Abstract: A simple circuit configuration allows an optical disc apparatus to reduce a problem of sound skips occurring due to damage on an optical disc. To this end, an LPF extracts a low-frequency component from a tracking actuator drive signal obtained by a tracking actuator driver. When the optical disc apparatus reads and writes information to and from the optical disc, a sled drive signal supplier outputs a sled pulse signal, as a drive signal for a sled motor, for a set-up predetermined time within each interval of a predetermined length, the sled pulse signal having a level corresponding to a level of the low-frequency component obtained by the LPF. On the other occasions, the sled drive signal supplier outputs the low-frequency component obtained by the LPF as the drive signal for the sled motor.

Abstract: The optical disk device can stably control an aberration correction lens even when one end of a movable range of the aberration correction lens is set as a reference position. The optical disk device comprises an optical pickup unit including the aberration correction lens and a stepping motor for moving the aberration correction lens, wherein, when an optical disk is inserted into the optical disk device, the aberration correction lens is moved to the reference position within the movable range and near one end thereof, and wherein, when moving the aberration correction lens to the reference position, driving pulses are applied to the stepping motor to press the aberration correction lens against the one end of the movable range, and thereafter a predetermined number of pulses are applied to reversely rotate the stepping motor and to set a stop position where the aberration correction lens stops as the reference position.

Abstract: The operability of an optical disc device for reading or writing data from/to a disc having a data layer and a servo layer is improved by increasing the resistance to control disturbances. An optical disc device in accordance with the present invention includes an objective lens, a relay lens, a blue-violet laser detector, a red laser detector, an objective lens focus actuator, an objective lens tracking actuator, a relay lens actuator, a pair of focus error signal generating units, a pair of focus control signal generating units, a switching unit for selecting a focus control signal, a pair of tracking error signal generating units, a pair of tracking control signal generating units, a switching unit for selecting a tracking control signal, a focus error conversion unit and a tracking error conversion unit.

Abstract: In optical recording and/or reproduction using an SIL optical system that performs a tilt servo using light for recording and/or reproduction, the SIL and an optical recording medium have a high probability of colliding with each other before the tilt servo is started. To prevent the collision, an optical recording/reproduction method performs a gap servo that controls a gap between a surface of an optical recording medium and a bottom surface of an SIL using reflected light that is generated from light traveling from the bottom surface of the SIL and reflecting on the optical recording medium, a focus servo that controls a distance between a focal point of the light and the bottom surface of the SIL, and a tilt servo that controls a tilt of the bottom surface of the SIL relative to the surface of the optical recording medium using the reflected light.

Abstract: The present invention can promptly start the tracking control. According to an embodiment of the present invention, after making it possible to discriminate the groove G and land L by the initial drive for the objective lens, the servo control and brake control are executed under an optimum condition when the objective lens is initially driven to the inner circumference direction to be outer eccentricity where a spot Pt is easily pulled in so as to pull in the spot Pt and start tracking control, and, in case the TR control error is raised when pulling in the spot Pt in an eccentricity speed minimum region AR1 for the first time, assuming that the eccentricity speed minimum region AR1 is inner eccentricity, the spot Pt is pulled in at the next eccentricity speed minimum region AR2 in which the eccentricity direction becomes opposite and the tracking control is started.

Abstract: A data recording/reproduction method for performing a data recording/reproduction process on a flexible optical disk by rotating the flexible optical disk while controlling an axial runout of the flexible optical disk with a stabilizing member that applies an aerodynamic force to the flexible optical disk, and irradiating an optical beam and focusing the optical beam to the flexible optical disk is disclosed that includes the steps of a) generating a first axial runout, b) generating a focus error signal forming an S-curve when the first axial runout is generated, c) determining a position of the optical beam according to the focus error signal, d) generating a second axial runout that is smaller than the first axial runout after step c), and e) conducting at least one of the data recording process and the data reproduction process after step d).

