Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10595—Control of operating function
  • G11B11/10597—Adaptations for transducing various formats on the same or different carriers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10502—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing characterised by the transducing operation to be executed
  • G11B11/10528—Shaping of magnetic domains, e.g. form, dimensions
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10532—Heads
  • G11B11/10541—Heads for reproducing
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
  • G11B11/10584—Record carriers characterised by the selection of the material or by the structure or form characterised by the form, e.g. comprising mechanical protection elements
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10502—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing characterised by the transducing operation to be executed
  • G11B11/10515—Reproducing
• • 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
  • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
  • G11B7/0079—Zoned data area, e.g. having different data structures or formats for the user data within data layer, Zone Constant Linear Velocity [ZCLV], Zone Constant Angular Velocity [ZCAV], carriers with RAM and ROM 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
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/2403—Layers; Shape, structure or physical properties thereof
  • G11B7/24035—Recording layers
  • G11B7/24038—Multiple laminated recording layers
• • 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
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/2407—Tracks or pits; Shape, structure or physical properties thereof
  • G11B7/24085—Pits

Definitions

• a magneto-optical recording medium a method for manufacturing the same, and a magneto-optical recording device
• the present invention relates to a magneto-optical recording medium having both functions of ROM (Read Only Memory) based on phase pits formed on a substrate and RAM (R and om Access Memory) based on a magneto-optical recording film.
• the present invention relates to a magneto-optical recording device, and more particularly to a magneto-optical recording medium and a magneto-optical recording device for favorably reproducing both of them.
• FIG. 21 shows a plan view of a conventional ISO standard magneto-optical disk.
• the magneto-optical disk 70 is divided into a lead-in area 71, a lead-out area 72, and a user area 73.
• the lead-in area 71 and the lead-out area 72 are ROM areas composed of phase pits. Phase pits are formed on the polycarbonate substrate with irregularities. The depth of the phase pits serving as the ROM area is set so that the light intensity modulation during reproduction is maximized.
• the area between the lead-in area 71 and the lead-out area 72 corresponds to the user area 73, that is, the RAM area. The user can freely record information in this RAM area.
• FIG. 22 shows an enlarged view of the user area 73.
• a phase pit 78 serving as a header section 76 and a user data section 77 are established on a land 75 sandwiched between dull tubes 74 serving as a tracking guide.
• the user data section 77 is composed of flat lands 75 sandwiched between the louvers 4. Information is recorded in the user data section 77 as a magneto-optical signal.
• the user area 73 When reading the magneto-optical signal, the user area 73 is irradiated with a weak laser beam. By the effect of what is called an effect as much as possible, the polarization plane of the laser beam changes according to the direction of the magnetic field of the recording film. The presence or absence of a signal is determined based on the strength of the polarization component of the reflected light. Thereby, the RAM information is read.
• Research and development utilizing such features of the magneto-optical disk have been promoted. For example, as disclosed in Japanese Patent Application Laid-Open No. 6-202850, a concurrent ROM-RAM optical disk capable of simultaneous reproduction by ROM-RAM has been proposed. You. For example, FIG.
• FIG. 23 shows a cross-sectional structure in the radial direction of a magneto-optical recording medium 81 that can be simultaneously reproduced by the ROM-RAM.
• a dielectric film 84 a magneto-optical recording film 85 such as TbFeCo
• a dielectric film 86 a dielectric film 86
• A1 aluminum
• a reflective film 87 and a UV (ultraviolet) cured film 88 as a protective film are laminated.
• FIGS. 23 and 24 ROM information is fixedly recorded by the phase pit row PP on the substrate 83.
• the RAM information ⁇ MM is recorded in the phase pit row PP by magneto-optical recording.
• FIG. 23 is a sectional view taken along the line 23-23 in FIG.
• the phase pit PP serves as a tracking guide.
• the group 74 as shown in FIG. 22 is not formed.
