Abstract: An information recording apparatus according to one aspect of this invention comprises a detection unit configured to detect a manufacturing error unique to an information storage medium, a transmission unit configured to transmit the manufacturing error detected by the detection unit to an external apparatus, a reception unit configured to receive a recordable capacity which is calculated by the external apparatus on the basis of the manufacturing error transmitted from the transmission unit, a limitation unit configured to limit data to be supplied on the basis of the recordable capacity received by the reception unit, and a recording/aborting unit configured to record the recording data, supply of which is limited by the limitation unit, or to abort recording of the recording data.

Abstract: Astigmatism of a beam of first laser light is cancelled at a position separated from first optical element by a predetermined distance on an optical axis of the beam of first laser light by refracting to transmit the beam of the first laser light by being refracted by rotating by a predetermined angle around an axis orthogonal to the optical axis of the beam of the first laser light, refracting a beam of second laser light to coincide with the optical axis of the beam of the first laser light and rotating by a predetermined angle around a second axis orthogonal thereto.

Abstract: A kind of an optical disc is discriminated by a disc discriminating section, an order of aberrations to be corrected is set by an order setting section by the kind of the optical disc, drive of a liquid crystal optical element is controlled by a drive control section through a liquid crystal driver, and an aberration of an optical beam is corrected based on the order of the aberration. The level of importance of the aberration correction differs by the kind of the optical disc, and the order of the aberration is set by the level of importance of the aberration correction.

Abstract: A method for detecting and controlling disc tilt in an optical disc mechanism comprising the steps of (A) measuring a 2-dimensional displacement of an optical lens of the optical disc mechanism, (B) extracting an absolute value of a disc tilt angle in the optical disc mechanism based upon the 2-dimensional displacement and (C) controlling deflection of a tilt moving coil according to the absolute value of the disc tilt angle.

Abstract: A tilt adjustment device for adjusting tilt of a left guide bar with respect to a right guide bar, and includes a holding seat and a cylindrical-shaped bushing disposed rotatably within the holding seat. The bushing defines a bar-retention hole to permit extension of the left guide bar therethrough, and has a turning portion defining a first axis and an insert portion that extends eccentrically from the turning portion and that defines a second axis parallel to the first axis. Rotation of the cylindrical-shaped bushing relative to the holding seat results in a radial movement of the turning portion, which, in turn, moves the first axis toward and away from the second axis of the insert portion.

Abstract: An optical disc apparatus is provided, which comprises a lens tilting section for tilting an objective lens to correct coma aberration occurring in a light beam spot focused on an information surface of an optical disc, a spherical aberration correcting section for correcting spherical aberration occurring in a light beam spot focused on the information surface, and a lens tilt-spherical aberration correction control section for controlling the spherical aberration correcting section to change an amount of spherical aberration correction performed by the spherical aberration correcting section depending on a tilt of the objective lens tilted by the lens tilting section.

Abstract: A method and system within optical disc player/recorders that measures tangential disc tilt and provides for responsive action. Optical discs inevitably show some degree of warping. By determining the tangential tilt angles over the disc and comparing these tilt angles with a prescribed maximum allowed tilt angle, responsive actions are taken if the maximum tilt angle is exceeded to stop operation or adjust the tangential lens tilt to compensate for the tangential disc tilt usig with a bandwidth suitable for high rotational speeds.

Abstract: Disclosed is an optical disk device including: an objective lens unit having an objective lens and a lens holder; an elastic supporting member supporting displaceably the objective lens unit on a body of an optical head; first and second drive sections applying respectively driving forces to first and second driven positions on the objective lens unit opposed across a position of a center of mass of the objective lens unit in a direction orthogonal to an optical axis of the objective lens; and a driving force adjustment section adjusting allocation of the driving forces respectively applied to the first and second driven positions so that a possible influence of a displacement force in a tilt direction on a displacement force in a focusing direction at the position of the center of mass when the displacement forces act on the objective lens unit is avoided.

Abstract: The present invention relates to a skew control method and a skew control unit by which stable skew control can be performed with a simple configuration without the need for a dedicated skew sensor. Focus drive voltages V1 and V2 are measured at a plurality of points P1 and P2 set by moving an optical pick-up 31 in the radial direction of an optical disc 2 in a state where a focus servo of the optical pick-up 31 is ON, and skew angle control is performed so that V1 and V2 are equal to each other.

