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

Abstract: An optical disc apparatus of the present invention includes an optical head (103) including a lens disposed at a position shifted from a traverse axis in a tangential direction, a traverse motor (104) as a second moving unit that moves the optical head (103) in a direction traversing tracks of the optical disc (101), a number-of-tracks calculating part (123) that calculates, as the number of tracks to be sought, the number of tracks that the optical head will traverse when moving from a first address to a second address of the optical disc (101), a tracking-drive-signal-at-seek generating part (112) and a traverse-drive-signal-at-seek generating part (119) as seek controlling units that move a convergent point of an optical beam from the first address to the second address, and a number-of-tracks correcting part (124) that corrects the number of tracks to be sought according to a shift amount of the lens from the traverse axis.

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: A servo system with a multi-track seek algorithm with an acceleration clamp is presented. The multi-track seek algorithm detects zero crossings in a tracking error signal, counts the number of zero crossings to form a count, and calculates a reference velocity from the count. The algorithm also determines a time period between successive zero crossings, calculates a velocity from the time period, calculates a difference signal between the reference velocity and the velocity, and adjusts the control signal so that the velocity follows the reference velocity. The reference velocity can follow a velocity profile with acceleration portions, coasting portions, and deceleration portions which move an optical pick-up unit from a starting position to a target position. The acceleration of an optical pick-up unit is clamped during the multi-track seek operation.

Abstract: Disclosed is a method and apparatus for controlling the record and reproduction of optical record medium in which plural non-record regions having different phase are arranged between recordable data regions for the distinction in the shape of the data region. The method and apparatus performs the servo using focus error signal and tracking error signal averaged by the low pass filter at the header region of the optical disc. Especially, the tracking servo is performed by holding a fixed DC off-set value at the header region existing on the L/G switching or holding the tracking error value of the previous same track region. As a result, the exact header region is detected, the track sliding phenomenon is removed, and the tracking servo is stabilized, resulting in preventing the degeneration of the record and reproduction characteristics.

Abstract: An intelligent layer jump method applied when an optical disc drive accesses a disc. The disc has a central reference point, at least a first recoding layer and a second recoding layer. The first recoding layer has a plurality of first tracks, while the second recoding layer has a plurality of second tracks. Firstly, a laser beam of the optical disc drive is focused on the first recoding layer to form a focal point and obtain an original position. Then, the relative position between an original position and a target position positioned on the second recoding layer are compared to determine a layer jump and track seeking path of the focal point. Lastly, the focal point is shifted from the original position to the target position according to the predetermined layer jump and track seeking path.

Abstract: A rotation correcting apparatus has a tracking servo controller which generates a tracking signal to perform a tracking servo control for guiding an optical beam spot outputted from a pickup to tracks of an optical disk and a track jump control for moving the optical beam spot to a certain track; a feed motor controller which controls a feed motor for moving the pickup to radius direction of the optical disk; a storage which stores signal component with a prescribed frequency band including a rotation frequency of the optical disk, the signal component being included in an output signal of the tracking servo controller; and a combination unit which combines the signal component stored in the storage with the tracking signal to generate an ultimate tracking signal for the tracking servo control and the tracking jump control, wherein the feed motor controller controls the feed motor based on the tracking signal generated by the tracking servo controller without using the signal component stored in the storage.

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

Abstract: A method for reading data from a track (3) of a data carrier (2) comprises the following steps. During reading, a tracking quality parameter (Q) is determined, relating to a track portion (3Px) of the data carrier from which the data is being read. The tracking quality parameter is stored in a tracking performance memory (30) in relation to the corresponding track portion (3Px). If a jump back to a previously read track portion appears to be necessary, said tracking performance memory (30) is consulted to determine a target track portion (3P(x-n)) having a sufficient value of the tracking quality parameter (Q); then, a jump back (JB) to the target track portion (3P(x-n)) thus determined is performed.

Abstract: The present invention discloses a method and apparatus of seek end polarity detection for an optical disk drive. The method comprises the steps of providing a horizontal level between the peak and the trough of the tracking error signal when the tracking error signal is used to determine the polarity of the tracking error; and determining the tracking error polarity by examining whether or not the adjacent waveform level is smaller or larger than the horizontal level after the tracking error signal passes through the horizontal level.