• an optical information recording medium having such ROM information and RAM information on the same recording surface there are many problems in simultaneously reproducing ROM information composed of phase pits PP and RAM information composed of magneto-optical recording MM. Exists.
• the light intensity modulation that occurs when reading ROM information contributes to the reproduction noise of RAM information.
• the applicant has proposed a solution in an international application filed with PCTZJ P 02/00159 (international filing date January 11, 2002).
• the light intensity modulation noise is reduced by negatively feeding back the light intensity modulation signal accompanying the reading of ROM information to the reading drive laser.
• the light intensity modulation degree of the ROM information is large, this alone cannot sufficiently reduce the noise.
• Patent Document 1
• Patent Document 2
• the present invention has been made in view of the above circumstances, and provides a magneto-optical recording medium and a magneto-optical recording apparatus for stably and simultaneously reproducing ROM information composed of phase pits and RAM information by magneto-optical recording.
• the purpose is to:
• Another object of the present invention is to provide a magneto-optical recording medium and a magneto-optical recording device for suppressing jitter of a reproduction signal of ROM information and RAM information within a predetermined range.
• a substrate centered on a tangent in a phase pit row direction passing through a position where a measurement light beam is irradiated on the substrate with respect to a reference plane orthogonal to the measurement light beam.
• the first birefringence value of a single pass measured at an angle of 20 ° and the posture of the substrate at 20 ° around a straight line perpendicular to the phase pit row direction in the substrate plane with respect to the reference plane
• the difference from the single-pass second birefringence value measured in the step is set to 47 [nm] or less.
• the substrate may be made of, for example, any of polycarbonate and amorphous polyolefin.
• the optical depth of the phase pit is set in the range of 0.06 ⁇ to 0.14 ⁇ , including the wavelength of the reading light beam used for reading information.
• ROM information is recorded by phase pits. The deeper the optical depth of the phase pit, the more reliably the ROM information can be read. So on the other hand, RAM information can be recorded on the recording medium by the magnetization of the recording magnetic film. The smaller the optical depth of the phase pit, the more reliable the RAM information can be read. If the optical depth of the phase pit is set as described above, not only the OM information but also the RAM information can be reliably read.
• the optical depth of the phase pit be set in the range of 0.073 to 0.15, where ⁇ is the wavelength of the reading light beam used for reading information.
• the modulation degree of the phase pit may be set, for example, in the range of 8% to 55%. If the modulation degree of the phase pit is set in such a range, jitter of 15% or less and stable tracking can be realized.
• Such a recording medium is produced by injection molding using polycarbonate or amorphous polyolefin.
• the substrate may be subjected to an annealing treatment at a temperature range of 90 ° C. or higher.
• the birefringence difference of the substrate can be suppressed to 37 [nm] or less.
• the temperature range is 100. If it is set at C or more, the birefringence difference is kept at 32 [nm] or less. At this time, when reading the RAM information, the jitter can be suppressed to 8 [] or less.
• the temperature range is preferably set to 13 (TC or less. If the temperature range exceeds 130 ° C, the board will be warped. The warp prevents reading of RAM information.
• a magnetic film is formed on the surface of the substrate.
• a light source that outputs a light beam, a spindle that supports the recording medium, and a light beam that is directed toward the recording medium with a polarization plane orthogonal to a recording track on the recording medium.
• a recording medium driving device including an irradiation optical system may be provided. In such a recording medium driving device, better jitter can be secured than when a light beam is directed toward the recording medium with a plane of polarization parallel to the recording track on the recording medium. .
• the recording medium driving device includes a first photodetector that detects rotation of a polarization plane between a light beam reflected by the recording medium and a light beam before reflection, and a second photodetector that detects the intensity of the light beam reflected by the recording medium. What is necessary is just to incorporate two photodetectors.
• the first photodetector is used to decode the RAM information.
• the second photodetector is used to decode the ROM information.
• FIG. 1 is a perspective view schematically showing the appearance of a magneto-optical disk.
