JP3440334B2 - Recording medium, usage of recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to an identification card, credit card, bank card, check, passbook, passport,
A suitable recording medium used as a prepaid card, a pass ticket, an admission ticket, a commuter pass, and the like, a method of using the recording medium for accurately determining whether this recording medium is a forged one, and a recording medium Regarding the reader.

[0002]

2. Description of the Related Art A thermoreversible recording layer capable of reversibly recording and erasing information by heating is disclosed, for example, in Japanese Patent Laid-Open No.
There are technical means described in JP-A-4-119377, JP-A-55-154198 and the like, and as an information recording card in which a thermoreversible recording layer is provided on a support (base material) or a magnetic recording layer. Japanese Utility Model Publication No. 3-37987 is known.

On the other hand, a card having a diffraction grating or a hologram provided on a support (base material) is disclosed in JP-A-59-8.
Japanese Patent No. 8780 and Japanese Patent Laid-Open No. 61-292181 are known.

[0004]

By the way, regardless of whether it is a transmission type or a reflection type, the diffraction grating or hologram formed on the base material becomes very conspicuous, and if the diffraction grating or hologram can be forged, the card can be forged. It has become a situation. Since the diffraction grating and the hologram are characterized by diffracting incident light to reproduce information, it has been impossible to conceal by providing a concealing layer that does not transmit light. Also, due to the recording method of the diffraction grating and hologram, if individual information is to be recorded as a diffraction grating or hologram, it is necessary to take a photograph or make an original plate each time, and it is not worth the production cost. It was

Under the above circumstances, the present invention has an object to provide a recording medium capable of greatly improving security, a method of using the recording medium, and a reading device thereof.

[0006]

In order to achieve the above-mentioned object, the recording medium of the present invention has an optical diffraction recording layer on which a structure for diffracting incident light is recorded. Transparent-opaque provided directly on the optical diffraction recording layer
Optical properties consisting of the a thermoreversible recording layer reversibly changes
And the optical diffraction recording layer, the thermoreversible recording layer
When transparent, it is optically readable and
Optically unreadable when the reversible recording layer is opaque
It is possible that the transparent-opaque state is heated.
Are partially formed by.

The optical diffraction recording layer may be a diffraction grating or a hologram.

Further, the structure for diffracting the incident light may be divided into a plurality of regions, and the structure for diffracting a plurality of different incident lights may be recorded in the divided regions.

In order to achieve the above-mentioned object, the method of using the recording medium of the present invention is such that the thermoreversible recording layer of the recording medium is partially heated so that the thermoreversible recording layer is partially transparent. After the state, the light is incident on the optical diffraction recording layer of the recording medium, and the diffracted light from the optical diffraction recording layer is read.

In this case, light is made incident on the optical diffraction recording layer of the recording medium, the diffracted light from the optical diffraction recording layer is read, and then the thermoreversible recording layer is heated again to reheat the thermoreversible recording layer. You may return to the original state.

[0011]

[0012]

In the recording medium of the present invention, the substrate, the optical diffraction recording layer and the thermoreversible recording layer are laminated in this order. Therefore, by heating the thermoreversible recording layer before reading, a partially transparent state is obtained. Tosu
To record information, read the record,
From the desired partial transparency of the window, or can Tsu read the information recorded on the optical diffraction recording layer thereunder.

In addition, if the optical diffraction recording layer has a structure in which a plurality of different incident lights are diffracted in a plurality of divided areas, it is thermally reversible by partially heating the thermoreversible recording layer. The partially transparent state of the recording layer can also be read.

In the method of use of the present invention, after the thermoreversible recording layer is heated to be in a transparent state, light is made incident and the diffracted light from the optical diffraction recording layer is read, so that the thermoreversible recording layer in the transparent state is obtained. The information of the optical diffraction recording layer can be read through.

In this case, the thermoreversible recording layer is heated again,
By returning to the original state again, the reading procedure and the like can be hidden.

The reading device used in the present invention comprises heating means for heating the thermoreversible recording layer, light irradiation means for irradiating the light diffraction recording layer with incident light, and light reading for reading diffracted light from the light diffraction recording layer. Since it has the means, all the reading operations can be performed in the apparatus, and the reading procedure is not known to an external person.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a first embodiment of a recording medium of the present invention, which is a recording medium 1 in which an optical diffraction recording layer 3, a thermoreversible recording layer 4, and a coloring layer 5 are laminated on a substrate 2 . .

The substrate 2 is made of paper, synthetic resin, metal, etc. alone, laminated, or according to the purpose of use of the recording medium, or
A sheet, a film, or a booklet-shaped material is used as a material obtained by mixing the materials, and examples thereof include cards, securities, and cash vouchers. The thickness of the substrate 2 is selected according to the purpose of use of the recording medium.

