WO2003032308A1 - Dispositif de memorisation d'information et circuit de detection de defaut - Google Patents

Dispositif de memorisation d'information et circuit de detection de defaut Download PDF

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Publication number
WO2003032308A1
WO2003032308A1 PCT/JP2001/006974 JP0106974W WO03032308A1 WO 2003032308 A1 WO2003032308 A1 WO 2003032308A1 JP 0106974 W JP0106974 W JP 0106974W WO 03032308 A1 WO03032308 A1 WO 03032308A1
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WIPO (PCT)
Prior art keywords
defect
signal
information storage
unit
information
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Application number
PCT/JP2001/006974
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English (en)
Japanese (ja)
Inventor
Manabu Kobayashi
Toshikatsu Narumi
Original Assignee
Fujitsu Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Fujitsu Limited filed Critical Fujitsu Limited
Priority to JP2003535189A priority Critical patent/JPWO2003032308A1/ja
Priority to PCT/JP2001/006974 priority patent/WO2003032308A1/fr
Publication of WO2003032308A1 publication Critical patent/WO2003032308A1/fr

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
    • G11B20/1883—Methods for assignment of alternate areas for defective areas
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor

Definitions

  • the present invention relates to an information storage device that performs at least information reproduction on an information storage medium, and a defect detection circuit that detects a defect in the information storage medium.
  • information storage media such as CD, CD-ROM, CD-R, DVD, PD, MO, and MD have been widely used as large-capacity storage media for storing audio signals and image signals.
  • magneto-optical information storage media in which information is recorded by magnetic marks and reproduced by light, are attracting attention as high-density storage media on which information can be rewritten.
  • R & D is being actively conducted for this purpose.
  • research and development of information storage devices that perform information reproduction and information storage on such information storage media are also being actively conducted.
  • defects such as scratches occur in the information storage medium during manufacture or use. Such defects often cause recording errors.
  • defects were detected by checking the writing and reproduction of information at the time of shipping and recording information, and measuring the error rate. Of the storage area, a section having a high error rate is treated as a defective section having a defect, and information recording in the section is avoided.
  • a small defect may occur in the information storage medium. In a section where such a small defect exists, information recording and information reproduction may fail or succeed. If the playback check at the time of information recording succeeds for a certain section, and then the information playback fails when the recorded information is needed, the information recorded in that section will be lost. .
  • the information storage device includes a defect detection unit that can detect such a small defect with high accuracy. As a result, it is possible to accurately eliminate defective sections at the time of recording and to improve the reproduction capability at the time of reproduction.
  • an object of the present invention is to provide an information storage device having a small-scale and high-accuracy defect detection unit, and a small-scale and high-accuracy defect detection circuit.
  • the information storage device of the present invention that achieves the above object is, in an information storage device that performs at least information reproduction on an information storage medium in which information is recorded in a predetermined information storage area by a magneto-optical recording method,
  • An intensity signal output unit that receives light reflected by the information storage medium and outputs an intensity signal corresponding to the intensity of the reflected light
  • An intensity signal acquisition unit that acquires the intensity signal output by the intensity signal output unit
  • a defect determining unit that determines whether there is a defect in the information storage area using the intensity signal acquired by the intensity signal acquiring unit.
  • an information storage medium of the magneto-optical recording system is provided with a number of parallel linear tracks, and information is recorded on each of the tracks.
  • Each track is divided into multiple sectors.
  • ID information for identifying each sector is recorded in an uneven pit, and arbitrary information is recorded in a flat MO area after the header by a magnetic mark.
  • the ID information recorded by the concave and convex pits is read based on the intensity of the reflected light from the information storage medium, and the information recorded by the magnetic mark is read based on the polarization direction of the reflected light.
  • the presence or absence of a defect in the M ⁇ region is determined based on the intensity signal corresponding to the intensity of the reflected light.
  • the effect of the above-mentioned small defect on the intensity of the reflected light is greater and more evident than the effect on the polarization direction of the reflected light, so that a small-scale circuit can perform defect determination with high accuracy.
  • the information storage device of the present invention receives the reflected light reflected by the information storage medium, and outputs a polarization signal output unit that outputs a polarization signal according to the polarization direction of the reflection light.
  • a peak hold section that tracks the peak of the polarization signal and holds an afterimage of the peak value;
  • the sensitivity for tracking the peak by the peak hold unit is set to the first sensitivity when the defect determination unit determines that there is no defect, and is set to the first sensitivity when the defect determination unit determines that there is a defect.
  • the peak hold unit tracks the peak of the polarization signal according to the sensitivity set by the sensitivity setting unit.
