JP4236853B2 - Authenticity judgment system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention card, gift certificates, cash vouchers, tickets, paper money, passport, identity card, securities, about the true positive determination system object you determine whether or not it is genuine, such as public sports betting ticket .
[0002]
[Prior art]
Conventionally, as a method for preventing counterfeiting of credit cards, certificates, and vouchers, there has been known a method in which an authenticity judgment body that is difficult to forge is pasted on an anti-counterfeit object and the authenticity is visually or mechanically determined. It has been. Examples of such authenticity determination bodies include those using holograms, which include machine-recognition using characters and pictures as hologram images and visual discrimination, numerical codes and specific patterns as hologram images. And combinations of both. Hologram images have become widespread because they cannot be duplicated by a normal color copying apparatus or the like, are effective in preventing forgery, have high designability, and are difficult to manufacture.
[0003]
[Problems to be solved by the invention]
However, with the popularization of hologram manufacturing technology in recent years, it has become possible to manufacture counterfeit products, the effect of preventing forgery has been reduced, and a new method of preventing forgery has been demanded.
[0004]
An object of the present invention, anti-counterfeiting effect is high, and the presence of anti-counterfeiting means to provide a leucine positive determination system of Satoraru it to others.
[0005]
[Means for Solving the Problems]
The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this .
[0015]
In order to solve the above problems, the invention of claim 1 is formed of a liquid crystal layer in which a cholesteric phase is fixed, reflects light (L1) in a first polarization state out of incident light, and The first light selective reflection part (11a) that transmits the light (L2) in the polarization state and the liquid crystal layer in which the cholesteric phase is fixed, and reflects the light (L2) in the second polarization state. The second light selective reflection part (11b) that transmits the light (L1) in the polarization state and the liquid crystal layer in which the cholesteric phase is fixed are heated to have reflection characteristics that do not depend on the polarization state. A non-selective reflection portion (11c) disposed in a region other than the first light selective reflection portion (11a) and the second light selective reflection portion (11b), and the first light selective reflection portion ( 11a) and is formed on the second light selective reflection portion (11b), before Light in which the first light selective reflection section (11a) and the second light selective reflection section (11b) selectively reflect light having the same polarization state as the reflected light to generate a light diffraction phenomenon. An authenticity determination system for determining authenticity using a light selective reflector (10) comprising a diffractive structure forming part (12), wherein light from a light source (21) is converted to light in a first polarization state The light converted by the first polarization forming means (24a) for conversion and the light from the light source (21) converted by the second polarization formation means (24b) for converting light into the second polarization state light When the first light selective reflection part (11a) and the second light selective reflection part (11b) of the light selective reflector (10) are alternately irradiating with light, and are not visible. The light selective reflector (10) is determined to be genuine. It is a positive determination system.
According to a second aspect of the present invention, in the authenticity determination system according to the first aspect, the first polarization forming means (24a) and the second circular polarization means (24b) convert light (L3) into linearly polarized light (L4). And a linear polarization means (22) for converting the linear polarization (L4) into a circular polarization (L5), and circularly polarized light (L5) having a specific polarization state. ) Is converted into a genuineness determination system.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a view showing a first embodiment of a light selective reflection label according to the present invention, FIG. 1 (A) is a plan view, and FIG. 1 (B) is a sectional view taken along line BB in FIG. 1 (A). .
The light selective reflection label 10 is a light selective reflector including a light selective reflection layer 11.
[0017]
The light selective reflection layer 11 is a light selective reflection film layer that selectively reflects or transmits incident circularly polarized light. The light selective reflection layer 11 of this embodiment is formed of a cholesteric liquid crystal liquid crystal film having a right twist structure. At this time, the light selective reflection layer 11 transmits the left circularly polarized light and reflects the right circularly polarized light.
[0018]
Next, the cholesteric liquid crystal will be described.
FIG. 2 is a schematic diagram showing the structure of the cholesteric liquid crystal in the reflective layer.
The cholesteric liquid crystal C has a regular twist so that the alignment structure of the liquid crystal molecules draws a spiral in the film thickness direction (FIG. 2). A cholesteric liquid crystal has two optical properties, wavelength selective reflectivity and circular polarization selectivity, when the pitch P (the film thickness necessary for the liquid crystal molecules to rotate 360 °) and the wavelength λ of incident light are substantially equal. Show properties.
