JPH08221754A - Medium and method for information recording, and information recording/reproducing method - Google Patents

Abstract

PURPOSE: To obtain an information recording medium, information recording method, etc., which are capable of re-recording. CONSTITUTION: The information recording medium A inserted to the information recorder is positioned at the prescribed position by a recording mechanism system 4. By irradiating with a laser beam 3a from a light emitting part 3, the heated part P is generated in a 1st photothermal conversion layer 15 and the thermal deformation is generated on a hologram forming layer 13 corresponded thereto. As the result, a diffraction grating on this part is destructed. When the diffraction grating is destructed in such a manner, the reflection light in the direction originally to be reflected becomes unobtainable. So, it becomes clear whether the diffraction grating is being destructed or not, by means of detecting the reflection light, thereby, the recording of binary information is attained by the destruction and nondestruction of the diffraction grating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium using a hologram, an information recording method and an information recording / reproducing method.

[0002]

2. Description of the Related Art Hitherto, a hologram using a diffraction grating that reflects irradiation light at a specific angle has been known. This hologram is attached to a card or a product and used for decoration or forgery prevention. It had been.

In recent years, a technique for recording / reproducing information by applying an automatically readable hologram to an information recording medium has been developed. This technology utilizes the optical property that the diffraction grating reflects the irradiation light at a certain angle, irradiates the information recording medium with the irradiation light at a specific angle, and detects the light amount of the reflected light. Is played. In the following, a hologram that can be automatically read is called a machine-readable hologram.

[0004]

By the way, in the conventional information recording medium using the machine-readable hologram, the stamper is pressed to form a diffraction grating, and the information is recorded by this. It was a read-only type information recording medium that can only be rotated. Therefore, it is suitable when mass-producing information recording media having the same information, but when each information recording medium has different information,
It has a drawback that it is not suitable for writing information after production. The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to record different information on each information recording medium and record information after production.

[0005]

In order to solve the above-mentioned problems, in the structure according to claim 1, a reflecting layer for reflecting incident light and a photothermal conversion layer for generating heat by the incident light are provided on the upper surface of the base. , A transmission layer that transmits incident light and a diffraction grating layer having a plurality of diffraction gratings are sequentially stacked, and the photothermal conversion layer is
When the incident light exceeds a predetermined amount, the diffraction grating in the vicinity thereof is destroyed by heat generation.

Further, the structure according to claim 2 is an information recording medium in which a reflective layer for reflecting incident light and a photothermal conversion layer for generating heat by the incident light are sequentially laminated on the upper surface of the substrate. A plurality of diffraction gratings are formed in the photothermal conversion layer.

Further, in the structure according to the third aspect, on the upper surface of the substrate, a reflective layer that reflects incident light, a first photothermal conversion layer that generates heat by the incident light, and a transmissive layer that transmits the incident light. And a second photothermal conversion layer that generates heat by incident light, which are sequentially laminated, and a plurality of diffraction gratings are formed in the second photothermal conversion layer. And

The structure according to claim 4 is characterized in that the reflective layer is formed of a material which is altered by heat generation.

According to a fifth aspect of the present invention, there is provided an information recording method for recording information on the information recording medium according to the first, second or third aspect, in which the information recording medium is irradiated with laser light. The information is recorded by heating the photothermal conversion layer and destroying a predetermined diffraction grating.

According to a sixth aspect of the present invention, there is provided an information recording method for recording information on the information recording medium according to the fourth aspect, in which the information recording medium is irradiated with a laser beam.
It is characterized in that the photothermal conversion layer in a portion corresponding to the information to be recorded is heated to destroy the reflection layer corresponding to a predetermined diffraction grating to record the information.

According to a seventh aspect of the present invention, there is provided an information recording / reproducing method for recording / reproducing information on / from the information recording medium according to the first, second or third aspect, wherein a laser beam is applied to the information recording medium. Irradiate, heat the photothermal conversion layer, destroy the predetermined diffraction grating to record information, irradiate the information recording medium with laser light, and reflect the light reflected by the reflection layer through the predetermined diffraction grating. It is characterized in that the amount of light is detected and information is reproduced based on the detected amount of light.

