JPH11161768A - Information carrier having diffraction grating pattern and its verifying method, and transfer foil or seal for forming information carrier on article surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information carrier constituted of a high-security diffraction grating pattern, and a means for easily confirming its validity. SOLUTION: A reversible thermosensitive layer 21 in which a transparent state or a non-transparent state having diffusion translucency is reversibly changed depending on temperature is arranged on a diffraction grating pattern having an information pattern constituted so as not to be visually recognizable by a part where any dot-shaped diffraction grating does not exist. At the time of visualizing the information pattern, a thermosensitive layer 21 is turned into a non-transparent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a security product using a diffraction grating pattern formed by arranging a fine diffraction grating (grating) on the surface of a substrate for each cell (dot), and relates to a normal observation condition. (Under white light), an information pattern that cannot be visually distinguished when visually observed (hereinafter, such a pattern is referred to as “hidden information”) is included in a diffraction grating pattern that can be visually observed. The present invention relates to an information carrier having a diffraction grating pattern having a configuration mixed with the information carrier.

[0002]

2. Description of the Related Art In order to obtain a diffraction grating (or hologram) having high security, there has been proposed a method of complicating the manufacturing method and making it difficult to forge (or imitate).

As an example, there is a method of obtaining a display having a diffraction grating pattern by arranging a plurality of minute dots formed of a diffraction grating on the surface of a substrate by two-beam interference of coherent light (laser beam). JP-A-60-156004 and JP-A-2-156 by the applicant
A method typified by Japanese Patent No. 72319 and Japanese Patent Laid-Open No. 5-72406 is known.

[0004] In these methods, two laser beams are crossed on a photosensitive material, and the two laser beams are caused to interfere by exposing in a dot unit, so that diffraction formed by minute interference fringes formed in each dot is performed. The grid, its pitch
Exposure recording one after another while appropriately changing the direction and light intensity,
This is a method (two-beam interference method) for producing a pattern composed of a group of diffraction grating dots (cells).

The pitch (the reciprocal of the spatial frequency) of the diffraction grating changes depending on the angle of the two light beams incident on the photosensitive material, and the direction of the diffraction grating changes depending on the incident direction of the two light beams. When observing the produced pattern, the pitch relates to the visible color, and the direction relates to the visible direction. In addition, the light intensity at the time of exposure changes the depth of the interference fringes, and is related as the brightness that can be seen during observation. The method of manufacturing the diffraction grating pattern is described in the above 2
The method is not limited to the light beam interference method, and a method of directly drawing lattice fringes on the surface of the substrate with an electron beam (electron beam = EB) and arranging diffraction grating dots (cells) may be employed. The above method is disclosed in Japanese Unexamined Patent Application Publication No.
It is known from U.S. Pat.

[0006] On the other hand, there is also a demand for a method of confirming the validity of a produced hologram (that is, determining the authenticity). As an example of the above method, a diffraction grating (or hologram) on which a reading code is recorded is irradiated with light, the light reproduced and received by a photodiode or the like is read, and the code is read. A proposal to recognize a normal diffraction grating (or hologram) in such a case is disclosed in Japanese Patent Application Laid-Open No. 3-71384.

As another example of the above method, a special light (for example, laser light) or a verifier is used for a hologram in which a reading code (hidden information) that cannot be observed by the naked eye under white light is recorded. Make the diffracted light visible to the naked eye, judge the validity of the hidden information,
A method for determining the authenticity of a hologram is disclosed in Japanese Patent Application Laid-Open Nos. 6-236136 and 6-274084 by the present applicant.
This is disclosed in Japanese Patent Publication No.

In these methods, it is necessary to use a special light source and a verifier for reading, and there is a problem that it is difficult to easily confirm the validity of the hologram.

[0009]

SUMMARY OF THE INVENTION The present invention provides an "information carrier comprising a diffraction grating pattern" having high security which is difficult to forge or imitate, and allows the validity of the information carrier to be easily confirmed. The purpose is to provide such means.

