JPH0366042A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium having high absorptivity for light of a dye layer and high reflectance be providing a dye layer having specified properties on a resin substrate and providing a reflecting layer and a protective layer thereon. CONSTITUTION:The medium consists of a resin substrate 2, dye layer 3, reflecting layer 4 and protective layer 5 successively deposited. The dye layer 3 has refractive index (n) of 1.8 - 3.2 and extinction factor (k) of 0.04 - 0.12 for 700 - 850 wavelength, and 100 - 1,500 Angstrom thickness in the area for light irradiation. When the medium is irradiated with light for recording, a mixture part 85 comprising the substrate material and decomposed dye is formed. At the same time, a part 8 having low refractive index and containing the decomposed dye from the mixture part 85 is formed. When the medium is irradiated with light for reproducing from the substrate side 2, reflectance from nonrecorded area is >60%, while reflectance from recorded area is as smaller as <40% of the reflectance from nonrecorded area. By this method, the low refractive index part 8 and the mixture part 85 are formed between the sub strate 2 and the dye layer 3 by irradiation of recording light and this area irradiated with light gives significantly decreased reflectance. Thereby, preferable optical record ing can be realized with reproducing performance according to CD standards.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical recording medium, and particularly to a write-once type optical recording disk compatible with a compact disk.

<Prior Art> An optical recording disc capable of additional writing or recording has been proposed in accordance with the compact disc (hereinafter abbreviated as CD) standard (S Kei Electronics January 23, 1989 issue, No. 465.P2O3, Kinki Chemical Society Functional Colorants Subcommittee, March 3, 1989, Osaka Science and Technology Center, PROCEEDINGSSPIE-T
HE INTERNATIONAL 5OCIE DINGY FOR0PTICAL ENGINEERING
VOL, 1078 PP8O-87,”0PTICAL
DATA 3-0RAGE TOPICAL M
EETING''17-19゜JANUARY 198
9 LO3ANGELES, etc.).

This material is formed by depositing a dye layer, an Au reflective layer, and a protective film in this order on a transparent substrate. That is, the reflective layer is provided in close contact with the dye layer.

When the dye layer of such an optical recording disk is irradiated with a recording laser beam, the dye layer absorbs the light and melts, and the substrate also softens, causing the bit part whose reflectance decreases due to the phase difference of the light to be exposed to the substrate and the dye. It is said that it is formed at the interface with the layer.

Conventionally, an air layer was provided on the dye layer in order to form bits in the dye layer, but in this proposal, the reflective layer is provided in close contact with the dye layer, so it is possible to reduce the total thickness of the disc according to the CD standard. A configuration of 1.2 mm is possible.

<Problems to be Solved by the Invention> The present inventors conducted various additional tests on such optical recording disks.

As a result, only a dye layer having a constant refractive index n (real part of the complex refractive index) and a constant extinction coefficient k (imaginary part of the complex refractive index) and a predetermined thickness can be used as a contact type. We have found that effective recording can be performed even if

When a resin substrate is used, the bit portion generated by recording light irradiation is composed of a mixed portion of the substrate and the dye decomposition product and a low refractive index portion on this mixed portion. It has been found that good recording and reproduction can be achieved by reducing the reflectance.

An object of the present invention is to provide a contact type optical recording medium that can perform good recording and reproduction.

Means for Solving the Problems> These objects are achieved by the following inventions (1) to (8).

(1) In an optical recording medium having a dye layer on a resin substrate, and a reflective layer and a protective film laminated on the dye layer, the dye layer has a refractive index n of 1.8 to 1.8 at a wavelength of 700 to 850 nm. 3.2 and extinction coefficient k of 0.04 to 0.1
2, and the thickness of the recording light irradiated part of the dye layer is 1000
~1,500 people, and when the recording light is irradiated, a mixed area of the substrate and the dye decomposition product is created, and a low refractive index area containing the dye decomposition product is created on this mixed part, and when the reproduction light is irradiated from the substrate side. An optical recording medium characterized in that the reflectance of the unrecorded portion is 130% or more, and the reflectance of the recorded portion is 40% or less of the reflectance of the unrecorded portion.

