JPH10106030A - Optical information recording medium and its reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible obtaining an inexpensive translucent reflection film easy to manufacture with reflectance and transmissivity of prescribed values or above by making the reflection film forming a first recording layer a film consisting of dystuff. SOLUTION: This optical information recording medium is provided with a translucent substrate 1, the first recording layer 2 consisting of the translucent reflection film placed on the substrate 1 and a second recording layer 4 consisting of the reflection film placed on the first recording layer 2, and the reflection film of the first recording layer 2 consists of the dystuff. Then, since the translucent reflection film forming the first recording layer 2 is the film consisting of the dystuff, the matter that the reflectance and transmissivity are made prescribed values or above also is easy, and the inexpensive manufacture is easy also.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording medium and a method for reproducing the same.

[0002]

2. Description of the Related Art In recent years, in addition to a conventional CD (compact disk), various optical information recording media such as a CD-ROM have been provided.

[0003] In particular, recently, D has a high information recording density.
VD (digital video disc) has been proposed.

FIG. 8 is a sectional view of a laminated optical information recording medium which is one of DVDs.

In the figure, 101 is a translucent substrate made of polycarbonate, 102 is various metals such as gold or SiN, SiO _2.
A first recording layer made of a light-transmitting reflective film (semi-transparent film) of various dielectrics such as a bonding material; 103, a bonding adhesive made of a light-transmitting resin; The second recording layer 105 is a translucent substrate made of polycarbonate.

[0006] In such an optical information recording medium, reading out any of the information in the first and second recording layers 102 and 104 is performed by irradiating reproduction light of the same wavelength from the translucent substrate 101 side. . Therefore, when reading information from the second recording layer 102, the reproduction light passes through the first recording layer 102, so that the first recording layer 102 outputs the information to the reproduction light in order to read the information. On the other hand, it is necessary to provide a reflectance higher than a predetermined value, and it is important to provide a transmittance higher than a predetermined value.

[0007]

However, when the above-described metal is used as the translucent reflective film 102,
There is a problem that it is difficult to control the film thickness so that both the reflectance and the transmittance are equal to or more than respective predetermined values because the reflectance and the transmittance have a very large thickness dependency.

[0008] In particular, in the case of commonly used gold, there is a problem that the price is high.

When a dielectric is used as the translucent reflective film 102, it is relatively easy to control the film thickness, but it is difficult to obtain a high reflectance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has an optical information recording medium having a light-transmitting reflective film having a reflectance and a transmittance of a predetermined value or more which are easy to manufacture at low cost. The purpose is to provide a method for the reproduction.

[0011]

According to the present invention, there is provided an optical information recording medium, comprising: a light-transmitting substrate; a first recording layer comprising a light-transmitting reflective film located on the substrate; An optical information recording medium comprising: a second recording layer made of a reflective film located on the recording layer; wherein the light-transmitting reflective film is a film made of a dye.

Further, the optical information recording medium of the present invention comprises a light-transmitting first substrate, a first recording layer made of a light-transmitting reflective film, a second recording layer made of a reflective film, and An optical information recording medium comprising: a first substrate and a second substrate bonded to each other in this order, wherein the light-transmitting reflective film is a film made of a dye. It is characterized by being.

Further, the optical information recording medium of the present invention has a light-transmitting first substrate having a light-transmitting reflective film formed on a surface thereof, and a second light-transmitting reflective substrate. A second substrate having a recording layer formed on a surface thereof, and bonding the first substrate and the second substrate such that the first recording layer and the second recording layer face each other. A combined optical information recording medium, wherein the light-transmitting reflective film is a film made of a dye.

Since the light-transmitting reflective film is a film made of a dye, it is easy to make both the reflectance and the transmittance higher than predetermined values, and it is easy to manufacture at low cost.

The adhesive used for the bonding is preferably a light-transmitting material such as a light-transmitting resin, and is preferably a light-transmitting ultraviolet-curable resin.

In particular, the bonding portion of the first substrate and the second substrate has at least a portion where the light-transmitting reflective film is not interposed.

Although the light-transmitting reflective film made of a dye has a low adhesive strength, in this case, since there is a portion where the light-transmitting reflective film is not interposed, the bonding strength between the first and second substrates is sufficient. And the durability of the medium is increased. In particular, the first and second
Preferably, the adhesive is directly interposed on the surface of the substrate, and the non-intervening portion is preferably the outer peripheral portion of the medium, or in the case of a disk, the central opening peripheral portion.

