JPH06333267A - Optical recording medium and its production - Google Patents

Abstract

PURPOSE:To produce an optical recording medium with a track groove formed in the reflecting layer of an org. coloring material without using a stamper. CONSTITUTION:A light reflecting layer 2 made of a thin film of an org. coloring material, a transparent intermediate layer 3 and a light absorbing layer 4 made of a thin film of an org. coloring material are successively laminated on a smooth transparent substrate 1 and a protective substrate 6 is fitted on the light absorbing layer 4 with an adhesive 5. A track groove 10 for tracking is formed in the light reflecting layer 2 by decoloring or decoloring and partial scattering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium for recording / reproducing information by light, particularly laser light, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, many optical recording media such as optical disks, optical cards, and optical tapes for optically recording and reproducing information have been proposed as means for efficiently handling a wide variety of information as the informationization of society progresses. Has been done. In addition, some optical recording media are known that can detect binarized information by converting the binarized information into intensity changes in reflectance due to changes in the shape or state of the recording layer or the reflective layer.

As such an optical recording medium, a phase change type medium which causes a phase change of the recording layer by irradiation of a laser beam, a pit (geometrical shape) in a recording layer containing an organic dye or a low melting point metal as a main component is used. Change type), a three-layer structure type including a reflection layer of an organic dye, a transparent intermediate layer, and a light absorption layer of an organic dye, and forming pits in both the light reflection layer and the light absorption layer. There is.

In such an optical recording medium, for example, there is a method of forming grooves (track grooves) on the surface of the transparent substrate in advance at a predetermined interval for recording / reproducing track servo. In this method, the groove serves as a guide for reproduction, so that the track control accuracy is improved and the access speed is higher than that of the conventional one using the grooveless substrate.

As a method of forming the guide groove on the substrate, there is known a method of thermally transferring the stamper mold by performing injection molding or hot pressing at a temperature above the melting point when the substrate is a thermoplastic resin. There is also known a method in which a photocurable resin composition is applied onto a substrate, a stamper mold is brought into close contact with the substrate, and the composition is cured by irradiation with ultraviolet rays or the like to optically transfer the stamper mold.

FIG. 7 is a schematic sectional view of a conventional card-shaped optical recording medium. 1 is a transparent substrate, 10 is a track groove, and 9 is a track groove.
Is a recording layer, 5 is an adhesive, and 6 is a protective substrate. In this optical recording medium, recording / reproducing of information is performed by optically writing and reading through the transparent substrate 1 and the track groove 10.

In the case of the above-mentioned thermal transfer method, the track groove 10
Is integrated with the transparent substrate 1 and made of the same material, whereas in the case of the optical transfer method, the track groove 10 is not made of the same material as the transparent substrate 1 but in a bonded state. In any case, a track groove corresponding to a light guide groove is formed in advance on the transparent substrate 1 so that tracking can be performed by a track signal due to a phase difference of a laser beam by utilizing fine irregularities.

However, since such an optical recording medium has a structure in which the optical recording layer is formed on a substrate having an uneven shape, the uneven shape must first be formed on the substrate in the production thereof. In the conventional method, the yield and transfer time of the stamper type transfer, the durability and cost of the stamper type greatly affect the mass productivity and cost of the optical recording medium.

[0009]

The object of the present invention has been made in view of the problems of the prior art as described above, and is excellent in that high reflectance and high sensitivity can be achieved. An optical recording medium having a three-layer structure comprising a reflective layer of a dye, a transparent intermediate layer, and a light absorbing layer of an organic dye, wherein track grooves are formed in the reflective layer of the organic dye without using a stamper, and a method for producing the same. Is provided.

Another object of the present invention is to provide an optical recording medium capable of obtaining a high quality tracking signal with a high yield in a simpler process than ever before and a method of manufacturing the same.