The optical diffraction recording layer 3 can be used in both a flat type and a volume type information recording form, and as a flat type form in which information is recorded as an uneven surface, an object light and Relief holograms or relief diffraction gratings in which the intensity distribution of light of interference fringes due to light interference with the reference light is recorded in an uneven pattern can be used, and Fresnel holograms, Fraunhofer holograms, image holograms, and other holograms, and those Color holograms using the principle, computer holograms, hologram displays, multiplex holograms, holographic stereograms, rainbow holograms that can reproduce white light, and holographic diffraction gratings that use hologram recording means are also available. Mechanically using a drawing device By creating a diffraction grating, calculations can be mentioned such as any of the diffracted light is obtained hologram or diffraction grating based on, it may be recorded in a single or multiple. These holograms or diffraction gratings are generally of a transmissive type (the incident side of the illumination light and the observer's observation side are opposite sides of the hologram or diffraction grating with the hologram light or diffraction grating sandwiched between them), and a reflective layer is formed on the surface having an uneven pattern. By providing it, it becomes a reflection type (the incidence side of the illumination light and the observation side of the observer are the same side with respect to the hologram or diffraction grating).

As a volume type recording form by the laminated interference fringes due to the change of the refractive index distribution, there is a Lippmann hologram in which the interference fringes of the object light and the reference light are recorded with the photosensitive material sandwiched therebetween. Since interference fringes are recorded in the thickness direction of the photosensitive material, wavelength selectivity is high, and when white light is incident, only the light of a specific wavelength is diffracted, the recorded information is reproduced, and it can be observed from the incident direction of white light. . Light having a wavelength other than the characteristic wavelength is transmitted without being diffracted.

When the light-diffraction recording layer 3 is of a flat type, the structure for diffracting light is composed of a relief layer 37 formed as an uneven surface and a reflective layer 38 formed on the uneven surface of the relief layer 37. ing. Such an uneven surface is a relief hologram or relief diffraction grating obtained by temporarily expressing the hologram or diffraction grating in the form of unevenness by taking an image by using a photosensitive resin, a thermoplastic, or the like. By molding a hologram or relief diffraction grating by plating or the like to create a mold or resin mold, the relief hologram or relief diffraction grating can be mass-produced by a molding method for a synthetic resin.

Examples of the moldable synthetic resin include the following. Thermoplastic resin such as polyvinyl chloride, acrylic (eg, MMA), cured of thermosetting resin such as unsaturated polyester, urethane (meth) acrylate, or the above thermoplastic resin and thermosetting resin A mixture, an electron beam curable resin having a radical polymerizable unsaturated group, an ultraviolet ray curable resin obtained by further adding a sensitizer to the electron beam curable resin, and the like can be used.
The relief layer has a thickness of about 0.4 to 4 μm, preferably 1 to 2 μm.

As the reflective layer 38, one that gives the uneven surface of the relief layer 37 reflectivity is used. Specifically, A
single metal such as 1, Cr, Ni, Ag, Sb ₂ S ₃ ,
A metal compound having a refractive index higher than that of the resin forming the relief layer 37, such as TiO ₂ or ZnS, is used. In addition, LiF, MgF ₂ , 3NaF · AlF ₃
A material having a refractive index smaller than that of the relief layer 37 such as CuCl, GaAs, BaTiO ₃ or a transparent strong derivative having a refractive index larger than that of the relief layer 37 such as CuCl, GaAs, or BaTiO ₃ can be similarly used.
A transparent synthetic resin layer having a refractive index different from that of the relief layer 37 such as polychlorotrifluoro may be used as the reflection layer 38. The film thickness may be a transparent region of the material forming the reflective layer 38, but normally 10 to 1000 Å is preferable. As a method of forming the reflection layer 38 on the uneven surface of the relief layer 37, a general thin film forming means such as a vacuum deposition method, a sputtering method, a reactive sputtering method, an ion plating method, or a material of the reflection layer 38 is a synthetic resin. If so, a general coating method can be adopted. The material of the reflective layer 38 has a refractive index of 0.3 than that of the relief layer 37.
It is preferable that they are different from each other, more preferably 0.5 or more. According to the experiments conducted by the present inventors, it is found that the difference of 1.0 or more is optimal.

When the optical diffraction recording layer 3 is a volume type such as a Lippmann hologram which causes a phase difference in incident light due to laminated interference fringes due to a change in the refractive index distribution, the resin layer is
It consists of a silver salt photographic film, dichromated gelatin, a photopolymer, or a film coated with them.When object light is incident from one side of such an optical recording material and reference light is incident from the other side, the optical recording material Interference fringes having a transmittance distribution or a refractive index distribution at specific intervals are recorded in the thickness direction. In any case, the optical diffraction recording layer 3 preferably has resistance to heat, pressure, electric field, etc. applied to the thermoreversible recording layer 4. For example, an ionizing radiation curable resin such as electron beam or ultraviolet ray is used. It is also possible to make the optical diffraction recording layer 3 resistant by increasing the glass transition point of the resin forming the optical diffraction recording layer 3.

