Abstract: The amount of light reflected from a disk is detected, and it is determined according to the amount of reflected light whether the disk is a recordable disk or a rewritable disk. The disk is controlled according to the result of determination such that it is rotated at a constant angular velocity (CAV) or at a constant linear velocity (CLV) and recording is executed. Further, rotation driving control of the disk is selected according to factors other than the type of the disk, such as according to whether random recording is allowed or not, according to a recording state in the disk, according to whether an alternative area is provided or not, according to a recording start position, or according to whether initialization is required or not. CLV control or CAV control is appropriately selected for a disk at recording to suppress a reduction in accessibility and a reduction in data transmission rate.

Abstract: A disc driving apparatus and an information readout method according to the present invention realize optimum servo control of a readout unit in reading out the information from a recording medium having lands and grooves. The disc driving apparatus includes a unit for correcting tracking error signals, a unit for inverting signals corrected by the correcting unit to generate inverted tracking error signals, a unit for detecting which of the lands and the grooves the readout unit is scanning, and a unit for selecting the tracking error signals or the inverted tracking error signals according to the results of detection by the detection unit to tracking-control the readout unit by the selected signals.

Abstract: A track jump method for an optical recording/reproducing medium is provided. In the track jump method, once a track jump command is input, a track jump operation is held until a falling edge of a header mask signal is detected. The track jump starts at the falling edge of the header mask signal and ends before a rising edge of the header mask signal so that a TZC signal is not influenced by a header during the track jump. Therefore, the track jump can be exactly and stably performed. In particular, when the track jump command is input, a PLL of a wobble signal is inhibited, and a PLL-wobble signal is held to a previous value obtained before the track jump is performed, during the track jump, or a header mask signal is generated using a read channel signal which is not influenced by a wobble period, until a wobble signal becomes stable after a trackjump. During a normal servo, a header mask signal is generated using a PLL-wobble signal to mask a header area.

Abstract: A servo control apparatus includes: a drive section that applies a thrust to move a driven object; a storage section that stores a control circuit output initial value; an approaching control section that moves the driven object toward a target position; an error signal detection section that detects an error signal varying according to a difference between the position of the driven object and the target position; a start position calculation section that calculates a start position of a servo control process; an arrival detection section that detects whether the driven object reaches the start position; a control circuit initial value calculation section that calculates a control circuit initial value of a control system and supplies it to a control circuit of the control system; and a servo control starting section that starts the servo control process when detecting that the driven object has reached the start position.

Abstract: An apparatus of processing an input signal generated according to accessing of an optical storage medium is disclosed. The apparatus has a detecting circuit and a decision logic. The detecting circuit is coupled to the input signal for detecting a target peak value and a target bottom value of the input signal within a time period, wherein the time period is not less than a period of a reference signal generated according to accessing of the optical storage medium. The decision logic is coupled to the detecting circuit for determining a reference level according to the target peak value and the target bottom value.

Abstract: When a remaining number of tracks is smaller than a first threshold value, a coarse seek operation is determined to be normal, and therefore, a learning process is not executed. If the remaining number of tracks is not smaller than a second threshold value, the coarse seek operation is determined to be abnormal, and a voltage learning process id executed. If the remaining number of tracks is not smaller than the first threshold value and smaller than the second threshold value and prescribed conditions are satisfied, the operation is determined to be abnormal, and a time learning process is executed.

Abstract: A servo error signal generation circuit comprises a first sampling unit for sampling first detection signals at first sampling timings, a second sampling unit for sampling second detection signals at second sampling timings which are obtained by periodically thinning out the first sampling timings, an AD converter for analog-to-digital converting the data sampled by the first and second sampling units, and a completion unit for completing the sampling date of the timings which have been thinned out by the sub sampling timing generator, for the data which have been sampled by the second sampling unit and outputted from the AD converter.

Abstract: The present invention provides an optical disc apparatus capable of rotating an optical disc with high speed while enabling reduced current consumption. The optical disc apparatus comprises a spindle motor for rotating the optical disc and a thread motor for driving an optical pick-up. When a command is received while the spindle motor is driven, a controller delays operation of the thread motor for a predetermined duration to allow operation of the spindle motor rather than immediately activating the thread motor. After the predetermined duration has elapsed, the controller activates the thread motor and halts the operation of the spindle motor. The predetermined duration may be either a fixed value or a variable value established so as to become smaller as rotation speed of the optical disc increases.

