JP2004029189A - Optical phase conversion body, light selecting/transmitting body, method and system for visualizing latent image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical phase conversion body, a light selecting/transmitting body and an authenticity decision system which have a high forgery prevention effect, and can easily decide authentic articles. <P>SOLUTION: The optical phase conversion body is provided with a phase conversion layer 11 having optical anisotropy and for transmitting light of specified polarization components and changing the phase of the transmitted light in accordance with the optical path length of the transmitted light, the phase conversion layer 11 is provided with a rugged part 11a formed to a shape of a prescribed pattern on one surface so as to change the optical path length of the transmitted light, the rugged part is an optical diffraction structure part for diffracting the transmitted light. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is used to determine whether or not an object such as securities, stock certificates, gift certificates, etc., various cards such as credit cards, prepaid cards, passports, etc., video software, personal computer software, etc. is genuine. The present invention relates to a suitable optical phase converter, light selective transmission body, latent image viewing system, and latent image viewing method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a method of preventing forgery of credit cards, certificates, and vouchers, a method of attaching an authenticity determination body that is difficult to forge to a forgery prevention target and visually or mechanically determining the authenticity thereof is known. Have been. Such authenticity determination bodies include, for example, those using holograms, such as those for visually distinguishing characters and pictures as hologram images, and those for machine recognition of numerical codes and specific patterns as hologram images. And a combination of both. Hologram images are widely used because they are beautiful in appearance and excellent in design, are not copyable with a normal color copying apparatus or the like, are effective in preventing forgery, and are difficult to manufacture.
[0003]
[Problems to be solved by the invention]
However, with the spread of hologram manufacturing technology in recent years, it has become possible to manufacture counterfeit products, and the anti-counterfeiting effect has been reduced, and a new anti-counterfeiting method has been demanded.
[0004]
An object of the present invention is to provide an optical phase converter, a light selective transmission body, a latent image viewing system, and a latent image viewing method, which have a high anti-counterfeiting effect and can easily determine a genuine product.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a phase conversion device that has optical anisotropy, transmits light having a specific polarization component, and changes the phase of the transmitted light according to the transmitted optical path length. An optical phase converter comprising a layer, wherein the phase conversion layer is formed in a predetermined pattern on one surface, and has an uneven portion that changes a transmission optical path length of the transmission light. It is a converter.
[0006]
A second aspect of the present invention is the optical phase converter according to the first aspect, wherein the uneven portion is an optical diffraction structure that diffracts the transmitted light.
[0007]
A third aspect of the present invention is the optical phase changer according to the first or second aspect, wherein the concave and convex portions are formed of hologram reliefs.
[0008]
According to a fourth aspect of the present invention, in the optical phase changer according to any one of the first to third aspects, a surface of the phase conversion layer having an uneven portion has a surface opposite to the uneven portion. An optical phase converter comprising a light transmitting layer formed so as to be flat and having a refractive index difference of 1 or less from the phase conversion layer and transmitting light transmitted through the phase conversion layer. is there.
[0009]
According to a fifth aspect of the present invention, in the optical phase converter according to any one of the first to fourth aspects, a reflection layer formed on the light transmission layer and reflecting light transmitted through the light transmission layer. An optical phase changer comprising:
[0010]
According to a sixth aspect of the present invention, there is provided a polarization filter layer for transmitting light having a specific polarization state among incident light, and a phase formed on the polarization filter layer for imparting a phase difference to polarized light transmitted through the polarization filter layer. And a phase conversion layer, wherein the polarization filter layer and the phase conversion layer are combinations in which transmitted light is in a circularly polarized state.
[0011]
According to a seventh aspect of the present invention, there is provided a light having the optical phase converter according to any one of the first to fifth aspects, and a polarization filter layer that transmits light having a specific polarization state among incident lights. And a selective transmission body.
