WO2007037070A1

WO2007037070A1 - Optical information recording medium and optical information recording medium reproducing device

Info

Publication number: WO2007037070A1
Application number: PCT/JP2006/315419
Authority: WO
Inventors: Masaki Yamamoto; Go Mori; Hideharu Tajima; Nobuyuki Takamori
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2005-09-29
Filing date: 2006-08-03
Publication date: 2007-04-05
Also published as: JP4209416B2; JP2007095211A

Abstract

An optical information recording medium (60) comprises a transparent layer (10), a first information recording layer (20), an intermediate layer (30) mainly made of resin, a second information recording layer (40), and a substrate (50) formed in this order from the reproducing light beam input side. Reproducing films (21, 41) enabling reproduction of a signal of a mark length shorter than the optical resolution limit that a reproducing device for reproduction with a reproducing light beam of a blue laser has and essential at least for super-resolution reproduction are formed on both the first and second information recording layers (20, 40), respectively. With this, without needing any reflective film that has been required for conventional super-resolution media using a mask layer, while reducing the cost up to a lowest limit, a two-layer super-resolution medium having a high reproduction durability and a higher recording density is realized.

Description

Specification

Optical information recording medium and optical information recording medium reproducing apparatus

Technical field

[0001] The present invention relates to an optical information recording medium for optically reproducing information, and an optical information recording medium reproducing apparatus for reproducing the optical information recording medium.

Background art

In recent years, in optical information recording media, it is required to increase the information recording density more and more in order to process enormous information such as images. As a solution to this problem, super-resolution technology, which is one of the information processing improvement technologies during reproduction, and multilayer optical information that can be recorded and reproduced on each information recording layer with multiple information recording layers. There is a recording medium. Super-resolution technology is a technology that reproduces a signal with a mark length (determined by the laser wavelength and the numerical aperture of the optical system) below the optical resolution limit of the playback device. As a result, recording using a smaller mark length becomes possible, so that the substantial recording density increases. This is due to the fact that the reproduction technology becomes a problem when the density is increased, not the recording technology.

[0003] These technologies will be described first from the super-resolution technology. Conventionally, many optical information recording media (hereinafter referred to as super-resolution media) for reproducing signals having a mark length shorter than the optical resolution limit of a reproducing apparatus have been proposed.

[0004] As such a technique, as disclosed in Patent Document 1, for example, a thermochromic dye layer whose optical characteristics (transmittance) change according to temperature is used as a mask layer, and incident light from a reflective film is incident. What is provided on the surface is known. Further, this technique is applicable not only to a rewritable optical recording medium but also to a reproduction-only optical recording medium in which information that cannot be rewritten due to unevenness of the substrate is recorded. Note that the mask layer is a layer that causes a super-resolution phenomenon such as artificially limiting a laser spot described later.

[0005] In an optical recording medium as disclosed in Patent Document 1, temperature or light intensity distribution is generated in a reproduction laser spot on a reproduction layer closer to the reproduction light incident surface than the reflection layer. A distribution of optical properties occurs in the laser spot. For example, transmission when the temperature is high When a material having a high rate is used for the reproducing layer, since the temperature is high and only the transmittance of the portion is high, the laser spot generated on the reflective layer surface is reduced in a pseudo manner. As a result, a signal having a mark length shorter than the optical resolution limit can be reproduced.

[0006] Next, a multilayer optical information recording medium will be described. For example, as disclosed in Patent Document 2, a multilayer optical information recording medium is provided with an information recording layer in the order of the first information recording layer, the second information recording layer, and the like from the reproduction light incident surface. In addition, each information recording layer is separated by an intermediate layer made of resin. In such a structure, the information recording layer other than the information recording layer farthest from the reproducing light incident surface is a translucent layer through which the reproducing light is transmitted. Therefore, the reproducing light incident surface force is incident on the reproducing light force incident on each information recording layer. Focused. Therefore, this multilayer optical information recording medium can be said to be an optical information recording medium capable of increasing the information recording density as the total number of information recording layers increases.

[0007] As described above, the above two methods have been conventionally proposed as a method for increasing the density of an optical information recording medium.

Patent Document 1: Japanese Patent Gazette “JP 2001-35012 (published on February 9, 2001)”

Patent Document 2: Japanese Patent Publication “JP 2000-235733 A (published August 29, 2000)”

Disclosure of the invention

[0008] In recent years, since the laser spot of the reproduction light can be made smaller, the reproduction laser has been shortened from a red laser (about 635 nm) to a blue laser (about 405 nm, which is 400 nm or more and 410 nm or less in the present application). With the shift to wavelength, further high-density information processing during information reproduction is becoming possible. Therefore, in the present application, blue laser light is used as reproduction light.

[0009] However, Patent Documents 1 and 2 listed as background art have the following problems.

First, the super-resolution reproduction technique is a technique for improving the recording density in a planar area, so there is a limit to the improvement of the recording density. For example, FIG. 21 shows a disk measurement having a semiconductor laser having a wavelength of 404 nm, which is the wavelength of blue laser light, and an optical system having an NA (aperture ratio) of 0.85. This is the result of measuring the OTF of a single-layer super-resolution optical information recording medium with 50 nm of Si layered on a pit substrate using a measuring instrument. Note that OTF is an index that represents super-resolution performance, and represents the dependency of CZN (an evaluation standard that represents signal quality) on the recording mark length (in the case of a read-only optical information recording medium, agrees with the pit length). FIG. 21 shows that the resolution limit of the single-layer super-resolution optical information recording medium is smaller than the theoretical resolution limit in the reproducing optical system existing in the hatched area. In other words, there is a limit to the improvement in recording density in super-resolution reproduction technology.

[0011] In the mask-type super-resolution reproduction technique represented by Patent Document 1, the laser spot is reduced in a pseudo manner, so that the utilization efficiency of the reproduction light is reduced (the reflected light is naturally reduced). For this reason, there is a limit to the reduction of the laser spot, and as with the case shown in FIG. In addition, the materials used for the mask layer are usually dyes and phase change materials, and these materials change in composition and phase by absorbing light or heat, so that there is a problem of poor reproduction durability. there were. In addition, since the materials used for the mask layer are usually pigments and phase change materials, they are more expensive than the film materials normally used for optical information recording media. Therefore, the super-resolution medium is more expensive than a normal optical information recording medium (one information recording layer).

On the other hand, since the multilayer optical information recording medium is difficult to produce, there is a problem that it becomes a very expensive recording medium. The reason why the production is difficult will be described below with an example of the production process of the multilayer optical information recording medium.

[0013] In the production of a multilayer optical information recording medium, first, a first information recording layer such as a recording film or a reflective film is formed on a substrate by sputtering or the like in a vacuum, and then the substrate is placed in the atmosphere. After returning to the inside, an ultraviolet curable resin or the like is spin-coated on the first information recording layer. Next, after sticking the plastic stamper, it is cured by irradiating with ultraviolet rays, and the plastic stamper is peeled off, so that the groove for the tracking and the prepits in which information is recorded by the arrangement are formed on the surface of the intermediate layer. The second information recording layer is formed on the intermediate layer, and the intermediate layer is transferred with the unevenness transferred by the 2P method. Such a process is repeated a number of times according to the number of information recording layers, and finally a cover layer (translucent layer) is provided. [0014] As described above, the multilayer optical information recording medium is produced by a very complicated process of going back and forth between the vacuum and the atmosphere over and over again. In addition, each layer of the multilayer optical information recording medium has a different film structure in order to adjust the reflectance of each layer. Therefore, during normal mass production, each layer of the multilayer optical information recording medium is unidirectional along the production line. Formed while proceeding. For this reason, as many vacuum film forming apparatuses as the number of information recording layers are required. In addition, the vacuum film forming apparatus is very expensive, and the running cost is also expensive among apparatuses used for producing optical information recording media.

[0015] For these reasons, the multilayer optical information recording medium becomes a very expensive recording medium. This means that the price of a single-sided dual-layer disc (recording capacity: 50 GB) in the Blu-ray Disc currently on sale (2005.01.31) is more than twice that of a single-layer disc (recording capacity: 25 GB). It is clear from some. In general, the cost increase due to the complexity of these production processes is much larger than the cost increase due to the change of the material used for the information recording layer.

[0016] As described above, there are many problems in the method for improving the information recording density in the conventional optical information recording medium.

[0017] The present invention has been made in view of the above problems, and is a multilayer optical information recording using super-resolution reproduction technology for reproduction light of blue laser light that is inexpensive and excellent in reproduction durability. Speak for the purpose of providing media.

[0018] In order to solve the above-described problems, the optical information recording medium according to the present invention includes at least a translucent layer, a first information recording layer, and an intermediate layer mainly made of resin from the incident surface side of the reproduction light. And an information recording medium in which the second information recording layer and the substrate are laminated in this order, and are reproduced by the reproduction light of the blue laser light on both the first and second information recording layers. A playback film made of an inorganic material that enables playback of a signal with a mark length shorter than the optical resolution limit of the playback device that performs playback is included! /

In the above configuration, when reproducing the information recorded on the first information recording layer, the reproduction light of blue laser light is irradiated through the translucent layer and focused on the first information recording layer. Then, it is possible to read out information recorded with a mark length less than the resolution limit of the first information recording layer. [0020] Further, when reproducing the information recorded in the second information recording layer, the reproduction light of the blue laser light is irradiated through the translucent layer, the first information recording layer, and the intermediate layer, Focus on the second information recording layer. Then, information recorded with a mark length less than the resolution limit of the second information recording layer can be read.

[0021] Thereby, in both the first and second information recording layers, the substantial recording density (meaning the reproducible recording density) can be made higher than the recording density limited by the resolution limit. Therefore, as compared with the super-resolution medium of Patent Document 1, the recording capacity can be improved by having more information recording layers. Furthermore, when producing recording media having the same recording capacity, the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Patent Document 2 in which each information recording layer has a recording density limited by the resolution limit. Is possible.

As described above, the first and second information recording layers can read information by the super-resolution effect. As a result, the recording density of the first and second light-absorbing films is below the resolution limit, so that the recording capacity of the optical information recording medium can be improved with respect to the manufacturing cost, and a recording medium with high cost performance can be obtained. Can be provided. Therefore, by providing the first and second information recording layers, when producing a recording medium having the same recording capacity, the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Patent Document 2. Become. Therefore, in the production line, the number of expensive vacuum devices for forming the recording layer by sputtering can be reduced, and the production cost of the recording medium accompanying the increase in the recording layer can be greatly reduced. .

