JP2011075878A - Authenticity identification element, authenticity determining sheet and authenticity determining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forgery-preventive technique which is simpler and permits high-reliability determination because, when functional material such as cholesteric liquid crystal having the function different from hologram in an authenticity identification element using the hologram is laminated, the lamination steps are complicated and it is difficult to suppress the deterioration such as out-of-focus image and distortion of a hologram image due to lamination. <P>SOLUTION: Holograms are discretely disposed in order to enhance the authenticity in the authenticity identification element using the holograms, a gap of the holograms is turned into a light-scattering rough surface and, thereby, a hologram image can not be recognized under usual observation but the method capable of visualizing the hologram image is permitted only by using a prescribed authenticity determining sheet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an authenticity identifier, an authenticity determination sheet, and an authenticity determination method that enable discrimination between authenticity obtained by forgery and falsification based on an unauthorized intention and authenticity. The present invention also relates to a product in which such an authenticity identifier is processed into a label form or transfer sheet form suitable for application to an article.
In the present specification, “part” indicating the formulation is based on mass. The “hologram” refers to a hologram and a light diffraction property such as a diffraction grating, a coherence of the diffracted light, and a function of reproducing a diffraction image.

(Main use) The main use of the authenticity identifier, the authenticity determination sheet and the authenticity determination method of the present invention is a hologram sheet used in the field of forgery prevention, specifically, a credit card or the like. If the card is forged and used, it may damage the cardholder or card company, driver's license, identification card such as employee ID card, membership card, entrance examination card, passport, banknote, There are gift certificates, point cards, stock certificates, securities, lottery tickets, horse tickets, passbooks, boarding tickets, passports, air tickets, admission tickets for various events, play tickets, prepaid cards for transportation and public telephones, and the like.
Each of these is an information recording body that holds information having economic or social value, and it is desirable to have a function that can identify the authenticity of the recording body for the purpose of preventing damage caused by forgery. .

In addition to these information recording media, expensive products such as luxury watches, luxury leather products, precious metal products, jewelry, etc., often referred to as luxury brand products, or storage of such expensive products. Boxes and cases can also be forged. In addition, mass-produced products of famous brands, such as audio products, electrical appliances, etc., or tags that are hung on them are also subject to forgery.
Furthermore, a storage body in which music software, video software, computer software, game software, or the like, which is a copyrighted work, or cases thereof can also be forged. In addition, it is desirable that products such as printer toner, paper, and the like in which supplies to be replaced are limited to genuine materials have a function of identifying their authenticity for the purpose of preventing damage caused by forgery.

(Background technology)
Conventionally, for the purpose of preventing counterfeiting of information recording bodies and various articles described above (collectively referred to as authenticity identification objects), it is said that they have manufacturing difficulties due to the precision of their structures. In many cases, holograms are applied as authenticity distinguishable. However, since the hologram manufacturing method itself is known and can be precisely processed by that method, when the hologram is merely for visual judgment, there is no difference between a genuine hologram and a forged hologram. It is difficult to distinguish.
These authentic identification objects, in particular, articles that have been subjected to hologram images in a label form or transfer form, are not only used for authentic identification of visual confirmation of hologram images, but also by using a new authenticity identification method. There is a need to identify the authenticity of.

(Prior art)
In order to meet these requirements, an authenticity discriminator having a light selective reflection layer that is laminated on a hologram and reflects only one of the left-handed polarized light and the right-handed polarized light in the incident light is proposed. It was. (For example, refer to Patent Document 1.)
As this light selective reflection layer, cholesteric liquid crystal is used, and the anti-counterfeiting property is enhanced by a method of confirming using a polarizing plate or the like.

However, as described in Patent Document 1, since the reflectance of the reflective thin film layer on the hologram forming layer is high, the light that is transmitted without being reflected by the cholesteric liquid crystal layer (complementary light of selective reflected light) Reflecting on the reflective thin film layer and returning to the cholesteric liquid crystal layer again (hereinafter referred to as return light), this return light becomes a noise component when observing the cholesteric liquid crystal and is added to and mixed with the selectively reflected light. However, the color tone was not the original color of the liquid crystal, and it was even difficult to see and identify.
In addition, the cholesteric liquid crystal material itself is expensive, and in order to draw out the liquid crystal performance, it is indispensable to form an alignment film in contact with the liquid crystal layer. Further, due to the light scattering property of the cholesteric liquid crystal, the hologram There have been problems such as blurring and distortion of the image when light for reproducing the image passes through the liquid crystal layer.
For this reason, it has been devised to suppress the light scattering property of the cholesteric liquid crystal layer or to make the cholesteric liquid crystal layer itself thin. However, in order to suppress the light scattering property of the cholesteric liquid crystal layer, the refractive index difference is reduced, or the cholesteric liquid crystal layer itself is reduced. When the liquid crystal layer is made thin, the function as the light selective reflection layer described above is deteriorated, and there is a drawback that it is difficult to obtain optimum conditions for ensuring the clarity of the hologram image and the anti-counterfeit performance. .

