JP2000339774A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfy both of the optical recording characteristic and the visibility to visible information on the back of a recording film in the optical information recording medium which is provided with the recording film consisting of intermediate oxides of tellurium (TeOx) which are excellent in stability, weatherability and recording sensitivity. SOLUTION: This optical information recording medium C is an optical information recording medium having the recording film 2 consisting of the intermediate oxides of tellurium. The recording film 2 is formed so as to have a refractive index for the light of 632.8 nm wavelength within the range of 2.9-3.0 and a thickness within the range of 300 Å-400 Å. The visible information layer (a card substrate 4) is disposed on the back side of the recording film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium capable of recording and / or reproducing information with a light beam, and more particularly to an optical information recording medium in which visible information is recorded in an optical information area. Regarding the medium.

[0002]

2. Description of the Related Art As a prior art relating to an optical recording medium provided with visible information behind an optical recording film, Japanese Patent Application Laid-Open No.
There is an information recording medium described in Japanese Patent No. 0595/95. This information recording medium includes a substrate, a recording layer in the visible light region, and a back substrate containing visible information, and an organic dye is disclosed as a material of the recording layer. Further, the thickness of the recording layer is usually 500 to 2000 Å, preferably 600 to 1200 Å.

[0003] Japanese Patent Application Laid-Open No. 6-55886 discloses that
An optical card is disclosed. This optical card is composed of a light-transmissive substrate, an optical recording material layer, an adhesive, and a card substrate including a printing layer. As a material for the optical recording material layer, a two-layer film of TeOx and TeOy is disclosed. The thickness of the optical recording material layer is set to 500 angstroms.

[0004] Japanese Patent Application Laid-Open No. 5-254283 discloses an optical card and a reader therefor. This optical card is composed of a transparent layer, a light-transmissive recording layer, and a substrate containing visible information (printing). The material of the recording layer and the like are not specifically suggested.

Japanese Patent Application Laid-Open No. 6-55887 discloses that
An optical information recording medium is disclosed. This optical information recording medium includes a light transmitting layer, a light transmitting optical recording material, a visible information recording layer, and a card base material. As a material of the optical recording material, a Te-Se alloy is disclosed. It is disclosed that the transmittance of the recording material is 1% or more, preferably 10% or more.

On the other hand, as a prior art relating to an optical recording material comprising tellurium oxide, for example, Japanese Patent Application Laid-Open No. 5-32626 is known.
There is an optical card described in Japanese Patent Application Laid-Open No. 6-206. This optical card includes a light-transmitting base material, a pattern, and an optical recording layer, and the optical recording layer is formed of tellurium intermediate oxide. This optical recording layer has a wavelength of 7 on a silicon wafer.
The refractive index measured with a laser beam of 80 nm is 2.7 to 3.5.

[0007] Japanese Patent Publication No. 54-3725 discloses that
An optical recording member is disclosed. This optical recording member is composed of a substrate and tellurium low oxide TeOx (0 <x <2). Although the thickness of tellurium low oxide is described as 300 Å to 3000 Å, there is no suggestion about the refractive index.
Further, although there is disclosure of a transmission spectrum, there is no suggestion about the relationship with the film thickness.

[0008]

In the case where visible information is provided behind a transparent recording film, the relationship between the characteristics of the recording film and the visibility of the visible information has not been sufficiently studied. For example, in JP-A-2-30595,
There is only disclosure about the thickness (preferably 600 to 1200 angstroms) of a recording film composed of an organic dye, but no disclosure or suggestion regarding the relationship between other characteristics of the recording film and the visibility of visible information. Similarly, Japanese Patent Application Laid-Open
Japanese Patent No. 55886 discloses only the thickness (500 Å) of an optical card composed of a two-layer film of TeOx and TeOy, and relates to the relationship between other characteristics of the recording film and the visibility of visible information. No disclosure or suggestion.

