Abstract: The characteristic test device 1 supplies the output from the photo detector of the optical pickup 2, as signals A to F, directly to the sample hold circuits 8a-8f. The sample hold circuits 8a-8f, the multiplexer 9, and the second analog/digital converting circuit 10 convert the signals A to F into digital data with the sampling frequency of 50 KHz or more. In the computer 12, the processing division 12d reads out the indicated program from the data storage division 12b, where the program P for measuring the level of RF signal, is stored. The processing division 12d performs the operation of the indicated measurement items, based on the digital data stored in the second memory 11, then measures the characteristic of the optical pickup 2.

Abstract: A device is provided for calculating mutual phase shift of first and second incident signals. The device includes a first pair of blocks associated with the first incident signal, a second pair of blocks associated with the second incident signal, checking circuit, and post-processing circuit. Each of the blocks has storage elements for storing a predetermined set of samples of the corresponding incident signal. In the presence of minimum samples or maximum samples of both incident signals, the checking circuit stores a first set of samples relating to the first incident signal in one of the blocks of the first pair and a first set of samples relating to the second incident signal in the counterpart block of the second pair, and then stores the following sets of samples of each incident signal alternately in the two blocks of each pair. The checking circuit delivers a block validation signal when a set of samples has been completely stored in the storage elements of one of the blocks.

Abstract: Apparatus and method for scanning a surface. An optical system generates a light beam to illuminate a surface. A carrier supports the surface for reciprocating motion with respect to the light beam to form one axis of a raster. A propulsion system moves the carrier at a substantially constant speed and a position sensor provides an output signal representing the surface position with respect to the light beam. A control system responsive to the output signal modulates a sample period reciprocally to carrier speed to achieve substantially constant scan length per sample and to control data acquisition timing.

Abstract: For reproducing information recorded on an optical disc, a pickup is used to detect a target track on the disc through an optical beam. In carriage servo control, movement of the pickup is servo-controlled in the radial direction of the optical disc. In this control, a tracking error signal is produced by a preamplifier. A pulse signal is produced, in which the period of the pulse signal is set to a constant amount corresponding to the accuracy of movement of the pickup. The duty ratio of the pulse signal is changed based on characteristic of the error signal, so that a changed pulse signal is produced. The changed pulse signal is multiplied by the tracking error signal, so that a carriage control signal is produced. The carriage control signal is supplied to a carriage motor by a driver, so that the pickup is moved.

Abstract: A header region detecting method and apparatus and recording/reproducing method and apparatus using thereof for an optical recording medium is disclosed. According to the method and apparatus, a tracking error signal is detected by detecting an RF signal from an optical reflected signal inputted from the optical recording medium and obtaining a phase difference of optical reflected signals in a radial direction based on the RF signal. Then, first and second header detection signals are generated by slicing the detected tracking error signal with predetermined upper and lower slice levels, and a header region is detected by logically combining the first and second header detection signals, so that the header region can be accurately and stably detected even in a free running or traverse operation.

Abstract: A circuit for detecting the mirror signal from the output signal of an RF (radio frequency) in an optical disk drive, includes a first peak hold circuit for holding the peak value of the output signal of the RF amplifier to provide a first peak value, a first bottom hold circuit for holding the bottom value of the output signal of the RF amplifier to provide a first bottom value, a differential amplifier for amplifying the difference between the first and second peak values, a second peak hold circuit for holding the peak value of the output signal of the differential amplifier to provide a second peak value, a second bottom hold circuit for holding the bottom value of the output signal of the differential amplifier to provide a second bottom value, a centered value extractor for processing the second peak and bottom values to extract the centered value of the output signal of the RF amplifier, a comparator for comparing the centered value with the output signal of the differential amplifier to generate the m

Abstract: An optical recording medium that permits high density recording and only needs a recording machine of simple structure, and a machine for reproducing recorded information from such optical recording medium. A track pitch of recording tracks is smaller than a diameter of a beam spot of a scanning laser beam, and tracking pits for tracking control are formed on the respective recording tracks. A certain number of neighboring recording tracks define a group, and in each group the tracking pits are spaced from each other in a recording track direction by a predetermined interval which is smaller than the diameter of the beam spot.

