Abstract: A clock extracting device of a disc reproducing apparatus includes an information read-out member for reading information signals from a disklike information recording medium; a voltage control oscillator; a phase comparator; a frequency comparator; a speed sensor for detecting the frequency of the output of the voltage control oscillator at a reference clock so as to output a speed signal; a gain command unit for designating a loop gain of a clock extracting circuit in accordance with the speed signal outputted from the speed sensor; a charge pump which discharges or draws electric current in accordance with outputs of the phase comparator and the frequency comparator and changes over an output current value in accordance with a gain command of the gain command unit; and a series circuit of a resistor and a capacitor, wherein the gain command unit issues the gain command such that the loop gain of the clock extracting circuit secures a desired operating point in accordance with a read rate of the information

Abstract: A wobble detection circuit detects a signal by a common photodetector (light receiving) element from several kinds of media having different pre-formats. Further, the wobble detection circuit changes a gain for amplifying the signal in a wobble signal detection process depending on the pre-format of a reproducing or recording medium to obtain a wobble signal.

Abstract: An optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises analog processing means including a binarization unit for subjecting a signal read from the optical disc to binarization and a servo unit for controlling recording and reproducing a signal in and from the optical disc; synchronous clock generating means for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; address detecting means for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the sync

Abstract: A method and an apparatus are provided which are capable of evaluating a state of a signal with a fewer number of samples compared with an error rate. A reproducing signal obtained from a magneto-optical disk is subjected to maximum-likelihood decode in a maximum-likelihood decoder, paths coupling with each other in the maximum-likelihood decode is detected by an evaluation index generation unit and, at the same time, a difference of likelihoods (path metrics) of those paths is obtained to adjust a parameter of a recording and reproducing signal or a control signal of an optical pickup based on the likelihood difference. The parameter is, for example, auto-tracking, a gain of an auto-focusing loop, or an offset value, or a gain value of a reproducing signal, a recording power, or a reproducing power intensity.

Abstract: A repeatable run-out (RRO) detector employs one or more digital interpolators to interpolate asynchronous sample values representing an RRO address mark (AM) and RRO data, and an asynchronous maximum-likelihood (AML) detector to detect the RRO AM. The AML detector selects one of either the asynchronous or interpolated sample sequences that are closest in distance to the ideal RRO AM sample sequence. In addition, a gain value is generated for each of the asynchronous and interpolated sample sequences. Once the RRO AM is detected, the AML detector provides a RRO AM found signal. Gain estimate values for either the selected asynchronous or selected interpolated sample sequences corresponding to the RRO AM found signal are averaged over a predefined number of detection events to generate a best gain error metric (BGEM). The BGEM is employed to adjust the gain of the asynchronous sample sequence.

Abstract: An optical disk apparatus capable of adjusting a focus servo and the like by precisely detecting a jitter amount. Light reflected from an optical disk is converted into an RF signal in an optical pickup and amplified by an RF amplifier before being supplied to an equalizer. The boost amount of the equalizer is set to zero during adjustment and set to a predetermined finite value (e.g., +20 dB) during normal recording and reproducing. By first setting the boost amount to zero, the delay characteristics of the RF signal from 3T to 11T are flattened such that an accurate jitter amount can be determined based on the integrated value of the phase differences of 3T to 11T, thereby allowing the optical pickup to be adjusted so as to minimize the jitter amount.

Abstract: A disk reproducing apparatus includes a variable gain amplifier (VCA) (32), and the VCA applies a radial push-pull signal including an address signal and an FCM leakage-in signal to a switch (38). The switch outputs only the address signal to a peak-hold circuit (40) on the basis of an FCM mask signal from a mask signal generation circuit (36). The peak-hold circuit generates a peak-hold signal of the address signal so as to be output to a DSP (30), and the DSP controls a gain of the VCA on the basis of the peak-hold signal. Then, the radial push-pull signal in which the gain is controlled on the basis of the address signal is applied to an address detection circuit (42), and the address signal is detected therein.

Abstract: During recording operations, decay processing is performed with regard to reflected light information signals (I1 and I2) during periods wherein the laser output is recording power which is comparatively high level, i.e., wherein data pits are being formed on the disk, and during recording operations, decay processing is not performed with regard to reflected light information signals during periods wherein the laser output is reproducing power which is comparatively low level, i.e., wherein the pits are not being formed on the disk. Accordingly, address information can be extracted in a stable manner while recording.

