Abstract: Disclosed are various systems, methods, and programs embodied in a computer readable medium for calibration of a lens position in an optical disc drive. In one embodiment, a method is provided that comprises manipulating a lens focus actuator to relocate the lens from a first position to a second position. The lens substantially focuses a laser onto the surface of the optical disc when in the second position. The method also comprises determining a first input setting delta to the lens focus actuator that corresponds to a predefined position offset of the lens. The first input setting delta is determined based upon a second input setting delta corresponding to a distance between the first position and the second position.

Abstract: An apparatus comprising a focus controller, a photo-diode sensor, a data circuit, a focus error creation circuit and a focus offset circuit. The focus controller may be configured to control a lens in relation to a laser beam and allow the laser beam to focus on a disc. The photo-diode sensor may be configured to generate one or more photo-diode signals in response to the laser beam. The data circuit may be configured to generate one or more disc status signals in response to the one or more photo-diode signals. The focus error creation circuit may generate a focus error signal. The focus error signal may provide a first value based on a focus point of the laser beam. The focus offset circuit may be configured to offset the first value of the focus error signal to a second value in response to the disc status signals to allow the focus controller to move the lens to a position which will increase the focus point of the laser beam on the disc.

Abstract: A control circuit creates a self-sensing active-damping voice coil. The control circuit includes a current sensor coupled to a voice coil. A first filter is coupled to the current sensor to create an error voltage that is proportional to the integral of an external acceleration applied to the voice coil. A second filter with a lead-lag component is coupled to the error voltage to create a voltage applied to the voice coil that substantially cancels the external acceleration below a pole defined by a lead-lag component thereby damping the external accelerations.

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: An optical reading/writing apparatus has an optical head that includes a collimator and a lens. For efficient and reliable focusing control for writing an empty optical disk, calibration of focus offset and spherical aberration is executed by setting a boundary and performing data-reading in an OPC area only with combinations of focus offset and spherical aberration within the boundary. Accordingly, an optimum combination of focus offset and spherical aberration is determined for focusing compensation in subsequent writing operation of the empty disk.

Abstract: A method for obtaining an optimum focusing point of an optical pickup unit and a servo system of an optical disk drive using this method is disclosed. An optical pickup drive circuit controls a position of an optical pickup unit according to an optical pickup control signal. A compensator receives an input signal and thus generates the optical pickup control signal. By varying levels of the input signal may enable the optical pickup unit to move to different positions. The optical pickup control signal enables the optical pickup unit to move to an optimum focusing point when the input signal activates the optical pickup unit to achieve the situation that an average difference between a peak envelop and a bottom envelop of the optical pickup control signal is minimized, or that an amplitude and a level of the tracking error signal are maximized in accompanied with minimum distortion range.

Abstract: An apparatus comprising a center error creation circuit and a center error offset injection circuit. The center error creation circuit may be configured to generate a center error signal in response to light from a main laser reflected from a surface of an optical disc. The center error offset injection circuit may be configured to (i) determine a value of the center error signal when a lens in a sled housing is at a mechanical center and (ii) generate an offset signal based upon the value. The center error offset injection circuit generally measures an average value of the center error signal over a predetermined amount of time when a lens suspension which holds the lens in place is in a mechanical equilibrium state.

Abstract: An optical disc apparatus has: an optical head 400 for emitting a light beam onto a predetermined track of an optical disc 300 before tracking control in order to detect reflected light with a photodetector; an arithmetic circuit 130 for generating measurement signals each indicative of a time-varying change of light received on a respective one of a plurality of light receiving areas of the photodetector; an A/D converter circuit 140 for A/D converting each measurement signal; a microcomputer 190 for determining a correction value based on a difference, in terms of high- and low-frequency components, between measurement signals having been A/D converted; and an adder circuit 180 for adding the correction value to a driving value output from a tracking control circuit 170, so that the driving value is corrected.

Abstract: An optical disc drive uses a tracking error signal derived from the wobble-induced signal components of the optical detector signal. This tracking error signal is relatively insensitive to beamlanding errors, and to differences in the signal amplitudes of the output signal of individual detector segments. Further, the need for a 3-spot grating is eliminated. A distinction is made between a situation where the track being followed is empty, and a situation where the track being followed is written. In case the track being followed is empty, a tracking error signal is derived from the wobble-induced signal components of the optical detector signal, whereas, in case the track being followed is written, a tracking error signal is derived from the data-induced signal components of the optical detector signal.

