Abstract: An apparatus for detecting a probe position error includes a position error extracting unit extracting probe position errors from signals detected by a probe; a position error adding unit calculating the probe position errors in units of a predetermined time; and a signal processing unit storing a past probe position error calculated by the position error extracting unit and generating a probe position error by processing the past probe position error and a current probe position error. An apparatus for tracking data includes a scanner moving a data storage medium; a probe detecting the signals from a data storage medium; an error detector detecting probe position errors in a half-period of an error extracting signal by applying the error extracting signal used to extract the probe position errors to the signal detected by the probe; and a compensator compensating for the probe position errors detected by the error detector.

Abstract: A visible light characteristic changing layer formed from photosensitive or heat-sensitive material is formed in a location which can be viewed from a part of a label surface of an optical disk. The optical disk is set on a turntable of an optical disk unit while the label surface of the optical disk is directed downward. The optical disk and an optical pickup are moved mutually along the plane of the optical disk. In synchronism with the relative movement, the power of a laser beam output from the optical pickup is modulated in accordance with image data, such as characters or graphic images to be printed, and the laser beam is emitted onto the visible light characteristic changing layer. As a result of the visible light characteristic changing layer being exposed to the laser beam, a visible-light reflectivity of the visible light characteristic changing layer is changed, thereby forming a image corresponding to the image data on the label surface.

Abstract: One of the objects of the invention is to provide an optical disc apparatus capable of focusing on a signal surface regardless of appearance of a fake signal. The optical disc apparatus includes: an optical pickup for outputting a signal on the basis of reflection light of the optical disc, the optical pickup including an objective lens; a driving section for moving the objective lens of the optical pickup relative to an optical disc surface; and a focus controlling section for carrying out a focus detecting operation by detecting a reflection signal on a signal surface of the optical disc from the output signal of the optical pickup within a predetermined range of distance between the objective lens and the optical disc surface while the objective lens is being moved relative to the optical disc surface by means of the driving section.

Abstract: An optical disc apparatus in which, regarding mutually adjacent recording layers, a focus offset of an optical system to a guide groove formed in a recording surface of the recording layer is learned based on a signal based on reflected light from the guide groove, and a focus offset for recording or reproduction is calculated and set based on the learned focus offsets for the respective recording layers. As the focus offset of the optical system for recording or reproduction, a mean value of the learned focus offsets for the respective recording layers is set as a focus offset common to the both recording layers. Otherwise, a focus offset when a difference between the focus offset and the learned focus offsets for the respective recording layers is a value corresponding to a characteristic of the optical system is set. This structure reduces processing time and ensures processing precision upon focus offset processing for plural recording layers.

Abstract: A focus servo system with a focus close algorithm is disclosed. The focus close algorithm provides a bias control effort to the focus servo system when focus is closed. A method of closing focus includes positioning an optical pick-up unit at a first position away from an optical medium, moving the optical pick-up unit towards a second position by altering a focus control effort, monitoring a sum signal obtained from signals received from the optical pick-up unit, and setting the bias control effort to the focus control effort when a closure criteria is satisfied. In some embodiments, the closure criteria includes that a sum signal exceeds a threshold value. In some embodiments, the closure criteria includes that a focus error signal is below a FES threshold.

Abstract: A system and methods for evaluating the response of an optical digital disk player to vibration encountered during playback of optical digital disks are provided. The system includes a simulator configured to provide digital simulated output signals simulating the output of an optical digital disk player encountering vibration during playback of an optical digital disk. The system also includes digital-to-analog converter circuitry to convert the digital simulated output signals to analog simulated output signals and provide the analog simulated output signals to processing circuitry. The processing circuitry generates control signals based on the value of the analog simulated output signals, and provides the control signals as outputs.

Abstract: A tracking error control system includes a tracking error signal generator in communication with an optical pickup head, a DC detector in communication with the tracking error signal generator and a comparator in communication with the DC detector and the tracking error signal generator. The operating optical signals received by the optical pickup head are operated with an offset signal to generate a tracking error signal. A direct current voltage of the tracking error signal is detected and compared with a reference voltage. The offset signal is adjusted according to the comparison result and fed back to the tracking error signal generator to adjust the tracking error signal.

