Abstract: A hard disk drive includes a magnetic recording medium comprising data sectors along a data track, a read head arranged to read data from the data sectors, and an integrated circuit. The integrated circuit includes circuitry programmed to detect a read error associated with a first of the data sectors and continue to read data from the data sectors after the detection of the read error.

Abstract: The invention relates to a method that comprises receiving wireless energy from a wireless energy transmitter device; determining a power level value of the received wireless energy; manipulating value of the determined power level to obtain a manipulated power level value; and sending the manipulated power level value to the wireless energy transmitter device so that a FOD does not prevent the power transfer from the wireless energy transmitter device. The invention further relates to an apparatus, a device and a computer program product for performing the method.

Abstract: The invention relates to a method that comprises receiving wireless energy from a wireless energy transmitter device; determining a power level value of the received wireless energy; manipulating value of the determined power level to obtain a manipulated power level value; and sending the manipulated power level value to the wireless energy transmitter device so that a FOD does not prevent the power transfer from the wireless energy transmitter device. The invention further relates to an apparatus, a device and a computer program product for performing the method.

Abstract: A control apparatus that controls one or more first communication apparatuses and one or more second communication apparatuses configured to identify a logic level of a signal, the control apparatus includes a memory; and a processor coupled to the memory and configured to: acquire, from one of the one or more second communication apparatuses, a length of an undefined time period during which a level of the signal is undefined; determine, based on the length of the undefined time period, a length of a protection time period indicating a time period during which a logic level of the signal received by the second communication apparatus is maintained at a same level; and determine, based on the length of the protection time period, a rate of a signal transmitted to one of the one or more second communication apparatuses by one of the one or more first communication apparatuses.

Abstract: The embodiments deal with files that are already present in a storage when mounting the storage in a file system and files created after the mounting as different groups. (Metadata of) the files is classified. The files are each divided into metadata (index) and a file main body and are recorded on different storage areas, that is, an index partition (IP) and a data partition (DP), associated with each other. This file system is effective in a storage format in which a new file is merely written and an already written file is not updated or deleted (for example, a tape medium used in the LTFS). The embodiments implement a WORM file system by rejecting a request to update or delete a file that is present at mounting as a WORM file and permitting update or deletion of a file that is created after mounting until the storage is unmounted.

Abstract: The embodiments deal with files that are already present in a storage when mounting the storage in a file system and files created after the mounting as different groups. (Metadata of) the files is classified. The files are each divided into metadata (index) and a file main body and are recorded on different storage areas, that is, an index partition (IP) and a data partition (DP), associated with each other. This file system is effective in a storage format in which a new file is merely written and an already written file is not updated or deleted (for example, a tape medium used in the LTFS). The embodiments implement a WORM file system by rejecting a request to update or delete a file that is present at mounting as a WORM file and permitting update or deletion of a file that is created after mounting until the storage is unmounted.

Abstract: A demodulation method of magnetic data may include a first data creating step which creates a preliminary data string for creating the demodulation data on a basis of an interval that is a time interval between peaks of a read signal of an analog-shaped magnetic data, and a second data creating step which creates a demodulation data creating data for creating the demodulation data on a basis of the preliminary data string created in the first data creating step. When a peak of the read signal is not detected for a predetermined time, a pseudo-peak is generated and a pseudo-interval is stored in a data storage section, and steps similar to the first data creating step and the second data creating step are executed, and the pseudo-peak is generated until the demodulation data creating data corresponding to a final interval is created.

Abstract: As for a quadruple light receiving unit, in a case where divided regions of A to D as in a DPD scheme is defined, when binarization signals of light reception signals in regions A to D are set as signals A to D, <1> exclusive OR between the signal A without delay and the signal B with delay, <2> exclusive OR between the signal A with delay and the signal C without delay, <3> exclusive OR between the signal B without delay and the signal D with delay, and exclusive OR between the signal B with delay and the signal D without delay are calculated, and a tracking error signal is obtained on the basis of the calculation of (<1>+<3>)?(<2>+<4>). Thus, the above problem can be solved.

Abstract: According to one embodiment, a multilayer optical recording medium including a substrate, a guide layer group that is provided on the substrate and has guide layers in which positional information in a radial direction is recorded, and a recording layer group that is provided on the substrate and has recording layers in which information can be recorded. In the recording layer group, positional information of the recording layers associated with the positional information recorded in the guide layers and control information of the optical device where reflected light volumes of the laser beams on the guide layers and the recording layers become maximum at the positions in the radial direction are recorded at the positions in the radial direction of the recording layers.