Further, according to the structure of claim 8, there is provided an information recording / reproducing method for recording / reproducing information on / from the information recording medium according to claim 4, wherein the information recording medium is irradiated with a laser beam, The information is recorded by heating the photothermal conversion layer and destroying the reflection layer corresponding to the predetermined diffraction grating, irradiating the information recording medium with laser light, and reflected by the reflection layer through the predetermined diffraction grating. The light amount of the reflected light is detected, and the information is reproduced based on the detected light amount.

[0013]

In the structure according to the first aspect, the base body functions as a base, and the reflection layer reflects incident light. The photothermal conversion layer generates heat by the incident light, and when the incident light exceeds a predetermined amount,
The diffraction grating near it is destroyed by heat generation. The transmission layer protects the diffraction grating during the manufacturing process. A plurality of diffraction gratings are formed in the diffraction grating layer.

In the structure according to the second aspect, the base body functions as a base, and the reflection layer reflects incident light.
In addition, a plurality of diffraction gratings are formed in the photothermal conversion layer, and the diffraction gratings are destroyed by heat generation.

Further, in the structure according to the third aspect, the base body functions as a base, and the reflection layer reflects incident light.
Further, the first photothermal conversion layer generates heat by the incident light, and the transmission layer protects the diffraction grating in the manufacturing process. Furthermore, a plurality of diffraction gratings are formed in the second photothermal conversion layer, and the diffraction gratings are destroyed by heat generation.

Further, in the structure according to the fourth aspect, the reflective layer is formed of a material which is altered by heat generation.

Further, in the structure according to the fifth aspect, the information recording medium is irradiated with laser light to heat the photothermal conversion layer and destroy the predetermined diffraction grating to record information.

Further, in the structure according to the sixth aspect, the information recording medium is irradiated with the laser beam to heat the portion of the photothermal conversion layer corresponding to the information to be recorded so as to correspond to a predetermined diffraction grating. Information is recorded by destroying the reflective layer.

Further, in the structure according to the seventh aspect, the information recording medium is irradiated with laser light, the photothermal conversion layer thereof is heated, and a predetermined diffraction grating is destroyed to record information, and the laser light is emitted. The information recording medium is irradiated, the light amount of the reflected light reflected by the reflective layer through a predetermined diffraction grating is detected, and information is reproduced based on the detected light amount.

Further, in the structure according to the eighth aspect, the information recording medium is irradiated with laser light to heat the photothermal conversion layer and destroy the information by destroying the reflection layer corresponding to a predetermined diffraction grating. Recording, irradiating the information recording medium with laser light,
The light amount of the reflected light reflected by the reflective layer is detected via a predetermined diffraction grating, and information is reproduced based on the detected light amount.

[0021]

【Example】

1. First Embodiment A. Information Recording Medium First, the configuration of the information recording medium will be described with reference to FIG. FIG. 1 is a plan view of an information recording medium. In the figure, A is an information recording medium, which is composed of a machine-readable hologram 1 and a substrate 2. The machine-readable hologram 1 has square-shaped holograms 101 to 104, in which information is recorded. Further, the base 2 functions as a base of the machine-readable hologram 1.

The machine readable hologram 1 has a structure shown in FIG. In the figure, 12
Is a protective layer, and is a layer provided for the purpose of protecting the information recording medium A from chemical mechanical damage. Then, the protective layer 12 is formed on the lower surface of the base material 11 using a gravure method so as to have a thickness of 1.5 μm under an environment of a drying temperature of 110 degrees. In addition, the composition is an acrylic resin (20
Parts), polyethylene wax (3 parts), polyester resin (7 parts), toluene (20 parts), methyl ethyl ketone (30 parts) and methyl isobutyl ketone (20 parts).