Abstract: A system and method are provided for processing signals in a magneto-optical computer memory device to detect mispositioning of a head with respect to a track centerline. A light beam is scanned over a first and a second set of radially offset optically-detectable position marks formed in the rotating medium surface. A detector receives the reflected light beam and responsively generates a position signal having a plurality of pulses corresponding to the position marks. The position signal is then passed through a differentiator circuit. The differentiated position signal may then be applied to low pass filter and resonator circuits, and is subsequently conveyed to a finite time integrator for rectification and detection of the areas of the pulses associated with the first and second set of position marks. Mispositioning of the head is detected by comparing the pulse areas of the first and second set of position marks.

Abstract: The present invention provides a track traverse signal detecting circuit which controls the level of a reference voltage by calculating a mean value of a track traverse signal, or adjusting the frequency or the phase of the track traverse signal. The track traverse signal detecting circuit further determines whether the disc is a CD or a DVD, and controls the level of the reference voltage accordingly, and then detects the accurate track traverse signal. Therefore, in case of track jump or random access, the track access operation can be performed accurately.

Abstract: An optical disk (2) includes a plurality of layers in a three-dimensional direction (i.e., “thickness direction” or “depth direction”) thereof. A plurality of recording surfaces are respectively formed on the layers, the recording surfaces each has data recording tracks (16) extending along a peripheral direction of the optical disk (2). Sample servo marks (11) each has at least two mark portions (11a, 11b). The two mark portions (11a, 11b) are arranged in a zig-zag manner to be shifted in the thickness direction of the optical disk (2) such that the two mark portions (11a, 11b) interpose one of the data recording tracks (16).

Abstract: A speed profile constituting the target speed for the next drive process during searching is generated by target speed generating section 140 and tracking actuator 132 is driven using the error signal in regard to the speed of movement of the light beam calculated by movement speed detection section 141 from a pulse signal obtained by converting the TE signal to binary form. Also linear motor 139 is driven using the difference signal obtained from the target speed and the speed of movement. Tracking actuator 132 is controlled so as to suppress swinging of focusing lens 107 during searching and linear motor 139 moves, during searching, under tracking control to a target speed.

Abstract: An optical pickup position control device according to the present invention automatically adjusts tracking with precision and in a short time. Two deviation signals, which express deviation of a light beam, projected by a pickup which uses the three-beam method, from a target track of a disk, are digitized by two AD converters. Two high-pass filters extract from the deviation signals AC signals, producing a tracking error signal. Further, two low-pass filters extract from the deviation signals DC signals (offset components). Two other low-pass filters extract from the deviation signals low-band signals containing DC components. Using the various foregoing signals, a control circuit calculates correction values to be applied to two offset correcting circuits and to two gain/balance correcting circuits, and corrections are performed collectively and simultaneously on the basis of these correction values.

Abstract: On an optical disk, a string of a plurality of pits having two different depths is formed. Quantity of light reflected from the pit string is detected by a photoreceptor element, and based on the detected quantity of reflected light, a pit depth detecting unit detects depth of each pit. Based on the detected quantity of reflected light, a servo signal generating unit generates a tracking servo signal. An output control unit supplies the generated tracking servo signal when a pit of such depth that is to be reproduced is tracked, and holds and supplies an immediately preceding tracking servo signal when a pit of different depth is being tracked, based on the result of detection by the pit depth detecting unit.

Abstract: The present invention provides an optical disc drive apparatus comprising: an optical unit (2) for reading out a data recorded on an optical disc (1) from a position specified by a servo signal; a signal processor (4) for calculating and amplifying the data which has been read out by said optical unit (2); a microcomputer (5) provided with software for performing a calculation for a servo processing and a system control according to an output signal from said signal processor (4); and a servo driver (3) for performing a servo processing via said optical unit according to an output signal from said microcomputer.

Abstract: An optical disk apparatus comprises a focusing means for focusing a light beam on a recording medium having first and second information faces; means for moving a focal point of the light beam in a direction substantially perpendicular to the information faces of the recording medium; means for detecting a reflected light from the recording medium; means for detecting a focus condition of the light beam on the basis of an output signal from the reflected light detecting means; a focus control means for driving the focal point moving means on the basis of an output signal from the focus condition detecting means, and controlling the light beam so that the focus condition of the light beam becomes a prescribed focus condition; and a focus jumping means for moving the focal point of the light beam from the first information face to the second information face by driving the focal point moving means.