Abstract: An apparatus and method for digitally detecting a tracking error signal using multiple phase clocks. The apparatus includes a phase extractor receiving four divided outputs in response to light reflected from an optical disk and extracting four divided phases, respectively, a phase difference detector detecting phase differences between two phases among the four divided phases, a multiple phase clock generator generating a plurality of phase clocks in response to a predetermined clock signal, a phase error detector counting phase differences in response to each of the plurality of phase clocks, summing the counted phase differences, and detecting a phase error, and a tracking error output unit detecting the tracking error signal in response to the phase error and outputting the detected tracking error signal.

Abstract: In an optical disc apparatus, whether an unrecorded recording layer without information recorded thereon is included in the multiple recording layers of the optical disc mounted inside the apparatus is judged. then when the unrecorded recording layer is judged to be present, a signal for focus offset adjustment is recorded in a non-user data recording area of the unrecorded recording layer, and reproduction of the recorded focus offset adjusting signal is followed by its quality evaluation, which is further followed by calculation and setup of an appropriate focus offset value based on evaluation results.

Abstract: An apparatus for detecting an oscillation of a servo controller of an optical disk is provided. An oscillation detector, electrically coupled to the servo controller of the optical disk, is provided and is configured to receive an error signal associated with the servo controller. The oscillation detector is further configured to compare an amplitude, a width and a period of the error signal with a reference amplitude, a reference width and reference period to determine if an oscillation is present in the error signal. Related methods and computer program products are provided.

Abstract: A recording device including a beam deflection section for relatively moving an irradiation position of an exposure beam with respect to a substrate on which a resist layer is formed; a substrate velocity adjustment section for adjusting a moving velocity of the substrate based on a deflection amount of the exposure beam; and a deflection control section for controlling to change a deflection velocity of the exposure beam during exposure of the recording signals according to the moving velocity of the substrate.

Abstract: An optical disk apparatus includes: a servo controller, operable to carry out a servo control of tracking of an optical pickup based on a tracking error signal; a TE balance regulator, operable to detect a TE balance correction value for equalizing, with a reference voltage, a central voltage of the tracking error signal when a beam spot of the optical pickup crosses a track; a detrack regulator, operable to detect a detrack correction value for causing signal quality of an output of the optical pickup to be the highest; and a TE offset corrector, operable to set an offset voltage, which is to be added to the tracking error signal, to be the TE balance correction value when a difference between the TE balance correction value and the detrack correction value is smaller than a predetermined value, and to set the offset voltage to be a value between the TE balance correction value and the detrack correction value when the difference is greater than the predetermined value.

Abstract: A disc device includes a lens that focuses a laser light on an optical disc surface, a focus drive unit that drives the lens in a focusing direction, a focus control unit that controls to focus the laser light on the optical disc surface, a focus displacement detecting unit that detects a displaced amount in the focusing direction, a differentiation unit that differentiates a focus displacement detected signal, and a unit that inverts a sign of a differentiated signal, thereby, the disc device is driven intermittently to restrain a motion of an objective lens in a focusing direction and avoid colliding the objective lens with the optical disc surface.

Abstract: The present invention relates to a servo-controlling method of an optical disk apparatus. In the present invention, an order on which servo-control manner is sequentially applied is determined in advance based on various depth to respective recording layers of a CD, a DVD, and a high-density DVD, and when a disk is placed a servo-control manner is sequentially selected in the determined order. Therefore, a collusion between a disk and an optical pickup can be prevented for any type of disk.

Abstract: A high-density read-only optical disc, and an optical disc apparatus and method using the same. The apparatus and method record data on a lead-in area of a high-density read-only optical disc such as a BD-ROM (Blu-ray disc ROM (Read Only Memory)) in the form of pre-pit strings associated with an HFM (High-Frequency Modulated) groove applied to a BD-RW (Blu-ray Disc Rewritable). Moreover, the apparatus and method continuously apply the same tracking servo operation to an entire area of the same high-density read-only optical disc or rewritable optical disc. Therefore, the apparatus and method can simplify an algorithm for controlling a plurality of tracking servo operations, and avoid an increased size of the optical disc apparatus.

Abstract: A recording/reproducing apparatus and a tracking control method which can perform data processing for reliably recording or reproducing data on or from a recording medium are disclosed. Tracking error signal (TE) is generated using difference signal (A?B) produced from reflected light from a recording medium and an offset included in the difference signal is compensated for using another reflected light received separately from the reflected light. Offset-compensated tracking error signal ((A?B)?k(C?D)) is obtained by subtracting another difference signal (C?D) produced from the separately received reflected light according to gain (k) from difference signal (A?B). Different gains may be used for areas on the recording medium having different reflectances. Thus, the tracking error signal can be compensated for an optical offset caused by lens movement and an offset caused by different reflectances and light radiated to the recording medium can accurately follow its track to perform reliable data processing.

