Abstract: An optical reproducing method for an optical medium including a disk-like substrate having a groove structure along tracks divided into a plurality of units. Each of the units includes a dropout portion of the groove structure along the track which is a non-groove portion. The groove structure is wobbled in a fixed cycle in a radial direction. When the wobble is formed in the circumferential direction of the track, the dropout portion is formed so that a phase of the wobble is continued with a phase of the wobble of the groove structure within another unit adjacent to the dropout portion. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by using a signal obtained by the reflected beam.

Abstract: An information recording apparatus for recording information to an optical recording medium including, a disk-like substrate, a spiral or concentric-shaped groove structure along a track formed on a disk-like substrate, the groove structure being wobbled in a radial direction of the medium, the track being divided into a plurality of recording units in the track direction by at least one radial boundary line, at least two adjacent recording units in the radial direction of the medium comprise one zone, and the groove structure included in the respective recording units within one zone having substantially same number of wobbling. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: An optical reproducing method for an optical medium including a disk-like substrate, a spiral or concentric-shaped groove structure along a track formed on the disk-like substrate, the groove structure being wobbled in a radial direction of the optical medium, the track being divided into a plurality of units in the track direction by at least one radial boundary line, at least two adjacent units in the radial direction of the optical medium comprise one zone, and the groove structure included in the respective units within one zone having substantially a same number of wobbling. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by sing a signal obtained by the reflected beam.

Abstract: An optical reproducing method for reproducing information on an optical medium, including a disk-like substrate, a spiral or concentric-shaped groove structure along tracks formed on the disk-like substrate with each of the tracks being divided into a plurality of units including a dropout portion in a circumferential direction of the groove structure. The dropout portion is a non-groove portion. The groove structure is formed with a wobble in a fixed cycled in a radial direction with the fixed cycle of the wobble continuing in the circumferential direction along the track. Each length of the units is an integer multiple of the cycle of the wobble. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by using a signal obtained by the reflected beam.

Abstract: An information recording apparatus for recording information to an optical recording medium, including a disk-like substrate, a spiral or concentric-shaped groove structure along tracks formed on the disk-like substrate, each of the tracks being divided into a plurality of recording units, each of the recording units including a dropout portion in a circumferential direction of the groove structure, the dropout portion being a non-groove portion, the groove structure is formed with a wobble in a fixed cycle in a radial direction, the fixed cycle of the wobble continuing in the circumferential direction along the track; and each length of the recording units is an integer multiple of the cycle of the wobble. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: Optical disk and recording/reproducing device for the optical disk are disclosed, the optical disk including alternating spirals of ridged land track and grooved groove track having substantially the same widths for recording data in high density on both of the tracks, each of the land track and the groove track having a plurality of sectors, each sector having a first region and a second data recording region, the first region having synchronization marks and sector address marks wobbled with an amplitude about a half of the width of the land track and the groove track from respective track centers for plurality of times, for example two times; and the recording/reproducing device having means for detecting the land track and the groove track.

Abstract: To increase the vibration resistance of an optical disk device with respect to vibrations in the focus direction. More specifically, an optical disk device is provided with a multiplication means for generating a focus vibration component FC from the focus error signal FE, a multiplication means for generating a tracking vibration component TC from the tracking error signal TE, an adder for adding the focus vibration components FC and TC, and a low-pass filter for extracting the vibration component VC from the added results. Thus, the vibration component VC is extracted considering not only vibrations in the tracking direction but also vibrations in the focus direction, so that vibrations acting on the device can be more accurately detected, and vibration resistance is increased.

Abstract: An optical disk device for writing data onto an optical disk having an undulating track comprises an optical pickup for illuminating laser light of a writing power and laser light of a replaying power onto an optical disk and for converting return light from the optical disk into an electrical signal, a filter for extracting a wobble component contained in the return light signal when the laser of a writing power is illuminated, a processor for detecting the direction of track deviation based on the phase of the wobble component, and an actuator for driving the optical pickup in the width direction of the track based on the direction of the track deviation in order to control the tracking. Because the phase of the wobble component differs for a case when a light spot is deviated radially inward and for a case when a light spot is deviated radially outward, the direction of the track deviation can be detected based on the phase of the wobble component and the tracking can be controlled during data writing.

Abstract: The invention provides: an optical recording medium having the changeability and compatibility of media and a large capacity in three dimensions; an optical pickup apparatus for the same and a control apparatus for the same.

