Abstract: A method for optical drive decoding of address in pre-groove (ADIP) data is provided to decode an input wobble signal to an ADIP unit signal. The method includes generating a wobble carrier frequency signal having the same phase with the wobble signal, multiplying the wobble carrier frequency signal by the input wobble signal to generate a product signal, accumulating the value of the product signal in each clock to generate a quotient summation signal, determining the phase change of the input wobble signal according to the value of the quotient summation to generate a phase change signal, and generating the ADIP unit signal by comparing the phase change signal with a plurality of ADIP patterns.

Abstract: A PLL circuit having an analog-to-digital converter; a phase error detecting circuit; and an oscillator, in which the phase error detecting circuit includes: phase error detecting means detecting a phase error from a data stream signal and a data stream signal 1 clock cycle earlier; absolute value comparing means detecting an absolute value of the phase error detected exceeding a predetermined threshold; holding means holding a polarity of the phase error, as of a timing of the detection by the absolute value comparing means, for a period of the detection; anticoincidence detecting means detecting anticoincidence between the polarity held by the holding means and a polarity of the phase error detected by the phase error detecting means; and polarity inverting means that provides the phase error detection signal by inverting the polarity of the phase error in detection of anticoincidence, or without inverting the polarity in detection of no anticoincidence.

Abstract: An optical disc reproducing apparatus includes an analog-to-digital (A/D) converter which converts an analog signal obtained from an optical disc to a digital signal; an asymmetry compensator which detects and corrects an offset of the digital signal; a phase locked loop (PLL) which estimates a clock of the digital signal and compensates for a frequency error; a binary module which converts the digital signal to binary data; an equalizer which equalizes a particular frequency of the digital signal; and a channel identifier which detects a reference level of the binary module, based on an input signal of the equalizer.

Abstract: An optical disk apparatus and a recording parameters setting method are provided to more effectively execute recording parameter learning during data recording on the optical disk, thereby shortening the time required for setting an optimum recording parameter. A phase error detection unit detects a phase error amount from a reproduction signal of actual data being recorded. A phase error adjustment unit adjusts recording parameters (recording strategy) set by a recording parameters setting unit based on the detected phase error amount. The phase error amount detection is executed simultaneously with a verify process of the actual data. If a verify process judgment results says that a target quality is not attained, test writing by a test signal is not executed but the adjustment of recording parameters is conducted on the basis of the phase error amount.

Abstract: Disclosed is a bit-detection arrangement able to convert an analog signal (AS) having an amplitude into a digital signal (DS) representing a bit sequence from which the analog signal (AS) is derived. The bit-detection arrangement has a phase detector which detect the phase difference between a quantized analog signal and a clock signal C2. The phase difference is sampled by an AD converter. The AD converter can sample at a relatively slow rate as the phase difference is a low frequency signal. The sampled phase difference is fed to a digital PLL which outputs a phase signal PHI. The phase signal and the quantized analog signal are used to recreate the digital signal (DS).

Abstract: An apparatus for generating a wobble clock includes an operation circuit for receiving a wobble signal and counting cycles of an oscillating signal during a cycle of the wobble signal to derive a cycle value and for comparing the cycle value with a preset cycle value to output a first protection signal, and a phase-locked loop circuit connected to the operation circuit for receiving the wobble signal, the wobble clock and the first protection signal, and determining whether the wobble clock is to be synchronized with the wobble signal according to the first protection signal.

Abstract: A method of identifying ADIP information through counting identical bits and different bits includes generating a wobble clock according to a wobble signal, generating a calculation result according to the wobble signal and the wobble clock, sampling the calculation result to generate a sampling signal and comparing each bit of the sampling signal with each bit of a bit stream containing an ADIP data, counting different bits corresponding to a predetermined logic value for generating a first bit count, and counting identical bits for generating a second bit count, and determining whether the calculation result corresponds to the ADIP data according to the first bit count and the second bit count.

Abstract: A method for optical drive decoding of address in pre-groove (ADIP) data is provided to decode an input wobble signal to an ADIP unit signal. The method includes generating a wobble carrier frequency signal having the same phase with the wobble signal, multiplying the wobble carrier frequency signal by the input wobble signal to generate a product signal, accumulating the value of the product signal in each clock to generate a quotient summation signal, determining the phase change of the input wobble signal according to the value of the quotient summation to generate a phase change signal, and generating the ADIP unit signal by comparing the phase change signal with a plurality of ADIP patterns.