[0023] Further, in the super-resolution technique using the mask layer as in Patent Document 1, a reflective film is further required in addition to the mask layer. On the other hand, according to the above configuration, as will be described later in the embodiment, it is possible to reproduce a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light. In order to perform at least super-resolution reproduction, it is only necessary to use a reproduction film that is not necessary as a reflection film, so that the cost can be reduced.

[0024] The materials of the first and second regenerative films are inorganic materials, which are generally more stable than organic materials, as will be described later in Examples. Further, as will be shown later in Examples, the first and second reproduction films are blue lasers and exhibit good super-resolution characteristics and reproduction durability.

[0025] Further, as will be described later in an embodiment, the power of laser light as shown in Patent Document 1 is used. Unlike the mask-type super-resolution medium, in which the average reflectance of the pit part changes, the first and second reproduction films have an average of the pit part with respect to the wavelength of the laser beam as the reproduction light, depending on the power of the laser beam as the reproduction light Reflectance hardly changes.

[0026] In the mask type super-resolution medium, the amount of light per unit area increases as the power of the laser beam increases, and the temperature rise associated therewith increases. The reflectance changes due to the power of. A similar phenomenon occurs when the focus servo is pulled into the information recording layer. When the amount of defocus of the information recording layer relative to the focal point of the pickup is large, the amount of light per unit area of the information recording layer is small, which is accompanied by this. Temperature rise is small. On the other hand, as the defocus amount decreases, the amount of light per unit area of the information recording layer increases, and the accompanying temperature increase also increases, so that the pseudo laser spot changes and the reflectance changes. For this reason, in the mask-type super-resolution medium, when the focus servo is pulled into the information recording layer, the reflectivity of the information recording layer changes depending on the relative position between the pickup and the information recording layer. Since a curve is distorted, a circuit is required to divide the focus error signal by the total light quantity and to standardize it. On the other hand, in the optical information recording medium of the present application, since the average reflectance of the pit portion with respect to the wavelength of the laser beam hardly changes depending on the temperature, the above circuit is not necessary. This has the effect of reducing the cost of the playback device.

[0027] In the mask type super-resolution medium, the average reflectance of the pit portion changes because the beam spot size changes in a pseudo manner depending on the power of the laser beam that is the reproduction light. Since the optimum beam spot varies depending on the laser beam, the optimum laser power varies depending on the mark length. For example, in a mask-type super-resolution medium, the signal quality with a mark length longer than the resolution limit deteriorates at the laser power at which marks below the resolution limit can be reproduced. On the other hand, in the optical information recording medium of the present application, the signal quality of the mark length longer than the resolution limit does not deteriorate even in the laser par where the mark below the resolution limit can be reproduced. This also has the effect that an optical information recording medium with better jitter can be obtained compared to a mask type super-resolution medium. Therefore, compared with the super-resolution technique disclosed in Patent Document 1, a super-resolution technique with improved reproduction durability becomes possible. [0028] Further, the optical information recording medium according to the present invention includes at least a translucent layer, a first information recording layer, an intermediate layer mainly made of resin, and a second information recording layer from the reproduction light incident surface side. And an optical information recording medium in which a substrate is laminated in this order, and the first information recording layer has a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with blue laser beam reproducing light. It can be characterized in that it contains a regenerative film made of an inorganic material that can regenerate the signal.

[0029] With the above configuration, only the first information recording layer can read information by the super-resolution effect, so that the recording capacity can be improved compared to the super-resolution medium of Patent Document 1, and the patent Although the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Document 2, the recording capacity can be improved as compared with the above-described configuration in which both the first information recording layer and the second information recording layer have reproducing films. The amount is reduced. However, when both the first and second information recording layers include a reproducing film, the first information recording layer is recorded under conditions that maintain the super-resolution characteristics and the reproduction durability in the second information recording layer. Whereas the conditions of the layer must be determined, in the above configuration, the restrictions on the conditions of the first information recording layer are relaxed, so the degree of freedom of the material and film thickness of the reproduction film of the first information recording layer is reduced. improves.

[0030] Further, the optical information recording medium according to the present invention includes at least a translucent layer, a first information recording layer, an intermediate layer mainly made of resin, and a second information recording layer from the reproduction light incident surface side. And an optical information recording medium in which the substrate is laminated in this order, and the second information recording layer has a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light. It can be characterized in that it contains a regenerative film made of an inorganic material that can regenerate the signal.

[0031] In the above configuration, the recording capacity is smaller than in the above configuration in which the first information recording layer and the second information recording layer are both provided with the reproducing film, as in the configuration in which only the first information recording layer includes the reproducing film. However, the degree of freedom of the material and film thickness of the reproducing film of the second information recording layer is improved.

[0032] Still other objects, features, and advantages of the present invention will be sufficiently enhanced by the following description. The benefits of the present invention will become apparent from the following description with reference to the accompanying drawings.

Brief Description of Drawings FIG. 1 is a cross-sectional view showing the structure of a double-layer super-resolution optical information recording medium according to Embodiment 1 of the present invention.

FIG. 2 (a) is a perspective view showing a structure of prepits provided in an intermediate layer in the optical information recording medium.

FIG. 2 (b) is a perspective view showing the structure of prepits provided on the substrate in the optical information recording medium.

FIG. 3 is a cross-sectional view showing the structure of an optical information recording medium of Comparative Example 1 relative to the optical information recording medium of Example 1 of Embodiment 1 of the present invention.

FIG. 4 (a) is a characteristic diagram showing CZN dependence (OTF) for each mark length in the first information recording layer in the optical information recording media of Example 1 and Comparative Example 1.

FIG. 4 (b) is a characteristic diagram showing the dependence (OTF) of CZN on each mark length in the second information recording layer in the optical information recording medium of Example 1 and Comparative Example 1.

FIG. 5 is a characteristic diagram showing the dependency of the 0 .: m mark length on C ZN with respect to the number of reproductions in the optical information recording medium of Example 1.

FIG. 6 is a cross-sectional view showing a structure of an optical information recording medium of Example 2 according to Embodiment 1 of the present invention.

[FIG. 7] The dependence (OTF) of CZN on the respective mark lengths in the first information recording layer in the optical information recording media of Example 1, Example 3-1, Example 3-2 and Comparative Example 2. FIG.

FIG. 8 is a characteristic diagram showing the dependence of CZN of the 0.1 μm mark length of the first information recording layer on the transmittance of the first information recording layer in the optical information recording media of Example 4 and Example 7. is there

[FIG. 9] In the optical information recording media of Example 4 and Example 7, the transmission rate of the three types of first information recording layer is 0.1M mark length CZN of the first information recording layer with respect to the number of reproductions. It is a characteristic view which shows dependence.

FIG. 10 is a characteristic diagram showing the CZN dependence of the 0.1 μm mark length of the second information recording layer on the transmittance of the first information recording layer in the optical information recording media of Example 3 and Example 4. is there FIG. 11 is a characteristic diagram showing the dependency of the transmittance of the first information recording layer on the first reproduction film thickness in the optical information recording media of Example 4 and Example 7.

FIG. 12 is a characteristic diagram showing the CZN dependence of the 0.1 μm mark length of the second information recording layer on the second reproduction film thickness in the optical information recording medium of Example 5.

FIG. 13 shows the dependence of CZN of the 0.1 μm mark length of the second information recording layer on the number of reproductions in the film thicknesses of the three second reproducing films in the optical information recording medium of Example 5. FIG.

FIG. 14 is a cross-sectional view showing a structure of an optical information recording medium of Example 6 according to Embodiment 1 of the present invention.

FIG. 15 is a characteristic diagram showing the CZN dependence of the 0.1 μm mark length of the first information recording layer on the number of reproductions in the optical information recording media of Example 6 and Example 1.

FIG. 16 is a characteristic diagram showing the CZN dependence of the 0.1 μm mark length of the second information recording layer on the number of reproductions in the optical information recording media of Example 6 and Example 1.

FIG. 17 is a cross-sectional view showing a structure of an optical information recording medium according to the second embodiment of the present invention.

FIG. 18 is a cross-sectional view showing a structure of an optical information recording medium according to Embodiment 3 of the present invention.

FIG. 19 is a diagram showing a schematic configuration of an optical information recording medium reproducing device in a fourth embodiment of the invention.

FIG. 20 is a diagram showing a schematic configuration of an optical pickup device in the optical information recording medium reproducing device.

FIG. 21 is a diagram showing that there is a limit to the improvement in recording capacity in single-layer super-resolution technology. Explanation of symbols

10 Translucent layer

11 Polycarbonate film

12 Transparent adhesive

13 Transparent substrate

20, 80 First information recording layer

21 First regeneration membrane

22 First protective film 30 middle tier

31 Prepit

40, 90 Second information recording layer

41 Second regeneration membrane

42 Second protective film

50 substrates

51 Prepit

60, 61, 62 Optical information recording media

81, 91 Reflective film

100 Optical information recording medium playback device

102 Optical pickup device (optical reading means)

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1]

One embodiment of the present invention is described below with reference to FIGS.

FIG. 1 shows a cross-sectional structure of a two-layer super-resolution optical information recording medium 60 according to the present embodiment.

As shown in FIG. 1, the optical information recording medium 60 includes a translucent layer 10, a first information recording layer 20, an intermediate layer 30, a second information recording layer 40, and a substrate 50. They are stacked in this order from the light incident surface.

The light transmitting layer 10 includes a polycarbonate film 11 and a transparent adhesive resin layer 12.

The intermediate layer 30 is formed of a resin such as a transparent ultraviolet curable resin. The substrate 50 is made of a resin such as polyolefin resin.

Further, as shown in the enlarged perspective view of FIG. 2A, prepits 31 in which information is recorded are formed in the intermediate layer 30. Further, as shown in the enlarged perspective view of FIG. 2B, pre-pits 51 are formed on the substrate 50.

[0040] The first and second information recording layers 20 and 40 are formed on the prepits 31 and 51, respectively.