[0012]
According to an eighth aspect of the present invention, there is provided the optical phase changer according to any one of the first to fifth aspects, and a light selective transmission body including a phase conversion layer that imparts a phase difference to transmitted polarized light. A latent image visualization system that performs visual recognition of a latent image using the optical phase changer having a first phase change layer, and the light selective transmission body having a second phase change layer. A latent image viewing system, characterized in that there are at least two or more regions having different sums of phase amounts converted when the light passes through the first and second phase conversion layers.
[0013]
According to a ninth aspect of the present invention, in the latent image viewing system according to the eighth aspect, the first and second phase conversion layers have a phase difference of π / 4. This is an image recognition system.
[0014]
According to a tenth aspect of the present invention, when light emitted from the optical phase converter according to any one of the first to fifth aspects is viewed through the light selective transmission body according to the sixth aspect, This method is a method for visually recognizing a latent image, in which when a predetermined pattern is visible, the optical phase converter is determined to be a genuine product.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings and the like.
(1st Embodiment)
FIG. 1 is a diagram showing a first embodiment of an optical phase conversion label according to the present invention, wherein FIG. 1 (A) is a plan view, and FIG. 1 (B) is a sectional view taken along line BB of FIG. 1 (A). .
The optical phase conversion label 10 includes a phase conversion layer 11, a light transmission layer 12, a reflection layer 13, and an adhesive layer 14.
The phase conversion layer 11 is a layer that has optical anisotropy and changes the phase by birefringence of transmitted light.
Here, birefringence is a phenomenon that occurs because the refractive index of a medium is not uniform depending on the polarization direction, and the phase difference σ of light transmitted through such a medium is
σ = 2π (n _e -N _o ) D / λ
n _e ： Ordinary ray refractive index
n _o : Extraordinary ray refractive index
d: thickness of the medium
λ: wavelength of light
And is known to be given. That is, the phase difference σ depends on the thickness of the medium, that is, the optical path length when light is transmitted.
[0016]
The phase conversion layer 11 can be formed of a plastic film produced in a stretching step. Stretching is a method for producing a film by stretching a plastic at an appropriate temperature from the melting point to the glass transition point or more, and includes uniaxial stretching and biaxial stretching depending on the stretching direction. In the present invention, a film produced by any of uniaxial stretching and biaxial stretching can be used, as long as it has a refractive index anisotropy.
Specifically, the phase conversion layer 11 is formed of a polymer film (for example, a polyethylene resin, a polypropylene resin, a polymethylpentene resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polyvinyl alcohol resin, a vinyl chloride-vinyl acetate copolymer resin). , Ethylene-vinyl acetate copolymer resin, ethylene-vinyl alcohol copolymer resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate-isophthalate copolymer resin, polymethyl methacrylate resin, polycarbonate resin, polyarylate resin, polyimide Resin, polysulfone resin, etc.).
[0017]
Further, the phase conversion layer 11 may be formed using a material such as liquid crystal that can control the alignment. In this case, a film that changes the phase is formed by forming it on a substrate whose orientation is controlled by a method such as rubbing treatment, chemical treatment, or optical treatment.
On one surface (the lower surface in FIG. 1) of the phase conversion layer 11, an uneven portion 11a is formed in a predetermined pattern. In the present embodiment, the concavo-convex portions 11a are formed in a “◎” shape. The optical path length of the light transmitted through the phase conversion layer 11 is different depending on the uneven portion 11a, and the phase difference σ of the light is changed. Details will be described later.
[0018]
The light transmission layer 12 is provided on the surface of the phase conversion layer 11 on which the uneven portions 11 a are formed, and is a layer that transmits light that has passed through the phase conversion layer 11. The difference between the refractive index of the light transmitting layer 12 and the refractive index of the phase conversion layer 11 is 1 or less, and light transmitted through the phase conversion layer 11 is transmitted with almost no refraction. Therefore, it becomes difficult to recognize the presence of the uneven portion 11a. The light transmission layer 12 does not change the phase of transmitted light, unlike the phase conversion layer 11.