Abstract: In a multiprocessor computer system with multiple nodes, a static end to end retry apparatus and method uses the concept of sequence numbers combined with a path number. All transactions sent along a path are delivered in order to remove any time dependency. The apparatus and method ensure there are no duplicate transactions through the use of special probe and plunge transactions and their respective responses. The apparatus and method also allow for any number of alternate paths being active simultaneously, such that if one path fails, the remaining alternate paths can continue on the communication (along with the backup alternate path if desired) as usual without any loss of transactions. Each node keeps track of transactions the node has sent over time to every other node, as well as every transaction the node has received from every other node along each active path for each flow control class. To accomplish this tracking function, two data structures exist.

Abstract: Correction for harmonic disturbances on rotating storage media in a phase-locked loop. The effects of harmonic disturbances in a phase-locked loop are reduced by employing harmonic correction. Harmonic correction may be present in the loop at all times, or may be switched in once the loop has achieved phase lock. Disturbance within the loop bandwidth is corrected using additional integrating pole or a bump (resonant) filter. Disturbance outside the loop bandwidth is corrected using low pass or a notch (anti-resonant) filter. Alternately, a canceling signal may be generated and added as a feedforward signal. A repetitive control scheme uses a filtered version of the residual errors on previous media rotations as a feedforward signal to cancel harmonic effects.

Abstract: Push-pull signal is created on the basis of reflected-light detection signals output from four divided light receiving elements that receive a reflection of a recording laser light beam off an optical disk. The push-pull signal is sent to a gain variation circuit. The push-pull signal is normalized by setting the gain of the gain variation circuit to a low level in response to a mark forming section of a recording signal, but to a high level in response to a blank forming section of the recording signal. Wobble detection and pre-pit detection are performed on the basis of the normalized push-pull signal.

Abstract: A data recording method for calculating a digital sum value (DSV) corresponding to a proportion of positive data and negative data included in predetermined data ranges, selecting a resync pattern to be inserted between the data ranges according to the DSV, and inserting the selected resync pattern between the data ranges, has a step of selecting a resync pattern that minimizes differences in DSV between the data ranges.

Abstract: An automatic gain controller (AGC) for preventing peaking in an optical disc reproducing system includes a capacitor for being charged to a voltage corresponding to a control current as a control voltage; an amplifier for inputting the optical disc reproducing signal as an input signal, amplifying the input signal by a gain corresponding to the control voltage, and generating the amplified input signal as the output signal; a peak detector for detecting a peak voltage in the output signal; a gm amplifier for converting a peak voltage detected by the peak detector into current and generating the converted current as the control current; and a peaking controller for preventing the capacitor from being charged by the control current in a defect section in the input signal, in response to a peaking control signal, and for maintaining a control voltage in the defect section to be the same as the prior to the defect section.

Abstract: Logical triggering methods and apparatus for use with optical bio-discs. Some embodiments place physical triggers on the surface of the disc. Other embodiments logically encode triggers in user data area of optical bio discs. Still other embodiments take advantage of common optical disc operational components such as pits, lands, and other information encoding indicia for the purpose of encoding triggers. Primary decoding components are used to decode logical triggers. Alternatively, an added secondary decoding component or a data processor may also be used for the purpose of processing triggers. Logical triggers may be encoded in a pit/land pattern, encoded in the time code control information of wobble signal of a CD-R/RW disc, encoded in the header address information of a DVD-RAM based disc, or may be superimposed on the operational logic of the drive. Other triggering patterns are invoked by chemical reaction caused by chemistry placed on the discs.

Abstract: A single-unit digital recorder with a built-in amplifier is disclosed. The digital recorder and the amplifier are both enclosed within the same housing and in electrical connection with each other for operation by a common set of controls. This design minimizes the weight of the components and also simplifies the controls for the components. The user only has to transport a fully integrated unit for both recording and amplifying functions.

Abstract: A disk reproducing apparatus for reproducing a digital audio signal recorded on a DVD or CD has a PLL portion for outputting a synchronizing signal in synchronism with the digital audio signal. When the CD is reproduced at double speed or higher, the PLL portion increases again while seeking tracks, and restores the gain if a predetermined time has passed after the end of seek.

Abstract: A device in accordance with the invention for recording or reproducing information onto/from a rotating information carrier (10) has rotating element (16) for rotating the information carrier. The device further has conversion (16) for converting a write signal (SW) into a detectable pattern on the information carrier, or for generating a read signal (SLS) in response to a detectable pattern on the information carrier. The device also includes control unit (25, 26) for supplying at least one control signal (SR, SF) to the conversion unit in response to an error signal (RE, FE). The device also includes detection unit (25A, 26A) for generating a detection signal (DR, DF) which is a measure of a periodic variation in the error signal (RE, FE). The device in accordance with the invention is characterized by adjustment unit (29) for influencing the response of the control unit (25, 26) to the error signal (RE, FE) in dependence on the detection signal (DR, DF).

