JP2011102843A - Identification medium and identification method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an identification medium in which a stereoscopic image is used, fabrication is difficult and an identifiability is high. <P>SOLUTION: On a cholesteric liquid crystal layer 103, a pattern 104a of a hologram forming layer constituting a hologram for a right eye and a pattern 104b of a hologram forming layer constituting a hologram for a left eye are provided in a stripe shape and are arranged so that reflection light from the pattern 104a may pass through a pattern 101a of a λ/2 plate and reflection light from the pattern 104b may not pass through the pattern 101b of the λ/2 plate. When the identification medium 100 is observed while setting a right circular polarization filter before the right eye and a left circular polarization filter before the left eye, the pattern 104a can be seen by the right eye and the pattern 104b can be seen by the left eye and consequently a stereoscopic image can be observed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an identification medium and an identification method thereof.

  Cited Document 1 describes an identification medium that displays a stereoscopic image using a hologram. Cited Document 2 describes an identification medium in which cholesteric liquid crystal layers reflecting different circularly polarized light are laminated on the left and right, and the patterns of the respective cholesteric liquid crystal layers are for the left eye and for the right eye.

JP-A-5-2148 JP 2000-255200 A

  In the configuration described in the cited document 1, a parallax image using a hologram is visually recognized separately by the left and right eyes, thereby causing a stereoscopic image to be observed. In the cited document 1, the material of the display is not mentioned, and the wavelength diffracted by the diffraction grating is not limited. Therefore, all wavelengths of natural light that are not specific wavelengths are diffracted by the diffraction grating and contribute to the generation of the hologram. In this case, hologram images having a large number of wavelengths are generated, and they appear to overlap with each other, resulting in blurring or blurring of the hologram image. For this reason, the sharpness of the observed stereoscopic image tends to be impaired.

  In addition, holograms formed by embossing a material that does not limit the wavelength of reflected light, such as a typical embossed hologram with aluminum deposited on the surface of the diffraction grating, can easily be embossed. Even if there is no original mold, a replica is easy to manufacture. That is, it is easy to manufacture a counterfeit product and the anti-counterfeiting property is low.

  In the configuration described in the cited document 2, since the image for the left eye and the image for the right eye are each constituted by the pattern of the cholesteric liquid crystal layer, it is clear from the property of the cholesteric liquid crystal that reflects light of a specific center wavelength. It is easy to obtain an image. However, the image formed by the pattern of the cholesteric liquid crystal layer is easy to duplicate, and it is easy to forge the same one. Also, an image used for identification cannot be obtained as a fine and highly distinguishable image, and must be monotonous and rough. For this reason, it is not suitable as an identification medium for authenticity determination.

  In such a background, an object of the present invention is to provide an identification medium that has a simple structure but is difficult to forge and has high identification.

  The invention described in claim 1 includes a cholesteric liquid crystal layer having a hologram layer for displaying a hologram, a first portion that is laminated on the cholesteric liquid crystal layer, and covers the cholesteric liquid crystal layer, and a second portion that does not cover And a layer functioning as a λ / 2 plate having a periodically repeated pattern, the hologram layer corresponding to the plurality of first regions corresponding to the first portion and the second portion A plurality of second regions, wherein the plurality of first regions constitutes a first hologram image, and the plurality of second regions constitutes a second hologram image. It is an identification medium.

  According to the first aspect of the present invention, the reflected light from the first region of the hologram layer formed in the cholesteric liquid crystal passes through the pattern of the layer functioning as a λ / 2 plate and is observed. Reflected light from the second region of the hologram layer formed in the cholesteric liquid crystal is observed without passing through the pattern of the layer functioning as a λ / 2 plate. The reflected light from the cholesteric liquid crystal is circularly polarized light having a specific turning direction, and the turning direction is reversed by passing through the λ / 2 plate. Therefore, the reflected light from the first region and the reflected light from the second region are circularly polarized light whose turning method is reversed. Therefore, the first image and the second image can be separated and observed by the circular polarization filter, and identification using this can be performed.

  Holograms obtained by hologram processing formed on a cholesteric liquid crystal layer are not easy to duplicate using a photosensitive material because cholesteric liquid crystals selectively reflect a specific center wavelength. For this reason, high forgery resistance is obtained.

  In addition, the image formed by the hologram can be fine and precise. In addition, as described above, light of a specific center wavelength is reflected from the cholesteric liquid crystal, so that interference of extra wavelengths is small. A clear hologram image is observed. For this reason, high discrimination can be obtained. Note that the cholesteric liquid crystal layer and the layer functioning as the λ / 2 plate need only overlap with each other when viewed from the direction of observation, and may or may not be in contact with each other.

