JP5231163B2 - Identification media and articles - Google Patents

Description

  The present invention relates to an identification medium for identifying authenticity (authenticity) of various products and the like, and more particularly, to an identification medium that can be independently identified in addition to authenticating by a tool and an article including the identification medium. .

  As a method for preventing forgery of passports, various cards, certificates, and various products, a technique for applying special ink to the surface of the object and a technique for attaching a hologram are known. For example, Patent Document 1 discloses a forgery prevention technique in which a cholesteric liquid crystal is combined with a hologram. According to this technique, authenticity is determined by combining a hologram and a cholesteric liquid crystal and observing the reflected light through left and right circularly polarizing filters. Specifically, authenticity is determined using a phenomenon that when it can be seen with the right circular polarizing filter, it cannot be seen with the left circular polarizing filter.

Table 00/013065

  However, in the above-described technique, the change of the hologram due to the inherent characteristics of the cholesteric liquid crystal cannot be confirmed unless a tool such as a circular polarizing filter is used. Further, in the background of increasing forgery technology, an identification medium using cholesteric liquid crystal that is more difficult to counterfeit and has high identification property is required.

  In view of the above, an object of the present invention is to provide an identification medium with improved discrimination and an article provided with the identification medium.

The invention according to claim 1 is an identification medium that performs identification by observation from one side and observation from the other side, and includes a cholesteric liquid crystal layer that is formed with a hologram and reflects clockwise or counterclockwise circularly polarized light, and An identification layer that is laminated on the cholesteric liquid crystal layer and has a polarizing layer that transmits specific polarized light; and a light-transmitting fixing layer for fixing the identification layer to a light-transmitting object; The polarizing layer is laminated on the cholesteric liquid crystal layer, and changes the linearly polarized light into clockwise or counterclockwise circularly polarized light, or changes the clockwise or counterclockwise circularly polarized light into linearly polarized light, / 4 is laminated wave plate layer, and a linearly polarizing plate layer which transmits a linearly polarized light, prior to when the identification layer is visually the identification layer from the cholesteric liquid crystal layer side in the laminated direction And appearance of the hologram, the hologram of the appearance and differ identification medium characterized in the case of visually the identification layer from the polarizing layer side.

According to the first aspect of the present invention, when the identification medium is viewed through a tool for determining authenticity such as a filter that selectively transmits clockwise circularly polarized light and blocks counterclockwise circularly polarized light and linearly polarized light. However, authenticity determination can be performed, and authenticity determination can be performed even when visually observed without using a tool. In addition, since the number of methods for performing authenticity determination increases, it is possible to improve discrimination and make forgery difficult. The specific polarization refers to any one of right-handed circularly polarized light, left-handed circularly polarized light, and linearly polarized light. In addition, according to the first aspect of the present invention, when viewed from the polarizing layer side, the reflected light from the cholesteric liquid crystal layer is not visually recognized, and authenticity determination can be performed without using a tool. , Can enhance discrimination. In addition, according to the first aspect of the present invention, it is possible to easily determine the authenticity by transmitting light, and it is possible to improve the distinguishability. Here, the light transmissive property means a property of transmitting visible light used for discrimination.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the polarizing layer absorbs or reflects the same circularly polarized light as the circularly polarized light reflected by the cholesteric liquid crystal layer. According to the second aspect of the present invention, when viewed from the polarizing layer side, the reflected light from the cholesteric liquid crystal layer is not visually recognized, and authenticity determination can be performed without using a tool. Can increase the sex.

The invention described in claim 3 is an article provided with a light-transmitting object and the identification medium described in claim 1 or 2 . According to the invention described in claim 3 , it is possible to provide an authentic and highly discriminating article.

  According to the present invention, in addition to authenticity determination by a tool, it is possible to perform independent determination, and it is possible to manufacture an identification medium with improved identification and an article including the identification medium.

(1) First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an identification medium and an object. FIG. 2 is a conceptual diagram conceptually showing the structure of the cholesteric liquid crystal layer. FIG. 3 is a cross-sectional view showing a case where the identification medium is visually recognized. FIG. 4 is a diagram illustrating a case where the identification medium is viewed from the surface via the right circular polarization filter. FIG. 5 is a diagram illustrating a case where the identification medium is viewed from the surface via the left circular polarization filter. FIG. 6 is a diagram illustrating a case where the identification medium is viewed from the back side by visual observation. FIG. 7 is a diagram illustrating an object having a part having light transparency. In addition, the code | symbol E of FIG. 3 is a human eye to visually recognize.