On the other hand, as a method of authenticity determination without using an expensive material such as cholesteric liquid crystal, two different band-shaped diffraction gratings are used as a pair of bands, and the angle of the bands is partially changed by 90 degrees, and the partial A hidden pattern with a light diffraction structure that performs the authenticity judgment of the appearance of characters, designs, etc. formed by the partial area using the effect that the area cannot be visually recognized and the determination tool having the same angle as the band of the partial area And a method for manufacturing the same.
However, the optical diffraction structure used for this determination is formed by combining a number of diffraction grating patterns in a complex and precise manner. This has the disadvantage that the characters can be easily confirmed with an optical microscope.

JP 2007-90538 A Japanese Patent Laid-Open No. 2003-344631

Accordingly, the present invention has been made to solve such problems. The purpose is to form a diffraction grating for reproducing a hologram image discretely in units of fine pixels, reflect it at discrete parts, generate partial diffraction, interference phenomenon, and generate discrete diffracted light, The reflected light from another adjacent reflective optical element interferes with the interference phenomenon in the discrete part, does not form a visible hologram image, and the discrete state is irregular and optical. An object of the present invention is to provide an authenticity identifier that cannot obtain any authenticity determination information even if a microscope is used.
In addition, there is provided an authenticity determination method capable of easily determining the authenticity by simply holding the authenticity determination sheet unique to the authenticity identifier so as to be in contact with the authenticity identifier.

To solve the above problem,
The first aspect of the authenticity identifier of the present invention is:
A hologram relief in which diffraction gratings corresponding to a hologram image in which the incident direction of the reference light and the reproduction direction thereof are substantially the same are formed on one surface of the transparent base material in discrete pixel units, and a diffraction grating, A transparent resin layer having surfaces on which different optical elements are alternately formed, and a reflective thin film layer is provided so as to follow the hologram relief and the optical element forming surface. Is.
According to the authenticity identifier of the first aspect,
A hologram relief in which diffraction gratings corresponding to a hologram image in which the incident direction of the reference light and the reproduction direction thereof are substantially the same are formed on one surface of the transparent base material in discrete pixel units, and a diffraction grating, A transparent resin layer having surfaces on which different optical elements are alternately formed, and a reflective thin film layer is provided so as to follow the hologram relief and the optical element forming surface. An authenticity identifier can be provided.

A diffraction grating for reproducing a hologram image is formed by forming a groove having a period of about 1 μm or a sub-μm in a region larger than the hologram image to be reproduced by using light interference or using an electron beam drawing method. The hologram image is reproduced at a predetermined angle by applying predetermined illumination light to the entire formation region.
The phenomenon will be described in detail.
The illumination light reaches the surface of each groove on the diffraction grating surface, and is reflected at the interface between the reflective thin film provided following the shape of the groove and the resin in which the groove is formed. This reflection phenomenon follows the Huygens principle, and a secondary wave is newly sent out as a spherical wave (a sphere consisting of points having the same phase of the wave) from every point on the interface between the resin and the reflective thin film. The curved surface in contact with all of the wavefronts of these secondary waves, that is, the envelope surface, becomes a wavefront at a later time, and all the spherical waves cause sufficient interference (depending on the coherence of the illumination light). Thus, the hologram image is formed in a predetermined direction.
This spherical wave forms a wavefront shape specific to each groove in units of individual grooves, and the wavefronts specific to each groove further cause an interference phenomenon to form one hologram image.
Interference between wavefronts formed by individual grooves contributes to the interference of the surface of the groove with several tens of grooves at the center, based on the theoretical formula of the diffraction intensity of the diffracted light of the simple diffraction grating and various experiments. In addition, it has been found that the interference of light generated in a space within a distance of several tens of μm from the diffraction grating forming surface greatly affects the image quality of the finally formed hologram image.
However, in the case of interference fringes formed by interference between the object light and the reference light, the interference extends to the entire interference fringe formation surface, and all wavefronts generated by individual grooves on the entire formation surface interfere. Therefore, since a desired hologram image is formed, complete reproduction cannot be performed only with the wavefront of the partial interference fringes. However, since the interference between the object light and the reference light is formed by overlapping the interference of all points, the hologram image must be referred to unless the maximum intensity of the reproduced image or the fine intensity is referred to. It can be said that reproduction is possible.

The present invention includes the above two principles,
One is that the “diffraction grating for reproducing a hologram image” has a region of several tens of μm on the hologram forming surface and exhibits an interference effect within a distance of several tens of μm from the hologram forming surface. That space is secured,
The other is that the hologram can reproduce the desired hologram image even if it is formed discretely due to its redundancy,
Is applied.
Accordingly, the size of the partial region of the diffraction grating for reproducing the hologram image, that is, the size of a fine pixel unit is set to several tens of μm or more, and at least the distance to the adjacent fine pixel is set to several tens of μm or more. To do.

