WO2014207911A1 - Support de stockage optique, dispositif d'enregistrement d'informations et procédé d'enregistrement d'informations - Google Patents

Support de stockage optique, dispositif d'enregistrement d'informations et procédé d'enregistrement d'informations Download PDF

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Publication number
WO2014207911A1
WO2014207911A1 PCT/JP2013/067856 JP2013067856W WO2014207911A1 WO 2014207911 A1 WO2014207911 A1 WO 2014207911A1 JP 2013067856 W JP2013067856 W JP 2013067856W WO 2014207911 A1 WO2014207911 A1 WO 2014207911A1
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Prior art keywords
layer
recording
thickness
guide
light
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PCT/JP2013/067856
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English (en)
Japanese (ja)
Inventor
渡部　一雄
岡野　英明
小川　昭人
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株式会社 東芝
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Priority to PCT/JP2013/067856 priority Critical patent/WO2014207911A1/fr
Publication of WO2014207911A1 publication Critical patent/WO2014207911A1/fr

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    • 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
    • G11B7/2403—Layers; Shape, structure or physical properties thereof
    • G11B7/24067—Combinations of two or more layers with specific interrelation

Definitions

  • Embodiments described herein relate generally to an optical storage medium, an information recording apparatus, and an information recording method.
  • interlayer crosstalk occurs during information reproduction of a multilayer optical disc having a plurality of recording layers.
  • a technique for reducing the occurrence of crosstalk of light rays (usually blue light) for reproducing information on a recording layer has been proposed.
  • a multilayer optical disc having a servo (dedicated) layer separately from the recording layer is known, and there is a demand to reduce the occurrence of crosstalk of servo dedicated light (usually red light) that reproduces information on the servo layer.
  • the servo signal is a signal that is the basis of information recording / reproduction, and it is required to have the same high reliability as the information reproduction signal not only in information recording but also in information reproduction.
  • the prior art documents do not mention interlayer crosstalk generated in the optical path of servo-dedicated light, and it is difficult to reduce interlayer crosstalk generated in the optical path of servo-dedicated light. Therefore, there is a possibility that sufficient performance as a multilayer optical disk cannot be exhibited.
  • the optical storage medium of the embodiment includes a cover layer, a recording layer group including a plurality of recording layers and a plurality of intermediate layers arranged between the plurality of recording layers.
  • the sum S1 of the thickness C1 of the cover layer and the layer thickness C2 between the first recording layer closest to the cover layer and the reflective recording layer where the laser beam that has passed through the cover layer is first reflected However, it does not coincide with the sum S2 of the thicknesses of one or more intermediate layers between the reflective recording layer and the target recording layer.
  • FIG. 1 is a diagram illustrating an example of an optical storage medium according to an embodiment.
  • the figure which shows an example of a structure of the information recording / reproducing apparatus of embodiment. 1 is a diagram illustrating an example of a configuration of an optical pickup according to an embodiment.
  • production The figure explaining an example of the 2nd conditions of guide light confocal crosstalk generation
  • the figure which shows an example of a mode that the confocal crosstalk was reduced.
  • the figure which shows an example of a mode that the confocal crosstalk of guide light was reduced.
  • FIG. 1 is a diagram illustrating a cross-sectional structure of an optical storage medium according to an embodiment.
  • the optical storage medium is an optical disc 10 having a plurality of recording / reproducing layers, and information is recorded on a recording film in the optical disc 10 by a laser beam emitted from an optical pickup (OPU) described later.
  • OPU optical pickup
  • the upper surface shape is, for example, a circle having a diameter of 120 mm.
  • the effect of the optical storage medium of the present embodiment does not depend on the shape of the upper surface, and may be, for example, an ellipse, a polygon, or a shape obtained by connecting them.
  • the optical disc 10 has a structure in which a guide layer 20 and a recording layer 21 (including recording layers 21A to 21L) in which guide grooves or pit rows for generating servo signals during recording and reproduction are formed are formed on a substrate 11. It has become.
  • the recording layer 21 is also referred to as a recording layer group, and the recording layer group includes 12 recording layers 21A to 21L and 11 intermediate layers 31A to 31K.
  • the recording layers 21A to 21L and the intermediate layers 31A to 31K are alternately arranged.
  • the guide layer 20 and the recording layer 21 are formed in the order of the guide layer 20 and the recording layer 21 from the substrate 11 side, and recording / reproducing laser beams 15 and 16 from the optical pickup enter from the opposite side of the substrate 11.
  • a cover layer 12 is formed on the side of the recording layer 21 opposite to the substrate 11.
  • the guide groove or pit row on the guide layer 20 has, for example, a helical structure with a depth of 60 nm and a track pitch of 0.64 ⁇ m, and the ratio of the concave and convex portions in the cross section is approximately 1: 1.
  • the groove depth (pit depth) and the track pitch are not limited to this, and may be a deep groove (deep pit) with a depth of about 100 nm or a shallow groove (shallow pit) with a thickness of about 20 nm, about 0.32 ⁇ m.
  • a narrow track pitch of about 0.74 ⁇ m, or a wide track pitch of about 1.2 ⁇ m may be used.
  • the track structure may be a concentric structure, a spiral structure, or a so-called single spiral structure in which the concave and convex portions are switched every round.
  • address information is applied to the guide groove by, for example, wobble.
  • the wobble is meandering in a direction perpendicular to the track extending direction of the guide groove in the surface of the optical disc 10.
  • An intermediate layer 30 having optical transparency is formed between the guide layer 20 and the recording layer 21A closest to the guide layer 20.
  • intermediate layers 31A to 31K having optical transparency are also formed between two adjacent recording layers of the recording layer 21. The thicknesses of the intermediate layer 30 and the intermediate layer 31 (including the intermediate layers 31A to 31K) will be described later.
  • the cover layer 12 is light transmissive and has a thickness of, for example, 53 ⁇ m.
  • the cover layer is not particularly limited as long as it is a transparent material, but synthetic resins such as polycarbonate and PMMA, glass, and the like can be used.
  • the recording layer 21 is a layer for recording information, and a change corresponding to the laser beam emitted from the optical pickup is generated, and a mark corresponding to the information is recorded.
  • a phase change recording film composed of a multilayer film containing a phase change material, a write-once recording film composed of an organic dye, and the like.
  • the thickness of one recording layer 21 is usually 0.2 ⁇ m or less, and the thickness of the recording layer 21 is very small with respect to the thickness of the cover layer and the intermediate layer.
  • the guide layer 20 and the recording layer 31 are irradiated with laser beams 15 and 16, respectively.
  • the laser beams 15 and 16 have different wavelengths for easy optical path separation in the optical pickup.
  • the laser beam 15 is a red laser beam and the laser beam 16 is a blue-violet laser beam.
  • FIG. 2 shows the configuration of the information recording / reproducing apparatus 300 according to the first embodiment.
  • Information recording / reproducing apparatus 300 includes interface (IF) 310, signal processing unit (DSP) 320, laser driver (LDD1) 330, (LDD2) 340, optical pickup head unit (OPU) 200, RF amplifier IC (RFRFAMP) 350 , A servo controller 360 and a spindle motor 60, and the multilayer optical disk 10 is set on the spindle motor 60.
  • IF interface
  • DSP signal processing unit
  • LDD1 laser driver
  • OPU optical pickup head unit
  • RFRFAMP RF amplifier IC
  • the interface 310 is a connection part for exchanging commands and data with an external host (not shown), and corresponds to a specific standard (for example, SATA).
  • the signal processing unit 320 transmits / receives commands and data to / from an external host via the interface 310, converts data, transmits data pulses and control signals to the laser driver, transmits control signals to the servo controller 360, RF amplifier IC 350 responsible for receiving data signals from
  • Laser drivers 330 and 340 receive data pulses from the signal processing unit 320, control signals, convert them into drive pulses, and transmit drive pulses to the optical pickup head unit 200.
  • the optical pickup head unit 200 irradiates the guide layer 20 and the recording layer 21 of the multilayer optical disc 10 with the laser beams 15 and 16 in response to the drive pulses from the laser drivers 330 and 340, receives the reflected light, and receives the reflected light.
  • a signal corresponding to the change in strength is transmitted to the RF amplifier IC 350.
