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

Abstract: A tracking error signal detector includes: a photodetector (103) for detecting reflected light from an optical recording medium having a servo area provided with a first wobble mark and a second wobble mark; an amplifier (104) for producing a summation signal of the reflected light; a sampling portion (105) for sampling the summation signal; a first arithmetic portion (106) for calculating an extremum of the summation signal in the vicinity of reproduction timing for each of the first and second wobble marks from the sampling values so as to produce first and second extremums; and a second arithmetic portion (107) for producing a tracking error signal that corresponds to a difference between the first and second extremum. The tracking error signal detector can produce a high-accuracy tracking error signal even if sampling is performed with an asynchronous clock relative to the summation signal.

Abstract: A recording information reproducing apparatus is disclosed for performing a searching operation. The recording information reproducing apparatus according to the invention is for reproducing recording information from a recording disc on which information data has been divided and recorded into a plurality of concentric zones. The apparatus selects a suitable one of a tracking servo by a sampled servo system and a tracking servo by a continuous servo system in accordance with a zone for reading information data.

Abstract: In an optical disk drive having the structure of rotating an optical disk under the alternative control of CAV or CLV, when the optical disk is rotated under the CLV control, the loop gains for at least one of the focus servo system and the tracking servo system for controlling the operation of the pickup of the optical disk drive are adjusted based on angular velocity detected by an angular velocity detector which is also used for rotating the optical disk under the CAV control, and, when the optical disk is rotated under the CAV control, the loop gains for at least one of the focus servo system and the tracking servo system are adjusted based on linear velocity detected by a linear velocity detector which is also used for rotating the optical disk under CLV control. The above structure enables the effective saving of electricity and cost in the optical disk drive.

Abstract: A servo error detector usable in an optical disk system is provided. An envelope detecting unit (24) detects the top envelopes and bottom envelopes of RF signals SA−SH, and top envelope signals SAtop−SHtop and bottom envelope signals SAbtm−SHbtm that represent the top envelope waveforms and bottom envelope waveforms of RF signals output from an optical detector. An analog/digital conversion unit (26) converts analog top envelope signals SAtop−SHtop and bottom envelope signals SAbtm−SHbtm corresponding to all input RF signals SA−SH to digital top envelope signals QAtop−QHtop and bottom envelope signals QAbtm−QHbtm, respectively. A digital operation unit (28) performs digital operation treatment for digital top envelope signals QAtop−QHtop and bottom envelope signals QAbtm−QHbtm to generate various servo error signals.

Abstract: The present invention relates to an optical disk apparatus which performs information recording or reproduction into/from an optical disk, and provides an optical disk apparatus which makes the amount of optical pickup movement performed before adjustment of a track error signal suited and enables reduction of a start-up time. When a track error signal is subjected to adjustment, it is previously detected in a signal amplitude detecting circuit 17 whether an optical pickup 1 is located in an area where a required track on an optical disk medium 2 exists or not, and a micro processing unit 6 executes the procedure which uses only the necessary but minimum moving time, even when the optical pickup is required to be moved.

Abstract: In an initial operation of an optical disc apparatus for reading out information data recorded in the innermost data recording area on the optical disc, a main processor judges whether periods between adjoining two pits are normal or not from signals outputted from an optical pickup. When the periods of the pits are normal, a light beam emitted from the optical pickup is on the present data recording track, and the information data is read out from the optical disc. Alternatively, when the periods of the pits are abnormal, the optical pickup is moved inwardly with sensing the periods of the pits and judges whether the periods are normal or not. When the periods of the pits become normal, the light beam is precisely tracked on the present data recording track, and reproduces the information data from the optical disc.

