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

Abstract: In a digital data reproduction apparatus for demodulating digital data from an optical recording medium, PRML (Partial Response Maximum Likelihood) signal processing effective to high-density recording/reproduction is carried out by using a half rate processing offset control means which performs data demodulation using half of the channel bit frequency, a half rate processing phase sync control means, a half rate processing adaptive equalization means, and a half rate processing maximum likelihood decoder, and the digital data recorded on the optical recording medium are reproduced while restoring signal components which are missing in the time direction, by linear interpolation or Nyquist interpolation. Therefore, digital data reproduction performance is improved, and power consumption is reduced.

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

Abstract: An optical disc apparatus reads the address information from an optical disc which has tracks and track spaces formed between tracks. The apparatus has an optical head which irradiates the disc with light and includes tracking detectors, divided into a first detector and a second detector in a track direction, detecting the light reflected from the disc and outputting detection signals, an adjusting circuit which adjusts amplitudes of the first and second detection signals and outputs the signals at a position where the address information is recorded, a differential amplifying circuit which outputs the differential signal which is the difference between the adjusted first and second detection signals, and an address detecting circuit which detects the address information based on the differential signal. As a result, the optical disc apparatus accurately detects whether information is being recorded on a correct track and improves the reliability during recording.

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

Abstract: A recording unit includes a laser diode emitting a recording light for information recording, a strategy signal generating unit generating a strategy signal, a correction signal generating unit generating the correction signal for offsetting a tilt of a waveform level of the recording light, and a driving signal generating unit generating a corrected driving signal for correcting the tilt of the waveform level of the recording light based on the strategy signal and the correction signal.

Abstract: An optical disk apparatus includes a generating unit which generates a wobble signal on the basis of a reflected light beam of an optical disk, a multiplying unit which multiplies the wobble signal and an oscillation wave, an integral processing unit which receives a multiplication result of the multiplying unit to integrate the multiplication result, an oscillating unit which generates the oscillation wave whose oscillation frequency is controlled on the basis of integral result of the integral processing unit, and a processing unit which processes information on the optical disk on the basis of the oscillation wave which is of a wobble PLL signal. In the optical disk apparatus of the invention, binarization is not performed unlike the conventional apparatus, and the wobble signal is compared to the oscillation wave in a signal area, so that the wobble PLL signal which is highly resistant to noise following the wobble is obtained.

Abstract: In an optical disc device that selectively implements a tracking servo and a spot position servo, a discontinuation cancellation unit is provided so that, when switching from the tracking servo to the spot position servo, and when switching in the opposite direction, the low-frequency component of the tracking drive signal and the low-frequency component of the spot position servo connect smoothly so that there is no step difference.

Abstract: An optical disc device serving as an information memory and reproduction device includes: an A/D converter for performing sampling to an analog signal to convert the analog signal into a first digital signal, which has been offset-adjusted, using an n times higher frequency than that of a channel clock (where n is 2 or a larger integer than 2); and a digital equalizer for digitally performing wave-form equalization of a reproduction signal, which has been converted into the first digital signal, and outputting a second digital signal. In this manner, wave-form equalization is performed to the digital signal which has been A/D converted, so that a small circuit configuration can be obtained. Moreover, oversampling is performed, thus equivalently improving a resolution when A/D conversion is performed.

Abstract: In the disclosed pulse shape modulation method, an amplitude modulation gain for a reproduced signal from an information recording medium that makes the jitter of the reproduced signal become the minimum is specified. Then, it is determined whether the amplitude modulation gain corresponding to the minimum jitter resides within a prescribed range. If the amplitude modulation gain corresponding to the minimum jitter is outside the prescribed range, the pulse shape of the pulsed laser beam is modulated.

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

Abstract: A circuit arrangement including means for determining a slicer level from incoming signal levels for slicing the incoming signal levels on the basis of the slicer level thus determined, includes a first and a second register circuit, which register circuits are connected to an output of a discriminator circuit. The discriminator circuit compares an incoming signal level with a set discrimination level and is adapted to apply an incoming signal level to the first register circuit if the incoming signal level is higher than the set discrimination level and to apply and incoming signal level to the second register circuit if the incoming signal level is lower than the set termination level. The first and the second register circuit are adapted to determine a register value of a least two different incoming signal levels consecutively applied to the register circuit. The circuit supplies a signal having a level which is a value determine from register values determined by the first and second register circuit.

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

Abstract: An apparatus for detecting a pre-pit signal at different laser power intensities of an optical disk drive. The apparatus includes an amplifier for receiving a push-pull signal acquired from an optical disk to generate an adjusted signal, a multiplexer for receiving the push-pull signal and the adjusted signal and selecting the push-pull signal or the adjusted signal as a slicing signal for output according to a power state signal, and a slicer for receiving the slicing signal and slicing the slicing signal according to a slicing level to generate the pre-pit signal. Thus, the apparatus only needs one set of slicer to correctly slice the pre-pit signal.