Abstract: The optical disc device includes an optical pickup, a focus-error-signal generation section for generating a focus error signal of the differential astigmatic method by using a parameter and an electric signal outputted from a photodetector in the optical pickup, a control section for controlling the optical pickup to make a focus jump operation, and a parameter value changing section for temporarily changing a value of the parameter to be used to generate a focus error signal of the differential astigmatic method by the focus-error-signal generation section when the focus jump operation is performed by using the focus error signal of the differential astigmatic method.

Abstract: An optical pickup device includes a light source configured to output laser light, an objective lens configured to converge the laser light emitted from the light source onto an optical disc, a sensor lens including a lens surface on which return light reflected by the optical disc is incident and that is also configured to generate an astigmatism in the return light, and a light-receiving element configured to receive the return light which has passed through the sensor lens 40 and to generate a focus error signal based on the received return light. The lens surface includes a first curvature radius in a first direction and a second curvature radius different from the first curvature radius in a second direction that is perpendicular or substantially perpendicular to the first direction.

Abstract: A test device communicates with an external device with a plurality of parameters. The test device includes a setting module, a first determining module, a focus module, and a prompting module. The setting module generates a setting signal for controlling the external device to set values of the parameters. The first determining module controls the focus module to generate a focus instruction to control the external device to execute a focus function, when the test device receives feedback information from the external device, which are generated by the external device after the values of the parameters are completely set. In addition, the focus module receives reflecting information which is generated by the external device after the external device executes the focus function. The prompting module outputs different prompting information based on the received reflecting information.

Abstract: An exemplary optical pickup comprises: a light source with first and second emission points; an optical branching element which branches light emitted from the first emission point into multiple light beams including a first main beam and first sub-beams and which also branches light emitted from the second emission point into multiple light beams including a second main beam and second sub-beams; an optical system which condenses the multiple light beams produced by the optical branching element onto an optical storage medium, thereby making the first and second main beams form a write light beam spot and a read light beam spot, respectively, on a target recording track on the storage medium and making the first and second sub-beams form reference light beam spots and other light beam spots somewhere on the storage medium other than the target recording track.

Abstract: There is provided a position control apparatus including a light radiating/receiving unit that performs radiation of laser light for recording and laser light for adjacent track servo onto an optical disc recording medium through a common objective lens, and receives return light of the laser light for the adjacent track servo and the laser light for the reference surface, a tracking mechanism unit that displaces the objective lens, a reference surface tracking error signal generating unit that generates a reference surface tracking error signal, a reference surface tracking servo control unit that controls the tracking mechanism unit, a recording layer tracking error signal generating unit that generates a recording layer tracking error signal, an integrating unit that integrates the recording layer tracking error signal, an offset providing unit that provides an integration output by the integrating unit, and a feedforward control unit that generates a control signal.

Abstract: A recording device performs recording on an optical disc recording medium having a reference face having a reflection film provided with a position guide, and a recording layer provided at a position of a depth different from that of the reference face and performing information recording by mark forming according to irradiation of light. The recording device includes a light generating and irradiation unit, a recording unit, a tracking mechanism, a first tracking error signal generating unit, a second tracking error signal generating unit, a tracking servo control unit, and a control unit.

Abstract: The optical disc device has a circuit which forms a focus error signal for focus servo control based on reflection light from an optical disc exposed to laser light. Also, the device has a data processing unit which can control by feedback a position to which an objective lens is moved by a focusing actuator based on a focus error signal. In label printing, the data processing unit controls, by feedforward, a position to which the objective lens is moved by the focusing actuator based on control data for label printing. The operation resolution of the focusing actuator in feedforward control is made higher than that in feedback control. Thus, an intended position control accuracy is achieved in feedforward control. For instance, in feedforward control, the gain of the driver circuit for the focusing actuator is switched to a smaller one in comparison to that in feedback control.

Abstract: A recording apparatus includes: a light-emitting/receiving unit which emits a recording beam, an ATS beam, and a position control beam toward an optical disc recording medium via a common object lens; a tracking mechanism which drives the object lens in a tracking direction parallel to a radial direction of the optical disc recording medium; a reference plane-side tracking error signal generation unit which generates a reference plane-side tracking error signal; a reference plane-side tracking servo signal generation unit which generates a reference plane-side tracking servo signal to cancel out a tracking error; a tracking driving unit which drives the tracking mechanism; an ATS-side tracking error signal generation unit which generates an ATS-side tracking error signal; an ATS control signal generation unit which generates an ATS control signal to cancel out a tracking error; and a signal providing unit which provides the ATS control signal to a tracking servo loop.