[0019]
Here, the wavelength selective reflectivity is a property of strongly reflecting light within a specific wavelength band and transmitting other light among incident light. Since this wavelength selective reflectivity is limitedly expressed within a specific wavelength band, the reflected light becomes a chromatic color with high color purity by appropriately selecting the pitch P of the cholesteric liquid crystal. Λs the center wavelength of the band, if the bandwidth [Delta] [lambda], these are the pitch P of the optical medium (= λ / n _m) and the average refractive index _{n m (= √ ((n} e 2 + n o 2) / 2)) and the following equations (1) and (2). Here, [Delta] n is the difference between the extraordinary ray refractive index n _e and ordinary index n _o in the plane of the optical medium _{(Δn = n e -n o)} .
λs = n _m · P (1)
Δλ = Δn · P / n _m (2)
[0020]
The center wavelength λs and the wavelength bandwidth Δλ shown in the expressions (1) and (2) are the cases where the incident light to the cholesteric liquid crystal layer is perpendicularly incident (0 ° incidence, on-axis incidence). In the case of oblique incidence (off-axis incidence), since the pitch P apparently decreases, the center wavelength λs shifts to the short wavelength side, and the bandwidth Δλ decreases. This phenomenon is called blue shift because λs shifts to the short wavelength side, and the shift amount depends on the incident angle, but can be easily identified visually. For example, the reflected color of a cholesteric liquid crystal that displays red when viewed from the vertical (0 ° incident position) changes in order of orange, yellow, green, blue-green, and blue as the viewing angle increases. Looks like.
[0021]
FIG. 3 is a diagram for explaining circularly polarized light selective reflectivity.
The circularly polarized light selective reflection property is a property of reflecting only circularly polarized light in a specific rotation direction and transmitting circularly polarized light having the opposite rotation direction. Of the incident light, it reflects the circularly polarized light component in the same direction as the twist direction of the alignment structure of the cholesteric liquid crystal and transmits the circularly polarized light component that rotates in the opposite direction. At this time, the rotation direction of the reflected light is also the same direction.
For example, the light selective reflection layer 11 of the cholesteric liquid crystal having a right twist structure reflects the right circularly polarized light L1, and the reflected light L1 remains the right circularly polarized light (FIG. 3A), but the left circularly polarized light. L2 is transmitted (FIG. 3B).
[0022]
FIG. 4 is a schematic diagram illustrating the specific polarized light irradiation device of the first embodiment.
The specific polarized light irradiation device 20 includes a light source 21, a polarizing layer 22, and a birefringent layer 23.
The light source 21 is, for example, a 100 W white light.
The polarizing layer 22 is a linearly polarizing film that transmits only the linearly polarized light L4 having a specific polarization direction in the light L3 of the light source 21. The polarizing layer 22 can be formed of a polarizing film or sheet in which a stretched film such as polyvinyl alcohol (PVAL) is absorbed with a dye such as a dichroic dye.
[0023]
The birefringent layer 23 is a so-called λ / 4 retardation film that birefringes incident light, and is formed on the polarizing layer 22.
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 medium λ: given by wavelength of light. As is apparent from this equation, the phase difference σ depends on the thickness d of the medium. Therefore, the phase difference σ can be changed by changing the thickness d of the medium.
In the present embodiment, the birefringent layer 23 receives the linearly polarized light L4 transmitted through the polarizing layer 22 and emits the circularly polarized light L5 having the phase difference σ. Thus, the polarizing layer 22 and the birefringent layer 23 act as polarization forming means for converting the light L3 emitted from the light source into circularly polarized light L5. As described above, the rotation direction of the circularly polarized light can be freely determined by adjusting the thickness d of the medium. In this embodiment, the thickness d is adjusted so as to emit left circularly polarized light.
[0024]
The birefringent layer 23 can be formed of a plastic film produced by a stretching process. Stretching is a method for producing a film by stretching a plastic at an appropriate temperature not higher than the melting point and not lower than the glass transition point, and includes uniaxial stretching and biaxial stretching depending on the stretching direction. In the present invention, since it is sufficient that the refractive index anisotropy exists, a film produced by any one of the uniaxial stretching method and the biaxial stretching method can be used.
Specifically, the birefringent layer 23 is made of cellophane, polyester, polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVAL), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polystyrene (PS), It can be formed using a stretched film made of polyethylene terephthalate (PET), polycarbonate (PC), nylon or the like.
