JP2001101713A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask layer in which recording information can securely be recorded and reproduced without damaging the information when an information signal is optically recorded an reproduced with high density (super resolution). SOLUTION: Guide grooves for tracking servo are formed on one face 2a of a transparent disk substrate 2, and a mask layer 4 which increases the transmittance for light by temperature increase when the intensity of irradiation light of laser light L increases and a recording layer 6 in which information signals are recorded and reproduced are successively laminated on the one face 2a of the substrate. In this optical disk, the spot diameter of the laser light L irradiating the other face 2b of the transparent disk substrate 2 is substantially reduced while the light passes the mask layer 3, and the laser light with the reduced spot diameter enters the recording layer 6. The mask layer 4 consists of a reproducing mask layer 4A deposited as a film on the disk substrate 2, and a recording mask layer 4B deposited as a film on the reproducing mask layer 4A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk capable of optically recording and reproducing information signals at high density (super-resolution), and particularly to a reproducing mask layer and a recording mask layer on a transparent disk substrate. The present invention relates to an optical disc on which a mask layer made of and a recording layer are sequentially laminated to form a film.

[0002]

2. Description of the Related Art Generally, an optical disk is known as a recording / reproducing medium capable of recording / reproducing a large amount of information signals and having a short access time. There is a demand for further high-density recording / reproducing (super-resolution recording / reproducing) using. Recording and reproduction in the following description means recording an information signal, reproducing an information signal, and reproducing while recording an information signal. For example, the following method has been proposed as a method for optically recording and reproducing an information signal on an optical disk at a high density.

[0003] That is, this method includes (a) shortening the wavelength of a laser beam for recording and reproduction, (b) increasing the NA (numerical aperture) of an objective lens focused on an optical disk, and (c) information. Making the recording layer for recording signals a multi-layer; (d) multiplexing recording by changing the wavelength of the laser light to be recorded; (e) forming a mask layer to substantially reduce the light spot diameter of the laser light. There is a method of doing. Among these methods, a method of forming a mask layer to substantially reduce the spot diameter of a laser beam is described in, for example, JP-A-5-12673, JP-A-5-12715, and JP-A-5-28498. JP-A-5-2853
No. 5, JP-A-5-73961, JP-A-5-2
No. 34126 and JP-A-8-315419.

FIG. 16 is an enlarged sectional view schematically showing a conventional optical disk, FIG. 17 is a diagram showing the relationship between the temperature of a mask layer and the light transmittance of the conventional optical disk, and FIG.
3A and 3B are schematic diagrams of an intensity distribution of light incident on a mask layer and an intensity distribution of light transmitted through the mask layer in a conventional optical disk, and FIG. FIG. 19B is a diagram showing the light intensity distribution in the radial direction of the optical disk, and FIG.
FIG. 4 is a diagram illustrating a relationship between a light spot of a laser beam incident on a mask layer and a light spot transmitted through the mask layer, which absorbs light and raises the temperature to increase the transmittance.

A conventional optical disk D11 having the above-mentioned mask layer is formed, for example, as shown in FIG. 16, and has a mask-like layer 4 on a disk-shaped transparent disk substrate (hereinafter referred to as a transparent substrate) 2. The recording layer 6 and the protective layer 8 are formed by sequentially laminating and forming a film. The mask layer 4 is used when the laser light L is not irradiated from the transparent substrate 2 side or when the laser light L from the transparent substrate 2 side is not irradiated.
When the light intensity of the laser light L is low, the transmittance decreases. On the other hand, when the light intensity of the laser light L from the transparent substrate 2 side increases, the mask layer 4 optically absorbs the light and the temperature rises. As a result, the light transmittance increases as shown in FIG. 17, and the spot diameter transmitted through the mask layer 4 becomes substantially smaller as shown in FIG.

That is, in the light intensity distribution characteristics of the laser light L shown in FIGS. 18A and 18B, the intensity distribution of the light transmitted through the mask layer 4 is different from the intensity distribution of the light incident on the mask layer 4. And the small pits can be recorded and reproduced using the mask effect. FIG. 19 shows the state of the light spot of the laser light appearing on the optical disk surface when this mask effect is used.
At this time, the state shown in FIG. 18A corresponds to the state in the rotation direction of point B described later in FIG.
The state shown in FIG. 8B corresponds to the state in the radial direction at point B in FIG.

As shown in FIG. 19, when a laser beam having a constant intensity is continuously irradiated in a spot shape while rotating the optical disk in the direction of the arrow, for example, point B on the optical disk is point A of circular light spot S. Light of an intensity obtained by integrating the light intensity from point to point B is applied. The temperature rises by the heat obtained by subtracting the heat lost by heat conduction and radiation from the heat converted by absorbing the light, thereby increasing the transmittance of the mask layer. Therefore, the portion where the transmittance increases in the light spot S is behind the spot diameter (the downstream side) in the rotation direction of the optical disk, and the spot diameter of the laser beam is substantially reduced. FIG.
In FIG. 9, a portion of an area C indicated by oblique lines in the light spot S indicates a mask transmitted light spot transmitted through the mask layer, and an area D excluding the area C indicates a light spot not transmitted through the mask layer. Is shown. By forming the mask layer in this manner, the spot diameter of the laser beam is substantially reduced, and high-density optical disk recording / reproduction becomes possible.

[0008]

By the way, the mask layer 4
For example, Japanese Patent Application Laid-Open No. 5-73661 describes that a temperature range in which recorded information is not destroyed during reproduction can be set by using In in a mask layer. However, the reproduction without losing the recorded information recorded on the optical disk at the irradiation light intensity (reproduction power) at the time of reproduction at which the mask effect is the best at the time of reproduction is due to the material of the mask layer and the material of the recording layer. Although it depends on the characteristics, it does not always work in reality, and there is a problem that recorded information is destroyed during reproduction.
Although the recorded information is not completely destroyed, the reproduced output may be gradually attenuated during repeated reproduction. Further, in an experiment using AgInSbTe as the recording material of the recording layer, In could not be used.

Japanese Unexamined Patent Publication No. Hei 5-234136 discloses that, with respect to the intensity of irradiation light, it has two or more nonlinear transmission characteristics or reflection characteristics, It describes the regulation of the spot diameter and the regulation of the spot diameter for the weak irradiation light used when reproducing the information signal. The irradiation light intensity at the time of recording and the irradiation light intensity at the time of reproduction of the laser light differ by about 10 times, depending on the characteristics of the recording material of the recording layer. For example, in the case of an AgInSbTe-based material that is a phase change recording material, the irradiation light intensity during recording is about 12 mw, and the irradiation light intensity during reproduction is about 0.7 mw. In the case of TeGeSb, which is also a phase change recording material,
The irradiation light intensity at the time of recording is about 15 mw, and the irradiation light intensity at the time of reproduction is about 1 mw. Thus, when the irradiation light intensity at the time of recording of laser light and the irradiation light intensity at the time of reproduction are largely different, if the masking effect is made sufficient at the time of recording, the light attenuation by the mask material at the time of reproduction becomes too large, Not enough playback output. In particular, when a mask material for forming a mask layer is coated on a light-incident side on a transparent substrate and a method of detecting reflected light, which is a general optical disk detection method, both at the time of incidence and at the time of reflection. Since the light entering the mask layer is attenuated, it cannot be practically used.

