Abstract: A push-pull signal is detected from light reflected from a disk-shaped storage medium on which wobbling grooves are formed as recording tracks and address information is recorded by forming pre-pits on lands between adjacent grooves. A fundamental amplitude variation signal indicating the fundamental amplitude variation of the push-pull signal is acquired, and a reference voltage is generated by adding an offset voltage to the fundamental amplitude variation signal. Pre-pits are detected by comparing the push-pull signal with the reference voltage. Because the reference voltage is produced on the basis of the fundamental amplitude variation signal indicating the variation components of the push-pull signal due to the wobbling of grooves and noise, the variation components due to the wobbling and noise are reflected in the reference voltage. Furthermore, the variation components of the push-pull signal corresponding to the pre-pits are also reflected to a properly small extent in the reference voltage.

Abstract: The statistical circuit includes a pulse-width measuring unit, serially coupling delay units, a logical circuit and counters. The pulse-width measuring unit is for receiving a sampling signal and generating a pulse-width signal. A pulse occurs on the pulse-width signal as the sampling signal has status change. The delay units include a first delay unit for receiving the pulse-width signal and outputting delay signals according to the trigger of a reference clock. The output of the first delay unit is used as a reset signal. The logic circuit is for receiving the pulse-width signal and the reset signal and generating a counting signal. The counting signal is enabled for a period of time as a pulse occurs on the pulse-width signal. The counters are respectively for receiving the delay signals and counting the number of the received delay signals in a first status as the trigger signal is enabled.

Abstract: The present invention discloses a mixed mode circuit for data slice with auto calibration and method thereof, which comprises a data slicer for converting an analog signal into a digital signal; a set of current pump for supplying a variable power supply; a microprocessor for controlling and adjusting the set of current pump; a digital sum value counter for performing an addition or a subtraction operation according to the result outputted by the data slicer; a digital signal processor for reading the internal values of the digital sum value counter and calculating the average of these internal values to obtain a parameter value. With the aforementioned structure, the invention integrates the mixed mode data slicer of analog and digital circuits so as to adopt the merits and eliminate the drawbacks of the pure analog and digital data slicer and thus achieves the objective of reading data from an optical disk better and more accurately.

Abstract: Provided are a restoration system and method for an optical disc, by which a radio frequency signal optically picked up from an optical disc is restored. The restoration system includes a slice, a phase locked loop, a latch circuit, a 3T correction circuit, and a demodulator. In particular, the 3T correction circuit includes an extension storage device, a length measuring device, a phase detector, and an extension determiner and corrects data output from the extension storage device. In the restoration method, data required for determining the need for correction and the direction of correction is detected and a plurality of steps for selecting non-correction, two directional correction, forward correction, and backward correction are performed, thereby correcting the high radio frequency signal according to conditions of the high radio frequency signal. It is preferable that the restoration system operates according to the restoration method.

Abstract: The present invention relates to a symbol detection apparatus for detecting the symbol values of a one-dimensional channel data stream recorded along one-dimensional contiguous tracks on a record carrier, wherein the symbols of adjacent tracks have a varying phase relation.

Abstract: A reproduction signal evaluation method of this invention includes the step of obtaining a reproduction signal from an information recording medium on which digital information is recorded with record marks having different sizes, the step of obtaining the amplitude of a first reproduction signal, of the signals contained in the reproduction signal, which reflects digital information recorded with a record mark having the maximum size, the step of obtaining the amplitude of a second reproduction signal, of the signals contained in the reproduction signal, which reflects digital information recorded with a record mark having the second smallest size, the step of obtaining an evaluation value from the ratio of the amplitudes of the first and second reproduction signals, and the step of evaluating a characteristic of the reproduction signal on the basis of the evaluation value.

Abstract: An apparatus and method for slicing an RF signal and compensating for the slice level of an RF signal reproduced from a disk, which minimizes a block error rate by optimizing the slice level of the RF signal according to variations in symmetry of the RF signal when slicing the RF signal. A comparator converts the RF signal reproduced from the disk into a digital signal by comparing the RF signal with a slice level, a low-pass filter low-pass filters the digital signal and provides the result to the comparator as the slice level, and a slice level compensator compensates for the slice level provided to the comparator by the low-pass filter according to variations in symmetry of the RF signal.

