Abstract: An optical disk medium and a drive system are provided that enable high density recording to be carried out. In the optical disk medium, recorded information tracks are formed in a concentric or spiral manner, and information is recorded and played back by irradiating the recorded information tracks with a laser beam through a transparent substrate or a transparent cover layer. A change in tilt of the optical disk medium over one circuit of each of the tracks is set equal to or less than an allowed value, a change in tilt over the entire surface of the optical disk medium is permitted to be larger than the allowed value, and low frequency bandwidth tilt control is carried out by the drive 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: There is disclosed an optical pickup apparatus in which an optical axis of an objective lens can be kept perpendicular to a recording surface of an optical disk regardless of a warp or a curvature of the optical disk. In this optical pickup apparatus, a lens holder can be moved in a focusing direction and a tracking direction. In order that the objective lens can be tilted in accordance with a skew of the optical disk in a radial direction, second magnets are mounted on the lens holder whereas second coils are mounted in opposed relation to the second magnets, respectively. The second magnets and the second coils cooperate with each other to tilt the objective lens.

Abstract: A retreat permission position of a carrier arm when the carrier arm is moved back to retreat outside a mounting table after the carrier arm carries a substrate to a position above the mounting table while holding a peripheral portion of the substrate, to thereby place the substrate on a plurality of supporting pins vertically movable through the mounting table. A disk substantially equal in size to the substrate, having insertion holes formed to allow the supporting pins to be inserted therethrough and being supportable by the carrier arm, and a sensor to detect whether or not the supporting pin inserted through the insertion hole of this disk exists.

Abstract: This tilt servo control method includes the step of reading a first jitter value “A”. Thereafter, a second jitter value “B” is read after an angle of an objective lens is moved by a predetermined step. If “A” is equal to or smaller than “B”, the angle of objective lens is optimized by performing the tilt servo while the angle of objective lens is moved. If “A” is larger than “B”, a third jitter value “C” is read after the angle of objective lens is moved by predetermined step. If “A” is equal to or smaller than “C”, the angle of objective lens is optimized by performing the tilt servo while the angle of objective lens is moved. If “A” is larger than “C”, the angle of objective lens is optimized while the angle of objective lens is moved by half of the predetermined step.

Abstract: This tilt correcting method includes the step of monitoring jitter values while adjusting a turntable or guide rail after a wobble disc is placed on the turntable. Thereafter, it is determined whether the depths of valleys of monitored jitter values are different, it is determined that the reference tilt is a radial tilt if it is determined that the depths of valleys of the monitored jitter values are different, and the radial tilt is corrected. If it is determined that the depths of valleys of the monitored jitter values are not different, it is determined whether the heights of peaks of the monitored jitter values are different, it is determined that the reference tilt is a tangential tilt if it is determined that the heights of peaks of the monitored jitter values are different, and the tangential tilt is corrected.

Abstract: A tilt control apparatus includes an orthogonal shift detector (9) which detects an orthogonal shift by comparing a pair of a plurality of tap coefficients (C1, . . . , C7) of a FIR filter and generates an orthogonal shift signal, and an actuator varies the inclination of the optical axis of the light beam to correct the orthogonal shift, and a tilt controller (10) controls the drive of the actuator in accordance with the orhogonal shift signal to minimize the orthogonal shift. In the information recording operation, the orthogonal shift obtained based on a recording track is previously stored in a temporary storage portion and the stored orthogonal shift is used to conduct the tilt control.

Abstract: An apparatus and a method are provided for compensating an aberration occurring in a reflected light beam from a recording medium. The apparatus includes a liquid crystal unit including a first electrode layer having divisional electrodes and a second electrode layer, and a liquid crystal element which provides a light beam with a phase change when an electric field is applied; a detector for receiving the reflected light beam through the liquid crystal unit to generate a detection signal; a voltage generator for generating voltages to be applied to the divisional electrodes; and a controller for performing aberration compensation control by changing the applied voltages to each of the divisional electrodes with reference to an applied reference voltage to a predetermined divisional electrode. The controller determines the applied reference voltage based on an amplitude change of the detection signal when the applied voltages to the divisional electrodes are changed.

