Abstract: An adaptive motion controller for driving a servo motor. The adaptive motion controller has an amplifier including a voltage command which can be set at a voltage at which the amplifier will be operated, a frequency selector which can be set at a frequency at which the amplifier will be operated, a power supply having a current feedback, and a control for driving the servo motor in a test mode wherein the voltage command is set at a selected voltage, and the frequency selector is sequentially set with a series of different frequencies. The servo motor is operated at each frequency, and the frequency of the series of frequencies that has the lowest current feedback is determined and the frequency selector is set at that frequency when the amplifier is operated to drive the servo motor.

Abstract: An optical disk provided with a land region and a groove region that are formed on a substrate, the land region and groove region being used as a recording track that is the medium of the recording/playback of information signal, and a pre-pit region that is formed at the boundary part of neighboring land region and groove region and is disposed every other boundary part, the pre-pit region including specific information. Characteristically, the specific information's in neighboring pre-pit regions are not aligned in the radius direction of the optical disk.

Abstract: A method for track locking in an optical disc drive. The optical disc drive includes a pick-up device for reading data from a plurality of tracks of a compact disc. The compact disc includes a plurality of adjacent track periods, each track period including an on-track period and an off-track period, and the on-track period including only one track. The optical disc drive further includes a driving device for driving the pickup device, and a location detecting device for detecting a location of the pick-up device and producing a tracking error signal.

Abstract: A system and method for controlling operation of a disc drive for optical media. The optical media includes a pitted premastered area that cannot be overwritten and a grooved user-writeable area that can be overwritten. The disc drive determines the position of an actuator arm in relation to the grooved and pitted areas, and enters a physical sector address (PSA) idle state, where no attempts to read physical address sectors (PSAs) are made when tracking or focus are not active. The drive transitions from the PSA idle state to a PSA enable state when tracking becomes active, and to a PSA locked state where PSAs can be read when both focus and tracking are active. The drive also re-attempts to acquire a PSA when the PSA cannot be read within a predetermined time period. The re-attempt includes toggling between control system settings appropriate for pits and settings appropriate for grooves.

Abstract: A CLV (Constant Linear Velocity) optical disc which can record the information with a constant linear velocity, wherein plural lines of specified tracks exist in a predetermined data area, a railroad length of the specified tracks is integer multiple of the length of a sector, the length of the sector on the specified tracks is 2×&pgr;×N times a track pitch, the number N being a positive integral number, and head positions of the specified tracks are lined up on a predetermined radius line A-A′ at equal track intervals. The tracks including a head sector on the predetermined data area are the specified tracks. In such structure, calculation of the conversion between the information number and the number of the tracks can be simple, the unevenness of the disc format manufactured by use of different optical disc master board (plate) can be eliminated, and high-speed accessing operations can be performed.

Abstract: A near-field optical head which reproduces, with high S/N, information recorded with extreme density and is compact in structure. On an electrode (2) is formed a recording medium (3) that emits a light by applying an electric field. Brought into proximity to a recording medium (3) is a near-field optical head (101) having a slider (31) formed with an inverted cone formed hole such that an apex thereof is rendered as a microscopic aperture (6). A microscopic electrode (5) is formed on a side surface (32) of the inverted cone formed hole. An electric field (9) is applied only to a microscopic region to cause light emission. It is possible at the aperture (6) to detect a light emitted only by the microscopic region.

Abstract: An information recording medium has a recording track, a plurality of address areas which are formed on the recording track and record address information, and mark areas, the number of which is larger than the number of address areas, and which are formed at predetermined intervals and include mark information. Each address area records address information by means of pits, and each mark area records mark information by means of wobbles as a part of a track boundary.