Furthermore, Japanese Patent Application Laid-Open No. 8-315419 discloses that a heat insulating layer is formed between the mask layer and the recording layer so that the heat of the recording layer does not affect the mask layer. It is indicated that it is preferable to form a resin film that does not easily conduct heat. Furthermore, the above-mentioned publication discloses that the reverse photochromic mask layer uses a reverse photochromic as a mask layer and the effect of the reverse photochromic mask layer is reduced by heat. However, according to an experiment performed by the present inventors, such a problem did not occur. In the experiments of the present inventor, the problem that recorded information was destroyed by heat due to light passing through the mask layer was greater.

Therefore, in the optical disk having the mask layer formed thereon, although the spot diameter of the laser beam is substantially reduced, and the information signal can be recorded and reproduced at a high density, the following two problems are raised from the above publications. There is a point.

First, the first problem is in the reproduction of an optical disk having a mask layer. The reproduction irradiation light intensity at which the mask effect is the best at the time of reproduction does not destroy the recorded information recorded on the optical disk. In the case where a rewritable phase change material is used as a recording material for reproduction, when the irradiation light intensity at the time of reproduction is increased, the recorded information recorded in an amorphous state is gradually crystallized, and the recorded information is destroyed.

The second problem is that the irradiation light intensity at the time of recording is larger than the irradiation light intensity at the time of reproduction. Therefore, if the mask effect is made to be large at the time of reproduction, the mask effect at the time of recording will be almost zero. Will be gone. Conversely, if the effect of the mask effect is made large at the time of recording, the mask transmittance will be small at the time of reproduction, and almost no reproduction output will be obtained.

[0014] Therefore, it is necessary that the effect of the masking function is large at the time of reproduction of the optical disk, and that the effect of the masking operation is also exerted at the time of recording.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first invention is to form at least a guide groove for tracking servo on one surface of a transparent disk substrate; The mask layer and the recording layer for recording and reproducing information signals are sequentially laminated on the one surface, and the temperature is increased when the irradiation light intensity of the laser beam is increased, and the recording layer for recording and reproducing the information signal is formed on the one surface. An optical disc in which a light spot of the laser light emitted from the other surface side of the transparent disc substrate passes through the mask layer to have a substantially reduced light spot diameter and enters the recording layer; Wherein the mask layer comprises: a reproducing mask layer formed on one surface of the disk substrate; and a recording mask layer formed on the reproducing mask layer. It is a disk.

According to a second aspect of the present invention, there is provided a recording layer having at least a guide groove for tracking servo formed on one surface of a disk substrate, and a recording layer for recording and reproducing information signals on the one surface, When the light irradiation intensity is increased, the temperature is increased and the light transmittance is increased, and a mask layer is sequentially laminated and formed on the mask layer. Further, a transparent protective layer having a thickness smaller than the thickness of the disk substrate is formed on the mask layer. Or, or a transparent sheet having a thickness smaller than the thickness of the disk substrate is attached on the mask layer, and the light spot of the laser beam irradiated from the transparent protective layer side or the transparent sheet side is In an optical disc, which is transmitted through the mask layer and has a substantially reduced light spot diameter and is incident on the recording layer, the mask layer is formed on the recording layer for recording. And disk layer composed of a recording mask layer films with reproduction mask layer on a disc which is characterized by comprising the transparent protective layer or the transparent sheet to the reproduction mask layer.

According to a third aspect of the present invention, in the optical disk according to the first or second aspect described above, the reproducing mask layer has a mask effect due to an irradiation intensity of the laser beam during reproduction, and The layer is characterized in that a mask effect is produced by the irradiation intensity of the laser beam at the time of recording while the light is attenuated at the irradiation intensity of the laser beam at the time of reproduction.

Further, the fourth aspect of the present invention is directed to the first to third aspects.
In the optical disc according to any one of the above aspects, the light transmittance of the recording mask layer with respect to irradiation light during reproduction is 30% to 70%.
%.

According to a fifth aspect of the present invention, at least a guide groove for tracking servo is formed on one surface of a transparent disk substrate, and when the intensity of the irradiation light of the laser beam is increased on the one surface, the temperature increases. A mask layer that increases in light transmittance and a recording layer that records and reproduces an information signal are sequentially laminated and formed into a film, and a light spot of the laser light irradiated from the other surface side of the transparent disk substrate Is transmitted through the mask layer so as to have a substantially reduced light spot diameter and is incident on the recording layer. In the optical disk, the mask layer acts as a mask by the irradiation intensity during reproduction of the laser light. The reproduction disk material having the effect and the recording mask material having the mask effect by the irradiation intensity at the time of recording of the laser light are mixed in the same layer to form the transparent disk. An optical disk, characterized in that the attached film on the one surface of the plate.

According to a sixth aspect of the present invention, there is provided a disk substrate, wherein at least one guide groove for tracking servo is formed on one surface of the disk substrate, and a recording layer for recording and reproducing an information signal on the one surface is provided. When the light irradiation intensity is increased, the temperature is increased and the light transmittance is increased, and a mask layer is sequentially laminated and formed on the mask layer. Further, a transparent protective layer having a thickness smaller than the thickness of the disk substrate is formed on the mask layer. Or, or a transparent sheet having a thickness smaller than the thickness of the disk substrate is attached on the mask layer, and the light spot of the laser beam irradiated from the transparent protective layer side or the transparent sheet side is In an optical disc which is made to enter the recording layer with a substantially reduced light spot diameter by transmitting through the mask layer, the mask layer has an irradiation intensity of the laser light at the time of reproduction. A reproducing mask material that produces a mask effect and a recording mask material that produces a mask effect at the irradiation intensity of the laser light during recording are mixed in the same layer and film-formed on the recording layer. It is an optical disk that performs

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an optical disk according to the present invention will be described with reference to FIGS.
The fourth embodiment will be described in detail. For convenience of explanation, the same reference numerals are given to the same constituent members as those shown in the conventional example, and will be described.