On the other hand, data bits can be recorded by irradiating an optical recording film made of tellurium low oxide with light such as a laser, for example, as described in JP-A-6-55887 and JP-A-5-325266. The characteristics of a recording film suitable for realizing high optical recording characteristics by providing a sufficient contrast between data bits and other portions with a commercially available semiconductor laser or the like have been sufficiently studied. Did not.

The present invention has been made in view of the above points, and has been made in view of the above circumstances, and has an optical information recording device having a recording film made of tellurium intermediate oxide (TeOx) which is excellent in stability, weather resistance and recording sensitivity. It is an object of the present invention to provide an optical information recording medium that satisfies both optical recording characteristics and visibility of visible information behind a recording film.

[0011]

The present invention relates to an optical information recording medium provided with a recording film made of tellurium intermediate oxide, wherein the recording film has a refractive index of 22.8 nm for light having a wavelength of 632.8 nm. 0.9 to 3.0, and the film thickness is 30.
An optical information recording medium formed to be in a range of 0 Å to 400 Å.

According to the present invention, it is possible to provide an optical information recording medium having both practically sufficient optical recording characteristics and visibility of visible information behind the optical recording section.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, W
FIG. 3 is a sectional view of an ORM type optical card, which corresponds to the xy sectional view of the optical card C shown in FIG.

An optical card C shown in FIG. 1 has a light transmitting pattern resin layer 1 on one side (back side) of a light transmitting base material 5.
An optical recording material layer 2 (recording film) is formed in this order, and a card substrate 4 (visible information layer) is further laminated via an adhesive layer 3. On the surface of the substrate 5 opposite to the side on which the optical recording material layer 2 is provided, a light-transmitting surface hardened layer 6 is laminated.

The card base material 4 includes an oversheet 4
a, a core sheet 4b, and an oversheet 4c are sequentially laminated, and a three-layer structure is used. A printing layer 7 is provided between the oversheet 4a and the core sheet 4b on the optical recording material layer 2 side.
a and 7b are the over sheet 4c and the core sheet 4b
Is provided with a printing layer 7c. Each printing layer 7a,
Visible information such as characters and pictures is printed on 7b and 7c.

The optical recording material layer 2 is made of a TeOx film (0 <x <2), which is an intermediate oxide of tellurium, and has a thickness of 3%.
00 to 400 angstroms.

The optical card C shown in FIG. 1 is produced by the steps shown in FIG. Hereinafter, this step will be described in order.

First, a roughened master having a low-reflectance portion roughened in accordance with an information recording pattern is prepared by a conventional method as disclosed in Japanese Patent Publication No. 7-64141.

As a first step, a transparent substrate (400 μm thick)
m of an acrylic plate) is uniformly coated with a photoresist to a thickness of 5000 angstroms by a rotary photoresist coating machine to form a photoresist layer (resist coating). As the photoresist, "Microposit 1400 manufactured by Shipley Co., Ltd." which is a positive resist (quinonediazide system) was used.

Next, as a second stage, after a photomask formed according to the information recording pattern is superimposed on the photoresist layer by using a mask alignment device, the first exposure (patterning exposure) with ultraviolet rays is performed.

Subsequently, as a third step, a glass plate having one surface roughened into fine irregularities (average roughness 0.3 μm, #
Exposure again using 3000 polished glass (roughening exposure)
I do.

After exposure, as a fourth step, the photoresist layer is developed. As a result, the photoresist that has been irradiated with ultraviolet rays flows away, and the photoresist that has not been irradiated remains, and the pattern of the photomask is transferred onto the transparent substrate. As a result, a photoresist layer having a roughened surface is formed with a guide track shape having a width of about 2.5 μm and a pitch of about 12 μm, for example.

Next, an optical recording medium having an information recording pattern formed of a low-reflectance portion having a roughened surface is formed.
A roughened master is used, and a mother mask is duplicated from the roughened original by a molding press.