[0011]

That is, according to the present invention, a light-reflecting layer comprising an organic dye thin film, a transparent intermediate layer, and a light absorbing layer comprising an organic dye thin film are sequentially laminated on a smooth transparent substrate, In an optical recording medium in which information is recorded by forming pits accompanied by a geometrical shape change using light of wavelength, and the presence or absence of the pits is discriminated by reflected light to reproduce information,
The optical recording medium is characterized in that a track groove for tracking is formed on the light reflecting layer by bleaching or partially scattering the organic dye thin film of the light reflecting layer.

Further, according to the present invention, a light reflecting layer formed of an organic dye thin film, a transparent intermediate layer, and a light absorbing layer formed of an organic dye thin film are sequentially laminated on a smooth transparent substrate, and light of a specific wavelength is used. In the method of manufacturing an optical recording medium, in which information is recorded by forming pits with a geometrical shape change, and the presence or absence of the pits is discriminated by reflected light to reproduce information, the light is irradiated to the light reflecting layer. Then, the organic dye thin film of the light reflecting layer is bleached or partially discolored to form a track groove for tracking to form an optical recording medium.

The present invention will be described in detail below. According to the present invention, a light-reflecting layer made of an organic dye thin film, a transparent intermediate layer, and a light absorbing layer made of an organic dye thin film are sequentially laminated on a smooth transparent substrate, and a geometric pattern is obtained by using light of a specific wavelength. In an optical recording medium in which information is recorded by forming pits accompanied by a physical shape change, the presence or absence of the pits is discriminated by reflected light, and information is reproduced. By irradiating light with a wavelength in the region of large absorption, the reflective layer is bleached or partly scattered with bleaching to form a track groove, and the track groove can be formed without using a stamper. An optical recording medium having a tracking signal can be manufactured with high yield.

FIG. 1 is a schematic sectional view showing an embodiment of the optical recording medium of the present invention. In the figure, the optical recording medium of the present invention comprises a smooth transparent substrate 1 on which a light reflection layer 2 made of an organic dye thin film, a transparent intermediate layer 3, and a light absorption layer 4 made of an organic dye thin film are sequentially laminated. A protective substrate 6 is provided on the absorption layer 4 with an adhesive 5, and a track groove 10 for tracking is formed on the light reflection layer 2 by decolorizing the organic dye thin film of the light reflection layer.

FIG. 2 is a schematic sectional view showing another embodiment of the optical recording medium of the present invention. It In the figure, a track groove 10 for tracking is formed in the light reflecting layer 2 by decolorizing and partially scattering the organic dye thin film of the light reflecting layer. The track groove 10 irradiates the light reflecting layer 2 with light to bleach the light reflecting layer 2 or
Or, it is a part where decolorization and a part are scattered.

The reflectance of the optical recording medium is as shown in FIG.
High reflectance can be obtained by multiple reflection among the light reflection layer 2, the transparent intermediate layer 3, and the light absorption layer 4. However, as shown in FIGS. 1 and 2, in the track groove 10 in which the light reflection layer 2 is decolorized or partially discolored and scattered, the multiple reflection is broken and the reflectance is lowered. The present invention is an optical recording medium and a method for manufacturing the same, in which a tracking signal is obtained by utilizing this effect.

As a method of forming the track groove 10, the method shown in FIG. 4 is used. The method of forming the track groove 10 uses light having a wavelength in a region in which the light reflection layer 2 has a large absorption. One of them is to narrow down the laser light to a track groove width and to direct the beam to the light reflection layer 2 in a desired track. There is a method of scanning in a groove pattern (see FIG. 4).
(See (a)). In this method, the laser beam may be scanned or the medium side may be moved. In addition,
20 is an optical recording medium, 21 is a laser, 22 is a prism,
23 is a condenser lens, 24 is laser light, 25 is light, 30
Is a mask, 31 is a mask pattern, and 32 is a spacer.

As another method, a mask 30 having a track groove pattern is used, and the mask 30 is placed in close contact with or in close proximity to a transparent substrate, and a laser beam is scanned or a xenon lamp or a halogen lamp is placed on the mask 30. There is a method of forming the track groove by collectively exposing with light such as (see FIGS. 4B and 4C).