Abstract: The present invention relates to a method and a circuit for recovering information contained in a wobbled track on an optical storage medium. One aim of the invention is to describe a method within an appliance for reading from and/or writing to optical storage media, which can correct disturbing data signal components in the wobble signal even when the swept frequency and the lowest signal frequency are close to one another. According to the invention, this object is achieved in that the signals from two detector halves of a photodetector which is used for reading the data contained in a track on an optical storage medium are provided with weighting factors which are adjusted dynamically during operation of the appliance. In order to adjust the weighting factors, the data signal component in the wobble signal is linked to a disturbance signal from a disturbance signal generator.

Abstract: The present invention has an object to stably reproduce wobble signals of all disks of CD-R/RW, DVD-R/RW and DVD-RAM by one wobble signal reproducing circuit. In the wobble signal reproducing circuit, an AGC (AUTOMATIC GAIN CONTROL) circuit for equating a push-pull circuit output of a wide range and an RF amplitude of an optical detector output of two systems obtained by push-pull, and an AGC circuit for making a wobble amplitude uniform are provided with a function to hold a gain or to change over a response time constant, and an address information recording region (PID region) at the time of reproduction, the AGC (AUTOMATIC GAIN CONTROL) is held or the response time constant is changed over.

Abstract: An optical reproduction apparatus in accordance with the present invention has a gain control circuit for controlling a gain of an amplifier circuit which amplifies a reproduction signal in accordance with amplitudes of the reproduction signal from an optical recording medium. The amplitude is sent to a power control calculation circuit which controls the reproduction power of a light beam in accordance with the amplitude. The gain control circuit has a slower response speed than that of the power control circuit at least during a period when the power control circuit controls the reproduction power. This allows to provide an optical reproduction apparatus that can realize the stable reproduction power and automatic gain control even to the unevenness of the amplitudes of the reproduction signal.

Abstract: A plurality of cross detectors have predetermined threshold levels different from each other. Each cross detector increments a count value when the reproduced signal crosses over its threshold level and generates the accumulated count value as a cross count value. Upon the cross count value agreeing with a common reference value, each comparator sends the coincidence signal to an OR circuit. The OR circuit produces a reset pulse in response to a first-arriving coincidence signal. The reset pulse is supplied to each cross detector to reset the cross count values of all of cross detectors and is also supplied to a down counter to reset it. When the cross count value becomes a predetermined value, an error signal is produced based on a deviation of the bit clock count value relative to a proper value so as to correct the deviation. The frequency control is performed based on the produced error signal.

Abstract: A method of determining interrupts in data on an optical disc, the data supported in a signal envelope subject to variation by mirror modulation and said interrupts. The method comprises the steps of (A) filtering the signal envelope to generate a first signal; (B) re-biasing the first signal to produce an intermediate signal having voltage swings attributable to the mirror modulation; (C) defining a slice level below a reference level to sample the mirror modulation to produce a mirror signal; (D) slicing the intermediate signal to generate the mirror signal containing a pulse resulting from a level transition through the slice level associated with re-biasing of the positive transition component; and (E) registering the presence of the pulse during the on-track mode of operation to identify the interrupt in data on the optical disc.

Abstract: A method of reproducing information by scanning information marks, disposed with a predetermined mark pitch therebetween and recorded on tracks inside a predetermined information recording region, by an optical spot. The method includes detecting the size of the optical change resulting from the information mark, calculating a plurality of equalization coefficients used for an equalization processing for the size of the optical change detected for each of the information marks, and reducing the inter-symbol interference on the basis of the equalization coefficients by the equalization processing. The equalization coefficient used for the equalization processing of the size of the optical change by a first information mark is greater than said equalization coefficient used for the equalization processing of the size of said optical change by a second information mark which is longer than the first information mark.

Abstract: A method of reproducing information by scanning information marks, disposed with a predetermined mark pitch therebetween and recorded on tracks inside a predetermined information recording region, by an optical spot. The method includes detecting the size of the optical change resulting from the information mark, calculating a plurality of equalization coefficients used for an equalization processing for the size of the optical change detected for each of the information marks, and reducing the inter-symbol interference on the basis of the equalization coefficients by the equalization processing. The equalization coefficient used for the equalization processing of the size of the optical change by a first information mark is greater than said equalization coefficient used for the equalization processing of the size of said optical change by a second information mark which is longer than the first information mark.