[0019]
Such materials include, for example, polyethylene [polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), vinyl chloride-vinyl acetate copolymer], polypropylene (PP), vinyl [polyvinyl chloride ( PVC), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyvinylidene chloride (PVdC), polyvinyl acetate (PVAc), polyvinyl formal (PVF)], polystyrene [polystyrene (PS), styrene-acrylonitrile copolymer (AS), acrylonitrile-butadiene-styrene copolymer (ABS)], acrylic [polymethyl methacrylate (PMMA), MMA-styrene copolymer], polycarbonate (PC), cellulose (ethyl cellulose (EC), cellulose acetate (C ), Propylcellulose (CP), acetic acid / cellulose acetate (CAB), cellulose nitrate (CN)], fluorine type [polychlorofluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoroethylene Copolymer (FEP), polyvinylidene fluoride (PVdF)], urethane (PU), nylon (type 6, type 66, type 610, type 11), polyester (alkyd) type (polyethylene terephthalate (PET), Polybutylene terephthalate (PBT), polycyclohexane terephthalate (PCT)], and thermoplastic resins such as novolak type phenol resins. It is also possible to use thermosetting resins such as resol type phenolic resins, urea resins, melamine resins, polyurethane resins, epoxies, unsaturated polyesters, and natural resins such as proteins, rubber, shellac, copal, starch, and rosin. it can.
[0020]
Further, these resins can be emulsions for waterborne coatings. Examples of emulsions for aqueous coatings include vinyl acetate (homo) emulsion, vinyl acetate-acrylate copolymer emulsion, vinyl acetate-ethylene copolymer resin emulsion (EVA emulsion), and vinyl acetate-vinyl versatate copolymer resin emulsion. , Vinyl acetate-polyvinyl alcohol copolymer resin emulsion, vinyl acetate-vinyl chloride copolymer resin emulsion, acrylic emulsion, acrylic silicone emulsion, styrene-acryl copolymer resin emulsion, polystyrene emulsion, urethane emulsion, chlorinated polyolefin emulsion, epoxy-acrylic dispersion John or SBR latex can be used.
[0021]
The reflection layer 13 is a thin film layer that reflects light transmitted through the light transmission layer 12, and is formed on the light transmission layer 12. The reflective layer 13 is desirably flat so that transmitted light can be uniformly reflected. The material of the reflective layer 13 includes aluminum (Al), zinc (Zn), indium (In), gold (Au), silver (Ag), cobalt (Co), tin (Sn), selenium (Se), titanium ( Simple metals such as Ti), iron (Fe), tellurium (Te), copper (Cu), lead (Pb), nickel (Ni), and palladium (Pd), or alloys thereof.
Examples of a method for forming the thin film of the reflective layer 13 include a thin film forming method such as a vacuum evaporation method, a sputtering method, and an ion plating method. The thin film may be set under appropriate conditions depending on the color tone, design, application, and the like, but preferably has a range of 5 to 1000 nm, and more preferably 10 to 100 nm.
[0022]
The adhesive layer 14 is a layer for attaching the optical phase conversion label 10 to an adherend such as a gift certificate. Examples of the material of the adhesive layer 14 include an acrylic resin, an acrylate resin, a copolymer thereof, a styrene-butadiene copolymer, a natural rubber, a casein, a gelatin, a rosin ester, a terpene resin, a phenol resin, and a styrene resin. , Chroman indene resin, polyvinyl ether, silicone resin, etc.Also, alpha-cyanoacrylate adhesive, silicone adhesive, maleimide adhesive, styrene adhesive, polyolefin adhesive, resorcinol adhesive, polyvinyl ether adhesive Adhesives, silicone-based adhesives and the like can be mentioned. When such a material is used, a release paper 14a (see FIG. 2) may be temporarily adhered to the adhesive layer 14 in order to prevent inadvertent adhesion before sticking to the adherend. . As the release paper 14a, a conventionally known release paper obtained by subjecting a paper or film base material to a release treatment may be used.