Abstract: A method for determining a track searching direction is disclosed. The method takes advantage of the characteristic that the movement of the photo-diode with respect to the optical disk is not perpendicular to the track direction. Therefore, the phase difference between the front side and the rear side of the photo-diode could be used to define a seeking error signal. The seeking error signal is used, together with a tracking error (TE) signal and a radio frequency ripple (RFRP) signal, to determine the track searching direction. Because the seeking error signal has a better signal-to-noise ratio, the phase lead or lag can be determined more accurately. As a result, the accuracy of detecting the track searching direction on a blank disk is improved.

Abstract: Provided are a focus search apparatus and method for performing a focus search after moving an optical pickup to a focus-on point according to a signal output from a sine wave generator so that a stable and smooth focus search is performed. In the focus search method, a sine wave is generated in response to a focus search command. The focus search is performed using an optical pickup in response to the sine wave. The optical pickup is driven in response to an amplitude of the sine wave during the focus search and in response to a filtered focus error signal during a focus servo.

Abstract: A method for setting a layer-jump point on a multilayer optical disc in an optical drive for accessing the multilayer optical disc. First, a magnetic-pole cycle value is accumulated. Next, a lag control signal of the optical drive is detected to record the magnetic-pole cycle value as a magnetic-pole basic value. Then, a magnetic-pole offset value is generated according to a phase difference between the lag control signal and an oscillating position of the multilayer optical disc. Finally, a layer-jump-point reference value, according to which the optical drive moves from one layer of the multilayer optical disc to another layer thereof to access data, is set by adding the magnetic-pole basic value to the magnetic-pole offset value.

Abstract: An optical disc apparatus, as a learning operation before a recording or reproducing operation, rotates an optical disc at a first speed to read PID information, discriminates between lands and grooves of the optical disc, detects switching positions between lands and grooves, sets a rotation angle position of tracking pull-in of an objective lens of a time length that allows the PID information to be stably read, with respect to the switching position, and stores the set position information of tracking pull-in as learning result information. During recording or reproducing, the optical disc apparatus rotates the optical disk at a second speed higher than the first speed, pulls in the objective lens for tracking based on the stored position information of tracking pull-in, reads PID information, and performs the recording or reproducing operation while discriminating between lands and grooves and detecting switching positions between lands and grooves.

Abstract: An apparatus having switchable servo gains and offsets for an optical disk drive adjusts its gains and offsets through the coupling of a servo signal and a switch with several changeable paths. The servo signals are either designated to undergo signal reduction with respect to a first offset, through the switch and then be output after a first gain unit performed proportional conversion, or designated to undergo signal reduction with respect to a second offset and then be output after a second gain unit performed proportional conversion. The switch is switched on/off in the light of the working status of the pick-up head, for example, seeking or tracking, at a data area or at a blank, area, and at. a groove area or at a land area, so as to choose different offsets and gains to have the conversion of the servo signals.

Abstract: In a layer jump and focusing control method, a first focusing error signal is generated according to the differential astigmatism method in a closed-loop focusing control manner when focusing on the first recording layer. A second focusing error signal is generated according to the astigmatic method in an open-loop focusing control manner when a first layer-jumping procedure is performed to shift a focusing position from the first recording layer to the second recording layer. Then, the completion of the first layer-jumping procedure is determined according to the second focusing error signal, for example when the second focusing error signal passes the zero crossing point and exceeds a threshold level. Afterwards, a third focusing error signal is generated according to the differential astigmatism method in a closed-loop focusing control manner when focusing on the second recording layer.

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: The present invention relates to a method for correcting the operating point of a focus control loop for a scanner for optical storage media. According to the invention, the method comprises the steps of: extracting from a focus error signal (FE) a signal component caused by vertical wobble of the optical storage medium; integrating the extracted signal component; and correcting the operating point with the aid of the integrated signal.

Abstract: An optical recording/reproducing apparatus includes a disc, a pickup to irradiate a laser beam to the disc and detect a reflected light of the irradiated laser beam, a controller to generate a tracking error signal from a signal of the reflected light and generate a control driving signal for track following by using the tracking error signal, a driving unit to perform tracking servo control by driving an actuator of the pickup according to the control driving signal, and an output unit to output an accelerating and decelerating control driving signal transmitted to the driving unit during the tracking servo control as a pulse width modulation (PWM) signal.

Abstract: An off-format condition in a digital tracking servo is presented. An off-format condition can be detected by low pass filtering a tracking control signal, detecting a DC level over a threshold level, and indicating the off-format condition if the DC level is above the threshold level for a maximum number of cycles.