  • the RF amplifier IC 350 amplifies the signal from the optical pickup head unit 200, generates a servo signal and a data signal, and transmits them to the servo controller 360 and the signal processing unit 320, respectively.
  • the servo controller 360 receives the servo signal from the RF amplifier IC 350, converts the servo signal into an actuator drive signal and a spindle motor drive signal, transmits the actuator drive signal to the optical pickup head unit 200, and drives the spindle motor 60. Transmit the signal.
  • the spindle motor 60 receives the spindle motor drive signal from the servo controller 360, and rotates the mounted optical disc 10 about an axis perpendicular to the extending direction.
  • FIG. 3 shows an example of a detailed configuration of the optical pickup head unit 200 of the information recording / reproducing apparatus 300 according to the embodiment.
  • the optical pickup head unit (OPU) 200 consists of a blue-violet laser (Blue LD), a red laser (Red LD), a polarizing beam splitter (PBS) 1 and 2, a quarter-wave plate (QWP) 1 and 2, a collimating lens (CL) 1, 2, objective lens (OL), hologram element (HOE), blue-violet detector IC (Blue PDIC), red detector IC (Red PDIC), diffraction element (GT), dichroic prism (DP), collimating lens actuator (CL-ACT), and objective lens actuator (OL-ACT).
  • Blue LD blue-violet laser
  • Red LD red laser
  • PBS polarizing beam splitter
  • QWP quarter-wave plate
  • the blue-violet laser is a semiconductor laser having a wavelength of 405 nm, for example, and emits laser light for recording and reproduction.
  • the blue-violet laser is connected to the laser driver 1 of the information recording / reproducing apparatus 300 in FIG.
  • PBS 1 transmits the incident light from the blue-violet laser and reflects the reflected light from the optical disk 10 of the blue-violet laser in which the incident light and the 90-degree polarization plane are rotated.
  • QWP1 transmits incident light from a blue-violet laser and converts linearly polarized light into circularly polarized light. Further, the reflected light from the optical disk 10 of the blue-violet laser is transmitted, and the circularly polarized light is converted into linearly polarized light. At this time, the incident light and the 90-degree polarization plane are linearly polarized light different from each other. For example, if the incident light is P-polarized light, the reflected light is S-polarized light.
  • the collimating lens 1 converts incident light from the blue-violet laser 1 into substantially parallel light.
  • the objective lens focuses the light emitted from the blue-violet laser on the recording layer 21 of the optical disc 10.
  • the objective lens has a wavelength selective aperture on the laser light source side so that the red laser beam 15 and the blue-violet laser beam 16 have different numerical apertures. For example, for the blue-violet laser beam 16, 0.85 and 0.65 for the red laser beam 15.
  • the dichroic prism transmits incident light from the blue-violet laser and reflects incident light from the red laser.
  • the red laser is a semiconductor laser having a wavelength of 655 nm, for example, and emits a tracking servo laser beam.
  • the red laser is connected to the laser driver 2 of the information recording / reproducing apparatus 300.
  • the diffraction element splits the red laser light into three beams by diffraction.
  • the three beams become one main beam and two sub beams on the optical disc 10.
  • PBS 2 transmits the incident light from the red laser and reflects the reflected light from the optical disk 10 of the red laser in which the incident light and the 90-degree polarization plane are rotated.
  • QWP2 transmits incident light from a red laser and converts linearly polarized light into circularly polarized light. Further, the reflected light from the optical disk 10 of the red laser is transmitted, and the circularly polarized light is converted into linearly polarized light. At this time, the incident light and the 90-degree polarization plane are linearly polarized light different from each other. For example, if the incident light is P-polarized light, the reflected light is S-polarized light.
  • the collimating lens 2 converts light emitted from the red laser into substantially parallel light.
  • the light beam emitted from the blue-violet laser 1 transmits the light beam reflected by the information recording layer of the optical disc 10, and diffracts a predetermined region of the light beam at a predetermined angle.
  • the blue-violet light detector IC receives the blue-violet laser light from the HOE, generates a current corresponding to the received light amount, converts the light into a voltage by an internal current-voltage conversion circuit, and outputs the voltage.
  • the red light detector IC receives the red laser light reflected by the PBS 2, generates a current corresponding to the received light amount, converts it into a voltage by an internal current-voltage conversion circuit, and outputs the voltage.
  • the collimating lens actuator drives the collimating lens 2 in the vertical direction in the drawing so that the red laser light emitted from the objective lens moves on the optical disk 10 in the optical axis direction (focus direction).
  • the objective lens actuator drives the objective lens in the left-right direction in the drawing so that the laser light emitted from the objective lens moves on the optical disc 10 along the optical axis (focus direction). Further, the laser beam emitted from the objective lens is driven in a direction perpendicular to the paper surface so that the laser beam moves in the vertical direction (radial direction) of the recording track on the optical disk 10.
  • a user data recording command and data to be recorded are sent from a host (not shown) and sent to the signal processing unit 320 via the interface 310.
  • the signal processing unit 320 starts the data recording process according to the received recording command.
  • the signal processing unit 320 transmits a drive signal to the laser driver 1 and the laser driver 2 to turn on the blue-violet laser and the red laser with the reproduction power.
  • the servo controller 360 transmits a rotation drive signal to the spindle motor 60 to drive the optical disk 10 to rotate at a predetermined rotation speed.
  • the signal processing unit 320 transmits a focus search control signal to the servo controller 360.
  • the servo controller 360 drives the collimating lens actuator with a single vibration in the focus direction in accordance with the transmitted control signal.
  • the focal point of the red laser light 15 emitted from the objective lens through the collimating lens driven by a single vibration reciprocates up and down repeatedly with the guide layer 20 of the optical disc 10 interposed therebetween.
  • the reflected light of the red laser light 15 on the guide layer 20 is condensed on the red photodetector IC.
  • the red photodetector IC converts a current based on the amount of reflected light into a voltage and sends it to the RF amplifier IC 350.
  • the RF amplifier IC 350 generates a focus error signal of the red laser light by a predetermined calculation from the received voltage signal, and sends it to the servo controller 360.
  • the focus error signal is generated by, for example, a known astigmatism method using an astigmatism generation optical element (not shown).
  • the servo controller 360 switches the drive of the collimating lens actuator from the single vibration drive to the drive based on the focus error signal near the focus error signal becomes zero, and draws the focus of the red laser light into the guide groove layer. Subsequently, the servo controller 360 draws the focus of the blue-violet laser beam 16 into the target recording layer 21 on the optical disc 10. At this time, the blue-violet laser beam 16 is focused on the recording layer by driving the objective lens actuator based on the focus error signal generated by the RF amplifier IC based on the voltage signal transmitted from the blue-violet photodetector IC.
  • the servo controller 360 pulls the red laser light 15 into a track formed by a guide groove or the like on the guide layer 20 of the optical disc 10. At this time, the servo controller 360 drives the objective lens actuator based on the tracking error signal generated by the RF amplifier IC based on the voltage signal sent from the red light detector IC and pulls it into the track on the guide layer.
  • the tracking error signal is generated by a known differential push-pull method, for example.
  • the signal processing unit 320 reads the data signal generated by the RF amplifier IC based on the voltage signal transmitted from the red photodetector IC, and reproduces the current address.
  • the signal processing unit 320 sends a track jump control signal for the track corresponding to the difference between the current address and the target address to the servo controller 360.
  • the servo controller 360 transmits a drive pulse to the objective lens actuator based on the track jump control signal, and moves the red laser light 15 to a desired track. At this time, the blue-violet laser light 16 irradiated through the same objective lens also performs track movement.
  • the signal processing unit 320 transmits the recording data series to the laser driver 1.
  • the laser driver 1 generates a drive pulse corresponding to the received recording data series, sends it to a blue-violet laser, and performs pulse drive.
  • the pulse emitted by the blue-violet laser passes through the objective lens and is applied to the recording layer 21 of the optical disc 10 to form a recording mark corresponding to the recording data series.
  • the information recording / reproducing apparatus of this embodiment records the recording target data on the target recording layer 21 of the optical disc 10.