Then, the unevenness due to the pre-pits 31, 51 is reflected, and information is recorded. This With such a structure, a so-called read-only optical information recording medium is configured.

[0041] The first information recording layer 20 includes a first reproducing film 21 made of Si or Ge, or an alloy or mixture of these as a main component. The first reproducing film 21 can reproduce a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light. Further, at least for super-resolution reproduction, the reflection film that is necessary for the super-resolution technique of Patent Document 1 is not required, and only the first reproduction film 21 may be used.

[0042] The second information recording layer 40 includes a second reproducing film 41 made of Si or Ge alone, or an alloy or mixture of these as a main component. The second reproduction film 41 can reproduce a signal having a mark length shorter than the optical resolution limit of a reproduction apparatus that reproduces with the reproduction light of blue laser light. Further, at least for super-resolution reproduction, the reflection film that is necessary for the super-resolution technique of Patent Document 1 is not required, and only the second reproduction film 41 may be used.

[0043] The first and second reproduction films 21 and 41 are formed by, for example, a sputtering method in a sputtering apparatus.

[0044] The first and second regenerative films 21, 41 are not limited to Si or Ge alone, or alloys or mixtures containing these as main components. Ni, Mo, W, Mn, Pt, C, Zr, In, Al, Cu, Fe, Co, etc. may be a single element film or a compound thereof, but it may be a simple substance of Si or Ge, or an alloy or mixture containing these as a main component. preferable. As a result, it is possible to obtain better super-resolution characteristics as compared with the reproduction film of other materials. Therefore, the recording capacity of the optical information recording medium can be improved.

[0045] The blue laser light here is light having a wavelength of 400 nm to 410 nm.

As described above, the optical information recording medium 60 has a mark length shorter than the optical resolution limit of the reproducing apparatus that reproduces with the reproducing light of the blue laser beam in the first and second information recording layers 20 and 40. The first and second reproduction films 21 and 41 that can reproduce the above signal are provided. In addition, in the first and second information recording layers 20 and 40, at least for super-resolution reproduction, the reflective film that was necessary in the super-resolution technique of Patent Document 1 is not required, and the first reproduction film 21 If only

[0047] Thereby, the first and second information recording layers 20 and 40 both have a substantial recording density (meaning a reproducible recording density) of a reproducing apparatus that reproduces with blue laser light. Image limit It is higher than the recording density limited by the field. Therefore, as compared with the super-resolution media of Patent Documents 1 and 2, the recording capacity can be improved by the number of information recording layers. Furthermore, when producing recording media having the same recording capacity, the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Patent Document 3 in which each information recording layer has a recording density limited by the resolution limit. Is possible. Therefore, the number of expensive vacuum devices for forming the recording layer by sputtering in the production line can be reduced, and the production cost of the recording medium associated with increasing the number of recording layers can be greatly reduced. it can.

[0048] In addition, in the super-resolution technique using the mask layer as in Patent Document 1, a reflective film is required in addition to the mask layer. According to the above configuration, the function of the reflective film is achieved by the reproduction film itself. Therefore, the cost can be reduced.

[0049] Further, as described above, the material of the first and second reproduction films is an inorganic substance, and is generally more stable than an organic substance. In addition, as will be shown later in Examples, the super-resolution characteristics and reproduction durability that are good with a blue laser not shown in Patent Document 2 are shown. Therefore, compared with the super-resolution technique disclosed in Patent Document 1 and Patent Document 2, a super-resolution technique with improved reproduction durability becomes possible.

[0050] (Example 1)

An optical information recording medium 60 according to the present embodiment shown in FIG. 1 includes a polycarbonate film 11 (film thickness: 80 m) and a transparent adhesive resin layer 12 (film thickness: 20 m) as a light-transmitting layer 10 and a first layer. The first reproduction film 21 (Si, film thickness: 7 nm) as the information recording layer 20, the transparent ultraviolet curable resin (film thickness: 25 m) as the intermediate layer 30, and the second information recording layer 40 The second reproduction film 41 (Si, film thickness: 50 ηm) and a polyolefin-based resin substrate as the substrate 50 are provided, and the layers are stacked in this order from the light incident surface.

In contrast, FIG. 3 shows a cross-sectional structure of a conventional two-layer optical information recording medium 70 as Comparative Example 1 for the optical information recording medium 60 of the present example. In Comparative Example 1, components having functions equivalent to those of the components of the optical information recording medium 60 of the present embodiment are denoted by the same reference numerals.

As shown in FIG. 3, the two-layer optical information recording medium 70 of Comparative Example 1 includes a polycarbonate film 11 (film thickness of 80 μm) as a light-transmitting layer 10 and a transparent adhesive resin layer 12 (film). Thickness 20 m) (1) Translucent reflective film 81 (Au, film thickness 20 nm) as information recording layer 80, transparent UV-cured resin layer (film thickness 25 μm) as intermediate layer 30, and second information recording layer 90 A reflection film 91 (Ni, film thickness: 30 nm) and a polyolefin-based resin substrate as the substrate 50 are provided, and the structure is laminated in this order from the light incident surface.

Further, as shown in FIGS. 2 (a) and 2 (b), prepits 31 on which information is recorded are formed on the intermediate layer 30 and the substrate 50 of the two-layer optical information recording medium 60 of the present embodiment. 51 is provided. As a result, the two-layer optical information recording medium 60 has the information recording layers 20 and 40 formed on the prepits 31 and 51, so that the prepits 31 and 40 corresponding to the information recording layers 20 and 40 are formed. As a result of 51, the unevenness is transferred. The same applies to the two-layer optical information recording medium 70. Therefore, the two-layer optical information recording medium 60 and the two-layer optical information recording medium 70 are so-called read-only optical information recording media in which the information recording layers 20 and 40 are in a recorded state. It is formed.

Subsequently, the optical information recording medium 60 of the present example (hereinafter referred to as “Example 1 medium” in the present example) and the two-layer optical information recording medium 70 of Comparative Example 1 (hereinafter referred to as the present example) Will be referred to as “Comparative Example 1 medium”).

[0055] FIGS. 4 (a) and 4 (b) show a wavelength of 404 nm semiconductor laser, which is the wavelength of blue laser light, and N.

A. (Aperture ratio) With a disk measuring instrument having an optical system of 0.85, the OTFs of the first and second information recording layers 20 and 40 were measured in the above Example 1 medium and Comparative Example 1 medium, respectively. It is a result. Note that OTF is an index that represents super-resolution performance, and represents the dependency of the recording mark length of CZN (an evaluation standard that indicates signal quality) (in the case of a read-only optical information recording medium, it agrees with the pit length).

[0056] As is apparent from FIGS. 4 (a) and (b), in the medium of Example 1, almost no signal is confirmed in both the first and second information recording layers 80 and 90 in the medium of Comparative Example 1 (CZN is 10 dB). Below) The C / N exceeds 30 dB for both the first and second information recording layers 20, 40 even at a mark length of 0.10 / zm, which is below the resolution limit of the reproduction optical system. This indicates that a signal with a mark length less than the resolution limit can be reproduced.

[0057] In addition, as shown by oblique lines in FIGS. 4 (a) and 4 (b), the theoretical optical resolution limit of the reproducing apparatus is a region larger than 0.10 / zm and smaller than 0.12 / zm. Exists within. Comparative Example 1 medium The CZN of the body is less than 10 dB where almost no signal is observed in this pit length region, and the optical resolution limit of Comparative Example 1 medium is the theoretical optical resolution limit of the playback device from 0.10 m It corresponds to the region that is larger than 0.12 / zm. On the other hand, the optical resolution limit of the medium of Example 1 is 0.06 / ζ πι to 0.10 m, which is shorter than that of the medium of Comparative Example 1. That is, the information recording using the signal of the shorter mark length is possible in the medium of Example 1 compared to the medium of Comparative Example 1. Therefore, when a signal with a short mark length is recorded in the same length region, naturally, a larger capacity signal can be recorded. Thus, the Example 1 medium has an information recording density (linear density) greater than that of the Comparative Example 1 medium.

In addition, in the first information recording layer 20 of the medium of Example 1, the laser beam intensity of the reproduction light having a CZN exceeding 30 dB at a mark length of 0.10 μm that is not more than the resolution limit of the reproduction optical system. Thus, the average reflectance of the 0.10 m pit row at the wavelength of the blue laser light (average reflectance of the concave and convex portions) is 12%, but it is less than half of the power of the laser light. At 10 / zm, CZN is less than 15dB of laser beam power, and the average reflectivity of 0.10 / zm pit row is 11%, and the reflectivity changes almost according to the laser beam power. I ’m going to scream.

FIG. 5 shows a mark length that is 20,000 times of continuous reproduction in each of the first and second information recording layers 20 and 40 of the medium of Example 1 and that is less than or equal to the optical resolution limit of the reproducing apparatus. This is the result of comparing the initial CZN at 10 m and the CZN after 20,000 times.

[0060] From FIG. 5, in Example 1 medium, the CZN with a mark length of 0.1 μm does not fall below 30 dB in both the first and second information recording layers 20 and 40 even after continuous playback of 20,000 times. It can be seen that there is almost no deterioration and excellent reproduction durability.

[0061] Thus, the medium of Example 1 cannot be obtained with a normal super-resolution optical information medium with respect to the reproduction light of blue laser light! /, Has reproduction durability and cannot be reached! /, It was shown that an information recording density larger than that of a normal optical information recording medium (single layer) can be produced at a lower production cost than a multilayer optical information recording medium having the same information recording density.

Note that the first reproduction film 21 and the second reproduction film 41 each enable reproduction of a signal having a mark length shorter than the optical resolution limit of a reproduction apparatus that reproduces with the reproduction light of blue laser light. At present, the super-resolution reproduction principle is not clear.

[0063] (Example 2)

Further, the optical information recording medium 60 of the present embodiment is not limited to the structure of the above Example 1 medium.