Abstract: An optical disk apparatus and method having a pick-up part for emitting a light onto a recording surface of an optical disk and receiving the light reflected from the recording surface of optical disk and a driving part for controlling the pick-up part. The apparatus and method comprise an error detection part for detecting a tracking error based on a distribution of the received and reflected light, when the pick-up part traces vertical movement of the optical-disk according to control of the driving part; a capacity calculation part for calculating capacity of an optical-disk corresponding to the calculated tracking error size; and a tracking control part for resetting a control method of the driving part for the pick-up part to trace a track of the optical-disk based on the calculated capacity. As such, the track of an optical disk may be minutely traced.

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 method for moving a sledge disposed thereon an optical pickup head of an optical disc drive is provided for controlling the motion of the sledge relative to an optical disc loaded. The optical disc drive further includes a sledge motor. At first, the sledge motor drives the sledge to move toward the center of the optical disc. At the same time, the tracks crossed by the optical pickup head are detected and counted according to a tracking error signal generated by the optical pickup head. When the count or an increment in the count within a specific period is not larger than a predetermined value or the tracking error signal is undetectable, the optical disc drive immediately stops the sledge motor from driving the sledge. The monitoring mechanism can avoid undesired impact and noises of the sledge.

Abstract: An optical disk drive capable of detecting occurrence of tooth jump in a mechanism for transferring an optical pickup. The optical pickup is transferred in a radial direction of an optical disk by means of a stepping motor. A control section having received a seek operation command from a host machine drives the stepping motor by way of a controller, to thus cause the optical pickup to perform seek up to a target address. The amount of displacement between a current address achieved after seek operation and a target address is computed. When the amount of displacement is equal to or greater than a pitch P of the transfer mechanism; namely, the pitch P of a lead screw, the tooth jump is determined to have arisen. Seek conditions are changed, and seek is reperformed.

Abstract: In an embodiment of the invention, the use of system parameters can be controlled according to the type of disc, thereby realizing a suitable operation. The embodiment includes means for changing the setting of a reproducing section according to output setting information, when any one of aspect, resolution, and audio used as the output setting information has been changed in the middle of reproducing a first content of the disc, and means for reproducing an object in the second content from an object starting position, when any one of aspect, resolution, and audio used as the output setting information has been changed in the middle of reproducing a second content of the disc.

Abstract: An optical-information recording medium includes a substrate that includes a servo surface; an information recording layer laminated on the servo surface of the substrate capable of recording information as a hologram produced by interference between an information beam containing the information and a reference beam; a tracking servo area that is formed in a track direction on the servo surface, and that records therein tracking information for tracking servo control; and a following up servo area that is formed in the track direction on the servo surface, and that is to be irradiated by a beam emitted from an optical-information recording apparatus for recording the information in the information recording layer so as to make the beam follow a rotation of the optical-information recording medium.

Abstract: A disc type determining apparatus in a disc recording and reproducing apparatus in which vibrations generated by rotations of a disc occur in a focus and tracking control actuator includes an error gain adjusting unit, which adjusts an amplitude of a focus and tracking error in order to maintain a constant amplitude of the focus and tracking error; a loop gain adjusting unit which compares the closed loop phase of the focus and tracking control loop and a predetermined reference closed loop phase, and maintains a constant gain of the focus and tracking control loop; a vibration measuring unit which measures vibrations using the adjusted error and the output of a controller; and a disc type determining unit which extracts a predetermined signal to determine the type of a disc using the measured vibrations, measures the deflection, eccentricity, and mass eccentricity of a disc using the extracted signal.

Abstract: An optical disk drive includes a pickup head, a recording/reproducing circuit, a servo circuit, a driver, a thread motor, a spindle motor, 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 causes 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. The controller calculates the target address by detecting the number of times the reflection intensity of the optical disk changes during the seek, for example. If the controller can perform no 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 this seek is made, the controller performs tracking servo control again.

Abstract: A tracking and servo system with a one-track jump is disclosed. The one track jump algorithm holds a control signal from the tracking servo system. The one track jump algorithm adds an acceleration control signal to the held control signal for a first period of time, delays for a second period of time, and adds a deceleration control signal to the held control signal for a third period of time. The algorithm then frees the control signal to close tracking on a new track separated by one track from the starting track.

