Abstract: A PLL circuit for generating a clock signal using a reference signal, the frequency of which is relatively low. The PLL circuit includes a first loop circuit for generating a first clock signal which is synchronized with a first reference signal. A second loop circuit generates a second clock signal which is synchronized with a second reference signal. The frequency of the second reference signal is sufficiently lower than the frequency of the first reference signal. The first reference signal is compared with the first clock signal to generate a first control voltage. The second reference signal is compared with the second clock signal to generate a second control voltage. The second loop circuit generates the second clock signal in accordance with the first control voltage and the second control voltage.

Abstract: An optical disc is described for recording data, which disc has a recording area for recording data encoded in optical marks at a recording density. The recording area has circular or spiral tracks provided with a servopattern comprising headers alternating with track portions. The headers contain position information encoded in preformed marks. The track portions comprise periodic characteristics, e.g. a wobble, to synchronise the data writing and reading operations. For reliably detecting the headers the phase of the periodic characteristics comprises a phase jump at a predetermined distance before each header.

Abstract: Maximal and minimal values represented by samples of a digital audio signal are detected. A number of samples from a sample representing a minimal value to a maximal-value-corresponding sample is detected. A number of samples from a sample representing a maximal value to a minimal-value-corresponding sample is detected. Calculation is given of a first difference between the maximal-value-corresponding sample and the immediately-preceding sample. Calculation is given of a second difference between the minimal-value-corresponding sample and the immediately-preceding sample. First and second coefficients are calculated from the detected sample numbers. The first coefficient and the first difference are multiplied to generate a first multiplication result. The second coefficient and the second difference are multiplied to generate a second multiplication result. The maximal value represented by the maximal-value-corresponding sample is incremented by the first multiplication result.

Abstract: An optical reproduction apparatus includes a light source which irradiates irradiation light onto a recording medium, the irradiation light being reflected by the recording medium to produce reflection light, a modulator which repetitively pulse modulates the irradiation light to produce irradiation light pulses, a photodetector which detects reflection light from the recording medium at more than two timings during each of the irradiation light pulses, and outputs detection signals respectively representative of the reflection light detected at the more than two timings during each of the irradiation light pulses, and an operation circuit which performs an operation between the detection signals outputted from the photodetector during each of the irradiation light pulses.

Abstract: A magneto-optical disk reproducing device includes a clock producing circuit, which, on the basis of a reproducing signal from recorded marks recorded in a magneto-optical disk, produces a timing offset from peak positions of the reproducing signal; an A/D converter, which samples the reproducing signal in accordance with the timing, and outputs a reproducing signal quantity; and a short mark signal quantity averaging circuit and a long mark signal quantity averaging circuit, each of which averages a plurality of reproducing signal quantities. When projecting a light beam onto a magneto-optical disk, the magneto-optical disk reproducing device controls light quantity of the light beam on the basis of a ratio between the respective values outputted by the foregoing averaging circuits.

Abstract: An apparatus for reproducing information that has been digitally recorded on a storage medium includes first and second waveform equalizers. The first waveform equalizer equalizes a read signal, corresponding to the information read out from the storage medium, thereby outputting a first equalized signal. The second waveform equalizer has an equalization characteristic different from that of the first waveform equalizer, outputs a second equalized signal and is selectively used to extract a read clock signal.

Abstract: A DVD-Audio which includes a data zone for storing data to be reproduced and an information zone for storing information on the data to be reproduced. The information zone includes directories of a video title set (VIDEO_TS) and an audio title set (AUDIO_TS). The AUDIO_TS directory includes information on an audio manager (AMG) having information on audio titles. The data zone includes the audio titles each having an audio title set information (ATSI) followed by a plurality of contiguous audio objects (AOBs). The ATSI includes a plurality of audio stream attributes each having an audio coding mode, first to third quantization bit numbers, first to third sampling frequencies and decoding algorithm information relating to the number of audio channels. Each of the AOBs includes a plurality of audio packs recorded with audio data corresponding to the decoding algorithm stored in the audio stream attribute.

Abstract: A digital AV signal processing apparatus includes a buffer for storing digital data input to the digital AV signal processing apparatus, and outputting the digital data as output digital data, a D/A converter for converting the output digital data to analog data, a voltage-controlled oscillator for generating a clock signal to control a conversion rate of the D/A converter, and a voltage-controlled oscillator controller for detecting a data amount of the digital data stored in the buffer, and controlling a frequency of the clock signal based on a deviation in the detected data amount from a first predetermined value and a time integral of the deviation value.

Abstract: An output device digitally stores data on a data carrier. The output device includes a reading unit, a data converter unit, and an output unit, provided with data reconstruction elements. Data to be reproduced can be processed by control data components contained in a start block. The control data components can be stored in a control data storage unit connected to the data reconstruction elements by way of a start block detector unit. This enables fast reproduction of large amounts of data, particularly digitized audio data.