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: There are provided a modulation table, a selector, and a counter. The modulation table is used for creating a plurality of modulation data candidates with respect to a mixture of user data and training data. The selector selects modulation data candidates. The counter counts DSVs for the selected modulation data and controls the selector. The DSV output from this counter is set to a specified value by keeping a state in which the training data is input.

Abstract: A disk reproducing apparatus includes a variable gain amplifier (VCA) (32), and the VCA applies a radial push-pull signal including an address signal and an FCM leakage-in signal to a switch (38). The switch outputs only the address signal to a peak-hold circuit (40) on the basis of an FCM mask signal from a mask signal generation circuit (36). The peak-hold circuit generates a peak-hold signal of the address signal so as to be output to a DSP (30), and the DSP controls a gain of the VCA on the basis of the peak-hold signal. Then, the radial push-pull signal in which the gain is controlled on the basis of the address signal is applied to an address detection circuit (42), and the address signal is detected therein.

Abstract: A tracking error balance adjustment circuit, and a current control circuit used for a variable gain RF amplifier automatically controlled to output a signal having a predetermined amplitude. The tracking error balance adjustment circuit comprises two separate gain adjusting circuits, each having variable attenuation circuit having first gm amplifier of variable gm type, a second gm amplifier of variable gm type connected to the variable attenuation circuit, and an output circuit connected to the second gm amplifier, comprising an operational amplifier circuit having feedback resistor, wherein the first and second gm amplifiers are differentially controlled commonly by a control current.

Abstract: The present invention provides a passive RFID chip with on-chip charge pumps for generating electrical power for the chip from radio frequencies. The passive RFID chip comprises an analog portion and a digital portion. The analog portion primarily comprises a voltage sensor and an AM data detector. The digital portion comprises a state machine digital logic controller. Incoming RF signals enter the chip via external antennas. The RF signals are converted into regulated DC signals by RF-DC converters with the voltage sensor. The RF-DC converters provide power for all the on-chip components and hence the chip does not require external power supply. The incoming RF signals are demodulated by demodulators and enter the AM data detector where the envelope transitions are detected. A voltage alarm is provided to ensure the voltage level does not drop below an operational level of the chip.

Abstract: A system and method are disclosed for reading a multilevel signal from an optical disc. The method includes reading a raw analog data signal from a disc using an optical detector and adjusting the amplitude of the raw analog data signal. A timing signal is recovered from the amplitude adjusted analog data signal and correction is made for amplitude modulation of the raw analog data signal by processing the raw analog data signal and the timing signal.

Abstract: Correction for harmonic disturbances on rotating storage media in a phase-locked loop. The effects of harmonic disturbances in a phase-locked loop are reduced by employing harmonic correction. Harmonic correction may be present in the loop at all times, or may be switched in once the loop has achieved phase lock. Disturbance within the loop bandwidth is corrected using additional integrating pole or a bump (resonant) filter. Disturbance outside the loop bandwidth is corrected using low pass or a notch (anti-resonant) filter. Alternately, a canceling signal may be generated and added as a feedforward signal. A repetitive control scheme uses a filtered version of the residual errors on previous media rotations as a feedforward signal to cancel harmonic effects.

Abstract: When first and second read signals generated on the basis of the outputs of electrical signals from a light receiving portion are input to an amplitude correcting circuit, the first and second read signals are added to generate an addition signal. Then the amplitudes of the first and second read signals are corrected for the each RF signal component corresponding to each recording pit, which is contained in the first and second read signals on the basis of the addition signal. Finally, the difference between the first and second read signals is computed to generate a difference signal so that a pre-pit signal will be detected on the basis of the difference signal.

Abstract: A disk device for controlling the revolution of a disk, and the operation of a focus coil and a tracking coil with high precision even during the low-velocity revolution of a disk is provided. A control signal gain switch circuit (12) is provided as control signal gain switch means for switching depending on an operation state and outputting a gain of at least one of a spindle motor control signal (10) output to a spindle motor control circuit (3) as the first control unit for controlling a spindle motor (2) which revolves the disk (1), and a focus tracking control signal (11) output to the focus tracking control circuit (4) as the second control unit for controlling an optical pickup (5) which reads information in the disk (1) and outputs a high frequency signal.

