JP2005071444A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform an accurate trial writing operation more quickly on the MSR reproducing medium of a GIGAMO standard without needing any special manufacturing method for a medium. <P>SOLUTION: On the basis of the instruction of a CPU 19 constituting a lowest reproducing light intensity calculating means, an evaluative reproducing light intensity calculating means, and a verifying means, the intensity information of reproducing laser power is fed to a reproducing intensity control part 14 for controlling the intensity of the reproducing laser power, and what level of a current is supplied to an LD driver 11 is instructed. Laser reproducing intensity when reproducing intensity is varied by the reproducing intensity control part 14 by the instruction of the CPU 19, i.e., when so-called trial reading is carried out, is stored in a read power storage part 16 which is a RAM. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus that uses a laser beam to write record information on a recording medium on a disk, and performs readout by magnetic super-resolution.

  In conventional magneto-optical recording, a magneto-optical recording system represented by the ISO standard is well known.

  In these magneto-optical recordings, the laser beam is irradiated to the perpendicular magnetization pus vacuum-deposited on the transparent substrate of the recording medium, the temperature of the perpendicular magnetization film is raised to the Curie point, and an external magnetic field is applied to the external magnetic field. Recording is performed by orienting a perpendicular magnetization film in the direction.

  The recording density at this time is determined by the size of a region having a temperature distribution by a laser beam spot irradiated on the perpendicular magnetization film, that is, a temperature distribution higher than the Curie point.

  For this reason, normally, it is not possible to form a recording portion smaller than the spot diameter of the laser, and the improvement of the recording density is carried out by reducing the spot diameter of the laser beam.

  On the other hand, what is called mark edge recording, in which recording is performed by giving information to both end edges of one pit instead of giving so-called “1” and “0” information to one pit. It is known in magneto-optical recording.

  In the mark edge recording, an improvement in recording density can be achieved. However, in order to maintain the reliability of information, it is necessary to accurately form the edge.

  For this reason, when performing magneto-optical recording by normal mark edge recording, it is necessary to perform so-called test writing in which optimum recording power is obtained by changing the recording power to the test track in advance and performing recording. Yes.

  Furthermore, in recent years, only the magnetic domain region smaller than the minimum spot diameter of the laser beam is made to be higher than the Curie point by dividing the irradiation intensity and timing of the laser beam into a plurality of stages and changing the thermal diffusion coefficient of the recording medium. So-called “brush tip recording” is possible, in which recording is performed by raising.

  At this time, in order to read a magnetic domain region recorded smaller than the spot diameter of the laser beam, a technique of magnetic super-resolution (hereinafter referred to as MSR) is required.

  In MSR, when a reproducing layer is provided on a magnetic film (hereinafter referred to as a recording layer) for recording via an intermediate layer and reproduction is performed by irradiating a laser, the thermal characteristics of the intermediate layer (Curie point, etc.) And applying an external magnetic field restricts (masks) the area where information on the recording layer is transferred.

  Further, by masking only a part of the laser spot, the magnetic domain orientation of the recording layer in a region smaller than the laser spot is transferred to the reproducing layer and reproduced.

  There are methods called FAD, CAD, and RAD in the area where the information of the recording layer is transferred to and read from the reproducing layer (hereinafter referred to as an aperture) depending on the relationship between the laser spot and the mask area.

  In a recording / reproducing apparatus using MSR, proper reading cannot be performed unless a mask is correctly formed. For this reason, the MSR method requires so-called trial reading for obtaining optimum reproduction power.

  For example, in Japanese Patent Laid-Open No. 2000-163823, in the FAD method of the MSR reproduction medium, the recording power is adjusted by detecting a long mark signal by utilizing the characteristic that a mask is not formed in a low reproduction power region. There has been proposed a technique of performing so-called test writing and performing test reading in a state where the recording power is guaranteed.