<First Embodiment> FIG. 1 is an enlarged sectional view schematically showing an optical disk according to a first embodiment of the present invention, and FIG. 2 is a partially modified optical disk according to the first embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view schematically showing Modified Example 1 and FIG. 3 is Modified Example 2 in which the optical disk of the first embodiment according to the present invention is partially modified.
FIG. 4 is an enlarged sectional view schematically showing the first embodiment of the present invention.
FIG. 5 is a view showing an example of a reproducing mask material of a reproducing mask layer in the optical disc of the embodiment, and FIG.
FIG. 6 shows an example of a recording mask material of a recording mask layer in the optical disc of the embodiment. FIG.
FIG. 7 shows the relationship between the irradiation light intensity and the transmittance of the reproducing mask layer in the optical disc of the embodiment. FIG. 7 shows the reproducing mask layer and the recording mask in the optical disc of the first embodiment according to the present invention. FIG. 8 is a diagram showing the relationship between the irradiation light intensity and the transmittance in the case of lamination, and FIG. 8 is a configuration diagram showing a recording / reproducing optical system device applied to the optical disc of the first embodiment according to the present invention.

The optical disk D1 according to the first embodiment of the present invention shown in FIG. 1 uses a general objective lens whose NA (numerical aperture) is set to a value of about 0.6, and uses a mask layer 4 The information signal is formed so that it can be recorded and reproduced at a high density (super-resolution) by the masking effect of.

In the optical disk D1 of the first embodiment described above, a transparent disk substrate (hereinafter, referred to as a transparent substrate) 2 is formed into a disk shape with a thickness of, for example, approximately 1.2 mm using a transparent resin material. I have. On one surface 2a of the transparent substrate 2, at least a guide groove for tracking servo is formed spirally or concentrically. In addition to this guide groove, a pre-format signal such as disk information or address information is provided in an uneven pit. It is formed in the form of.

On one surface 2a of the transparent substrate 2, a reproducing mask layer 4A, as a mask layer 4 which increases in temperature and increases light transmittance when the intensity of the irradiation light of the laser beam L increases.
The recording mask layer 4B is sequentially laminated and formed into a film, and
As a recording layer 6 for recording and reproducing information signals on the recording mask layer 4B, a dielectric film 6A, a phase change material film 6B, a dielectric film 6C, and an Al (aluminum) reflecting film 6D are sequentially laminated and formed. Further, a protective layer 8 is formed on the recording layer 6.

At this time, since the mask layer 4 and the recording layer 6 on one surface 2a of the transparent substrate 2 are formed to be extremely thin,
The guide groove or the uneven pit formed on one surface 2a is not filled with the mask layer 4 and the recording layer 6, and the mask layer 4 and the recording layer 6 follow the guide groove or the uneven pit.
Is formed.

Then, a recording / reproducing laser beam L emitted from a general objective lens having an NA (numerical aperture) of approximately 0.6 is applied to the other surface 2b side of the transparent substrate 2, and this laser beam L Is transmitted through the mask layer 4 composed of the reproducing mask layer 4A and the recording mask layer 4B to have a substantially reduced light spot diameter and is incident on the recording layer 6; The information signal can be recorded / reproduced only from one side.

Next, in the optical disc D2 of Modification 1 which is a partial modification of the first embodiment of the present invention shown in FIG. 2, the technical concept of the optical disc D1 of the first embodiment shown in FIG. Here, the plate thickness is, for example, approximately 0.6 mm
And the thickness of the transparent substrate 2 is approximately 0.6 mm, for example.
And a bonded optical disk is formed such that the total thickness of the bonded substrates becomes approximately 1.2 mm. Of course, the above-mentioned dummy substrate 9 is a simple disk-shaped plate.

That is, the optical disc D2 of the first modification of the first embodiment is the same as the transparent substrate 2 of the optical disc D1 of the first embodiment.
The thickness of the transparent substrate 2 and the one surface 2a of the transparent substrate 2
A reproducing mask layer 4A and a recording mask layer 4B as the mask layer 4, and a dielectric film 6A, a phase change material film 6B, a dielectric film 6C, and an Al (aluminum) reflecting film 6D as the recording layer 6 are sequentially formed thereon. The laminated optical disk is formed by laminating and film-forming, and further bonding the dummy substrate 9 on the recording layer 6 via an adhesive layer (not shown). Therefore, this optical disk D2 also has the other surface 2b of the transparent substrate 2.
A laser beam L emitted from an objective lens having an NA (numerical aperture) of approximately 0.6 is irradiated from the side, and an information signal can be recorded and reproduced only from one side.

Next, in the optical disc D3 of Modification 2 which is a partial modification of the first embodiment of the present invention shown in FIG. 3, the technical concept of the optical disc D1 of the first embodiment shown in FIG. Has been applied. In the optical disc D3 of Modification 2 of the first embodiment, two transparent substrates 2 each having a thickness of, for example, about 0.6 mm are used, and the two transparent substrates 2 are protected from the structure of the first embodiment. A material excluding the layer 8 is prepared.

Then, a mask layer 4 composed of a reproduction mask layer 4A and a recording mask layer 4B and a recording layer 6 are sequentially formed on one surface 2a of each transparent substrate 2 on which at least a guide groove for tracking servo is formed. In a state where the films are attached, the transparent substrates 2 are bonded together by bonding the recording layers 6 to each other via the adhesive layer 40 with the other surface 2b side of the transparent substrate 2 facing outside and the recording layer 6 side facing inside. An optical disk is formed. Therefore, the bonded optical disc D
3 has a total thickness of about 1.2 mm,
A laser beam L emitted from an objective lens having an NA (numerical aperture) of approximately 0.6 is irradiated from the other surface 2b side of each transparent substrate 2 to record and reproduce information signals on both sides of the optical disc D3. It has become.

Here, the components of the optical disk D1 (or D2 or D3) in the first embodiment will be described in detail. The transparent substrate 2 is made of a transparent resin material such as a polycarbonate resin or an acrylic resin. Or it is formed in a disk shape using a transparent glass plate,
A central hole (not shown) is formed at the center.

Next, in the mask layer 4 described above, the temperature increases and the light transmittance increases as the intensity of the irradiation light of the laser beam L increases, as in the conventional example. Unlike the one-layered mask layer of the example, it is characterized in that the reproducing mask layer 4A and the recording mask layer 4B are formed in a two-layer structure.

That is, the reproducing mask layer 4A formed on the one surface 2a of the transparent substrate 2 is provided on the optical disc D1 (or D
2 or D3), the reproduction irradiation light intensity is about 1
A thermochromic, a photochromic, a phase change material, or the like that can exert a masking effect with a laser beam L as small as 2.5 mw is used.

In this embodiment, thermochromic is used as a reproducing mask material of the reproducing mask layer 4A.
As shown in the above, as a coloring agent, trade name G manufactured by Yamamoto Kasei Co., Ltd.
N2, BHPE (bishydroxyphenylethane) as a color developer, and a color former (GN2) and a developer (B
(HPE) in a weight ratio of about 1: 2 using a binary vapor deposition machine at the same time by vapor deposition.