Abstract: Crosstalk cancellation is realized more accurately than ever by considering both magnitude and a phase difference of a crosstalk signal from a recording track adjoining a target track, in comparison with magnitude and a phase of a desired signal from the target track, which is implemented by providing a crosstalk amount detection means, a phase difference measurement means, and a crosstalk component generation means that generates a crosstalk component to be subtracted from a signal obtained by an optical scanning that includes the desired signal and the crosstalk.

Abstract: Level detectors detect levels of digital audio signals of individual channels. A controller predicts whether or not an overflow will take place corresponding to detected signals. When the controller predicts an occurrence of an overflow, attenuators attenuate a signal level of at least one channel. In addition, when variable length delaying devices vary the phases of signals, an overflow can be prevented.

Abstract: The invention provides a transmission apparatus, a recording apparatus, a transmission and reception apparatus, a transmission method, a recording method and a transmission and reception method by which data can be communicated between different apparatus over a single data bus in accordance with a first communication method wherein data can be transmitted and/or received periodically and a second communication method wherein data can be transmitted and/or received asynchronously.

Abstract: During recording operations, decay processing is performed with regard to reflected light information signals (I1 and I2) during periods wherein the laser output is recording power which is comparatively high level, i.e., wherein data pits are being formed on the disk, and during recording operations, decay processing is not performed with regard to reflected light information signals during periods wherein the laser output is reproducing power which is comparatively low level, i.e., wherein the pits are not being formed on the disk. Accordingly, address information can be extracted in a stable manner while recording.

Abstract: To provide a spindle motor control method adapted to an optical disk recording and reproducing apparatus capable of recording a signal onto a disk using a laser applied from an optical pick-up, a reference signal originated from a disk (1) and a reference signal necessary for signal recording are synchronized to each other when resuming signal recording once suspended. The synchronization is established without using a phase error component. Once synchronization is established, a phase error component is added to a servo signal of the spindle motor (2). A gain for a phase error component is begun gradually increasing after a phase error component is begun being added to a servo signal. An upper limit value of the gain of a phase error component to be added is determined depending on the location of a part on the disk (1) at which to resume the once suspended signal recording.

Abstract: An optical recording method for an optical disk having a disk surface portion in which prepits, indicative of preformat information, are formed. In the optical recording method, a portion of a data signal which matches one of the prepits and corresponds to a write mark radially adjacent to one of the prepits is detected. Marks are recorded along a track of the disk by selectively using one of an optimal recording power and a proper recording power level, in accordance with the non-match portion or the match portion of the data signal. A radial width of the marks recorded in accordance with the match portion of the data signal is smaller than a radial width of the marks recorded in accordance with the non-match portion of the data signal. An optical reproducing method is adapted to accurately detect a wobble signal and a prepit signal from the optical disk to which data is recorded by the above optical recording method.

Abstract: A servo controller for correcting a read position of a head when reading data recorded on a recording medium. In accordance with the amplitude ratio of data signals read from each segment of a servo section defined on a recording medium, the servo controller generates an AGC signal corresponding to the next segment before reading the next segment. The data signal read from a phase detection segment of the servo section is amplified to an amplitude greater than the predetermined determination range. The amplified data signal is converted to a two-value digital signal in accordance with the determination range. The phase used during servo control is calculated in accordance with the digital signal.

Abstract: An optical disc apparatus and method for recording and reproducing information to/from an optical disc, including discrimination of the optical disc, reading control information in an un-recordable area formed in an inner periphery of the optical disc, conducting focus control based on a focus error signal in a recordable area formed outside of the un-recordable area, and determining an optimum offset value of the focus error signal in the recordable area. Further, adjustment in amplitude of a reproduced signal from an inner periphery of the recordable area is conducted, test-writing in the inner periphery of the recordable area is conducted, test-writing in an outer periphery of the recordable area is conducted, and adjustment in amplitude of a reproduced signal from the outer periphery of the recordable area is conducted. The respective operations are conducted sequentially so as to make the optical disc in a reproducible and recordable condition.

Abstract: When first and second read signals generated on the basis of the outputs of electrical signals from a light receiving portion are input to an amplitude correcting circuit, the first and second read signals are added to generate an addition signal. Then the amplitudes of the first and second read signals are corrected for the each RF signal component corresponding to each recording pit, which is contained in the first and second read signals on the basis of the addition signal. Finally, the difference between the first and second read signals is computed to generate a difference signal so that a pre-pit signal will be detected on the basis of the difference signal.