Particularly, the first recording layer and the second recording layer are separated from each other.

In this case, when reproducing the second recording layer, the reproduction light passing through the first recording layer is not sufficiently stopped, so that the unwanted interference effect exerted on the first recording layer is reduced. it can. As the separation distance, for example, about 30 to 70
μm is selected.

In particular, the reproduction of the information in the first and second recording layers is performed by irradiating reproduction light of the same wavelength. In this case, the playback device may have only one light source.

In particular, the dye is an organic dye having an absorption maximum on a shorter wavelength side than the wavelength of the reproduction light so as to increase the refractive index at the wavelength of the reproduction light. In particular, it is preferable that the refractive index be substantially maximum at the wavelength of the reproduction light.

In this case, since the first recording layer can have a high transmittance for the reproduction light and a high reflectance for the reproduction light, the information of the first and second recording layers can be reproduced well. .

In particular, the first recording layer is characterized in that the reflectance for the reproduction light is 25 to 40% and the transmittance for the reproduction light is 50% or more.

In this case, the first and second recording layers can be reproduced better. Note that the reflectance of the second recording layer is preferably greater than 70%.

In particular, the wavelength of the reproduction light is 600 nm to
660 nm. In this case, high-density reproduction can be performed.

In particular, the wavelength of the reproduction light is 635 nm or 650 nm.

Further, the dye is a cyanine dye or a phthalocyanine dye.

In this case, a suitable dye material can be selected to reproduce the first and second recording layers well.

In particular, the film made of the dye is characterized by being made of amorphous. In this case, noise at the time of reproduction can be reduced, so that the SN ratio is improved.

In particular, a light-transmitting protective film is provided under the first recording layer and / or on the first recording layer.

When a protective film is provided under the first recording layer, damage to the substrate when the first recording layer is formed can be prevented by the protective film serving as an underlayer of the first recording layer.

For example, when the first recording layer is formed on a resin substrate by spin coating using a solvent or the like, a solvent-resistant material may be selected as the protective film. When the recording layer is formed by vapor deposition or the like, an impact-resistant protective film may be used.

When a protective film is provided on the first recording layer, damage due to, for example, an adhesive on which the first recording layer is located can be prevented.

As the protective film, a dielectric film such as a SiO ₂ film or a polymer such as polyvinyl alcohol can be used.

Also, in the reproducing method of the optical information recording medium of the present invention, the laser beam outputted from the semiconductor laser is radiated so as to be focused on the first recording layer or the second recording layer. Information from one of the first recording layer and the second recording layer is selectively read.

In this case, the first and second recording layers can be reproduced more favorably.

In particular, the semiconductor laser is made of AlGaIn
It is a P-based semiconductor laser.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laminated disk-shaped optical information recording medium according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of the optical information recording medium of the present embodiment, and FIG. 2 is a schematic sectional view of the optical information recording medium of the present embodiment.

In the figure, reference numeral 1 denotes a first transparent substrate made of polycarbonate having a thickness of 0.6 mm and a diameter of 120 mm having an uneven surface 1a constituting an information bit (refractive index n =
1.4 to 1.6), 2 is an amorphous material having a high reflectivity and a high transmittance formed of an organic dye thin film formed by transferring the uneven shape of the surface 1a formed on the uneven surface 1a. A light-transmitting reflective film (first recording layer) 3 has a thickness of 0.6 having an uneven surface 3a constituting an information bit.
The light-transmitting second substrate (refractive index n = 1.4 to 1.6) made of polycarbonate having a diameter of 120 mm and a diameter of 120 mm is formed on the uneven surface 3a by a vacuum deposition method or the like. A reflection film (second recording layer) having a high reflectance of 800 ° thick Al obtained by transferring the uneven shape of 3a, preferably having a high reflectance of more than 70%, and 5 is a first and a second recording layer. The first and second substrates 1 and 3 are arranged so that
Is a translucent UV curable resin (translucent adhesive: refractive index n = 1.4 to 1.6) having a thickness of 40 μm and containing modified urethane acrylate as a main component for bonding. Cured by irradiation.

The reproduction of such a recording medium is performed at 600 nm to 660 nm output from an AlGaInP semiconductor laser.
In particular, the same laser light (reproducing light) of 635 nm or 650 nm is selectively condensed from the first substrate 1 side to one of the first and second recording layers 2 and 4 via a condensing lens (not shown). And the information from either one of the first and second recording layers 2 and 4 is selectively read.

The first recording layer 2 preferably has an optical property of a reflectance of 25 to 40% for the reproduction light and a transmittance of 50% or more for the reproduction light.

