Abstract: Even in an optical disk which includes, within a single disk, plural record areas whose track-pitches differ from each other, a tracking parameter is adjusted in a short time and with a high accuracy. At first, an optical pickup for reading information recorded in the optical disk is displaced into a reference track-pitch area which is one of the plural record areas of the optical disk. Moreover, the tracking gain is adjusted so that the tracking servo gain in this area may exhibit a predetermined characteristic. Also, the value thus acquired is recorded into, e.g., a non-volatile memory. After that, based on the tracking parameter learned/adjusted in the reference track-pitch area, the tracking parameter in another track-pitch area is calculated using the track-pitch ratio therebetween. Thereby it becomes possible to adjust the tracking parameter in a short time and with a high accuracy.

Abstract: An off-track state is to be detected accurately. A photodetector 11 converts the light reflected from an optical disc into an electrical signal. A MIRR signal generating circuit 16 generates a bi-level MIRR signal 23, indicating whether the photodetector 11 is in an on-track state or an off-track state with respect to a track of the optical disc, based on an output signal of the photodetector 11. A TEC signal generating circuit 17 generates a bi-level TEC signal 24, indicating whether the photodetector 11 is on an inner side or on an outer side in the radial direction of the optical disc with respect to the track in the optical disc currently closest to the photodetector, based on the output signal of the photodetector 11. An off-track detector 18 outputs an off-track signal 25 if, after the level of the MIRR signal 23 is changed from an on-track state to an off-track state, the level of the TEC signal 24 is changed without the level of the MIRR signal 23 being changed.

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: The present invention realizes stable focus entry control even in the case where a wideband focus error signal is used with which the focus error signal sensitivity and the level in the vicinity of a focus point vary depending on a light path length. A second focus error signal having a wide range is used, causing an objective lens to approach a disk while maintaining a predetermined rate of change with respect to time, and, during approach, a transition to focus servo is performed by detecting the focus position according to the first focus error signal.

Abstract: A method and an optical disk apparatus that can accurately and stably correct the spherical aberration even for a blank write-once optical disk and can detect a spherical aberration error signal with a simple construction of parts in real time. In a blank write-once disk 20, the tracking servo is switched to an inoperative state, push-pull signals from outputs of the photodetector 12 are detected in a state of “in focus” and in a state of “out focus,” respectively, by a push-pull signal generation circuit 34, and.the amplitudes of these push-pull signals are subjected to difference calculation in a spherical aberration error detector 31 to obtain a spherical aberration error signal A.

Abstract: A tracking controller includes a tracking error detecting section and a tracking control section. The tracking error detecting section generates and outputs a tracking error signal that represents how much the focal point of a light beam has shifted from a target track on a storage medium. The tracking control section generates a drive signal in response to the tracking error signal so as to move the light beam such that the focal point of the light beam is located right on the target track. The gain of at least one of the tracking error signal and the drive signal is switched depending on whether or not the focal point of the light beam is located on a recorded area of the storage medium on which data has already been written.

Abstract: An optical information recording/reproduction apparatus capable of performing accurate tracking control without depending on a radial runout of an optical disk is provided. Specifically, light reflected on an optical disk is detected by a first photodetector and a tracking error signal is detected from an output thereof. Also, return light reflected on an end surface of an SIL which is opposed to the optical disk is detected by a second photodetector, and a position signal of an optical head portion in a tracking direction is detected from on an output thereof. Further, the tracking error signal is corrected based on the position signal to remove an offset, thereby performing accurate tracking control.

Abstract: An optical disk servo device capable of correcting spherical aberration occurring by thickness errors of a cover layer of an optical disk or disc while avoiding risks of influence by vibrations and shocks or else is disclosed. The device includes an optical head unit for writing or reading information to or from the optical disk, a tracking-servo unit, a lens for correction of spherical aberration, and a lens position detector for detecting a position change amount or displacement of the lens and for generating at its output a lens position detection signal, which is then subjected to negative feedback to the tracking-servo unit.

Abstract: In a CLV(constant linear velocity) or MCLV(substantially constant linear velocity)-type optical disk apparatus, instability of servo at inner and outer circumferences of an optical disk is prevented by adjusting a servo-loop gain of tracking servo control or focus servo control in accordance with the radial-direction position of an optical spot, i.e., in accordance with the rotation frequency of the optical disk.

