JP2014021152A - Identification medium and identification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an identification medium in which a dramatic change in a fine pattern appears.SOLUTION: An identification medium has a layer of fluorescent dichroic pigments having an embossment structure having an orientation along a specific direction in order to carry out a hologram display and molecules in the fluorescent dichroic pigments are oriented along the specific direction. For example, the state of orientation in the layer of the fluorescent dichroic pigments has: a first region oriented in a first direction; a second region oriented in a second direction; and a third region oriented in a third direction. In this case, the first direction to the third direction are different directions from each other and an angle formed by the first direction and the second direction and an angle formed by the first direction and the third direction are the same.

Description

  The present invention includes a passport, a document, various cards, a pass, a banknote, a cash voucher, a security, a certificate, a gift certificate, a picture, a ticket, a public competition voting ticket, a recording medium on which music and video are recorded, and a recording on which computer software is recorded. The present invention relates to a technique for identifying authenticity (authenticity) of media, various parts, various products, and their packages.

  Patent Document 1 describes a technique in which a liquid crystal compound that emits polarized light is applied to an alignment substrate and attached to an object, and the light emission intensity is measured through a polarizing plate. Patent Document 2 describes a technique in which a fluorescent dichroic dye is applied to an alignment substrate and a latent image on which polarization information is formed is discriminated through a polarizing plate. Patent Document 3 describes an optical security element in which liquid crystal molecules are aligned using a diffractive structure using embossing.

JP 2009-250817 A JP 2011-131527 A Japanese Patent No. 4768600

  In the optical identification medium, it is important to be able to observe a dramatic change in a fine pattern when the polarizing plate is rotated or switched. This is because if the design is fine, counterfeiting is more difficult, and the dramatic changes in design are greatly affected by the manufacturing conditions and structure. Because it becomes difficult to do. Here, in the techniques described in Patent Documents 1 and 2, since the orientation direction is controlled by orientation treatment, it takes time to form a fine pattern and is not practical. In this regard, the orientation control using the embossed structure of Patent Document 3 is advantageous, but it is not satisfactory in terms of dramatic changes in fine patterns.

  In such a background, an object of the present invention is to provide an identification medium in which a dramatic change of a fine pattern appears.

  The invention according to claim 1 comprises a layer of polarized fluorescent light emitting material provided with an embossed structure for performing hologram display, the embossed structure having an arrangement along a specific direction, and the polarized fluorescent light emitting The material layer is oriented in a direction along the specific direction, and the polarized fluorescent light emitting material layer oriented in the specific direction has a plurality of regions having different orientation states. It is a characteristic identification medium.

  In the first aspect of the present invention, the polarized fluorescent light-emitting material is in a state of being oriented in a specific direction, and when irradiated with specific light, linearly polarized fluorescence whose polarization direction coincides with the direction of the orientation is generated. The material. Examples of the polarized fluorescent light-emitting material include a fluorescent dichroic dye that is in an alignment state that fluoresces when irradiated with ultraviolet light, or a liquid crystal compound that is in an aligned state that fluoresces when irradiated with ultraviolet light.

  Since the embossed structure can be formed using a mold, it is easy to make a fine structure. In addition, since the polarized fluorescent light emitting material emits linearly polarized light in a situation where specific light is applied, it shows a dramatic change in appearance when observed through a linear polarization filter. Therefore, it is possible to obtain an identification medium in which a dramatic change of a fine design appears. A similar optical function can also be obtained when irradiation light that triggers fluorescence is irradiated through a linear polarization filter. Moreover, figures, characters, various patterns, and the like can be used as the formed pattern.

  As the identification medium using the invention according to the first aspect, both a reflection type and a transmission type can be realized. In the case of a transmissive structure, fluorescence is generated on the front side when light for generating fluorescence is emitted from the other side of the identification medium. Of course, in the reflection type structure, it is also possible to observe fluorescence from the surface side irradiated with light for generating fluorescence.

  The invention according to claim 2 is the invention according to claim 1, wherein the plurality of regions are a first region oriented in a first direction, a second region oriented in a second direction, A third region oriented in a third direction, wherein the first direction to the third direction are different from each other, and an angle formed by the first direction and the second direction; The angle formed by the first direction and the third direction is the same.

  According to the second aspect of the present invention, in the state where the light for generating fluorescence is irradiated on the layer of the polarized fluorescent light emitting material, the linearly polarized fluorescence in the corresponding direction is generated from each region. In this configuration, the first to third regions are separately created by the embossed structure. For example, consider a case where fluorescence is generated by ultraviolet light. In this case, in the state where the non-polarized ultraviolet light is irradiated and the fluorescence is generated, the linearly polarized fluorescence polarized in the first direction, the linearly polarized fluorescence polarized in the second direction, and the third direction Polarized linearly polarized fluorescence is observed. When these three types of fluorescence are observed through the linear polarization filter, the intensity of the three fluorescences is increased or decreased depending on the relationship between the polarization direction of the linear polarization filter and the polarization direction of each fluorescence.

  These three types of fluorescence intensity change individually when the linear polarization filter is rotated relative to the identification medium. Further, the fluorescence is preferential at the relative rotational position where the polarization direction of the fluorescence from the specific region and the polarization direction of the linear polarization filter coincide with each other, and the intensity of the fluorescence from the other two regions decreases. . In other words, one of the three regions appears preferentially. The phenomenon in which this one area looks preferentially compared to the other two areas is switched when the relative rotation angle of the linear polarization filter and the identification medium is changed. That is, when the relative rotation angle of the linear polarization filter and the identification medium is changed, the first area is preferentially seen, the second area is preferentially seen, and the third area is preferentially seen. The state changes.