Abstract: An optical disk apparatus comprising a light source for emitting a light beam, an optical system for focusing the light beam to form a beam spot on the optical disk, a tracking unit for detecting the light reflected from the optical disk to generate a tracking error signal from the light by a differential phase detection method, and move the beam spot in accordance with the tracking error signal, and an information-readout section for reading out information from the optical disk. To achieve readout compatibility between a high-definition DVD and a DVD-ROM, a predetermined delay is given relatively to first and second signals obtained from two pairs of regions arranged in two crossing diagonals of a quadrant photodetector, thereby shifting the beam spot from the centerline of the pit stream in the radial direction of a DVD-ROM, in order to read out information from the DVD-ROM.

Abstract: Address groups are composed of two of address blocks 16, 17, 18, and 19, where the address blocks 16, 17, 18, and 19 are disposed in a sector address region 5 and include identifiable information of address numbers 13 and overlapping sequential numbers 14. The address groups are disposed so that each group is alternately shifted from a track center 2 toward the inner periphery side or the outer periphery side, by a width substantially equal to half the track pitch, along the radius direction.

Abstract: An analog to digital circuit assembly for use in an optical information includes a circuit for multiplexing a reference voltage input of an analog to digital converter to produce alternating normalized and referenced digital outputs of a plurality of analog signal inputs at a rate controlled by a sampling clock which includes a switch including first and second inputs, an output, and a control input for alternately connecting the first and the second inputs to the output, the output being applied to the reference voltage input.

Abstract: An optical disk apparatus comprising a light source for emitting a light beam, an optical system for focusing the light beam to form a beam spot on the optical disk, a tracking unit for detecting the light reflected from the optical disk to generate a tracking error signal from the light by a differential phase detection method, and move the beam spot in accordance with the tracking error signal, and an information-readout section for reading out information from the optical disk. To achieve readout compatibility between a high-definition DVD and a DVD-ROM, a predetermined delay is given relatively to first and second signals obtained from two pairs of regions arranged in two crossing diagonals of a quadrant photodetector, thereby shifting the beam spot from the centerline of the pit stream in the radial direction of a DVD-ROM, in order to read out information from the DVD-ROM.

Abstract: A signal compensating apparatus is an apparatus for compensating a control signal which is generated on the basis of a light beam reflected by an optical recording medium and which includes information with respect to a relationship between a spot of the light beam and a track of the optical recording medium. The signal compensating apparatus has: a detecting device for detecting a damaged part of the control signal, which is caused by a defect of the optical recording medium or an obstruction existing on an optical path of the light beam or on the optical recording medium; a replacing signal generating device for generating a replacing signal whose level gradually varies so as to connect a level of a first normal part of the control signal immediately before the damaged part with a level of a second normal part of the control signal immediately after the damage part; and a replacing device for replacing the damaged part by the replacing signal.

Abstract: A tracking control method and apparatus wherein an offset generated in the push-pull signals is removed to realize correct tracking. In an address area AR1, a pit-shaped groove GR1 is formed between a wobbling groove GR and a groove header GRH on a line of extension of the wobbling land. That is, the groove GR1 is surrounded by two neighboring lands. On the other hand, a land X of the address area AR1 lying on a line of extension of the groove GR and on a sector boundary is surrounded by two neighboring pit-shaped grooves GR1.

Abstract: A correction processing unit for correcting a level fluctuation appearing on a tracking error signal when a laser beam passes an ID area on a medium track during an on-track control is provided. That is, in the correction processing unit, a correction value determined by a correction value determining unit at a correction timing detected by a correction timing discriminating unit is subtracted by a correcting unit from a signal value obtained by sampling and converting the tracking error signal into digital data by an A/D converter at a predetermined period and reading, thereby performing the correction.

Abstract: A read channel circuit of an optical disk reproducing apparatus is adapted to provide stability in servo control and reduce power consumption by revising the offset component of the circuit components after application of reference signals and then the offset component caused by pit depth resulting from signals read out in reproducing a data from an optical disk. The read channel circuit includes: a data converting section for amplifying signals input via different channels and converting them to digital data. A data reproducing section is provided for summing and waveform-equalizing the digital signals, detecting the phase difference between the waveform-equalized signals and reference sampling points, and generating a sampling clock frequency which is provided to the data converting section for compensating for the phase difference.