Abstract: The present invention relates to a device for reading from and/or writing to optical recording media (1) having an optical scanner (2) for scanning the recording medium (1) by means of a light beam (3) and for generating scanning signals (HF) from the reflected beam (3), a data slicer (5) for converting a scanning signal (HF) output by the optical scanner (2) into a binary signal (HF?), an averaging unit (6) for forming an average value (M) from the scanning signal (HF, HF?) as input signal of the data slicer (5), and a control unit (14) for changing a parameter (T, OF) of the averaging unit (6). The object of the present invention is to propose a device of this type and also a suitable method therefor in which the average value (M) can be adapted to disturbances during the scanning of the recording medium.

Abstract: A combined signal Spc in which a pre-pit signal is superposed on a wobble signal is generated based on a radial push-pull signal Spp with a noise component having been removed therefrom. Based on the combined signal Spc, a wobble signal SWB with the phase ?0 not having time fluctuation and a pre-pit signal SPD are generated with the phases compared to each other, and then a phase adjustment signal SCNT corresponding to a phase difference ?e is generated. The phase differences ?e are stored, and an average value ?r thereof generated, the phase difference ?e is compared to the average value ?r, the phase ?0 is shifted according to only by the phase difference ?e only when the phase difference ?e is within the range of (?r±W), and then a wobble signal SWB with the phase ?1 synchronized to the pre-pit signal SPD is generated.

Abstract: A detector for detecting information carried by a signal having a sawtooth-like shape. The detector includes a low-pass filter for receiving the wobble signal and filtering the wobble signal to generate a filtered signal, a comparator for comparing the wobble signal with the filtered signal and generating a compared signal, and a detecting unit for receiving the compared signal and generating a bit signal according to the duty cycle of the compared signal. The bit signal is a first value when the duty cycle of the compared signal is greater than a predetermined value, and the bit signal is a second value when the duty cycle of the compared signal is smaller than the predetermined value.

Abstract: A method and apparatus for reading an index mark pattern. The pattern may be formed on an optical disc medium. The optical disc medium may include a set of data arranged in a data field, and an index mark pattern for identifying a relative location of the data field.

Abstract: A data slicer includes a comparator coupled with an input signal and a reference signal for generating a sliced signal, a waveform generator for generating a calibration signal, a pulse extension device coupled to the comparator and the waveform generator for modifying the duty cycle of the sliced signal or the calibration signal to output, a charge pump coupled between the pulse extension device and a first node for charging and discharging the first node according to the signal output from the pulse extension device, a determining circuit for adjusting the data slicer according to the level change at the first node, and a feedback device coupled between the first node and the comparator for generating the reference signal.

Abstract: In a data slicer and data slicing method for an optical disc system, the data slicer for converting an analog input signal into a digital signal includes a comparator, a duty detector, and a low pass filter. The comparator compares the analog input signal with a feedback signal to generate the digital signal. The duty detector detects the duty of the digital signal. If the detected duty is longer than a preset duration, the duty detector converts the detected signal into a signal having the preset duration, and outputs the converted signal. The low pass filter integrates the output signal of the duty detector to generate the feedback signal.

Abstract: An optical information recording/reproducing apparatus is adapted to record and/or reproduce multilevel information on/or from an optical information recording medium. The multilevel information is recorded in the form of pits in cells virtually formed at regular intervals on a track. The respective levels are represented by varying the length or the area of information pits such that a reproduced signal has a different amplitude level depending on the length or the area of information pits. A reproduced signal correction circuit corrects a reproduced signal obtained by performing sampling at the center of each cell. An error power calculation circuit calculates error power on the basis of the difference between the corrected reproduced signal and an ideal value of each level of the cell. A decoder performs decoding on the basis of the calculated error power values.

