TW201435865A - Guide-layer separation type optical recording medium - Google Patents

Abstract

The invention is directed to a guide-layer separation type optical recording medium and achieves the enhancement of reproduction characteristics of information recording. In an embodiment of the invention, a guide-layer separation type optical recording medium 11 includes a guide layer 112 and a plurality of recording layers 113. The guide layer 112 has a guide track 121 including an in-groove part 121L and an on-groove part 121G. The recording layer 112 can record information on regions corresponding to the in-groove part 121L and the on-groove part 121G. The in-groove part 121L having a groove width (a half of the sum of a bottom width InWa and an opening width InWb) of InW[nm] and a depth of InD[nm] satisfies the relationship formulas of: 280 ≤ InW ≤ 430, (0.2 λ -65) ≤ InD ≤ (0.2 λ -40), 600 ≤ λ ≤ 700, wherein λ [nm] is the wavelength of a laser light focused on the guide track 121.

Description

Guide layer separated optical recording medium

The present invention relates to a guide layer separation type optical recording medium having a guide layer having a concavo-convex structure.

A disc such as a DVD (Digital Versatile Disk) or a Blu-ray Disc (registered trademark) is multi-layered for the purpose of increasing the capacity. With the multilayering of the recording layer, tracking control at the time of recording or reproduction of data on the recording layer is performed by providing a guiding layer different from the recording layer. (for example, Patent Documents 1, 2, etc.).

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 stacked in the thickness direction of the optical disk through an intermediate layer. The guide layer is designed with grooves and projections. When writing (recording) or reading (reproducing) information on the recording layer in this manner, tracking and control of the guide layer is performed using the laser for recording and reproducing and the laser for tracking having the same optical axis.

In the guide layer separation type optical recording medium, since the above-described guide layer and recording layer are respectively designed as different layers, high tracking traceability is required. For example, Patent Document 3 listed below proposes an optical recording medium drive device and an additional record in which the distance between the recorded position and the additionally recorded position is only a fixed number of tracks, and the recording can be additionally performed without destroying the already recorded information. method.

When a laser of a blue wavelength is used on the recording layer of the separation layer type optical recording medium, for example, when recording is performed at a track pitch of 0.32 μm, the guide layer is also required. It is necessary to have a guide track with a track pitch of 0.32 μm. For example, in an optical recording system in which a blue wavelength laser is collected on a recording layer for recording or reproduction while tracking a guide track by a laser of a red wavelength, a guide track having a track pitch of 0.32 μm is desired to be realized by a concave-convex structure. In this case, each of the projections and grooves must be utilized as a guide rail.

In the following description, in the guide rail, the track close to the laser light source is called "groove" or "on-Groove", and the track away from the laser light source is called "bump" or "inside groove" (In-Groove) )unit".

[Previous Technical Literature] [Patent Document]

Patent Document 1 Japanese Patent Laid-Open Publication No. 2003-59092

Patent Document 2 Japanese Patent Laid-Open Publication No. 2008-192246

Patent Document 3, JP-A-2010-40093

The diffracted properties of the laser are different due to the different geometry of the bumps and grooves. For example, when the spot diameter of the laser is small in the range of the inner groove portion, the diffraction of the inner groove portion is less than that of the front groove portion. As a result, the tracking performance of the inner groove portion is lowered, and the quality of the track of the recording pit formed on the region corresponding to the inner groove portion on the recording layer is lowered. Further, in the case where the reproduction light is tracked by the recording track formed on the recording layer, it is difficult to reproduce the recording track corresponding to the inner groove portion with high precision.

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

In order to achieve the above object, a guide layer separation type optical recording medium according to an embodiment of the present invention includes a guide layer and one or more recording layers.

The guiding layer includes a guide rail including an inner groove portion and a front groove portion.

The one or more recording layers can record information on a region corresponding to the inner groove portion and the front groove portion.

The groove width of the inner groove portion (half the sum of the base width of the inner groove portion and the opening width of the inner groove portion) is InW [nm], and the depth of the inner groove portion is InD [nm], and the laser beam is collected on the guide rail. When the wavelength is λ [nm], the inner groove portion satisfies the following relationship: 280 ≦ InW ≦ 430, (0.2 λ - 65) ≦ InD ≦ (0.2 λ - 40), and 600 ≦ λ ≦ 700.

According to the above-described guide layer separation type optical recording medium, the diffraction characteristics of the laser light in the inner groove portion are high, and the tracking property of the In-Groove portion is improved. Thus, it is possible to form a high-quality recording track in the recording layer, and at the same time, it is possible to improve the recording track reproduction characteristics.

The groove width InW [nm] of the inner groove portion may satisfy the condition of 330 ≦ InW ≦ 400.

Further, the depth InD [nm] of the inner groove portion may satisfy the condition of (0.2λ - 55) ≦ InD ≦ (0.2λ - 45).

This ensures that the stability can correct the wrong SER (Symbol Error Rate) evaluation value (below 1E-3).

The groove width of the inner groove portion may be wider than the groove width of the front groove portion (half the sum of the minimum width of the front groove portion and the maximum width of the front groove portion).

Thus, it is possible to ensure good diffraction characteristics of the laser light in the inner groove portion, and to generate a tracking error signal with high accuracy.

According to the guide layer separation type optical recording medium of the present invention, it is possible to improve the recording and reproducing characteristics of information.