Abstract: A tracking error detector receives laser light that is irradiated onto tracks on a disc surface and that is reflected from the tracks by using a light-receiving device having divided portions, binarizes signals output from the light-receiving device having divided portions in accordance with the amount of tracking error by using a signal processing circuit including a binarization circuit, and outputs a tracking error signal for tracking control on the basis of a phase difference between the binarized signals. The tracking error detector includes an inter-signal amplitude difference adjustment circuit for determining an amplitude difference between signals output from the light-receiving device, for adjusting the amplitude difference between the signals, the amplitude difference being binarized by the signal processing circuit, for equalizing the phase offset of each of the signals, and for suppressing the phase offset with respect to the tracking error signal.

Abstract: An optical pickup apparatus capable of compensating for a thickness deviation of a high-density optical recording medium is disclosed. The optical pickup apparatus has a light source, a collimator lens, a beamsplitter, and an objective lens system comprising a solid immersion lens which has a planar surface facing the substrate of the optical recording medium. The optical pickup apparatus has a position adjustment unit connected to the light source or the collimated lens, mating the light source or the collimated lens shift according to a focus control signal generated from the focus control unit. Further, a finite optical pickup apparatus in which a collimator lens is not used has a position adjustment unit connected to the light source, making the light source shift according to the focus control signal.

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: An optical disk device includes a pickup head, a thread motor, and a drive controller, and a thread drive IC. The drive controller supplies directed voltage to the thread drive IC. The thread drive IC in response supplies drive voltage to the thread motor, which moves the pickup based on the drive voltage from the thread drive IC. The drive controller directs to the thread drive IC supply of first directed voltage. The thread drive IC supplies first supplied voltage to the thread motor in response to the directive from the drive controller to supply the first directed voltage. The drive controller detects the first supplied voltage and calculates a correction value based on the detected first supplied voltage. The drive controller corrects the directed voltage with the correction value and then directs to the thread drive IC supply of a corrected drive voltage.

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: In an optical disc device of the present invention, time differences among the focus error signal corresponding to the surface of the optical disc, the focus error signal corresponding to the first reflection layer, and the focus error signal corresponding to the second reflection layer, all of which are obtained through the light receiving element when a relative distance between the objective lens and the optical disc is linearly changed in a focus search of the optical disc are measured. The thickness of the cover layer from the surface of the optical disc to the first reflection layer and the thickness of a cover layer from the surface of the optical disc to the second reflection layer are detected on the basis of these time differences.

Abstract: The present invention provides a method for reading information recorded in a boundary area adjacent to a boundary between a first area and a second area on an optical disc. The method includes: controlling a pick-up head (PUH) to detect the optical disc to generate a detection signal accordingly; moving the PUH along a first direction from a start point; monitoring the detection signal and stopping the PUH when the detection signal changes; moving the PUH along a second direction; monitoring the detection signal and stopping the PUH in the boundary area of the first area when the detection signal changes; and reading the information recorded in the boundary area of the first area by the PUH.

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: A motor control circuit for reducing current consumption. A stepping motor control circuit includes an A/B phase current setting signal generation circuit for generating an A/B phase current signal setting signals provided to a stepping motor driver to supply a stepping motor with a predetermined amount of drive current. Based on a switch signal, first and second switches selectively output an A/B phase current setting signal and an A/B phase reference signal, for reducing the drive current of the stepping motor more than the A/B phase current setting signal. An intermittent drive control circuit generates the switch signal. The stepping motor control circuit provides the motor driver with the A/B phase reference signal in accordance with the switch signal.

Abstract: The invention relates to a system and method of recording data on an optical disc by a plurality of laser beams positioned along inner tracks to outer tracks of said optical disc, said optical disc comprising segments each being identified by a start of segment, said method comprising the steps of: switching writing on (710) successively each laser beam at different starts of segments for recording data, switching writing off (720) successively each laser beam arriving at the start of a segment previously recorded by another laser beam, detecting (730) when only one laser beam remains writing on, detecting (740) a subsequent start of a segment accessed by said one laser beam, switching writing off (750) said one laser beam, shifting (760) all the laser beams so that the innermost laser beam gets positioned at said subsequent start.