Abstract: An optical drive device for performing information recording or reproduction of recorded information by formation of a mark by focusing a first light at a necessary position in a recording layer of an optical recording medium by an objective lens includes a position control unit configured to focus a second light on a reflection film, in which a position guide element of the optical recording medium is formed, through the objective lens and to enable the spot position of the second light to follow the position guide element based on the reflected light of the second light focused on the reflection film so as to control the position of the objective lens. The optical drive device further includes a first focusing unit, a first light-sensing portion, and a surface reflection light deviation amount detection unit.

Abstract: Techniques are provided for controlling the reading of optical data from a master disk in a holographic replication system. Imperfections in the master disk or movement of the disk during a recording process may cause source beams to deviate from target data tracks. In some embodiments, a detector system is used to determine the focus and alignment of the source beams on the master disk, as well as the tilt and rotation of the disk with respect to the holographic replication system. The detector system may detect deviations in the intensity distribution of the reflections of the source beams and generate an error signal corresponding to focusing, tracking, tilt, and/or rotational errors. Servo-mechanical devices may actuate optical components to compensate for such errors.

Abstract: In an optical pickup device for a simple optical system, a light beam emitted from a laser diode is split into first and second light beams by a polarized beam splitter, an optical disc is irradiated with the first light beam to obtain signal light, and the second beam is reflected by a reflection element to obtain reference light. Light beams of the signal light and the reference light are synthesized into one light beam, the synthesized light beam is separated into four light beams by a phase difference forming unit including a grating, a divided wave plate and a polarization grating, and different phase differences are afforded to the signal light and the reference light in each light beam. The four light beams are detected by one detector to generate the reproduction signal.

Abstract: A system and method for adjusting the radial tilt, tangential tilt, or a combination of radial and tangential tilt of an optical detection unit in an optical disc reading system can include applying different weighting factors to different signal components depending on which detection area detects the component, measuring a value of a signal characteristic, such as signal-to-noise ratio, of two signals with different sets of weighting factors, and determining an adjustment factor to the radial tilt as a function of the of the measured signal characteristic values.

Abstract: There is a need to provide correction of a temperature characteristic of an optical pickup of an optical disk recording/reproducing apparatus, in which items of the optical pickup including spherical aberration may be improved in temperature characteristic. To achieve the need, an optical disk drive is characterized by correcting a spherical aberration correction element when variation of a signal from the control circuit to the driver and/or a tracking or focusing error signal supplied to the controller has a value equal to or more than a predetermined value.

Abstract: An optical recording medium driving apparatus includes an optical pickup which irradiates first and second laser lights from one object lens with respect to an optical recording medium having a bulk layer and a tilt detection surface; a focus control portion that performs the focus control relative to each predetermined position of the optical recording medium in regard to each of the first and second laser lights; a tracking control portion that controls the position of the object lens to perform the tracking control of the first and second laser lights relative to the optical recording medium; and a tilt control portion.

Abstract: With a high-density optical disc drive, although it is necessary to correct spherical aberrations which depend on a disc substrate thickness error, operation of an aberrations correction element takes time and therefore easy correction according to a disc radius degrades the operability of the apparatus. The present invention comprises an optical pickup unit including an objective lens and an aberrations correction lens, a focus actuator, a tracking actuator, a aberrations correction motor, a seek motor, an aberrations correction lens control module, a radius information detecting module, and a system control module.

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 for performing information recording using formation of marks by focusing a first light with an objective lens at a given position in a recording layer included in an optical disc recording medium, includes: a rotation driving unit; a focus servo control unit for condensing a second light on a reflection film and for controlling a position of the objective lens; a recording position setting unit for setting an information recording position of the first light in a focus direction; a tracking servo control unit for controlling a position of the objective lens; an eccentricity amount estimating unit for estimating an eccentricity amount of the optical disc recording medium; and an eccentricity estimation amount acquisition control unit for acquiring an eccentricity estimation amount for each rotation angle within one revolution of the disc.