More specifically, a transparent substrate (an acrylic plate having a thickness of 1.2 mm) was formed on a transparent substrate (a 1.2-mm-thick acrylic plate) via a molding agent formed of an ionizing radiation-curable resin or a thermosetting resin. After irradiating the UV light with the roughened original plate laminated and pressed by a press machine, release the roughened original plate and the transparent base material, duplicate the pattern on the transparent base material side, and apply a mother mask. Form. In this embodiment, as a molding resin, a UV curable resin (manufactured by The Inktec, SEL-XA (mainly composed of a polyester acrylate oligomer and neopentyl glycol diacrylate monomer, Irgacure 18) is used.
4 (to which a photopolymerization initiator) was added)).

Examples of other molding agents are listed below.
Among the ionizing radiation-curable resins, electron beam-curable resins include acryloyl groups such as urethane acrylate, oligoester acrylate, trimethylolpropane triacrylate, neopentyl glycol diacrylate, epoxy acrylate, polyester acrylate, polyether acrylate, and melamine acrylate. Or a mixture of the above oligomer or monomer and a monofunctional or polyfunctional monomer containing a polymerizable vinyl group such as acrylic acid, acrylamide, acrylonitrile, styrene and the like.

The ultraviolet-curable resin of the ionizing radiation-curable resin is obtained by adding a photopolymerization initiator, a sensitizer, or a desired additive to the resin compositions listed as the electron beam-curable resin.

As the thermosetting resin, epoxy resin, melamine resin, unsaturated polyester resin, urethane resin,
Urea resin, amide resin, phenol / formalin resin.

On the other hand, a hardened surface layer 6 is formed on a transparent base material to be the transparent protective layer 5 of the optical card C.

Here, as the substrate 5, polycarbonate (PC) having a thickness of 400 μm was used. In addition, polymethyl methacrylate (PMMA), acrylonitrile-styrene copolymer (AS resin), cellulose propionate (CP), cellulose acetate butyrate (CA)
B), polyvinyl chloride (PVC), polyester, and the like can be used. In this embodiment, PC having a small birefringence is used. As the surface cured layer 6, an acrylic UV-curable hard coat agent (UH-001, manufactured by Toray Industries, Inc.) was used. In addition, a UV curable resin (oligomer, monomer initiator), a melamine-based thermosetting resin, or the like can also be used.

Next, the light-transmitting pattern resin layer 1 is duplicated on the back side of the substrate 5 by molding using the mother mask as a duplication master for mass duplication.

Specifically, after duplicating resin is sandwiched between the back side surface (back surface) of the base material 5 and the pattern surface of the mother mask, the ultraviolet light is irradiated while being pressed by a press machine.
The pattern is duplicated on the substrate 5 side by releasing the substrate 5 and the mother mask. Thus, a low reflectance portion is formed on the surface of the duplication resin, and this duplication resin becomes the light-transmitting pattern resin layer 1 of the optical card C. And the pattern resin layer 1, the base material 5, and the surface hardened layer 6 become a light-transmitting protective layer.

In this embodiment, an ultraviolet-curing resin (SS-120, urethane acrylate) manufactured by Three Bond Co., Ltd. was used as the replica resin. In addition, various ionizing radiation-curing resins described in the section of forming a mother mask were used. You may.

Subsequently, an optical recording material layer 2 is laminated so as to cover a low reflectance portion of the light transmitting pattern resin layer 1 made of a duplication resin. Specifically, TeO
The x film was formed in a thickness of 300 to 4 using a reactive sputtering apparatus.
The optical recording material layer 2 was formed to have a thickness of 00 Å.

Here, the method of laminating the optical recording material layer 2 will be described in detail. A metal mask is superimposed on the base material 5 integrated with the pattern resin layer 1 formed from the molding agent, and a sputtering apparatus is used. 1 in the substrate holder
Exhaust to a pressure of the order of × 10 ^-5 Torr, Ar gas and O
₂ Introduce the gas while controlling it with a flow meter. Next, in order to stably maintain the glow discharge, the main valve is adjusted to a pressure of the order of 1 × 10 ⁻³ Torr, and spark is generated to generate sputtering. An RF power source having a capacity of 1 kW was used as a power source, and tellurium (Te) having a diameter of 10 inches was used as a target. Before the film formation, in order to stabilize the target surface in the atmosphere in a constant state, pre-sputtering is performed for 5 minutes while the shutter is closed, and then the sputtering is performed for 12 minutes.
For a minute.

