JPH06282880A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To provide an excellent optical information recording medium in which jitter, modulation factor exceed those of CD standards. CONSTITUTION:An optical information recording medium comprises a light transmissive board 12 on one surface side of a light absorption layer 14 containing organic dye, and a reflecting layer 18 on the other surface side of the layer 14 in such a manner that an optical phase of the layer 14 of a position of a pit formed by emitting a recording laser light is different from that of the layer 14 of a part except a position of the pit, wherein the layer 18 of the position of the pit protrudes to the side of the layer 14 or is in contact with the layer 18 at its position to form an air gap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a light absorbing layer containing an organic dye with a recording laser beam on which information is superimposed to form a pit having an optical phase difference with a background portion. And an optical information recording medium.

[0002]

2. Description of the Related Art As an optical information recording medium of this type, for example, Japanese Patent Application Laid-Open No. 2-87342 proposed by the applicant of the present invention is disclosed.
Japanese Patent Application Laid-Open No. 2-132656, Japanese Patent Application Laid-Open No. 2-1
The one disclosed in Japanese Patent No. 32657 is known.

Each of these optical information recording media has a transparent substrate, a light absorbing layer formed on the transparent substrate directly or through another layer, and on the light absorbing layer. An enhance layer that is transparent to the wavelength of the reproducing laser beam and that is formed directly or through another layer on the reflective layer and a reflective layer that is formed on the enhance layer directly or through another layer. It is what

In these optical information recording media, the organic dye contained in the light absorbing layer is decomposed in the portion irradiated with the recording laser beam to change the optical properties of the light absorbing layer. An optical path length difference (optical phase difference) is formed between a portion (pit) irradiated with the application laser beam and the background portion, and information is recorded as an optical bright and dark.

Since these optical information recording media employ an information recording system utilizing an optical phase difference, they are 70%.
It is possible to obtain an output signal having a high reflectance as described above and having a jitter and a modulation degree that satisfy the CD standard when reproducing data.

[0006]

By the way, in order to industrially manufacture an optical information recording medium satisfying the CD standard, it is necessary to make it easy for the jitter and the modulation degree of the output signal to fall within the CD standard. Therefore, it is desirable that the output signal jitter and modulation be as good as possible beyond the CD standard.

An object of the present invention is to provide an optical information recording medium having a jitter and a modulation degree which exceed the CD standard and which is further excellent.

[0008]

An optical information recording medium according to the present invention has a transparent substrate on one surface side of a light absorbing layer containing an organic dye, and the other surface side of the light absorbing layer. The optical phase of the light absorption layer at the pit portion formed by irradiating the recording laser beam is different from the optical phase at the portion other than the pit portion. .

In the optical information recording medium according to the present invention, the reflective layer at the pit portion projects toward the light absorbing layer side, or a void is formed in contact with the light absorbing layer side surface of the reflective layer at that portion. It is characterized by being.

In this optical information recording medium, the light transmissive substrate at the pit portion may be further projected toward the light absorption layer side, or between the light absorption layer and the reflection layer or between the light absorption layer and the light absorption layer. An enhancement layer that is transparent to the wavelength of the reproduction laser beam may be provided between the substrate and the optical substrate, or a hard protective layer may be formed outside the reflective layer.

[0011]

In the present invention, when the reflection layer at the pit portion is projected toward the light absorption layer side, the reproducing laser light is diffracted at the projecting reflection layer portion so that the pit portion is more than the background portion. It becomes darker, and the contrast between the pit portion and the background portion is improved.

Further, in the present invention, when a void is formed in contact with the surface of the reflection layer at the pit portion on the side of the light absorption layer, the reproducing laser light is diffracted in this void portion,
The brightness of the pit portion becomes darker than that of the background portion, and the contrast between the pit portion and the background portion is improved.

Further, in the present invention, when the light-transmitting substrate at the pit portion is projected toward the light absorbing layer, the optical path difference between the pit portion and the portion other than the pit becomes large, and the pit portion becomes large. Brightness becomes darker than the background part, and the contrast between the pit part and the background part becomes better.

Further, in the present invention, when an enhance layer transparent to the reproducing laser beam is provided between the light absorbing layer and the reflecting layer or between the light absorbing layer and the transparent substrate, the optical information The reflectance of the recording medium is improved.

Further, in the present invention, when the hard protective layer is formed on the outer side of the reflective layer, the reflective layer in the portion where the recording laser beam is irradiated and the pits are formed is on the light absorbing layer side. It becomes easy to project and form.

[0016]

1 is a partially cutaway perspective view of an example of an optical information recording medium according to the present invention, and FIG. 2 is an enlarged view of portion A in FIG. In this optical information recording medium 10, as shown in the figure, the light absorption layer 14 and the enhancement layer 1 are provided on one surface of the transparent substrate 12.
6, the reflective layer 18 and the protective layer 20 are laminated in this order.