Abstract: According to one embodiment, an optical disc apparatus includes a calculation unit that calculates a tilt of a disc, a determining unit that determines whether or not the tilt of the disc calculated by the calculation unit is larger than a preset predetermined reference value, and a correction unit that corrects the tilt of the disc calculated by the calculation unit.

Abstract: A method of compensating for tilt and/or defocus and an apparatus therefor. The apparatus has a tilt and/or defocus detector detecting the tilt and/or defocus of an optical recording medium, and a recording compensator compensating a write pulse having a predetermined recording pattern using a predetermined system with respect to the detected tilt and/or defocus. The apparatus both adjusts write power with respect to the detected defocus, shifts the recording pattern with respect to the detected tilt, adjusts a power level and/or write time required for recording, and records a recording mark having a desired size (length and width). The apparatus is useful in compensating for tilt and/or defocus in a high-density optical system.

Abstract: A disk apparatus has an equalizing unit which performs PR equalization for the read signal from the disk based on a plurality of tap coefficients, a decoding unit which performs a decoding process for the equalized read signal, a calculating unit which obtains an ideal signal of the decoded read signal, and compares the ideal signal with the decoded read signal, thereby calculating an error signal E, and a control unit which groups the tap coefficients into at least a first and second coefficient groups which are groups of tap coefficients at symmetrical locations each, and determines tap coefficients of the first coefficient group in a range of a first limit value K1 according to the calculated error signal, determines tap coefficients of the second coefficient group in a range of a second limit value and supplies the determined tap coefficients to the equalizing unit.

Abstract: A tilt adjusting apparatus including a digital signal processor, a first drive integrated circuit, and a tilt adjuster. When an optical recording medium is loaded into a deck, the digital signal processor outputs a focus control signal to control a focus of an optical recording medium, measures a tilt with respect to the optical recording medium, and outputs a tilt adjustment signal and a switch control signal so as to adjust the tilt. The first drive integrated circuit either synthesizes the tilt adjustment signal and the focus control signal or receives only the focus control signal according to the switch control signal and then outputs the synthesized signal or the focus control signal to the optical pickup. The tilt adjuster synthesizes the tilt adjustment signal output from the first drive integrated circuit and the focus control signal and then outputs the synthesized signal to the optical pickup.

Abstract: A compatible optical pickup compatibly using a high density recording medium and at least one low density recording medium, includes an objective lens to form a light spot suitable for use on a recording surface of the high density recording medium by focusing a corresponding incident light beam with a high NA suitable for the high density recording medium and a light spot suitable for use on another recording surface of the low density recording medium by focusing another corresponding incident light beam, and an actuator provided to apply tilt to the objective lens. The light beam for the low density recording medium is incident on the objective lens as a divergent beam. When the objective lens is shifted in a radial direction, a tilt is applied to the objective lens corresponding to the shift.

Abstract: An auto-adjusting system for an optical incident angle comprises a memory, a linear tilt calculation unit, a non-linear tilt calculation unit, a controller, and a tilt actuator. The memory is used for storing a linear tilt compensation table and a non-linear tilt compensation table. The linear tilt calculation unit is used for calculating the corresponding linear tilt dac value by consulting the linear tilt compensation table according to a first radius and a focus output voltage. According to a predetermined comparison procedure, the non-linear tilt calculation unit is used for generating a second radius wherein the compact disc begins to generate non-linear deformation and then obtaining the corresponding non-linear tilt compensation parameter by consulting the non-linear tilt compensation table according to the first radius and the second radius. The controller is used for controlling the pickup head, the memory, the linear tilt calculation unit, and the non-linear tilt calculation unit.

Abstract: This invention relates to an optical scanning device for scanning an optical record carrier and detecting a tilt characteristic of the optical record carrier during scanning. The device includes a redirecting structure (26) arranged on an objective lens (10) to redirect a part of a radiation beam, when travelling towards the record carrier, differently to a main part of the radiation beam. The redirected beam part follows a path which is different to that of a path followed by the main beam part, towards a position sensitive detector in a detection system (16).

Abstract: The invention detects the thickness error of the transparent substrate using a general focus error signal detection system employing the fact that the reflecting light from the optical disk causes distortions in diffraction image at the detection plane or unsymmetrical expansions before and after the detection plane due to spherical aberration as a result of thickness errors of the transparent substrate. The absolute amount of the thickness error of the transparent substrate and its symbol are detected by detecting the difference between the absolute value of the positive side peak and the absolute value of the negative side peak of the focus sum signal, or the difference in focus positions between the peak point of the focus sum signals and the zero point of the focus error signals using the focus error signal detection system according to the knife-edge method. This enables it to detect the thickness error of the transparent substrate without using a special optical system.

