WO2014091845A1

WO2014091845A1 - Guide layer separation type optical recording medium

Info

Publication number: WO2014091845A1
Application number: PCT/JP2013/080199
Authority: WO
Inventors: 松田　勲
Original assignee: 太陽誘電株式会社
Priority date: 2012-12-14
Filing date: 2013-11-08
Publication date: 2014-06-19
Also published as: JP2014120182A; TW201435865A

Abstract

[Problem] To provide a guide layer separation type optical recording medium in which information recording and reproduction characteristics can be improved. [Solution] A guide layer separation type optical recording medium (11) according to an embodiment of the present invention is provided with a guide layer (112) and one or more recording layers (113). The guide layer (112) has a guide track (121) including an in-groove part (121L) and an on-groove part (121G). Information can be recorded, in a region corresponding to the in-groove part (121L) and the on-groove part (121G), in each of the recording layers (113). When the groove width (half the sum of the bottom width (InWa) and the opening width (InWb)) is represented by InW [nm], the depth is represented by inD [nm], and the wavelength of the laser light collected on the guide track (121) is λ [nm], the in-groove part (121L) satisfies the relationships 280 ≤ InW ≤ 430, (0.2λ - 65) ≤ InD ≤ (0.2λ - 40), and 600 ≤ λ ≤ 700.

Description

Guide layer separation type optical recording medium

The present invention relates to a guide layer separation type optical recording medium having a land / groove structure guide layer.

For the purpose of increasing the capacity of optical discs such as DVD (Digital Versatile Disk) and Blu-ray Disc (registered trademark), the recording layer is multilayered. Along with the increase in the number of recording layers, there is also known a method in which tracking control at the time of recording or reproducing data on a recording layer is performed using a guide layer provided separately from the recording layer (for example, Patent Document 1 below) 2).

Such a guide layer separation type optical recording medium generally has a structure in which a guide layer and a plurality of recording layers are laminated via an intermediate layer along the thickness direction of the disc. Grooves and lands are provided in the guide layer. When writing (recording) or reading (reproducing) information on the recording layer, tracking control of the guide layer is performed using a tracking laser beam having the same optical axis as the recording / reproducing laser beam. .

In the guide layer separation type optical recording medium, since the guide layer and the recording layer are provided in separate layers as described above, high tracking followability is required. For example, in Patent Document 3 below, an optical recording medium drive device and an additional recording device that can perform additional recording without destroying recorded information by separating the distance between the already recorded portion and the additional recorded portion by a predetermined number of tracks. A recording method has been proposed.

When recording is performed on a recording layer of a guide layer separation type optical recording medium using a blue wavelength laser beam, for example, at a track pitch of 0.32 μm, a guide track having a track pitch of 0.32 μm is also required in the guide layer. It is. For example, in an optical recording system in which a blue wavelength laser beam is collected on a recording layer while tracking a guide track with a red wavelength laser beam, a guide track having a track pitch of 0.32 μm is recorded on a land track. If it is going to be realized by the groove structure, it is necessary to use each of the land and the groove as a guide track.

In the following description, in the guide track, the track closer to the laser light source is referred to as “groove” or “On-Groove”, and the track farther from the laser light source is referred to as “land” or “in-groove”. (In-Groove) part ".

JP 2003-59092 A JP 2008-192246 A JP 2010-40093 A

Land and groove have different diffraction characteristics of laser light due to the difference in their geometric shapes. For example, if the width of the in-groove portion is narrower than the spot diameter of the laser light, the diffraction of the laser light at the in-groove portion becomes insufficient as compared with the on-groove portion. As a result, there is a problem that the tracking followability at the in-groove portion is lowered and the track quality of the recording pit formed in the region corresponding to the in-groove portion on the recording layer is lowered. Further, when reproducing light is tracked by a recording track formed on the recording layer, it becomes difficult to accurately reproduce the recording track corresponding to the in-groove portion.

In view of the circumstances as described above, an object of the present invention is to provide a guide layer separation type optical recording medium capable of realizing improvement of information recording / reproducing characteristics.

In order to achieve the above object, a guide layer separation type optical recording medium according to one embodiment of the present invention comprises a guide layer and one or more recording layers.
The guide layer has a guide track including an in-groove portion and an on-groove portion.
The one or more recording layers can record information in areas corresponding to the in-groove portion and the on-groove portion.
The in-groove portion has a groove width of the in-groove portion (half value of the sum of the bottom width of the in-groove portion and the opening width of the in-groove portion) is InW [nm], and the depth of the in-groove portion is InD. [Nm], when the wavelength of the laser beam focused on the guide track is λ [nm],
280 ≦ InW ≦ 430,
(0.2λ−65) ≦ InD ≦ (0.2λ−40), and
600 ≦ λ ≦ 700
Satisfy the relationship.

According to the above guide layer separation type optical recording medium, the diffraction characteristic of the laser beam to the in-groove portion is enhanced, and the tracking followability of the in-groove portion is improved. As a result, a high-quality recording track can be formed on the recording layer, and the reproduction characteristics of the recording track can be improved.

The groove width InW [nm] of the in-groove portion may be configured to satisfy a relationship of 330 ≦ InW ≦ 400.
Further, the depth InD [nm] of the in-groove portion may be configured to satisfy a relationship of (0.2λ−55) ≦ InD ≦ (0.2λ−45).
This makes it possible to stably secure an evaluation value (less than 1E-3) of SER (Symbol Error Rate) that enables error correction.

The groove width of the in-groove portion may be wider than the groove width of the on-groove portion (half value of the sum of the minimum width of the on-groove portion and the maximum width of the on-groove portion).
As a result, good diffraction characteristics of the laser light in the in-groove portion can be secured, and a tracking error signal can be generated with high accuracy.

According to the guide layer separation type optical recording medium of the present invention, it is possible to realize improvement in information recording / reproducing characteristics.

It is a figure which shows the optical recording system applied in one Embodiment of this invention. It is a figure which shows the accommodation form of the disc cartridge and the some optical recording medium in this in the optical recording system of FIG. It is a figure which shows the structure of the disc cartridge in the optical recording system of FIG. 1, an optical recording medium, and a drive unit. It is sectional drawing which shows the structure of the guide layer separation type | mold optical recording medium which concerns on one Embodiment of this invention. It is a principal part enlarged view of the optical recording medium of FIG. FIG. 5 is a diagram illustrating a structure of a double spiral track of a guide layer in the optical recording medium of FIG. 4. FIG. 5 is a diagram illustrating a configuration of a region divided by a radial position of a guide layer and a recording layer in the optical recording medium in FIG. 4. It is a figure which shows the structure of the disk drive in the optical recording system of FIG. FIG. 9 is a diagram for explaining a recording order of data tracks by the disk drive of FIG. 8. FIG. 9 is a diagram for explaining a recording order of data tracks by the disk drive of FIG. 8. FIG. 5 is a schematic diagram illustrating a form of guide light irradiation to a guide layer in the optical recording medium of FIG. 4. FIG. 5 is a schematic diagram illustrating details of an in-groove portion provided in a guide layer in the optical recording medium in FIG. 4. It is one experimental result which shows the wavelength dependence of the NPP value of the diffracted light with respect to the groove width of the in-groove part of FIG. It is one experimental result which shows the wavelength dependence of the NPP value of the diffracted light with respect to the groove depth of the in-groove part of FIG. In FIG. 14, it is the figure which plotted the groove depth from which NPP becomes the maximum in each wavelength range of guide light. It is a figure which shows the relationship between the groove width and depth of an in-groove part in wavelength 650nm of guide light, and an NPP characteristic. It is a figure which shows the relationship between the groove width and depth of an in-groove part in wavelength 600nm of guide light, and NPP characteristic. It is a figure which shows the relationship between the groove width and depth of an in-groove part in wavelength 700nm of guide light, and NPP characteristic.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an optical recording system according to an embodiment of the present invention.