  • the signal level of the polarization signal according to the polarization direction of the light reflected by the information storage medium fluctuates due to various factors such as the use environment such as temperature and the laser power. Further, the signal level of the intensity signal according to the intensity of the reflected light also fluctuates due to factors such as laser power and the type of medium. For this reason, when information is recorded with uneven pits or magnetic marks, a specified repetition mark (VFO) is written at the beginning of the information, and when information is reproduced, the top peak of the signal caused by the repetition mark is written. And a peak peak are measured by the peak hold unit, and an intermediate value between the top peak and the peak peak is set as a slice level. The slice level is used as a reference to binarize the signal resulting from the recorded information, and the recorded information is reproduced.
  • VFO specified repetition mark
  • the defect determination unit determines that there is a defect, the sensitivity of the peak hold unit is reduced, thereby preventing a slice level shift and realizing normal information reproduction.
  • the sensitivity setting section sets the sensitivity at which the peak hold section tracks the peak to 0 when the defect determination section determines that there is a defect. It is.
  • the information storage device including such a sensitivity setting unit, when a defect is detected, the slice level shift becomes zero.
  • the information storage device of the present invention performs information reproduction and information recording on an information storage medium, and also performs reproduction confirmation of the recorded information, the information storage device includes:
  • a sensitivity fixing unit that fixes the sensitivity of the peak hold unit to track the peak to the first sensitivity when confirming the reproduction of information.
  • the information storage device of the present invention includes an error forcing unit that forcibly generates a reproduction error when the defect determining unit determines that there is a defect.
  • the defective sector can be actively replaced when there is a defect, so that the quality of information recording is improved.
  • the defect determination unit in the information storage device of the present invention may determine that there is a defect when the signal level of the intensity signal exceeds a predetermined high level.
  • the defect determination unit may determine that the signal level of the intensity signal is a predetermined level. If it is lower than the low level, it may be determined that there is a defect. Further, it is preferable that the defect determination section performs a bipolar defect determination using both the high level and the low level.
  • the signal level of the intensity signal often rises due to a defect, but may fall. Therefore, a high determination accuracy can be obtained by performing the bipolar defect determination.
  • a defect determination unit is used when the signal level of the intensity signal continuously exceeds a predetermined high level for a predetermined time interval or more. Alternatively, it may be determined that there is a defect when the predetermined lower level continues to fall below the predetermined time interval or longer. In this case, if the size of the defect exceeds a predetermined size, it is determined that there is a defect.
  • these defect determination units are capable of setting the high level and are capable of setting the low level. According to the information storage device having such a defect judging section, the high level and the low level can be tuned to the optimum values to improve the defect judging ability and the information reproducing ability.
  • the information storage device may be configured such that "the intensity signal acquiring unit amplifies the acquired intensity signal; and The defect determination unit determines the presence or absence of a defect in the information storage area using the intensity signal amplified by the intensity signal acquisition unit. " According to such an information storage device, the accuracy of defect determination is improved by amplifying the intensity signal.
  • the information storage device of the present invention is such that "the defect determination unit outputs a determination signal representing a result of determining the presence or absence of a defect in binary, and
  • a delay unit that receives the determination signal output by the defect determination unit, and delays and outputs a change timing of the determination signal from a signal value indicating a determination result that there is a defect to a signal value that indicates a determination result that there is no defect; It is also preferable. According to such an information storage device, it is possible to eliminate the influence of an error between the change timing of the intensity signal or the determination signal and the position where the defect exists.
  • a defect detection circuit that achieves the above object is a defect detection circuit that detects a defect in an information storage medium in which information is recorded in a predetermined information storage area by a magneto-optical recording method, wherein the information storage medium is reflected.
  • An intensity signal acquisition unit that acquires an intensity signal representing the intensity of the reflected light;
  • a defect determining unit that determines whether there is a defect in the information storage area using the intensity signal acquired by the intensity signal acquiring unit.
  • defect detection circuit of the present invention only shows the basic form here, but this is merely to avoid duplication, and the defect detection circuit of the present invention has the above-described defect detection form of the basic form. Not only circuits but also various types of defect detection circuits corresponding to the above-described information storage devices are included.
  • FIG. 1 is a diagram showing a specified repetition mark (VF) recorded on an information storage medium.
  • FIG. 2 is a diagram illustrating a comparative example of the peak hold circuit.
  • FIG. 3 is a block diagram of an optical disk device according to an embodiment of the information storage device of the present invention.
  • FIG. 4 is a diagram showing details of the reproducing circuit.
  • FIG. 5 is a diagram showing a first embodiment of the defect detection circuit of the present invention and a peak hold unit.
  • FIG. 6 is a diagram showing an envelope signal generated in the peak hold section shown in FIG.
  • FIG. 7 is a diagram showing a second embodiment of the defect detection circuit of the present invention.
  • FIG. 8 is a diagram illustrating a third embodiment of the defect detection circuit.