Abstract: A tilt compensator in an optical disk drive detects an optimum tilt setting of the objective lens with respect to a reference plane of the optical head, which allows the optical head to obtain an optimum characteristic of a disk signal at a specified radial position of an optical disk. The optimum tilt setting is corrected at a desired track of the optical disk by using a difference between a first tilt angle of the reference plane with respect to the optical disk measured at the specified radial position and a second tilt angle of the reference plane measured at a desire track of the optical disk. The disk signal is a RF signal, a jitter of the encoded RF signal, a tracking error signal or a wobble signal.

Abstract: Disclosed is an adjustment apparatus for adjusting an optical pickup capable of recording and/or reproducing plural optical discs of different sorts. The adjustment apparatus is an optical disc for adjustment (1) having a first signal recording layer (5) having a physical format in common with a CD and a second signal recording layer (7) having 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 (8), (9) not overlapped with each other.

Abstract: A recording apparatus to record a mark on a recording medium includes an aberration detecting part and an optical power controller. The aberration detecting part detects an aberration signal corresponding to the amount of an aberration contained in a light beam radiated onto a recording surface of the recording medium by using an optical pickup system which includes a light source and an objective lens. The light source emits a light beam having a power to record the mark on the recording medium. The objective lens condenses the light beam to focus the light beam as an optical spot on the recording surface of the recording medium. The optical power controller controls the power output from the light source according to the detected aberration signal, so as to have the light source output an optical power to record the mark, in which a deformation due to the aberration is compensated for, on the recording medium.

Abstract: At the initialization, a tilt mechanism 9 is activated in a state where an optical pick-up 3 is fixed, and set up at a position where the level of a focus error signal obtained from an output of the optical pick-up 3 is at minimum. Thereafter, a reproducing operation is started. During the reproducing operation, the tilt mechanism 9 is not activated and the focus control is made with the focus servo by moving the optical pick-up 3 up or down, while the level of focus error signal is within a certain range. Further, if the level of focus error signal is beyond the certain range because the optical disk 1 is greatly inclined, the tilt mechanism 9 is activated to cause the optical disk 1 to come closer to the optical pick-up 3 to enable the control of the focus servo.

Abstract: A method of detecting a servo error, an apparatus therefor, a disk which maintains quantity of a servo error signal, a method of controlling a servo of an apparatus for recording data on and reproducing data from a disk, a method of detecting the tracking error, and a method of detecting tilt error of the apparatus.

Abstract: At the initialization, a tilt mechanism 9 is activated in a state where an optical pick-up 3 is fixed, and set up at a position where an E-F phase difference obtained in a signal processing portion 4 is 180°. Thereafter, a reproducing operation is started. During the reproducing operation, the tilt mechanism 9 is not activated and the focus control is made with the focus servo by moving the optical pick-up 3 up or down, while the level of a focus error signal is within a certain range. Further, if the level of focus error signal is beyond the certain range because the optical disk 1 is greatly inclined, the tilt mechanism 9 is activated to cause the optical disk 1 to come closer to the optical pick-up 3 to enable the control of the focus servo.

Abstract: An error signal detecting apparatus for an optical recording/reproducing apparatus, the error signal detecting apparatus including a photodetector to receive light reflected and diffracted by a recording medium, and a signal processor to detect an error signal by calculating a detection signal of the photodetector. The photodetector includes a plurality of light receiving areas to independently receive light of a light area in which the profile of the light changes to the opposite profile according to the tangential tilt of the recording medium. The signal processor detects a tangential tilt error signal from detection signals of the light receiving areas. Thus, a signal output from the error signal detecting apparatus does not change when a shift is generated in the objective lens or the distance between the objective lens and the disc is deviated from the on-focus position.

Abstract: An optical disk (10) includes several tracks (21-23, 121-125) that each include a series of optical data elements (29, 39). Each optical data element includes several reflective surfaces (31-34, 41-44) with respective different orientations that represent stored information. A detection system (210) directs a beam from a laser (217) onto successive optical data elements. The multiple reflective surfaces of each optical data element produce multiple reflected sub-beams that are imaged onto respective portions of a detector (219, 501, 541). The position of each sub-beam on the corresponding portion of the detector is determined, to thereby identify the orientation of the corresponding reflective surface and thus the stored information represented by that surface.