Abstract: An optical disk drive includes a pickup head, a servo circuit, and a controller. An optical disk has a first area and a second area for which different tracking methods are to be used. The controller may cause the pickup head to make a seek for a target address in the first area from a position in this area that is farther from the boundary between the two areas than the address. If the controller cannot perform tracking servo control after the seek is made, and if the calculated address is located in a critical region, the controller immediately causes the pickup head to make a seek by a specified number of addresses toward the position farther from the boundary. After the seek is made, the controller performs tracking servo control again.

Abstract: An apparatus for and a method of compensating for a defect of an optical disc. The method includes: detecting a disc defect zone according to an RF sum signal level read from the optical disc; inverting a phase of a tracking error signal generated during a first specified time from the start of the defect zone; and holding a tracking servo control by adding components of the inverted tracking error signal to a tracking drive signal for a second specified time.

Abstract: The purpose is to provide an optical disc apparatus which can accurately calculate a gain for focus control. An optical apparatus (100) includes: an FE generator (20) for generating an FE signal; an AS generator for generating an AS signal (21); a normalization operator (22); an Fc filter (23); a selector (24); a spherical aberration setting device (34); an FE amplitude measuring device (30); an Fc pull-in instructor (52); an after-pull-in AS measuring device (40); and a gain operator (32). The optical apparatus obtains an amplitude of the FE signal before the focus is pulled in, and obtains a level of the AS signal after the focus is pulled in to adjust a focus gain.

Abstract: An optical pickup 4 that converts the reflected light from a laser light irradiated onto a disc into an electrical signal, is provided with an objective lens 42 that performs the irradiation of the laser light and reception of the reflected light and a biaxial actuator 43 that drives the objective lens 42. There are provided a focusing error signal detection unit 52 that detects the drive signal of the actuator using the electrical signal from the optical pickup 4, an actuator drive unit 56 that controls drive of the biaxial actuator 43 such that the objective lens 42 performs a focus pull-in action, using the drive signal, a focus gain setting section that sets the focus gain of the drive signal and a focus gain adjustment unit 54 that clips a drive signal waveform.

Abstract: According to one embodiment, an optical disk apparatus comprises an optical pickup which irradiates an optical disk with a light beam and receives reflected light from the disk, and a driving module which drives the pickup. The driving module includes an error detector which detects a tracking servo error with respect to a recording track on the disk from an output signal of the pickup and a tracking control module which performs tracking control over the pickup based on a servo error signal from the error detector. The control module is configured to temporarily set a tracking servo to an OFF state upon switching from a reproduction state to a recording state, measure an offset of the servo error signal, perform offset correction for the offset with respect to the servo error signal, and restore the tracking servo to an ON state after the offset correction.

Abstract: An apparatus comprising a center error creation circuit, a center error offset injection circuit and a center error controller. The center error creation circuit may be configured to generate a center error signal in response to one or more photo-diode signals. The center error offset injection circuit may be configured to (i) offset the center error signal and (ii) generate an offset signal. The lens controller may be configured to adjust a lens in a sled housing at a mechanical center is response to the offset signal when the apparatus is in a rough seek mode.

Abstract: An apparatus comprising a center error creation circuit, a center error controller, and a center error repeatable run out circuit. The center error creation circuit may be configured to generate a center error signal in response to photo-diode signals. The center error controller may be configured to adjust a lens to a center position in a sled housing with a step motor in response to a center error measure signal. The center error repeatable run out circuit may be configured to generate a center error run out signal and the center error measure signal in response to the center error signal. The center error repeatable run out circuit may generate the center error measure signal by measuring the center error signal when the center error run out signal is in a peak phase.

Abstract: A method, medium, and device changing a play mode if an error occurs in a process of discriminating the type of optical discs. The method includes the operation of discriminating a type of an optical disc loaded in an optical player, and if the optical disc is discriminated as one of a plurality of optical discs that belong to a first type, setting the play mode of the optical player to a play mode corresponding to the type of the discriminated optical disc, reading and playing data recorded in the loaded optical disc, and if the optical player is unable to reproduce the data recorded in the optical disc, then changing the play mode of the optical player to a play mode for reproducing one of a plurality of optical discs that belong to a second type.

Abstract: A system and method for controlling the position of an optical head of a disc during high speed recording. In one embodiment of the method, an optical disc has a plurality of tracks. The method comprises implementing CLV recording by said optical drive, determining a wobble signal based on address information contained in said plurality of tracks of said optical disk and determining a wobble clock signal based on said wobble signal. The method further comprises decoding said wobble clock signal by a decoder, said decoder to provide a sync clock signal to an encoder loop circuit, said sync clock signal based on said wobble clock signal generating an encoder clock signal using said encoder loop circuit. In addition, the method comprises comparing said sync clock signal to said encoder clock signal to provide a position command to position the optical head of said optical drive.

