JPH0796337B2 - Optical information recording medium - Google Patents

Description

The present invention relates to a writable optical information recording medium having at least a light absorbing layer and a reflecting layer on a transparent substrate.

[Prior Art] An optical information recording medium capable of recording data by irradiation with a laser beam includes a metal layer such as Te, Bi, and Mn and a recording layer including a dye layer such as cyanine, merocyanine, and phthalocyanine. The pits are formed and the data is recorded by means of deforming, sublimating, evaporating or modifying the recording layer by irradiating with a laser beam. In an optical information recording medium having such a recording layer, a void is generally provided behind the recording layer in order to facilitate deformation, sublimation, evaporation or modification of the recording layer when forming pits. ing. Specifically, for example, a so-called air sandwich structure, in which two substrates are stacked with a space therebetween, is used.

In this optical information recording medium, pits are formed by irradiating laser light from the side of the substrate 1 having the above-mentioned translucency. And
When the recorded data is reproduced, the substrate 1 side is irradiated with a laser beam having a power lower than that at the time of recording, and a signal is read due to the difference in the reflected light between the pit and other portions.

On the other hand, a so-called ROM type optical information recording medium in which data is recorded in advance and the data cannot be written or erased thereafter has already been widely put to practical use in the information processing and audio departments. This kind of optical information recording medium does not have the recording layer as described above,
Pits for reproducing recorded data are formed beforehand on a polycarbonate substrate by means of a press etc.
A reflective layer made of a metal film of Au, Ag, Cu, Al or the like is formed and further covered with a protective layer.

The most typical of these ROM type optical information recording media is a compact disc, which is widely used in the audio sector and the information processing sector, so-called CD, and the specifications of the recording and reproducing signals of this CD are the so-called CD standard. A playback device standardized as, and made according to this standard is extremely widespread as a compact disc player (CD player).

[Problems to be Solved by the Invention] Since the above optical information recording medium is also a recording / reproducing means that uses the same laser light as that of a CD, it is strongly desired that the optical information recording medium can be reproduced in the same manner as a CD which has already been widely spread. .

However, the above-mentioned optical information recording medium has a recording layer not present in CD, and by irradiating this recording layer with laser light that has passed through the substrate, not on the substrate, it is evaporated and sublimated to form pits. It is formed and recorded. Then, in order to facilitate the formation of pits in this recording layer, it is necessary to provide the above-mentioned voids or the like behind the recording layer, and therefore it is not possible to form a reflective layer or the like made of a metal film there. . As a result, the layer structure of the optical information recording medium is essentially different from that of the CD, and the obtained reproduction signal and the reflectance of the laser light are different from those of the CD. Therefore, it is difficult to satisfy the above-mentioned CD standard, which defines the standard for so-called CD. In particular, since the degree of modulation of the reproduced signal is low, a reproduced signal that satisfies the CD standard cannot be obtained and the reflectance is low.

The present invention has been made to solve the above conventional problems, and an object of the present invention is to provide a writable optical information recording medium that can obtain a reproduction signal satisfying the CD standard.

[Means for Solving the Problems] That is, in order to achieve the above-mentioned object, the means adopted in the present invention is that a light absorbing layer is formed directly or through another layer on a transparent substrate. In the optical information recording medium, the light-absorbing layer contains a material that absorbs laser light and rises in temperature and causes an exothermic reaction with gas generation at 100 ° C. or higher and 600 ° C. or lower. In the optical information recording medium, the surface is deformed by the same exothermic reaction, and a light reflecting layer made of a metal film is formed on the light absorbing layer directly or through another layer. is there.

[Operation] In this optical information recording medium, when the light absorbing layer is irradiated with laser light, the light absorbing layer absorbs the laser light and generates heat.
Melting, evaporation, sublimation, reaction, decomposition or modification causes local energy conversion such as heat or pressure. Therefore, the above heat and pressure are applied to the surface of the translucent substrate and the layer formed thereon, and the surface is locally deformed, or at the same time, melting, evaporation, sublimation, reaction, decomposition or Incorporates the components of the knitted light absorbing layer to form optically modified pits.