As a result of the experiment, the reproduction mask layer 4A
Means that the irradiation light intensity during reproduction of the laser light L is about 1 to 2.5 mw
In the case of (1), a preferable masking effect was obtained. In particular, when the irradiation light intensity during reproduction was about 1.5 mw, the masking effect was large.

Further, the relationship between the irradiation light intensity of the reproducing mask layer 4A and the transmittance shown in FIG. 6 indicates the transmittance of the entire spot. This embodiment is an example in which a recording mask layer 4B having a transmittance of about 44% at a place where the intensity is low is laminated on a reproduction mask layer 4A having the characteristics shown in FIG.

As shown in FIG. 7, the relationship between the irradiation light intensity and the transmittance after laminating the reproduction mask layer 4A and the recording mask layer 4B increases the irradiation light intensity of the laser light L. First, the transmittance of the reproduction mask layer 4A sharply increases, and a mask effect is generated by the reproduction power.
Thereafter, the transmittance of the recording mask layer 4B increases, and a mask effect is produced by the recording power. However, since the transmittance of the recording mask layer 4A at a low power where the mask effect does not occur is as high as about 44%, the mask effect is small as compared with the case where the transmittance at a low power is small.

The recording mask layer 4B formed on the reproducing mask layer 4A is masked by a laser beam L having a large irradiation light intensity of about 15 mw during recording on the optical disk D1 (or D2 or D3). Thermochromic, photochromic, phase-change materials, etc. that can exhibit the characteristics are used.

In this embodiment, thermochromic is used as a recording mask material for the recording mask layer 4B, and as shown in FIG. 5, a prototype D9 manufactured by Yamamoto Kasei Co., Ltd. is used as a coloring material.
4-006, BHPE (bishydroxyphenylethane) is used as a developer, and a color former (D94-00)
6) and a color developer (BHPE) are simultaneously deposited by vapor deposition at a ratio of about 1: 2 by weight using a binary vapor deposition machine. At this time, the recording mask layer 4B produces a mask effect at the recording irradiation intensity of the laser beam L while attenuating the light at the reproduction irradiation light. Light transmittance to light is 30% or more
70%.

Next, as the recording layer 6 formed on the recording mask layer 4A, a phase change material, a magneto-optical material, an organic material, or the like is used. The recording layer 6 of this embodiment uses a phase change material, and this recording layer 6 is composed of a plurality of laminated films. More specifically, the recording layer 6 is composed of the ZnS-SiO2 dielectric films 6A and 6A, which are closer to the recording mask layer 4B.
A gInSbTe phase change material film 6B, a ZnS-SiO2 dielectric film 6C, and an Al (aluminum) reflection film 6D are sequentially laminated and attached.

The protective layer 8 formed on the recording layer 6,
As a material of the adhesive layer 40, a photopolymer or the like is used.

Next, a recording / reproducing optical system device 20 applied to the optical disk D1 (or D2 or D3) according to the first embodiment of the present invention formed as described above will be briefly described with reference to FIG.

The recording / reproducing optical system device 20 has a wavelength of 65
Semiconductor laser element 2 that emits laser light L of 0 nm
2, a collimator lens 24 for converting the laser light L from the semiconductor laser element 22 into parallel light, and a polarizing prism 26
, A quarter-wave plate 28, and the laser light L
1 (D2, D3) to collect the reflected light from the optical disc D1 (D2, D3) branched by the polarizing prism 26 and the objective lens 30 having an NA (numerical aperture) of approximately 0.6 in order to collect the light. Condensing lens 32, a cylindrical lens 34 for obtaining focus information and tracking information from the reflected light, and a photodetector 36 for detecting the condensed light.
The light detector 36 detects reflected light from the optical disk D1 (D2, D3) to record and reproduce information recorded on the optical disk D1 (D2, D3).

At this time, when the recording and reproduction of the information signal are performed separately, the recording / reproduction optical system device 20 uses the irradiation light intensity of the laser beam L emitted from the semiconductor laser element 22 as the recording irradiation irradiation light intensity and the reproduction light intensity. What is necessary is just to switch to irradiation light intensity. When recording and reproducing information signals are performed at the same time, the recording and reproducing optical system device 20 may have two systems for recording and reproducing.

Next, information signals were recorded / reproduced by the recording / reproducing optical system device 20 using the optical disk D1 (or D2 or D3) in the first embodiment according to the present invention.

Here, as Comparative Example 1 of the present invention, the case where the AgInSbTe phase change material was used as the recording material of the recording layer 6 without attaching the reproducing mask layer 4A and the recording mask layer 4B to the film was described above. The wavelength of the laser beam L is 65
Under the recording / reproducing condition of 0 nm, the NA (numerical aperture) of the objective lens 30 is approximately 0.6, and the linear velocity is 3.5 m / s,
If the reproduction power is not set to 0.7 mw or less, recorded information will be destroyed.

As Comparative Example 2 of the present invention, when only the reproducing mask layer 4A having the characteristics shown in FIG.
If the same location is continuously reproduced for a long time with a reproduction power of w or more, the recorded information is destroyed. At this time, the transmittance of the entire irradiation light intensity of the laser beam L is small at around 60%, but the intensity at the center of the Gaussian distribution is large, and the heat absorbed by the light absorbed by the reproduction mask layer 4A is transmitted to the recording layer 6. Instead, the recorded information is destroyed.

On the other hand, when the optical disc D1 (or D2 or D3) in the first embodiment according to the present invention is structured as described above, light is absorbed by the recording mask layer 4B and transmitted through the reproducing mask layer 4A. Decays. Also,
The recording mask layer 4B becomes a layer for blocking the heat generated by the reproducing mask layer 4A, and the recorded information is not destroyed.

At this time, the transmittance of the recording mask layer 4B to the irradiation light during reproduction is preferably 30% to 70%. When the transmittance of the recording mask layer 4B to the irradiation light at the time of reproduction becomes 30% or less, the optical disc D1 (D2, D3)
In the case of detecting and reproducing the reflected light from the optical disk, the light is attenuated in a round trip, so that the detection output becomes small, the stability of the focus and tracking servo is deteriorated, and the reproduction C / N
Also gets worse. Further, when the transmittance of the recording mask layer 4B to the irradiation light at the time of reproduction becomes 70% or more, the effect of the mask at the time of recording can hardly be expected, and at the same time, the light attenuation effect is small and the fluctuation of the reproduction power or the like causes Destruction is likely to occur.

When a non-thermochromic phase change material such as In, TeGe, Sb, or the like is used for the reproducing mask layer 4A, the reproducing irradiation light intensity at which the mask effect is maximized is the thermochromic intensity. It becomes even larger than in the case, and the destruction of recorded information during repeated reproduction is large.
However, it may be used for the recording mask layer 4B.