  According to a second aspect of the present invention, in the first aspect, the first hologram image is a hologram image for one eye of the left and right eyes, and the second hologram image is the left and right eyes. The hologram image for the other eye is characterized in that a stereoscopic image is constituted by the first hologram image and the second hologram image.

  According to the second aspect of the present invention, when the identification medium of the present invention is observed through the optical filter so that the left and right eyes can selectively see the circularly polarized light in the reverse rotation direction, the first region is observed with one eye. The reflected light from the second region is selectively seen, and the reflected light from the second region is selectively seen by the other eye. Here, the reflected light constituting the hologram image for one eye is obtained from the first area, and the reflected light constituting the hologram image for the other eye is obtained from the second area. The hologram image for the right eye is selectively seen, and the hologram image for the left eye is selectively seen with the left eye. That is, the right-eye hologram image constituting the stereoscopic image is visually recognized by the right eye, and the left-eye hologram image constituting the stereoscopic image is visually recognized by the left eye. As a result, a stereoscopic image is recognized.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein a plurality of the first hologram image and the second hologram image are prepared in accordance with an angle at which the identification medium is viewed. It is characterized by.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the first region and the second region form a stripe pattern or a checkered pattern. It is characterized by.

  The invention according to claim 5 is the invention according to any one of claims 2 to 4, wherein the first hologram image is formed by one of the left and right eyes, and the first hologram A dummy hologram is formed in the cholesteric liquid crystal layer that reflects circularly polarized light in the same swiveling direction as the reflected light from the hologram image to the outside of the identification medium and forms an image on the other side of the left and right eyes without forming an image on the other side. It is characterized by being.

  The invention according to claim 6 is the invention according to any one of claims 2 to 4, wherein the first hologram image is formed by one of the left and right eyes, and further, the first hologram A circular hologram polarized in the direction opposite to the reflected light from the hologram image is reflected to the outside of the identification medium, and a dummy hologram is formed on the cholesteric liquid crystal layer while forming an image on one of the left and right eyes and not on the other. It is characterized by being.

  The invention according to claim 7 is an optical filter that transmits the identification medium according to any one of claims 2 to 6 through the first turning direction and blocks the second turning direction opposite to the turning direction. And the other eye of the left and right eyes through an optical filter that passes through the second turning direction and blocks the first turning direction. An identification medium identifying method characterized by observing.

  According to the first aspect of the present invention, it is possible to provide an identification medium that has a simple structure but is difficult to forge and has high identification.

  According to invention of Claim 2, the identification medium which can utilize a stereo image for identification is provided.

  According to the third aspect of the present invention, there is provided an identification medium in which an image changes or switches depending on the viewing angle.

  According to invention of Claim 4, a 1st area | region and a 2nd area | region are comprised by the pattern arrangement | sequence of stripe shape or checkered pattern.

  According to the invention described in claim 5 or 6, the phenomenon that the left and right hologram images appear blurred when the identification medium is viewed without an optical filter is alleviated.

  According to the seventh aspect of the present invention, there is provided an identification medium identification method capable of identifying a stereoscopic image.

It is a conceptual diagram which shows the cross-sectional structure of the identification medium of embodiment. It is a conceptual diagram which shows the mechanism which observes the identification medium of embodiment. It is a conceptual diagram which shows how the identification medium of embodiment is visible. It is a conceptual diagram which shows the cross-sectional structure of the identification medium of embodiment. It is a conceptual diagram which shows an example of the structure of the pattern of (lambda) / 2 board of embodiment. It is a conceptual diagram which shows the cross-sectional structure of the identification medium of embodiment. It is a conceptual diagram which shows the cross-sectional structure of the identification medium of embodiment. It is a conceptual diagram which shows how the identification medium of embodiment is visible.

(Configuration of identification medium)
FIG. 1 shows an identification medium 100 using the invention. The identification medium 100 has an embossed structure formed on a pattern layer 101 of a λ / 2 plate (half-wave plate), a transparent substrate 102, a cholesteric liquid crystal layer 103, and a cholesteric liquid crystal layer 103 from the observation side. The hologram forming layer (hologram interference layer) 104 and the adhesive layer 105 are laminated.

  The pattern layer 101 of the λ / 2 plate is a resin layer pattern that functions as a λ / 2 plate formed using the transparent substrate 102 as a base material. The λ / 2 plate is made of a material having birefringence. When linearly polarized light is incident at an angle of 45 ° with respect to the slow axis, outgoing light whose polarization direction is rotated by 90 ° is obtained. When circularly polarized light is incident, the turning direction is reversed and the circularly polarized light in the reverse turning direction is emitted.