[0010]

An information carrier according to the present invention comprises:
A plurality of fine dots or cells composed of a relief type diffraction grating are desirably arranged on the surface of the substrate, and a diffraction grating pattern in which a reflective layer is formed on the surface and a resin in which organic low-molecular substances are dispersed and mixed are mainly used. As a component, it is composed of a reversible thermosensitive layer in which a transparent state or a non-transparent state having a diffuse translucency changes reversibly depending on temperature, and an area where there is no dot or cell in the pattern cannot be visually discriminated. It is characterized in that it is intentionally provided so as to constitute a certain degree of information pattern, and is mixed in the diffraction grating pattern.

In order to verify the authenticity of the hidden information provided on the information carrier, the transparent reversible thermosensitive layer on the outermost surface of the information carrier is heated to diffuse and transmit light. It is characterized in that an information pattern composed of an area where the dots or cells do not exist is visually determined by observing through the thermosensitive layer which is in a transparent state and the non-transparent state is maintained even at room temperature. .

By forming the information carrier on the surface or the like, it is possible to provide an article which is difficult to forge and illegally use. A typical product is a credit card or a securities, and the information carrier is described in claim 3.
"Forms of transfer foil and stickers" as described in 4.
By doing so, it can be formed on the surface of these articles.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an example of the information carrier of the present invention. FIG. 1 (a) is an explanatory view showing a pattern observed with the naked eye under white light, and FIG. It is explanatory drawing which shows the pattern at the time of visually discriminating the said pattern by the verification method of this invention.

In FIG. 1A, the reversible thermosensitive layer on the outermost surface of the information carrier is in a transparent state, and only a pattern corresponding to the arrangement of fine dots or cells composed of a relief type diffraction grating in the lower layer is visible. However, hidden information consisting of an area where the dot or cell does not exist cannot be recognized.

A pattern composed of a group of diffraction grating dots (cells) is produced by the above-described two-beam interference method or EB drawing, and is copied in large quantities by a known method. It is well-known that a metal reflective layer is formed on the entire surface of a relief surface in order to make a pattern formed by a relief type diffraction grating easy to see. Generally, a metal layer having high reflectivity such as Al, Cr, Au, and Ag is generally used. Also, a metal compound layer having transparency such as TiO ₂ , ZnS or the like is formed by vapor deposition or sputtering.

In the information carrier according to the present invention, the surface of the diffraction grating pattern is mainly composed of a resin in which an organic low-molecular substance is dispersed and mixed, and is in a transparent state or a non-transparent state having a diffuse translucency depending on temperature. Is reversibly changed to form a reversible thermosensitive layer.

The heat-sensitive layer, which is located on the outermost surface of the information carrier and exhibits a transparent state, is heated to a non-transparent state having a diffuse translucency, and the non-transparent state is maintained at room temperature. 1B, the information pattern (“E” in FIG. 1B) composed of the area where the dot or cell does not exist can be visually discriminated as shown in FIG. 1B.

The reversible thermosensitive layer having the above-mentioned properties is
It is disclosed in JP-A-55-154198.

The heat-sensitive layer is mainly composed of an organic low-molecular substance and a resin for dispersing and mixing the same. As the above resin,
A thermoplastic resin having a refractive index close to that of an organic low-molecular substance, having no compatibility, excellent mechanical strength, film forming ability, and high transparency is preferable.

The heat-sensitive layer becomes transparent by heating up to the temperature T _1, and is kept transparent even when cooled. Further, by heating up to the temperature T ₂ (T ₂ > T ₁ ), the liquid crystal becomes a cloudy state (a non-transparent state having a diffuse translucency), and even when cooled, the transparent state is maintained, and the state change is reversible.

If the above characteristics are the same not only in the visible light region but also in the near-infrared region, the verification can be performed in the near-infrared region (for example, determination of a diffraction pattern by irradiation with a laser beam having a near-infrared wavelength). It is.