FIG. 1 is a diagram showing the overall configuration of an optical recording system.
The optical recording system 1 includes a disk cartridge 10, a disk transport mechanism 20, a drive unit 30, a RAID controller 40, and a host device 50. Details of each will be described below.

[Disc cartridge]
The disc cartridge 10 is a unit in which a plurality of multilayer optical discs 11 (guide layer separation type optical recording media) are individually detachably accommodated.

FIG. 2 is a view showing a storage form of the disk cartridge 10 and a plurality of multilayer optical disks 11 therein.
As the accommodation form of the plurality of multilayer optical discs 11 in the disc cartridge 10, flat stacking, vertical alignment, and the like are assumed. In any case, it is preferable that a certain gap is provided between adjacent multilayer optical discs 11 so that the multilayer optical disc 11 can be smoothly inserted into and removed from the disc cartridge 10. The shape of the disk cartridge 10 is assumed to be, for example, a rectangular parallelepiped shape or a cylindrical shape from the viewpoint of handling by the user and the storage efficiency of the multilayer optical disk 11. In the example of FIG. 2, a rectangular parallelepiped disk cartridge 10 in which a plurality of multilayer optical disks 11 are accommodated in a flat stack is used.

FIG. 3 is a diagram showing the configuration of the disk cartridge 10, the multilayer optical disk 11, and the drive unit 30.
At least one side surface of the disk cartridge 10 is provided with an opening 101 for loading and unloading the multilayer optical disk 11 and a door (not shown) for opening and closing the opening 101. The door is opened and closed in conjunction with the operation of loading / unloading the multilayer optical disk 11 from / to the disk cartridge 10 by the disk transport mechanism 20, and is closed at other times. The plurality of multilayer optical disks 11 accommodated in the disk cartridge 10 are taken out by the disk transport mechanism 20 and selectively transported (loaded) to the plurality of disk drives 31 in the drive unit 30.

In the present invention, the configuration of the disk cartridge 10 is not limited to that shown in FIG. Various modifications such as the shape of the disk cartridge 10, the number and position of the openings, the presence / absence of a door, and the accommodation form of a plurality of multilayer optical disks 11 are possible.

[Multilayer optical disc 11]
The multilayer optical disk 11 accommodated in the disk cartridge 10 is assumed to be a so-called guide layer separation type multilayer optical disk in which the guide layer and the recording layer are separated into separate layers.

4 and 5 are cross-sectional views showing the configuration of a multilayer optical disk 11 as a guide layer separation type optical recording medium.
As shown in FIG. 4, the multilayer optical disc 11 includes a guide layer 112 and a plurality of recording layers 113. In the example of the multilayer optical disk 11 in FIG. 9, the number of recording layers 113 is “4”. An intermediate layer 114 having optical transparency is interposed between the guide layer 112 and the recording layer 113 closest to the guide layer 112 and between the adjacent recording layers 113. These layers are the protective layer 115, the recording layer 113 (R3), the intermediate layer 114, the recording layer 113 (R2), and the intermediate layer 114 from the side on which the recording / reproducing light R1 and the guide light R2 from the optical pickup 32 are incident. The recording layer 113 (R1), the intermediate layer 114, the recording layer 113 (R0), the intermediate layer 114, and the guide layer 112 are laminated in this order.

As shown in FIG. 5, the guide layer 112 includes a light-transmitting plastic substrate 110 such as a disc-shaped polycarbonate having a spiral uneven portion 111 on one surface, and the uneven portion 111 following the uneven shape of the uneven portion 111. And a reflective structure 120 covering the substrate. The substrate 110 is typically molded using a molding die such as a stamper, and the reflective film 120 is a metal material having a high reflectance with respect to red laser light, such as silver (Ag) or an alloy thereof. The sputtered film is formed. The thickness of the substrate 110 is not particularly limited, and is, for example, 0.6 mm to 1.2 mm, and 1.1 mm in this embodiment. The thickness of the reflective film 120 is not particularly limited, and is, for example, 20 nm to 100 nm, and in this embodiment, 60 nm.

As shown in FIGS. 5 and 6, a guide track 121 having a land / groove structure is spirally provided on the surface of the guide layer 112 facing the recording layer 113. The land is formed between the grooves, and the groove is formed between the lands. In the following description, in the guide track 121, the track closer to the laser light source (optical pickup 32) is referred to as “groove” or “On-Groove portion”, and the track farther from the laser light source is referred to as “land”. Or “In-Groove”.

The guide track 121 constitutes a so-called “double spiral track” composed of a land guide track (in-groove portion 121L) and a groove guide track (on-groove portion 121G). In the present embodiment, the in-groove portion 121L and the on-groove portion 121G are continuously formed in a spiral shape from the inner peripheral side to the outer peripheral side of the multilayer optical disc 11, but are not limited thereto. For example, the in-groove portion 121L and the on-groove portion 121G may be continuously formed in a spiral shape so as to be alternately switched at a predetermined period (for example, every circumference) from the inner circumference side to the outer circumference side of the multilayer optical disc 11.

The in-groove portion 121L is surrounded by a pair of side walls 121s that form a boundary with the on-groove portion 121G. The side wall 121s is typically formed with a tapered surface, but may be formed with a surface perpendicular to the surface of the substrate 110. The taper angle of the side wall 121s is not particularly limited, and is appropriately set according to the draft angle of the stamper mold, the uneven height of the uneven portion 111, the thickness of the reflective film 120, and the like.

In the guide track 121, physical address information is formed by wobbling or pit rows on the side wall surface. The in-groove portion 121L and the on-groove portion 121G are formed with a track pitch (0.64 μm) corresponding to red laser light used for recording / reproduction of a DVD (Digital Versatile Disk), for example. The average pitch between the land and the groove is 0.32 μm, which corresponds to the track pitch of the guide track 121. Hereinafter, the laser beam of the red laser beam is referred to as “guide light”.

In the optical recording system 1 of the present embodiment, for example, a push-pull method (PP: Push-Pull), a differential push-pull method (DPP: Differential Push-Pull), 3 beams in each of the land and groove of the guide track 121. Tracking control is performed by law. By performing tracking control in each of the land and groove of the guide track 121, information can be recorded on the recording layer 113 at a track pitch of 0.32 μm.
Details of the configuration of the guide track 121 will be described later.