The adhesive layer 14 may use a heat sealant. Examples of such a heat sealant include ethylene-vinyl acetate copolymer resin, polyamide resin, polyester resin, polyethylene resin, ethylene-isobutyl acrylate copolymer resin, butyral resin, polyvinyl acetate and its copolymer resin, cellulose derivative, Examples thereof include a polymethyl methacrylate resin, a polyvinyl ether resin, a polyurethane resin, a polycarbonate resin, a polypropylene resin, an epoxy resin, a phenol resin, a thermoplastic elastomer such as SBS, SIS, SEBS, and SEPS, or a reactive hot melt resin. .
Note that the thickness of the adhesive layer 14 is preferably 3 μm to 20 μm.
[0023]
FIG. 2 is a diagram illustrating a case where the optical phase conversion label is used as a transfer seal. The optical phase conversion label 10 is used, for example, as a transfer seal. In this case, the release layer 21 is formed on the support sheet 20, and the phase conversion layer 11, the light transmission layer 12, and the like are sequentially laminated thereon to manufacture the optical phase conversion label 10. . At this time, the support sheet 20 needs to have heat resistance and solvent resistance enough to withstand the production of the optical phase conversion label 10. Further, in the case of a type in which the optical phase conversion label 10 is thermally transferred to an adherend such as a gift certificate, heat resistance that can withstand the heat is required. Examples of a material having such performance include a biaxially stretched polyethylene terephthalate film (PET film). When such a PET film is used, its thickness is preferably from 5 to 250 µm, and more preferably from 10 to 50 µm in consideration of workability, tensile strength, thermal efficiency at the time of thermal transfer, and the like.
[0024]
The release layer 21 is formed from an acrylic skeleton resin, a vinyl chloride-vinyl acetate copolymer, a mixture of cellulose acetate and a thermosetting acrylic resin, a melamine resin, a nitrocellulose resin, and a polyethylene wax. It is preferable that the resin is a main component. In addition, a polyester resin or the like may be used to adjust the adhesive force with the support sheet 20. Further, wax and a silicon-based resin may be added in order to improve the releasability. The release layer 21 is formed by applying a coating solution obtained by dissolving or dispersing the above resin in an appropriate solvent to the support sheet 20 by a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate. It is formed by coating and drying. The thickness after drying is 0.1 to 10 μm.
[0025]
The discriminator 40 (see FIG. 3) is a polarizing film that allows light of a specific polarization state to pass. As such a discriminating tool 40, for example, a device in which a linear polarizing film layer 41 and a λ / 4 retardation film layer 42 are laminated can be used. When the natural light is incident, the discriminator 40 converts the natural light into circularly polarized light. Specific usage will be described later.
The linearly polarizing film layer 41 is a film layer that transmits only linearly polarized light L2 having a specific polarization direction in the light L1 of the light source (see FIG. 3). The linearly polarizing film layer 41 can be formed of a polarizing film or sheet in which a stretched film such as polyvinyl alcohol (PVAL) has absorbed a dye such as a dichroic dye.
The λ / 4 retardation film layer 42 is a layer that imparts λ / 4 retardation by birefringent incident light. If such a λ / 4 retardation film layer 42 is used, the linearly polarized light L2 can be converted into the circularly polarized light L3 (see FIG. 3). As the λ / 4 retardation film layer 42, the same one as the above-mentioned phase conversion layer 11 can be used. However, the thickness is adjusted so that a phase difference of λ / 4 can be given to the transmitted light.
[0026]
FIG. 10 is a diagram illustrating the principle of visualizing the optical phase converter according to the present embodiment.
The combination of the linear polarization film layer 41 and the phase conversion layer 11 provides the following two types of phase amounts σ given by the phase conversion layer 11, and the combination with the reflection layer 13 reflects and blocks incident light. The principle will be described.
σ _A = (Π / 2) · (2n-1) (A)
σ _B = Π · n (B)
Where n is a natural number
[0027]
The condition in this case is that the angle between the ordinary ray axis of the phase conversion layer 11 and the extraordinary ray axis is 90 degrees (π / 2), and the orientation of the linear polarizing film layer 41 is the ordinary ray of the phase conversion layer 11. It is assumed that there is a positional relationship of 45 degrees (π / 4) located in the middle between the axis and the extraordinary ray axis.