Abstract: An adjustment apparatus for adjusting an optical pickup capable of recording and/or reproducing optical discs of different sorts. The adjustment apparatus is an adjustment optical disc having a first signal recording layer of a physical format in common with a CD and a second signal recording layer of a physical format in common with a DVD. On the first and second signal recording layers, there are concentrically recorded EFM modulated data. The respective signal recording layers are provided with recording areas that are not overlapped with each other.

Abstract: A lens holder (101) holds an objective lens (4) and a support shaft (103) is inserted in a bearing hole (101a) in the lens holder (101). Light that is emitted from a light source and reflected by an information recording medium enters two light receiving parts, which output currents (I21a, I21b) responsive to the amounts of light received. A controller (109) applies a current (I96) based on the difference between the currents (I21a, I21b) to coils (116a) in an inclination drive unit (106). By interaction between the coils (116a) and magnets (116b), the lens holder (101) is turned on a first axis (I) while the light source and other components are secured. Fluids provided in the bearing hole (101a) further improve the vibration-resisting properties.

Abstract: A method of, and an apparatus for detecting a radial tilt of a disc. Phases of summed signals obtained from signals that external light-receiving units of an octant photo diode receive are compared to generate an external phase comparison signal Do. Phases of other summed signals obtained from other signals, that internal light-receiving units of the octant photo diode receive, are compared to generate the internal phase comparison signal Di. The radial tilt is detected based on the internal and external phase comparison signals Di and Do obtained when a laser beam crosses a track formed the disc. Thus, the radial tilt can be more precisely detected.

Abstract: An optical disc drive for recording and/or reading information on or from an optical disc is disclosed. The optical disc drive includes: a position controller which controls the position of the objective lens based on the position-controlling light beam reflected by the reflective surface by condensing the position-controlling light beam by the objective lens such that the position-controlling light beam is brought to a focus at a target guide position on the reflective surface corresponding to the target recording position; a tilt angle detector which detects tilt angle of the optical disc relative to optical axis of the position-controlling light beam; and a focal position corrector which makes a correction such that a focal position obtained when the information light beam is condensed by the objective lens is aligned to the target recording position according to the tilt angle.

Abstract: There is provided an optical system of an optical pick-up for recording/reproducing data to/from at least two types of optical discs including a first optical disc and a second optical disc whose recording density is higher than that of the first optical disc. The optical system is provided with a light source unit for the first and second optical discs, an objective lens, and a photo detector. The optical system further includes an optical surface to satisfy compatibility between the at least two types of optical discs, the optical surface being located between the light source unit and one of the at least two type of optical discs. The optical surface has an inner region having a numerical aperture for the first optical disc, an outer region located having a numerical aperture for the second optical disc, and an intermediate region that is located within the outer region at a periphery of the inner region.

Abstract: In an optical disk medium, land recording tracks (1) are coupled by first and second coupling portions (3 and 4) at a particular radial position to form a tilt detecting mark SM.

Abstract: A holographic digital data storage apparatus detects a wobbling in a disc shaped storage medium, wherein the apparatus includes a beam generator and finding means, the disc including therein one or more holographically generated patterns. The beam generator projects at least two wobble detection beams to the holographically generated patterns, the wobble detection beams having different diffraction efficiencies provided at respective characteristic angles, wherein the characteristic angle is an angle between an optical path of one wobble detection beam and that of its corresponding pattern forming beam used in forming one of the holographically generated patterns and a diffraction efficiency is given by a ratio of a power of a diffracted beam of one of the wobble detection beams to a power of said one of the wobble detection beams. The finding means finds at least a difference between the diffraction efficiencies to thereby determine the wobbling in the disc.

Abstract: A disk drive apparatus for recording (writing) and/or reproducing (reading) information on an optical disk by rotating the optical disk, and adjusting the tilt angle of an optical pickup device with respect to the optical disk. A spindle chassis rotationally supports a turntable on which the optical disk is placed. A pickup chassis, rotationally supported on said spindle chassis, movably supports an optical pickup device that writes and/or reads the information to/from the optical disk and is movable toward and away from the turntable. A tilt mechanism adjusts the tilt angle of the optical pickup device with respect to the optical disk by rotating the pickup chassis with respect to the spindle chassis.