  • FIG. 9 is a diagram illustrating a fourth embodiment of the defect detection circuit.
  • FIG. 10 is a diagram showing a fifth embodiment of the defect detection circuit.
  • FIG. 11 is a diagram showing a sixth embodiment of the defect detection circuit.
  • FIG. 12 is a diagram showing a peak-hold portion in which the amount of change in sensitivity can be adjusted.
  • FIG. 13 is a diagram showing another form of the peak hold unit.
  • FIG. 14 is a diagram illustrating an envelope signal generated by the peak hold unit illustrated in FIG.
  • FIG. 15 is a diagram showing a seventh embodiment of the defect detection circuit. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 is a diagram showing a specified repetition mark (VFO) recorded on an information storage medium.
  • Part (A) of Fig. 1 shows the vicinity of the beginning of the MO area where information is recorded by magneto-optical recording, followed by the VF0 part 10 where the prescribed repeat mark (VFO) is written.
  • An information portion 11 is provided in which a mark representing information is written.
  • Part (B) of FIG. 1 shows the waveform of the polarization signal 13 obtained from the mark written in the area shown in Part (A), and this polarization signal 13 is obtained by a peak hold circuit described below.
  • the envelopes 14 and 15 of the waveform 3 are obtained.
  • FIG. 2 is a diagram illustrating a comparative example of the peak hold circuit.
  • This peak hold circuit 20 is provided with a charge constant current power supply 21 and a discharge constant current power supply 22.
  • the charge constant current power supply 21 charges the capacitor 23 with a constant charge current.
  • the discharge constant current power supply 22 discharges the electric charge from the capacitor 23 with a constant discharge current.
  • the above-mentioned polarization signal is input to the peak hold circuit 20 as a reproduction signal via the operation 26 and the diode 27, and a voltage corresponding to the reproduction signal is applied to the point 28.
  • the amount of charge that capacitor 23 can store is proportional to the voltage applied to point 28, and when the charge of capacitor 23 is saturated, a signal with the same voltage as the voltage at point 28 is output. Output from terminal 25 as envelope signal.
  • the amount of charge that the capacitor 23 can store also changes.
  • the capacitor 23 becomes unsaturated, and the charge is stored in the capacitor 23 by the effective charge current described above.
  • the amount of charge that can be stored decreases, the capacitor 23 becomes oversaturated, and the charge is discharged from the capacitor 23 by the above-described discharge current.
  • the envelope signal deviates from the reproduction signal by a voltage corresponding to the amount of unsaturation or supersaturation, and as the unsaturation ⁇ oversaturation is eliminated, the envelope signal becomes the reproduction signal. Approaching.
  • Embello The speed at which the loop signal approaches the playback signal is proportional to the effective charge current and the discharge current. Therefore, when the effective charge current is much larger than the discharge charge current, the envelope signal quickly follows the rise in the level of the reproduction signal, and also greatly follows the fall in the level of the reproduction signal. Causes delay. In other words, the envelope signal tracks the signal peak (top peak) toward the high level and retains the afterimage of the top peak, and the envelope 14 on the high level shown in FIG. 1 is obtained. Conversely, if the effective charge current is much smaller than the discharge current, the envelope signal will track the signal peak (bottom peak) to the lower level and retain the afterimage of the bottom peak. Thus, the low-level envelope 15 shown in FIG. 1 is obtained. In the following description, the envelope signal and the envelope may be used without distinction.
  • an information storage device is provided with two peak hold circuits, and one of the two peak hold circuits functions as a top peak hold section for obtaining a high-level envelope 14.
  • the other functions as a bottom peak hold unit for obtaining the low-level envelope 15.
  • the trigger signal 12 rises at a predetermined timing which is expected from experience that the two envelopes 14 and 15 have sufficiently converged on the waveform of the polarization signal 13, and is sliced at the timing of the rising edge. Hold is performed and slice level 16 is fixed. Thereafter, the polarization signal 13 is binarized by a binarization process based on the fixed slice level 16, and the information stored in the information portion 11 is reproduced.
  • the waveform of the polarization signal 13-1 causes a sudden change at the position of the defect, as shown in part (C) of FIG.
  • one of the two envelopes 14-1 and 15-1 is moved from the original envelope for a while after the defect for a while after the defect.
  • the slice level 16_1 also deviates from the original level for a while after the defect, and if the trigger signal 12 rises during that time, the slice level 16-1 is fixed while deviating from the original level It will cause a playback error.
  • the rising timing of the trigger signal 12 is changed.
  • FIG. 3 is a block diagram of an optical disk device as one embodiment of the information storage device of the present invention.
  • an optical disk is used as the information storage medium according to the present invention.
  • the optical disk device includes a controller 40 and an optical head unit 30.
  • the optical head section 30 is shown as one square, but in practice, the optical head section 30 is composed of a movable section and a fixed section. The movable part is moved in the radial direction with respect to the optical disk, and the fixed part is fixed to the housing of the optical disk device.
  • the optical head section 30 is provided with a Poiscoil module (VCM) 34.
  • VCM 34 moves the movable section of the optical head section 30 in the radial direction of the optical disc to position the optical head section. I do.
  • the laser diode 31 generates a write beam during a write operation, a read beam during a read operation, and an erase beam during an erase operation.
  • the focus actuator 33 is provided in the optical head section 30 (not shown here).
  • the objective lens is moved in the optical axis direction, and a beam spot of a specified size is formed on the optical disk.
  • the focus is adjusted to form an image.