Abstract: A recording apparatus includes: a light illumination and light sensing unit configured to illuminate an optical disc recording medium including a reference surface having address information recorded and a recording layer, with recording light and light for position control; a recording unit which performs recording on the recording layer; and a control unit which controls, when data instructed to be recorded is to be recorded from an instructed recording start address, the recording unit to perform recording of dummy data on an area adjacent to a front side at least from the recording start address over a range of equal to or greater than the maximum spot deviation amount between an illumination spot of the light for position control and an illumination spot of the recording light and to perform recording of the data instructed to be recorded in succession to a recorded area of the dummy data.

Abstract: [Problem] In a conventional multilayer optical disc, management information needs to be retrieved from the control area of its reference layer to find how many information layers there are in the optical disc. [Means for Solving the Problem] A multilayer optical disc according to the present invention has multiple information layers that are stacked one upon the other. The information layers include at least one layer on which layer number information, indicating its own place in the multiple information layers, and information about the total number of information layers included are both stored.

Abstract: A disc drive includes an optical pickup that emits laser light to a predetermined layer position via an objective lens and detects reflection light of the laser light, a tracking mechanism that drives the objective lens in a tracking direction, a tracking error signal generation unit that generates a tracking error signal, based on a light detecting signal for the reflection light obtained by the optical pickup, a tracking servo control unit that performs a tracking servo control based on the tracking error signal, and a control unit that makes the tracking servo control unit perform tracking servo pull-in on the basis of a frequency measurement result of the tracking error signal and a recording or non-recording determination result based on the light detecting signal.

Abstract: Disclosed are a pickup device assembly and an optical drive system. The assembly may comprise: a laser generator for generating laser beams; an objective lens; and at least one piezoelectric actuator for generating bending moments once applied with voltages, wherein the generated bending moments move the objective lens such that the laser beams are focused by the objective lens and then aim at concentric spiral data tracks of a disc with a strongest reflected signal of the laser beams from the disc.

Abstract: In a small-sized optical pickup device for enabling to obtain a stable servo-signal, as well as, a focus error signal and a tracking error signal, without receiving ill influences of stray lights from other layers, when recording/reproducing a multi-layer optical disc, a reflection light from the multi-layer optical disc is divided into plural numbers of regions by a diffraction grating. And, it is divided into at least four (4) regions, by a division line in the tangential direction of the optical disc and a division line in the radial direction thereof. Light receiving parts, for detecting either one of grating diffraction lights, i.e.

Abstract: An optical recording medium in which recording is performed by a recording device that is configured such that tracking servo control of recording light is performed by irradiating the recording light and ATS light for an adjacent track servo and by an adjacent track servo based on reflected light of the ATS light, wherein while a recording layer in which a mark is formed according to an irradiation of the recording light is included, a mark row is formed in advance by a pitch that is twice a distance between an irradiation spot of the recording light and an irradiation spot of the ATS light or greater in the recording layer.

Abstract: An optical disk device for recording/reproducing information on/from a multi-layer optical disk moves a light focusing point for several layers by one focus jump. The optical disk device includes a controller to detect a level of a focus error signal to change an output level of a focus drive signal, and the controller changes timing to change the output level of the focus drive signal based on the number of layers for the focus jump.

Abstract: A method of generating a 1-beam tracking error signal (TES), an optical pickup device, and an optical disc drive device adopting the method. A light-receiving element receives a single reflection beam and detects an alternating current (AC) component and a direct current (DC) component from each of areas formed on two sides of a data track. A servo unit generates a TES by adding and subtracting the AC component and the DC component.

Abstract: A focus servo control device includes a first detector, first controller, second detector, and second controller. The first detector detects a first focus error signal. The first controller controls the objective lens based on the first focus error signal, so that a focal point of the first laser agrees with the guide layer. The second detector detects a second focus error signal. The second controller changes a relative distance between the focal point of the second laser and the focal point of the first laser, so that the focal point of the second laser agrees with a target recording/reproducing layer.