1‧‧‧ optical recording device

10‧‧‧Disc box

11‧‧‧Multilayer CD

20‧‧‧Disc transmission mechanism

30‧‧‧Drive unit

31‧‧‧Disc drive

32‧‧‧ Optical pickup department

33‧‧‧1st light source

34‧‧‧1st collimating lens

35‧‧‧1st polarized beam splitter

36‧‧‧1st relay lens

37‧‧‧2nd collimating lens

38‧‧‧Synthetic prism

39‧‧‧1/4 wavelength plate

40‧‧‧RAID controller

50‧‧‧Host equipment

51‧‧‧CPU

52‧‧‧ memory

53‧‧‧ drive

54‧‧‧Disc transmission mechanism

56‧‧‧System Bus

60‧‧‧ objective lens

61‧‧‧1st receiving lens

62‧‧‧1st light receiving department

63‧‧‧2nd light source

64‧‧‧3rd collimating lens

65‧‧‧2nd polarization beam splitter

66‧‧‧2nd relay lens

67‧‧‧4th collimating lens

68‧‧‧2nd receiving lens

69‧‧‧2nd light receiving department

70‧‧‧Tracking actuator

71‧‧‧ Tracking Control Department

72‧‧‧Data Modulation Department

73‧‧‧1st light source drive unit

74‧‧‧2nd light source drive unit

75‧‧‧ Equalizer

76‧‧‧Data Regeneration Department

77‧‧‧Focus Control Department

79‧‧‧focus actuator

80‧‧‧1st relay lens actuator

81‧‧‧2nd relay lens actuator

82‧‧‧ Tracking error generation unit

83‧‧‧ Controller

84‧‧‧1st relay control unit

85‧‧‧2nd relay control unit

86‧‧‧ Focus Error Generation Department

87‧‧‧ drive optical disc motor

101‧‧‧ openings

110‧‧‧Substrate

111‧‧‧

112‧‧‧Guiding layer

113‧‧‧recording layer

114‧‧‧Intermediate

115‧‧‧Protective layer

120‧‧‧Reflective film

121‧‧‧rails

121G‧‧‧ front ditch

121L‧‧‧Internal Department

121S‧‧‧ side wall

221‧‧‧rail

221G‧‧‧ front ditch

221L‧‧‧Internal Department

R1‧‧‧Reproduced light

R2‧‧‧ Guide light

S11, S12, S21, S22, S31, S32‧‧‧ rectangle

1 is a schematic view of an optical recording apparatus to which an embodiment of the present invention is applied.

Fig. 2 is a view showing the configuration of a storage mode of a plurality of optical recording media among the optical disk cartridge and the optical recording device of Fig. 1;

Fig. 3 is a view showing the configuration of an optical disk case, an optical recording medium, and a drive unit in the optical recording apparatus of Fig. 1.

4 is a cross-sectional view showing the configuration of a guide layer separation type optical recording medium according to an embodiment of the present invention.

Fig. 5 is an enlarged view of an important part of the optical recording medium of Fig. 4.

Fig. 6 is a view showing the configuration of a double spiral track of a guide layer in the optical recording medium of Fig. 4.

Fig. 7 is a view showing a configuration in which the positions of the guide layer and the recording layer in the radial direction are distinguished by the field in the optical recording medium of Fig. 4;

Fig. 8 is a view showing the configuration of a disc drive in the optical recording apparatus of Fig. 1.

Fig. 9 is a view showing the recording sequence of the data track by the optical disk drive of Fig. 8.

Fig. 10 is a view showing the recording sequence of the data track by the optical disk drive of Fig. 8.

Fig. 11 is a schematic view showing an irradiation form of the guiding light on the guiding layer in the optical recording medium of Fig. 4;

Fig. 12 is a schematic view showing a specific structure of an inner groove portion designed on a guide layer in the optical recording medium of Fig. 4;

Fig. 13 is a test result showing the wavelength dependence of the NPP value of the diffracted light with respect to the groove width of the inner groove portion of Fig. 12 .

Fig. 14 is a test result showing the wavelength dependence of the NPP value of the diffracted light with respect to the groove depth of the inner groove portion of Fig. 12 .

Fig. 15 is a view showing the groove depth when the wavelength band NPP of the guided light is the largest in Fig. 14;

Fig. 16 is a view showing the relationship between the groove width and the depth of the inner groove portion and the NPP characteristics when the wavelength of the guiding light is 650 nm.

Fig. 17 is a schematic view showing the relationship between the groove width and the depth of the inner groove portion and the NPP characteristics when the wavelength of the guiding light is 600 nm.

Fig. 18 is a schematic view showing the relationship between the groove width and the depth of the inner groove portion and the NPP characteristics when the wavelength of the guiding light is 700 nm.

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

1 is a schematic view of an optical recording apparatus according to an embodiment of the present invention.

Fig. 1 is a schematic view showing the overall configuration of an optical recording apparatus.

The optical recording apparatus 1 includes an optical disk cartridge 10, a optical disk transfer mechanism 20, a drive unit 30, a RAID controller 40, and a host device 50. The details are explained below.

(disc box)

The optical disk cartridge 10 is a unit that can detachably house a plurality of multilayer optical disks 11 (guide layer separation type optical recording media).

FIG. 2 is a schematic view showing the configuration of a plurality of optical discs 11 in the optical disc case 10 and the storage method.

The storage mode of the plurality of multilayer optical discs 11 in the optical disc case 10 is assumed to be parallel lamination, vertical alignment, or the like. In any case, in order to smoothly perform the pick-and-place operation of the multilayer optical disc 11 in the optical disc case 10, a certain gap is tended to be provided between the adjacent multi-layer optical discs 11. The shape of the optical disk cartridge 10 is assumed to be, for example, a rectangular parallelepiped shape, a cylindrical shape, or the like from the viewpoints of the processing capability of the user, the storage efficiency of the multilayer optical disk 11, and the like. In the example of Fig. 2, a disk case 10 having a rectangular parallelepiped shape in which a plurality of multilayer optical disks 11 are stacked in parallel is used.

3 is a schematic diagram showing the structure of the optical disc case 10, the multi-layer optical disc 11 and the driving unit 30. Figure.

The optical disc case 10 is provided with an opening 101 for accommodating the multilayer optical disc 11 and a door (not shown) for opening and closing the opening 101 on at least one side surface. The operation of the door and the optical disc transport mechanism 20 to take and place the multi-layer optical disc 11 from the optical disc case 10 is linked and opened together, and at the other time, it is in a closed state. The plurality of multilayer optical discs 11 accommodated in the optical disc case 10 are taken out by the optical disc transport mechanism 20, and are selectively transported (loaded) by a plurality of optical disc drives 31 in the drive unit 30.

Further, the configuration of the optical disk cartridge 10 in the present invention is not limited to the configuration shown in FIG. The shape of the optical disk cartridge 10, the number and position of the openings, the presence or absence of the door, the storage mode of the plurality of multilayer optical disks 11, and the like can be variously modified.

(multilayer disc 11)

The multilayer optical disc 11 accommodated in the optical disc case 10 has a guide layer and a recording layer separated from each other to form a different layer, which is a "guide layer separation type multilayer optical disc".

4 and 5 are cross-sectional views showing the configuration of the multilayer optical disk 11 of the layer-separating type optical recording medium.

The multilayer optical disc 11 shown in FIG. 4 includes a guide layer 112 and a plurality of recording layers 113. In the example of the multilayer optical disc 11 of the same figure, the number of layers of the recording layer 113 is "4". An intermediate layer 114 having light transparency is interposed between the guiding layer 112 and the recording layer 113 closest thereto and between the adjacent recording layers 113, respectively. These layers are in accordance with the recording and reproducing light R1 in the optical pickup unit 32, the guiding light R2 on the incident side, the protective layer 115, the recording layer 113 (R3), the intermediate layer 114, the recording layer 113 (R2), the intermediate layer 114, and the recording. The sequential lamination of the layer 113 (R1), the intermediate layer 114, the recording layer 113 (R0), the intermediate layer 114, and the guiding layer 112 is arranged.