The RF output at this time is 310 W,
The oxygen input was 505 sccm and the argon input was 90 sccm.

In this case, the Si wafer was fixed on the mask with a heat-resistant tape, and the film thickness was measured by a stylus type step thickness gauge to be 300 Å. Further, when the refractive index was measured with an ellipsometer using laser light (He-Ne laser) having a wavelength of 632.8 nm,
The result as shown in FIG. 4 was obtained. FIG. 4 shows the relationship between the oxidation degree of tellurium (x value of TeOx) and the refractive index when the oxidation degree of tellurium is changed. Further, when a writing test using a laser was performed, the refractive index was found to be 2.9 to
It was found that the writing performance and the stability over time were excellent in the range of 3.0. At this time, light (semiconductor laser) with a recording bit contrast of 0.4 or more and a wavelength of 780 nm
And a read ride error rate of about 1 × 10 ^−4, and excellent recording response and recording bit shape. In FIG. 1, the optical recording portion is shown as 8a and the non-recording portion is shown as 8b.

As shown in FIG. 5, the recording pit contrast is the ratio of the recording bit level B to the complete black level A, that is, B / A, which is a unitless amount.
For example, the optical card C is inserted into a reader / writer to be in a READ mode, and a READ waveform (FIG. 5) is observed and measured with an oscilloscope or the like.

Now, apart from the above series of steps, a card base material 4 is prepared. The card base material in this embodiment is formed by providing printing layers 7a, 7b, 7c on both sides of a core sheet 4b, and laminating over-sheet layers 4a, 4b thereon.

As the core sheet 4b, substances such as milky white vinyl chloride, polycarbonate, cellulose acetate butyrate (CAB) and cellulose acetate propionate (CAP) can be used.
It may be about 20 μm.

In this embodiment, a printed layer 7b on which normal printing is performed is provided on a portion corresponding to the optical recording material layer 2 on the core sheet 4b.

The ink used for the printing layer 7b includes
Silk inks for acrylic, soft vinyl chloride, hard vinyl chloride, etc., for example, SS-8 series (manufactured by Toyo Ink), Sericol CAD series (manufactured by Teikoku Ink)
However, there is no particular limitation. By silk screen printing using these inks, desired patterns, characters, and the like are printed on the entire surface of the core sheet 4b, and the print layer 7b is formed. Usually, silk screen printing and offset printing are used for printing on the card, but in offset printing, the oversheet 4a does not join with the core sheet 4b during hot pressing. Therefore, in this case, the printing layer 7b is formed by silk screen printing with good bonding at the time of hot pressing.
Is preferably formed.

The printing layer 7a and the printing layer 7c on the side opposite to the core sheet are formed in substantially the same manner as the printing layer 7b.

For the purpose of protecting the printing layers 7a, 7b, 7c, over-sheet layers 4a, 4c are further provided on the printing layers 7a, 7b, 7c. The oversheet layers 4a and 4c are made of a material such as transparent vinyl chloride, transparent CAB, and transparent CAP. When the oversheet layers 4a and 4c are provided on both sides of the core sheet 4b, the card base 4 has a three-layer structure, so that warpage during hot pressing is prevented.

Then, the card substrate 4 is bonded and laminated to the substrate 1 provided with the optical recording material layer 2 via the adhesive layer 3. Specifically, “Toray UH-1260C” (two-component curing type) was used and bonded at a normal temperature to a thickness of 60 μm. In this case, since the adhesive layer 3 is in direct contact with the oversheet 4a (transparent polyvinyl chloride) of the card base material 4 over the entire surface, the adhesive layer 3 is firmly adhered. Note that a hot melt type adhesive may be used.

An optical card C shown in FIGS. 1 and 2 is produced by punching the raw material produced as described above.
In this state, the print layers 7a, 7b
At this time, the optical recording material layer 2, the pattern resin layer 1, the base material 5, and the surface hardened layer 6 have a wavelength of 55 nm.
A light transmittance of 22% or more for 0 nm light was achieved. Here, the wavelength of 550 nm means a peak wavelength of human luminosity (representative of visible light).