Abstract: The present invention discloses an apparatus for generating a TE signal in an optical disc drive. The disclosed apparatus includes a signal generation module, a quality detection module coupled to the signal generation module, and a signal-synthesizing module coupled to the signal generation module and the quality detection module. The signal generation module generates a first and a second candidate TE signal according to a light beam reflected off an optical disc. The quality detection module estimates the signal quality of the first and/or the second candidate TE signal and controls the signal-synthesizing module accordingly. The signal-synthesizing module generates the TE signal according to the first and/or the second candidate TE signal.

Abstract: The optical scanning device [10] is arranged for scanning a record carrier [1]. The record carrier has an outer face [7]. The scanning device comprises a radiation source [11] for generating a radiation beam [12] and an objective system [25] having an exit face [26] arranged for evanescent coupling of the radiation beam between the exit face and the outer face and for converging the radiation beam to a focus [27]. A tilt measuring system [67, 77] provides a tilt signal [87; 88] representing a tilt angle between the objective system and the record carrier. A control unit [95] determines a distance signal representing a distance between the exit face and the focus from the tilt signal.

Abstract: Disclosed is an optical disc apparatus that sets a plurality of virtual zones, which correspond to a plurality of zones that are arranged in the radial direction of an optical disc, for a plurality of recording layers of the optical disc. When a servo signal distortion is detected in a virtual zone to change the rotation speed of the optical disc to a low speed in the virtual zone during an information recording or reproduction operation relative to a first recording layer, the optical disc apparatus stores the change information. When a recording or reproducing operation is to be performed in a virtual zone of a second recording layer, which is in the same disc radial position as the virtual zone of the first layer, the optical disc apparatus changes the rotation speed of the optical disc for the virtual zone to a low speed in accordance with the change information.

Abstract: A method for controlling a stepper motor in an optical disc system, comprising the steps of (A) measuring a static offset of a center error signal, (B) measuring a maximum value, minimum value and an average value of the center error signal in response to rotating the optical disc, (C) computing one or more upper threshold values and one or more lower threshold values of the center error signal, (D) sampling the center error signal, (E) comparing the center error signal to the one or more upper threshold values and to the one or more lower threshold values and (F) computing a control output to control the stepper motor in response to comparing the center error signal to the one or more upper and lower threshold values.

Abstract: The invention provides a reproduction apparatus that reproduces information recorded in a recording medium having plural recording layers, including: an optical head that irradiates laser beams on the respective recording layers and detects reflected light information to read out information recorded in the respective recording layers; a shaft sliding type focus actuator that holds the object lens; a focus servo section that generates a focus servo drive signal and drives the focus actuator such that a focus state of the laser beams is kept in a state of focus on a recording layer on which the reproduction is performed; and a focus jump control section that generates a kick signal for starting focus jump movement by the focus actuator and a brake signal for ending the focus jump movement.

Abstract: An optical disk drive includes: a light source for producing a light beam; an objective lens for converging the light beam; an actuator for moving the objective lens with respect to an optical disk; a converging state detecting section for generating a focus error signal representing a converging state of the light beam on an information storage layer of the optical disk; and a focus control section for controlling the operation of the actuator such that the focus position of the light beam matches its target focus position as closely as possible in accordance with information about the target focus position and the focus error signal. The optical disk drive changes the target focus positions of the light beam when modes of operation are switched from a read mode into a write mode, or vice versa.

Abstract: In a particle-beam projection processing apparatus a target (41) is irradiated by means of a beam (pb) of energetic electrically charged particles, using a projection system (103) to image a pattern presented in a pattern definition means (102) onto the target (41) held at position by means of a target stage; no elements—other than the target itself—obstruct the path of the beam after the optical elements of the projection system. In order to reduce contaminations from the target space into the projection system, a protective diaphragm (15) is provided between the projection system and the target stage, having a central aperture surrounding the path of the patterned beam, wherein at least the portions of the diaphragm defining the central aperture are located within a field-free space after the projection system (103).