(2) In an optical recording medium having a dye layer on a resin substrate and a reflective layer and a protective film laminated on the dye layer, the dye layer has a refractive index n of 1.8 to 1.8 at a wavelength of 700 to 850 nm. 3.2 and extinction coefficient k of 0.04 to 0.1
2, and the thickness of the recording light irradiated part of the dye layer is 1000
-1,500 people, and when the recording light is irradiated, a mixed area is created between the substrate and the dye decomposition product, and a hollow low refractive index area is created above this mixed area, and when the reproduction light is irradiated from the substrate side, no recording occurs. An optical recording medium characterized in that the reflectance of the recorded portion is 60% or more, and the reflectance of the recorded portion is 40% or less of the reflectance of the unrecorded portion.

(3) In an optical recording medium having a dye layer on a resin substrate, and a reflective layer and a protective film laminated on the dye layer, the dye layer has a refractive index n of 1.8 to 1.8 at a wavelength of 700 to 850 nm. 3.2 and extinction coefficient k of 0.04 to 0.1
2, and the thickness of the recording light irradiated part of the dye layer is 1000
- 1,500 people, a mixed part of the substrate and the dye decomposition product is generated by recording light irradiation, and a low refractive index part is created on this mixed part, and this low refractive index part contains the cavity and the dye decomposition product. When the reproduction light is irradiated from the substrate side, the reflectance of the unrecorded part is 60% or more, and the reflectance of the recorded part is 40% or less of the reflectance of the unrecorded part. Characteristic optical recording media.

(4) The thickness of the mixing part is 0.1 to 0.0 times the thickness of the dye layer.
The optical recording medium according to any one of (1) to 3) above, which is 4 times as large.

(5) The optical recording medium according to any one of (1) to 4 above, wherein the substrate has a groove, and the recording light is irradiated onto the dye layer within the groove.

(6) The optical recording medium according to (5) above, wherein the sum of the thickness of the dye layer in the land portion and the group depth is greater than the thickness of the dye layer in the groove portion.

(7) The depth of the groove is 250 to 550 people,
The land width is 0.8 to 1.3 times the groove width (
5) or the optical recording medium according to (6).

(8) The optical recording medium according to any one of (1) to 7 above, wherein the reflective layer is made of any one of Au, A4Mg alloy, AgNi alloy, Ag, Pt, and Cu.

<Function> In the optical recording medium of the present invention, since k of the dye layer is set within a predetermined range, the light absorption rate and light reflectance of the dye layer are high.

In addition, since n and the thickness of the dye layer are set within a predetermined range,
High reflectance can be obtained.

Further, by irradiation with the recording light, a mixed portion of the thermoplastic resin substrate and the dye decomposition product and a low refractive index portion on this mixed portion are formed. Therefore, in the recording light irradiation section, the decrease in reflectance can be increased.

With such a configuration, the optical recording medium of the present invention exhibits a high reflectance in the unrecorded area and a large decrease in reflectance in the recorded area, so that good optical recording that can be played back by a CD player is possible. Become.

Specific composition> Hereinafter, a specific configuration of the present invention will be explained in detail.

FIG. 1 shows an example of an optical recording medium 1 of the present invention.

This optical recording medium 1 is of a contact type having a dye layer 3 on a substrate 2, and a reflective layer 4 and a protective film 5 formed in close contact with the dye layer 3.

The substrate 2 receives recording light and reproducing light (700 to 850 nm
Semiconductor laser light of about 780 nm, especially in the case of CD
m), it is made of a substantially transparent (preferably transmittance of 89% or more) resin. This allows recording and reproduction from the back side of the substrate.

The substrate is in the shape of a normal size disk, and when used as a CD, has a thickness of about 1.2 mm and a diameter of 80 to 120 mm.

In the present invention, a resin material, particularly a thermoplastic resin, is used as the substrate material. There is no particular restriction on the thermoplastic resin that can be used, and any of polycarbonate resin, acrylic resin, amorphous polyolefin, TPX, etc. may be used.

It is preferable that a groove for tracking is formed on the surface of the substrate 2 on which the dye layer 3 is formed.

The groove is preferably a continuous spiral groove, with a depth of 250 to 550 people and a width of 0.5 to 1.
．． 1 to 1, especially 0.5 to 0.8-, land (the part between adjacent grooves) width 0.5 to 1.1, especially 0.
It is preferably from 8 to 1.1.