Abstract: An optical-pickup device includes a plurality of light sources, an objective lens for converging light from the plurality of light sources on an optical disc, and at least one light-receiving element for receiving light reflected by the optical disc. A light source of the plurality of light sources, which light source is not used for recording/reproducing, is used for detecting relative tilt between the optical disc and the objective lens.

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: An optical disc apparatus comprises: rotating means for rotating an information recording medium; a light source for irradiating a light beam onto a data side of the information recording medium; converging means for converging said light beam; focus error detecting means for detecting a difference between said data side and the focus of the light beam converged by said converging means; focus direction transferring means for transferring said converging means in a direction perpendicular to said data side; focus controlling means for driving said focus direction transferring means based on the output of said focus error detecting means in such a way that said light beam converges on said data side in a predetermined state; tracking direction transferring means for transferring said light source in the radius direction of said information recording medium; and tilt calculating means for calculating average values of the outputs of said focus controlling means obtained for a period of time, which is an integer

Abstract: An optical pickup tilt control module and a method for controlling a tilt value of an optical pickup to reduce the jitter value of a generated reproducing signal. The optical pickup tilt control module includes a reproducing signal generator, a jitter detector, a tilt controller and a tilt actuator. The reproducing signal generator receives a RF signal generated from the optical pickup and generates an EFM signal. The jitter detector receives the EFM signal and detects a jitter value of the EFM signal. The tilt controller generates optimum tilt control values during a correction stage and outputs a tilt control value according to a track position of reproduction data during an adjusting stage. The tilt actuator controls the tilt of the optical pickup according to the tilt control value.

Abstract: A recording and/or reproducing apparatus employing a disc-shaped recording medium in which difficulties in detecting an address in the case of a groove of the recording medium exhibiting superior recording characteristics and in detecting an address in the case that both a land and a groove of the recording medium are used as recording tracks are resolved. A recording and/or reproducing unit includes an optical head for illuminating the laser light converged as spots on an optical disc and for receiving the return light reflected and diffracted from the optical disc. An address information generating unit generates the address information from the return light received by the optical head in the recording and/or reproducing processing unit. A tilt compensation unit detects the inclination (tilt) of the optical head relative to the optical disc to correct the tilt of the optical head in accordance with the tilt detected.

Abstract: A tilt servo control apparatus has a tilt error correcting device for correcting a tilt error caused by a tilt angle defined between a normal at an irradiating position of a laser beam irradiated onto a recording surface of an optical recording medium and an optical axis of the laser beam. The tilt error correcting device is driven based on an intensity of the reflected light of the laser beam irradiated onto the recording surface. The apparatus provides a control to hold a drive value of the tilt error correcting device to a predetermined value in response to a track jump command for changing the irradiating position of the laser beam from the first irradiating position to the second irradiating position that is away therefrom by a distance corresponding to a predetermined number of tracks.

Abstract: An optical head scans the information layer (3) of an optical record carrier (1) by means of a radiation beam (13). Optical aberrations in the beam such as coma and spherical aberration, caused by tilt and thickness variations in the optical disc respectively, are compensated by an aberration compensator (27) arranged in the radiation beam. The tilt or thickness variation is measured by a detector (30) and used to control the aberration compensator. The radiation beam is focused onto the information layer by an objective system (11). A displacement of the objective system in the transverse direction (26) as used for radial tracking of the optical beam, causes a mismatch between the wavefront to be compensated and the wavefront introduced by the aberration compensator (27). The mismatch is reduced by using a position detector (33) for measuring the transverse position of the objective system and using the position signal (34) as input for the control of the aberration compensator.

Abstract: A tilt adjustment method for an optical disk recording and reproducing apparatus in which a signal is recorded on or reproduced from a disk using an optical pickup. In an optical disk recording and reproducing apparatus which uses an optical pickup having a tilt adjustment coil for adjusting the tilt of an objective lens, the errors contained in a signal reproduced from the disk are counted each time the tilt voltage to be supplied to the tilt adjustment coil is changed. When an appropriate count value is obtained, the tilt voltage at this state is determined to be an optimum tilt voltage.