Abstract: In a servo controller and an optical disk device (FIG. 4), the following performance for disturbance is improved. By disposing a characteristic change section to change a characteristic to improve the following performance for disturbance, the disturbance is detected by use of a signal in a stage after the characteristic change section.

Abstract: An objective lens element which can obtain appropriate spot performance only by simple position adjustment, and an optical pickup device using the objective lens element are provided. In the objective lens element, an amount of a generated third-order astigmatism of a spot which is formed when symmetry axes of optically functional surfaces are located parallel to the normal line of a base plate and an incident light beam incident such that a central light beam thereof is tilted at 0.5 degree with respect to the normal line of the base plate is converged, is reduced to be less than an amount of a generated spherical aberration of a spot which is formed when the symmetry axes of the optically functional surface are located parallel to the normal line of the base plate and an incident light beam incident parallel to the normal line of the base plate is converged.

Abstract: Stable interlayer jump is realized by judging whether a signal is a false signal caused by noises, stray light, or interference of an adjacent layer or a true FE signal.

Abstract: An optical disc apparatus, for executing recording or reproducing on an optical disc having at least two recording/reproducing layers, includes an optical pickup, having a sphere aberration compensating portion, an objective lens, a driver portion, and an obtaining portion. The sphere aberration compensating portion sets up a compensation volume corresponding to an intermediate position laying between a deepest layer and a most front layer from the optical pickup, and the driver portion drives the objective lens in a direction approaching to the optical disc in accordance with the set compensation volume. When the sphere aberration compensating portion sets up the compensation volume corresponding to the deepest layer, and when the objective lens is driven in a direction approaching the optical disc, the driver portion drives the objective lens in a direction of separating from the optical disc.

Abstract: A method for performing a servo defect compensating operation by compensating a servo-related signal in an optical disc drive and a related optical disc drive system with a DSP is provided. The method comprises: reading an optical medium by an optical pick-up unit; detecting whether a defect exists by monitoring a side beam signal; when the defect on the optical medium is detected, determining a new compensation value based on a servo error signal; and compensating the servo-related signal with the new compensation value during defect crossing to adjust servo control when the optical pick-up unit passes the defect.

Abstract: A method for assembling an optical pickup apparatus for recording/reproducing a high density DVD, DVD and CD including two objective lens and three laser light sources, the objective lenses being provided on the lens holder having an actuator base for supporting the actuator, the method for assembling the optical pickup apparatus comprises the steps of adjusting a first tilt angle of the actuator base so that a coma aberration of a spot formed by the first light beams decreases when the first light beams are converged onto the first recording medium via the first objective lens, and adjusting a second tilt angle formed between the second objective lens and the lens holder so that a coma aberration of a beam spot formed by the second light beams decreases when the second light beams are converged onto the second recording medium via the second objective lens.

Abstract: A recording/reproducing apparatus includes: a light source; a first correction section to correct a position of an objective lens that collects laser light from the light source on a surface of an optical disc based on a focus bias setting value obtained from a focus bias value; a second correction section to correct an aberration of the laser light based on an aberration correction setting value obtained from an aberration correction value; an evaluation value generation section to generate an evaluation value; a focus bias adjustment section to change plus/minus of the focus bias value and calculate a new focus bias value based on the evaluation value every time a first cycle passes; and an aberration adjustment section to change plus/minus of the aberration correction value and calculate a new aberration correction value every time a second cycle passes, in parallel with an update of the focus bias value.

Abstract: Methods of optimizing optical alignment in an optical package are provided. In one embodiment, the optical package includes a laser diode, a wavelength conversion device, coupling optics positioned along an optical path extending from the laser diode to the wavelength conversion device, and one or more adaptive actuators. The method involves adjusting the optical alignment of the wavelength conversion device in a non-adaptive degree of freedom by referring to a thermally-dependent output intensity profile of the laser diode and a thermally-dependent coupling efficiency profile of the optical package.