• FIG. 2 is an enlarged partial vertical sectional view taken along line 2-2 of FIG.
• FIG. 3 is a schematic diagram showing an outline of a method of measuring birefringence.
• FIG. 4 is an enlarged partial perspective view of the magneto-optical disk illustrating the concepts of track pitch, phase pit width, and shortest pit.
• FIG. 5 is a partially enlarged vertical sectional view showing a conventional continuous groove substrate for land recording.
• FIG. 6 is a schematic diagram showing an outline of a method of measuring birefringence.
• FIG. 7 is a graph showing the correlation between the birefringence difference of the substrate and the jitter when reading RAM (Random Access Memory) information based on the magnetization of the recording magnetic film.
• FIG. 8 is a graph showing the correlation between the birefringence difference of the substrate and the jitter when reading ROM (Read Only Memory) information based on phase pits.
• FIG. 9 is a graph showing the relationship between the birefringence difference and the magneto-optical reproduction signal jitter on a substrate on which only lands are formed.
• Figure 10 is a graph showing the correlation between the birefringence of a normally incident light beam and RAM jitter.
• FIG. 11 is a table showing the relationship between the tilt angle of the substrate and the birefringence difference.
• FIG. 12 is a graph showing the relationship between the inclination of the substrate and the birefringence difference when the jitter is suppressed to 10% or less.
• Fig. 13 is a table showing the birefringence difference, RAM jitter and warpage of the substrate according to the annealing temperature.
• FIG. 14 is a graph showing the relationship between the optical depth of phase pits and jitter when reading RAM information and reading ROM information.
• FIG. 15 is a conceptual diagram illustrating a method of defining a modulation factor.
• FIG. 16 is a graph showing the relationship between the modulation degree of the phase pit and the jitter when reading the RAM information and reading the ROM information.
• FIG. 17 is a schematic diagram conceptually showing the configuration of the magneto-optical disk drive.
• FIG. 18 is an enlarged partial perspective view showing the relationship between the recording track and the polarization plane of the laser beam.
• FIG. 19 is a graph showing the correlation between birefringence difference and jitter when vertical polarization or horizontal polarization is used for reading RAM information based on the magnetization of the recording magnetic film.
• FIG. 20 is a graph showing the correlation between the birefringence difference and jitter when vertical polarization or horizontal polarization is used in reading ROM information based on phase pits.
• FIG. 21 is a plan view of a conventional ISO standard magneto-optical disk.
• FIG. 22 is a partially enlarged view of a user area of a conventional magneto-optical disk.
• FIG. 23 is a partial vertical sectional view of a user area of a conventional magneto-optical disk.
• FIG. 24 is a diagram showing the relationship between the phase pits of a magneto-optical disk capable of simultaneously reproducing ROM information and RAM information and MO (magneto-optical recording) signals.
• FIG. 1 shows a magneto-optical recording medium, that is, a magneto-optical disk 1I.
• This magneto-optical disk 11 is configured as a so-called concurrent ROM-RAM magneto-optical disk.
• the diameter of the magneto-optical disk 11 is set to, for example, 120 mm.
• FIG. 2 schematically shows a cross-sectional structure of the magneto-optical disk 11.
• the magneto-optical disk 11 includes a substrate 12.
• the substrate 12 is made of a light transmissive material.
• a resin material such as a polycarbonate or an amorphous polyolefin may be used.
• the substrate 12 is formed by an injection molding method.
• Phase pits 13 are transferred and formed on the surface of the substrate 12. Phase pits 13 are substrates
• the undercoat film 14, the recording magnetic film 15, the auxiliary magnetic film 16, the overcoat film 17, the reflective film 18 and the protective film 19 are phase pits.
• the magneto-optical disk 11 has a single-pass first birefringence value measured on the substrate 12 by the first oblique incident light beam and a single-pass first birefringence value similarly measured on the substrate 12 by the second oblique incident light beam. Is set to 47 nm or less.