In particular, in the present invention, since the light absorption layer contains a material that absorbs laser light and increases in temperature, and causes an exothermic reaction with gas generation at 100 ° C. or higher and 600 ° C. or lower, at a relatively low temperature. As the energy is converted, heat generated by heat generation and pressure increase due to gas generation are generated, and even if there is no void or the like behind to assist deformation, the surface of the translucent substrate is good as described later. It is possible to form pits that can obtain various reproduction signals.

The pits thus formed on the surface of the transparent substrate are similar to the pits previously formed on the surface of the transparent substrate of the CD by using a stamper. In addition, since a light reflecting layer made of a metal layer is provided behind the light absorbing layer, an optical information recording medium having a layer structure similar to that of a CD can be obtained, and a recordable optical information recording satisfying the CD standard can be obtained. The medium is easily obtained.

The reason why the critical temperature at which the component contained in the light absorption layer 2 causes an exothermic reaction accompanied by gas generation is limited to the range of 100 ° C to 600 ° C is as follows. That is, when the temperature is lower than 100 ° C., there is a concern that the environment may change such as direct sunlight, and when the temperature is higher than 600 ° C., the energy required to reach that temperature becomes large, and the sensitivity decreases. In addition, about 150 to 300 ° C. is more preferable because it is stable and has high sensitivity.

[Examples] Next, examples of the present invention will be described in detail with reference to the drawings.

Examples of the schematic structure of the optical information recording medium according to the present invention are shown in FIGS. In the figure, reference numeral 1 is a translucent substrate, and reference numeral 2 is a light absorption layer formed thereon, which absorbs the irradiated laser light to generate heat, thereby melting, evaporating, sublimating, deforming or It is a layer that has been modified and has an action of forming a pit on the adjacent layer, for example, the surface of the transparent substrate 1.

As described above, in the present invention, it is necessary that the light absorption layer 2 contains a material that absorbs a laser beam and raises the temperature to cause an exothermic reaction with a weight reduction at 100 ° C. or higher and 600 ° C. or lower. Is.

Reference numeral 3 is a light reflecting layer formed thereon, which reflects the laser light, and is made of a metal film of Au, Ag, Al, Cu or the like. Reference numeral 4 indicates a protective layer provided so as to cover the light reflection layer 3. Note that FIG. 2 shows the state before recording with laser light, and FIG. 3 shows the state after recording, that is, due to the local change of the light absorption layer 2 at the time of laser light irradiation, the transparent substrate 1 The surface of is partially deformed, and the state in which the optically knitted pits 5 are formed is schematically shown.

A specific example of this optical information recording medium will be described below.

(Example 1) A width of 0.8 μm, a depth of 0.08 μm, a spiral pregroove having a pitch of 1.6 μm, a thickness of 1.2 mm and an outer diameter of 120 mm.
A polycarbonate substrate 1 having φ and an inner diameter of 15 mmφ was molded by an injection molding method.

About 20 nm of silicon-based coating agent on the surface of the transparent substrate 1
After being spin-coated to a thickness of 1 and subjected to a solvent-resistant treatment, 8.5 g of a soluble phthalocyanine represented by the following chemical formula was dissolved in 10 cc of dimethylformamide solvent as an organic dye for forming the light absorbing layer 2, The substrate 1 was coated by a spin coating method to form a light absorption layer 2 made of a dye film having a thickness of 160 nm. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 measured with a TG8110 calorimetric analyzer (DTA) manufactured by Rigaku Denki Co., Ltd. in a nitrogen gas with a temperature gradient of 20 ° C./min was 400 ° C. .

_{R: -C (CH 3) 3} , M: Co Further, by sputtering on the entire surface of the disc, to form a film and Au film with a thickness of 50 nm, to form a reflective layer 3. further,
An ultraviolet curable resin was spin-coated on the reflective layer 3 and irradiated with ultraviolet rays to be cured to form a protective layer 4 having a thickness of 10 μm.

