JP4984776B2 - Anti-counterfeit medium, anti-counterfeit label, printed matter, transfer foil, and discrimination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve more higher forgery preventive effect by containing an optical reflecting layer and a &lambda;/4 phase difference layer opposite to its front surface. <P>SOLUTION: A forgery preventive medium 10 is equipped with first and second optical reflecting layers 11, 12 ranged in line in a plane direction. The first optical reflecting area contains a circular polarized light reflecting layer 24, and the second optical reflecting area contains an optical reflecting layer 22 and a &lambda;/4 phase contrast layer 25 facing its front surface. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a forgery prevention technique that can be used to prevent forgery of securities such as stock certificates, bonds, checks, and gift certificates, lotteries, and ID cards.

  In recent years, copiers using electrophotographic technology have become widespread, and anyone can easily copy documents using this. In particular, according to a recent color digital copying machine, even a copy that is extremely difficult to determine whether it is a manuscript or a copy can be easily produced.

  A general color digital copying machine performs copying by the following method. First, the original is irradiated with light, and the reflected light is detected by a CCD line sensor. The CCD line sensor generates a digital signal corresponding to the intensity of the reflected light and transmits it to a memory in the copying machine. This reading is performed for three colors of red (R), green (G), and blue (B), and digital signals obtained for the respective colors are stored in the memory. Next, based on the stored digital signal, an electrostatic latent image is drawn on the photosensitive drum with a laser beam. Subsequently, a toner image corresponding to the electrostatic latent image is formed on the photosensitive drum using electrostatic force. Thereafter, the toner image is transferred to a sheet, and the transferred toner image is fixed on the sheet. For example, by performing this process for three colors, an elaborate color copy can be obtained.

  While such color copying is convenient, it facilitates the forgery of securities such as stock certificates, bonds, promissory notes, checks, and printed materials such as admission tickets and boarding passes. For this reason, various proposals have been made to take measures to prevent duplication of printed matter so that they cannot be easily copied.

  A technique has been proposed in which the color of a color copy is different from the color of the original. For example, a technique for coloring a document such as securities with a very light color has been proposed. It is difficult to accurately reproduce this light color by copying. In addition, a technique for forming halftone dots of different sizes has been proposed. In these copies, the reproducibility of small halftone dots tends to be insufficient. Further, a technique for printing in a color that is not found in toner of color copiers such as green, purple, orange, gold, and silver has been proposed. Also, reflection and / or absorption characteristics are almost equal in the wavelength range of light that can be easily perceived by humans, and reflection and / or absorption in the wavelength range of light that is difficult for humans to perceive, for example, wavelength ranges of 380 nm to 450 nm and 650 nm to 780 nm. Techniques using two types of inks having different characteristics have been proposed. The two areas formed using these inks are visually the same color, but can be reproduced in different colors when copied on a color copier.

  However, the color copying machine can correct the output color. Also, digital presses that correct digital data read by a color scanner with a computer and output the data with a color printer are becoming widespread. Therefore, if a little effort is required, it is possible to precisely reproduce the color of the document, and it is difficult to prevent forgery with the above-described technique.

  In addition, for example, a technique has been proposed in which securities are provided with special parts that cannot be reproduced by a color copying machine. Among these, the technique of providing an OVD (Optical Variable Device) such as a hologram foil described in Patent Documents 1 and 2 on the surface of securities or the like has already been put into practical use. According to this technique, since the silver surface of the hologram specularly reflects light, the reflected light does not enter the CCD line sensor, and the silver surface portion of the original is reproduced in black on the copy. Patent Document 3 describes a technique using an optical thin film in which ceramic layers having different refractive indexes are stacked and the color changes depending on the viewing angle. Since this color change cannot be obtained with a copy, it is possible to easily determine the authenticity. Furthermore, it has also been proposed to perform printing by crushing the thin film formed by this method and mixing fragments into ink.

  However, due to the development of embossing technology, the formation of a reflective layer using relief-type diffracted light has become more difficult than before. In addition, multilayer thin film has begun to be sold as a general packaging film. As a result, the effect of preventing forgery of holograms has been reduced.

  Patent Documents 4 to 7 describe the use of cholesteric liquid crystal in order to obtain an effect of changing the color of reflected light in accordance with the viewing angle, that is, a color shift effect, similarly to a hologram.

  The wavelength of circularly polarized light selectively reflected by the polymer cholesteric liquid crystal changes according to the viewing angle. Patent Documents 4 to 7 disclose that this color shift effect is used in order to obtain an anti-counterfeit effect. Also disclosed are techniques for laminating a cholesteric liquid crystal layer and a hologram forming portion, and using an ink containing a cholesteric liquid crystal pigment and an ionizing radiation curable resin. Furthermore, there is a disclosure of a technique for controlling the rotation direction of polarized light as reflected light by combining a cholesteric liquid crystal layer and a phase difference layer using nematic liquid crystal.

However, nowadays cholesteric liquid crystals are easily available because of the frequent use of circularly polarizing plates in displays. Therefore, the anti-counterfeit effect by the cholesteric liquid crystal is decreasing.
JP-A-6-259013 Japanese Patent Laid-Open No. 7-089293 JP-T-2004-505158 JP-A-63-51193 WO00 / 13065 JP 2002-114935 A JP 2005-88381 A

  An object of the present invention is to achieve a higher anti-counterfeit effect.

  A first invention for solving the above-described problems includes first and second light reflecting regions arranged in an in-plane direction, the first light reflecting region including a circularly polarized light reflecting layer, and the second light reflecting region. The light reflection region is a forgery prevention medium including a light reflection layer and a λ / 4 retardation layer facing the front surface thereof.

  The second invention is the anti-counterfeit medium according to the first invention, wherein the first light reflection region is adjacent to the second light reflection region.

  The third invention further includes a third light reflecting region aligned with the first and second light reflecting regions in the in-plane direction, the third light reflecting region including a light reflecting layer, The three-light reflection region is a forgery-preventing medium according to the first invention, wherein the three-light reflection region does not include a layer in front of the light reflection layer included in the three-light reflection region or includes only an optically isotropic layer. is there.

  According to a fourth aspect of the invention, the first light reflecting region further includes a λ / 8 retardation layer covering at least a part of the circularly polarized light reflecting layer. It is any one of the anti-counterfeit media of the invention.

  According to a fifth aspect of the invention, the first light reflecting region further includes a λ / 8 phase difference layer partially covering the circularly polarized light reflecting layer. Any one of the anti-counterfeit media.

  The sixth invention is the anti-counterfeit medium according to any one of the first to fifth inventions, wherein the circularly polarized light reflection layer is a cholesteric liquid crystal layer.

  According to a seventh invention, the λ / 4 retardation layer is made of nematic liquid crystal, and the light reflection layer is a metal light reflection layer. It is a prevention medium.

  In addition, according to an eighth invention, in any one of the first to seventh inventions, the first light reflection region further includes a light absorption layer facing a back surface of the circularly polarized light reflection layer. Is an anti-counterfeit medium.

  The ninth invention is a forgery prevention label comprising the forgery prevention medium of any one of the first to eighth inventions and an adhesive layer supported on the back surface thereof.

  According to a tenth aspect of the present invention, there is provided a printed matter comprising the forgery prevention medium according to any one of the first to eighth aspects and a paper into which the forgery prevention medium is inserted.

  An eleventh aspect of the invention is supported by any one of the first to eighth aspects of the anti-counterfeit medium, a base material that releasably supports the front surface of the anti-counterfeit medium, and a back surface of the anti-counterfeit medium. The transfer foil is characterized by including an adhesive layer.

A twelfth aspect of the invention is a method for discriminating between an authentic product and a non-authentic product using a verification tool for an article of which authenticity is unknown or not. An article that supports the anti-counterfeit medium according to any one of the inventions, wherein the verification tool faces a linearly polarizing film, a part of one main surface of the linearly polarizing film, and a fast axis is the linearly polarizing film. The first λ / 4 retardation layer forming an angle of 45 ° with respect to the transmission axis of the linearly polarizing film faces the other part of the main surface of the linearly polarizing film, and the fast axis is the first λ. / 4 retardation layer orthogonal to the fast axis of the / 4 retardation layer, the article having the unknown whether or not the authenticity and the verification tool, the verification tool of the verification tool In this state, the first and second λ / 4 retardation layers are overlapped with the article of which the authenticity is unknown or not. And the second λ / 4 phase difference between the brightness of the verification tool and the second λ / 4 phase difference when the article of which the authenticity is unknown is observed through the portion corresponding to the first λ / 4 phase difference layer. If it does not include a region that is different from the brightness when observing an unknown article whether or not it is authentic through a portion corresponding to a layer, the authentic or unknown article is an unauthentic product. Judging that there is an article, whether the authenticity is unknown, and the verification tool, and the linear polarizing film of the verification tool, and the authenticity, whether the authenticity is unknown. In addition, in this state, when observing an article of which the authenticity is unknown through the verification tool, it does not include a region where the brightness changes according to the direction of the transmission axis of the linearly polarizing film. In some cases, the authentic or unknown article is determined to be non-authentic. It is the discrimination method characterized by including cutting off.

  According to the present invention, a higher forgery prevention effect can be achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same referential mark is attached | subjected to the component which exhibits the same or similar function, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view schematically showing a forgery prevention medium according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of the forgery prevention medium shown in FIG.

  The anti-counterfeit medium 10 includes a base material 21 shown in FIG. The base material 21 is a biaxially stretched film made of, for example, polyethylene terephthalate.

  A light reflection layer 22 is formed on the substrate 21. Typically, the light reflecting layer 22 is a specular reflector. The light reflecting layer 22 can be formed by evaporating aluminum, for example.

  The front surface of the light reflection layer 22 is partially covered with a light absorption layer 23. The light absorption layer 23 can be formed, for example, by applying black ink to a part of the front surface of the light reflection layer 22. As this black ink, for example, one obtained by dispersing carbon black in a resin can be used.