As shown in FIG. 2, the optical information recording medium 10 is formed with pits by irradiating the portion shown by the arrow B with the recording laser beam. Part 22 of the pit of the light absorption layer 14
Is in a contracted state after heat is generated, and the organic dye is denatured so that the optical phase is different from the optical phase of the portion other than the pit portion.

The reflective layer 18 is a light absorbing layer 14 at the pit portion.
It is a protrusion 24 that projects to the side. Further, the enhancement layer 16 protrudes toward the light absorption layer 14 side at this portion, and the translucent substrate 12 also protrudes toward the light absorption layer 14 side at this portion.

Examples of the translucent material forming the translucent substrate 12 include polycarbonate, acrylic resin, polyolefin, epoxy resin, glass and the like. Any material having a refractive index of 1.4 to 1.6 and excellent impact resistance can be used.

The transparent substrate 12 can be molded by means such as injection molding. In addition, the transparent substrate 1
The 2 may have pregrooves formed in a spiral shape in advance. The pregroove may be under any condition that is usually considered, but the depth is 50
It is preferably about 300 nm. The pre-groove is generally formed by pressing a stamper when manufacturing the transparent substrate 12 by injection molding, but the pre-groove is not necessarily limited to this method.

The dye contained in the light absorbing layer 14 is preferably a light absorbing organic dye. As the light-absorbing organic dye, specifically, for example, cyanine dye, triarylmethane dye, pyrylium dye, phenanthrene dye, tetradehydrocholine dye, triarylamine dye, squarylium dye, croconic methine dye,
Examples thereof include phthalocyanine dyes and azurenium dyes, but other light-absorbing organic dyes can also be used.

The light absorbing layer 14 may contain other dyes, resins (for example, thermoplastic resins such as nitrocellulose, thermoplastic elastomers), liquid rubber, and the like. Light absorbing layer 14
Is a translucent substrate 12 on which a pre-groove is formed by dissolving the above-described dye and any additive in an organic solvent (for example, alcohol, acetylacetone, methyl cellosolve, toluene, etc.), or of the translucent substrate 12. Coated on top of the other layers coated above.

As the coating method in this case, vapor deposition, L
Examples of the method include the B method and the spin coating method.
The spin coating method is preferred because the layer thickness can be controlled by adjusting the concentration, viscosity, and drying rate of the solvent.

The enhancement layer 16 is made of, for example, SiO ₂ ,
Amorphous SiO, Si ₃ N ₄ , SiN, AlN, Z
It can be formed of an inorganic dielectric such as nS or an organic dielectric such as silicon resin. When the enhancement layer 16 is formed of an inorganic dielectric material, the raw material is sputtered on the light absorption layer 14 directly or through another layer. Enhance layer 1
When 6 is formed of an organic dielectric, the raw material liquid is spin-coated on the light absorption layer 14 directly or through another layer.

The film thickness d _ehs of the enhancement layer 16 is the real part n _abs of the complex refractive index of the light absorption layer 14, the film thickness d _abs of the light absorption layer 14, and the real part n of the complex refractive index of the enhancement layer 16.
_ehs, the film thickness d _ehs and reproducing Les enhancement layer 16 - the value given by the wavelength of the laser light _{λ ρ = (n abs · d} abs
+ N _ehs · d _ehs ) ÷ λ is set so that 0.05 ≦ ρ ≦ 1.6.

The reflective layer 18 is preferably a metal film such as gold, silver, aluminum or an alloy containing these.
The metal film can be formed by means such as vapor deposition and sputtering. The reflective layer 18 may be coated with an oxidation resistant layer in order to prevent its oxidation.

In order to protect the reflective layer 18, it is preferable to form the protective layer 20 on the reflective layer 18 directly or via another layer. It is desirable that the protective layer 20 be formed of a synthetic resin having excellent impact resistance. For example, it is formed by applying an ultraviolet curable resin such as a polyacrylate resin by a spin coating method and irradiating it with ultraviolet rays to cure it.

The optical information recording medium 10 of the example of FIG.
Although the reflective layer 18 protrudes toward the light absorption layer 14 at the pit portion, as shown in FIG. 3, a gap 26 is formed at the pit portion between the reflective layer 18 and the enhancement layer 16. May be.

Further, in the optical information recording medium of the examples of FIGS. 2 and 3, the enhancement layer 1 is provided between the light absorption layer 14 and the reflection layer 18.
6 is provided, the enhancement layer 16 may be provided between the translucent substrate 12 and the light absorption layer 14.

Example 1 First, a disc-shaped light-transmitting substrate 12 having spiral-shaped pregrooves was formed by an injection molding method. Here, polycarbonate was used as the material of the transparent substrate 12. The transparent substrate 12 has a thickness of 1.2 m.
m, outer diameter 120 mmφ, and inner diameter 15 mmφ. The pre-groove has a width of 0.8 μm, a depth of 0.08 μm and a pitch of 1.6 μm, and the diameter of the transparent substrate 12 is 46 to 117 m.
It was formed in the range of mφ.