The guide layer 112 shown in FIG. 5 includes a translucent plastic base material 110 such as a disk-shaped polycarbonate having a spiral concavo-convex portion 111, and a concave-convex shape of the uneven portion 111 covering the uneven portion 111. A laminated structure of the reflective film 120. Substrate 110, Typically, the molding die is formed by a molding die, and the reflecting film 120 is made of, for example, a sputtering film of a metal material having a high reflectance to red laser such as silver (Ag) or an alloy thereof. The thickness of the substrate 110 is not particularly limited and may be, for example, 0.6 mm to 1.2 mm, and is 1.1 mm in the present embodiment. The thickness of the reflective film 120 is also not particularly limited, and may be, for example, 20 nm to 100 nm, and is 60 nm in the present embodiment.

As shown in FIGS. 5 and 6, the uneven structure rail 121 is spirally formed on the surface of the guide layer 112 on the side opposite to the recording layer 113. The protrusions are formed between the grooves, and the grooves are formed between the protrusions. In the following description, in the guide rail 121, a track close to the laser light source (optical pickup unit 32) is referred to as a "groove" or an "on-Groove portion", and a track away from the laser light source is referred to as a "convex". "" or "In-Groove".

The guide rail 121 is composed of a guide rail (inner groove portion 121L) formed by a projection and a guide rail (front groove portion 121G) formed by a groove, that is, a "double spiral track". In the present embodiment, the inner groove portion 121L and the front groove portion 121G are formed in a continuous spiral shape from the inner circumferential side to the outer circumferential side of the multilayer optical disk 11, but are not limited thereto. For example, the inner groove portion 121L and the front groove portion 121G may be formed in a continuous spiral shape by changing positions from the inner peripheral side to the outer peripheral side of the multilayer optical disk 11 at a predetermined cycle (for example, every week).

The inner groove portion 121L is surrounded by a pair of side walls 121S that form a boundary of the front groove portion 121G. The side wall 121S, typically formed by a tapered surface, may also be formed by a face that is perpendicular to the surface of the substrate 110. The taper angle of the side wall 121S is not particularly limited, and is appropriately set in accordance with the draft angle of the stamper and the height of the unevenness of the uneven portion 111, the thickness of the reflective film 120, and the like.

On the guide rail 121, physical address information is formed due to jitter or pit rows of the side wall surface. The inner groove portion 121L and the front groove portion 121G are formed, for example, by a gauge (0.64 μm) corresponding to a red laser for recording and reproduction of a DVD (Digital Versatile Disk). The average spacing between the protrusions and the grooves is 0.32 μm, which is the gauge of the guide rail 121. quite. Later, the red laser's laser is called "guide light."

The optical recording apparatus 1 of the present embodiment is respectively subjected to, for example, a push-pull method (PP: Push-Pull) and a differential push-pull (DPP), three beams, on the projections and grooves of the guide rail 121. Law and so on for tracking control. Since the tracking control is performed on the projections and the grooves of the guide rails 121, the recording of the information of the recording layer 113 can be performed at a track pitch of 0.32 μm.

The configuration of the guide rail 121 will be described later.

The recording layer 113 is a layer for performing information recording on, for example, a track pitch (0.32 μm) corresponding to a blue laser for recording and reproducing of a Blu-ray disc (registered trademark). Later, this blue laser is called "recording reproduction light" or "recording light".

The recording layer 113 is composed of, for example, a light absorbing layer, a reflective layer, and the like. As the light absorbing layer, an organic dye such as a cyan dye or an azo dye or an inorganic oxidized material such as Si, Cu, Sb, Te, Ge, Fe, or Bi is used. After the recording light is irradiated onto the target recording layer 113 on the multilayer optical disk 11, the reflectance of the field in which the recording light is irradiated changes, and in the field where the reflectance changes, the information is recorded on the recording layer 113 by forming the recording mark. The thickness of the recording layer 113 is not particularly limited, and is, for example, 10 nm to 200 nm, and in the present embodiment, it is 83 nm.

The distance X between the guiding layer 112 and the recording layer 113 (R0) closest to the guiding layer 112 is not particularly limited, and can be set to an appropriate value. In the present embodiment, the distance X is set to 25 μm or more, so that the crosstalk of the guided light irradiated on the guiding layer 112 and the recording and reproducing light irradiated on the recording layer 113 (R0) can be prevented, and the guiding layer 112 can be improved (especially inside). Traceability of the groove portion 121L).

Further, the tracking control at the time of recording information on the recording layer 113 and the acquisition of the physical address and the reference clock are performed by the guide rail 121 of the guide layer 112, so that the guide layer 121 composed of the projections and the grooves is not required on the recording layer 113. Therefore, the surface of the recording layer 113 is flat.

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

Fig. 7 is a schematic view showing the configuration of the field in accordance with the position of the guide layer 112 and the recording layer 113 in the radial direction in the multilayer optical disk 11.

The guiding layer 112 and the recording layer 113 are divided into a lead-in area, a data area, and a lead-out area from the inner peripheral side at the position in the radial direction.

On the lead-in area of the guide layer 112, the management information inherent to the multilayer optical disc 11 is previously recorded by the jitter of the guide rail or the pit row designed on the groove and the groove.

The management information inherent in the multilayer optical disc 11, for example, includes the number of recording layers, the recording mode, the recording line speed, the laser power during recording and reproduction, the recommended information of the laser driving pulse waveform, the position information of the data area, and the OPC area. Location information, etc. The OPC area is designed, for example, on the inner peripheral side of the lead-in area.

On the data area of the guiding layer 112, the physical address information of the data area is recorded in advance by the jitter of the guide rail 121 or the pre-pit rows designed on the protrusions and the grooves.

And the information on the lead-out area of the guiding layer 112 and the information recorded in the lead-in area can also be recorded in advance by the shaking of the guide rail 121 or the pre-pit rows designed on the protrusions and the grooves.

The lead-in area of the recording layer 113 is a field in which the management information for recording and reproduction on the recording layer 113 is recorded by the recording mark. The management information for recording and reproduction on the recording layer 113 includes layer information such as layer numbers assigned on the recording layer 113, alternate management information on alternate processing of defective areas, and recording time determined by OPC processing (correction processing). Recording condition data such as laser power, position information of the recording completion area, and the like. Among them, at least the layer information is, for example, the number of the optical discs 11 according to the number of users According to the record, the information recorded by the record mark on the previous record layer 113 actually used.

(disc transfer mechanism)

The optical disk transfer mechanism 20 is a mechanism for taking out the intended multilayer optical disk 11 from the optical disk case 10 into the optical disk drive 31 in the drive unit 30, or conversely, returning the multilayer optical disk 11 ejected from the optical disk drive 31 to the optical disk case 10.