  In recent years, for example, in the 90 mm 1.3 GB magneto-optical recording standard (GIGAMO standard) proposed by Fujitsu-Sony, signals are read using MSR reproduction by the D-RAD method.

  The D-RAD method is an improved version of the RAD (Rear Aperture Detection) method mentioned earlier, and masks the low temperature part of the front of the light spot under temperature conditions to form a rear aperture. In the state, it is masked by the influence of the externally applied magnetic field.

For example, in JP-A-2002-8280, in a GIGAMO standard medium, a long mark / space repeated pattern is recorded on a test track, and the reproduction intensity is increased until direct transfer to the reproduction layer is performed without applying a reproduction magnetic field. The signal is reproduced, and the reproduction power is directly stored as the transfer start power Pr2, and then the reproduction power is varied while applying an external magnetic field. The reproduction start power at that time is Pr1, and the reproduction intensity Pr is Pr = Γ × Pr1 (constant of γ ≧ 1)
Or
Pr = (Pr1 + Pr2) / 2
And performing trial reading using the average of both Pr1 and Pr2 as the reproduction intensity Pr.
JP 2000-163823 A Japanese Patent Laid-Open No. 2002-8280

  However, the above Japanese Patent Laid-Open No. 2000-163823 is limited to the CAD system among the MSR reproducing media, and is applied to the RAD and D-RAD system media in which all spots are masked in the low reproducing power region. I can't.

  In the above Japanese Patent Laid-Open No. 2002-8280, it is necessary to increase the reproduction power to an intensity that can be directly transferred without applying a magnetic field.

  In the D-RAD medium, the reproduction power necessary for performing the MSR reproduction is at least about 5 mW at the outer periphery reproduction of the drive rotating at 3000 rpm, whereas the reproduction power that can be directly transferred is considerably large as about 8 mW.

  At this time, high frequency superposition (HFM) is also required for reproduction, increasing the burden on the electrical system. Further, since the reproduction power is scanned by trial reading from around 5 mW to around 8 mW, the time required for trial reading becomes long.

  The present invention has been made in view of the above circumstances, and an optical disk apparatus capable of performing an accurate trial reading operation more quickly without requiring a special production method for a GIGAMO standard MSR playback medium. The purpose is to provide.

  The optical disk apparatus of the present invention is a minimum reproduction light intensity for calculating a minimum reproduction light intensity Prmin that can be super-resolution reproduced in an optical disk apparatus that performs super-resolution reproduction by irradiating a recording medium with laser light and applying an external magnetic field. Calculation means, evaluation reproduction light intensity calculation means for calculating a first evaluation reproduction light intensity Pr1 and a second evaluation reproduction light intensity Pr2 from the minimum reproduction light intensity Prmin, the first evaluation reproduction light intensity Pr1, and the And verification means for verifying the validity of the minimum reproduction light intensity Prmin based on the second evaluation reproduction light intensity Pr2.

  According to the present invention, there is an effect that an accurate trial reading operation can be performed more quickly without requiring a special production method for the MSR playback medium of the GIGAMO standard.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 relate to the first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of the optical disk apparatus, FIG. 2 is a first flowchart for explaining the operation of the optical disk apparatus of FIG. 1, and FIG. 6 is a second flowchart for explaining the operation of the optical disc apparatus of FIG.

  As shown in FIG. 1, the optical disc apparatus 1 of this embodiment includes an LD 9 that emits laser light, an LD driver 11 that drives the LD 9, an optical head 5 that irradiates the optical disc 2 with laser light, and an optical disc 2 An optical system including a PD (photo detector) 10 for detecting return light is provided.