[0064] For example, in the optical information recording medium 60 of the present embodiment (hereinafter referred to as "embodiment 2 medium" in this embodiment), the light-transmitting layer 10 can sufficiently transmit the reproduction light. A hard coat may be provided on the reclaimed surface, or it may be formed of other materials such as ultraviolet curable resin. Further, as shown in FIG. 6, the translucent layer 10 may be a transparent substrate 13 or a structure including the transparent substrate 13. In this structure, the prepits 31 provided in the intermediate layer 30 in the medium of Example 1 can be provided on the transparent substrate 13. In this configuration, prepits (not shown) provided on the transparent substrate 13 are formed in the opposite direction to the prepits 31. Further, in such a configuration, it is only necessary to bond the two-layer structure, so that it is not necessary to use 2P transfer which requires complicated processes, which is used in the manufacture of Example 1. The optical information recording medium is manufactured at a lower cost. can do. Since this structure conforms to the DVD standard, a high-density DVD (HD-DVD) can be provided at low cost.

[0065] The substrate 50 may also be polycarbonate resin or other resin that can be compression-molded !, glass, metal, or the like.

[0066] (Example 3)

Further, the optical information recording medium 60 of the present embodiment is not limited to the structure of the above Example 1 medium and Example 2 medium.

For example, in the optical information recording medium 60 of the present embodiment (hereinafter referred to as “embodiment 3 medium” in this embodiment), the materials of the first and second reproduction films 21 and 41 are as follows: In addition, it is possible to reproduce a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light, and at least the first and second reproducing films 21, 21 for super-resolution reproduction. Any material that requires 41 is acceptable. It is not limited to Si or Ge alone, or an alloy or mixture containing these as a main component.

[0068] Example 1 medium in which the material of the first reproduction film 21 is Si (film thickness: 7 nm), and Example 3-1 medium in which the material of the first reproduction film is Ni (film thickness: 7 nm); The material of the first regeneration film is Ni (film thickness: 15nm) Example 3-2 and Comparative Example 2 medium in which the material of the first reproduction film is Ni (film thickness: 30 nm) are compared for the OTF of the first information recording layer 20. Figure 7 shows.

[0069] As clearly shown in FIG. 7, Example 3-1 using 7 nm thick Ni as the material of the first reproduction film 21 also includes a medium using 7 nm thick Si. Represents almost the same OTF, and C ZN exceeds 30 dB even at a mark length below the resolution limit of the reproduction optical system, and Z Z exceeds 30 dB. A signal having a mark length shorter than the optical resolution limit of the apparatus can be sufficiently reproduced. In addition, Example 3 using Ni with a thickness of 15 nm as the material of the first reproduction film 21 Example 2 using Si with a thickness of 7 nm in Example 3-2 medium Example of using Ni with a thickness of 7 nm 3-1 Power that shows slightly inferior OTF compared to media 3-1 C / N exceeds 25 dB even at a mark length below the resolution limit of the reproduction optical system, 0.10 / zm. It is possible to reproduce a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light.

[0070] However, in the comparative example 2 medium using Ni with a film thickness of 30 nm as the material of the first reproduction film 21, the mark length is not more than the resolution limit of the reproduction optical system as shown in FIG. At 10 / zm, CZN was less than 10 dB, and no super-resolution characteristics were observed. Furthermore, even in the case of a simple element film such as Mo, W, Mn, Pt, C, Zr, In, Al, Cu, Fe, Co, or a compound containing Ni, the film thickness is almost the same. Since we confirmed that super-resolution characteristics can be obtained, we included simple element films such as Mo, W, Mn, Pt, C, Zr, In, Al, Cu, Fe, Co and Ni with a film thickness of 15 nm or less Even the compound is sufficiently expected to exhibit super-resolution characteristics with the same structure as each example.

[0071] Further, as will be described later with reference to Fig. 10 of the fourth embodiment, for example, the second information recording layer 40 of the medium of the third embodiment has the best super-resolution characteristics currently obtained. 1 When the film structure (Si, film thickness 50 nm) is the same as that of the second information recording layer 40 of the medium, the mark length is less than the optical resolution limit of the reproducing device in the second information recording layer 40 of the medium of Example 3. In order to maintain CZN at a certain 0.1 μm at 30 dB where the characteristics can be sufficiently confirmed, it is preferable that the transmittance of the first information recording layer 20 at the reproduction light wavelength that is the blue laser light is greater than 20%. If the material of the first playback film 21 is Ni, the playback is blue laser light when the film thickness is 15 nm. The transmittance at the optical wavelength is 20.4%, and it has been confirmed that when the film thickness is thinner than 15 nm, the transmittance is larger than 20.4%. Therefore, a film thickness of 15 nm or less is preferable. In addition, as a material for the first reproduction film 21, a single element film such as Mo, W, Mn, Pt, C, Zr, In, Al, Cu, Fe, Co or the like having a film thickness of 15 nm or less, or a film including Ni is included. Even when a compound is used, the transmittance is preferably greater than 20%.

[0072] However, the material of the first reproduction film 21 is preferably Si or Ge alone, or an alloy or mixture containing these as a main component, for the following reasons. First, as can be seen from FIG. 7, when Si is used as the material for the first regenerative film 21, the super-resolution characteristics are slightly better than when 7nm-thick Ni is used (0. 06 m mark length, 0.12 m mark length, etc.) and the recording capacity of the optical information recording medium 60 can be improved. In addition, when using Si so that the OTF force of the second information recording layer 40 in the Example 1 medium shown in FIG. As shown in Fig. 7, when Ni is used, increasing the thickness to 30 nm significantly lowers the super-resolution characteristics. Therefore, from the viewpoint of the super-resolution characteristics of the blue laser beam with respect to the reproduced light. Even in the configuration of the present embodiment, it can be sufficiently predicted that the thickness limit of the first reproduction film can be expanded by using Si as the material of the first reproduction film 21. In addition, the reproduction power obtained by measuring OTF shown in Fig. 7 is Example 1 using Si with a film thickness of 7 nm. The reproduction power of the medium is Example 3 using Ni with a film thickness of 7 nm and 15 nm. —One medium and Example 3-2 The super-resolution reproduction sensitivity is small, about half of the reproduction capacity of the two media. This makes it possible to reduce the power consumption of the reproduction laser. The same can be said for Si when using Ge.

Note that the same applies to the material of the second reproduction film 41 as in the first reproduction film 21.

[Example 4]

Further, the optical information recording medium 60 of the present embodiment is not limited to the structure of the above-described Example 1 medium, Example 2 medium, and Example 3 medium.

For example, in the optical information recording medium 60 of this example (hereinafter referred to as “Example 4 medium” in this example), what is the thickness of the first reproducing film 21? Even if it is a material, when the first information recording layer 20 is reproduced, the super-resolution characteristics of the first information recording layer 20 are produced, and sufficient reproduction durability is provided. Enough when focused on playback light In addition, any film thickness may be used as long as the second information recording layer 40 has super-resolution characteristics.

[0076] For example, the first information recording layer 20 in the medium of Example 4 is made of the same material (Si) as the first information recording layer 20 in the medium of Example 1 having the best super-resolution characteristics currently available. In that case, the transmittance of the first information recording layer 20 at the wavelength of the reproduction light, which is blue laser light, and the mark length below the optical resolution limit of the reproduction device in the first information recording layer 20 are 0 .: L Figure 8 shows the results of measuring the CZN relationship at m. As shown in FIG. 8, the super-resolution characteristics of the first information recording layer 20 can be sufficiently confirmed when the transmittance of the first information recording layer 20 is in the transmittance range of 5.7% to 53.5%. Has a CZN of 30 dB or more.

[0077] Also, in this case, a double-layer super-resolution optical information recording medium having the first information recording layer 20 having three kinds of transmittances (5.7%, 39.8%, and 53.5%) is manufactured. Figure 9 shows the results of confirmation of reproduction durability at 0.1 μm, which is the mark length below the optical resolution limit of the reproduction device in the first information recording layer 20. As can be seen from FIG. 9, when the transmittance of the first information recording layer 20 is 5.7% and 39.8%, the optical resolution limit of the playback device is maintained even during continuous playback of 20,000 times. The CZN at 0.1 m, which is the mark length below the boundary, is less than 30 dB, which indicates a good regeneration durability. On the other hand, when the transmittance of the first information recording layer 20 is 53.5%, the track servo is disconnected when the number of playbacks exceeds 10,000, so data measurement cannot be performed for 20,000 playbacks. The reproduction durability was bad. Therefore, in order to satisfy the above-mentioned necessary condition of the first information recording layer 20, it is preferable that the transmittance is smaller than 53.5%.

Further, for example, the second information recording layer 40 of the medium of Example 4 is the same film structure as that of the second information recording layer 40 of Example 1 medium that is currently obtained and has the best super-resolution characteristics. In this case, the relationship between the transmittance of the first information recording layer 20 and the CZN at 0.1 μm, which is the mark length below the optical resolution limit of the reproducing device in the second information recording layer 40, is shown. Figure 10 shows the measurement results. As shown in FIG. 10, when the transmittance of the first information recording layer 20 at the reproducing light wavelength is 20%, the mark length is equal to or less than the optical resolution limit of the reproducing device in the second information recording layer 40. 0.1 7 at 111 is reduced to 30 dB or less where the characteristics can be fully confirmed. Therefore, in order to satisfy the necessary condition of the first information recording layer 20, the transmittance is preferably larger than 20%. Thus, the thickness of the first reproduction film 21 is limited by the transmittance. FIG. 11 shows the relationship between the film thickness of Si that is the first reproduction film 21 and the transmittance of the first information recording layer 20 at the reproduction light wavelength that is blue laser light. When Si is used for the first reproducing film 21, it is preferable that it is thicker than 5 nm and thinner than 17 nm, as can be seen from FIG. The same can be said when Ge is used. Thereby, the transmittance can be satisfied, and the super-resolution characteristics and the reproduction durability in the first information recording layer 20 and the second information recording layer 40 can be obtained.

[0080] (Example 5)

Further, the optical information recording medium 60 of the present embodiment is not limited to the structure of each example medium described above.

For example, in the optical information recording medium 60 of this example (hereinafter referred to as “Example 5 medium” in this example), the film thickness of the second reproducing film 41 is not limited. Even if it is a material, when the second information recording layer 20 is reproduced, it should be a film thickness that provides the super-resolution characteristics of the second information recording layer and has sufficient reproduction durability.