However, in the case of a rewritable optical disk using a phase change recording material as the recording material of the recording layer 6,
Before use, initialization is performed to irradiate a laser beam L to change from an amorphous state after film formation to a crystallized state. However, if a phase change material such as In, TeGe, or Sb is used for the recording mask layer 4B, The laser power at initialization must be higher. On the other hand, in the case of a thermochromic material, the attenuation of light during initialization can be reduced by selecting the laser wavelength used for initialization.
, The laser power at the time of initialization can be made almost the same as when there is no recording mask layer 4B.

The laser beam L used for recording / reproduction is
In general, noise is small where the output used for recording is large, but small when the output is low used for reproduction. Therefore, a recording mask with an irradiation light intensity of 1.5 mw (about 4.5 mw, which is about three times as high as the laser output) is used as compared with reproduction with an irradiation light intensity of 0.7 mw (about 2.1 mw which is about three times as high as the laser output). When the light is attenuated and reproduced in the layer 4B, C /
N ratio is good.

As described in detail above, according to the optical disk D1 (or D2 or D3) in the first embodiment,
The mask layer 4 is composed of a reproduction mask layer 4A and a recording mask layer 4B.
Since the laser light L has a two-layer structure, a masking effect is produced in the reproducing mask layer 4A at the irradiation intensity of the laser beam L during reproduction, and the light is attenuated by the recording mask layer 4B at the reproduction light irradiation intensity of the laser beam. The recorded information can be reproduced without destroying it, and a masking effect is produced on the recording mask layer 4B by the irradiation intensity of the laser beam L at the time of recording. be able to.

<Second Embodiment> FIG. 9 is an enlarged sectional view schematically showing an optical disk according to a second embodiment of the present invention.
FIG. 9 is an enlarged cross-sectional view schematically showing Modification 1 in which the optical disc of the second embodiment according to the present invention is partially deformed. FIG.
FIG. 9 is an enlarged sectional view schematically showing Modification 2 in which the optical disc of the second embodiment according to the present invention is partially modified.

The optical disc D4 of the second embodiment according to the present invention shown in FIG. 9 also uses a general objective lens whose NA (numerical aperture) is set to a value of about 0.6, and The information signal is formed so that it can be recorded and reproduced at a high density (super-resolution) by the masking effect of.

In the optical disk D4 of the second embodiment, the transparent substrate 2 is made of a transparent resin material, for example, about 1.2 mm.
It is formed in a disk shape with a thickness of mm. A guide groove for tracking servo is formed at least in a spiral or concentric shape on one surface 2a of the transparent substrate 2,
In addition to the guide grooves, preformat signals such as disk information and address information are formed in the form of uneven pits.

On one surface 2 a of the transparent substrate 2, a mask layer 4 for recording / reproducing is formed as a mask layer 4 for increasing the temperature and increasing the light transmittance when the irradiation light intensity of the laser beam L is increased.
C is formed as a single layer, and the recording / reproducing mask layer 4 is formed.
A dielectric film 6A and a phase change material film 6 as a recording layer 6 on C
B, a dielectric film 6C, and an Al (aluminum) reflection film 6D are sequentially laminated and formed, and further, a protective layer 8 is formed on the recording layer 6.
Is filmed.

Then, a recording / reproducing laser beam L emitted from a general objective lens having an NA (numerical aperture) of about 0.6 is applied to the other surface 2b of the transparent substrate 2, and the laser beam L The light spot is transmitted through the recording / reproducing mask layer 4C so as to have a substantially reduced light spot diameter and is incident on the recording layer 6, so that an information signal can be recorded / reproduced only from one side of the optical disc D4. It has a structural form.

Next, in an optical disc D5 of Modification 1 in which the second embodiment according to the present invention shown in FIG. 10 is partially modified,
The technical idea of the optical disk D4 of the second embodiment shown in FIG. 9 is applied, and here, the plate thickness is, for example, approximately 0.6 m.
m, and the thickness of the transparent substrate 2 is, for example, approximately 0.6 m.
In this example, a laminated optical disk is formed by laminating the dummy substrate 9 formed on the substrate m and the total thickness of the laminated substrates to be approximately 1.2 mm. Of course, the above-mentioned dummy substrate 9 is a simple disk-shaped plate.

That is, the optical disc D5 of the first modification of the second embodiment is the same as the transparent substrate 2 of the optical disc D4 of the second embodiment.
The thickness of the transparent substrate 2 and the one surface 2a of the transparent substrate 2
On top, a recording / reproducing mask layer 4C as the mask layer 4 and a dielectric film 6A, a phase change material film 6B, a dielectric film 6C, and an Al (aluminum) reflecting film 6D as the recording layer 6 are sequentially laminated. Further, a bonded optical disk is formed by bonding a dummy substrate 9 on the recording layer 6 via an adhesive layer (not shown). Therefore, this optical disc D5 also has a laser beam L emitted from an objective lens having an NA (numerical aperture) of approximately 0.6 from the other surface 2b side of the transparent substrate 2.
, Respectively, so that information signals can be recorded and reproduced only from one side.

Next, in an optical disc D6 of a modified example 2 in which the second embodiment according to the present invention shown in FIG. 11 is partially modified,
The technical idea of the optical disc D4 of the second embodiment shown in FIG. 9 is applied. In the optical disc D6 of the modified example 2 of the second embodiment, two transparent substrates 2 having a thickness of, for example, about 0.6 mm are used, and the two transparent substrates 2
A structure prepared by removing the protective layer 8 from the structure of the embodiment is prepared.

Then, the recording / reproducing mask layer 4C and the recording layer 6 are sequentially formed on one surface 2a of each transparent substrate 2 on which at least a guide groove for tracking servo is formed. The optical disks are formed by bonding the recording layers 6 by bonding the recording layers 6 to each other with an adhesive layer 40 with the other surface 2b side facing outward and the recording layer 6 sides facing each other. Accordingly, the bonded optical disc D6 also has a total thickness of about 1.2 mm and is irradiated with laser light from the other surface 2b of each transparent substrate 2 to transmit information signals on both sides of the optical disk D6. It has a structure that allows recording and reproduction.

Here, among the constituent members of the optical disk D4 (or D5 or D6) in the above-described second embodiment, the recording / reproducing mask layer 4C produces a mask effect by the irradiation intensity of the laser beam L during reproduction. A reproduction mask material and a recording mask material that produces a mask effect by the irradiation intensity of the laser beam L during recording are mixed in the same layer and formed on one surface 2 a of the transparent substrate 2. That is, as a coloring agent of a mask material for reproduction, a brand name G manufactured by Yamamoto Kasei Co., Ltd.
GN2: D94, using N2, a prototype product name D94-006 manufactured by Yamamoto Kasei Co., Ltd. as a colorant for the recording mask material, and BHPE (bishydroxyphenylethane) as a common developer for recording and reproduction. -006: BHPE
Are mixed in the same layer at a ratio of about 2: 1: 6 by weight% to form a film by vapor deposition.