  The optical disc apparatus 1 also includes a reproduction intensity control unit 14 that controls the intensity of the reproduction laser power of the LD 9 when reproducing information, a bias generation apparatus 4 that generates a magnetic field, and a reproduction magnetic field intensity of the bias generation apparatus 4. A magnetic field intensity control unit 18 for controlling the above, a recording intensity control unit 13 for controlling the intensity of the recording laser power of the LD 9 when recording information, and a pulse corresponding to the actual recording signal that receives information on the recording signal A recording signal processing unit 12 that generates a light emission pattern and outputs it to the LD driver 11, a reproduction signal processing unit 15 that processes a reproduction signal from the PD 10, and a read power that stores the reproduction intensity of the laser when trial reading is performed. A storage unit 16, a read magnetic field storage unit 17 that stores the reproduction magnetic field strength when trial reading is performed by changing the magnetic field, and a CPU 19 that controls these units are provided. CPU19 is adapted to be connected to an external host computer 3 by via SCSI I / F20.

  The CPU 19 of the optical disc apparatus 1 constitutes minimum reproduction light intensity calculation means, evaluation reproduction light intensity calculation means, and verification means.

  In FIG. 1, when reading information with the optical disk 2 inserted in the optical disk device 1, the reproduction intensity control unit 14 that controls the intensity of the reproduction laser power is controlled based on an instruction from the CPU 19 to determine the reproduction laser power. The intensity information is given, and an instruction is given as to how much current is to flow through the LD driver 11.

  Depending on the amount of current of the LD driver 11, the intensity of the laser beam emitted from the LD 9 can be arbitrarily changed.

  The variable reproduction laser light emitted from the LD 9 is reflected by the rising mirror 7 in the separated optical head 5 via the beam splitter 8, and condensed and irradiated on the optical disk 2 by the objective optical system 6.

  The optical head 5 can be driven in a one-dimensional direction in parallel with the optical disk 2 rotated by a spindle motor (not shown), and the reproduction light can be condensed on an arbitrary part in the surface of the optical disk 2.

  When a reproducing magnetic field is required at the time of reproduction, magnetic field strength information is given from the CPU 19 to the magnetic field strength control unit 18 to cause the bias generator 4 to generate a magnetic field. Reflected reproduction light from the surface of the optical disk 2 passes again through the objective optical system 6 and is reflected by the mirror 7, divided by the beam splitter 8, and detected by the PD 10.

  The detected reproduction signal is processed by the reproduction signal processing unit 15 as information corresponding to the signal intensity, converted into data, and transmitted to the CPU 19.

  When information is recorded on the optical disc apparatus 1, the recording intensity control unit 13 is provided with the intensity information of the recording laser power from the CPU 19, and how much current is supplied to the LD driver 11 via the recording signal processing unit 12. Instruct whether to flow.

  Further, the recording signal processing unit 12 receives the information of the recording signal from the CPU 19, generates a pulse light emission pattern according to the actual recording signal, and performs pulse light emission at the previous intensity.

  The reproduction intensity of the laser at the time of performing so-called trial reading when the reproduction intensity is variously changed via the reproduction intensity control unit 14 according to an instruction from the CPU 19 is stored in the read power storage unit 16 which is a RAM.

  Further, the reproduction magnetic field strength when trial reading is performed by so-called magnetic field change when the magnetic field strength is variously changed via the magnetic field strength control unit 18 according to the instruction of the CPU 19 is stored in the read magnetic field storage unit 17 which is a RAM. Is done.

  Next, the operation of this embodiment will be described with reference to the flowcharts in FIG.

  When trial reading is performed by the optical disc apparatus 1 of the present embodiment, an area for trial reading is first determined in step S1 according to the flowchart processing of FIG. Here, it is set at the head of the test track area prepared for power adjustment of the optical disc 2.

  Next, in step S1, laser light from the sector LD9 that performs trial reading is sought to erase and record the area.

  Note that the laser intensity from the LD 9 at the time of recording is prepared by preparing an initial recording power table for each band in the CPU 19 in advance.

  The recording signal pattern may be a repeated mark / space signal having the same length, or may be a random pattern. In the former case, the signal amplitude or the reading error rate (hereinafter referred to as error rate) can be used as the recording signal judgment condition, and in the latter case, the signal error rate can be used.