The recording layer 113 is a layer on which information is recorded at a track pitch (0.32 μm) corresponding to blue laser light used for recording / reproducing of a Blu-ray Disc (registered trademark), for example. Hereinafter, this blue laser light is referred to as “recording / reproducing light” or “recording light”.

The recording layer 113 includes, for example, a light absorption layer and a reflection layer. As the light absorption layer, an organic dye such as a cyanine dye or an azo dye, or an inorganic oxide material such as Si, Cu, Sb, Te, Ge, Fe, or Bi is used. When the target recording layer 113 in the multilayer optical disc 11 is irradiated with the recording light, the reflectance of the area irradiated with the recording light is changed, and the area where the reflectance is changed is formed as a recording mark. Information is recorded in layer 113. The thickness of the recording layer 113 is not particularly limited, and is 10 nm to 200 nm, for example, and 83 nm in the present embodiment.

The distance X between the guide layer 112 and the recording layer 113 (R0) closest to the guide layer 112 is not particularly limited, and an appropriate value can be set. In the present embodiment, the distance X is set to 25 μm or more, thereby preventing crosstalk between the guide light irradiated to the guide layer 112 and the recording / reproducing light irradiated to the recording layer 113 (R0). The tracking followability of the guide layer 112 (particularly the in-groove portion 121L) can be improved.

The tracking control and the acquisition of the physical address and the reference clock at the time of recording information on the recording layer 113 are performed by using the guide track 121 of the guide layer 112. Therefore, the recording track 113 has a guide track having a land / groove structure. 121 is not necessary. Therefore, the surface of the recording layer 113 may be flat.

The intermediate layer 114 and the protective layer 115 are formed of a light-transmitting material such as an ultraviolet curable resin. The thickness of the intermediate layer 114 is not particularly limited, and is 10 μm to 300 μm, for example, and is 200 μm in this embodiment. The thickness of the protective layer 115 is not particularly limited, and is 10 μm to 300 μm, for example, and is 100 μm in this embodiment.

FIG. 7 is a diagram showing a configuration of regions divided by the radial positions of the guide layer 112 and the recording layer 113 in the multilayer optical disc 11.
The guide layer 112 and the recording layer 113 are divided into the lead-in area, the data area, and the lead-out area in common from the inner peripheral side depending on the position in the radial direction.

In the lead-in area of the guide layer 112, management information unique to the multilayer optical disk 11 is recorded in advance by wobbling of guide tracks or pit rows provided in lands and grooves.
The management information unique to the multilayer optical disc 11 includes, for example, recommended information such as the number of recording layers, recording method, recording linear velocity, laser power and laser drive pulse waveform during recording / reproduction, position information of the data area, position of the OPC area Contains information. The OPC area is provided, for example, on the inner peripheral side of the lead-in area.

In the data area of the guide layer 112, physical address information assigned to the data area is recorded in advance by wobbling of the guide track 121 or prepit strings provided in lands and grooves.

In the lead-out area of the guide layer 112, the same information as the information recorded in the lead-in area may be recorded in advance by wobbling of the guide track 121 or a prepit row provided in the land and groove. Good.

The lead-in area of the recording layer 113 is an area where management information used for recording / reproducing of the recording layer 113 is recorded by a recording mark. Management information used for recording / reproduction of the recording layer 113 includes layer information such as a layer number assigned to the recording layer 113, replacement management information regarding replacement processing of a defective area, and recording time determined by OPC processing (calibration processing). Recording condition data such as the optimum laser power, address information of the recorded area, and the like. Among these, at least the layer information is, for example, information recorded with a recording mark on each recording layer 113 before the multilayer optical disc 11 is actually used for data recording by the user.

[Disc transport mechanism]
The disk transport mechanism 20 takes out the target multilayer optical disk 11 from the disk cartridge 10 and loads it in the disk drive 31 in the drive unit 30, or conversely returns the multilayer optical disk 11 ejected from the disk drive 31 to the disk cartridge 10. Mechanism.

The disk transport mechanism 20 operates independently so that, for example, a plurality of multilayer optical disks 11 can be taken out simultaneously or sequentially from the disk cartridge 10 and can be separately loaded into the plurality of disk drives 31 in the drive unit 30. A plurality of possible transport mechanisms may be provided.

[Drive unit]
A plurality of disk drives 31 are mounted on the drive unit 30. In the example of FIG. 1, five disk drives 31 are installed. The number of multilayer optical disks 11 accommodated in the disk cartridge 10 and the number of disk drives 31 mounted in the drive unit 30 are not necessarily the same.

(Disk drive configuration)
FIG. 8 is a diagram showing the configuration of a disk drive 31 that is an optical recording apparatus.
The disk drive 31 includes an optical pickup 32. The optical pickup 32 includes a recording / reproducing optical system corresponding to the recording / reproducing light and a guide optical system corresponding to the guide light.

The recording / reproducing optical system includes a first light source 33, a first collimator lens 34, a first polarizing beam splitter 35, a first relay lens 36, a second collimator lens 37, a combining prism 38, and a quarter wavelength plate. 39, an objective lens 60, a first light receiving lens 61, a first light receiving portion 62, and the like. Here, the combining prism 38, the quarter wavelength plate 39, and the objective lens 60 belong to both the recording / reproducing optical system and a guide optical system described later.

The first light source 33 includes a laser diode that emits blue laser light as recording / reproducing light R1. The recording / reproducing light R 1 emitted from the first light source 33 is converted into parallel light by the first collimator lens 34, and passes through the first polarization beam splitter 35, the first relay lens 36 and the second collimator lens 37. The light enters the combining prism 38. The synthesizing prism 38 makes the optical axes of the recording / reproducing light R1 incident from the second collimator lens 37 and the guide light R2 incident from a third collimator lens belonging to a guide optical system, which will be described later, coincide with each other. And is incident on the objective lens 60 through the quarter-wave plate 39. The incident recording / reproducing light is collected by the objective lens 60 so as to be focused on the target recording layer 113 of the multilayer optical disc 11.

The recording / reproducing light (returned light) reflected by the recording layer 113 is incident on the combining prism 38 via the objective lens 60 and the quarter wavelength plate 39, and is transmitted through the combining prism 38 in the incident direction. Return to the first polarization beam splitter 35 via the collimator lens 37 and the first relay lens 36. The first polarization beam splitter 35 reflects the return light of the first wavelength from the first relay lens 36 at an angle of about 90 degrees and passes through the first light receiving lens 61 to the first light receiving unit 62. Make it incident.

For example, the first light receiving unit 62 includes a light receiving element whose light receiving surface is divided into four in the disk radial direction and the tangential direction, and outputs a voltage signal of a level corresponding to the light receiving intensity for each divided light receiving surface. To do.

The guide optical system includes a second light source 63, a third collimator lens 64, a second polarizing beam splitter 65, a second relay lens 66, a fourth collimator lens 67, a combining prism 38, and a quarter wavelength plate 39. The objective lens 60, the second light receiving lens 68, the second light receiving portion 69, and the like.