  • the photodetector 32 receives the reflected light obtained by reflecting the laser beam irradiated on the optical disc by the optical disc.
  • a four-segment photodetector with a four-segment light-receiving surface is used, and the four light-receiving surfaces receive reflected light via a lens or a prism.
  • the four-segment photodetector outputs four light-receiving signals corresponding to the amounts of light received on each of the four light-receiving surfaces, and these four light-receiving signals are combined in a predetermined combination to generate a tracking error signal and a focus error signal.
  • a signal is obtained, and an intensity signal corresponding to the intensity of the reflected light and a polarization signal corresponding to the polarization direction of the reflected light are also obtained.
  • the electromagnet 36 generates an external magnetic field for initializing the medium during an erase operation or an external magnetic field during a write operation.
  • the temperature sensor 35 detects the environmental temperature inside the optical disk device.
  • the movable part of the optical head 30 is equipped with an objective lens and a focus actuator 33, while the fixed part is a VCM 34, a photodetector 32, a laser diode 31, and a temperature. Sensor 35 and electromagnet 36 are installed, and the movable side is as light as possible.
  • the spindle motor 64 rotationally drives an optical disk inserted into the optical disk device.
  • the optical disk cartridge containing the optical disk is inserted into the optical disk device, the optical disk is chucked on the rotating shaft of the spindle motor 64, and when the chucking is completed, the spindle motor 64 is started to keep the optical disk constant. Rotated at speed.
  • the optical disk When an eject button provided outside the casing of the optical disk device is pressed, the optical disk is released from chucking, and the optical disk is sent out of the optical disk device together with the optical disk cartridge by the eject motor 66.
  • controller 40 will be described.
  • the functions of the controller 40 are realized by program control of a microprocessor (MPU) or a digital signal processor (DSP).
  • FIG. 3 shows functional blocks of the controller 40.
  • the controller 40 is provided with an overall control unit 41.
  • the overall control unit 41 exchanges commands and data with a host device such as a personal computer via an interface control unit 47.
  • the overall control unit 41 controls each unit in the optical disk device to perform a write operation, a read operation, This is to perform an erase operation.
  • the overall control unit 41 performs an initialization diagnosis operation when the power is turned on. Thereafter, when an access request to the designated track is received from the host device via the interface control unit 47, a seek operation to the designated track address is performed, and the spot of the laser beam is spotted on the target track. On-track control to maintain the position of. In addition, a write operation, a read operation, or an erase operation is performed while a beam spot is maintained on a target track.
  • the controller 40 includes, in addition to the overall control unit 41, a track support control unit 46, a focus support control unit 45, a light emission power control unit 42, a bias magnet control unit 43, and a motor control unit. 4 4 are provided.
  • the track support controller 46 receives the tracking error signal detected by the tracking error detector 55 from the light receiving signal of the photodetector 32 via the AD converter 56.
  • the track support controller 46 controls the VCM 34 via the DA comparator 52 and the VCM driver 51 based on the tracking error signal, and performs seek operation and seek operation. Perform on-track control after completion.
  • the focus support control unit 45 captures a focus error detection signal obtained by the focus error detection unit 57 from the light reception signal of the photodetector 32 via the AD converter 58. Further, the focus support control unit 45 controls the focus actuator 33 via the DA converter 54 and the actuator driver 53 based on the focus error detection signal, and performs laser control. Focus control is performed so that the beam has a specified spot diameter.
  • the light-emission power control section 42 is controlled by the general control section 41 to perform a write operation, a read operation, and a release operation, so that the light emission power specified for each operation becomes the same.
  • the drive current of the laser diode 31 is controlled via the one-way drive circuit 59 to output a laser beam having a specified emission power.
  • the bias magnet control section 43 drives the electromagnet 36 via the electromagnet driver 62 during an erase operation or a write operation to generate an external magnetic field.
  • the motor control unit 4 4 completes loading the optical disk cartridge from the overall control unit 4 1.
  • the spindle motor 64 is driven to rotate at a constant speed via the spindle motor driver 65.
  • the motor control unit 44 drives the eject motor 66 via the eject motor driver 67. Send out the optical disk.
  • the optical disk device is provided with a recording circuit 60 and a reproducing circuit 61.
  • the recording circuit 60 operates as a data modulation circuit, generates a modulation signal upon receiving write data from the overall control unit 41 during a write operation, and supplies the modulation signal to the laser drive circuit 59.
  • the modulation of the light amount of the light beam is performed according to the write data.
  • the reproduction circuit 61 functions as a data demodulation circuit, receives an intensity signal and a polarization signal based on the received light signal output from the photodetector 32 of the optical head unit 30, and demodulates data from the intensity signal and the polarization signal. And supplies it to the overall control unit 41.
  • FIG. 4 is a diagram showing details of the reproducing circuit.
  • the optical disk 68 shown in FIG. 4 is provided with a number of sectors as the minimum recording unit, and in each sector, ID information for identifying each sector is stored as read-only information by a preformat of uneven pits. It consists of an ID section and a rewritable MO section in which arbitrary information is recorded by magneto-optical recording.
