JP2003257082A - Optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk wherein the error caused by adhesion of dirt can be prevented. <P>SOLUTION: A photocatalyst layer 16 to be photoactivated by the wavelength of a laser beam L for reproducing and recording information is formed on the surface of the optical disk 10 on which the laser beam L is made incident and the photocatalyst layer 16 consists of a substance formed by substituting nitrogen atoms N for a portion of oxygen atoms O of titanium oxide TiO<SB>2</SB>. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc on which information is reproduced or recorded by laser light.

[0002]

2. Description of the Related Art CD, CD-ROM, MO, MD, DV
In an optical disk such as D, a laser beam is used to read, write, or read or write a signal. Therefore, if the incident surface of the laser beam is dirty, the optical signal is disturbed and an error is caused. By causing such an error, the focus may be lost, and the objective lens may come into contact with or scratch the disk surface.

[0003]

In an optical disc which is used by exposing a medium such as a CD, since the user directly handles it by hand, the adhesion of dirt is unavoidable.

Further, as represented by MO and MD, an optical disk used in a state where a medium is housed in a cartridge is not as hard as an optical disk used for being exposed, but under severe working environment such as a machining factory. When used in, it may become dirty. When the cartridge is stored in this way, it is unavoidable that the cost is increased by the amount of the cartridge.

Particularly, as the recording density of the optical disc is increased, the durability against dirt is reduced, and thus the dirt on the incident surface of the laser beam becomes a problem.

In order to solve the above problems, the present invention provides an optical disc capable of preventing the occurrence of an error due to the attachment of dirt.

[0007]

The optical disc of the present invention comprises:
A photocatalyst layer that becomes photoactive at the wavelength of this laser light is formed on the surface on the side where the laser light for reproducing or recording information is incident, and this photocatalyst layer forms part of the oxygen atoms of titanium oxide with nitrogen atoms. It is composed of the replaced substance.

According to the above-mentioned structure of the optical disc of the present invention, the photocatalytic layer which is photoactive at the wavelength of the laser light is formed on the surface on the side on which the laser light for reproducing or recording information is incident. By irradiating laser light for reproducing or recording information, the photocatalyst layer in the area exposed to the laser light is activated, and it is possible to decompose, for example, organic contaminants attached to the photocatalyst layer. In addition, since the photocatalyst layer is made of a substance in which a part of oxygen atoms of titanium oxide is replaced with nitrogen atoms, organic contaminants attached to the photocatalyst layer can be decomposed by the action of titanium oxide,
Since part of the oxygen atoms of titanium oxide is replaced with nitrogen atoms, it becomes possible to activate the photocatalytic layer with laser light in a wavelength range longer than that of titanium oxide alone.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a photocatalyst layer which becomes photoactive at the wavelength of the laser light is formed on the surface on the side on which the laser light for reproducing or recording information is incident, and the photocatalyst layer is oxidized. It is an optical disc made of a material in which some of the oxygen atoms of titanium are replaced with nitrogen atoms.

The present invention also provides the above-mentioned optical disc,
1 to 10% of oxygen atoms are replaced by nitrogen atoms.

As an embodiment of the present invention, a schematic configuration diagram (cross-sectional view) of an optical disc is shown in FIG. This optical disc 10 has a polycarbonate substrate 11 that serves as a disc substrate.
A reflection layer 12 is formed on the polycarbonate substrate 11, and a cover film 15 and an adhesive layer 14 such as UV-
PSA (PSA (Pressure Sensiti)
ve adhensive; pressure sensitive adhesive). A pregroove (not shown) is formed on the polycarbonate substrate 11, and a recording layer 13 is formed on the upper surface of the reflective layer 12.

In the optical disc 10, the laser beam L is made incident from the side opposite to the disc substrate 11, that is, the side of the cover film 15 to read, write, read and write the recording layer 13, that is, reproduce or record information. It is composed.