Abstract: An optical disk apparatus for correcting astigmatism that influences the read/write. If there is astigmatism, and auto-focus and tracking control are in operation, then a push-pull signal amplitude and a 2T signal amplitude vary with the variation of an amount of spherical aberration, resulting in two cases. In one case, the amount of spherical aberration to give the maximum value of push-pull signal amplitude agrees with the amount of spherical aberration to give the maximum value of 2T signal amplitude, and in the other case the two amounts do not agree. If there is no astigmatism, two amounts agree each other. If there in no agreement, then correction is made by using an astigmatism correcting element until the agreement is reached between the two. In the case where two amounts agree, specification is made for the existence and angle of astigmatism, and correction is made by using focus error signals from adjacent tracks.

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

Abstract: An information recording apparatus is provided with: a recording device for recording information onto an information recording medium; a detrack detecting device for detecting occurrence of detrack during the recording of the information; and a controlling device for controlling the recording device to return to a location where the detrack has occurred and restart the recording if the occurrence of the detrack is detected.

Abstract: In an optical disc device employing a CLV method, executing pickup return processing when focus drop occurs during recording poses problems of increased waiting time for rotation and increased focus servo recovery processing time. When defocusing occurs and focus pull-in cannot be achieved by retry, a first rotation frequency at a radial position thereof is calculated. Next, a second rotation frequency at the innermost circumferential position at the current speed is calculated. Next, a third rotation frequency at a radial position where recording is restarted after focus servo recovery is calculated. Next, a fourth rotation frequency at pickup return position at a different speed is calculated.

Abstract: The method prevents an optical disk from being scraped by an optical apparatus of a pickup head of an optical disc drive is disclosed, it mainly includes: moving the optical apparatus of the pickup head to a detection position in which the laser-light emitted from the pickup head focuses on the optical disk; detecting the first-detection position and setting a movement boundary according to the first-detection position, wherein the movement boundary has a upper boundary and a bottom boundary; preventing the optical apparatus from moving out of the movement boundary. The present method can be implemented without installing any additional apparatus in the original video disc player, and can prevent the optical disk and the inner apparatus of the optical disc drive from being scraped or damaged by the pickup head during a read/write process to increase the service life of the optical disk and the optical disc drive.

Abstract: In an optical disc apparatus, the amplitude level of a focus error signal for performing focus search is measured, and in order to bring the measured amplitude level of the focus error signal to a target value, gains of focus servo drive amplifiers which amplify respective detection signals from four respective divided detection regions of an optical detector are set as initial values. As a result, the amplitude level of the focus error signal is adjusted at the target value. Next, the amplitude levels of the detection signals from the respective detection regions are measured, and the gains of the respective focus servo drive amplifiers are adjusted individually so that crosstalk can be cancelled based on the measured amplitude levels of the detection signals.

Abstract: An apparatus for scanning a track on a record carrier has a head (41) for providing a beam of radiation and generating at least one sensor signal. The device has a focusing unit for controlling a focusing element to maintain an in-focus position for generating a focused spot on the track. The sensor signal is converted into a displacement signal by a multitude of piecewise converters (42, 43, 44), each converter converting a range of the sensor signal values into a position signal, and selection means (46) for selecting one of the position signals as the displacement signal based on an estimated displacement.

Abstract: Defocus detection device and method capable of detecting a defocus accurately during recording of information to an optical disk having a plurality of recording layers and an optical disk unit using the device and method are provided. A temporal restriction is imposed on defocus detection and besides, in comparison with a level for detection of a first change of a focus error signal developing during a defocus, a level for detection of a successively occurring second change of a polarity inverse to that of the first change is made to be smaller. When the first level is exceeded and thereafter the second level is exceeded within a restricted time, a defocus is detected.

Abstract: Disclosed is a system for detecting a location of an optical pick-up head on an optical disk, and the optical disk comprises a plurality of sectors and the optical pick-up head emitting light to the optical disk and detected the reflected light from the optical disk. The system comprises: a signal generator, a counter, and a processing unit. The signal generator is coupled to the optical pick-up head for receiving a detecting signal from the optical pick-up head to generate a sector determined signal. The counter is coupled to the signal generator for receiving the sector determined signal and a period determined signal for counting a number according to the sector determined signal and the period determined signal; and a processing unit for receiving the number and calculating the location of the optical pick-up head accordingly.