Abstract: An optical disk device that records and reproduces information on/from a recordable optical disk is provided.

Abstract: An apparatus and a method for generating a write pulse to be written on an optical storage medium using a ring oscillator are provided. The apparatus includes a ring oscillator outputting n tap signals, and a pulse generation unit converting a channel clock signal to have as long a cycle as an interval among the n tap signals, and generating a write pulse following the converted channel clock signal.

Abstract: A recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, capable of preventing unauthorized duplication of data streams, written thereon, onto another medium, such as a BD-RE or BD-R, which includes physical mark information, and to methods and apparatuses for forming, recording, reproducing, and restricting playback of the recording medium to prevent unauthorized duplication.

Abstract: A record carrier (1) has a servo track (4) indicating an information track (9) intended for recording information blocks represented by marks, the servo track (4) having a periodic variation of a physical parameter at a first frequency and modulated parts for encoding record carrier information. The modulated parts have a bit synchronization element constituted by a phase modulation of the periodic variation and a data part having data bits of the record carrier information encoded by direct digital modulation. Alternatively, the modulated parts include a second frequency, which is substantially different from the first frequency, for encoding data bits of the record carrier information, the second frequency being a integral multiple N of the first frequency. A recording and/or playback device has a device for recording/reading the information blocks and for reading the record carrier information.

Abstract: In order to generate a clock signal (fT1) that is coupled to a reference signal (FBAS), especially to an analog video signal, a free-running clock pulse (fT1) is generated from a high-frequency clock pulse (f0) and the reference signal (FBAS) is digitized therewith. In addition, a second clock pulse (fT1) is generated from the high-frequency clock pulse (f0) and the phase deviation between the first clock pulse (fT2) and the second clock pulse (fT1) is determined. The digitized sampling values of the reference signal (FBAS) at the first clock frequency (fT1) are converted, according to the phase deviation determined, into corresponding digitized sampling values having the second clock frequency (fT1) and are used as a target specification for generating the second clock pulse (fT1) thus coupled to the reference signal.

Abstract: An optical recording method for recording mark length-modulated information on a recording medium by using a plurality of recording mark lengths. The optical recording method comprises the steps of: when a time length of one recording mark is denoted nT (T is a reference clock period equal to or less than 25 ns, and n is a natural number equal to or more than 2), (i) dividing the time length of the recording mark nT into ?1T, ?1T, ?1T, ?2T, ?2T, . . .

Abstract: A multi-value data recording and reproducing device is provided that can accurately eliminate interference among codes through waveform equalization when reproducing information from a reproduction signal having levels multi-valued through modulation of the areas of recording marks on an optical information recording medium. This multi-value data recording and reproducing device is embodied by a multi-value data detecting circuit that varies the sizes of the recording marks in accordance with multi-value data (0, 1, 2, . . . , (m?1): m being an integer of 3 or greater) on the optical information recording medium, and detects the multi-value data through predetermined signal processing on signals obtained by scanning the recording marks with an optical spot.

Abstract: A method and circuit for providing a playback signal which is compensated for time delay. The circuit includes a time delay compensator for detecting a time difference between outputs of a photodetector and temporally matching part of the outputs of the photodetector and another part of the outputs of the photodetector, between which the time difference occurs, to compensate for time delay between different outputs of the photodetector, and an operational unit for summing the part of the outputs of the photodetector, which is compensated for the time delay, and the other part of the outputs of the photodetector to provide a playback signal. Accordingly, the circuit compensates for the time delay between the outputs of the photodetector, thereby increasing the degree of modulation of the data playback signal.

Abstract: A method for protecting a phase lock loop (PLL) in an optical system is disclosed. The disclosed method will determine whether the currently reading data is erroneous and then maintain the frequency currently locked by the PLL circuit when the waveform lengths of the EFM signal in a detecting window contain at least one waveform length longer than 11T and at least one waveform length shorter than 3T. Otherwise, the PLL circuit will adjust the locked frequency according to the waveform length of the detected EFM signal so that the system clock frequency can be adjusted based on the locked one. In addition, when the optical system seeks tracks for reading required data under a constant angular velocity (CAV) modulation mode, the PLL circuit will increase the locked frequency gradually as the pick-up head moves towards the outer tracks of the optical disc, and decrease the locked frequency gradually as the pick-up head moves towards the inner tracks of the optical disc.