The step of forming the track groove may be carried out at the end after the transparent substrate 1, the light reflecting layer 2, the transparent intermediate layer 3, the light absorbing layer 4, the adhesive layer 5 and the protective substrate 6 are brought into close contact with each other. It may be performed after forming the light reflection layer 2 on the transparent substrate 1. However, when the track groove is formed last, the wavelength of the light used for forming the track groove is preferably a wavelength in a region where the light reflection layer 2 has a large absorption but the light absorption layer 4 has a small absorption. This is to reduce crosstalk from the light absorption layer in the tracking signal.

Next, materials used for the optical recording medium of the present invention will be described. As the transparent substrate 1, information recording /
It may be transparent to the light used for reproduction, and for example, plastics such as polyester, acrylic resin, polyamide, polycarbonate resin, epoxy resin, polyimide, or glass can be used.

The light-reflecting layer 2 and the light-absorbing layer 4 both contain an organic dye as a main component, for example, polymethine type, azulene type, pyrylium type, squarylium type, croconium type,
Triphenylmethane type, xanthene type, anthraquinone type, cyanine type, phthalocyanine type, dioxazine type,
There are tetrahydrocholine type, triphenothiazine type, phenanthrene type, aminium salt / diimonium salt type, metal chelate complex type, and dye. Further, these dyes may be mixed in order to improve stability. The light reflection layer 2 and the light absorption layer 4 may be selected in consideration of the absorption maximum wavelength and reflectance of these dye thin films.

The transparent intermediate layer 3 may be transparent to light for recording / reproducing and can be formed into a film having a desired thickness. The thickness is the following formula

[0023]

[Equation 1] (Where, λ = wavelength of recording / reproducing light, n = refractive index of transparent intermediate layer, m; rearrangement of 0 or more).

The transparent intermediate layer 3 includes, for example, polyvinyl alcohol, polyvinyl acetal resin, polyurethane resin, polyamide, polystyrene, cellulose derivative, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer and its modified resin, acetic acid. Vinyl-acrylate copolymer, polyolefin and its copolymer, polycarbonate resin, acrylic resin, silicone resin,
Examples include polyester, polyparaxylylene, and petroleum-based resins. Examples of the film forming method include various coatings, vapor deposition, plasma polymerization CVD method, and the like.

The protective substrate 6 may be transparent or opaque, but a material having the same or similar property as that of the transparent substrate 1 is preferable so that it does not warp when exposed to temperature and humidity. .

Examples of the adhesive 4 include hot-melt type ethylene-vinyl acetate copolymer and its modified resin, ethylene-ethyl acrylate copolymer, vinyl acetate-acrylate copolymer, polyimide resin and the like. Further, since the thermosetting, photocurable, and photothermal combined curing type adhesives sometimes impinge on the optical recording layer, they cannot be directly adhered solidly, but can be used by partial adhesion or the like. This type of adhesive may be a known adhesive and is not particularly limited.

Next, a light source for forming the track groove 10 will be described. When a track groove is formed by scanning with a beam spot of laser light, for example, Xef (351 nm), N ₂ (337 nm), XCl
(308 nm), KrF (248 nm), KrCl (2
22 nm), an excimer laser such as ArF (193 nm), He-Ne (633 nm), Ar (488 nm, 5
14.5 nm) laser, semiconductor laser, CO ₂
A laser, a YAG laser, etc. can also be used. Further, in the case of mask exposure using a mask, a Xe lamp, a halogen lamp or the like can be used in addition to the above laser.

Further, as the mask base material of the mask used in the present invention, a material which does not absorb laser light is preferable. Therefore, as long as it has a high transmittance for the laser light, it may be either organic or inorganic. For example, for organic type, acrylic resin, polyester, imide type resin, polycarbonate, for inorganic type, quartz glass, soda lime glass,
A silicone substrate or the like can be used.