  • a user data reproduction command is sent from a host (not shown) and sent to the signal processing unit 320 via the interface 310.
  • the signal processing unit 320 starts the data reproduction process according to the received reproduction command.
  • the signal processing unit 320 transmits a drive signal to the laser driver 1 and the laser driver 2 to turn on the blue-violet laser and the red laser with the reproduction power.
  • the signal processing unit 320 transmits a focus search control signal to the servo controller 360.
  • the servo controller 360 drives the collimating lens actuator with a single vibration in the focus direction in accordance with the transmitted control signal.
  • the focal point of the red laser light 15 emitted from the objective lens through the collimating lens driven by a single vibration repeatedly reciprocates up and down across the guide layer 20 of the optical disc 10.
  • the reflected light of the red laser light 15 on the guide layer is condensed on the red photodetector IC.
  • the red photodetector IC converts a current based on the amount of reflected light into a voltage and sends it to the RF amplifier IC 350.
  • the RF amplifier IC 350 generates a focus error signal of the red laser light by a predetermined calculation from the received voltage signal, and sends it to the servo controller 360.
  • the servo controller 360 switches the drive of the collimating lens actuator from the single vibration drive to the drive based on the focus error signal near the focus error signal becomes zero, and pulls the focus of the red laser light into the guide layer.
  • the servo controller 360 draws the focus of the blue-violet laser beam 16 into the target recording layer 21 on the optical disc 10.
  • the blue-violet laser beam 16 is focused on the recording layer by driving the objective lens actuator based on the focus error signal generated by the RF amplifier IC based on the voltage signal transmitted from the blue-violet photodetector IC. Pull the desired recording layer out of 21.
  • the servo controller 360 pulls the red laser light 15 into the track of the guide layer 20.
  • the servo controller 360 drives the objective lens actuator based on the tracking error signal generated by the RF amplifier IC based on the voltage signal sent from the red light detector IC and pulls it into the track of the guide layer 20.
  • the signal processing unit 320 reads the data signal generated by the RF amplifier IC based on the voltage signal transmitted from the red photodetector IC, and reproduces the current address. If the target address is different, the signal processing unit 320 sends a track jump control signal for the track corresponding to the difference between the current address and the target address to the servo controller 360.
  • the servo controller 360 transmits a drive pulse to the objective lens actuator based on the track jump control signal, and moves the red laser light 15 to a desired track. At this time, the blue-violet laser light 16 irradiated through the same objective lens also performs track movement.
  • the blue-violet photodetector IC converts a current based on the amount of reflected light reflected by the recording layer 21 of the optical disk 10 into the blue-violet laser light 16 into a voltage, and sends the voltage to the RF amplifier IC 350.
  • the RF amplifier IC 350 generates a tracking error signal of the blue-violet laser light 16 by a predetermined calculation from the received voltage signal, and sends it to the servo controller 360.
  • the tracking error signal in this case is, for example, a DPD (Differential Pase Deciton) signal or a push-pull signal generated from a recorded mark string of the recording layer 21.
  • the signal processing unit 320 transmits a disconnection control signal from the guide layer servo to the servo controller 360 after determining that the track near the target address has been reached.
  • the servo controller 360 switches the driving of the objective lens actuator from driving based on the tracking error signal of the red laser beam 15 to driving based on the tracking error signal of the blue purple laser beam 16, and records the blue-violet laser beam 16. Pull into the recorded track of layer 21.
  • the signal processing unit 320 reads the data signal generated by the RF amplifier IC based on the voltage signal transmitted from the blue-violet photodetector IC, and the current of the recording layer 21 into which the blue-violet laser light 16 has been drawn. Play the address.
  • the signal processing unit 320 sends a track jump control signal for the track corresponding to the difference between the current address and the target address to the servo controller 360.
  • the servo controller 360 transmits a drive pulse to the objective lens actuator based on the track jump control signal, and moves the blue-violet laser light 16 to a desired track.
  • the signal processing unit 320 confirms that the target address has been reached, and starts data reproduction from the recording layer 21.
  • the information recording / reproducing apparatus of this embodiment can reproduce information from the recording layer.
  • the red laser beam 15 for reproducing information from the guide layer 20 and the blue-violet laser beam 16 for recording information on the recording layer 21 or reproducing information from the recording layer 21 each play a necessary role.
  • the recording / reproduction of the optical disk 10 is established.
  • Interlayer crosstalk is a phenomenon that causes problems in optical discs having a plurality of recording layers.
  • Interlayer crosstalk includes interlayer crosstalk caused by reflection of adjacent recording layers and confocal crosstalk (see the prior art). Interlayer crosstalk due to reflection of adjacent recording layers can be avoided by setting the thickness of the intermediate layer 31 to 10 ⁇ m or more as in the prior art, and the minimum value of the thickness of the intermediate layer 31 is 10 ⁇ m. In consideration of the error, the thickness design value of the intermediate layer 31 may be used.
  • the recording / reproducing blue-violet laser light 16 irradiated on the target recording layer (the recording layer 21C in the figure) of the recording layer 21 of the optical disc 10 is branched into a plurality of light beams due to the semi-transmission of the recording layer.
  • a part of the laser beam 16 is reflected by the recording layer 21G, becomes a branched beam 17 and is focused on the recording layer 21K, and this reflected light is reflected again by the recording layer 21G and is reflected by the laser beam 16, that is, the recording It merges with the recording / reproducing light of the layer 21C, and is detected simultaneously and spatially at substantially the same position by the blue photodetector IC.
  • This confocal crosstalk light is detected at the same wavelength as the recording / reproducing light and through almost the same optical path, so that the spatial and band separation means do not work effectively and are detected as powerful noise. It becomes.
  • the thickness of the intermediate layer 31 of the recording layer 21 is different from each other for reducing the confocal crosstalk of the recording / reproducing light (blue-violet laser light) in the recording layer.
  • the intermediate layer 31 may have a thickness in which the first and second intermediate layer thicknesses are alternately repeated.
  • the first intermediate layer thickness and the second intermediate layer thickness take a manufacturing margin into consideration, and the confocal crosstalk is reduced by providing a difference of 4 ⁇ m or more. Therefore, by setting the first intermediate layer thickness to 12 ⁇ m and the second intermediate layer thickness to 16 ⁇ m, it is possible to reduce confocal crosstalk and also reduce interlayer crosstalk due to reflection. . Further, the confocal crosstalk can be further reduced by setting the reflectance of all the recording layers 21 to 2% or less.
  • the countermeasure against the interlayer crosstalk of the guide light (red laser beam 15) is as important as the interlayer crosstalk of the recording / reproducing light.
  • FIG. 6 shows how the confocal crosstalk occurs in the guide light (red laser light 15).
  • the red laser light 15 for guide irradiated on the guide layer 20 of the optical disc 10 is branched into a plurality of light beams due to the semi-transparency of the recording layer.
  • a part of the laser beam 15 is reflected by the recording layer 21A, becomes a branched beam 40 and is focused by the recording layer 21F, and this reflected light is reflected again by the recording layer 21A and is reflected by the laser beam 15, that is, the guide It merges with the recording / reproducing light of the layer 20 and is detected simultaneously and spatially at substantially the same position by the red photodetector IC.
  • FIG. 7 shows another confocal crosstalk occurring in the guide light (red laser light 15).
  • the red laser light 15 for guide irradiated on the guide layer 20 of the optical disc 10 is branched into a plurality of light beams due to the semi-transparency of the recording layer. For example, a part of the laser beam 15 is reflected by the recording layer 21A, becomes a branched beam 42, and is reflected by the recording layer 21J.
  • the reflected light is reflected by the recording layer 21E and merges with the laser light 15, that is, the recording / reproducing light of the guide layer 20.
  • the crosstalk light is not focused on the recording layer 21 ⁇ / b> J.
  • the crosstalk light is substantially simultaneously and spatially reduced by the red photodetector IC. It will be detected at the same position. Therefore, in the present embodiment, this is also considered as a kind of confocal crosstalk.