Abstract: A disk device includes: an optical pick-up, operable to reproduce data recorded in a disk; a flaw detector, operable to output a flaw detecting signal when a flaw formed on the disk is detected; and a jump controller, operable to control a track jump of the optical pick-up including a first track jump and a second track jump subsequent to the first track jump. A timing of starting to control the track jump corresponding to a still reproduction mode is determined based on a rotational position of the disk. When the flaw detecting signal is outputted in a time period in which the jump controller controls the first track jump corresponding to the still reproduction mode, the jump controller sets a timing for stating the second track jump to a timing different from a timing for starting the first track jump.

Abstract: An image entering from the left side of the figure passes through a correcting lens unit, and forms an image on an image pickup device on the right side of the figure. The correcting lens unit includes a cylindrical outer frame and a lens arranged therein, and at coupling points, coupled to one end of each of electrostrictive coils and suspended thereby. Electrostrictive coils strain in response to voltages applied from a voltage applying unit, causing displacement of electrostrictive coils. The displacement is transmitted to correcting lens unit through the coupling points, and therefore, in accordance with the displacement from electrostrictive coils, position and/or direction of correcting lens unit changes.

Abstract: A method of one embodiment of the invention is disclosed that outputs an oscillating wave towards a surface of an optical disc. A proximity signal is detected in response to the oscillating wave being output towards the output of the optical disc, and denotes closeness of the oscillating wave to the surface. A number of peaks within the proximity signal are determined. Each peak corresponds to the oscillating wave crossing the surface of the optical disc. 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 disc is approximated from these time-value pairs.

Abstract: An optical playback or recording device is equipped with mass-unbalance detection means (20) for detecting unbalance on the record carrier (2). Mass-unbalance causes vibration and sound in the optical device when the record carrier (2) is rotated at a relatively high speed. When mass-unbalance is detected, the speed may be reduced to reduce the vibration and sound in the optical device. The mass-unbalance detection means (20) performs the following steps to detect mass-unbalance: a) determining the maximum value Umax1 of the actuator control signal (AS) at a rotational speed ?1; b) determining the maximum value Umax2 of the actuator control signal (AS) at a rotational speed ?2; c) comparing Formula (I) with Formula (II). If these values are substantially equal, then the effect of mass-unbalance is small, otherwise the effect of mass-unbalance is too great and the speed may have to be reduced U max ? ? 1 ? 1 2 ? ? with ? ? U max ? ? 2 ? 2 2 .

Abstract: An optical disc drive is used to read and/or write data from/on an optical disc having a data storage layer. The drive corrects electrical offset while reading and/or writing data. The drive updates a correction value based on an electrical offset detected at correcting operation or a value derived using electrical offset values that has been detected and stored, without detecting an electrical offset at correcting operation. Therefore, the optical disc drive can correct the electrical offset less often.

Abstract: A optical disk drive long distance seek control device and method thereof, capable of feeding back the optical head control device through the step motor control device during the long distance seek; wherein, the step motor control device comprises a velocity profile generator capable of producing a quadratic profile to stabilize the step motor when finishing the seek; and more particular, the optical head control device uses a center error signal and a velocity error signal alternatively; moreover, the velocity error signal can be adjusted according to the output signals from the optical head control device and the step motor control device through a weighting mechanism.

Abstract: A focus jump technique enables focus control on recording layers of a disc in such a manner that its effect is not absorbed by disturbance or a variation in the movement speed of an objective lens. The technique involves monitoring level of a focus error signal and rejecting noise from the error signal. A speed sensor detects movement speed of an objective lens; and a speed control circuit generates a voltage for controlling the objective lens, based on the detected movement speed. Movement speed of the objective lens is detected during focus jump, a corresponding lens drive signal is generated, and an end position is determined from behavior of the error signal immediately before the end of the jump. A focus control is pulled, from a focus point corresponding to one recording layer, into a focus point corresponding to another recording layer forcibly in a stable manner.

Abstract: Track jumping on optical storage media whose address information items invalidate the track error signal at time intervals is intended to be configured more securely and more reliably. For this purpose, at the end of a coarse jump, one or more correction jumps are carried out if the optical scanner is not presently sweeping over an address information area and the track change frequency of the tracks crossed by the scanner falls below a predetermined value.