The optical disc transport mechanism 20, for example, is capable of continuously taking out a plurality of multi-layer optical discs 11 simultaneously or sequentially from the optical disc case 10, and respectively loading them into a plurality of optical disc drives 31 in the drive unit 30, preferably provided to be independently movable. A plurality of transport mechanisms.

(Drive unit)

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

(The composition of the disc drive)

Fig. 8 is a view showing the configuration of the optical disk drive 31 of the optical recording apparatus.

The optical disc drive 31 includes an optical pickup unit 32. The optical pickup unit 32 includes a recording and reproducing optical system corresponding to the recording and reproducing light and a guiding optical system corresponding to the guided light.

The recording/reproducing optical system includes a first light source 33, a first collimator lens 34, a first polarization beam splitter 35, a first relay lens 36, a second collimator lens 37, a synthesizing prism 38, and a quarter-wave plate 39. The objective lens 60, the first receiving lens 61, the first light receiving portion 62, and the like. Here, the combining prism 38, the 1⁄4 wavelength plate 39, and the objective lens 60 belong to both the recording and reproducing optical system and a guiding optical system to be described later.

The first light source 33 includes a laser diode that emits blue laser light as the recording and reproducing light R1. The recording and reproducing light R1 emitted from the first light source 33 passes through the first collimating lens 34. The parallel light passes through the first polarization beam splitter 35, the first relay lens 36, and the second collimator lens 37, and enters the combining prism 38. The combining prism 38 combines the recording and reproducing light R1 incident from the second collimating lens 37 and the guiding light R2 incident from the third collimating lens belonging to the guiding optical system, which will be described later, to each other, and passes through the 1/4 wavelength. The plate 39 is incident on the objective lens 60. On the objective lens 60, the incident recording and reproducing light is condensed on the recording layer 113 of the objective of the multilayer optical disk 11.

The recording and reproducing light (return light) reflected by the recording layer 113 is incident on the combining prism 38 through the objective lens 60 and the 1⁄4 wavelength plate 39, passes through the combining prism 38 from the incident direction, passes through the second collimating lens 37, and is first. The lens 36 returns to the first polarization beam splitter 35. 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 enters the first light receiving portion 62 through the first receiving lens 61.

The first light receiving unit 62 is configured, for example, by a light receiving element that is divided into four in the radial direction and the tangential direction of the optical disk, and outputs voltage signals of different levels according to the receiving intensity of each divided receiving surface.

The guiding optical system includes a second light source 63, a third collimating lens 64, a second polarizing beam splitter 65, a second relay lens 66, a fourth collimating lens 67, a synthesizing prism 38, and a quarter-wave plate. 39. Objective lens 60, second receiving lens 68, second light receiving portion 69, and the like.

The second light source 63 emits the guide light R2 of the red laser. The guide light R2 emitted from the second light source 63 is parallel light by the third collimator lens 64, passes through the second polarization beam splitter 65, the second relay lens 66, and the fourth collimator lens 67, and is incident and combined. Prism 38. As described above, the guided light R2 incident on the combining prism 38 is combined with the recording and reproducing light R1 incident on the second collimating lens 37 of the recording and reproducing optical system from the combining prism 38, and passes through the 1/4 wavelength plate. 39 is incident on the objective lens 60. The guiding light R2 incident on the objective lens 60 is condensed on the guiding layer 112 of the multilayer optical disk 11.

The guiding light R2 (return light) reflected by the guiding layer 112 is incident on the combining prism 38 through the objective lens 60 and the 1⁄4 wavelength plate 39, and is reflected at an angle of about 90 degrees on the combining prism 38, and passes through the 4th collimating lens. The 67 and second relay lenses 66 return to the second polarization beam splitter 65. The second polarization beam splitter 65 reflects the return light of the guided light R2 from the second relay lens 66 at an angle of about 90 degrees, and enters the second light receiving portion 69 through the second receiving lens 68.

The second light receiving unit 69 is configured, for example, by a light receiving element that is divided into four in the radial direction and the tangential direction of the optical disk. The second light receiving unit 69 outputs a corresponding voltage signal based on the reception intensity of each divided receiving surface.

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

In the optical pickup unit 32, in order to change the recording layer 113 on which the recording and reproducing light is irradiated, the first relay lens actuator 80 that moves the first relay lens 36 in the optical axis direction is provided, and the guide light R2 is placed on the guiding layer. The 112 is condensed, and a second relay lens actuator 81 that moves the second relay lens 66 in the optical axis direction is provided.

Further, the optical pickup unit 32 is provided with a tilt actuator or the like (not shown) for adjusting the inclination of the objective lens 60 in the radial direction and the tangential direction on the recording surface of the multilayer optical disc 11.

The above is the description of the optical pickup unit 32.

The optical disk drive 31 includes the optical pickup unit 32, the tracking control unit 71, the data modulation unit 72, the first light source drive unit 73, the second light source drive unit 74, the equalizer 75, the data reproduction unit 76, and the focus control unit. 77. The tracking error generation unit 82, the controller 83, the first relay control unit 84, the second relay control unit 85, and the focus error generation unit 86. Further, the optical disc drive 31 further includes a disc motor that drives the optical disc motor 87. The drive unit and the feed mechanism that transports the optical pickup unit 32 in the radial direction of the multilayer optical disk 11 and the pickup upper and lower transfer mechanism that transmits the optical pickup unit 32 to the optical axis direction of the objective lens 60 are used. Not shown on these figures.

The data modulation unit 72 modulates the data for recording supplied from the controller 83, and supplies the modulated signal to the first light source driving unit 73.

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

The equalizer 75 performs equalization processing such as PRML (Partial Response Maximum Like) on the reproduced RF signal of the first light receiving unit 62 to generate a binary signal.

The data reproducing unit 76 demodulates the data by the binary signal output from the equalizer 75, performs decoding processing such as error correction using the demodulated data, and generates reproduced data, which is supplied to the controller 83.

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

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

The focus error generation unit 86 generates a focus error signal based on the output of the first light receiving unit 62, for example, by an astigmatic focus error detection method or the like.

The focus control unit 77 controls the focus actuator 79 based on the focus error signal to move the objective lens 60 in the optical axis direction and perform focus control.

The first relay control unit 84 controls the first relay lens driver 80 in order to replace the recording layer to be recorded.

The second relay control unit 85 controls the second relay lens driver 81 to guide the light R2 on the guide layer 112 (the guide rail 121).

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

A plurality of the above-described optical disk drives 31 are mounted on the drive unit 30, and can be independently controlled, and information can be simultaneously recorded and reproduced on the loaded multilayer optical disk 11.

