JP5828182B2 - Authenticating medium - Google Patents

Description

  The present invention is viewed from the front side and the back side in the field of valuable printed materials such as banknotes, passports, securities, identification cards, cards, and passports, which are security printed materials that require anti-counterfeiting effects. The present invention relates to a true / false discrimination medium in which an image that can be observed changes.

  With recent developments in digital devices such as scanners, printers, and color copiers, it has become possible to easily produce elaborate copies of precious printed matter. As one of anti-counterfeiting techniques for preventing such duplication and forgery, there is a technique using a cholesteric liquid crystal.

  Cholesteric liquid crystals have two characteristics resulting from their molecular structure. One is a structural color corresponding to the helical pitch in the molecular structure, and by changing the angle at which light is reflected, the helical pitch is changed in a pseudo manner, and the observed hue changes, so-called hue transition effect. It is the feature. When observed with transmitted light, it exhibits a complementary color of the reflected color. The other feature is that only polarized light having the same rotation direction as that of the helix in the molecular structure is reflected. This hue transition effect can be seen with the naked eye without using a tool, and the feature of reflecting only the same polarized light of one rotation can be confirmed only when observed through a circular polarizing filter. is there. As described above, cholesteric liquid crystals have been widely used in the field of anti-counterfeiting since two different effects can be used simultaneously.

  As a printed material using such a cholesteric liquid crystal material, a cholesteric liquid crystal part is provided in the transparent part of the base material, and it is easy to visually check the authenticity of a copied material that has been forged by copying with a color copying machine or a personal computer printer. An anti-counterfeit paper that can be used is disclosed (for example, see Patent Document 1).

  In addition, a colored layer is formed on the substrate, a right polarization reflecting layer that reflects right-rotated polarized light out of the light incident on the colored layer, and a left polarized light that reflects left-rotated polarized light among the incident light There has been disclosed a printed material on which an optical element having a polarization reflection layer is attached (see, for example, Patent Document 2 and Patent Document 3).

JP 2000-318399 A JP 2003-170649 A JP 2009-98454 A

  In any of the techniques described in Patent Document 1, Patent Document 2, and Patent Document 3, a circular polarizing filter is used as a discriminator when performing authenticity determination using circularly polarized light reflected by cholesteric liquid crystal provided in a printed material. It was necessary to check whether the image that can be used and observed changes. In other words, the determination method using the circular polarizing filter visualizes the characteristics of the molecular arrangement unique to the cholesteric liquid crystal in a visible form, so it can be said that it is extremely difficult to counterfeit and is an extremely accurate determination method. . However, this determination method has a problem in that it is necessary to prepare and check a dedicated circular polarization filter separately, and the number of users that can be determined is limited.

  The present invention aims to solve the above-described problems, and does not need to have a circularly polarizing filter for authenticity discrimination as in the prior art, and all users are viewed from the front side and from the back side. It is an object of the present invention to provide a true / false discriminating medium capable of easily observing a change in an image caused by viewing and discriminating the authenticity.

  The authenticity determination medium of the present invention has at least a first image and a second image on the front side of a transparent or translucent substrate having a function of transmitting either right-handed rotation or left-handed circularly polarized light. The first image is composed of cholesteric liquid crystal that reflects only circularly polarized light that is reversely rotated and circularly polarized light transmitted through the substrate, and the second image is reversely rotated from circularly polarized light that is transmitted through the substrate. It consists of a material that does not reflect only circularly polarized light. When the substrate is observed from the front side under reflected light, the substrate is observed from the back side under reflected light and the substrate is transmitted from the front and back sides. The image that can be observed is different depending on whether the image is observed under light.

  In addition, the authenticity determination medium of the present invention is characterized in that the first image and the second image have the same color when viewed from a predetermined angle under reflected light from the front side.

  Further, the authenticity determination medium of the present invention is characterized in that the second image is made of a cholesteric liquid crystal material that reflects circularly polarized light having the same rotation as the circularly polarized light that is transmitted through the substrate.

  In addition, the precious printed matter of the present invention is characterized in that it is laminated so as to cover a window opening provided on a part of a base material different from the base material constituting the authenticity discrimination medium.

  Authentic discrimination using the direction of rotation of the helix in the molecular arrangement of cholesteric liquid crystals, when the substrate is observed from the front side, and when the substrate is viewed from the back side without preparing a dedicated circular polarizing filter This can be done by checking the change in the image that occurs in By this method, everyone who has the authenticity determination medium can quickly and very easily determine authenticity.

  Further, the authenticity determination medium of the present invention is observed through the filter even when formed using the same material (cholesteric liquid crystal and filter) as compared with the type of authentication in which the conventional print image and filter are separated. The image (the image observed from the back side in the authenticity determination medium of the present invention) becomes a clearer image. This is a great advantage caused by disturbance light not entering between the print image and the filter because the filter and the print image are in close contact with each other.