At this time, the recording / reproducing mask layer 4C is the same as the reproducing mask layer 4A described in the first embodiment with reference to FIG.
And a recording mask layer 4B. That is, the recording / reproducing mask layer 4C
Is a mask layer 4 which has a mask effect by the irradiation light at the time of reproduction and attenuates to a power which does not destroy recorded information, and has a transmittance characteristic which has a mask effect even by the irradiation light at the time of recording. In this case, even if the reproducing power was 1.5 mw, the recorded information was not destroyed.

As described in detail above, according to the optical disk D4 (or D5 or D6) in the second embodiment, a reproduction mask material and a recording mask material are mixed in the same layer in the recording / reproduction mask layer 4C. The first
The optical disc D1 (or D2 or D2 in the embodiment)
It is possible to obtain substantially the same effect as in 3).

<Third Embodiment> FIG. 12 shows a third embodiment according to the present invention.
FIG. 1 is an enlarged sectional view schematically showing the optical disc of the embodiment.
FIG. 3 is an enlarged sectional view schematically showing a modified example in which the optical disk of the third embodiment according to the present invention is partially modified.

The optical disk D7 of the third embodiment according to the present invention shown in FIG. 12 uses an objective lens whose NA (numerical aperture) is set to a large value of approximately 0.85, and has a high N of the objective lens.
The information signal is formed so as to be able to record and reproduce the information signal at a higher density (super-resolution) by the use of A and the mask effect by the mask layer 4. And the high N of the objective lens
Laser light L emitted from the objective lens with the A
Are formed so as to cope with the short focal length when forming an image on the recording layer 6.

In the optical disk D7 of the third embodiment, the disk substrate 10 is made of a transparent or opaque resin material such as a polycarbonate resin or an acrylic resin, or a glass plate of about 1.0 to 1.15 mm. It is formed in a thick, disk-like shape. Then, this disk substrate 10
A guide groove for tracking servo is formed at least in a spiral or concentric shape on one surface 10a of the first surface 10a. In addition to this guide groove, a preformat signal such as disk information or address information is formed in the form of uneven pits. I have.
Here, since the laser beam L is not incident from the other surface 10b side of the disk substrate 10, the material of the disk substrate 10 may be either transparent or opaque.

Also, one surface 10a of the disk substrate 10
On the recording layer 6 for recording and reproducing information signals, Ag is used.
(Silver) reflective film 6D, dielectric film 6C, phase change material film 6B,
Dielectric films 6A are sequentially laminated and applied, and when the intensity of the irradiation light of the laser beam L is increased on the recording layer 6, the temperature is increased and the light transmittance is increased. Reproducing mask layers 4A are sequentially laminated and applied. Therefore, in the optical disc D7 of the third embodiment, the Ag (silver) reflection film 6D, the dielectric film 6C, the phase change material film 6B, the dielectric film 6A as the recording layer 6 and the mask layer 4
Among the recording mask layer 4B and the reproduction mask layer 4A as described above, except for the Ag (silver) reflection film 6D, the first mask described above is used.
Although the same material is used as in the case of the optical disk D1 of the embodiment, each of the films 6D to 6A in the recording layer 6 on the disk substrate 10 and the recording mask layer 4B in the mask layer 4,
As is clear from the above, the order of film formation of the reproducing mask layer 4A is reversed from that of the optical disk D1 of the first embodiment.

Further, a transparent protective layer 11 having a thickness smaller than the thickness of the disk substrate 10 is formed on the reproducing mask layer 4A.
Or a transparent sheet (1) having a thickness smaller than the thickness of the disk substrate 10 on the reproduction mask layer 4A.
1) is adhered flat via an ultraviolet-curable adhesive (not shown). At this time, the thickness of the transparent protective layer 11 is set to approximately 0.0 in accordance with the value of the objective lens having a high NA (numerical aperture).
The thickness of the transparent sheet (11) is set to about 0.05 to 0.2 mm. Further, the sum of the thickness of the disk substrate 10 and the thickness of the transparent protective layer 11 is approximately 1.2 mm, or
The sum of the thickness of the disk substrate 10 and the thickness of the transparent sheet (11) is also approximately 1.2 mm.

When the transparent protective layer 11 is applied on the reproducing mask layer 4A or when the transparent sheet (11) is pasted through an ultraviolet curable adhesive, the reproducing mask layer 4A becomes transparent. Inside protective layer 11 or transparent sheet (11)
If there is a risk of dissolving into the UV curable adhesive for use, the alicyclic hydrocarbon resin manufactured by ZEON CORPORATION, product name Quinton 1325 is used for the purpose of protecting the regenerating mask layer 4A if necessary. It may be dissolved in cyclohexane and applied very thinly on the reproducing mask layer 4A, and thereafter, a transparent protective layer 11 may be applied or a transparent sheet (11) may be attached.

Then, the recording / reproducing laser beam L emitted from the objective lens having an NA (numerical aperture) of 0.85 is the thin transparent protective layer 11 side or the thin transparent sheet (11). And the light spot of the laser beam L is transmitted through the mask layer 4 composed of the reproducing mask layer 4A and the recording mask layer 4B to have a substantially reduced light spot diameter and enters the recording layer 6. The optical disc D7 has a structure capable of recording and reproducing information signals only from one side thereof.

Next, in the optical disc D8 of the modified example in which the third embodiment according to the present invention shown in FIG. 13 is partially modified, the technical concept of the optical disc D7 of the third embodiment shown in FIG. Although applied, at this time, the thickness of the disk substrate 10 is formed to be about 0.8 to 1.1 mm, and at least one guide groove for tracking servo is formed on one surface 10a and the other surface 10b. ing.

In this case, the disk substrate 1
0, a guide groove for tracking servo is formed at least simultaneously on both surfaces to manufacture the optical disk 6 with one substrate. In addition to this method, the thickness of the disk substrate 10 applied to the optical disk D7 of the third embodiment is set to 1 / 2, there is a method of manufacturing an optical disk 6 by using two disk substrates of this thickness and bonding the other surfaces of the two disk substrates on which the guide grooves are not formed to each other.

