Abstract: A method of verifying that a disc recording and reproducing apparatus normally analyzes defect management area (DMA) information in a read or write mode, and a test apparatus for performing the method. The method includes operating the recording and reproducing apparatus in a read or write mode, using a test disc with test reference information, and checking whether the recording and reproducing apparatus operates in the read or write mode to verify the DMA information analyzing function of the recording and reproducing apparatus. Accordingly, a DMA information analyzing function of the disc recording and reproducing apparatus in the read or write mode can be tested.

Abstract: An information storage apparatus includes a mark reading section for reading a mark written on an information storage medium. A recording state changing section is provided for changing a recording state in an adjacent region situated next to a region from which the mark reading section fails to read a mark, so as to reduce cross talk caused by the adjacent region. The mark reading section reads the mark in the failed region again after the recording state changing section changes the recording state in the adjacent region.

Abstract: A content recording/erasing apparatus includes a hard disk. An unnecessary MPEG file recorded on the hard disk is intermittently erased part by part in parallel with a normal recording process. It is noted that prior to a start of erasing the unnecessary MPEG file, time length data relating to a total amount of an actual remaining amount of the hard disk and the unnecessary MPEG file is set in a remaining amount register, and a setting value is periodically subtracted.

Abstract: The present invention is directed to a recording/reproducing apparatus having a Read After Write function which simultaneously performs recording operation and reproduction operation, and is such that, in a reproducing system (120) of a tape streamer (100) which performs Read After Write operation for signals through a magnetic tape (105), the apparatus serves to distribute reproduction signals obtained from the magnetic tape by a first data distribution switch (133) to store signals thus distributed into frame memories (135A), (135B) of 2 channels, and to distribute a recording signal from a recording system (110) by a second data distribution switch (134) as cause signals of crosstalk signals included in reproduction signals to store signals thus distributed into frame memories to generate pseudo crosstalk signals of respective channels by crosstalk cancellers (136A), (136B) on the basis of reproduction signals and cause signals of respective channels which are read out from the frame memories to cancel, ev

Abstract: The method of sampling wobble components of the present invention is capable of realizing a disk drive unit, which can write data at high speed, and reducing manufacturing cost of the disk drive unit. The wobble components are sampled from laser beams reflected from an optical disk so as to write data on the optical disk. The laser beams are low power laser beams for reading data and high power laser beams for writing data. The method is characterized in that the wobble components of the reflected low power laser beams and the reflected high power laser beams are continuously sampled.

Abstract: A recording medium controlling apparatus for reading/writing data from/to a recording data area as a recording track formed on a non-circular recording medium while rotating the recording medium includes a detector for detecting a discontinuity in the recording track due to the non-circularity of the recording medium during rotation of the recording medium, and a combiner for combining data present on recording data area portions present before and after the discontinuity in a rotating direction of the recording medium and detected by said detecting means so that these data continue.

Abstract: A method of and a circuit for providing a playback signal, which is compensated for time delay, from a photodetector having a plurality of outputs. A time difference between a first signal corresponding to a part of the outputs of the photodetector and a second signal corresponding to another part of the outputs of the photodetector is detected and one of the first and second signals is temporally shifted to compensate for a time delay between different outputs of the photodetector. The temporally shifted signal is summed with the other signal to provide a playback signal. Accordingly, the time delay between the outputs of the photodetector is compensated, thereby increasing the degree of modulation of the data playback signal. In addition, distortion or degradation of the signal is suppressed and occurrence of errors in the playback signal is minimized, thereby improving the reliability of the playback signal.

Abstract: When subcodes included in a CD format are reproduced, jitter is removed when the subcodes are synchronized with signal data. The data is connected together by using the subcode data to prevent interruptions of sound and pictures. An error correction unit performs error correction processing for signal data reproduced (read) from a CD. A memory stores the signal data whose error is corrected and a data output unit reads out the signal data stored in the memory according to a reference clock. A subcode detection/jitter removal unit detects subcode data reproduced from the CD and outputs the subcode data to the memory in synchronism with outputting of the signal data whose error is corrected by the error correction unit, to thereby remove jitter.