As the above thermoplastic resin, vinyl chloride-
Vinyl chloride copolymers such as vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer; polyvinylidene chloride resin ; Vinylidene chloride-vinyl chloride copolymer, vinylidene chloride
Vinylidene chloride copolymers such as acrylonitrile copolymers; polyamide resins; silicone resins; polyacrylate or polymethacrylate resins or copolymers thereof; and these may be used alone or as a mixture of two or more. Can be.

The organic low-molecular substance dispersed and mixed in the thermoplastic resin contains at least one of oxygen, sulfur, nitrogen and halogen, has 10 to 40 carbon atoms, and has a molecular weight of 100 to 700. Yes, and melting point 50 ~
Organic compounds having a temperature in the range of 150 ° C. may be mentioned. Specific examples include higher alcohols such as alkanols, alkanediols, halogen alkanols, and halogen alkane diols; higher aliphatic amines; alkanes, alkenes, alkynes, and halogen substitution thereof. Body; cycloalkane,
Cyclic compounds such as cycloalkenes and cycloalkynes;
Saturated carboxylic acids, unsaturated monocarboxylic acids, dicarboxylic acids or their esters, amides, ammonium salts; saturated or unsaturated halogen aliphatics, or their esters, amides, ammonium salts; acrylic carboxylic acids or their esters, amides Thioalcohols or their carboxylic esters; thiocarboxylic acids or their esters, amides,
Ammonium salts and the like;
A mixture of more than one species can be applied.

An organic solution in which the above-mentioned thermoplastic resin and an organic low-molecular substance are dissolved, such as methyl ethyl ketone, methyl isobutyl ketone, chloroform, ethanol, benzene, toluene, tetrahydrofuran, carbon tetrachloride, or the above-mentioned thermoplastic resin A dispersion in which the above-mentioned organic low-molecular substance is dispersed in the form of fine particles in a solution in which a resin is dissolved is applied to a base film and dried to form the heat-sensitive layer.

For the purpose of changing the optical properties of the heat-sensitive layer, a dye, an ultraviolet absorber, or an infrared or visible light absorber may be added to the layer.
Furthermore, a protective layer made of a heat-resistant resin (film) may be formed on the layer for the purpose of improving the resistance of the reversible reaction between the transparent state and the cloudy state.

The diffraction grating pattern in the information carrier is excellent in display (decorative) effect and security, and further information patterns are mixed in the form of hidden information, so that security is further improved. .

The information pattern may be a two-dimensional code such as a decorative image (pattern) or a bar code or a color code, as in the case of the diffraction grating pattern.
It is preferably character information.

The relief type diffraction grating is formed by a so-called embossing method. As the layer for forming the diffraction grating pattern, a resin having good embossing moldability and good adhesion to the heat-sensitive layer and a reflective thin film layer described later is preferable, and an acrylic resin, a urethane-based resin, a cellulose acetate-based resin,
Examples include nitrocellulose resins.

The above-mentioned resin is formed into a liquid by a known coating method so as to have a dry thickness of 0.5 to 2 μm, and a hologram master on which information is recorded in the form of relief (unevenness) is used as a stamper. By embossing (heating and pressing) the resin, a relief type diffraction grating is formed.

As described above, the reflective thin film layer may be a metal layer having high reflectivity or a metal compound layer having not only reflection but also transmissivity. More specifically, materials applicable to the reflective thin film layer include Al and C.
Opaque but high reflectivity materials such as r, Sn, Ni, etc., Sb ₂ S ₃ , Fe ₂ O ₃ , TiO ₂ , CdS, Ce
O ₂ , PbCl ₂ , CdO, Sb ₂ O ₃ , Bi ₂ O ₃ ,
ZnS, WO ₃ , SiO, In ₂ O ₃ , PbO, Ta ₂
O ₃ , ZnO, CaO.SiO ₂ , ZrO, Cd
Transparent materials such as ₂ O ₃ and Al ₂ O _{3 which} have a higher refractive index than the material constituting the diffraction grating forming layer are exemplified. In the latter case, within the reproducible angle range of the diffraction grating pattern, the reflectivity of light by the reflective thin film layer is maximized,
While functioning as a reflection type, it functions as a mere transparent film outside the reproducible angle range of the diffraction grating pattern. Each material has a thickness of 0.03 to 0.08 μm by a vacuum evaporation method, a sputtering method, an ion plating method, or the like.
m reflective thin film layers can be formed.