Actually, the diffraction grating manufacturing process for reproducing the hologram image, the image quality of the reproduced hologram image, and the “optical element different from the diffraction grating” formed between this fine pixel and the adjacent pixel In view of this balance, the size of a fine pixel unit of a diffraction grating for reproducing a hologram image is preferably 30 μm to 300 μm, particularly 50 μm to 100 μm.
If it is less than 30 μm, the interference effect of each region is not sufficient, and if it exceeds 300 μm, interference inhibition of light from the adjacent optical element does not spread over the entire region, and the hologram image can be seen without an authenticity determination sheet. Will end up.
Among them, in the case of 50 μm to 100 μm, both the interference effect and the inhibition effect are sufficiently exhibited and good.
Further, as described above, it is not desirable for the purpose of preventing counterfeiting to make the size of the region and the distance between the regions precisely the same or uniform, but rather, within the above range, It is preferred that the value be random.
Therefore, the shape of the partial region may be a random shape or a random arrangement of a plurality of shapes within the above range.
Next, the “optical element different from the diffraction grating” will be described.
The purpose of forming this optical element is to prevent the reproduction of the hologram image by interfering with or disturbing the interference phenomenon of each discrete region of the “diffraction grating for reproducing the hologram image” as described above. For that purpose, the above-mentioned “interference space important for hologram reproduction” of each region, that is, “within a distance of several tens of μm on the hologram forming surface and several tens of μm from the hologram forming surface” It is necessary to cast (superimpose) the reflected light generated by the optical element.
Of course, it is essential that the reflected light generated by the optical element has no coherence with the diffracted light of the individual regions described above. If this coherence is even a little, there is a possibility that a new image is formed due to interference between the interference lights.
Therefore, the “optical element different from the diffraction grating” of the present invention does not derive reflected light having a light coherence such as a diffraction grating or a mirror surface, and is a reflection having no light coherence. That is, it has the property of randomizing the direction and phase of the reflected light at each reflected point.
In the simplest case, it is desirable to scatter scattered light from a rough surface, particularly one that emits scattered light with similar intensity in all directions.

However, if the illuminating light is spot-shaped with a certain extent, when the illuminating light is incident obliquely, the scattered reflected light from the rough surface tends to be strongly reflected in the regular reflection direction. . Of course, the “0th-order diffracted light” of the diffraction grating for reproducing the hologram image is also reflected with a certain intensity in the regular reflection direction.
Therefore, by diffracting the “first-order diffracted light (hologram image)” of the diffraction grating that reproduces the hologram image in a direction completely different from this direction, that is, substantially the same direction as the incident angle of the illumination light, these unnecessary The sharpness of the hologram reproduction image of light (regular reflection light) can be improved. That is, a clear hologram image can be viewed with a simple authenticity determination sheet only when determining the authenticity while minimizing the disturbance or disturbance of the interference phenomenon due to the unnecessary light.
Further, the surface from which the scattered reflected light is emitted (the surface serving as the base thereof) does not need to be flat, and it is also preferable to take a raised shape like a convex mirror and emit light around it. is there.
The roughness of the rough surface is 0.1 μm to 10 μm as a maximum drop, and preferably 3 μm to 5 μm. Since it is the maximum head, there are many irregularities smaller than this value. If the thickness is less than 0.1 μm, the scattered light is small, and if it exceeds 10 μm, the scattering property is uneven. The period of the irregularities on the rough surface may be comparatively gentle, as long as it is greater than the maximum drop.
As the rough surface, it is possible to use a surface treatment such as a sand blast treatment, a wet etching treatment or a dry etching treatment on the surface of a resin film or a metal film, a photoresist development treatment, a microbead coating treatment such as polyethylene powder, etc. it can. In particular, when microbeads are used, the particle size can be easily controlled, and the particle surface is also rough, which is preferable because unnecessary interference does not occur.

The maximum height of the convex surface is preferably the size of the region, that is, 30 μm to 300 μm. For example, if each region is assumed to be circular, and the gap between the circular regions is filled with `` optical elements different from the diffraction grating '', scattered light is directed from the periphery of each region toward its center. It is optimal to take the raised shape so that the scattered light fills the circular area.
Next, the simplest procedure for providing individual “diffraction gratings for reproducing hologram images” and “optical elements different from the diffraction gratings” will be described.