  On the light absorption layer 23, a circularly polarized light reflection layer 24 is formed. The circularly polarized light reflection layer 24 selectively reflects part of the circularly polarized light. The circularly polarized light reflecting layer 24 is made of, for example, cholesteric liquid crystal. The cholesteric liquid crystal will be described in detail later.

On the front surface of the light reflection layer 22, the λ / 4 retardation layer 25 is adjacent to the light absorption layer 23. The λ / 4 retardation layer 25 is made of, for example, nematic liquid crystal. The λ / 4 retardation layer 25 has, for example, a _fast axis along a direction indicated by an arrow n _A25 in FIG. 1 and a slow axis n _B25 (not shown in FIG. 1) perpendicular to the fast axis. Have. The λ / 4 phase difference layer 25 has a wavelength of λ and a plane of polarization (oscillation plane of the electric field vector) that is obliquely incident on the fast axis n _A25 makes the plane of polarization the slow axis n _B25. And a second linearly polarized light whose plane of polarization is parallel to the fast axis n _A25 and whose phase is advanced by λ / 4 from the first linearly polarized light.

  The wavelength λ is a design wavelength. The design wavelength λ is typically a wavelength of green light in which natural human light cells have high sensitivity, for example, about 550 nm. The retardation of the λ / 4 retardation layer 25 at the design wavelength λ may not be as designed due to variations in the thickness thereof. Even in such a case, if the deviation of the retardation from the design value is about 10% or less of the design value, the verification described later is not greatly affected.

  Hereinafter, in the forgery prevention medium 10, a portion corresponding to the circularly polarized reflection layer 24 is referred to as a first light reflection region 11, and a portion corresponding to the λ / 4 retardation layer 25 is referred to as a second light reflection region 12. In FIG. 2, the circularly polarized light reflection layer 24 and the λ / 4 retardation layer 25 are flush with each other, but the heights of the surfaces may not be equal.

  Next, the cholesteric liquid crystal will be described.

  A cholesteric liquid crystal is composed of a plurality of molecular layers. The orientation direction of the molecules of the cholesteric liquid crystal is constant in each molecular layer, but is slightly different between adjacent molecular layers. Thus, in the cholesteric liquid crystal, the liquid crystal molecules form a clockwise or counterclockwise helical structure.

  The cholesteric liquid crystal reflects circularly polarized light having a polarization plane that rotates in the same direction as the helical twist direction of the helical structure out of light having a wavelength that matches the helical pitch, while maintaining the twisted direction of the polarization plane. The circularly polarized light whose rotation direction is reverse is transmitted. This property of cholesteric liquid crystals is called selective reflection.

  A cholesteric liquid crystal shows the maximum reflectance with respect to right-handed circularly polarized light or left-handed circularly polarized light having a wavelength corresponding to the helical pitch. This reflectance decreases as the wavelength of circularly polarized light deviates from the helical pitch.

  Here, as an example, it is assumed that the circularly polarized light reflecting layer 24 is made of cholesteric liquid crystal having a helical pitch equal to the design wavelength λ. If the deviation of the helical pitch from the design wavelength λ is about 10% or less of the design wavelength λ, the verification described later is not greatly affected.

  In the following description, as an example, it is assumed that the circularly polarized light reflecting layer 24 is made of cholesteric liquid crystal having a clockwise helical structure. Of course, in the circularly polarized light reflection layer 24, the helical structure of the cholesteric liquid crystal may be clockwise or counterclockwise.

  Next, an image that is seen when natural light is irradiated onto the anti-counterfeit medium 10 and observed with the naked eye will be described.

  The circularly polarized light reflecting layer 24 in the first light reflecting region 11 selectively reflects right circularly polarized light having a wavelength substantially equal to the design wavelength λ from natural light, and transmits other light components. The light component transmitted through the circularly polarized light reflection layer 24 is absorbed by the light absorption layer 23. Accordingly, the first light reflection region 11 emits only the right circularly polarized light selectively reflected by the circularly polarized light reflection layer 24.

  On the other hand, in the second light reflection region 12, the light reflection layer 22 specularly reflects incident light. Accordingly, the second reflection region 12 emits light having an intensity substantially equal to the incident light.

  Therefore, when the forgery prevention medium 10 is irradiated with natural light and observed, the first light reflection region 11 appears darker than the second light reflection region 12.

  Next, a verification tool used for confirming that the article supporting the forgery prevention medium 10 is a genuine product will be described.

  FIG. 3 is an exploded view schematically showing an example of the verification tool. A verification tool 50 shown in FIG. 3 includes a linearly polarizing film 51 and λ / 4 retardation layers 53 and 54.

  The linearly polarizing film 51 is, for example, an absorptive polarizing film. In this case, the linearly polarizing film 51 transmits linearly polarized light having a polarization plane parallel to the transmission axis OP, and absorbs linearly polarized light having a polarization plane orthogonal to the transmission axis OP.

  The λ / 4 retardation layer 53 faces a part of one main surface of the linearly polarizing film 51. The λ / 4 retardation layer 54 faces the other part of the front main surface of the linearly polarizing film 51. The λ / 4 retardation layers 53 and 54 are adjacent to each other, and typically form one retardation layer 52.

The λ / 4 retardation layer 53 and the λ / 4 retardation layer 54 are different in the direction of the fast axis. Further, the fast axes of the λ / 4 retardation layers 53 and 54 are oblique to the transmission axis OP of the linearly polarizing film 51. As an example, when the retardation layer 52 is viewed from the linearly polarizing film 51 side, the direction of the _fast axis n _A53 of the λ / 4 retardation layer 53 is rotated 45 ° clockwise from the direction parallel to the transmission axis OP. It is assumed that the direction of the _fast axis _nA54 of the λ / 4 retardation layer 54 is a direction rotated 45 ° counterclockwise from a direction parallel to the transmission axis OP. In this case, in the verification tool 50, a portion corresponding to the λ / 4 retardation layer 53 functions as a right circular polarizer, and a portion corresponding to the λ / 4 retardation layer 54 functions as a left circular polarizer.

  The retardation of each of the λ / 4 retardation layers 53 and 54 at the design wavelength λ may not be as designed due to variations in the thickness thereof. Even in such a case, if the deviation of the retardation from the design value is about 10% or less of the design value, the verification described later is not greatly affected.

  Next, a method for verifying that the article supporting the forgery prevention medium 10 is an authentic product using the verification tool 50 will be described.

  FIG. 4 is a plan view schematically showing an example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 1 and 2 and the verification tool shown in FIG. 3 are overlapped. FIG. 5 is a cross-sectional view taken along line VV of the structure shown in FIG.

  4 and 5, the false image prevention medium 10 and the verification tool 50 are arranged such that each of the λ / 4 retardation layers 53 and 54 faces both the light reflection regions 11 and 12. In this case, as shown in FIG. 4, in the first light reflecting region 11, the region 11 b facing the λ / 4 retardation layer 54 appears as a dark portion, and the region 11 a facing the λ / 4 retardation layer 53. Appears brighter than region 11b. On the other hand, in the second light reflection region 12, the region 12a facing the λ / 4 retardation layer 53 appears as a bright portion, and the region 12b facing the λ / 4 retardation layer 54 has the same brightness as the region 12a. Looks like.

  The reason why the bright part and the dark part are formed by overlapping the verification tool 50 will be described. Here, for simplification, only light having a wavelength equal to the design wavelength λ is considered.

  First, the light and darkness that occurs in the first light reflection region 11 will be described.

  As shown in FIG. 5, when the polarizing film 51 is irradiated with natural light 80, the λ / 4 retardation layer 53 emits right circularly polarized light 82, and the λ / 4 retardation layer 54 emits left circularly polarized light 83.

  The circularly polarized light reflecting layer 24 selectively reflects the right circularly polarized light emitted from the λ / 4 retardation layer 53. The selectively reflected right circularly polarized light 82 enters the λ / 4 retardation layer 53. The λ / 4 retardation layer 53 converts the right circularly polarized light 82 into linearly polarized light 82 ′. The linearly polarized light 82 ′ passes through the polarizing film 51 because the plane of polarization is parallel to the transmission axis OP of the polarizing film 51. On the other hand, the left circularly polarized light 83 emitted from the λ / 4 retardation layer 54 passes through the circularly polarized light reflecting layer 24 and is absorbed by the light absorbing layer 23.

  For the above reasons, in the first light reflection region 11 shown in FIG. 4, the region 11b facing the λ / 4 retardation layer 54 appears as a dark portion, and the region 11a facing the λ / 4 retardation layer 53 is It looks brighter than the region 11b.

  Next, the light and darkness that occurs in the second light reflection region 12 will be described.

  As described with reference to FIG. 5, when the polarizing film 51 is irradiated with natural light, the λ / 4 retardation layer 53 emits right circularly polarized light, and the λ / 4 retardation layer 54 emits left circularly polarized light.

  The right circularly polarized light emitted from the λ / 4 retardation layer 53 is incident on the λ / 4 retardation layer 25 shown in FIG. The λ / 4 retardation layer 25 converts right circularly polarized light into first linearly polarized light. The first linearly polarized light is specularly reflected by the light reflecting layer 22 and enters the λ / 4 retardation layer 25 again. The λ / 4 retardation layer 25 converts the first linearly polarized light into right circularly polarized light. The right circularly polarized light emitted from the λ / 4 retardation layer 25 is incident on the λ / 4 retardation layer 53 shown in FIG. The λ / 4 retardation layer 53 converts right circularly polarized light into linearly polarized light. The linearly polarized light is transmitted through the polarizing film 51 because the plane of polarization is parallel to the transmission axis OP of the polarizing film 51.

  The left circularly polarized light emitted from the λ / 4 retardation layer 54 shown in FIG. 5 is incident on the λ / 4 retardation layer 25 shown in FIG. The λ / 4 retardation layer 25 converts the left circularly polarized light into second linearly polarized light having a polarization plane perpendicular to the polarization plane of the first linearly polarized light. The second linearly polarized light is specularly reflected by the light reflecting layer 22 and enters the λ / 4 retardation layer 25 again. The λ / 4 retardation layer 25 converts the second linearly polarized light into left circularly polarized light. The left circularly polarized light emitted from the λ / 4 retardation layer 25 is incident on the λ / 4 retardation layer 54 shown in FIG. The λ / 4 retardation layer 54 converts left circularly polarized light into linearly polarized light. The linearly polarized light is transmitted through the polarizing film 51 because the plane of polarization is parallel to the transmission axis OP of the polarizing film 51.