As described above, according to the present embodiment, both practically sufficient optical recording characteristics and visibility of visible information behind the optical recording section can be achieved.

In the case of the present embodiment in the form of a card, the optical recording film area occupies most of one side of the card. Therefore, by providing visible information such as character information and images in the area, the design can be improved. The degree of freedom can be significantly increased.

In the process leading to the present invention, the main factor that determines the sensitivity of the recording film is the refractive index. If the refractive index is within a predetermined range, the thinner the film thickness, the smaller the film thickness. While finding that the visibility of the visible information is enhanced, the present inventors have also found that if the film thickness is too thin, the recording sensitivity is reduced. The following can be explained by supplementing the criticality of each numerical limitation of the present invention based on these findings.

When the thickness of the recording film is substantially larger than 400 Å, the transmittance of the recording film becomes low,
Visible information behind the recording film becomes difficult to see. On the other hand, the recording sensitivity is not so good.

When the thickness of the recording film is substantially smaller than 300 angstroms, the reflectance of the recording film becomes low,
The recording sensitivity decreases, that is, the contrast of the recording bit decreases.

When the refractive index of the recording film with respect to light having a wavelength of 632.8 nm is substantially larger than 3.0, the recording sensitivity and the reflectance of the recording film are improved, but the transmittance of the recording film is reduced.

When the refractive index of the recording film with respect to light having a wavelength of 632.8 nm is substantially smaller than 2.9, the reflectance of the recording film becomes low, and the recording sensitivity is lowered, that is, the contrast of the recording bit is lowered. .

[0053]

According to the present invention, it is possible to provide an optical information recording medium having both practically sufficient optical recording characteristics and visibility of visible information behind the optical recording section.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of an optical information recording medium according to the present invention.

FIG. 2 is an overall schematic diagram showing the optical information recording medium of FIG. 1;

FIG. 3 is a process chart for producing the optical information recording medium of FIG. 1;

FIG. 4 is a graph showing the relationship between the oxidation degree of tellurium and the refractive index.

FIG. 5 is a diagram illustrating the contrast of a recording bit.

[Explanation of symbols]

 C Optical card 1 Pattern resin layer 2 Optical recording material layer (recording film) 3 Adhesive layer 4 Card base 4a, 4c Oversheet 4b Core sheet 5 Base 6 Surface hardened layer 7a, 7c Print layer 7b Corresponds to optical recording section Printing layer 8a Optical recording part 8b Non-recording part

Claims (9)

[Claims] 1. An optical information recording medium provided with a recording film made of a tellurium intermediate oxide, wherein the recording film has a refractive index for light having a wavelength of 632.8 nm in a range of 2.9 to 3.0. An optical information recording medium characterized in that the optical information recording medium is formed so as to have a thickness within a range of 300 Å to 400 Å. 2. The optical information recording medium according to claim 1, wherein a visible information layer is provided on the back side of said recording film. 3. The optical information recording medium according to claim 2, wherein said visible information layer is a printed layer on which visible information is printed. 4. The optical information recording medium according to claim 2, wherein the recording film and the visible information layer are bonded by a light-transmitting adhesive layer. 5. The recording film according to claim 1, wherein said recording film has a recording bit contrast of 0.4 or more and a reflectivity for light having a wavelength of 780 nm of 25% or more. 5. The optical information recording medium according to any one of 4. 6. The optical information recording apparatus according to claim 1, wherein the recording film is formed so that the light transmittance for light having a wavelength of 550 nm is 22% or more. Medium. 7. The optical information recording medium according to claim 1, wherein a light-transmitting protective layer is provided on the front side of said recording film. 8. The recording film and the protective layer have a wavelength of 550.
The optical information recording medium according to claim 7, wherein the optical information recording medium is formed so as to have a light transmittance of 22% or more for light of nm. 9. The optical information recording medium according to claim 1, wherein the whole is formed in a card shape.