Abstract: A method for servoing when reading out a recorded holographic disk or recording in a preformatted disk includes detecting a primary signal of a reflected primary beam from a target data track of a target data layer of the disk, wherein the primary beam of radiation has a first wavelength; comparing a power measurement of the primary signal with a threshold value of power; detecting a tracking signal of a reflected tracking beam from a reference layer of the disk in an event that the power measurement of the primary signal is below the threshold value, wherein the tracking beam of radiation has a second wavelength; generating a servo error signal based upon the primary signal or the tracking signal; actuating an optical sub-system based upon either of the primary servo error signal or the tracking servo error signal such that the primary beam focuses on the target data layer.

Abstract: There is a need to prevent a possible erroneous detection of an off-track condition during recording to an optical disk. The above need can be addressed by, for example, determining an off-track condition has occurred when a light spot is located at least half-way from the track being recorded toward another track adjacent the track being recorded, and stopping a recording operation. In another example, the above need can be addressed by determining that off-track has occurred based on an output of a first off-track detector which detects that the light spot is off the track based on a wobble signal, an output of a second off-track detector which detects that the light spot is off the track based on a tracking error signal, and an output of a zero-cross detector which detects that the tracking error signal crosses zero based on an output of the tracking error signal.

Abstract: A focus search is performed on a mounted optical-disc recording medium once the optical-disc recording medium has been mounted in an optical disc device. The type of the mounted optical-disc recording medium is determined on the basis of results of the focus search. When a determination has been made that the mounted optical-disc recording medium is a multilayer optical-disc recording medium having three or more recording layers, a playback power is for an optical-disc recording medium being of a specification identical to the multilayer optical-disc recording medium and having one or two recording layers. A playback operation at the set playback power is used to read optical disc information from the mounted optical-disc recording medium, the optical disc information indicating the type of the mounted optical-disc recording medium.

Abstract: An optical drive apparatus includes: a phase-difference detection-signal generating unit that generates PEDr based on PEROd and PEFOd obtained by delaying a phase-lead output signal indicating a phase lead amount of DA with respect to DB and X that is changed to high at a timing at which NAND of the DA and the DB is changed from high to low and changed to low at a timing at which OR of the DA and the DB is changed from high to low, and generates PADr based on PAROd and PAFOd obtained by delaying a phase-lag output signal indicating a phase lag amount of the DA with respect to the DB by a predetermined time and the X; and a DPD signal generating unit that generates a phase difference signal indicating a phase difference between the DA and the DB based on the PEDr and the PADr, and generates a DPD signal based on the phase difference signal.

Abstract: For obtaining stable servo-signals without receiving ill influences of stray lights from other layers, on both a focus error signal and a tracking error signal, when recording/reproducing a multi-layer optical disc having small gap between layers thereof, a light beam is divided with using a first and a second diffraction gratings. The first diffraction grating is a polarization diffraction grating, and is mounted on an actuator. The second diffraction grating is disposed on a fixed portion. The first diffraction grating has a first region having a center of a light beam and other(s), and among signal lights reflecting from the disc, the light beam entering into the first region is diffracted, and the light beam entering into the second region transmits therethrough. The second diffraction grating transmits the light beam diffracting on the first region of the polarization diffraction grating therethrough, while diffracting the light beam diffracting on the second region.

Abstract: Erroneous data erasure owing to radiation of laser beam with excessive power to the recording layer of the multilayered optical disc upon servo-off while reproducing data of the disc is prevented. When detecting the servo-off based on the amplitude of the tracking error signal or the focus error signal, the laser beam power is reduced to a predetermined minimum value, and the laser beam power value is set again based on the address of the recording medium, which has been obtained later for reproduction. The laser beam power value is changed by applying an offset to the drive current or changing the target value under APC.

Abstract: A method for determining a type of an optical disk includes following steps. A laser beam of a first type is focused on a disk to generate a first optical reflection signal. A first spherical aberration estimate is generated according to the degree of dispersion and strength of the first optical reflection signal. A laser beam of a second type is focused on the disk to generate a second optical reflection signal. A second spherical aberration estimate is generated according to the degree of dispersion and strength of the second optical reflection signal. The type of the disk is determined based on the first spherical aberration estimate and the second spherical aberration estimate.