In the optical disk 10 of this embodiment, the photocatalyst layer 16 is formed on the surface of the laser light L incident surface side, that is, on the cover film 15.

Further, the photocatalyst layer 16 is made of titanium oxide Ti.
Substance T in which a part of oxygen atom O of O ₂ is replaced by nitrogen atom N
iO _(2-x) N _x . As a result, the titanium oxide TiO ₂ is activated by the laser light irradiation L, so that the region hit by the laser light L is activated, and the organic contaminants adhering to the surface of the optical disc 10, that is, the surface of the photocatalyst layer 16 are decomposed and decomposed. Has the function of removing.

Further, by substituting a part of the oxygen atoms O of titanium oxide TiO ₂ with nitrogen atoms N, the wavelength range of the activating laser beam can be extended to the longer wavelength side than titanium oxide alone. The activation becomes possible not only in the ultraviolet region but also in a wide wavelength range of the visible light region (for example, to 600 nm).

For example, the photocatalyst layer 16 of titanium oxide TiO ₂ alone is suitable for the optical disk 10 using a deep UV laser having a wavelength of 266 nm as the laser beam L, for example, a part of oxygen atoms of titanium oxide TiO ₂ is nitrogen atoms. when using substituted TiO _(2-x) N _x photocatalytic layer 16 becomes for example suitable to the optical disk 10 using the laser beam L with a wavelength of 405 nm.

The amount of substitution of oxygen atoms by nitrogen atoms is preferably in the range of 1 to 10% of oxygen atoms.

The photocatalyst layer 16 made of such a substance (hereinafter referred to as titanium oxide photocatalyst) is generally used for vacuum deposition, sputtering, dipping, spin coating, bar coating, spraying, It is formed by a technique such as pyrosol film formation.

Here, it is conceivable that light in the wavelength range that activates the photocatalytic layer 16 of the optical disk 10 is supplied by an ultraviolet lamp or the like provided separately from the laser light L for reproducing or recording information on the optical disk 10. However, in this configuration, since the light source for activation has to be installed separately from the optical head, the cost of the disk device is high and it is necessary to secure a large space in the disk device.

On the other hand, in the present embodiment, the recording layer 1 of the optical disk 10 is read by the laser light L for reading, writing, or reading / writing, that is, reproducing or recording information.
For 3 the information can be reproduced or recorded, and the area of the photocatalyst layer 16 exposed to the laser beam L can be activated to decompose the dirt adhering to the surface. This allows
The laser light L from the same light source can both reproduce and record information and activate the area of the photocatalyst layer 16 that is exposed to the laser light L, and does not require a special configuration for the disk device. Then, by irradiation with the laser light L,
The activation can be repeated.

Instead of the above-mentioned titanium oxide photocatalyst, it is also possible to use a substance such as an indium tantalate compound, which is activated by irradiation with ultraviolet rays and decomposes water, in the photocatalyst layer 16. The photocatalyst layer 16 can be formed by using a substance such as an indium tantalate-based compound together with a titanium oxide-based photocatalyst.

As the indium tantalate-based compound, indium tantalate (InTaO ₄ ) which is an inorganic oxide semiconductor is doped with Ni, and NiO _x (nickel oxide) is further formed on the surface ( For example, NiO _x / In _0.9 Ni _0.1 TaO
₄ ) etc. are known.

When, for example, an indium tantalate-based compound which is photoactivated in the visible light region near a wavelength of 402 nm is used for the photocatalyst layer 16, the wavelength is 400 to 410 n.
In the optical disc 10 using the laser light L of m, when recording, reproducing, or recording / reproducing information, the area exposed to the laser light L can be activated to decompose and remove water on the surface of the optical disc 10.

Also, by performing Ni doping treatment on indium tantalate, the wavelength range for photoactivation is expanded to the longer wavelength side, and photoactivation can be widely performed in the visible light region.

Further, when NiO _x is supported on the surface of the indium tantalate-based compound, the water adhering to the surface of the optical disk 10 can be completely decomposed into hydrogen and oxygen. In this case, the generated oxygen also has the effect of oxidizing and decomposing organic contaminants on the disk surface.