  • the reflectance of the recording layer 21 is adjusted in accordance with the blue-violet wavelength band that is recording / reproducing light, the reflectance in the red wavelength band that is the guide light cannot be preferentially adjusted. Conversely, if priority is given to adjusting the reflectance in the red wavelength band so that confocal crosstalk does not occur, the material selection range and film thickness adjustment range of the recording layer will be extremely limited. As a result, the productivity of the optical disk 10 is extremely deteriorated and the cost is increased. Therefore, in order to reduce the confocal crosstalk of the guide light, it is desirable to take an approach independent of the confocal crosstalk (FIG. 5) in the recording layer of the recording / reproducing light. Therefore, in this embodiment, the confocal crosstalk of the guide light is reduced by suitably creating the thickness of the intermediate layer 30 between the guide layer 20 and the recording layer 21A and the intermediate layer 31 in the recording layer 21; did.
  • FIG. 8 is a diagram illustrating an example of a state in which the confocal crosstalk of the guide light is reduced.
  • a part of the guide red laser light 15 irradiated to the guide layer 20 of the optical disc 10 is reflected by the recording layer 21A, and becomes a branched beam 41 and reflected by the recording layer 21F.
  • the branched beam 41 does not have to be focused on the recording layer 21F, and even if this reflected light is reflected again by the recording layer 21A,
  • the laser beam 15, that is, the recording / reproducing light of the guide layer 20 does not merge in the same optical path, but is detected at a position that does not spatially coincide with the red photodetector IC. For this reason, the crosstalk light can be spatially separated from the guide light 15, and noise can be reduced.
  • an intermediate layer thickness configuration capable of reducing the confocal crosstalk of the guide light will be described.
  • an intermediate layer thickness configuration capable of reducing the confocal crosstalk of the guide light it is necessary to clarify the intermediate layer thickness condition in which the confocal crosstalk is generated, and to integrate the front and back. Therefore, conditions for generating confocal crosstalk of the guide light will be described below.
  • FIG. 9 shows how the confocal crosstalk occurs when the guide light is satisfied.
  • the thickness (SL0) of the intermediate layer 30 between the guide layer and the recording layer closest to the guide layer is the thickness of the intermediate layer 31H to the intermediate layer 31J between the recording layer 21H and the recording layer 21K. It is consistent with the sum. Therefore, the line segment AD and the line segment BC in FIG. 9 have the same length. At this time, the quadrangle ABCD in FIG.
  • the branched beam passing through the optical path IABCO merges with the guide light (optical path IADCO) to become confocal crosstalk light. If the thickness of the intermediate layer 30 matches the sum of the thicknesses of any successive intermediate layers including the intermediate layer 31A, the branched beam is a type of confocal crosstalk light that is focused on the recording layer. Become.
  • FIG. 10 shows how the confocal crosstalk occurs in the guide light when this condition is satisfied. In FIG. 10, the sum SL0 + SL1 of the thickness (SL0) of the intermediate layer 30 between the guide layer and the recording layer 21A closest to the guide layer and the thickness of the intermediate layer 31A between the recording layer 21A and the recording layer 21B.
  • the line segment A′D ′ and the line segment B′C ′ in FIG. 10 have the same length.
  • the quadrangle A′B′C′D ′ in FIG. 10 becomes a parallelogram, and the branched beam passing through the optical path IA′B′C′O merges with the guide light (optical path IA′D′C′O). It becomes confocal crosstalk light.
  • the branched beam is of a type that focuses on the recording layer. Confocal crosstalk light.
  • the branched beam is focused on the recording layer. Type of confocal crosstalk light.
  • the intermediate layer thickness configuration that can reduce the confocal crosstalk of the guide light means an intermediate layer thickness configuration that does not satisfy the first condition and the second condition at the same time or one of them.
  • the intermediate layer 31 of the recording layer 21 may have a structure in which the first and second intermediate layer thicknesses are alternately repeated in order to reduce the interlayer crosstalk of the recording / reproducing light (blue-violet laser light 16).
  • the optical disc 10 has a structure that can reduce the interlayer crosstalk of the guide light (red laser beam 15) and the interlayer crosstalk of the recording / reproducing light (blue-violet laser beam 16) at the same time. Is possible. Accordingly, it is preferable to apply the intermediate layer thickness configuration capable of reducing the confocal crosstalk of the guide light to a structure in which the first and second intermediate layer thicknesses are alternately repeated.
  • the conditions of the intermediate layer thickness configuration capable of reducing the confocal crosstalk of the guide light while reducing the interlayer crosstalk of the recording / reproducing light will be examined. It is assumed that the recording layer 21 has 12 layers. Generalizing the structure in which the first and second intermediate layer thicknesses are alternately repeated, the first intermediate layer thickness is expressed as m ( ⁇ m), and the second intermediate layer thickness is expressed as m + a ( ⁇ m). Can do. Here, the first intermediate layer thickness is assumed to be thinner than the second intermediate layer thickness. Note that the intermediate layer between the recording layer closest to the guide layer and the recording layer closest thereto is considered to have the first intermediate layer thickness.
  • the thickness of the intermediate layer 30 satisfying the first condition is as follows. However, the case where the thickness of the intermediate layer 30 is equal to or smaller than the second intermediate layer thickness is excluded because the interlayer crosstalk due to the reflection of the recording layer adjacent to the guide layer increases.
  • the thickness of the intermediate layer 30 that satisfies the second condition is as follows.
  • the thickness of the intermediate layer 30 that satisfies either the first condition or the second condition is as follows (intermediate layer thickness condition group 1).
  • the difference between the first intermediate layer thickness and the second intermediate layer thickness that is, a ( ⁇ m) is better from the viewpoint of reducing the interlayer crosstalk. If it is too large, the thickness of the entire recording layer 21 is increased, and the aberration becomes large as a characteristic of the objective lens of the optical pickup unit 200.
  • a needs to be smaller than m. That is, m> a.
  • the thickness of the intermediate layer 30 preferably satisfies neither the first condition nor the second condition from the viewpoint of avoiding confocal crosstalk.
  • the thickness of the intermediate layer 30 is preferably set to a thickness far from any value of the intermediate layer thickness condition group 1 described above. For this reason, for example, one method is to make the thickness of the intermediate layer 30 sufficiently larger than 11 m + 6a. In this case, the confocal crosstalk of the guide light does not occur, but the total thickness of the intermediate layer 30, the intermediate layer 31, and the cover layer becomes too large, and the aberration is large as a characteristic of the objective lens of the optical pickup unit 200. turn into.
  • the first condition is 2m + a, 3m + a, 3m + 2a, 4m + 2a, 5m + 2a, 5m + 3a, 6m + 3a, 7m + 3a, 7m + 4a, 8m + 4a, 9m
  • the thickness of the intermediate layer 30 can be set to an intermediate value or a value close to the intermediate value among + 4a, 9m + 5a, 10m + 5a, 11m + 5a, and 11m + 6a.
  • the intermediate value between 2m + a and 3m + a is 2.5m + a.
  • the thickness of the intermediate layer 30 is preferably set to an intermediate value in the intermediate layer thickness condition group 1 or a value close to the intermediate value.
  • the interval of the continuous values in the intermediate layer thickness condition group 1 is any one of m, a, and m-a. When m> a is considered, the interval is the longest when the interval is m. That is, between 3m + 2a and 4m + 2a, 5m + 3a and 6m + 3a, 7m + 4a and 8m + 4a, and 9m + 5a and 10m + 5a.
  • the thickness of the intermediate layer 30 is a guide when formed as an intermediate value of these, 3.5 m + 2a, 5.5 m + 3a, 7.5 m + 4a, 9.5 m + 5a Interlayer crosstalk of recording / reproducing light can be reduced while reducing confocal crosstalk of light.
  • the optical disk 10 is a highly reliable optical disk in which the interlayer crosstalk of the guide light (red laser light 15) and the recording / reproducing light (blue-violet laser light 16) is reduced, and the defective product rate at the time of manufacturing the disk is low.
  • the intermediate layer 30 is preferably thin from the viewpoint of aberration of the objective lens of the optical pickup unit 200, it is preferably 57 ⁇ m or 89 ⁇ m among the above.
  • the first intermediate layer thickness may be larger than the second intermediate layer thickness.
  • the first intermediate layer thickness can be expressed as m + a ( ⁇ m)
  • the second intermediate layer thickness can be expressed as m ( ⁇ m).
  • the thickness of the intermediate layer 30 that satisfies the second condition is as follows.