Abstract: An optical disc reproduction apparatus includes a sector detection section for detecting a sector; a sector reproduction time measuring section for measuring a reproduction time of the sector, and outputting sector reproduction time data which represents the measured reproduction time of the sector; an unrecorded portion detection section for detecting an unrecorded portion which is a portion of the sector in which no data is recorded; an unrecorded portion time measuring section for measuring a reproduction time of the unrecorded portion, and outputting unrecorded portion time data which represents the measured reproduction time of the unrecorded portion; and a sector determination section for determining whether the sector is an unrecorded sector or not, based on a relationship between the sector reproduction time data and the unrecorded portion time data, the unrecorded sector being a sector which is in an unrecorded state.

Abstract: The invention relates to a polycarbonate composite material which can be thermoplastically shaped and which comprises at least two layers. The invention is characterised in that at least one layer comprises an LOI value of lower than 29 and at least one layer comprises an LOI value of higher than 29. The invention also relates to methods for producing said material, the use of the same and flame-proof polycarbonate moulded parts.

Abstract: A method for reading data from high density optical recording media is disclosed. In this method, a value is generated from a formula Pr/(&lgr;/NA), wherein Pr is light source reading power; &lgr; is wavelength; and NA is numerical aperture, when the value is in a range of about 1.15 to about 8 mW/&mgr;m, a recording mark within the high density optical recording medium which is smaller than a resolution limit of an optical system is detected.

Abstract: An aligned write signal generator with alignment calibration utilizes an alignment unit to align a plurality of write signal. The aligned write signal generator includes a write signal generator for receiving an EFM signal and converting the EFM signal into a plurality of write signals according to a write strategy waveform generating rule, an alignment unit for receiving the plurality of write signals, aligning the write signals and outputting phase adjusted write signals, and a phase calibration unit for receiving the phase adjusted write signals, detecting phase error between the phase adjusted write signals, and outputting phase control signals. The alignment unit further receives the phase control signals to adjust the delay time of each write signal.

Abstract: A high speed, high accuracy parallel/serial conversion circuit, wherein a PLL circuit 50 receives as input and locks a clock CLK, and supplies the same to different parts of an apparatus; the PLL circuit 50 controls a 16-tap ring oscillator 60 to shift the phase of a clock frequency-locked to a reference clock so as to generate 32 types of phase shift pulses CK0 to CK31 shifted in phase by increments of {fraction (1/32)} of the clock width from the reference clock by the differential outputs of the 16 taps and supplies the same to a P/S conversion circuit 70; and the P/S conversion circuit 70 generates fine width pulses with {fraction (1/32)} pulse widths based on the 32 types of phase shift pulses shifted in phase by increments of {fraction (1/32)}. Further, the fine width pulses are used to convert parallel signals output from a RAM 30 and a decoder 40 to a serial signal.

Abstract: A record carrier (1) is described comprising a servo track (4) indicating an information track (9) intended for recording information blocks represented by marks having lengths expressed in channel bits, which servo track (4) has a periodic variation of a physical parameter. The periodic variation is modulated for encoding record carrier information, such as addresses. The modulation is a bi-phase modulation in which a data bit of the record carrier information is encoded by a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase. A recording and/or playback device has a demodulator for retrieving data bits of the record carrier information from a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase.

Abstract: A method and apparatus for detecting information recorded as a phase-modulated wobble along a track of an optical disk, whereby a reference phase section is recorded with wobble having a predetermined reference phase and whereby respective polarities of phase integration values obtained by synchronous detection of phase-modulated unit sections following the reference phase section, in a playback wobble signal, are compared with the polarity of a reference phase integration value obtained for the reference phase section, to thereby detect respective bit states expressed by the phase-modulated unit sections.