Abstract: A method and a device for adjusting control parameters of a servo system of an optical disk drive. A first sinusoidal signal is introduced into a control loop of the servo system, while a band-pass filter is used to extract a second sinusoidal signal. Gain and/or phase variations of the control loop are derived by comparing signal parameters of both the first and second sinusoidal signals. A compensator is then employed to adjust the derived gain and/or phase variations of the control loop so as to overcome the disadvantage of system instability after a long-term working.

Abstract: The optical pickup apparatus includes a light emitting means, an optical means, and an optical detection means. The light emitting means emits a single beam. The optical means diffracts the single beam, focuses the optical spot of the diffracted beam on a track, and transmits the diffracted beam to an outside. The optical detection means includes a first optical detection unit on which a central beam having a 0-order diffraction coefficient is focused, and second and third optical detection units on which side beams having ±1 diffraction coefficients are focused, respectively. Each optical detection unit is segmented into a specific number of optical detection areas, and at least one of the optical detection units is provided with an optical detection area on which a tracking error signal used to compensate for tracking offset attributable to optical axis offset of an objective lens is not formed.

Abstract: Methods for start-up lens. The lens moves from a stowing position to a standby position along an axis, and a reset point, a first turning point, a second turning point, and a third turning point are defined in sequence during the movement. A drive unit rotates at a first angular velocity to drive the lens in a first route, rotates at a second angular velocity to drive the lens in a second route, and rotates at a third angular velocity to drive the lens in a third route.

Abstract: Comparators compare the amplitudes of a DPD tracking error signal indicating the phase difference between the detection signals supplied from a photodetector, and a PP tracking error signal indicating the level difference between the detection signals with the reference values, respectively. A gain control amplifier mutes a tracking error signal with the maximum amplitude smaller than a reference value.

Abstract: An optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises analog processing means including a binarization unit for subjecting a signal read from the optical disc to binarization and a servo unit for controlling recording and reproducing a signal in and from the optical disc; synchronous clock generating means for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; address detecting means for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the sync

Abstract: A tracking error detection apparatus comprises a photodetector comprising plural photoreceptor elements; zerocross detection circuits for detecting zerocross points at which two sequences of digital signals intersect the center levels of the respective digital signals, which digital signals are generated according to the amounts of light received by the respective photoreceptor elements and are outputted from the photodetector; a phase difference detection circuit for performing phase comparison using a distance between zerocross points of the two sequences of digital signals, and outputting a result of phase comparison; and a low-pass filter for performing band restriction to a signal outputted from the phase difference detection circuit. When a phase difference between the two sequences of digital signals, which is detected by the phase difference detection circuit, is larger than a maximum value of a theoretical tracking error signal, the output from the phase difference detection circuit is limited.

Abstract: A layer change control method and an apparatus for an optical medium in which a layer change is accurately performed even where there is a level deviation of a focus actuator error signal (FE). The layer change control method includes measuring a needed time from where a focus point of the optical medium breaks away from a current layer to where the focus point arrives at a desired layer, and controlling a focus driving voltage needed to pull the focus point of the optical medium into the desired layer, and a time to output the focus driving voltage by using the needed time. Therefore, since a layer change can always be accurately performed even where there is a deviation in a FE level, according to the physical characteristic and operational deviation of a focus actuator, a stable disc driving environment can be provided.

Abstract: An optical storage apparatus, a preamplifier and a method of generating a tracking error signal. The optical storage apparatus includes a pickup head, a preamplifier, and a servo control. The pickup head generates radio frequency (RF) signals. The preamplifier includes a signal adjusting apparatus, a phase detector, a charge pump, and a circuit. The signal adjusting apparatus has input terminals for receiving the RF signals. At least two of the input terminals are substantially short-circuited when the optical storage apparatus is in a calibration mode. The phase detector generates control signals based on the phase differences between the radio frequency signals. The circuit generates current control signal based on the tracking error signal when the optical storage apparatus is in the calibration mode. The current magnitude of at least one of the current sources in the charge pump is determined according to the current control signal.