The photocatalyst layer 16 made of the above-mentioned indium tantalate compound can be formed by, for example, a vacuum deposition method, a sputtering method, a dipping method, a spin coating method, a bar coating method, a sol-gel method, a spraying method or a pyrosol film formation. it can.

By the way, in an optical disc used for exposing a medium such as a CD, dirt such as dust may be fixed by the water adhering to the surface, which may also cause an error. Further, this water easily causes mold on the surface of the optical disk, which is not only unsanitary, but also causes mold to cause an error. Also,
An optical disc that stores a medium in a cartridge and is used is not as good as an optical disc that is used to expose the medium, but depending on the environment of use, water adhesion and accompanying stains may be attached.

In the case of a so-called flying head or the like in which the optical head is arranged in the immediate vicinity of the disk surface, the optical head easily sticks due to water adhering to the surface of the optical disk. In some cases, the disk surface may be scratched or the head itself may be damaged.

Therefore, by using the above-described indium tantalate-based compound for the photocatalyst layer 16, laser light is emitted by irradiating laser light L for reading, writing, or reading / writing of information from the optical disk 10, that is, reproduction or recording of information. It becomes possible to activate the region hit by L to decompose and remove the attached water.

According to the optical disk 10 of the present embodiment described above, the photocatalyst layer 16 using the substance TiO _(2-x) N _{x in} which a part of the oxygen atoms O of titanium oxide TiO ₂ is replaced by the nitrogen atoms N is used. , Reading and writing information on the optical disc 10,
Alternatively, since it is provided on the surface on the incident surface side of the laser light L for reading / writing, that is, for reproducing or recording information, the reproduction or recording of information is performed by irradiation of the laser light L for reproducing or recording information on the optical disc 10. It is possible to perform recording and activate the area exposed to the laser beam L to decompose and remove the attached dirt.

Therefore, it is possible to decompose and remove organic stains on the surface of the optical disk at low cost without requiring a special structure.

Further, it can be applied regardless of whether the optical disk 10 is housed in a cartridge or not.

Further, when a material such as an indium tantalate compound which is activated by irradiation with laser light and decomposes water adhering to the surface is used for the photocatalyst layer 16, no special constitution is required. The water on the surface of the optical disk can be decomposed and removed at low cost. In this case, as a secondary effect, it is possible to suppress the fixation of dust and the generation of mold. Furthermore, when a photocatalyst that completely decomposes water into hydrogen and oxygen is used, the generated enzyme also has an effect of oxidizing and decomposing / removing organic contaminants on the surface of the optical disk 10.

Next, other embodiments of the optical disk of the present invention are shown in FIGS. 2A to 2C, respectively. First, FIG. 2A
The optical disc 21 shown in FIG.
The recording layer 13B has two recording layers 13B, and the reading and writing of signals (reproduction or recording of information) is performed from one side. The optical disc 21 is formed by forming a reflection layer 12 on a polycarbonate substrate 11 having a pre-groove (not shown).
Is formed, and the first recording layer 1 is formed on the upper surface of the reflective layer 12.
3 is formed. Further, the second recording layer 13B is formed on the lower surface of the cover film 15 in which a pre-groove (not shown) having the second recording layer 13B is formed. Then, the polycarbonate substrate 11 and the cover film 15 are connected to each other with an adhesive layer 14 such as UV-PSA.
The optical disk 21 is formed by laminating with. Further, in this optical disc 21, in order to obtain a signal from the second recording layer 13B, the cover film 15 and the adhesive layer 1
A semi-transmissive reflective layer 17 is provided between the semi-transmissive reflective layer 17 and the reflective layer 4. In this optical disc 21 as well, the photocatalyst layer 16 is formed on the surface which is the incident surface side of the laser light L for reproducing or recording the information of the recording layer 13, that is, on the cover film 15. Thus, by irradiating the laser light L for reproducing or recording information on the recording layer 13, the area exposed to the laser light L can be activated to decompose and remove the attached organic contaminants.

