JPS63153192A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To increase reflectance and make it possible to realize a recording medium having a recording layer comprising an organic material, by providing a plurality of coloring matter films having different complex indices of refraction on a base to provide a recording layer. CONSTITUTION:In the case of recording and reproducing information through incicence 6 of laser light on the base side, the following can be held with reference to complex indices of refraction of coloring matter films. Let the n and k (n: refractive index; k: absorption coefficient) of a coloring matter film 2 be n1 and k1 and let the n and k of a coloring matter film 3 be n2 and k2, then the reflectance is increased when k2<k1 where n2>=n1. In the case of recording and reproducing information through incidence of laser light on the medium side, the following can be held. Let the n and k of a coloring matter film 4 be n3 and k3 and let the n and k of a coloring matter film 5 be n4 and k4, then the reflectance is increased when k3<k4 where n3>=n4. inIaddition, the reflectance is increased when (n4-n3)<=(0.4-k3) where n3<n4. Since the recording layer in this invention is not interposed with a metallic film such as Al, it can be utilized for both incidence on the base part and incidence on the medium part.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical information recording medium, particularly a heat mode optical information recording medium.

<Prior art> Optical recording media have the characteristic that the recording medium does not deteriorate due to wear and tear because there is no contact between the medium and the writing or reading head.For this reason, research and development of various optical recording media are being conducted. .

Among such optical recording media, heat mode optical recording media are being actively developed because they do not require development in a dark room. This heat mode optical recording medium is an optical recording medium that uses recording light as heat. For example, a part of the medium is melted or removed using recording light such as a laser, and a part of the medium is melted or removed to form a pit. There is a pit-forming type in which writing is performed by forming small holes, information is recorded using the pits, and reading is performed by detecting the pits with a readout light.

Most of these bit-forming type recording media, particularly those using a semiconductor radar as a light source which can make the device smaller, have a recording layer made of a material mainly composed of Te.

However, in recent years, Te-based materials are harmful and there is a need for higher sensitivity and lower manufacturing costs, so organic materials mainly containing dyes have been used instead of Te-based materials. Proposals and reports about recording media using recording layers are increasing.

For example, for He-Ne lasers, 7!
J Rium Color a C JP-A No. 56-46221, V.
BJipson and C, R, Jones, J.
Vac, Sci, Techno3,, 18(1) 1
05 (1981)) and metal phthalocyanine dyes (Japanese Unexamined Patent Publication Nos. 57-82094 and 57-82095).

In addition, for semiconductor lasers, there are those using metal phthalocyanine dyes (Japanese Patent Laid-Open No. 56-86795), cyanine dyes (Japanese Patent Laid-Open No. 59-24690), naphthoquinone dyes (Japanese Patent Laid-Open No. 59-48187), etc. be.

<Problems to be Solved by the Invention> However, the reflectance of the dye film to the laser is generally small, and the currently used normal method of obtaining a readout signal by changing (reducing) the amount of reflected light by pits has a large C. /N ratio cannot be obtained.

In order to improve the read C/N ratio of a recording layer made of a dye film, a metal film such as AI is usually interposed between the substrate and the recording layer.

In this case, the metal film is used to increase the reflectance and improve the C/N ratio, and the metal film is exposed by pit formation and increases the reflectance. Recording and playback from the side is not possible.

Therefore, in order to realize a recording medium that has a recording layer made of an organic material that allows recording and reproduction from the substrate side and is compatible with a recording medium that has a recording layer made of a Te-based material, it is necessary to use the organic material itself. must exhibit a large reflectance.

Means for Solving the Problems〉 The present inventors conducted intensive studies to improve the above-mentioned shortcomings, and as a result, we found that a complex refractive index (■=n-ik; n is a complex refractive index, n is a complex refractive index, The ac! It was discovered that the reflectance was increased by forming a green layer, and the present invention was completed.

The basic structure of the recording medium of the present invention is shown in FIGS. 1 and 2, for example.
Although shown in the figure, an undercoat layer, a protective layer, etc. may be provided in addition to the recording layer, if necessary. Furthermore, in order to protect the recording layer, a cover may be provided as usual, or two recording media having the same structure as shown in FIG. 1 may be arranged with the dye film 2 facing inside (so-called air sandwich structure). It is possible. Information is recorded by changing the shape of the dye film due to the thermal action of laser light, and information is reproduced by detecting the difference in reflected light from the shape-changing portion and the non-shape-changing portion.