Abstract: The present invention is provides a method and apparatus for slip protection of DVD-RAM drive's seek control, comprising a slip end velocity controller, a re-seek controller, and a slip detector. Among them, the slip end velocity controller is used for providing a first control signal to direct a driver to control the slip end velocity of the optical head while seeking. The re-seek controller is capable of providing a second control signal to the seek controller for directing the seek controller to control the driver driving the optical head for re-seeking. The slip detector is used for receiving the TE signal sent from the preamplifier to determine if the optical head is slipping and to switch the input signal of the driver.

Abstract: There is provided an optical disk drive capable of appropriately effecting recording and reproducing operations without being affected by offset values and a laser output value, which are set at startup of the disk drive, even when changes have arisen in the internal temperature of the disk drive because of changes in ambient temperature. In an optical disk drive, a temperature sensor provided on a pickup measures a temperature. When changes in temperature are greater than a predetermined level, a focus offset value, a tracking offset value, and a value of laser output from the pickup are reset.

Abstract: A positioning control device and method in which the relative position error in tracking is reduced by using the periodicity of position shift. The positioning control device comprises a position detecting unit for measuring the relative position error between the desired position of an objective member and a moving member, an adding unit for adding a position error signal output from the position detecting unit and a delay signal, a signal delay unit for outputting the delay signal which is obtained by delaying an output of the adding unit at a period corresponding to the position shift of the objective member, a drive unit for moving a moving member, and an inputting unit for inputting the signal of the sum of the position error signal and the delay signal to the drive unit and addition-inputting the delay signal to the drive unit through a filter having a predetermined frequency characteristic in a specific frequency range.

Abstract: An optical disk device includes a pickup head, and a controller which controls the pickup head. The controller subtracting a second measured value determined from an amplitude value of the tracking error signal when the pickup head irradiates a second area of the optical disk with a first DVD laser beam, from a first measured value determined from the amplitude value of the tracking error signal output when the pickup irradiates a first area of the optical disk with the first DVD laser beam, to determine an evaluation value. The controller determining that the optical disk is the first DVD if the evaluation value is smaller than a reference value, and determining that the installed optical disk is a second DVD if the evaluation value is larger than the reference value, the second DVD optical disk having a smaller track width than the first DVD optical disk.

Abstract: An optical disc apparatus includes an optical pickup which irradiates a first laser beam for reproducing a first DVD medium, or a second laser beam for reproducing a second DVD medium onto a installed optical disc, and receives the reflected light from the installed optical disc, a controller determines that the installed optical disc is the second DVD medium when a value by normalizing the amplitude of a RF signal generated from the reflected light with a coefficient is larger than first threshold value and smaller than a second threshold value, and the controller determines that the installed optical disc is the first DVD medium when the value is not larger than first threshold value and smaller than a second threshold value.

Abstract: An offset adjusting circuit for an optical disc comprises a plurality of offset-adjustment differential operational amplifiers, each of the amplifiers having an input terminal to which an output signal of an optical pickup is input and another input terminal to which a control voltage is applied, an adding circuit that adds output signals of the offset-adjustment differential operational amplifiers, an A/D converter that outputs a digital signal based on an output signal of the adding circuit, and a control voltage adjuster that varies the control voltage applied to the offset-adjustment differential operational amplifiers based on the digital signal so as to remove an offset.

Abstract: A tracking error detection device for an optical disk apparatus comprises a detecting unit which includes at least two detectors and detects a reflected light from a series of pits formed on an optical disk, a phase comparing unit which detects a phase difference of outputs of the at least two detectors, and a low-pass filter which smoothes an output of the phase comparing unit, a cut-off frequency of the low-pass filter being higher than a frequency at which a spectrum of a modulation code recorded in the optical disk becomes ?10 dB and lower than a frequency at which the spectrum of the modulation code recorded in the optical disk becomes ?5 dB.

Abstract: The present invention comprises a tracking actuator which drives an objective of a pickup emitting the laser beam, in accordance with a drive signal, a detector which detects or estimates a temperature variation putting an influence on a sensitivity of the tracking actuator, and a corrector which corrects the drive signal in accordance with information detected or estimated by a state detector.