Next, the optical disk 22 shown in FIG. 2B has two recording layers, a first recording layer 13A and a second recording layer 13B, and reads and writes signals (reproduction or recording of information) from both sides. It is something to do. Although not shown, the optical disk 22 includes two polycarbonate substrates 11A and 11B each having a pre-groove, and a reflective layer 12
By providing A and 12B, the first recording layer 13A and the second recording layer 13B are respectively configured. And
These two polycarbonate substrates 11A and 11B are
The optical disk 22 is formed by bonding the adhesive layers 14 such as UV-PSA so that the reflective layers 12A and 12B and the recording layers 13A and 13B are on the inside. In this optical disc 22, photocatalyst layers 16 are formed on the surfaces of the polycarbonate substrates 11A and 11B on which the laser light L is incident, that is, on the upper surface and the lower surface of the optical disk 22, respectively. As a result, by irradiating the laser beam L for reproducing or recording information on the recording layers 13A and 13B, it is possible to activate the region exposed to the laser beam L and decompose and remove the attached organic contaminants.

Next, the optical disc 30 shown in FIG. 2C is similar to a so-called compact disc (CD) in that the recording layer 3
The laser beam L is irradiated from the side of the polycarbonate substrate 31 on which 2 is formed to read and write signals in the recording layer 32 (reproduction or recording of information). This optical disc 3
In the case of 0, a recording layer 32 is formed on a polycarbonate substrate 31 having a pregroove (not shown), and a cover film 33 made of a UV curable resin is further arranged. In this optical disc 30, the photocatalyst layer 1 is formed on the surface of the polycarbonate substrate 31 on which the laser light L is incident.
6 is formed. Thus, by irradiating the laser light L for reproducing or recording the information on the recording layer 32, the area exposed to the laser light L can be activated to decompose and remove the dirt of the attached organic matter.

Next, as a method of manufacturing an optical disk having a photocatalyst layer of the present invention, the optical disk 1 having the structure shown in FIG.
A manufacturing method of 0 will be described.

In FIG. 3, the photocatalyst layer 16 is formed on the cover film 15 in advance, and the photocatalyst layer 16 is formed on the cover film 15 via the adhesive layer 14.
It is a manufacturing method in which it is bonded to the polycarbonate substrate 11 having No. 3. First, the thickness shown in FIG. 3A is, for example, 75 μm.
Cover film 1 made of polycarbonate resin
Prepare 5. Then, as shown in FIG. 3B, a photocatalyst layer 16 is formed on the cover film 15 by a sputtering method to have a thickness of 5 nm, for example. Further, the reflective layer 12 is formed on the polycarbonate substrate 11 on which the pre-groove is formed, the recording layer 13 is formed on the upper surface of the reflective layer 12, and the adhesive is made of a UV-curing pressure-sensitive adhesive having a thickness of, for example, 25 μm. The layer 14 is prepared. The adhesive layer 14 is in a semi-solidified state, and is obtained by cutting a sheet having upper and lower sides sandwiched by a release film (not shown) into a predetermined size.
Then, the peeling film of the adhesive layer 14 is peeled off, and as shown in FIG. 3C, the reflective layer 12 is peeled off by the adhesive layer 14.
Polycarbonate substrate 11 on which a photocatalyst layer 1 is formed
The cover film 15 on which 6 is formed is attached. In this way, the optical disk 10 shown in FIG. 1 can be manufactured.