Abstract: The invention provides an optical disk medium having a recording spiral formed by connecting groove tracks and land tracks alternately, and permitting detection of a connecting point between a groove track and a land track reliably is provided, and a method of tracking the optical disk medium and an optical disk drive apparatus for driving the optical disk medium. One part of an identification signal area is shifted by a predetermined distance in one radial direction from the center of a groove, while another part of the identification signal area is shifted by the same distance in the opposite radial direction from the center of the groove. A land/groove polarity of a sector is determined by the polarity of a tracking error signal and the order of the polarities during reproduction of an identification signal.

Abstract: An optical disk apparatus comprising a device for moving a focal point of a light beam for reproducing information recorded on an information face of a disk, in the direction perpendicular to the information face; a device for detecting a reflected light from the disk; and a device for discriminating whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate. In this apparatus, a maximum value AS1Lmax of an output signal from the reflected light detecting device and a maximum value ENVmax of an amplitude of an information reproducing signal are detected while driving the focal point moving device so that the focal point passes through the information face, and the discriminating device discriminates whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate, on the basis of the ratio of ENVmax to AS1Lmax.

Abstract: An optical positioning circuit includes an electro-optic positioner which positions an optical beam on an optical medium to read/write patterns of data on the optical medium, and a driver circuit, such as an inductive capacitive circuit, which drives the electro-optic positioner. The optical medium has a dimension along which the optical medium is moved, and each of the micropatterns extends along less than (e.g., {fraction (1/10)}th of) that dimension.

Abstract: A light beam from a light source is introduced to a grating element of a pickup device to create zero order diffracted light, ±first order diffracted light, and ±second order diffracted light. An irradiation system focuses the zero order, ±first order and ±second order diffracted light onto tracks extending on a recording surface of an optical recording medium to form spots. A spot of the zero order diffracted light is formed on a target track, spots of the ±second order diffracted light are formed on tracks adjacent to the target track, and spots of the ±first order diffracted light are formed midway between the spots of the ±zero order and ±second order diffracted light. An optical system guides returning light reflected from the spots to an optical detector. The optical detector has independent light-receiving elements for receiving the returning light.

Abstract: A recording and/or reproducing apparatus for an optical disc in which the loop gain variation in tracking servo control can be suppressed to cause the illuminated laser light to follow correctly the recording track center. An optical disc recording/reproducing device 1 detects a traversing signal generated when the laser light traverses a track at the time of tracking servo pull-in and sets the amplification degree of a GCA 4 so that the push-pull signals will be at a predetermined level. The optical disc recording/reproducing device 1 holds the amplitude of the wobbling signals on memory as an initial setting value. On starting the recording or reproduction, the optical disc recording/reproducing device 1 monitors the amplitudes of the wobbling signals during the recording or reproduction to compare the amplitudes to the initial setting value.

Abstract: Optical disk recording device includes a beam projection section for projecting a light beam onto a write-once optical disk, and a photodetector having two light receiving surfaces divided in a radial direction of the optical disk for detecting reflected light from the optical disk, and wobble-signal reproduction circuitry for reproducing a wobble signal on the basis of reflected light detection signals output from the two light receiving surfaces of the photodetector. The wobble-signal reproduction circuitry includes peak-holding circuits for, when the optical disk device is in a reproduction mode, detecting and holding respective upper envelopes of the two light detection signals from the photodetector. The wobble-signal reproduction circuitry also includes holding circuits for, when the optical disk device is in a recording mode, detecting respective lower envelopes of the two light detection signals from the photodetector.

Abstract: An optical head device includes a light source for emitting at least one of a coherent beam and a quasi-monochromatic beam; a collection optical system for collecting the beam to an information memory medium having a track which has at least one mark and at least one space; a light detector having a plurality of detection areas for receiving the beam reflected by the information memory medium and outputting a signal in accordance with a light amount of the beam received; and a tracking error signal generator for receiving the signals output from the light detector and generating a tracking error signal based on the signals. The tracking error signal generator reduces a difference between a first signal amplitude and a second signal amplitude. The first signal amplitude is an absolute value of a difference between first and second signal levels. The second signal amplitude is an absolute value of a difference between the first and third signal levels.