Further, the land width is preferably about 0.8 to 1.3 times, more preferably 1.0 to 1.3 times, particularly about 1.2 times the groove width.

By configuring the groove in this manner, a good tracking signal can be obtained without lowering the reflection level of the groove portion.

Incidentally, the groove can also be provided with concavities and convexities for address signals.

Further, it is also possible to meander the groove and provide a signal for rotation control or time axis control.

In the present invention, when the substrate has a groove, it is preferable that the recording light be configured to irradiate the dye layer within the groove. That is, the optical recording medium of the present invention is preferably used as an optical recording medium for groove recording.

By performing groove recording, the effective thickness of the dye layer can be increased.

The dye layer 3 has an extinction coefficient k (imaginary part of the complex refractive index) of 0.04 to 0.12 at the recording and reproducing light wavelengths. In this case, extremely favorable results are obtained when k is 0.04 to 0.08.

In a contact type optical recording medium, the extinction coefficient k of one dye layer is 0.0.
When it is less than 4, the light absorption rate of the dye layer decreases and recording cannot be performed with normal recording power. Also, k is 0.
If it exceeds 12, the reflectance will fall below 60% and the CD
Cannot be played by player.

The refractive index n (real part of the complex refractive index) of the dye layer 3 is 1.8 to
3.2, preferably 2.0 to 3.0.

When n<1.8, the reflectance decreases, and the degree of decrease in the refractive index of the bit part after recording is small, and the degree of phase change of the reflected light becomes small, making it impossible to obtain a signal of sufficient size. , it tends to be difficult to play back on a CD player.
Moreover, in order to make n>3.2, it is difficult to obtain raw material pigments.

There are no particular restrictions on the dyes used, but cyanine-based, phthalocyanine-based, naphthalocyanine-based, anthraquinone-based, azo-based, triphenylmethane-based, biryllium or thiapyrylium salt-based, metal complex dyes, and the like are preferred.

The cyanine dye is preferably a cyanine dye having an indolenine ring.

Further, a dye may be mixed with a quencher to be used as a mixture, in which case the quencher functions as a dye. Furthermore, an ionic combination of a dye cation and a quencher anion may be used as the dye.

In the above case, the dye is preferably a cyanine dye having an indolenine ring, and the quencher is preferably a metal complex dye such as a bisphenyldithiol metal complex.

For details of preferred dyes and quencher conjugates, see JP-A Nos. 59-24692, 59-55794, and 5
No. 9-55795, No. 59-81194, No. 59-8
No. 3695, No. 60-18387, No. 60-1958
No. 6, No. 60-19587, No. 60-35054,
No. 60-36190, No. 60-36191, No. 60
-44554, 60-44555, 60-44
No. 389, No. 60-44390, No. 60-47069
No. 60-20991, No. 60-71294, No. 60-54892, No. 60-71295, No. 60-
No. 71296, No. 60-73891, No. 60-738
No. 92, No. 60-73893, No. 60-83892, No. 60-8544'9, No. 60-92893, No. 60-159087, No. 60-162691, No. 6
No. 0-203488, No. 60-201988, No. 60
-234886, 60-234892, 61~
No. 16894, No. 61-11292, No. 61-112
No. 94, No. 61-16891, No. 61-8384,
No. 61-14988, No. 61-163243, No. 6
1 to 210539, Japanese Patent Application No. 60-54013, etc.

In the present invention, from among the dyes, dye-quencher mixtures, and dye-quencher conjugates described above, those having n and k within the above ranges may be selected, or they may be synthesized by new molecular design.

Note that the k of a dye for recording light and reproduction light varies from about 0 to 2 depending on its skeleton and substituents, so when selecting a dye with a k of 0.04 to 0.12, it is important to There are restrictions on substituents. For this reason, there may be restrictions on the coating solvent, or coating may not be possible depending on the substrate material. Alternatively, vapor phase film formation may not be possible.

Furthermore, when designing a new molecule, a large amount of effort is required for design and synthesis.

On the other hand, according to the experiments conducted by the present inventors, the value k of a mixed dye layer containing two or more types of dyes corresponds to the k value of a dye layer composed of each dye used alone, and approximately corresponds to the mixing ratio thereof. It turned out to be. Therefore, in the present invention, the dye layer 3
may be formed by dissolving two or more types of dyes.