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: An information system according to the invention comprises a record carrier (1) and a playback apparatus (20). The record carrier has information marks along a track (11) thereof and exhibits first variations caused by existence and nonexistence of the information marks along the track. The first variations represent an information signal recorded on said record carrier. The record carrier further exhibits second variations (W) caused by variations associated with the information marks. The phase of the second variations is coupled to the phase of the first variations.

Abstract: The invention relates to an additional information field DI in at least a group of headers 3 on an information carrier. The additional information field may be used to store information describing properties of the information carrier. This information can be stored in an information field DI of a single header or, alternatively, in the information fields DI of a sub-group of headers 3. When no information field DI is present in a second group of headers, a second synchronization field VFO2 may replace the information field DI.

Abstract: A DVD-Audio which includes a data zone for storing data to be reproduced and an information zone for storing information on the data to be reproduced. The information zone includes directories of a video title set (VIDEO TS) and an audio title set (AUDIO_TS). The AUDIO_TS directory includes information on an audio manager (AMG) having information on audio titles. The data zone includes the audio titles each having an audio title set information (ATSI) followed by a plurality of contiguous audio objects (AOBs). The ATSI includes a plurality of audio stream attributes each having an audio coding mode, first to third quantization bit numbers, first to third sampling frequencies and decoding algorithm information relating to the number of audio channels. Each of the AOBs includes a plurality of audio packs recorded with audio data corresponding to the decoding algorithm stored in the audio stream attribute.

Abstract: An optical information recording medium (1) is composed of a pit recording area (2), wherein various control information is recorded by a prepit, and an user recording area (3) having a guide groove formed in a groove format, and a phase depth for the prepit and the groove are approximately the same that the phase depth is less than or equal to &lgr;/10, wherein &lgr; is a wavelength for reproducing light source. A recording/reproducing apparatus (4) for the optical information recording medium (1) is composed of decoding means (12) for decoding information by detecting a tangential push-pull reproduced signal from the prepit recording area (2) and detecting an aggregated signal from the user recording area (3).

Abstract: An interface circuit that is suitable for use in a recording system and a system for manufacturing optical disks, which is provided with this interface circuit, have an analog-side interface circuit 100A and a digital-side interface circuit 100B, these interface circuits being optically linked, either acoustically, or electromagnetically, so as to enable mutual transmitting and receiving of a digital signal therebetween. The interface circuits 100A and 100B, which serve as a receiving side with respect to the other sides, detect the logic of the digital signal with a timing that does not include the jitter component that is included in the transmitted digital signal, the detected digital signal logic being used as the basis for generating a new digital signal.

Abstract: A data recording and reproducing method for an optical disk data storage system to record data compressed at different data compression rate according to an operator's specification, and to reproduce the recorded data by decompressing. According to the operator's indication, the data is recorded at certain data compression rate in indicated area. The information of the data compression rate and the recorded area is stored as a table of contents (TOC) data. The TOC data is reproduced and stored in a memory after the optical disk is loaded. The recorded data is reproduced by selecting a decoding circuit to decompress the data. The decoding circuit is selected by referring the TOC data to identify data compression rate of the recorded data. Also the TOC data is referred to identify read-in and read-out region of the recorded data. The position of a pick-up when the data recording is started and ended, is recorded as the TOC data to provide random access capability for the data reproduction.

Abstract: According to the present invention, in a disk-shaped recording medium such as an optical disk and the like, a reference clock with a frequency corresponding to a reproduction frequency of data reproduced from a data recording region is divided in accordance with a ratio between a record density of a header region where pre-formatted data including a sector mark for indicating a leading position of a sector is recorded, and a recording density of a data recording region subsequent to the header region, so as to produce a sampling clock. Then, by use of thus-produced sampling clock, the sector mark is detected. This structure enables, even if the header region has a recording density different from the recording density of the data region, to use a sector mark detector having the same structure as of a sector mark detector which is employed in the case where the header region has the same recording density as that of the data region and therefore a reference clock is used.

Abstract: In an apparatus for recording information to an optical recording medium, a laser beam is irradiated to and reflected from the medium. A photodetector detects the light quantity of the irradiated or reflected light beam, and the detected laser beam is subjected to the signal processing. Then, a sampler samples it at the timing of a sampling pulse supplied from a sampling pulse generator. Then, a controller controls the laser power according to the sampled laser beam. A pulse timing setting unit sets and adjusts the timing of the sampling pulse by taking into account the response time in the propagation path of the laser beam from the start of the irradiation to the sampling. Thus, the laser power can be monitored correctly, and it can be optimized so as to stably and reliably reproduce an address signal and to generate a servo signal while data is recorded.