Abstract: The present invention relates to a device for reading from and/or writing to an optical recording medium, which has a data track having a first area, which is provided for markings arranged centerd with respect to the center of the data track, and at least one further area, which is provided for markings arranged laterally offset with regard to the center of the data track. Corresponding devices have detection means, track error detector, signal shaping means, and correction signal generation means. The object of the present invention is to propose a device of the generic type in which an accurate correction signal for the track error signal can be obtained without a high outlay, and also a method for generating a corresponding correction signal. This object is achieved according to the invention by the fact that the signal shaping means has an averaging unit, whose output is connected to an input of the correction signal generation means.

Abstract: An optical information recording and reproducing apparatus for recording and reproducing an information signal on/from both concave portions and convex portions of guide grooves formed on a recording medium is disclosed.

Abstract: A method and apparatus for optical disc discrimination, which can discriminate immediately and correctly the types of a plurality of optical discs having different record densities of recorded information from each other.

Abstract: A light spot detects a focus offset amount based on an amount of variation of a focus error signal when a light spot passes a boundary between a land section and a groove section adjacent to the land section on an optical disk. Specifically, an amount of variations in the focus error signal at a center of a land section at a time the light spot passes the boundary between the land and the groove adjacent to the land is detected as a focus offset amount, and an amount of variation in the focus error signal at a center of the groove section is detected as a focus offset amount for the groove sections, thereby providing an optical information recording/reproducing device which permits recording/reproducing information on and from a tracking area of an optical disk under just-in-focus conditions without increasing a cost of the device nor being affected by an error due to changes over time or variations in optical disks.

Abstract: This invention relates to methods of using an optical disc reader to detect an analyte of interest that is associated with an optical disc assembly. The method includes the steps of: (1) providing the optical disc to the optical disc reader; (2) directing at least one beam of electromagnetic radiation to the optical disc and scanning the beam over the optical disc; (3) acquiring radiation returned from or transmitted through the optical disc using a detector of the optical disc reader; (4) generating from the acquired radiation at least a signal which is indicative of the presence of the analyte; and (5) generating from the acquired radiation signals which enable the optical disc reader to track operational structures impressed or encoded in the optical disc.

Abstract: A high-density optical disk includes lands and grooves which are alternately formed to different depths around tracks of the optical disk and on each of the lands and grooves user information marks are formed. A mirror region is formed at a region of a change between a land and a groove, to guide a beam to sequentially access from a track to an adjacent next track, wherein the land and the groove are formed next to the mirror region, and a change between the land and the groove can be recognized by the detection of the mirror region.

Abstract: This invention is applicable to an apparatus using an optical pickup to reproduce information recorded on an optical recording medium. By enabling the automatic setting of reproducing conditions applicable to a mounted optical recording medium so that a plurality of types of optical recording media can be compatibly mounted, the present invention enables recorded information to be reliably reproduced even if the recording medium has a low recording density.

Abstract: A disc-like record carrier (1) has control information recorded. The control information comprises diameter information which is indicative of the diameter of the record carrier. An information recording and/or reading apparatus involves a drive structure for rotatingly driving the disc-like record carrier. The apparatus includes a control unit which adapts the loop gain of a control loop for controlling the number of revolutions per minute of the record carrier in dependence on the control information recorded on the record carrier.

Abstract: An optical disk apparatus comprising a light source for emitting a light beam, an optical system for focusing the light beam to form a beam spot on the optical disk, a tracking unit for detecting the light reflected from the optical disk to generate a tracking error signal from the light by a differential phase detection method, and move the beam spot in accordance with the tracking error signal, and an information-readout section for reading out information from the optical disk. To achieve readout compatibility between a high-definition DVD and a DVD-ROM, a predetermined delay is given relatively to first and second signals obtained from two pairs of regions arranged in two crossing diagonals of a quadrant photodetector, thereby shifting the beam spot from the centerline of the pit stream in the radial direction of a DVD-ROM, in order to read out information from the DVD-ROM.