In FIG. 4, the cover film 15 is attached to the adhesive layer 1
Polycarbonate substrate 1 having recording layer 13 via
1 is a manufacturing method in which the photocatalyst layer 16 is formed after being attached to the substrate 1. First, as shown in FIG. 4A, a reflective layer 12 is formed on a polycarbonate substrate 11 on which pregrooves are formed, a recording layer 13 is formed on the upper surface of the reflective layer 12, and a UV curing feeling of, for example, 25 μm is formed. An adhesive layer 14 made of a pressure-sensitive adhesive and a cover film 15 made of a polycarbonate resin having a thickness of 75 μm, for example, are prepared. Of these, the adhesive layer 14 is in a semi-solidified state, and is obtained by cutting a sheet having a top and bottom sandwiched by a release film (not shown) into a predetermined size. Next, as shown in FIG. 4B, the release film of the adhesive layer 14 is peeled off, and the polycarbonate substrate 11 on which the reflective layer 12 is formed and the cover film 15 are bonded together by this adhesive layer 14. Then, as shown in FIG. 4C, the cover film 1
The photocatalyst layer 16 is formed on the substrate 5 by sputtering to have a thickness of 5 nm, for example. In this way, the optical disk 10 shown in FIG. 1 can be manufactured.

The adhesive layer 14 is formed by using the polycarbonate substrate 1 instead of using the above-mentioned semi-solidified sheet.
1 or the cover film 15 may be formed by applying an adhesive.

The thickness of the photocatalyst layer 16 is 5 nm to 200 μm.
It is possible to adopt a wide range of m. In practice, the film thickness of the photocatalyst layer 16 is selected so as to obtain the required activation action and satisfy the desired optical disc standard.

A light source having a wavelength for activating the photocatalyst may be additionally disposed on the incident surface side of the laser light L for reproducing or recording the information on the optical disk or on the opposite side. Good. As a result, the activation by the laser light L and the activation by the light source arranged in an auxiliary manner can be used together to more effectively decompose and remove the dirt and water.

Further, since the above-mentioned material of the photocatalyst layer 16 can be activated in a wide range of visible light region, the catalytic action is exhibited even by light such as sunlight which is not related to the reading and writing of signals of the optical disk. sell. Therefore, the photocatalyst layer may be formed not only on the surface of the optical disk on which the laser light is incident, but also on the surface on the side opposite to the side on which the laser light is incident, that is, the back surface of the optical disk. By thus forming the photocatalyst layer on the back surface of the optical disc as well, it is possible to add the effect of preventing water from adhering to the back surface and the resulting dirt such as dust sticking, and the effect of suppressing the generation of mold. As a result, long-term storage stability can be improved in an optical disk such as a CD (compact disk) whose recording layer is close to the back surface.

The present invention is not limited to the above-mentioned embodiments, and various other configurations can be adopted without departing from the gist of the present invention.

[0045]

According to the present invention described above, by irradiating a laser beam for reproducing or recording information on an optical disk,
It is possible to decompose and remove the dirt adhering to the surface by activating the area exposed to the laser light. This allows
It is possible to decompose and remove organic stains on the surface of an optical disc at low cost without requiring a special configuration. Further, it can be applied regardless of the presence or absence of the cartridge.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram (cross-sectional view) of an optical disc according to an embodiment of the present invention.

2A to 2C are diagrams showing another embodiment of the optical disc of the present invention.

3A to 3C are process diagrams showing one embodiment of a method for manufacturing the optical disc of FIGS.

4A to 4C are process diagrams showing another embodiment of the method for manufacturing the optical disc of FIG.

[Explanation of symbols]

10, 21, 22, 30 Optical disc, 11, 11A,
11B, 31 polycarbonate substrate (disk substrate), 13, 13A, 13B, 32 recording layer, 15 cover film, 16 photocatalyst layer, L 2 laser light

Claims (2)

[Claims] 1. A photocatalyst layer that is photoactive at the wavelength of the laser light is formed on the surface on which the laser light for reproducing or recording information is incident, and the photocatalyst layer is formed of oxygen atoms of titanium oxide. An optical disc comprising a substance in which a part of the atoms is replaced with nitrogen atoms. 2. One of the oxygen atoms is replaced by the nitrogen atom.
The optical disk according to claim 1, wherein 10% is replaced.