Abstract: An information recording apparatus is provided, which can control over the power of light beams emitted from a light source and various types of servo control with higher accuracy. A laser beam is emitted from a semiconductor laser to write information onto an optical disc. A detection signal indicative of the power of the laser beam output from a light-receiving device is sampled and held with a sample and hold circuit via an I-V converter at a timing delayed by the time corresponding to the delay time of the I-V converter. A tracking error generation circuit and a focus error generation circuit generate a tracking error signal and a focus error signal, respectively, on the basis of a detection signal having information about tracking error and focus error and output from a light-receiving device. Sample and hold circuits sample and hold the tracking error signal and the focus error signal at a timing delayed by the time corresponding to the delay time of each of the generation circuits, respectively.

Abstract: An optical disk has a servo area composed of a synchronous pit and guard pits provided on each track and a data area composed of data pits. In recording and reproducing digital data on and from the optical disk, a beam spot of laser beam is traced on centerlines between adjacent two tracks. In the tracking of this case, a reflected light is changed due to a tracking error with an arrangement of the synchronous pit and the guard pits on an odd track and an arrangement of the synchronous pit and the guard pits on an even track. A tracking servo is made by comparing output levels of the reflected light changed before and after this synchronous pit.

Abstract: An apparatus for scanning optical recording media, having a detection unit with a photodetector and a reference voltage associated therewith, an evaluation unit having an input, and a connection disposed between the detection unit and the input of the evaluation unit. In such scanning apparatuses, voltage coupling is usually provided between the detection unit and the input of the evaluation unit. Such a coupling arrangement has the disadvantage that the two units must operate in approximately the same voltage range. In the scanning apparatus according to the present invention it is not necessary for the detection unit and the evaluation unit to operate in substantially the same voltage range. According to the present invention, the evaluation unit has a controller, that holds the input of the connection at the value of a reference voltage of the detection unit.

Abstract: An optical disc drive includes: an optical head with an actuator and a photodetector; a tracking driver outputting a drive signal to the actuator; a first tracking error signal generator for generating a first tracking error signal based on an output signal of the photodetector; first and second lens position control sections for respectively outputting first and second lens position control signals to the tracking driver; and a selector for selectively supplying the first tracking error signal to the first or second lens position control section according to a moving velocity of the optical head during a seek operation. The first lens position control signal is obtained by extracting signal components, of which the frequencies are equal to or lower than a predetermined frequency, from the first tracking error signal. The second lens position control signal is obtained by extracting DC components of the first tracking error signal at on-track points thereof.

Abstract: A rotation control circuit comprising, a pickup controller configured to amplify an error signal detected by a pickup from an optical disk, and to generate both a low-frequency component in the error signal and a pickup control signal so as to control the pickup, a memory controller configured to generate a memory address control signal in synchronization with a frequency generator signal provided by a disk motor, a memory circuit configured to store the low-frequency component by using the memory address control signal at a specified timing, a compensation signal adder configured to add the low-frequency component to the pickup control signal at another specified timing, and a system controller configured to control operational timing of the memory controller and the compensation signal adder.

Abstract: An optical recording medium driving apparatus which can obtain a tracking error signal necessary for an accurate track count. An optical recording medium driving apparatus for recording and/or reproducing data in/from an optical recording medium, where information can be recorded in plural tracks formed by land portions and groove portions provided between the land portions, based on a light emitted to the tracks. The apparatus includes a detector for detecting a position of the emitted light, a peak-hold circuit for holding a peak of a position detected signal outputted from the detector so as to output the position detected signal, a bottom-hold circuit for holding a bottom of the position detected signal so as to output the position detected signal, and a switching circuit for switching signals based on the output signals from the peak-hold circuit and bottom-hold circuit so as to output either signal.

Abstract: A learning control unit is provided between a feedback calculating unit and a driving unit. When a period for one medium rotation period is assumed to be TL, an unknown drive current function Irepeat(t) which repeats for a period of time from a start time t=0 for one medium rotation period to an end time t=TL is obtained by a learning algorithm as an approximated function I{circumflex over ( )}repeat(t) that is approximately presumed by a set of the heights Ci of N rectangular functions having interval numbers i=0˜ (N−1) whose time widths are obtained by dividing the period for one medium rotation period into N intervals. After the learning, a learning control signal I{circumflex over ( )}repeat is outputted synchronously with the medium rotation and a feed-forward control is performed.