Abstract: Disclosed herein are an optical recording medium driving device and an additional recording method, which performs tracking servo control for moving an objective lens in a direction orthogonal to a tangential direction of a guide track so that a guide tracking error signal is decreased with respect to a guide track of a guide layer separation type recording medium, detects an additional recording start position subsequent to a recorded track if the recorded track is present in a recording layer of the optical recording medium, generates a tracking correction signal according to the reproduction tracking error signal upon tracking servo control of the recorded track just before the additional recording start position, and corrects tracking servo control according to the tracking correction signal upon additional recording start.

Abstract: There is provided a method of recording and reproducing an optical recording medium which performs a tracking servo and a focusing servo by irradiating a laser beam onto determined positions including lands and grooves of a track of the recording medium and detecting a tracking error signal and a focusing error signal using an electric signal from an optical pickup for picking up the laser beam reflected from the recording medium. The method includes the steps of: detecting servo information in a plurality of the determined positions including lands and grooves of the track while rotating the recording medium in a state in which only the focus servo is turned on when the optical recording medium is loaded, storing the servo information of the respective determined positions as a table, and performing the servo of the corresponding positions by applying the servo information in table during an actual data recording/reproduction.

Abstract: An optical pickup apparatus comprising: a diffraction grating that a laser beam enters, the diffraction grating being configured to generate a main beam that is 0th order light and sub-beams that are +1st order diffracted light and ?1st order diffracted light; an objective lens configured to focus the main beam and the sub-beams onto a signal recording layer; a main-beam light-receiving portion that the main beam reflected by the signal recording layer is applied to; and sub-beam light-receiving portions that the sub-beams reflected by the signal recording layer are respectively applied to, each light-receiving area of the sub-beam light-receiving portions being smaller than a light-receiving area of the main-beam light-receiving portion.

Abstract: An optical recording/reproducing apparatus and a data recording method thereof. The optical recording and/or reproducing apparatus includes: an encoder which encodes a data for recording in a specified format; an optical pickup which records the encoded data onto a data record area of an optical recording medium which is loaded in the optical recording/reproducing apparatus; and a controller which allocates a specified area of the optical recording medium as a management information record area, controls the optical pickup to record the management information regarding the data being recorded in the data record area to be recorded in the management information record area, and controls the optical pickup to periodically record the management information of the management information record area onto a file information record area of the optical recording medium.

Abstract: A position-error-signal calculation circuit (105) calculates a relative position error between a laser-focused-beam spot (103) and an information recording layer (102), and generates a focus error signal (106). A filter (108) amplifies and passes therethrough a signal component in the vicinity of the natural resonance frequency of at least one mode among the natural vibration modes of the optical disc medium (101). A drive amplifier receives through a stabilizing compensator (109) and a D/A converter (110) the focus error signal (106) passed by the filter (108), to drive an objective lens (113), thereby allowing the laser-focused-beam spot (103) to track the information recording layer (102).

Abstract: An optical disc apparatus, for executing recording or reproducing onto/from a multilayered optical disc having “N” pieces of recording layers (N?3, “N” is an integer), from a first layer to a Nth layer, including a light emitting portion configured to emit a laser beam, a light receiving portion, a correcting portion configured to correct a tilt of the optical disc or an aberration of the laser beam, an adjusting portion, a detecting portion, and a selecting portion configured to select “A” pieces of recording layers (A<N, and “A” is an integer) depending on the layer structure of the optical disc. The adjusting portion obtains the correction volumes on the “A” pieces of recording layers, which are selected by the selecting portion.