• the substrate 12 adjusts the irradiation position of the measurement light beam 21 with respect to a reference plane 22 orthogonal to the measurement light beam 21 as shown in FIG. 3, for example. It is held at a position inclined at an angle ⁇ of 20 degrees around the passing radius line 23.
• the substrate 12 is moved in the phase pit row direction passing through the irradiation position of the measurement light beam 21 with respect to the reference plane 22 orthogonal to the measurement light beam 21. That is, the posture is maintained at an angle iS of 20 degrees around the tangent line 24 in the tracking direction.
• a general birefringence measuring device may be used.
• the inventor prepared a phase pit substrate having a thickness of 1.2 mm.
• a phase pit was formed by EFM modulation.
• the phase pit substrate was made by injection molding.
• a stamper having a plurality of phase pit depths was prepared.
• the depth of the phase pit was changed to several types.
• a continuous groove substrate composed of a conventional continuous track for land recording was prepared.
• the track pitch (distance between adjacent groups) of the continuous groove substrate for land recording is 0.90 m.
• the material of the substrate and the conditions of substrate annealing to be described later were the same. These multiple substrates were mounted on a birefringence meter. In the above-described manner, as shown in FIG. 6, the birefringence difference of the substrate was measured at an angle of 20 degrees.
• AD R-200B manufactured by OWIC Co., Ltd. was used as a birefringence measuring instrument.
• the wavelength of the laser beam of the birefringence measuring instrument is 635 nm.
• a magneto-optical disk was formed from the above-described phase pit substrate and continuous groove substrate.
• the phase pit substrate and the continuous groove substrate were subjected to an initial process under a plurality of conditions. Thereafter, the phase pit substrate and the continuous groove substrate were injected into a sputtering apparatus.
• the ultimate vacuum is 5 X e— 5 [P a] It was set as follows.
• the first chamber was equipped with a Si target.
• the phase pit substrate and the continuous groove substrate were transported to the first chamber.
• Ar gas and N 2 gas were introduced into the first chamber.
• reactive sputtering was performed.
• an 8 Nm thick SiN film that is, an undercoat film 14 was formed.
• the phase pit substrate and the continuous groove substrate were transferred to the second chamber.
• Ding 22 (FeCo 12) 78 film that is, the recording magnetic film 15 and the thickness 4nm of Gd 19 (F eCo 20) film i.e. auxiliary magnetic film 16 having a thickness of 3,011,111 were deposited in sequence.
• the phase pit substrate and the continuous groove substrate were transferred to the first chamber.
• a 5 nm-thick SiN film or overcoat film 17 and a 50 nm-thick A1 (aluminum) film or reflective film 18 were formed.
• An ultraviolet curable resin coat that is, a protective film 19 was formed on the reflective film 18.
• a magneto-optical disk was created.
• the produced magneto-optical disks were sequentially mounted on a recording / reproducing apparatus.
• the ROM jitter due to the phase pit train and the M ⁇ playback jitter on the phase pit train, ie, the RAM jitter were measured.
• the wavelength of the laser beam was set to 650 ⁇ m.
• the numerical aperture NA was set to 0.55.
• the linear velocity was set to 4.8 [m / s].
• predetermined data was recorded by magnetic field modulation recording on the recording magnetic film by EFM modulation of the shortest mark of 0.832 m.
• the read power of both the ROM and RAM lasers was set to 1.5 [mW].
• Figures 7 and 8 show the measurement results of the zipper.
• the optical depth of the phase pit was set to 0.095 ⁇ (actual depth 40 nm).
• Figure 7 shows the M ⁇ playback jitter on the phase pits, ie, RAM jitter.
• FIG. 8 shows the ROM jitter of the phase pit.
• the material of the phase pit substrate was Panlite ST-3000 and AD-900TG manufactured by Teijin Limited.
• the phase pit substrate was made by injection molding.