Abstract: A recording and playback apparatus comprises, a drive unit configured to rotate an optical recording medium including a recording track, a recording and playback unit configured to irradiate a light beam on the recording track, and to perform recording and playback of an information detected a reflected light beam by an upside photo detection area and a downside photo detection area bisected in a tangential direction of the recording track, and a recording and playback controller configured to generate a position tracking signal based on the reflected light beam detected by the upside photo detection area and the downside photo detection area, and to compensate a level of the position tracking signal when the position tracking signal and a record mark on the recording track are detected.

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 tracking error signal generating apparatus having an inexpensive and simple configuration for a disc-shaped information recording medium driven in conformity with a given system, such as the CAV system, CLV system or ZCLV system, is provided.

Abstract: A process and device are provided for controlling an incident optical beam for reading a track of a dynamic medium, e.g. a digital disc, having information stored therein. The beam reflected by the disc is picked up by an optical pickup having several photodetectors and the positioning error of the beam with respect to the track is determined from elementary signals delivered respectively by the photodetectors and from an overall signal containing the information and delivered by the pickup.

Abstract: A digital servo controller generates a control signal from an analog observation signal using an output equation, state equation or a transfer function, and performs high precision servo-control with an inexpensive configuration. In a digital servo which executes an output equation yd[k]=C·x[k]+D·ud[k] and state equation x[k+1]=A·x[k]+B·ud[k]. The digital servo comprises a digital processor which outputs the second term D·ud[k] of the output equation by an analog circuit, and outputs the first term C·x[k] earlier for Ts/2. The digital servo also comprises a digital processor which executes the direct term of the output equation at period Ts/N (N is a 2 or higher natural number), which is 1/N of the basic operation period Ts, and updates the first term with the same delay time as the average delay time Ts/(2N) of the direct term.

Abstract: Apparatus and method for scanning a surface. An optical system generates a light beam to illuminate a surface. A carrier supports the surface for reciprocating motion with respect to the light beam to form one axis of a raster. A propulsion system moves the carrier at a substantially constant speed and a position sensor provides an output signal representing the surface position with respect to the light beam. A control system responsive to the output signal modulates a sample period reciprocally to carrier speed to achieve substantially constant scan length per sample and to control data acquisition timing.

Abstract: A method of detecting a servo error, an apparatus therefor, a disk which maintains quantity of a servo error signal, a method of controlling a servo of an apparatus for recording data on and reproducing data from a disk, a method of detecting the tracking error, and a method of detecting tilt error of the apparatus.

Abstract: An optical information recording device for recording information utilizing holography comprises a recording medium moving means for moving a recording medium, a follow-up control circuit for controlling an irradiation position, and a signal converting means for obtaining a reproduction signal from an address servo-control area including a light source for radiating an information beam and a reference beam onto the recording medium. The follow-up control circuit is composed of a binary-coding means for binary-coding the reproduction signal and a follow-up signal circuit, and detects the travel amount of the irradiation position moving means and generates, according to the travel amount detected and for a specific time during which the irradiation position of the information beam and the reference beam follows, an irradiation position control signal for controlling an irradiation position moving in one information recording area through an output terminal of a gain control amplifier.

Abstract: In an optical disc recording method conducted by irradiating an optical beam for recording onto an optical disc to form pits on the lands thereof, when a recording speed is lower than a predetermined recording speed, the sampling/holding operation of a light receiving signal for detecting a wobble signal is performed during a power-off period of a recording signal. On the other hand, when the recording speed is higher than the predetermined recording speed, the sampling/holding operation is performed during a power-on period of the recording signal. Therefore, a wobble signal can be detected at all times at good C/N ratio independently of the speed recording.