  In the situation where the first region is preferentially viewed, the polarization direction in the second and third regions and the polarization direction of the linear polarization filter have the same relationship, so the second region and the third region are It looks the same and cannot be distinguished. That is, only the first area appears to be raised. Of course, when the linear polarization filter is rotated, the symbol constituted by the second region and the symbol constituted by the third region can be recognized.

  Here, an example of irradiating non-polarized ultraviolet light and observing fluorescence from a polarized fluorescent light-emitting material through a linear polarizing filter has been explained, but the same optical function is irradiated with linear polarized ultraviolet light. However, the same applies to the case of observing the fluorescence at that time. In this case, the same optical function can be obtained by rotating the direction of the linearly polarized light to be irradiated. This point is the same in the descriptions related to other claims.

  The invention according to claim 3 is the invention according to claim 2, wherein an angle formed by the first direction and the second direction and an angle formed by the first direction and the third direction are as follows. Are both 45 °. According to the third aspect of the present invention, when the alignment direction of the linear polarizing filter is aligned with the alignment direction of the second region, the polarization direction of the linear polarizing filter is orthogonal to the alignment direction of the third region. Therefore, the fluorescence in the third region is not observed, and the fluorescence in the second region is preferentially observed. A similar phenomenon occurs when the relationship between the second and third regions is switched. For this reason, high discrimination is obtained.

  The invention according to claim 4 is the invention according to claim 3, wherein the layer of the polarized fluorescent light-emitting material has a fourth region oriented in a fourth direction different from the first to third directions. The angle between the fourth direction and the first direction is 90 °. In this case, the first region and the fourth region are perpendicular to each other in the polarization direction of the fluorescence, so that when one is bright, the other is dark, and higher discrimination is obtained.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the polarized fluorescent light-emitting material is irradiated with a fluorescent dichroic dye or ultraviolet light that fluoresces when irradiated with ultraviolet light. This is a liquid crystal compound that fluoresces. For example, by using a fluorescent dichroic dye that fluoresces when irradiated with ultraviolet light, it is difficult to distinguish each region without irradiating with ultraviolet light in observation using a linearly polarized light filter. The area can be clearly identified. For this reason, when an identification medium composed of a plurality of regions with different orientation directions is observed through a linear polarizing filter, a pattern that is difficult to see without irradiation with ultraviolet light is clear when irradiated with ultraviolet light. The optical function can be obtained.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the plurality of regions have a plurality of regions having the same orientation direction and different orientation pitches. And According to the sixth aspect of the present invention, there is a difference between the appearance of the hologram image in the first orientation pitch area and the appearance of the hologram image in the second orientation pitch area in a situation where no fluorescence is generated. Observed. Since this difference is reduced in a state where fluorescence is generated, it is possible to obtain an identification function that makes it difficult to see a pattern that was visible in a state where fluorescence is not generated in a state where fluorescence is generated.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the unevenness of the embossed structure of the layer of the polarized fluorescent light emitting material is filled with a resin. . In general, the refractive index value of the resin and the refractive index value of the layer of the polarized fluorescent light emitting material are close to each other. Therefore, in a situation where the embossed structure is filled with the resin, the ultraviolet light is not irradiated. The degree of light refraction and reflection at the embossed structure interface is small, and the hologram image is difficult to see. Therefore, in a state where light that causes fluorescence is not irradiated, it is difficult to see each of the divided areas due to the difference in the embossed structure. On the other hand, when irradiating light that causes fluorescence, the polarized fluorescent light-emitting material fluoresces, so that linearly polarized fluorescence due to the embossed structure can be observed, and each region divided by the difference in the embossed structure has a different direction. The linearly polarized light is emitted, and a specific pattern can be visually recognized by a combination of differences in the appearance of each region. In other words, it is possible to obtain a latent image in which an image that has been hidden in a state in which light that causes fluorescence is not emitted emerges upon irradiation with light that causes fluorescence. The resin that fills the embossed structure of the layer of the polarized fluorescent light emitting material is selected so as to transmit visible light and light that causes fluorescence (of course, there may be a loss).

  The invention according to claim 8 is the invention according to claim 7, wherein the ratio of the refractive index of the layer of the polarized fluorescent light-emitting material and the refractive index of the resin is in the range of 0.8 to 1.2. Features. By making the refractive index of the layer of the polarized fluorescent light-emitting material layer and the refractive index of the resin filling the unevenness of the embossed structure of this layer within the above range, in the state where the light causing fluorescence is not irradiated, It is difficult to recognize the division of the region, and the tendency that the pattern constituted by the embossed structure appears to be almost transparent without being seen is more prominent.

  The invention according to claim 9 is the invention according to claim 8, wherein the refractive index of the layer of the polarized fluorescent light emitting material is the refractive index in the direction perpendicular to the oriented direction and the refractive index in the oriented direction. It is an average value (intermediate value).

  The invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein a cholesteric liquid crystal layer is provided in contact with the embossed surface of the layer of the polarized fluorescent light-emitting material, The embossed surface is formed using an embossed structure for hologram formation formed on the surface of the cholesteric liquid crystal layer. According to the tenth aspect of the invention, the embossed structure for forming a hologram formed in the cholesteric liquid crystal layer is further used for controlling the orientation of the polarized fluorescent light emitting material. According to this aspect, the hologram image resulting from the embossed structure formed in the cholesteric liquid crystal layer is observed selectively using the circular polarizing filter, and in the observation using the linear polarizing filter in the fluorescent state, A fluorescence image resulting from the orientation state of the layer of the polarized fluorescent light-emitting material can be observed.