(About cholesteric liquid crystal)
First, the cholesteric liquid crystal will be briefly described. The cholesteric liquid crystal layer has a layered structure as shown in FIG. When attention is paid to one layer, the molecular long axes of the liquid crystal molecules are aligned in the layer and are aligned parallel to the plane of the layer. The orientation direction is slightly shifted in the adjacent layers, and as a whole, the layers are stacked while the orientation rotates in a three-dimensional spiral shape.

  In this structure, considering the direction perpendicular to the layers, the distance from the molecular major axis rotating 360 ° to returning to the original is assumed to be a pitch P, and the average refractive index in each layer is n. In this case, the cholesteric liquid crystal layer exhibits a property of selectively reflecting circularly polarized light having a center wavelength λs that satisfies λs = n × P. That is, when white light is incident on the cholesteric liquid crystal layer, clockwise or counterclockwise circularly polarized light having a specific wavelength as a center wavelength is selectively reflected. In this case, the circularly polarized light having the same turning direction as that of the reflected circularly polarized light but having a wavelength that is not λs, the circularly polarized light in the reverse direction of the reflected circularly polarized light, and the linearly polarized light component are transmitted through the cholesteric liquid crystal layer.

  The turning direction (rotation direction) of the reflected circularly polarized light can be determined by selecting the spiral direction of the cholesteric liquid crystal layer. That is, as viewed from the incident direction of light, draw a spiral in the direction of the right-hand screw and the molecular long axis in each layer is oriented, or draw a spiral in the direction of the left-hand screw and the molecular long axis in each layer is oriented, By selecting, the turning direction (rotation direction) of the reflected circularly polarized light can be determined.

  The cholesteric liquid crystal layer exhibits a phenomenon called color shift. Hereinafter, the principle of color shift will be described. When light is incident on a light-transmitting multilayer thin film having a different refractive index between adjacent layers, the light is reflected at each interface of the multilayer structure. This reflection is caused by the difference in refractive index between the light-transmitting layers adjacent in the vertical direction. When the interface of one layer is seen, what is reflected is a part of the incident light, and most of the incident light is transmitted. That is, incident light that has entered the interfaces stacked in multiple layers is reflected little by little at each interface. Since the reflected light generated at each interface is basically reflected in the same direction, they cause interference due to the optical path difference.

  The more the incident light is incident from a direction closer to the plane, the smaller the optical path difference. Therefore, light of shorter wavelengths interferes and strengthens each other. From this principle, when the viewing angle is increased, the reflected light with shorter wavelengths interfere with each other and strengthen each other. As a result, when the multi-layer thin film is viewed under white light, the multi-layer thin film that appears to have a predetermined color at a viewing angle of 0 ° gradually becomes a bluish color as the viewing angle is increased. The phenomenon of changing is observed. This phenomenon is called color shift. The viewing angle is defined as an angle formed between a perpendicular to the layer and the line of sight.

(Configuration of identification medium and article provided with identification medium)
Next, the configuration of the identification medium 1 and the article including the identification medium 1 will be described with reference to the drawings. As shown in FIG. 1, the identification medium 1 is attached to an object 2 that also functions as a support. In this example, the article is a tag made of a plate-like transparent resin. The identification medium 1 includes an identification layer 10 and an adhesive layer 500 that is an example of a fixed layer. The identification medium 1 is a medium for determining the authenticity of the object 2 to which the identification medium 1 is attached. The entire object 2 is light transmissive. That is, the entire object 2 is transparent.

  As shown in FIGS. 1 and 3, the separate layer 10 is formed by laminating a surface protective layer 100, a cholesteric liquid crystal layer 200, an adhesive layer 300, and a polarizing layer 400 in order from the object 2. Yes. The identification layer 10 is manufactured by laminating a cholesteric liquid crystal layer 200, an adhesive layer 300, and a polarizing layer 400 in this order on the surface protective layer 100.