Abstract: An information recording apparatus for recording information to an optical recording medium including a disk-like substrate having a plurality of tracks and associated with a plurality of grooves. A plurality of zones are provided on the disk-like substrate and each zone includes at least two tracks. Each track is divided into a plurality of recording units of substantially the same length. The grooves are wobbled in the radial direction and a length of each recording unit is an integer multiple of a cycle of the wobble which is the same for the different zones. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: An optical reproducing method for an optical medium including a disk-like substrate having a plurality of tracks associated with a plurality of grooves. A plurality of zones are provided with each zone including at least two tracks. Radially adjacent units of a respective zone are delimited by a pair of radial lines joined to form a central angle at an apex proximate to a center of the disk-like substrate with each unit of a respective zone being delimited by the same central angle and units of different zones being delimited by different central angles. The grooves are wobbled in the radial direction and the length is the same for the different zones. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by using a signal obtained by the reflected beam.

Abstract: The invention provides an apparatus and method which allows playback of both of a first optical disc wherein the opposite side faces of a groove formed thereon are wobbled at a first predetermined frequency and a second optical disc wherein one of the opposite side faces of a groove formed thereon is wobbled at a second frequency shorter than the first predetermined frequency while the other face of the groove is formed as a flat face. In the apparatus and method, it is discriminated whether an object optical disc of playback is the first optical disc or the second optical disc, and various servo systems are switched based on a result of the discrimination.

Abstract: Disclosed herein is a disc drive apparatus for recording and reproducing data to and from an optical disc-like storage medium. The apparatus includes a wobble signal generating element for generating a wobble signal representative of information about the wobble detected based on reflected light from the optical disc-like storage medium, and a land/groove detecting element for determining, when the light beam fails to trace a specific track correctly on the storage medium, whether the emitted light beam is located on a land field or in a groove field. The land/groove detecting element further outputs a land/groove detection signal having a waveform inverted depending on whether the light beam is located on the land field or in the groove field.

Abstract: An optical recording medium for accurately deriving the address information or the disc rotation control information despite narrow track pitch and for recording signals to a high density, and a method and apparatus for recording and/or reproducing such optical recording medium. The optical recording medium has a wobbled groove and pits formed at a pre-set interval in an area between turns of the wobbled groove. The recording/reproducing method includes controlling rotation of the optical recording medium by a wobbled signal from the groove and detecting the position on the optical recording medium of a recording signal by pit signals detected from the pits. The recording/reproducing apparatus includes a detection device for detecting the wobbled signal from the groove and a detection device for detecting pit signals from the pits.

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: An information record disc is provided with: a track formed on a disc surface, on which record information to be reproduced is recorded or to be recorded; and a wobble formed on the track such that a phase of the wobble is changed at a plurality of locations on the track and that positional information indicative of a position on the disc surface is recorded as a change in the phase of the wobble. The record information is arranged at a predetermined arrangement cycle, and includes a synchronization signal to attain a synchronization when the record information is recorded or reproduced. An interval at which the phase of the wobble is changed on the track is equal to N times (N is an integer equal to or greater than 1) of the predetermined arrangement cycle of the synchronization signal when the record information is recorded on the track.

Abstract: A method for compensating track offset in an optical disk drive is provided, which achieves complete compensation of the track offset and than reduces the compensation time for the track offset. (a) An optical disk with wobbled grooves is provided, the wobbled grooves being used for generating a wobbling signal with a wobbling period. (b) A beat-inducing signal is recorded on the disk. The period of she beat-inducing signal has a specific relationship with the wobbling period in such a way that a beat signal is induced by the beat-inducing signal and the wobbling signal. (c) A tracking-error signal is generated using a push-pull method by optically reading the wobbled grooves of the disk and the beat-inducing signal recorded on the disk. The tracking-error signal contains a bear signal induced by the beat-inducing signal and the wobbling signal. (d) Track offset is compensated based on the beat signal contained in she tracking-error signal.

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: A tracking servo system with a feed-forward control loop is presented. Periodic variations in a control signal can be detected. These periodic variations can be added into the control signal to form a new control signal so that on subsequent cycles the control signal does not include the periodic variations.

Abstract: An information recording apparatus for recording information to an optical recording medium including, a disk-like substrate, a spiral or concentric-shaped groove structure along a track formed on a disk-like substrate, the groove structure being wobbled in a radial direction of the optical recording medium, the track being divided into a plurality of recording units in the track direction by at least one radial boundary line, at least two adjacent recording units in the radius direction of the optical recording medium comprise one zone, the optical recording medium including a plurality of zones, and the groove structure included in the adjacent recording units within any zone having substantially same number of wobbling. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: An exposure system and method for an original disk for an information recording medium. A rotating device is provided for driving an original disk and an optical head irradiates a beam for exposure on the original disk. A scanner performs exposure to light in a shape of a track by scanning the beam in a radial direction of the original disk and a controller controls a width of the scanning by the scanner. The controller controls the scanner so that borders on both sides of the track are shifted in phase from each other with a phase difference.