Abstract: Provided is an optical disk apparatus capable achieving stable focus control or tracking control. A first detector receives reflected light from an object lens optical system, a second detector receives reflected light from a prescribed information layer, a positional deviation determination unit determines positional deviation between a focal point of a light beam and a point where information on the prescribed information layer is recorded or reproduced, on the basis of a signal from the second detector, a stray light determination unit determines a surface stray light component which is reflected light from the surface of an optical disk and is included in the signal from the positional deviation determination unit, on the basis of the signal from the first detector, and a stray light correction unit corrects the signal output from the positional deviation determination unit on the basis of the surface stray light component thus determined.

Abstract: A recording device including a light irradiating and light receiving unit which, in regard to an optical recording medium, which has a reference surface and a recording layer which is formed at a depth position different from the reference surface, where a pit row where intervals of pit formable positions in one circumference is limited to a first interval is formed in the reference surface, and which has a plurality of pit row phases by intervals of the pit formable positions in a pit row formation direction being set in a position which is each deviated by a predetermined second interval in the pit row which are arranged in the radial direction, irradiates a first light as recording light with regard to the recording layer and a second light for obtaining reflected light from the reference surface and which receives reflected light of the second light from the reference surface.

Abstract: The invention provides a method for determining the layer type of a blu-ray disk. First, a laser beam is focused on a target layer of the blu-ray disk. Reflection of the laser beam from the target layer is the detected to obtain a reflection signal. The reflection signal is then processed to generate a first tracking error signal and a second tracking error signal. Magnitudes of the first tracking error signal and the second tracking error signal are then measured. The magnitude of the second tracking error signal is then subtracted from the magnitude of the first tracking error signal to obtain a difference value. Finally, the layer type of the target layer is determined by comparing the difference value with the first predetermined threshold.

Abstract: Optical density is enhanced on print media darkened by exposure to electromagnetic radiation. The print media is divided into at least one track. A defocused spot of electromagnetic radiation is created within the track. The defocused spot of electromagnetic radiation darkens the print media within the track.

Abstract: A three-dimensional optical memory device comprises an optical disc positioning system, two sources of radiation with wavelengths ?1 and ?2, a focusing system, an illumination system, focusing system positioning means, a spectrum splitter, an optical sensor, and a control unit. The radiation source with wavelength ?2 is an array of laser diodes, which optical axes are parallel and lie in the same plane. The illumination system comprises: a cylindrical lens positioned so that the generatrix of its cylindrical surface is parallel to the plane of the p-n junctions of the laser diodes; a focusing lens; and a stabilizing circuit comprising a beam splitter situated between the focusing lens and the cylindrical lens, a second optical sensor optically coupled to the focusing lens via the beam splitter, and a stabilizer coupled to the focusing lens, wherein the stabilizer and the second optical sensor are electrically connected to the control unit.

Abstract: A low-cost technique to improve the performance of optical disk drives is presented. An algorithm is used to decouple electro-mechanical actuators thus compensating for inaccuracies in the control of the actuators. A similar method can be used to decouple the position sensors. Prior art methods treated cross-coupling between focus, tracking and sled control loops as noise and therefore increased the bandwidth of the system, also increasing the cost of the optical disk drive. The present disclosure actively decouples the control loops using a software algorithm to provide better performing optical disk drives. The cross-coupling effects are measured, a decoupling matrix is determined, and the output of the control laws is modified so as to decouple the actuators.

Abstract: Disclosed is an optical information reproducing apparatus that has a light path difference between two lights easily adjusted, has a high effect on the amplification of a signal, and detects an optical information signal of an interfering type. The optical information reproducing apparatus splits a luminous flux emitted from a laser source into a first luminous flux as a signal light and a second luminous flux as a reference light not collected on an optical information recoding medium, makes the signal light optically interfere with the reference light in a state in which the signal light and the reference light are different from each other in a phase relationship to thereby produce interfering lights, and detects the interfering lights.

Abstract: In one embodiment, the optical pickup device includes: a light source that emits a light beam; a diffractive element that diffracts the light beam and generates a zero-order and ±first-order diffracted light beams; an objective lens that converges the diffracted light beams onto the same track on the storage medium; and a photodetector that receives the diffracted light beams reflected from the storage medium. If a distance from a light beam spot left by the zero-order diffracted light beam on the track to light beam spots left by the ±first-order diffracted light beams on that track is d [?m], the scanning linear velocity of the storage medium is v [m/s], and a time it takes for a phase-change material of the storage medium that has once been melted by the zero-order diffracted light beam to solidify is T [?s], vT?d is satisfied.