  In this embodiment, a long mark / space repetitive signal is used as a recording signal pattern, and the determination is made based on the amplitude of the signal.

  Next, in order to obtain an accurate minimum reproduction power by trial reading in step S3, a flag called a trial reading impossible flag is provided and its initial value is set to zero. The trial reading impossibility flag has a function of changing the flag to 1 when a signal is not detected during the reproduction operation. Next, initial reproduction power setting is performed in step S4. As the intensity of the LD 9 at the time of reproduction, the CPU 19 prepared in advance with an initial recording power table for each band is used.

  When the reproduction intensity is set, the sector for actual trial reading is reproduced in step S5.

  Further, in step S6, it is determined whether the sector on which trial reading is being performed can be reproduced. In the present embodiment, as a reproducible condition, a condition that the reproduction signal amplitude is Zmv or more is provided.

  If the reproduction signal amplitude is detected, it means that the reproduction power capable of super-resolution reproduction has been reached, and therefore the state of the trial reading impossibility flag (trial reading impossibility flag = 1) is confirmed in step S7. Since the trial reading impossible flag is initially cleared to 0, the flag does not change if trial reading is performed in a range larger than the minimum reproduction intensity at which reproduction is possible. Conversely, a flag is set at a reproduction intensity at which reproduction is impossible.

  When the condition of step S7 is satisfied, the sequence after step S9 described later is performed, and thus the condition is satisfied with the maximum intensity that cannot be reproduced + αmW.

  For this reason, in step S8, the currently set reproduction intensity is stored in the CPU 19 as the minimum power Prmin that can be reproduced in super-resolution, and the process ends.

  If the trial reading impossible flag is 0 in step S7, it is determined that sufficient reproduction intensity for super-resolution reproduction is given, and the current reproduction intensity is lowered in step S12. In this embodiment, the value is reduced by a certain minute step αmW, but this reduction amount may be reduced by multiplication by a certain ratio.

  At this time, a lower limit XmW is provided so that the changed reproduction intensity does not become an abnormal value, and it is determined whether or not the lower limit XmW does not fall below that. In the MSR medium, the recording signal may be raised on the reproducing layer by direct transfer, and the trial reading cannot be performed correctly.

  When the reset reproduction intensity is greater than the lower limit XmW, the processing from step S5 is continued.

  If the value is below the lower limit XmW, it is determined that there is an abnormality in the sector on which the trial reading of the MSR medium is performed, and the next sector is set as the sector for trial reading in step S14.

  Then, no matter how many sectors are used, if the medium itself or the optical drive apparatus itself is defective and cannot be read correctly, the sequence process becomes infinite. Set an upper limit. Here, when the upper limit value is K and trial reading is performed for K sectors or more, the processing ends because there is an abnormality in the medium or the drive.

  Next, the process after step S9 is demonstrated. Step S9 is a case where the amplitude cannot be detected in the super-resolution reproduction, and the trial reading impossible flag is changed to 1.

  Next, the reproduction intensity is increased by a certain minute step + αmW so that super-resolution reproduction is possible in step S10.

  At this time, a certain upper limit YmW is provided so that the changed reproduction intensity does not become an abnormal value, and it is determined in step S11 whether or not the upper limit is exceeded. That is, if the reproduction intensity is too high, the recording signal is erased by the reproduction operation, which causes a serious problem. Thus, the upper limit is set in this way.

  When the reproduction intensity is less than YmW, the processing from step S5 is continued. If the reproduction intensity exceeds YmW, the signal of the sector used for the trial reading has disappeared, or an abnormality has occurred in the sector itself, and the next sector is used for the trial reading. Perform the process.

  Next, the sequence process of FIG. 3 will be described. FIG. 3 is a sequence for verifying the accuracy of the minimum intensity Prmin of super-resolution reproduction obtained in this way.