  The surface protective layer 100 is formed by forming a light-transmitting TAC (isotropic triacetyl cellulose) having a predetermined thickness into a film shape. The surface protective layer 100 is made of an isotropic refractive index so as not to disturb the circular polarization state of transmitted light. Polycarbonate, polystyrene, or the like can be used as a light-transmitting material that satisfies this condition.

  The cholesteric liquid crystal layer 200 is laminated adjacent to the surface protective layer 100. The cholesteric liquid crystal layer 200 selectively reflects specific clockwise or counterclockwise circularly polarized light and transmits other polarized light such as linearly polarized light. In the following description, it is assumed that the cholesteric liquid crystal layer 200 reflects clockwise circularly polarized light having a specific wavelength (for example, green).

  The cholesteric liquid crystal layer 200 is provided with a hologram forming part 210. The hologram forming part 210 is provided on the polarizing layer 400 side of the cholesteric liquid crystal layer 200. The hologram forming unit 210 is formed by pressing a mold for forming a hologram on the cholesteric liquid crystal layer 200 to form an embossed pattern or unevenness. The hologram forming unit 210 is not limited to being provided on the polarizing layer 400 side of the cholesteric liquid crystal layer 200, but may be provided on the surface protective layer 100 side of the cholesteric liquid crystal layer 200.

  The adhesive layer 300 is laminated adjacent to the cholesteric liquid crystal layer 200. The adhesive layer 300 has a function of fixing the polarizing layer 400 to the cholesteric liquid crystal layer 200. The adhesive layer 300 is light transmissive. That is, the adhesive layer 300 is transparent.

  The polarizing layer 400 is laminated on the cholesteric liquid crystal layer 200 via the adhesive layer 300. The polarizing layer 400 is provided so as to cover the entire surface of the cholesteric liquid crystal layer 200. The polarizing layer 400 is formed by laminating a quarter-wave plate layer 410 and a linear polarizing plate layer 420 in the order closer to the cholesteric liquid crystal layer 200. The polarizing layer 400 selectively absorbs polarized light.

  The quarter-wave plate layer 410 is laminated on the cholesteric liquid crystal layer 200 via the adhesive layer 300. The quarter-wave plate layer 410 changes linearly polarized light into clockwise or counterclockwise circularly polarized light. The quarter-wave plate layer 410 changes clockwise or counterclockwise circularly polarized light into linearly polarized light.

  The linear polarizing plate layer 420 is laminated adjacently under the quarter wave plate layer 410. The linearly polarizing plate layer 420 transmits linearly polarized light polarized in a predetermined direction. In this example, when viewed from the linear polarizing plate 420 side, the slow axis of the quarter-wave plate layer 410 is rotated 135 degrees clockwise with respect to the absorption axis of the linear polarizing plate layer 420. By doing so, the linearly polarized light emitted from the linearly polarizing plate layer 420 is transmitted through the quarter-wave plate layer 410, so that it becomes counterclockwise circularly polarized light. In this case, the left-handed circularly polarized light incident on the quarter-wave plate layer 410 from above in the drawing becomes linearly polarized light that passes through the linear polarizing plate layer 420 and passes through the linear polarizing plate layer 420. The clockwise circularly polarized light incident on the quarter-wave plate layer 410 from the upper side of the drawing becomes linearly polarized light blocked by the linear polarizing plate layer 420 and is blocked by the linear polarizing plate layer 420. Note that when viewed from the linear polarizing plate layer 420 side, when the slow axis of the quarter-wave plate layer 410 is rotated 45 degrees in the clockwise direction with respect to the absorption axis of the linear polarizing plate layer 420, the linearly polarized light The linearly polarized light emitted from the plate layer 420 is transmitted through the quarter-wave plate layer 410, so that a setting that becomes clockwise circularly polarized light is obtained.

  The adhesive layer 500 is provided between the identification layer 10 and the object 2. That is, the adhesive layer 500 is laminated adjacent to the linear polarizing plate layer 420. The adhesive layer 500 has a function of fixing the identification layer 10 to the object 2. The adhesive layer 500 is light transmissive. That is, the adhesive layer 500 is transparent.