Abstract: An optical drive device includes first and second light sources, an objective lens configured to receive a first light emitted from the first light source and a second light emitted from the second light source and to irradiate both the first light and the second light to an optical disc recording medium, a first focus mechanism configured to drive the objective lens in a focus direction, a second focus mechanism configured to change collimation of the second light incident to the objective lens and changing the focusing position of the second light independently of the first light, a first focus servo control unit configured to drive the first focus mechanism, an error signal subtraction unit configured to subtract the first focus error signal from a second focus error signal, and a second focus servo control unit configured to drive the second focus mechanism.

Abstract: An optical disc apparatus includes an optical pickup, a signal generation section which generates a total reflection signal and a focus error signal, and a servo control section which controls optical pickup. The optical disc apparatus further includes a main control section which binarizes the track cross signal by using a predetermined threshold value and, by using the binarized track cross signal, checks the tracing state of a track. The main control section controls the servo control section to check, by tracing one turn of the track of an optical disc, whether or not a tracking servo deviation occurs. When a tracking servo deviation occurs during the tracing, the main control section controls the servo control section to make the check once again. When, in the check made once again, a tracking servo deviation is found to occur again, the main control section increases the threshold value used in binarization.

Abstract: An optical recording/reproduction method and device that can perform control for optimizing the amount of spherical aberration in a multilayered optical disc in a short period of time. When the objective lens is displaced in the focusing direction, the amplitude value of the focusing error signal detected just after leaving the focal position of a given first recording layer and the amplitude value of the focusing error signal detected just before passing through the focal position of a given second recording layer other than the first recording layer are measured with a particular spherical aberration, the amplitude ratio of amplitude values is calculated, the difference between spherical aberration and the optimal spherical aberration for the second recording layer is approximated as a function of the amplitude ratio, the optimal spherical aberration is calculated on the basis of this approximation, and the spherical aberration is set.

Abstract: An optical disc device includes: a diffraction element receiving as input reflected light from an optical disc recording medium, including a first diffraction area formed in a position where light in the center portion of incident light flux is diffracted, a second diffraction area formed so as to be in contact with an outer edge of the first diffraction area, and a third diffraction area formed so as to be in contact with an outer edge of the second diffraction area; and a light receiving/signal generating unit which generates a focus error signal and a lens error signal based on light diffracted at the third diffraction area; with the light receiving/signal generating unit receiving light diffracted at the second diffraction area, and generating the focus error signal based on the received light signal thereof and a received light signal obtained by receiving light diffracted at the third diffraction area.

Abstract: An optical pickup device includes an astigmatism element which imparts astigmatism to laser light reflected on a disc, a spectral element which changes propagating directions of four light fluxes obtained by dividing a light flux of the laser light reflected on the disc to disperse the four light fluxes from each other, and a photodetector having a sensor group which receives the four light fluxes. The optical pickup device is further provided with a memory which holds a correction value for suppressing a DC component in a tracking error signal resulting from a positional displacement of the spectral element. The tracking error signal is corrected by the correction value to thereby suppress the DC component.

Abstract: There is provided an optical disk drive that pursues power saving and simultaneously assures data recording quality. A servo processor of the optical disk drive has a low frequency equalizer, a high frequency equalizer, a limiter, and an adder. A limit voltage value of the limiter is set by means of a control command from a system controller. The limit voltage value is set so as to become greater during a data recording period than in a data regeneration period. An output from the adder is supplied as a tracking drive signal to a tracking actuator or as a focus drive signal to a focus actuator.

Abstract: Efficient recording and reading are achieved in an optical recording medium including servo layers and recording and reading layers. The optical recording medium includes: a first servo layer having a projection and a depression for tracking control that are formed in a first spiral direction; a second servo layer having a projection and a depression for tracking control that are formed in a second spiral direction opposite to the first spiral direction; and a plurality of recording and reading layers having a flat structure with no projection and depression for tracking control. Information is recorded on each of the plurality of recording and reading layers while tracking control is performed using the first servo layer or the second servo layer.

Abstract: An optical disc drive includes a disc holder, a pickup head, a focus servo, an S-curve identifying unit, a first counter, a second counter, a judging unit, a disc identifying unit, and a system controller. The optical disc drive can detect whether a disc exhibits vertical deviation. Upon detection, the optical disc drive restricts the maximum speed of data reading and writing. The judging unit determines whether the disc exhibits vertical deviation based on a comparison result of the number of the one or more S curves with a first preset value.

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