  The invention according to claim 11 is directed to the identification medium according to any one of claims 1 to 10, when the non-polarized ultraviolet light is irradiated to the identification medium via a linear polarization filter. It is an identification method characterized by observing.

  Invention of Claim 12 observes the said identification medium in the state in which the linearly polarized ultraviolet light is irradiated with respect to the identification medium as described in any one of Claims 1-10. This is an identification method.

  ADVANTAGE OF THE INVENTION According to this invention, the identification medium in which the dramatic change of a fine pattern appears is provided.

It is process sectional drawing (A)-(E) which shows the manufacturing process of the identification medium of embodiment in steps. It is a schematic diagram which shows the state of an embossed surface. It is the conceptual diagram (A) which shows the state of orientation of the layer of a fluorescent dichroic dye, and the conceptual diagram (B) which shows the area | regions ad made into the same orientation direction. It is a front view (A)-(E) which shows how an identification medium of an embodiment looks. It is process sectional drawing (A)-(E) which shows the manufacturing process of the identification medium of embodiment in steps. It is process sectional drawing (A)-(E) which shows the manufacturing process of the identification medium of embodiment in steps. It is sectional drawing of the identification medium of embodiment. It is sectional drawing of the identification medium of embodiment. It is a front view which shows how the identification medium of embodiment is visible.

First embodiment (structure and manufacturing process)
FIG. 1 is a process cross-sectional view illustrating a manufacturing process of an identification medium according to an embodiment step by step. FIG. 1E shows an identification medium 106 according to the embodiment. Hereinafter, the manufacturing process of the identification medium 106 will be described. First, a diffraction grating 101 having an embossed surface (diffraction grating surface) 101a subjected to hologram processing is prepared (FIG. 1A). The diffraction grating 101 is a mold member serving as a base for forming an embossed surface for performing hologram display, and is made of resin, glass, metal, or the like.

  FIG. 2 schematically shows an example of the embossed surface 101 a formed on the surface of the diffraction grating 101. The embossed surface 101a is a mold for forming irregularities for forming a hologram by optical interference, and has a structure oriented in one direction (in the Y-axis direction in the case of FIG. 2) as shown. . Here, the pitch L of the groove structure is selected from about 0.3 μm to 1.5 μm.

  When the diffraction grating 101 is prepared, a fluorescent dichroic dye layer 102, which is one of the layers using a polarized fluorescent material, is formed on the diffraction grating 101 (FIG. 1B). The thickness of the layer 102 of the fluorescent dichroic dye is, for example, about 0.5 μm to 5 μm. When the layer 102 (see FIG. 1) of the fluorescent dichroic dye is formed on the embossed surface 101a, the fluorescent dichroic dye has a molecular long axis aligned with the Y-axis direction of FIG. The state of molecular orientation of layer 102 is determined. The embossed surface 102a formed on the surface of the fluorescent dichroic dye layer 102 is a shape to which the embossed surface 101a of FIG. 2 is transferred, and has the same surface shape as shown in FIG. . The fluorescent dichroic dye has a molecular structure having anisotropy. Optically, it does not have an absorption band in the visible region, and has the property that the absorbance and the fluorescence emission intensity associated with light absorption differ greatly depending on the major axis direction of the dye molecule and the direction orthogonal thereto. . When this fluorescent dichroic dye is irradiated with light in the ultraviolet band, it is absorbed and fluorescence including light in the visible light band is generated.

  For example, consider a situation in which linearly polarized ultraviolet light is irradiated in a state where the molecules of the fluorescent dichroic dye are aligned in a specific direction. At this time, if the polarization direction of the ultraviolet light coincides with the direction of the molecular long axis of the fluorescent dichroic dye, the absorption efficiency of the ultraviolet light is maximized and the fluorescence emission intensity is also maximized. The fluorescence at this time is linearly polarized light polarized in the orientation direction of the fluorescent dichroic dye molecule. On the other hand, when the polarization direction of the ultraviolet light is orthogonal to the direction of the long axis of the fluorescent dichroic dye molecule, the absorption efficiency of the ultraviolet light is lowered and the emission intensity of the fluorescence is also reduced. That is, when a linearly polarized light polarized in the X-axis direction is irradiated onto a fluorescent dichroic dye oriented in the X-axis direction, linearly polarized fluorescence polarized in the X-axis direction is relatively strongly generated. When irradiated with linearly polarized light polarized in the Y-axis direction, almost no fluorescence is generated.

  In addition, when the polarized fluorescent dichroic dye is irradiated with non-polarized ultraviolet light, the linearly polarized light in the aligned direction is preferentially fluorescent. That is, when the dichroic dye oriented in the X-axis direction is irradiated with non-polarized (polarized light not having a specific polarization state) ultraviolet light, linearly polarized light polarized in the X-axis direction mainly emits light. At this time, linearly polarized light polarized in the Y-axis direction does not occur or is weak even if it occurs.

  Fluorescent dichroic dyes include benzothiazole dyes, but other dyes can also be used. For example, various dyes described in the reference "Display and Functional Dye, CMC, p64-73" can be used. Fluorescent dichroic dyes can be used. As the polarized fluorescent light-emitting material, a liquid crystal compound that emits polarized light described in JP-A-2009-250817 can also be used.