• the annealing temperature was 90, changed to 110 ° C and 130. like this
• the birefringence difference of the 20 ° obliquely incident light beam was set to different values for the six types of magneto-optical disks.
• CD Compact Disk
• CIRC Chip-Interleaved read-Solomon Code
• the birefringence difference of the 20-degree oblique incident light beam may be set to 37 nm or less. If various fluctuation factors are expected at the maximum, the jitter should be suppressed to 8% or less. In this case, the birefringence difference of the 20 ° obliquely incident light beam may be set to 30 nm or less. If the jitter is suppressed to 8% or less, sufficient quality can be ensured without reading errors even under various fluctuations.
• the ROM jitter of the phase pit substrate was kept almost constant irrespective of the birefringence difference of the obliquely incident light beam of 20 degrees.
• the difference between the first birefringence value of the single path measured with the first obliquely incident light beam and the second birefringence value of the sinal path measured with the second obliquely incident light beam that is, birefringence. It can be seen that if the difference is reduced, the RAM jitter will be greatly improved.
• FIG. 9 shows the result of land recording, which is a usual recording method.
• land recording the jitter rises slowly with respect to the birefringence difference. Even if the birefringence difference increases to 5 O nm, It is suppressed to less than 8%. As described above, if the focus adjustment attempts to suppress jitter, the rise in RAM jitter can be almost completely suppressed due to the birefringence difference.
• FIG. 10 shows the relationship between the birefringence at normal incidence on the phase pit substrate and jitter.
• the birefringence at normal incidence is the value of the birefringence measured by setting the angle of inclination of the substrate in FIG. In other words, the substrate is maintained in a vertical posture with respect to the laser beam 24.
• This is a general method of measuring birefringence.
• FIG. 10 there is no correlation between the normal birefringence of normal incidence and the RAM jitter.
• the RAM jitter on the phase pit is closely related to the fact that the value of the birefringence measured with the obliquely incident light beam differs depending on the direction of the tilt, as shown in Figure 3.
• FIG. 10 shows the relationship between the birefringence at normal incidence on the phase pit substrate and jitter.
• FIG. 11 shows a representative example of the relationship between the inclination angle of the substrate,
• FIG. 12 shows the relationship between the substrate tilt and the birefringence difference when the force is reduced to less than 10%. Assuming that the birefringence difference is y and the substrate angle is X, the following should be satisfied.
• the present inventor created a phase pit substrate in the same manner as described above.
• the optical depth of the phase pit was also set to 0.095 ⁇ (actual depth of 40 nm).
• Panlite ST-30000 polycarbonate was used as the material of the phase pit substrate.
• the phase pit substrate was made by injection molding.
• the annealing temperature of the substrate was finely changed.
• the anneal time was set at 30 minutes. As is evident from Fig. 13, when the anneal temperature is set to 90 ° C or higher, a birefringence difference of 37 nm or less is secured, and the jitter is suppressed to 10% or less.
• the annealing temperature is set to 100 ° C or more, the jitter is suppressed to 8% or less.
• the annealing temperature is preferably set in the range of 90 ° C. to 130 ° C.
• the inventor prepared a phase pit substrate in the same manner as described above.
• Polycarbonate of Panlite ST-30000 was used as a material for the phase pit substrate.
• Anil Wen The temperature was set at 130 ° C.
• the optical depth of the phase pit was changed.
• the optical depth of the phase pit is set to 0.141 or less, the RAM jitter is suppressed to 15% or less.
• the optical depth of the phase pit is less than 0.06 ⁇ , stable tracking cannot be ensured. As a result, normal recording and reproduction cannot be realized. Therefore, the optical depth of the phase pit must be maintained at 0.06 ⁇ or more.