  When observed under reflected light, the first image formed of the cholesteric liquid crystal exhibits a vivid structural color, and the hue transition effect that occurs when the observation angle is changed is extremely high, so that the authenticity discrimination effect is excellent.

  When observed under transmitted light, the structural color of the first image is lost, and the effect of changing to colorless and transparent occurs. Therefore, the true / false discrimination effect is excellent even under transmitted light.

  When the second image is formed with a cholesteric liquid crystal having the same rotation as the circularly polarized light transmitted through the substrate, the second image also has an effect of exhibiting a complementary color of the reflected color under transmitted light. .

It is explanatory drawing which shows the authenticity determination medium of this invention. (A) is an explanatory view of a print image, (b) is an explanatory view of a first image included in the authenticity determination medium, and (c) is an explanatory view of a second image included in the authenticity determination medium. . (A) is a figure which shows the state which observes a true / false discrimination medium, (b) is explanatory drawing of the image observed when a true / false discrimination medium is seen from the front side, (c) is true / false It is explanatory drawing of the image observed when a discrimination | determination medium is seen from the back side. (A) is explanatory drawing which shows the optical path of each circularly polarized light at the time of observing the authenticity determination medium of this invention from the front side under reflected light. (B) is explanatory drawing which shows the optical path of each circularly polarized light at the time of observing the authenticity determination medium of this invention from back side under reflected light. (A) is explanatory drawing which shows the optical path of each circularly polarized light at the time of observing the authenticity determination medium of this invention from the front side under transmitted light. (B) is explanatory drawing which shows the optical path of each circularly polarized light at the time of observing the authenticity determination medium of this invention from the back side under transmitted light. It is explanatory drawing of the valuable printed matter in which the authenticity discrimination medium is affixed. It is explanatory drawing which shows the authenticity determination medium of this invention. (A) is an explanatory diagram of a print image, (b) is a first image included in the authenticity determination medium, (c) is a second image included in the authenticity determination medium, and (d) FIG. 5 is an explanatory diagram of additional elements included in the authenticity determination medium. (A) is a figure which shows the state which observes a true / false discrimination medium, (b) is explanatory drawing of the image observed when a true / false discrimination medium is seen from the front side, (c) is true / false It is explanatory drawing of the image observed when a discrimination | determination medium is seen from the back side.

  An embodiment of the present invention will be described with reference to FIGS. However, the present invention is not limited to the embodiments described below, and includes various other embodiments within the scope of the technical idea described in the claims.

  FIG. 1 shows the authenticity determination medium (1) of the present invention. In the authenticity determination medium (1) of the present invention, a printed image (3) is formed on a substrate (2). The substrate (2) has a function of polarizing incident light into circularly polarized light (including elliptically polarized light), and is transparent or semi-transparent to transmit only one of right-handed and left-handed circularly polarized light. It is made of a transparent material. The light transmittance of the substrate (2) is preferably 30% or more. This is because if the transmittance of the base material (2) is smaller than 30%, it is difficult to observe the change in the image that occurs when viewed from the front side and when viewed from the back side. As an example of such a base material, at least a polarizing film and a retardation film (1/4 wavelength plate) are laminated to protect them in strength and prevent deterioration due to temperature and humidity. It is desirable to laminate a protective film having high transparency, low birefringence and excellent weather resistance. Examples of such a protective film include a triacetyl cellulose (TAC) film. The retardation film may have a configuration in which a plurality of retardation plates are laminated in order to broaden the bandwidth. However, the structure of the base material (2) is not limited to this, and any structure may be used as long as it exhibits the same function without taking the laminated structure described above. In the following description, the surface on which the printed image (3) is formed on the substrate (2) will be described as “front side”, and the opposite surface will be described as “back side”.

  FIG. 2 shows the configuration of the print image (3). The print image (3) shown in FIG. 2 (a) is composed of a first image (4a) shown in FIG. 2 (b) and a second image (4b) shown in FIG. 2 (c). In the present invention, the first image (4a) is formed by a cholesteric liquid crystal having a property of reflecting only polarized light having a reverse rotation to the polarized light transmitted through the substrate (2). For example, the substrate (2) When the first image (4a) transmits right-handed polarized light, the first image (4a) is formed of a cholesteric liquid crystal having a property of reflecting only the left-handed polarized light, and when the substrate (2) transmits left-handed polarized light, It is formed of a cholesteric liquid crystal having a property of reflecting only right-handed polarized light.