The surface of the glass substrate is formed with a rough surface that becomes a “optical element different from the diffraction grating” and takes a value in the above-described range using hydrogen fluoride, and a hologram photoresist is formed on the rough surface. (If the thickness is too thin, unnecessary interference fringes due to the reflected light from the roughening will also be formed when the thickness is small. After the formation of a “diffraction grating that reproduces a hologram image” by interferometry, a mask pattern that defines the shape of each region is used to create a “diffraction grating that reproduces a hologram image”. The photoresist is left only in the formed portion, and the photoresist is completely removed in the other portions to expose the rough surface of the glass substrate.
The surface of the glass substrate, which has the “diffraction grating that reproduces the hologram image” and the “optical element different from the diffraction grating” produced in this way, is duplicated with the duplication resin formed on the film substrate. Then, a reflective thin film is formed on the replication surface to obtain an authenticity identifier.
An adhesive may be applied to the reflective thin film layer to form a label, or an adhesive may be applied to form a transfer sheet.
The second aspect of the authenticity identifier of the present invention is:
The size of each region of the alternately formed optical element is larger than the size of a fine pixel unit of the diffraction grating.
According to the authenticity identifier of the second aspect,
2. The authenticity identifier according to claim 1, wherein a size of each of the alternately formed optical elements is larger than a size of a fine pixel unit of the diffraction grating. Can do.

Interference of the “diffraction grating that reproduces the hologram image” when the authenticator with the “diffraction grating that reproduces the hologram image” and the “optical element different from the diffraction grating” is observed under illumination light In order to sufficiently bring out the effect of the “optical element different from the diffraction grating” hindering the phenomenon, the size of the individual area of the “optical element different from the diffraction grating” is changed to the individual diffraction grating that reproduces the hologram image. Make it larger than the size of the area.
However, if the size exceeds three times, the ratio of illuminating the “diffraction grating that reproduces the hologram image” with respect to the entire illumination light becomes too small, and authenticity is determined using an authenticity determination sheet. This leads to a decrease in reliability.
However, the ratio of the individual regions described above is not fixed uniformly, but is preferably a plurality of values or random within the above range.
The third aspect of the authenticity identifier of the present invention is:
An authenticity determination sheet for determining authenticity of the authenticity identifier, wherein an angle that transmits light incident on one surface and an angle that transmits light incident on the other surface are substantially the same, The angle is substantially equal to an incident angle and a diffraction angle of the diffraction grating.
According to the authenticity identifier of the third aspect,
An authenticity determination sheet for determining authenticity of the authenticity identifier, wherein an angle that transmits light incident on one surface and an angle that transmits light incident on the other surface are substantially the same, It is possible to provide an authenticity determination sheet in which the angle is substantially equal to the incident angle and the diffraction angle of the diffraction grating.

The fourth aspect of the authenticity identifier of the present invention is:
It is characterized in that the authenticity of the authenticity identifier is determined by superimposing the authenticity determination sheet on the authenticity identifier and observing the hologram image.
According to the authenticity identifier of the fourth aspect,
To provide an authenticity determination method characterized by determining the authenticity of the authenticity identifier by superimposing the authenticity determination sheet on the authenticity identifier and observing the hologram image. Can do.
When the authenticity identification object is observed under illumination light, the “diffraction grating that reproduces the hologram image” and the “optical element different from the diffraction grating” simultaneously emit reflected light to observe a dim rainbow glow. However, when an authenticity determination sheet in which the angle at which light incident on one surface is transmitted and the angle at which light incident on the other surface is transmitted is approximately the same is observed, it is reflected (diffracted). As the incoming light, only the light returning in almost the same direction (reverse direction) as the illumination light incident in a spot shape is transmitted, and other light is blocked, so the specular reflection direction as well as other directions In order to block the light scattered in the light, when the hologram image is reproduced at this specific angle, it is observed that a clear hologram image with a little excess light is lifted, thereby reliably determining the authenticity. Can That.

The clarity of the image depends on the degree of coincidence between the angle selectivity of the authenticity determination sheet and the reproduction angle of the hologram image. Light that illuminates with a predetermined spread corresponding to the hologram image to be reproduced also has a property of spreading further, and the degree of coincidence changes slightly because the hologram reproduction image also has a spread of the image size. The substantially same width needs to be determined in consideration of these factors. However, with respect to the incident angle α degrees, the reproduction angle β is α ± 5 degrees to ± 25 degrees, and further α ± 5 degrees to ± 10 degrees. Degree is preferred. If it is less than 5 degrees, it will overlap with the incident light, and if it exceeds 25 degrees, it will be blocked by the authenticity judgment sheet. Therefore, the range of 5 degrees to 10 degrees is suitable for clearly viewing the reproduced image.
Such an authenticity determination sheet can be obtained by stacking blazed gratings having the same shape so as to face each other at a predetermined distance. The blaze angle can be arbitrarily set within a range of 10 degrees to 30 degrees, and glass, transparent plastic, etc. can be arbitrarily employed as long as it is a transparent material. In addition, the space may be air, but may be filled with a transparent material having a refractive index different from that of the transparent material constituting the blazed grating.
Since the authenticity determination sheet produced in this way transmits light only at a predetermined angle, the above-mentioned effect is brought about by matching the angle of the reference light and the reproduction light of the hologram image described above to this angle. Can do.