Here, in the phase conversion layer 11, as shown in FIG. 10A, a portion having the relationship (A) is defined as a region A and a portion having the relationship (B) is defined as a region B. In the region A, the polarization component in the x direction is different from the polarization component in the y direction in the phase amount σ of the above (A). _A In the region B, the polarization component in the x direction is different from the polarization component in the y direction in the phase amount σ of the above (B). _B Just go forward.
In addition, the linear polarization film layer 41 has a polarization direction of 45 degrees as shown in FIG.
Then, as shown in FIG. 10C, the linear polarization film layer 41, the phase conversion layer 11, and the reflection layer 13 are arranged, and the polarization state of each part will be described.
[0028]
FIG. 11 is a diagram illustrating the polarization state of the region A in FIG.
Here, the amplitude in the x direction and the y direction with respect to time (t) is exemplified by a sine wave (in the figure, a triangular wave is used), and n = 1.
As shown in FIG. 11A, in the state of (1) in FIG. 10C, the direction of the linear polarizing film layer 41 is located at an intermediate position between the ordinary ray axis and the extraordinary ray axis of the phase conversion layer 11. Since there is a positional relationship of 45 degrees (π / 4) (see FIG. 11E), linearly polarized light having the same amplitude and the same phase in both directions x and y.
As shown in FIG. 11B, in the state (2) of FIG. 10C, due to the anisotropy of the phase conversion layer 11, the phase in the x direction advances by π / 2, and becomes circularly polarized light.
As shown in FIG. 11C, in the state of (3) in FIG. 10C, the phase is advanced by π (inverted) in the x direction and the y direction by the reflective layer 13 but remains circularly polarized.
As shown in FIG. 11D, in the state of (4) in FIG. 10C, the phase in the x direction is further advanced by π / 2, and becomes linearly polarized light in the opposite phase to the y direction component. The direction becomes orthogonal to the film layer 41 (see FIG. 11 (f)), the light cannot pass through the linearly polarizing film layer 41, and the reflected light is blocked.
[0029]
FIG. 12 is a diagram illustrating the polarization state of region B in FIG.
As shown in FIG. 12A, in the state of (1) in FIG. 10C, the direction of the linear polarizing film layer 41 is located at an intermediate position between the ordinary ray axis and the extraordinary ray axis of the phase conversion layer 11. Since there is a positional relationship of degrees (π / 4) (see FIG. 12E), linearly polarized light having the same amplitude and the same phase in both x and y directions.
As shown in FIG. 12 (b), in the state (2) of FIG. 10 (c), the phase in the x direction advances by π and becomes linearly polarized light in the direction opposite to the y direction component.
As shown in FIG. 12C, in the state of (3) in FIG. 10C, the phase is advanced by π (inverted) in the x direction and the y direction by the reflective layer 11, but remains linearly polarized light.
As shown in FIG. 12D, in the state (4) of FIG. 10C, the phase in the x direction advances by π again, becomes linearly polarized light in phase with the y direction, becomes the same linearly polarized light as incident light, and becomes linearly polarized. The direction becomes parallel to the polarizing plate 11 (see FIG. 12F), and the reflected light passes through the linear polarizing film layer 41.
[0030]
From the above results, since the reflected light is blocked in the area A and the reflected light is transmitted in the area B, the difference between the area A and the area B can be visually observed.
Here, when the amount of phase change in the phase conversion layer 11 is other than the above, the reflected light becomes elliptically polarized light (it becomes circularly polarized light depending on conditions), and the shape differs depending on the amount of phase change. Further, since the amount of light transmitted through the linear polarizing film layer 41 depends on the shape of the elliptically polarized light, the difference in the amount of phase change can be visually observed through the linear polarizing film layer 41.
[0031]
FIG. 3 is a diagram illustrating a state in which the latent image recognition system according to the present embodiment cannot be visually recognized.