FIG. 2 shows the information carrier in the form of a seal (sticker), which is adhered to the surface of an article 1 such as a voucher or a card to read a diffraction grating pattern or hidden information in the information carrier. It is explanatory drawing which shows the state which is.

It is also conceivable to process the information carrier into a transfer foil form instead of a seal (sticker) form and to stick the information carrier on the article surface. FIG. 3 is a cross-sectional explanatory view of the form of the seal (sticker), and FIG. 4 is a cross-sectional explanatory view of the form of the transfer foil. 3 and 4, members having the same function are denoted by the same reference numerals, and overlapping description will be omitted.

In the case of a transfer foil, heat resistance and flexibility are required for the base film 20 (temporary support for the information carrier) due to the characteristics required at the time of thermal transfer. , Polyolefin, polyvinyl chloride, acrylonitrile-butadiene-styrene and the like. The reversible thermosensitive layer 2
No. 1 requires good peeling from the base film 20 at the time of transfer, and it is preferable that the heat-sensitive layer 21 itself has releasability by heating with a thermal head (or heating with a hot plate). A peeling layer (not shown) (for example, waxes having a melting point of 60 to 120 ° C. or resins having a softening point of 60 to 150 ° C.) may be interposed therebetween for peeling.

A reflective thin film layer 23 is formed on the relief surface of the diffraction grating pattern forming layer 22. The reflective thin film layer 23 is formed on the reflective thin film layer 23 in FIG. The adhesive layer 24 is formed. Adhesive layer 24
As a main component, an acrylic resin, a vinyl resin or the like is used as a main component, and its thickness is suitably about 0.5 to 2.0 μm.

In the case of a seal (sticker), the base film 20 is a transparent film that supports the information carrier. After the information carrier is transferred to the surface of the article, either the base film 20 remains on the carrier or is removed. But it is good. If left on the carrier, the base film 20 will primarily function as a protective layer for the information carrier. Properties required for the base film 20 include transparency, flexibility, and film materials such as polyethylene, polyester, and polyvinyl chloride.

The adhesive layer 24 is composed of an auxiliary material such as an elastic body as a main component, a tackifier, a plasticizer, and a filler. Examples of the elastic body include natural rubber, synthetic isopropylene, recycled rubber, SBR rubber, polyisoprene rubber, polyacrylate or a derivative thereof, styrene-isoprene-styrene rubber, silicone comb, and silicone resin. Examples of the tackifier include rosin and rosin derivatives, polyterpene resins, chroman-indene resins, petroleum resins, and terpene phenol resins. Examples of the plasticizer include liquid polybutene, mineral oil, lanolin, liquid polyisoprene, and liquid polyacrylate. If necessary, a filler such as an extender or an inorganic pigment, and an antioxidant such as an antioxidant may be added.

The release sheet 25 is a sheet for preventing the information carrier from adhering to other objects until the information carrier is attached to the surface of the article. The release sheet 25 is a sheet of paper coated with silicone through a polyethylene film. Known materials such as kraft paper, glassine paper, and various plastic films which have been subjected to super calendering after clay coating are used.

When the information carrier is processed into the above-described form (seal or transfer foil) and adhered to the surface of the article, it is further fragile to prevent unauthorized use such as forgery or tampering. Applications such as providing a destruction layer are appropriately considered.

The hidden information can be confirmed by observing the diffraction grating pattern of the lower layer through the non-transparent reversible thermosensitive layer 21 having a diffuse translucency because the diffusivity is higher in the portion where no diffraction grating is present. The reason for this is that the amount of light entering the eye is inferior, and the principle will be described in detail below.