A hologram forming layer 13 is provided with a fine diffraction grating that can be automatically read. Therefore, a material having good embossing moldability and capable of uniform press molding is used for this layer. Then, the hologram forming layer 13 is formed on the lower surface of the protective layer 12 by a gravure method so as to have a thickness of 1.0 μm under an environment of a drying temperature of 110 degrees. Further, the composition is vinyl chloride-
Vinyl acetate copolymer (10 parts), polyurethane resin (2
0 parts), methyl ethyl ketone (35 parts) and toluene (35 parts).

Then, a press plate made of nickel having a fine concavo-convex pattern is heated and pressed at 165 degrees on part or all of the hologram forming layer 13 to form a hologram forming surface made of a relief hologram. This is illustrated in FIG. In the figure, the hologram 101 is in the shape of a square having areas a to d, and the areas a to d reflect incident light of a specific angle at different angles. Also, hologram 1
02 to 104 also have areas e to h, i to 1, m to p, respectively. The areas e, i, and m are the area a and the areas f, j, and n.
Is a region b, regions g, k, o are regions c, and regions h, l,
p is the same diffraction grating as that of the region d.

Next, reference numeral 14 shown in FIG. 2C is a transparent thin film layer which transmits incident light and protects the hologram forming surface in the manufacturing process of the information recording medium A. The transparent thin film layer 14 is formed on the lower surface of the hologram forming layer 13 by vacuum-depositing ZnS having a thickness of 50 nm.

Numeral 15 is a first light-heat conversion layer, which has a function of destroying the hologram forming surface and recording information when heated. The first photothermal conversion layer 15 uses a gravure method and has a thickness of 2.0 μm under an environment of a drying temperature of 110 degrees.
m is formed on the lower surface of the transparent thin film layer 14. And, the composition is a cyanine-based light-heat exchange agent (10
Part), polyester resin (30 parts), methyl ethyl ketone (30 parts), toluene (20 parts) and ethyl acetate (1 part)
0 parts).

Reference numeral 16 is a reflective thin film layer, which is a layer for reflecting incident light. The reflective thin film layer 16 has a thickness of 100.
nm aluminum and 50 nm tin are laminated on the lower surface of the first photothermal conversion layer 15 by a vacuum vapor deposition method.

Next, 17 is an adhesive layer, which has a function of fixing the reflective thin film layer 16 to the substrate 2. The adhesive layer 17 is formed on the lower surface of the reflective thin film layer 16 using a gravure method so as to have a thickness of 2.0 μm under an environment of a drying temperature of 110 degrees. The composition also comprises a vinyl chloride-vinyl acetate copolymer (15 parts), a polyester resin (10 parts), methyl ethyl ketone (40 parts) and toluene (35 parts). In this way, the machine-readable hologram 1 is formed as a thin film having a thickness of approximately 7 μm.

Next, a method of manufacturing the information recording medium A will be described with reference to FIG. In FIG. 1A, B is a hologram sheet (transfer foil), which is formed by forming a base material 11 on the upper surface of the machine-readable hologram 1. In addition, the base material 11
Is made of a polyethylene terephthalate film having a thickness of 25 μm. After fixing the hologram sheet B on the upper surface of the base 2 as shown in FIG.
The base material 11 is peeled off from the hologram sheet B to manufacture the information recording medium A shown in FIG.

B. Information Recording Device Next, the configuration of the information recording device will be described. FIG. 4 is a block diagram of an information recording apparatus for recording predetermined information on the information recording medium A. In the figure, 3 is a light emitting unit, and 150
The semiconductor laser device has a beam diameter of nm and emits laser light having a wavelength of 780 nm. A recording mechanism system 4 conveys the information recording medium A to a predetermined position.
Further, 5 is a recording control means, which is a control signal 5 for controlling the irradiation timing of the light emitting unit 3 based on the recording information aa.
a and a control signal 5b for controlling the operation timing of the recording mechanism system 4 are generated.