The optical disc thus obtained was irradiated with a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.2 m / sec and a recording power of 6.0 mW, and EFM was applied.
The signal was recorded. Then, use this optical disc as a commercially available CD
When reproduced with a player (Aurex XR-V73, reproduction light wavelength λ = 780 nm), the reflectance of the optical disk was 73%, the I ₁₁ / I _top required from the eye pattern was 0.63, and the I ₃ / I _top was 0.35. It was

According to the CD standard, the reflectance is 70% or more, I ₁₁ / I _top is 0.6 or more, I
_{The 3} / I _top is determined to be 0.3 to 0.7, and the optical disc according to this example satisfies this standard.

(Embodiment 2) In the above-mentioned Embodiment 1, as the transparent substrate 1, 2p is formed on the surface.
An epoxy resin disk with pregrooves formed by the photo poly-marization method is used, and Cr-bis 1 (2 hydroxyphenyl) azo 2 hydroxynaphthalate is directly coated on the disk without coating the silicon-based coating agent. (Orient Black Co., Ltd., Oil Black HBB) 5.0 g was dissolved in dichloroethane solvent 10 cc and spin-coated to form a light absorption layer 2 having a thickness of 150 nm. The light reflection layer 3 was directly composed of Au and Ir. An optical disk was manufactured in the same manner as in Example 1 except that a light reflecting layer made of a 9: 1 alloy thin film was provided. The peak value of the thermal decomposition temperature of the material forming the light absorption layer 2 is 260 ° C.

An EFM signal was recorded on the thus-obtained optical disc in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 80%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ / I
_top was 0.33.

(Example 3) In Example 1, the SiN layer having a thickness of 30 nm was formed on the transparent substrate 1 in place of the silicon-based coating agent by the reactive sputtering method using nitrogen gas.
6.5 g of 3,3 '-(2-acetoxyethyl) 10-diphenylamino 9,11 ethylenethiadicarbocyanine perchlorate was dissolved in 10 cc of acetylacetone solvent and spin-coated to form a light absorption layer having a thickness of 130 nm. An optical disc was manufactured in the same manner as in Example 1 except the above.
The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is
It is 240 ℃.

An EFM signal was recorded on the thus-obtained optical disc in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 78%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.61, I ₃ / I
_top was 0.32.

(Example 4) In Example 1, the polystyrene resin layer having a thickness of 60 nm was formed on the translucent substrate 1 in place of the silicon-based coating agent by a spin coating method, and further by a sputtering method. A 30 nm thick SiO ₂ layer was formed on top of this, and 7.0 g of 3,3′-di (3-acetoxypropyl) 5,6,5 ′, 6′-tetramethoxythiadicarbocyaninetoluenesulfonate was formed on it. , Dissolved in 10 cc of hydroxyacetone solvent and spin-coated to form a light absorption layer 2 having a thickness of 140 nm, provided a light reflection layer 3 directly on the light absorption layer 2 by a vacuum deposition method, and a protective layer An optical disk was manufactured in the same manner as in Example 1 except that the thickness of bisphenol-curable epoxy resin was 4 μm. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is 285 ° C.

An EFM signal was recorded on the optical disc thus obtained in the same manner as in Example 1 above, and when this optical disc was reproduced with a commercially available CD player, the reflectance was 70%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ / I
_top was 0.33.

(Example 5) In the above Example 1, a polyvinyl acetate layer having a thickness of 60 nm was formed on the translucent substrate 1 by a spin coating method instead of the silicon-based coating agent, and 6.7 g of the polyvinyl acetate layer was formed thereon. 1,
1'dibutyl 3,3,3 ', 3' tetramethyl 5,5 '
Diethoxy indodicarbocyanine perchlorate was dissolved in 10 cc of diacetone alcohol solvent and spin-coated to form a light absorbing layer having a thickness of 135 nm, and a light reflecting layer composed of an Au film was formed thereon by a vacuum deposition method. An optical disk was manufactured in the same manner as in Example 1 except that the above was provided. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is 267 ° C.