The second light source 63 emits guide light R2 which is red laser light. The guide light R2 emitted from the second light source 63 is converted into parallel light by the third collimator lens 64, and is combined through the second polarization beam splitter 65, the second relay lens 66, and the fourth collimator lens 67. The light enters the prism 38. As described above, the guide light R2 incident on the combining prism 38 is combined by the combining prism 38 so that the optical axis coincides with the recording / reproducing light R1 incident from the second collimator lens 37 of the recording / reproducing optical system. Then, the light enters the objective lens 60 through the quarter-wave plate 39. The incident guide light R <b> 2 is collected by the objective lens 60 so as to be focused on the guide layer 112 of the multilayer optical disk 11.

The guide light R2 (return light) reflected by the guide layer 112 enters the synthesis prism 38 through the objective lens 60 and the quarter wavelength plate 39, and is reflected by the synthesis prism 38 at an angle of about 90 degrees. Returning to the second polarizing beam splitter 65 via the fourth collimator lens 67 and the second relay lens 66. The second polarization beam splitter 65 reflects the return light of the guide light R2 from the second relay lens 66 at an angle of about 90 degrees, and passes through the second light receiving lens 68 to the second light receiving unit 69. Make it incident.

The second light receiving unit 69 is constituted by, for example, a light receiving element in which the light receiving surface is divided into four in the disk radial direction and the tangential direction. The second light receiving unit 69 outputs a voltage signal corresponding to the amount of received light for each divided light receiving surface.

Further, the optical pickup 32 is provided with a tracking actuator 70 and a focusing actuator 79. The tracking actuator 70 moves the objective lens 60 in the disk radial direction that is perpendicular to the optical axis under the control of the tracking control unit 71. The focusing actuator 79 moves the objective lens 60 in the optical axis direction under the control of the focus control unit 77.

Further, the optical pickup 32 guides the guide light R2 and the first relay lens actuator 80 that moves the first relay lens 36 in the optical axis direction in order to switch the recording layer 113 irradiated with the recording / reproducing light. In order to focus on the layer 112, a second relay lens actuator 81 that moves the second relay lens 66 in the optical axis direction is provided.

Also. Although not shown, the optical pickup 32 is also provided with a tilt actuator that adjusts the inclination of the objective lens 60 in the radial direction and the tangential direction with respect to the recording surface of the multilayer optical disc 11.
The above is the description of the optical pickup 32.

In addition to the optical pickup 32, the disk drive 31 includes a tracking control unit 71, a data modulation unit 72, a first light source drive unit 73, a second light source drive unit 74, an equalizer 75, a data reproduction unit 76, a focus A control unit 77, a tracking error generation unit 82, a controller 83, a first relay control unit 84, a second relay control unit 85, and a focus error generation unit 86 are provided. In addition, the disk drive 31 includes a disk motor drive unit that drives the disk motor 87, a feed mechanism that sends the optical pickup 32 in the radial direction of the multilayer optical disk 11, and a pickup vertical feed mechanism that sends the optical pickup 32 in the optical axis direction of the objective lens 60. Etc. These illustrations are omitted.

The data modulator 72 modulates the recording data supplied from the controller 83 and supplies the modulated signal to the first light source driver 73.

The first light source drive unit 73 generates a drive pulse for driving the first light source 33 based on the modulation signal from the data modulation unit 72.

The equalizer 75 performs an equalization process such as PRML (Partial Response Maximum Maximum Likelihood) on the reproduction RF signal from the first light receiving unit 62 to generate a binary signal.

The data reproduction unit 76 demodulates data from the binary signal output from the equalizer 75, performs decoding processing such as error correction from the demodulated data, generates reproduction data, and supplies the reproduction data to the controller 83.

The tracking error generation unit 82 generates a tracking error signal by, for example, a push-pull method, a differential push-pull method, a three-beam method, or the like based on the output of the second light receiving unit 69 at the time of data recording. The tracking error generation unit 82 generates a tracking error signal by, for example, push-pull method, differential push-pull method, three-beam method, etc. based on the output of the first light receiving unit 62 at the time of data reproduction, for example. To do.

The tracking control unit 71 performs tracking control by controlling the tracking actuator 70 based on the tracking error signal to move the objective lens 60 in a direction perpendicular to the optical axis.

The focus error generation unit 86 generates a focus error signal based on, for example, the astigmatism method based on the output of the first light receiving unit 62.

The focus control unit 77 performs focus control by controlling the focus actuator 79 and moving the objective lens 60 in the optical axis direction based on the focus error signal.

The first relay control unit 84 controls the first relay lens actuator 80 so as to switch the recording layer to be recorded.

The second relay control unit 85 controls the second relay lens actuator 81 so that the guide light R2 is focused on the guide layer 112 (guide track 121).

The controller 83 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and the like. The controller 83 controls the entire disk drive 31 based on a program loaded in the main memory area allocated to the RAM.

The drive unit 30 includes a plurality of the disk drives 31 and can be independently controlled, and can record and reproduce information on the loaded multilayer optical disk 11 simultaneously.

[RAID controller]
A RAID (Redundant Arrays of Inexpensive Disks) controller 40, in response to a recording command from the host device 50, multiplexly records data on one or more disk drives 31 in the drive unit 30, or records them in a distributed manner by striping. RAID control is performed. The controller 83 of each disk drive 31 to which a recording or reproduction instruction is given from the RAID controller 40 performs control for recording or reproducing data on the multilayer optical disk 11.

[Host device]
The host device 50 is the highest-level device that controls the optical recording system 1. The host device 50 may be a personal computer. The host device 50 creates or prepares data for recording, and supplies a recording command for the data for recording to the RAID controller 40. Further, the host device 50 supplies a read command including a file name designated by a user or the like to the RAID controller 40, and acquires data of the corresponding file name from the RAID controller 40 as a response.

3, the host device 50 includes a CPU 51, a memory 52, a drive I / F 53, a disk transport mechanism I / F 54, and a system bus 56.

The CPU 51 performs arithmetic processing for executing a program stored in the memory 52 and controls exchange of information with each unit through the system bus 56.
The memory 52 is a main memory that stores programs to be executed by the CPU 51, operation results, and the like.

The drive I / F 53 is an interface for communicating with a plurality of disk drives 31 through the RAID controller 40.

The disk transport mechanism I / F 54 is an interface for communicating with the disk transport mechanism 20.

[Operation example of optical recording system]
Next, control when recording is performed on the multilayer optical disk 11 in one or more disk drives 31 in the drive unit 30 of the optical recording system 1 will be described.

A data recording command is given from the host device 50 to the controller 83 of one or more disk drives 31 in the drive unit 30 through the RAID controller 40. Since the operation of each disk drive 31 when receiving a recording command is the same, the operation of one disk drive 31 will be described.

The controller 83 of the disk drive 31 controls a feed mechanism (not shown) so as to move the optical pickup 32 to a position corresponding to the innermost circumference of the area where data is not recorded in the recording area of the recording layer 113 of the optical disk 11. Then, the disk motor drive unit (not shown) is controlled to rotate the disk 11 at an appropriate speed in the CLV method or the CAV method.