The relationship between the linearly polarizing film layer 41 and the λ / 4 retardation film layer 42 requires a condition for L3 to be circularly polarized. Specifically, the polarization angle of the linearly polarizing film layer 41 is λ There is a 45 ° (π / 4) positional relationship between the ordinary ray axis and the extraordinary ray axis of the / 4 retardation film layer 42. However, the ordinary ray axis and the extraordinary ray axis at this time are in an orthogonal relationship. The phase amount of the phase conversion layer 11 satisfies the relationship (A).
[0032]
FIG. 4 is a diagram illustrating a visible state of the latent image viewing system according to the present embodiment.
As in FIG. 3, the relationship between the linear polarizing film layer 41 and the λ / 4 retardation film layer 42 requires a condition for L3 to be circularly polarized. Is in a positional relationship of 45 degrees (π / 4), which is located between the ordinary ray axis and the extraordinary ray axis of the λ / 4 retardation film layer 42. However, the ordinary ray axis and the extraordinary ray axis at this time are in a parallel relationship. The phase amount of the phase conversion layer 11 satisfies the relationship (B).
[0033]
As described above, when the optical phase converter 10 and the discriminator 40 are overlapped, the latent image recorded on the optical phase converter 10 can be viewed. The point of this embodiment that effectively realizes the principle is:
(1) The phase conversion layer (11, 41) is divided into two layers, that is, the optical phase converter 10 side and the discriminator 40 side. More than one,
(2) converting the light passing through the discrimination tool 40 into circularly polarized light;
The two.
[0034]
Due to the configuration in which at least two or more regions having different phase amounts exist according to the condition (1), when the optical phase converter 10 and the discriminator 40 are overlapped, there is a difference in the amount of reflected light. One area is generated, and the latent image can be visually confirmed.
However, it is most effective when the difference between the phase amounts is π / 4 and the difference between the reflected lights is maximum. Therefore, not only is the phase amount different, but in the present embodiment, the difference between the reflected lights is , The phase amount corresponding to 最大 of the maximum is π / 8 or more, which is more preferable.
[0035]
Under the condition (2), if the light passing through the discrimination tool 40 is circularly polarized, the restriction on the relative angle between the optical phase converter 10 and the discrimination tool 40 can be eliminated.
That is, if the light in the state (1) of FIG. 10C that has passed through the discriminator 40 is in a circularly polarized state, the relative angle between the discriminator 40 and the optical phase converter 10 is not restricted. Has the effect that the latent image can be confirmed.
A specific condition for realizing this condition is that the direction of the polarization angle of the linear polarizing film layer 41 of the discriminator 40 is 45 degrees, which is located between the ordinary ray axis and the extraordinary ray axis of the phase conversion layer 11 ( (π / 4).
When the discriminator 40 is composed of only the linearly polarizing film layer, the relative angle between the discriminator 40 and the optical phase converter 10 is limited, but the region where the phase amount of the optical phase converter 10 is different is limited. When there are at least two or more, the latent image can be viewed on the same principle.
[0036]
FIG. 5 is a schematic cross-sectional view when a genuine product is determined.
FIG. 6 is a diagram illustrating a method of determining a genuine product.
As shown in FIG. 6A, even if the optical phase conversion label 10 is visually observed without using the discriminator 40, characters and symbols cannot be recognized.
Next, when the discriminator 40 is overlaid, a predetermined pattern (in this embodiment, “◎”) becomes visible on the optical phase conversion label 10 as shown in FIG. 6B.
This allows the judge to know that the optical phase conversion label 10 is a genuine product.
On the other hand, a third party who does not have the discriminator 40 cannot recognize characters, symbols, and the like in the optical phase conversion label 10, and cannot recognize that the label is a special label.
[0037]
According to the present embodiment, since the uneven portion 11a is formed on the phase conversion layer 11, the incident light is converted into polarized light having a different state depending on the transmission position. The authenticity can be easily determined by viewing the polarized light through the discriminator 40.