Since the “diffraction grating for reproducing a hologram image” is discrete and formed in various shapes, the above-described authenticity determination sheet cannot open all the portions, and partially However, since it is formed discretely, a “hologram image” can be reproduced with relatively little bias.
Moreover, since it is formed discretely and in various shapes, no matter how much the authenticity identification medium is analyzed, it is theoretically impossible to forge the same medium. It has preventive properties.
The fine pixels are discretely formed, but may be formed so as to display (suggest) some image from the outline when the whole is visually observed. Of course, if this image display is related to a hologram image or the like that appears when the authenticity determination sheet is held over, the authenticity can be immediately identified when the image is displayed.

According to the authenticity identifier of the present invention,
On one surface of the transparent substrate, a surface formed by mixing a hologram relief in which diffraction gratings for reproducing a hologram image are discretely formed in fine pixel units and optical elements different from the diffraction grating are mixed. There is provided an authenticity identifier comprising a transparent resin layer having a reflective thin film layer so as to follow the hologram relief and the optical element forming surface.
Also, according to another authenticity identifier of the present invention,
An authenticity determination sheet for determining authenticity of the authenticity identifier, wherein an angle that transmits light incident on one surface and an angle that transmits light incident on the other surface are substantially the same, It is possible to provide an authenticity determination sheet characterized in that the angle is substantially equal to an incident angle and a diffraction angle of the diffraction grating, and the authenticity determination sheet is superimposed on the authenticity identifier. By observing the hologram image, there is provided an authenticity determination method characterized by determining the authenticity of the authenticity identifier.

These are sectional drawings of the authenticity identification body A which shows one Example of this invention. These are sectional drawings of the authenticity determination sheet | seat B which shows the other Example of this invention. These are authenticity determination methods showing other embodiments of the present invention.

(Transparent substrate)
The transparent substrate 1 used in the present invention can be thinned, and has a mechanical strength and a solvent resistance and a heat resistance that can withstand the processing when manufacturing the authenticity identifier A. Is preferred. Since it depends on the purpose of use, it is not limited, but a film-like or sheet-like plastic is preferable.
For example, various plastic films such as polyethylene terephthalate (PET), polycarbonate, polyvinyl alcohol, polysulfone, polyethylene, polypropylene, polystyrene, polyarylate, triacetyl cellulose (TAC), diacetyl cellulose, and polyethylene / vinyl alcohol can be exemplified. .
The thickness of the transparent substrate 1 is usually 5 to 100 μm, but when considering the sneak light from the reflective thin film layer 3, it is preferably 5 to 50 μm, particularly 5 to 25 μm.

(Transparent resin layer having a surface on which hologram reliefs in which diffraction gratings for reproducing hologram images are discretely formed in fine pixel units and optical elements different from the diffraction gratings are alternately formed)
The hologram relief surface (diffraction grating surface 3 for reproducing the hologram image) in which the diffraction grating for reproducing the hologram image of the present invention is discretely formed in fine pixel units and the optical element surface 4 different from the diffraction grating are provided. Transparent resin layers 2 (hereinafter referred to as hologram forming layers 2) having alternately formed surfaces are formed.
As the transparent resin material, various thermoplastic resins, thermosetting resins, or ionizing radiation curable resins can be used. Thermoplastic resins include acrylic ester resins, acrylamide resins, nitrocellulose resins, or polystyrene resins. Thermosetting resins include unsaturated polyester resins, acrylic urethane resins, epoxy-modified acrylic resins, and epoxy-modified unsaturated resins. A polyester resin, an alkyd resin, a phenol resin, etc. are mentioned.

These thermoplastic resins and thermosetting resins can be used alone or in combination of two or more. One or more of these resins may be cross-linked using various isocyanate resins, or various curing catalysts, for example, metal soap such as cobalt naphthenate or zinc naphthenate may be blended. Or peroxide such as benzoyl peroxide and methyl ethyl ketone peroxide for initiating polymerization with heat or ultraviolet light, benzophenone, acetophenone, anthraquinone, naphthoquinone, azobisisobutyronitrile, or diphenyl sulfide good.
Examples of the ionizing radiation curable resin include epoxy acrylate, urethane acrylate, acrylic-modified polyester, etc., and for the purpose of introducing a crosslinked structure into such an ionizing radiation curable resin or adjusting the viscosity, A monofunctional monomer, a polyfunctional monomer, or an oligomer may be blended and used.
In order to form the hologram forming layer 2 using the above resin material, first, a master having a desired uneven surface is prepared.
To produce the master, the surface of a 100 mm square transparent glass substrate with a thickness of 5 mm is partially dissolved with hydrogen fluoride to form a rough surface having a maximum depth of 3 μm. A photosensitive resin material (photoresist) is coated to a thickness of 10 μm, and using an argon laser, object light and reference light are interfered with each other on the resist surface at a predetermined angle (a diffraction angle during reproduction). To form a latent image of a “diffraction grating that reproduces a hologram image”, and further exposes and develops it using a mask pattern that defines the shape of each region. “Diffraction grating that reproduces a hologram image” The photoresist is left only in the formed portion, and the photoresist is completely removed in the other portions to expose the rough surface of the glass substrate.
For the master that combines the “diffraction grating that reproduces the hologram image” and the “optical element different from the diffraction grating”,
The transparent resin material having a thickness of 20 μm formed on the transparent film substrate having a thickness of 50 μm may be overlapped so as to be in contact with the uneven surface of the master, and the unevenness may be duplicated by heating and pressing. It is preferable to perform molding by using a replica or a plating mold or the like from the master as a replication mold in advance and pressing the mold surface against the layer of the resin material.