  • the ID information recorded in the ID section is reproduced using the intensity signal described above, and the information recorded in the MO section is reproduced using the polarization signal described above.
  • the intensity signal may be referred to as an ID signal
  • the polarization signal may be referred to as an M ⁇ signal, which is a customary name in the technical field of the present invention.
  • the reflected light from the optical disk 68 which refers to the intensity signal as the ID signal regardless of whether or not it is caused by the ID information, is received by the photodetector 32 of the optical head 30, and Two light receiving signals are output.
  • the head amplifier 37 for the MO signal (polarized signal) amplifies the difference A—B between the two signals A and B, which are obtained by combining the four received light signals into two parts according to the polarization direction.
  • MOP and MON To generate inverted non-inverted signals MOP and MON.
  • MOP, M ⁇ N corresponds to the MO signal described above. Therefore, the optical detector 32 of the optical head 30 and the M ⁇ signal ( The head amplifier 37 for the polarization signal) constitutes an example of the polarization signal output unit according to the present invention.
  • the head amplifier 38 for the ID signal (strength signal) amplifies the sum A + B of the two signals A and B to generate inverted non-inverted signals IDP and IDN.
  • the difference between these two signals I DP and I DN corresponds to the above-mentioned ID signal. Therefore, the photodetector 32 of the optical head 30 and the head amplifier 38 for the ID signal (intensity signal) constitute an example of the intensity signal output unit according to the present invention.
  • the four signals MOP, MON, IDP, and IDN thus generated are sent to the reproducing circuit 61.
  • the mute 71 removes the DC offset from the four signals MOP, MON, IDP, and IDN at the timing of the mute gate signal from the higher-level control unit.
  • the multiplexer 72 selects two signals I DP and I DN or two signals M 0 P and MON in accordance with the ID section and MO section switching signals from the higher-level control section, and inputs them to the low-pass filter 73.
  • each of the two input signals is subjected to filtering, differential signal processing, AGC processing, etc., to create normal reproduction signals NP, NN and differential reproduction signals DP, DN. .
  • the difference signal between the normal playback signal NP and NN is input to both the top peak hold (PH) section 74a and the bottom peak hold (PH) section 74b as a playback signal, and the high and low level envelopes are respectively input. —A loop is generated.
  • the top peak hold (PH) section 74a and the bottom peak hold (PH) section 74b have almost the same circuit configuration. Hereinafter, these are sometimes collectively referred to as the peak hold (PH) section. is there.
  • the two envelopes generated by the two peak hold units are input to the slice circuit 75a, and the intermediate value between the two envelopes is fixed as the slice level at the timing of the slice hold signal described above.
  • a pit position recording method is adopted, and a difference signal between the normal reproduction signals NP and NN and a fixed slice level are compared by a comparator 75b to generate a window signal.
  • the binarization circuit 78 receives the window signal and the differential reproduction signals DP and DN described above.
  • the differential reproduction signals DP and DN are zero-cross-compared, and the logical sum of the comparison result and the window signal is calculated to obtain binary reproduced data.
  • the reproduction data obtained in this way is data that has been modulated during recording so as to be suitable for recording and reproduction on a recording medium, and this reproduction data is demodulated by the demodulation circuit 79 to normal data. This is input to the overall control unit 41.
  • the reproduction circuit 61 is provided with a defect detection unit 76, which receives two signals IDP and IDN, which are the basis of the ID signal, and detects a defect in the MO section of the optical disc as described later. .
  • the judgment signal representing the detection result by the defect detection unit 76 is input to both the top peak hold (PH) unit 74a and the bottom peak hold (PH) unit 74, and the sensitivity of following the peak is described later. Is set by the judgment signal as described above.
  • the determination signal is also input to the binarization circuit 78, and the non-operation of the binarization circuit 78 is set by the determination signal. However, it is assumed that the input destination of the determination signal is appropriately distributed by the entire system control unit 41.
  • the serial interface 77 is connected to the overall control unit 41, and various settings during the read operation are executed by the overall control unit 41 via the serial interface 77.
  • defect detection unit 76 and the peak hold (PH) unit will be described below. However, in the following description, the description will be made using the configuration as the top peak hold section as a representative, and the configuration as the bottom peak hold section will be supplementary description.
  • FIG. 5 is a diagram showing a first embodiment of the defect detection circuit of the present invention and a peak hold unit
  • FIG. 6 is a diagram showing an envelope signal generated in the peak hold unit. .
  • the defect detection circuit 76-1 shown in FIG. 5 is a circuit incorporated as the defect detection unit 76 shown in FIG. 4, and the peak hold unit 74 shown in FIG. PH) This is a circuit incorporated as part 74a.
  • the defect detection circuit 76-1 includes a difference circuit 81 as an example of an intensity signal acquisition unit according to the present invention, and a comparator 83 as an example of a defect determination unit according to the present invention.
  • This defect detection circuit 761 is a simple and small-scale circuit.
  • the difference circuit 81 receives two signals IDP and IDN which are the basis of the ID signal, and generates an ID signal which is a difference between the two signals IDP and IDN as a voltage signal.
  • the signal level of the ID signal is compared by the comparator 83 with the slice voltage generated by the slice voltage generator 82 to output a binary decision signal.
  • the value of the judgment signal is “1” indicating that there is a defect
  • the value of the judgment signal is “0” indicating that there is no defect. is there.