Further, the controller 83 positions the first relay lens 36 of the optical pickup 32 in the optical axis direction so that the recording light from the objective lens 60 of the optical pickup 32 is focused on the target recording layer 113 of the multilayer optical disc 11. And the position of the second relay lens 66 of the optical pickup 32 in the optical axis direction is controlled so that the guide light from the objective lens 60 of the optical pickup 32 is focused on the guide layer 112 of the optical disc 11.

The controller 83 of the disk drive 31 supplies the data modulation unit 72 with the recording data transferred from the host device 50 through the RAID controller 40. The data modulation unit 72 generates a recording signal by performing modulation of recording data, adding an error correction code, and the like, and supplies the recording signal to the first light source driving unit 73. The first light source driving unit 73 generates a driving pulse for the first light source 33 based on the recording signal and supplies it to the first light source 33. At the same time, the controller 83 outputs a control signal to the second light source driving unit 74 so as to drive the second light source 63. Thereby, recording of data on the recording layer 113 by the recording light from the optical pickup 32 is started. That is, data recording by the CLV method or the CAV method is started from the inner periphery to the outer periphery with respect to the target recording layer 113 of the optical disc 11.

Here, tracking control during data recording will be described.
The tracking error generation unit 82 generates an NPP (Normalized Push-Pull) signal (tracking error signal) by the PP (push-pull) method, for example, based on the output of the second light receiving unit 69. The NPP signal is a signal obtained by dividing the push-pull voltage by the RF signal voltage and standardizing it. In addition to the push-pull method, for example, the tracking error signal may be generated by a DPP (differential push-pull) method or a three-beam method.

The tracking control unit 71 inputs a tracking error signal, supplies a tracking drive signal to the tracking actuator 70 so that the value approaches 0, and moves the objective lens 60 in a direction perpendicular to the optical axis (disk radial direction). Move to perform tracking control.

Tracking control at the time of recording is performed using one of the in-groove portion 121L and the on-groove portion 121G constituting the guide track 121 provided on the guide layer 112 of the multilayer optical disc 11 first.

Note that tracking control at the time of data reproduction is performed using a data track constituted by a row of recording marks recorded on the recording layer 113 of the multilayer optical disc 11.

9 and 10 are diagrams showing the recording order of data tracks by the disk drive 31 of this embodiment.
In the disk drive 31 of this embodiment, for example, recording is first performed by tracking control for the in-groove portion 121L (see FIG. 9), and after recording by tracking control for all the in-groove portions 121L is completed. Then, the recording is switched to the tracking control for the on-groove portion 121G (see FIG. 10). The details will be described below.

In FIG. 9, using the in-groove portion 121L, recording is continuously performed in the order of L1, L2, and L3 on an arbitrary recording layer Rx of the multilayer optical disc 11 from the inner circumference side to the outer circumference side of the multilayer optical disc 11. FIG.
The upper half of the figure shows the multilayer optical disk 11 viewed from a direction orthogonal to the optical axis direction of the objective lens 60, and the lower half shows an arbitrary recording layer Rx of the multilayer optical disk 11 in the optical axis direction of the objective lens 60. FIG.

L0-L4 indicates the in-groove portion 121L, and G0-G4 indicates the on-groove portion 121G. Note that the in-groove portion 121L is actually one continuous track, and the on-groove portion 121G is the same, but for the sake of explanation, guide track portions having different positions on the disk radius are referred to as “in-groove portion ( L0) ”and“ on-groove portion (G0) ”.

In the disk drive 31 of the present embodiment, recording is performed by tracking control on the in-groove portion 121L first, whereby recording marks M are recorded on an arbitrary recording layer Rx of the multilayer optical disk 11 at a pitch of 0.64 μm.

[Multilayer Optical Disc According to this Embodiment]
Next, details of the multilayer optical disc 11 according to the present embodiment will be described.

Generally, in the guide layer separation type optical recording medium, the in-groove portion and the on-groove portion of the guide layer have a diffraction characteristic of the laser light (guide light) for tracking control due to the difference in the geometric shape thereof. Different from each other. For example, if the width of the in-groove portion is narrow with respect to the spot diameter of the laser light (for example, 1.1 μm at a wavelength of 650 nm), the diffraction of the laser light at the in-groove portion becomes insufficient compared to the on-groove portion, Since the tracking becomes slippery, the scanning on the recording pit is easily shifted.

For example, FIG. 11 schematically shows a state in which the guide light GL is irradiated to the in-groove portion 221L and the on-groove portion 221G of the guide track 221. The groove width of the in-groove portion 221L is narrower than the spot diameter of the guide light GL. Since the on-groove portion 221G is irradiated with the guide light GL on the groove (groove) protruding toward the optical pickup (lower side in the figure) and the groove (land) recessed on both sides around this, the diffraction limit is not exceeded. Hard to reach. On the other hand, since the guide light GL is irradiated to the land and the grooves on both sides of the in-groove portion 221L, the guide light GL hardly enters the land and it is difficult to obtain diffraction. Such a phenomenon depends on the wavelength of the guide light GL, and becomes more prominent as the wavelength of the guide light GL is longer.

As a result of the above problems, the C / N (Carrier-to-Noise-ratio) of the NPP signal due to insufficient diffraction deteriorates and the tracking followability at the in-groove portion decreases, so that the in-groove portion on the recording layer is reduced. There is a problem that the track quality of the recording pits (record marks) formed in the area corresponding to is lowered. Further, when reproducing light is tracked by a recording track formed on the recording layer, it becomes difficult to accurately reproduce the recording track corresponding to the in-groove portion.

Therefore, in order to solve the above problem, the present inventor has examined the groove width and depth of the in-groove portion 121L that can suppress the deterioration of C / N of the NPP signal. Here, as shown in FIG. 11, the groove width of the in-groove portion 121L in the guide layer 112 is InW [nm], and the depth of the in-groove portion 121L is InD [nm]. The groove width InW was set to a half value ((InWa + InWb) / 2) of the sum of the bottom width InWa of the in-groove portion 121L and the opening width InWb of the in-groove portion 121L.

In FIG. 11, “P” represents the track pitch of the in-groove portion 121L (or the on-groove portion 121G), which is 0.64 μm here. Since both the in-groove portion 121L and the on-groove portion 121G function as guide tracks, the track pitch of the land / groove structure guide track 121 as a whole is 0.32 μm (P / 2).

In this embodiment, as shown in FIG. 11, the groove width of the on-groove portion 121G is set to OnW [nm]. The groove width OnW is defined as a half value ((OnWa + OnWb) / 2) of the minimum width (width of the protruding end) OnWa of the on-groove part 121G and the maximum width (base part width) OnWb of the on-groove part 121G. . As a result, the sum of the groove width InW of the in-groove portion 121L and the groove width OnW of the on-groove portion 121G matches the track pitch P of the in-groove portion 121L (or the on-groove portion 121G).
The depth (height) of the on-groove portion 121G is the same as the depth (InD) of the in-groove portion 121L.