At this time, in most dye mixing systems, k can be obtained that is approximately proportional to the mixing ratio. That is, when the mixing fraction of the i type of dye and k are respectively CL and ki, k becomes approximately ΣC1ki. Therefore, by mixing dyes with different k values by controlling the mixing ratio, k
=0.04-0.12 dye layer can be obtained.
Therefore, the dye to be used can be selected from a very wide range of dye groups.

As a result, there are no restrictions on film-forming methods such as restrictions on coating solvents, etc., and it is also possible to use dyes that are easy to synthesize and are inexpensive, dyes with good properties, and dyes that are poorly soluble. be able to.

When the dye layer 3 is a mixed dye layer, the dye used is n=
1.9 to 3.2, and may be selected from those within the scope of the claims.

In addition, when measuring n and k, a measurement sample is prepared by forming a dye layer on a predetermined transparent substrate to a thickness of, for example, about 400 to 800 layers under actual conditions. Next, the reflectance through the substrate or from the dye layer side is measured. The reflectance is measured by specular reflection (
51). Also, measure the transmittance of the sample. From these measurements, for example, Kyoritsu Zensho ``
n and k may be calculated according to "Optics" by Kozo Ishiguro, pp. 168-178.

The thickness of the dye layer 3 at the portion irradiated with the recording light is 1
The number of people is preferably 000 to 1500. Outside this range, the reflectance decreases, making it difficult to reproduce on a CD player.

Note that when a groove is formed on the substrate 2, the recording light is irradiated onto the groove portion, so the above dye layer thickness is the thickness at the groove portion. Further, when the substrate 2 does not have a groove, the upper surface of the dye layer 3 is flat, but when the substrate 2 has a groove, a sufficient tracking signal can be obtained in the push-pull track error control described later, and the top surface of the dye layer 3 is flat. In order to ensure that the reflection level in the groove and land areas is sufficiently large when played back by
It is preferable that the sum of the thickness of the dye layer in the land portion and the depth of the groove is larger than the thickness of the dye layer in the groove portion. In this case, the thickness of the dye layer in the land part is 0.7 to 0.9 times the thickness of the dye layer in the groove part, and the thickness of the dye layer in the groove part is 0.78 to 0.8.
Preferably, it is 8 times larger than Luco. Below this range, a sufficient tracking signal cannot be obtained. Furthermore, when forming the dye layer 3 by coating, it is difficult to obtain a value exceeding this range.

The thickness of the dye layer in the groove portion and the land portion can be measured by a cross-sectional measuring device using a scanning electron microscope.

By configuring the dye layer 3 as described above, when the reproduction light is irradiated from the substrate 2 side after forming the reflective layer 4 described later, the reflectance of the unrecorded area through the substrate 2 can be increased to 60% or more, especially 70%.
% or more, and the reflectance of the recorded portion can be made 40% or less of the reflectance of the unrecorded portion. Therefore, the optical recording medium of the present invention can be favorably recorded and reproduced by a CD player.

Although there is no particular restriction on the method of forming the dye layer 3, in the present invention,
It is preferable to form the layer by coating, since the degree of freedom and ease in dye selection, medium design, and manufacturing are expanded.

Various solvents such as ketone, ester, ether, aromatic, halogenated alkyl, and alcohol solvents can be used for coating the dye layer. For application, a spin cord or the like may be used.

A reflective layer 4 is provided on the dye layer 3 in direct contact with it.

As the reflective layer 4, Au, A4Mg alloy, Al2N i
Although high reflectance metals such as alloys, Ag, Pt, and Cu may be used, it is preferable to use one of Au, Al2Mg alloy, and Aj2Ni alloy because the reflectance is particularly high among these metals. However, since Au has insufficient adhesion with the dye layer, in order to increase the adhesion between the reflective layer and the dye layer, it is necessary to use Aj2Mg alloy and Aj2Mg alloy.
Preferably, one of the QN i alloys is used. Note that the Mg content in the Al2Mg alloy is preferably about 3 to 7 wt%. In addition, the Ni content in the AβNi alloy is 3
About 4 wt% is preferable.