Abstract: A recording information reproducing apparatus which can reduce a residual phase error in a read signal caused due to an influence by a time base fluctuation. A read signal read out from a recording medium is sampled at a timing according to a clock signal, thereby obtaining a read sampling value sequence. An oscillation signal whose phase is synchronized with the read sampling value sequence is formed as a clock signal. A sampling value sequence which is obtained at a time point when the phase in the read sampling value sequence is deviated by an amount corresponding to a phase error occurring in the read sampling value sequence is obtained as a corrected read sampling value sequence. By performing a decoding process to the correction read sampling value sequence, information data is obtained.

Abstract: To more precisely digitize a signal read from a data storage medium into a binary value to reduce the rate of occurrence of bit error in reproduction. A phase difference of the intersecttion between a signal read from a data storage medium and a slice signal is evaluated to select a probable time cell in which the intersection should be contained for more precisely digitizing the read signal into a binary value.

Abstract: Address information indicative of a certain recording/reproduction position is recorded twice (first address, second address) in an optical disk. Second phase control means makes sampling timings for digitizing the first address have optimal phases. Third phase control means makes sampling timings for digitizing the second address have optimal phases. The second and third phase control means are formed with different circuits, respectively.

Abstract: Disclosed is a method of recording/reproducing information signals at an access speed in the order of &mgr;s, a recording density of 1 to 10 GBs/cm2, and a data transfer rate in the order of Gbit/sec without breakage of the data. The method includes the steps of: making a head device face to a memory medium having a flat recording surface, the head device including a plurality of head elements two-dimensionally arranged each of which has at its leading end a flat portion having an area of 0.1 &mgr;m2 or less; moving the head device relative to the memory medium a distance more than a gap between two adjacent ones of the head elements; and recording an information signal at a specific position of the recording surface at a recording density of 1 Gbit/cm2 or more, or reproducing an information signal previously recorded on the recording surface al a specific position by the head device.

Abstract: The present invention is aimed at providing an optical disk, an optical disk device, and an optical disk reproduction method, for allowing for stable and efficient reading of address information. The optical disk includes a plurality of tracks each divided into a plurality of recording sectors. Each of the recording sectors includes a header region. The header region includes address information for identifying the position of the corresponding recording sector and address synchronous information for identifying the recording position of the address information for bit synchronization. The address information has been modulated using a run length limit code of a maximum inversion interval of Tmax bits (Tmax is a natural number), and the address synchronous information includes two patterns of which inversion interval is (Tmax+3) bits or more, so that the reproduced signal of the address synchronous information is distinguished from the reproduced signal of other information.

Abstract: An asymmetry detection apparatus includes: a clock signal generator for generating a clock signal based on a reproduced signal; an A/D converter for sampling the reproduced signal in synchronization with the clock signal; a determiner for determining whether a level of each of a plurality of sampled data obtained by the sampling operation is equal to or greater than a predetermined level; and a detector for detecting asymmetry in the reproduced signal by using predetermined ones of the sampled data based on an output from the determiner.

Abstract: A sector mark detecting circuit for detecting a sector mark on an optical storage medium includes a binarizing circuit which binarizes a reading signal of an optical head in accordance with a predetermined detection parameter and is capable of changing the detection parameter. A recognizing circuit is adapted to recognize a sector mark from an output of the binarizing circuit, and a control circuit is adapted to measure an optimal value of the detection parameter of the binarizing circuit and control the detection parameter of the binarizing circuit to the optimal value. A sector mark detection rate is thereby enhanced.

Abstract: An information recording and reproduction apparatus for a magneto-optical medium includes a synchronizing signal generation circuit for generating a synchronizing signal to provide a pulsed laser beam at the time of reproduction according to an internal clock obtained from a reproduction signal. The laser beam is driven on/off according to the synchronizing signal at the time of reproduction to have the laser spot on the signal plane prevented from being enlarged, so that the reproducible domain is smaller than the domain of when a laser beam is continuously emitted. In reproduction, an optical superresolution method is applied simultaneous to provision of a pulsed laser beam to allow reproduction of higher density. An external synchronizing signal generation circuit for generating an external synchronizing signal according to a wobble on a surface of a recording medium can be used instead of a synchronizing signal generation circuit according to an internal clock.

Abstract: An optical information reproducing method for demodulating the information recorded on a recording medium by a viterbi decoding method, in which data can be demodulated with high accuracy even if the recording power has undergone variations at the time of recording the information. Data recorded on the recording medium after modulation in which the minimum length between transitions is limited to not less than 2 is decoded using the viterbi decoding method. A specified signal recorded on the recording medium is used for setting the reference value used for viterbi decoding.