FIG. 13 is an experimental result showing the wavelength dependence of the guide light of the NPP characteristic with respect to the groove width InW of the in-groove portion 121L. As shown in the figure, the NPP characteristic tends to decrease as the wavelength of the guide light increases. Further, it was confirmed that the groove width InW of the in-groove portion 121L having the maximum NPP characteristic was 350 nm at any wavelength (600 nm, 650 nm, and 700 nm).

On the other hand, FIG. 14 shows an experimental result showing the wavelength dependence of the guide light of the NPP characteristic with respect to the depth InD of the in-groove portion 121L. As shown in the figure, the maximum value of NPP in each wavelength band was almost constant. Further, the depth of the in-groove portion 121L at which the NPP characteristic is maximized increases as the wavelength of the guide light increases. FIG. 15 is a graph plotting the groove depth InD at which the NPP is maximum for each wavelength (λ) of the guide light. As shown in FIG. 15, the wavelength and the groove depth InD are linear functions (y = 0. It was confirmed that it can be approximated by 2x-50).

From the viewpoint of ensuring high-accuracy tracking followability, the value of NPP is preferably high, and practically, reproduction evaluation of recording pits (record marks) formed on the recording track of the recording layer Rx corresponding to the in-groove portion It is preferable that the index (SER: Symbol Error Rate) is suppressed to 10 or less of the fourth power of the order (9.9 × 10 ⁻⁴ (9.9E-4)). The groove width InW [nm] and the depth InD [nm] of the in-groove portion 121L satisfying such conditions are defined by the following equations (1) to (3).

280 ≦ InW ≦ 430 (1)
(0.2λ−65) ≦ InD ≦ (0.2λ−40) (2)
600 ≦ λ ≦ 700 (3)
Here, λ [nm] represents the wavelength of the laser light focused on the guide track 121, that is, the guide light.

When the groove width InW of the in-groove portion 121L is less than 280 nm, the diffraction of the guide light to the in-groove portion 121L becomes insufficient, and the C / N deterioration of the NPP signal is inevitable. On the other hand, when the groove width InW exceeds 430 nm, the groove width (OnW) of the on-groove portion 121G becomes too narrow at the track pitch P (0.64 μm) of the in-groove portion 121L, and the tracking followability of the on-groove portion 121G is reduced. Decline is inevitable.

Further, when the depth InD of the in-groove portion 121L is less than (0.2λ−65) nm, the difference between the diffraction characteristics in the in-groove portion 121L and the diffraction characteristics in the on-groove portion 121G is small, and the tracking follow-up property is reduced. Invite. On the other hand, when the depth InD of the in-groove portion 121L exceeds (0.2λ-40) nm, the diffraction of the guide light to the in-groove portion 121L becomes insufficient, and the C / N deterioration of the NPP signal is inevitable.

By satisfying the above formulas (1) to (3), the C / N deterioration of the NPP signal due to insufficient diffraction is prevented, and the tracking followability of the on-groove portion 121G is ensured while the in-groove portion 121L is scanned. The guide light from above the center can be prevented from coming off. As a result, a high-quality recording track can be formed on the recording layer, and the reproduction characteristics of the recording track can be improved.

From the above expressions (1) and (2), the groove width InW and the depth InD of the in-groove portion 121L are defined as follows according to the wavelength λ of the guide light.
When the wavelength is 600 nm,
280 nm ≦ InW ≦ 430 nm, 55 nm ≦ InD ≦ 80 nm
When the wavelength is 650 nm,
280 nm ≦ InW ≦ 430 nm, 65 nm ≦ InD ≦ 90 nm
When the wavelength is 700 nm,
280 nm ≦ InW ≦ 430 nm, 75 nm ≦ InD ≦ 100 nm

Preferably, the groove width InW and the depth InD of the in-groove portion 121L are defined as follows according to the wavelength λ of the guide light.
When the wavelength is 600 nm,
330 nm ≦ InW ≦ 400 nm, 65 nm ≦ InD ≦ 75 nm
When the wavelength is 650 nm,
330 nm ≦ InW ≦ 400 nm, 75 nm ≦ InD ≦ 85 nm
When the wavelength is 700 nm,
330 nm ≦ InW ≦ 400 nm, 85 nm ≦ InD ≦ 95 nm

In this case, when 600 ≦ λ ≦ 700, the above equations (1) and (2) are modified as follows.
330 ≦ InW ≦ 400 (1) ′
(0.2λ−55) ≦ InD ≦ (0.2λ−45) (2) ′

Note that the expression (1) ′ indicates that the groove width InW of the in-groove portion 121L is larger (wider) than the groove width OnW of the on-groove portion 121G at the track pitch (P) of the in-groove portion 121L (on-groove portion 121G). Represents. Accordingly, the in-groove portion 121L can be scanned with a tracking capability equivalent to or better than the tracking tracking capability with respect to the on-groove portion 121G.

Hereinafter, examples of the present invention will be described. Of course, the present invention is not limited to the following examples.

(Example 1)
A disc-shaped polycarbonate substrate (base material) having an outer diameter of 120 mm and a thickness of 1.1 mm was produced using a stamper molding die. In this example, an annular area from the position of a radius of 23.5 mm to a radius of 58.0 mm is used as a data recording area, and this data recording area is constituted by a guide track including a spiral in-groove portion and an on-groove portion. . A reflective layer made of an Ag-0.2 wt% In alloy was sputtered to a thickness of 60 nm on the surface of the guide track. When a concave portion corresponding to the in-groove portion was measured using an atomic force microscope (AFM) after formation of the reflective layer, the groove width (corresponding to “InW” in FIG. 12, the same applies hereinafter) was 330 nm, and the groove depth ( 12 corresponds to “InD” in FIG. 12 and the same applies hereinafter), and the track pitch (P) of the in-groove portion was 0.64 μm.

Next, an ultraviolet curable resin was applied on the reflective layer in a thickness of 200 μm by spin coating, and then cured. Next, a transparent material (thickness 25 nm) mainly composed of SiO ₂ and In ₂ O ₃ , Fe ₃ O ₄ (3 nm), GeBi—O (30 nm), mainly composed of SiO ₂ and In ₂ O ₃ A recording layer was formed by laminating the layers in the order of transparent material (thickness 25 nm) by sputtering. Finally, an ultraviolet curable resin was applied on the recording layer to a thickness of 100 μm by spin coating, and then cured to form a cover layer (protective layer).