Abstract: A signal generation method capable of generating a cross track signal having a predetermined phase difference from a tracking error signal even in a land and groove recording method in which a land width and a groove width are made equal, wherein a main spot is detected at a split photodetector, a first side spot is detected at a split photodetector, and a second side spot is detected at a split photodetector; a first error is calculated as an error of the optical disk in a radial direction from four detection signals detected at the photodetector, a second error is calculated as the error of two detection signals of the photodetector, a third error is calculated as the error of two detection signals of the third photodetector, and the sum of the second and third errors is subtracted from the first error to calculate a tracking error signal; and a difference between the second error and the third error is found to calculate a cross track signal having a phase shifted by 90° from the tracking error signal

Abstract: A defined level comparator compares a track error signal with each of a predetermined upper limit level and a predetermined lower limit level so as to generate two comparison signals. A logic unit ANDs two comparison signals so as to obtain a track pull-in enabling signal. A header component removal arithmetic unit removes a header component from the track pull-in enabling signal in accordance with a header area signal. A track polarity inverter outputs a land/groove detection signal in which a polarity of a signal level is inverted every timing at which a signal level of the track pull-in enabling signal is in a track pull-in enabling state. A track polarity correcting and determining unit compares a polarity signal held by a sampling holder with the land/groove detection signal in the header area.

Abstract: An optical information recording/reproducing apparatus for optically recording/reproducing information by irradiating a track on a recording medium with a light comprises: a detecting circuit, a tracking error signal producing circuit, and a tracking control circuit. The detecting circuit selectively detects a circular area having a diameter smaller than a diameter of a light beam reflected from the recording medium and obtains an output signal corresponding to the detected circular area. The tracking error signal producing circuit produces, from the output signal of the detecting circuit, a tracking error signal indicating a shift in a position of a light beam irradiated on the recording medium in a track width direction. The tracking control circuit controls an irradiation position of a light beam irradiated on the recording medium in the track width direction based on the tracking error signal.

Abstract: A header region detecting method and apparatus and recording/reproducing method and apparatus using thereof for an optical recording medium is disclosed. According to the method and apparatus, a tracking error signal is detected by detecting an RF signal from an optical reflected signal inputted from the optical recording medium and obtaining a phase difference of optical reflected signals in a radial direction based on the RF signal. Then, first and second header detection signals are generated by slicing the detected tracking error signal with predetermined upper and lower slice levels, and a header region is detected by logically combining the first and second header detection signals, so that the header region can be accurately and stably detected even in a free running or traverse operation.

Abstract: A system and method are provided for processing signals in a magneto-optical computer memory device to detect mispositioning of a head with respect to a track centerline. A light beam is scanned over a first and a second set of radially offset optically-detectable position marks formed in the rotating medium surface. A detector receives the reflected light beam and responsively generates a position signal having a plurality of pulses corresponding to the position marks. The position signal is then passed through a differentiator circuit. The differentiated position signal may then be applied to low pass filter and resonator circuits, and is subsequently conveyed to a finite time integrator for rectification and detection of the areas of the pulses associated with the first and second set of position marks. Mispositioning of the head is detected by comparing the pulse areas of the first and second set of position marks.

Abstract: An optical disk apparatus comprising a device for moving a focal point of a light beam for reproducing information recorded on an information face of a disk, in the direction perpendicular to the information face; a device for detecting a reflected light from the disk; and a device for discriminating whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate. In this apparatus, a maximum value AS1Lmax of an output signal from the reflected light detecting device and a maximum value ENVmax of an amplitude of an information reproducing signal are detected while driving the focal point moving device so that the focal point passes through the information face, and the discriminating device discriminates whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate, on the basis of the ratio of ENVmax to AS1Lmax.