  The pattern layer 101 of the λ / 2 plate is a stripe pattern in which a plurality of 300 μm-wide linear patterns 101a are arranged with an interval of 300 μm. The interval between the patterns is preferably a value selected from a range of about 10 μm to 1 mm. The pattern layer 101 of the λ / 2 plate can be used as long as it is a material that functions as a λ / 2 plate due to birefringence.

  The transparent substrate 102 is made of a film of a material (for example, TAC (triacetyl cellulose)) that transmits light used for identification and does not disturb the polarization characteristics of the transmitted light. The cholesteric liquid crystal layer 103 is a cholesteric liquid crystal layer that reflects circularly polarized light having a green center wavelength in the left-turning direction. The turning direction of the reflected light of the cholesteric liquid crystal layer 103 may be a right turning direction, and the center wavelength of the reflected light may be a wavelength of another color.

  The hologram forming layer 104 is configured by an uneven structure (embossed structure) formed by pressing a hologram type against the cholesteric liquid crystal layer 103. The hologram forming layer 104 interferes with circularly polarized light reflected upward from the cholesteric liquid crystal layer 103 to form a hologram image.

  The hologram forming layer 104 includes a plurality of patterns 104a and 104b in which linear patterns are alternately arranged in a stripe pattern. The pattern 104a constitutes the right-eye image of the stereoscopic image, and the pattern 104b constitutes the left-eye image of the stereoscopic image. That is, the hologram patterns 104a and 104b are formed so that a stereoscopic image can be recognized by visually recognizing the pattern 104a with the right eye without being viewed with the left eye and with the left eye without recognizing the pattern 104b with the right eye. .

  Further, the positional relationship between the patterns is set so that the pattern 104a is located at a position overlapping the pattern 101a and the pattern 104b is located at a position where the pattern 101a does not exist. That is, when the identification medium 100 is viewed from the pattern layer 101 side of the λ / 2 plate, there is a hologram pattern 104a at a position hidden by the linear pattern 101a, and the hologram pattern 104a from the gap portion of the linear pattern 101a. The positional relationship is such that the pattern 104b can be seen.

  The adhesive layer 105 is made of an adhesive material mixed with black or dark pigment or dye, and has a function of attaching the identification medium 100 to an article to be identified. The pressure-sensitive adhesive layer may be composed of an adhesive instead of a pressure-sensitive adhesive. Moreover, you may have a light transmittance. In the case of having optical transparency, the surface of the attached object can be seen through the identification medium 100.

  In FIG. 1, the pattern layer 101 of the λ / 2 plate is exposed. However, the protective layer may be provided by covering the pattern layer 101 with a light-transmitting material film that does not disturb the polarization characteristics of light. . In addition, release paper is affixed to the exposed surface of the adhesive layer 105 at a stage before being affixed to the article, but this is not shown in the drawing. In the configuration shown in FIG. 1, the image for the left eye may be configured by the pattern 104a, and the image for the right eye may be configured by the pattern 104b.

(Identification medium manufacturing method)
Hereinafter, an example of a method for manufacturing the identification medium 100 will be described. First, a transparent substrate 102 is prepared, and a λ / 2 plate pattern layer 101 is formed on one surface thereof. The λ / 2 plate pattern layer 101 is formed by a method of transferring a light-transmitting resin film functioning as a λ / 2 plate formed in a stripe shape. As a method of forming the pattern layer 101 of the λ / 2 plate, a method by printing a liquid crystal material, a method of drawing light by applying light to the liquid crystal material, and partially imparting birefringence can be used. . The pattern layer 101 of the λ / 2 plate may be configured by transferring a film having a phase difference other than the liquid crystal.

  After the λ / 2 plate pattern layer 101 is formed on the transparent substrate 102, a cholesteric liquid crystal layer 103 is formed on the opposite surface. The surface of the transparent substrate 102 that is in contact with the cholesteric liquid crystal layer 103 is previously subjected to an alignment treatment, and the cholesteric liquid crystal layer 103 is grown thereon. When the cholesteric liquid crystal layer 103 is formed, a hologram mold is pressed against the exposed surface to form the hologram forming layer 104. Next, an adhesive layer 105 is formed to obtain the identification medium 100 shown in FIG.

(Identification function)
FIG. 2 is a conceptual diagram showing a state of observation through the identification medium 100 through the optical filter. FIG. 3 is a conceptual diagram showing how the identification medium 100 is seen. In FIG. 2, the identification medium 100 is observed with the right eye 201 through the right circular polarization filter 203 that transmits right-handed circularly polarized light and blocks left-handed circularly polarized light, and at the same time, transmits left-turned circularly polarized light, A state is shown in which the left eye 202 observes the identification medium 100 through a left circular polarization filter 204 that blocks right-handed circularly polarized light.