Subsequently, 1-7PP (Parity preserve / Prohibit repeated minimum transition length) is used for the recording layer of the optical recording medium manufactured as described above, using an optical disc drive unit “ODU-1000” manufactured by Pulstec Industrial Co., Ltd. ) Format data was recorded by the modulation method. At this time, the optical recording medium is rotated at a linear velocity of 9.84 m / s, and a laser beam (guide light) having a wavelength of 650 nm and an output of 0.3 mW is condensed on the in-groove portion, and tracking tracking control is performed. A laser beam (recording light) having a wavelength of 405 nm and an output of 20 mW was focused on a recording layer region corresponding to the in-groove portion to form a recording pit. Then, after forming recording pits (recording marks) in the region of the recording layer corresponding to the in-groove portion, track deviation was evaluated for the recording pits with laser light (reproducing light) having a wavelength of 405 nm and an output of 80 mW. The track deviation was evaluated based on the degree of deterioration of the reproduction signal. A measured value of SER (Symbol Error Rate) was used as an evaluation index, and the value of 1E-3 (1.0 × 10 ⁻³ ) was used as a criterion for quality.

As a result of the evaluation, the value of SER was 4.2E-4 (4.2 × 10 ⁻⁴ ), and a good result was obtained.

(Example 2)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 360 nm and the groove depth (InD) was 75 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 2.3E-4 (2.3 × 10 ⁻⁴ ), and a good result was obtained.

(Example 3)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 400 nm and the groove depth (InD) was 75 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 3.4E-4 (3.4 × 10 ⁻⁴ ), and a good result was obtained.

Example 4
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 330 nm and the groove depth (InD) was 80 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 2.5E-4 (2.5 × 10 ⁻⁴ ), and a good result was obtained.

(Example 5)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 360 nm and the groove depth (InD) was 80 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 1.9E-4 (1.9 × 10 ⁻⁴ ), and a good result was obtained.

(Example 6)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 400 nm and the groove depth (InD) was 80 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 2.0E-4 (2.0 × 10 ⁻⁴ ), and a good result was obtained.

(Example 7)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 330 nm and the groove depth (InD) was 85 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 5.6E-4 (5.6 × 10 ⁻⁴ ), and a good result was obtained.

(Example 8)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 360 nm and the groove depth (InD) was 85 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 4.1E-4 (4.1 × 10 ⁻⁴ ), and a good result was obtained.

Example 9
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 400 nm and the groove depth (InD) was 85 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 5.1E-4 (5.1 × 10 ⁻⁴ ), and a good result was obtained.

(Example 10)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 280 nm and the groove depth (InD) was 65 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 8.2E-4 (8.2 × 10 ⁻⁴ ), and a good result was obtained.

(Example 11)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 300 nm and the groove depth (InD) was 65 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 7.1E-4 (7.1 × 10 ⁻⁴ ), and a good result was obtained.

Example 12
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 330 nm and the groove depth (InD) was 65 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 6.4E-4 (6.4 × 10 ⁻⁴ ), and a good result was obtained.

(Example 13)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 360 nm and the groove depth (InD) was 65 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 4.7E-4 (4.7 × 10 ⁻⁴ ), and a good result was obtained.

(Example 14)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 400 nm and the groove depth (InD) was 65 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 5.5E-4 (5.5 × 10 ⁻⁴ ), and a good result was obtained.

(Example 15)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 430 nm and the groove depth (InD) was 65 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 8.9E-4 (8.9 × 10 ⁻⁴ ), and a good result was obtained.

(Example 16)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 280 nm and the groove depth (InD) was 75 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 7.7E-4 (7.7 × 10 ⁻⁴ ), and a good result was obtained.

(Example 17)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 300 nm and the groove depth (InD) was 75 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 5.5E-4 (5.5 × 10 ⁻⁴ ), and a good result was obtained.

(Example 18)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 430 nm and the groove depth (InD) was 75 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 7.4E-4 (7.4 × 10 ⁻⁴ ), and a good result was obtained.

(Example 19)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 280 nm and the groove depth (InD) was 80 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 6.0E-4 (6.0 × 10 ⁻⁴ ), and a good result was obtained.

(Example 20)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 300 nm and the groove depth (InD) was 80 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 3.1E-4 (3.1 × 10 ⁻⁴ ), and a good result was obtained.

(Example 21)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 430 nm and the groove depth (InD) was 80 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 7.7E-4 (7.7 × 10 ⁻⁴ ), and a good result was obtained.

(Example 22)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 280 nm and the groove depth (InD) was 85 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 7.0E-4 (7.0 × 10 ⁻⁴ ), and a good result was obtained.

(Example 23)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 300 nm and the groove depth (InD) was 85 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 6.1E-4 (6.1 × 10 ⁻⁴ ), and a good result was obtained.

(Example 24)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 430 nm and the groove depth (InD) was 85 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 5.3E-4 (5.3 × 10 ⁻⁴ ), and a good result was obtained.

(Example 25)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 280 nm and the groove depth (InD) was 90 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 9.0E-4 (9.0 × 10 ⁻⁴ ), and a good result was obtained.

(Example 26)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 300 nm and the groove depth (InD) was 90 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 8.1E-4 (8.1 × 10 ⁻⁴ ), and a good result was obtained.

(Example 27)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 330 nm and the groove depth (InD) was 90 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 5.6E-4 (5.6 × 10 ⁻⁴ ), and a good result was obtained.

(Example 28)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 360 nm and the groove depth (InD) was 90 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 5.5E-4 (5.5 × 10 ⁻⁴ ), and a good result was obtained.

(Example 29)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 400 nm and the groove depth (InD) was 90 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 6.3E-4 (6.3 × 10 ⁻⁴ ), and a good result was obtained.

(Example 30)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 430 nm and the groove depth (InD) was 90 nm. When this optical recording medium was measured for SER by the same evaluation method as in Example 1, the evaluation value was 6.9E-4 (6.9 × 10 ⁻⁴ ), and a good result was obtained.

(Comparative Example 1)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 260 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 3.2E-3 (3.2 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 2)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 280 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.9E-3 (1.9 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 3)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 300 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.6E-3 (1.6 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 4)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 330 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.1E-3 (1.1 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 5)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 360 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.1E-3 (1.1 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 6)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 400 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.3E-3 (1.3 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 7)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 430 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.5E-3 (1.5 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 8)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 450 nm and the groove depth (InD) was 60 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.7E-3 (1.7 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 9)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 260 nm and the groove depth (InD) was 65 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 2.3E-3 (2.3 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 10)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 450 nm and the groove depth (InD) was 65 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.3E-3 (1.3 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 11)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 260 nm and the groove depth (InD) was 75 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.9E-3 (1.9 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 12)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 450 nm and the groove depth (InD) was 75 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.3E-3 (1.3 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 13)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 260 nm and the groove depth (InD) was 80 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.4E-3 (1.4 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 14)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 450 nm and the groove depth (InD) was 80 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.2E-3 (1.2 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 15)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 260 nm and the groove depth (InD) was 85 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.8E-3 (1.8 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 16)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 450 nm and the groove depth (InD) was 85 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.2E-3 (1.2 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 17)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 260 nm and the groove depth (InD) was 90 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 2.2E-3 (2.2 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 18)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 450 nm and the groove depth (InD) was 90 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.1E-3 (1.1 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 19)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 260 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 2.5E-3 (2.5 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 20)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 280 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 2.5E-3 (2.5 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 21)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 300 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.7E-3 (1.7 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 22)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 330 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.2E-3 (1.2 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 23)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 360 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.1E-3 (1.1 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 24)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 400 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.1E-3 (1.1 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 25)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 430 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.2E-3 (1.2 × 10 ⁻³ ), and a result exceeding the standard was obtained.