  A cholesteric liquid crystal is a structure in which long and narrow molecules are aligned in the same plane in a single plane, and the molecules are arranged in a spiral direction as they move in a direction perpendicular to the plane. It is a liquid crystal and has the property of selectively reflecting light having the same wavelength as the helical pitch and the property of selectively reflecting circularly polarized light (including elliptically polarized light) in the same rotational direction as the rotational direction of the spiral. . Furthermore, regarding the property of reflecting light or polarized light of cholesteric liquid crystals, the hue of the reflected color can be controlled by controlling the pitch of the helix, and the effect of changing not only the brightness but also the hue at the same time when the light is reflected It has a so-called hue transition effect. In addition, when the liquid crystal is tilted and observed, the helical pitch is artificially shortened, and the hue to be observed changes when the wavelength of the interfering light is shifted to the short wavelength side.

  Further, it is known that cholesteric liquid crystals exhibit a complementary color of structural colors that have been viewed under reflected light under transmitted light. More specifically, the light transmitted through the cholesteric liquid crystal is light of the complementary color of the structural color and circularly polarized light opposite to the rotational direction of the cholesteric liquid crystal out of the light in the same rotational direction as the light reflected by the cholesteric liquid crystal. . At this time, the circularly polarized light opposite to the rotation direction of the cholesteric liquid crystal includes all light components in the visible wavelength range, and thus does not affect the visibility of the color of the light transmitted through the cholesteric liquid crystal. The complementary color of the structural color is observed as transmitted light.

  The circularly polarized light having a certain rotational direction that is reflected or transmitted by the cholesteric liquid crystal described above is transmitted through a filter with the same rotational direction, while the reversely rotated filter with the same rotational direction cannot transmit. This difference in the direction of rotation of circularly polarized light has the characteristic that it cannot be observed unless it has a dedicated filter.

  In the present invention, by utilizing the characteristics of the cholesteric liquid crystal, the base material is transmitted through in order to obtain an effect of changing the observable image when the authenticity determination medium (1) is viewed from the front side and when viewed from the back side. The polarized light to be reflected and the polarized light reflected by the first image (4a) are necessarily configured in the opposite relationship. In addition, the detailed description of the effect observed when the image changes when observed from the front and back will be described later.

  In the present invention, the cholesteric liquid crystal forming the first image (4a) may be an ink containing a pigment obtained by solidifying and pulverizing a cholesteric liquid crystal, or the cholesteric liquid crystal itself in a fluid state is directly used. You may print and form as ink. The printing method is not particularly limited, but a printing method capable of obtaining a constant ink transfer amount, such as flexographic printing, gravure printing, screen printing, and intaglio printing, is suitable.

  On the other hand, the second image (4b) shown in FIG. 2 (c) may be formed of any material as long as it is not a cholesteric liquid crystal forming the first image (4a). A material having an object color typified by normal coloring ink such as red, blue, or yellow may be used, or a transparent material having no object color such as transparent varnish or medium may be used. Further, although there is no object color like iris pearl ink, there is no problem even if a special material exhibiting a specific structural color is used. The second image (4b) may be printed by a known printing method such as offset printing, gravure printing, inkjet printing or the like.

  In addition, when the second image (4b) is formed using the cholesteric liquid crystal forming the first image (4a), the printed matter which is the maximum effect of the present invention is viewed from the front side, An effect of changing the image that can be observed when viewed from the back side can be realized. However, in this case, the image that was seen when viewed from the front side is limited to the disappearing effect of disappearing when viewed from the back side, which is not desirable.

  Hereinafter, a specific material for forming the second image (4b) will be described, and together with this, an image observed when the authenticity determination medium (1) of the present invention is observed with reflected light and transmitted light. Will be described. First, as a first example, the base material (2) has the property of transmitting only the right-handed polarized light, and the first image (4a) has the property that the structural color is red and the left-handed polarized light is reflected. The authenticity determination medium (1) formed of the cholesteric liquid crystal having the second image (4b) with light green ordinary coloring ink will be described.

  FIG. 3A is a diagram showing a state of observing the authenticity determination medium (1) of the present invention, and the viewpoint (5a) is the position of the viewpoint when observing the authenticity determination medium (1) from the front side. The viewpoint (5b) indicates the position of the viewpoint when observing from the back side. In FIG. 3A, the reflected light when the authenticity determination medium (1) is observed is indicated by a solid line arrow, and the transmitted light is indicated by a broken line arrow.

  At this time, when the authenticity determination medium (1) is observed from the front-side viewpoint (5a) under reflected light, the entire printed image (3) is observed, and the first image (4a) is red, The second image (4b) is observed in pale green (FIG. 3 (b)). Further, when the first image (4a) is tilted while being regularly reflected, an effect of changing the structural color to a hue having a shorter wavelength occurs as the tilt angle increases. The authenticity can also be determined by confirming this excellent hue transition effect that occurs only in the first image (4a).