Abstract: An object of the invention is to provide an optical disk drive apparatus in which skew adjustment can be performed easily while allowing size, weight and cost reduction. An optical disk drive apparatus has an objective lens which converges a light beam to direct it to an optical disk, an objective lens support for supporting the objective lens on a chassis of the apparatus, an elastic support member which movably supports the objective lens on the objective lens support portion, and a coil and a magnet, one of which is provided substantially integral with the objective lens and another of which is mounted on the objective lens support portion independently from the objective lens.

Abstract: In a method and an apparatus for aberration correction according to the invention, aberration occurring in recording/reproducing information derived from causes such as thickness variation of a substrate, a tilt, a focus error and a tracking error is detected, and the aberration is corrected by correcting these causes.

Abstract: An optical disk apparatus configured to be compatible with a plurality of disk types includes an objective lens to focus a laser beam onto an optical disk provided in the apparatus. A drive mechanism is coupled to the objective lens to enable tilting of the objective lens to a plurality of tilt angles. A first signal detection circuit is configured to receive and process a first information signal associated with information read from the optical disk and to output a data signal derived from the first information signal. A second signal detection circuit is configured to receive and process a second information signal associated with information read from the optical disk and to generate a first track error signal. A third signal detection circuit is configured to receive and process a third information signal associated with information read from the optical disk and to generate a second track error signal.

Abstract: A skew of an optical pickup device can be adjusted by a movable-side member itself which holds thereon an objective lens. A holder which holds an objective lens is supported by four spring wires such that it can be moved in the focusing direction and the tracking direction of an optical disk. A center of a magnetic circuit which drives the holder is shifted in the outer peripheral side relative to the optical disk. Elastic force of the spring wires of the inner peripheral side is suppressed by increasing the amount of a gel material bonded to the spring wires located on the inner peripheral side of the optical disk as a damping material as compared with the amount of the gel material bonded to the spring wires located on the outer peripheral side.

Abstract: In an optical head apparatus for an optical recording medium, including a light source for emitting a light beam, an objective lens for focusing the light beam at the optical recording medium and receiving a reflected light beam from the optical recording medium, and a photodetector for receiving the reflected light beam from the objective lens, a unit is provided between the light source and the objective lens to generate a main beam and a sub beam from the light beam. The intensity distributions of the main beam and the sub beam are different from each other, and the sub beam is divided into a plurality of portions having different phase distributions from each other. The photodetector includes photodetecting portions for each of the main beam and the sub beam, thus obtaining a push-pull signal from each of the main beam and the sub beam.

Abstract: An optical pickup device comprises an objective lens unit having an objective lens, a support member for supporting the objective lens and an objective-lens driving mechanism for driving the objective lens in a radial direction and a focusing direction of an optical disc in such a way that a light beam is focused on an information recording surface of the optical disc; and a main unit having an optical irradiation system which includes a light source for emitting a light beam and guides the light beam to the objective lens, and an optical detection system which includes a photo-sensor and guides reflected light from the information recording surface to the photo-sensor via the objective lens.

Abstract: An optical axis angle adjusting device is provided, which can adjust the optical axis angle, which can prevent sound skipping or noise in the image of the optical reproduction device even when the disk has certain surface undulation. In the adjusting device, an adjustment disk 10 is inclined relative to the turn table. Rotation phases of the disk are detected, and incident angle is detected at the respective rotation phases. The optical axis angle is adjusted so that the incident angles at the respective phases are identical with each other. Because the disk is inclined, the incident angle can be detected accurately, and the optical axis adjustment can be achieved accurately.

Abstract: In a tilt compensation method and an apparatus thereof, an apparatus that compensates for a tilt of a recordable and reproducible optical recording medium includes a tilt detector detecting a tilt of the optical recording medium and a recording compensator. The recording compensator compensates for a recording signal having a predetermined recording pattern by using a predetermined system according to the tilt detected by the tilt detector, in which the tilt detector detects a tilt with respect to an optical recording medium in which a tilt margin is greater than 0 and less than 0.0052 (0<tilt margin<0.0052) and the recording compensator compensates for the detected tilt. Thus, a desired size (length and width) of a mark can be recorded by controlling the power level and the recording time needed for recording according to the detected tilt. Also, the above method and apparatus are suitable for a high density optical disc system.