Abstract: A focus jump technique enables focus control on recording layers of a disc in such a manner that its effect is not absorbed by disturbance or a variation in the movement speed of an objective lens. The technique involves monitoring level of a focus error signal and rejecting noise from the error signal. A speed sensor detects movement speed of an objective lens; and a speed control circuit generates a voltage for controlling the objective lens, based on the detected movement speed. Movement speed of the objective lens is detected during focus jump, a corresponding lens drive signal is generated, and an end position is determined from behavior of the error signal immediately before the end of the jump. A focus control is pulled, from a focus point corresponding to one recording layer, into a focus point corresponding to another recording layer forcibly in a stable manner.

Abstract: Information about the number of traversed tracks is acquired with a code at a first rotational speed and a second rotational speed in each area provided by dividing one rotation into m (m is a natural number equal to or larger than 1). As to the information about the number of traversed tracks, a difference is calculated between the areas. A value proportionate to the sum of absolute values of the information about the traversed tracks in the areas is used as a vibration detection value proportionate to vibration amplitude.

Abstract: A track-locking method for an optical disk drive is conducted according to the following steps. First, a tracking error signal (TE signal) is detected, and then the time period for a pickup head jumping from one track to another track is divided into four periods. Secondly, the extreme values of the reshaped tracking error signal (TE? signal) in the first, second and third periods are preset, and the TE signal of the first period is reshaped in view of the extreme value of the TE? signal in the first period and the crest value or the trough value of the TE signal, so as to form the TE? signal in the first period. Then, a line connecting the extreme values of the TE? signal in the first period and the second period is established as the TE? signal in the second period, and a line connecting the extreme values of the TE? signals in the second and third periods is established as the TE? signal in the third period.

Abstract: A data access method for improving performance of an optical disk drive is applied on a predetermined data access operation. A predetermined application program and the optical disk drive are used to run first, second, and third processes for accomplishing the predetermined data access operation. The predetermined application program runs the first process, and the optical disk drive runs the second process. The data access method includes the predetermined application program running the first process and outputting a control command to command the optical disk drive to start the second process, and the predetermined application program running the third process for controlling the optical disk drive to access an optical disk after the first process and the second process are finished. In addition, the time for the predetermined application program to complete the first process overlaps the time for the optical disk drive to complete the second process.

Abstract: An optical disc apparatus has a crosstalk level determining section which, when a track jump is performed without applying a tracking servo, determines whether a crosstalk component is larger than a predetermined level or not. If the crosstalk level determining section determines that the crosstalk component is larger than the predetermined level, a crosstalk correcting section performs a calculation for reducing the crosstalk component. If the crosstalk level determining section determines that the crosstalk component is not larger than the predetermined level, the crosstalk correcting section does not reduce the crosstalk component.

Abstract: An optical disk device in which data is written to or reproduced from an optical disk having an area which contains a header section and another area which does not contain a header section. When a track deviation of an optical pickup occurs, it is detected whether or not a signal representing the header section is contained in the return light signal from the optical disk. When a signal representing the header section is contained in the return light signal, it is determined that the optical pickup is located in an area which contains a header section and tracking is controlled through a push-pull method etc. On the other hand, when a signal representing the header section is not contained in the return light signal from the optical pickup, it is determined that the optical pickup is located in an area which does not contain a header section and tracking is controlled through differential phase detection etc.

Abstract: A compensation method for detecting the seeking speed of an optical disk drive involves the following steps. First, a TE signal is converted into a TEZC signal, or an RFRP signal is converted into an RFZC signal. Then, take the average of the respective pulse widths of an upper waveform and an adjoining lower waveform of the TEZC signal or the RFZC signal to acquire the recovered TEZC signal or RFZC signal wherein both the upper waveform and the lower waveform are decided by a slice levels.

Abstract: A focus jump technique enables focus control on recording layers of a disc in such a manner that its effect is not absorbed by disturbance or a variation in the movement speed of an objective lens. The technique involves monitoring level of a focus error signal and rejecting noise from the error signal. A speed sensor detects movement speed of an objective lens; and a speed control circuit generates a voltage for controlling the objective lens, based on the detected movement speed. Movement speed of the objective lens is detected during focus jump, a corresponding lens drive signal is generated, and an end position is determined from behavior of the error signal immediately before the end of the jump. A focus control is pulled, from a focus point corresponding to one recording layer, into a focus point corresponding to another recording layer forcibly in a stable manner.