  The fluorescent dichroic dye layer 102 in FIG. 1B is formed by applying a solution containing the above-described fluorescent dichroic dye to the embossed surface 101 a of the diffraction grating 101. At this time, additives can be added to the solution to be applied, if necessary. A groove structure illustrated in FIG. 2 is formed on the embossed surface 101a of the diffraction grating 101, and the molecules of the fluorescent dichroic dye included in the layer 102 of the fluorescent dichroic dye are oriented according to the groove structure. In addition, the shape of the interface between the fluorescent dichroic dye layer 102 and the diffraction grating 101 is an uneven shape following the embossed structure of the embossed surface 101a. That is, an embossed surface 102 a that functions as a diffraction grating for forming a hologram is formed on the surface of the layer 102 of the fluorescent dichroic dye.

  When the state shown in FIG. 1B is obtained, the support film 103 is laminated on the exposed surface of the layer 102 of the fluorescent dichroic dye in this state (FIG. 1C). As the support film 103, a film made of a resin material that has no refractive index anisotropy such as TAC (triacetyl cellulose), acrylic, polycarbonate, or the like and does not disturb the state of polarization of transmitted light is used. Although the thickness of the support film 103 should just be a value which can ensure the intensity | strength required, the value of about 10 micrometers-100 micrometers is selected, for example.

  After the support film 103 is laminated, an adhesive layer 104 composed of a transparent adhesive is formed to obtain the state shown in FIG. For example, a value of about 5 μm to 30 μm is selected as the thickness of the adhesive layer 104. Although not shown, a separator (release paper) is attached to the exposed surface of the adhesive layer 104 in an unused state, and this separator is peeled off when the adhesive layer 104 is attached to the object. The identification medium 106 is affixed to a target object by making it contact with a target object. Further, if the transmission type is not used, it is not necessary to make the adhesive layer 104 transparent.

  When the state shown in FIG. 1C is obtained, the diffraction grating 101 is peeled from the layer 102 of the fluorescent dichroic dye. FIG. 1D shows a state in which the diffraction grating 101 is peeled upside down from the state of FIG. In this state, the fluorescent dichroic dye layer 102 is held on one side of the support film 103, and the adhesive layer 104 is provided on the other side of the support film 103. Further, an embossed surface 102 a to which the embossed shape of the embossed surface 101 a formed on the surface of the diffraction grating 101 is transferred is formed on the exposed surface of the fluorescent dichroic dye layer 102.

  When the state shown in FIG. 1D is obtained, the exposed surface of the fluorescent dichroic dye layer 102 has no refractive index anisotropy such as TAC, acrylic, polycarbonate, etc., and does not disturb the polarization state of transmitted light. The protective layer 105 is formed by laminating a resin material with an adhesive or an adhesive. Alternatively, the protective layer 105 may be formed by applying a liquid material such as urethane resin and curing. Here, it is important that the embossed structure (uneven structure) formed on the surface of the layer 102 of the fluorescent dichroic dye is filled with the adhesive, adhesive or resin of the protective layer 105. As the thickness of the protective layer 105, for example, a value of about 5 μm to 100 μm is selected.

  Further, the ratio of the refractive index of the fluorescent dichroic dye layer 102 to the refractive index of the protective layer 105 is set to fall within the range of 0.8 to 1.2, more preferably 0.9 to 1.1. To do. Here, the refractive index of the layer 102 of the fluorescent dichroic dye is based on the refractive index of the fluorescent dichroic dye in the molecular major axis direction (orientation direction) and the refraction in the molecular minor axis direction (direction orthogonal to the orientation direction). The average (intermediate) value with the rate is adopted. By making the refractive index values of the fluorescent dichroic dye layer 102 and the protective layer 105 close to each other in the visible light band, when observed in an environment irradiated with visible light, the fluorescent dichroic dye described later is used. The pattern of the layer 102 is difficult to see and the latent image effect observed when irradiated with ultraviolet light can be obtained more remarkably. When the ratio between the refractive index of the fluorescent dichroic dye layer 102 and the refractive index of the protective layer 105 is out of the above range, the fluorescent dichroic dye layer 102 described later is used in an environment where visible light is applied. The pattern is more visible, and the latent image effect observed when irradiated with ultraviolet light, that is, the image (design) that had not been seen before when exposed to ultraviolet light, appears to emerge. The tendency to become less effective increases.

(Pattern of fluorescent dichroic dye layer)
The layer 102 of the fluorescent dichroic dye is not uniform, and a pattern described below is formed. FIG. 3 conceptually shows the state of the embossed structure pattern when the fluorescent dichroic dye layer 102 is viewed from the front. FIG. 3A shows the overall state, and FIG. 3B shows a rectangular region. In each of the four rectangular areas a to c in FIG. 3B, an emboss structure is arranged along the orientation direction shown in the figure, and a plurality of grooves extend in that direction ( (See FIG. 2). The direction in which the groove structure extends is the orientation direction of the fluorescent dichroic dye. In this example, the embossed structure in each of the areas a to c is uniform.

  That is, in the rectangular regions a and b, the orientation directions of the fluorescent dichroic dye (the direction of the molecular long axis) are orthogonal to each other. Similarly, the rectangular regions c and d have a relationship in which the orientation directions of the fluorescent dichroic dyes are orthogonal to each other. The rectangular regions a and c have a relationship in which the orientation direction of the fluorescent dichroic dye differs by 45 °. The rectangular regions b and d have a relationship in which the orientation direction of the fluorescent dichroic dye differs by 45 °. The shape of each region is not limited to a rectangle, and may be a circle or a polygon other than a rectangle (rectangle or hexagon).