  For the above reason, in the second light reflection region 12 shown in FIG. 4, the region 12a facing the λ / 4 retardation layer 53 appears as a bright portion, and the region 12b facing the λ / 4 retardation layer 54. Appears as bright as the region 12a.

  It should be noted that the brightness relationship described above for the regions 11a and 11b and the regions 12a and 12b does not change even if the verification tool 50 is rotated around the normal line. This is because the light emitted from the λ / 4 retardation layers 53 and 54 toward the anti-counterfeit medium 10 is circularly polarized, and the region 11b does not emit light toward the verification tool 50, and the regions 11a, 12a, and 12b This is because the light emitted toward the verification tool 50 is also circularly polarized light.

  Next, an image that is seen when the verification tool 50 is turned over and superimposed on the forgery prevention medium 10 will be described.

FIG. 6 is a plan view schematically showing another example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 1 and 2 and the verification tool shown in FIG. 3 are overlapped. FIG. 7 is a cross-sectional view taken along line VII-VII of the structure shown in FIG. 6 and 7, the verification tool 50 is turned upside down, and the transmission axis OP of the polarizing film 51 and the _fast axis n _{A25 of the} λ / 4 retardation layer 25 are orthogonal to each other.

When the verification tool 50 is turned upside down, the verification tool 50 functions as a linear polarizer having a transmission axis OP. That is, as illustrated in FIG. 7, when the verification tool 50 is irradiated with natural light L _i-n from the λ / 4 retardation layer 52 side, the verification tool 50 is directed toward the anti-counterfeit medium 10 and the transmission axis of the polarizing film 51. Linearly polarized light L _p-p1 having a polarization plane parallel to OP is emitted.

Of the linearly polarized light L _p-p1 incident on the first light reflecting region 11, the right circularly polarized light L _r-r is selectively reflected by the circularly polarized light reflecting layer 24, and the other left circularly polarized light L _{p -l} is the circularly polarized light reflecting layer. 24 is absorbed by the light absorption layer 23. The selectively reflected right-handed circularly polarized light L _rr enters the polarizing film 51. Of the right circularly polarized light L _rr , the polarizing film 51 transmits linearly polarized light whose polarization plane is parallel to the transmission axis OP, and absorbs linearly polarized light whose polarization plane is perpendicular to the transmission axis OP. The linearly polarized light transmitted through the polarizing film 51 is incident on the λ / 4 retardation layer 52. The λ / 4 retardation layers 53 and 54 of the λ / 4 retardation layer 52 convert the linearly polarized light into right circularly polarized light and left circularly polarized light, respectively. There is no difference in intensity between the right circularly polarized light and the left circularly polarized light. Therefore, there is no difference in brightness between a portion of the first light reflection region 11 that can be seen through the λ / 4 retardation layer 53 and a portion that can be seen through the λ / 4 retardation layer 54.

The linearly polarized light L _p-p1 incident on the second light reflection region 12 is transmitted through the λ / 4 retardation layer 25. Since the fast axis _{n A25} of the linearly polarized light _{L p-p1} polarization plane and lambda / 4 retardation layer 25 is orthogonal, linearly polarized light _{L p-p1} incident is transmitted as linearly polarized light _{L p-p1,} Reflected by the light reflecting layer 22. The linearly polarized light L _r-p1 as reflected light passes through the λ / 4 retardation layer 25 and further passes through the polarizing film 51. The linearly polarized light L _r-p1 emitted from the polarizing film 51 enters the λ / 4 retardation layer 52. The λ / 4 retardation layers 53 and 54 of the λ / 4 retardation layer 52 convert the linearly polarized light into right circularly polarized light and left circularly polarized light, respectively. There is no difference in intensity between the right circularly polarized light and the left circularly polarized light. Therefore, there is no difference in brightness between a portion of the second light reflection region 12 that can be seen through the λ / 4 retardation layer 53 and a portion that can be seen through the λ / 4 retardation layer 54.

  FIG. 8 is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 1 and 2 and the verification tool shown in FIG. 3 are overlapped. FIG. 9 is a cross-sectional view taken along line IX-IX of the structure shown in FIG. 8 and 9 illustrate a state in which only the verification tool 50 is rotated 45 ° clockwise as viewed from the observer side from the state illustrated in FIGS. 6 and 7.

  When the anti-counterfeit medium 10 and the verification tool 50 are arranged as shown in FIGS. 8 and 9, the first light reflection region 11 looks the same brightness as described with reference to FIGS. 6 and 7. This is because the light that the first light reflection region 11 uses for display is only the light that is selectively reflected by the circularly polarized light reflection layer 24.

  On the other hand, the 2nd light reflection area | region 12 looks darker compared with the case where the arrangement | positioning demonstrated referring FIG.6 and FIG.7 is employ | adopted. This will be described below.

In the arrangements shown in FIGS. 8 and 9, the transmission axis OP and the fast axis n _{A25 form} an angle of 45 °. Therefore, the linearly polarized light L _p-p1 emitted from the polarizing film 51 is converted into right circularly polarized light by the λ / 4 retardation layer 25. The right circularly polarized light becomes left circularly polarized light by being reflected by the light reflecting layer 22, and is converted to linearly polarized light L _r-p2 by being transmitted through the λ / 4 retardation layer 25. The plane of polarization of the linearly polarized light L _r-p2 is perpendicular to the transmission axis OP of the polarizing film 51. Therefore, the linearly polarized light L _r-p2 incident on the polarizing film 51 is absorbed by the polarizing film 51. As a result, in the arrangement shown in FIGS. 8 and 9, the second light reflection region 12 appears as a dark part.

  The anti-counterfeit medium 10 is supported on an article to be confirmed to be authentic. Even when it is not possible to discriminate between such an article with anti-counterfeit measures and a non-authentic product such as a counterfeit product with the naked eye, it is possible to discriminate them by using the verification tool 50, for example. For example, when the above-described image is not displayed when observing an article whose unknown whether it is authentic by the method described with reference to FIGS. 4 to 9, it is determined that the article is non-authentic. be able to. The change in the display image according to the arrangement of the forgery prevention medium 10 and the verification tool 50 cannot be reproduced with a copy of the forgery prevention medium 10. Further, it is difficult to copy the forgery prevention medium 10. Therefore, when the anti-counterfeit medium 10 is used, a higher anti-counterfeit effect can be achieved.

  Next, another embodiment of the present invention will be described.

  FIG. 10 is a plan view schematically showing a forgery prevention medium according to the second embodiment of the present invention. 11 is a cross-sectional view of the forgery prevention medium shown in FIG. 10 taken along line XI-XI.

The forgery prevention medium 10 is the same as the forgery prevention medium 10 described with reference to FIGS. 1 and 2 except that the following configuration is adopted. That is, in the forgery prevention medium 10 shown in FIGS. 10 and 11, the λ / 4 retardation layer 25 is separated from the light absorption layer 23 and the circularly polarized light reflection layer 24. In other words, in the forgery prevention medium 10, the first light reflection region 11 and the second light reflection region 12 are separated from each other, and the third light reflection region 13 including the light reflection layer 22 is interposed therebetween. Forming.

As shown in FIGS. 10 and 11, the third light reflection region 13 may not include a layer in front of the light reflection layer 22 included in the third light reflection region 13. Alternatively, the third light reflection region 13 may include an optically isotropic layer in front of the light reflection layer 22 included in the third light reflection region 13.

  Next, an image that is seen when natural light is irradiated onto the anti-counterfeit medium 10 and observed with the naked eye will be described.

  As described in the first embodiment, the first light reflecting region 11 emits only the right circularly polarized light selectively reflected by the circularly polarized light reflecting layer 24, and the second reflecting region 12 emits light having substantially the same intensity as the incident light. . The third reflection region 13 also emits light that has substantially the same intensity as the incident light. Therefore, when the forgery prevention medium 10 is irradiated with natural light and observed with the naked eye, the first light reflection region 11 is darker than the second light reflection region 12 and the third light reflection region 13. appear.

  Next, an image displayed when the anti-counterfeit medium 10 is observed using the verification tool 50 shown in FIG. 3 will be described.

  12 is a plan view schematically showing an example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 10 and 11 and the verification tool shown in FIG. 3 are overlapped.

  In FIG. 12, the false image preventing medium 10 and the verification tool 50 are arranged so that each of the λ / 4 retardation layers 53 and 54 faces the light reflection regions 11 to 13. In this case, as described with reference to FIGS. 4 and 5, in the first light reflecting region 11, the region 11 b facing the λ / 4 retardation layer 54 appears as a dark part, and is in the λ / 4 position. The region 11a facing the phase difference layer 53 looks brighter than the region 11b. In the second light reflection region 12, the region 12a facing the λ / 4 retardation layer 53 appears as a bright portion, and the region 12b facing the λ / 4 retardation layer 54 has the same brightness as the region 12a. Looks like.

  As described with reference to FIG. 5, when the polarizing film 51 is irradiated with natural light 80, the λ / 4 retardation layer 53 emits the right circularly polarized light 82, and the λ / 4 retardation layer 54 is left circularly polarized. 83 is released. The third light reflection region 13 converts right circularly polarized light into left circularly polarized light and converts left circularly polarized light into right circularly polarized light. That is, the reflected light from the third light reflection region 13 incident on the λ / 4 retardation layer 53 is left circularly polarized light, and the reflected light from the third light reflection region 13 incident on the λ / 4 retardation layer 54 is Right circularly polarized light. Therefore, in the third light reflection region 13, the region 13a facing the λ / 4 retardation layer 53 appears as a dark portion, and the region 13b facing the λ / 4 retardation layer 54 also appears as a dark portion.