The operation of the information recording apparatus will be described with reference to FIG. First, the information recording medium A inserted in the information recording device is positioned at a predetermined position by the recording mechanism system 4. Then, the laser light 3a is emitted from the light emitting unit 3, a heat generating portion P is generated in the first photothermal conversion layer 15, and the hologram forming layer 13 corresponding thereto is thermally deformed.
As a result, the diffraction grating in that portion is destroyed. If the diffraction grating is destroyed in this way, it becomes impossible to obtain reflected light in the direction in which it should be reflected. Therefore, by detecting the reflected light, it can be determined whether or not the diffraction grating is destroyed,
This makes it possible to record binary information by breaking or not breaking the diffraction grating.

Here, since the holograms 101 to 104 are composed of areas a to d, e to h, i to l, and m to p, depending on which area is to be destroyed, 4 holograms are included in one hologram.
It becomes possible to represent bits of information. That is, 16 types of destruction patterns are obtained by the destruction of each area described above, and the numerical information shown in FIG. 6 is represented correspondingly. In addition, in the same figure, the black portion represents the destroyed region.

Now, let us say that the recording information aa in FIG. 4 represents "5A3B", the information recording medium A by the recording mechanism system 4.
The laser beam 3a is irradiated in synchronism with the conveyance of the sheet, and the region c → region d → region e → region g → region i → region m → region n.
→ Destruction is performed in the order of region p. As a result, the hologram forming layer 13 of the information recording medium A becomes as shown in FIG.

C. Information Reproducing Device Next, the configuration of the information reproducing device will be described. FIG. 5 is a block diagram of an information reproducing apparatus for reproducing predetermined information from the information recording medium A. In the figure, reference numeral 21 denotes a light emitting portion, which is used to reproduce information from the information recording medium A.
Irradiate a. Further, 22 to 25 are first to fourth light receiving portions, which photoelectrically convert the reflected light reflected from the information recording medium A and detect the light amount thereof. Therefore, the first to fourth light receiving portions 22 to 24 are provided at predetermined positions corresponding to the respective areas of the holograms 101 to 104.

A reproducing mechanism system 26 conveys the information recording medium A. 27 is a reproduction control means,
Control signal 27a for controlling the irradiation timing of the light emitting unit 3
And a control signal 27b for controlling the operation timing of the recording mechanism system 4. Further, 28 is an information reproducing means, which generates reproduction information bb based on the signals 22a to 25a.

Next, the operation of the information reproducing / reproducing apparatus will be described with reference to FIG. When the information information recording medium A is inserted into the information reproducing apparatus, the reproducing mechanism system 26 conveys the information recording medium A to a predetermined position. Then, the region a of the hologram 101 is irradiated with the laser light 21a from the light emitting unit 21, the reflected light reflected at the specific angle in the region a is photoelectrically converted by the first light receiving unit 22, and a signal indicating the light amount of the reflected light. 22a is generated. Following this, the amount of reflected light from the area b to the area o is sequentially detected.

The information reproducing means 28 then outputs the signal 22a.
25a are respectively compared with a predetermined reference value R, and a binary signal (not shown) representing "1" when the value exceeds the reference value R and "0" when the value falls below the reference value R. Generate each. That is, the binary signal corresponding to the area not destroyed during recording becomes "1", and the binary signal corresponding to the area destroyed during recording becomes "0".

Here, the value "5A3" is recorded on the information recording medium A.
If "B" is recorded, the binary signal corresponding to the areas a to d of the hologram 101 is "1, 1, 0, 0", and the binary signal corresponding to the areas e to h of the hologram 102 is ". 0,1,0,1 ", the binary signal corresponding to the regions i to 1 of the hologram 103 is" 0,1,1,1 ", and the binary signal corresponding to the regions m to p of the hologram 104 is" 0,0,1,0 ". Then, the binary signal obtained in each hologram unit is used as address information, and referring to a ROM (not shown) storing the number information shown in FIG.
Play the number "5A3B".