The thermoreversible recording layer 4 repeatedly performs recording and erasing on the thermoreversible recording layer 4 depending on the amount of energy to be applied, for example, by reversible change between a transparent state and an opaque state. It has the property of being able to. Specific examples of the thermoreversible recording layer 4 include a resin layer in which a fatty acid is dispersed in a polymer compound, a resin layer utilizing a phase change of the polymer compound, and a resin in which liquid crystal molecules are dispersed in a polymer liquid crystal. Layers are used. It is particularly preferable that the hiding property in the opaque state is high and the light scattering property in the transparent state is small. In particular, the light diffractive recording layer 3 under the thermoreversible recording layer 4 is particularly preferable.
In order to read the information recorded in, it is desirable that the haze degree (cloud value) is 20% or less in the transparent state.
% Or less is preferable.

The thermoreversible recording layer 4 composed of a resin layer in which fatty acid is dispersed in a polymer compound is used for reversing recording and erasing of the recording between a transparent state and an opaque state of the thermoreversible recording layer 4. It is known that it has a property that it can be repeatedly carried out depending on changes, and a matrix material made of at least one resin, for example, a vinyl chloride resin such as a polyvinyl chloride / vinyl acetate copolymer, polyvinylidene chloride. Vinylidene chloride resin, ester resin, acrylic resin, methacrylic resin, urethane resin, phenol resin, silicon resin, melamine resin, epoxy resin, aryl resin, amide resin, and the like From polymers, modified products, and mixtures thereof, and at least one aliphatic monocarboxylic acid and / or aliphatic dicarboxylic acid That higher fatty acids such as caprylic acid,
Pelargonic acid, capric acid, undecyl acid, lauric acid, tridecylic acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heneicosanoic acid, heptacosanoic acid , Saturated fatty acids such as montanic acid, melissic acid, laxeric acid, acrylic acid, crotonic acid, isocrotonic acid, hexadecenoic acid, heptadecenoic acid, undecylenic acid, oleic acid, octadecenoic acid, elaidic acid, cetrain acid, erucic acid, eleostearic acid Unsaturated fatty acids such as acids, brassic acid, sorbic acid, propiolic acid, stearolic acid, oxalic acid,
Malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, mazelaic acid, sebacic acid, eicosane diacid, dodecane diacid, maleic acid, fumaric acid, and aliphatic dicarboxylic acids such as brassylic acid are used. .

The transparentization temperature range of the thermoreversible recording layer 4 made of a resin layer in which fatty acid is dispersed in a polymer compound is widened,
In addition, an organic low molecular weight compound having a polyoxyethylene chain can be added to the reversible recording layer for the purpose of increasing the contrast, which is the ratio of the transparent state to the opaque state. Polyoxyethylene fatty acid ester represented, Polyoxyethylene alkyl ether represented by Chemical formula 3, Polyoxyethylene alkylphenyl ether represented by Chemical formula 4, Polyoxyethylene sorbitan alkyl ester represented by Chemical formula 5 The polyoxyethylene alkylamines represented by Chemical formula 6 can be used.

[0028]

[Chemical 1]

[0029]

[Chemical 2]

[0030]

[Chemical 3]

[0031]

[Chemical 4]

[0032]

[Chemical 5]

[0033]

[Chemical 6]

When selecting the organic low molecular weight compound having the polyoxyethylene chain, a suitable one should be selected in combination with the aliphatic monocarboxylic acid and / or the aliphatic dicarboxylic acid used in combination. desirable.
For example, in a system of behenic acid / stearic acid, polyoxyethylene / alkyl phenyl ether or the like is preferable, and in a system of eicosane / 2 / acid / stearic acid, polyoxyethylene / sorbitan alkyl listel or the like is preferable. Of course, even if it is not such a specific combination, by mixing the organic low molecular weight compound having the polyoxyethylene chain, the transparency temperature range can be widened, and the transparency at the time of transparency and the opacity at the time of clouding can be improved. The thermoreversible recording layer 4 having a sufficient contrast, which is a ratio with the property, can be obtained.