The mask material is preferably a material that absorbs laser light. Therefore, any material having a low transmittance for the laser light may be used. For example, Cr, Ni, Al,
Ti, TiN, NiCr, etc. can be used.

Further, if an antireflection film is formed on the film surface, the function can be enhanced.

[0031]

The present invention will be described in detail below with reference to examples.

Example 1 Polymethylmethacrylate having a thickness of 0.4 mm (hereinafter referred to as "P
Abbreviated as "MMA") transparent substrate (86 mm x 54 mm)
A solution of 2 parts by weight of a compound of the following structural formula [I] dissolved in 98 parts by weight of dichloroethane was applied as a light reflection layer thereon by a spinner (rotation speed 3000 rpm, 30 seconds) (thickness: about 1000Å), and then a transparent intermediate layer. An aqueous polyvinyl alcohol solution (Kuraray's Poval PV205, 3% by weight) was applied as a layer by a spinner (rotation speed 3000 rpm, 6
0 second) (thickness: about 1400Å) to form a film.

[0033]

[Chemical 1]

Next, a solution prepared by dissolving 5.5 parts by weight of the compound of the following structural formula [II] in 94.5 parts by weight of diacetone alcohol was coated on a polyethylene terephthalate having a thickness of 50 μm by a spinner (3000 rpm, 90 rpm).
Second) to form a light absorbing layer (thickness: about 1000Å), and then stack the transparent intermediate layer and the light absorbing layer so that they are adjacent to each other, and then EVA (ethylene-vinyl acetate copolymer) hot melt adhesion Agent sheet (thickness: 50 μm, 758 made by Hirodyne
0) was used and bonded to a PMMA protective substrate (thickness: 0.3 mm).

[0035]

[Chemical 2]

An Ar laser (488) was added to this card-shaped medium.
nm) to 3 μm spot, and this beam is 12 μm
The track groove portion was formed by scanning at a pitch to decolorize the light reflection layer. At this time, the laser power is 10 mW.

The optical card thus obtained is shown in the schematic sectional view of FIG. In this optical card, the reflectance of the track groove and the reflectance of the recording portion were measured using a semiconductor laser of 830 nm (spot diameter 3.0 μm, reproduction power 0.2 mW). Was 45%, and the contrast was as high as about 0.73.

Example 2 2.5 parts by weight of a compound of the following structural formula [III] was placed on a polycarbonate (hereinafter abbreviated as "PC") transparent substrate having a thickness of 0.4 mm and a size of 86 mm × 54 mm and diacetone alcohol. It was dissolved in 97.5 parts by weight, applied by a gravure coating method, and dried to form a light reflecting layer having a thickness of about 900Å.

[0039]

[Chemical 3]

As shown in FIG. 6, a mask on which an optical card pattern was formed was placed on this light reflecting layer via a spacer of 10 μm and irradiated with KrF laser light. At this time,
The mask was made by using quartz as a substrate and masked with Cr, and was placed so that the Cr masking surface faces the light reflection layer (see FIG. 6A).

The laser power at this time is an area of 5 mm ×
It was about 17 mJ at 30 mm and a distance of 300 mm. Due to this laser light irradiation, the laser-irradiated portion of the light-reflecting layer was decolored and partly scattered (see FIG. 6B), and the track groove width was 3.0.
An optical card pattern having a recording width of 9.0 μm and a recording portion width of 9.0 μm was formed.

Next, 2 parts by weight of a silicone resin (SD4570, manufactured by Shin-Etsu Silicone) was added to 9 parts of n-hexane.
Dissolve in 8 parts by weight and apply this solution with a spinner (300
At 0 rpm for 60 seconds), a film was formed as a transparent intermediate layer having a thickness of about 1500Å (see FIG. 6C).

Further, 1.5 parts by weight of the compound of the above structural formula [I] and 0.5 part by weight of the following compound of the following structural formula [III] were used as a light absorbing layer on a PC protective substrate having a thickness of 0.3 mm and diacetone alcohol. It was dissolved in 98 parts by weight, and a film was formed by gravure coating to a thickness of about 950Å (see FIG. 6 (d)).