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: A push-pull signal is detected 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. The detected push-pull signal is compared with a reference voltage thereby generating a land pre-pit detection signal. Of pulses included in the land pre-pit detection signal, those pulses having a small pulse width are regarded as noise pulses and removed thereby obtaining a corrected land pre-pit detection signal. The number of pulses included in the land pre-pit detection signal is counted, and the reference voltage is controlled in accordance with the counted number of pulses.

Abstract: Prior to actual reproduction of an optical disk, test reproduction is performed with respect to a plurality of testing radial locations of the optical disk. In the test reproduction, waveform-equalization-characteristic parameters of the waveform equalization section are adjusted to optimal settings so as to optimize jitter of a reproduced RF signal detected at each of the testing radial locations of the optical disk. In the actual reproduction of the optical disk, the waveform-equalization-characteristic parameters of the waveform equalization section are adjusted to optimal settings that are predicted, from the optimal settings determined by the test reproduction, in accordance with a radial position or address, on the optical disk, of each location to be reproduced.

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

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

Abstract: When information is reproduced in an optical disk of high recording density or of low recording density, a main beam and sub-beams are emitted onto adjacent tracks. The main beam has a shape longer in a direction perpendicular to the tracks. When the optical disk of high recording density is reproduced, cross talk components from adjacent tracks included in signals reproduced from reflection light of the main beam are canceled by using signals reproduced from reflection lights of the sub-beams. When the optical disk of low recording density is reproduced, information is reproduced with a beam. Thus, two types of optical disks can be reproduced with a simple structure in a compatible way. In the cross talk canceling, discrimination marks formed along the tracks at constant distances are reproduced, and a time difference between the main beam and the sub-beams is corrected precisely by using track jump and detection of discrimination marks.

Abstract: In an apparatus for reproducing recorded data, a crosstalk signal is generated by converting adjacent data recorded on an adjacent track into a waveform of said reproduction signal and the crostalk signal is deducted from the reproduction signal. Then, the reproduction signal in which the crosstalk signal is eliminated is decoded in accordance with the predetermined algorithm and reproduced.

Abstract: A method and device are provided for jitter enhancement in an optical disc system. The optical disc system generates a signal that includes an effective component having a first slew rate, and a pre-pit component having a second slew rate larger than the first slew rate. The signal is fed to a slew rate control module having a predetermined slew rate that is larger than the first slew rate and smaller than the second slew rate. The slew rate control module outputs a component of the signal having a slew rate not larger than the predetermined slew rate, and suppresses a component of the information signal having a slew rate larger than the predetermined slew rate.

Abstract: An optical disk provided with a land region and a groove region that are formed on a substrate, the land region and groove region being used as a recording track that is the medium of the recording/playback of information signal, and a pre-pit region that is formed at the boundary part of neighboring land region and groove region and is disposed every other boundary part, the pre-pit region including specific information. Characteristically, the specific information's in neighboring pre-pit regions are not aligned in the radius direction of the optical disk.

Abstract: A method and apparatus for measuring the crosstalk of an optical disc of an optical disc player adapted to reproduce signals recorded on the disc, in which there are concentrically or spirally formed continuous recorded signal strings or signal recording regions and in which there is provided a positioning aperture at the center of the disc substantially concentric with said recorded signal strings or signal recording regions. A light beam is wobbled at a predetermined amplitude in the direction along the radius of the optical disc. The wobbling period is set so as to be asynchronous with the period of the optical disc rotation. The ratio between the quantity of the traverse signal obtained by the optical pickup and the quantity of strays signals is measured as crosstalk.

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: A reproducing apparatus for reproducing an audio signal from a record carrier having a first digital audio signal (a PCM encoded audio signal) recorded on it in a first format and a second digital audio signal (an MPEG encoded multi channel audio signal) recorded on it in a second format. The apparatus includes a read unit for reading an information signal from the record carrier, a decoding unit for channel decoding the information signal read from the record carrier into a decoded information signal, a keyboard for receiving a selection signal and an output terminal for supplying an output signal which comprises either the first digital audio signal or the second digital audio signal in response to said selection signal. An output circuit is available to add an identification signal (bit b1) into the output signal, indicating that the output signal includes either the first digital audio signal or another audio signal.