[RAID controller]

The RAID (Redundant Arrays of Independent Disks) controller 40, for recording commands to the host device 50, and the like, multi-record data or stripe the recorded data on one or more optical disc drives 31 in the drive unit 30 to perform RAID. control. The controller 83 of each of the optical disk drives 31, to which the recording or reproducing command has been issued by the RAID controller 40, controls the recording and reproduction of data on the multilayer optical disk 11.

[host device]

The host device 50 is a device that controls the uppermost layer of the optical recording apparatus 1. The host device 50 can also be a personal computer. The host device 50 creates or prepares data for recording, and supplies the RAID controller 40 with a record command for the data for recording. Further, the host device 50 provides a read command including the file name specified by the user to the RAID controller 40, and the data of the file name is obtained by the RAID controller 40 as a response.

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

The CPU 51 performs arithmetic processing for executing the program stored in the memory 52, and controls information exchange with each unit via the system bus 56.

The memory 52 is a main memory that stores programs, calculation results, and the like executed in the CPU 51.

The drive I/F 53, is an interface that communicates with a plurality of optical disc drives 31 through the RAID controller 40.

The optical disk transfer mechanism I/F 54, is an interface that communicates with the optical disk transfer mechanism 20.

[Example of Operation of Optical Recording Apparatus]

Hereinafter, the control in the case where the multilayer optical disc 11 is recorded on one or more optical disc drives 31 in the drive unit 30 of the optical recording apparatus 1 will be described.

The data recording commands are respectively sent from the host device 50 to the controller 83 of one or more of the optical disk drives 31 in the drive unit 30 via the RAID controller 40. The operation of each of the optical disc drives 31 at the time of receiving the recording command is the same, and the operation of the optical disc drive 31 of one of them will be described here.

The controller 83 of the optical disc drive 31 controls the feed not shown on the drawing in order to move the optical pickup unit 32 to the recording area of the recording layer 113 of the optical disc 11 at a position corresponding to the innermost circumference of the area where the data is not recorded. At the same time as the mechanism, the optical disk drive unit not shown in the control chart is used to drive the optical disk 11 at a suitable speed in a CLV mode or a CAV mode.

In the recording layer 113 for the purpose of the multilayer optical disk 11, the controller 83 focuses on the recording light from the objective lens 60 of the optical pickup unit 32, and controls the position of the first relay lens 36 of the optical pickup unit 32 in the optical axis direction. In the guide layer 112 of the optical disk 11, the guided light from the objective lens 60 of the optical pickup unit 32 is focused, and the position of the second relay lens 66 of the optical pickup unit 32 in the optical axis direction is controlled.

The controller 83 of the optical disk drive 31 supplies the data for recording transferred from the host device 50 via the RAID controller 40 to the data modulation unit 72. The data modulation unit 72 generates a recording signal by performing modulation of data for recording and addition of an error correction code, and supplies it to the first light source driving unit 73. First light source driving unit 73 for recording Based on the signal, a drive pulse of the first light source 33 is generated and supplied 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 in order to drive the second light source 63. Thus, the recording light from the optical pickup unit 32 starts the recording of the data on the recording layer 113. That is, on the recording layer 113 for the purpose of the optical disk 11, recording of data is started by the CLV method or the CAV method from the inner circumference to the outer circumference.

Here, the tracking control at the time of data recording will be described.

The tracking error generation unit 82 generates an NPP (Normalized Push-Pull) signal (tracking error signal) based on the output of the second light receiving unit 69, for example, by the PP method (push-pull method). The NPP signal is a signal that is normalized by dividing the push-pull voltage by the RF signal voltage. In addition to the push-pull method, a tracking error signal can be generated by, for example, DPP (Differential Push-Pull Method) or a three-beam method.

The tracking control unit 71 inputs a tracking error signal, and supplies a tracking drive signal to the control tracking actuator 70 to move the objective lens 60 in a direction perpendicular to the optical axis (the radial direction of the optical disk) to perform tracking control.

The tracking control at the time of recording is performed on the inner groove portion 121L and the front groove portion 121G of the guide rail 121 which are designed on the guide layer 112 of the multilayer optical disk 11 by using the guide rail 121 on one side.

Further, the tracking control at the time of data reproduction is performed using the data track formed by the recording layer 113 of the multilayer optical disk 11 so as to record the columns of the recording marks.

9 and 10 are views showing the recording sequence of the data track by the optical disk drive 31 according to the present embodiment.

For example, the optical disk drive 31 of the present embodiment records the tracking according to the tracking control for the inner groove portion 121L (see FIG. 9), and after all the inner groove portions 121L are recorded by the tracking control, the previous groove portion 121G is replaced with the previous groove portion 121G as the target tracking control. Recording is performed (refer to Figure 10). The details are described below.

Fig. 9 is a view showing an arbitrary recording layer for the multilayer optical disk 11 by using the inner groove portion 121L. Rx is a schematic view in which the state continuously performed in the order of L1, L2, and L3 is recorded from the inner peripheral side to the outer peripheral side of the multilayer optical disc 11.

The upper half of the figure is a view of the multilayer optical disc 11 seen in a direction perpendicular to the optical axis direction of the objective lens 60, and the lower half is an arbitrary recording layer Rx of the multilayer optical disc 11 as seen from the optical axis direction of the objective lens 60. view.

L0-L4 denotes the inner groove portion 121L, and G0-G4 denotes the front groove portion 121G. Further, the inner groove portion 121L is actually one continuous track, and the front groove portion 121G is also the same. It is to be noted that the rail portion having a different position on the radius of the disk is marked as, for example, "inner groove portion (L0)" and "front groove portion (G0)".

In the optical disk drive 31 of the present embodiment, recording is performed by tracking control of the inner groove portion 121L, and the recording marks M on the arbitrary recording layer Rx of the multilayer optical disk 11 are recorded at intervals of 0.64 μm.

[Multilayer Disc of the Present Embodiment]

Next, the multilayer optical disc 11 of the present embodiment will be described.

In general, in the guide layer separation type optical recording medium, the inner groove portion and the front groove portion of the guide layer have different diffraction characteristics of the laser (guide light) for tracking control due to their different geometrical shapes. For example, if the spot diameter of the laser (for example, 1.1 μm at a wavelength of 650 nm) is small, the diffraction of the inner groove portion is less than that of the front groove portion, and the tracking becomes slippery. The scan is easy to shift.