The mixing amount of the organic low molecular weight compound having a polyoxyethylene chain is 50 to 500% by weight, preferably about 50 to 200% by weight, based on the total weight of the aliphatic monocarboxylic acid and the aliphatic dicarboxylic acid. Is. Based on the total weight of the aliphatic monocarboxylic acid and the aliphatic dicarboxylic acid, the amount of the organic low-molecular compound having a polyoxyethylene chain is 5
If it is less than 0% by weight, the improvement effect of the addition by the organic low molecular weight compound cannot be measured, and the desired characteristics cannot be obtained. When it exceeds 500% by weight,
The reversibility of recording / erasing due to heating in the reversible recording layer 4 is impaired. Generally, the mixing amount of the organic low molecular weight compound having a polyoxyethylene chain is based on the total weight of the aliphatic monocarboxylic acid and the aliphatic dicarboxylic acid,
It is desirable to mix the same amount or more.

The thermoreversible recording layer 4 made of a resin layer utilizing the phase change of the polymer compound changes the optical characteristics such as the refractive index and the transmittance due to the reversible change of the crystalline or amorphous state of the polymer compound. are those recorded by using obtained, for example _{[- {- S- (C 6} H 4) -S-CH 2 -CH 2 -
_{(C 6 H 4) -CH 2} -CH 2} n -] poly (1,4-benzenedithiol -CO-1,4-divinylbenzene) displayed in, the amorphous state transparent (light transmittance 91 %
Above) has a high refractive index (1.81), becomes opaque (light transmittance of less than 1%) in a crystalline state, and has a thickness of 0.1 to 0.5.
When a thin film layer having a thickness of μm is used as a recording layer, it becomes transparent after heat recording at 170 ° C. for 1 to 2 seconds.
It becomes opaque again when heated for 0 to 30 minutes, and recording and erasing of the record on the reversible recording layer 4 can be reversibly and repeatedly performed by utilizing this mechanism.

The thermoreversible recording layer 4 consisting of a resin layer in which liquid crystal is dispersed in a polymer compound is formed from a composite film layer of a polymer substance / liquid crystal substance containing a polymer substance having a film-forming performance and a liquid crystal substance. In general, it is formed as a composite film layer containing 10 to 500 parts by weight of a liquid crystal substance with respect to 100 parts by weight of a polymer substance having film forming performance.

The composite film layer composed of a polymer substance / liquid crystal substance containing a polymer substance having film forming performance and a liquid crystal substance is
A composite film layer in which a liquid crystal substance is substantially uniformly dispersed in a polymer substance having film-forming performance by a method such as a microencapsulation method, a solvent vapor deposition method, or a suspension polymerization method. The layer has recording properties and properties that allow the recorded information to be erased.

In the composite film layer composed of the polymer substance / liquid crystal substance, the polymer substance preferably has good film-forming ability and heat resistance, for example, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer. Vinyl chloride resin such as polyvinylidene chloride resin such as polyvinylidene chloride
Polyester resin, polyamide resin, polyacrylate, polymethacrylate, acrylic resin such as acrylate / methacrylate copolymer, polyurethane resin, polyvinyl alcohol resin and the like are used. Also,
As the liquid crystal material, nematic liquid crystal, smectic liquid crystal having a memory property, or a mixture thereof can be used, and specifically, BH of Pool, UK.
"Smectic A phase material S2", commercially available from DHD Chemical (BHD Chemical), or E.M. of Darmstadt, Germany. Merck Chemicals (E.
K commercially available from Merck Chemicals)
24, K30, K36, ZLI1840, CB15, etc. may be used.

In the composite film phase composed of a polymer substance and a liquid crystal substance having film forming performance, if the liquid crystal substance is less than 10 parts by weight with respect to 100 parts by weight of the polymer substance, the recording sensitivity in the composite film layer becomes high. It tends to be low, and clear recording cannot be obtained. Further, when the amount of the liquid crystal material exceeds 500 parts by weight with respect to 100 parts by weight of the polymer material, the amount of liquid crystal leaching to the surface of the composite film layer increases, so that the surface of the composite film layer may be exposed. It tends to be difficult to form a protective resin layer. Therefore, in the composite film layer of the polymer substance / liquid crystal substance having film forming performance, the liquid crystal substance 10 to 50 is added to 100 parts by weight of the polymer substance having film forming performance.
It is preferable to use 0 part by weight, more preferably 50 parts by weight.
About 200 parts by weight of liquid crystal material is used.

Further, in the composite film layer formed of the polymer substance and the liquid crystal substance, dichroic dye molecules matching the molecules of the liquid crystal substance in the composite film layer and having the same optical function as the liquid crystal substance are provided. By including it, the color of the recording portion can be made more clear. Examples of the dichroic dye molecule include Indole Blue, Sudan Black B, Sudan 3, Sudan 2, and E.I. Merck Chemicals (E. Mer
D-3 commercially available from K Chemicals)
7, D-43, D-85 and the like can be used.