Abstract: An optical information apparatus of the present invention includes: an optical pick-up head including: a light source; a diffraction unit; a condensing unit; a beam splitter; a photodetector; and a tracking error signal generator. An optical recording medium has tracks arranged substantially at a constant pitch. An average of a pitch is tp. When a main beam is placed on the track, a first sub-beam and a second sub-beam are placed between the tracks.

Abstract: A method for calibrating a center error signal in an optical disc system, comprising the steps of (i) measuring a peak-to-peak value of the center error signal, (ii) computing a nominal peak-to-peak value of the center error signal after locking to a particular track of an optical disc, (iii) computing the nominal peak-to-peak value of the center error signal for a run-out condition, and (iv) defining a calibration gain for the current value for the center error signal.

Abstract: An offset calibration system of a control loop at least comprises an optical-to-electrical converter and an electrical-to-optical converter. The optical-to-electrical converter generates a pre-output signal and then transmits the pre-output signal to the electrical-to-optical converter to amplify. The offset calibration system comprises a comparator, an offset calibration module, and a determination circuit. The comparator compares the pre-output signal with a predetermined pre-reference signal to generate a pre-compared signal. The offset calibration module stores a predetermined and adjustable offset calibration value for adding to the pre-output signal.

Abstract: There is provided an optical disc apparatus that includes a sound pickup portion, an optical pickup to record a sound picked up by the sound pickup portion as audio data onto an optical disc using laser light, a focus adjustment portion to adjust a focal position of the laser light based on the focus drive signal, a tracking control portion to control tracking so that the optical pickup traces a track formed on the optical disc, and a gain setting portion to change the gain of the focus drive signal during a first period when adjustment of the focal position of the laser light by the focus adjustment portion is performed and control by the tracking control portion is not performed according to a level of an operation sound of the focus adjustment portion.

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: An optical disk apparatus decides reading time parameters to be set in a tracking error signal generation part at the reading time by applying a laser light of record power to an optical disk. A state where the laser light of record power is applied to the optical disk is artificially produced based on the reading time parameters decided herein. In the state, the recording time parameters to be set in the tracking error signal generation part at the recording time are decided.

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: An apparatus comprising a photo diode array, a differential push-pull generator circuit and an attenuation prediction circuit. The photo diode array may be configured to generate a plurality of beam signals. The differential push-pull generator circuit may be configured to generate a differential push-pull signal with one or more gain blocks in response to (i) a plurality of input signals, (ii) a gain approximation signal and (iii) the plurality of beam signals. The attenuation prediction circuit may be configured to (i) predict an attenuation factor of the differential push-pull signal and (ii) generate the gain approximation signal in response to (a) a plurality of amplification signals and (b) a plurality of angle signals.

Abstract: An information reproduction method according to an aspect of this invention is directed to an information reproduction method which reproduces information from an information storage medium on which land and groove tracks which can record information are alternately formed in the radial direction along wobbles that represent address information, comprising determining a track structure of a current position traced by a light beam on the basis of the address information, and a track structure of a target position on the basis of a target position address, controlling access to the address of the target position by switching between a first servo polarity corresponding to a land track and a second servo polarity corresponding to a groove track at a predetermined timing as needed on the basis of the determination result of the two track structures, and reproducing predetermined information from the target position address.

Abstract: The present invention aims to obtain a position control device which, even if the range within which a mechanical part can be pulled in for position control is narrow, enables quickly stabilizing the pull-in operation.

Abstract: An optical disk apparatus is provided with an actuator that moves a beam spot that is formed by an optical head on an optical disk to recording surfaces; position control portions that control a position of the beam spot based on the output signal of the optical head; a disturbance estimation observer relating to the actuator; and a summing circuit that takes a sum of the output of the position control portion and the output of the observer, so as to drive the actuator based on the output of the summing circuit. The optical disk apparatus further is provided with a system controller that turns the observer on and off, a LPF that attenuates the high-frequency components of the output of the observer and retains the final value of the observer when the observer is turned off, and a switching circuit that switches between the output of the observer and the output of the LPF according to whether the observer is on or off.

Abstract: An optical disc apparatus, which executes tracking control for an objective lens by generating a push-pull signal, includes a determination unit which detects symmetry of the push-pull signal and determines whether balance of signal characteristics of the push-pull signal is good, a lens shift amount detection unit which detects, in a case where the determination unit determines that the balance of the signal characteristics of the push-pull signal is not good, a lens shift amount of the objective lens in such a manner as to improve the balance of the signal characteristics, a memory unit which stores the lens shift amount that is detected by the lens shift amount detection unit, and an addition unit which constantly applies the lens shift amount, which is stored in the memory unit, to a tracking actuator which shifts the objective lens.