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: An optical disk apparatus includes a rotary driving unit rotating an optical disk which is flexible, an optical pickup irradiating light upon a recording surface of the optical disk on which writing/reading of information is performed, a stabilizing unit stabilizing vibration of the optical disk in a rotary axial direction by using pressure difference of air flow at least on a portion where writing/reading is performed, and being disposed on a side of the optical disk opposite to a side on which the recording surface is provided, and a control-adjustment unit analyzing a value of a tracking error signal of the optical disk obtained by scanning along a groove of the optical disk with use of the optical pickup, comparing the analyzed value of the tracking error signal of the optical disk and a value priorly obtained by scanning along a groove of a standard disk prepared beforehand, and adjusting a positional relation between the optical disk and the stabilizing member in a three dimensional space according to t

Abstract: In an optical disc drive apparatus, when a start time of a tracking pull-in operation is adjusted according to the eccentricity amount of the optical disc, a suitable starting point of the tracking pull-in operation can be always captured and the pull-in operation of the tracking control can be stably performed, without depending on the eccentricity amount of the optical disc. Further, the eccentricity amount and an eccentricity phase are detected from a track zero crossing signal before the tracking pull-in, and an eccentricity compensation signal of the track is added to the tracking control signal. As a result, also in the optical disc with the large eccentricity amount, the tracking pull-in operation can be stably performed.

Abstract: An optical defect detection method for patterned media includes: irradiating a laser beam onto a patterned medium and obtaining reflected light by reflection very close to a sample; outputting the reflected light as an analog electrical signal from an optical receiver; converting the analog signal to a digital signal; obtaining a surface profile in a track direction by sampling the analog signal; obtaining a servo area profile by setting a slice for detecting servo area; calculating an average value in a track width direction based on plural servo area profiles; generating a master servo area profile based on the average value; obtaining a difference between the master servo area profile and the specific servo area profile; and detecting the presence of a defect including surface roughness, process fluctuation, and adhesion of foreign matters, from a differential waveform.

Abstract: A recording device including a light irradiating and light receiving unit which, in regard to an optical recording medium, which has a reference surface and a recording layer which is formed at a depth position different from the reference surface, where a pit row where intervals of pit formable positions in one circumference is limited to a first interval is formed in the reference surface, and which has a plurality of pit row phases by intervals of the pit formable positions in a pit row formation direction being set in a position which is each deviated by a predetermined second interval in the pit row which are arranged in the radial direction, irradiates a first light as recording light with regard to the recording layer and a second light for obtaining reflected light from the reference surface and which receives reflected light of the second light from the reference surface.

Abstract: A temperature sensor is disposed in an optical pickup to detect a temperature of an objective lens. An optical element (for example, a collimator lens) is driven according to a temperature change of the objective lens, which corrects deterioration of an optical characteristic of a laser beam passing through the objective lens. Good recording/reproduction is smoothly performed even if the optical characteristic of the objective lens is changed with the temperature change.

Abstract: Prevention of deletion of data in an unintended recording layer of an optical disc is ensured even when servo deviation occurs while controlling data reproduction. A light source outputs a light beam with light intensity according to a driving current on which a high frequency signal is superimposed. The light beam is collected on a recording layer of an optical disc. As triggered by detection of servo deviation during data reproduction, a light intensity controller adjusts a superimposed amount of the high frequency signal in the driving current to suit to a specific recording layer with the lowest reproduction tolerance in the optical disc and thereby controls the light intensity of the light beam output from the light source.

Abstract: An optical pickup apparatus comprising: a laser diode; an objective lens made of synthetic resin arranged in an optical path of laser light between the laser diode and an optical disc so that the laser light from the laser diode is focused onto a signal recording layer through a protection layer of the optical disc; and an aberration correction element interposed in an optical path of the laser light between the laser diode and the objective lens, the aberration correction element configured to be operated so as to correct spherical aberration caused by moisture-absorption characteristics of the objective lens.