The thermoreversible recording layer 4 composed of a composite film layer of a polymer substance and a liquid crystal substance containing a polymer substance having a film-forming property and a liquid crystal substance has a thermoreversible recording layer 4 having an electric field due to, for example, corona charging. The liquid crystal molecules in the liquid crystal particles dispersed in the composite film layer of the polymer substance and the liquid crystal substance in the thermoreversible recording layer 4 are aligned in the same direction, and the refractive indices of the polymer substance and the liquid crystal substance are passed. , The composite membrane layer is in a transparent state. When the thermoreversible recording layer 4 in this state is heated, the alignment of the liquid crystal molecules in the liquid crystal particles dispersed in the composite film layer of the polymer substance and the liquid crystal substance becomes random, and the polymer substance and the liquid crystal substance are combined. Due to the difference in the refractive index, only the heat-treated portion is visually recognized as an opaque turbid state from the outside. Therefore, when the thermoreversible recording layer 4 is again passed through the electric field, the molecules of the polymer substance and the liquid crystal substance in the composite film layer are aligned in the same direction. When the thermoreversible recording layer 4 is recorded and erased by repeating the reversible change between the transparent state and the opaque state of the thermoreversible recording layer 4, recording and erasing of the recording can be repeated. it can.

The thermoreversible recording layer 4 is formed on the base material 2 by, for example, a gravure coating method. In addition,
The thermoreversible recording layer 4 may be formed so as to cover only the optical diffraction recording layer 3, or may be formed so as to cover the entire surface of the optical diffraction recording layer 3 and the surface of the substrate 2. Good.

The coloring layer 5 is provided as necessary, and particularly when reading the information recorded in the optical diffraction recording layer 3 with infrared light, the coloring layer 5 is formed by using a dye that transmits infrared light.
With the above constitution, the thermoreversible recording layer 4 can more effectively conceal the optical diffraction recording layer 3 from visual observation.

As the coloring layer 5, a cellulose derivative such as ethyl cellulose, ethyl hydroxyethyl cellulose, cellulose acetate propionate or cellulose acetate, a styrene resin such as polystyrene or poly-α-methylstyrene or a styrene copolymer resin, polymethacrylic acid. Acrylic resin or methacrylic resin homo or copolymer such as methyl, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate, rosin, rosin-modified maleic acid resin, rosin-modified phenolic resin, rosin ester resin such as polymerized rosin , Polyvinyl acetate resin, coumarone resin, vinyltoluene resin, vinyl chloride resin, polyester resin, polyurethane resin, butyral resin and the like, as a dye that transmits infrared light, for example, S Red GP, Macrol
ex Red Violet R, Ceres Red
7B, Samaron Red HBSL, Reso
lin Red F3BS (above, red dye), Holon Brilliant Yellow 6GL, PTY-52, Macrolex Yellow 6G (above, yellow dye), Kayaset Blue 714, Waxolin Blue AP-FW, Holon Brilliant Blue SR, MS. Various pigments and dyes that transmit infrared light and do not transmit visible light such as Blue 100 (above, blue dye) are added, and if necessary, plasticizer, stabilizer, wax, grease, desiccant, drying aid After adding a curing agent, a curing agent, a thickener, a dispersant, using a paint or ink that is sufficiently kneaded with a solvent or a diluent, a usual gravure method, a roll method, a knife edge method, an offset method, etc. It can be formed on a desired portion by a coating method or a printing method. The colored layer 5 may be formed of a single color, or may be formed of a desired picture, character, tint block, pattern or the like by using dyes of a plurality of colors.

Next, FIG. 2 is a diagram showing a usage state of the first embodiment of the recording medium of the present invention. The card-shaped recording medium 1 shown in this FIG.
An optical diffraction recording layer 3 formed of a diffraction grating having a substantially uniform grating direction and a grating depth is formed, and a thermoreversible recording layer 4 is formed on the entire surface of the optical diffraction recording layer 3. . Further, a magnetic recording layer 6 is provided on the other portion of the base material 2, and information capable of individually identifying the cardholder is recorded as binary information on the magnetic recording layer 6 by a known magnetic recording method. Has been done.

First, the information recorded on the magnetic recording layer 6 is read by using a magnetic head (not shown), and the thermoreversible recording layer is read based on the read information specific to the cardholder, such as an account number. 2 is partially heated by a thermal head (not shown) at 0.2 mJ / dot to make the desired portion transparent, and the recording medium 1 shown in FIG.
Set to the state shown in.