2. Second Embodiment FIG. 8 shows the structure of the information recording medium in the second embodiment.
In the figure, the information recording medium A in the second embodiment is different from the information recording medium A in the first embodiment in that the hologram forming layer 13, the transparent thin film layer 14 and the first photothermal conversion of the first embodiment are different. Instead of layer 15 (see FIG. 2C),
That is, the second photothermal conversion layer 18 is used. Hereinafter, this point will be described.

The second photothermal conversion layer 18 shown in the figure is formed by press-molding a diffraction grating on the photothermal conversion agent applied to the lower surface of the protective layer 12. The second photothermal conversion layer 18 is formed on the lower surface of the protective layer 12 by a gravure method so as to have a thickness of 1.0 μm under an environment of a drying temperature of 110 degrees. In addition, the composition is composed of a cyanine-based photothermal conversion agent (5 parts) and a vinyl chloride-vinyl acetate copolymer (25 parts).
Parts), polyurethane resin (10 parts), methyl ethyl ketone (30 parts) and toluene (30 parts). The second photothermal conversion layer 18 thus formed has good adhesiveness to the protective layer 12 on its upper surface and the reflective thin film layer 16 on its lower surface.

Then, a nickel press plate having a fine concavo-convex pattern is heated and pressed at 165 degrees on a part or all of the lower surface of the second photothermal conversion layer 18 to form a relief hologram. Therefore, the second photothermal conversion layer 1
8 is a layer that also serves as the hologram forming layer 13 and the first photothermal conversion layer 15 of the first embodiment. In this case, since the diffraction grating is directly formed on the photothermal conversion agent itself, the transparent thin film layer 1
4 is omitted. In addition, the information recording medium A of the second embodiment
Is a hologram sheet B having the base material 11 of the first embodiment.
Is fixed to the base body 2, and then the base material 11 is peeled off to manufacture the same.

Recording and reproduction of information on the information recording medium A of the second embodiment thus obtained are performed by the above-mentioned information recording apparatus and information reproducing apparatus, respectively.
However, since the information recording medium A of the second embodiment does not have the hologram forming layer 13, the operation of the information recording device is different from that of the first embodiment. Therefore, this point will be described with reference to FIG.

In the figure, the laser light 3 is emitted from the light emitting unit 3.
When a is irradiated, a heat generating portion P is generated in the second photothermal conversion layer 18, and the hologram forming surface formed on the lower surface is directly destroyed by thermal deformation. As a result, a broken portion occurs in the diffraction grating of the second photothermal conversion layer 18 corresponding to the recorded information aa, and the information is recorded. As described above, in the second embodiment, since the hologram forming surface made of the diffraction grating is provided in the second light-heat converting layer 18, it is independent of the first light-heat converting layer 15 as in the first embodiment. It is not necessary to provide the hologram forming layer 13, and the information information recording medium A can be simplified.

3. Third Embodiment FIG. 10 shows the structure of the information recording medium in the third embodiment. In the figure, the information recording medium A in this embodiment is shown.
The difference between the information recording medium A and the information recording medium A in the first embodiment is that the hologram forming layer 13 and the first photothermal conversion layer 15 are different.
Instead of (see FIG. 2C), the second photothermal conversion layer 18
And the third photothermal conversion layer 19 is used.
Hereinafter, this point will be described.

The second photothermal conversion layer 18 shown in the figure is formed by press-molding a diffraction grating on the photothermal conversion agent applied to the lower surface of the protective layer 12. The third light-heat conversion layer 19 also functions as a heat-sensitive sensitizing layer that assists the heat generated in the second light-heat conversion layer 18. Then, the third photothermal conversion layer 19 is formed by the gravure method under the environment of a drying temperature of 110 degrees so that the transparent thin film layer 1 has a thickness of 2.0 μm.
4 is formed on the lower surface. The composition is a cyanine-based photothermal conversion agent (5 parts), vinyl chloride-vinyl acetate copolymer (15 parts), polyester resin (10 parts), methyl ethyl ketone (30 parts), toluene (30 parts) and ethyl acetate. (10 copies). The information recording medium A of the third embodiment is manufactured by fixing the hologram sheet B having the base material 11 of the first embodiment on the base body 2 and then peeling the base material 11.