Complex refractive index of the dye film of the present invention (■=n-ik; n: refractive index, n: extinction coefficient, where n and k are transmittance.

Physical property values specific to the dye for a specific wavelength that can be calculated from the values of reflectance and film thickness) are calculated when the recording medium has the configuration shown in Figure 1, that is, when information is recorded and reproduced by laser light incident from the substrate side. When carrying out this process, n and k of the pigment film 1 are
+kl+n and k of pigment film 2 are n2. If k2, then n
In the case of 2≧n1, the reflectance increases when the relationship 2<k holds. In addition, if n2<n, (n+-02)≦(
kl-kz), the reflectance increases. nl
In any case of the +02 relationship, the larger the value of n2 and the larger the value of (kl-2), the greater the effect of increasing reflectance.

When the configuration of the recording medium is as shown in Fig. 2, that is, when recording and reproducing information is performed by laser beam incidence from the medium side, n, k of the pigment film 3 is 03 + k3 + n, k of the pigment film 4 is '. If 4+k4, then the reflectance increases when there is a relationship of 3<k when n≧n. Also n
, if <n, then (nana) ≦(0,4-
kn), the reflectance increases. J+ '4
In any relationship, the larger the value of n and the larger the value of (kak=), the greater the effect of increasing reflectance.

As described above, since the recording layer according to the present invention does not include a metal film such as A1, it can be used for incidence on the substrate side and for incidence on the medium side, as shown in FIGS. 1 and 2.

The dyes used in the present invention have absorption maximum in the region of 350□ to 900°, and include naphthoquinone, anthraquinone, indoaniline, azo, indigo,
carbonium-based, quinoneimine-based, phthalocyanine-based,
Various types of dye compounds include naphthalocyanine compounds, cyanine compounds, benzenedithiol complexes, etc., but are not limited to these. Dyes with preferable n and k values are selected as appropriate depending on the wavelength of the laser used. Use in combination.

Among the above dyes, the dyes shown in Tables 1 to 6 can be cited as dyes for lasers with an oscillation wavelength of 750 to 8501 m.

Among these, the compounds shown in Tables 1 to 5 are suitable for the pigment film 11 and the pigment film 4.
Compounds such as those shown in No. 5 are suitable for the dye film 2 and the dye film 3, but the present invention is not limited thereto.

Table-! 3° 2' Table-2 Note) Metal (M); Table-3, including substituents on metals, 1 Compound: Substitution
Group I Table-4 Table-5 (P): Para Note) Ph: Phel group The following compounds are R,, R,, R,, R,, are a mixture of A and B, or other components as necessary. For example, binders, stabilizers, etc. may be included.

The dye film of the present invention can be formed into a thin film by a vacuum evaporation method or a wet coating method. The thickness of the pigment film is 50 to 5
000 people, preferably in the range of 100 to 1000 people.

The substrate material used in the present invention is transparent to the laser beam used, and includes glass, quartz, and various plastics.

Typical plastics include polycarbonate resin, vinyl chloride resin, and polymethylmethacrylic resin (P
MM^), polyester resin, polyethylene resin, polypropylene resin, polyamide resin, polystyrene resin,
Examples include polyamide resins, epoxy resins, and other homopolymers and copolymers.

Lasers that can be applied to the information recording medium of the present invention include semiconductor lasers, He-Ne lasers, Ar lasers, etc., but semiconductor lasers are particularly preferable because they are small, inexpensive, and can be changed at high speed. You need to choose a dye.

<Effects of the Invention> The recording medium of the present invention has a high reflectance at any wavelength depending on the dye used, and is therefore excellent in that a large signal intensity can be obtained.

The present invention will be specifically explained below using Examples and Comparative Examples, but the present invention is not limited thereto.

In the examples, spectra were measured using a LIV-365 spectrophotometer manufactured by Shimazu Corporation, film thickness was measured using a Christetsub film thickness meter manufactured by Tiller-Hobson, and disk evaluation was performed using a 0MS-1000 manufactured by Nakamichi Corporation. was used.