• the optical depth of the phase pit is set in the range of 0.06 ⁇ to 0.14 ⁇ , jitter of 15% or less and stable tracking can be realized. Further, when the optical depth of the phase pit is set in the range of 0.065 ⁇ to 0.118 ⁇ , both the ROM jitter and the RAM jitter are suppressed to 10% or less. When the optical depth of the phase pit is set in the range of 0.073 in to 0.105 ⁇ , both ROM and RAM are suppressed to 8% or less.
• the change in the optical depth of the phase pits was realized by the conditions for forming the stamper used in the fabrication of the phase pit substrate and the deep UV irradiation applied to the substrate after the fabrication.
• the inventor prepared a phase pit substrate in the same manner as described above.
• the phase pit substrate was made of Panlite ST-3000 poly-polypropylene.
• the phase pit substrate was formed by injection molding.
• the optical depth of the different phase pits was set for each individual phase pit substrate.
• the phase pit substrate was annealed at 130 ° C for 30 minutes.
• a magneto-optical disk was produced from the phase pit substrate as described above.
• the modulation degree and the jitter were measured on the created magneto-optical disk.
• the created magneto-optical disks were sequentially sent to a tester.
• the ROM signal of the phase pit was reproduced based on the tracking service of the phase pit.
• the wavelength of the laser beam was set at 65 Onm.
• the numerical aperture NA was set to 0.55.
• the linear velocity was set to 4.8 [m / s].
• predetermined data was recorded by magnetic field modulation recording on the recording magnetic film by FM modulation of the shortest mark 0.832111.
• the phase pit ROM was recorded with the shortest mark 0.832 of EFM modulation.
• the R ⁇ M jitter and the RAM jitter on ROM due to the phase pit sequence were measured.
• the read power of the ROM and RAM lasers was set to 1.5 [mW] during the measurement.
• DC emission of laser power Pw 8.0 [mW] is used during magnetic field modulation recording I was.
• the polarization direction of the laser beam during reproduction was set perpendicular to the track direction.
• the degree of modulation the light intensity of the laser beam reflected from the magneto-optical disk was measured. As described later, the light intensity of the laser beam is detected by a two-segment photodetector for each polarization plane orthogonal to each other. The electric signals output from the photodetector are added by an addition amplifier. Thus, the intensity of the entire laser beam is detected. The added electric signal is input to the oscilloscope. As shown in Fig. 15, when the laser beam is irradiated on the phase pit, the reflection level decreases. On the other hand, the reflection level increases when the laser beam is applied to the space without phase pits. Such a difference in the reflection level corresponds to the ROM signal intensity from the phase pit.
• the degree of modulation is represented by the ratio of the space reflection level La to the ROM signal intensity Lb. Specifically, the modulation factor M is calculated according to the following equation.
• the ROM jitter decreases as the modulation depth increases and the RAM jitter increases on the contrary. If the modulation degree of the phase pit is set to 55% or less, both the ROM jitter and the RAM jitter can be suppressed to 15% or less. However, when the optical depth of the phase pit is reduced and the modulation depth is less than 8%, a stable
• the birefringence difference is set to be equal to or less than the aforementioned value
• the phase When the optical depth and modulation depth of the pit are adjusted, ROM and RAM In both cases, good zipper can be realized at a practical level. If this birefringence difference deviates from the range described above, practically acceptable levels of ROM and RAM will not be secured even if the optical depth of the phase pit is changed or the modulation is adjusted. Can not.
• the magneto-optical disk drive 31 is used for recording and reproducing on the magneto-optical disk 11 as described above.
• the magneto-optical disk drive 31 includes a spindle 32 for supporting the magneto-optical disk 11 as shown in FIG. 17, for example.
• the spindle 32 can rotate the magneto-optical disk 11 around the central axis.
• the magneto-optical disk drive 31 has a light source, that is, a semiconductor laser diode 33.
• the semiconductor laser diode 33 outputs a linearly polarized light beam, that is, a laser beam 34.
• the so-called optical system 35 guides the laser beam 34 to the magneto-optical disk 11.
• the optical system 35 includes, for example, an objective lens 36 facing the surface of the magneto-optical disk 11.