  On the other hand, when the authenticity determination medium (1) is observed with reflected light from the back side viewpoint (5b), as shown in FIG. 3C, the first image (4a) of the print image (3) is displayed. ) Disappear and only the second image (4b) is observed in light green.

  When the area where the first image (4a) of the authenticity determination medium (1) is formed under the reflected light is observed from the front and back, the principle that the image changes and the first image (4a) has a hue transition effect. The resulting principle will be described with reference to FIG. FIG. 4A shows the optical paths of right-handed polarized light (6R) and left-handed polarized light (6L) when the authenticity determination medium (1) is observed from the front-side viewpoint (5a) under reflected light. FIG. 4B shows optical paths of right-handed polarized light (6R) and left-handed polarized light (6L) when the authenticity determination medium (1) is observed from the back-side viewpoint (5b) under reflected light. 4A and 4B, the incident light is divided into two components of right-handed polarized light (6R) and left-handed polarized light (6L) in advance for the sake of clarity. It is assumed that the light is incident on the discrimination medium (1). In addition, it is assumed that the polarized light in the figure is incident on the authenticity determination medium (1) from an oblique direction, and the observer observes the authenticity determination medium (1) from an oblique direction. It is not limited to the observation angle or the observation angle, and the same applies to the case where the light is vertically incident as shown in FIG. 3 and the observer observes the authenticity determination medium (1).

First, the optical path of each polarization when the region where the first image (4a) of the authenticity determination medium (1) is formed under the reflected light is observed from the front side, and the effects caused thereby are shown in FIG. Will be described. Of the two incident polarized light, the right-handed polarized light (6R) passes through the first image (4a) and the base material (2) as it is, and thus does not reach the observer's viewpoint (5a). Of one left rotation of the polarization (6L), red light falling structural color of the cholesteric liquid crystal (6L _R) is reflected by the first image (4a), reaching the observer's viewpoint (5a). At this time, the complementary color (6L _GB ) of the structural color that has not been reflected among the left-rotated polarized light (6L) is absorbed by the base material (2). Therefore, the light reaching the observer's viewpoint (5a) is only the red component (6L _R ) of the left-handed polarized light (6L).

  Next, the optical path of each polarization when the region where the first image (4a) of the authenticity determination medium (1) is formed under the reflected light is observed from the back side, and the effects caused thereby are shown in FIG. ). Of the two incident polarized light, the right-handed polarized light (6R) passes through the first image (4a) and the base material (2) as it is, and does not reach the observer's viewpoint (5b). One counterclockwise polarized light (6L) is absorbed by the base material (2) and is not reflected by the observer's viewpoint (5b). Normally, when a pattern printed on the front side of a translucent or transparent substrate is observed from the back side, the pattern on the front side can be seen through due to the transparency of the substrate, but the configuration of the present invention is used. In some cases, according to the principle described above, the light reaching the observer's viewpoint (5b) does not include the light reflected from the first image (4a), and the first viewpoint (5b) from the observer's viewpoint (5b). The image (4a) appears to have disappeared completely. In addition, since the 2nd image (4b) is formed with normal coloring ink, it is observed as it is with the permeability | transmittance of a base material (2).

  The above is the observation principle of the image when observed from the front and back under reflected light. In the authenticity determination medium (1) of the present invention, the first image (4a) that disappears and the second image that does not disappear By combining (4b), the effect of changing the image observed when observed from the front and back is produced.

  In the prior art, unless the base material (2) is colored black or a dark color close thereto, it is difficult to keep the hue transition effect that occurs when the structural color of the cholesteric liquid crystal appears vividly and tilted. Has been considered. This is because, when the substrate has a white color or a specific hue, the cholesteric liquid crystal reflects only the structural color, while the substrate (2) reflects the complementary color of the structural color transmitted through the cholesteric liquid crystal. This is because the structural color reflected by and the complementary color of the structural color reflected by the base material (2) are combined, and the reflected light returns to white light. In order to obtain a high hue transition effect, it is not sufficient for the substrate to absorb only the color of a specific hue, but it must absorb or transmit all the complementary colors of the structural color of the cholesteric liquid crystal that changes with the angle. I must. Therefore, cholesteric liquid crystals are usually printed on a black substrate.

  However, in the true / false discrimination medium (1) of the present invention, the base material absorbs or transmits all the complementary colors of the structural color transmitted through the cholesteric liquid crystal, and is a clear material having light transmission properties. For this reason, the complementary color component is not reflected and reaches the observer. Therefore, the first image (4a) of the authenticity determination medium (1) exhibits a very clear structural color, and an excellent hue transition effect can be obtained even when the inclination is changed. This is one of the excellent features of the present invention.