Abstract: An optical disc medium according to the present invention includes at least one zone on which multiple track grooves are formed in a CAV format. Each of the track grooves has a wobbling structure made up of a fundamental wave having a single period. Information is recorded on the wobbling structure. In the at least one zone, the fundamental waves that make up the respective wobbling structures of mutually adjacent ones of the track grooves always have their phases shifted from each other by 90 degrees. As a result, the information recorded on the wobbling structure can be detected without being affected by crosstalk.

Abstract: There is disclosed a crosstalk removal apparatus in which a main track, one adjacent track, and the other adjacent track in a disk with the tracks formed therein are irradiated with light beams at predetermined intervals in a tangent direction by a pickup. A CTC unit uses delay amounts of respective sample value series corresponding to a reproduction signal of the main track and those of the adjacent tracks to correct delays, and outputs a CTC output signal from which a crosstalk component is removed. A wobble signal detector detects wobble signals of the respective tracks based on a push-pull output of the disk, and a delay circuit controller obtains optimum delay amounts based on a phase relation of the respective wobble signals and sets the delay amounts in the CTC unit.

Abstract: An information recording/reproducing apparatus of the invention is equipped with an objective lens, a light source find a variable optical element having a grating which demonstrates a piezo-electric effect by means of an electric field. The light source emits and irradiates a laser beam onto the grating to generate a 0th order diffraction beam and +/− 1st order diffraction beams in accordance with first order diffraction efficiency, and the objective lens converges the 0th diffraction beam and +/− 1st order diffraction beams which are irradiated onto an information recording medium for the purpose of information recording or information reproducing. By controlling an electric field applied to the grating, the first order diffraction efficiency of the grating is adjusted, whereby light beams are generated which have power levels appropriate for various kinds of information recording media.

Abstract: In an apparatus and a method for correcting asymmetry in an optical disk reproduction system, an analog RF signal is received from an optical diode and an asymmetry-corrected signal is output as a digital EFM signal. The apparatus includes envelope detectors for detecting upper and lower envelopes of the RF signal, a level controller for controlling the level of the sum of the upper envelope and the lower envelope and for outputting signal having the controlled level, and a comparator for comparing the level of the signal output from the level controller with the level of the RF signal and for outputting the comparison result as the digital EFM signal.

Abstract: On an information recording medium (1), digital information is multi-level-recorded by changing a shape of an information pit in correspondence with the digital information by multiple steps.

Abstract: A wobble-signal detecting device detects a wobble signal based on a signal which is the difference between outputs of two divisions of a light receiving device. These two divisions are located on both sides of a line parallel to a target portion of an information recording track. This light receiving device receives light reflected by a recording medium as a result of an optical beam being incident on the recording medium. This recording medium contains the information recording track, which wobbles at a predetermined frequency, and has pre-pits formed at predetermined intervals in areas between the information recording tracks.

Abstract: It is an object to provide a recorded information reproducing apparatus that allows to eliminate crosstalk from an adjacent track correctly, even from a recording medium having both a recorded area in which information data are recorded and an unrecorded area. In order to detect a crosstalk component from an adjacent track based on a correlation between a main read signal read from a main track and a sub read signal read from an adjacent track, the relative phase between the sub read signal and the main read signal is shifted.

Abstract: An input analog signal is digitized according to a level thereof by a digitizing circuit. A chattering component is removed from the digitized signal by a chattering removing circuit. A signal processing is performed according to the signal from which the chattering component is removed by the chattering removing circuit. In this course, the input analog signal is digitized together with the chattering component included therein by the digitizing circuit.

Abstract: An optical disk provided with a land region and a groove region that are formed on a substrate, the land region and groove region being used as a recording track that is the medium of the recording/playback of information signal, and a pre-pit region that is formed at the boundary part of neighboring land region and groove region and is disposed every other boundary part, the pre-pit region including specific information. Characteristically, the specific information's in neighboring pre-pit regions are not aligned in the radius direction of the optical disk.