Abstract: In an optical disk, serial data representative of positional information is preformatted by using a groove, and this groove is wobbled. When this preformatted optical disk is applied to an optical disk apparatus, a laser beam irradiation position can be controlled in high precision. A method for manufacturing this preformatted optical disk is disclosed.

Abstract: An optical reproducing method for an optical medium including a disk-like substrate having a groove structure along tracks divided into a plurality of units. Each of the units includes a blank portion of the groove structure along the track which is a non-groove portion. The groove structure is wobbled in a fixed cycle in a radial direction. When the wobble is formed on the blank portion and the blank portion is formed so that a phase of the wobble is formed on the groove structure, a phase of the wobble on the blank portion is continued with a phase of the wobble of the groove structure within another unit adjacent to the blank portion. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by using a signal obtained by the reflected beam.

Abstract: An optical reproducing method for an optical medium including a disk-like substrate, a spiral or concentric-shaped groove structure along a track formed on the disk-like substrate, the groove structure being wobbled in a radial direction of the optical medium, the track being divided into a plurality of units in the track direction by at least one radial boundary line, at least two adjacent units in the radial direction of the optical medium comprise one zone, and the groove structure included in the respective units within one zone having substantially a same number of wobbling. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by sing a signal obtained by the reflected beam.

Abstract: An information recording apparatus for recording information to an optical recording medium including a disk-like substrate, a spiral or concentric-shaped groove structure along tracks formed on the disk-like substrate, each of the tracks being divided into a plurality of recording units, each of the recording units including a blank portion of the groove structure along the track in a circumferential direction of the track, the blank portion being a non-groove portion and the groove structure being wobbled in a fixed cycle in a radial direction, the fixed cycle of the wobble continuing in the circumferential direction along the track. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: An optical reproducing method for an optical medium, including a disk-like substrate, a spiral or concentric-shape groove structure along a track formed on the disk-like substrate, the groove structure being wobbled in a radial direction of the optical medium, the track being divided into a plurality of units in the track direction by at least one radial boundary line and at least two adjacent units in the radial direction of the medium comprise one zone. The optical medium includes a plurality of zones, and the groove structure included in the adjacent units within any zone have substantially a same number of wobbling. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by using a signal obtained by the reflected beam.

Abstract: An information recording apparatus for recording information to an optical recording medium, including a disk-like substrate, a spiral or concentric-shaped groove structure along tracks formed on the disk-like substrate, each of the tracks being divided into a plurality of recording units, each of the recording units including a blank portion in a circumferential direction of the groove structure, the blank portion being a non-groove portion, the groove structure is formed with a wobble in a fixed cycle in a radial direction, the fixed cycle of the wobble continuing in the circumferential direction along the track; and each length of the recording units is an integer multiple of the cycle of the wobble. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: An information recording apparatus for recording information to an optical recording medium including a disk-like substrate having a plurality of tracks and associated with a plurality of grooves. A plurality of zones are provided on the disk-like substrate and each zone includes at least two tracks. Each track is divided into a plurality of recording units of substantially the same length. The grooves are wobbled in the radial direction and a length of each recording unit is an integer multiple of a cycle of the wobble which is the same for the different zones. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: An optical reproducing method for an optical medium, including a disk-like substrate, a spiral or concentric-shaped groove structure along the tracks formed on the disk-like substrate with each of the tracks being divided into a plurality of units including a blank portion in a circumferential direction of the groove structure. The blank portion is a non-groove portion. The groove structure is formed with a wobble in a fixed cycled in a radial direction with the fixed cycle of the wobble continuing in the circumferential direction along the track. Each length of the units is an integer multiple of the cycle of the wobble. The method includes irradiating an optical spot on the optical medium, detecting a reflected beam from the optical medium, and reproducing information on the optical medium by using a signal obtained by the reflected beam.

Abstract: An information recording apparatus for recording information to an optical recording medium including, a disk-like substrate, a spiral or concentric-shaped groove structure along a track formed on a disk-like substrate, the groove structure being wobbled in a radial direction of the medium, the track being divided into a plurality of recording units in the track direction by at least one radial boundary line, at least two adjacent recording units in the radial direction of the medium comprise one zone, and the groove structure included in the respective recording units within one zone having substantially same number of wobbling. The information recording apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Abstract: In performing CLV readout, a target frequency is corrected based on current and target numbers of revolutions of a disk motor during a seek operation, thereby controlling the frequency of a read clock signal at a value approximately equal to the corrected target frequency. In performing CAV readout on the other hand, the frequency of the read clock signal is approximately equalized with a data read frequency at a seek destination. By performing these frequency control operations, data reading can be started quickly enough after the seek operation is finished. In reading out information from a recordable disk with wobbling tracks on a data portion, frequency control is performed using a wobble signal with respect to an unrecorded data portion, and phase locking control is performed using a data signal with respect to an address portion. In this manner, an address can be read out constantly.