(Optical function)
FIG. 4A shows a case where the identification medium 106 is observed from the front (the protective layer 105 side) in an environment where natural light is applied. In this case, fluorescence of the fluorescent dichroic dye does not occur (or is weak even if it occurs and is difficult to observe). Further, since the embossed structure on the surface of the fluorescent dichroic dye layer 102 is filled with the protective layer 105 having a refractive index close to that of the fluorescent dichroic dye layer 102, the embossed surface of the fluorescent dichroic dye layer 102 is embossed. The reflection and refraction of visible light from the structure interface is weak, and the hologram effect due to the embossed structure is weak. For this reason, the grid structure shown in FIG. 3A is difficult to observe, and the identification medium 106 is almost transparent, or the grid structure shown in FIG. This is the same whether or not a linear polarizing filter is used, regardless of the use of the linear polarizing filter. This state is shown in FIG.

  Next, a case in an environment irradiated with non-polarized ultraviolet light will be described. In the following description, a case where observation is performed in a state where the back of the identification medium 106 is black will be described.

  FIG. 4B shows identification through a linearly polarizing filter that selectively transmits linearly polarized light in a direction matching the orientation direction of region b in FIG. 3 in an environment irradiated with non-polarized ultraviolet light. The case where the medium 106 is observed is shown. In this case, in the region a, linearly polarized fluorescence is generated in a direction orthogonal to the polarization direction of the linear polarizing filter to be used. Since this fluorescence is blocked by the linear polarization filter and cannot be observed, the region a appears black. In the region b, linearly polarized fluorescence is generated in a direction parallel to the polarization direction of the linear polarizing filter to be used. Since this fluorescence is transmitted through the linear polarization filter, the region b appears bright. Further, since the fluorescence generated in the regions c and d is linearly polarized light deviated by 45 ° from the polarization direction of the linear polarizing filter, a loss occurs in the linear polarizing filter, which is darker than the region b and brighter than the region a. That is, it looks like a lightness intermediate between the areas d and a. As a result, a mosaic pattern as shown in FIG. 4B is observed. The pattern shown in FIG. 4B is a latent image that is not visible when ultraviolet light is not irradiated and is visible when ultraviolet light is irradiated.

  FIG. 4C shows identification through a linear polarization filter that selectively transmits linearly polarized light in a direction matching the orientation direction of the region a in FIG. 3 in an environment irradiated with unpolarized ultraviolet light. The case where the medium 106 is observed is shown. In this case, in the region a, linearly polarized fluorescence is generated in a direction parallel to the polarization direction of the linear polarization filter to be used. Since this fluorescence is transmitted through the linear polarization filter, the region a looks bright. Further, in the region b, linearly polarized fluorescence is generated in a direction orthogonal to the polarization direction of the linear polarizing filter to be used. Since this fluorescence is blocked by the linear polarization filter, the region b appears black. Further, since the fluorescence generated in the regions c and d is linearly polarized light deviated by 45 ° from the polarization direction of the linear polarizing filter, a loss occurs in the linear polarizing filter, which is darker than the region a and brighter than the region b. It looks like a state, that is, a lightness intermediate between the areas a and b. As a result, a mosaic pattern as shown in FIG. 4C is observed. The pattern shown in FIG. 4C is a latent image that is not visible when ultraviolet light is not irradiated and is visible when ultraviolet light is irradiated.

  FIG. 4D shows identification through a linear polarization filter that selectively transmits linearly polarized light in a direction matching the orientation direction of the region d in FIG. 3 in an environment irradiated with non-polarized ultraviolet light. The case where the medium 106 is observed is shown. In this case, in the region c, linearly polarized fluorescence is generated in a direction orthogonal to the polarization direction of the linear polarization filter to be used. Since this fluorescence is blocked by the linear polarization filter, the region c appears black. In the region d, linearly polarized fluorescence is generated in a direction parallel to the polarization direction of the linear polarizing filter to be used. Since this fluorescence is transmitted through the linear polarization filter, the region d appears bright. In addition, since the fluorescence generated in the regions a and b is linearly polarized light that is shifted by 45 ° from the polarization direction of the linear polarizing filter, a loss occurs in the linear polarizing filter, which is darker than the region c and brighter than the region d. In other words, the brightness appears to be intermediate between the areas c and d. As a result, a mosaic pattern as shown in FIG. 4D is observed. The pattern shown in FIG. 4D is a latent image that is not visible when ultraviolet light is not irradiated and is visible when ultraviolet light is irradiated.

  FIG. 4E shows identification through a linearly polarizing filter that selectively transmits linearly polarized light in a direction matching the orientation direction of the region c in FIG. 3 in an environment irradiated with non-polarized ultraviolet light. The case where the medium 106 is observed is shown. In this case, in the region c, linearly polarized fluorescence is generated in a direction parallel to the polarization direction of the linear polarization filter to be used. Since this fluorescence is transmitted through the linear polarization filter, the area c appears bright. In the region d, linearly polarized fluorescence is generated in a direction orthogonal to the polarization direction of the linear polarization filter to be used. Since this fluorescence is blocked by the linear polarization filter, the region d appears black. In addition, since the fluorescence generated in the regions a and b is linearly polarized light deviated from the polarization direction of the linear polarization filter by 45 °, a loss occurs in the linear polarization filter, which is darker than the region d and brighter than the region c. That is, it looks like a lightness intermediate between the areas d and c. As a result, a mosaic pattern as shown in FIG. 4E is observed. The pattern shown in FIG. 4E is a latent image that is not visible when ultraviolet light is not irradiated and is visible when ultraviolet light is irradiated.