  In the state shown in FIG. 2, the reflected light from the pattern 104 a of the hologram forming layer 104 is left-turning circularly polarized light, but when passing through the linear pattern 101 a of the λ / 2λ plate 101, right-turning circularly polarized light. Thus, the light passes through the right circular polarizing filter 203 and does not pass through the left circular polarizing filter 204, and is selectively visible only with the right eye 201.

  The reflected light from the pattern 104b of the hologram forming layer 104 is left-handed circularly polarized light and passes through the gap between the linear patterns 101a of the λ / 2λ plate 101. Although it is blocked by the polarizing filter 203 and is not visually recognized by the right eye 201, it passes through the left circular polarizing filter 204, so that it is selectively visually recognized only by the left eye.

  Thus, the right eye 201 selectively recognizes the pattern 104a, and the left eye 202 selectively recognizes the pattern 104b. Here, the pattern 104a constitutes the right-eye image of the stereoscopic image, and the pattern 104b constitutes the left-eye image of the stereoscopic image. Therefore, the right eye 201 visually recognizes the right-eye image, and the left eye 202 The image for the left eye is visually recognized at the same time. As a result, a stereoscopic image is synthesized and recognized at the visual center.

  FIG. 3A shows how the identification medium 100 looks directly without using an optical filter. In this example, the case where the letter “N” is composed of the hologram patterns 104a and 104b (see FIG. 1) is shown. In FIG. 3A, since the hologram patterns 104a and 104b can be seen simultaneously by the left and right eyes, the images for the left and right eyes that are shifted by the amount of parallax can be seen simultaneously by the left and right eyes, and “N” that is double-blurred I can see the characters.

  In FIG. 3B, the identification medium 100 was observed with the right circular polarizing filter positioned in front of the right eye and the left circular polarizing filter positioned in front of the left eye, as shown in FIG. The appearance of the case is shown. In this case, as described with reference to FIG. 2, the hologram pattern 104a is selectively visually recognized by the right eye, and the hologram pattern 104b is selectively visually recognized by the left eye. Then, the hologram image constituted by the pattern 104a and the hologram image constituted by the pattern 104b are synthesized at the visual center, and the three-dimensional image 300 of the letter “N” is recognized. The illustrated display is an example, and may be a number or other characters. Further, it may be a pattern imitating an article or various designs.

(Superiority)
Holograms using reflected light from cholesteric liquid crystals have the advantage of being difficult to counterfeit. In other words, emboss hologram processing with a reflective layer such as aluminum vapor deposition, which is formed on an ordinary light-transmitting material, is performed by exposing the photosensitive material with ultraviolet laser light or the like while the photosensitive material is in close contact therewith. By performing the above, it is possible to copy the embossed structure (uneven structure) constituting the hologram processing relatively easily. On the other hand, the cholesteric liquid crystal layer has a property of selectively reflecting light having a specific center wavelength. Therefore, the above-described duplication technique requires a photosensitive material having a photosensitive characteristic that matches the reflection spectral characteristic. However, it is difficult to prepare a photosensitive material having a photosensitive characteristic that matches the reflective characteristic of the cholesteric liquid crystal layer. For this reason, it is difficult to reproduce the hologram processing provided in the cholesteric liquid crystal layer unless the original is obtained.

  In the case of a stereoscopic image, since the parallax between the left and right eyes is used, a subtle error affects the reproducibility of the stereoscopic image. For this reason, it becomes more difficult to reproduce the identification medium shown in the present embodiment by reverse engineering.

  Further, as described above, the cholesteric liquid crystal layer reflects reflected light centered on a specific wavelength (in other words, reflects reflected light of a specific color and transmits other color components). For this reason, a clear interference image (hologram image) can be observed. Embossed holograms that are made of ordinary light-transmitting material and have a reflective layer such as aluminum vapor deposition diffract the light of all wavelengths of natural light at different angles, so you can also visually recognize interference light that you do not want to recognize. Will be. This causes blurring and blurring of the image. When the present invention is used, the above-described interference with an unnecessary wavelength can be suppressed due to the optical characteristic of the cholesteric liquid crystal layer that reflects the light with the specific center wavelength described above. For this reason, it is possible to obtain a clear three-dimensional image without blurring or blurring. In addition, an image formed using a hologram has an advantage that a fine fine portion can be reproduced. For these reasons, high discrimination can be obtained in an identification medium using a stereoscopic image.