For example, FIG. 11 shows a mode in which the inner groove portion 221L and the front groove portion 221G of the guide rail 221 guide the light GL to be irradiated. The groove width of the inner groove portion 221L is narrow with respect to the spot diameter of the guide light GL. The front groove portion 221G faces the optical pickup (lower side in the drawing), the protruding groove (groove), and the groove (protrusion) which is bulged on both sides of the center, and the guide light GL is irradiated, so that the diffraction limit is hard to reach. On the other hand, the inner groove portion 221L illuminates the guide light GL on the projections and the grooves on both sides, and the guide light GL hardly enters the projection, making it difficult to obtain diffraction. Such a phenomenon depends on the wavelength of the guiding light GL, and the wavelength of the guiding light GL The longer the more significant.

As a result of the above problem, the C/N (Carrier to Noise Ratio) of the NPP signal is deteriorated due to insufficient diffraction, and the tracking property of the inner groove portion is lowered, so that a region corresponding to the inner groove portion on the recording layer is formed. The problem of the track quality of the pit (record mark) is reduced. Further, in the case where the reproduction light is tracked based on the recording track formed on the recording layer, it is difficult to reproduce the recording track corresponding to the inner groove portion with good precision.

In order to solve the above problems, the inventors of the present invention have separately explored the groove width and depth of the inner groove portion 121L capable of suppressing the deterioration of the C/N of the NPP signal. Here, as shown in FIG. 11, the groove width of the inner groove portion 121L on the guide layer 112 is InW [nm], and the depth of the inner groove portion 121L is InD [nm]. The groove width InW is half ((InWa+InWb)/2) of the sum of the bottom surface width InWa of the inner groove portion 121L and the opening width InWb of the inner groove portion 121L.

In Fig. 11, "P" is the gauge of the inner groove portion 121L (or the front groove portion 121G), which is 0.64 μm here. Since the inner groove portion 121L and the front groove portion 121G have the function of the guide rails, the total gauge distance of the guide rails 121 as the projection/groove structure is 0.32 μm (P/2).

Further, in the present embodiment, as shown in FIG. 11, the groove width of the front groove portion 121G is OnW [nm]. The groove width OnW is defined as a half of the sum of the minimum width (width of the protruding end portion) OnWa of the front groove portion 121G and the maximum width (width of the base portion) OnWb of the front groove portion 121G ((OnWa+OnWb)/2). Thus, the sum of the groove width InW of the inner groove portion 121L and the groove width OnW of the front groove portion 121G coincides with the gauge distance P of the inner groove portion 121L (or the front groove portion 121G).

The depth (height) of the front groove portion 121G is the same as the depth (InD) of the inner groove portion 121L.

FIG. 13 is an experimental result showing the wavelength dependence of the guiding light of the groove width InW and NPP characteristics of the inner groove portion 121L. As shown in the figure, the larger the wavelength of the guided light, the NPP characteristics are Low tendency. Further, it was confirmed that the groove width InW of the inner groove portion 121L having the largest NPP characteristics was 350 nm at any wavelength (600 nm, 650 nm, and 700 nm).

On the other hand, FIG. 14 is an experimental result showing the wavelength dependence of the guiding light of the depth InD and NPP characteristics of the inner groove portion 121L. As shown in the figure, the maximum value of NPP in each wavelength band is almost constant. Further, the depth of the inner groove portion 121L having the largest NPP characteristic becomes larger as the wavelength of the guiding light becomes larger. Fig. 15 is a view showing the groove depth InD of the maximum NPP with respect to each wavelength (λ) of the guided light. As shown in the figure, it was confirmed that the wavelength and the groove depth InD approximate a linear function (y = 0.2 x - 50).

From the viewpoint of ensuring high-accuracy tracking and traceability, the value of NPP tends to be high, and practically, it tends to reproduce the evaluation index of the recording pit (recording mark) formed on the recording track of the recording layer Rx corresponding to the inner groove portion ( SER:Symbol Error Rate) is suppressed to the order of magnitude of negative 4th power of 10 (for example, 9.9×10 ^-4 (9.9E-4)). The groove width InW [nm] and the depth InD [nm] of the inner groove portion 121L satisfying such conditions are defined by the following formulas (1) to (3).

280≦InW≦430...(1)

(0.2λ-65)≦InD≦(0.2λ-40)...(2)

600≦ λ ≦700...(3)

Here, λ[nm] represents the laser light collected on the guide rail 121, that is, the wavelength of the guided light.

When the groove width InW of the inner groove portion 121L is less than 280 nm, the diffraction of the guiding light on the inner groove portion 121L is insufficient, and the C/N deterioration of the NPP signal is unavoidable. On the other hand, when the groove width InW exceeds 430 nm, the groove width (OnW) of the upper groove portion 121G of the gauge P (0.64 μm) of the inner groove portion 121L is too narrow, so that the tracking traceability of the groove portion 121G is lowered. Inevitable.

Further, when the depth InD of the inner groove portion 121L is less than (0.2λ-65) nm, the difference between the diffraction characteristic on the inner groove portion 121L and the diffraction characteristic on the front groove portion 121G becomes Small, resulting in reduced traceability. On the other hand, when the depth InD of the inner groove portion 121L exceeds (0.2λ - 40) nm, the diffraction of the guiding light on the inner groove portion 121L is insufficient, and the C/N deterioration of the NPP signal is unavoidable.

By satisfying the above equations (1) to (3), it is possible to prevent the C/N deterioration of the NPP signal due to insufficient diffraction, and to ensure the tracking and tracking property of the front groove portion 121G, and to prevent the center of the track from being scanned when the inner groove portion 121L is scanned. The guiding light that comes up is deviated. Thus, it is possible to form a recording track having a high quality in the recording layer, and it is possible to improve the reproduction characteristics of the recording track.

According to the above formulas (1) and (2), the groove width InW and the depth InD of the inner groove portion 121L are defined as follows according to the wavelength λ of the guide light.

At a wavelength of 600 nm: 280 nm ≦ InW ≦ 430 nm, 55 nm ≦ InD ≦ 80 nm; at 650 nm: 280 nm ≦ InW ≦ 430 nm, 65 nm ≦ InD ≦ 90 nm; at a wavelength of 700 nm: 280 nm ≦ InW ≦ 430 nm, 75 nm ≦ InD ≦ 100 nm.

Further, it is preferable that the groove width InW and the depth InD of the inner groove portion 121L are defined as follows according to the wavelength λ of the guiding light.

At a wavelength of 600 nm, 330 nm ≦ InW ≦ 400 nm, 65 nm ≦ InD ≦ 75 nm; at a wavelength of 650 nm: 330 nm ≦ InW ≦ 400 nm, 75 nm ≦ InD ≦ 85 nm; at a wavelength of 700 nm: 330 nm ≦ InW ≦ 400 nm, 85 nm ≦ InD ≦ 95 nm.

In this case, when 600 ≦ λ ≦ 700, the above formulas (1) and (2) are modified as follows.