FIG. 5 is an explanatory view schematically showing diffuse reflection characteristics when light is vertically incident on a surface having a diffusive property (diffuse surface). In the figure, I ₀ represents the intensity of incident light, I represents the intensity of diffused light, and the dotted line represents the intensity distribution of diffusion. Approximately, it can be expressed as I = I ₀ cos ⁿ θ. Here, n is a specific index of the diffusion surface, and the larger the value of n, the lower the diffusivity, and the smaller the value, the higher the diffusivity. In the present invention, it is assumed that when n takes a value of 5 to 100, visual determination is possible.

FIG. 6 is an explanatory diagram for schematically showing the phenomenon (principle) of reading hidden information in FIG. The incident light is diffused on the diffusing surface of the reversible thermosensitive layer in a non-transparent state having diffuse translucency, then enters the diffraction grating, and is divided into a diffracted component, a specularly reflected component, and a diffused component.

In a region where the relief type diffraction grating does not exist, it is considered that the light is simply regularly reflected by the reflection layer. Further, in practice, a base material, a relief forming layer, and the like are present before reaching the reflective layer, but it is considered that the influence on the incident light is small.

In the case of a relief type diffraction grating having a reflective layer, reflected light and diffracted light travel in the direction of incident light (to the left in the figure). The diffracted light will also be described in such a way that it travels symmetrically to the right with respect to the reflective layer.

In the figure, A indicates a simple transmitted light (actually reflected light) in a region where no diffraction grating exists, B indicates a first-order diffracted light which is diffracted by the diffraction grating, and C indicates a 0th-order light. still,
The diffracted light of the second and subsequent orders is ignored because it is very small. D indicates light diffused by the lattice plane.

The relationship between A and D is expressed by the following "(1) and (2)".
become that way. (1) A = B + C + D (2) A>B>C> D or A>C>B> D In the figure, the thickness of the arrow is an index indicating the intensity (light amount) of the light beam. It is represented schematically.

The light reaching the observer from the area where the diffraction grating does not exist is A, and the light reaching the observer from the area where the diffraction grating exists is any of B, C and D or a combination thereof. According to the relationship, the light amount of A becomes the largest, and therefore, the hidden information can be confirmed by observing through the light-transmitting sheet having a diffusive property.

The above can be explained by the following concept. First, a diffraction grating is considered as a kind of diffusion plate, and diffraction is regarded as being equivalent to diffusion.
In the region where the diffraction grating does not exist, the light is diffused by the non-transparent reversible thermosensitive layer having a diffusing property upon incidence of light, and is simply specularly reflected by the region (reflection layer). Will be spread again. That is, the light beam is diffused twice at the time of incidence and at the time of emission. Similarly, in the region where the diffraction grating exists, the light is diffused twice at the time of incidence and emission at the non-transparent reversible thermosensitive layer having a diffusive property, but is also diffused (diffracted) by the diffraction grating. In this case, the light is diffused three times, and the number of times of diffusion is one more. Therefore, the amount of light perceived by an observer is narrower and brighter in a region where no diffraction grating is present than in a region where no diffraction grating exists.

When the heat-sensitive layer is transparent, it is required that the presence of a pattern (hidden information) constituted by a region where no diffraction grating is present is hard to be visually recognized. In such a case, it is required that the hidden information be easily visible. The size of a diffraction grating dot (cell) satisfying the above requirements is preferably about 100 to 200 μm in diameter (one side in the case of a rectangle).

[0049]

<Example 1> An example in which an information carrier is processed into a transfer foil form and applied to the surface of an article will be described. A reversible thermosensitive composition having the following composition was gravure coated on a base film made of a biaxially stretched polyethylene terephthalate film having a thickness of 25 μm and having a releasable surface to form a 1 μm thick reversible thermosensitive layer.