  Next, an image that is seen when the verification tool 50 is turned over and superimposed on the forgery prevention medium 10 will be described.

13 is a plan view schematically showing another example of an image that can be observed when the forgery prevention medium shown in FIGS. 10 and 11 and the verification tool shown in FIG. 3 are overlapped. In FIG. 13, the verification tool 50 is turned upside down, and the transmission axis OP of the polarizing film 51 and the _fast axis n _{A25 of the} λ / 4 retardation layer 25 are orthogonal to each other.

  In this case, the first light reflection region 11 and the second light reflection region 12 appear with the same brightness as described with reference to FIGS. When the verification tool 50 is turned upside down, the verification tool 50 functions as a linear polarizer having a transmission axis OP. Therefore, in the third light reflection region 13, a region that can be observed through the λ / 4 retardation layer 53 appears as a bright portion, and a region that can be observed through the λ / 4 retardation layer 54 also appears as a bright portion. .

  14 is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 10 and 11 and the verification tool shown in FIG. 3 are overlapped. FIG. 14 illustrates a state in which only the verification tool 50 is rotated 45 ° clockwise as viewed from the observer side from the state illustrated in FIG. 13.

  In this case, the first light reflection region 11 and the second light reflection region 12 appear with the same brightness as described with reference to FIGS. In addition, the third light reflection region 13 appears with the same brightness as described with reference to FIG.

  When this anti-counterfeit medium 10 is supported by an article to be confirmed to be authentic, it is possible to discriminate between genuine and non-authentic products by the same method as described in the first embodiment. In addition, as described above, the change of the image displayed in the third light reflection region 13 according to the arrangement of the forgery prevention medium 10 and the verification tool 50 is different from the image displayed in the first light reflection region 11 and the second light reflection. This is different from the change in the image displayed in the region 12. Therefore, when an article whose identity is unknown or not does not cause the image change described above with respect to the third light reflection region 13, it can be determined that the article is a non-authentic product. Therefore, the use of this reduces the probability that a non-genuine product is erroneously determined to be a genuine product.

  Further, the forgery prevention medium 10 described with reference to FIGS. 10 and 11 has a more complicated structure than the forgery prevention medium 10 described with reference to FIGS. 1 and 2. Therefore, the anti-counterfeit medium 10 is more difficult to duplicate. Therefore, when this anti-counterfeit medium 10 is used, a higher anti-counterfeit effect can be achieved.

  Next, still another embodiment of the present invention will be described.

  FIG. 15 is a plan view schematically showing a forgery prevention medium according to the third embodiment of the present invention. 16 is a cross-sectional view of the forgery prevention medium shown in FIG. 15 taken along line XVI-XVI.

  The forgery prevention medium 10 is the same as the forgery prevention medium 10 described with reference to FIGS. 1 and 2 except that the following configuration is adopted. That is, in the anti-counterfeit medium 10 shown in FIGS. 15 and 16, the circularly polarized light reflection layer 24 is partially covered with the λ / 8 retardation layer 26. The portion corresponding to the λ / 8 retardation layer 26 in the forgery prevention medium 10 is the fourth light reflection region 14. The fourth light reflection region 14 is adjacent to the first light reflection region 11 and the second light reflection region 12 in the in-plane direction.

The λ / 8 retardation layer 26 includes, for example, a _fast axis along a direction indicated by an arrow n _A26 in FIG. 20 and a slow axis n _B26 (not shown in FIG. 20) perpendicular to the fast axis. Have. The λ / 8 phase difference layer 26 has a wavelength of λ and a plane of polarization (oscillation plane of the electric field vector) is incident on linearly polarized light oblique to the fast axis n _A26 , and the plane of polarization is the slow axis n _B26. And a second linearly polarized light whose plane of polarization is parallel to the fast axis n _A26 and whose phase is advanced by λ / 8 from the first linearly polarized light. The λ / 8 retardation layer 26 can be formed by a method similar to that described for the λ / 4 retardation layer 25.

The angle formed by the _fast axis n _{A26 of the} λ / 8 retardation layer 26 with respect to the _fast axis n _{A25 of the} λ / 4 retardation layer 25 is arbitrary. Here, as an example, the fast axis n _A26 and the fast axis n _A25 are orthogonal to each other.

  Next, an image that is seen when natural light is irradiated onto the anti-counterfeit medium 10 and observed with the naked eye will be described.

  As described in the first embodiment, the first light reflecting region 11 emits only the right circularly polarized light selectively reflected by the circularly polarized light reflecting layer 24, and the second reflecting region 12 emits light having substantially the same intensity as the incident light. . The fourth reflective region 14 also emits only the right circularly polarized light that is selectively reflected by the circularly polarized reflective layer 24. Therefore, when natural light is irradiated on the anti-counterfeit medium 10 and this is observed with the naked eye, the first light reflection region 11 and the fourth light reflection region 14 appear to have almost the same brightness and the second light. It looks darker than the reflective area 12.

  Next, an image displayed when the anti-counterfeit medium 10 is observed using the verification tool 50 shown in FIG. 3 will be described.

  FIG. 17 is a plan view schematically showing an example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped.

  In FIG. 17, the false image prevention medium 10 and the verification tool 50 are arranged so that each of the λ / 4 retardation layers 53 and 54 faces the light reflection regions 11, 12, and 14. In this case, as described with reference to FIGS. 4 and 5, in the first light reflecting region 11, the region 11 b facing the λ / 4 retardation layer 54 appears as a dark part, and is in the λ / 4 position. The region 11a facing the phase difference layer 53 looks brighter than the region 11b. In the second light reflection region 12, the region 12a facing the λ / 4 retardation layer 53 appears as a bright portion, and the region 12b facing the λ / 4 retardation layer 54 has the same brightness as the region 12a. Looks like.

  Of the fourth light reflecting region 14, the region 14 a facing the λ / 4 retardation layer 53 looks brighter than the region 14 b facing the λ / 4 retardation layer 54. This will be described with reference to FIG.

  FIG. 18 is a diagram schematically illustrating a state in which the fourth light reflection region reflects light when the forgery prevention medium illustrated in FIGS. 15 and 16 and the verification tool illustrated in FIG. 3 are overlapped. FIG. 18A shows a state in which the region 14a facing the λ / 4 retardation layer 53 in the fourth light reflecting region 14 reflects light. FIG. 18B shows a state in which the region 14 b facing the λ / 4 retardation layer 54 in the fourth light reflecting region 14 reflects light.

As shown in FIG. 18A, natural light L _i-n emitted from the light source 100 is incident on the linearly polarizing film 51. The polarizing film 51 emits linearly polarized light L _p-p1 having a polarization plane parallel to the transmission axis OP.

The linearly polarized light L _p-p1 emitted from the polarizing film 51 enters the λ / 4 retardation layer 53. The λ / 4 retardation layer 53 converts the linearly polarized light L _p-p1 into the right circularly polarized light L _pr .

The right circularly polarized light L _p−r emitted from the λ / 4 retardation layer 53 is incident on the λ / 8 retardation layer 26. The λ / 8 phase difference layer 26 converts the right circularly polarized light L _p-r into the right elliptically polarized light L _p-er . The trajectory of the electric field vector of the right elliptically polarized light L _p-er is an ellipse whose major axis is inclined 45 ° counterclockwise with respect to the _fast axis n _A26 when viewed from the circularly polarized light reflecting layer 24 side. Forming.

The right elliptically polarized light L _p-er emitted from the λ / 8 retardation layer 26 is incident on the circularly polarized light reflecting layer 24. Since the circularly polarized light reflection layer 24 has a right helical structure, it selectively reflects the right circularly polarized light _LAr-r and transmits other light components. The light component L _p−1 transmitted through the circularly polarized light reflecting layer 24 is absorbed by the light absorbing layer 23.

The right circularly polarized light _LAr-r selectively reflected by the circularly polarized light reflecting layer 24 is incident on the λ / 8 phase difference layer 26. The λ / 8 retardation layer 26 converts the right circularly polarized light L _Ar-r into the right elliptically polarized light L _Ar-er . The locus of the electric field vector of the right elliptically polarized light L _{Ar-er is} an ellipse whose major axis is inclined by 45 ° clockwise with respect to the _fast axis n _A53 when viewed from the λ / 4 retardation layer 53 side. Is forming.

The right elliptically polarized light L _Ar-er emitted from the λ / 8 retardation layer 26 is incident on the λ / 4 retardation layer 53. The λ / 4 retardation layer 53 converts the right elliptical polarization L _Ar-er into the right elliptical polarization L ′ _Ar-er . The locus of the end of the electric field vector of the right elliptically polarized light L ′ _Ar-er forms an ellipse whose major axis is parallel to the transmission axis OP when viewed from the polarizing film 51 side.

The elliptically polarized light L ′ _Ar-er emitted from the λ / 4 retardation layer 53 is incident on the linearly polarizing film 51. The polarizing film 51 transmits the linearly polarized light L _Ar-p1 having a polarization plane parallel to the transmission axis OP among the elliptically polarized light L ′ _Ar-er and absorbs other light components.

In this way, the linearly polarized light _LAr-p1 reaches the observer 200 as reflected light from the region 14a.

As shown in FIG. 18B, linearly polarized light L _p-p1 out of the natural light L _i-n emitted from the light source 100 is incident on the region 14b. Specifically, the linearly polarized light L _p-p1 is incident on the λ / 4 retardation layer 54. The λ / 4 retardation layer 54 converts the linearly polarized light L _p-p1 into the left circularly polarized light L _p-1 .

lambda / 4 left circular polarization phase difference layer 54 is released L _p-l is incident on the lambda / 8 retardation layer 26. The λ / 8 retardation layer 26 converts the left circularly polarized light L _p-l to the left elliptical polarized light L _p-el . The locus of the terminal of the electric field vector of the left elliptically polarized light L _p-el is an ellipse whose major axis is inclined 45 ° counterclockwise with respect to the _fast axis n _A26 when viewed from the circularly polarized light reflecting layer 24 side. Forming.