  • Part (B) of FIG. 6 shows the ID signal 17 and the slice voltage 18.
  • the ID signal 17 shown here is the ID signal when the spot of the laser beam passes through the MO section. It is. Since the MO section has a flat shape, if a defect occurs in the MO section, the defect causes a large change in the amount of reflected laser beam and a large change in the signal level of the ID signal 17. Therefore, by comparing the level of the ID signal 17 with the slice voltage 18, a defect in the MO section can be detected with high accuracy.
  • the presence or absence of a defect is determined by comparing the polarization signal (MO signal) 13-1 shown in part (A) of FIG. 6 with the threshold level.
  • the threshold level is set to be equal to or higher than the maximum amplitude of the normal waveform, and the threshold level is set to a value lower than that required to detect the defect more accurately. It is necessary to set, and it turns out that setting is very difficult.
  • the change in the MO signal represents the change in the polarization direction of the light, it is difficult to predict the behavior of the MO signal with respect to the defect, and in some cases, the signal waveform has a smaller amplitude than the normal waveform amplitude. It may not be possible to judge by comparing with the threshold level.
  • the determination signal generated by the comparator 83 shown in FIG. 5 is input to the AND gate 84 together with the above-described ID section / M section switching signal.
  • the ID section / MO section switching signal has a value of “0” when the laser beam spot irradiated on the optical disc exists on the ID section, and has a value of “0” when the laser beam spot exists on the MO section. 1 ". Therefore, the judgment signal output by the comparator 83 is output.
  • the signal is input to the peak hold section 74 only when the laser beam spot exists in the MO section.
  • the peak hold unit 74 differs from the comparative example in that two charge constant current power supplies 21a and 21b are provided in place of the one charge constant current power supply provided in the peak hold circuit of the comparative example described above.
  • the circuit is different, and the same components as those in the comparative example are denoted by the same reference numerals, and redundant description will be omitted.
  • the current value setting system 24 shown here represents a setting function by the serial interface 77 and the overall control unit 41 shown in FIG.
  • the total charge current value of the two charge constant current power supplies 21a and 2lb is equal to the charge current value of one charge constant current power supply provided in the comparative example.
  • the bottom peak hold (PH) section 74b shown in FIG. 4 one charge constant current power supply is provided as in the comparative example, and one discharger provided in the comparative example is provided. Two discharge constant current power supplies are provided instead of one constant current power supply.
  • One of the two charge constant current power supplies 21a and 21b provided in the peak hold part 74 has a charge constant current power supply 21b, and the defect detection circuit 76-1- A determination signal representing a detection result is input. If the detection result by the defect detection circuit 76_1 is a defect-free detection result, the operation of the charge constant current power supply 21b is turned on, and the peak hold unit 74 operates in exactly the same manner as the comparative example described above. Generate an envelope signal. On the other hand, if the detection result by the defect detection circuit 76--1 is a detection result indicating that there is a defect, the operation of the charge constant current power supply 21b is turned off, and the peak hold section 74 follows the peak of the reproduced signal.
  • the sensitivity is lower than in the comparative example described above. That is, the charge constant current power supply 21b functions as the sensitivity setting unit according to the present invention.
  • Part (A) of FIG. 6 shows the same polarization signal (M ⁇ signal) 13-1 as the polarization signal 13-1 shown in part (C) of FIG. Also shown are the envelope signals 14-2 and 15-2 generated by the peak hold sections on the top and bottom sides, respectively.
  • the level of the ID signal 17 shown in part (B) of Figure 6 is below the slice voltage 18 and the envelope signals 14-2 and 15-2 are polarized signals.
  • the level of the ID signal 17 exceeds the slice voltage 18, and the defect detection circuit detects the defect, and the sensitivity of the peak hold circuit to follow the peak decreases. Therefore, even if a sudden change occurs in the waveform of the polarization signal 13-1, the changes of the envelope signals 14-2 and 155-2 are small.
  • the slice level 16-2 immediately returns to the normal level. Therefore, a large shift of the slice level as occurred in the comparative example is avoided in the present embodiment, and normal binarization work is performed after the slice is held.
  • FIG. 7 is a diagram showing a second embodiment of the defect detection circuit of the present invention.
  • the defect detection circuit 76-2 shown in FIG. 7 includes a difference circuit 81, a slice voltage generator 82, and a comparator 83, similarly to the defect detection circuit 76-1 shown in FIG. A further slice voltage generator 85 and a comparator 86 are provided. Then, the comparison results of the two comparators 83 and 86 are integrated by the OR gate 87 to generate a judgment signal, which is input to the AND gate 84.
  • the presence of a defect may increase or decrease the amount of reflected laser beam and the ID signal level.
  • two sets of slice voltage generators and comparators are provided to monitor changes in both polarities of the ID signal, and highly accurate defect detection is expected.
  • FIG. 8 is a diagram illustrating a third embodiment of the defect detection circuit.
  • the defect detection circuit 76-3 shown in FIG. 8 is the same as the defect detection circuit 76-2 shown in FIG. 7 except that an amplifier 88 is provided.
  • FIG. 9 is a diagram illustrating a fourth embodiment of the defect detection circuit.
  • the slice voltage of the slice voltage generator is set by the voltage value setting systems 89 and 90 with respect to the defect detection circuit 76_3 shown in FIG. This is a circuit with added functions.
  • These voltage value setting systems 89 and 90 represent the setting functions of the serial interface 77 and the overall control unit 41 shown in FIG.