Abstract: A method and apparatus for detecting a signal to determine on-track/off-track and/or a track cross direction, using a detection signal corresponding to a reflected main light beam and detection signals respectively corresponding to reflected first and second sub light beams, and an optical recording and/or reproducing apparatus using the same are provided. When detection signals respectively corresponding to one side portions, in a direction corresponding to a radial direction of the optical information storage medium, of the respective main light beam and first and second sub light beams are referred to as a first main signal, a first sub signal, and a second sub signal, respectively, the method and apparatus include obtaining a first operational signal, which is used to determine on-track/off-track and/or a track cross direction, by performing a subtraction on the combination of the first and second sub signals, and the first main signal.

Abstract: The present invention provides a system for causing an optical beam to impinge on a spot on an optical medium, while keeping an optical head apparatus in an essentially stationary position, such that it eliminates the need for a tracking function to move an optical head apparatus in order to direct an optical beam between tracks or to an location on the optical medium.

Abstract: Optical disc drives designed for reduced power consumption switch the supply voltage in three stages between first, second, and third power supplies. The reduction in power consumption that is possible in the focusing and tracking drive circuits with three stage switching control is limited. This drive apparatus enables further reductions in power consumption. A drive output tracking signal is generated according to the drive conditions of the focusing or tracking drive circuit. The drive output tracking signal is applied to the drive circuit power supply, and the power supply is controlled according to the drive output tracking signal. A power supply change detector detects sudden changes in the drive output tracking signal, and inputs the detection signal to the DSP controlling the entire system. The DSP determines whether to improve the power supply response by comparison with predetermined conditions, and returns the result to the power supply.

Abstract: According to one embodiment, an optical head device provides a signal processing circuit which sets a control amount to move an objective lens so that a distance between the objective lens and a given recording layer of the an optical disc coincides with a focal position, an optical path length correction mechanism which corrects an influence of an aberration component producing an error in the focal distance, a thickness difference detection circuit which finds an amount of correction to be made by the optical path length, and an aberration correction circuit which generates a correction signal to correct the influence of the aberration component producing the error in the focal distance detected by the thickness difference detection circuit, and supplies the correction signal to the optical path length correction mechanism.

Abstract: A method and apparatus for controlling a focus of an optical disk in an optical disk recording/reproducing apparatus are provided. A method of controlling focusing onto an optical information storage medium having a plurality of data layers during an interlayer jump by moving an object lens up and down includes receiving a focus jump command for a focus jump from a current data layer to a target data layer, performing spherical aberration correction on the target data layer, holding a focusing servo with respect to the current data layer, and performing the focus jump to the target data layer in which the performing of the focus jump includes applying an acceleration pulse to a focus control signal for controlling driving of the object lens, and terminating the application of the acceleration pulse when the level of a sum signal resulting from the summation of the amplitude of light reflected from the optical information storage medium and collected by a light detector is less than a predetermined level.

Abstract: Disclosed is an apparatus which includes a tracking error detection circuit, for detecting tracking error signal from outputs of a photodetector, a peak/bottom detection circuit for detecting peak and bottom values of the tracking error signal, a difference circuit for finding the difference between a peak value and a bottom value, and a comparator for comparing an output of the difference circuit with a preset reference voltage VR to output a tracking-off signal based on the result of comparison. The comparator outputs the tracking-off signal, indicating the tracking-off of the light beam spot with respect to a track.

Abstract: An optical disk drive is used for recording data to and/or reproducing data from an optical disk. The optical disk drive includes a pickup head, a stepping motor, an ASP, and a DSP. The stepping motor is used for moving a pickup head to seek a target track of the optical disk from an initial track. The ASP is used for converting an analog electronic signal from the pickup head to a digital electronic signal. The DSP is used for obtaining a current position of the pickup head by analyzing the digital electronic signal, and for calculating a current track count between the current track area and the target track area and modifying a current distance per step of the stepping motor with an actual distance per step calculated based on the current track count. A seeking method is also disclosed.

Abstract: A system, method, computer program and apparatus for providing regulating signals for regulating the position of an objective lens relative to a track on a disk. The regulating signals are obtained in response to an access request specifying an access target region on the disk. The tracks of a disc are divided into a plurality of zones, each zone having associated signal regulation information. In response to an access request, the signal regulation information for the zone containing the access target region is used to regulate the position of the objective lens.

Abstract: A seek control unit increments by a first magnitude the maximum speed when the pickup head is moved while the number of jumped tracks can be counted appropriately. If the number of tracks jumped during seek could not be counted appropriately, the seek control unit decrements the maximum speed by a second magnitude. The seek control unit sets the maximum speed stored in a speed information storage device 8 for a marginal speed. Once set for the marginal speed, the seek control unit, even when the number of jumped tracks can be counted appropriately, does not execute updating of incrementing the maximum speed stored in the speed information storage unit.