The left elliptically polarized light L _p-el emitted from the λ / 8 retardation layer 26 is incident on the circularly polarized light reflecting layer 24. Since the circularly polarized light reflecting layer 24 has a right helical structure, the circularly polarized light reflecting layer 24 selectively reflects the right circularly polarized light _LBr-r and transmits other light components. The light component L _p−1 transmitted through the circularly polarized light reflecting layer 24 is absorbed by the light absorbing layer 23.

Note that the circularly polarized light incident on the circularly polarized light reflection layer 24 is the right elliptically polarized light L _p-er in the region 14a, whereas the circularly polarized light incident on the circularly polarized light reflecting layer 24 is the left elliptically polarized light L _p-el in the region 14b. Therefore, the right circularly polarized light L _Br-r selectively reflected by the circularly polarized light reflecting layer 24 in the region 14b has a lower intensity than the right circularly polarized light L _Ar-r selectively reflected by the circularly polarized light reflecting layer 24 in the region 14a. .

The right circularly polarized light L _Br-r selectively reflected by the circularly polarized light reflecting layer 24 is incident on the λ / 8 phase difference layer 26. The λ / 8 retardation layer 26 converts the right circularly polarized light L _Br-r into right elliptically polarized light L _Br-er . The trajectory of the electric field vector of the right elliptically polarized light _{LBr-er is} an ellipse whose major axis is inclined by 45 ° clockwise with respect to the _fast axis n _A53 when viewed from the λ / 4 phase difference layer 53 side. Is forming.

The right elliptically polarized light L _Br-er emitted from the λ / 8 retardation layer 26 is incident on the λ / 4 retardation layer 53. The λ / 4 retardation layer 53 converts the right elliptically polarized light L _Br-er into the right elliptically polarized light L ′ _Br-er . The locus of the end of the electric field vector of the right elliptically polarized light L ′ _Br-er forms an ellipse whose major axis is parallel to the transmission axis OP when viewed from the polarizing film 51 side.

The elliptically polarized light L ′ _Br-er emitted from the λ / 4 retardation layer 53 is incident on the linearly polarizing film 51. The polarizing film 51 transmits linearly polarized light _LBr-p1 having a polarization plane parallel to the transmission axis OP among the elliptically polarized light L′ _Br-er and absorbs other light components.

In this manner, the linearly polarized light L _Br-p1 reaches the observer 200 as the reflected light from the region 14b.

As described above, the right circularly polarized light L _Br-r selectively reflected by the circularly polarized light reflecting layer 24 in the region 14b has an intensity compared to the right circularly polarized light L _Ar-r selectively reflected by the circularly polarized light reflecting layer 24 in the region 14a. Smaller than. Accordingly, the linearly polarized light L _Br-p1 emitted from the region 14b has a lower intensity than the linearly polarized light L _Ar-p1 emitted from the region 14a. Therefore, the region 14a looks brighter than the region 14b.

  Next, an image that is seen when the verification tool 50 is turned over and superimposed on the forgery prevention medium 10 will be described.

  19 is a plan view schematically showing another example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped.

In FIG. 19, the verification tool 50 is turned upside down and parallel to the transmission axis OP of the polarizing film 51 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26. In this case, the first light reflection region 11 and the second light reflection region 12 appear with the same brightness as described with reference to FIGS.

When the verification tool 50 is turned upside down, the verification tool 50 functions as a linear polarizer having a transmission axis OP. In the arrangement shown in FIG. 19, the transmission axis OP of the polarizing film 51 and the _fast axis n _{A26 of the} λ / 8 retardation layer 26 are parallel, and therefore, in the fourth light reflecting region 14, The linearly polarized light whose polarization plane is parallel to the _fast axis n _A26 of the λ / 8 retardation layer 26 is incident. The circularly polarized light reflection layer 24 selectively reflects right circularly polarized light out of the linearly polarized light incident thereon, and transmits left circularly polarized light. The left circularly polarized light is absorbed by the light absorbing layer 23, and the right circularly polarized light is incident on the λ / 8 retardation layer 26.

  The λ / 8 retardation layer 26 converts the previous right circularly polarized light into right elliptically polarized light. The locus of the end of the electric field vector of the right elliptical polarization forms an ellipse whose major axis is inclined 45 ° counterclockwise with respect to the transmission axis OP when viewed from the polarizing film 51 side. The right elliptically polarized light emitted from the λ / 8 retardation layer 26 is incident on the polarizing film 51. The polarizing film 51 transmits linearly polarized light whose polarization plane is parallel to the transmission axis OP among right elliptical polarized light. The λ / 4 retardation layers 53 and 54 convert the linearly polarized light into right circularly polarized light and left circularly polarized light having the same intensity, respectively. Therefore, in the fourth light reflection region 14, the region that can be observed through the λ / 4 retardation layer 53 and the region that can be observed through the λ / 4 retardation layer 54 appear to have the same brightness.

  20 is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped.

  FIG. 20 shows a state in which only the verification tool 50 is rotated 45 ° counterclockwise from the state shown in FIG. 19 when viewed from the observer side. In this case, the first light reflection region 11 and the second light reflection region 12 appear with the same brightness as described with reference to FIGS.

In the arrangement shown in FIG. 20, when the anti-counterfeit medium 10 is viewed from the verification tool 50 side, the transmission axis OP of the polarizing film 51 is counterclockwise with respect to the _fast axis n _A26 of the λ / 8 retardation layer 26. The angle is 45 °. Accordingly, in the fourth light reflection region 14, the λ / 8 retardation layer 26 converts the linearly polarized light emitted from the polarizing film 51 into right elliptically polarized light. The locus of the end of the electric field vector of the right elliptically polarized light is 45 ° clockwise with respect to the _fast axis n _{A26 of the} λ / 8 phase difference layer 26 when viewed from the circularly polarized light reflecting layer 24 side. Forming an ellipse.

  The right elliptically polarized light is incident on the circularly polarized light reflecting layer 24. The circularly polarized light reflecting layer 24 selectively reflects right circularly polarized light out of the right elliptically polarized light incident thereon and transmits other light components. The left circularly polarized light is absorbed by the light absorbing layer 23, and the right circularly polarized light is incident on the λ / 8 retardation layer 26.

  The λ / 8 retardation layer 26 converts the previous right circularly polarized light into right elliptically polarized light. The locus of the end of the electric field vector of the right elliptical polarization forms an ellipse whose major axis is inclined 45 ° counterclockwise with respect to the transmission axis OP when viewed from the polarizing film 51 side. The right elliptically polarized light emitted from the λ / 8 retardation layer 26 is incident on the polarizing film 51. The polarizing film 51 transmits linearly polarized light whose polarization plane is parallel to the transmission axis OP among right elliptical polarized light. The λ / 4 retardation layers 53 and 54 convert the linearly polarized light into right circularly polarized light and left circularly polarized light having the same intensity, respectively. Therefore, in the fourth light reflection region 14, the region that can be observed through the λ / 4 retardation layer 53 and the region that can be observed through the λ / 4 retardation layer 54 appear to have the same brightness.

  In the arrangement of FIG. 19, linearly polarized light is incident on the circularly polarized reflective layer 24, whereas right elliptically polarized light is incident on the circularly polarized reflective layer 24 in the arrangement of FIG. Therefore, according to the arrangement of FIG. 20, the intensity of the right circularly polarized light selectively reflected by the circularly polarized light reflecting layer 24 is higher than that of the arrangement of FIG. That is, in the arrangement of FIG. 20, the fourth light reflection region 14 appears brighter than the arrangement of FIG.

  FIG. 21 is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped.

  FIG. 21 shows a state in which only the verification tool 50 is rotated 90 ° counterclockwise from the state shown in FIG. In this case, the first light reflection region 11 and the second light reflection region 12 appear with the same brightness as described with reference to FIGS. Further, the fourth light reflection region 14 looks the same brightness as when the anti-counterfeit medium 10 and the verification tool 50 are arranged as shown in FIG.

  22 is a plan view schematically showing still another example of an image that can be observed when the forgery prevention medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped.

  FIG. 22 illustrates a state in which only the verification tool 50 is rotated 135 ° counterclockwise from the state illustrated in FIG. 19 when viewed from the observer side. In this case, the first light reflection region 11 and the second light reflection region 12 appear with the same brightness as described with reference to FIGS.

In the arrangement shown in FIG. 22, when the anti-counterfeit medium 10 is viewed from the verification tool 50 side, the transmission axis OP of the polarizing film 51 is clockwise with respect to the _fast axis n _A26 of the λ / 8 retardation layer 26. The angle is 45 °. Accordingly, in the fourth light reflection region 14, the λ / 8 retardation layer 26 converts the linearly polarized light emitted from the polarizing film 51 into left elliptically polarized light. The locus of the end of the electric field vector of the left elliptical polarization is 45 ° counterclockwise with respect to the _fast axis n _{A26 of the} λ / 8 phase difference layer 26 when viewed from the circularly polarized reflection layer 24 side. An inclined ellipse is formed.

  This left elliptical polarized light is incident on the circularly polarized light reflecting layer 24. The circularly polarized light reflecting layer 24 selectively reflects right circularly polarized light out of the left elliptically polarized light incident thereon and transmits other light components. The left circularly polarized light is absorbed by the light absorbing layer 23, and the right circularly polarized light is incident on the λ / 8 retardation layer 26.

  The λ / 8 retardation layer 26 converts the previous right circularly polarized light into right elliptically polarized light. The locus of the end of the electric field vector of the right elliptical polarization forms an ellipse whose major axis is inclined 45 ° counterclockwise with respect to the transmission axis OP when viewed from the polarizing film 51 side. The right elliptically polarized light emitted from the λ / 8 retardation layer 26 is incident on the polarizing film 51. The polarizing film 51 transmits linearly polarized light whose polarization plane is parallel to the transmission axis OP among right elliptical polarized light. The λ / 4 retardation layers 53 and 54 convert the linearly polarized light into right circularly polarized light and left circularly polarized light having the same intensity, respectively. Therefore, in the fourth light reflection region 14, the region that can be observed through the λ / 4 retardation layer 53 and the region that can be observed through the λ / 4 retardation layer 54 appear to have the same brightness.

