A lens actuating apparatus includes a fixed part, a moving part and at least one flexible part. The moving part is movably located on the fixed part. The flexible part has four contacting portions that form a hollow enclosed body. Two contacting portions that are located at the diagonal direction fasten the fixing part, and the other two contacting portions that are located at another diagonal direction contact the moving part. When the moving part has a movement related to the fixed part, the contacting portions of the flexible part contacted the moving part move far away from the fixed part. Thereby, the moved contacting portions exert a flexible recovery force to the moving part. The flexible part can be fully utilized in a limited space and does not affect the allocation of the other elements.

Abstract: An apparatus including a first engaging portion for holding an optical pickup, a second engaging portion to be engaged with the first engaging portion, a transfer portion for driving the second engaging portion to transfer the first engaging portion in a radial direction, a calculating portion for calculating a backlash value between the first and second engaging portions in a transfer direction of the first engaging portion, and a driving control unit. The driving control unit controls a driving portion to transfer the optical pickup based on a calculated backlash value.

Abstract: There is provided a disk drive including a base chassis, a first optical pickup mechanism including a disk rotation drive disposed on the base chassis, first optical pickup unit to write and/or read data to and/or from a first optical disk and a first pickup moving mechanism to move the first optical pickup unit radially of the first optical disk, a second optical pickup mechanism disposed opposite to the first optical pickup mechanism and including a second optical pickup unit to write and/or read data to and/or from a second optical disk and a second pickup moving mechanism to move the second optical pickup unit radially of the second optical disk, and a controlling means for detecting the movement of one of the optical pickup units and moving the other optical pickup unit to make weight balancing of the base chassis. Thus, the base chassis weight is balanced while one of the two optical pickup units is being moved.

Abstract: An apparatus for scanning a track on a record carrier has a head for scanning the track and generating a read signal. The tilt between the head and the record carrier (11) is compensated via a tilt servo loop. Thereto the head is provided with tilt compensating actuators (42). A measure of the tilt is jitter in the read signal generated by a front end (43) and filter (44). A wobble generator (40) provides a wobble signal to the actuators and to an input of multiplier (45) for synchronous detection of the jitter. The output of the multiplier (45) is coupled to a low pass filter (46) for generating a tilt error signal coupled to a tilt controller (47) for generating a tilt control signal.

Abstract: A method and apparatus for compensating tilt. The tilt compensation method includes: obtaining one of a jitter best, an RF envelope, and a focus DC offset (FODC) from a detection signal of the ROM data region and determining whether the obtained value is within a tolerance range; and obtaining an initial skew compensation value using the obtained value when the obtained value is within the tolerance, changing the magnitude of current applied to an actuator designed to perform driving in at least three-axis directions to drive an objective lens of an optical pickup assembly in a radial tilt direction when the obtained value is not within the tolerance range, and repeating the obtaining of one of the jitter best, the RF envelope, and the FODC and changing the magnitude of the current until the obtained value is within the tolerance range.

Abstract: A pick-up angle adjustment apparatus in provided for adjusting an angle of an optical pick-up mounted in an optical disk apparatus. In the pick-up angle adjustment apparatus, a first guide shaft has a first length between a pair of ends thereof for guiding and supporting the optical pick-up. A second guide shaft has a second length between a pair of ends thereof for guiding and supporting the optical pick-up. A first adjustment member is operable for vertically moving one end of the first guide shaft so as to adjust the angle of the optical pick-up. The first adjustment member is capable of moving the one end of the first guide shaft by a first distance when the first adjustment member is operated by a given operation amount. A second adjustment member is operable for vertically moving one end of the second guide shaft so as to adjust the angle of the optical pick-up.

Abstract: An optical disk as disclosed herein includes, among other things, a summing module that sums a compensation signal to a predetermined signal in a servo loop. The compensation signal compensates for a periodical disturbance input into a servo system of the optical disk device in units of a rotation angle of the disk rotating module. A phase lead imparting module imparts a predetermined amount of phase lead to an output signal from an optical detector module and outputs the predetermined amount of phase lead as the compensation signal. The predetermined amount of phase lead is determined in accordance with the rotation period information. The optical disk device performs an accurate iterative learning control to provide stable servo performance. The iterative learning control is performed such that the signal having imparted an optimal amount of phase lead in accordance with the rotation period information is added to the servo loop.

Abstract: An optical disk apparatus detects a predetermined tilt angle and a predetermined focus bias at least two detection points on an inner and an outer circumferences of the optical disk. On the basis of the predetermined tilt angle detected at the detection points, the apparatus estimates the predetermined tilt angle at a radial position of the optical disk, and also estimates a focus bias. The apparatus controls the tilt angle according to a radial position of target track and a focus bias on the basis of estimation results at the time of recording and reading data on the optical disk.