[0082] For example, the second information recording layer 40 in the medium of Example 5 is the same material (Si) as the second information recording layer 40 in the medium of Example 1 because of the highest super-resolution characteristics currently obtained. The relationship between the film thickness of Si as the second playback film 41 and the CZN at 0.1 μm, which is the mark length below the optical resolution limit of the playback device in the second information recording layer 40 Figure 12 shows the measurement results. At this time, the transmittance of the first reproduction film 21 with respect to the reproduction light wavelength, which is blue laser light, is 20% or more. As shown in FIG. 12, when Si is used for the second reproducing film, it has a CZN of 30 dB or more at which the super-resolution characteristics of the second information recording layer 40 can be sufficiently confirmed when the thickness of the Si film is 5 nm or more.

[0083] In addition, at this time, a two-layer super-resolution optical information recording medium having the thickness of each of the three types of Si (5 nm, lOnm, 50 nm) as the thickness of the second reproducing film 41 was fabricated, and the second information recording layer Figure 13 shows the results of confirmation of reproduction durability at a mark length of 0.1 µm, which is below the optical resolution limit of 40 playback devices. As can be seen from FIG. 13, when the film thickness of the second playback film, Si, is lOnm and 50 nm, CZN does not fall below 30 dB even during continuous playback of 20,000 times. Shows durability. On the other hand, when the film thickness of Si, which is the second playback film 41, is 5 nm, the track servo was released when the playback count exceeded 10,000, so the playback speed Data measurement of several 20,000 times was impossible, and reproduction durability was bad. Therefore, in order to satisfy the necessary condition of the second information recording layer 40, the thickness of the second reproducing film 41 needs to be larger than 5 nm.

Note that the same can be said when Ge is used.

Thereby, better super-resolution characteristics and reproduction durability in the second information recording layer 40 can be obtained.

[0086] (Example 6)

For example, in the optical information recording medium 60 of this example (hereinafter referred to as “Example 6 medium” in this example), as shown in FIG. The first reproduction film 21 has a first protective film 22 for preventing reproduction degradation of the first reproduction film 21 on the incident light side of the reproduction light with respect to the first reproduction film 21, and the second information recording The layer 40 may include a second reproducing film 41 and a second protective film 42 for preventing reproduction degradation of the second reproducing film 41 on the incident light side of the reproducing light with respect to the second reproducing film 41. An optical information recording medium 60 according to this example shown in FIG. 14 has silicon nitride (film thickness: 40 nm) as the first protective film 22, and silicon nitride (film thickness: 155 nm) as the second protective film 42. Except for the first protective film 22 and the second protective film 42, members having the same reference numerals as those of the optical information recording medium 60 shown in Example 1 have the same material and film thickness.

FIG. 15 shows the mark lengths below the optical resolution limit of the reproducing apparatus in each of the first information recording layer 20 of the medium of Example 1 and the first information recording layer 20 of the medium of Example 6. The following shows the results of comparison between the initial CZN and the CZN after 20,000 times after continuous playback of 20,000 times at μm. FIG. 16 shows the mark lengths below the optical resolution limit of the reproducing apparatus in each of the second information recording layer 40 of the medium of Example 1 and the second information recording layer 40 of the medium of Example 6. The following shows the results of comparison between the initial CZN and the CZN after 20,000 times after continuous playback of 20,000 times at μm.

As can be seen from FIGS. 15 and 16, both the first information recording layer 20 and the second information recording layer 40 have a first protective film 22 for protecting the first reproducing film 21 and a second reproducing film 41. Example 6 media each having a second protective film 42 for protecting the first and second protective films 22, 42 Example 1 It can be seen that the reproduction durability is improved from the medium.

The material and film thickness of the first and second protective films 22 and 42 are 40 nm thick silicon nitride films as the first protective film 22 in this embodiment, and the second protective film 42 Although a silicon nitride film with a film thickness of 155 nm is employed, the present invention is not limited to this, and any film having a function of protecting the reproduction film may be used. However, the material of the first and second protective films 22 and 42 is preferably a material that transmits the reproduction light of the blue laser light. The material is preferably a material whose optical constant at the blue laser wavelength does not change with temperature. For example, the material may be aluminum nitride or ZnS—SiO. The film thickness of the first and second protective films 22, 42

2

If the film is too thin, the protective film functions poorly, and the material of the protective film is blue laser light. However, if the thickness is too thick, it takes a long time to form a film, resulting in poor productivity. Therefore, for example, the thickness of the first and second protective films 22 and 42 is preferably 5 nm or more and less than 500 nm.

In the present embodiment, both the first information recording layer 20 and the second information recording layer 40 have the first and second protective films 22 and 42. However, the present invention is not limited to this. A configuration having the first protective film 22 only in the information recording layer 20 may be employed, or a structure having the second protective film 42 only in the second information recording layer 40 may be employed. For example, it is judged that the reproduction durability of one information recording layer is sufficiently good even if it does not have a protective film, and the reproduction durability is poor unless the other information recording layer has a protective film! If judged, the reproduction durability is poor, and a structure having a protective film only on the information recording layer can be obtained. In such a configuration, productivity can be improved because one step of forming a protective film can be omitted, compared to a configuration in which both information recording layers have protective films.

Thereby, good reproduction durability can be obtained in each of the first information recording layer 20 and the second information recording layer 40.

[0093] In addition, in the structure of the media in the first to sixth embodiments, the characteristics as described above are not greatly lost even when another film or the like is added to each information recording layer 20, 40. ,.

[Embodiment 2]

An embodiment of the present invention will be described with reference to FIG. For convenience of explanation, members having the same functions as those used in Embodiment 1 are denoted by the same reference numerals. A description thereof will be omitted.

FIG. 17 shows a cross-sectional structure of a two-layer super-resolution optical information recording medium 61 according to the present embodiment.

As shown in FIG. 17, the optical information recording medium 61 includes a translucent layer 10, a first information recording layer 20, an intermediate layer 30, a second information recording layer 90, and a substrate 50. They are stacked in this order from the light incident surface.

[0097] The first information recording layer 20 is capable of reproducing a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with blue laser light, and is essential for at least super-resolution reproduction. The first reproduction film 21 is included. The material of the first reclaimed film 21 may be a simple element film such as Ni, Mo, W, Mn, Pt, C, Zr, In, Al, Cu, Fe, Co or a compound of a relatively thin film thickness. Although it is good, it is preferable that it is composed of a simple substance of Si or Ge, or an alloy or a mixture based on these.

The second information recording layer 90 includes a reflective film 91 having a function of reflecting reproduction light that is blue laser light. The reflective film 91 does not need to have super-resolution characteristics that enable reproduction of a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light.

[0099] The reflective film 91 is formed by, for example, a sputtering method in a sputtering apparatus.

[0100] As described above, the optical information recording medium 61 reproduces, in the first information recording layer 20, a signal having a mark length shorter than the optical resolution limit of the reproducing apparatus that reproduces with the reproducing light of the blue laser light. The first reproducing film 21 which is possible and at least essential for super-resolution reproduction is provided.

[0101] Thereby, the substantial recording density (meaning the reproducible recording density) of the first information recording layer 20 is limited by the resolution limit of the reproducing apparatus that reproduces with the reproducing light of the blue laser beam. It is higher than the recording density. Therefore, as compared with the super-resolution media of Patent Documents 1 and 2, the recording capacity can be improved because there are more information recording layers. Furthermore, when producing recording media having the same recording capacity, the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Patent Document 3 in which each information recording layer has a recording density limited by the resolution limit. Possible The Therefore, the number of expensive vacuum apparatuses for forming the recording layer by sputtering in the production line can be reduced, and the production cost of the recording medium accompanying the increase of the recording layer can be greatly reduced.

[0102] In addition, in the super-resolution technique using the mask layer as in Patent Document 1, a reflective film is required in addition to the mask layer, but according to the above configuration, the function of the reflective film is achieved by the reproducing film itself. Therefore, the cost can be reduced.

[0103] The material of the first reproduction film 21 is an inorganic material as described above, and is generally more stable than an organic material. Further, as will be described later in Examples, a blue laser not shown in Patent Document 2 shows good super-resolution characteristics and reproduction durability. Therefore, compared with the super-resolution technique disclosed in Patent Document 1 and Patent Document 2, a super-resolution technique with improved reproduction durability becomes possible.

Further, the first and second information recording layers 20 and 40 both include the first and second reproduction films 21 and 41 having super-resolution characteristics, respectively, and the light described in the first embodiment Compared to the information recording medium 60, the optical information recording medium 61 of the present embodiment includes the first information recording layer 20 including the first reproducing film 21 having super-resolution characteristics, while the second information recording layer 90 Therefore, the recording capacity is inferior to that of the optical information recording medium 60 described in the first embodiment. However, in the optical information recording medium 60 in Embodiment 1, the conditions of the first information recording layer 20 must be determined under conditions that maintain the super-resolution characteristics and reproduction durability in the second information recording layer 40. On the other hand, in the above configuration, since the restriction on the conditions of the first information recording layer 20 is relaxed, the degree of freedom of the material and film thickness of the first reproducing film 21 of the first information recording layer 20 is improved.

[0105] (Example 7)

The optical information recording medium 61 according to the present embodiment shown in FIG. 17 includes a first transparent film 10 having a polycarbonate film 11 (film thickness: 80 m) and a transparent adhesive resin layer 12 (film thickness: 20 m). The first reproducing film 21 (Si, film thickness: 7 nm) as the information recording layer 20, the transparent ultraviolet curable resin (film thickness: 25 m) as the intermediate layer 30, and the reflective film as the second information recording layer 90 It has a structure in which 91 (Ni, film thickness: 30 nm) and a polyolefin-based resin substrate as the substrate 50 are laminated in this order from the light incident surface. [0106] The OTF indicating the super-resolution characteristics of the first information recording layer 20 is substantially the same as the OTF of the first information recording layer 20 of the optical information recording medium 60 of Example 1 shown in Fig. 4 (a). there were.

In the optical information recording medium 61 of this example (hereinafter referred to as “Example 7 medium” in this example), the thickness of the first reproduction film 21 can be determined as follows. The film thickness is such that when information in the first information recording layer 20 is reproduced, the super-resolution characteristics of the first information recording layer 20 occur and sufficient reproduction durability is obtained regardless of the material. In addition, when the information in the second information recording layer 90 is reproduced, the film thickness is such that the information in the second information recording layer 90 can be reproduced.