Abstract: An enhanced write splice for optical recording channels is disclosed. Optical control circuitry locks to previously-written data and determines the estimated write splice location. A training sequence is written to the optical medium at a location based on the estimated write splice location. The phase offset is then estimated by reading the training sequence. A new write splice location may then be calculated compensating for the phase offset estimate. Finally, the new data to be spliced may be written or overwritten to the channel at the new write splice location.

Abstract: An automatic detecting device of land pre-pits signal is disclosed. The device adjusts gain of push-pull signals to raise the signal to noise ratio of the land pre-pits signal to the wobble signal. Digital logic computation is also utilized to recognize the practical position of the land pre-pits. The level automatic detection of the RC circuit and the fixed slice level compose an automatic slice level, which is the basis for detecting the land pre-pits. The disclosed device eliminates the drawback of not easy to obtain correct land pre-pits signal from written disks by the conventional of fixed land pre-pits slice level technology.

Abstract: An apparatus and method of estimating the quality of an input signal, and an optical disc driver including the apparatus for estimating the quality of the input signal, the signal quality estimating apparatus including a level value detection unit that detects level values of an input signal according to a binary signal of the input signal, an input signal composing unit that composes a plurality of ideal input signals by using the level values and a plurality of pre-defined binary signals, and a quality calculation unit that obtains a quality of the input signal according to a calculation between the plurality of ideal input signals.

Abstract: An optical disk includes a recording region formed on a substrate for recording user data, and a management region formed on the substrate which includes an identification information region for recording disk-specific identification information such as address information (ID), a SYNC code, or an error detection code (EDC). The identification information region in this optical disk has a flat portion (a mirror region) formed by means of sectioning part of a groove or a land in a given step. The disk-specific identification information is recorded on the identification information region inclusive of this mirror region as irreversible record marks. Moreover, a signal of the disk-specific identification information is detected by a laser beam which is servoed on the recording track of this optical disk. Then, a change in the detected signal level of the disk-specific identification information is detected based on a predetermined threshold level.

Abstract: An RF signal that is a disk reproduction signal is binarized through an equalizer and a slicer, followed by data demodulation, and an error rate of the reproduction signal is detected in an error detection circuit. If the error rate in the error detection circuit is higher than a prescribed value, a slice balance adjustment circuit performs slice balance adjustment for the slicer and a boost adjustment circuit performs boost adjustment for the equalizer.

Abstract: A data detection circuit and method detect a first bit that is the least significant among bits having a value 1 in N-bit input binary data and a second bit that is the second least significant among bits having the value 1 in the N-bit input data. The data detection method includes the steps of receiving N-bit input data, detecting the first bit that is the least significant among bits having the first value in the received N-bit input data, changing only the value of the detected first bit in the N-bit input data into a second value, and outputting thus generated N-bit intermediate data, in response to a clock signal, and then receiving the N-bit intermediate data, detecting a second bit that is the least significant among bits having the first value in the received N-bit intermediate data, and outputting the detection result, in response to an inverted signal of the clock signal.

Abstract: In this optical disk device, a reflected light of a light beam reflected from a pre-pit-formed side of a track wobbled on a disk is detected as a first detection signal. A reflected light of the light beam reflected from the other side of the track is detected as a second detection signal. The first detection signal and/or the second detection signal are/is amplified with a gain(s) so set that a peak value of a wobble signal component of the first detection signal coincides with a bottom value of a wobble signal component of the second detection signal.

Abstract: An optical disk apparatus for driving an optical disk having formed therein sawtooth wobbles of +STW and ?STW. A pickup receives a laser beam reflected from the optical disk and supplies a reproduced signal to a wobble signal processing section. The wobble signal processing section differentiates the reproduced signal and binarizes the differential signal with reference to a zero level. A pulse length of the binary signal achieved during a positive period is compared with that of the binary signal achieved during a negative period. When the pulse length achieved during the positive period is longer than that achieved during the negative period, the binary signal is determined to be a +STW. In contrast, when the pulse length achieved during the negative period is longer than that achieved during the positive period, the binary signal is determined to be a ?STW, whereby a wobble signal is demodulated.