When thermosetting resin or ionizing radiation curable resin is used, curing is performed by heating or ionizing radiation irradiation while keeping the uncured resin in close contact with the mold surface, and then cured by peeling after curing. Fine relief of the relief hologram and unevenness of the optical element different from the diffraction grating can be formed on one side of the layer made of a transparent resin material. A diffraction grating forming layer having a diffraction grating formed in a pattern by a similar method can also be used as the optical diffraction structure.
A hologram is a recording of interference fringes due to interference of light between object light and reference light in an uneven relief shape. For example, a laser reproduction hologram such as a Fresnel hologram, a white light reproduction hologram such as a rainbow hologram, There are color holograms utilizing the above principle, computer generated holograms (CGH), holographic diffraction gratings and the like. Further, like a machine readable hologram, the reproduction light may be converted into data by a light receiving unit and transmitted as predetermined information, or authenticity determination may be performed.

In order to precisely create fine irregularities, not only optical methods, but also electron beam lithography equipment can be used to create precisely designed relief structures that produce more precise and complex reproduction light. Good. The relief shape is designed to have a pitch, depth, or specific periodic shape of the unevenness according to the wavelength (range) of the light or light source for reproducing or reproducing the hologram, the direction and the intensity of reproduction or reproduction.
In addition, a color hologram image is formed by a diffraction grating pixel consisting of diffraction grating lines (a minimum unit of a single diffraction grating area consisting of the same diffraction grating line. A set of light emitted from these pixels as diffracted light is one color hologram image. It is also possible to form the image by using an image processing method in which element decomposition is performed and a predetermined pixel size, grid line pitch, and grid line angle are assigned to each element and reproduced.

The pitch (period) of the unevenness depends on the reproduction or reproduction angle, but is usually 0.1 μm to several μm, and the depth of the unevenness is a factor that greatly affects the reproduction or reproduction intensity, but is usually 0.1 μm. ˜1 μm.
Of course, the redundancy of the hologram can be reproduced sufficiently even if the reflected interference light is deleted over a considerable part, and is suitable for the purpose of authenticity determination.
As in the case of a single diffraction grating, when the unevenness of exactly the same shape is repeated, as the adjacent unevenness is the same shape, the degree of interference of reflected light increases and the intensity increases, and the maximum value is reached. Converge. Diffraction in the diffraction direction is also minimized. When a single point of an image converges to a focal point, such as a stereoscopic image, the convergence accuracy to the focal point is improved, and a reproduced or reproduced image becomes clear.
Further, when the reflective thin film layer is a transparent metal compound thin film, the upper and lower surfaces of the thin film have the same relief shape and the distance between the surfaces (that is, the film thickness) is more uniform. , Reproduction or reproduction intensity increases.
The hologram relief shape is shaped (also referred to as replication) by using an original plate on which diffraction gratings and interference fringes are recorded in a concavo-convex shape as a press die (referred to as a stamper), and the transparent substrate 1 and the reflective thin film layer 3. The uneven pattern of the original plate can be duplicated by superimposing the original plate on top of each other and heat-pressing both of them with an appropriate means such as a heating roll. The hologram pattern to be formed may be single or plural.

In order to accurately reproduce the above-mentioned extremely fine shape and to minimize distortion and deformation such as heat shrinkage after replication, the original plate is made of metal and replicated at low temperature and high pressure.
For the original plate, a metal having high hardness such as Ni is used. After a Cr or Ni thin film layer is formed on the surface of a glass master or the like formed by optical imaging or electron beam drawing or the like by vacuum deposition or sputtering, Ni or the like is electrodeposited (electroplating, electroless plating) Further, it can be made by peeling the metal after forming 50 to 1000 μm by composite plating or the like.
The duplication method uses a flat plate type or a rotary type, the linear pressure is 0.1 ton / m to 10 ton / m, and the duplication temperature is usually 60 ° C. to 200 ° C.