(Other configuration 1)
FIG. 4 is a conceptual diagram showing an identification medium according to another embodiment. FIG. 4 shows an identification medium 400. In the identification medium 400, the same reference numerals as those of the identification medium 100 in FIG. 1 are the same as those described in relation to FIG.

  The identification medium 400 differs from the identification medium 100 (see FIG. 1) in the position of the hologram forming layer. In the identification medium 400, the hologram forming layer 106 is formed on the transparent substrate 102 side of the cholesteric liquid crystal layer 103. In this example, a concavo-convex structure having a hologram type is formed on the surface of the transparent substrate 102 on the side in contact with the cholesteric liquid crystal layer 103. When the cholesteric liquid crystal layer 103 is formed on the surface, the cholesteric liquid crystal layer 103 is imitated. An uneven structure is formed at the interface of the liquid crystal layer 103, which functions as a hologram forming layer. Note that since the concavo-convex structure that is a hologram type and the concavo-convex structure subjected to the alignment treatment have different dimensions, they can be simultaneously formed on the same surface of the transparent substrate 102.

  On the hologram forming layer 106, a hologram pattern 106a for the right eye and a hologram pattern 106b for the left eye are formed. This is the same as the case of reference numerals 104a and 104b in FIG.

(Other configuration 2)
In the example of FIG. 1 and FIG. 4, the image for the right eye and the image for the left eye are formed by a linear pattern alternately arranged (stripe arrangement), but a checkered pattern in which rectangular dot patterns are alternately arranged ( It is also possible to adopt a check pattern) pattern arrangement. FIG. 5 is a conceptual diagram showing another example of the pattern arrangement constituting the left and right images.

  FIG. 5 shows a state in which the identification medium 500 is viewed from a direction perpendicular to the surface. The identification medium 500 has the same cross-sectional structure as the identification medium 100 in FIG. Here, reference numeral 501 is an area where a pattern of λ / 2 plate exists, and reference numeral 502 is an area where a λ / 2 plate does not exist. In this case, the area of the hologram layer constituting the hologram for the right eye is arranged under the area of the reference numeral 501, and the area of the hologram layer constituting the hologram for the left eye is arranged under the area of the reference numeral 502. .

  When the identification medium 500 is observed in the same manner as in the state shown in FIG. 2, the image for the right eye composed of the pattern 501 arranged in a checkered pattern is selectively observed with the right eye, and the pattern arranged in the checkered pattern. The image for the left eye constituted by 502 is selectively observed with the left eye. Then, these two images are synthesized at the visual center, so that a stereoscopic image is recognized.

(Other configuration 3)
FIG. 6 shows an identification medium 600 according to the embodiment. The identification medium 600 has a structure in which a surface protective layer 601, a λ / 2 plate pattern layer 602, a cholesteric liquid crystal layer 603, a hologram forming layer 604, a substrate 605, and an adhesive layer 606 are stacked from the observation side. .

  The surface protective layer 601 is a light transmissive film that does not disturb the transmission polarization characteristics. The pattern layer 602 of the λ / 2 plate has the same pattern arrangement structure as the pattern layer 101 of the λ / 2 plate. The cholesteric liquid crystal layer 603 selectively reflects a specific center wavelength in a predetermined turning direction, like the cholesteric liquid crystal layer 103. The hologram forming layer 604 is an embossed pattern that forms a hologram embossed by the cholesteric liquid crystal layer 603, and has the same arrangement structure as the hologram forming layer 104. The substrate 605 is a light transmissive substrate. The adhesive layer 606 is a layer of an adhesive material having a black or dark color.

  Hereinafter, an example of a method for manufacturing the identification medium 600 will be described. First, the surface of the substrate 605 is provided with a concavo-convex structure for obtaining the alignment treatment and the hologram forming layer 604. Then, the cholesteric liquid crystal layer 603 is formed on the surface of the substrate 605 with the alignment treatment and the concavo-convex structure for the hologram, whereby the hologram forming layer 604 is obtained simultaneously with the cholesteric liquid crystal layer 603. Note that by adjusting the period of the concavo-convex structure of the hologram forming layer 604, it is also possible to serve as an alignment process.

  Next, a λ / 2 plate pattern layer 602 is attached to the upper surface of the cholesteric liquid crystal layer 603 by transfer. Then, the surface protective layer 601 and the adhesion layer 606 are provided, and the identification medium 600 is obtained.

(Other configuration 4)
FIG. 7 shows an identification medium 700 according to another embodiment. Similar to the identification medium 100, the identification medium 700 has an embossed structure formed on the pattern layer 101 of the λ / 2 plate, the transparent substrate 102, the cholesteric liquid crystal layer 103, and the cholesteric liquid crystal layer 103 from the observation side. The hologram forming layer (hologram interference layer) 104 and the adhesive layer 105 are laminated.