Abstract: Disclosed is a PLL circuit having a voltage-controlled oscillator, to which a difference voltage across non-inverting and inverting input terminals is input as a control voltage, for oscillating at a frequency in accordance with the control voltage; a phase comparator for comparing the phase of an output signal obtained by frequency-dividing the output of the voltage-controlled oscillator by a frequency-divider, with the phase of an input signal and outputting the result of this phase comparison; first and second loop filters connected at output terminals thereof to the non-inverting and inverting input terminals, respectively, of the voltage-controlled oscillator; and a charge pump, which is responsive to receipt of an UP signal supplied from the phase comparator, for supplying a first charging current from a PMOS transistor to a capacitor of the first loop filter and supplying a first discharge current from an NMOS transistor to a capacitor of the second loop filter, and which is responsive to receipt of a

Abstract: A disk is placed into a disk drive device to be held therein. Then, a laser pickup is moved to the inner edge of the disk in step S1, various servos are automatically adjusted in step S2, TOC information of the disk is read in step S3, and a DBAL adjustment is performed in step S4. Here, the DBAL adjustment refers to an adjustment of a balance of a slice value for data. It is then determined whether or not the disk is recorded with information in multisession in step S5. If the disk is recorded in multisession, the DBAL adjustment for the session proceeds to a DBAL adjustment for a subsequent session in step S7. In other words, if the disk is a multisession disk, the DBAL adjustment is performed for each session.

Abstract: There are provided a balance adjustment circuit (6) for adjusting levels of first and second detection signals from a tracking detector, a differential circuit (8) for generating a difference signal between the adjusted first and second detection signals, an AD conversion circuit (10) for digitizing the difference signal, a wobble signal detection circuit (14) for detecting a wobble signal from the digitized difference signal, an adder circuit (30) for generating a sum signal of the adjusted first and second detection signals, a binarization circuit (32) for converting the sum signal into a binarized signal, a latch circuit (33) for latching the binarized signal and converting the same into a timing signal, a control signal generation circuit (34) for generating a control signal based on the timing signal and the digitized difference signal, a residual component removal circuit (18) for removing a residual signal component included in the digitized difference signal based on the control signal and outputting

Abstract: A method of increasing data extraction compatibility for an optical disc drive is disclosed. The method first provides extraction parameter sets, wherein the extraction parameter sets comprise a first extraction parameter set and a second extraction parameter set. The optical disc drive then uses the first extraction parameter set to extract data from an optical disc. Finally, the optical disc drive uses the second extraction parameter set to extract data from the optical disc if a data extraction error occurs.

Abstract: The present invention provides a method for automatically tuning a pre-pit slicing level and a related apparatus. The pre-pit slicing level can be used for slicing a first signal generated by an optical storage device when reading an optical storage disc to identify at least one pre-pit signal within the first signal. The method includes finding a first maximum according to the first signal, and generating the pre-pit slicing level according to the first maximum so that the optical storage device is capable of identifying the pre-pit signal within the first signal.

Abstract: An information recording medium for recording main information and auxiliary information is provided. The auxiliary information is recorded on the information recording medium in a manner that edge positions of the pits or the recording marks indicating the main information are shifted either in a phase advancing direction or in a phase delaying direction along the track direction. A predetermined frequency is used to determine whether the edge position is shifted in the phase advancing direction or in the phase delaying direction in order to record the auxiliary information. The predetermined frequency is substantially consistently lower than ½ of a reference frequency of a recording clock for creating the pits or the recording marks and is higher than a response frequency of a PLL for generating a reproduction clock for reproducing the main information.

Abstract: In a method of detecting defects during a write operation for an optical disk recording device, during a period of time immediately after writing begins, a sub-beam added (SBAD) signal is compared with a reference signal having a second threshold frequency. A defect is identified when a difference between the SBAD signal and the reference signal exceeds either a second upper limit or a second lower limit. Then, after the short period of time has elapsed, a SBAD signal is compared with and a reference signal having a first threshold frequency that is less than the second threshold frequency. A defect is identified when a difference between the SBAD signal and the reference signal exceeds either a first upper limit that is less than the second upper limit, or a first lower limit that is greater than the second lower limit.