  • the thickness of the intermediate layer 30 that satisfies either the first condition or the second condition is as follows (intermediate layer thickness condition group 2).
  • the first condition is 2m + a, 3m + a, 3m + 2a, 4m + 2a, 5m + 2a, 5m + 3a, 6m + 3a, 7m + 3a, 7m + 4a, 8m + 4a, 9m
  • the thickness of the intermediate layer 30 can be set to an intermediate value or a value close to the intermediate value among + 4a, 9m + 5a, 10m + 5a, 11m + 5a, and 11m + 6a.
  • the intermediate value between 2m + a and 3m + a is 2.5m + a.
  • the thickness of the intermediate layer 30 is preferably set to an intermediate value of the intermediate layer thickness condition group 2 or a value close to the intermediate value.
  • the interval between the continuous values of the intermediate layer thickness condition group 2 is any one of m, a, and ma. Considering m> a, the interval is the longest when the interval is m. That is, between 2m + a and 3m + a, 4m + 2a and 5m + 2a, 6m + 3a and 7m + 3a, and 8m + 4a and 9m + 4a.
  • the thickness of the intermediate layer 30 is a guide when it is formed as these intermediate values, 2.5m + a, 4.5m + 2a, 6.5m + 3a, 8.5m + 4a Interlayer crosstalk of recording / reproducing light can be reduced while reducing confocal crosstalk of light.
  • the optical disk 10 is a highly reliable optical disk in which the interlayer crosstalk of the guide light (red laser light 15) and the recording / reproducing light (blue-violet laser light 16) is reduced, and the defective product rate at the time of manufacturing the disk is low.
  • the intermediate layer 30 is preferably thin from the viewpoint of aberration of the objective lens of the optical pickup unit 200, it is preferably 39 ⁇ m or 71 ⁇ m among the above.
  • FIG. 11A, 11B, and 11C show the disk structure when the first intermediate layer is thinner than the second intermediate layer.
  • the thickness of the intermediate layer 30 is 57 ⁇ m or 89 ⁇ m so that the optical disk is highly reliable. Is obtained.
  • FIG. 11A shows an example of the structure of the optical disc 10 having 12 recording layers 21.
  • FIG. 11B and FIG. 11C are structural examples of the optical disc 10 provided with 8 and 6 recording layers 21, respectively.
  • the guide layer 20 is located 284 ⁇ m from the surface of the cover layer as in the case of the 12 layers.
  • An optical disk with high reliability can be obtained by setting the thickness of the intermediate layer 30 to 57 ⁇ m or 89 ⁇ m. However, in order to prevent the cover layer 12 from becoming extremely thick, the thickness is set to 89 ⁇ m. As a result, the distance of the recording layer 21A from the cover layer surface is 195 ⁇ m. As a result, the thickness of the cover layer 12 of the disc having eight recording layers is 85 ⁇ m (FIG. 11B), and the thickness of the cover layer 12 of the disc having six recording layers is 117 ⁇ m (FIG. 11C).
  • FIG. 12A, FIG. 12B, and FIG. 12C show examples of the disk structure when the first intermediate layer is thicker than the second intermediate layer.
  • the thickness of the intermediate layer 30 is 39 ⁇ m or 71 ⁇ m.
  • FIG. 12A is a structural example of the optical disc 10 having 12 recording layers 21.
  • the thickness of the cover layer 12 was 53 ⁇ m for the same reason as described above.
  • the distance from the cover layer surface of the guide layer 20 is 270 ⁇ m
  • the distance from the cover layer surface of the recording layer 21A is 231 ⁇ m.
  • the guide layer 20 is located 270 ⁇ m from the surface of the cover layer as in the example of 12 layers.
  • An optical disk with high reliability can be obtained by setting the thickness of the intermediate layer 30 to 39 ⁇ m or 71 ⁇ m.
  • the thickness is set to 71 ⁇ m.
  • the distance of the recording layer 21A from the cover layer surface is 199 ⁇ m.
  • the thickness of the cover layer 12 of the disc having 8 recording layers is 85 ⁇ m (FIG. 12B), and the thickness of the cover layer 12 of the disc having 6 recording layers is 117 ⁇ m (FIG. 12C).
  • Confocal crosstalk to be considered in this case includes (1) confocal crosstalk of recording / reproducing light (blue-violet laser light 16) and (2) confocal crosstalk of guide light (red laser light 15). .
  • the recording / reproducing blue-violet laser light 16 irradiated to the target recording layer (the recording layer 21F in the figure) of the recording layer 21 of the optical disc 10 is branched into a plurality of light beams due to the semi-transmission of the recording layer.
  • a part of the laser light 16 is reflected by the recording layer 21L, becomes a branched beam 51 and is focused from the inside of the cover layer on the surface of the cover layer 12, and this reflected light is reflected again by the recording layer 21L.
  • the laser light 16 that is, the recording / reproducing light of the recording layer 21F is merged and detected simultaneously and spatially at substantially the same position by the blue photodetector IC.
  • This confocal crosstalk light is detected at the same wavelength as the recording / reproducing light and through almost the same optical path, so that the spatial and band separation means do not work effectively and are detected as powerful noise. It becomes.
  • the cover layer 12 is too thick, the tilt margin at the time of recording / reproducing of the recording layer is lowered. If the cover layer 12 is too thin, there is a problem that the recording layer 21L closest to the cover layer is not sufficiently protected. It is relatively gentle, and the confocal crosstalk of the recording / reproducing light can be reduced by making the thickness of the cover layer 12 more preferable in detail.
  • FIG. 16 is a diagram showing an example of a state in which confocal crosstalk of recording / reproducing light is reduced.
  • the recording / reproducing blue-violet laser light 16 irradiated on the target recording layer (in the figure, the recording layer 21F) is partially reflected by the recording layer 21L, and the branched beam 52 and
  • the surface of the cover layer 12 is reflected from the inside.
  • the cover layer 12 since the cover layer 12 is suitably formed, the branched beam 52 does not have to be focused on the surface of the cover layer 12, and even if this reflected light is reflected again by the recording layer 21L, it is bluish purple.
  • the laser beam 16 that is, the recording / reproducing light of the recording layer 21, does not merge in the same optical path, but is detected at a position not spatially matched by the blue-violet photodetector IC. Therefore, the crosstalk light can be spatially separated from the recording / reproducing light 16, and noise can be reduced.
  • the cover layer thickness configuration capable of reducing the confocal crosstalk of the recording / reproducing light will be described.
  • the intermediate layer thickness configuration capable of reducing the confocal crosstalk of the recording / reproducing light it is necessary to clarify the cover layer thickness condition in which the confocal crosstalk is generated and to be integrated. Therefore, conditions for generating confocal crosstalk of recording / reproducing light will be described below.
  • the first reflective recording layer is a recording layer in which recording / reproducing light is first branched and reflected among the recording layers, and in the example of FIG. 15, is the recording layer 21L.
  • FIG. 17 shows the occurrence of confocal crosstalk of the recording / reproducing light when this condition is satisfied.
  • the sum of the thicknesses coincides with the sum of the thicknesses of the intermediate layers (intermediate layer 31C to intermediate layer 31I) between the first reflective recording layer (recording layer 21J) and the target recording layer (recording layer 21C).
  • the line segment AD and the line segment BC in FIG. 17 have the same length.
  • the quadrangle ABCD in FIG. 17 becomes a parallelogram, and the branched beam passing through the optical path IABCO merges with the recording / reproducing light (optical path IADCO) to become confocal crosstalk light.
  • the cover layer thickness configuration that can reduce the confocal crosstalk of the recording / reproducing light in consideration of the reflected light on the surface of the cover layer means a cover layer thickness configuration that does not satisfy the above conditions.
  • the thickness of the intermediate layer since the recording layer is extremely thin relative to the intermediate layer, the thickness of the intermediate layer can be designed without considering the thickness of the recording layer.
  • the thickness of the intermediate layer may be designed in consideration of the thickness.
  • the intermediate layer 31 of the recording layer 21 is preferably applied to a structure in which the first and second intermediate layer thicknesses are alternately repeated.
  • the conditions of the cover layer thickness configuration capable of reducing the confocal crosstalk of the recording / reproducing light will be examined.
  • the case where the number of recording layers 21 is 12 is considered.
  • the first intermediate layer thickness can be expressed as m ( ⁇ m)
  • the second intermediate layer thickness can be expressed as m + a ( ⁇ m). Note that the intermediate layer between the recording layer closest to the guide layer and the recording layer closest thereto is considered to have the first intermediate layer thickness.
  • the thickness of the cover layer 12 satisfying the above conditions is as follows.
  • the thickness of the cover layer thickness 12 that satisfies the above conditions is as follows. .
  • the first intermediate layer thickness may be larger than the second intermediate layer thickness.
  • the first intermediate layer thickness can be expressed as m + a ( ⁇ m)
  • the second intermediate layer thickness can be expressed as m ( ⁇ m).