Then, one surface 10 of the disk substrate 10
In a state where at least a guide groove for tracking servo is formed on the other surface 10b of the disk substrate 10, Ag is formed as a recording layer 6 on one surface 10a and the other surface 10b of the disk substrate 10.
(Silver) reflective film 6D, dielectric film 6C, phase change material film 6B,
A dielectric film 6A) and a recording mask layer 4 as the mask layer 4
B, a reproduction mask layer 4A is sequentially formed on the disk substrate 10, and a transparent protective layer 11 having a thickness smaller than the thickness of the disk substrate 10 is evenly applied on the reproduction mask layer 4A on both sides of the disk substrate 10. Alternatively, a transparent sheet (11) having a thickness smaller than the thickness of the disk substrate 10 is flatly adhered on the reproducing mask layer 4A via an ultraviolet curable adhesive (not shown). Also in this case, the thickness of the transparent protective layer 11 is approximately 0.05 to 0.05 depending on the value of a high NA (numerical aperture) of the objective lens.
It is set to about 0.2 mm, and the transparent sheet (1
The plate thickness of 1) is also set to about 0.05 to 0.2 mm. Further, the total value of the thickness of the disk substrate 10 + 2 × the thickness of the transparent protective layer 11 is approximately 1.2 mm, or
The total value of the thickness of the disk substrate 10 + 2 × the thickness of the transparent sheet (11) is also approximately 1.2 mm.

Therefore, the objective lens having an NA (numerical aperture) of approximately 0.85 from the side of the thin transparent protective layer 11 provided on both sides of the optical disk D8 or the side of the transparent sheet (11) having a small thickness. Irradiate the emitted laser light L, respectively,
The optical disc D8 has a structure in which information signals can be recorded and reproduced on both sides.

As described in detail above, according to the optical discs D1 and D2 in the third embodiment, the mask layer 4 has two layers, ie, the reproducing mask layer 4A and the recording mask layer 4B, and the NA is further increased. A thin transparent protective layer 11 is applied on the reproducing mask layer 4A so that an objective lens can be applied, or a thin transparent sheet (11) is attached on the reproducing mask layer 4A. , A transparent protective layer 11 having a thin laser beam L emitted from an objective lens having a high NA
And the light spot of the laser light L is substantially reduced by transmitting through the mask layer 4 composed of the reproducing mask layer 4A and the recording mask layer 4B. Since the light beam has a light spot diameter and is incident on the recording layer 6, the information signal can be further densified (super-resolution) by increasing the NA of the objective lens and the masking effect of the mask layer 4. Record and play back.

<Fourth Embodiment> FIG. 14 shows a fourth embodiment according to the present invention.
FIG. 1 is an enlarged sectional view schematically showing the optical disc of the embodiment.
FIG. 5 is an enlarged cross-sectional view schematically showing a modified example in which the optical disk of the fourth embodiment according to the present invention is partially modified.

The optical disk D9 of the fourth embodiment according to the present invention shown in FIG. 14 and the optical disk D10 of the modification of the fourth embodiment shown in FIG. 15 also have a large NA (numerical aperture) of approximately 0.85. The information signal is formed so as to be able to record and reproduce information signals at a higher density (more super resolution) by using a high NA of the objective lens and a masking effect of the mask layer 4 using the objective lens set as described above.

The optical disk D9 of the fourth embodiment and the optical disk D10 of the modification of the fourth embodiment are both the optical disk D7 and the third optical disk of the third embodiment described above.
Recording mask layer 4 of optical disc D8 according to a modification of the embodiment
B, since the mask layer 4 composed of the reproducing mask layer 4A is replaced by the recording / reproducing mask layer 4C used for the optical disk D4 of the second embodiment and the optical disk D6 of the modification 2 of the second embodiment. The details are omitted.

Therefore, in the optical disk D9 of the fourth embodiment and the optical disk D10 of the modification of the fourth embodiment, a reproducing mask material and a recording mask material are mixed in the same layer in the recording / reproducing mask layer 4C. In this state, a transparent protective layer 11 having a small thickness is applied on the recording / reproducing mask layer 4C so that an objective lens having a high NA can be applied, or a thin plate thickness is provided on the recording / reproducing mask layer 4C. The transparent sheet (11) is adhered, and the laser beam L emitted from the objective lens having a high NA is irradiated on the transparent protective layer 11 side having a small thickness or the transparent sheet (11) side having a small thickness. Laser light L
Is transmitted through the recording / reproducing mask layer 4C so as to have a substantially reduced light spot diameter and enter the recording layer 6, so that the light spot of the second embodiment and the third embodiment can be used. It is clear that the combined effect can be obtained.

[0083]

According to the optical disk according to the present invention described in detail above, according to claims 1, 3 and 4,
In particular, since the mask layer is composed of two layers, a reproducing mask layer and a recording mask layer, a mask effect is produced in the reproducing mask layer by the irradiation intensity of the laser beam at the time of reproduction, and the irradiation intensity of the laser beam at the time of reproduction is increased. Since the light is attenuated by the recording mask layer, the recorded information can be reproduced without destroying the recorded information. At the same time, the recording light irradiation intensity at the time of recording produces a masking effect on the recording mask layer. Super-resolution recording / reproduction) can be reliably performed.

According to the second, third, and fourth aspects of the present invention, in particular, the mask layer is composed of two layers, ie, a reproduction mask layer and a recording mask layer. Apply a thin transparent protective layer on the reproduction mask layer so that it can be applied, or attach a thin transparent sheet on the reproduction mask layer and emit from the objective lens with a high NA. The irradiated laser beam L is applied to the transparent protective layer side having a small thickness or the transparent sheet side having a small thickness, and the light spot of the laser beam passes through a mask layer composed of a reproducing mask layer and a recording mask layer. , The light spot diameter becomes substantially reduced, and the light enters the recording layer. Therefore, the information signal can be further densified (higher density) by increasing the NA of the objective lens and the mask effect by the mask layer. Super-resolution recording and playback Kill.

According to the fifth aspect, in particular, the reproduction mask material and the recording mask material are mixed in the same layer in the recording / reproduction mask layer. Thus, substantially the same effects as those of the optical disk according to the fourth aspect can be obtained.

According to the sixth aspect of the present invention, in particular, the objective lens having a high NA is provided in a state where the reproducing mask material and the recording mask material are mixed in the same layer in the recording / reproducing mask layer. A thin transparent protective layer is applied on the recording / reproducing mask layer so as to be applicable, or a thin sheet of a transparent sheet is pasted on the recording / reproducing mask layer to obtain a high N
The laser light emitted from the A-formed objective lens is irradiated on the thin transparent protective layer side or the thin transparent sheet side, and the light spot of this laser light is transmitted through the recording / reproducing mask layer to substantially reduce the light spot. Since the light spot diameter is reduced to be incident on the recording layer, it is possible to obtain substantially the same effects as those of the optical disks according to the second, third, and fourth aspects.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view schematically showing an optical disc of a first embodiment according to the present invention.

FIG. 2 is an enlarged cross-sectional view schematically showing Modification 1 in which the optical disc of the first embodiment according to the present invention is partially deformed.

FIG. 3 is an enlarged sectional view schematically showing Modification 2 in which the optical disk of the first embodiment according to the present invention is partially modified.

FIG. 4 is a diagram showing an example of a reproducing mask material of a reproducing mask layer in the optical disc of the first embodiment according to the present invention.