330≦InW≦400...(1)’

(0.2λ-55)≦InD≦(0.2λ-45)...(2)’

In the gauge "P" of the inner groove portion 121L (front groove portion 121G), the groove width InW of the inner groove portion 121L is larger (wider) than the groove width OnW of the front groove portion 121G. In this way, the inner groove portion 121L can be scanned with the tracking property equal to or higher than the tracking traceability of the front groove portion 121G.

(Example)

The embodiments of the present invention are described below, but the present invention is not limited to the following embodiments.

(Example 1)

A disk-shaped polycarbonate substrate (base material) having an outer diameter of 120 mm and a thickness of 1.1 mm was produced by a press molding die. In this example, an annular region having a radius of 23.5 mm from the substrate and an annular region having a radius of 58.0 mm is used as a data recording region, and the data recording region is constituted by a guide rail including a spiral inner groove portion and a front groove portion. On the surface of the above-mentioned guide rail, a reflective layer formed of Ag-0.2 wt% In alloy was sputter-deposited at a thickness of 60 nm. After the formation of the reflective layer, the groove corresponding to the inner groove portion was measured by an atomic force microscope (AFM), and the groove width (corresponding to "InW" in Fig. 12. The same applies hereinafter) was 330 nm, and the groove depth (corresponding to "InD of Fig. 12" The same applies hereinafter.) At 75 nm, the gauge P of the inner groove portion is 0.64 μm.

Next, on the reflective layer, the ultraviolet curable resin was applied to a thickness of 200 μm by a spin coating method to be hardened. Transparent material (thickness of a transparent material followed by SiO ₂ and In ₂ O ₃ as a main component (thickness _{25nm), Fe 3 O (3nm} ) 4, GeBi-O (30nm), SiO 2 , and In ₂ O ₃ as a main component In the order of 25 nm), a recording layer laminated in a mold was formed by a sputtering method. Finally, on the recording layer, the ultraviolet curable resin was applied to a thickness of 100 μm by a spin coating method to be hardened to form a cover layer (protective layer).

Next, on the recording layer of the optical recording medium produced as described above, the optical disk drive unit "ODU-1000" manufactured by PULSTEC INDUSTRIAL CO., LTD. was used, and 1-7PP (Parity preserve/ Prohibit repeated minimum transition length) modulation mode, record data format. At this time, the optical recording medium was rotated at a linear velocity of 9.84 m/s, and a laser (guide light) outputting 0.3 mW at a wavelength of 650 nm was collected in the inner groove portion, and tracking tracking control was performed, and a laser beam of 20 mW was output at a wavelength of 405 nm. The recording light is condensed on a region of the recording layer corresponding to the inner groove portion to form a recording pit. After a recording pit (recording mark) was formed on the region of the recording layer corresponding to the inner groove portion, the recording pit was output at a wavelength of 405 nm, and laser light (reproduced light) of 80 mW was output, and the track deviation was evaluated. The track deviation is evaluated by the degree of deterioration of the reproduced signal. The measurement index of SER (Symbol Error Rate) is used as a reference for 1A-3 (1.0×10 ^-3 ).

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

(Example 2)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 360 nm and the groove depth (InD) was 75 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 2.3E-4 (2.3 × 10 ^-4 ), and good results were obtained.

(Example 3)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 400 nm and the groove depth (InD) was 75 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 3.4E-4 (3.4 × 10 ^-4 ), and good results were obtained.

(Example 4)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 330 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 2.5E-4 (2.5 × 10 ^-4 ), and good results were obtained.

(Example 5)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 360 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 1.9E-4 (1.9 × 10 ^-4 ), and good results were obtained.

(Example 6)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 400 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 2.0E-4 (2.0 × 10 ^-4 ), and good results were obtained.

(Example 7)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 330 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 5.6E-4 (5.6 × 10 ^-4 ), and good results were obtained.

(Example 8)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 360 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 4.1E-4 (4.1 × 10 ^-4 ), and good results were obtained.

(Example 9)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 400 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 5.1E-4 (5.1 × 10 ^-4 ), and good results were obtained.

(Embodiment 10)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 280 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 8.2E-4 (8.2 × 10 ^-4 ), and good results were obtained.

(Example 11)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 300 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 7.1E-4 (7.1 × 10 ^-4 ), and good results were obtained.

(Embodiment 12)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 330 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 6.4E-4 (6.4 × 10 ^-4 ), and good results were obtained.

(Example 13)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 360 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 4.7E-4 (4.7 × 10 ^-4 ), and good results were obtained.

(Example 14)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 400 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 5.5E-4 (5.5 × 10 ^-4 ), and good results were obtained.

(Example 15)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 430 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 8.9E-4 (8.9 × 10 ^-4 ), and good results were obtained.

(Embodiment 16)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 280 nm and the groove depth (InD) was 75 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 7.7E-4 (7.7 × 10 ^-4 ), and good results were obtained.

(Example 17)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 300 nm and the groove depth (InD) was 75 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 5.5E-4 (5.5 × 10 ^-4 ), and good results were obtained.

(Embodiment 18)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 430 nm and the groove depth (InD) was 75 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 7.4E-4 (7.4 × 10 ^-4 ), and good results were obtained.

(Embodiment 19)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 280 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 6.0E-4 (6.0 × 10 ^-4 ), and good results were obtained.

(Embodiment 20)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 300 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 3.1E-4 (3.1 × 10 ^-4 ), and good results were obtained.

(Example 21)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 430 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 7.7E-4 (7.7 × 10 ^-4 ), and good results were obtained.

(Example 22)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 280 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 7.0E-4 (7.0 × 10 ^-4 ), and good results were obtained.

(Example 23)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 300 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 6.1E-4 (6.1 × 10 ^-4 ), and good results were obtained.

(Example 24)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 430 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 5.3E-4 (5.3 × 10 ^-4 ), and good results were obtained.

(Embodiment 25)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 280 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 9.0E-4 (9.0 × 10 ^-4 ), and good results were obtained.

(Example 26)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 300 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 8.1 E-4 (8.1 × 10 ^-4 ), and good results were obtained.

(Example 27)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 330 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 5.6E-4 (5.6 × 10 ^-4 ), and good results were obtained.

(Embodiment 28)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 360 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 5.5E-4 (5.5 × 10 ^-4 ), and good results were obtained.

(Example 29)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 400 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 6.3E-4 (6.3 × 10 ^-4 ), and good results were obtained.

(Embodiment 30)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 430 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and the evaluation value was 6.9E-4 (6.9 × 10 ^-4 ), and good results were obtained.