  • the defect detection sensitivity is set. Further, the detection accuracy is improved by tuning the slice voltage to an optimum value according to the type of the laser power medium.
  • FIG. 10 is a diagram showing a fifth embodiment of the defect detection circuit.
  • the defect detection circuit 76-5 shown in FIG. 10 is a circuit obtained by adding a delay control circuit 91 to the defect detection circuit 76-1 shown in FIG.
  • the delay control circuit 91 shown in FIG. 10 is a circuit for delaying only the falling evening of the determination signal by a predetermined time. Due to such a delay, the time interval during which the judgment signal rises becomes long, so even if the judgment signal falls while the laser spot passes through the defect position, a reproduction error is avoided. can do.
  • FIG. 11 is a diagram showing a sixth embodiment of the defect detection circuit.
  • the defect detection circuit 76-6 shown in Fig. 11 is added to the defect detection circuit 76-4 shown in Fig. 9 with the function of limiting the output of the judgment signal in accordance with the Enab 1 e signal 92. Circuit.
  • the Enab 1 e signal 92 is a signal having a value of “1” during a read operation and a value of “0” upon confirming reproduction in a write operation. If the output of the judgment signal is limited by such an Enab 1 e signal 92, the judgment signal is not output at the time of playback confirmation in the write operation, and even if a defect exists, the peak hold portion is not generated.
  • the peak hold portion is not generated.
  • a slice level 16 shift occurs as shown in Part (C) of Figure 1.
  • the charge current value is switched by switching the on / off state of the charge / discharge constant current power supply according to the determination signal of the defect detection circuit, and the tracking sensitivity of the envelope changes. It is desirable that the amount of change in sensitivity at that time can be adjusted.
  • FIG. 12 is a diagram showing a peak hold unit in which the amount of change in sensitivity can be adjusted.
  • the peak hold section shown in this figure is provided with a current value setting section 24 ′ that sets the charge current value of the charge constant current power supply that is switched on and off according to the judgment signal of the defect detection circuit 76-6. Have been. For this reason, for example, when signal reproduction fails during read operation or when reproduction confirmation fails during write operation, the charge current value can be reset to tune to the optimum sensitivity change amount. Thereby, the signal reproduction capability can be improved.
  • FIG. 13 is a diagram showing another form of the peak hold unit.
  • the peak hold unit 74 'shown in FIG. 13 is a circuit in which an analog switch 29 is added to the peak hold circuit 20 of the comparative example shown in FIG.
  • the peak hold unit 74 'shown in FIG. 13 is also a circuit incorporated as the top peak hold (PH) unit 74a shown in FIG.
  • the judgment signal output from the defect detection circuit 76-6 is input to the analog switch 29, and the analog switch 29 is turned on in accordance with the judgment result that there is no defect, and in accordance with the judgment result that there is a defect.
  • the analog switch 29 is turned off.
  • the peak hold section 74 When the analog switch 29 is in the ON state, the peak hold section 74 'becomes a circuit exactly the same as the peak hold circuit 20 of the comparative example, and tracks the peak of the reproduced signal with a predetermined sensitivity. On the other hand, when the analog switch 29 is in the off state, the output of the peak hold section 74 is fixed, and the sensitivity of the peak hold section 74 ′ to track the peak of the reproduction signal is “0”. Therefore, the analog switch 29 is an example of the sensitivity setting unit according to the present invention.
  • Figure 14 shows the envelope signal generated by the peak hold section shown in Figure 13.
  • Part (A) of FIG. 14 shows the envelopes 14-3 and 15-3 generated by the peak hold section 7 4 '.
  • the level of the ID signal 17 shown in part (B) of Figure 14 is below the slice voltage 18 and the envelope signals 14-3 and 15-3 are the polarization signals.
  • FIG. 15 is a diagram showing a seventh embodiment of the defect detection circuit.
  • the defect detection circuit 76-7 shown in FIG. 15 is a circuit in which a counter 93, a register 94, and a comparator 95 are added to the defect detection circuit 76-6 shown in FIG.
  • the Enab1e signal shown here is a signal having a value of “1” when the reproduction is confirmed in the write operation.
  • the defect detection circuit 76-7 shown in FIG. 15 is a more complicated circuit than the defect detection circuits of the above-described embodiments, but can be realized by a sufficiently small circuit.
  • the register 94 receives and holds a defect count slice value by the overall control unit via the serial interface 77 shown in FIG.
  • the judgment signal and the read clock are input to the counter 93. If the value of the judgment signal is “1 J”, the counter 93 counts the read clock. In other words, the count value of the counter 93 is defective. Will be shown.
  • the comparator 95 stops the binarization work. Is output to the binarizing circuit 78 shown in FIG. As a result, a reproduction error is forcibly generated, and the sector being checked for reproduction is replaced as a defective sector, and the quality of information recording is improved.
  • a very simple determination method is exemplified as a defect determination method in the defect detection circuit.
  • another determination method may be used in the defect determination unit according to the present invention.
  • the sensitivity setting of the peak hold unit and the on / off setting of the binarization circuit are exemplified as methods of using the determination result by the defect detection circuit.
  • the usage is not limited.
  • an optical disk is illustrated as an example of the information storage medium according to the present invention.
  • the shape of the information storage medium according to the present invention is not limited to a disk shape.
  • the shape may be as follows.
  • small-scale and high-accuracy defect detection means can be obtained. For this reason, it is possible to accurately eliminate defective sections at the time of recording and to improve the reproduction capability at the time of reproduction.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