Abstract: A system and method of drawing a visible image on an optical disk are provided. The optical disk is rotated while a optical pickup irradiates a laser beam onto the optical disk to draw the visible image on the optical disk. The rotating state of the optical disk is detected. The optical pickup is fed in a radial direction of the optical disk. An irradiating position of the laser beam is controlled relative to the optical disk by fixing the laser beam in the radial direction of the optical disk during one rotation of the optical disk, and shifting the irradiating position of the laser beam by a first distance in the radial direction each time one rotation of the optical disk is detected. The optical pickup is fed in the radial direction by a second distance the optical disk has rotated a predetermined number of rotations.

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

Abstract: A method controls an assembly using an oscillating wave, such that the assembly moves in an oscillated manner in relation to a surface of an optically writable medium in correspondence with oscillation of the oscillating wave. The assembly generates a beam towards the surface of the optically writable medium. A proximity signal is detected in response to the beam being generated towards the surface of the optical medium, and denotes closeness of the assembly to the surface. A number of peaks within the proximity signal are determined. The time at which each peak within the proximity signal occurs is correlated with a value of the oscillating wave at that time, yielding a number of time-value pairs. The topology of the surface of the optical medium is approximated from these time-value pairs.

Abstract: A signal gain control method and system for use in optical disc drives to prevent undesirable saturation occurrences in circuit operations. The method includes fetching a preset reading front monitor diode signal and a preset gain controlling signal for reading; generating a front monitor diode signal by a front monitor diode signal conversion circuit; calculating a gain controlling signal based on the preset gain controlling signal for reading, the preset reading front monitor diode signal, and the front monitor diode signal by a signal processor; adjusting a gain for detection signals according to the gain controlling signal by a gain adjustment unit; and generating control signals according to the adjusted detection signals by a pre-amp module.

Abstract: A processor-readable medium comprises processor-executable instructions. The instructions are configured for scanning a reference pattern on a disc to determine a first radial position of the laser, wherein the reference pattern is located at a first nominal distance from a center of the disc and extends to a second nominal distance from the center of the disc, wherein the first and second nominal distances are accurate to within a nominal runout tolerance. The instructions are also configured for reading media ID data on the disc only when the radial position is greater than or equal to the first nominal distance plus the nominal runout tolerance and is less than or equal to the second nominal distance minus the nominal runout tolerance.

Abstract: [Problems] To provide an optical head device capable of obtaining a desirable track error signal and a lens position signal for both two types of optical media having different groove pitches. [Means for Solving the Problems] Light emitted from a light source is divided by a diffraction optical element (3a) into a main beam that is transmitted light, first sub beams that are positive and negative first order diffracted light beams, and second sub beams that are positive and negative second order diffracted light beams. The phase of the positive and negative first order diffracted light beams from regions (13a, 13c) and that of the positive and negative first order diffracted light beams from regions (13b, 13d) are shifted from each other by 180 degrees, and the phase of positive and negative second order diffracted light beams from regions (13a, 13d) and that of the positive and negative second order diffracted light beams from regions (13b, 13c) are shifted from each other by 180 degrees.

Abstract: An example hologram recording and reproducing apparatus includes a recording unit which records information on a holographic recording medium by recording interference fringes formed by irradiation of a reference light and an object light corresponding to recording information, a reproducing unit which generates detected information data and a focus error signal on the basis of detected light from the holographic recording medium, and a focus servo unit that carries out focus servo on the basis of the focus error signal. The focus servo unit has a servo target value setting unit which sets a target value for focus servo on the basis of the detected information data. The detected information data also includes information indicative of the position relationship between the recording medium and the reference light or the like.

Abstract: A device is for scribing a visible label on the medium. The medium (11), for example an optical disc, has a label side provided with a radiation sensitive layer for creating the visible label via a beam of radiation. The device has a head (22) for providing the beam and generating a detector signal in dependence of radiation reflected from the medium, and a focus unit (32) for generating a focus control signal for focusing the beam. A label control unit (33) controls the scribing in dependence of label data. The focus unit (32) detects a focus error by including a focus excitation signal in the focus control signal and detecting a deviation in the detector signal in dependence of the focus excitation signal. The label control unit (33) is for controlling the focus unit in dependence on the label data to detect the focus error during said scribing and without interrupting said scribing.