Abstract: A PLL circuit is disclosed which extracts phase difference information of a high S/N ratio from a readout signal uses the phase difference information for PLL control. An A/D converter samples the input signal to produce a digital signal. A pattern string detector identifies a type of an input pattern string formed from a plurality of successive sample values successively outputted from the A/D converter and outputs pattern string identification information which indicates an identification result. A phase difference generator outputs phase difference information which indicates a phase error of the output of the A/D converter based on the pattern string identification information and the output of the A/D converter. A loop filter, a D/A converter and a voltage controlled oscillator generate a clock signal from the phase difference information to control the sampling timing of the A/D converter.

Abstract: An analog filter is placed at a stage previous to an analog-digital converter (ADC), and a waveform equalizer is placed at a stage subsequent to the ADC. The sampling frequency of the ADC is determined by a clock generation section according to the relationship between the bit rate of an input reproduction signal and the characteristic of the analog filter. The number of taps is changed according to the relationship between the bit rate of the input reproduction signal and the characteristic of the analog filter. Further, the tap coefficients of a waveform equalizer are changed according to the height of the frequency band of the input reproduction signal. A waveform evaluation section generates a signal that evaluates a waveform equalization signal transmitted from the waveform equalizer to a Viterbi decoder, whereby adaptive waveform equalization is realized.

Abstract: A method of accelerating a track-following process for an optical drive. The optical drive has a motor and a pickup head for reading information from an optical disc therein. According to the method, an input signal with a first frequency and a first phase is received by detecting the rotation speed of the motor and a radius of the information track where the pickup head locates on the optical disc. When either frequency or phase of a data phase locked loop (DPLL) frequency signal of the optical drive is different from the first frequency and the first phase, the DPLL frequency signal is adjusted to the first frequency and the first phase. With the adjusted DPLL frequency signal, data from the optical disc is read correctly.

Abstract: The invention provides a method and apparatus for generating delays to shift edges of an EFM data stream from an EFM modulator for a CD-R and CD-RW write encoder. EFM data pulse edges may be delayed in increments of about {fraction (1/32)} Tefm where Tefm is the code rate clock of an EFM data stream output. The delays are generated by a synthesizer running at four times the EFM code rate. The synthesizer may be built using a four-stage ring oscillator. Delays are selectable based upon the write strategy matrix in coarse increments of ¼ T and fine increments of {fraction (1/32)} T. For the coarse delay, the EFM data may be passed through a four stage shift register running at Fsynth, where Tefm=4×Fsynth, allowing for a coarse delay selection of ¼ Tefm.

Abstract: A sample of an information signal is periodically generated in response to a sampling clock signal. A level relation between successive ones of the information-signal samples is detected. A peak-corresponding sample is detected among the information-signal samples in response to the detected level relation and in response to a prescribed level range containing a “0” level. A level represented by the detected peak-corresponding sample is outside the prescribed level range. Calculation is made regarding a level difference between information-signal samples immediately preceding and immediately following the detected peak-corresponding sample. A phase error signal is generated in response to the calculated level difference. The sampling clock signal is controlled in response to the phase error signal to lock the sampling clock signal in phase with the information signal.

Abstract: If adequate setup time or hold time cannot be provided between a recording clock signal and modulated signal during the use of a laser control integrated circuit for generating a recording strategy from the recording clock signal and modulated signal to drive a laser diode, the disk recording information becomes erroneous. To solve this problem, the present invention provides the laser control integrated circuit input stage for the recording clock signal and modulated signal with variable delay devices that can vary the phases of these signals. The variable delay devices control the delay amounts of the variable delay devices in accordance with disk recording information error and optimize the phase relationship between the recording clock signal and modulated signal.

Abstract: An optical recording method for recording mark length-modulated information on a recording medium by using a plurality of recording mark lengths. The optical recording method comprises the steps of: when a time length of one recording mark is denoted nT (T is a reference clock period equal to or less than 25 ns, and n is a natural number equal to or more than 2), (i) dividing the time length of the recording mark nT into &eegr;1T, &agr;1T, &bgr;1T, &agr;2T, &bgr;2T, . . . , &agr;iT, &bgr;iT, . . .

Abstract: A method of recording information on an information medium, especially on an optical recording medium with light. It has been hard to determine optimum power accurately due to the influence of the linearity and the mark length dependence on rewrite deterioration when a write parameter calibration on a phase change optical disk is performed by a conventional asymmetry method prior to information recording. According to the present invention, a single pattern or a random pattern is recorded on an information medium, and the difference between the clock and the data edge is detected using a reproduced signal. On the basis of this difference, the threshold power of the recording is determined and multiplied by a constant to optimize the recording power.