In the present embodiment, the thickness of the first recording layer 2 made of an organic dye having a high refractive index with respect to the reproduction light and a low light absorption is adjusted so that the reflectance is maximized, and the thickness is reduced. Thereby, high reflectance and high transmittance are achieved.

Specifically, an organic dye having an absorption maximum on the shorter wavelength side than the wavelength of the reproduction light utilizes the fact that the wavelength of the refractive index maximum generally exists on the longer wavelength side with respect to the wavelength of the absorption maximum. That is, as shown in FIG. 3, in the present embodiment, among organic dyes having an absorption maximum on the shorter wavelength side than the wavelength of the reproduction light, those having a refractive index maximum near the wavelength of the reproduction light are selected.

In this embodiment, the methanol solvent 0.3c
c is a cyanine dye having the following structural formula (3,3′-Diethyl-2,2
´-selenacarbocyanine iodide: absorption maximum is 570nm
In the vicinity, the refractive index at a wavelength of 635 nm is 3) A solution in which 15 mg is dissolved is applied on the uneven surface 1a of the first substrate 1 by a spin coating method, and then naturally dried.
A first recording layer 2 of an organic dye thin film made of amorphous with a thickness of 0 ° was formed.

[0045]

Embedded image

The first recording layer 2 had a reflectivity of 32% with respect to the 635-nm reproduction light, and a transmittance of 63% with respect to the reproduction light.

Therefore, in the present embodiment, the first recording layer 2
Has a high reflectance, so that the first recording layer 2 can be reproduced well, and in addition, since the first recording layer 2 has a high transmittance, the second recording layer 4 can be reproduced well.

Moreover, since the first recording layer 2 is made of amorphous, the effect of reducing noise during reproduction is lower than that of the polycrystalline first recording layer in which grain boundaries such as polycrystals are remarkably present. Is obtained.

In addition, in the present embodiment, the first recording layer 2
The use of an organic dye film makes it inexpensive, and the organic dye film is less dependent on film thickness in reflectivity and transmittance than a metal film, requiring high-precision film thickness control like a metal film. Therefore, manufacturing is easy.

On the other hand, as Comparative Example 1, when a dielectric film made of SiO ₂ was used for the first recording layer 2, the transmittance was as high as 85% for 635 nm reproduced light, but the reflectance was 15%. %, It was difficult to satisfactorily reproduce the first recording layer 2.

As Comparative Example 2, when an Au film formed by a sputtering method was used for the first recording layer 2,
The uniformity of the film thickness distribution is poor, the distribution of the reflectivity is 30 to 40%, and the reproduction of the first recording layer 2 may not be satisfactorily performed. In addition, it is necessary to control the film thickness with high accuracy. It was difficult to manufacture at low cost.

Next, a laminated optical information recording medium according to a second embodiment of the present invention will be described with reference to FIG. Note that the present embodiment differs from the first embodiment in the material and layer thickness of the first recording layer, and the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. .

In FIG. 4, reference numeral 12 denotes a high reflectivity and high transmittance made of an organic dye thin film formed by transferring the unevenness of the surface 1a formed on the uneven surface 1a as in the first embodiment. It is a light-transmitting reflective film (first recording layer) made of amorphous having a refractive index.

In this embodiment, a copper phthalocyanine dye having the following structural formula (the absorption maximum is around 560 nm, the wavelength is 635
The refractive index with respect to nm is 3.2).
A first recording layer 12 made of 900 ° amorphous was formed on the uneven surface 1a of the substrate 1.

[0055]

Embedded image

The first recording layer 12 had a reflectivity of 34% with respect to the 635 nm reproduction light and a transmittance of 60% with respect to the reproduction light.

Therefore, in the present embodiment, the first recording layer 1
2 has a high reflectance, so that the first recording layer 12 can be reproduced well, and in addition, since the first recording layer 12 has a high transmittance, the second recording layer 4 can be reproduced well. , First
The same effect as that of the embodiment can be obtained.

Next, a laminated optical information recording medium according to a third embodiment of the present invention will be described with reference to FIG. Note that the present embodiment differs from the first embodiment in the material and layer thickness of the first recording layer, and the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. .

In FIG. 5, reference numeral 22 denotes a high reflectivity and high transmittance made of an organic dye thin film formed by transferring the uneven shape of the surface 1a formed on the uneven surface 1a as in the first embodiment. It is a light-transmitting reflective film (first recording layer) made of amorphous having a refractive index.