  First, in step S21, Pr1 (= Prmin-a) is subtracted by a small value a larger than a certain α in Prmin obtained in FIG. 2 and added to generate Pr2 (= Prmin + a).

  Next, in step S22, the sector used for the trial reading is sought and a signal for performing the trial reading is recorded. This operation is the same as the processing in step S2 of FIG. Next, in step S23, the reproduction intensity is set to the previously obtained Pr1, and the signal is reproduced in step S24.

  Here, since Pr1 is obtained by subtracting amW from the minimum power Prmin necessary for super-resolution reproduction, it is predicted that super-resolution reproduction cannot be performed and therefore reproduction is impossible. If reproduction becomes impossible in step S25, the sequence proceeds to step S26 and subsequent sequences. If playback is possible in step S26, the sequence proceeds to step S29 and subsequent sequences.

  First, the sequence after step S26 will be described. If it is verified that playback is impossible at Pr1, the playback intensity is changed to Pr2 at step S26. In this state, the signal is reproduced in step S27 as in step S24.

  Since Pr2 is obtained by adding amW to the minimum power Pmin necessary for super-resolution reproduction, it is predicted that reproduction is possible. Therefore, if reproduction is possible in step S28, it is determined that Prmin is valid, and the process is normally terminated. If reproduction becomes impossible in step S28, the sequence proceeds to step S29 and subsequent sequences.

  Next, the process after step S29 is demonstrated. If the data is reproduced with Pr1 or Pr2 cannot be reproduced, there may be an abnormality in the sector used for trial reading.

  Therefore, the sector used for trial reading is changed to the next sector in step S29, and the processing in step S22 and subsequent steps is continued. At this time, in step S30, if there is an abnormality in the medium itself or the drive, the sequence process becomes infinite. Therefore, if the sector used for the trial reading is equal to or more than K sectors, the process ends as an abnormality has occurred. .

  As described above, in this embodiment, Prmin can be obtained with an accuracy of ± amW or less. Therefore, by suppressing the value of a, the accuracy can be improved.

  In addition, the reproduction intensity actually used for super-resolution reproduction can be calculated with accuracy according to Prmin by adding or multiplying Prmin.

  Further, although not described in the present embodiment, the sequence of FIG. 2 can be processed by replacing the reproduction LD light intensity with the reproduction magnetic field intensity as it is.

  The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the scope of the present invention.

1 is a block diagram showing a configuration of an optical disc apparatus according to Embodiment 1 of the present invention. First flowchart for explaining the operation of the optical disc apparatus of FIG. 2 is a second flowchart for explaining the operation of the optical disk apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus 2 ... Optical disk 3 ... Host computer 4 ... Bias generator 5 ... Optical head 9 ... LD
10 ... PD
DESCRIPTION OF SYMBOLS 11 ... LD driver 12 ... Recording signal processing part 13 ... Recording intensity control part 14 ... Reproduction intensity control part 15 ... Reproduction signal processing part 16 ... Read power storage part 17 ... Read magnetic field storage part 18 ... Magnetic field intensity control part 19 ... CPU
20 ... SCSI I / F
Attorney Susumu Ito

Claims (8)