In the case of FIGS. 4B and 4C, it is difficult to distinguish the region c and the region d in FIG. The angle difference between the polarization direction of the linear polarization filter and the orientation direction of the region c is Δθ ₁ , and the angle difference between the polarization direction of the linear polarization filter and the orientation direction of the region d is Δθ ₂ . This is because Δθ ₁ = Δθ ₂ and the amount of light reaching the observer from the regions c and d is the same. 4D and 4E, it is difficult to distinguish the region a and the region b in FIG. This is also due to the same reason as described above.

(Superiority)
As described above, the identification medium 106 includes the fluorescent dichroic dye layer 102. The layer 102 of fluorescent dichroic dye has an embossed surface 102a having an arrangement along a specific direction for performing hologram display. The molecules of the fluorescent dichroic dye constituting the fluorescent dichroic dye layer 102 are oriented along the specific direction. Furthermore, the orientation state of the layer 102 of the fluorescent dichroic dye includes the first region oriented in the first direction (for example, the region c in FIG. 3) and the second region oriented in the second direction ( For example, it has a region a) in FIG. 3 and a third region (for example, region b in FIG. 3) oriented in the third direction, and the first to third directions are different from each other. The angle formed by the first direction and the second direction and the angle formed by the first direction and the third direction are set to be the same (in this case, 45 °). The uneven structure of the embossed surface 102a is filled with a transparent protective layer 105 having a refractive index close to that of the layer 102 of the fluorescent dichroic dye.

  According to this configuration, the pattern of the identification medium 106 cannot be observed (or is difficult to observe) in a state where it is exposed to visible light, but is irradiated with non-polarized ultraviolet light and the identification medium 106 is observed through the linear polarization filter. Then, the patterns of the latent images shown in FIGS. 4B to 4E are observed according to the relative angular positions of the linear polarization filter and the identification medium 106. Moreover, this latent image shows a dramatic change in appearance as shown in FIGS.

  The optical function of FIG. 4 can be similarly obtained even when ultraviolet light is irradiated from one surface (upper surface or lower surface) of the identification medium 106 and observed from the other surface (lower surface or upper surface). Also, when irradiating linearly polarized ultraviolet light and observing fluorescence at that time, a similar optical function can be obtained by changing the polarization direction of the irradiated ultraviolet light.

  It should be noted that the degree of definition of the pattern constituted by the combination of the rectangular hologram areas shown in FIG. 4 is not particularly limited. For example, if the rectangular areas a to d serving as pixels illustrated in FIG. 3 are reduced (for example, a size of several tens of μm square), a finer image can be formed. In addition, as a mosaic pattern illustrated in FIG. 4, the arrangement of rectangular regions can be determined so that stars and characters are displayed.

Second Embodiment (Structure and Manufacturing Process)
FIG. 5 shows an identification medium 206 of the embodiment. Hereinafter, the manufacturing process of the identification medium 206 will be described. The parts common to the first embodiment are the same as those in the first embodiment.

  First, the support film 201 is prepared. The support film 201 is selected from a material that is light transmissive and does not disturb the polarization characteristics of transmitted light. When the support film 201 is prepared, the hologram forming layer 202 is formed thereon with a thickness of about 0.5 μm to 5 μm (FIG. 5A). The hologram forming layer 202 is selected from a material that is light transmissive and does not disturb the polarization characteristics of transmitted light. As the hologram forming layer 202, for example, polyester-based, acrylic-based, urethane-based resin, or the like is used.

  After obtaining the state shown in FIG. 5A, an embossed surface (diffraction grating surface) 202a is formed by embossing a hologram mold on the exposed surface of the hologram forming layer 202 (FIG. 5B). The formation pattern of the embossed surface 202a viewed from the front is the same as that of the first embodiment shown in FIG.

  When the state shown in FIG. 5B is obtained, a layer of zinc sulfide, titanium dioxide or the like having a refractive index of 2 or more is formed on the embossed surface 202a as the transparent vapor deposition layer 203 with a thickness of about 0.01 μm to 0.1 μm. (FIG. 5C). Since the transparent vapor-deposited layer 203 is thin, the transparent vapor-deposited layer 203 has a cross-sectional shape along the concavo-convex structure of the embossed surface 202a of the hologram forming layer 202 as shown in the figure, and its surface becomes an embossed surface 203a similar to the embossed surface 202a. .

  When the state shown in FIG. 5C is obtained, a fluorescent dichroic dye layer 204 is formed on the transparent vapor-deposited layer 203 (FIG. 5D), and is further adhered to the exposed surface of the fluorescent dichroic dye layer 204. The layer 205 is formed (FIG. 5E). At this time, the fluorescent dichroic dye layer 204 is oriented following the orientation state of the embossed surface 203a (the orientation state of FIG. 3A). In FIGS. 5D and 5E, the images are displayed in an inverted state.

(Optical function)
The identification function obtained when the identification medium 206 is irradiated with ultraviolet light is the same as that of the identification medium 106 of FIG. 1 described in the first embodiment. That is, the optical function obtained when observing through the linearly polarized light filter in the state irradiated with non-polarized ultraviolet light and the optical function obtained when irradiating with linearly polarized ultraviolet light are the same in the identification media 206 and 106. is there.