• a beam splitter 37 is arranged between the semiconductor laser diode 33 and the objective lens 36.
• the laser beam 34 of the semiconductor laser diode 33 passes through the beam splitter 37.
• the laser beam 34 is irradiated on the magneto-optical disk 11 from the objective lens 36.
• the objective lens 36 forms a minute beam spot on the surface of the magneto-optical disk 11.
• the laser beam 34 passes through the substrate 12, the undercoat film 14, the recording magnetic film 15, the auxiliary magnetic film 16, and the overcoat film 17, and then reaches the reflection film 18.
• the laser beam 34 is reflected by the reflection film 18.
• the laser beam 34 is guided again from the objective lens 36 to the beam splitter 37.
• the two beam wollaston 38 faces the beam splitter 37.
• the laser beam 34 returned from the magneto-optical disk 11 is reflected by the beam splitter 37.
• the laser beam 34 is directed from the beam splitter 37 to a two-beam Wollaston 38.
• the two-beam Wollaston 38 decomposes the laser beam 34 with polarization planes orthogonal to each other.
• a two-segment photodetector 41 is arranged.
• Two-beam Wollaston 3 The laser beam decomposed by 3 8 3 2 Detected by the split photodetector 41.
• the laser beam 34 is converted into an electric signal for each polarization plane.
• the two electric signals are added by a summing amplifier 42.
• the intensity of the entire laser beam 34 is detected.
• the ROM information is decoded based on the output of the summing amplifier 42.
• the two electric signals are subtracted by the subtraction amplifier 43.
• the rotation of the plane of polarization is detected between the laser beam 34 reflected from the magneto-optical disk 11 and the laser beam 34 before reflection.
• the RAM information is decoded based on the output of the subtraction amplifier 43.
• a magnetic head slider 44 is opposed to the objective lens 36.
• An electromagnetic transducer is mounted on the magnetic head slider 4.
• Such an electromagnetic transducer may be arranged on an extension of the path of the laser beam 34 from the objective lens 36 to the magneto-optical disk 11.
• the temperature of the recording magnetic film 15 increases.
• a write magnetic field acts on the recording magnetic film 15 from the electromagnetic transducer.
• the magnetization of the recording magnetic film 15 can be relatively easily aligned in accordance with the direction of the write magnetic field.
• the RAM information is written to the recording magnetic film 15.
• so-called optical modulation recording may be used instead of such magnetic modulation recording.
• the magneto-optical disk 46 has a polarization plane 46 perpendicular to a recording track 45 composed of a series of phase pits on the magneto-optical disk 11.
• the disk 11 is irradiated with a laser beam 34.
• the laser beam 34 irradiates the phase pits 13 and the recording magnetic film 15 with so-called vertical polarization.
• the vertically polarized laser beam 3.4 can greatly contribute to the reduction of jitter when reading the ROM information and RAM information described above.
• the inventor prepared magneto-optical disks 11 according to six specific examples in the same manner as described above.
• the inventor measured the jitter for each specific example.
• Two types of laser beams were prepared for the measurement.
• One laser beam was applied to the magneto-optical disk 11 with vertical polarization, as in the magneto-optical disk drive 31 described above.
• the other laser beam was irradiated on the magneto-optical disk 11 with a plane of polarization parallel to the recording tracks on the magneto-optical disk 11. That is, the other laser beam was applied to the phase pit 13 and the recording magnetic film 15 with so-called horizontal polarization.

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• 2003
  • 2003-05-23 AU AU2003242421A patent/AU2003242421A1/en not_active Abandoned
  • 2003-05-23 WO PCT/JP2003/006452 patent/WO2004105014A1/ja active Application Filing
  • 2003-05-23 CN CN03825227.9A patent/CN1701367A/zh active Pending
  • 2003-05-23 JP JP2004572120A patent/JP4235182B2/ja not_active Expired - Fee Related

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