Abstract: An optical disc device comprises a spherical or coma aberration correction unit to pre-correct spherical or coma aberration occurring in the light beam, a focus or tracking detection unit operable to detect a focus or tracking error signal, and an FE or TE amplitude adjustment unit operable to adjust the signal amplitude of the focus or tracking detection unit to a specific value after the amount of spherical or coma aberration has been matched to a specific value by the spherical or coma aberration correction unit.

Abstract: An optical pickup is provided for preventing an objective lens from colliding with an optical recording medium at the stage of initial adjustments. The optical pickup device comprises a servo circuit, and a lens driver for driving an objective lens. In the servo circuit, a drive signal generator supplies the lens driver with one of a first focus drive signal for moving the objective lens in a direction closer to an information recording layer, and a second focus drive signal for moving the objective lens in a direction away from the information recording layer. A controller in a timing generator switches a signal supplied to the lens driver from the first focus drive signal to the second focus drive signal when the level changes by a predetermined range or more in a servo signal which is generated during a period in which the first focus drive signal is being supplied to the lens driver.

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

Abstract: A method and apparatus position a beam spot on a recording medium. The positioning includes (a) observing a first center error in a first closed loop control during tracking mode, the first center error including a repeatable run out (RRO) error, (b) estimating a center error (CE)-RRO from the first center error, the CE-RRO being part of the first center error caused by the RRO, (c) observing a second center error in a second closed loop control during a rough seek, (d) subtracting the CE-RRO from the second center error, (e) controlling the beam spot based on the second center error less the CE-RRO during the rough seek, and (f) adding an open loop control to the second closed loop control during the rough seek, the added open loop control inducing a motion of the lens relative to an optical center of the OPU during the rough seek.

Abstract: A lens position signal LCE which indicates the discrepancy between the lens and its geometric mid-position is required for coarse tracking of optical storage drives. The prior art is for the lens position signal LCE to be formed in three-beam pick-ups by weighted combination of specific photodetector signals from a primary beam and secondary beam. The only way to ensure that the lens position signal is free of crosstalk caused by the tracking error signal is for the weights to be set correctly. The invention describes methods by means of which the weights can be adjusted automatically and can be matched to the characteristics of the pick-up and of the respective storage medium. The amplitudes of those components in the main and secondary beam signals which are dependent on the tracking error are measured, and the matched weights are determined from them by joint evaluation. Evaluations with synchronous detection and with time integration are described, some of which can be used during writing and reading.

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

Abstract: A device for reading from and/or writing on a rotating disk including a mobile opto-electromechanical device placed above the disk and connected to a motherboard via a set of electric wires. The opto-electromechanical device includes actuators, a laser diode, photodetectors, and an electronic circuit, each photodetector providing the electronic circuit with an analog electric signal proportional to the received light signal, the electronic circuit controlling the diode and the actuators. The electronic circuit comprises an analog-to-digital converter digitizing the analog electric signals coming from the photodetectors and transmitting the digitized signals to a digital processing unit providing data of alignment of the opto-electromechanical device with respect to the disk, and a reference clock signal having its period substantially corresponding to a multiple or to a sub-multiple of the time period corresponding to the overflight by the opto-electromechanical device of a bit of the disk.

Abstract: The present invention provides an optical disk control device that can perform focus pulling in a short time for a target information surface of an optical disk having a plurality of information surfaces. An objective lens (23) is moved toward an optical disk (1) having a plurality of information surfaces (1A, 1B) by the output signal of a driving signal generating circuit (42B), passage of an initial focused focal position is detected by a focal point passage detecting circuit (44), and when the objective lens moves past that position only a predetermined amount closer to the optical disk, an n-rotation delay circuit (70) outputs a reversal instruction f. After changing directions and moving the objective lens away from the optical disk, a focus pulling-in circuit (32B) switches a signal “a” that is output to an actuator driving circuit (21) from the output signal of the driving signal generating circuit to the output signal of the control circuit, activates a control circuit and performs focus pulling-in.

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: An optical information apparatus of the present invention includes: an optical pick-up head including: a light source; a diffraction unit; a condensing unit; a beam splitter; a photodetector; and a tracking error signal generator. An optical recording medium has tracks arranged substantially at a constant pitch. An average of a pitch is tp. When a main beam is placed on the track, a first sub-beam and a second sub-beam are placed between the tracks.