Recording and reproduction of information on the information recording medium A of the third embodiment thus obtained are performed by the above-mentioned information recording apparatus and information reproducing apparatus, respectively.
However, since the information recording medium A of the third embodiment has the second and third photothermal conversion layers 18 and 19, the operation of the information recording apparatus is different from that of the first embodiment. Therefore, this point will be described with reference to FIG.

In the figure, the laser light 3 is emitted from the light emitting unit 3.
When a is irradiated, a heat generating portion P is generated in the second light-heat conversion layer 18 and the third light-heat conversion layer 19, and the hologram formation surface formed on the lower surface of the second light-heat conversion layer 18 moves up and down. It is transformed by the heat from. As a result, the diffraction grating is destroyed and information corresponding to the recorded information aa is recorded. As described above, in the third embodiment, since the third photothermal conversion layer 16 is newly provided and the hologram forming surface composed of the diffraction grating is heated from above and below, the information can be recorded more reliably.

4. Modifications The present invention is not limited to the embodiments described above, and various modifications described below are possible. In each of the above examples, the substrate 11 is described as a 25 μm polyethylene terephthalate film, but it may be a synthetic resin such as polyvinyl chloride, polyester, polo carbonate, polymethylmethacrylate or polyester, natural resin, paper or synthetic paper. Well Further, it may be a complex in which these are combined. Further, the thickness is preferably 4 to 100 μm, but is not particularly specified.

In each of the above embodiments, the protective layer 1
2 also has a function of facilitating peeling from the base material 11. In addition, as a material of the protective layer 12, a thermoplastic resin such as a thermoplastic acrylic resin, a vinyl chloride-butynyl acetate copolymer resin, a cellulosic resin, a chlorinated polypropylene resin, or an epoxy resin, a thermosetting resin, or a radical polymerizable resin. An unsaturated group may be used. Further, in order to prevent mechanical damage from the outside, it is preferable to add a friction resistant agent to the above material. As the anti-friction agent, animal wax, plant wax, mineral wax, natural wax such as petroleum wax, synthetic hydrocarbon wax, aliphatic alcohol wax, aliphatic acid wax, fatty acid ester wax, fatty acid Glycerite wax, hydrogenated wax, synthetic ketone wax, amine wax, amide wax, chlorinated hydrocarbon wax,
It is possible to use synthetic waxes such as synthetic animal waxes and alcohol olefin waxes, Teflon powder, polyethylene powder, inorganic fillers, or organic compounds (zinc stearate) such as metal salts of higher fatty acids.

In the first embodiment, the hologram forming layer 13 may be made of any material as long as it is stable enough to form a hologram image, but the following materials are particularly preferable. For example, polycarbonate resin, polystyrene resin, thermoplastic resin such as polyvinyl chloride resin, unsaturated polyester resin, melamine resin, epoxy resin, urethane (meth) acrylate, polyester (meth), epoxy (meth) acrylate, melamine (meth) Thermosetting resins such as acrylates and triazine (meth) acrylates, polyol-curable urethane resins comprising a polyol component such as polyester polyol, polyether polyol or acrylic polyol and a prepolymer having an isocyanate group. The isocyanate group includes tolylene diisocyanate, xylene diisocyanate and hexamethylene diisocyanate.

In the first and third embodiments, the decorative property can be improved by making the refractive index of the transparent thin film layer 14 higher than that of the hologram forming layer 13 (1.3 to 1.5). In this case, as the material of the transparent thin film layer 14, the inorganic materials shown in Table 1 below may be used.