Abstract: An optical disk device that records and reproduces information on/from a recordable optical disk is provided.

Abstract: A multi-value data recording and reproducing device is provided that can accurately eliminate interference among codes through waveform equalization when reproducing information from a reproduction signal having levels multi-valued through modulation of the areas of recording marks on an optical information recording medium. This multi-value data recording and reproducing device is embodied by a multi-value data detecting circuit that varies the sizes of the recording marks in accordance with multi-value data (0, 1, 2, . . . , (m−1): m being an integer of 3 or greater) on the optical information recording medium, and detects the multi-value data through predetermined signal processing on signals obtained by scanning the recording marks with an optical spot.

Abstract: The write-timing calibration involves (1) writing a calibration data sequence referenced to a physical timing clock (such as a wobble clock on a DVD disk), (2) measuring the timing offset or phase offset between the calibration data sequence and the clock, (3) writing a test data sequence using the same or a different recording device, (4) measuring the timing offset or phase offset between the test data and the clock, (5) comparing the timing offsets of the calibration and test data sequences, with respect to the clock, (6) iteratively adjusting the timing of the beginning of the write process, and repeating steps (3), (4) and (5) until the timing offsets are equal to within a defined tolerance, and (7) Adjusting the delay of the write driver relative to the clock by the amount determined in step (6), for equal timing offsets of the calibration and test data sequences.

Abstract: An apparatus and a method for generating a write pulse to be written on an optical storage medium using a ring oscillator are provided. The apparatus includes a ring oscillator outputting n tap signals, and a pulse generation unit converting a channel clock signal to have as long a cycle as an interval among the n tap signals, and generating a write pulse following the converted channel clock signal.

Abstract: A data reproduction system, which determines reproduced data based on comparison results of path metrics calculated in accordance with a Viterbi algorithm based on branch metrics calculated from expected values and a sampled value of a readout signal, includes an expected value setting unit for variably setting the expected values used for a calculation of the branch metrics in order to perform a Viterbi detection process without being easily affected by the transient response, offset variation, phase error and nonlinear torsion component of the readout signal. The readout signal is obtained from a recording medium on which data is recorded in accordance with a recording signal of a partial response waveform, the expected values are determined by the partial response waveform, and the sampled value is obtained by sampling the readout signal at a predetermined frequency.

Abstract: When data recording on a disk is interrupted due to the termination of data reception and recording is then resumed with reception of new data, specific data generated by a data generator (23) is added to the last block of the data received immediately before recording interruption and to the first block of the data received immediately after release of recording interruption to secure the interleave length of the aforementioned last and first blocks, respectively. Thus, the data in the last block of the received data is modulated into recording data and is recorded on the disk before recording interruption. Disk recording is resumed with recording data obtained by modulating data of the first block of the newly received data so that new recording data can be recorded so as to be continuous to the terminal end of the data already recorded on the disk without employing any link blocks.

Abstract: A laser beam is irradiated from a pickup head on a disk. Light reflected by the disk is detected by the pickup head. The data is binarized by a data slice circuit, and a synchronizing clock and a synchronizing signal are extracted by a PLL and synchronizing signal separation circuit. The center frequency of the voltage controlled oscillator of the PLL and synchronizing signal separation circuit continuously changes according to a control voltage. A disk motor control circuit continuously changes the rotation speed of the disk in accordance with a control instruction from a system controller. The disk rotates at the highest rotation speed at which a data read operation is normally performed. The characteristics of the voltage controlled oscillator change in correspondence with the rotation speed of the disk.

Abstract: A record carrier is described comprising a servo track indicating an information track intended for recording information blocks represented by marks having lengths expressed in channel bits, which servo track has a periodic variation of a physical parameter. The periodic variation is modulated for encoding record carrier information, such as addresses. The modulation is a bi-phase modulation in which a data bit of the record carrier information is encoded by a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase. A recording and/or playback device has a demodulator for retrieving data bits of the record carrier information from a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase.