  The above is the principle of the image change that occurs when the authenticity determination medium (1) of the present invention is observed from the front and back under reflected light, and the first image (4a) exhibits a clear structural color and is excellent. This is the principle of the hue transition effect.

  Next, the effect of the authenticity determination medium (1) of the present invention in observation under transmitted light and the principle of the effect will be described. It is known that under transmitted light, cholesteric liquid crystals exhibit a complementary color of the structural color viewed under reflected light. However, in the authenticity determination medium (1) of the present invention, the first image (4a) should be visible under the transmitted light when observed under the transmitted light from the viewpoint (5a) and the viewpoint (5b). It has the effect of changing to colorless and transparent without exhibiting a complementary color. This effect and the principle on which this effect occurs will be described below with reference to FIG.

  The effect of changing the first image (4a) to colorless and transparent when the authenticity determination medium (1) is observed under transmitted light is as if the first image (4a) has disappeared at first glance. Therefore, it is easy to be confused with the image disappearance effect that occurs when the authenticity determination medium (1) is observed under the reflected light from the back side viewpoint (5b). In reality, however, the effects and principles are very different. FIG. 5 (a) shows the optical paths of right-handed polarized light and left-handed polarized light when the authenticity determination medium (1) is observed under transmission from the front-side viewpoint (5a), and FIG. The optical paths of right-handed polarized light and left-handed polarized light when the false discrimination medium (1) is observed under transmission from the back viewpoint (5b) are shown. In the description of FIG. 5, it is assumed that the base material (2) transmits right-handed polarized light and the first image (4a) has a characteristic of reflecting left-handed polarized light. Further, in order to clarify the explanation in FIG. 5, it is assumed that the incident light is divided into two components of right-handed polarized light and left-handed polarized light and is incident on the authenticity discrimination medium (1). .

As shown in FIG. 5 (a), when the authenticity determination medium (1) is observed with the transmitted light from the front-side viewpoint (5a), the right-handed polarized light (6R) is the same as the base material (2) and the first one. After reaching the image (4a), the observer is reached. On the other hand, since the left-handed polarized light (6L) is absorbed by the substrate (2), the left-handed polarized light (6L) does not reach the observer's viewpoint (5a). Therefore, in the example shown in FIG. 5A, the light reaching the observer's viewpoint (5a) is only the right-handed polarized light (6R). Although this light does not interfere with the helical structure of the cholesteric liquid crystal forming the first image (4a) and does not exhibit a complementary color to the structural color, the light passes through the first image (4a). Therefore, the attenuation of light occurs under the influence of the resin or liquid crystal material forming the first image (4a), and the first image (4a) is visually recognized by the observer by the intensity of light. . In addition, even when the authenticity determination medium (1) is observed with the transmitted light shown in FIG. 5B from the back side viewpoint (5b), the left-handed polarized light (6L _GB ) is absorbed and the right-handed polarized light (6L _GB ) 6R) is affected by the resin or liquid crystal material that forms the first image (4a), and light attenuation occurs to reach the observer's viewpoint (5b).

  From the above, in observation under transmitted light, the first image (4a) does not completely disappear as in the case of observation from the back side under reflected light, but the first image (4a). Only the color of the image is lost, and the shape and contour of the image can be visually recognized by the intensity of transmitted light. Thus, the effect that a cholesteric liquid crystal having a specific structural color changes to colorless and transparent under transmitted light is extremely unique, and is effective as a true / false discrimination method using transmitted light, and is an excellent feature of the present invention. It can be said that it is one of.

  Subsequently, a second example will be described. The second example is different from the first example in that the second image (4b) is colored with the same color as the first image (4a) when observed from a predetermined observation angle under reflected light. The difference is that it is formed with ink. In the present invention, in observation under reflected light, the “specific observation angle” when the second image (4b) is observed in the same color as the first image (4a) is the base material (2 ) With respect to the vertical direction.

  At this time, when the authenticity determination medium (1) is observed from the front-side viewpoint (5a) under reflected light, the entire printed image (3) is all observed in the same red color. On the other hand, when the authenticity determination medium (1) is observed with reflected light from the back-side viewpoint (5b), the first image (3) of the print image (3) is similar to the observation principle of the first example. 4a) disappears and only the second image (4b) is observed in red. In this case, since the print image (3) is composed of a single color, the observer simply observes the authenticity determination medium (1) from the front viewpoint (5a) at a specific angle under reflected light. Although it is difficult to expect that the image (4a) and the second image (4b) are formed of different materials, the first image (4a) and the second image (4b) are observed when reflected under reflected light from the back side viewpoint (5b). The effect that only the image (4a) disappears appears, and a stronger impact can be given to the observer. Similarly to the above-described example, when the first image (4a) is tilted while being regularly reflected, a hue transition effect occurs as the tilt angle increases, so the hue change is confirmed. In other words, true / false discrimination is possible.