[0025]
The birefringent layer 23 is formed by adhering to the polarizing layer 22. In FIG. 4, the birefringent layer 23 is drawn separately from the polarizing layer 22 for easy understanding. For this bonding, thermosetting resins (for example, phenol resins, furan resins, urea resins, melamine resins, polyester resins, polyurethane resins, epoxy resins and other resins), thermosetting resins (for example, , Polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride resin, polyvinyl butyral resin, poly (meth) acrylic resin, nitrocellulose, polyamide and other resins), rubber (for example, butadiene-acrylonitrile rubber, neoprene rubber and other rubber), Nikawa Adhesives composed mainly of one or more of natural resin, casein, sodium silicate, dextrin, starch, gum arabic and the like can be used. These adhesives may be any of a solution type, an emulsion type, a powder type, or a film type. Furthermore, these adhesives may be any of a room temperature solidification type, a solvent volatile solidification type, or a melt solidification type.
[0026]
(Authentication method)
FIG. 5 is a diagram for explaining the authenticity determination method, and FIG. 6 is a diagram showing the state of the light selective reflection label at the time of authenticity determination.
As shown in FIG. 5, the light selective reflection label 10 performs authenticity determination by irradiating light from the specific polarized light irradiation device 20.
Under natural light, the light selective reflection layer 11 reflects specific circularly polarized light with a specific wavelength included in the natural light, so that the judge looks that the light selective reflection label 10 is colored (FIG. 6A). Further, in this state, the light selective reflection label 10 looks like an ordinary film, so that it is not recognized by others that it is authenticity determination means.
Others will not realize the existence of authenticity judgment means.
Next, the light selective reflection label 10 is placed under the specific polarized light irradiation device 20 and irradiated with left circularly polarized light.
Then, since the irradiated left circularly polarized light passes through the light selective reflection label 10 (light selective reflection layer 11), the determiner cannot see the light selective reflection label 10 (FIG. 6B). Thereby, the determiner can determine that the light selective reflection label 10 is genuine.
[0027]
According to the present embodiment, it is possible to easily determine whether or not the light selective reflection label 10 is genuine by simply irradiating the light of the specific polarized light irradiation device 20 to the light selective reflection label 10. .
In addition, under the natural light, the light selective reflection label 10 looks like an ordinary film, so that other people cannot realize that it is an authenticity determination means.
Furthermore, since a cholesteric liquid crystal film is used for the light selective reflection layer 11, the reflected light is very clean and excellent in design.
Furthermore, since the specific polarized light irradiation device 20 can be formed by the polarizing layer 22 and the birefringent layer 23, it can be manufactured at low cost.
[0028]
(Second Embodiment)
FIG. 7 is a view showing a second embodiment of the light selective reflection label according to the present invention.
In each of the embodiments described below, the same reference numerals or the same reference numerals are given to the portions that perform the same functions as those in the first embodiment described above, and redundant description will be omitted as appropriate.
The light selective reflection label 10 of this embodiment includes a light selective reflection layer 11 and a light diffraction structure forming unit 12.
The light selective reflection layer 11 is a light selective reflection film layer including a left circularly polarized light selective reflection part 11a, a right circularly polarized light selective reflection part 11b, and a non-selective reflection part 11c.
[0029]
The left circularly polarized light selective reflection unit 11a transmits right circularly polarized light and reflects left circularly polarized light in incident light. The left circularly polarized light selective reflection portion 11a is formed of a cholesteric liquid crystal having a left twisted structure.
Right circular polarization selective reflection portion 11b, the incident light passes through the left-handed circularly polarized light and reflects the right circularly polarized light. The right circularly polarized light selective reflection portion 11b is formed of a cholesteric liquid crystal having a right twist structure.
The non-selective reflection unit 11c reflects incident light without reflecting reflection characteristics depending on the polarization state. The non-selective reflection portion 11c is formed by changing the quality of the light selective reflection film layer so that the light selective reflectivity disappears by heating with a laser irradiation, a thermal head or the like. By doing in this way, shapes, such as a character and a picture, can be formed freely.
[0030]
The light diffraction structure forming unit 12 is formed on the back surfaces of the left circularly polarized light selective reflecting portion 11 a and the right circularly polarized light selective reflecting portion 11 b of the light selective reflection layer 11. The light diffraction structure forming unit 12 generates a light diffraction phenomenon with respect to reflected light in a polarization state that is selectively reflected by the light selective reflection layer 11. That is, when the irradiated light includes specific polarized light that can be reflected by the left circularly polarized light selective reflection unit 11a and the right circularly polarized light selective reflection unit 11b, the light diffraction image becomes visible.
Examples of such a light diffraction structure forming unit include a hologram and a diffraction grating.