Abstract: A reproduction signal evaluation method evaluates the quality of a reproduction signal reproduced from an information recording medium based on a binary signal generated from the reproduction signal using a PRML signal processing system. The method includes a pattern extraction step of extracting, from the binary signal, a specific state transition pattern which has the possibility of causing a bit error; a step of computing a differential metric based on the binary signal; an extraction step of extracting the differential metric which is not greater than a predetermined signal processing threshold; a step of determining a mean value of the differential metrics which are not greater than the signal processing threshold and extracted in the extraction step; a standard deviation computing step of determining a standard deviation which corresponds to an error rate predicted from the mean value; and an evaluation step of evaluating a quality of the reproduction signal using the standard deviation.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is discussed that includes a summation circuit, a data detector circuit, an error feedback circuit, and an error calculation circuit. The summation circuit subtracts a low frequency offset feedback from an input signal to yield a processing output. The data detector circuit applies a data detection algorithm to a derivative of the processing output and provides an ideal output. The error feedback circuit includes a conditional subtraction circuit that conditionally subtracts an interim low frequency offset correction signal from a delayed version of the derivative of the processing output to yield an interim factor. The error calculation circuit generates an interim low frequency offset correction signal based at least in part on the interim factor and a derivative of the ideal output.

Abstract: An objective lens driving apparatus includes an objective lens (13) collecting a light flux emitted from a light source on a optical disk (11), and a lens holder (14) holding the objective lens (13). The lens holder (14) includes a first bonding portion (14i) and a second bonding portion (14j) for holding the objective lens (13) by means of bonding. The objective lens (13) is fixed to the lens holder (14) by applying a first bonding adhesive (25) to the first bonding portion (14i) to thereby bond the objective lens (13) thereto, adjusting an inclination of an optical axis of the objective lens (13) while causing the first bonding adhesive (25) to deform, and applying a second bonding adhesive (26) to the second bonding portion (14j). The second bonding adhesive (26) has a larger Young's modulus after curing than the first bonding adhesive (25).

Abstract: An optical disc apparatus according to the present invention includes a disc type recognizing section for determining whether the optical disc loaded is a first type, of which the number of information storage layers is less than a setting T (where T is an integer that is greater than two), or a second type, of which the number of information storage layers is equal to or greater than the setting T. Depending on whether the optical disc loaded has turned out to be the first type or the second type, the apparatus determines the read/write preprocessing (such as whether a fingerprint detection process needs to be performed or not).

Abstract: A disk drive for driving a disk is disclosed, which includes: a driving unit configured to provide a driving force onto the disk, a main circuit pattern electrically connected with the driving unit, a sensor unit configured to sense a rotation speed of the disk, a first board supporting the sensor unit, a second board supporting the first board, and a base plate supporting the second board and the driving unit. One of the first board and the second board can be a flexible board electrically connecting the sensor unit with the main circuit pattern, and the other of the first board and the second board can be a rigid board. This disk drive can be utilized to ensure the distance between the sensor unit and the disk required for a rotation sensor to measure the rotation speed of the disk.

Abstract: An optical recording medium drive device including: a combining prism for combining a recording first laser beam emitted from a first light source with a recording second laser beam emitted from the first light source so as to coaxially guide them; an objective lens for condensing the first and second laser beams from the combining prism toward an optical recording medium; a first photodetecting means for detecting reflected light of the first laser beam from a recording layer; a second photodetecting means for detecting reflected light of the second laser beam from a guide layer; a magnification conversion element disposed on an optical path of the second laser beam between a second light source and the combining prism for diffusing or converging the second laser beam incident upon the objective lens; a first focus error generating means for generating a first focus error signal indicating an error between a condensed spot position of the first laser beam and the recording layer based on an output signal of

Abstract: To provide write protection of a disc in a bare state that is usually used in a cartridge having a recognition switch for write protection, such as a DVD-RAM, write protection information is recorded in a Lead-in area, a Lead-out area or a recording information area other than a user data area of the disc, and the data is protected from unwanted overwriting or erasing using the write protection information. Even when the write protection information stored on a disc does not match the state of a recognition switch of a case for write protection, the data can be prevented from unwanted overwriting or erasing. Thus, write protection can be ensured when a recordable and/or rewritable recording medium, such as a DVD-RAM, a DVD-R or a DVD-RW, is used in a bare state.