Abstract: An apparatus for recording/reproducing holographic data which can record holographic data in a data storage medium and can reproduce recorded data includes a light source emitting a laser beam, a lens unit focusing the laser beam emitted from the light source by classifying the laser beam into a reference beam passing through a first area and a signal beam passing through a second area and having a first lens focusing the signal beam to a first focus and a second lens focusing the reference beam to a second focus, and a driving unit driving the first lens to vary the first focus in a depth direction of the data storage medium.

Abstract: An optical disk drive is used for recording data to and/or reproducing data from an optical disk. The optical disk drive includes a storing module, a controlling module, an actuator, and a pickup head. The actuator is connected to the controlling module. The storing module is used for storing at least one measured tracking error signal. The controlling module is used for generating the adjusted track-jumping control signal based on the track-jump command and a measured tracking error signal chosen from the storing module. The actuator is used for generating a driving force based on the adjusted track-jumping control signal to move the pickup head to a targeted position by the driving force.

Abstract: There is provided an optical disk device that performs a focus jump operation in a stable and prompt manner. The optical disk device includes an objective lens, a light-detecting element, a lens holder, a shaft member configured to penetrate a hole, a focus drive mechanism, a focus drive circuit, a tracking rotation mechanism, a tracking drive circuit, and a control circuit. The control circuit includes a drive control portion, a wobble control portion, and a switch portion. The drive control portion generates a control signal to be input to the focus drive circuit and a control signal to be input to the tracking drive circuit. The wobble control portion generates a control signal indicating that a current value should fluctuate. During a period of focus jump, the switch portion introduces into the tracking drive circuit the control signal generated by the wobble control portion.

Abstract: A scanning probe microscope includes a scanning probe tip and an electrostatic surface actuator operatively coupled to the scanning probe tip. The electrostatic surface actuator includes a movable member that has a first surface with a first plurality of electrodes disposed on the first surface and a stationary member that has a second surface with a second plurality of electrodes disposed on the second surface. The first and second surfaces are disposed in a confronting relationship The movable and stationary members are resiliently coupled so that the movable member is capable of being displaced with respect to the stationary member. The first and second pluralities of electrodes are configured to generate electrostatic forces in response to voltages applied. The electrostatic forces laterally displace the movable member in the direction generally parallel to the first and second surfaces. The scanning probe tip is controllably positioned by displacement of the movable member.

Abstract: An adaptive frequency detector used in a phase locked loop for detecting a frequency difference between an input signal and an output clock generated from an oscillator of the phase locked loop includes: a frequency comparator for generating an up signal or a down signal according to the frequency difference between the input signal and the output clock; and a pulse controller coupled to the frequency comparator for generating a charge signal based on the up signal or generating a discharge signal based on the down signal. The pulse controller dynamically adjusts the pulse width of the charge signal or the pulse width of the discharge signal.

Abstract: A motor control method for rotating an optical disc to be accessed by an optical head includes steps of: providing an increasing power to rotate a motor at increasing speed when a seeking operation of the optical head is performed; and interrupting the increasing power when a jumping operation of the optical head is performed.

Abstract: An optical disk medium includes a track groove thereon. On the optical disk medium, information is recorded along the track groove on a block unit basis. The block unit has a predetermined length. The block unit having the predetermined length includes a number of sub-blocks that are arranged along the groove. A sub-block mark is provided within each of the sub-blocks and used to identify the sub-block.

Abstract: A method for controlling a stepping motor in an optical storage system and for achieving a short seek with the stepping motor is disclosed. The optical storage system comprises a pick-up head and object lens, wherein the object lens is movably installed on the pick-up head. The method includes determining a number of steps that the stepping motor should rotate; moving the object lens toward a target track; and utilizing the stepping motor to move the pick-up head toward a target position according to the number of steps that the stepping motor should rotate.

Abstract: In an apparatus for reading from and/or writing to an optical recording medium, it is desirable, in particular in the case of track jumps, to detect the direction of the track jump, i.e. the direction of movement of an objective lens of the apparatus relative to the optical recording medium in order to be able to carry out corresponding track regulation. For this purpose, and also for determining the number of tracks crossed by the scanning beams, it is proposed to determine the number of zero crossings and also the phase difference between at least two error signals derived from the reflected scanning beams.