[0044]

[Chemical 4]

After the light absorbing layer and the transparent intermediate layer were adhered to each other so as to be adjacent to each other, a light curable adhesive (made by Asahi Denka Co., Ltd.,
A bonded optical card was obtained with KRX-4) (see FIG. 6 (e)).

In the optical card medium thus obtained, the reflectance of the track groove and the recording portion was measured with a semiconductor laser of 830 nm at a spot size of 3.2 μmφ and a reproducing power of 0.2 mW. The recording area was 40% and the contrast was good at 0.75.

[0047]

As described above, according to the method of manufacturing an optical recording medium of the present invention, a DRAW type optical recording medium having a simple structure can be manufactured by a simple process without stamper type transfer. Mold transfer yield, transfer time,
Problems such as stamper type durability, low mass productivity and high cost can be solved.

Further, in the optical recording medium of the present invention, the light reflecting layer of the recording layer can be formed on a smooth substrate, so that a light reflecting layer having a uniform thickness can be obtained and stable recording sensitivity can be obtained. Further, when the light quantity ratio of the reflected light from the track groove and the optical recording portion is obtained as the contrast, a high contrast can be obtained, and a higher quality tracking signal can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an optical recording medium of the present invention.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the optical recording medium of the present invention.

FIG. 3 is an explanatory diagram of light reflection.

FIG. 4 is an explanatory diagram showing a method of forming a track groove.

FIG. 5 is a cross-sectional view of the optical card according to the first embodiment.

FIG. 6 is a manufacturing process diagram of the optical card of Example 2;

FIG. 7 is a cross-sectional view of a conventional optical card.

[Explanation of symbols]

 1 Transparent Substrate 2 Light Reflecting Layer 3 Transparent Intermediate Layer 4 Light Absorbing Layer 5 Adhesive 6 Protective Substrate 7 Hard Coat Layer 8 Support Plate 9 Recording Layer 10 Track Groove 20 Optical Recording Medium 21 Laser 22 Prism 23 Condensing Lens 24 Laser Light 25 Light 30 Mask 31 Mask pattern 32 Spacer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Miki Tamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroyuki Sugada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (5)

[Claims] 1. A light-reflecting layer composed of an organic dye thin film, a transparent intermediate layer, and a light absorbing layer composed of an organic dye thin film are sequentially laminated on a smooth transparent substrate, and geometrically formed by using light of a specific wavelength. In an optical recording medium in which information is recorded by forming pits accompanied by a shape change, and the presence or absence of the pits is discriminated by reflected light to reproduce information, the track groove for performing tracking on the light reflecting layer is the light reflecting layer. An optical recording medium, characterized in that it is formed by decolorizing an organic dye thin film or by partially scattering it. 2. A light-reflecting layer made of an organic dye thin film, a transparent intermediate layer, and a light absorbing layer made of an organic dye thin film are sequentially laminated on a smooth transparent substrate, and geometrically formed by using light of a specific wavelength. In a method of manufacturing an optical recording medium in which pits accompanied by a shape change are formed to record information, the presence or absence of the pits is discriminated by reflected light, and information is reproduced, the light is reflected to a light reflection layer. A method of manufacturing an optical recording medium, characterized in that a track groove for performing tracking is formed by decolorizing or partially scattering the organic dye thin film of the layer. 3. The method for manufacturing an optical recording medium according to claim 2, wherein the wavelength of the light with which the light reflecting layer is irradiated is a region in which the light reflecting layer has a large absorption. 4. The method for manufacturing an optical recording medium according to claim 2, wherein the light applied to the light reflection layer is a laser light, and the laser light is narrowed down to a track groove width and applied. 5. The method of manufacturing an optical recording medium according to claim 2, wherein the light reflection layer is irradiated with light through a mask having a track groove pattern.