Abstract: A method for adjusting a reference level of an analog signal from a plurality of periodically sampled points includes the following steps. Firstly, a first level shift from an preliminary reference level to the last second sampled point within a specified period and a second level shift from the preliminary reference level to the last sampled point within the specified period is determined when one of a first level of the last second sampled point and a second level of the last sampled point is higher than the preliminary reference level and the other is lower than the preliminary reference level. Then, the preliminary reference level is moved toward the first level when an absolute value of the first level shift is greater than an absolute value of the second level shift, and the preliminary reference level is moved toward the second level when the absolute value of the first level shift is less than the absolute value of the second level shift, thereby defining an adjusted reference level.

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

Abstract: An optical disc playback apparatus capable of signal processing so that the above-noted new jitter does not appear even when a waveform equalizer is used is provided. A trimmer is inserted before the waveform equalizer, the maximum amplitude in the positive direction of the playback signal waveform and the maximum amplitude in the negative direction are limited so that amplitude in the positive direction and amplitude in the negative direction are substantially equal. Jitter in the playback signal can be improved as a result.

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: Methods and apparatus for recording on DVD-like recording media in which audio content is stored in a high-capacity multi-channel (e.g., six-channel) format are provided. Various channels may use various resolutions. A two-channel audio output may be derived from the multi-channel audio data stream during playback. To facilitate an accurate derivation, the mixing coefficients to be used in generating the derivation can be supplied along with the six-channel audio data.

Abstract: An optical disk apparatus for recording and reproducing data using a grove and a land of an optical disk. For data recording and reproducing using a groove, a groove focus position is used. For data recording and reproducing using a land, a land focus position is used. When shifting from a groove to a land or vice versa, a boost amount of an equalizer or power of a laser beam is temporarily increased for compensation of delay in response of a focus actuator.

Abstract: To provide an asymmetry correcting circuit capable of canceling an asymmetry simultaneously with quantization in an ADC and utilizing the dynamic range of the ADC effectively, and also to provide an information reproducing apparatus using such a correcting circuit.

Abstract: An optical recording apparatus for writing information on an optical recording medium in which a recording surface is covered with a transparent layer. The information to be written on the optical recording medium is converted into a pulse signal, and spherical aberration occurring due to an error of a thickness of the transparent layer is detected, the pulse signal being controlled in accordance with the detected spherical aberration.

Abstract: Light beams are irradiated from a head 2 onto an optical disc 1 including a recording layer and a reproduction (readout) layer to open, at the reproduction layer, detection window smaller than irradiation range of light beams to thereby read out recording information of the recording layer. A resolution detecting section 15 detects resolution on tile basis of signal level of a reproduction signal reproduced from the optical disc 1. A signal level detecting circuit 11 of the resolution detecting section 15 detects signal level of a specific mark length signal corresponding to specific mark length data in the reproduction signal which has been reproduced, and a resolution calculating circuit 12 calculates resolution on the basis of the detected signal level of specific mark length.

Abstract: To accurately detect whether the information is being recorded on a correct track and improve the reliability during recording. The invention relates to an optical disc apparatus for reading the address information from an optical disc which has tracks and track spaces formed between tracks. The apparatus comprises an optical head which irradiates the disc with light and includes tracking detectors, divided into a first detector and a second detector in a track direction, detecting the reflecting light from the disc and outputting detection signals, an adjusting circuit which adjusts amplitudes of the first and second detection signals and outputting the signals at a position where the address information is recorded, a differential amplifying circuit which outputs the differential signal which is the difference between the first and the second detection signals adjusted, and an address detecting circuit which detects the address information based on the differential signal.

Abstract: An optical disk comprising a substrate 4, and a plurality of tracks 269 to 273 formed on the substrate 4, wherein the plurality of tracks 269 to 273 include groove tracks 270, 272 consisting of a plurality of grooves mutually space apart by a fixed space, and land tracks 269, 271, 273 consisting of areas between the groove tracks, wherein the borders 14, 15 between the groove tracks and the land tracks represent information using the waveforms from their wobbling patterns, wherein the period of the wobbling waveforms of the borders 14, 15 are constant on each border, but the wobbling waveforms of the opposite portions of the borders across the track are shifted in phase by a predetermined phase difference.

Abstract: An apparatus for correcting asymmetry existing in a reproduction signal corrects the asymmetry by signal-processing the reproduction signal from an optical disk in digital form. The asymmetry correction apparatus changes the threshold values for counting the sign bits of the reproduction signal and the asymmetry correction values although discontinuous intervals exist on the optical disc, thereby providing an effect of easily varying an adaptive speed with respect to the discontinuous signal.