Abstract: A tracking servo device for use with an optical disc apparatus includes a photodetector unit having a plurality of photodetectors each of which is split in association with the direction of tracks formed on the optical disc, and a tracking error generating unit for finding the difference in outputs from at least two of the photodetectors of the photodetector unit for generating a tracking error signal. The tracking servo device also includes a first correction unit for removing an offset produced in the tracking error signal when the tracking servo is on, and a second correction unit for removing an offset produced in the tracking error signal when the tracking servo is off.

Abstract: An optical recording medium having a number of adjacent tracks for storing digital optical information extending in a first direction. The tracks are separated by a pitch amount in a second direction and each track has a servo field comprising at least one synchronization mark and at least one tracking mark in one of at least three positions on the track. The tracking marks of tracks adjacent in the second direction to a first track are in different positions from each other and from the position of the tracking mark on the first track. The track marks extend in the second direction to give rise to cross-talk from the tracking marks of adjacent tracks when the first track is being read.

Abstract: An optical recording device for use in a recording/reproducing operation has a photodetector for receiving a part of a laser beam generated by a laser source, and a CCD sensor for receiving the laser beam reflected from an optical disk and including information of the energy profile of the laser beam on the optical disk. The signal processor generates a defect signal representing an occurrence of a defect caused by the fluctuation of the laser power and/or the focal position and the cause of the defect during operation of the optical recording device.

Abstract: A reproduced signal 104 is sampled with a half-frequency clock signal to set two threshold levels 107, 108 for a sub-sampled data string 105, and the sub-sampled data string 105 is determined to be at three levels to produce an intermediate value data string 109. A modulo-2 operation is performed on the intermediate data string 109 to determine the data of the sub-sampled data string 105, and the data of a non-sampled data string 106 are decided with the state transition of the sub-sampled data string 105 to acquire reproduced data 112.

Abstract: An optical pickup position control device according to the present invention automatically adjusts tracking with precision and in a short time. Two deviation signals, which express deviation of a light beam, projected by a pickup which uses the three-beam method, from a target track of a disk, are digitized by two AD converters. Two high-pass filters extract from the deviation signals AC signals, producing a tracking error signal. Further, two low-pass filters extract from the deviation signals DC signals (offset components). Two other low-pass filters extract from the deviation signals low-band signals containing DC components. Using the various foregoing signals, a control circuit calculates correction values to be applied to two offset correcting circuits and to two gain/balance correcting circuits, and corrections are performed collectively and simultaneously on the basis of these correction values.

Abstract: An information recording and reproducing method having a track identification function that is suitable for performing an accurate information record and reproduction for a recording medium including user information areas having any ones of land and groove tracks arranged alternately each other and identification areas having at least one pit stream arranged intersectionally each other at each side on the basis of the center line of the tracks and arranged alternately with the user information area. In the method, a first identification information signal for a pit stream recorded on one side and a second identification information signal for a pit stream recorded on the other side, on the basis of any one center line in tracks, are detected.

Abstract: A speed profile constituting the target speed for the next drive process during searching is generated by target speed generating section 140 and tracking actuator 132 is driven using the error signal in regard to the speed of movement of the light beam calculated by movement speed detection section 141 from a pulse signal obtained by converting the TE signal to binary form. Also linear motor 139 is driven using the difference signal obtained from the target speed and the speed of movement. Tracking actuator 132 is controlled so as to suppress swinging of focusing lens 107 during searching and linear motor 139 moves, during searching, under tracking control to a target speed.

Abstract: A focus servo control system is a system for selectively applying a light beam to a disk on which data is recorded on plurally layered recording surfaces and setting the focus position of the light beam on a selected recording surface of the two-layered recording surfaces based on a signal read from reflected light from the selected recording surface of the plurally layered recording surfaces of the disk and includes a focus error detector for detecting a positional difference between the focus position of the light beam and the selected recording surface of the plurally layered recording surfaces, a sample-hold circuit for sampling and holding an output of the focus error detector, a focus position correcting circuit for correcting the focus position of the light beam based on one of the output of the focus error detector and an output of the sample-hold circuit, a data signal level detector for detecting the signal level relating to data read out from the disk, a comparator for comparing a signal level dete