<Example> Example 1 5-amino-8-(4'-ethoxyphenylamino)-2,3-dicyano-1,4-naphthoquinone was deposited on a PMMA substrate to obtain a film of 450 people ( Pigment film 1).

The degree of vacuum during vapor deposition was 2×10-’T.

rr or less. The substrate was not heated, and almost no increase in substrate temperature due to vapor deposition was observed. The resistance heating boat temperature was 225-230 °C, and the deposition rate was approximately 0.5
It was deposited as a person/sec. 1.4 on top of the obtained membrane
．． A dye film was formed by depositing a 500-layer film of 5.8-tetra(3'-methylphenylamino)anthraquinone (pigment film 2). The degree of vacuum is less than 2 × 10-'Torr,
The boat temperature was 260-270°C. The transmission and reflection spectra (incidence on the substrate side) of the obtained recording medium are shown in FIG.

The complex refractive index of the dye used at this time at 830nln is T1. =2.1,
kl = 0.6, nz = 2.2, k2 = 0.4, (ni - n,) = 0.1, (kl - to 2
) =0.2.

A signal of 1 MHz was recorded on this recording medium using a semiconductor radar with a wavelength of 830 nm at a linear velocity of 2.8 buttons/sec. When this was reproduced, a CNR of 60 dB was obtained.

Example 2 5-amino-8-(4'-ethquinphenylamino)-2,3-dicyano-1,4-naphthoquinone was deposited on a PMMA substrate, and a film of 450 people was deposited on one fathom (pigment film). 1)
. The degree of vacuum during vapor deposition was 2×IO-'T.

rr or less. The substrate was not heated, and almost no increase in substrate temperature due to vapor deposition was observed. The resistance heating boat temperature was 225-230 °C, and the deposition rate was approximately 0.5
It was deposited as a person/sec. 1.4 on top of the obtained membrane
．． A dye film was formed by vapor depositing a 600-layer film of 5,8-tetra(3',5'-dimethquinphenylamino)anthraquinone (pigment film 2). The degree of vacuum is 2 x l 0
-5 Torr or less, and the boat temperature was 290 to 300°C. The transmission and reflection spectra (incidence on the substrate side) of the obtained recording medium are shown in FIG.

The complex refractive index of the dye used at this time at 830 nm is n, k of dye film 1 nIn kIt dye film 2
When n and k are n2+k2, 711=2.1
, kl =0.6, nz=2.2, k2 =
0.4, (n2-n+) =0.1, (k
, -2) = 0.2.

This recording medium uses a semiconductor laser with a wavelength of 830 nm, a linear velocity of 2.33 m/sec, and l! JHz signal was recorded. When this was reproduced, a CNR of 52 dB was obtained.

Example 3 5-amino-8-(4'-ethoxyphenylamino)-2,3-dicyano-1,4-naphthoquinone was deposited on a PMMA substrate to obtain a 450-layer film (dye film 1). .

The degree of vacuum during vapor deposition was 2×10-’T.

rr or less. The substrate was not heated, and almost no increase in substrate temperature due to vapor deposition was observed. The resistance heating boat temperature was 225-230 °C, and the deposition rate was approximately 0.5
It was deposited as a person/sec. 1.4 on the obtained membrane
, 60 of 5.8-tetraphenylaminoanthraquinone
A color S film was formed by vapor depositing a 0.0-color film (pigment film 2).

The degree of vacuum was 2 x 10-'Torr or less, and the boat temperature was 260-270°C. The transmission and reflection spectra (incidence on the substrate side) of the obtained recording medium are shown in FIG.

Furthermore, a semiconductor laser with an oscillation wavelength of 830 nm was used for the recording medium, and the spot diameter was set to 1 μm, and the spot diameter was 4QmJ/cm'.
When irradiated with , a clear pit pattern was observed.

The complex refractive index of the dye used at this time at 830 nm is n1=2.1, where n and k of dye film 1 are 'l+kl+ and n and k of dye film 2 are n2+k2.
kl=0.6, n2=2. :l,k2=0
．． 2, (n, -n,) -0,2, (k
l-2) = 0.4.