  Further, the second image (4b) may be formed of cholesteric liquid crystal having a property of reflecting the cholesteric liquid crystal forming the first image (4a) and reversely polarized light. In this case, printing methods such as flexographic printing, gravure printing, screen printing, and intaglio printing are suitable as in the case of forming the first image (4a). Taking this as a third example, the base material (2) has the property of transmitting only the right-handed polarized light, and the first image (4a) has the property that the structural color is red and the left-handed polarized light is reflected. The second image (4b) is formed of a cholesteric liquid crystal having a red structure color and reflecting the right-handed polarized light in the reverse direction to the first image (4a). The authenticity determination medium (1) will be described.

  At this time, when the authenticity determination medium (1) is observed with reflected light from the front-side viewpoint (5a), the entire printed image (3) is observed in red. On the other hand, when the authenticity determination medium (1) is observed with reflected light from the back side viewpoint (5b), the first image (4a) of the print image (3) disappears and the second image ( Only 4b) is observed in red. The principle that the second image (4b) is observed is that the right-handed polarized light (6R) transmitted through the base material (2) is reflected by the second image (4b), and the second image (4b) is reflected. This is because the light reflected by) passes through the base material (2) again and reaches the observer's viewpoint (5b). In the two examples described so far, when the authenticity determination medium (1) is tilted while being regularly reflected, only the first image (4a) has undergone a hue change. In this example, the second image is changed. In (4b), the same hue change as in the first image (4a) occurs. A pair of cholesteric liquid crystals with the same spiral pitch of right and left rotations, when viewed from any angle under reflected light, can be completely color-matched. Thus, it is impossible to predict that the first image (4a) and the second image (4b) are formed of different materials. In this example in which the first image (4a) and the second image (4b) are formed of cholesteric liquid crystals having the same structural color that differ only in the rotation direction, the first image (4a) and the second image (4b) Since the image (4b) is observed with the same color and the hue change when tilted is the same, the first image (4a) and the second image (4b) are formed of different materials. This is difficult to detect in advance, and therefore, when viewed from the back side, the first image (4a) disappears and the impact observed is very large. Therefore, it can be said that this example is the most excellent form of the present invention.

  In addition, when the second image (4b) is observed under transmitted light, the authenticity determination medium (1) formed of cholesteric liquid crystal that reflects the same circularly polarized light as the substrate (2) transmits. When viewed from either the front-side viewpoint (5a) or the back-side viewpoint (5b), the complementary color of the structural color under the reflected light is visually recognized. In addition, the hue gradually changes when the observation is performed while tilting from the state in which light enters vertically under transmitted light.

  As described above, the authenticity determination medium (1) of the present invention authenticates the vivid hue transition effect exhibited by the first image (4a) when observed at different angles while being regularly reflected under reflected light. The first effect to authenticate, the second effect to authenticate the effect that the first image (4a) changes to colorless and transparent under transmitted light, the front side viewpoint (5a), and the back side viewpoint ( 5b) has at least a third effect of changing the image that can be observed when viewed from the viewpoint of 5b), and any of the three effects can be confirmed with the naked eye without the need for a tool, so that the authenticity discrimination is excellent.

  The authenticity determination medium (1) of the present invention can be used not only as a single unit but also as a part of valuable printed matter such as banknotes, passports, securities, identification cards, cards, pass tickets, gift certificates, etc. Can be laminated and used together. The configuration of such a precious printed matter will be described with reference to FIG.

  FIG. 6 shows a precious printed matter (8) in the form of a gift certificate as an example, FIG. 6 (a) is a plan view thereof, and FIG. 6 (b) is taken along the line XX ′ of FIG. 6 (a). A cross-sectional view is shown. Although the face print (11) is provided in the valuable printed matter (8) shown in FIG. 6 (a), a configuration in which other patterns and designs are formed may be used. In addition, as a countermeasure against forgery, a configuration in which threads, holograms, ultraviolet infrared light-emitting ink, copy prevention image lines, or the like is applied may be used.

  As the base material (9) constituting the valuable printed matter (8), paper, film, or plastic is used. In addition, the base material (21) constituting the valuable printed matter may be transparent or opaque. The window opening part (10) from which the base material (9) has been removed in advance is formed on a part of the base material (9) constituting such a valuable printed matter. In this invention, a window opening part (10) is a hole which penetrates the base material (9) which comprises valuable printed matter, and the range of the window opening part (10) is a broken line in Fig.6 (a). It is shown. As shown in FIG. 6A, the range in which the window opening (10) is formed needs to be larger than the range of the print image (3) formed on the authenticity determination medium (1). As a method for forming the window opening portion (10), die cutting or laser processing can be used.