  • the thickness of the cover layer thickness 12 that satisfies the above conditions is as follows. .
  • the red laser light 15 for guide irradiated on the guide layer 20 of the optical disc 10 is branched into a plurality of light beams due to the semi-transparency of the recording layer.
  • a part of the laser beam 15 is reflected by the recording layer 21H, becomes a branched beam 43 and is focused from the inside of the cover layer on the surface of the cover layer 12, and this reflected light is reflected again by the recording layer 21H.
  • the laser beam 15, that is, the recording / reproducing light of the guide layer 20 is merged and detected simultaneously and spatially at substantially the same position by the red photodetector IC.
  • This confocal crosstalk light is detected at the same wavelength as the recording / reproducing light and through almost the same optical path, so that the spatial and band separation means do not work effectively and are detected as powerful noise. It becomes.
  • the intermediate layer 30 between the guide layer 20 and the recording layer 21A and the thickness of the intermediate layer 31 in the recording layer 21 should be suitably created. Therefore, the confocal crosstalk of the guide light is reduced. Therefore, for the confocal crosstalk caused by the light beam reflected from the surface of the cover layer 12, it is desirable to reduce the confocal crosstalk of the guide light by suitably creating the thickness of the cover layer 12.
  • FIG. 19 is a diagram illustrating an example of a state in which the confocal crosstalk of the guide light is reduced.
  • a part of the guide red laser light 15 irradiated to the guide layer 20 of the optical disc 10 is reflected by the recording layer 21H, and becomes a branched beam 44 and reflected by the recording layer 21H.
  • the cover layer 12 is preferably formed, the branched beam 44 does not focus on the surface of the cover layer 12, and even if this reflected light is reflected again by the recording layer 21H, the laser beam 15, that is, the recording / reproducing light of the guide layer 20 does not merge in the same optical path, and is detected at a position that does not spatially coincide with the red photodetector IC. For this reason, the crosstalk light can be spatially separated from the guide light 15, and noise can be reduced.
  • the thickness of the cover layer 12 is determined in consideration of the confocal crosstalk of (1) recording / reproducing light and (2) guide light caused by the light reflected from the inside of the cover layer 12 on the surface of the cover layer 12.
  • the thickness range (stray light zero zone width) of the intermediate layer 30 in which the confocal crosstalk can be sufficiently reduced according to the cover layer thickness is plotted. The wider the thickness range of the intermediate layer 30 that can sufficiently reduce the confocal crosstalk, it is possible to provide a multilayer optical disk having better characteristics. More preferably, the thickness range of the intermediate layer 30 that can sufficiently reduce the confocal crosstalk can be secured to 7 ⁇ m or more.
  • cover layer thickness that can reduce the confocal crosstalk of the recording / reproducing light of (1), that is, a cover layer thickness range having a margin of 2 ⁇ m or more with respect to the above conditions. Show. Therefore, the cover layer thickness can reduce the confocal crosstalk of (1) recording / reproducing light and (2) guide light due to the light reflected from the inside of the cover layer 12 on the surface of the cover layer 12. And an area having a thickness range of the intermediate layer 30 of 7 ⁇ m or more. As described above, the cover layer thickness is required to be approximately 50 ⁇ m or more from the viewpoint of recording layer protection. On the other hand, from the viewpoint of the tilt margin during recording and reproduction, the cover layer thickness is approximately 100 ⁇ m or less in the case of 12 recording layers.
  • FIG. 21A, 21B, and 21C show examples of the disk structure when the first intermediate layer is thinner than the second intermediate layer.
  • the thickness of the cover layer is preferably 66 ⁇ m as an example.
  • An optical disk with high reliability can be obtained by setting the thickness of 30 to about 57 ⁇ m or 89 ⁇ m.
  • the preferable thickness is set to 58 ⁇ m.
  • FIG. 21A shows an example of the structure of the optical disc 10 having 12 recording layers 21.
  • the distance of the guide layer 20 from the cover layer surface is 298 ⁇ m
  • the distance of the recording layer 21A from the cover layer surface is 240 ⁇ m.
  • FIG. 21B and FIG. 21C are structural examples of the optical disc 10 provided with 8 and 6 recording layers 21, respectively.
  • the guide layer 20 is located at 298 ⁇ m from the cover layer surface as in the case of the 12 layers. This is because when these discs are recorded and reproduced by the same optical pickup unit 200, it can be expected that the quality and aberration characteristics of the guide light are substantially the same.
  • the 8-layer disc has a configuration in which the two recording layers near the guide layer and the two recording layers near the cover layer are deleted from the configuration in FIG. 21A, and the thickness of the intermediate layer 30 is 90 ⁇ m.
  • the distance of the recording layer 21A from the cover layer surface is 208 ⁇ m.
  • the thickness of the cover layer is 98 ⁇ m.
  • the disc having 6 recording layers in FIG. 21C has a configuration in which two recording layers close to the cover layer are deleted, the thickness of the intermediate layer 30 remains 90 ⁇ m, and the thickness of the cover layer is 130 ⁇ m. did.
  • the line graph in FIG. 22 is a diagram showing a reduced state of the confocal crosstalk of the guide light (2) when the first intermediate layer thickness is 18 ⁇ m and the second intermediate layer thickness is 14 ⁇ m.
  • the thickness range (stray light zero zone width) of the intermediate layer 30 in which the confocal crosstalk can be sufficiently reduced according to the cover layer thickness is plotted.
  • the wider the thickness range of the intermediate layer 30 that can sufficiently reduce the confocal crosstalk it is possible to provide a multilayer optical disk having better characteristics. More preferably, as described above, the thickness range of the intermediate layer 30 that can sufficiently reduce the confocal crosstalk can be ensured to be 7 ⁇ m or more.
  • the cover layer thickness that can reduce the confocal crosstalk of the recording / reproducing light of (1) above, that is, the cover layer thickness range having a margin of 2 ⁇ m or more with respect to the above conditions. Show. Therefore, the cover layer thickness can reduce the confocal crosstalk of (1) recording / reproducing light and (2) guide light due to the light reflected from the inside of the cover layer 12 on the surface of the cover layer 12. And an area having a thickness range of the intermediate layer 30 of 7 ⁇ m or more. As described above, the cover layer thickness is required to be approximately 50 ⁇ m or more from the viewpoint of recording layer protection. On the other hand, from the viewpoint of the tilt margin during recording and reproduction, the cover layer thickness is approximately 100 ⁇ m or less in the case of 12 recording layers.
  • FIG. 23A, FIG. 23B, and FIG. 23C show the disk structure when the first intermediate layer is thicker than the second intermediate layer.
  • the thickness of the cover layer is preferably 75 ⁇ m as an example.
  • An optical disk with high reliability can be obtained by setting the thickness of 30 to about 39 ⁇ m or 71 ⁇ m.
  • the preferable thickness is set to 37.5 ⁇ m.
  • FIG. 23A shows an example of the structure of the optical disc 10 having 12 recording layers 21.
  • the distance of the guide layer 20 from the cover layer surface is 290.5 ⁇ m
  • the distance of the recording layer 21A from the cover layer surface is 253 ⁇ m.
  • FIG. 23B and FIG. 23C are structural examples of the optical disc 10 provided with 8 and 6 recording layers 21, respectively.
  • the guide layer 20 is located at 290.5 ⁇ m from the cover layer surface as in the case of the 12 layers. This is because when these discs are recorded and reproduced by the same optical pickup unit 200, it can be expected that the quality and aberration characteristics of the guide light are substantially the same.
  • the 8-layer disc has a configuration in which the two recording layers near the guide layer and the two recording layers near the cover layer are deleted from the configuration in FIG. 23A, and the thickness of the intermediate layer 30 is 69.5 ⁇ m.
  • the distance of the recording layer 21A from the cover layer surface is 221 ⁇ m.
  • the thickness of the cover layer is 107 ⁇ m.
  • the disc having 6 recording layers in FIG. 23C has a configuration in which two recording layers close to the cover layer are deleted, the thickness of the intermediate layer 30 remains 69.5 ⁇ m, and the thickness of the cover layer is 139 ⁇ m. It was.
  • the thickness range (stray light zero zone width) of the intermediate layer 30 in which the confocal crosstalk can be sufficiently reduced according to the cover layer thickness is plotted. The wider the thickness range of the intermediate layer 30 that can sufficiently reduce the confocal crosstalk, it is possible to provide a multilayer optical disk having better characteristics. More preferably, the thickness range of the intermediate layer 30 that can sufficiently reduce the confocal crosstalk can be secured to 7 ⁇ m or more.