Abstract: The present invention provides an optical recording apparatus having an information recording unit configured to record information in recording guide grooves formed on a surface of an optical recording medium by irradiating the optical recording medium while scanning the recording guide grooves with a light beam to change optical properties of the optical recording medium, a determining unit configured to determine a signal amplitude in the recording guide grooves to determine whether or not the determined signal amplitude is more than a specified amplitude value which has been preliminarily stored in the optical recording apparatus, and a recording condition changing unit configured to change recording conditions of the information recording unit when the determined signal amplitude is determined as being more than the specified amplitude value.

Abstract: In a configuration in which side beams scan in positions that are offset with respect to a main beam by approximately (¼+n)P or (¾+n)P in the radial direction of an optical disk, a differential signal is generated from push-pull signals of the return lights of the side beams to generate a track-cross signal. In a configuration in which side beams scan in positions that are offset with respect to a main beam by approximately (¼+n)P or (¾+n)P in the radial direction of an optical disk, far-side or near-side light detection results of the return lights of the side beams are processed and computed with respect to a push-pull signal of the return light of the main beam.

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: A method of adjusting channel properties of an optical storage system is disclosed to include the steps: Step 1) give a modify step, a trial step and a threshold, Step 2) give an initial point, Step 3) add an initial focus point to the trial step and measure the sum so as to obtain a first jitter value, Step 4) deduct the trial step from the initial focus point and measure the difference so as to obtain a second jitter value, Step 5) deduct the second jitter value from the first jitter value and judge if the difference is greater than the threshold or not, Step 6) deduct the modify step from the initial focus point and then return to step 3) when the difference obtained from step 5) is greater than the threshold, Step 7) deduct the first jitter value from the second jitter value and judge if the difference is greater than the threshold or not in case the difference obtained from step 5) is smaller than the threshold, Step 8) add the initial focus point to the modify step and then return to step 3) when the di

Abstract: A controller of an optical disk apparatus moves a pickup head to a data area of an optical disk, and radiates a first DVD laser beam to the optical disk. The controller measures, as a first eccentricity amount, a number of beams, which have crossed a track on the optical disk, from a first tracking error signal from a head amplifier. The controller determines that the optical disk is a data-recorded first DVD optical if the controller determines that the measured first eccentricity amount is less than a predetermined reference value. The controller determines that the optical disk is a second DVD optical disk or the first DVD optical disk with a large eccentricity amount if the controller determines that the measured first eccentricity amount is greater than the predetermined reference value.

Abstract: An optical disk apparatus includes: a servo control unit, operable to execute a servo control of focusing based on a focus error signal and to execute a servo control of tracking based on a tracking error signal; a detrack regulating unit, operable to execute a detrack regulation for setting an offset voltage, which is to be added to the tracking error signal, to be a voltage for giving the highest signal quality of an output of an optical pickup; and a defocus regulating unit, operable to execute a defocus regulation for setting an offset voltage, which is to be added to the focus error signal, to be a voltage for giving the highest signal quality of the output of the optical pickup. The defocus regulation is executed in a state in which the servo control of the focusing and the servo control of the tracking are executed. The defocus regulation is executed after the detrack regulation is executed, in the state in which the servo control of the focusing and the servo control of the tracking are executed.

Abstract: An optical element feeding device driving method and an optical disk apparatus capable of detecting biting in a stepping motor and conducting restoration. The optical disk apparatus includes an optical element feeding device including a movable frame for supporting a spherical aberration correcting lens to move the lens in optical axis direction, a spring for applying force to the frame in the direction, a sensor for detecting a lens reference position, a stepping motor, and a lead screw and a nut for converting motor rotation into the direction, a motor driving circuit, a decision circuit for judging abnormality when an output of the sensor does not change even if the driving circuit outputs a driving signal to the motor after reference position detection, and a changeover circuit for lowering a driving frequency than in ordinary operation, based on an abnormality signal.

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: An optical disc apparatus includes a spherical aberration correction element for correcting spherical aberration and a preadjustment unit for obtaining setting of a spherical aberration correction element for correcting spherical aberration appropriately in a case where a focus position of a light beam emitted from a light source is adjusted on each of recording layers of an optical recording medium every time when the optical recording medium is loaded to the apparatus.