An EFM signal was recorded on the thus-obtained optical disc in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 78%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.64, I ₃ / I
_top was 0.36.

Example 6 In Example 1, a glass substrate was used as the translucent substrate 1, and 4.5 g of the organic dye represented by the following chemical formula was directly coated on the substrate 1 without coating a silicon coating agent. Was dissolved in 10 cc of tetrahydrofuran solvent and spin-coated to form a light-absorbing layer 2 having a thickness of 180 nm, and polybutadiene was spin-coated on the light-absorbing layer 2 to have a thickness of 10 nm, and then vacuum-coated thereon. An optical disk was manufactured in the same manner as in Example 1 except that the light reflecting layer 3 made of an Au film was provided by the vapor deposition method. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is 200 to 540 ° C.

An EFM signal was recorded on the thus-obtained optical disc in the same manner as in Example 1 above, and when this optical disc was reproduced with a commercially available CD player, the reflectance was 75%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ / I
_top was 0.32.

(Example 7) In Example 1, the translucent substrate 1 was directly coated with 8.0 g of an organic dye represented by the following chemical formula in 10 cc of a butanol solvent and spin-coated without coating a silicon coating agent. The light absorption layer 2 having a thickness of 65 nm was formed, the SiO ₂ layer having a thickness of 160 nm was interposed between the light absorption layer 2 and the light reflection layer 3, and the light reflection made of an Au film was formed by a vacuum deposition method. An optical disk was manufactured in the same manner as in Example 1 except that the layer 3 was provided, and the light reflecting layer 3 was coated with polybutadiene having a thickness of 20 nm and the protective layer 4 was provided.
The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is
It is 300-400 ℃.

An EFM signal was recorded on the optical disc thus obtained in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 77%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ /
_top was 0.32.

_{R: -C (CH 3) 3} , M: the TiCl ₂ (Example 8) Example 1, on the transparent substrate 1 that, in place of the silicon-based coating agent was coated SiN, light absorption Coating layer 2 with a silicone resin,
Except that the light reflection layer 3 is formed by a vacuum deposition method, that the light reflection layer 3 is coated with a 20 nm thick bisphenol-curable epoxy resin, and the protective layer 4 is provided thereon.
An optical disk was manufactured in the same manner as in Example 1 above. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 in this optical disk is the same as that in the above-described first embodiment.

An EFM signal was recorded on the thus-obtained optical disc in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 76%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ / I
_top was 0.32.

(Embodiment 9) In the above-mentioned Embodiment 1, as the transparent substrate 1, 2p is formed on the surface.
Using an epoxy resin disk with pregrooves formed by the photo poly-marization method, Cr-bis 1 (2 hydroxyphenyl) azo 2-hydroxynaphthalate (Orient Chem. (Manufactured by Oil Black HBB) 5.0 g of dichloroethane solvent 1
Light absorption layer 2 with a thickness of 150 nm
An optical disk was manufactured in the same manner as in Example 1 except that the light reflecting layer made of Ag film was directly provided as the light reflecting layer 3 by the vacuum evaporation method. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is 260 ° C.

An EFM signal was recorded on the thus-obtained optical disc in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 80% and the I pattern obtained from the reproduced signal eye pattern I ₁₁ / I _top is 0.64, I ₃ / I
_top was 0.33.

(Example 10) In the above-described Example 1, a silicon resin was spin-coated on the translucent substrate 1 in place of the silicon-based coating agent to have a film thickness of 20 nm. ′-(2-
Acetoxyethyl) 10-diphenylamino 9,11 ethylenethiadicarbocyanine perchlorate was dissolved in 10 cc of acetylacetone solvent and spin-coated to form a light-absorbing layer 2 having a thickness of 130 nm. Directly
An optical disk was manufactured in the same manner as in Example 1 except that the light reflecting layer 3 made of a 9: 1 alloy film of Au and Ir was provided. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is 240 ° C.

An EFM signal was recorded on the thus-obtained optical disc in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 78%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ / I
_top was 0.31.