Abstract: A learning control unit is provided between a feedback calculating unit and a driving unit. When a period for one medium rotation period is assumed to be TL, an unknown drive current function Irepeat(t) which repeats for a period of time from a start time t=0 for one medium rotation period to an end time t=TL is obtained by a learning algorithm as an approximated function Iˆ repeat(t) that is approximately presumed by a set of the heights Ci of N rectangular functions having interval numbers i=0˜(N−1) whose time widths are obtained by dividing the period for one medium rotation period into N intervals. After the learning, a learning control signal Iˆ repeat is outputted synchronously with the medium rotation and a feed-forward control is performed.

Abstract: An optical disk (2) includes a plurality of layers in a three-dimensional direction (i.e., “thickness direction” or “depth direction”) thereof. A plurality of recording surfaces are respectively formed on the layers, the recording surfaces each has data recording tracks (16) extending along a peripheral direction of the optical disk (2). Sample servo marks (11) each has at least two mark portions (11a, 11b). The two mark portions (11a, 11b) are arranged in a zig-zag manner to be shifted in the thickness direction of the optical disk (2) such that the two mark portions (11a, 11b) interpose one of the data recording tracks (16).

Abstract: To correct for run-out in an optical disk drive, a run-out reducing gain factor is selected. A run-out correction signal is produced by applying the run-out reducing gain factor to a center error signal. A servo drive signal is refined with the run-out correction signal to produce an adjusted servo drive signal. A tracking actuator is driven with the adjusted servo drive signal.

Abstract: An optical disc cutting apparatus capable of suppressing an unnecessary deflection component and unnecessary light intensity variation component and manufacturing a optical disc suitable for a high definition, high precision and high density optical disc.

Abstract: An optical information recording medium according to the present invention includes at least one groove track and at least one land track allowing information to be recorded on or reproduced from the groove track and the land track, the groove track and the land track adjoining each other. The optical information recording medium further includes: an identification signal region including a pre-pit array, the pre-pit array indicating identification information concerning the groove track and the land track; and a servo control region disposed ahead of the identification signal region along the groove track and the land track, the servo control region including wobble pits positioned so as to shift to opposite sides of a center line of either the groove track or the land track.

Abstract: An optical disc apparatus in which the inclination of an optical axis of laser light relative to an optical disc is adjusted. When data is recorded, laser light is irradiated at recording power in mark periods and irradiated at reproducing power or erasing power in space periods. Immediately after the beginning of the mark periods, no pits are ye formed even though recording power is applied and the amount of reflected light has a level corresponding to the inclination of the optical axis of laser light relative to the optical disc without influence exerted by the pits. Also in the space period, the amount of reflected light has a level corresponding to the inclination of the optical axis of laser light relative to the optical disc. By sampling the reflected light signal at the instant following to the beginning of the mark period or space periods, the inclination is adjusted so as to maximize the sampled signal level.

Abstract: In a focus control for following a focus position of light beam to be radiated to an optical disk to an optical disk surface, the technique is for shorten the memory length in the learning controller. The learning controller is provided to a focus feedback control system and updates the memory comprised of N numbers of memory cells with a shorter sample period than a time obtained by dividing the time required for one rotation of the disk by N numbers and outputs the learning results in the memory with the shorter sample period.

Abstract: An optical disc 1 has spiral grooves GR formed on a data recording surface thereof and in which information is written to, and read from, both a land between the grooves and the grooves as tracks. Each track has a plurality of address areas AR1 and user areas AR2 formed thereon, and each of the address areas AR1 has embossed pits for a groove header GRH and embossed pits for a land header LH. Each of the address areas AR1 has provided in a leading part thereof a header mark area HM formed from a mirror finished surface. That is, this optical disc is of an on-land/in-groove recording type. An offset taking place in a tracking error signal and focus error signal is removed to accurately control the tracking and focus of an optical head.