Abstract: In order to generate a lens position signal, which describes the position of the optical axis of an objective lens of an apparatus for reading from and/or writing to an optical recording medium with regard to the optical axis of the remaining components contained in an optical scanner, the application of the DPP method is proposed in accordance with a first exemplary embodiment, wherein a primary-beam error signal and a secondary-beam error signal are obtained with the aid of the DPP method, wherein the desired lens position signal is generated by addition of the primary-beam error signal and the secondary-beam error signal. In accordance with a second exemplary embodiment, it is not necessary to generate a primary beam, rather it suffices to detect the secondary beams reflected from the optical recording medium in order to obtain the lens position signal by addition of the secondary-beam error signals generated in a manner dependent thereon.

Abstract: Provided is an information recording/reproducing apparatus which can perform servo control with a simple circuit structure and can be manufactured at a low cost. Analog output signals from a plurality of separate portions of a photosensor which receive reflected light from an optical disk are converted into one-bit digital outputs using a plurality of ?? conversion circuits; the one-bit output signals of the plurality of ?? conversion circuits are arithmetically operated using an arithmetic circuit to generate an n-bit (n>1) servo error signal. Further, the servo error signal of the arithmetic circuit is converted into an m-bit (m>n) servo error signal by a single decimation filter.

Abstract: A label side of a light-scribe optical disc includes a control feature zone recording therein reference information of the optical disc and a label zone to be marked based on the reference information. An optical head is moved in the label zone to determine a first FE gain and a first sub-beam addition (SBAD) signal by way of focusing servo technology. The optical head is further moved in the control feature zone to determine a second SBAD Signal. The first and second SBAD signals are operated to obtain a ratio. The ratio is used with the first FE gain to estimate a second FE gain for accessing to the control feature zone.

Abstract: A controller includes a servo-controller for performing nonlinear and linear control of the read/write position according to an error signal to drive an actuator for driving the pickup; a switch for switching the servo-controller from open-mode to closed-mode according to the error signal; and an adjuster for adjusting the gains of the nonlinear and linear control so that the nonlinear control component is larger than the linear control component at the time of switching and the linear control component is larger than the nonlinear control component after the elapse of a predetermined time from the time of switching.

Abstract: A focus control process (S2), a spherical aberration correcting process (S4), and a focus offset adjusting process (S7 to S9) are performed in this order. In the focus control process, an output of a focus error signal obtained by detecting focal point displacement that occurs in a direction of an optical axis of a light beam focused through a two-element object lens is controlled so that the output becomes close to zero. In the spherical aberration correcting process, spherical aberration that occurs with respect to the light beam is corrected. In the focus offset adjusting process, offset of the focus error signal is adjusted. In this way, it is possible to provide a focal point adjusting method and an optical pickup device in which focus control can be performed stably by eliminating the offset.

Abstract: The present disclosure provides systems and methods for tracking of control and error signals in optical disk drives. Successive square waves are generated as a tracking control output signal, and a tracking error signal is generated as a function of both the tracking control output signal and an offset correction factor. Due to the characteristics of the square wave, more reliable tracking is possible by the use of the square wave.

Abstract: An optical disk unit of this invention includes a defocus detecting system for detecting a defocus of an objective lens, a thickness unevenness detecting system for detecting a thickness unevenness of a transparent resin layer provided nearest the objective lens of a recording medium, and a thickness unevenness correcting mechanism for changing the focusing characteristic of light impinging upon the objective lens based on a change in the thickness of the transparent resin layer detected by the thickness detecting system.

Abstract: An apparatus and method of estimating the quality of an input signal, and an optical disc driver including the apparatus for estimating the quality of the input signal, the signal quality estimating apparatus including a level value detection unit that detects level values of an input signal according to a binary signal of the input signal, an input signal composing unit that composes a plurality of ideal input signals by using the level values and a plurality of pre-defined binary signals, and a quality calculation unit that obtains a quality of the input signal according to a calculation between the plurality of ideal input signals.