The thickness of the reflective layer 4 is preferably 500 Å or more,
The layer may be formed by vapor deposition, sputtering, or the like. Further, although there is no particular restriction on the upper limit of the thickness, in consideration of cost, production time, etc., it is preferably about 1000 Å or less. As a result, the reflectance of the unrecorded portion of the recording layer through the substrate can be 60% or more, particularly 70% or more.

A protective film 5 is provided on the reflective layer 4 .

The protective film 5 may be formed of various resin materials such as ultraviolet curing resin, and generally has a thickness of about 10 to 100 microns.

To perform recording or additional writing on the optical recording medium 1 having such a configuration, recording light of, for example, 780 nm is irradiated in a pulsed manner through the substrate 2.

The power of the recording light is preferably about 5 to lomW, and the linear velocity during recording is about 1.2 to 1.4 a+/s.

As a result, the dye layer 3 absorbs light and generates heat, and the substrate 2 is also heated at the same time. As a result, the dye melts or decomposes near the interface between the substrate 2 and the dye layer 3, and pressure is applied to the interface between the dye layer 3 and the substrate 2.

Furthermore, since the substrate 2 is made of thermoplastic resin, the substrate material and the dye decomposition product are mixed.

As a result, deformation occurs in the vicinity of the interface, and as shown in FIG. 1, a mixed portion 7 of the substrate and the decomposed dye is formed in the dye layer in a convex shape, such as a hemispherical shape.

In this mixing section 7, the resin constituent material or its decomposition product and the dye or its decomposition product exist in a dispersed or compatible state with each other, or partially react with each other to form a mixed state. be.

The formation of this mixed portion can be confirmed by SEM or STM (tunneling microscope) on the substrate surface after the dye layer has been removed after recording.

Furthermore, a low refractive index section 8 is formed on this mixing section 7 .

The low refractive index portion 8 contains cavities or dye decomposition products.

In the illustrated example, a cavity 81 is formed in the center above the mixing part 7, and a dye decomposition product containing part 85 is formed around this cavity 81. In addition, the low refractive index portion 8 may be formed by the cavity 81 or the dye decomposition product alone, or may take various forms when both are present.

Such a state can be confirmed by no longer observing a dye peak in an ESCA%FT-IR spectrum or the like, and can also be confirmed by an electron microscope.

In the present invention, it is preferable that the mixing part 7 and the low refractive index part 8 have the following refractive index and dimensions.

Since the refractive index of the substrate is 1.57 to 1.59, the refractive index of the mixing portion 7 does not fall outside the range of 1.4 to 1.6 even if mixing with the dye decomposition product occurs.

The thickness of the mixing part 7 is preferably 0.1 of the thickness of the dye layer 3.
~0.4 times, more preferably 0.2 to 0.4 times.

The thickness of the mixing part 7 is unlikely to fall outside this range.

Further, the low refractive index portion 8 exists over almost the entire area between the mixing portion 7 and the reflective layer 4 in the bit portion.

After forming a recording bit composed of such a mixing part 7 and a low refractive index part 8, when a reproduction light of, for example, 780 nm is irradiated through the substrate 2, the bit will separate the land part from the recorded part, or the unrecorded part from the recorded part. This causes a phase difference between the reflected light and the reflected light, and the reflectance decreases by 60% or more. Note that the power of the reproduction light is approximately 0.1 to 1.0 mW.

On the other hand, since the unrecorded portion exhibits a high reflectance of 60% or more, particularly 70% or more, it can be reproduced by a CD player.

Note that the optical recording medium of the present invention can be played back by a normal CD player, and the tracking control at this time is performed by so-called push-pull tracking error control that utilizes the interference between the reflected light from the groove portion and the reflected light from the land portion. Alternatively, a so-called 3-beam method may be used in which tracking control is performed by irradiating recording bits with a laser beam for tracking control in addition to the reproduction light.

On the other hand, in an unrecorded state, no bits are formed, so
It is difficult to perform three-beam tracking control during recording. Therefore, in the optical recording medium of the present invention,
It is preferable that tracking control during recording be performed by push-pull track error control.

Color "L△" 2 <Example> 120+nmφ with continuous groove, thickness 1.2mm
Various dye layers were formed on a polycarbonate resin substrate. The groove is 300 deep, 0.65 wide,
The land width was 0.95μ.