[Reversible thermosensitive composition] Behenic acid (7 parts by weight) Eicosane diacid (1 part by weight) 1,4-ciscyclohexanedicarboxylic acid (0.7 parts by weight) 1,4-transcyclohexanedicarboxylic acid (0 part by weight) .3
100 parts by weight of vinyl chloride-vinyl acetate-vinyl alcohol copolymer (trade name "Eslec A" manufactured by Sekisui Chemical Co., Ltd.) ... 30 parts by weight
0 parts by weight Curing agent: Isocyanate (trade name “Duranate 24A-100” manufactured by Asahi Kasei Corporation) 30 parts by weight Curing accelerator: triethylenediamine 3 parts by weight Toluene 300 parts by weight Tetrahydrofuran 1200 parts by weight

The following composition was gravure coated to a thickness of 1
A μm diffraction grating forming layer was formed. [Composition for forming diffraction grating layer] Acrylic polyol (Tg; 75 ° C., OH value; 10)
0) 30 parts by weight Nitrocellulose 5 parts by weight Xylene diisocyanate 5 parts by weight Toluene 35 parts by weight Methyl ethyl ketone 30 parts by weight

By a two-beam interference method, a plurality of minute dots made of a diffraction grating were arranged as desired on a photoresist, and a diffraction grating pattern in which "hidden information" in a region without a diffraction grating was mixed was produced. Next, a stamper is raised from the pattern, a diffraction grating pattern is embossed on the diffraction grating forming layer, and Al
Vacuum evaporation was performed at a thickness of 0 μm to form a reflective thin film layer. [Stamper] Size; 3 mm x 3 mm Dot size; 0.1 mm diameter Spatial frequency of diffraction grating; 700 dots / mm Dot in pattern; Four types of diffraction grating directions differing by 45 °

The following composition was gravure coated on the reflective thin film layer to form an adhesive layer having a thickness of 1.5 μm to obtain a transfer foil. [Composition for Adhesive Layer] Polyester resin: 30 parts by weight Methyl ethyl ketone: 50 parts by weight Toluene: 50 parts by weight

Using the transfer foil obtained as described above, an information carrier was formed on the surface of the article. In a transparent state, the reversible thermosensitive layer of the information carrier transmits infrared rays or visible rays, and the underlying diffraction grating pattern can be recognized by the naked eye. ), The hidden information can be recognized with the naked eye. Further, once the reversible thermosensitive layer in the clouded state is heated to 80 ° C., the thermosensitive layer can be returned to the transparent state, and the diffraction grating pattern can be recognized with the naked eye, but the hidden information Cannot be recognized with the naked eye.

The entire surface of the reversible thermosensitive layer can be heated at once by a hot plate. However, when the entire surface is sequentially heated by a thermal head, the reversible thermosensitive layer can be easily slipped on the surface. It is also effective to perform anti-sticking processing on the. Sticking is disadvantageous in that the surface movement of the thermal head is not smooth, and as the above-described prevention treatment, the thermal head and the moving surface are microscopically brought into contact with each other at a `` plane-point ''. Forming is taking place.

<Embodiment 2> An embodiment in which an information carrier is processed into a seal (label) form and applied to the surface of an article will be described. A reversible thermosensitive layer having the same composition as in Example 1 was applied to a transparent film made of biaxially stretched polyethylene terephthalate having a thickness of 50 μm by gravure coating to a thickness of 1 μm.
It was formed in μm.

Further, the same composition as in Example 1 was gravure coated to form a diffraction grating forming layer having a thickness of 1 μm.

By EB drawing, a diffraction grating pattern was formed on the electron beam resist in which hidden information composed of regions without diffraction grating cells was mixed. After embossing a diffraction grating pattern on the diffraction grating forming layer with a stamper raised from the above pattern, Zn
S was formed by vacuum evaporation to a thickness of 80 nm to form a reflective thin film layer.

After forming an adhesive layer by gravure coating a polyacrylate on the reflective thin film layer, a release sheet made of kraft paper was laminated to form a seal (label).

An information carrier was formed on the surface of a card made of polyvinyl chloride with the seal (label) obtained as described above.