In this embodiment, a solution in which a cyanine dye having the following structural formula (the absorption maximum is around 550 nm and the refractive index is 3 for a wavelength of 635 nm: 3) is dissolved at 20 wt% in a methanol solvent is formed into an irregular shape on the first substrate 1. After spin-coating on the surface 1a, it is naturally dried to 1000
A first recording layer 22 of an organic dye thin film made of a thick amorphous layer was prepared.

[0061]

Embedded image

The first recording layer 22 had a reflectivity of 30% for 635 nm reproduction light and a transmittance of 61% for the reproduction light.

Accordingly, in the present embodiment, the first recording layer 2
2 has a high reflectance, so that the first recording layer 22 can reproduce well, and in addition, the first recording layer 22 has a high transmittance, so that the second recording layer 4 can reproduce well. , First
The same effect as that of the embodiment can be obtained.

Next, a laminated optical information recording medium according to a fourth embodiment of the present invention will be described with reference to FIG. Note that this embodiment is different from the first embodiment in that the first recording layer is not formed on the entire surface of the first substrate, and the same portion or a corresponding portion as the first embodiment is provided. Are denoted by the same reference numerals and description thereof is omitted.

In FIG. 6, reference numeral 2 denotes a light-transmitting amorphous material having a high reflectivity and a high transmittance formed of an organic dye thin film formed by transferring the uneven shape of the surface 1a formed on the uneven surface 1a. Reference numeral 31 denotes a reflection film (first recording layer), which is an unformed portion where the first recording layer 2 does not exist on the first substrate 1 around the opening located at the center of the medium.

Therefore, in the first to third embodiments, the first and second substrates 1 and 3 are provided by the light-transmitting resin (light-transmitting adhesive) 5 via the organic dye thin film 2 having a low adhesion strength. Are bonded to each other, so that the mechanical strength is low. However, in the optical information recording medium of the present embodiment, the first and second substrates 1 and 3 are made of a light-transmitting resin (light-transmitting resin) as in the above embodiments. Adhesive 5), but a first layer made of an organic dye thin film
Since the first and second substrates 1 and 3 are also bonded by the portion (the unformed portion 31) where the recording layer 2 is not interposed, the first and second substrates 1 and 3 are bonded with high strength.

Next, a laminated optical information recording medium according to a fifth embodiment of the present invention will be described with reference to FIG. Note that the present embodiment is different from the fourth embodiment in that a protective film is formed below the first recording layer.
The same reference numerals are given to the same portions or corresponding portions as those of the embodiment, and the description is omitted.

In FIG. 7, reference numeral 41 denotes a light-transmitting protective film (n = 1.6 to 1.7) formed on the uneven surface 1a and made of a dielectric such as SiO _{2 having a} thickness of 200 °. 2 is a protective film 4
Reference numeral 31 denotes a light-transmitting reflective film (first recording layer) made of an amorphous material having a high reflectance and a high transmittance formed of an organic dye thin film obtained by transferring the uneven shape of the surface 1a formed on the surface 1a. This is an unformed portion on the first substrate 1 where the first recording layer 2 does not exist.

In this embodiment, a protective film 4 having solvent resistance is used as an underlayer of the first recording layer 2 made of an organic dye thin film.
Since the first recording layer 1 is formed, it is possible to prevent the surface of the substrate 1 from being dissolved by the solvent when the first recording layer 2 is formed by a spin coating method or the like. Therefore, various solvents can be selected as a solvent for dissolving the dye.

When the first recording layer 2 is formed by a method such as vapor deposition, it has an impact resistance, for example, 200
By providing a light-transmitting protective film made of a thick dielectric such as SiO ₂ , it is possible to prevent generation of undesired irregularities on the surface of the substrate 1.

Further, forming the light-transmitting protective film having solvent resistance on the upper side of the first recording layer (on the side of the adhesive 5) is performed by dissolving the first recording layer 2 when the adhesive 5 is formed. This is preferable because it can prevent

In each of the above embodiments, the dye film constituting the translucent reflective film does not contain an additive such as a binder, but may contain an additive as appropriate.

Although the dye film contains only one type of dye, it may contain a plurality of dyes, and the first recording layer may be formed of a plurality of dye films. Can also. Further, the dye is not limited to those described above, and various dyes can be appropriately selected.

Further, in each of the above embodiments, a polycarbonate substrate is used as the first and second substrates. However, other translucent synthetic resin substrates such as polymethyl methacrylate can be used as appropriate. The second substrate that is not on the light incident side does not have to be translucent.