Next, monochromatic light is emitted from the light source 11 made of a semiconductor laser to the optical diffraction recording layer 3 and the thermoreversible recording layer 4 of the recording medium 1. The monochromatic light applied to the transparent portion of the thermoreversible recording layer 4 reaches the optical diffraction recording layer 3,
The light is diffracted in a diffraction direction based on the incident direction depending on the grating spacing, the grating direction, and the grating depth of the diffraction grating of the optical diffraction recording layer 3, and is incident on the optical sensor 12 such as a photosensor with a predetermined intensity. The monochromatic light emitted to the opaque state portion of the thermoreversible recording layer 4 is scattered in multiple directions on the surface of the thermoreversible recording layer 4, and the amount of scattered light reaching the optical sensor 12 is very small. Therefore, by setting a threshold value for the received light intensity of the optical sensor, it is possible to determine whether the incident light is the light diffracted by the optical diffraction recording layer 3 or the light scattered by the thermoreversible recording layer 4. Further, the information recorded on the thermoreversible recording layer 4 by the thermal head is moved by moving the light source 11 and the optical sensor 12 in the direction of the arrow with respect to the recording medium 1 while keeping the spatial relative distance between them. Can be read.

By comparing the information read as the diffracted light with the information recorded on the magnetic recording layer 6, the authenticity of the card can be determined. After the card is determined to be authentic, the thermoreversible recording layer 4 is heated again by the thermal head at 0.5 mJ / dot to make the entire thermoreversible recording layer 4 in an opaque state, thereby performing optical diffraction recording. Conceal layer 3 and return to owner.

FIG. 3 is a diagram showing the usage state of the second embodiment of the recording medium of the present invention. In the card-shaped recording medium 1 shown in FIG. 3, an optical diffraction recording layer 3 made of four different Fresnel holograms in which binarized information is recorded as a bar is formed on a card-shaped substrate 2. Furthermore, over the entire surface of the optical diffraction recording layer 3,
A thermoreversible recording layer 4 is formed. Further, an optical recording layer 7 in which bit information is recorded by binarized unevenness is provided on the other portion of the base material 2. The optical recording layer 6 is provided.
The cardholder information is recorded by a known optical recording method as information encrypted based on the information recorded in the hologram selected from the four Fresnel holograms.

First, based on the personal identification number input by the card holder, the thermoreversible recording layer 4 is partially heated with a thermal head (not shown) at 0.2 mJ / dot,
The thermoreversible recording layer 3 on the Fresnel holograms 31, 33 and 34 is brought into the transparent state, and the recording medium 1 is brought into the state shown in FIG.

Next, monochromatic light is emitted from the light source 11 made of a semiconductor laser to generate Fresnel holograms 31 and 3 of the recording medium 1.
Irradiation is performed on the area where 2, 33, and 34 are formed. The monochromatic light radiated to the transparent portion of the thermoreversible recording layer 4 reaches the optical diffraction recording layer 3 and is positioned at a position based on the incident direction of the monochromatic light depending on the imaging conditions of the Fresnel hologram of the optical diffraction recording layer 3. The bar pattern is imaged, enters a photosensor such as a line sensor (not shown) with a predetermined intensity, and the monochromatic light emitted to the opaque state portion of the thermoreversible recording layer 4 is the surface of the thermoreversible recording layer 4. Is scattered in many directions, and the amount of scattered light that reaches the optical sensor is very small. Therefore, by setting a threshold value for the received light intensity of the optical sensor, it is possible to determine whether the incident light is the light imaged by the optical diffraction recording layer 3 or the light scattered by the thermoreversible recording layer 4. Further, by moving the light source 11 and the optical sensor in the direction of the arrow in the figure with respect to the recording medium 1 while maintaining the spatial relative distance between them, the thermoreversible recording layer 4 was made transparent by the thermal head. It is possible to read the information of different bar patterns recorded in the Fresnel hologram of the other part.

After the information recorded in the selected Fresnel hologram is stored in the storage element of the reading device of the recording medium 1 as an encryption key, the entire thermal reversible recording layer 4 is again recorded by the thermal head. 0.5 mJ / dot
The thermoreversible recording layer 4 is made opaque by heating at. Further, the information of the cardholder can be read by inversely converting the encrypted information read from the optical recording layer 7 using the read head using the stored encryption key.