[0052]

[Table 1]

Further, the transparent thin film layer 14 may be a multi-layer film. For example, even if a plurality of layers having different refractive indexes are appropriately laminated, a high refractive index layer and a low refractive index layer are alternately formed. You may laminate. Further, as a method of forming the transparent thin film layer 14, a spattering method or an ion plating method may be applied instead of the vacuum vapor deposition method. The thickness of the transparent thin film layer 14 is preferably in the range of 10 nm to 1000 nm.

In the first embodiment, the light-heat exchange agent used for the first light-heat conversion layer 15 has been described by taking the cyanine dye as an example. Instead of this, a merocyanine dye or a triphenylmethane dye is used. You may use. Further, as the binder resin, a thermoplastic resin such as a polyester resin, a polyacrylic resin, a polyurethane resin, a polyvinyl chloride resin, a polyvinyl acetate resin or a copolymer thereof can be used, but the binder resin is not limited thereto. Absent.

In each of the above-described embodiments, the material of the reflective thin film layer 16 is silver, gold or titanium oxide (TiN).
X) etc. are also applicable. As the binder resin of the adhesive layer 17, a thermoplastic resin such as a polyester resin, a polyurethane resin, an acrylic resin, a polyvinyl chloride resin, a polyvinyl acetate resin, or a copolymer thereof can be used, but the binder resin is not limited to this. Not something. Further, by using a metal having a low melting point for the reflective thin film layer 16, the reflective thin film layer 16 can also be destroyed and information can be recorded more reliably. That is, the laser light 3 is emitted from the light emitting unit 3.
When a is irradiated, the low melting point metal is melted by heat from the heat generating portion P, bowl-up occurs, and the reflective thin film layer 16 is destroyed. As a result, the reflectance of the irradiation light is reduced during reproduction, and the recorded information can be reproduced reliably.

In the second embodiment, as the light-heat converting agent of the second light-heat converting layer 18, a merocyanine dye or a triphenylmethane dye can be applied instead of the cyanine dye. Further, as the binder of the second photothermal conversion layer 18, a stable substance capable of forming a diffraction grating may be used. In particular, the thermoplastic resin and the heat used for the hologram forming layer 13 in the first embodiment are used. Curable resins are preferred.

In each of the above embodiments, the information recording medium A may be manufactured by sequentially laminating the above layers on the upper surface of the substrate 2.

Further, in each of the above embodiments, the information reproducing apparatus irradiates the laser beam from a single light emitting part, but the light emitting parts corresponding to the four regions forming the square grid diffraction grating. Of course, each may be provided. Further, although four light receiving portions are provided so as to correspond to the respective regions of the diffraction grating, a reflecting mirror may be provided so as to correspond to the respective regions and the light amount of the reflected light may be detected by a single light receiving portion.

[0059]

As described above, according to the first to fifth and seventh aspects, since the photothermal conversion layer that destroys the diffraction grating by heat generation is provided, the information is recorded after the information recording medium is produced. You can

According to the first or third aspect of the invention, since the protective layer is provided, the diffraction grating can be protected from solvent attack in the manufacturing process of the information recording medium.

According to the second aspect of the invention, since a plurality of diffraction gratings are directly formed on the photothermal conversion layer, it is not necessary to separately provide a diffraction grating layer, and the structure can be simplified.

According to the third to fifth and seventh aspects, since the first and second photothermal conversion layers are provided, the diffraction grating can be heated from the upper and lower surfaces to reliably record information.

Further, according to the structure of claim 4, 6 or 8, since the reflective layer is formed of a material which is altered by heat generation, the heat generation of the photothermal conversion layer can destroy the reflection layer. , Information can be recorded more reliably along with the destruction of the diffraction grating.

According to the seventh or eighth aspect of the invention, it is possible to detect the light quantity of the reflected light reflected by the predetermined diffraction grating and reproduce the information based on the detected light quantity.