Abstract: A magneto-optical record medium and a reproducing apparatus for the same allow data reproduction having good characteristics by a simple structure. The magneto-optical record medium includes a plurality of first grooves (3) each having sidewalls, at least one of which is wobbled in accordance with address information; an address mark (21) formed by changing a width of a land located between second grooves connected to the first grooves; and third grooves wobbled cyclically, formed in a data portion magnetically storing data and connected to the second grooves. The reproducing apparatus reproduces the data from the magneto-optical record medium.

Abstract: An optical recording/reproducing apparatus having drive means for rotating a recording medium, an optical head for applying light to the recording medium being rotated by the drive means, thereby to record data signals on the recording medium or reproducing data from the recording medium, and a signal-processing circuit for processing a signal detected by the optical head. The optical head comprises a light source for emitting light, an objective lens, and signal detecting means. The objective lens has a numerical aperture NA, where 0.5<NA≦0.6. The apparatus can reliably record data on and reproduce data from high-density optical recording media that have different track pitches.

Abstract: A method for generating a land/groove (L/G) switching signal from pits on a land/groove (POLG) type disc and an apparatus therefor. In the method for generating an L/G switching signal from pits on a POLG type disc having tracks with wobbles, in which header information is recorded in sectors of each track, the header information including physical identification data (PID) and a peak header and a bottom header distinguished by envelopes of the peak header signal and the bottom header signal and both the peak and bottom header signals having phases according to lands or grooves, the phases of the peak header signal and the bottom header signal are compared to determine a track switching point and the sequence of sectors is determined using the physical identification data of the disc.

Abstract: Method for controlling track jump in an optical recording medium for writing/reading data on/from land/groove tracks having depths different from each other in a direction of a beam incident, including the steps of (1) adjusting an offset of a servo error signal generated by using an optical signal reflected at the optical recording medium consistent to the land track, (2) adjusting an offset of a servo error signal generated by using an optical signal reflected at the optical recording medium consistent to the groove track, (3) selecting the servo error signal having the offset adjusted consistent to the land/groove track in the step (1) or (2) in response to a land/groove switching signal, (4) receiving a track jump command, and determining the track jump command of being an ‘N’(‘N’ is an odd numeral) track jump command, and (5) if the track jump command is determined of being an ‘N’(‘N’ is an odd numeral) track jump command in the step (4), after switching th

Abstract: On an optical disk, a string of a plurality of pits having two different depths is formed. Quantity of light reflected from the pit string is detected by a photoreceptor element, and based on the detected quantity of reflected light, a pit depth detecting unit detects depth of each pit. Based on the detected quantity of reflected light, a servo signal generating unit generates a tracking servo signal. An output control unit supplies the generated tracking servo signal when a pit of such depth that is to be reproduced is tracked, and holds and supplies an immediately preceding tracking servo signal when a pit of different depth is being tracked, based on the result of detection by the pit depth detecting unit.

Abstract: An optical record carrier comprises substantially parallel tracks being divided into recording units having an address area (23,24), adjacent address areas of adjacent tracks (43,44) comprising shared address marks (48). Shared address marks (47,48) are positioned in between adjacent tracks and arranged in sharing portions (40,41) of the address area, each sharing portion sharing address marks only to one side. The address area also comprises a free portion (39) which is free from shared address marks, which free portion is aligned with a sharing portion (42) of an adjacent address area. This is advantageous for reducing crosstalk in the address read signal. The sequence of the free and sharing portions within an address area differs so as to be matching in adjacent address areas.