Abstract: An optical disk apparatus includes a laser diode, and a light from the laser diode becomes a parallel light by a collimator lens, which is reflected toward an object lens by a reflection mirror. The parallel light transmitted through a through-hole provided on an object lens holder is reflected by a disk, and a reflected light is incident upon a light-receiving sensor via the collimator lens, a polarizing beam splitter and a prism. The parallel light reflected by the reflection mirror is reflected by a mirror integrated with the object lens holder, and incident upon the light-receiving sensor via the collimator lens, the polarizing beam splitter and the prism. A disk tilt and/or an object lens tilt are/is detected from output signals of divided light-receiving sensors of the light-receiving sensor.

Abstract: An apparatus and method for servo control in an optical disk driver. The amount of disk eccentricity is measured, and a compensation value corresponding to the measured disk eccentricity is calculated and stored. The stored compensation value is used in the track search mode so that a more stable and precise track search operation is achieved despite the disk eccentricity caused by imperfect disk manufacturing processes or disk clamping errors. Also, when a track jump is requested during a track-following operation, the jump start point is adjusted properly, thereby reducing the time needed to complete the track jump operation, as well as reducing track jump errors.

Abstract: A liquid-crystal tilt servo apparatus in which a reference voltage generating circuit is unnecessary for a liquid-crystal driving circuit and which has a simple circuit configuration and high reliability is realized. The liquid-crystal driving circuit has a DC removing circuit for removing a DC component of a driving signal generated on the basis of a tilt error correction control signal from a control unit and supplying a resultant signal to a liquid crystal device.

Abstract: An optical-pickup device includes a plurality of light sources, an objective lens for converging light from the plurality of light sources on an optical disc, and at least one light-receiving element for receiving light reflected by the optical disc. A light source of the plurality of light sources, which light source is not used for recording/reproducing, is used for detecting relative tilt between the optical disc and the objective lens.

Abstract: An optical disc apparatus in which the inclination of an optical axis of laser light relative to an optical disc is adjusted. When data is recorded, laser light is irradiated at recording power in mark periods and irradiated at reproducing power or erasing power in space periods. Immediately after the beginning of the mark periods, no pits are ye formed even though recording power is applied and the amount of reflected light has a level corresponding to the inclination of the optical axis of laser light relative to the optical disc without influence exerted by the pits. Also in the space period, the amount of reflected light has a level corresponding to the inclination of the optical axis of laser light relative to the optical disc. By sampling the reflected light signal at the instant following to the beginning of the mark period or space periods, the inclination is adjusted so as to maximize the sampled signal level.

Abstract: A method of adjusting a condition for at least one of a recording operation and a reproducing operation includes the following steps. At least first and second asymmetry values is found. The first asymmetry value is defined based on a first signal combination selected from at least three signals different in cycle from each other. The second asymmetry value is defined based on a second signal combination selected from the at least three signals. The second signal combination is different from the first signal combination. The condition is set with reference to the at least first and second asymmetry values.

Abstract: A circuit element driver includes a control section and a driving section. The control section receives a number n of instruction values of a first group (where n≧2) and produces and outputs a number p of instruction values of a second group (where (n+1)≦p<2n) in accordance with the n instruction values of the first group. The instruction values of the first group are issued to generate voltages to be applied to n two-terminal circuit elements. The driving section generates and outputs p drive voltages in accordance with the p instruction values of the second group. At least one of the p drive voltages changes with at least one of the instruction values of the first group and is applied in common to two or more of the circuit elements at one terminal thereof.

Abstract: An optical disc reproducing device 10 has an optical pickup 11 for reading out digital data recorded on an optical disc, an amplitude detection circuit 18 for detecting the amplitude of a wobble component signal passed by a band pass filter 14, and a tilt detection, target value setting and drive signal generation circuit 23 for carrying out detection of the tilt quantity.