  And as shown in FIG.6 (b), an integral valuable printed matter (8) is formed by laminating | stacking the authenticity discrimination | determination medium (1) so that a window opening part (10) may be covered. At this time, the print image (3) formed on the authenticity determination medium (1) is laminated so as to be positioned within the range of the window opening (10). The means for laminating the authenticity discriminating medium (1) can be adhered directly to the base material (9) constituting the precious printed matter with an adhesive or adhered so as to cover the authenticity discriminating medium (1) with a laminate film. it can.

  The precious printed matter (8) produced in this way can be observed on the front side and the back side of the authenticity discrimination medium (1) by providing the window opening (10), and the effect of changing the image is obtained. It is done.

  Further, when a transparent film or plastic is used for the base material (9) constituting the valuable printed matter (8), the authenticity determination medium (1) may be directly attached.

  Hereinafter, an example of the authenticity determination medium that is specifically produced according to the above-described mode for carrying out the invention will be described in detail, but the present invention is not limited to this example.

Example 1
In the first embodiment, the authenticity determination medium (1) is formed of a base material (2) that transmits circularly polarized light rotated clockwise, the first image is formed of cholesteric liquid crystal rotated counterclockwise, and the second image is formed of the first image. It is an example formed with normal coloring ink of the same color as the image.

  The drawings will be described with reference to FIGS. 1 to 3 used in the embodiment. In Example 1, as the base material (2), a circularly polarizing filter having a property of transmitting right-handed polarized light was used. Although the substrate (2) is slightly blackish, it is a transparent material having sufficient light transmittance, and cannot be judged to be a filter at first glance. A first image (4a) shown in FIG. 2B was formed on the base material (2) by a flexographic printing method using a UV drying method, using a left-rotating cholesteric liquid crystal exhibiting a green structural color. Moreover, using the light green flexo ink of the mixing | blending shown in Table 1, the 2nd image (4b) of the same color as the 1st image (4a) shown in FIG.2 (c) is changed to the 1st image (4a). ), The printed image (3) was formed by the flexographic printing method to obtain the authenticity determination medium (1).

  The effect of Example 1 is demonstrated using FIG. When the authenticity determination medium (1) was observed from the front-side viewpoint (5a) under reflected light, a green printed image (3) was observed as shown in FIG. 3 (b). In addition, when the authenticity determination medium (1) is regularly reflected and gradually tilted, only the first image (4a) has a hue transition effect in which the hue gradually changes from green to blue. When the authenticity determination medium (1) was observed from the back side viewpoint (5b) under reflected light, only the second image (4b) was observed in green as shown in FIG. 3 (c). In addition, when the authenticity determination medium (1) was observed under transmitted light, it was confirmed that the structural color was lost from the first image (4a) and the color changed to colorless and transparent. As described above, the hue transition effect of the first image (4a) and the effect that the image viewed from the front side and the image viewed from the back side are different can be confirmed.

(Example 2)
In the second embodiment, the authenticity determination medium (1) is formed of a base material (2) that transmits circularly polarized light rotated to the right, the first image is rotated with a cholesteric liquid crystal rotated left, and the second image is rotated with a clockwise rotation. It is an example formed with cholesteric liquid crystal.

  The drawings will be described with reference to FIGS. 1 to 3 used in the embodiment. In Example 2, as the base material (2), a circularly polarizing filter having a property of transmitting right-handed polarized light as in Example 1 was used. A first image (4a) shown in FIG. 2B was formed on the base material (2) by a flexographic printing method using a UV drying method, using a counterclockwise cholesteric liquid crystal having a structural color of red. Further, the first image shown in FIG. 2 (c) is formed using a right-rotating cholesteric liquid crystal having a structural color of red and paired with a left-rotating cholesteric liquid crystal that forms the first image (4a). The second image (4b) of the same color as 4a) is printed by the flexographic printing method in the same manner as the first image (4a) to form a print image (3), which is used as the authenticity determination medium (1). .

  The effect of the embodiment will be described with reference to FIG. When the authenticity determination medium (1) was observed from the front-side viewpoint (5a) under reflected light, a red printed image (3) was observed as shown in FIG. 3 (b). In addition, when the authenticity determination medium (1) is regularly reflected and tilted gradually, both the first image (4a) and the second image (4b) gradually change from red to yellow, green, and blue. The hue transition effect of changing hue is shown in Fig.2. Moreover, when the authenticity determination medium (1) was observed from the back side viewpoint (5b) under reflected light, only the second image (4b) was observed in red as shown in FIG. In addition, when the authenticity determination medium (1) is observed under transmitted light, the structural color is lost from the first image (4a) and changes to colorless and transparent, while the second image (4b) It was confirmed that the color changed to blue-green (cyan), which is a complementary color of red. As described above, it was possible to confirm the hue transition effect of the first image (4a) and the second image (4b), and the effect that the image viewed from the front side and the image viewed from the back side are different.