[0108] For example, the first information recording layer 20 in the Example 7 medium is made of the same material (Si) as the first information recording layer 20 in the Example 1 medium having the best super-resolution characteristics currently available. In this case, the transmittance of the first information recording layer 20 at the reproduction light wavelength, which is blue laser light, and a mark length of 0.1 m that is less than the optical resolution limit of the reproduction device in the first information recording layer 20 The result of measuring the relationship of CZN was the same as that shown in FIG. As can be seen from FIG. 8, the super-resolution characteristics of the first information recording layer 20 are sufficiently confirmed in the transmittance range of the first information recording layer 20 from 5.7% to 53.5%. It has a C / N of 30 dB or higher.

[0109] Also, in this case, a two-layer super-resolution optical information recording medium having the first information recording layer 20 having three kinds of transmittances (5.7%, 39.8%, and 53.5%) is manufactured. The result of confirming the reproduction durability at a mark length of 0.1 μm, which is below the optical resolution limit of the reproduction apparatus, was the same as that shown in FIG. As can be seen from FIG. 9, when the transmittance of the first information recording layer is 5.7% and 39.8%, the optical resolution limit of the playback device is maintained even during continuous playback of 20,000 times. The following mark length of 0.1 m, CZN is less than 30 dB, which indicates a good reproduction durability. On the other hand, when the transmittance of the first information recording layer is 53.5%, the track servo is disconnected when the number of playbacks exceeds 10,000, so data measurement of 20,000 playbacks is impossible. Yes, reproduction durability was bad. Therefore, in order to satisfy the above-mentioned necessary conditions for the first information recording layer 20, the transmittance needs to be smaller than 53.5%.

[0110] In addition, when reproducing the second information recording layer, since light is transmitted through the first information recording layer, if the transmittance of the first information recording layer 20 is less than 5%, the second information recording layer Return light from Becomes so small that the signal of the second information recording layer cannot be reproduced. Therefore, the transmittance of the first information recording layer 20 needs to be greater than 5%.

[0111] Thus, the film thickness of the first reproduction film 21 is limited by the transmittance. First regeneration membrane 2

The relationship between the film thickness of Si, which is 1, and the transmittance of the first information recording layer 20 at the reproduction light wavelength, which is blue laser light, was the same as that shown in FIG. Therefore, the first regeneration membrane

When Si is used for 21, as shown in Fig. 11, the thickness of the first regenerative film must be thicker than 5 nm and thinner than 65 nm. The same is true when Ge is used. Thereby, the transmittance can be satisfied, and the super-resolution characteristics and the reproduction durability in the first information recording layer 20 can be obtained.

[0112] In the optical information recording medium 61 of the present example, the transparent layer 10 may be the transparent substrate 13 used for the transparent layer 10 of the optical information recording medium 60 of Example 2 described above. Alternatively, a structure including the transparent substrate 13 may be used.

[Embodiment 3]

An embodiment of the present invention will be described with reference to FIG. For convenience of explanation, members having the same functions as those used in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

FIG. 18 shows a cross-sectional structure of a two-layer super-resolution optical information recording medium 62 according to the present embodiment.

As shown in FIG. 18, the optical information recording medium 61 includes a light-transmitting layer 10, a first information recording layer 80, an intermediate layer 30, a second information recording layer 40, and a substrate 50. They are stacked in this order from the light incident surface.

[0116] The second information recording layer 40 is capable of reproducing a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with blue laser light, and is essential for at least super-resolution reproduction. The second regeneration film 41 is included. The material of the second regenerative film 41 may be a simple element film such as Ni, Mo, W, Mn, Pt, C, Zr, In, Al, Cu, Fe, Co or a compound of a relatively thin film thickness. Although it is good, it is preferable that it is composed of a simple substance of Si or Ge, or an alloy or a mixture based on these.

[0117] The first information recording layer 80 is a reflective film having a function of reflecting reproduction light that is blue laser light. Includes 81. The reflective film 81 does not need to have super-resolution characteristics that enable reproduction of a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light.

[0118] The reflective film 81 is formed by, for example, a sputtering method in a sputtering apparatus.

As described above, the optical information recording medium 62 reproduces, in the second information recording layer 40, a signal having a mark length shorter than the optical resolution limit of the reproducing apparatus that reproduces with the reproducing light of the blue laser light. A second reproducing film 41 that is possible and at least essential for super-resolution reproduction is provided.

Thus, the substantial recording density (meaning the reproducible recording density) of the second information recording layer 40 is limited by the resolution limit of the reproducing apparatus that reproduces with the reproducing light of the blue laser light. It is higher than the recording density. Therefore, as compared with the super-resolution media of Patent Documents 1 and 2, the recording capacity can be improved because there are more information recording layers. Furthermore, when producing recording media having the same recording capacity, the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Patent Document 3 in which each information recording layer has a recording density limited by the resolution limit. It becomes possible. Therefore, the number of expensive vacuum apparatuses for forming the recording layer by sputtering in the production line can be reduced, and the production cost of the recording medium accompanying the increase in the recording layer can be greatly reduced.

[0121] In addition, in the super-resolution technique using the mask layer as in Patent Document 1, a reflective film is required in addition to the mask layer, but according to the above configuration, the function of the reflective film is achieved by the reproducing film itself. Therefore, the cost can be reduced.

[0122] Further, as described above, the material of the first reproduction film is an inorganic substance, and is generally more stable than an organic substance. Further, as will be described later in Examples, the super-resolution characteristics and reproduction durability that are not disclosed in Patent Document 2 but are good with a blue laser are shown. Therefore, compared with the super-resolution technique disclosed in Patent Document 1 and Patent Document 2, a super-resolution technique with improved reproduction durability becomes possible.

[0123] In addition, compared with the optical information recording medium 60 described in the first embodiment, each of the first and second information recording layers includes a reproducing film having super-resolution characteristics. Light of form In the information recording medium 62, the second information recording layer 40 includes a second reproducing film 41 having super-resolution characteristics, while the first information recording layer 80 does not include a reproducing film having super-resolution characteristics. The capacity is inferior to that of the optical information recording medium 60 described in the first embodiment. However, in the optical information recording medium described in the first embodiment, the conditions of the second information recording layer 20 must be determined under conditions that maintain the super-resolution characteristics and the reproduction durability in the first information recording layer 20. On the other hand, in the above configuration, since the restriction on the conditions of the second information recording layer 40 is relaxed, the degree of freedom of the material and film thickness of the second reproducing film 41 of the second information recording layer 40 is improved.

[0124] (Example 8)

The optical information recording medium 62 according to the present embodiment shown in FIG. 18 includes a first transparent film 10 having a polycarbonate film 11 (film thickness: 80 m) and a transparent adhesive resin layer 12 (film thickness: 20 m). The reflective film 81 (Au, film thickness: 20 nm) in the information recording layer 80, the transparent ultraviolet-cured resin (film thickness: 25 μηι) as the intermediate layer 30, and the reflective film in the second information recording layer 40 as the reflective film. (2) A reproduction film 41 (Si, film thickness: 50 nm) and a polyolefin-based resin substrate as the substrate 50 are provided, and the layers are laminated in this order from the light incident surface.

[0125] The OTF indicating the super-resolution characteristics of the first information recording layer 40 is substantially the same as the OTF of the second information recording layer 40 of the optical information recording medium 60 of Example 1 shown in Fig. 4 (b). there were.

The present embodiment is not limited to this example.

[0127] Although each of the media of Embodiments 1 to 3 and Examples 1 to 8 is a reproduction-only optical information recording medium, the optical information recording medium of the present invention is not limited to this. This includes recording Z playback type optical information recording media and write-once type optical information recording media. In these cases, at least a recording film is added to each information recording layer.

[0128] Furthermore, the present invention can be applied to a multilayer optical information recording medium having three or more layers as long as the cost and recording capacity can be balanced.

[0129] As optical information recording media, CD-ROM (Compact Disk Read Only Memory), CD-R (Compact Disk Recordable), CD-RW (Compact Disk Rewritable), DVD-ROM (Digital Versatile Disk Read Only) Memory), DVD—RW (Digital Versatile Disc Rewritable), BD (Blu-ray Disc), BD (Blu-ray Disc) —ROM and other optically readable discs, magneto-optical discs, phase change discs, etc. Optical information for various optical discs It can be listed as a recording medium format. The present invention does not ask the recording method or size.

[0130] Further, as is clear from the above description, the optical information recording medium 60, 61, 62 is used to reproduce information from the optical information recording medium recorded at a higher density. It can be seen that stable information reproduction is possible.

[0131] In the optical information recording medium 62 of the present embodiment, the light transmissive layer 10 may be the transparent substrate 13 used for the light transmissive layer 10 of the optical information recording medium 60 of the above-described second embodiment. Alternatively, a structure including the transparent substrate 13 may be used.

[Embodiment 4]

One embodiment of the present invention will be described with reference to FIGS. 19 and 20.

In the present embodiment, an optical information recording medium playback device for playing back the optical information recording media 60, 61, 62 described in the first embodiment will be described. FIG. 19 is a diagram showing a schematic configuration of the optical information recording medium reproducing apparatus 100. As shown in FIG.

As shown in FIG. 19, the present optical information recording medium reproducing device 100 irradiates the optical information recording medium 60, 61, 62 with a light beam and detects the reflected light. This is a device for reproducing information recorded on the information recording medium 60, 61, 62. In the present embodiment, the case where the optical information recording media 60, 61, 62 are disc-shaped optical discs will be described. However, the optical information recording media 60, 61, 62 are not necessarily disc-shaped optical discs. .

As shown in FIG. 19, the optical information recording medium reproducing device 100 rotates the optical information recording media 60, 61, 62 by the spindle motor 101, and the optical information recording medium 60 by the optical pickup device 102. , 61 and 62 are read out. The control of the optical pickup device 102 and the spindle motor 101 is performed by the control unit 103.

The spindle motor 101 scans the optical spot on the optical information recording medium 60, 61, 62 by rotating the optical information recording medium 60, 61, 62.

[0137] The control unit 103 includes a signal processing unit 103a, a drive control unit 103b, and the like.