Abstract: A storage medium is provided having a relatively large number of relatively small servo sectors. The storage medium includes a plurality of tracks. Each track includes a plurality of data sectors and a plurality of servo sectors. Each servo sector includes a plurality of servo marks and a synchronization gap. A plurality of first servo sectors includes a synchronization gap having a first length and a plurality of second servo sectors includes a synchronization gap having a second length. The first length is different from the second length, whereby, an unsynchronized reading device may recognize the longer synchronization gap and synchronize to the servo sector and a synchronized reading device may remain synchronized by recognizing the shorter synchronization gap.

Abstract: A method of pre-processing sampled data prior to estimating the peak amplitude of a pulse includes averaging of two adjacent sample values. Pre-processing makes the peak amplitude estimation less sensitive to the sampling phase relative to the peak position and consequently allows for the use of a lower sampling period relative to the full-width-half-maximum pulse width for a given peak estimation accuracy. The method incorporates a step in which a base line offset signal is subtracted from an estimated peak value, and multiplying the consequent pulse peak amplitude estimate by a predetermined constant in order to compensate for a systematic change in a final peak amplitude estimate. The multiplying constant may have a value derived from estimated peak values of other detected pulses in order to compensate for a systematic change in the peak amplitude estimate.

Abstract: A control device for a focusing system of a compact disk (CD) reader is provided. The control device uses fuzzy logic incorporated to the audio data processing system of the CD reader which is adapted to detect and segregate a light beam reflected by the surface of the compact disk from an incident light beam to the surface. The fuzzy logic control device receives a focus error signal and a derivative of the focus error. It then calculates, using appropriate membership functions, output signals to provide to a focusing servo-system of the CD reader to adjust the distance of the focal plane from the light beam detecting circuitry.

Abstract: A tracking error signal compensation device for removing an offset of a tracking error signal to be used for a tracking servo control includes: a low pass filter that extracts a direct current component and a low frequency component whose frequency is lower than a reference frequency from the tracking error signal, and generates a detection signal including the extracted direct current component and the extracted low frequency component; a determination device that determines whether or not a frequency of the tracking error signal is lower than a reference frequency; a holding device that generates a hold signal by holding the detection signal generated by the low pass filter, when the determination device determines that the frequency of the tracking error signal is lower than the reference signal; a detection device that detects the offset of the tracking error signal by using the detection signal and the hold signal; and a removing device that removes the offset detected by the detection device from the tr

Abstract: A prepit detecting apparatus which uses an optical recording medium having information recording tracks on which information is recorded and guide tracks each of which guides a light beam to the information recording track and on which prepits for saving pre-information are formed such that the light beam is applied to the information track of the optical recording medium, the prepit detecting apparatus comprising: light receiving means divided into a first divided light receiving portion and a second divided light receiving portion divided along an optically parallel division line in a direction of tangent of the information tracks and arranged to receive reflected light of the light beam with which the optical recording medium has been irradiated; and a difference calculator for calculating the difference between a first read signal output from the first divided light receiving portion and a second read signal output from the second divided light receiving portion so that the prepit is detected in response

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: A tracking error detection apparatus includes a phase error detection unit for detecting a phase error of an output signal according to the amount of reflected light that is obtained when a light beam is applied to an information recording medium; a low-band pass unit for performing band restriction to obtain a tracking error signal from the phase error signal; a clock generation unit for generating a clock; and a clock control unit having a frequency divider for generating a frequency-divided clock of the clock that is generated by the clock generation unit; wherein the clock control unit uses the frequency-divided clock as an operation clock for the tracking error detection apparatus. Therefore, the operation rate of each unit when generating a tracking error signal can be reduced, whereby a reduction in power consumption is achieved.

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 tracking control method carries out a tracking control based on a tracking error signal which indicates an error of a beam spot formed on a recording medium by a light beam from a light source with respect to a track. The tracking control method includes detecting a change in a light emission power of the light source, calculating a correction quantity which is used to correct a shift and/or fluctuation of the tracking error signal generated due to the change in the light emission power, and carrying out a correction by adding the correction quantity to the tracking error signal when the change in the light emission power is detected.