(Reflective thin film layer)
In the present invention, the reflective thin film layer 5 is formed on the surface of the hologram forming layer 2. Since this thin film layer needs to reflect incident light, it is not particularly limited as long as it is a thin film layer having a refractive index higher than that of the hologram forming layer 2.
The reflective thin film layer 5 may be a metallic glossy reflective layer such as a metal thin film formed by a vacuum thin film method or the like, or a transparent reflective layer. When provided, it is preferable because the design of the authenticity identification object can be confirmed through the transparent reflective layer. However, a metallic luster reflective film is desirable in the sense of hiding the magnetic pattern.
As a transparent reflective layer, since the optical refractive index is different from that of the hologram forming layer 2 with a substantially colorless and transparent hue, it is possible to visually recognize the glitter of a hologram or the like even though there is no metallic luster, A transparent hologram can be produced. For example, a thin film having a higher refractive index than that of the hologram forming layer 2, such as ZnS, TiO ₂ , Al ₂ O ₃ , Sb ₂ S ₃ , SiO, SnO ₂ , ITO, and the like are available.

Preferably, it is a metal oxide or nitride, specifically, Be, Mg, Ca, Cr, Mn, Cu, Ag, Al, Sn, In, Te, Ti, Fe, Co, Zn, Ge, Pb. Cd, Bi, Se, Ga, Rb, Sb, Pb, Ni, Sr, Ba, La, Ce, Au, and other oxides or nitrides, and the like can be exemplified by a mixture of two or more thereof. Also, a general light-reflective metal thin film such as aluminum can be used as a transparent reflective layer when it has a thickness of 20 nm or less and becomes transparent.
The transparent metal compound is formed on the hologram relief surface of the hologram forming layer 2 by vapor deposition, sputtering, ion plating, CVD (to the thickness of about 10 to 2000 nm, preferably 20 to 1000 nm, similarly to the metal thin film. It may be provided by a vacuum thin film method such as a chemical vapor deposition method. When a transparent reflective film is used, in order to hide the magnetic pattern layer, it is necessary to provide a print layer having the same color tone and to fill a portion without the magnetic layer.

(Adhesive layer)
Further, the authenticity identifier of the present invention can be further labeled with a pressure-sensitive adhesive to form a pressure-sensitive adhesive layer, or a transfer sheet can be coated with an adhesive.
In this case, as the pressure-sensitive adhesive, any conventionally known solvent-based or water-based pressure-sensitive adhesives such as vinyl acetate resin, acrylic resin, vinyl acetate-acrylic copolymer, vinyl acetate-vinyl chloride copolymer, ethylene-acetic acid are used. Examples include vinyl copolymers, polyurethane resins, and rubber resins such as natural rubber and chloroprene rubber.
Natural latex such as natural rubber latex, natural rubber latex obtained by graft polymerization of natural rubber with styrene, especially methacrylic acid methyl, in particular, in order to achieve a natural material composition. What was produced from the raw material may be used and formation thickness, a formation method, etc. are selected suitably.
Moreover, as an adhesive agent, since it is for ensuring the adhesiveness with respect to various articles | goods, the adhesiveness with the reflective thin film layer 5 is good, and what can adhere | attach an adherend firmly is preferable. Specific examples include vinyl chloride resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymer resins, acrylic resins, polyester resins, polyurethane resins, polyamide resins, and rubber-modified products. Appropriately selected from the above can be selected and used, and these can be used alone or in a mixture of two or more, and if necessary, hard resins, plasticizers, and other additives can be added. The formation thickness, the formation method, and the like are appropriately selected.

(Authenticity judgment sheet)
As shown in FIG. 2, the authenticity determination sheet B is prepared by producing a blazed grating master with a predetermined blaze angle (predetermined shape) and a predetermined pitch by a photoresist method, an etching method, a grinding method, etc., and by injection molding or the like. It can be formed into a sheet shape using a material having transparency and durability such as polycarbonate and TAC.
Of course, glass made of glass having excellent optical characteristics and durability is most desirable, but a light plastic material is preferable in consideration of handling as an authenticity determination sheet. Accordingly, the thickness is set to 50 μm to 250 μm.
Using a method of applying ionizing radiation curable resin to a transparent film substrate and transferring a blazed pattern by a sheet molding method, a blazed lattice sheet excellent in mass productivity and durability can be made and this sheet is made to face (FIG. 2). ), And a space between them is filled with a transparent resin adhesive having a different refractive index and cured by ionizing radiation or the like, whereby an authenticity determination sheet can be produced.

(Authenticity judgment method)
As shown in FIG. 3, the authenticity discriminator A is placed over the authenticity judgment sheet B and placed in the “interference space important for hologram reproduction” described above, and the illumination spot light is applied to the blazed grating. When illuminated at the combined angle, the hologram image is reproduced in approximately the same direction of the illuminated angle, so that a predetermined “hologram image 12” appears in that direction, thereby ensuring authenticity. Can be determined.