Without the light diffractive structure forming portion 12, particularly when the reflected light returns from under the light selective reflection layer 11 (for example, when pasted on a white base material), the reflection from the light selective reflection layer 11 It is difficult to distinguish between light and reflected light from the substrate. However, when the light diffraction structure forming unit 12 is formed on the back surface of the left circularly polarized light selective reflecting portion 11a and the right circularly polarized light selective reflecting portion 11b of the light selective reflection layer 11 , the left circular polarization selective reflection portion 11a of the light selective reflection layer 11 and The reflected light from the right circularly polarized light selective reflecting portion 11b is circularly polarized light (left circularly polarized light or right circularly polarized light) corresponding to each reflection characteristic, and exhibits a light diffraction image by the light diffraction phenomenon by the light diffraction structure forming unit 12. because, it becomes possible to easily identify visible left circularly light selective reflection portion 11a and the right circularly polarized light selective reflection portion 11b with respect to changes in the polarization state of illumination light, the invisible change. Moreover, the improvement of design property and the forgery prevention effect is realizable.
[0031]
FIG. 8 is a schematic diagram showing the specific polarized light irradiation device of the second embodiment.
The specific polarized light irradiation device 20 includes a light source 21, a circularly polarized light forming unit 24, and a rotation motor 25.
The circularly polarized light forming unit 24 includes a left circularly polarized light forming unit 24 a and a right circularly polarized light forming unit 24 b, which are alternately arranged on the circular frame 26.
The left circularly polarized light forming portion 24a is a portion that changes the light of the light source 21 to left circularly polarized light, and includes a polarizing layer and a birefringent layer. The polarizing layer and the birefringent layer are the same as those in the first embodiment, and the birefringent layer is adjusted to a thickness that allows the light from the light source 21 to be left circularly polarized.
The right circularly polarized light forming portion 24b is a portion that changes the light from the light source 21 to right circularly polarized light, and is formed by laminating a polarizing layer and a birefringent layer. The birefringent layer is adjusted to a thickness that allows the light from the light source 21 to be right circularly polarized light.
The rotation motor 25 rotates the circular frame 26 in a certain direction.
In addition, the specific polarized light irradiation device 20 is, for example, a desk lamp, and the light selective reflection label 10 is used by being attached to an authenticity determination body 40 such as a passport or a voucher.
[0032]
(Authentication method)
FIG. 9 is a diagram illustrating a state of the light selective reflection label at the time of authenticity determination.
As in the first embodiment, the light selective reflection label 10 is used by being affixed to an authenticity determination body 40 such as a passport or a voucher.
When it is determined whether or not the voucher with the light selective reflection label 10 attached is genuine, the light selective reflection label 10 is illuminated with the specific polarized light irradiation device 20.
At this time, as shown in FIGS. 9A and 9B, when “O” and “X” appear to blink alternately, it can be determined that the product is genuine.
In this way, it is obvious whether the passport or the voucher is genuine at immigration or storefront. Moreover, if this specific polarized light irradiation apparatus 20 is installed on the ceiling of a warehouse, for example, and the light selective reflection label 10 is used as a product tag, it is obvious whether or not the product in the warehouse is a genuine product.
[0033]
According to the present embodiment, in addition to the effects of the first embodiment, since “○” and “×” appear to blink alternately, it is possible to more easily determine whether or not the product is genuine. .
Further, since the light diffraction structure forming part 12 is formed on the back surfaces of the left circularly polarized light selective reflecting part 11 a and the right circularly polarized light selective reflecting part 11 b of the light selective reflection layer 11 , the left circularly polarized light selective reflection of the light selective reflection layer 11. The reflected light from the part 11a and the right circularly polarized light selective reflection part 11b is circularly polarized light (left circularly polarized light or right circularly polarized light) corresponding to the respective reflection characteristics, and is light diffracted by the light diffraction phenomenon by the light diffraction structure forming part 12. since presenting an image, it is possible to more easily identify left circularly light selective reflection portion 11a and the right circularly polarized light selective reflection portion 11b of the visible to the change in the polarization state of the illumination light, the invisible changes by light diffraction image.
Furthermore, since a light diffraction image is exhibited, it is possible to improve the design and anti-counterfeit effect.
[0034]
(Third embodiment)
FIG. 10 is a diagram showing a third embodiment of the light selective reflection label according to the present invention.
The light selective reflection label 10 of this embodiment further includes a light absorption layer 13 with respect to the light selective reflection label 10 of the second embodiment.
The light absorption layer 13 is formed on the back surface of the light selective reflection layer 11. The light absorption layer 13 is colored, for example, black, and absorbs light that has passed through the light selective reflection layer 11 and suppresses reflection of this light. As a result, the reflected light from the light selective reflector is only the reflected light from the light selective reflection layer 11, and identification is facilitated. For example, the light absorption layer 13 may be formed by applying an adhesive. This is because the light selective reflection label 10 can be attached to an authenticity determination body such as a gift certificate.