Abstract: A reproduction signal evaluation method of this invention includes the step of obtaining a reproduction signal from an information recording medium on which digital information is recorded with record marks having different sizes, the step of obtaining the amplitude of a first reproduction signal, of the signals contained in the reproduction signal, which reflects digital information recorded with a record mark having the maximum size, the step of obtaining the amplitude of a second reproduction signal, of the signals contained in the reproduction signal, which reflects digital information recorded with a record mark having the second smallest size, the step of obtaining an evaluation value from the ratio of the amplitudes of the first and second reproduction signals, and the step of evaluating a characteristic of the reproduction signal on the basis of the evaluation value.

Abstract: The present invention is applied to an optical disk apparatus which records data on and/or plays back data from one of a variety of DVD optical disks. The present invention generates a binarization threshold S3 by offsetting an envelope S2 of a playback signal RF by an offset voltage V1, and binarizes the playback signal RF (S4) according to the binarization threshold.

Abstract: A maximum error region determining unit determines a region having a maximum likelihood of error from a channel signal y(t). An optimal path searching unit uses only an error signal at the region having a maximum likelihood of error to find a minimum error generation path and to correct the error signal. A signal recovery unit applies a predetermined algorithm to the channel signal y(t) in which a part of the signal has been corrected by the optimal path searching unit in order to recover an original recorded signal ak. The signal processing apparatus and method search for an optimal path of a channel signal only in the maximum error generation region, thereby reducing complexity and simplifying implementing hardware while allowing for signal processing without change in hardware where changes in a channel model or conditions of an input signal occur.

Abstract: An apparatus for reading and/or writing data markings of an optical recording medium having data markings arranged along a track and header markings arranged laterally offset with respect to the center of the track, the apparatus having a header identification unit. According to the present invention an intermediate track signal is formed, which enables direction identification during the traversal of tracks. The present invention comprises an apparatus having a header sequence detector, a track crossing detector and an intermediate track detector, wherein the intermediate track detector is connected to outputs of the header identification unit, the track crossing detector and the header sequence detector, and generates an intermediate track signal.

Abstract: The present invention provides a binarization device that realizes reproduction with a low error rate, even where optimum recording conditions such as recording power have not been set in the recording device, or where optimum recording has not been carried out for the reproducing device. The binarization device includes a binarization unit, a slice level setting unit, and a weight adding function. The binarization unit binarizes a reproduction signal obtained by reproducing information recorded by mark length recording on a recording medium to output high-level signals and low-level signals based on a slice level. The slice level setting unit calculates the average value of the high-level signals output from the binarization unit, and determines the slice level from the average value. The determined slice level is set to the binarization unit. Either the binarization unit or the slice level setting unit adds a predetermined weight to each signal having a short high-level time among the high-level signals.

Abstract: An apparatus for detecting pre-pit information is disclosed, including an optical pickup, an optical-detecting section, a difference-detecting circuit, a first peak-value detecting circuit, a filtering circuit, a second peak-value detecting circuit, a differential potential-dividing circuit, and a comparator.

Abstract: A data slicer capable of removing current mismatch between internal current pumps and its operating method is proposed. The data slicer includes a comparator for comparing an analog signal with a slice reference level to convert the analog signal into a digital signal, a counter electrically connected to the comparator for calculating a digital sum value according to logic values carried by the digital signal, and a voltage-adjusting circuit electrically connected to the comparator for adjusting the slice reference level. The voltage-adjusting circuit has two current pumps for shifting the slice reference level. The current generated by the current pumps can be adjusted according to the calculated digital sum value to reduce a difference between a first and a second binary values which are used to increase and decrease the slice reference level respectively.