Abstract: A method and apparatus to make the signal slice level during data qualification in an Optical Disc apparatus adaptable to DSV variation. According to this method, phase error signals from a Phase Locked Loop (PLL) subjected to the input data signal are used to generate Pump Up (PU) and Pump Down (PD) signals. These signals are used to determine a direction and degree of a slice level shift and to control a voltage adjustment, by feedback, of the modulated input analog signal to compensate for the slice level shift. The present invention also adapts to the presence of non-zero DSV, or DC components, by generating phase error signals (also by the PLL) when DC components (and corresponding DSV variation) are detected. When DC components are detected, slice level shift is cancelled. In this manner, the method suppresses a system response to any effects of DC component variation and thereby adapts to their presence.

Abstract: An optical disc drive equipped with a TLN signal generating apparatus is disclosed. The TLN signal generating apparatus includes a TLN signal generating circuit for generating a TLN signal (track loss signal) based on signals obtained from an optical pick-up; a digitizing circuit for digitizing the TLN signal by comparing it with a reference level; and a correction circuit for correcting the TLN signal so that it is accurately digitized by the digitizing circuit irrespective of an offset component which is a direct current component contained in the TLN signal.

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 is irradiated with a main beam and a pair of side beams, and respected reflected beams of light are detected by a main detector and a pair of side detectors. A first push-pull signal is generated which includes wobble components obtained by a detection signal from the main detector, and second and third push-pull signals are generated using detection signals from the pair of side detectors. The second and third push-pull signals are added by an adder to generate crosstalk components included in the first push-pull signal, and wobble information of the recording track is generated and output using signals obtained by canceling the crosstalk components in the first push-pull signal including wobble signal components in the recording track.

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

Abstract: An information reproducing apparatus for reproducing information of information marks by scanning information marks recorded on tracks inside a predetermined information recording region by an optical spot, the apparatus includes a driving device, an optical head, a head driving device, a laser driving device, an automatic gain control circuit, a non-linear equalization circuit, a phase locked loop circuit, a data demodulation circuit, and a control circuit.

Abstract: The objective of the present invention is to provide an optical disc recording and reproducing apparatus in which the target pre-format address and the recorded information can be read from the optical disc with excellent reproducibility, and the crosstalk between adjacent pregrooves can be prevented, even if the light beam is applied across adjacent information recording layers in accordance with the increase in a storage density of the optical disc.

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: An information reproduction apparatus for reading information of an optical recording medium is provided with: a first detecting device which supplies a difference between respective output signals optically obtained by a pair of detectors for reading information of a first track; a second detecting device and a third detecting device which supply a difference between respective output signals optically obtained by a pair of detectors for reading information of a second track and a third track respectively, the third and second tracks being placed on opposite sides of the first track; a crosstalk extracting device which extracts crosstalk caused by the second and third tracks, which is included in a detected signal supplied from the first detecting device; and a tracking control device which executes tracking control for the first detecting device based on a balance between the crosstalks caused by the second and third tracks.

Abstract: An optical disk provided with a land region and a groove region that are formed on a substrate, the land region and groove region being used as a recording track that is the medium of the recording/playback of information signal, and a pre-pit region that is formed at the boundary part of neighboring land region and groove region and is disposed every other boundary part, the pre-pit region including specific information. Characteristically, the specific information's in neighboring pre-pit regions are not aligned in the radius direction of the optical disk.

Abstract: One aspect of the invention is a method for detecting the border of recorded video data. The method comprises analyzing a plurality of video frames. The plurality of video frames comprise recorded video data and undesired data. The method also includes determining whether at least one of the plurality of video frames comprises substantially all undesired data, and identifying the at least one of the plurality of video frames as a border of the recorded video data if the at least one of the plurality of video frames comprises substantially all undesired data.