  The identification medium 700 is different in the pattern structure of the identification medium 100 and the hologram forming layer 104. Hereinafter, this point will be described. In the identification medium 700, the hologram forming layer 104 includes a stripe pattern group 10 including linear patterns 11, 12, 13, and 14. The stripe pattern group 10 is repeatedly arranged.

  In this example, the linear pattern 11 forms a hologram image for the right eye that is recognized when viewed from an angle of sight of 0 degrees. The linear pattern 12 constitutes a hologram image for the left eye that is recognized when viewed from a viewing angle of 0 degrees. The linear pattern 13 constitutes a hologram image for the right eye that is recognized when viewed from a viewing angle of 30 degrees. The linear pattern 14 constitutes a hologram image for the left eye that is recognized when viewed from a viewing angle of 30 degrees. The combination of the patterns 11 and 12 constitutes a first stereoscopic image, and the combination of the patterns 13 and 14 constitutes a second stereoscopic image different from the first stereoscopic image. The line-of-sight angle is defined as an angle formed with a direction perpendicular to the surface of the identification medium.

  According to this example, in the observation through the optical filter as shown in FIG. 2, the first stereoscopic image is recognized when the line-of-sight angle is 0 degrees, and the second stereoscopic image is recognized when the line-of-sight angle is 30 degrees. Is done. That is, by tilting the identification medium, it is possible to observe a state in which the three-dimensional image changes (or switches). By utilizing this phenomenon, a visual effect as if the stereoscopic image is rotated is obtained when the identification medium 700 is tilted. Further, when the identification medium 700 is tilted, a visual effect of switching to another stereoscopic image is obtained.

  Here, an example in which a stereoscopic image is prepared for two viewing angles has been described, but a configuration in which a stereoscopic image is prepared for more viewing angles may be employed.

(Other configuration 5)
As a method for obtaining the same visual effect of FIG. 7, there is a method in which one of the patterns 104a and 104b in the configuration shown in FIG. 1 is further separated into stripes, and a plurality of right-eye hologram images and left-eye hologram images are prepared. Can be mentioned. In this case, the pattern 104a in FIG. 1 is divided into stripes, and holograms for a plurality of angles are prepared there. Also, the pattern 104b of FIG. 1 is divided into stripes, and a plurality of angle holograms are prepared there.

(Other configuration 6)
FIG. 1 shows an example in which the first image is for the right eye, the second image is for the left eye, and the stereoscopic image can be observed. The first image is a number, and the second image is It may be an alphabetic character. In this case, when looking directly at the identification medium, numbers and alphabet letters can be seen at the same time, and when observing the identification medium through the right circular polarizing filter, only the numbers are visible and when observing the identification medium through the left circular polarizing filter Only the alphabet letters are visible. Identification is performed by using this change in appearance.

  Here, although the combination of a number and an alphabetic character was shown, the combination of a number and a design, the combination of an alphabetic character and a design, and the combination of a different design can also be employ | adopted.

(Other configuration 7)
In the embodiment in which the first stereoscopic image is used for identification, an example in which the phenomenon that the image appears to be blurred twice when viewed directly will be described below. FIG. 8 is a conceptual diagram showing how the identification medium of this embodiment looks. In FIG. 8A, an identification medium 800 is shown. The identification medium 800 has the cross-sectional structure illustrated in FIG. 1, and the cholesteric liquid crystal layer is set to selectively reflect left circularly polarized light. The cholesteric liquid crystal layer has left and right hologram images and dummy holograms described below.

  FIG. 8A shows a hologram image 801 and a dummy hologram 802 for the right eye. In FIG. 8A, the left-eye hologram image is not shown. The hologram image 801 and the dummy hologram 802 are configured in such a manner that reflected light is observed in the same manner (in FIG. 8A, the patterns are distinguished from each other) and are observed through a λ / 2 plate. It is said that.

  In a state where the hologram image 801 is visually recognized with the right eye, the dummy hologram 802 is a hologram that is not visible (difficult to see) from the right eye and is easily visible with the left eye. That is, in a state where the hologram image 801 is viewed with the right eye, the dummy hologram 802 is a hologram that does not form an image with the right eye but forms an image with the left eye.

  On the other hand, as shown in FIG. 8B, the hologram image 803 for the left eye is configured with a positional relationship slightly shifted from the hologram image 801 for the right eye in FIG. 8A. The left-eye hologram image 803 is a hologram image formed with the left eye while the hologram image 801 is being observed with the right eye, and is observed without a λ / 2 plate.