Abstract: A method and apparatus cancel repeatable run-out (RRO) errors in positioning on a recording medium using a RRO cancellation control voltage. The RRO cancellation includes (a) estimating a rotation period of the recording medium, (b) determining an update interval for the RRO cancellation control voltage based on the estimated rotation period and a desired number of updates to be performed per rotation, (c) updating a value of the RRO cancellation control voltage if a time period passed from a last update is greater than the update interval, and (d) applying the updated RRO cancellation voltage to control the positioning. A phase and a magnitude of the RRO cancellation control voltage may be determined for a RRO frequency range.

Abstract: Prior to recording/reproducing information to/from an optical disk rotationally driven by a spindle motor, an optical pickup is moved to a plurality of measuring positions set beforehand in a radial direction of the optical disk. A relative tilt between the optical disk and the optical pickup is detected with the spindle motor being rotated so that a linear velocity at each of the measuring positions equals a linear velocity upon actually recording or reproducing the information thereat. The tilt detected at each of the measuring positions is stored as tilt detection data corresponding to each of the measuring positions.

Abstract: In an optical disk apparatus for focusing a light beam on a track of an optical disk by using a tracking control loop to perform at least one of recording and reproducing operations upon the optical disk, a loop level calculating unit calculates loop levels of the tracking control loop. A control unit calculates a loop gain of the tracking control loop in accordance with the loop levels of the tracking control loop and compensates for a radial tilt of the optical disk in accordance with the calculated loop gain of the tracking control loop.

Abstract: The method for reproducing records for the optical recording medium detects and compensates for detrack, tilt and defocus, having advantages in that: (1) the magnitude and the direction of detrack, tilt and defocus can be detected from a difference signal (for example, a read channel 2 signal or a tracking error signal obtained by processing the read channel 2 signal) between optical reflecting signals detected at the header fields staggered on the basis of the tract center, and compensates for detrack, tilt and defocus, thereby preventing deterioration of data quality caused by detrack, tilt and defocus during a recording/reproducing operation and enabling the stable operation of the system; and (2) the focus servo is rapidly stabilized to enable real-time recording as well as the stable operation of the system.

Abstract: An apparatus and a method of playing an optical recording medium, including a method of compensating for a tilt by a real time tilt detection before and during a playing operation of the optical recording medium. A tilt compensating apparatus includes an optical pickup, a tilt adjuster which adjust a tilt of the optical pickup, a jitter detector which detects a jittering amount of a playing signal generated from the optical pickup, and a tilt controller which controls operations of the tilt adjuster so as to have the jittering amount become minimum by comparing the jittering amount detected before a reproduction of a content of the optical recording medium with a first jittering reference value, and comparing the jittering amount detected during the reproducing of the optical recording medium, per a certain period, with a second reference value. Since the reproduction of the optical recording medium is performed after a tilt compensation, it takes a shorter time to start the reproduction operation.

Abstract: An optical head includes the following: a light beam separator (35) that includes substantial interference regions for light that is reflected from an information recording medium and travels in a straight path and ±first-order diffracted light produced by information tracks of the information recording medium, and diffracts each of plural light beams in regions (32a, 32b) of the substantial interference regions, where the amount of light is changed by a change in the relative angle between the information recording medium and the objective lens and by a shift of the objective lens in the radial direction of the information recording medium; a light-receiving element (36a, 36b) for receiving the light beam that is reflected by the information recording medium and separated by the light beam separator (35); and an arithmetic circuit that corrects a value of an electrical signal detected by the light-receiving element (36a, 36b) in accordance with a radial position signal corresponding to the amount of shift of

Abstract: An optical disk apparatus includes a tilt detection unit detecting the tilt value of an optical disk medium with respect to an optical system. A tilt compensation unit compensates for the tilt of the optical disk medium by adjusting a relative angle between the optical system and the optical disk medium according to the tilt value detected by the tilt detection unit. A tilt detection error estimation unit estimates tilt detection error of the tilt detection unit with respect to a radial position of the optical disk medium at which information is recorded/reproduced by the optical systems by referring to tilt values that are previously detected at a plurality of radial positions of the optical disk medium by the tilt detection unit. The tilt compensation unit has a correction unit that corrects the tilt value according to the tilt detection error estimated by the tilt detection error estimation unit.

Abstract: The present invention discloses a tilt error detecting device for detecting a tilt error signal indicative of a tilt error between an optical disc and an optical pick-up head. The tilt error detecting device includes: a first combining module for generating a first level signal according to a first portion of a plurality of detecting signals which corresponds to a plurality of first detecting areas on a photo detector; a second combining module for generating a second level signal according to a second portion of the detecting signals which corresponds to a plurality of second detecting areas on the photo detector; and a calculating module coupled to the first combining module and the second combining module for generating the tilt error signal according to the first level signal and the second level signal.