Then, a solution of 1,1'dibutyl 3,3,3 ', 3' tetramethyl 5,5'diethoxyindoca-bocyanine perchlorate in hydroxyacetone was spin-coated on the transparent substrate 12. -Coating method and film thickness d
The light absorption layer 14 with _abs = 70 nm was formed.

Here, this hydroxyacetone solution is
5.0 g of 1,1'dibutyl 3,3,3 ', 3'tetramethyl 5,5'diethoxyindoca-bocyanine per
A chlorate dissolved in 10 cc of hydroxyacetone was used. The real part n _abs of the complex refractive index of the light absorption layer 14 is 2.65, and the imaginary part k _abs thereof is 0.
It was 04.

Next, SiO ₂ was sputtered on the light absorption layer 14 to form an enhancement layer 16 having an average film thickness _dehs of 50 nm. The real part n _ehs of the complex refractive index of the enhancement layer 16 was 1.45.

Next, Au was sputtered on the enhancement layer 16 to form a reflection layer 18 having a film thickness of 70 nm.

Next, a polyacrylate resin was applied onto the reflective layer 18 by a spin coating method, and was irradiated with ultraviolet rays to be cured to form a protective layer 20 having a film thickness of 10 μm.

Next, a laser beam having a wavelength of 780 nm is applied to the optical information recording medium thus obtained at a linear velocity of 1.2 m / s.
It was irradiated with ec and a recording power of 6.0 mW to record an EFM signal. Then, a commercially available CD player (Aurex XR-V73, wavelength of reproduction light λ =
When reproduced at 780 nm), the reflectance of the reproduction laser light is 79%, the jitter is 26, and I ₁₁ / I _top is 75.5.
%, I ₃ / I _top was 32.05, and block error rate BLER was 3.0 × 10 ^-4 .

According to the CD standard, the reflectance is 70% or more, the jitter is 30 ns or less, the modulation degree I ₁₁ / I _top is 0.6 or more,
It is defined that I ₃ / I _top is 0.3 to 0.7 and the block error rate BLER is 3 × 10 ^-2 or less. The optical information recording medium according to this embodiment is sufficiently above this standard. Was satisfied with.

Next, when the pits were observed from the transparent substrate 12 side with an electron microscope, the light absorption layer 1 of the transparent substrate 12 was observed.
I found that the side of 4 was protruding. In addition, the protective layer 20
When the reflective layer 18 was peeled off and observed from behind with an electron microscope, it was found that the reflective layer 18 was recessed at the pits.

Further, although the reflective layer 18 is not dented at the pit, when the surface of the enhancement layer 16 is observed by melting the reflective layer 18 in a sample having a good jitter, it is found that the pit is dented. It was

[0040]

According to the present invention, since the contrast between the pit portion and the background portion is improved, it is possible to obtain an optical information recording medium in which the jitter and the degree of modulation exceed the CD standard and which is even better. is there. .

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of an example of an optical information recording medium according to the present invention.

FIG. 2 is an enlarged view of part A of FIG.

FIG. 3 is a partial sectional view of another example of the optical information recording medium according to the present invention.

[Explanation of symbols]

 10 Optical Information Recording Medium 12 Translucent Substrate 14 Light Absorbing Layer 16 Enhance Layer 18 Reflective Layer 20 Protective Layer 22 Pit Part of Light Absorbing Layer 24 Projection 26 Void

Claims (5)

[Claims] 1. A light-absorbing layer containing an organic dye has a translucent substrate on one surface side, and a reflective layer on the other surface side of the light-absorbing layer, and is irradiated with a recording laser beam. In the optical information recording medium in which the optical phase of the light absorption layer at the pit portion formed differently from the optical phase of the light absorption layer at the portion other than the pit portion, An optical information recording medium, wherein a reflective layer projects toward the light absorbing layer. 2. A light-absorbing layer containing an organic dye has a light-transmitting substrate on one surface side, and a light-reflective layer on the other surface side of the light-absorbing layer, and is irradiated with a recording laser beam. In the optical information recording medium in which the optical phase of the light absorption layer at the pit portion formed differently from the optical phase of the light absorption layer at the portion other than the pit portion, An optical information recording medium, wherein a void is formed in contact with the surface of the reflective layer on the side of the light absorbing layer. 3. The optical information recording medium according to claim 1 or 2, wherein the transparent substrate at the pit portion is projected toward the light absorbing layer. 4. The optical information recording medium according to claim 1, wherein the wavelength of the reproducing laser light is between the light absorbing layer and the reflecting layer or between the light absorbing layer and the transparent substrate. An optical information recording medium having an enhancement layer transparent to. 5. The optical information recording medium according to claim 1, wherein a hard protective layer is formed outside the reflective layer.