In an optical disc apparatus that performs super-resolution reproduction by irradiating a recording medium with laser light and applying an external magnetic field,
Minimum reproduction light intensity calculating means for calculating the minimum reproduction light intensity Prmin capable of super-resolution reproduction;
An evaluation reproduction light intensity calculating means for calculating a first evaluation reproduction light intensity Pr1 and a second evaluation reproduction light intensity Pr2 from the minimum reproduction light intensity Prmin;
An optical disc apparatus comprising: verification means for verifying the validity of the minimum reproduction light intensity Prmin based on the first evaluation reproduction light intensity Pr1 and the second evaluation reproduction light intensity Pr2. The evaluation reproduction light intensity calculation means includes:
The first evaluation reproduction light intensity Pr1 and the second evaluation reproduction light intensity Pr2 are set as Pr1 <Prmin <Pr2
Calculated from the minimum reproduction light intensity Prmin so as to satisfy
The verification means means that the reproduction signal is not detected at the first evaluation reproduction light intensity Pr1, and the reproduction signal is detected at the second evaluation reproduction light intensity Pr2, so that the minimum reproduction light intensity is detected. The optical disc apparatus according to claim 1, wherein the validity of Prmin is verified. The evaluation reproduction light intensity calculation means includes:
The first evaluation reproduction light intensity Pr1 is calculated by subtracting a predetermined value from the minimum reproduction light intensity Prmin, and the second evaluation reproduction light intensity Pr2 is calculated by adding the predetermined value from the minimum reproduction light intensity Prmin. The optical disk device according to claim 1, wherein the optical disk device is calculated. In an optical disc apparatus that performs super-resolution reproduction by irradiating a recording medium with laser light and applying an external magnetic field,
A minimum applied magnetic field strength calculating means for calculating a minimum applied magnetic field strength Hrmin capable of super-resolution reproduction;
An evaluation reproduction magnetic field strength calculating means for calculating a first evaluation reproduction magnetic field strength Hr1 and a second evaluation reproduction magnetic field strength Hr2 from the minimum applied magnetic field strength Hrmin;
An optical disc apparatus comprising: verification means for verifying validity of the minimum applied magnetic field strength Hrmin based on the first evaluation reproduction magnetic field strength Hr1 and the second evaluation reproduction magnetic field strength Hr2. The evaluation reproducing magnetic field strength calculating means includes
The first evaluation reproduction magnetic field strength Hrr1 and the second evaluation reproduction magnetic field strength Hrr2 are set to Hr1 <Hrmin <Hr2
Calculated from the minimum applied magnetic field strength Hrmin to satisfy
The verification means means that the reproduction signal is not detected at the first evaluation reproduction magnetic field strength Hr1, and the reproduction signal is detected at the second evaluation reproduction magnetic field strength Hr2, so that the minimum applied magnetic field strength is obtained. The optical disk apparatus according to claim 4, wherein validity of Hrmin is verified. The evaluation reproducing magnetic field strength calculating means includes
The first evaluation reproduction magnetic field strength Hr1 is calculated by subtracting a predetermined value from the minimum applied magnetic field strength Hrmin, and the second evaluation reproduction magnetic field strength Hr2 is calculated by adding the predetermined value from the minimum applied magnetic field strength Hrmin. The optical disc apparatus according to claim 5, wherein the optical disc device is calculated. In a reproducing light intensity setting method of an optical disc apparatus that performs super-resolution reproduction by irradiating a recording medium with laser light and applying an external magnetic field,
A minimum reproduction light intensity calculation step for calculating a minimum reproduction light intensity Prmin capable of super-resolution reproduction;
An evaluation reproduction light intensity calculating step for calculating a first evaluation reproduction light intensity Pr1 and a second evaluation reproduction light intensity Pr2 from the minimum reproduction light intensity Prmin;
And a verification step for verifying the validity of the minimum reproduction light intensity Prmin based on the first evaluation reproduction light intensity Pr1 and the second evaluation reproduction light intensity Pr2. Setting method. In a method for setting the reproduction light intensity of an optical disc apparatus that performs super-resolution reproduction by irradiating a recording medium with laser light and applying an external magnetic field,
A minimum applied magnetic field strength calculating step for calculating a minimum applied magnetic field strength Hrmin capable of super-resolution reproduction;
An evaluation reproduction magnetic field strength calculating step of calculating a first evaluation reproduction magnetic field strength Hr1 and a second evaluation reproduction magnetic field strength Hr2 from the minimum applied magnetic field strength Hrmin;
And a verification step for verifying the validity of the minimum applied magnetic field strength Hrmin based on the first evaluation reproducing magnetic field strength Hr1 and the second evaluation reproducing magnetic field strength Hr2. Setting method.

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