  According to this configuration, when directly observing the identification medium 800 without using the circular polarizing filter, the viewpoint is aligned with the right eye hologram 801 and the left eye is aligned with the left eye hologram 803. In this case, the right-eye hologram image 801 can be seen with the right eye, and the dummy hologram 802 can be seen with the left eye. Since the hologram image 801 and the dummy hologram 802 have the same pattern as a negative positive, the hologram image 801 can be seen together with the dummy hologram 802 by simultaneously recognizing both, so that it is difficult to distinguish the two. That is, when the identification medium 800 is viewed directly, the hologram image 801 becomes difficult to recognize. For this reason, when viewed directly, a uniform hologram image is recognized as indicated by reference numeral 804 in FIG. 8B, and the right-eye hologram image 801 is not observed (or difficult to observe).

  On the other hand, even when viewing directly, the left-eye hologram 803 is visible to the left eye, so that the left-eye hologram image 803 is visible. For this reason, when the identification medium 800 is directly viewed without passing through the optical filter, the left-eye hologram image 803 is preferentially recognized as shown in FIG.

  Next, a right circular polarizing filter that selectively transmits right-turning circularly polarized light is disposed in front of the right eye, and a left circular polarizing filter that selectively transmits left-turning circularly polarized light is disposed in front of the left eye. A case where 800 is observed will be described.

  In this case, right-turn circularly polarized light is reflected from the hologram image 801 for the right eye so as to pass through the λ / 2 plate. This is the same for the dummy hologram 802. At this time, in the state where the image from the hologram image 801 for the right eye is observed with the right eye via the right circular polarization filter, the reflected light from the dummy hologram 802 is not visually recognized (or difficult to visually recognize) by the right eye. This is because in the state where the right-eye hologram image 801 is formed with the right eye, the dummy hologram 802 is set so as not to form the image with the right eye but to form the image with the left eye. On the other hand, since the left eye sees the identification medium 800 via the left circular polarization filter, the right-handed circularly polarized reflected light from the dummy hologram 802 is blocked by the left circular polarization filter and does not reach the left eye. . That is, in this state, the dummy hologram 802 cannot be seen with the left eye.

  Accordingly, the right-eye hologram image 801 is selectively visible with the right eye, the left-eye hologram image 803 is selectively visible with the left eye, and the dummy hologram 802 is not visible with both eyes. Thereby, the three-dimensional image 805 shown in FIG. 8C is recognized. As described above, by using the dummy hologram 802 shown in the present embodiment, the phenomenon that the image is blurred when viewed directly is alleviated, and the dummy hologram is not recognized in the observation using the optical filter. An identification medium capable of observing a stereoscopic image is provided.

  As described above, in the above example, the hologram image 801 for the right eye is formed with the right eye, and circularly polarized light in the same turning direction (right turning direction) as the reflected light from the hologram image 801 is identified. A dummy hologram 802 that reflects to the outside of the medium 800 and forms an image with the left eye without forming an image with the right eye is formed in a cholesteric liquid crystal layer (corresponding to reference numeral 103 in FIG. 1). “Dummy hologram 802 that reflects circularly polarized light in the same turning direction (right turning direction) as the reflected light from hologram image 801 to the outside of the identification medium 800 and forms an image with the left eye without forming an image with the right eye. “When the identification medium 800 is observed from the outside, the reflected light from the dummy hologram 802 is circularly polarized light in the same turning direction as the reflected light from the hologram image 801, and further the reflected light from the dummy hologram 802. Means that a hologram image is formed with the left eye but not with the right eye.

  Here, a configuration has been described in which, when viewed directly, the hologram image for the right eye is made difficult to see by the dummy hologram that can be seen by the left eye, so that the image blur is suppressed, but the dummy hologram is applied to the hologram image for the left eye You can also. A dummy hologram can also be applied to the left and right hologram images simultaneously. When dummy holograms are applied to the left and right hologram images, it is difficult to see the images when viewed directly, and a right circular polarizing filter is placed in front of the right eye and a left circular polarizing filter is placed in front of the left eye. An identification medium that appears to appear is obtained.

(Other configuration 8)
As another modification of the configuration 7, the dummy hologram 802 may be observed without using the λ / 2 plate. In this case, the dummy hologram 802 and the right-eye hologram image 801 are simultaneously formed with the right eye, and the left-eye hologram image 803 is viewed with the left eye, and the dummy hologram image 802 is not formed with the left eye.

  In this case, when the identification medium 800 is viewed directly, the right-eye hologram image 801 and the right-eye hologram image 801 can be seen at the same time, and both holograms can be seen at the same time, so that the right-eye hologram image 801 is recognized as shown in FIG. It is not possible (it is difficult to recognize). Further, the left eye visually recognizes the hologram image 803 for the left eye. Furthermore, since the dummy hologram image 802 is not formed with the left eye in this state, the dummy hologram 802 cannot be seen with the left eye (it is difficult to see).