Abstract: A wobble detecting apparatus for an information recording and/or reproducing for an optical disk, includes a wobble detecting unit for detecting a wobble on the basis of a signal from a light receiving element which receives light reflected from the optical disk; an offset voltage generating unit for generating an offset voltage; an adder unit for adding said offset voltage to a control signal to an actuator for the optical disk; an actuator switch for on/off controlling a control signal to said actuator; and a control unit for turning on said actuator for wobble detection to decide whether or not the wobble has been detected by said wobble detecting unit, and if the wobble has not been detected, causing said offset voltage generating unit to generate a positive or negative prescribed voltage to decide further whether or not the wobble has been detected by said wobble detecting unit. In this configuration, the wobble can be detected with high accuracy.

Abstract: A device for demodulating position information that is recorded as track wobbling in a record medium by a BPSK scheme includes a carrier-wave-generation circuit which derives a carrier wave from a wobbling signal obtained from the record medium, a phase-adjustment circuit which generates a phase-comparison signal having a 90° phase difference relative to the carrier wave, a multiplier which multiplies the wobbling signal and the phase-comparison signal to supply a product signal, and a detection circuit which detects a phase error of the carrier wave introduced by the carrier-wave-generation circuit by detecting the phase error between the wobbling signal and the phase-comparison signal based on the product signal.

Abstract: The present invention provides an exposure apparatus of an optical disc master plate for exposing a photoresist master plate and writing-in a DVD-R format, and a method of exposing an optical disc master plate. The exposure apparatus of the optical disc master plate can cause both the wobble signal and the land pre-pit signal to precisely synchronize with each other and to output the synchronized signals by use of a formatter. The formatter can facilitate the design of a separation element for electrically separating an analog circuit and a digital circuit from each other and a circumferential circuit thereof. The formatter of the optical disc exposing apparatus operates on the basis of the predetermined basic clock signal Fclk. The formatter is provided with a wobble signal generating circuit which generates a wobble signal and a land pre-pit signal generating circuit which operates on the basis of the same basic clock signal Fclk and generates a land pre-pit signal.

Abstract: An optical information recording medium, an optical information recording method and an optical information recording apparatus are able to prevent one laser beam of two laser beams from affecting the other laser beam by an offset. In an optical disc in which a groove whose one-side is wobbled or modulated only is sequentially formed by turning on or off one laser beam of two laser beams in accordance with a modulation signal and desired data is recorded by the groove, since the groove is formed by wobbling the one laser beam in such a manner that the one laser beam may not affect the other laser beam, a light intensity of the one laser beam is not added to a light intensity of the other laser beam, which is not wobbled by a wobbled amount so that the other-side of groove may be protected from the influence of the offset.

Abstract: An apparatus for applying an optical signal to a surface and collecting the light leaving the surface in response to the application of the optical signal. The optical signal and the collected light traverse an optical fiber having an end proximate to the surface which delivers light to the surface with the aid of a lens that couples the optical signal to the surface, collects the light emitted by the surface, and couples collected light into the optical fiber. A detector measures the intensity of light delivered into the optical fiber and generates a detection signal indicative of the measured intensity as a function of time. A set of actuators dither the position of the lens relative to the proximate end of the fiber. Each actuator operates at a different dither frequency and moves the lens relative to fiber along a different axis.

Abstract: An optical disc and associated recording/reproducing apparatus is described which creates and reads wobbled tracks on the optical disc. Wobbled tracks are formed in correspondence to a wobble signal which is phase modulated with address information. Phase modulation is used to convert the address information to the wobble signal. The carrier to noise ratio (C/N) of the address information is good, and it is possible to shorten the wobbling amplitude of the tracks while maintaining addressing capabilities. It is thus possible to arrange the track pitch in a high density, and increase the recording capacity of the optical disc.

Abstract: A daylight operable, scan-free, laser spot locating device for locating a laser spot pointed at an object.

Abstract: An apparatus and method for reproducing information stored in a fluorescent multilayer information carrier. The apparatus utilizes auto-focusing and auto-framing techniques when reading the information to enable parallel reading from uniformly moving carrier. To avoid discontinuity in motion, an actuator with an objective lens performs periodic motion following a specific moving information page and, after the end of reading of this page, returns back to follow the next page.