Although the embodiments of the recording medium, the method of using the recording medium, and the reading device of the recording medium according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and the gist of the present invention is not limited thereto. Various modifications are possible without departing from the above. For example, although the magnetic recording layer has been described in the example of FIG. 2, the information recording layer by printing or a semiconductor memory element may be the same, and the optical diffraction recording layer is adhered on the base material. The structure is not limited to the recording medium, and a light diffractive recording layer may be formed by forming a structure for diffracting light on a substrate having reflectivity and forming a part of the substrate on which the structure for diffracting light is formed. Further, a thermoreversible recording layer may be provided below the optical diffraction recording layer, a magnetic recording layer may be provided between the optical diffraction recording layer and the thermoreversible recording layer, and the optical diffraction recording layer and the thermoreversible recording layer may be provided. The anti-counterfeiting effect can be further enhanced by transferring or adhering the present recording medium including and in the form of a label or a transfer foil to an optical card, a memory card, a contact or non-contact type IC card, or the like. The illumination area (spot diameter) when the light from the light source is incident on the optical diffraction recording layer does not necessarily have to be limited to one unit of the transparent area. The use of diffracted light further enhances the forgery prevention property. It is also possible to form a recording medium having a partially reversible thermoreversible recording layer, read the diffracted light, and then discharge another portion by heating to hide the reading procedure. You can also display the usage history. Furthermore, by overheating the thermoreversible recording layer, by hiding the optical diffraction recording layer in an irreversible opaque state, it is possible to record reduction information on a prepaid card, etc. Can be read out from the optical diffraction recording layer which is not.

The specific structure of the present invention will be described below based on embodiments. As shown in FIG. 4, a supporting sheet 35 made of polyethylene terephthalate having a thickness of 25 μm
A composition for the peelable protective layer 36 having the following composition was formed in a thickness of 0.5 μm by a gravure coating method. Cellulose acetate resin ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 5 parts by weight Methanol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 25 parts by weight Methyl ethyl ketone ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 45 parts by weight Toluene ・ ・ ・ ・ ・ ・ ・ ・ 25 parts by weight Methylol melamine resin ........ 0.5 parts by weight paratoluene sulfonic acid ........ 0.05 parts by weight

Next, the peelable protective layer 36 was coated with the following composition for the relief layer 37 to a thickness of 2.5 μm. Acrylic resin: 40 parts by weight Melamine resin: 10 parts by weight Anone: 50 parts by weight Methylethylketone: 50 parts by weight Arylalkylketone ..... 3 parts by weight

A mold provided with eight diffraction gratings 3a to 3h having different grating intervals or directions is used as the relief layer 3
After making it adhere to 7 and passing the position of 10 cm under a 80 W / cm mercury lamp from the support sheet side at a speed of 2 / min to cure the relief layer 37, the mold was peeled from the relief layer 37. Aluminum is formed to a thickness of 300 Å on the uneven surface of the relief layer 37 by a vacuum vapor deposition method to form a reflection layer 38.
And

Further, a heat seal layer 39 made of the following composition was formed on the reflective layer 38 to prepare the transfer sheet shown in FIG. Vinyl chloride vinyl acetate copolymer resin: 20 parts by weight Acrylic resin: 10 parts by weight Ethyl acetate: 20 parts by weight Toluene: 50 parts by weight

A heat-sealing layer 3 of this transfer sheet was formed on a card-shaped substrate made of polyvinyl chloride having a thickness of 0.76 mm.
9 side was contacted, the support sheet 35 was heated from the support sheet 35 side at 170 ° C. for 2 seconds, and then the support sheet 35 was peeled off to form the optical diffraction recording layer 3 on the substrate 2.

Next, a thermoreversible recording layer 4 was formed on the optical diffraction recording layer 3 by forming a coating layer of the following composition to a thickness of 5 μm by a gravure coating method. Vinyl chloride vinyl acetate copolymer resin: 15 parts by weight Behenic acid: 5 parts by weight Tetrahydrofuran: 80 parts by weight

A colored layer 5 was formed on the thermoreversible recording layer 4 by forming a coating layer of the following composition to a thickness of 2 μm by a gravure coating method. Polybutyl vinylal resin: 10 parts by weight Urethane resin: 10 parts by weight Tetrafluoroethylene powder: 10 parts by weight MS Red GP: 10 30 parts by weight 30 parts by weight methyl ethyl ketone 30 parts by weight 30 parts by weight A card-like product which is one embodiment of the present invention by the above steps. The recording medium was created.

Next, a method of using the recording medium thus prepared and an embodiment of the reading device will be described. A total of eight diffraction gratings in four directions are recorded on the optical diffraction recording layer 3, and a thermoreversible recording layer 4 is formed on the optical diffraction recording layer 3.

In the optical sensor 12 of FIG. 5, 4 when the light receiving element 12a receives the diffracted light, 3 when the light receiving element 12b receives the diffracted light, and 2 when the light receiving element 12c receives the diffracted light, The case where the light receiving element 12d received the diffracted light was set to 1, and the case where no light receiving element received the diffracted light was set to 0. Due to the characteristics of the diffraction grating, the 0th order, the 1st order, the −1st order, the 2nd order, and the
Since the diffracted light of the second order, the second order, ... Is generated, when the light receiving element 12a receives the diffracted light, the light receiving element 1
The diffracted light is also received by the light receiving element 12e in front of 2a.