Moyens de détection de défauts miniaturisés et extrêmement précis servant à éliminer un défaut pendant l'enregistrement et à améliorer la reproductibilité pendant la reproduction. Ces moyens de détection de défaut effectuent, de façon caractéristique, la détection d'un défaut éventuel au moyen d'un signal d'intensité représentant l'intensité de la lumière réfléchie par un support de mémorisation d'information dans la zone dans laquelle l'information est enregistrée au moyen d'un procédé d'enregistrement magnéto-optique.
PCT/JP2001/006974 2001-08-13 2001-08-13 Dispositif de memorisation d'information et circuit de detection de defaut WO2003032308A1 (fr)

Priority Applications (2)

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JP2003535189A JPWO2003032308A1 (ja) 2001-08-13 2001-08-13 情報記憶装置および欠陥検出回路
PCT/JP2001/006974 WO2003032308A1 (fr) 2001-08-13 2001-08-13 Dispositif de memorisation d'information et circuit de detection de defaut

Applications Claiming Priority (1)

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PCT/JP2001/006974 WO2003032308A1 (fr) 2001-08-13 2001-08-13 Dispositif de memorisation d'information et circuit de detection de defaut

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009516316A (ja) * 2005-11-14 2009-04-16 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 光学式担体上のヘッダ領域を検出する方法および光学式ドライブ

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04105824U (ja) * 1991-02-22 1992-09-11 日本電気ホームエレクトロニクス株式会社 光磁気記録媒体検査装置
JPH06302040A (ja) * 1993-04-13 1994-10-28 Shin Etsu Chem Co Ltd 光磁気ディスク検査装置
JPH06338144A (ja) * 1993-05-26 1994-12-06 Sony Corp ディスク再生装置
JP2000268430A (ja) * 1999-03-16 2000-09-29 Hitachi Maxell Ltd 光磁気記録媒体

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04105824U (ja) * 1991-02-22 1992-09-11 日本電気ホームエレクトロニクス株式会社 光磁気記録媒体検査装置
JPH06302040A (ja) * 1993-04-13 1994-10-28 Shin Etsu Chem Co Ltd 光磁気ディスク検査装置
JPH06338144A (ja) * 1993-05-26 1994-12-06 Sony Corp ディスク再生装置
JP2000268430A (ja) * 1999-03-16 2000-09-29 Hitachi Maxell Ltd 光磁気記録媒体

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009516316A (ja) * 2005-11-14 2009-04-16 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 光学式担体上のヘッダ領域を検出する方法および光学式ドライブ

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