  When the identification medium 206 is observed without being irradiated with ultraviolet light and exposed to visible light, the transparent deposition layer 203 causes hologram images resulting from the embossed surfaces 202a and 203a (in this case, the hologram pattern shown in FIG. 3A). ) Can be observed. However, in this state, since ultraviolet light is not irradiated, fluorescence of the fluorescent dichroic dye, that is, linearly polarized fluorescence does not occur. The change in the design as shown in () cannot be observed. Thus, it is possible to confirm the hologram image with visible light and to confirm the change in brightness of the hologram image under ultraviolet light irradiation.

Third Embodiment FIG. 6 shows a modification of FIG. In this case, first, a peeling layer 212 and a protective layer 213 are laminated on a base substrate 211 such as a PET film. The protective layer 213 is selected from a material that is light transmissive and does not disturb the state of polarization of transmitted light. Next, the hologram forming layer 202 is formed to obtain the state shown in FIG. Next, an embossed surface 202a is formed on the surface of the hologram forming layer 202 by embossing (FIG. 6B). Further, a transparent vapor deposition layer 203 is formed. At this time, an embossed surface 203a that follows the formation of the embossed surface 202a is formed on the surface of the transparent vapor deposition layer 203 (FIG. 6C).

  Next, a layer 204 of fluorescent dichroic dye is formed. At this time, the fluorescent dichroic dye layer 204 is oriented following the orientation state of the embossed surface 203a (the orientation state of FIG. 3A). Then, a hot melt layer (a layer that develops an adhesive force by heating) 207 is formed on the exposed surface of the layer 204 of the fluorescent dichroic dye, and an identification medium 214 shown in FIG. 6D is obtained. By hot stamping this on the adherend, the peeling layer 212 and the base substrate 211 are removed from the protective layer 213, and a thin transfer type identification medium 214 (FIG. 6E) without the base substrate is obtained. Note that FIG. 6E shows a state in which the top and bottom are reversed. The optical function of the identification medium 214 is the same as that of the identification medium 206 shown in FIG. Further, if the transparent vapor deposition layer 203 is not provided, the identification medium 106 shown in FIG.

Fourth Embodiment FIG. 7 shows an identification medium 220. The identification medium 220 has a structure in which an adhesive layer 221, a support film 222, a hologram forming layer 223, an aluminum vapor deposition layer (light reflecting layer) 224, a fluorescent dichroic dye layer 225, and a protective layer 226 are laminated. . The identification medium 220 is a reflection type, and an identification function can be obtained only when observation is performed from the protective layer 226 side. The identification function is the same as in the third and fourth embodiments.

Fifth Embodiment FIG. 8 shows a modification of FIG. FIG. 8 shows the identification medium 230. The identification medium 230 is produced as follows. First, the cholesteric liquid crystal 208 is formed on the support film 201 with a thickness of about 0.5 to 5 μm. As the support film, a material that does not disturb the polarization state of the transmitted light is selected. The cholesteric liquid crystal layer 208 is set to have a characteristic of selectively reflecting red right circularly polarized light as viewed from the front, for example. The turning direction of the circularly polarized light that is selectively reflected may be left circularly polarized light. The wavelength for selective reflection may be another value (for example, green). Then, an embossed surface (diffraction grating surface) 208a is formed by embossing a hologram type on the exposed surface of the cholesteric liquid crystal layer 208. The embossed surface 208a is formed, for example, in the pattern shown in FIG.

  Next, a fluorescent dichroic dye layer 204 is formed on the embossed surface 208a. At this time, the interface of the fluorescent dichroic dye layer 204 in contact with the cholesteric liquid crystal layer 208 has the same surface structure as the embossed surface 208a, and the fluorescent dichroic dye 204 is configured in a direction along the groove structure of the embossed surface 208a. The molecules of the fluorescent dichroic dye are oriented. After forming the fluorescent dichroic dye layer 204, an adhesive layer 205 is formed on the exposed surface. Thus, the structure shown in FIG. 8 is obtained.

  The identification medium 230 is observed from the support film 201 side. First, when the identification medium 230 is observed in an environment that is exposed to visible light, reflected light from the cholesteric liquid crystal layer 208 is observed, so that a red hologram image caused by the embossed surface 208a can be confirmed. Here, the observed hologram image is a mosaic pattern image shown in FIG. When tilted and observed further, a color shift in which reflected light changes to the short wavelength side is observed. When the identification medium 230 is observed through a right circularly polarizing filter that selectively transmits right circularly polarized light in an environment where visible light is applied, a hologram image can be observed as in visual observation. At this time, since the right circularly polarized light selectively reflected from the cholesteric liquid crystal layer 208 is preferentially observed, the red hologram image can be observed in a clearer state than when the right circular polarizing filter is not used. On the other hand, when the identification medium 230 is observed through a left circular polarization filter that selectively transmits left circular polarization in an environment where visible light is applied, the right circular polarization is cut by the left circular polarization filter, so that a hologram image is obtained. Disappears.

  Further, under the environment irradiated with ultraviolet light, fluorescence of the fluorescent dichroic dye layer 204 is generated. This fluorescence is generated in the polarization pattern of FIG. Here, when the identification medium 230 is viewed directly, the difference in polarization cannot be visually recognized, and the pattern of FIG. 3 (that is, the patterns of FIGS. 4B to 4C) cannot be observed. On the other hand, when observing through a linear polarizing filter, a change in design as shown in FIG. 4 is observed depending on the direction of the linear polarizing filter, as in the case of the first embodiment. Thus, the identification medium 230 can be observed by three types of methods: (1) visual observation, (2) visual observation + circularly polarizing filter, and (3) ultraviolet light + linearly polarizing filter.