(Comparative Example 26)
An optical recording medium was manufactured under the same conditions as in Example 1 except that the groove width (InW) of the in-groove portion was 450 nm and the groove depth (InD) was 100 nm. When SER was measured for this optical recording medium by the same evaluation method as in Example 1, the evaluation value was 1.5E-3 (1.5 × 10 ⁻³ ), and a result exceeding the standard was obtained.

The above results are summarized in Table 1. Table 1 shows the relationship between the groove width and depth of the in-groove portion and the SER evaluation value.

As shown in Table 1, according to Examples 1 to 30 that satisfy the conditions of 280 nm ≦ InW ≦ 430 nm and 65 nm ≦ InD ≦ 90 nm, the SER evaluation value is lower than the reference value (1E-3) (10 minus) 4th order). On the other hand, in Comparative Examples 1 to 26 that did not satisfy the above conditions, the SER evaluation value exceeded the reference value (1E-3). If the SER evaluation value exceeds 1E-3, error correction during reproduction becomes difficult and reproduction characteristics deteriorate. Therefore, according to the first to thirty-first embodiments, the tracking followability of the in-groove portion is high, and track deviation can be effectively suppressed.

In addition, according to Examples 1 to 9, 11 to 14, 16 to 24, and 27 to 30, a SER evaluation value of 8E-4 or less can be obtained. Therefore, a predetermined value with respect to the reference value (1E-3) is obtained. A margin can be secured and stable recording / reproduction characteristics can be obtained.

Furthermore, according to Examples 1 to 9 that satisfy the conditions of 330 nm ≦ InW ≦ 400 nm and 75 nm ≦ InD ≦ 85 nm, a SER evaluation value of 5.6E-4 or less can be obtained. Can be secured stably.

FIG. 16 shows the relationship between the groove width and depth of the in-groove portion at the wavelength of 650 nm of the guide light and the NPP characteristics, and is a diagram showing the magnitude of the NPP value with contour lines. The region surrounded by the rectangle S11 in the figure (280 nm ≦ InW ≦ 430 nm, 65 nm ≦ InD ≦ 90 nm) corresponds to Examples 1 to 30, and the region surrounded by the rectangle S12 in S11 (330 nm ≦ InW ≦ 400 nm, (75 nm ≦ InD ≦ 85 nm) indicates a region having a particularly high NPP value, and this range corresponds to Examples 1 to 9. As is apparent from Table 1 and FIG. 16, the higher the NPP value, the lower the SER evaluation value.

(Example 31)
As in Examples 1 to 30, a plurality of samples of optical recording media having different groove widths (InW) or depths (InD) of the in-groove portions were prepared, and laser light having a wavelength of 600 nm and an output of 0.3 mW was produced for each sample. (Guide light) was condensed on the in-groove portion, and the output value of the NPP signal acquired based on the diffracted light was measured. The result is shown in FIG.

In FIG. 17, the region surrounded by the rectangle S21 satisfies the conditions of 280 nm ≦ InW ≦ 430 nm and 55 nm ≦ InD ≦ 80 nm, the region surrounded by the rectangle S22 in S21 is 330 nm ≦ InW ≦ 400 nm, and The condition of 65 nm ≦ InD ≦ 75 nm is satisfied. The SER evaluation value in the region S21 was lower than 1E-3, as in Examples 1 to 30, and good results were obtained. The region S22 is a region having a particularly high NPP value in S21, and it has been confirmed that a SER evaluation value of 8E-4 or less can be obtained.

(Example 32)
Similar to Examples 1 to 30, a plurality of samples of optical recording media having different groove widths (InW) or depths (InD) of the in-groove portions were prepared, and laser light having a wavelength of 700 nm and an output of 0.3 mW was produced for each sample. (Guide light) was condensed on the in-groove portion, and the output value of the NPP signal acquired based on the diffracted light was measured. The result is shown in FIG.

In FIG. 18, the region surrounded by the rectangle S31 satisfies the conditions of 280 nm ≦ InW ≦ 430 nm and 75 nm ≦ InD ≦ 100 nm, the region surrounded by the rectangle S32 in S31 is 330 nm ≦ InW ≦ 400 nm, and The condition of 85 nm ≦ InD ≦ 95 nm is satisfied. The SER evaluation value in the region S31 was lower than 1E-3, as in Examples 1 to 30, and good results were obtained. The region surrounded by the rectangle S32 is a region having a particularly high NPP value in S31, and it has been confirmed that a SER evaluation value of 8E-4 or less can be obtained.

As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, in the range which does not deviate from the summary of this invention, a various change can be added.

For example, in the above embodiment, the guide layer separation type optical recording medium having a plurality of recording layers 113 has been described as an example. However, for example, the present invention is also applied to a guide layer separation type optical recording medium having a single recording layer. The invention is applicable.

In the above embodiment, the example in which the optical recording medium according to the present invention is driven by the optical recording system 1 shown in FIG. 1 is described. However, the optical recording system is not limited to the above example, The present invention can also be applied to an optical recording system.

Further, in the above embodiment, the guide track having a track pitch of 0.32 μm has been described as an example, but the track pitch is not limited to this, and an appropriate track according to the pitch between lands (or pitch between grooves). Pitch is applicable.

DESCRIPTION OF SYMBOLS 11 ... Multilayer optical disk 110 ... Base material 112 ... Guide layer 113 ... Recording layer 114 ... Intermediate layer 115 ... Protective layer 121 ... Guide track 121G ... On-groove part 121L ... In-groove part

Claims

A guide layer having a guide track including an in-groove portion and an on-groove portion;
Comprising one or more recording layers capable of recording information in areas corresponding to the in-groove part and the on-groove part,
The in-groove portion has a groove width of the in-groove portion (half value of the sum of the bottom width of the in-groove portion and the opening width of the in-groove portion) InW [nm], and the depth of the in-groove portion is InD [Nm], when the wavelength of the laser beam focused on the guide track is λ [nm],
280 ≦ InW ≦ 430,
(0.2λ−65) ≦ InD ≦ (0.2λ−40), and
600 ≦ λ ≦ 700
Guide layer separation type optical recording medium satisfying the above relationship.
The guide layer separation type optical recording medium according to claim 1,
The groove width InW [nm] of the in-groove portion is
330 ≦ InW ≦ 400
Guide layer separation type optical recording medium satisfying the above relationship.
The guide layer separation type optical recording medium according to claim 1 or 2,
The depth InD [nm] of the in-groove portion is
(0.2λ−55) ≦ InD ≦ (0.2λ−45)
Guide layer separation type optical recording medium satisfying the above relationship.
The guide layer separation type optical recording medium according to any one of claims 1 to 3,
The guide layer separation type optical recording medium, wherein the groove width of the in-groove portion is wider than the groove width of the on-groove portion (half the sum of the minimum width of the on-groove portion and the maximum width of the on-groove portion).