Example 4 An indoaniline compound represented by the following structural formula was wet-coated on a glass substrate, and 40
A membrane of 0 people was obtained (pigment membrane 1). Trichlorethylene was used as the solvent for wet coating. A 500-layer film of 1,4,5,8-tetra(3'-ethylphenylamino)anthraquinone was vapor-deposited on top of the prepared film to form a dye film (pigment film 2). Vacuum degree is 2 x 10-'T
The boat temperature was 255-265°C. The transmission and reflection spectra (incidence on the substrate side) of the obtained recording medium are shown in FIG.

The complex refractive index at 830 nm of the dye used at this time is: n, k of dye film 1 is nIn kl+ n of dye film 2
,k is n,,k2,n,=2.3,k
, =0.6, n2=2.3, k2 =0.3
and (n2 - n,) = 0゜(kl-km)
=0.3.

Example 5 5-Ami7-8- (4'
-ethoxyphenylamino)-2,3-dineano-1
, 4-naphthoquinone was deposited to obtain a 500-layer film (dye film 1). The degree of vacuum during vapor deposition was 2 x 10-5T.

rr or less. The substrate was not heated, and almost no increase in substrate temperature due to vapor deposition was observed. The resistance heating board temperature was 225-230 °C, and the deposition rate was approximately 0.5 °C.
Deposited as 1/sec. On the obtained film, a 100-layer film of 1,4,5,8-tetra(3"-methoxyphenylamino)anthraquinone was deposited to form a dye film. Dye film 2).The degree of vacuum was 2X. 10-'To
Below rr, the boat temperature was 240-250°C. The transmission and reflection spectra (incidence on the substrate side) of the obtained recording medium are shown in FIG.

The complex refractive index of the dye used at this time at 830 nm is n1=2°1, where n and k of dye film 1 are 'l+ Kl+ and n and k of dye film 2 are 02+ K2+.
, KI=0.6, n2=2.3, k,=Q,3, and (112-nl)=0.2, (k,-2)
=0.3.

For each recording medium, a semiconductor laser with an oscillation wavelength of 830 nm was used to record a signal at a linear velocity of 5.55 m/sec and IMHz.

When this was regenerated, a CNR of 57 clB was obtained.

Example 6 5-amino-8-(4°-ethoxyphenylamino)-2,3-dicyano-1,4-naphthoquinone was deposited on a PMMA substrate to obtain a 500-layer film (dye film 1). . The degree of vacuum during vapor deposition was 2 x 10-'T.

rr or less. The substrate was not heated, and almost no increase in substrate temperature due to vapor deposition was observed. The resistance heating board temperature was 225-230 °C, and the deposition rate was about 0.5
Deposited as 1/sec. 1 on the obtained film
．． 4,5.8-tetra(3″-ethylphenylamino)
A dye film was formed by depositing a 100-layer film of anthraquinone (pigment film 2). The degree of vacuum was 2×10-'Torr or less, and the boat temperature was 235-245°C. The transmission and reflection spectra of the obtained recording medium (incidence on the substrate side are shown in No. 8r!gJ).

The complex refractive index at 830 nm of the dye used at this time is nl+ Kl+ n of dye film 2.
, k to '2+' to 2. Then, n1=2.1, Kl
=0.6, n2=2.2, k2=0.2,
(n2-nl) = 0.1, (kl-2) =
It was 0.4.

This recording medium uses a semiconductor laser with an oscillation wavelength of 830 nm at a linear velocity of 5.65 m/sec, l! , 4Hz signals were recorded.

When this was reproduced, a C'NR of 55 dB was obtained.

Example 7 5-amino-8-(4'-ethoxyphenylamino)-2,3-dicyano-1,4-naphthoquinone was deposited on a PMMA substrate to obtain a 500-layer film (dye film 1). .

The degree of vacuum during vapor deposition was 2×10-’T.

rr or less. The substrate was not heated, and almost no increase in substrate temperature due to vapor deposition was observed. The resistance heating board temperature is 250-255 °C, and the deposition rate is about 0.5
Deposited as 1/sec. 1 on the obtained membrane
．． 4.5.8-tetra(3°-ethylphenylamino)
2) We want to form a colored sM by depositing a 200-layer film of anthraquinone. Vacuum degree is 2X I O-'Torr
Hereinafter, the boat temperature was set at 235 to 245°C. Transmission and reflection spectra of the obtained recording medium (incidence on the substrate side)
is shown in Figure 9.