Sixth Embodiment For example, in the second embodiment, the embossed structure pattern may be a combination of two patterns having the same groove direction and different groove pitches as shown in FIG. FIG. 9 shows a rectangular first pattern and a circular second pattern having the same extending direction of the grooves. Here, the pitch of the grooves of the first pattern is set to be relatively large, and the pitch of the grooves of the second pattern is set to be relatively narrow (that is, finer). In this case, an image having a round shape in a rectangle is observed when the identification medium is tilted from the front due to a difference in the pitch of the embossed pattern in an environment exposed to visible light. That is, the rectangular first pattern and the round second pattern are visually recognized in a distinguishable state.

  On the other hand, under the environment irradiated with ultraviolet light, the fluorescent dichroic dye is oriented in the same groove direction, so that the rectangular shape and the inner circular shape emit light similarly. Accordingly, the round second pattern is buried in the rectangular first pattern and is difficult to observe, and it is difficult to distinguish between the rectangular first pattern and the round second pattern. Thus, by combining patterns having the same groove direction and different pitches, it is possible to realize a form in which the hologram image observed with visible light and the pattern observed under ultraviolet light irradiation are different.

  This embodiment can be applied to embodiments other than the second embodiment. Further, a configuration in which one or more of the rectangular patterns (regions a to c) in FIG. 3 are replaced with the patterns shown in FIG. 9 is also possible.

(Other)
In the above example, the case of using a layer of a fluorescent dichroic dye that generates fluorescence when irradiated with ultraviolet light has been described. However, fluorescence dichroism that generates fluorescence when irradiated with light other than ultraviolet light such as infrared light. It is also possible to use a dye layer.

  The present invention can be used in a technique for identifying authenticity.

  DESCRIPTION OF SYMBOLS 101 ... Diffraction grating, 101a ... Embossed surface (diffraction grating surface), 102 ... Layer of fluorescent dichroic dye, 103 ... Support film, 104 ... Adhesive layer, 105 ... Protective layer, 106 ... Identification medium, 201 ... Support film, 202 ... Hologram forming layer, 202a ... Embossed surface, 203a ... Embossed surface, 203 ... Transparent vapor deposition layer, 204 ... Layer of fluorescent dichroic dye, 205 ... Adhesive layer, 206 ... Identification medium, 207 ... Hot melt layer, 208 ... Cholesteric liquid crystal layer, 208a ... embossed surface, 220 ... identification medium, 221 ... adhesive layer, 222 ... support film, 223 ... hologram forming layer, 224 ... aluminum vapor deposition layer, 225 ... fluorescent dichroic dye layer, 226 ... protective layer 230 ... Identification medium.

Claims (12)

It comprises a layer of polarized fluorescent light emitting material provided with an embossed structure for holographic display,
The embossed structure has an arrangement along a specific direction;
The layer of the polarized fluorescent light emitting material is oriented in a direction along the specific direction,
The identification medium characterized in that the layer of the polarized fluorescent light emitting material oriented in the specific direction has a plurality of regions having different orientation states. The plurality of regions include a first region oriented in a first direction, a second region oriented in a second direction, and a third region oriented in a third direction,
The first direction to the third direction are different from each other,
The identification medium according to claim 1, wherein an angle formed by the first direction and the second direction and an angle formed by the first direction and the third direction are the same.   The identification according to claim 2, wherein an angle formed by the first direction and the second direction and an angle formed by the first direction and the third direction are both 45 °. Medium. The layer of polarized fluorescent light-emitting material has a fourth region oriented in a fourth direction different from the first to third directions,
The identification medium according to claim 3, wherein an angle formed by the fourth direction and the first direction is 90 °.   5. The polarized fluorescent luminescent material is a fluorescent dichroic dye that fluoresces when irradiated with ultraviolet light or a liquid crystal compound that fluoresces when irradiated with ultraviolet light. 6. Identification medium.   The identification medium according to claim 1, wherein the plurality of regions have a plurality of regions having the same orientation direction and different orientation pitches.   The identification medium according to any one of claims 1 to 6, wherein the embossed structure of the polarized fluorescent light emitting material layer is filled with resin.   The identification medium according to claim 7, wherein a ratio of a refractive index of the layer of the polarized fluorescent light-emitting material and a refractive index of the resin is in a range of 0.8 to 1.2.   9. The identification medium according to claim 8, wherein a refractive index of the layer of the polarized fluorescent light emitting material is an average value of a refractive index in the oriented direction and a refractive index in a direction orthogonal to the oriented direction.   A cholesteric liquid crystal layer is provided in contact with the embossed surface of the layer of the polarized fluorescent light emitting material, and the embossed surface is formed by using an embossed structure for hologram formation formed on the surface of the cholesteric liquid crystal layer. The identification medium according to any one of claims 1 to 9, wherein the identification medium is formed.   The identification method according to claim 1, wherein the identification medium is observed through a linear polarization filter in a state where non-polarized ultraviolet light is irradiated to the identification medium according to claim 1. .   An identification method according to claim 1, wherein the identification medium is observed in a state where linearly polarized ultraviolet light is irradiated to the identification medium according to claim 1.

Images