Further, the light-transmitting resin (light-transmitting adhesive) 5 is not limited to the above resin, and any light-transmitting and adhesive material can be used as appropriate.

Although the Au film is used as the second recording layer 4, an Al film, a Cu film, or the like can be used.

[0077]

According to the present invention, it is possible to provide an optical information recording medium having a light-transmitting reflective film having a predetermined reflectance and transmittance which is easy to manufacture at low cost and a method for reproducing the same.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an optical information recording medium according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of the optical information recording medium according to the first embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the magnitude of absorption and the refractive index with respect to wavelength.

FIG. 4 is a schematic sectional view of an optical information recording medium according to a second embodiment of the present invention.

FIG. 5 is a schematic sectional view of an optical information recording medium according to a third embodiment of the present invention.

FIG. 6 is a schematic sectional view of an optical information recording medium according to a fourth embodiment of the present invention.

FIG. 7 is a schematic sectional view of an optical information recording medium according to a fifth embodiment of the present invention.

FIG. 8 is a schematic sectional view of a conventional optical information recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 1st recording layer (translucent reflective film) 3 2nd substrate 4 2nd recording layer (reflective film) 12 1st recording layer (translucent reflective film) 22 1st Recording layer (translucent reflective film) 31 Unformed portion 41 Protective film

Claims (15)

[Claims] 1. A first recording layer comprising a translucent substrate, a translucent reflective film located on the substrate, and a second recording comprising a reflective film located on the first recording layer. An optical information recording medium comprising: a light-transmitting reflective film, wherein the light-transmitting reflective film is a film made of a dye. 2. A light-transmitting first substrate, a first recording layer made of a light-transmitting reflective film, a second recording layer made of a reflective film, and a second substrate are provided in this order. An optical information recording medium in which a first substrate and the second substrate are bonded to face each other, wherein the translucent reflective film is a film made of a dye. recoding media. 3. A light-transmitting first substrate having a first recording layer made of a light-transmitting reflective film formed on a surface thereof, and a first light-transmitting substrate having a second recording layer made of a reflective film formed on a surface thereof. An optical information recording medium comprising: a first substrate and a second substrate bonded to each other such that the first recording layer and the second recording layer face each other. The optical information recording medium, wherein the translucent reflection film is a film made of a dye. 4. The bonding portion between the first substrate and the second substrate has at least a portion where the light-transmitting reflective film is not interposed. Optical information recording medium. 5. The method according to claim 1, wherein the first recording layer and the second recording layer are separated from each other.
5. The optical information recording medium according to 3 or 4. 6. The apparatus according to claim 1, wherein reproduction of information from the first and second recording layers is performed by irradiating reproduction light of the same wavelength. Optical information recording medium. 7. The dye according to claim 6, wherein the dye is an organic dye having an absorption maximum on a shorter wavelength side than the wavelength of the reproduction light so as to increase the refractive index at the wavelength of the reproduction light. Optical information recording medium. 8. The recording medium according to claim 6, wherein the first recording layer has a reflectance for the reproduction light of 25% to 40% and a transmittance for the reproduction light of 50% or more. Optical information recording medium. 9. The wavelength of the reproduction light is from 600 nm to 66 nm.
9. The optical information recording medium according to claim 6, wherein the optical information recording medium has a thickness of 0 nm. 10. The optical information recording medium according to claim 9, wherein the wavelength of the reproduction light is 635 nm or 650 nm. 11. The method according to claim 1, wherein the dye is a cyanine dye or a phthalocyanine dye.
The optical information recording medium according to 2, 3, 4, 5, 6, 7, 8, 9, or 10. 12. The method according to claim 1, wherein the film made of the dye is made of amorphous.
The optical information recording medium according to 6, 7, 8, 9, 10, or 11. 13. The method according to claim 1, further comprising a light-transmitting protective film under the first recording layer and / or on the first recording layer. 7, 8, 9, 10,
13. The optical information recording medium according to 11 or 12. 14. The method for reproducing an optical information recording medium according to claim 1, wherein a laser beam output from a semiconductor laser is supplied to the first recording layer or the second recording layer. A method for reproducing an optical information recording medium, comprising: irradiating a recording layer with light so as to condense the light; and selectively reading out information from one of the first recording layer and the second recording layer. 15. The semiconductor laser according to claim 1, wherein the semiconductor laser is AlGaInP.
15. The method for reproducing an optical information recording medium according to claim 14, wherein the method is a system semiconductor laser.