Abstract: A method and a related apparatus for diagnosing crosstalk within an optical pick-up unit by utilizing firmware. The method includes calculating a tracking driving signal and a focusing driving signal according to a tracking error signal and a focusing error signal respectively, adding a noise to the focusing driving signal to form a test focusing driving signal through executing firmware, driving an optical pick-up unit by the tracking driving signal and the test focusing driving signal, and diagnosing characteristics of the pick-up unit through observing the tracking error signal.

Abstract: An optical pickup irradiates laser light upon a track of an optical disk and receives light reflected therefrom. A tracking actuator shifts an objective lens of this optical pickup in a tracking direction. A tracking error signal detection circuit outputs a tracking error signal based upon the reflected light received by the optical pickup. A phase compensation circuit generates a tracking drive signal based upon the tracking error signal, and outputs this tracking drive signal to the tracking actuator. A balance compensation value calculation circuit calculates a balance compensation value for the tracking error signal according to the tracking drive signal outputted by the phase compensation circuit. And a balance compensation circuit adds this balance compensation value to the tracking error signal detected by the tracking error signal detection circuit, and inputs this compensated value to the phase compensation circuit.

Abstract: A focus search driving voltage corresponding to a signal surface of an optical disc is obtained on the basis of detection information from a photodetector when an objective lens is focused on the signal surface of the optical disc in the middle of raising or lowering the objective lens placed on standby at a lens midpoint between a temporarily set lens bottom point and a temporarily set lens top point according to a temporarily set lens bottom point voltage and a temporarily set lens top point voltage.

Abstract: An unknown optical disc is identified as a CD when an all sum signal value AS-max by a photodetector on a signal surface of the unknown optical disc is larger than an all sum signal value AS-cdref for CD signal surface reference for identifying the CD and the hybrid SACD as a CD based on each CD signal surface thereof, and a focus search driving voltage Y corresponding to the signal surface of the unknown optical disc is lager than a voltage value acquired by a predetermined relational expression between a focus search driving voltage Q corresponding to a DVD signal surface of a reference DVD and a focus search driving voltage R corresponding to a CD signal surface of a reference CD.

Abstract: A track locking method and an apparatus thereof enable an optical disk drive to rapidly and stably read data recorded on a target track from a seeking mode to a track locking mode. An optical pick-up head can switch from the on-track interval of a target track to an adjoining off track period only if the tracking servo control system memorizes the last-minute level of the tracking servo output signal of the on-track interval and keeps the tracking servo output signal at the level, so as to generate a pulling force whereby the optical pick-up head is moved back to the on-track interval from the off-track interval.

Abstract: A land/groove track discriminating method and apparatus for an optical recording medium having a land/groove structure which can stably discriminate the kind of a track even in an unstable state of the system. The kind of the track is discriminated by using the differential characteristic of a tracking error signal in a header region, by using the relation that the phase of a wobbling signal in the lang track is opposite to the phase of the wobbling signal in the groove track, or by comparing phase levels of delayed first and second header region signals. Accordingly, the servo control suitable to the kind of the track can be performed at a proper time, and thus an accurate tracking control can be performed with respect to an optical disc having the land/groove track structure.

Abstract: An optical disc player executes a focus pull-in operation while avoiding an inconvenience that an objective lens comes into contact with an optical disc, or the like. The objective lens is forcedly moved gradually from a position that is away from the surface of the optical disc and outside a capture range of a focus servo toward the surface of the optical disc. When the objective lens reaches the capture range of the focusing servo loop by the moving operation and a distance between the objective lens and the disc surface is at the minimum distance or is changing in a widening direction, the moving operation of the objective lens is stopped.

Abstract: A tracking error detection apparatus comprises a phase difference detection circuit for receiving two sequences of digital signals, and performing phase comparison using a distance between zerocross points of the two sequences of digital signals to output a result of phase comparison, and an LPF for generating a tracking error signal from the result of phase comparison. The phase difference detection circuit does not carry out phase composition in a position that is not appropriate as a target position to perform phase comparison, and outputs the result of phase comparison as a pulse signal corresponding to one sampling clock. Therefore, even when a disc is played at CAV or a flaw or the like exists on the disc, an accurate tracking error signal can be detected.