Abstract: When an optical disc is set to the motor, the slice level is set to a slice level Sk as a reference slice level and a measured jitter value A (S0, S1) is produced. The slice level is incremented in steps of a fixed quantity Si (S2). Then, a measured jitter value B obtained at the incremented slice level is compared with the previous measured jitter value A (S3, S4). This sequence of process is repeated, and when the measured jitter value A is smaller than the counter value, it is judged that the jitter changes its quantity varying direction to a decreasing direction. Then, the incrementing operation of the slice level is immediately stopped, and the slice level is decremented in steps of another fixed quantity Sd (<Si). The previous measured jitter value C is compared with a measured jitter value D after the slice level is decremented (S5 to S8). When the measured jitter value C is smaller than the counter jitter value, it is judged that the slice level detected at that time is an optimum slice level.

Abstract: An ATIP (absolute time in pre-groove) bit data generator free from an uneven duty cycle. The ATIP bit data generator includes an analog processor, a high-frequency clock generator, a first decoder, a sync pattern detector, and a second decoder. The analog processor receives a signal generated from an optical pickup, and further processes the signal to generate an ATIP FM signal. The high-frequency clock generator provides a high-frequency clock using the ATIP FM signal as a reference signal. The first decoder receives the ATIP FM signal and the high-frequency clock and generates bi-phase data. The sync pattern detector receives the bi-phase data and the high-frequency clock, and generates a sync indication signal. The second decoder counts the pulse number of the high-frequency clock for each counting cycle, and the counting cycle includes a plurality of half periods of the ATIP FM signal.

Abstract: A digital signal processor (1045) arithmetically determines a comparison level for comparing each signal component by determining a comparison level of comparators (1033 and 1034) for comparing a fine clock mark signal such that a larger weight is assigned to the comparison level of the signal component already compared. The comparators (1033 and 1034) compare the fine clock mark signal with reference to a level set on a peak side and a level set on a bottom side. When digital signal processor (1045) receives the comparison signal from one of the comparators (1033 and 1034) prior to the comparison signal sent from the other, the digital signal processor produces a fine clock mark detection signal FCMT based on the comparison signal sent from a comparator (1047). Thereby, the clock can be accurately produced based on the fine clock mark signal even when a signal component having a larger amplitude than that of the fine clock mark signal is detected.

Abstract: A signal processing circuit, which extracts a signal superimposed on a reference signal and having a peak level higher than a level of the reference signal by a value greater than a given value, includes a first pulse generation part generating a first binary signal by binarizing a composite signal of the reference signal and the superimposed signal by using a given slice level, a noise elimination part eliminating noise from the first binary signal by using a cumulative length of time of each of polarities of the first binary signal, a second pulse generation part generating a second binary signal by binarizing the composite signal by using a slice level higher than the level of the reference signal by a value smaller than or equal to the given value, and a gate part outputting the second binary signal based on a signal output from said noise elimination part.

Abstract: A calibration method for a slice level of zero cross signal and a method of producing zero cross signal are disclosed. In this invention, the positive cycle and the negative cycle of the zero cross signal are sampled to obtain an error value related to the slice level due to asymmetry of the zero cross signal. By this invention, the asymmetry between the positive cycle and the negative cycle of the zero cross signal can be adjusted.

Abstract: A pre-pit detecting apparatus which, when a light beam is radiated onto an optical recording medium having a recording surface with pre-pits repeatedly formed between tracks, receives light reflected by the recording surface with first and second light receiving faces, obtains the push-pull signal corresponding to the light receiving signals for the first and second light receiving faces, and binarizes the push-pull signal by using a threshold value to generate a pre-pit detection signal. It is judged which area of a plurality of areas including at least a not-yet-recorded area corresponds to a position of the recording surface where the light beam is radiated is performed to judge. Then the threshold value is set in accordance with the judgement result.