Example 1
The surface of a transparent glass substrate of 100 mm square with a thickness of 5 mm is roughened by sandblasting (maximum unevenness 5 μm), and a hologram photoresist is coated on the entire surface to a thickness of 10 μm on this surface with argon laser light. Rainbow hologram imaging technology for object light (reflected light from the three-dimensional model of the letter “to”) and reference light on this resist surface at an angle of 10 degrees (incident light 15 degrees−diffracted light 5 degrees = 10 degrees) A mask for masking the formation of a latent image of a hologram image by interfering with each other, and further, as individual regions, having a maximum width of 50 μm to 100 μm and an interval of about 50 μm of random-sized circular regions Overlapping the film, exposing the other areas, developing with a developer, forming a hologram relief only in each area, the other glass substrate A master for reproduction having a rough surface.
Next, a hologram relief is obtained by applying a melamine resin composition to the surface of a 50 μm PET film as the transparent substrate 1 and heating and curing the uneven surface of the replication master having the uneven structure. (Reproducing two hologram images in different directions, “diffraction grating surface 3 for reproducing hologram image”) and a sandblast surface (optical element surface 4 different from the diffraction grating), and forming a hologram forming layer having a thickness of 10 μm 2 was obtained.

On this hologram formation layer 2, AL was vacuum-deposited to form a reflective thin film layer 5 having a thickness of 50 nm, and an authenticity identification medium A of Example 1 was obtained.
Even when observing this authenticity identifier A, it was only a slight rainbow color, and the hologram image could not be visually recognized.
On the reflective thin film layer 5, the following composition is applied with a gravure coater so that the coating amount after drying is 20 μm, and dried at 70 ° C. to form an adhesive layer, which is adhered to a passport. did.
・ <Adhesive composition>
Vinyl acetate-acrylic copolymer 30 parts by mass Toluene 40 parts by mass Vinyl acetate 40 parts by mass A blazed grating master with a blazed angle of 10 degrees and a pitch of 1.0 μm is applied to one surface of a 100 μm thick TAC film. Two blazed lattice sheets having a size of 20 mm, pressed and cured with the sheet sandwiched between them, were aligned with each other in a predetermined position, and overlapped and fixed to produce an authenticity determination sheet B. (The space between the sheets was air.)
When the authenticity determination sheet B was placed over the authenticity identifier A provided on the passport, the hologram images of the object image “NO” could be visually confirmed.
As a result, it was possible to determine that this passport was authentic.

(Example 2)
Example 2 was obtained in the same manner as Example 1 except that random-sized circular areas were formed at intervals of 100 to 150 μm as individual areas.
When observed in the same manner as in Example 1, the anti-counterfeiting property was improved without observing the existence of a holographic image because almost no rainbow color was observed when observing the authentic identifier A.
In the observation with the authenticity determination sheet, the hologram image felt slightly thin, but it was surely visible, and it was possible to determine that this passport was authentic, as in Example 1.
(Comparative example)
A comparative example was obtained by treating the surface of the glass substrate in the same manner as in Example 1 except that the surface was used without being roughened by sandblasting.
When the determination was made in the same manner as in Example 1, it was determined that the hologram image could be visually recognized before the authenticity determination sheet was held over, and it could not be used for anti-counterfeiting purposes.

A Authenticity discriminator B Authenticity determination sheet C Authenticity determination method 1 Transparent substrate 2 Hologram relief in which a diffraction grating for reproducing a hologram image is discretely formed in fine pixel units is different from a diffraction grating Transparent resin layer having surfaces on which optical elements are alternately formed 3 Diffraction grating surface for reproducing hologram image 4 Optical element surface different from diffraction grating 5 Reflective thin film layer 6 Blaze grating sheet 7 Blaze grating surface 8 Blaze grating sheet (Same shape as 6)
9 Incident light 10 Reflected light 11 Authenticity determination sheet 12 Hologram image

Claims (4)

  A hologram relief in which diffraction gratings corresponding to hologram images whose reference light incident direction and reproduction direction are substantially the same are formed on one surface of the transparent base material in units of fine pixels, and a diffraction grating A transparent resin layer having surfaces on which different optical elements are alternately formed, and a reflective thin film layer is provided so as to follow the hologram relief and the optical element forming surface. Authenticity identifier.   The authenticity identifier according to claim 1, wherein the size of each of the alternately formed optical elements is larger than the size of a fine pixel unit of the diffraction grating.     An authenticity determination sheet for determining the authenticity of the authenticity identifier, wherein an angle that transmits light incident on one surface and an angle that transmits light incident on the other surface are substantially the same, The authenticity determination sheet, wherein the angle is substantially equal to an incident angle and a diffraction angle of the diffraction grating.   An authenticity determination method comprising: determining the authenticity of the authenticity identifier by superimposing the authenticity determination sheet on the authenticity identifier and observing the hologram image.

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