In addition, since this polarized light cannot be understood only by visual inspection, a third party cannot realize that it is a special label.
Furthermore, since the light transmitting layer 12 is provided, the existence of the uneven portion 11a is not known to a third party.
[0038]
(2nd Embodiment)
7A and 7B are diagrams showing a second embodiment of the optical phase conversion label according to the present invention, wherein FIG. 7A is a plan view, and FIG. 7B is a cross-sectional view taken along the line BB of FIG. 7A. .
In the following, portions that perform the same functions as in the first embodiment described above are denoted by the same reference numerals, and redundant description will be omitted as appropriate.
The uneven portion 11a of the phase conversion layer 11 of the present embodiment has fine unevenness and can diffract light. As a result, the reflected light changes, and the design is excellent.
If the uneven portion 11a is manufactured using a hologram-forming relief, very fine unevenness can be formed, so that it looks like a hologram image and is very beautiful.
[0039]
According to the present embodiment, since the light can be diffracted by the concave and convex portions 11a finely formed on the phase conversion layer 11, the reflected light looks rainbow-colored and is very beautiful. In particular, if the uneven portion 11a is manufactured using a hologram-forming relief, it looks like a hologram image and is very beautiful.
[0040]
(Third embodiment)
FIG. 8 is a sectional view showing a third embodiment of the optical phase conversion label according to the present invention. The optical phase conversion label 10 of the present embodiment has a phase conversion layer 11, but differs from the first embodiment in that it does not include the light transmission layer 12, the reflection layer 13, and the adhesive layer 14.
The phase conversion layer 11 has an uneven portion 11a.
[0041]
FIG. 9 is a diagram illustrating a method of determining the authenticity of an optical phase conversion label according to a third embodiment of the present invention.
In the present embodiment, the authenticity determination is performed by sandwiching the optical phase conversion label 10 in a sandwich shape with the two discriminators 40 and holding the optical phase conversion label 10 over the light source.
The natural light L1 of the light source is converted by the linear polarizing film layer 41 into linearly polarized light L2 in the vertical direction, and is converted by the λ / 4 retardation film layer into circularly polarized light L3.
Subsequently, the circularly polarized light L3 has an optical path length d. ₃ While passing through the phase conversion layer 11, the phase is further imparted and converted into circularly polarized light L43.
The circularly polarized light L43 is converted into linearly polarized light by the λ / 4 retardation film layer 42, but the linearly polarized light cannot pass through the linearly polarized film layer 41. Therefore, the participant will see that part in black.
[0042]
The natural light L1 of the light source is converted into linearly polarized light L2 by the linearly polarizing film layer 41, and converted into circularly polarized light L3 by the λ / 4 retardation film layer 42, and has an optical path length d. ₄ While passing through the phase conversion layer 11, the phase is further given and converted into circularly polarized light L44. This circularly polarized light L44 is converted into linearly polarized light L54 by the λ / 4 retardation film layer 42.
The discriminator can visually observe the linearly polarized light L53, and can confirm the “◎ ×” pattern on the optical phase conversion label 10. Thereby, the determiner can determine that the optical phase conversion label 10 is genuine.
[0043]
Also according to the present embodiment, it is possible to easily determine the authentic product.
Further, since the optical phase conversion label 10 has a small number of layers, it can be manufactured at low cost.
Further, since this polarized light cannot be seen only by visual inspection, a third party cannot realize that it is a special label.
[0044]
(Modified form)
Various modifications and changes are possible without being limited to the embodiment described above, and these are also within the equivalent scope of the present invention.
For example, in the second embodiment, the same light transmitting layer 12 as that of the first embodiment may be provided, so that it is difficult to understand that the unevenness 11a is formed on the phase conversion layer 11. Can be.
[0045]
【The invention's effect】
As described above in detail, according to the present invention, the following effects can be obtained.
(1) By viewing the light converted by the phase conversion layer 11 through the discriminator 40, the authenticity can be easily determined.