Abstract: There is disclosed a crosstalk removal apparatus in which a main track, one adjacent track, and the other adjacent track in a disk with the tracks formed therein are irradiated with light beams at predetermined intervals in a tangent direction by a pickup. A CTC unit uses delay amounts of respective sample value series corresponding to a reproduction signal of the main track and those of the adjacent tracks to correct delays, and outputs a CTC output signal from which a crosstalk component is removed. A wobble signal detector detects wobble signals of the respective tracks based on a push-pull output of the disk, and a delay circuit controller obtains optimum delay amounts based on a phase relation of the respective wobble signals and sets the delay amounts in the CTC unit.

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

Abstract: The method of sampling wobble components of the present invention is capable of realizing a disk drive unit, which can write data at high speed, and reducing manufacturing cost of the disk drive unit. The wobble components are sampled from laser beams reflected from an optical disk so as to write data on the optical disk. The laser beams are low power laser beams for reading data and high power laser beams for writing data. The method is characterized in that the wobble components of the reflected low power laser beams and the reflected high power laser beams are continuously sampled.

Abstract: The invention provides an optical disk medium having a recording spiral formed by connecting groove tracks and land tracks alternately, and permitting detection of a connecting point between a groove track and a land track reliably is provided, and a method of tracking the optical disk medium and an optical disk drive apparatus for driving the optical disk medium. One part of an identification signal area is shifted by a predetermined distance in one radial direction from the center of a groove, while another part of the identification signal area is shifted by the same distance in the opposite radial direction from the center of the groove. A land/groove polarity of a sector is determined by the polarity of a tracking error signal and the order of the polarities during reproduction of an identification signal.

Abstract: A pick up irradiates light beams at specified intervals in the tangential direction of the main track to be reproduced and both of adjacent tracks on a disk 10 on which tracks are formed. A CTC unit 15 uses the delay amount &Dgr;d of the respective sample-value series corresponding to the reproduction signal RFm from the main track and reproduction signals RF1, RF2 from both adjacent tracks to correct the delay, then outputs a CTC output signal from which the cross-talk component has been removed. In addition, when adjusting the delay, the CPU 17 applies a disturbance to the control signal for the actuator of the servo-control unit 18 and changes the delay amount &Dgr;d within a specified range of change. At this time, the CPU 17 sets the delay amount &Dgr;d, which minimizes the jitter value found by the jitter detection unit 16 according to the CTC output signal, for the CTC unit 15.

Abstract: There are disclosed an information reproduction apparatus, signal processing apparatus, and information reproduction method which can remove a crosstalk to a wobble signal, particularly a crosstalk attributed to an RF signal. The information reproduction apparatus for reading information of an optical recording medium includes a detector for outputting a difference between individual output signals optically obtained by a pair of detectors for reading the information of a first track, a detector for reading RF information of a second track adjacent to the first track, a demodulator for demodulating a detection signal outputted from the detector, and a crosstalk canceller which uses the detection signal outputted from the detector to cancel the crosstalk arising from the RF information of the track included in the detection signal outputted from the detector.

Abstract: A media type detector in a tracking and focus servo system is presented. Operating parameters for a first media type are loaded and a peak-to-peak value of a tracking error signal is calculated. Whether the media type is the first media or a second media can then be determined by comparing the peak-to-peak value with a threshold value.

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

Abstract: An information playback apparatus of the present invention is provided with: a first detecting unit for supplying a difference between respective output signals optically obtained by a pair of detectors for reading the information of the first track; a second detecting unit for supplying a difference between respective output signals optically obtained by a pair of detectors for reading the information of the second track adjacent to the first track; a first demodulating unit for demodulating a detected signal supplied from the first detecting unit, a second demodulating unit for demodulating a detected signal supplied from the second detecting unit. A coefficient controlling unit extracts the crosstalk caused by the second track, which is included in a demodulation signal obtained by the first demodulating unit, from the same signal and controls a coefficient based on the extracted crosstalk, and cancels the crosstalk by the calculated coefficient.

Abstract: In an apparatus for reproducing recorded data, a crosstalk signal is generated by converting adjacent data recorded on an adjacent track into a waveform of said reproduction signal and the crostalk signal is deducted from the reproduction signal. Then, the reproduction signal in which the crosstalk signal is eliminated is decoded in accordance with the predetermined algorithm and reproduced.