FIG. 5 is a diagram showing an example of a recording mask material of a recording mask layer in the optical disc of the first embodiment according to the present invention.

FIG. 6 is a diagram showing the relationship between the irradiation light intensity of the reproducing mask layer and the transmittance in the optical disc of the first embodiment according to the present invention.

FIG. 7 is a diagram showing the relationship between the irradiation light intensity and the transmittance when the reproducing mask layer and the recording mask are stacked on the optical disc of the first embodiment according to the present invention.

FIG. 8 is a configuration diagram showing a recording / reproducing optical system device applied to the optical disc of the first embodiment according to the present invention.

FIG. 9 is an enlarged sectional view schematically showing an optical disc of a second embodiment according to the present invention.

FIG. 10 is an enlarged sectional view schematically showing Modification 1 in which the optical disc of the second embodiment according to the present invention is partially modified.

FIG. 11 is an enlarged sectional view schematically showing Modification 2 in which the optical disc of the second embodiment according to the present invention is partially modified.

FIG. 12 is an enlarged sectional view schematically showing an optical disc according to a third embodiment of the present invention.

FIG. 13 is an enlarged sectional view schematically showing a modification in which the optical disk of the third embodiment according to the present invention is partially modified.

FIG. 14 is an enlarged sectional view schematically showing an optical disc of a fourth embodiment according to the present invention.

FIG. 15 is an enlarged sectional view schematically showing a modification in which the optical disc of the fourth embodiment according to the present invention is partially modified.

FIG. 16 is an enlarged sectional view schematically showing a conventional optical disk.

FIG. 17 is a diagram showing a relationship between a temperature of a mask layer and a light transmittance in a conventional optical disc.

FIG. 18 is a schematic diagram of an intensity distribution of light incident on a mask layer and an intensity distribution of light transmitted through the mask layer in a conventional optical disc.

FIG. 19 is a diagram showing the relationship between a light spot of a laser beam incident on a mask layer and a light spot transmitted through the mask layer, which absorbs light and raises the temperature to increase the transmittance, in a conventional optical disc. .

[Explanation of symbols]

D1 ... the optical disc of the first embodiment according to the present invention, D2 ... the optical disc of the first modification of the first embodiment according to the present invention, D3 ...
Optical disc of modification 2 of first embodiment according to the present invention, D4
... the optical disk of the second embodiment of the present invention, D5 ... the optical disk of the first modification of the second embodiment of the present invention, D6 ... the optical disk of the second modification of the second embodiment of the present invention, D7: the present invention The optical disk of the third embodiment according to the present invention, D8: an optical disk of a modification of the third embodiment according to the present invention, D9: the optical disk of the fourth embodiment according to the present invention, D10: the fourth optical system of the present invention
An optical disk according to a modification of the embodiment, 2 ... a transparent disk substrate (transparent substrate), 2a ... one surface, 2b ... the other surface, 4 ...
Mask layer, 4A: reproduction mask layer, 4B: recording mask layer, 4C: recording / reproduction mask layer, 6: recording layer, 8: protective layer, 9: dummy substrate, 10: disk substrate, 10a: one surface 10b: the other surface, 11: a transparent protective layer or transparent sheet, 40: an adhesive layer, L: a laser beam.

Claims (6)

[Claims] 1. A transparent disk substrate having at least a guide groove for tracking servo formed on one surface thereof, and an increase in the intensity of laser beam irradiation on the one surface increases the temperature and the light transmittance. An ascending mask layer and a recording layer for recording and reproducing information signals are sequentially laminated and formed into a film, and a light spot of the laser beam irradiated from the other surface side of the transparent disk substrate passes through the mask layer. In the optical disk, the light spot diameter of which is substantially reduced by being incident on the recording layer, the mask layer includes a reproducing mask layer formed on one surface of the disk substrate. An optical disk comprising a recording mask layer formed on the reproducing mask layer. 2. A recording layer on which at least a guide groove for tracking servo is formed on one surface of a disk substrate, and a recording layer for recording and reproducing an information signal on said one surface, and a laser beam irradiation intensity is high. When the temperature becomes higher, a mask layer having an increased light transmittance is sequentially laminated and formed into a film, and further, a transparent protective layer having a thickness smaller than the thickness of the disk substrate is applied on the mask layer, or A transparent sheet having a thickness smaller than the thickness of the disk substrate is stuck on the mask layer, and the light spot of the laser beam irradiated from the transparent protective layer side or the transparent sheet side passes through the mask layer. An optical disk having a substantially reduced light spot diameter and incident on the recording layer, wherein the mask layer comprises: a recording mask layer formed on the recording layer; An optical disc comprising: a reproduction mask layer formed on a reproduction mask layer; and the transparent protective layer or the transparent sheet is provided on the reproduction mask layer. 3. The reproducing mask layer produces a mask effect by the irradiation intensity of the laser beam during reproduction, and the recording mask layer produces a mask effect by the irradiation intensity of the laser beam during recording. 3. The optical disc according to claim 1, wherein the light is attenuated at the irradiation intensity at the time of reproduction of the laser light. 4. The optical disk according to claim 1, wherein a light transmittance of the recording mask layer with respect to irradiation light at the time of reproduction is set to 30% to 70%. 5. A transparent disk substrate having at least one guide groove for tracking servo formed on one surface thereof, and the intensity of laser light applied on said one surface increases the temperature to increase the light transmittance. A rising mask layer and a recording layer for recording and reproducing an information signal are sequentially laminated and formed into a film, and a light spot of the laser light irradiated from the other surface side of the transparent disk substrate passes through the mask layer. An optical disc which is made to have a light spot diameter which is substantially reduced by being incident on the recording layer, wherein the mask layer has a mask effect by the irradiation intensity at the time of reproduction of the laser beam. A material and a recording mask material that produces a masking effect at the irradiation intensity during recording of the laser light are mixed in the same layer to form a film on one surface of the transparent disk substrate. An optical disc characterized by being attached. 6. A recording layer in which at least a guide groove for tracking servo is formed on one surface of a disk substrate, and a recording layer for recording and reproducing an information signal on said one surface has a high laser beam irradiation intensity. When the temperature becomes higher, a mask layer having an increased light transmittance is sequentially laminated and formed into a film, and further, a transparent protective layer having a thickness smaller than the thickness of the disk substrate is applied on the mask layer, or A transparent sheet having a thickness smaller than the thickness of the disk substrate is stuck on the mask layer, and the light spot of the laser beam irradiated from the transparent protective layer side or the transparent sheet side passes through the mask layer. In the optical disc, which has a substantially reduced light spot diameter and is incident on the recording layer, the mask layer produces a mask effect by the irradiation intensity of the laser light during reproduction. An optical disk, wherein a reproduction mask material and a recording mask material that produces a mask effect by the irradiation intensity of the laser beam during recording are mixed in the same layer and formed on the recording layer.