[Brief description of drawings]

FIG. 1 is a plan view of an information recording medium.

FIG. 2 is a conceptual diagram for explaining a manufacturing process of the information recording medium in the first embodiment.

FIG. 3 is a plan view of a hologram forming layer.

FIG. 4 is a block diagram of the information recording apparatus of the first embodiment.

FIG. 5 is a conceptual diagram showing a destruction pattern of a hologram.

FIG. 6 is a plan view of a recorded hologram forming layer.

FIG. 7 is a block diagram of the information reproducing apparatus in the first embodiment.

FIG. 8 is a cross-sectional view of the information recording medium of the second embodiment.

FIG. 9 is a block diagram of an information recording device of a second embodiment.

FIG. 10 is a sectional view of an information recording medium in a third embodiment.

FIG. 11 is a block diagram of an information recording device of a third embodiment.

[Explanation of symbols]

 2 Substrate A Information recording medium 13 Hologram forming layer (diffraction grating layer) 14 Transparent thin film layer (transmissive layer) 15 First photothermal conversion layer (photothermal conversion layer) 16 Reflective thin film layer (reflective layer) 18 Second photothermal Conversion layer 19 Third light-heat conversion layer (first light-heat conversion layer)

Claims (8)

[Claims] 1. A reflective layer that reflects incident light, a photothermal conversion layer that generates heat by the incident light, a transmissive layer that transmits the incident light, and a diffraction grating layer having a plurality of diffraction gratings on the upper surface of the substrate. An information recording medium characterized in that, when the incident light exceeds a predetermined amount, the diffraction grating in the vicinity of the photothermal conversion layer is destroyed by heat generation. 2. An information recording medium in which a reflective layer that reflects incident light and a photothermal conversion layer that generates heat by incident light are sequentially laminated on the upper surface of a substrate, wherein the photothermal conversion layer has a plurality of layers. An information recording medium having a diffraction grating formed therein. 3. A reflective layer that reflects incident light, a first photothermal conversion layer that generates heat by the incident light, a transmissive layer that transmits the incident light, and a second photoheat that generates heat by the incident light on the upper surface of the substrate. An information recording medium comprising a conversion layer and a conversion layer, which are sequentially laminated, wherein a plurality of diffraction gratings are formed in the second photothermal conversion layer. 4. The information recording medium according to claim 1, 2 or 3, wherein the reflective layer is formed of a material which is altered by heat generation. 5. An information recording method for recording information on the information recording medium according to claim 1, 2, or 3, wherein the information recording medium is irradiated with a laser beam to heat the photothermal conversion layer, and a predetermined time is applied. An information recording method characterized by destroying a diffraction grating and recording information. 6. An information recording method for recording information on the information recording medium according to claim 4, wherein the information recording medium is irradiated with laser light to heat a portion of the photothermal conversion layer corresponding to the information to be recorded. Then, the information recording method is characterized in that the reflection layer corresponding to a predetermined diffraction grating is destroyed to record information. 7. An information recording / reproducing method for recording / reproducing information on / from the information recording medium according to claim 1, wherein the information recording medium is irradiated with laser light to heat the photothermal conversion layer, The information is recorded by destroying the diffraction grating of, laser light is irradiated to the information recording medium, and the light amount of the reflected light reflected by the reflection layer through the predetermined diffraction grating is detected,
An information recording / reproducing method characterized in that information is reproduced based on the detected light amount. 8. An information recording / reproducing method for recording / reproducing information on / from the information recording medium according to claim 4, wherein the information recording medium is irradiated with a laser beam and a portion of the photothermal conversion layer corresponding to the information to be recorded. The information is recorded by destroying the reflective layer corresponding to the predetermined diffraction grating by irradiating the information recording medium with laser light, and the reflection reflected by the reflective layer through the predetermined diffraction grating. Detects the amount of light,
An information recording / reproducing method characterized in that information is reproduced based on the detected light amount.