  In the arrangement of FIG. 19, linearly polarized light is incident on the circularly polarized light reflecting layer 24, whereas in the arrangement of FIG. 22, left elliptically polarized light is incident on the circularly polarized light reflecting layer 24. Therefore, according to the arrangement of FIG. 22, the intensity of the right circularly polarized light selectively reflected by the circularly polarized light reflecting layer 24 is smaller than that of the arrangement of FIG. That is, in the arrangement of FIG. 22, the fourth light reflection region 14 looks darker than the arrangement of FIG.

When this anti-counterfeit medium 10 is supported by an article to be confirmed to be authentic, it is possible to discriminate between genuine and non-authentic products by the same method as described in the first embodiment. In addition, as described above, the change of the image displayed in the fourth light reflection area 14 according to the arrangement of the forgery prevention medium 10 and the verification tool 50 is different from the image displayed in the first light reflection area 11 and the second light reflection. This is different from the change in the image displayed in the region 12. Therefore, when an article whose identity is unknown or not does not cause the above-described image change with respect to the fourth light reflection region 13, it can be determined that the article is non-authentic. Therefore, the use of this reduces the probability that a non-genuine product is erroneously determined to be a genuine product.

  Further, the forgery prevention medium 10 described with reference to FIGS. 15 and 16 has a more complicated structure than the forgery prevention medium 10 described with reference to FIGS. 1 and 2. Therefore, the anti-counterfeit medium 10 is more difficult to duplicate. Therefore, when this anti-counterfeit medium 10 is used, a higher anti-counterfeit effect can be achieved.

  Various modifications can be made to the forgery prevention medium 10 described above. For example, the entire front surface of the circularly polarized light reflecting layer 24 may be covered with the λ / 8 phase difference layer 26, or a part of the front surface of the circularly polarized light reflecting layer 24 may be covered with the λ / 8 phase difference layer 26. A part thereof may be covered with a λ / 4 retardation layer.

  The light absorption layer 23 may be a colored layer. Further, a part or the whole of the light absorption layer 23 may be replaced with a light reflection layer.

  The light reflecting layer 22 may be a color-shifting pigment-containing layer. The light reflection layer 22 may be a metal reflection layer having a relief structure.

  Each retardation layer included in the anti-counterfeit medium 10 may be colored with a dye and / or a pigment so as not to block reflected light. For example, the colored layer may be sandwiched between a pair of retardation layers, and one retardation layer may be configured by them. Alternatively, a colored layer may be provided in front of and / or behind the retardation layer.

  The twist direction of the helical structure of the cholesteric liquid crystal forming the circularly polarized light reflection layer 24 may be either left or right. A cholesteric liquid crystal layer having a clockwise helical structure and a cholesteric liquid crystal layer having a counterclockwise helical structure may be used in combination. The circularly polarized light reflection layer 24 may be formed using, for example, a material obtained by pulverizing cholesteric liquid crystal and dispersing it in a resin.

  The front surface of the anti-counterfeit medium 10 may be covered with a protective layer.

  The back surface of the anti-counterfeit medium 10, here, the surface on which the reflective layer 22 is not formed, of the two main surfaces of the base material 21 may be subjected to adhesion or adhesion processing. That is, an adhesive label that can be used as an anti-counterfeit label may be formed using the anti-counterfeit medium 10.

  The anti-counterfeit medium 10 can be applied to printed matter by various methods. For example, you may affix said adhesive label on printed matter. In this case, the base material 21 may be provided with cuts or perforations. That is, you may employ | adopt the structure where the base material 21 is torn from an incision when it is going to peel off a label. Of course, the forgery prevention medium 10 can also be affixed to articles other than printed matter.

  A transfer foil containing the anti-counterfeit medium 10 may be formed and used to attach the anti-counterfeit medium 10 to the article.

  FIG. 23 is a cross-sectional view schematically showing an example of a transfer foil. A transfer foil 90 shown in FIG. 23 includes a base material 91. On the base material 91, a peeling layer 92, an anti-counterfeit medium 10, and an adhesive layer 93 are sequentially laminated.

  The front surface of the anti-counterfeit medium 10 faces the base material 91. The forgery prevention medium 10 may not include the base material 21 described with reference to FIG.

  When the anti-counterfeit medium 10 is applied to a printed matter, it may be cut into paper in a form called a thread (also called a strip, a filament, a thread, a safety strip, or the like).

  Hereinafter, materials that can be used for the anti-spoofing medium 10 will be described.

  Examples of the material of the base material 21 include synthetic resin films such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, and polystyrene. A natural resin film, synthetic paper, paper, glass plate, aluminum foil, or the like can be used alone or in combination as a composite. The thickness may be appropriately selected according to the purpose of use of the forgery prevention medium.

  The material used for the light reflecting layer 22 is not particularly limited as long as light reflectivity is obtained. For example, a metal or an alloy such as aluminum, gold, silver, or copper can be used. These materials can be used alone or laminated. The light reflecting layer 22 can be formed using a known method such as vacuum deposition or sputtering, for example. The thickness of the light reflection layer 22 is, for example, in the range of 50 to 1000 mm.

  The light absorption layer 23 can be formed using, for example, black ink in which carbon black is dispersed in a resin. The light absorption layer 23 may be a chromatic color layer.

  The circularly polarized light reflecting layer 24 can be obtained, for example, by aligning a chiral two-dimensional or three-dimensional crosslinkable liquid crystal substance and causing a crosslinking reaction in this state.

  As described above, the circularly polarized light reflecting layer 24 made of cholesteric liquid crystal exhibits selective reflectivity, and selectively reflects right circularly polarized light or left circularly polarized light having a wavelength equal to the pitch of the helical structure. The pitch of the helical structure can be controlled using temperature and / or a chiral agent, thereby creating the desired reflection color by the cholesteric liquid crystal. A liquid crystal having a helical structure has its optical characteristics only when the molecules are arranged in layers and are uniformly arranged in the layers.

  The orientation of each molecular layer can be controlled by a known method such as an orientation layer or an electric field or a magnetic field. As a typical method for fixing the alignment, there is a method in which a chiral three-dimensional cross-linkable liquid crystal and a polyfunctional polymer compound are combined and irradiated with ultraviolet rays to cause three-dimensional cross-linking. By this method, a cholesteric polymer liquid crystal having a fixed helical structure can be obtained.

  As the starting material of the cholesteric polymer liquid crystal, all cholesteric liquid crystals can be used as long as the pitch of the helical structure is equal to the wavelength of light in the range from ultraviolet to infrared. Accordingly, a liquid crystal substance having a chiral phase can be produced by adding a chiral substance to a liquid crystal having a nematic or smectic structure. The kind and molecular weight of the chiral substance determine the twist direction and pitch of the helical structure, and thus the wavelength of the reflected light. Furthermore, a liquid crystal having an irregular carbon in the structure can have a helical structure without adding a chiral substance. Changing the temperature of the helical structure is also effective for changing the temperature. However, since the pitch is long when the temperature is low and short when the temperature is high, the reflected light enters the infrared region if the temperature is too low, and if it is high, the reflected light enters the ultraviolet region except for absorption by molecules, and isotropic phase. And no longer exhibits liquid crystallinity. Therefore, in order to obtain reflected light necessary for design properties, anti-counterfeiting properties, etc., it is necessary to appropriately manage depending on which wavelength is used.

  The starting material has a polymerizable group, a polycondensable group or a group effective for polyaddition, and a conventionally known energy ray curable compound is used, and in particular, two or more energy ray curable compounds in the molecule are used. It is preferable to contain a monomer or oligomer having a functional group. As the radical photopolymerizable monomer, conventionally known, for example, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, etc. Other functional oligomers such as a polyfunctional monomer, polyurethane polyacrylate, epoxy resin-based polyacrylate, and acrylic polyol polyacrylate are preferred. Monofunctional monomers include alkyl (C1 to C18) (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, alkylene (C2 to C4) glycol (meth) acrylate, alkoxy (C1 to C10). ) Alkyl (C2-C4) (meth) acrylate, polyalkylene (C2-C4) glycol (meth) acrylate, alkoxy (C2-C10) polyalkylene (C2-C4) glycol (meth) acrylate, and the like. Examples of the cationic photopolymerizable monomer include conventionally known aromatic epoxy compounds, alicyclic epoxy compounds, and glycidyl ester compounds.

  In the production of a cholesteric liquid crystal layer, typically, a polymerization initiator or the like is used as necessary to cause energy ray curing. As the polymerization initiator to be used, a known one having properties suitable for the energy beam to be irradiated is selected. For example, conventionally known photopolymerization initiators can be used. Examples of radical photopolymerization initiators include known acetophenones such as α-hydroxyacetophenone and α-aminoacetophenone, benzoin ethers, benzyl ketals, α-dicarbonyls, α-acyloxime esters, and the like. Can be used. Specific uses include α-aminoacetophenone, acetophenone diethyl ketal, benzyldimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylphenylpropanone, benzophenone, Michler's ketone, isopropylthioxanthone, benzophenone and N- The combined use with methyldiethanolamine is mentioned. As the cationic photopolymerization initiator, for example, a conventionally known one can be used without particular limitation. Preferably, the cationic photopolymerization initiator is appropriately used in combination with known sensitizers and peroxides. Examples of the combination include allyl iodonium salt-α-hydroxyacetophenone, triallylsulfonium salt, metallocene compound-peroxide combination, metallocene compound-thioxanthone combination, metallocene compound-anthracene combination.

  The cholesteric liquid crystal layer is formed on the base material so that the above-described materials are formed by a known coating method or printing method such as a comma coater, gravure, or micro gravure coater offset to a thickness of 0.5 to 20 μm, preferably 2 to 10 μm It is obtained by coating and crosslinking with a known active energy ray irradiation apparatus such as a metal halide lamp or a high-pressure mercury lamp. In order to advance the crosslinking promptly, the active energy ray irradiation environment can be reduced by using an inert gas, such as nitrogen, to reduce the oxygen concentration, or by bonding with a film such as polyethylene to prevent oxygen inhibition.