(Comparative Example 1)

An optical recording medium was produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 260 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 280 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 300 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 330 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 360 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 400 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 430 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 450 nm and the groove depth (InD) was 60 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 260 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 450 nm and the groove depth (InD) was 65 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 260 nm and the groove depth (InD) was 75 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 450 nm and the groove depth (InD) was 75 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 260 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 450 nm and the groove depth (InD) was 80 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 260 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 450 nm and the groove depth (InD) was 85 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 260 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 450 nm and the groove depth (InD) was 90 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 260 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 280 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 300 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 330 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 360 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 400 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 430 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 produced under the same conditions as in Example 1 except that the groove width (InW) of the inner groove portion was 450 nm and the groove depth (InD) was 100 nm. The optical recording medium was measured for SER by the same evaluation method as in Example 1, and 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 groove width and groove depth of the inner groove portion. The relationship between SER evaluation values.

As shown in Table 1, according to Example 1-30 satisfying the conditions of 280 nm ≦InW ≦ 430 nm and 65 nm ≦InD ≦ 90 nm, it was confirmed that the SER evaluation value was lower than the reference value (1E-3) (negative 4 times of 10) The order of magnitude). On the other hand, in Comparative Example 1-26 which did not satisfy the above conditions, a result was obtained in which any SER evaluation value exceeded the reference value (1E-3). When the SER evaluation value exceeds 1E-3, the error at the time of reproduction becomes difficult and the reproduction characteristics deteriorate. Therefore, according to the embodiment 1-30, the tracking of the inner groove portion is high, and the track deviation can be effectively suppressed.

Further, according to the examples 1 to 9, 11 to 14, 16 to 24, and 27 to 30, since the SER evaluation value of 8E-4 or less is obtained, it is possible to secure a certain range with respect to the above reference value (1E-3). Stable recording and reproduction characteristics.

According to Example 1-9 which satisfies the conditions of 330 nm ≦ InW ≦ 400 nm and 75 nm ≦ InD ≦ 85 nm, the SER evaluation value of 5.6E-4 or less is obtained, and the recording and reproduction characteristics of the stable high definition accuracy can be ensured.

Fig. 16 is a view showing the relationship between the groove width and the depth of the inner groove portion and the NPP characteristics when the wavelength of the guiding light is 650 nm, and the magnitude of the NPP value is represented by a contour line. The region surrounded by the rectangle S11 in the figure (280 nm ≦ InW ≦ 430 nm, 65 nm ≦ InD ≦ 90 nm) corresponds to the region surrounded by the rectangle S12 in the embodiment 1-30, and the region surrounded by the rectangle S12 (330 nm ≦ InW ≦ 400 nm, 75 nm ≦ InD ≦ 85 nm) is particularly A high area showing the NPP value, This range corresponds to Examples 1-9. As shown in Table 1 and FIG. 16, the higher the NPP value, the lower the SER evaluation value can be suppressed.

(Example 31)

In the same manner as in Example 1-30, a sample of a plurality of optical recording media having different groove widths (InW) or groove depths (InD) in the inner groove portion was prepared, and a laser beam of 0.3 mW (guide light) was output at a wavelength of 600 nm for each sample. The inner groove portion collects light, and the output value of the NPP signal obtained based on the diffracted light is measured. This result is shown in Fig. 17.

In Fig. 17, the region surrounded by the rectangle S21 satisfies the condition of 280 nm ≦ InW ≦ 430 nm and 55 nm ≦ InD ≦ 80 nm, and the region surrounded by the rectangle S22 in S21 satisfies 330 nm ≦ InW ≦ 400 nm and 65 nm ≦ InD ≦ 75 nm. conditions of. The SER evaluation value of the region S21 was lower than 1E-3 in the same manner as in Example 1-30, and good results were obtained. In the region S22, the region having a high NPP value in S21 was specifically displayed, and it was confirmed that the SER evaluation value of 8E-4 or less was obtained.

(Example 32)

In the same manner as in Example 1-30, a sample of a plurality of optical recording media having different groove widths (InW) or groove depths (InD) in the inner groove portion was prepared, and a laser beam of 0.3 mW (guide light) was output at a wavelength of 700 nm for each sample. The inner groove portion collects light, and the output value of the NPP signal obtained based on the diffracted light is measured. This result is shown in Fig. 18.

In Fig. 18, the region surrounded by the rectangle S31 satisfies the condition of 280 nm ≦ InW ≦ 430 nm and 75 nm ≦ InD ≦ 100 nm, and the region surrounded by the rectangle S32 in S31 satisfies 330 nm ≦ InW ≦ 400 nm and 85 nm ≦ InD ≦ 95 nm. conditions of. The SER evaluation value of the region S31 was lower than that of 1E-3 in the same manner as in Example 1-30, and good results were obtained. The region surrounded by the rectangle S32 particularly shows the region where the NPP value in S31 is high, and it is confirmed that the SER evaluation value of 8E-4 or less is obtained.

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

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

Further, in the above embodiment, an example in which the optical recording medium of the present invention is driven by the optical recording device 1 shown in FIG. 1 has been described. However, the optical recording device is not limited to the above example, and other optical recording devices are also applicable to this invention.

In the above embodiment, an example of a guide rail having a gauge of 0.32 μm has been described, but the gauge distance is not limited thereto, and a suitable gauge distance corresponding to the distance between the projections (or the distance between the grooves) can also be applied.

121‧‧‧rails

121G‧‧‧ front ditch

121L‧‧‧Internal Department

Claims (4)

A guide layer separation type optical recording medium comprising: a guide layer including a guide rail of an inner groove portion and a front groove portion; and one or more recording layers capable of recording information on an area corresponding to the inner groove portion and the front groove portion; The groove width of the inner groove portion (half the sum of the base width of the inner groove portion and the opening width of the inner groove portion) is InW [nm], the depth of the inner groove portion is InD [nm], and the laser beam condensed on the guide rail When the wavelength is λ [nm], the inner groove portion satisfies the following relationship: 280 ≦ InW ≦ 430, (0.2 λ - 65) ≦ InD ≦ (0.2 λ - 40), and 600 ≦ λ ≦ 700. The guide layer separation type optical recording medium according to claim 1, wherein the groove width InW [nm] of the inner groove portion satisfies the relationship of 330 ≦ InW ≦ 400. The guide layer separation type optical recording medium according to claim 1 or claim 2, wherein the depth InD [nm] of the inner groove portion satisfies the relationship of (0.2λ - 55) ≦ InD ≦ (0.2λ - 45). The guide layer separation type optical recording medium according to claim 1 or claim 2, wherein the groove width of the inner groove portion is wider than a groove width of the front groove portion, wherein a groove width of the front groove portion is the front groove portion Half of the sum of the minimum width and the maximum width of the front groove portion described above.