Abstract: A method and apparatus for adjusting tracking error balance in an optical disk reproducing apparatus are provided. The method includes pre-setting a tracking error balance for an optical recording medium and adjusting the tracking error balance during reproduction of data from the optical recording medium.

Abstract: A tilt compensating device and method of performing normal tilt compensation in the event of a servo emergency which may occur during reproduction of data from an optical recording medium are provided. The tilt compensating device includes: an optical pickup; a tilt adjusting unit that adjusts a tilt angle of the optical pickup; a jitter detecting unit that detects an amount of jitter in a reproduction signal output from the optical pickup; and a controlling unit that monitors speed at which the optical recording medium operates using a phase-locked loop (PLL) signal generated from the reproduction signal and the degree of focus of the optical pickup, performs an operation to return to a normal state if any abnormality occurs, and controls operation of the tilt adjusting unit by comparing an amount of jitter detected at regular intervals against a reference.

Abstract: Disclosed is a tilt controlling method and apparatus in which an FE signal track at a point where an RF signal is the maximum or an RE signal track at a point where a jitter is the minimum is detected as a tilt control signal to induct a DC component according to the disk shape and an AC component according to the surface vibration of the disk. Further, the fact is used that an RF envelope has a maximum value when the disk is parallel to an object lens or there is no tilt. Thus, in a tilt initialization step, a tilt track as the RF Max. is obtained for one rotation and the central potential of this track is set as a tilt control reference voltage, and when the RF envelope becomes a phase corresponding to a condition of a controller or a differential value of the RF envelope in the tilt window signal becomes a desired phase, tilt control is started so that the RF envelope always has the maximum value.

Abstract: An optical pickup apparatus aiming at reduction of adverse effect on a tracking control signal and a data signal by preventing the reflected light from the adjacent layers of a multilayer disc changing to a stray light. In this optical pickup apparatus, the reflected light from the optical disc including the stray light from the adjacent layer is once focused with a focusing lens and is then reflected with the reflection plate. A flat attenuation element is provided between the lens and the reflection plate parallel to the optical axis with inclusion of the optical axis under the condition separated from the reflection plate. The reflection plate reflects the reflected light from the relevant layer and the attenuation element shields the reflected light from the adjacent layer. The light returning to the focusing lens includes less influence of the stray light. This light is detected with a detector to become a control signal and a data signal.

Abstract: An optical disk apparatus includes an objective lens that condenses light on an information recording layer of an optical disk that has a first area with a first track pitch and a second area with a second track pitch, to form an optical spot. The apparatus also includes a tilt driver that inclines the objective lens; a positioning unit that positions the optical spot on a target track; a position error detector that detects a position error of the optical spot from the target track; a tilt detection correcting unit that calculates a tilt error signal based on a first position error detected when the optical spot is positioned on a target track in the first area and a second position error detected when the optical spot is positioned on a target track in the second area; and a tilt controller that controls an inclination based on the tilt error signal.

Abstract: According to one embodiment, an optical disc apparatus, includes an offset addition section configured to add an offset amount to the electric signal output from each of a photo receiving elements in accordance with a first signal, a gain variable section configured to adjust a gain amount of each offset added electric signal obtained by adding an offset in accordance with a second signal, an A/D converter configured to convert each of the offset added electric signals to a digital signal from an analog signal, a servo signal arithmetic section configured to generate an error signal used for focus and tracking servo control from the digital signal, a reference signal generation section configured to generate the first signal and the second signal from the digital signal, and a gain/offset correction section configured to correct the error signal in accordance with the first signal and the second signal.

Abstract: For automatic adjustment of tracking balance, a microprocessor controls a servo control unit to adjust a tracking balance signal value for the optical disc reproduction to be a mid-value between a tracking balance signal value (hereafter referred to as first tracking balance signal value) to make a tracking error balance value 0% and a tracking balance signal value (hereafter referred to as second tracking balance signal value) to minimize jitter when the first tracking balance signal value is different from the second tracking balance signal value. This makes it possible to perform balanced tracking control with a good balance between tracking performance and jitter performance.

Abstract: A hologram apparatus comprises a vibration detection beam generation unit to apply a vibration detection beam, incoherent to the data and reference beams and to detect the presence/absence of vibrations, to the hologram recording medium; a light reception/determination unit to receive the vibration detection beam emitted from the medium after the beam is applied to and propagates through the medium and to determine whether the beam receiving position is within a preset range; and an interruption unit to interrupt at least one of the data and reference beams from being applied to the medium, when this unit has determined that the position of beam reception is not within the preset range.