On this dye layer, Au is deposited to a thickness of 1000 μm by vapor deposition to form a reflective layer, and then an ultraviolet curable resin containing oligoester acrylate is coated and cured with ultraviolet light to form a protective film with a thickness of 50 μm. A recording disc sample was obtained.

The dyes contained in the dye layers of each sample No. 1 to 3 are shown below.

The CβO4- dye layer was deposited by spin cord coating while rotating the substrate at 50 rpm.

The coating solution used was a 3.0 wt% Cellosolve solution for sample No. 1.3, and a 3.0 wt% solution of Cellosolve for sample No. 2.
Here, a 3.0 wt% methanol solution was used.

The thickness of the dye layer within the groove after drying is 1300 Å.
The thickness outside the groove was 1050 people. The thickness of the dye layer was measured using a cross-sectional measuring device (PMS-1 manufactured by Elionix ■) using a scanning electron microscope.
I went to Yosu.

Table 1 below shows the dye, quencher, and their contents contained in the dye layer of each sample, as well as the refractive index (n) and extinction coefficient (k) of the dye layer at 780 nm.

For n and k, a solution containing the above dye and quencher is formed on a measurement substrate to a dry film thickness of 600 mm to form a test dye layer, and n and k of this test dye layer are measured. It was determined by

This measurement was carried out by back calculation from the measured values of reflectance and transmittance, in accordance with the description in "Optics" (written by Kozo Ishiguro, Prefectural Zensho), pages 168-178. Further, dichloroethane was used as the coating solvent, and a glass substrate was used as the measurement substrate.

Table 1 1 Al(96)+A2(4)
2.3 0.082 AI(10
0) 2.4 0.033
AI (90) + A2 (10) 2.3
0.14 For each sample obtained, the wavelength 780
CD signal (190-720 kHz) using nm laser
Nine types of pulses of z (duty: 50%) were recorded.

The recording power was 7.0mW, and the linear velocity during recording was 1.3+n/
It was set as s. Note that recording was performed on the groove section.

Tracking during recording was performed using push-pull track error control.

Then, it was played back on a commercially available compact disc player. The reproduction power was 0.2 ml.

As a result, good recording and reproduction could be performed with sample N001. In these samples, a reflectance of 70% or more was obtained in the unrecorded portion, and the reflectance of the recorded portion of the 11T pulse of the CD signal was 40% or less of the reflectance of the unrecorded portion.

In addition, after recording these samples, the reflective layer was removed and
When the bit part was observed using STM, cavities were observed in the bit part, and decomposition products of the dye were found to be attached around the pits. When the dye layer was also removed and the recording area of the substrate was observed in the same manner, a bulge in the mixed area with a height of 200 to 300 people was observed.

On the other hand, in Sample No. 2, the absorption of the dye layer was small and the recording was insufficient. When the recording light irradiated area of this sample was observed in the same manner as above, it was found that the cavity in the dye layer was small and undecomposed dye remained. Further, the height of the swelling of the mixed portion of the recording portion of the substrate was 100 Å or less.

In addition, sample No. 013 had small reflection and was difficult to reproduce. When the recording light irradiation area of this sample was observed in the same manner as above, there were sufficient cavities and adhesion of dye decomposition products in the dye layer, and the height of the bulge in the mixed area was approximately 350 mm.
It was a person.

Next, for each of the above-mentioned samples of the present invention, a sample in which the thickness of the dye layer at the groove part was less than 1000 mm and a sample in which the thickness exceeded 1500 mm were prepared, and the same recording and reproducing test as above was conducted. . As a result,
In samples with a diameter of less than 1000 A and more than 500 A, the reflectance of the groove portion was less than 60%, and sufficient reflectance necessary for reproduction could not be obtained.

Furthermore, in each of the samples of the present invention with a groove depth of 300 layers, when the thickness of the dye layer in the groove portion and the land portion was set to 1400 layers and 900 layers, respectively, a sufficient tracking signal could not be obtained. .

Furthermore, in each of the above inventive samples,
The reflective layer is made of AnMg alloy, Al2Ni alloy, Ag, Pt.
When the same recording and reproduction as above was carried out using either of the above-mentioned samples and Cu, results equivalent to those of the above-mentioned samples of the present invention were obtained.