  On the other hand, when the identification medium 800 is observed with the right circular polarizing filter disposed in front of the right eye and the left circular polarizing filter disposed in front of the left eye, the reflected light from the dummy hologram 802 does not transmit the λ / 2 wavelength. Therefore, it is left-handed circularly polarized light, does not reach the right eye, and is not visible (or difficult to see) with the right eye. Further, in a state where the hologram image 803 is formed with the left eye, the dummy hologram 802 is not formed with the left eye, and therefore the dummy hologram 802 is not visible (or difficult to see) with the left eye. On the other hand, the right-eye hologram image is selectively visually recognized by the right eye, and the left-eye hologram image is selectively visually recognized by the left eye.

  Also in this case, there is provided an identification medium in which a phenomenon that an image is blurred when viewed directly is alleviated, and in observation using an optical filter, a stereoscopic image can be observed without recognizing a dummy hologram. Is done.

  As described above, in the above example, the right-eye hologram image 801 is formed with the right eye, and further, circularly polarized light in the direction of rotation opposite to the reflected light from the right-eye hologram image 801 is applied to the identification medium 800. A dummy hologram 802 is formed in the cholesteric liquid crystal layer (corresponding to reference numeral 103 in FIG. 1) that reflects to the outside and forms an image with the right eye but not with the left eye. Note that “a dummy hologram 802 that reflects circularly polarized light in a direction opposite to the reflected light from the hologram image 801 for the right eye to the outside of the identification medium 800 and forms an image with the right eye and does not form an image with the left eye”. When the identification medium 800 is observed from the outside, the reflected light from the dummy hologram 802 is circularly polarized light in the direction opposite to the reflected light from the hologram image 801, and the reflected light from the dummy hologram 802 is the right eye. This means that a holographic image is formed with the left eye but not with the left eye.

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

  DESCRIPTION OF SYMBOLS 100 ... Identification medium, 101 ... (lambda) / 2 board, 101a ... Linear pattern comprised by (lambda) / 2 board, 102 ... Transparent substrate, 103 ... Cholesteric liquid crystal layer, 104 ... Hologram formation layer, 104a ... Hologram for right eye Formation layer pattern, 104b ... Left eye hologram formation layer pattern, 105 ... Adhesive layer, 201 ... Right eye, 202 ... Left eye, 203 ... Right circular polarization filter that selectively transmits right-turn circularly polarized light, 204 ... Left rotation Left circular polarization filter that selectively transmits circularly polarized light.

Claims (7)

A cholesteric liquid crystal layer having a hologram layer for displaying a hologram;
A layer that is stacked on the cholesteric liquid crystal layer, and functions as a λ / 2 plate having a pattern in which a first portion that covers the cholesteric liquid crystal layer and a second portion that does not cover are periodically repeated;
The hologram layer has a plurality of first regions corresponding to the first portion and a plurality of second regions corresponding to the second portion;
A first hologram image is constituted by the plurality of first regions,
An identification medium, wherein the plurality of second regions constitute a second hologram image. The first hologram image is a hologram image for one eye of left and right eyes;
The second hologram image is a hologram image for the other eye of the left and right eyes;
The identification medium according to claim 1, wherein a stereoscopic image is configured by the first hologram image and the second hologram image.   The identification medium according to claim 1 or 2, wherein a plurality of the first hologram image and the second hologram image are prepared in accordance with an angle at which the identification medium is viewed.   The identification medium according to claim 1, wherein the first region and the second region form a stripe pattern or a checkered pattern. The first hologram image is formed on one of the left and right eyes,
Further, a dummy hologram that reflects circularly polarized light in the same turning direction as the reflected light from the first hologram image to the outside of the identification medium and forms an image on the other side of the left and right eyes without forming an image on the other side. The identification medium according to claim 2, wherein the identification medium is formed in the cholesteric liquid crystal layer. The first hologram image is formed on one of the left and right eyes,
Further, a dummy hologram that reflects circularly polarized light in a direction opposite to the reflected light from the first hologram image to the outside of the identification medium and forms an image on one of the left and right eyes and does not form an image on the other side. The identification medium according to claim 2, wherein the identification medium is formed in the cholesteric liquid crystal layer.   One of the left and right eyes through an optical filter that transmits the identification medium according to any one of claims 2 to 6 in the first turning direction and blocks the second turning direction opposite to the turning direction. And the other eye of the left and right eyes through an optical filter that transmits the second turning direction and blocks the first turning direction. Identification method.

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