(Example 3)
In the third embodiment, the authenticity determination medium (1 ′) is formed of a base material (2 ′) that transmits left-polarized polarized light, the first image is rotated clockwise, and the second image is rotated counterclockwise. This is an example in which the third image is formed with ordinary colored ink.

  The drawings will be described with reference to FIGS. In Example 3, as the base material (2 ′), a circular polarizing filter having a property of transmitting left-handed polarized light was used. The first image (4a ′) shown in FIG. 8B was formed by the flexographic printing method of the UV drying method using the right-rotating cholesteric liquid crystal with the structural color of green on the base material (2 ′). . Further, by using a counterclockwise cholesteric liquid crystal with a structural color of green, a second image (4b ′) having the same color as the first image (4a ′) shown in FIG. In the same manner as in 4a ′), the flexographic printing method was used. Finally, a third image (4c ′) showing the petals of cherry blossoms shown in FIG. 8 (d) is printed using a normal light red flexo ink having the composition shown in Table 2 to obtain a printed image (3 ′). Was used as the authenticity discrimination medium (1 ′).

  The first image (4a ′) is a pattern in which the letters “NP” of the mirror-inverted alphabet are expressed in negative, while the second image (4b ′) is the alphabet “NP” of the mirror-inverted alphabet. Is a pattern that expresses the characters "" in positive, and when the first image (4a ') and the second image (4b') are combined, it becomes a mere solid and the mirror-inverted "NP" characters are concealed It has become.

  The effect of Example 3 is demonstrated using FIG. When the authenticity determination medium (1 ′) is observed from the front-side viewpoint (5a ′) under reflected light, as shown in FIG. 9B, the printed image (3 ′) is on a green solid pattern. Red cherry petals were observed. Further, when the authenticity determination medium (1 ') is regularly reflected and tilted gradually, since both the first image (4a') and the second image (4b ') are cholesteric liquid crystals, the background The whole showed a hue transition effect in which the hue gradually changed from green to blue. Further, when the authenticity determination medium (1 ′) is observed under reflected light from the back side viewpoint (5b ′), the second image (4b ′) is observed in green as shown in FIG. 9C. The cherry blossom petals, which are the third image (4c '), were observed with a slightly weak red color on the back. In addition, when the authenticity determination medium (1 ′) is observed under transmitted light, the structural color is lost from the first image (4a ′) and changes to colorless and transparent. It was confirmed that 4b ′) changed to red, which is a complementary color of green. As described above, it was confirmed that the hue transition effect of the first image (4a ′) and the second image (4b ′) was different from the image viewed from the front side and the image viewed from the back side. In Example 3, the first image (4a ′) is completely hidden in the printed image (3 ′) when observed from the front side under reflected light. The impact when the appearance of the second image (4b ′) is confirmed is great.

1, 1 'authenticity determination medium 2, 2' base material 3, 3 'printed image 4a, 4a' first image 4b, 4b 'second image 4c' third image 5a, 5b, 5a ', 5b ′ Observer's viewpoint 6L Left rotation polarization 6R Right rotation polarization
6L _R left-handed polarized structural color (R component)
Complementary color (GB component) of 6L _GB counterclockwise polarized structural color
8 Precious printed matter 9 Base material constituting valuable printed matter 10 Window opening 11

Claims (4)

Provided with a printed image having at least a first image and a second image on the front side of a transparent or translucent substrate having a function of transmitting either right-rotation or left-rotation circularly polarized light, The image consists of a cholesteric liquid crystal that reflects only circularly polarized light that is transmitted through the substrate and reversely rotated circularly polarized light, and the second image reflects only circularly polarized light that is transmitted through the substrate and reversely rotated circularly polarized light. Made of materials that do not have the properties to
When the printed image is observed from the front side under reflected light, the first image and the second image can be observed. When the printed image is observed from the back side under reflected light, the first image is completely When the printed image is observed from the front side or the back side under transmitted light, the first image loses the structural color of the first image and is colorless. An authenticity determination medium characterized by being transparent and capable of observing the contour of the first image by the intensity of transmitted light .

  The authenticity determination medium according to claim 1, wherein the first image and the second image have the same color when viewed from a predetermined angle under reflected light from the front side.   The authenticity determination medium according to claim 2, wherein the second image is made of a cholesteric liquid crystal material that reflects circularly polarized light having the same rotation as the circularly polarized light that is transmitted through the base material.   The authenticity determination medium according to any one of claims 1 to 3 is laminated so as to cover a window opening provided on a part of a base material different from the base material constituting the authenticity determination medium. Precious printed matter characterized by comprising.

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