Abstract: An optical head device includes a light source for emitting light; a collection optical system for collecting the light emitted by the light source to an information memory medium including at least one of a track having a mark or a space selectively arranged, and a track having a prescribed groove; a light detector having a plurality of detection areas for receiving the light reflected by the information memory medium and outputting a signal in accordance with a light amount of the light received; a division element for dividing the light reflected by the information memory medium and allowing the light to be received by the light detector; a switch element for receiving a first signal and a second signal, which are respectively obtained in accordance with the reflected light incident on a first prescribed area and a second prescribed area of the division element and outputting either one of the first signal or the second signal, the first and second prescribed areas being obtained by dividing the division e

Abstract: A recording medium that is adapted to maximize the recording capacity and to simplify the configuration of an information recording/reproducing apparatus including a pickup. In the medium, a different type of wobbling signals are preformatted in each of the adjacent land and groove signal tracks. A same-phase wobbling signal provided by wobbling each side of the respective land and groove signal tracks in the same phase and a different-phase wobbling signal provided by wobbling each side of the respective land and groove signal tracks in a different phase are used as the different type of wobbling signals. The physical positions of all the land and groove signal tracks are indicated by the same-phase wobbling signal.

Abstract: In this invention, track address information is recorded at a portion different from a recording track along user data by a land pre-pit, wobbled groove interrupt, wobble stop, or a projecting portion formed at a land/groove boundary. With the address information, the track position can be detected at least once per data length of the minimum recording unit. To increase the recording frequency of tracking error detection information, instead of recording the absolute address value of a track, information representing a position in tracks divided into groups is recorded.

Abstract: The present invention provides a focusing and tracking servo circuit used in an optical disk device that can maintain stability of the focusing and tracking servo at a time of recording or reproduction. This focusing and tracking servo circuit includes: a first storage unit that stores a parameter corresponding to light beam power at a time of recording; a second storage unit that stores a parameter corresponding to light beam power at a time of reproduction; and a selector unit that selects from the parameters stored in the first and second storage units upon switching between recording and reproduction, and sets the selected parameters in a detector unit. With this structure, the parameters can be instantly switched at the same time as the switching between recording and reproduction, and the stability of the focusing and tracking servo can be maintained.

Abstract: An optical disk includes at least one region along a radial direction, and a plurality of tracks provided in the at least one region. The at least one region contains address regions radially positioned on the plurality of tracks. In the address regions, data which is common between two adjacent tracks of the plurality of tracks is recorded at positions aligned along the same radial direction on the two adjacent tracks, and data which is not common between the two adjacent tracks is recorded at positions along different radial directions on the two adjacent tracks.

Abstract: An optical disc drive control apparatus according to the present invention comprises a disc drive into or from which various optical discs are inserted or ejected. The system includes a first memory for storing various players that play back various optical discs, a second memory for storing a table in which combinations of various information recording mediums and various players corresponding to these mediums are written, and a disc manager, which comprises a unit for sensing the type of an optical disc inserted into the disc drive, a unit for referring to the table in the second memory and deriving the type of a player corresponding to the sensed type of optical disc, as well as the type of data stored on the disk, and a unit for driving one of the various players stored in the first memory which is of the type derived by the deriving means and causing the player to play back the optical disc.

Abstract: A bias voltage controlling apparatus controls a bias voltage for a focus servo control to control a position of a focal point of a light beam, which is irradiated onto an information record surface of an information record medium, in a direction perpendicular to the information record surface. The bias voltage controlling apparatus is provided with: a distinguishing device for distinguishing a type of the information record medium; and a controlling device for optimally controlling the bias voltage on the basis of the type of the information record medium distinguished by the distinguishing device.

Abstract: A system and method for generating position error signals within a magneto-optical computer memory device whose track pitch is close to the full width half maximum width of the laser spot, the narrow track being typical of data stored on magnetic super resolution media. The magneto-optical computer memory device comprises a storage media for storing information, position marks embossed on the storage media, a head device coupled to the storage media for sensing the position marks to generate position error signals, and a correction device coupled to the head device to access the position error signals and responsively position the head device to correctly sense the stored information.