  In coating, a solvent may be appropriately selected and dissolved, and the dilution rate may be set as necessary.

  Alternatively, an adhesive may be applied to the liquid crystal surface of the cholesteric liquid crystal film constructed on the substrate, and transferred to another substrate in a shape as required.

  The retardation layer such as the λ / 4 retardation layer 25 can be formed of, for example, a nematic or smectic liquid crystal. As the material of the retardation layer, a material having a polymerizable group, a polycondensable group, or a group effective for polyaddition in the same manner as described for the cholesteric liquid crystal forming the circularly polarized reflection layer 24 is preferable. An energy ray curable compound can be used.

  Further, the same polymerization initiator as that described for the cholesteric liquid crystal can be used, and the production method is also the same.

  The required film thickness depends on the difference between the refractive index and the birefringence of the liquid crystal. The film thickness of the liquid crystal that gives a phase difference of λ / 2 to light having a wavelength of 550 nm on the reflective substrate is about 1.4 μm when the refractive index difference is 0.1, and the phase difference of λ / 4 Is about 0.7 μm.

  An apparatus similar to that described for the cholesteric liquid crystal can also be used for coating, and dissolution and dilution can be appropriately performed as necessary.

  An alignment film may be used for alignment of the liquid crystal of the cholesteric liquid crystal layer, nematic or smectic liquid crystal layer. As a material for the alignment film, for example, a known resin such as polyvinyl alcohol (PVA) or polyimide can be used.

  A resin solution in which these resins are appropriately dissolved is applied onto a reflective substrate using a coating method such as wire bar, gravure, or microgravure, and the coating film is dried. The film thickness is, for example, in the range of 0.1 μm to 20 μm, preferably between 0.3 μm and 10 μm.

  Thereafter, a rubbing process is performed by rubbing the alignment film surface with a rubbing cloth to obtain an alignment film. For the rubbing cloth, for example, a known material such as cotton or velvet can be used.

  A more preferable retardation and circularly polarized light can be obtained by installing a liquid crystal on the alignment film thus prepared.

  A general material can be used as the adhesive for applying the forgery prevention medium 10 to a printed matter or the like. For example, an adhesive such as vinyl chloride-vinyl acetate copolymer, polyester polyamide, acrylic, butyl rubber, natural rubber, silicon, polyisobutyl, etc. can be used alone, or these adhesives can be used. Aggregating components such as alkyl methacrylates, vinyl esters, acrylonitrile, styrene, vinyl monomers, unsaturated carboxylic acids, hydroxy group-containing monomers, modifying components such as acrylonitrile, polymerization initiators, plasticizers, curing agents, curing What added additives, such as an accelerator and antioxidant, as needed can also be used. For the formation of the adhesive layer, a known gravure printing method, offset printing method, screen printing method or other printing method or bar coating method, gravure method, roll coating method or other coating method can be used.

  Furthermore, what formed the adhesive in the separator previously may be prepared, and a separator may be peeled off and bonded together to the forgery prevention medium 10. FIG.

  Further, in order to facilitate the handling of the anti-counterfeit medium 10 subjected to the adhesive processing, a release paper or a release film that has been subjected to a release treatment may be placed on the adhesive layer.

  Examples of the present invention will be described below.

Example 1
A single-sided aluminum vapor-deposited polyethylene terephthalate (vapor-deposited PET) film having a thickness of 25 μm was prepared, and black ink was gravure-printed as a light-absorbing layer on a part of the aluminum vapor-deposited surface using a flatbed proof press. The following inks were used.

Ink ink (FD Carton ACE Conch ink Toyo Ink Co., Ltd.)
After printing the ink, it was irradiated with ultraviolet rays of 200 mJ / cm ² using a high pressure mercury lamp.

  Next, an alignment film ink solution was applied to the entire surface by a bar coater method. The composition of the applied alignment film ink is shown below.

Polyvinyl alcohol resin (trade name: PVA-117, Kuraray Co., Ltd.) 10% by weight
90% by weight of solvent (water)
This coating film was formed so that the dry film thickness was 2 μm.

  Subsequently, this coating film was rubbed using a rubbing cloth (FINE PUFF YA-20-R manufactured by Yoshikawa Chemical Co., Ltd.). Thereby, an alignment film was obtained.

  Next, in order to form a circularly polarized light reflection layer, gravure printing was performed on the black ink layer described above using a flat table proofing machine so that the cured film thickness was 5 μm.

Nematic liquid crystal (Paliocolor LC242 manufactured by BASF Corp.) 30 parts by weight Chiral agent (Paliocolor LC756 manufactured by BASF Corp.) 1.5 parts by weight Polymerization initiator (Irgacure 184 manufactured by Ciba Geigy Co., Ltd.) 1.5 parts by weight Solvent (Methyl ethyl ketone) 67 parts by weight.

After printing, it was dried at 80 ° C. for 1 minute, and then cured by irradiation with a high-pressure mercury lamp at 500 mJ / cm ² to obtain a circularly polarized reflective layer.

  Next, in order to form a λ / 4 retardation layer adjacent to the circularly polarized light reflecting layer, an ink having the following composition was subjected to gravure printing using a flat table calibrator so that the cured film thickness was 1.0 μm.

Nematic liquid crystal (Paliocolor LC242 manufactured by BASF Corp.) 30 parts by weight Polymerization initiator (Irgacure 184 manufactured by Ciba Geigy Co., Ltd.) 1.5 parts by weight Solvent (methyl ethyl ketone) 68.5 parts by weight 1 minute at 100 ° C. after printing After drying, it was cured by irradiation with 500 mJ / cm ^{2 with} a high-pressure mercury lamp. After the curing process, an anti-counterfeit medium was obtained.

  The counterfeit prevention medium described above with reference to FIG. 3 was superimposed on the anti-counterfeit medium so that the phase difference layer 52 side faces the anti-counterfeit medium, and the anti-counterfeit medium was observed in this state. As a result, the region of the anti-counterfeit medium on which the circularly polarized reflective layer is formed appears as a dark portion when observed through a portion corresponding to the λ / 4 phase difference layer 54 of the verification tool 50, and When observed through a portion corresponding to the λ / 4 retardation layer 53, it was seen as a bright portion.

  On the other hand, the region where the λ / 4 retardation layer was formed in the anti-counterfeit medium appeared as a bright portion when observed in either part of the verification tool.

  Next, the anti-counterfeit medium and the verification tool 50 were overlapped so that the linearly polarizing film 51 faced the anti-counterfeit medium. At this time, in the arrangement in which the crystal orientation direction of the λ / 4 retardation layer included in the forgery prevention medium and the transmission axis OP of the linearly polarizing film 51 are parallel or orthogonal, the λ / 4 retardation layer of the forgery prevention medium is Reflected light was observed in the formed area. However, if the angle formed by the crystal orientation direction of the λ / 4 retardation layer included in the forgery prevention medium and the transmission axis OP of the polarizing film 51 is 45 °, the λ / 4 retardation layer is formed in the forgery prevention medium. The area was clearly darkened. On the other hand, in the forgery prevention medium, the region where the circularly polarized light reflecting layer was formed became a bright portion because the reflected light returned regardless of the angle of placing the verification tool, and the appearance did not change.

  Next, this anti-counterfeit medium was color copied and verified by the same method as described above using a verification tool. As a result, no change in brightness could be confirmed.

(Example 2)
Example 1 except that the λ / 4 retardation layer is formed without being adjacent to the circularly polarizing reflection layer portion, thereby providing a region where neither the circularly polarizing reflection layer nor the λ / 4 retardation layer is formed on the aluminum deposition surface. The anti-counterfeit medium was obtained by the same method.

  The verification tool 50 was stacked on the forgery prevention medium obtained above so that the retardation layer 52 faced the forgery prevention medium, and the forgery prevention medium was observed in this state. As a result, the region of the anti-counterfeit medium on which the circularly polarized reflective layer is formed appears as a dark portion when observed through a portion corresponding to the λ / 4 phase difference layer 54 of the verification tool 50, and When observed through a portion corresponding to the λ / 4 retardation layer 53, it was seen as a bright portion.

  On the other hand, the region where the λ / 4 retardation layer was formed in the anti-counterfeit medium appeared as a bright portion when observed through any part of the verification tool.

  Further, the region where neither the circularly polarized light reflection layer nor the λ / 4 phase difference layer of the anti-counterfeit medium was seen as a dark part when observed through either part of the verification tool.

  Next, the anti-counterfeit medium and the verification tool 50 were stacked so that the polarizing film 51 and the anti-counterfeit medium face each other. At this time, in the arrangement in which the crystal orientation direction of the λ / 4 retardation layer included in the forgery prevention medium and the transmission axis OP of the polarizing film 51 are parallel or orthogonal, the λ / 4 retardation layer is formed in the forgery prevention medium. Reflected light was observed in the area. However, if the angle formed by the crystal orientation direction of the λ / 4 retardation layer included in the forgery prevention medium and the transmission axis OP of the polarizing film 51 is 45 °, the λ / 4 retardation layer is formed in the forgery prevention medium. The area was clearly darkened. On the other hand, the region in which the circularly polarized reflective layer is formed and the region in which neither the circularly polarized reflective layer nor the λ / 4 retardation layer is formed in the anti-counterfeit medium are bright portions regardless of the angle at which the verification tool 50 is placed. It looked and the way it looked did not change.

  This anti-counterfeit medium was color copied and verified by the same method as described above using a verification tool. As a result, no change in brightness could be confirmed.

Example 3
The PVA solution was applied on the circularly polarized reflective layer with a gravure printing machine and dried. Further, the PVA layer was rubbed in the same direction as the λ / 4 retardation layer, and a λ / 8 retardation layer was formed thereon. Except for this, an anti-counterfeit medium was prepared in the same manner as in Example 1.