The information carrier according to this embodiment also transmits infrared or visible light when the reversible thermosensitive layer is transparent,
The diffraction grating pattern in the lower layer can be recognized with the naked eye, but once heated to 120 ° C. to make it cloudy,
Hidden information can be recognized by the naked eye, and the reversible thermosensitive layer in the cloudy state can be returned to the transparent state by heating it to 80 ° C once, so that the diffraction grating pattern can be recognized by the naked eye. However, hidden information cannot be recognized with the naked eye.

[0062]

According to the present invention, an information carrier having a diffraction grating pattern with high security which is difficult to forge or imitate is provided. In the information carrier, the transparent state and the non-transparent state having diffuse translucency are appropriately changed by changing the state of the reversible thermosensitive layer having the property of reversibly changing. Confirming the validity of the underlying hologram is realized. The state change is
Since it is a simple one using only heat treatment, a special light source and a verifier for reading are not required unlike the existing authenticity discrimination.

[0063]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a diffraction grating pattern of the present invention.

FIG. 2 shows an information carrier having a diffraction grating pattern according to the present invention in the form of a seal (sticker), and reads hidden information in the pattern from an article attached to a surface such as a voucher or a card. Explanatory drawing which shows a state.

FIG. 3 is an explanatory cross-sectional view when the information carrier of the present invention is processed into a seal form.

FIG. 4 is an explanatory cross-sectional view when the information carrier of the present invention is processed into a transfer foil form.

FIG. 5 is an explanatory diagram schematically showing diffuse reflection characteristics when light is vertically incident on a surface having a diffusive property (diffuse surface).

FIG. 6 is an explanatory diagram schematically showing a phenomenon (principle) of reading hidden information in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Article 2 ... Information carrier 20 ... Base film 21 ... Reversible thermosensitive layer 22 ... Diffraction grating pattern forming layer 23 ... Reflective thin film layer 24 ... Adhesive layer (adhesive layer) 25 ... Release sheet

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G06K 19/06 G06K 19/00 D G07F 7/08 G07F 7/08 A

Claims (4)

[Claims] 1. A diffraction grating pattern in which a plurality of fine dots or cells formed of a relief type diffraction grating are desirably arranged on the surface of a substrate and a reflective layer is formed on the surface, and an organic low molecular substance is dispersed and mixed. The resin is a main component, a transparent state or a non-transparent state having a diffuse translucency depending on the temperature is formed of a reversible thermosensitive layer that reversibly changes, and the area where the dots or cells of the pattern do not exist,
An information carrier characterized by being intentionally provided so as to constitute an information pattern that cannot be visually discriminated, and being mixed in a diffraction grating pattern. 2. A method for verifying an information pattern recorded on an information carrier according to claim 1, wherein the reversible thermosensitive layer in a transparent state is heated to a non-transparent state having a diffuse translucency, A verification method characterized by visually discriminating an information pattern composed of an area where the dots or cells do not exist by observing through the heat-sensitive layer in which the non-transparent state is maintained even at room temperature. 3. A transparent film or a translucent non-transparent state reversibly changes depending on temperature at least based on at least a resin in which an organic low-molecular substance is dispersed and mixed on a base film. A reversible thermosensitive layer, a plurality of fine dots or cells composed of a relief type diffraction grating are desirably arranged on the surface of the substrate, and a diffraction grating pattern in which a reflective layer is formed on the surface, and a thermosensitive adhesive layer, A transfer foil formed in this order, wherein the information carrier according to claim 1 is formed on the surface of the transfer-receiving body by thermal transfer. 4. A reversible heat-sensitive layer containing a resin in which an organic low-molecular substance is dispersed and mixed as a main component and reversibly changing a transparent state or a non-transparent state having a diffuse translucency depending on temperature. A plurality of fine dots or cells composed of a relief type diffraction grating are desirably arranged on the surface of the substrate, a diffraction grating pattern in which a reflective layer is formed on the surface, an adhesive layer, and a release sheet, in this order. A seal having a configuration in which the information carrier according to claim 1 is formed on the surface of the article by forming, peeling off and peeling off the release sheet.