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 compensation value setting device selects, based on the first and second index values calculated by the first and second index value calculation sections for each combination of the spherical aberration compensation value and the lens' position compensation value, one combination of the spherical aberration compensation value and the lens' position compensation value and then sets the selected combination for correcting the spherical aberration and the position of the objective lens.

Abstract: In order to obtain a corrected or compensated focus error signal or track error signal, it is proposed to generate primary and secondary scanning beams incident on adjacent tracks of an optical recording medium and to detect the primary and secondary scanning beams reflected from the optical recording medium in order to derive from them primary-beam and secondary-beam focus error signals or primary-beam and secondary-beam track error signals, which are subsequently normalized in order to obtain the compensated focus error signal or track error signal from the normalized primary-beam and secondary-beam error signals by means of weighted combinations. As a result of the normalization, the corrected or compensated focus error signal or track error signal is generated independently of the reflection properties of the respectively scanned track.

Abstract: An optical recording and reproducing apparatus for recording and/or reproducing an optical recording medium by irradiating light from a light source to the optical recording medium as near-field light from a near-field light irradiating unit includes a light source for emitting light, a first light-receiving unit for receiving and detecting returned light from the optical recording medium, a second light-receiving unit for receiving and detecting returned light from the near-field light irradiating unit, a control unit for detecting a relative skew between the optical recording medium and the near-field light irradiating unit based on a plurality of gap detection signals generated from divided detection signals of the second light-receiving unit and a drive control unit for outputting a drive signal to correct a skew of at least the near-field light irradiating unit to a drive unit in response to a skew detected in the control unit.

Abstract: The present invention provides a deficiency detecting apparatus that can accurately detect dusts and deficiencies on an optical disk even when an emitting power of a laser light source changes. The deficiency detecting apparatus is provided with a deficiency detecting section for detecting deficiencies or the like on an optical disk by reflected light, and a power adjusting section for adjusting an emitting power of a laser light source to be an optimum value. The deficiency detecting section can accurately detect the deficiencies on the optical disk even when the laser power changes by comparing a threshold value, which is determined in accordance with the adjustment result of the power adjusting section, with a value in accordance with the reflected light.

Abstract: The invention relates to a tilt controller for controlling the tilt (radial and/or tangential) of an actuator relative to a recording surface of an optical storage medium, compensation for the radial to tilt crosstalk being effected by feeding a filtered version of the radial control signal (r) into the tilt branch, and/or compensation for the focus to tilt crosstalk being effected by feeding a filtered version of the focus control signal (f) into the tilt branch.

Abstract: A method for generating a feedback signal in optical disc drives is disclosed. Firstly RF signal is generated by a pickup head and coupled to a converter to generate a digital signal. Then a detector generates a plurality of pseudo-jitter according to the digital signal. Thereafter a calculator receives the said pseudo-jitter and calculates for outputting a feedback signal to the pickup head.

Abstract: A tilt detection apparatus for a medium comprises a tilt detection beam generator that makes a tilt detection beam incident ion a medium to detect whether the medium is tilted with respect to a reference position; a light reception unit that receives the tilt detection beam that after striking the medium, has come from the medium; and a correction output unit that outputs a signal to correct a tilt of the medium, based on a difference in light reception position on the light reception unit between a position at which the light reception unit receives the tilt detection beam and a position at which the light reception unit is to receive the tilt detection beam when the medium is in the reference position.

Abstract: The present invention provides highly reliable PLL without influence of variations in amplitude of a reproduced signal or variations in inclination of an edge. An information-reproducing apparatus according to the present invention includes a unit for detecting a phase difference between a reproduced signal and a reproducing clock signal, a PLL circuit for regulating a frequency of the reproducing clock signal to compensate for the detected phase difference, a unit for detecting a state of the PLL circuit, and a unit for regulating a loop gain of the PLL circuit corresponding to the detected state.

Abstract: A method and device for measuring the tilt in an optical disc drive (1) is disclosed. The optical disc drive (1) comprises two lasers (31, 41) generating two laser beams (32, 42) having mutually different optical characteristics. One of these laser beams (32) is continuously ON, and is used for writing or reading data to or form the disc. The other laser beam (42) is repeatedly switched ON and OFF. Tilt is measured by comparing a normalized error signal (RES(ON)) during the ON-phase (TON) with a normalized error signal (RES(OFF)) during the OFF-phase.

Abstract: In a method of obtaining a reproduction signal with good quality from a data recording medium, two actual signals are generated as first and second signals I1 and I2 from detection signals obtained from the data recording medium. A coefficient k which has linear correlation with a tilt is calculated based on the first and second signals I1 and I2. A reproduction signal in which influence of the tilt is eliminated, is reproduced by using the coefficient k and the first and second signals I1 and I2.