Abstract: A tilt sensor 23 is provided on a CD optical pickup 11, and a sub-chassis 24 and a height adjustment mechanism 25 and the like are provided for adjusting the tilt of a DVD optical pickup 12. A recording or reproduction position is read in by the DVD optical pickup 12 while moving the CD optical pickup 11 and the DVD optical pickup 12 along guide shafts 18 and 26 respectively, the amount of tilt of the optical disk 16 at this position is detected by the tilt sensor 23 of the CD optical pickup 11, the tilt of the laser light axis from the DVD optical pickup 12 is adjusted in accordance with the amount of tilt that is detected, and the amount of tilt of the optical disk 16 is corrected.

Abstract: In a tilt correction method, first information about a specific inclination of an object lens is acquired in response to an access request to an information recording medium. The specific inclination is obtained when the signal characteristic of a push-pull signal becomes a prescribed level in or near a target access area. Then, second information about the optimum inclination of the object lens is acquired for the target access area, based on the first information and tilt difference information representing a difference between a first inclination and a second inclination of the object lens defined in advance in a particular area on the information recording medium. The first inclination corresponds to an optimum reproduced signal from the particular area, and the second inclination is obtained when the signal characteristic of the push-pull signal from the particular area becomes the prescribed level. Finally, tilt correction information is estimated from the second information.

Abstract: The invention provides a servo calibration mark detection circuit for use in an optical disk drive. In one embodiment, the servo calibration mark detection circuit comprises a summing processor, a slicing level generator, and a comparator. The summing processor sums an intensity of a light beam reflected from both an inner groove and an outer groove to obtain a first signal. The slicing level generator generates a slicing level. The comparator then compares the first signal with the slicing level to obtain a second signal, wherein the second signal indicates a first location of a first servo calibration mark recorded on the inner groove and a second location of a second servo calibration mark recorded on the outer groove.

Abstract: An optical head that detects a tilt in an optical disk. The optical head includes a condensing means, a light receiving means, a tracking error signal detection means, and an optical tilt detecting means. The light receiving means includes at least first and second light receiving areas, the first light receiving area being a rectangle having long sides that extend in a direction perpendicular to information tracks on the optical disk. The tracking error signal detection means detect error signals corresponding to light signals received in the first and second light receiving areas. The optical disk tilt detection means compare the tracking error signals to detect a radial tilt in the optical disk. In an alternative embodiment, the long sides of first light receiving area extend in a direction parallel to the information tracks, and the optical disk tilt detecting means detect a tangential tilt in the optical disk.

Abstract: An actuator of an optical disk system and an apparatus producing a signal for driving the actuator, the actuator including a light source, with which information is recorded on or reproduced from an optical disk surface. In the actuator, an inner focusing coil and an outer focusing coil are installed near an inner boundary and an outer boundary, respectively, of the optical disk surface. A first signal wire is connected to a first port of the inner focusing coil and transmits an inner coil signal. A second signal wire is connected to a first port of the outer focusing coil and transmits an outer coil signal. A common signal wire is connected to a second port of the inner focusing coil and a second port of the outer focusing coil and transmits a common reference signal. Thus, a simple, inexpensive 8-wire actuator can be obtained.

Abstract: An optical disc drive includes an objective lens for focusing light on an optical disc with five or more stacked data storage layers and a tilt control mechanism for controlling a tilt angle defined between the optical axis of the light and a normal to the storage layers. The drive reads and/or writes data from/on a selected one of the storage layers by focusing the light on the selected layer. The numerical aperture NA of the objective lens is defined so as to fall within the range of 1.3009×D3?2.9315×D2+2.3133×D?0.0502 to 1.3009×D3?2.9315×D2+2.3133×D+0.2028, where D is a distance (mm) from a light incident side of the disc to the deepest one of the storage layers, which is located most distant from the light incident side.

Abstract: The present invention relates to an optical pickup and an optical disc drive that records or reproduces data signals on or from optical discs different in specifications, such as recording density and thickness. One objective lens (17) is used for optical discs (22a, 22b) of two types that differ in specifications. The optical pickup and the optical disc drive comprise two light source sections (24a, 24b) and a lens-supporting mechanism (15). The light source sections emit two laser beams of different wavelengths, respectively. The lens-supporting mechanism (15) controls the position of the objective lens (17) in the radial direction of the discs and along the optical axis.