First, after applying 0.5 mJ / dot of energy with a thermal head to the entire surface of the thermoreversible recording layer 4 to make the entire surface opaque, based on the information of the card holder,
Of the diffraction gratings 3a to 3h, the diffraction gratings 3b, 3c, 3f,
In the portion of the thermoreversible recording layer 4 corresponding to the portion of 3g, 3h,
Energy of 0.2 mJ / dot was applied with a thermal head to make the portion transparent.

Further, the light source 11 made of a semiconductor laser
Recording medium 1 in which the optical diffraction recording layer 3 is formed by using
Is irradiated to the light receiving elements 12a to 12h.
Is read by the optical sensor 12 consisting of
When the optical sensor 12 is moved in the direction of the arrow while maintaining the spatial relative position between the optical sensor 12 and the optical sensor 12, the read information is "02440043".

Next, 0.5 mJ / dot of energy was applied to the entire surface of the thermoreversible recording layer 4 by the thermal head to make the entire surface opaque, and the reading of the recording medium was completed.

The read information was collated by the card holder with the personal identification number directly input to the reading device, and the identity between the recording medium and the recording medium holder was confirmed.

[0068]

In the recording medium of the present invention, the substrate, the optical diffraction recording layer and the thermoreversible recording layer are laminated in this order. Therefore, after the thermoreversible recording layer is made to be transparent to light by heating. Since the light-diffraction recording layer can be read, even if an attempt is made to forge a card, the holder of the card does not know what guarantees the authenticity of the card and can prevent the forgery.

If the optical diffraction recording layer has a structure in which a plurality of different incident lights are diffracted in a plurality of divided areas, the thermoreversible recording layer can be partially reversibly heated. Due to the partially transparent state of the recording layer, even a card provided with an optical diffraction recording layer having a structure for diffracting light common to all cards can be read as individual information of the card owner.

According to the method of using the recording medium of the present invention, after the thermoreversible recording layer is heated to be in a transparent state, light is made incident and the diffracted light from the optical diffractive recording layer is read. Information on the optical diffraction recording layer can be read through the reversible recording layer.

In this case, the thermoreversible recording layer is heated again,
If the optical diffraction recording layer is returned to the original state again, the optical diffraction recording layer is always hidden by the thermoreversible recording layer in the opaque state except when reading, and therefore it cannot be seen that the optical diffraction recording layer is formed.

[0072]

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a recording medium of the present invention.

FIG. 2 is a diagram showing a reading state of the first embodiment of the recording medium of the present invention.

FIG. 3 is a diagram showing a reading state of a second embodiment of the recording medium of the present invention.

FIG. 4 is a sectional view showing an example of a transfer sheet used for the recording medium of the present invention.

FIG. 5 is a diagram showing a reading state of a third embodiment of the recording medium of the present invention.

[Explanation of symbols]

1 recording medium 2 base materials 3 Optical diffraction recording layer 3a to 3h diffraction grating 31-34 Fresnel hologram 4 Thermoreversible recording layer 5 colored layers 6 Magnetic recording layer 7 Optical recording layer 11 light source 12 Optical sensor 12a to 12e Light receiving element

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-73738 (JP, A) JP-A-6-143746 (JP, A) JP-A-51-31682 (JP, A) 58334 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41M 5/26-5/36 B42D 15/10 501

Claims (6)

(57) [Claims] 1. A light-diffraction recording layer, on which a structure for diffracting incident light is recorded, is formed on a substrate, and transparent-opaque light directly provided on the light-diffraction recording layer. It has a thermoreversible recording layer whose reversible property changes reversibly .
The optical diffraction recording layer and the thermoreversible recording layer are transparent.
The thermo-reversible recording that is optically readable when read
Optically unreadable when the layer is opaque
The transparent-opaque state is heated by
A recording medium that is partially formed. 2. The recording medium according to claim 1, wherein the structure that diffracts the incident light is a diffraction grating. 3. The recording medium according to claim 1, wherein the structure that diffracts the incident light is a hologram. 4. The structure for diffracting the incident light is divided into a plurality of regions, and the structure for diffracting a plurality of different incident lights is recorded in the divided regions. The recording medium according to any one of 1 to 3. 5. The method of using the recording medium according to claim 1, wherein the thermoreversible recording layer of the recording medium is used.
After partially heating the thermoreversible recording layer to a partially transparent state, light is incident on the optical diffraction recording layer of the recording medium to read diffracted light from the optical diffraction recording layer. And how to use the recording medium. 6. After making light incident on the optical diffraction recording layer of the recording medium and reading the diffracted light from the optical diffraction recording layer,
The method according to claim 5, wherein the thermoreversible recording layer is heated again to restore the thermoreversible recording layer to the original state.