Abstract: On an optical disc, an information record track wobbled in accordance with a wobbling signal is formed and pre-pits are formed at an predetermined interval on a guide track adjacent to the information record track. A pre-pit signal based on the pre-pit is detected by a pre-pit detecting apparatus.

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: An optical record carrier has parallel tracks for recording user information in a pattern of optically detectable marks, the tracks being provided with control information. The tracks are grouped in pairs of neighboring tracks. The control information in both tracks of a pair is identical and the control information in tracks of different pairs is different. The identity of the control information reduces the effect of crosstalk on neighboring tracks.

Abstract: A novel recording medium capable of realizing high density, reliability in a recording/reproducing operation and facilitating the process which is performed by a drive apparatus is provided. An amplitude amount of wobbling of a track is made to be 10 nm to 15 nm and a track pitch of the track is made 0.74 &mgr;m to 0.82 &mgr;m. The determined values enable large-capacity recording to be realized and the recording/reproducing performance to be prevented from being deteriorated. As administration information, recommended information for a recording/reproducing operation at an inner peripheral position and an outer peripheral position is recorded. The size of data in a linking section is made to be the same as the sector for constituting a data block.

Abstract: An optical disc and associated recording/reproducing apparatus is described which creates and reads wobbled tracks on the optical disc. Wobbled tracks are formed in correspondence to a wobble signal which is phase modulated with address information. Phase modulation is used to convert the address information to the wobble signal. The carrier to noise ratio (C/N) of the address information is good, and it is possible to shorten the wobbling amplitude of the tracks while maintaining addressing capabilities. It is thus possible to arrange the track pitch in a high density, and increase the recording capacity of the optical disc.

Abstract: The invention provides an apparatus and method which allows playback of both of a first optical disc wherein the opposite side faces of a groove formed thereon are wobbled at a first predetermined frequency and a second optical disc wherein one of the opposite side faces of a groove formed thereon is wobbled at a second frequency shorter than the first predetermined frequency while the other face of the groove is formed as a flat face. In the apparatus and method, it is discriminated whether an object optical disc of playback is the first optical disc or the second optical disc, and various servo systems are switched based on a result of the discrimination.

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: A disk type recording medium has spiral or concentric grooves that are divided into a plurality of zones 1, 2 and 3 in the radial direction of the disk. Physical address information and sector boundary information are recorded by groove wobbling. Records of data are arranged on grooves with reference to sector boundary information on the condition that a wobble frequency of physical address information obtainable when rotating the disk at a constant angular velocity is constant within a unit zone and increases with each change of zones from inner to outer peripheral zone on the disk.

Abstract: An optical disc and associated recording/reproducing apparatus is described which creates and reads wobbled tracks on the optical disc. Wobbled tracks are formed in correspondence to a wobble signal which is phase modulated with address information. Phase modulation is used to convert the address information to the wobble signal. The carrier to noise ratio (C/N) of the address information is good, and it is possible to shorten the wobbling amplitude of the tracks while maintaining addressing capabilities. It is thus possible to arrange the track pitch in a high density, and increase the recording capacity of the optical disc.

Abstract: A tracking control apparatus for effectively compensating for a direct current offset of a tracking error signal when a recording medium having wobbled land and groove tracks is accessed. In the apparatus, a light beam is irradiated onto signal tracks of a recording medium including successively formed wobbled areas or intermittently formed wobbled areas, and a reflective light is detected by a photo detector divided into a plurality of areas. Signals detected by two areas of the photo detector symmetrically divided on a basis of the direction of the track are subtracted to generate a difference signal. Also, signals detected by the two area of the photo detector are added to generate a sum signal. A tracking offset compensating signal is generated based on the difference signal and the sum signal. The tracking error signal is compensated by the tracking offset compensating signal, so that a light beam can accurately trace the signal tracks.

Abstract: A magneto-optical disk 1 has a track, wherein one of the sidewalls (sidewall 4) of a groove 2 is wobbled by a wobble signal, and is provided with a notch 5 in the track having a different frequency from the wobble signal. The absolute position of the magneto-optical disk 1 is detected with a sample bit stored by the notch 5 of the track, and an information bit is stored with a recording/reproducing clock synchronizing with that position. By forming the notch 5 in this manner, information can always be recorded at the same information bit position, regardless of how many times information is rewritten. Therefore, a gap area and a buffer area, which have conventionally been essential, are not needed on the optical disk. Consequently, it is possible to use a recording area effectively.