Abstract: A spherical aberration compensation method is provided. A first thickness of a cover layer at a first radius position of an optical disc is measured. A second thickness of the cover layer at a second radius position of the optical disc is measured. A spherical aberration calibration is performed at a third radius position of the optical disc to obtain an optimal spherical aberration compensation value. According to the first and second radius positions, the first and second thicknesses, and the optimal spherical aberration compensation value at the third radius position, a spherical aberration compensation formula is acquired. Afterwards, an updated spherical aberration compensation value is calculated by the spherical aberration compensation formula according to a fourth radius position where an optical pickup head of the optical disc drive is located. The updated spherical aberration compensation value is inputted into a spherical aberration compensator of the optical disc drive.

Abstract: An optical disk driving apparatus includes an optical head device having a laser light source, a converging optical system converging a light beam emitted by the laser light source onto an optical disk, a photo detector receiving reflected light reflected by the optical disk, and an aberration correcting optical system controlling aberration of the converging optical system; a motor rotating the optical disk; and a control section receiving a signal from the photo detector, wherein the converging optical system has an objective lens formed using resin as a main material, the aberration correcting optical system has a spherical aberration correcting element correcting spherical aberration, and the control section evaluates quality of a reproduction signal for information in the optical disk by using the reflected light received by the photo detector, and utilizes a result of the evaluation to perform closed loop control on the spherical aberration correcting element.

Abstract: A method for determining an optimal combination of focus bias and spherical aberration compensating value (SA value) in an optical disc drive is provided. Firstly, a first focus bias is set, the SA values are adjusted and the corresponding tracking error signal values are measured. Second-order-approximation is performed to obtain a first maximum value of tracking error signal. Secondly, a second focus bias is set, the SA values are adjusted and the corresponding tracking error signal values are measured. Second-order-approximation is performed to obtain a second maximum value of tracking error signal. Thirdly, a third focus bias is set, the SA values are adjusted and the corresponding tracking error signal values are measured. Second-order-approximation is performed to obtain a third maximum value of the tracking error signal. The three maximum values are compared to obtain the optimal combination of focus bias and SA compensating value in the optical disc drive.

Abstract: An optical pickup apparatus changes a propagation direction of luminous fluxes, out of a laser light reflected by a disc, in four luminous flux regions set about a laser optical axis so as to mutually disperse these luminous fluxes. A signal light region in which only a signal light is present appears on a detection surface of a photodetector. A plurality of sensors for a signal light are placed at positions irradiated with the signal light within the region. When an arithmetic process is performed on a detection signal outputted from each sensor, a DC component occurring in a tracking error signal is suppressed.

Abstract: A device for protecting a servo in reading signals on a defect disc from disturbance and instability is provided. The device includes a defect detection unit and a logic combination unit. The defect detection unit receives a plurality of defect detection signals to detect various defects for setting a plurality of defect flag signals, wherein the plurality of defect detection signals at least include an envelope signal of a RF signal and bit modulation signals. The logic combination unit performs logic operation on the defect flag signals in order to detect a specified defect. The logic combination unit indicates a servo control unit generating low-pass output signals according to said plurality of defect flag signals for controlling related electromechanical devices to prevent from disturbance and instability when the specified defect is detected. A method for protecting a servo in reading signals on a defect disc is also provided.

Abstract: A method of operating a channel module, including: receiving a plurality of sensor signals generated based on at least one detected characteristic of a laser beam of an optical drive; performing computations based on the plurality of sensor signals; generating a computation output signal based on the computations; generating a first control signal and a second control signal; generating a first input signal based on (i) the computation output signal, (ii) the first control signal, and (iii) a first set of filter values; generating a second input signal based on (i) the second control signal, (ii) a second set of filter values, and (iii) an accumulated output signal; generating the accumulated output signal based on a sum of products generated based on the first input signal and the second input signal; and adjusting the at least one detected characteristic of the laser beam based on the accumulated output signal.