Abstract: A defect detecting circuit generates a defect detection signal when the level of a sum signal obtained from an optical sensor in an optical pickup is lower than a predetermined level, and a gate circuit responds to the defect detection signal to set the level of a fine clock mark signal to zero, that is a difference signal obtained from the optical sensor in the optical pickup. A fine clock mark is thus distinguished from any defect such as scratch and a correct fine clock mark signal is accordingly generated. Alternatively, the value of a sum signal, which indicates the total amount of reflected light output from the optical pickup, is compared with a predetermined threshold. When the period in which the value of the sum signal is smaller than the threshold lasts for a predetermined threshold time period, it is determined that focus of an objective lens deviates from an optical disk and accordingly focus servo control is stopped.

Abstract: A binarizing device operates for controlling a slice level relative to a DC level of a reproduced signal in response to a slice level control signal to generate a controlling-resultant slice level, and for comparing the reproduced signal with the controlling-resultant slice level to convert the reproduced signal into a binary signal. A signal generating device operates for generating the slice level control signal in response to the binary signal. An offset detecting device operates for detecting an offset in a modulation-resultant-code pattern in response to the binary signal, and for generating code pattern offset information in response to the detected offset. An offset-responsive controlling device operates for implementing one of (1) changing a response characteristic of a loop formed by the binarizing device and the signal generating device and (2) suspending the slice level control by the binarizing device in response to the code pattern offset information.

Abstract: When a circuit that is likely to cause noise is enabled, a control circuit turns on a switch so that an inverter will be formed by one P-channel MOSFET and two parallel-connected N-channel MOSFETs. This helps enhance the current capacity of the inverter on its N-channel MOSFET side, and thereby lower the threshold voltage of the inverter.

Abstract: To correct a bit shift of binary data read from a medium and further enable correction of a bit error caused by mis-correction of the bit shift, a data recovery apparatus according to the present invention comprises: circuits for respectively correcting time at an intersection of a read signal and a slice signal; and a circuit for generating gray bits representing a time cell including an intersection, the time of the intersection being uncorrected and a time cell adjacent to the time cell, positioned in the direction of the intersection being shifted for correction.

Abstract: An information readout apparatus and an information readout method can efficiently correct the change in the size of the aperture. An optical disk 1 having a recording layer and a readout layer is used and the information recorded on the recording layer of the optical disk 1 is read out by irradiating a light beam onto the optical disk form head 2 and opening a detection window smaller than the area irradiated by the light beam in the readout layer. The resolution detecting section 15 of the apparatus detects the isolated mark recorded in the optical disk 1 in advance and then detects the resolution on the basis of the quotient obtained by dividing the difference X between the sample value Y near the peak of said isolated mark and the sample value adjacent to said sample value Y by said sample value Y near the peak, or X/Y.

Abstract: The invention has an object to provide a disk evaluation apparatus capable of performing a highly reliable disk evaluation even on a recording disk on which information is recorded in high density. Amplitude-limited read sample value sequence are obtained by limiting read sample value sequence to a predetermined amplitude limit value, the read sample value sequence obtained by sampling a read signal read out from the recording disk as timed to a clock having the same frequency as that of a channel clock. Where a gap between a maximum sample value and a minimum sample value of the amplitude-limited read sample value sequence is equivalent to a predetermined distance of high-frequency wavelength, the maximum sample value and the minimum sample value are increased thereby to obtain high-frequency enhanced read sample value sequence enhanced at the high region thereof.

Abstract: A method and apparatus detecting binary data from a signal read from an optical recording medium are provided. The apparatus detecting binary data includes a first signal processor nonlinearly converting the input signal based on the result of comparing an absolute value and a predetermined critical value of the input signal and a second signal processor detecting binary data from the nonlinearly converted signal.

Abstract: An apparatus of the present invention is an optical disk apparatus for irradiating with a laser beam an optical disk on which address marks are recorded at intervals based on a pulse width modulation method and for reproducing data from a reproduced signal based on reflected light. The apparatus includes: a pulse signal reproduction section for producing a reproduced pulse signal from the reproduced signal based on a threshold value; a threshold value production section for producing the threshold value based on the reproduced pulse signal; and a gate signal production section for producing an address gate signal at a timing when the address mark is reproduced.