(Example 11) In the above-mentioned Example 1, 7.0 g of 3,3'-di (3-acetoxypropyl) 5 was directly coated on the transparent substrate 1 without coating the silicon-based coating agent. 6,
5 ', 6'-Tetramethoxythiadicarbocyanine toluene sulfonate was dissolved in 10 cc of hydroxyacetone solvent and spin-coated to form a light absorption layer 2 having a thickness of 140 nm, and polysulfide was added on the light reflection layer 3. An optical disk was manufactured in the same manner as in Example 1 except that the epoxy resin was applied to a thickness of 20 nm and the protective layer 4 was formed thereon. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is 285 ° C.

An EFM signal was recorded on the optical disc thus obtained in the same manner as in Example 1 above, and when this optical disc was reproduced with a commercially available CD player, the reflectance was 70%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.63, I ₃ / I
_top was 0.32.

(Example 12) In Example 1, the transparent substrate 1 was not coated with the silicon-based coating agent, but 6.7 g of 1, 1'dibutyl 3 was directly coated on the transparent substrate 1. 3, 3 ', 3'
Tetramethyl 5,5'diethoxyindodicarbocyanine perchlorate was dissolved in 10 cc of diacetone alcohol solvent and spin-coated to form a light absorption layer having a thickness of 135 nm, and a ZnS film having a thickness of 60 nm. Was formed by a vacuum vapor deposition method, and the light reflection layer 3 was provided thereon,
An optical disk was manufactured in the same manner as in Example 1 above. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is
It was 267 ° C.

An EFM signal was recorded on the optical disc thus obtained in the same manner as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 82%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ / I
_top was 0.33.

Example 13 In Example 1, a glass substrate was used as the translucent substrate 1, and 4.5 g of the organic dye represented by the following chemical formula was directly coated on the substrate 1 without coating a silicon coating agent. Was dissolved in 10 cc of tetrahydrofuran solvent and spin-coated to form a 180 nm-thick light absorption layer 2, and a 60 nm-thick SiO ₂ film was formed thereon by a sputtering method, and a light reflection layer was formed thereon. An optical disc was manufactured in the same manner as in Example 1 except that the optical disc No. 3 was provided. The peak value of the thermal decomposition temperature of the material of the light absorption layer 2 is 200 to 540.
℃.

An EFM signal was recorded on the thus-obtained optical disc at the same time as in Example 1 above, and when this optical disc was reproduced by a commercially available CD player, the reflectance was 78%, which was obtained from the eye pattern of the reproduced signal. I ₁₁ / I _top is 0.62, I ₃ / I
_top was 0.32.

[Effects of the Invention] As described above, according to the present invention, a reproduction signal that has a high reflectance of 70% or more and that satisfies the CD standard when data is reproduced by recording in the light absorption layer is obtained. The resulting writable optical information recording medium is obtained.

[Brief description of drawings]

FIG. 1 is a schematic half cross-sectional perspective view showing an example of the structure of an optical information recording medium, FIG. 2 is an enlarged view of part A of FIG. 1, and FIG.
It is sectional drawing which shows an example of the state after recording of said A part. 1 ... Substrate, 2 ... Light absorbing layer, 3 ... Reflective layer, 4 ... Protective layer

Front Page Continuation (72) Inventor Ariake 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. (72) Inventor Takashi Ishiguro 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denshi Co., Ltd. In-house (56) References JP 63-121142 (JP, A) JP 62-288087 (JP, A)

Claims (1)

[Claims] 1. An optical information recording medium in which a light absorbing layer is formed on a transparent substrate directly or through another layer, and the light absorbing layer absorbs a laser beam to raise the temperature, It contains a material that causes an exothermic reaction with gas generation at 100 ° C or more and 600 ° C or less, and the surface of the translucent substrate is deformed by the exothermic reaction, which is directly on the light absorbing layer. Alternatively, the optical information recording medium is characterized in that a light reflecting layer made of a metal film is formed via another layer.