[0138] The signal processing unit 103a receives reflected light from the recording marks on the optical information recording medium 60, 61, 62. By detecting the record information based on the electrical signal from the optical pickup device 102 obtained as described above, the information recorded by the record mark on the optical information recording medium 60, 61, 62 is read. Further, the signal processing unit 103a is based on an electrical signal from the optical pickup device 102 obtained from the reflected light from the recording marks on the optical information recording medium 60, 61, 62, and a focus error signal and a tracking error described later. Generate a signal.

The drive control unit 103b drives the spindle motor 101 and the optical pickup device 102 based on an electrical signal read from the optical pickup device 102 and generated by the signal processing unit 103a or an external force instruction. A servo circuit is provided for control. In particular, the drive control unit 103b corrects the position of the objective lens 102e based on the focus error signal and tracking error signal from the signal processing unit 103a, and performs servo focusing for tracking and autofocusing the laser beam. A circuit is included as the servo circuit described above.

FIG. 20 is a diagram showing a configuration of the optical pickup device 102 mounted on the optical information recording medium reproducing device 100. As shown in FIG.

[0141] As shown in FIG. 20, the optical pickup device 102 includes a semiconductor laser 102a, a collimator lens 102b, a beam shaping prism (prism that makes the beam circular) 102c, a beam splitter 102d, an objective lens 102e, and a lens action. A ueator 102f and a detection optical system 102g are provided.

The optical pickup device 102 is a device that shapes the laser light emitted from the semiconductor laser 102a, which is a light source, into a beam shape and focuses it on the optical information recording medium 60, 61, 62. In this optical pickup device 102, a semiconductor laser 102a is used as a laser light source. However, the present invention is not limited to this, and other light sources may be used. Further, the laser power of the semiconductor laser 102a can be set higher than the conventional laser power in order to develop the super-resolution characteristics, and can be switched to the conventional laser power. As a result, reproduction with a double-layer super-resolution medium becomes possible, so reproduction using a double-layer super-resolution medium with the same recording capacity and lower cost than a four-layer normal medium becomes possible. In addition, since the number of layers is halved compared to the case of reproducing a four-layer normal medium having the same recording capacity, the number of times of focusing on each layer is reduced. Therefore, since the time required for focusing is shortened, the response to the playback command is improved. [0143] Laser light from the semiconductor laser 102a is converted into substantially parallel light by the collimator lens 102b, and is shaped by the beam shaping prism 102c so that the light intensity distribution becomes substantially circular. The substantially circular parallel light passes through the beam splitter 102d, and is then focused on the optical information recording medium 60, 61, 62 as a light beam (incident light) by the objective lens 102e. The numerical aperture (NA) of the objective lens 102e is set to 0.65 or 0.85.

[0144] Reflected light from the optical information recording media 60, 61, 62 is branched by the beam splitter 102d and guided to the detection optical system 102g. In the detection optical system 102g, the recorded information, defocus information, and track position deviation are determined from changes in the polarization direction of reflected light from the optical information recording media 60, 61, 62, and changes in reflected light intensity (level of reflected light level). Information is identified, and this information is converted into electrical signals. The converted electric signal is sent to the signal processing unit 103a.

[0145] The reflected light includes reflected light from an address information mark constituted by a part of the prepits 31, 51 provided on the optical information recording medium 60, 61, 62. The detection optical system 102g uses the electrical signal obtained from the reflected light, that is, the electrical signal obtained by reproducing the address information mark, to irradiate the optical beam on the optical information recording medium 60, 61, 62. A focus error signal and a tracking error signal for the optical information recording medium 60, 61, 62 of the light spot (light beam condensing portion) formed on the optical disc are detected.

[0146] The lens actuator 102f corrects the positional deviation of the light spot in the optical axis direction by feeding back the focus error signal. Thus, the optical pickup device 102 can form a light spot on the desired first information recording layer 20 or the second information recording layer 40 in the optical information recording medium 60, 61, 62. Further, the lens actuator 102f corrects the positional deviation of the light spot in the track width direction by feeding back the tracking error signal. As a result, the optical pickup device 102 can cause the optical spot to follow the target track in the optical information recording medium 60, 61, 62.

[0147] In the conventional multilayer optical information recording medium reproducing device, it is necessary to improve the performance of the pickup accompanied by an increase in cost in order to reproduce information by focusing the reproducing light on many recording layers. On the other hand, in the present optical information recording medium reproducing apparatus 100, reproduction is performed using the optical information recording medium 60, 61, 62 of the first embodiment. Therefore, the cost increase of the pickup device 102 can be suppressed. That is, a lower cost reproducing apparatus can be realized. In addition, the optical information recording medium reproducing apparatus 100 can perform stable information reproduction by using the optical information recording media 60, 61, 62 recorded at high density.

[0148] As described above, the optical information recording medium according to the present invention has at least a translucent layer, a first information recording layer, an intermediate layer mainly made of a resin, and a second layer from the reproduction light incident surface side. An optical information recording medium in which an information recording layer and a substrate are laminated in this order, and has a reproducing apparatus that reproduces with the reproducing light of the blue laser light in both the first and second information recording layers. It is characterized by the inclusion of a regenerative film made of inorganic material that can regenerate signals with a mark length shorter than the optical resolution limit.

In the above configuration, when reproducing the information recorded on the first information recording layer, the reproduction light of blue laser light is irradiated through the translucent layer and focused on the first information recording layer. Then, it is possible to read out information recorded with a mark length less than the resolution limit of the first information recording layer.

[0150] Further, when reproducing the information recorded in the second information recording layer, the reproduction light of the blue laser light is irradiated through the light transmitting layer, the first information recording layer, and the intermediate layer, Focus on the second information recording layer. Then, information recorded with a mark length less than the resolution limit of the second information recording layer can be read.

[0151] Thereby, in both the first and second information recording layers, the substantial recording density (meaning the reproducible recording density) is made higher than the recording density limited by the resolution limit. Therefore, as compared with the super-resolution medium of Patent Document 1, the recording capacity can be improved by having more information recording layers. Furthermore, when producing recording media having the same recording capacity, the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Patent Document 2 in which each information recording layer has a recording density limited by the resolution limit. Is possible.

[0152] As described above, the first and second information recording layers can read information by the super-resolution effect. As a result, the recording density of the first and second light-absorbing films is below the resolution limit, so that the recording capacity of the optical information recording medium can be improved with respect to the manufacturing cost, and a recording medium with high cost performance can be obtained. Can be provided. Therefore, the first and second information records By providing the recording layer, when producing a recording medium having the same recording capacity, the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Patent Document 2. Therefore, in the production line, the number of expensive vacuum devices for forming the recording layer by sputtering can be reduced, and the production cost of the recording medium accompanying the increase in the recording layer can be greatly reduced. . In addition, in the super-resolution technique using a mask layer as in Patent Document 1, a reflective film is required in addition to the mask layer. On the other hand, according to the above configuration, as will be described later in the embodiment, it is possible to reproduce a Mark Agency signal that is shorter than the optical resolution limit of a reproduction apparatus that reproduces with the reproduction light of blue laser light, and at least In order to perform super-resolution reproduction, it is only necessary to use a regenerative film that is not necessary for the reflective film, so that the cost can be reduced.

[0153] Further, as will be described later in Examples, the materials of the first and second reproduction films are inorganic materials, and are generally more stable than organic materials. Further, as will be shown later in Examples, the first and second reproduction films are blue lasers and exhibit good super-resolution characteristics and reproduction durability.

[0154] Further, as will be described later in the examples, unlike the mask type super-resolution medium in which the average reflectance of the pit portion is changed by the power of the laser beam as shown in Patent Document 1, the first and second In the reproduction film, the average reflectance of the pit portion with respect to the wavelength of the laser beam as the reproduction light hardly changes depending on the power of the laser beam as the reproduction light.

[0155] In the mask-type super-resolution medium, the amount of light per unit area increases as the laser beam power increases, and the associated temperature rise increases. The reflectance changes due to the power of. A similar phenomenon occurs when the focus servo is pulled into the information recording layer. When the amount of defocus of the information recording layer relative to the focal point of the pickup is large, the amount of light per unit area of the information recording layer is small, which is accompanied by this. Temperature rise is small. On the other hand, as the defocus amount decreases, the amount of light per unit area of the information recording layer increases, and the accompanying temperature increase also increases, so that the pseudo laser spot changes and the reflectance changes. For this reason, in the mask-type super-resolution medium, when the focus servo is pulled into the information recording layer, the reflectivity of the information recording layer changes depending on the relative position between the pickup and the information recording layer. Curve), the focus error signal is divided by the total amount of light. A circuit for calculating and standardizing is required. On the other hand, in the optical information recording medium of the present application, since the average reflectance of the pit portion with respect to the wavelength of the laser beam hardly changes depending on the temperature, the above-described circuit is not necessary, so that the reproduction apparatus is inexpensive. There is.

[0156] Also, in the mask-type super-resolution medium, the average reflectance of the pits changes because the beam spot size changes in a pseudo manner due to the power of the laser beam that is the reproduction light. Since the optimum beam spot varies depending on the laser beam, the optimum laser power varies depending on the mark length. For example, in a mask-type super-resolution medium, the signal quality with a mark length longer than the resolution limit deteriorates at the laser power at which marks below the resolution limit can be reproduced. On the other hand, in the optical information recording medium of the present application, the signal quality of the mark length longer than the resolution limit does not deteriorate even in the laser par where the mark below the resolution limit can be reproduced. This also has the effect that an optical information recording medium with better jitter can be obtained compared to a mask type super-resolution medium. Therefore, compared with the super-resolution technique disclosed in Patent Document 1, a super-resolution technique with improved reproduction durability becomes possible.

[0157] Further, the optical information recording medium according to the present invention includes, from the reproduction light incident surface side, at least a translucent layer, a first information recording layer, an intermediate layer mainly made of a resin, and a second information recording layer. And an optical information recording medium in which a substrate is laminated in this order, and the first information recording layer has a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with blue laser beam reproducing light. It can be characterized in that it contains a regenerative film made of an inorganic material that can regenerate the signal.