  Note that the adhesive layer 300 and the adhesive layer 500 having a fixing function are made of a material such as a seal that shows an adhesive force when the release film is peeled off, an ultraviolet curable resin, a thermosetting resin, or other known adhesive materials. The In addition, the adhesive layer 300 and the adhesive layer 500 are transparent, but the whole may be transparent, or a part of the adhesive layer 300 and the adhesive layer 500 may be transparent by, for example, adding a process that produces characters when peeled. Further, the adhesive layer 300 and the adhesive layer 500 are not limited to being transparent, and the adhesive layer 300 and the adhesive layer 500 may be translucent as long as they have light transmissivity. In addition, you may utilize the adhesion layer which used the adhesive instead of the contact bonding layer.

(Identification function of the first embodiment)
Next, the identification function of the first embodiment will be described with reference to the drawings. Here, an example will be described in which the identification medium 1 shown in FIG. 3 is visually recognized without using an identification filter for identification and when it is visually recognized through an identification filter. One surface of the object 2 to which the identification medium 1 is fixed is called a surface (the upper surface in the figure), and the other surface of the object 2 to which the identification medium 1 is not fixed (the lower surface in the figure). Is called the back side. Further, as the identification filter, a right filter R (right circular polarization filter) that selectively transmits clockwise circular polarized light and a left filter L (left circular polarization filter) that selectively transmits counterclockwise circular polarized light are used.

(When observed from the surface without an identification filter)
First, a case will be described in which the identification medium 1 is observed from the direction (upper side in the drawing) of the object 2 where the identification medium 1 is fixed without using the identification filter. In this case, the reflected light from the cholesteric liquid crystal layer 200 is visually recognized. That is, right-handed circularly polarized light of incident light incident from the surface protective layer 100 side is reflected by the cholesteric liquid crystal layer 200 and observed. In addition, a color shift indicated by the cholesteric liquid crystal layer 200 is observed.

  On the other hand, incident light incident from the back surface of the object 2 is transmitted through the transparent object 2 and the transparent adhesive layer 500, and further, linearly polarized light in a specific direction is transmitted through the linearly polarizing plate layer 420. . Thereafter, the linearly polarized light that has passed through the linear polarizing plate layer 420 becomes counterclockwise circularly polarized light by the quarter-wave plate layer 410 and passes through the transparent adhesive layer 300, the cholesteric liquid crystal layer 200, and the transparent surface protective layer 100. Further, the component that could not reach the cholesteric liquid crystal layer 200 is absorbed by the polarizing layer 400.

  For this reason, when the identification medium 1 is observed from the direction (the upper side in the figure) of the object 2 where the identification medium 1 is fixed without going through the identification filter, the hologram design of the hologram forming unit 210, the cholesteric liquid crystal layer 200 The color (for example, green) and the scenery on the back side of the object 2 (the scenery on the other side seen through) can be visually recognized. Further, when the viewing angle is changed, the color of the cholesteric liquid crystal layer 200 changes due to the color shift of the cholesteric liquid crystal layer 200 and can be visually recognized.

(When observed from the surface via a right circular polarizing filter)
In FIG. 4, the identification medium 1 of the object 2 is fixed through a right filter R (right circular polarization filter) that selectively transmits clockwise circularly polarized light and blocks counterclockwise circularly polarized light and linearly polarized light. The state which looked at the identification medium 1 from the direction of is shown. In this case, only the reflected light from the cholesteric liquid crystal layer 200 is visually recognized. That is, right-handed circularly polarized light of incident light incident from the surface protective layer 100 side is reflected by the cholesteric liquid crystal layer 200 and passes through the right filter R.

  On the other hand, incident light incident from the back surface (lower side of the figure) of the object 2 is blocked by the polarizing layer 400, the cholesteric liquid crystal layer 200, or the right filter R. For this reason, the background is not visible, and the hologram pattern of the hologram forming unit 210 is more clearly shown as shown in FIG. 4 than when the identification medium 1 is viewed from the direction of the identification medium 1 of the object 2 fixed. (Black dots) and the color (for example, green) of the cholesteric liquid crystal layer 200 are visible. Further, also in this case, when the viewing angle is changed, the color of the cholesteric liquid crystal layer 200 is changed by the color shift of the cholesteric liquid crystal layer 200 and can be visually recognized.