Abstract: Disclosed is a pick-up head controller for optical disk drives, structured particularly for optimal actuation characteristics of a pick-up head of optical disk drives. A framework, composed of a high-frequency digital controller and a low-frequency digital controller, accomplishing different order types of controllers required by optical head systems, is provided based upon the sampling rate dependence of response of digital controllers. Experimental results shows excellent performance in optical systems that high performance, low cost and easy designing can be achieved.

Abstract: A method of determining interrupts in data on an optical disc, the data supported in a signal envelope subject to variation by mirror modulation and said interrupts. The method comprises the steps of (A) filtering the signal envelope to generate a first signal; (B) re-biasing the first signal to produce an intermediate signal having voltage swings attributable to the mirror modulation; (C) defining a slice level below a reference level to sample the mirror modulation to produce a mirror signal; (D) slicing the intermediate signal to generate the mirror signal containing a pulse resulting from a level transition through the slice level associated with re-biasing of the positive transition component; and (E) registering the presence of the pulse during the on-track mode of operation to identify the interrupt in data on the optical disc.

Abstract: An information reproducing apparatus method includes the steps of radiating an optical spots to scan information marks recorded on tracks inside a predetermined information recording region, detecting an optical change of the information marks by this scanning operation, executing a signal processing for the reproducing signal so as to reduce inter-symbol interference of an interference amount that varies for each of the information marks, and reproducing the information corresponding to the information mark. The magnitude of the optical change due to the information mark is thereby detected, and a plurality of equalization coefficients used for an equalization processing are calculated for the magnitude of the optical change detected for each information mark. The inter-symbol interference is reduced on the basis of these equalization coefficients.

Abstract: A defect protecting circuit and a method for data slicer in an optical drive is disclosed. As a defect occurs in a disk, the gain of the data slicer is switched to a high gain. After the defect does not occur further, the gain is switched back to a normal gain. Therefore the slicing level can return back to a correct slicing level for reducing incorrect data after the defect terminates, and the jitter in the output data is also reduced.

Abstract: A clock extracting device of a disc reproducing apparatus, comprising: an information read-out member for reading information signals from a disklike information recording medium; a voltage control oscillator; a phase comparator for comparing a phase of the information signals read by the information read-out member and a phase of an output of the voltage control oscillator; a frequency comparator for comparing a frequency of the information signals read by the information read-out member and a frequency of the output of the voltage control oscillator; a speed sensor for detecting the frequency of the output of the voltage control oscillator at a reference clock so as to output a speed signal; a gain command unit for designating a loop gain of a clock extracting circuit in accordance with the speed signal outputted from the speed sensor; a charge pump which discharges or draws electric current in accordance with outputs of the phase comparator and the frequency comparator and changes over an output current va

Abstract: An apparatus operates for recording and reproducing information on and from a recording medium formed with a track and pre-pits. The track has a wobble. The pre-pits are in a predetermined phase relation with the wobble of the track. The apparatus includes a pickup for reproducing a signal from the recording medium. A limiter operates for limiting an amplitude of the signal reproduced by the pickup in response to a limiting level, and thereby processing the signal reproduced by the pickup into a limiting-resultant signal. A filter operates for suppressing components of the limiting-resultant signal, and thereby processing the limiting-resultant signal into a filtering-resultant signal. The components have specified frequencies, and are caused by the pre-pits. The limiting level for the limiter is generated in response to the filtering-resultant signal. A signal caused by the wobble of the groove is extracted from the filtering-resultant signal.

Abstract: The invention relates to a predetermined synchronization pattern (40), a so-called VFO field, in, for example, the headers 3 of an information carrier. The proposed predetermined synchronization pattern (40) consists of sequences of 3T marks and spaces (41), of 8T marks and spaces (42) and of 5T marks and spaces (43). This sequence of patterns is advantageous for setting the dynamic range of an Automatic Gain Controlled (AGC) amplifier located within a device reading the information carrier.

Abstract: An optical reproduction apparatus in accordance with the present invention has a gain control circuit for controlling a gain of an amplifier circuit which amplifies a reproduction signal in accordance with amplitudes of the reproduction signal from an optical recording medium. The amplitude is sent to a power control calculation circuit which controls the reproduction power of a light beam in accordance with the amplitude. The gain control circuit has a slower response speed than that of the power control circuit at least during a period when the power control circuit controls the reproduction power. This allows to provide an optical reproduction apparatus that can realize the stable reproduction power and automatic gain control even to the unevenness of the amplitudes of the reproduction signal.