Abstract: The present invention obtains a more optimal focus in at least two dimensions (such as axial and radial dimensions) by setting or keeping a focus in at least a first dimension (such as both axial and radial dimensions) and detecting and adjusting the focus in a second dimension (such as radial dimension) so that it can be brought to the same focal plane as the focus for the at least first dimension (such as both axial and radial dimension). An actuator lens assembly is used to continually adjust the focus for either primarily the first dimension or primarily the second dimension, using a feedback loop. In one embodiment of the present invention, certain photocell(s), (such as photocells E and F that are normally used for tracking) are compared to certain photocell(s), (such as photocells A and B and C and D) in order to derive a Radial Focus Error (RFE) signal, by observing radial spot size.

Abstract: An optical disc drive and a method of controlling the same. The optical disc drive includes: a pickup module to apply a laser beam to a surface of a record layer of an optical disc, and forming a focal point on the record-layer surface; and a servo controller to correct (e.g., iteratively or otherwise) the servo gain to allow a record-servo gain to move along a playback-servo gain of the optical disc. Therefore, the optical disc drive and associated method provide servo-control.

Abstract: Minimum deflection acceleration point detection, focus pull-in, and layer jump methods, and an optical disc drive capable of performing the methods. The method of detecting a minimum deflection acceleration point in an optical disc drive includes rotating a disc loaded in the optical disc drive, detecting a first minimum deflection acceleration point of the disc during one rotation cycle of the disc, and detecting a second minimum deflection acceleration point of the disc during one rotation cycle of the disc. Thus, a stable focus pull-in and layer jump is available.

Abstract: The track jumping of a scanner on optical storage media in which information items are stored on groove and land tracks or which have not yet been written to is intended to be made possible in a reliable manner. For this purpose, firstly a fictitious track type is defined for a regulating circuit, which regulates the position of the scanner. The regulating circuit is then closed on the basis of the track type defined and a track scanning signal. The reaction of the scanner to the closing is detected in order to obtain from this an item of information about the track type. This method is also advantageous, in principle, for closing the track following regulation in information carriers having relatively high storage densities.

Abstract: A method for controlling long seeking operation in an optical disc drive is provided. The optical disc drive includes a sled actuator, a pickup head installed on the sled actuator for reading and/or writing data in an optical disc, and a controller for controlling the sled actuator to move together with the pickup head. The method includes the steps of (a) receiving remaining tracks information indicating a number of tracks remained to be crossed by the sled actuator and/or the pickup head; (b) receiving velocity information indicating a velocity of the sled actuator and/or the pickup head; (c) receiving acceleration information indicating an acceleration of the sled actuator and/or the pickup head; (d) driving the sled actuator to move according to the remaining tracks information, the velocity information, and the acceleration information.

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: System and method for synchronizing the low speed mirror movement of a mirror display system with incoming frame or video signals, and synchronizing buffered lines of video data to the independently oscillating scanning mirror. According to one embodiment of the invention, the peak portions of the low speed cyclic drive signal are synchronized with the incoming frames of video by compressing or expanding the peak portion or turn around portion so that each video frame begins at the same location on the display screen. The actual position of the high frequency mirror is determined by sensors and a “trigger” signal is generated to distribute the signals for each scan line such that the scan lines are properly positioned on the display.

Abstract: An optical disc drive and a control method thereof perform a stable layer jump in a deflected optical disc having surface vibration component to increase a rate of success of the layer jump. Accordingly, recording and reproducing of information between layers are continuously performed. The control method of an optical disc drive includes rotating an optical disc, detecting a point where an optical axial relative movement between the optical disc and a pickup module is zero or about zero, and controlling the pickup module such that a layer jump is performed in the vicinity of a point where the optical axial relative speed or movement between the optical disc and the pickup module is zero or about zero during the rotation of the optical disc.

Abstract: This disk device includes a pickup head (PUH), a PUH shift control unit, and an inner circumference position detection unit. The PUH reads out data upon a disk. The inner circumference position detection unit detects whether or not the PUH has shifted to the inner circumferential edge of the disk. And, after having stopped the PUH in the neighborhood of a position at which the detection state of the inner circumference position detection unit changes over, the PUH shift control unit determines a shift time period T5 for the PUH when a predetermined operation has been performed. And, by supplying power during the time period T7, the PUH is stopped at a predetermined position.