Furthermore, for each sample with different reflective layer constituent materials,
When we conducted an experiment in which adhesive tape was pasted on the protective film and then peeled off, peeling occurred between the recording layer and the reflective layer in the sample with the Au reflective layer, but with the AlMg alloy reflective layer or the AβNi alloy reflective layer. No peeling was observed in the samples with

From these results, the effects of the present invention are clear.

<Effects of the Invention> In the optical recording medium of the present invention, the dye layer has a high light absorption rate and a high reflectance since the n and thickness of the dye layer are set within a predetermined range.

Since a mixed region of the substrate and the dye and a low refractive index region are formed by the recording light irradiation, the reflectance exhibits a large decrease in the recording light irradiated region. Therefore, good optical recording that can be reproduced according to the CD standard is possible.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing the optical recording medium of the present invention. Explanation of symbols 1... Optical recording medium 2... Substrate 3... Dye layer 4... Reflective layer 5... Protective film 7... Mixing part 8... Low refractive index part 81...・Cavity part 85...part containing pigment decomposition products Patent attorney, Td-K Co., Ltd., Akira Ishii

Claims (8)

[Claims] (1) In an optical recording medium having a dye layer on a resin substrate, and a reflective layer and a protective film laminated on the dye layer, the refractive index n of the dye layer at a wavelength of 700 to 850 nm
is 1.8 to 3.2 and extinction coefficient k is 0.04 to 0.12
and the thickness of the recording light irradiated part of the dye layer is 1000~
1500 Å, a mixed area of the substrate and the dye decomposition product is generated by irradiation with the recording light, and a low refractive index area containing the dye decomposition product is generated on this mixed area, and when the reproduction light is irradiated from the substrate side, the unused part is formed. An optical recording medium characterized in that the recorded portion has a reflectance of 60% or more, and the recorded portion has a reflectance of 40% or less of the unrecorded portion. (2) In an optical recording medium having a dye layer on a resin substrate, and a reflective layer and a protective film laminated on this dye layer, the refractive index n of the dye layer at a wavelength of 700 to 850 nm.
is 1.8 to 3.2 and extinction coefficient k is 0.04 to 0.12
and the thickness of the recording light irradiated part of the dye layer is 1000~
The recording light irradiation creates a mixed area between the substrate and the dye decomposition product, and a hollow low refractive index area is created above this mixed area, and when the reproduction light is irradiated from the substrate side, the unrecorded area is An optical recording medium characterized in that the reflectance of the recorded portion is 60% or more, and the reflectance of the recorded portion is 40% or less of the reflectance of the unrecorded portion. (3) In an optical recording medium having a dye layer on a resin substrate, and a reflective layer and a protective film laminated on this dye layer, the refractive index n of the dye layer at a wavelength of 700 to 850 nm.
is 1.8 to 3.2 and extinction coefficient k is 0.04 to 0.12
and the thickness of the recording light irradiated part of the dye layer is 1000~
The recording light irradiation produces a mixed area between the substrate and the dye decomposition product, and a low refractive index area is generated on this mixed area, and this low refractive index area is a part containing the cavity and the dye decomposition product. characterized in that when the reproduction light is irradiated from the substrate side, the reflectance of the unrecorded part is 60% or more, and the reflectance of the recorded part is 40% or less of the reflectance of the unrecorded part. optical recording medium. (4) The thickness of the mixing part is 0.1 to 0.0 times the thickness of the dye layer.
The optical recording medium according to any one of claims 1 to 3, which is 4 times as large. (5) The optical recording medium according to any one of claims 1 to 4, wherein the substrate has a groove, and the recording light is irradiated onto the dye layer within the groove. (6) The optical recording medium according to claim 5, wherein the sum of the thickness of the dye layer in the land portion and the depth of the groove is greater than the thickness of the dye layer in the groove portion. (7) The depth of the groove is 250 to 550 Å,
7. The optical recording medium according to claim 5, wherein the land width is 0.8 to 1.3 times the groove width. (8) The optical recording medium according to any one of claims 1 to 7, wherein the reflective layer is made of any one of Au, AlMg alloy, AlNi alloy, Ag, Pt, and Cu.