(When observed from the surface via a left circular polarizing filter)
In FIG. 5, the identification medium 1 of the object 2 is fixed via a left filter L (left circular polarization filter) that selectively transmits counterclockwise circularly polarized light and blocks clockwise circularly polarized light and linearly polarized light. The state which looked at the identification medium 1 from the direction of the side is shown. In this case, the reflected light from the cholesteric liquid crystal layer 200 is not visually recognized. That is, right-handed circularly polarized light in the incident light incident from the surface protective layer 100 is reflected by the cholesteric liquid crystal layer 200 and blocked by the left filter L.

  On the other hand, incident light that has entered from the back surface of the object 2 passes through the transparent object 2 and the transparent adhesive layer 500, and specific linearly polarized light thereof passes through the linear polarizing plate layer 420. The linearly polarized light transmitted through the linear polarizing plate layer 420 becomes counterclockwise circularly polarized light by the quarter wavelength plate layer 410 and is transmitted through the transparent adhesive layer 300, the cholesteric liquid crystal layer 200, and the transparent surface protective layer 100. Then, the counterclockwise circularly polarized light transmitted through the surface protective layer 100 passes through the left filter L. Further, a part of incident light incident from the back surface of the object 2 is absorbed by the polarizing layer 400. For this reason, when the identification medium 1 is observed from the surface protective layer 100 side through the left circular polarizing filter, the hologram design of the hologram forming part 210 formed on the cholesteric liquid crystal layer 200 is not visually recognized, and the back surface of the object 2 Only the scenery on the side can be seen through.

(When viewed from the back without an identification filter)
FIG. 6 shows a state in which the identification medium 1 is viewed from the back surface of the object 2 (the lower side in FIG. 3) without using the identification filter. In this case, the reflected light from the cholesteric liquid crystal layer 200 is not visually recognized. That is, incident light incident from the surface protective layer 100 is transmitted through the transparent surface protective layer 100, and the counterclockwise circularly polarized light contained therein is transmitted through the cholesteric liquid crystal layer 200 and the transparent adhesive layer 300. Thereafter, the counterclockwise circularly polarized light transmitted through the adhesive layer 300 becomes linearly polarized light by the quarter-wave plate layer 410 and is transmitted through the linear polarizing plate layer 420, the transparent adhesive layer 500, and the transparent object 2.

  On the other hand, the linearly polarized light transmitted through the linearly polarizing plate layer 420 out of the incident light incident from the back surface of the target object 2 becomes counterclockwise circularly polarized light by the quarter wavelength plate layer 410, and the adhesive layer 300, the cholesteric liquid crystal layer 200, The surface protective layer 100 is transmitted. Also, most of the clockwise circularly polarized light in the incident light incident from the back surface of the object 2 is absorbed by the linear polarizing plate layer 420 and the rest is also absorbed by the transmission loss in the quarter wavelength plate. That is, the clockwise circularly polarized light in the incident light incident from the back surface of the object 2 is absorbed by the polarizing layer 400. For this reason, clockwise circularly polarized light does not reach the cholesteric liquid crystal layer 200. For this reason, when observed from the back without an identification filter, the hologram pattern of the hologram forming part 210 formed on the cholesteric liquid crystal layer 200 is not visually recognized, but only the scenery on the surface side of the object 2 (seen through). Visible.

(Identification function)
As described above, when the identification layer 10 is fixed to the object 2, when the identification layer 10 is viewed from the cholesteric liquid crystal layer 200 side in the direction in which the identification layer 10 is laminated, This is different from how the identification layer 10 is viewed. Therefore, authenticity determination can be performed even when the identification medium 1 is visually recognized through a tool for identification such as the right filter R and the left filter L, and authenticity determination is performed even when the identification medium 1 is viewed without using a tool. Can do. In addition, since the number of methods for performing authenticity determination increases, it is possible to improve discrimination and make forgery difficult.