  • the cover layer thickness that can reduce the confocal crosstalk of the recording / reproducing light of (1) above, that is, the cover layer thickness range having a margin of 2 ⁇ m or more with respect to the above conditions. Show. Therefore, the cover layer thickness can reduce the confocal crosstalk of (1) recording / reproducing light and (2) guide light due to the light reflected from the inside of the cover layer 12 on the surface of the cover layer 12. And an area having a thickness range of the intermediate layer 30 of 7 ⁇ m or more. As described above, the cover layer thickness is required to be approximately 50 ⁇ m or more from the viewpoint of recording layer protection. On the other hand, from the viewpoint of the tilt margin during recording and reproduction, the cover layer thickness is approximately 100 ⁇ m or less in the case of 12 recording layers.
  • FIG. 25A, FIG. 25B, and FIG. 25C show examples of the disk structure when the first intermediate layer is thinner than the second intermediate layer.
  • the thickness of the cover layer is preferably 68 ⁇ m as an example.
  • a highly reliable optical disk can be obtained by setting the thickness of the intermediate layer 30 to about 58.75 ⁇ m or 91.75 ⁇ m.
  • FIG. 25A shows an example of the structure of the optical disc 10 having 12 recording layers 21.
  • the distance of the guide layer 20 from the cover layer surface is 307 ⁇ m, and the distance of the recording layer 21A from the cover layer surface is 247.5 ⁇ m.
  • 25B and 25C are structural examples of the optical disc 10 provided with 8 and 6 recording layers 21, respectively.
  • the guide layer 20 is located 307 ⁇ m from the surface of the cover layer as in the case of the 12 layers.
  • the 8-layer disc has a configuration in which the two recording layers near the guide layer and the two recording layers near the cover layer are deleted from the configuration in FIG. 25A, and the thickness of the intermediate layer 30 is 92.5 ⁇ m. As a result, the distance of the recording layer 21A from the cover layer surface is 214.5 ⁇ m.
  • the thickness of the cover layer is 101 ⁇ m.
  • the disc having 6 recording layers in FIG. 25C has a configuration in which two recording layers close to the cover layer are deleted, the thickness of the intermediate layer 30 remains 92.5 ⁇ m, and the thickness of the cover layer is 134 ⁇ m. It was.
  • the line graph of FIG. 26 is a diagram showing a reduced state of the confocal crosstalk of the guide light (2) when the first intermediate layer thickness is 18.5 ⁇ m and the second intermediate layer thickness is 14.5 ⁇ m. .
  • the thickness range (stray light zero zone width) of the intermediate layer 30 in which the confocal crosstalk can be sufficiently reduced according to the cover layer thickness is plotted.
  • the cover layer thickness that can reduce the confocal crosstalk of the recording / reproducing light of (1) above, that is, the cover layer thickness range having a margin of 2 ⁇ m or more with respect to the above conditions. Show. Therefore, the cover layer thickness can reduce the confocal crosstalk of (1) recording / reproducing light and (2) guide light due to the light reflected from the inside of the cover layer 12 on the surface of the cover layer 12. And an area having a thickness range of the intermediate layer 30 of 7 ⁇ m or more. As described above, the cover layer thickness is required to be approximately 50 ⁇ m or more from the viewpoint of recording layer protection. On the other hand, from the viewpoint of the tilt margin during recording and reproduction, the cover layer thickness is approximately 100 ⁇ m or less in the case of 12 recording layers.
  • FIG. 27A, 27B, and 27C show the disk structure in the case where the first intermediate layer is thicker than the second intermediate layer.
  • the cover layer thickness is preferably 77.5 ⁇ m as an example.
  • the thickness of the intermediate layer 30 is about 40.25 ⁇ m or 73.25 ⁇ m, a highly reliable optical disk can be obtained.
  • the preferable thickness is 39 ⁇ m. did.
  • FIG. 27A shows an example of the structure of the optical disc 10 having 12 recording layers 21.
  • the distance of the guide layer 20 from the cover layer surface is 300 ⁇ m
  • the distance of the recording layer 21A from the cover layer surface is 261 ⁇ m.
  • 27B and 27C are structural examples of the optical disc 10 provided with 8 and 6 recording layers 21, respectively.
  • the guide layer 20 is located 300 ⁇ m from the surface of the cover layer as in the example of 12 layers. This is because when these discs are recorded and reproduced by the same optical pickup unit 200, it can be expected that the quality and aberration characteristics of the guide light are substantially the same.
  • the 8-layer disc has a configuration in which two recording layers near the guide layer and two recording layers near the cover layer are deleted from the configuration in FIG. 27A, and the thickness of the intermediate layer 30 is 72 ⁇ m.
  • the distance of the recording layer 21A from the cover layer surface is 228 ⁇ m.
  • the thickness of the cover layer is 110.5 ⁇ m.
  • the disc having the 6 recording layers in FIG. 27C has a configuration in which two recording layers close to the cover layer are deleted, the intermediate layer 30 remains 72 ⁇ m, and the cover layer has a thickness of 143.5 ⁇ m. It was.
  • the cover layer thickness configuration that does not satisfy the confocal crosstalk generation condition of the recording / reproducing light is preferable. More specifically, 1) The cover layer thickness is as far as possible from the cover layer thickness that satisfies the above-mentioned generation conditions. 2) When the margin from the cover layer thickness that satisfies the above-mentioned generation conditions is the same, the intermediate between the first reflective layer and the target layer. It can be said that the smaller the number obtained by subtracting the number of intermediate layers between the first reflective layer and the reflective layer closest to the cover layer from the number of layers is better.
  • the manufacturing error of the optical storage medium is not taken into consideration.
  • the manufacturing error such as the intermediate layer thickness
  • the cover layer thickness can be selected.
  • thickness manufacturing errors do not occur unevenly in a plurality of intermediate layers, but thickness manufacturing errors tend to occur uniformly.
  • the first intermediate layer thickness is designed to be 18 ⁇ m and the second intermediate layer thickness is 14 ⁇ m
  • the first intermediate layer thickness is actually 18 ⁇ m + error ⁇
  • the second intermediate layer thickness is 14 ⁇ m + error ⁇ . May be.
  • a plurality of intermediate layer thicknesses including manufacturing errors can be examined. Thereby, a more suitable cover layer thickness can be selected from a plurality of cover layer thickness candidates described in the present embodiment.
  • the recording layer is formed by suitably creating the intermediate layer thickness configuration of the guide layer and the recording layer. Interlayer crosstalk in guide light for reproducing the guide layer as well as recording / reproduction light for recording / reproduction can be reduced, and a multilayer optical disc having high reliability in information recording / reproduction can be provided.
  • the thickness of the intermediate layer between the guide layer and the recording layer closest to the guide layer does not match the sum of the thicknesses of any continuous intermediate layers in the recording layer group.
  • the intermediate layer of the recording layer group has a first intermediate layer that is the first film thickness and a second film thickness that is different from the first film thickness. Second intermediate layers are alternately stacked with the recording layer interposed therebetween.
  • the first film thickness is m
  • the second film thickness is m + a
  • the thickness of the intermediate layer between the guide layer and the recording layer closest to the guide layer Is 3.5m + 2a, 5.5m + 3a, 7.5m + 4a, or 9.5m + 5a.
  • the first film thickness is m + a
  • the second film thickness is m
  • the thickness of the intermediate layer between the guide layer and the recording layer closest to the guide layer Is 2.5m + a, 4.5m + 2a, 6.5m + 3a, 8.5m + 4a, or 10.5m + 5a.
  • the first film thickness is 14 ⁇ m
  • the second film thickness is 18 ⁇ m
  • the thickness of the intermediate layer between the guide layer and the recording layer closest to the guide layer is 57 ⁇ m or 89 ⁇ m.
  • the first film thickness is 18 ⁇ m
  • the second film thickness is 14 ⁇ m
  • the thickness of the intermediate layer between the guide layer and the recording layer closest to the guide layer is It is 39 ⁇ m or 71 ⁇ m.
  • the thickness of the cover layer and the layer thickness between the first recording layer closest to the cover layer and the reflective recording layer where the laser beam that has passed through the cover layer is first reflected. Is not the same as the sum of the thicknesses of one or more intermediate layers between the reflective recording layer and the target recording layer.
  • the recording layer group includes a first intermediate layer having a first film thickness that is alternately arranged with one recording layer interposed therebetween, and a second film that is different from the first film thickness.
  • the first film thickness is 18 ⁇ m
  • the second film thickness is 14 ⁇ m
  • the cover layer thickness is 62 ⁇ m, 66-68 ⁇ m, 74-76 ⁇ m, 80 ⁇ m, 94 ⁇ m, and It is a value included in any range of 98 to 100 ⁇ m or any value.
  • the first film thickness is 14.5 ⁇ m
  • the second film thickness is 18.5 ⁇ m
  • the cover layer thickness is 53.5 to 56 ⁇ m, 61 to 64 ⁇ m, 68 ⁇ m, 82.5 ⁇ m, And a value included in any one of 86.5 to 89 ⁇ m and 94 to 97 ⁇ m, or any value.
  • the first film thickness is 18.5 ⁇ m
  • the second film thickness is 14.5 ⁇ m
  • the cover layer thickness C1 is 64 ⁇ m, 68-71.5 ⁇ m, 75.5-78.5 ⁇ m.