Abstract: A tracking error signal detector includes: a photodetector (103) for detecting reflected light from an optical recording medium having a servo area provided with a first wobble mark and a second wobble mark; an amplifier (104) for producing a summation signal of the reflected light; a sampling portion (105) for sampling the summation signal; a first arithmetic portion (106) for calculating an extremum of the summation signal in the vicinity of reproduction timing for each of the first and second wobble marks from the sampling values so as to produce first and second extremums; and a second arithmetic portion (107) for producing a tracking error signal that corresponds to a difference between the first and second extremum. The tracking error signal detector can produce a high-accuracy tracking error signal even if sampling is performed with an asynchronous clock relative to the summation signal.

Abstract: Header regions are formed by dividing a groove or grooves. Each of the header regions is provided with two ID sections G-ID1, G-ID2 storing address information and a track center detection mark section, arranged between the two ID sections, so as to be used for detecting the track center.

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

Abstract: A method for controlling the position of an optical beam incident on a track of a rotationally mobile carrier of information, such as a disc, includes picking up a beam reflected by the disc using an optical pick-up and determining a positioning error of the beam with respect to the track. The pick-up may include several photodetectors each providing an elementary signal, and the positioning error may be determined from the elementary signals. More precisely, from the elementary signals two sampled secondary signals whose mutual time gap is representative of the positioning error of the beam with respect to the track may be formulated. Furthermore, successive current values of the mutual time gap may be determined at the sampling frequency by searching at the sampling frequency for a successive current maximum of the cross-correlation function between the two sampled secondary signals. The present invention may be particularly applicable to multifunction digital disc (e.g., DVD) readers, for example.

Abstract: An optical disk includes tracks and grooves, the grooves being formed with a pitch equal to or greater than about &lgr;/NA. A first array of pits is provided at a position which is shifted by a predetermined amount with respect to each track in one of two directions substantially perpendicular to the tracks, the first array of pits being formed with a predetermined pitch, where the predetermined pitch is a function of a pitch of the grooves taking a value within a range from about 0 to about &lgr;/NA. A second array of pits is provided at a position which is shifted by a predetermined amount with respect to the track in the other one of the two directions substantially perpendicular to the tracks, the second array of pits being formed with a predetermined pitch, where the predetermined pitch is a function of the pitch of the grooves taking a value within the range from about 0 to about &lgr;/NA.

Abstract: A method of detecting a deviation in a servo control system to control a controlled system, has the processes of: applying a disturbance signal, which has a wave form having a constant frequency, to the controlled system; detecting a variation in a wave form of an output signal output from the controlled system by comparing the wave form of the output signal with the wave form of the disturbance signal; and detecting the deviation on the basis of the detected variation.

Abstract: An optical disk for a sampled servo system is provided with a servo area having a synchronization pit serving as a synchronization reference of reproduction; and a data area having a plurality of data pits which records the digital data and a tracking pit which serves as a tracking reference of the reproduction. The data pits are provided with first data pits and second data pits; and the tracking pit is located between the first and the second data pits. The tracking pit is located at a predetermined position in the data area. A pit row of the plurality of data pits and the tracking pit has the identical pit period. A pit row of the plurality of data pits and the tracking pit has a reverse phase between adjoining two tracks.

Abstract: An analog to digital circuit assembly includes a circuit for multiplexing a reference voltage input of an analog to digital converter to produce alternating normalized and referenced digital outputs of an analog signal input at a rate controlled by a sampling clock which includes a switch including first and second inputs, an output, and a control input for alternately connecting the first and the second inputs to the output, the output being applied to the reference voltage input. An information detection device having a detection output and a servo mechanism that controls operations on detected information is provided in conjunction with a signal summing circuit, a direct current voltage reference, a control clock connected, a servo error signal circuit having a servo error signal output and input, a sampling clock, and a processing circuit having an input connected to a digital output of the analog to digital converter and an output for controlling the servo mechanism.

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: 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.