  The polarizing layer 400 absorbs the same clockwise circularly polarized light as the clockwise circularly polarized light reflected by the cholesteric liquid crystal layer 200. Therefore, when the identification medium 1 is viewed from the back surface (downward direction of the figure) of the object 2, the reflected light from the cholesteric liquid crystal layer 200 is not visually recognized, and the appearance is the same as when viewed from the front side (upward direction of the figure). Different. That is, when the identification medium 1 is viewed from the direction of the object 2 on which the identification medium 1 is fixed, a hologram image of the cholesteric liquid crystal layer 200 is seen and the optical characteristics of the cholesteric liquid crystal layer 200 are visually recognized. When the identification medium 1 is viewed from the back side of the object 2 through the object 2, the reflected light from the cholesteric liquid crystal layer 200 is not visually recognized but looks transparent. Based on the difference in appearance, it is possible to perform authentication determination without using a tool.

(Other)
The polarizing layer 400 is not limited to being provided so as to cover the entire surface of the cholesteric liquid crystal layer 200, and the polarizing layer 400 may be provided partially. In this case, the appearance of the object 2 when viewed from the direction where the identification medium 1 is fixed is not different from the case of FIGS. 4 and 5, but it is viewed from the back surface (the lower side of the figure) of the object 2. When viewed, the hologram design disappears only in the portion where the polarizing layer 400 is provided, and the portion where the hologram design disappears stands out. Therefore, it becomes a unique appearance, an authenticity determination function that is performed without using a tool is enhanced, and the identification property of the identification medium 1 can be enhanced. Moreover, it is good not only when making the whole surface of the target object 2 transparent, but it is good also as the target object 2 which has the transparent part 21 which has light transmittance, and the opaque part 22 which does not have light transmittance, as shown in FIG. .

(2) Second Embodiment The second embodiment is a modification of the first embodiment. Accordingly, the changed part will be mainly described, and the description of the same configuration and operation as those of the first embodiment will be omitted. FIG. 8 is a cross-sectional view showing an identification medium and an object according to the second embodiment.

  In the identification medium 3, a retardation layer 600 is provided on the identification layer 11. The retardation layer 600 is laminated on the side of the surface protective layer 100 opposite to the side on which the cholesteric liquid crystal layer 200 is laminated. That is, the retardation layer 600 is provided on the outer surface of the surface protective layer 100. The retardation layer 600 is provided so as to cover a part of the surface of the surface protective layer 100. The retardation layer 600 changes clockwise circularly polarized light to counterclockwise circularly polarized light or changes leftward circularly polarized light to clockwise circularly polarized light. In this example, a half-wave plate is used as the retardation layer 600.

  According to the second embodiment, the identification medium 3 from the direction (upper side in the figure) of the object 2 to which the identification medium 3 is fixed without passing through the identification filter and the opposite direction (lower side in the figure). Is the same as in the first embodiment. On the other hand, when the identification medium 3 is viewed from the direction where the identification medium 3 of the object 2 is fixed via the right filter R, the counterclockwise circularly polarized light in the incident light incident on the retardation layer 600 is The phase difference layer 600 causes clockwise circularly polarized light to be reflected by the cholesteric liquid crystal layer 200. The reflected clockwise circularly polarized light becomes counterclockwise circularly polarized light by the retardation layer 600 and is blocked by the right filter R. Therefore, the hologram design disappears in the portion where the retardation layer 600 is provided, and the hologram design is visible in the portion where the retardation layer 600 is not provided.

  Further, when the identification medium 3 is viewed from the direction of the identification medium 3 of the object 2 fixed via the left filter L, the counterclockwise circularly polarized light in the incident light incident on the retardation layer 600 is The phase difference layer 600 causes clockwise circularly polarized light to be reflected by the cholesteric liquid crystal layer 200. The reflected clockwise circularly polarized light becomes counterclockwise circularly polarized light by the retardation layer 600 and passes through the left filter L. Therefore, the hologram design can be seen in the portion where the retardation layer 600 is provided, and the hologram design disappears in the portion where the retardation layer 600 is not provided.

  A mode in which the phase difference generated in the phase difference layer 600 is not a (1/2) wavelength (in the case of a layer that generates a phase difference other than 0) is also possible. In this aspect, even when the identification medium 3 is viewed through the right filter R or when the identification medium 3 is viewed through the left filter L, the phase difference layer 600 has (1/2). Since a phase difference which is not a wavelength is generated, a hologram pattern in a portion where the phase difference layer 600 is present can be seen. When the identification medium is viewed directly, the appearance is the same as in the first embodiment.