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

Abstract: The method prevents an optical disk from being scraped by an optical apparatus of a pickup head of an optical disc drive is disclosed, it mainly includes: moving the optical apparatus of the pickup head to a detection position in which the laser-light emitted from the pickup head focuses on the optical disk; detecting the first-detection position and setting a movement boundary according to the first-detection position, wherein the movement boundary has a upper boundary and a bottom boundary; preventing the optical apparatus from moving out of the movement boundary. The present method can be implemented without installing any additional apparatus in the original video disc player, and can prevent the optical disk and the inner apparatus of the optical disc drive from being scraped or damaged by the pickup head during a read/write process to increase the service life of the optical disk and the optical disc drive.

Abstract: When a laser light focal point, driven by an objective lens, passes through each of a plurality of recording layers of an optical disc, data recorded on the recording layers through which the focal point passes may be deteriorated due to a difference in optical sensitivity for each recording layer or the like. In a focal point position movement in which switching of recording layers is made by a focus error signal, when the focal point position moves from a recording layer on which a laser light is focused to another recording layer which is not adjacent, light intensity or light density at the focal point is reduced in accordance with the recording layer to be passed through, thus deterioration of the data on the optical disc being prevented.

Abstract: The displacement of a pick-up head along the radial direction of an optical disk is detected, and the absolute position of the pick-up head is determined by the accumulation of the displacement, hence the apparatus knows which area on the optical disk the pick-up head currently stays. After obtaining control signals for a motor to drive the pick-up head to move along the radial direction, the apparatus calculates the displacement of the pick-up head during every stroke according the control signals. Afterward, the absolute position is determined by the accumulation of the displacement during all strokes.

Abstract: A controlling unit 130 of an optical disc recording apparatus judges a failure of a focus servo in accordance with an output signal of a servo circuit 107. When a failure of the focus servo is detected, a laser light irradiating position at the time of the failure is obtained as a standard position and a laser power controlling unit 140 is controlled to pause a control of the laser power based on data to be recorded. Thereafter, the laser power controlling unit 140 and a position of an optical pickup 103 are controlled to restart the control of the laser power based on the data to be recorded from the standard position as a starting position.

Abstract: A method for adjusting a focus bias in an optical disc drive comprises the steps of: rotationally driving an optical disc in a state that only focus servo is engaged without engaging tracking servo; driving an actuator of an optical pick-up so that a laser beam projected from the optical pick-up is moved in a tracking direction to obtain an HF signal; and determining a focus bias by which a proper focusing point can be obtained based on the HF signal. The driving of the actuator is carried out by supplying an actuator drive control signal to a tracking actuator of the optical pick-up in a state that tracking servo is not engaged.

Abstract: A visible light characteristic changing layer formed from photosensitive or heat-sensitive material is formed in a location which can be viewed from a part of a label surface of an optical disk. The optical disk is set on a turntable of an optical disk unit while the label surface of the optical disk is directed downward. The optical disk and an optical pickup are moved mutually along the plane of the optical disk. In synchronism with the relative movement, the power of a laser beam output from the optical pickup is modulated in accordance with image data, such as characters or graphic images to be printed, and the laser beam is emitted onto the visible light characteristic changing layer. As a result of the visible light characteristic changing layer being exposed to the laser beam, a visible-light reflectivity of the visible light characteristic changing layer is changed, thereby forming a image corresponding to the image data on the label surface.

Abstract: A method of reproducing an optical disk that that shortens the time between optical disk insertion and implementation of a standby mode enabling reproduction is provided that comprises a step of reading parameters stored in a nonvolatile memory, a step of deciding whether the optical disk can be properly reproduced using the read parameters, a step of, when it is found that the optical disk cannot be properly reproduced using the parameters, conducting a focusing search, reflection level detection, tracking error signal amplitude measurement and the like with respect to the optical disk, a step of specifying new parameters based on the result, and a step of storing the new parameters in the volatile memory.

Abstract: An optical apparatus includes: a light source outputting light; a head disposed so as to face a disk on which a signal is recordable, the head being capable of condensing a light from the light source onto the disk as near-field light; an distance adjusting mechanism adjusting a distance between the head and the disk; first control means for causing the head to approach the disk and controlling the head to nearly stop at a position where a distance from the disk is a first distance at which the light is condensed on the disk by the head as the near-field light; detection means for detecting if the distance is the first distance; and second control means for controlling the distance adjusting mechanism based on the detected signal so as that the distance is a second distance under near-field light condition.