(2) If the discriminator 40 is not used, the light converted by the phase conversion layer 11 looks uniform, so that a third party cannot realize that the optical phase conversion label 10 is a special label.
(3) If the light transmission layer 12 is formed on the phase conversion layer 11, the existence of the uneven portion 11a will not be known to a third party.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of an optical phase conversion label according to the present invention.
FIG. 2 is a diagram illustrating a case where an optical phase conversion label is used as a transfer seal.
FIG. 3 is a schematic diagram illustrating a method for determining the authenticity of the optical phase conversion label according to the first embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating a method for determining the authenticity of an optical phase conversion label according to the first embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view when a genuine product is determined.
FIG. 6 is a diagram illustrating a method of determining a genuine product.
FIG. 7 is a diagram showing a second embodiment of the optical phase conversion label according to the present invention.
FIG. 8 is a sectional view showing a third embodiment of the optical phase conversion label according to the present invention.
FIG. 9 is a diagram illustrating a method for determining the authenticity of an optical phase conversion label according to a third embodiment of the present invention.
FIG. 10 is a diagram illustrating the principle of visualization of the optical phase converter according to the present embodiment.
FIG. 11 is a diagram illustrating a polarization state of a region A in FIG.
FIG. 12 is a diagram illustrating a polarization state of a region B in FIG.
[Explanation of symbols]
10. Optical phase conversion label
11 Phase conversion layer
11a Uneven part
12 Light transmission layer
13 Reflective layer
14 Adhesive layer
20 Support sheet
40 discriminator
41 Linear polarizing film layer
42 λ / 4 retardation film layer

Claims (10)

An optical phase converter having an optical anisotropy, transmitting light of a specific polarization component, and including a phase conversion layer that changes the phase of the transmitted light according to the transmitted optical path length,
The phase conversion layer is formed in a predetermined pattern on one surface, and has an uneven portion that changes a transmitted light path length of the transmitted light, and the uneven portion is a light diffraction structure that diffracts the transmitted light. An optical phase converter, characterized in that: The optical phase converter according to claim 1,
The optical phase converter, wherein the uneven portion is a light diffraction structure that diffracts the transmitted light. The optical phase converter according to claim 1 or 2,
The optical phase converter, wherein the uneven portion is formed of a hologram relief. The optical phase converter according to any one of claims 1 to 3,
The surface of the phase conversion layer having the uneven portion is formed so that the surface on the opposite side to the uneven portion is flat, and the refractive index difference from the phase conversion layer is 1 or less. An optical phase converter comprising a light transmitting layer that transmits transmitted light. The optical phase converter according to any one of claims 1 to 4,
An optical phase changer comprising: a reflection layer formed on the light transmission layer and reflecting light transmitted through the light transmission layer. Among the incident light, a polarization filter layer that transmits light in a specific polarization state,
A phase conversion layer formed on the polarization filter layer and imparting a phase difference to polarized light transmitted through the polarization filter layer,
The polarization filter layer and the phase conversion layer, a combination that the transmitted light is in a circular polarization state,
A light selective transmission body characterized by the following. An optical phase converter according to any one of claims 1 to 5,
Of the incident light, a light selective transmission body including a polarization filter layer that transmits light in a specific polarization state,
A latent image recognition system comprising: An optical phase converter according to any one of claims 1 to 5,
A light selective transmission body including a phase conversion layer that imparts a phase difference to transmitted polarized light,
A latent image recognition system that performs visual recognition of a latent image using
The optical phase changer has a first phase change layer,
The light selective transmission body has a second phase change layer,
A latent image viewing system, wherein at least two or more regions having different sums of phase amounts converted when transmitted through the first and second phase conversion layers are present. The latent image viewing system according to claim 8, wherein
The latent image viewing system according to claim 1, wherein the first and second phase conversion layers have a phase difference of π / 4. When the light emitted from the optical phase converter according to any one of claims 1 to 5 is viewed through the light selective transmission body according to claim 6, the predetermined pattern is visible. A method of visually recognizing a latent image when the optical phase converter is genuine.

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