The complex refractive index at 830 nm of the dye used at this time is as follows: n, k of dye film 1 is nl+ L+ n of dye film 2,
k to n2+ K2. When, n, =2.3, K
l = 0.8, n2 = 2.2, k2 = 0.2, (fly-Ill) = 0.1, (kl- to 2
) =0.6.

This recording medium uses a semiconductor laser with an oscillation wavelength of 830 nm at a linear velocity of 5.65 m/sec, l! A signal of JHz was recorded.

When this was played back, a CNR of 57 dB was observed.

Comparative Example The same procedure as in Example 1.2 or 3 was carried out except that the dye was used as a single layer. FIG. 10 shows the transmission and reflection spectra (incidence on the substrate side) of a 700A single-layer thin film of 5-amino-8-(4'-ethoxyphenylamino)-2,3-dicyano-1,4-naphthoquinone.

In addition, FIG. 11 shows the transmission and reflection spectra (incidence on the substrate side) of a single-layer thin film of 750 people of 1,4,5,8-tetra(3'-methylphenylamino)anthraquinone.

As is clear from the above, it was not possible to obtain a high reflectance as in Examples 1 and 2.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing the basic structure of an optical information recording medium according to the present invention. 1 Substrate, 2 Dye film 1.3 Dye film 2, 4 Dye film 3.
5 Dye film 4.6 Laser beam Figure 3 shows the transmission spectrum and reflection spectrum (
(incidence on the substrate side). FIG. 4 shows the transmission spectrum and reflection spectrum (incidence on the substrate side) of the recording medium obtained in Example 2. FIG. 5 shows the transmission spectrum and reflection spectrum (incidence on the substrate side) of the recording medium obtained in Example 3. FIG. 6 shows the transmission spectrum and reflection spectrum (incidence on the substrate side) of the recording medium obtained in Example 4. FIG. 7 shows the transmission spectrum and reflection spectrum (incidence on the substrate side) of the recording medium prepared in Example 5. FIG. 8 shows the transmission spectrum and reflection spectrum (incidence on the substrate side) of the recording medium prepared in Example 6. FIG. 9 shows the transmission spectrum and reflection spectrum (incidence on the substrate side) of the recording medium prepared in Example 7. 10 and 11 show comparative examples, and the transmission spectra and reflection spectra of the two types of dye monolayers used in Example 1 (
(incidence on the substrate side). Figure 1. 2 (%) Figure 3.00 (n wavelength (%)) Figure 4.00 (n wavelength (%)) Figure 5.9 (''ゝ(%)) Figure 6.00 (n wavelength (%) ) Fig. 7 00 (n Wavelength (%) Fig. 8 500 600 700 800' 900
101000 (n Wavelength (%) Figure 9 (0m) (%) Figure 10 00 (n Fun and

Claims (5)

[Claims] (1) A recording layer is formed by laminating a plurality of dye films with different complex refractive indexes (■=n-ik; ■ is the complex refractive index, n is the refractive index, and k is the extinction coefficient) on the substrate. optical information recording medium. (2) Dye film 1 (n_1, k_1) and dye film 2 on the substrate
The optical information recording medium according to claim 1, characterized in that two layers (n_2, k_2) are successively laminated to form a recording layer, and information is recorded and reproduced by laser beam incidence from the substrate side. . (3) The optical information recording medium according to claim 2, wherein n and k have the following relationship. If n_2≧n_1; k_2<k_1 If n_2<n_1; (n_1-n_2)≦(k_1
-k_2) (4) Dye film 3 (n_3, k_3), dye film 4 on the substrate
The optical information recording medium according to claim 1, wherein two layers (n_4, k_4) are laminated to form a recording layer, and information is recorded and reproduced by laser beam incidence from the medium side. (5) The optical information recording medium according to claim 4, wherein n and k have the following relationship. If n_3≧n_4; k_3<k_4 If n_3<n_4; (n_4-n_3)≦(0.4
-k_3)