(3) Third Embodiment The third embodiment is a modification of the first embodiment. Accordingly, the changed part will be mainly described, and the description of the same configuration and operation as those of the first embodiment will be omitted. FIG. 9 is a sectional view showing an identification medium and an object according to the third embodiment.

  In the identification medium 4, a cholesteric liquid crystal layer 700 is provided on the polarizing layer 401 of the identification layer 12. The cholesteric liquid crystal layer 700 is laminated adjacent to the linear polarizing plate layer 420. That is, the cholesteric liquid crystal layer 700 is provided between the linear polarizing plate layer 420 and the adhesive layer 500. The cholesteric liquid crystal layer 700 is formed by a printing method using an ink containing a cholesteric liquid crystal layer, and is provided so as to cover the entire surface of the linear polarizing plate layer 420. The cholesteric liquid crystal layer 700 may be the same as the cholesteric liquid crystal layer 200 or may exhibit different optical characteristics. That is, the type of the cholesteric liquid crystal layer 700 is not limited as long as it is a cholesteric liquid crystal layer.

  According to the third embodiment, when the identification medium 4 is viewed from the direction (upper side in the drawing) of the object 2 on which the identification medium 4 is fixed, the same as in the first embodiment. On the other hand, when the identification medium 4 is viewed from the back surface (the lower side of the drawing) of the object 2 without using the identification filter, the component reflected by the cholesteric liquid crystal layer 200 (a clockwise circle having a specific wavelength) as viewed from the back surface side. (Polarized light) is reflected by the cholesteric liquid crystal layer 700 or absorbed by the polarizing layer 400 and does not reach the cholesteric liquid crystal layer 200. For this reason, the hologram pattern 210 of the cholesteric liquid crystal layer 200 disappears and the color of the cholesteric liquid crystal layer 700 can be seen. Further, a part or all of the components incident on the cholesteric liquid crystal layer 200 from the surface protective layer 100 side and transmitted through the cholesteric liquid crystal layer 200 are also transmitted through the cholesteric liquid crystal layer 700. For this reason, the scenery on the front side of the identification medium 4 can be seen through.

  The cholesteric liquid crystal layer 700 is not limited to being provided so as to cover the entire surface of the linear polarizing layer 420, and may be provided partially. Further, the cholesteric liquid crystal layer 700 may be subjected to hologram processing.

(4) Fourth Embodiment The fourth embodiment of the identification medium is a modification of the first embodiment. Therefore, the changed part will be mainly described, and the description of the same configuration as that of the first embodiment will be omitted. FIG. 10 is a sectional view showing an identification medium and an object according to the fourth embodiment.

  The identification medium 5 is provided with a cholesteric liquid crystal layer 800 that serves as a polarizing layer without providing the polarizing layer 400 on the identification layer 13. The cholesteric liquid crystal layer 800 has optical characteristics similar to those of the cholesteric liquid crystal constituting the cholesteric liquid crystal layer 200. That is, the cholesteric liquid crystal layer 800 selectively reflects clockwise circular polarized light including a specific wavelength (for example, green) reflected by the cholesteric liquid crystal layer 200 and transmits other components. Note that the wavelength range of polarized light reflected by the cholesteric liquid crystal layer 800 may be wider than the wavelength range of polarized light reflected by the cholesteric liquid crystal layer 200.

  According to the fourth embodiment, when the identification medium 5 is viewed from the direction where the identification medium 5 of the object 2 is fixed, it is the same as in the first embodiment, and the identification filter 5 is not used. When the identification medium 5 is viewed from the back of the object 2, the hologram pattern 210 of the cholesteric liquid crystal layer 200 disappears, the color of the cholesteric liquid crystal layer 800 can be seen, and the other side can be seen through. That is, when viewed from the back side, a component reflected by the cholesteric liquid crystal layer 200 is reflected by the cholesteric liquid crystal layer 800 and does not reach the cholesteric liquid crystal layer 200. For this reason, the hologram pattern 210 of the cholesteric liquid crystal layer 200 disappears, and the color of the cholesteric liquid crystal layer 800 can be seen. Further, a part or all of the components incident on the cholesteric liquid crystal layer 200 from the surface protective layer 100 side and transmitted through the cholesteric liquid crystal layer 200 are also transmitted through the cholesteric liquid crystal layer 800. For this reason, the scenery on the front side of the identification medium 5 can be seen through. In other words, the other side of the identification medium 5 can be seen through the object 2 when viewed from the back side.