Abstract: In recording on an optical disk, tracking control is performed using tracking error signals detected during an OFF period and a rear time segment within an ON period of a recording pulse signal. The time segment for detecting the tracking error signal within the recording pulse ON period is variably controlled in accordance with recording conditions such as a disk type and recording speed. This control can effectively prevent a tendency of pits being formed off the center line of a track toward the inner circumference of the optical disk due to the influence of residual heat from an adjoining inner track, thereby allowing pits to be formed accurately on and along the track center line.

Abstract: Disclosed is a method of tracking control for an optical disc recorder and reproducer, which includes the steps of detecting a land/groove switching position, storing tracking error signals for a predetermined time if the land/groove switching position is detected, obtaining a mean value of the stored tracking error signals, and judging whether the mean value is larger than a predetermined permissible tracking level, and if it is judged that the mean value is larger than the predetermined tracking level, determining a direction of a track center, correcting the track center, and compensating for a DC offset.

Abstract: Apparatus (10) and method (100) for inscribing a clock pattern (14), detecting the clock pattern (14) optically, and using the clock pattern (14) to write a sevo pattern in an information storage unit (12), such as a computer hard drive. The clock pattern (14) is inscribed using a marking system (64), which may include a laser (66) or employ other, even non-optical, methods. The clock pattern (14) is inscribable into various locations on a disk platter (16) inside the storage unit (12), including many outside the media surface (26) conventionally used for such in data storage units. While the disk platter (16) is rotating, the clock pattern (14) is on detected using an detection subsystem (46), if desired through a transparent window (36) in a hermetically sealed housing (34) of the storage unit (12), for use in writing the servo pattern with less sector-inconsistency error and off-track error.

Abstract: A tracking control method and apparatus for providing a stable tracking control for an optical recording medium of land/groove recording system. Wobbling signals are detected from each side of a track irradiated with a laser light beam in land and groove tracks formed on the optical recording medium in a wobbled shape. The wobbling signals are added and subtracted or multiplied to generate a tracking error signal to be used for the tracking control. The tracking error signal has a positive or negative voltage level in accordance with whether a light beam is inclined toward the inner circumference side or the outer circumference side on the basis of the center lines of the land and groove tracks.

Abstract: An optical record carrier is described comprising a track for carrying data encoded in optical marks. A parameter of the track has a periodic variation for generating a varying signal when scanning the track, for example a variation of the center of a pre-groove usually called wobble. The track further comprises reference elements, e.g. headers, interrupting the periodic variation. The phase of the periodic variation after the reference elements is indicative of a property of the record carrier for controlling the scanning of the record carrier in dependence of said property. In particular the phase may indicate whether or not the bottom of the pre-groove is closer to the scanning beam entry side of the disc. Further a scanning device is described comprising a detector for detecting said phase based on the varying signal. The device adapts its scanning control means to the indicated property.

Abstract: Drive systems for moving the optics sled in a laser servowriting system used to provide a servo pattern on the media of a magnetic data storage disk are disclosed. The drive systems include multiple actuators located about the centroidal axis of the optics sled. Moments induced by the multiple actuators acting on the optics sled can be balanced by varying the forces applied to the optics sled by the actuators. Also disclosed are control systems and methods for balancing the forces provided by the actuators by varying the gains on the signals driving the actuators.

Abstract: An optical recording medium having a number of adjacent tracks for storing digital optical information is provided, such as an optical disc. The tracks extend in a tangential direction, for example, surrounding the center of the disc. Each track is separated by a pitch amount in a radial direction, for example, outward from the center across the tracks. The tracks each have a servo field comprising one tracking mark located on the track in one of four discrete tangential positions A, B, C and D on the track. There is a mark in one of these four positions for every four adjacent tracks on the media. The position of the tracking marks repeat in the same sequence for every four adjacent tracks. For any four such adjacent tracks, the tracks having marks at positions A and B are separated by one track, and tracks having marks at positions C and D are separated by one track.