[0035]
According to the present embodiment, light that has passed through the light selective reflection layer 11 is absorbed by the light absorption layer 13 and becomes only reflected light from the light selective reflection layer 11, so that identification is facilitated.
[0036]
(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
For example, the light absorption layer 13 may be provided on the lower surface of the light selective reflection layer 11 of the first embodiment. At this time, when the left circularly polarized light is irradiated, the light passes through the light selective reflection layer 11 and is absorbed by the light absorption layer 13 so that the light selective reflection label 10 looks black and whether or not it is genuine. Judgment can be made easily.
In the second embodiment, the circularly polarized light selective reflection portions 11a and 11b have different twist structures, but those having the same twist structure may be used. By doing so, the circularly polarized light selective reflection portions 11a and 11b blink simultaneously. When blinking in this way, it is determined that the product is genuine.
Furthermore, the same effect can be obtained even with a structure having only one circularly polarized light selective reflection portion.
Furthermore, a desired polarized light may be obtained by using a spatial modulation element in the specific polarized light irradiation device.
The specific polarized light irradiation device can also produce the effect of the present invention by alternately irradiating natural light and specific polarized light.
[0037]
【The invention's effect】
As described above in detail, the present invention has the following effects.
(1) It is possible to easily determine whether or not the authenticity determination product is a genuine product.
(2) Under natural light, others will not realize the existence of authenticity determination means.
(3) Since the specific polarized light irradiation device can be formed by the birefringent layer and the polarizing layer, it can be manufactured at low cost.
(4) Since the light selective reflection layer is formed of a cholesteric liquid crystal film, the reflected light is very clean and excellent in design.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of a light selective reflection label according to the present invention.
FIG. 2 is a schematic diagram showing the structure of a cholesteric liquid crystal in a reflective layer.
FIG. 3 is a diagram for explaining circularly polarized light selective reflectivity.
FIG. 4 is a schematic diagram showing the specific polarized light irradiation device of the first embodiment.
FIG. 5 is a diagram for explaining an authenticity determination method.
FIG. 6 is a diagram showing a state of a light selective reflection label at the time of authenticity determination.
FIG. 7 is a view showing a second embodiment of the light selective reflection label according to the present invention.
FIG. 8 is a schematic view showing a specific polarized light irradiation device of a second embodiment.
FIG. 9 is a diagram showing a state of a light selective reflection label at the time of authenticity determination.
FIG. 10 is a diagram showing a third embodiment of the light selective reflection label according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Light selective reflection label 11 Light selective reflection layer 11a Left circular polarization selective reflection part 11b Right circular polarization selective reflection part 12 Light diffraction structure formation part 13 Light absorption layer 20 Specific polarized light irradiation apparatus 21 Light source 22 Polarization layer 23 Birefringence layer 24 Circle Polarization forming unit 24a Left circular polarization forming unit 24b Right circular polarization forming unit 25 Rotating motor 26 Circular frame 40 True judgment object

Claims (2)

A first light selective reflection unit that is formed of a liquid crystal layer in which a cholesteric phase is fixed and reflects light in a first polarization state and transmits light in a second polarization state among incident light;
A second light selective reflection portion that is formed of a liquid crystal layer in which a cholesteric phase is fixed, reflects light in the second polarization state, and transmits light in the first polarization state;
A liquid crystal layer in which a cholesteric phase is fixed is heated to have a reflection characteristic that does not depend on the polarization state, and is provided in a region other than the first light selective reflection portion and the second light selective reflection portion. A non-selective reflection portion to be disposed;
Same as the respective reflected lights that are formed in the first light selective reflection part and the second light selective reflection part and selectively reflected by the first light selective reflection part and the second light selective reflection part. A light diffractive structure forming part that reflects light in the polarization state and generates a light diffraction phenomenon;
An authenticity determination system for determining authenticity using a light selective reflector comprising:
Light converted by first polarization forming means for converting light from the light source into light in the first polarization state, and second polarization forming means for converting light from the light source into light in the second polarization state When the first light selective reflection portion and the second light selective reflection portion of the light selective reflector become alternately invisible, the light selective reflection is performed. An authenticity determination system characterized by determining that the body is genuine. The authenticity determination system according to claim 1,
The first polarization forming means and the second polarization forming means have linear polarization means for converting light into linearly polarized light and circular polarization means for converting the linearly polarized light into circularly polarized light, and specify light. Authenticity determination system characterized by converting into circularly polarized light having a polarization state of.

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