  The cholesteric liquid crystal layer 800 is not limited to be provided so as to cover the whole, but may be provided partially. Further, the cholesteric liquid crystal layer 800 may be subjected to hologram processing.

(5) Other Embodiments When a notch is made in the identification medium 1 and is to be peeled off from the object 2, the identification medium 1 may be torn from the notch and cannot be reused. In this way, unauthorized reuse of the identification medium 1 can be prevented. By utilizing this principle, it is possible to obtain an opening identification seal for identifying whether or not the package is opened.

  In addition, a configuration in which interlaminar fracture occurs when an attempt is made to peel the identification medium 1 from the object 2 to some layers constituting the identification medium 1 can also be given. As a specific example of this configuration, an example in which the layer structure of the cholesteric liquid crystal layer 200 is physically destroyed and separated in the stacked direction before the adhesive layer 300 or the adhesive layer 500 is peeled off is given. be able to. This adjustment can be realized by adjusting a temperature condition at the time of manufacturing the cholesteric liquid crystal layer 200.

  Furthermore, the adhesive layer 500 may not be provided, and the identification layers 10 to 13 may be used alone without being attached like a tag. Moreover, the target object 2 may have a part which has a light transmittance. In this case, the light-transmitting part contributes to the visual effect when observed from the back side. Further, the article to be applied may be a cash card or an identification card. In this case, at least a part of the cash card or identification card is provided with a transparent part (watermark part), and the structure shown in the embodiment as the object 2 may be applied.

  The present invention can be used for an identification medium used for authenticity determination.

It is sectional drawing which shows an identification medium and a target object. It is a conceptual diagram which shows notionally the structure of a cholesteric liquid crystal layer. It is sectional drawing which shows the case where an identification medium is visually recognized. It is a figure which shows the case where an identification medium is seen from the surface through a right filter. It is a figure which shows the case where an identification medium is seen from the surface through the left filter. It is a figure which shows the case where an identification medium is seen from the back surface by visual observation. It is a figure which shows the target object which has a part which has a light transmittance in part. It is sectional drawing which shows the identification medium and target object concerning 2nd Embodiment. It is sectional drawing which shows the identification medium and target object concerning 3rd Embodiment. It is sectional drawing which shows the identification medium and target object concerning 4th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Identification medium, 2 ... Object, 10 ... Identification layer, 200 ... Cholesteric liquid crystal layer, 400 ... Polarizing layer, 410 ... 1/4 wavelength plate layer, 420 ... Linear polarizing plate layer, 500 ... Adhesive layer.

Claims (3)

An identification medium for identifying by observation from one side and observation from the other side,
A cholesteric liquid crystal layer that forms a hologram and reflects clockwise or counterclockwise circularly polarized light, and an identification layer that is stacked on the cholesteric liquid crystal layer and has a polarizing layer that transmits specific polarized light;
A light-transmitting fixing layer for fixing the identification layer to a light-transmitting object,
The polarizing layer is laminated on the cholesteric liquid crystal layer, and changes the linearly polarized light into clockwise or counterclockwise circularly polarized light, or changes the clockwise or counterclockwise circularly polarized light into linearly polarized light, A linear polarizing plate layer that is laminated on a / 4 wavelength plate layer and transmits linearly polarized light,
And appearance of the hologram when the identification layer is visually the identification layer from the cholesteric liquid crystal layer side in the laminated direction, and the said appearance of the hologram in the case of visually the identification layer from the polarizing layer side An identification medium characterized by being different.   The identification medium according to claim 1, wherein the polarizing layer absorbs or reflects the same circularly polarized light as the circularly polarized light reflected by the cholesteric liquid crystal layer. An object having optical transparency;
An article comprising: the identification medium according to claim 1.

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