Abstract: There are provided an optical disk device and tilt correction processing method for performing recording/reproduction by rapidly acquiring an optimal tilt correction value for an optical disk having a plurality of recording/reproducing layers. In an optical disk device capable of recording or reproducing information by irradiating a laser beam to each of a plurality of recording/reproducing layers of an optical disk, the tilt value is stepwise set within a predetermined range at a predetermined radius position of the recording/reproducing layer located at the farthest distance from the laser beam irradiation side so that an optimal tilt correction value can be obtained from the quadratic function by the method of least squares of the jitter or the like obtained from the disk. By applying the optimal tilt value obtained to the other recording/reproducing layer, it is possible to start recording or reproduction in a short time.

Abstract: A light pickup device includes a light projection optical system comprising a light source which emits light, and an objective lens which condenses the light on an optical disk, a light detection optical system comprising a light detector, and a condenser lens which condenses light reflected from the optical disk on the light detector, and an adjustment optical element for coinciding a center axis of an intensity distribution of the light condensed on the optical disk by the light projection optical system with an optical axis of the objective lens.

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: An optical head performs recording and/or reproducing of a signal to an optical recording medium and comprises a light source, an objective lens converging the light emitted from the light source to the optical recording medium, and objective lens tilting mechanism for tilting the objective lens in order to correct aberration generated when the optical recording medium is tilted, and the optical head is assembled so that a direction of the coma aberration of the objective lens itself perpendicularly crosses a direction tilted by the objective lens tilting mechanism.

Abstract: An optical-disc driving apparatus for an optical disc includes a pickup; a detection unit for detecting a traverse signal by differential push-pull (DPP) detection for every radial tilt angle within a first range, the radial tilt angle being measured between the optical disc and the pickup; a determination unit for determining the radial tilt angle corresponding to a traverse signal within a second range including a maximum value among the detected traverse signals; and a control unit for controlling the orientation of the pickup with respect to the optical disc based on the determined radial tilt angle. The optical-disc driving apparatus controls driving of the optical disc based on the traverse signal by DPP detection generated from a preceding beam, a main beam, and a succeeding beam.

Abstract: The invention relates to a method and an arrangement for a replay or recording appliance for optical recording media having an inclination control system for vertical alignment of the scanning beam with respect to optical recording media. In order to exclude other factors which, in addition to the inclination of the scanning beam, influence the radio-frequency signal which is detected by the recording medium, without any additional inclination sensors from the disadvantageous influence of the inclination control, an inclination control system is provided which uses the lower envelope curve signal of a radio-frequency signal which is detected by the optical recording medium and represents the dark value of the detected radio-frequency signal.

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: A method for calibrating tilt control values of a PUH in real time is applied to an optical disk drive and includes the steps of: creating a look-up table, the look-up table including several optical disk data/physical addresses of track zones and the corresponding tilt control values; reading tilt control values as reference values from the look-up table corresponding the track position of a PUH; calculating a current tilt control value according to the reference values; controlling the PUH according to the current tilt control value; reading a decoding error generated during a decoding procedure of the optical disk drive; calibrating the tilt control values and updating the look-up table. When the decoding error is larger than a decoding error threshold, the tilt control values of the track zone is calibrated. Hence, even an irregularly deformed optical disk can be calibrated to obtain better tilt control values.

Abstract: An objective lens drive having an optical axis adjustment function. An objective lens is supported by a lens holder, and the lens holder is supported on a suspension holder by way of a suspension. The suspension holder is supported so as to be rotatable about an axis extending in a direction in which the suspension extends, whereby the suspension holder is supported laterally by means of multilayer piezoelectric elements. When a drive voltage is applied to the multilayer piezoelectric elements, the piezoelectric elements are displaced vertically, whereupon the suspension holder is rotated about the axis, to thus adjust the optical axis of the objective lens.

Abstract: A method for measuring a tilt angle of a pickup head. The method includes the steps of: moving the pickup head to a track to be measured; radiating a laser beam with a constant power; defining a proper range of tilt control values; controlling the tilt angle of the pickup head according to the range of tilt control values, acquiring a RF signal corresponding to each tilt control value, and storing an associated value of a associated signal; detecting the maximum among the stored associated values; selecting and storing the tilt control value corresponding to the maximum as the optimum tilt control value for the track if there is a maximum; and modifying the range of tilt control values and executing the previous steps if there is no maximum. The so-called associated signal includes a tracking error signal, a reading/writing RF signal, an S-curve signal, or the RF signal.