Abstract: This invention relates to a method for detecting and compensating the disk tilt of an optical disk and an apparatus using it. The disk tilt causes the coma which degrades the carrier-to-signal ratio of a pickup. To reduce the coma induced by the disk tilt of an optical disk, the pickup of the present invention adapts a two-dimension (2-D) grating to produce a plurality of laser beams for detecting the disk tilt in the radial and tangential direction of the optical disk. In addition, according to the radial and tangential tilts of the disk, an actuation device adjusts a reflection angle of a reflective mean to change the incident angles of the laser beams for the compensation of the coma induced by the disk tilt of the optical disk.

Abstract: An optical wavefront modifier (27) is adapted for modifying a wavefront of an optical beam passing through the modifier. The modifier comprises a first and a second transparent electrode layer (42′, 43′) and a flat medium (46) for modifying the wavefront in dependence on electrical excitation and arranged between the electrode layers. The first electrode layer (42′) comprises three or more electrodes (51-55) of a transparent, conductive material. The electrode layer also comprises a series arrangement of resistors, comprising three terminals (48, 48′, 48″) connected to the electrodes and resistors (49, 49′) connecting the terminals. The resistors are made of the same transparent conductive material as the electrodes.

Abstract: A radial tilt detector for an optical disc includes a first system for measuring a first average velocity vector of a light beam on a recording surface of the optical disc along a focusing direction of the light beam, a second system for measuring a second average velocity vector of the light beam on the recording surface of the optical disc along a radial direction of the optical disc, a third system for calculating a resultant vector of the measured first and second velocity vectors, and a fourth system for calculating the radial tilt angle of the optical disc using the measured first average velocity, the measured second average velocity, and the calculated resultant vector.

Abstract: In a method and an apparatus for aberration correction according to the invention, aberration occurring in recording/reproducing information derived from causes such as thickness variation of a substrate, a tilt, a focus error and a tracking error is detected, and the aberration is corrected by correcting these causes.

Abstract: Light emitted from a semiconductor laser is separated by a diffractive optical element into a main beam, first sub beams, and second sub beams. The distribution of the intensity of each of the first sub beams is the same as the distribution of the intensity of the main beam. The distribution of the intensity of each of the second sub beams is different from the distribution of the intensity of the main beam. The sum of the focusing error signals relating to the main beam and the first sub beams is a final focusing error signal. The difference between the tracking error signal relating to the main beam and the tracking error signal of each of the first sub beam is a final tracking error signal. The deviation of the thickness of the substrate of the disk and the radial tilt thereof are detected on the basis of the deviation of the zero crossing points of the focusing error signal and the tracking error signal relating to the main beam and each of the second sub beams.

Abstract: Within the same magnetic gap of a magnetic circuit including at least one magnet magnetized in multi-polarities, there is disposed a coil unit with a focus coil, a tracking coil and a tilt coil mounted thereon.

Abstract: An optical pickup device including a light source; an objective lens for converging a light beam emitted from the light source at a signal recording surface of an optical recording medium and irradiating the signal recording surface of the optical recording medium with the light beam; and a liquid crystal device, disposed in a light path between the light source and the objective lens, for giving a predetermined phase distribution to transmission light that passes through the liquid crystal device, with both front and back surfaces of the liquid crystal device being flat surfaces. In the optical pickup device, the liquid crystal device is constructed by sandwiching a liquid crystal molecule layer by a pair of transparent substrates.

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 (196) 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: An optical head has an initial setting for a tilt angle of an objective lens with respect to an optical disk. If a different optical disk having a different transparent layer is used for recording/reproducing data thereon, the lens actuator changes the tilt angle of the objective lens to an optimum tilt angle with respect to the different optical disk, or a optical correction device optically compensates the wave front aberration.

Abstract: An optical disc inclination detecting method for detecting an inclination angle of an optical disc with respect to a light spot, for recording information or reproducing information by irradiating the light spot on the optical disc by an optical pickup. The method includes dividing the light spot into a main spot and both side spots in a specified track and track crossing directions before and after the specified track, detecting signals corresponding to a reflected light from the optical disc by photo detectors corresponding to the main spot and both side spots, and generating a DPP (differential push-pull) signal from signals corresponding to the main spot and both side spots. The method also generates a DPD (differential phase direction) signal by comparing phases from the signals corresponding to the main spot, determining a differential operation value of the DPP and DPD signals, and detecting the inclination angle of the optical disc based on the differential operation value.