[0158] With the above configuration, only the first information recording layer can read information by the super-resolution effect, so that the recording capacity can be improved compared to the super-resolution medium of Patent Document 1, and the patent Although the number of recording layers can be reduced as compared with the multilayer optical information recording medium of Document 2, the recording capacity can be improved as compared with the above-described configuration in which both the first information recording layer and the second information recording layer have reproducing films. The amount is reduced. However, when both the first and second information recording layers include a reproducing film, the first information recording layer is recorded under conditions that maintain the super-resolution characteristics and the reproduction durability in the second information recording layer. Whereas the conditions of the layer must be determined, the above configuration relaxes the restrictions on the conditions of the first information recording layer, so the material and thickness of the reproduction film of the first information recording layer are free. The degree is improved.

[0159] Also, the optical information recording medium according to the present invention includes at least a translucent layer, a first information recording layer, an intermediate layer mainly made of resin, and a second information recording layer from the reproduction light incident surface side. And an optical information recording medium in which the substrate is laminated in this order, and the second information recording layer has a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light. It can be characterized in that it contains a regenerative film made of an inorganic material that can regenerate the signal.

[0160] In the above configuration, the recording capacity is smaller than in the above configuration in which the first information recording layer and the second information recording layer are both provided with the reproducing film, as in the configuration in which only the first information recording layer includes the reproducing film. However, the degree of freedom of the material and film thickness of the reproducing film of the second information recording layer is improved.

[0161] In the optical information recording medium having the reproducing film in both the first and second information recording layers, the first information recording layer is larger than 20% in the reproduction light wavelength of the blue laser light. It is preferable to have a transmittance of less than%. As a result, it is possible to obtain the super-resolution characteristics and good reproduction durability of the first information recording / reproducing layer without substantially degrading the super-resolution characteristics of the second information recording layer. Therefore, it is possible to improve the recording capacity of the optical information recording medium.

[0162] In the optical information recording medium having the reproducing film only on the first information recording layer, the first information recording layer is larger than 5% and smaller than 53.5% at the reproducing light wavelength of the blue laser light. It is preferable to have a high transmittance. This makes it possible to obtain the super-resolution characteristics and good reproduction durability of the first information recording / reproducing layer while making it possible to reproduce the signal of the second information recording layer. Therefore, the recording capacity of the optical information recording medium can be improved.

[0163] In the optical information recording medium, it is preferable that the reproducing film also has a simple substance of Si or Ge, or an alloy or a mixture of these as a main component. As a result, it is possible to obtain better super-resolution characteristics as compared with the reproduction film of other materials. Therefore, the recording capacity of the optical information recording medium can be further improved.

[0164] An optical information recording medium having a reproducing film in both the first and second information recording layers, and at least the reproducing film of the first information recording layer is a simple substance of Si or Ge, or a main component thereof. In an optical information recording medium comprising an alloy or mixture as a component, the reproducing film of the first information recording layer Preferably, the film thickness is greater than 5 nm and less than 17 nm. As a result, since the reproduction film of the first information recording layer has the minimum film thickness necessary for maintaining the reproduction durability, the reproduction durability of the first information recording layer is maintained, and the second information layer The super-resolution characteristics of the first information layer can be obtained without substantially degrading the super-resolution characteristics of the optical information recording medium, and the recording capacity of the optical information recording medium can be improved.

[0165] An optical information recording medium having a reproducing film in both the first and second information recording layers, and at least the reproducing film of the second information recording layer is a simple substance of Si or Ge, or a main component thereof. In an optical information recording medium made of an alloy or mixture as a component, it is preferable that the thickness of the reproducing film of the second information recording layer is greater than 5 nm. This makes it possible to obtain the super-resolution characteristics and good reproduction durability of the second information recording layer, and to improve the recording capacity of the optical information recording medium.

[0166] An optical information recording medium having a reproduction film only on the first information recording layer, wherein the reproduction film of the first information recording layer is composed of a simple substance of Si or Ge, or an alloy or mixture containing these as a main component. In the optical information recording medium, it is preferable that the reproducing film of the first information recording layer is thicker than 5 nm and thinner than 65 nm. As a result, the reproduction film of the first information recording layer has the minimum film thickness necessary for maintaining the reproduction durability. Therefore, the reproduction durability of the first information recording layer is maintained, and the second information It is possible to obtain a good super-resolution characteristic of the first information recording layer while making it possible to reproduce the signal of the recording layer, and to improve the recording capacity of the optical information recording medium.

[0167] The optical information recording medium preferably includes a protective film for preventing reproduction degradation of the reproduction film in the information recording layer. In this configuration, it is possible to obtain better super-resolution characteristics and better reproduction durability by having a protective film for preventing reproduction deterioration of the reproduction film. If the protective film is too thin, the protective film functions poorly. If the material of the protective film is not zero with respect to the reproduction light wavelength, which is blue laser light, the film thickness is increased. The thicker the film, the worse the utilization efficiency of the reconstructed light. Therefore, for example, the thickness of the protective film is preferably 5 nm or more and less than 500 nm.

[0168] In the optical information recording medium, the light transmitting layer is preferably a transparent substrate. This configuration Then, since it is only necessary to bond the two-layer structure, the optical information recording medium can be manufactured at a lower cost without using a complicated process such as 2P transfer for forming a multilayer structure. Further, since this structure conforms to the DVD standard, a high-density DVD (HD DVD) can be provided at low cost.

[0169] Further, the optical information recording medium reproducing apparatus according to the present invention provides the above-mentioned first or second information as the reproduction light of the laser beam having a laser power capable of reproducing any of the above-mentioned optical information recording media. It comprises an optical reading means for irradiating the recording layer and reading the reflected light from the optical information recording medium.

[0170] This optical information recording medium reproducing device irradiates the reflected light from the optical information recording medium by irradiating the reproducing light of the laser beam having a laser power capable of reproducing the optical information recording medium by the optical reading means. Since reading is performed, stable information reproduction from an optical information recording medium recorded with higher density becomes possible. In order to make such an optical information recording medium reproducible, the laser power must be higher than the conventional laser power, and if the laser power is too high, the playback film will be destroyed. Set to the value of the laser power. If the optical information recording medium can be reproduced in this way, it can be reproduced on a double-layer super-resolution medium. For example, if the recording procedure in a single layer of the optical information recording medium of the present application is double that of a normal medium due to the super-resolution effect, a two-layer super-resolution medium with the same recording capacity and lower cost than a four-layer normal medium will The reproduction using it becomes possible. Therefore, the number of information recording layers that must be focused is reduced compared to the reproduction of a multilayer optical information recording medium with an increased information recording density without using super-resolution technology. The number of times decreases. For example, the number of layers is halved and the number of times of focus is halved compared to the case of playing a four-layer normal medium with the same recording capacity. As a result, the focus control of the optical reading device (optical pickup) is simplified, so that an increase in cost of the optical reading device is suppressed and the time required for focusing is shortened, and the response to the reproduction command is improved. Therefore, a high-performance playback device can be provided at a lower cost.

[0171] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. Such embodiments are also included in the technical scope of the present invention. Industrial applicability

In the optical information recording medium of the present invention, in the information recording layer, by providing a light absorption film that collects the reproduction light and converts it into heat, and a reproduction film that changes the light transmittance of the portion heated by the heat, Since the production cost can be reduced, the information recording density can be improved, and the reproduction durability of the information recording layer can be improved, it can be suitably used for high density recording.

Claims

The scope of the claims

[1] Light in which at least a translucent layer, a first information recording layer, an intermediate layer mainly made of resin, a second information recording layer, and a substrate are laminated in this order from the reproduction light incident surface side. An information recording medium,

A reproduction film made of an inorganic material that can reproduce a signal having a mark length shorter than the optical resolution limit of a reproduction apparatus that reproduces with the reproduction light of blue laser light is formed on both the first and second information recording layers. An optical information recording medium comprising the optical information recording medium.

[2] Light in which at least a light transmitting layer, a first information recording layer, an intermediate layer mainly made of resin, a second information recording layer, and a substrate are laminated in this order from the reproduction light incident surface side. An information recording medium,

The first information recording layer includes a reproducing film made of an inorganic material capable of reproducing a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light! An optical information recording medium.

[3] Light in which at least a translucent layer, a first information recording layer, an intermediate layer mainly made of resin, a second information recording layer, and a substrate are laminated in this order from the reproduction light incident surface side. An information recording medium,

The second information recording layer includes a reproducing film made of an inorganic material capable of reproducing a signal having a mark length shorter than the optical resolution limit of a reproducing apparatus that reproduces with the reproducing light of blue laser light! An optical information recording medium.

4. The optical information recording medium according to claim 1, wherein the first information recording layer has a transmittance of greater than 20% and less than 53.5% at a reproduction light wavelength.

5. The optical information recording medium according to claim 2, wherein the first information recording layer has a transmittance of greater than 5% and less than 53.5% at a reproduction light wavelength.

6. The reproduction film of the first information recording layer and Z or the second information recording layer is made of a simple substance of Si or Ge, or an alloy or mixture containing these as a main component. 5. The optical information recording medium according to item 1 above.

[7] Of the reproducing film, at least the reproducing film of the first information recording layer is a simple substance of Si or Ge.

Or an alloy or mixture containing these as a main component, and the reproducing film of the first information recording layer 5. The optical information recording medium according to claim 1, wherein the film thickness is greater than 5 nm and less than 17 nm.

[8] Of the reproducing film, at least the reproducing film of the second information recording layer is made of Si or Ge alone, or an alloy or mixture containing these as a main component, and the reproducing of the second information recording layer is performed. 5. The optical information recording medium according to claim 1, wherein the film thickness is greater than 5 nm.

[9] The reproducing film of the first information recording layer is a simple substance of Si or Ge, or an alloy or a mixture of these as a main component, and the thickness of the reproducing film of the first information recording layer is thicker than 5 nm. 6. The optical information recording medium according to claim 2, wherein the optical information recording medium is thinner than 5 nm.

10. The optical information recording medium according to any one of claims 1 to 9, wherein the information recording layer includes a protective film for preventing reproduction degradation of the reproduction film.

11. The optical information recording medium according to claim 10, wherein the protective film has a thickness of 5 nm or more and less than 500 nm.

12. The optical information recording medium according to claim 1, wherein the light transmissive layer is a transparent substrate.

[13] The first or second information recording layer is irradiated with reproduction light of a laser beam having a laser power capable of reproducing the optical information recording medium according to any one of claims 1 to 12, and the light is recorded. An optical information recording medium reproducing device comprising optical reading means for reading reflected light of an information recording medium force.