Abstract

L'invention concerne un dispositif de stockage optique capable de réduire la diaphonie inter-couches provoquée par un faisceau laser dirigé sur une couche d'asservissement (couche de guidage). Un support de stockage optique d'un mode de réalisation est équipé : d'une couche de couverture ; et d'un groupe de couches d'enregistrement qui comprend des couches d'enregistrement multiples et des couches intermédiaires multiples disposées entre les couches d'enregistrement multiples. La somme (S1) de l'épaisseur (C1) de la couche de couverture et de l'épaisseur (C2) des couches situées entre une première couche d'enregistrement, qui est la plus proche de la couche de couverture, et une couche d'enregistrement réfléchissante, par laquelle un faisceau laser traversant la couche de couverture est d'abord réfléchi, ne correspond pas à la somme (S2) des épaisseurs d'une ou plusieurs couches situées entre la couche d'enregistrement réfléchissante et une couche d'enregistrement cible.
PCT/JP2013/067856 2013-06-28 2013-06-28 Support de stockage optique, dispositif d'enregistrement d'informations et procédé d'enregistrement d'informations WO2014207911A1 (fr)

Priority Applications (1)

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PCT/JP2013/067856 WO2014207911A1 (fr) 2013-06-28 2013-06-28 Support de stockage optique, dispositif d'enregistrement d'informations et procédé d'enregistrement d'informations

Applications Claiming Priority (1)

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PCT/JP2013/067856 WO2014207911A1 (fr) 2013-06-28 2013-06-28 Support de stockage optique, dispositif d'enregistrement d'informations et procédé d'enregistrement d'informations

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WO2014207911A1 true WO2014207911A1 (fr) 2014-12-31

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI632546B (zh) * 2015-10-05 2018-08-11 大陸商上海納光信息科技有限公司 用於光學資料存儲的介質、系統及方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004213720A (ja) * 2002-12-27 2004-07-29 Tdk Corp 光記録媒体
JP2006252752A (ja) * 2005-03-10 2006-09-21 Samsung Electronics Co Ltd 多層記録媒体及びその製造方法
JP2007080303A (ja) * 2005-09-09 2007-03-29 Toshiba Corp 情報記録媒体および光ディスク装置
WO2008015974A1 (fr) * 2006-08-01 2008-02-07 Panasonic Corporation Support d'enregistrement optique et dispositif de reproduction
JP2008117513A (ja) * 2006-10-10 2008-05-22 Matsushita Electric Ind Co Ltd 光記録媒体、情報記録または再生方法、および情報記録または再生装置
JP2011170939A (ja) * 2010-02-22 2011-09-01 Tdk Corp 光記録媒体シリーズ

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004213720A (ja) * 2002-12-27 2004-07-29 Tdk Corp 光記録媒体
JP2006252752A (ja) * 2005-03-10 2006-09-21 Samsung Electronics Co Ltd 多層記録媒体及びその製造方法
JP2007080303A (ja) * 2005-09-09 2007-03-29 Toshiba Corp 情報記録媒体および光ディスク装置
WO2008015974A1 (fr) * 2006-08-01 2008-02-07 Panasonic Corporation Support d'enregistrement optique et dispositif de reproduction
JP2008117513A (ja) * 2006-10-10 2008-05-22 Matsushita Electric Ind Co Ltd 光記録媒体、情報記録または再生方法、および情報記録または再生装置
JP2011170939A (ja) * 2010-02-22 2011-09-01 Tdk Corp 光記録媒体シリーズ

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI632546B (zh) * 2015-10-05 2018-08-11 大陸商上海納光信息科技有限公司 用於光學資料存儲的介質、系統及方法

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