Abstract: In an optical disc having tracks for recording user data such as a rewritable type optical disc using a phase change medium or a magneto-optical medium, or a write-once type optical disc using a pigment based medium, a wobble portion waved in a radial direction of the optical disc and a non wobble portion which is not waved are provided on the tracks, sub information which is data other than the user data is recorded on the tracks by using a combination of the wobble portion and the non wobble portion, a logic value of each bit is represented by a pair of the wobble portion and the non wobble portion, and the phase of wave in the wobble portion when a bit is a logical value of “0” and the phase of wave in the wobble portion when a bit is a logical value of “1” are different.

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

Abstract: This invention prepares two control voltage to be input to a VCO circuit. The first control voltage is used to continuously change the oscillation frequency of the VCO circuit. The second control voltage is used to continuously change the first control voltage/oscillation frequency characteristics. The invention also includes a phase detecting circuit for comparing the phase of the data read from a disk with that of the output from the voltage-controlled oscillator, a frequency detecting circuit for comparing the frequency of the data read from the disk with that of the output from the voltage-controlled oscillator, a first filter circuit for equalizing signals representing the detection results obtained by the phase detecting circuit and the frequency detecting circuit, and a second filter circuit for extracting only a low-frequency component from the output from the first filter circuit. The output from the first filter circuit is used as the first control voltage.

Abstract: A pulse width control circuit is used to control the pulse with of a modulation signal to be written to a recording medium, such as a CD-R. The circuit controls both the leading and trailing edges of the modulation signal. The circuit includes a first delay circuit including multiple series connected first inverters for delaying the modulation signal and generating multiple first delay signals. The first delay signals are input to a first selector, which selects one of the first delay signals. A first logic circuit receives the selected first delay signal and the modulation signal and performs a first logic operation. The output of the first logic circuit is input to a second delay circuit, which includes multiple series connected second inverters for delaying the first logic circuit output signal, and generating multiple second delay signals. A second selector selects one of the plurality of delayed logic signals in accordance with the second selection signal.

Abstract: This invention achieves high-density recording while preventing recording units from overlapping. Recording is done to form a gap between predetermined recording units. Since this gap is formed, even when a rotation driving mechanism of a medium suffers rotation nonuniformity, two neighboring recording units never overlap each other, and destruction of recording data can be prevented.

Abstract: The life of a rewritable information carrier such a CD-E covered by a phase-change recording layer is extended by varying the manner of representing information of an information block, for subsequent recordings, in the same portion of the record carrier. The manner can be changed, for example, by shifting the initial position at which representing information is written along the track over a distance randomly selected within predefined boundaries; or by writing a varying amount of information representing information from the end of the block before the start of information from the beginning of the information block to rotate the information in the track; or by scrambling the information in a varying manner such as using different keys. The manner of representation can be changed, for example, for each subsequent recording on the same portion of the record carrier. This causes different patterns to be recorded in the same portion, even if the same information is recorded in that portion of the track.

Abstract: An improved writing strategy for CAV writing of CD-RW is proposed and uses similar strategy as the CLV writing. The writing strategy comprises step of setting a duty ratio; obtaining a laser writing pulse duration corresponding to the duty ratio; and obtaining the duty ratio for each writing speed according to the laser writing pulse duration.

Abstract: In a circuit to provide a high precision delay signal, an oscillator generates oscillator pulses, each with an oscillator period. A counter, in response to an enable signal, counts the oscillator pulses and outputs a count signal. The enable signal is a reference clock signal having a reference-clock period that is greater than the oscillator period. A delay generator delays an input signal to provide a sequence of incrementally delayed delay-signals. A multiplexor, in response to the count signal, selects one of the delayed signals. In another aspect of the invention, a disc controller uses the circuit to provide a high precision delay to a write data signal. Another aspect of the invention provides a method of providing the high precision delay.

Abstract: The object of the present invention is to provide an optical recording/reproducing method and apparatus that accurately record data blocks onto an optical disk in a seamless formation while effectively reducing the deterioration of recording properties of the disk. The recording properties of the disk may deteriorate when data is repeatedly written to a same data block of the disk. In the optical recording/reproducing method and apparatus of the invention, a read clock signal is generated in response to recorded data on an optical storage medium. A write clock signal is generated in response to a position information carrying signal detected from the storage medium. A phase difference between the read clock signal and the write clock signal is detected when writing data blocks to the storage medium in a seamless formation. It is determined whether a phase of the write clock signal is delayed or advanced based on the phase difference.

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