Abstract: An optical storage disc stores storage information and includes track information. A method for performing a target search on the optical storage disc includes: generating a first intermediate signal according to a readout signal generated by an optical storage device reading the storage information; generating a second intermediate signal according to the track information carried within the readout signal; generating a hybrid address signal according to the first intermediate signal and the second intermediate signal; and performing the target search on the optical storage disc according to the hybrid address signal and a target address set by the optical storage device.

Abstract: A method of tracking error correction, primarily for utilization in optical disc drives using single beam optical pick-up heads. Delinearization in the tracking servo of a single beam optical pick-up head, contributed to by inherent design properties, is minimized by extracting a value proportional to a tracking error signal offset component from a tracking servo demand signal, applying a scaling factor to match the scaling applied to the tracking servo demand signal with scaling applied to the amplified tracking error signal, and subtracting the product of this function from the source signal i.e. the tracking error signal. The modified source signal, following this operation, has a reduced order of tracking error offset.

Abstract: The present invention provides an information storage apparatus that generates a tracking error signal based on a detection signal, and performs various control operations based on the tracking error signal. When the operation mode is a seek operation mode, the information storage apparatus generates a tracking error signal by holding the peak value of the detection signal. When the operation mode is a tracking operation mode, the information storage apparatus generates a tracking error signal directly from the detection signal. With this information storage apparatus, stable control operations can be performed, regardless of changes of conditions.

Abstract: A positioning control apparatus for controlling a moving member to trace the position of a target member which almost equally repeats the position shift at a predetermined period comprises a position detector for detecting a relative position error, a first adder for adding a delay signal and a position error signal, a signal delay unit for outputting the delay signal which is obtained by delaying an output signal of the first adder at a period corresponding to the position shift of the target member, a second adder for adding the position error signal and the delay signal, a third adder for adding an output of the second adder and the delay signal via a filter, a compensating unit for performing the compensation for offset and/or the compensation for stabilization of the positioning control apparatus based on an output of the third adder, a drive unit for driving the moving member based on an output of the compensating unit, and a delay-amount setting unit for setting the amount of delay of a signal delayed

Abstract: Techniques for reading data from a storage medium (150) having a high track density prone to adjacent track interference are disclosed. One or more sensing elements (120) are used to extract data stored on adjacent tracks. Multiuser detection (130) is then used to detect/decode a single track that is closely spaced to its neighboring tracks, resolve interference from adjacent tracks, or to simultaneously detect/decode multiple adjacent closely packed tracks.

Abstract: A circuit to improve the SN characteristic of a tracking error signal. This tracking error detection circuit is formed as a push-pull system utilizing a quadrant type photo-detector and provided with 4 gain control amplifiers 20, 22, 24, and 26, 4 bottom envelope circuits 28, 30, 32, and 34, a pair of subtracting circuits 36 and 38, adding (subtracting) circuit 40, offset circuit 42, and gain control circuit 44. Bottom envelope circuits 28, 30, 32, and 34 are configured with a capacitor-type peak-hold circuit, for example, whereby bottom envelopes of RF signals SA, SB, SC, and SD given from light receiving areas A, B, C, and D of a photo-detector via gain control amplifiers 20, 22, 24, and 26 are detected, and bottom envelope signals SAbtm, SBbtm, SCbtm, and SDbtm representing the waveforms of the respective bottom envelopes are output.

Abstract: An apparatus to generate a seek direction detecting signal for an optical pickup to determine a position of a center of an optical spot focused on an optical disk relative to a center of a track, which focuses a main beam on a first optical detector and a sub-beam having a predetermined aberration in a radial direction on a second optical detector using a light dividing unit. The second optical detector has an inner and an outer pair of light receiving portions arranged along the radial direction, the inner pair being between the outer pair. A signal processing portion includes a first signal processing portion to detect a track error signal from signals output from the first optical detector, and a second signal processing portion to generate the seek direction detecting signal from signals detected by the second optical detector and the track error signal.

Abstract: A device for reading and/or writing information from an optical carrier, the device comprising an imager for imaging a radiation beam into scanning spot to scan the carrier, and a detector for generating a read signal indicative of the intensity of the radiation reflected from the carrier. The device has an information transfer mode, wherein the scanning spot is moved in a first direction. The device has a displacement mode, wherein the scanning spot is moved in a second direction transverse to the first direction. The device includes a controller for controlling the imager in response to a measurement signal indicative of the degree of focusing of the radiation beam. The controller samples and holds the measurement signal in response to a sample signal causing the measurement signal to be sampled when the intensity is comparatively high thus reducing radial-to-vertical crosstalk.