  The anti-counterfeit medium obtained above and the verification tool 50 were overlapped so that the phase difference layer 52 and the anti-counterfeit medium face each other, and the anti-counterfeit medium was observed in this state. As a result, the region of the anti-counterfeit medium in which only the circularly polarized reflective layer is formed appears as a dark portion when observed through a portion corresponding to the λ / 4 phase difference layer 54 of the verification tool 50, and the verification tool 50. When observed through a portion corresponding to the λ / 4 retardation layer 53, it was seen as a bright portion.

  Further, in the anti-counterfeit medium, the region where the λ / 8 retardation layer is formed is formed only by the circularly polarized reflection layer when observed through the portion corresponding to the λ / 4 retardation layer 53 of the verification tool 50. Although the brightness is lower than that of the region thus formed, it appears as a bright portion, and when observed through a portion corresponding to the λ / 4 phase difference layer 54 of the verification tool 50, it passes through a portion corresponding to the λ / 4 phase difference layer 53. However, the brightness was not as high as that observed, but it appeared as a bright part.

  On the other hand, the region of the anti-counterfeit medium where the λ / 4 retardation layer was formed appeared as a bright portion when observed through any part of the verification tool 50.

  Next, the anti-counterfeit medium and the verification tool 50 were stacked so that the polarizing film and the anti-counterfeit medium face each other. At this time, when the crystal orientation direction of the λ / 4 retardation layer included in the forgery prevention medium and the transmission axis OP of the polarizing film 51 are parallel or orthogonal, the λ / 4 retardation layer of the forgery prevention medium is Reflected light was observed in the formed area. However, if the angle formed by the crystal orientation direction of the λ / 4 retardation layer included in the forgery prevention medium and the transmission axis OP of the polarizing film 51 is 45 °, the λ / 4 retardation layer is formed in the forgery prevention medium. The area was clearly darkened.

  On the other hand, the region of the anti-counterfeit medium on which the circularly polarized reflective layer was formed appeared as a bright part regardless of the angle at which the verification tool was placed, and the appearance did not change. The brightness of the anti-counterfeit medium in which the λ / 8 retardation layer was formed varied depending on the angle formed by the crystal orientation direction of the λ / 8 retardation layer and the transmission axis OP of the polarizing film 51. The region in which the λ / 8 retardation layer is formed in the anti-counterfeit medium in the arrangement in which the crystal orientation direction of the λ / 8 retardation layer is parallel to the transmission axis OP of the polarizing film 51 and the arrangement in which these are orthogonal to each other. Appeared as a bright part, and the brightness was the same. When the verification tool 50 was rotated 45 ° counterclockwise, the intensity of the reflected light was increased, and the brightness of the region where the λ / 8 phase difference layer was formed in the anti-counterfeit medium was increased. On the other hand, if the verification tool is rotated 45 ° clockwise from the arrangement in which the crystal orientation direction of the λ / 8 phase difference layer and the transmission axis OP of the polarizing film 51 are parallel, the intensity of the reflected light is reduced, and counterfeiting is prevented. The brightness of the region where the λ / 8 retardation layer was formed in the medium was lower.

  This anti-counterfeit medium was color copied and verified by the same method as described above using a verification tool. As a result, no change in brightness could be confirmed.

The top view which shows roughly the forgery prevention medium of 1st Embodiment of this invention. Sectional drawing along the II-II line of the forgery prevention medium shown in FIG. The exploded view which shows roughly an example of the verification tool used with the determination method of this invention. FIG. 4 is a plan view schematically showing an example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 1 and 2 and the verification tool shown in FIG. 3 are overlapped. Sectional drawing along the VV line of the structure shown in FIG. The top view which shows schematically the other example of the image which can be observed when the forgery prevention medium shown in FIG.1 and FIG.2 and the verification tool shown in FIG.3 are piled up. Sectional drawing along the VII-VII line of the structure shown in FIG. FIG. 4 is a plan view schematically showing still another example of an image that can be observed when the anti-counterfeit medium shown in FIGS. 1 and 2 and the verification tool shown in FIG. 3 are overlapped. Sectional drawing along the IX-IX line of the structure shown in FIG. The top view which shows roughly the forgery prevention medium of 2nd Embodiment of this invention. Sectional drawing along the XI-XI line of the forgery prevention medium shown in FIG. FIG. 12 is a plan view schematically showing an example of an image that can be observed when the forgery prevention medium shown in FIGS. 10 and 11 and the verification tool shown in FIG. 3 are overlapped. FIG. 12 is a plan view schematically showing another example of an image that can be observed when the forgery prevention medium shown in FIGS. 10 and 11 and the verification tool shown in FIG. 3 are overlapped. FIG. 12 is a plan view schematically showing still another example of an image that can be observed when the forgery prevention medium shown in FIGS. 10 and 11 and the verification tool shown in FIG. 3 are overlapped. The top view which shows roughly the forgery prevention medium of 3rd Embodiment of this invention. Sectional drawing along the XVI-XVI line of the forgery prevention medium shown in FIG. FIG. 17 is a plan view schematically showing an example of an image that can be observed when the forgery prevention medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped. The figure which shows a mode that a 4th light reflection area reflects light when the forgery prevention medium shown in FIG.15 and FIG.16 and the verification tool shown in FIG. 3 are piled up. FIG. 17 is a plan view schematically showing another example of an image that can be observed when the forgery prevention medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped. FIG. 17 is a plan view schematically showing still another example of an image that can be observed when the forgery prevention medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped. FIG. 17 is a plan view schematically showing still another example of an image that can be observed when the forgery prevention medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped. FIG. 17 is a plan view schematically showing still another example of an image that can be observed when the forgery prevention medium shown in FIGS. 15 and 16 and the verification tool shown in FIG. 3 are overlapped. Sectional drawing which shows an example of the transfer foil of this invention roughly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Anti-counterfeit medium, 11 ... 1st light reflection area | region, 12 ... 2nd light reflection area | region, 13 ... 3rd light reflection area | region, 14 ... 4th light reflection area | region, 21 ... Base material, 22 ... Light reflection layer, 23 DESCRIPTION OF SYMBOLS ... Light absorption layer, 24 ... Circularly polarized light reflection layer, 25 ... (lambda) / 4 phase difference layer, 26 ... (lambda) / 8 phase difference layer, 50 ... Verification tool, 51 ... Linearly polarized film, 52 ... (lambda) / 4 phase difference layer, 53 ... λ / 4 retardation layer, 54 ... λ / 4 retardation layer, 90 ... transfer foil, 91 ... substrate, 92 ... peeling layer, 93 ... adhesive layer.

Claims (12)

Comprising first and second light reflecting regions arranged in an in-plane direction;
The first light reflection region includes a circularly polarized light reflection layer,
The anti-counterfeit medium, wherein the second light reflection region includes a light reflection layer and a λ / 4 phase difference layer facing the front surface thereof.   The forgery prevention medium according to claim 1, wherein the first light reflection area is adjacent to the second light reflection area.   The first and second light reflecting areas further include a third light reflecting area aligned in the in-plane direction, the third light reflecting area includes a light reflecting layer, and the third light reflecting area includes The anti-counterfeit medium according to claim 1, wherein the anti-counterfeit medium according to claim 1, wherein the anti-counterfeit medium includes no layer or only an optically isotropic layer in front of the light reflecting layer.   The forgery prevention according to any one of claims 1 to 3, wherein the first light reflection region further includes a λ / 8 retardation layer covering at least a part of the circularly polarized light reflection layer. Medium.   The forgery prevention medium according to any one of claims 1 to 3, wherein the first light reflection region further includes a λ / 8 phase difference layer partially covering the circularly polarized light reflection layer. .   6. The medium for preventing forgery according to claim 1, wherein the circularly polarized light reflection layer is a cholesteric liquid crystal layer.   The forgery prevention medium according to claim 1, wherein the λ / 4 retardation layer is made of a nematic liquid crystal, and the light reflection layer is a metal light reflection layer.   The forgery prevention medium according to any one of claims 1 to 7, wherein the first light reflection region further includes a light absorption layer facing a back surface of the circularly polarized light reflection layer.   An anti-counterfeit label comprising the anti-counterfeit medium according to any one of claims 1 to 8, and an adhesive layer supported on a back surface thereof.   A printed matter comprising the anti-counterfeit medium according to any one of claims 1 to 8, and paper into which the anti-counterfeit medium is inserted. An anti-counterfeit medium according to any one of claims 1 to 8,
A base material that releasably supports the front surface of the anti-counterfeit medium,
A transfer foil comprising an adhesive layer supported on the back surface of the anti-counterfeit medium. A method of discriminating between an authentic product and a non-authentic product using a verification tool for an article whose authenticity is unknown.
The genuine product is an article that supports the forgery prevention medium according to any one of claims 1 to 8,
The verification tool includes a linearly polarizing film, a first surface that faces a part of one main surface of the linearly polarizing film, and a fast axis is at an angle of 45 ° with respect to a transmission axis of the linearly polarizing film. The second phase layer facing the λ / 4 retardation layer and another part of the main surface of the linearly polarizing film and having a fast axis orthogonal to the fast axis of the first λ / 4 retardation layer a λ / 4 retardation layer,
The article having an unknown authenticity and the verification tool face each other, and the first and second λ / 4 phase difference layers of the verification tool face the article having an unknown authenticity. In this state, in this state, the brightness when observing an article whose unknown whether or not it is authentic through the portion corresponding to the first λ / 4 retardation layer of the verification tool and the second If it does not include a region that is different from the brightness when observing an unknown article whether or not it is authentic through a portion corresponding to the λ / 4 retardation layer, the authentic or unknown Determining that the article is non-genuine;
The article of which the authenticity is unknown and the verification tool are overlapped with the linearly polarizing film of the verification tool so that the authenticity of the unknown article faces each other, and the verification is performed in this state. When an article of which the authenticity is unknown is observed through a tool and does not include a region where the brightness changes according to the direction of the transmission axis of the linearly polarizing film , A determination method characterized by including determining that a certain or unknown article is a non-genuine product.

Images