Abstract: An optical disk device and a tilt correction method capable of high precision tilt correction with a smaller number of measurement positions are provided. Prior to data recording and reproduction, a number of measurement positions are set in the radial direction on an optical disk with intervals between two adjacent measurement positions shorter and shorter from the inner region to the peripheral region of the optical disk. The tilt at each of the measurement positions is measured, and the resulting tilt data are stored in a memory. The tilt data are used for making tilt corrections when recording or reproducing data on the optical disk.

Abstract: An information storage device having a uniaxial tracking mechanism as a pickup which can perform a stable track pull-in operation is provided. A deceleration pulse amplitude á supplied to a tracking actuator is determined from a linear function á=K(V?V0) of a detected movement velocity of a beam in the vicinity of a target track. The deceleration pulse amplitude is divided into two, and is supplied to the tracking actuator on two different occasions.

Abstract: A method for long seeking control of an optical read/write head is disclosed. The optical read/write head includes a sled moved by a sled motor, and a lens mounted on the sled and moved by a lens actuator, and said method includes steps of determining a velocity profile according to a desired travel distance of the optical read/write head; detecting an instant velocity and an instantaneous position of the optical read/write head at a certain time spot; comparing the instant velocity with a target velocity corresponding to the instantaneous position according to the velocity profile; modifying velocities of the sled and the lens according to the comparing result; and dynamically adjusting a position of the lens in the sled. An apparatus for long seeking control of an optical read/write head is also disclosed.

Abstract: A disc drive includes a tracking actuator, and determines when the tracking actuator is positioned off a formatted portion of optical media in the disc drive. The optical media includes a pitted premastered area that cannot be overwritten and a grooved user-writeable area that can be overwritten. Tracking control effort is monitored to determine when the tracking actuator is in the off-format condition and whether tracking good or tracking bad is detected within a predetermined time period. An absolute value of the tracking control effort is generated and the absolute value of the tracking control effort is filtered. An off-format condition is indicated if the filtered value of the tracking control effort is not within a predetermined threshold value.

Abstract: Disclosed is a track-search control circuit for performing track-search of an optical disc stably even at the time of multi-speed reproduction of the optical disc.

Abstract: A method for labeling an optically writable label side of an optical disc of one embodiment of the invention is disclosed which includes at least one of the following. First, the method may multiply pass over a track of the optically writable label side of the optical disc with an optical marking mechanism, such that the optical marking mechanism writes to the track during each pass. Second, the method may advance the optical marking mechanism from the track to a next track of the optically writable label side of the optical disc, such that a starting position on the track is radially non-collinear with a starting position on the next track.

Abstract: Method for tracking in an apparatus for reading from and/or writing to an optical recording medium, and corresponding apparatus for reading from and/or writing to an optical recording medium. In order, in an apparatus for reading from and/or writing to an optical recording medium (18), to enable exact counting of the tracks of the optical recording medium (18) crossed by an optical scanning unit (16), it is proposed to derive a signal corresponding to the TZC signal (Tracking ZeroCross) and also a signal corresponding to the MZC signal (Mirror Zero Cross) from the output signal or the output signals (OUT1, OUT2) of a phase comparator (1) provided for tracking in accordance with the so-called differential phase detection method.

Abstract: A device and a method for judging the radial moving direction of light spots formed on the signal recording surface of an optical disc having grooves of two types, which are different from each other in terms of depth and which are arranged along a recording track that is a land of the optical disc. The judging section of the device judges the moving direction of the main spot on the basis of binarized data of a difference signal of the main spot and binarized data of a difference signal of one of spots on the side. With this arrangement, the moving direction of the light spots relative to a radial direction of the optical disc can be determined only by using difference signals without using any sum signal.

Abstract: The present invention provides a method for adjusting the mechanical error of an optical disc reading device. The optical disc reading device consists of a driving device and an optical pickup. The driving device has a base plate for supporting and rotating an optical disc. The method consists of moving the optical pickup to surface of optical disc, the optical pickup emitting two tracking light spots onto the surface, and the optical pickup reciprocally moving relative to the surface. Next, the optical pickup reads reflected signal of two tracking light spots for generating a track crossing signal. By using the track crossing signal, the method adjusts position of optical pickup relative to the base plate.