JP5915838B2 - Stereoscopic image forming body - Google Patents

Description

The present invention relates primarily imaging techniques applied to the anti-counterfeit fields, in particular, an image formed in a planar shape, at the time of use relates to an image forming member to visualize the three-dimensional image by simple stereoscopic equipment.

  As authenticity determination means for confirming the authenticity of an article, various methods have been proposed so far, and it has been put to practical use in various fields as a forgery prevention technique. In particular, it can be said that some anti-counterfeiting technology has been put into articles that are likely to be forged, such as credit cards, certificates, and vouchers. The anti-counterfeiting technology used is wide-ranging, such as those using special inks, those using visual effects such as fluorescent ink, those using fine patterns such as holograms, and those using liquid crystal films. There are also various methods for determining authenticity, such as visual inspection, a combination of determination tools, and machine recognition. In addition, by using a plurality of methods in combination, the effect (that is, forgery difficulty) is higher.

  Patent Document 1 is an invention related to an identification structure used for a security medium, and describes a technique for determining authenticity based on a difference in color when observed through a filter serving as a determination tool using wavelength selective reflectivity of cholesteric liquid crystal. ing.

  Patent Document 2 is an invention related to an anti-counterfeit foil, and a pattern (latent image) formed by an optically anisotropic layer made of a liquid crystalline compound is invisible under natural light, but is visualized when observed through a polarizing plate. Authenticity is determined by

  The laminated structure of the anti-counterfeit foil of Patent Document 2 has the configuration shown in FIG. 5, and the retardation (phase difference) of the pattern portion of the optically anisotropic layer 50 in which a pattern is formed by aligning a liquid crystalline compound. Each is different. Although the pattern is invisible under natural light, each pattern is visually recognized when irradiated with linearly polarized light or observed through a linearly polarized light filter. In addition, the functional layer 51 in the figure is a general term for layers formed by selecting as necessary, such as an adhesive layer, a reflective layer, an alignment layer, and a release layer.

  However, Patent Document 1 only observes the color change, and Patent Document 2 merely makes the latent image visible, and makes a true / false determination based on a change in light and darkness or a color change by using a determination tool. Therefore, it is insufficient in terms of anti-counterfeiting effect and cost-effectiveness.

JP 11-42875 A JP 2010-113249 A

In view of the above, an object of the present invention is to provide an image forming body that is easy to visually judge and that has a design property, and that is particularly suitable for the forgery prevention field.

This gun onset Ming, a stereoscopic image forming member which can be distinguished difference in the observation image due to the presence of stereoscopic equipment, the stereoscopic image forming body, a first occupying resulting binocular parallax image and a second The stereoscopic image forming body includes a reflective layer and a liquid crystal layer in this order on a substrate, and the liquid crystal layer has natural anisotropy having optical anisotropy exhibiting a predetermined phase difference. second image invisible under are recorded, the stereoscopic imaging characterized that you have a first image is recorded, which can be visually recognized under natural light by the coloring material exhibiting a predetermined color on the surface of the liquid crystal layer Karadadea Ru.

The stereoscopic image forming body of the present invention has an image that can be seen in a normal viewing state, and can be perceived as a stereoscopic image when the stereoscopic image forming body is combined with a stereoscopic viewing tool. For this reason, the difference of the observation image by the presence or absence of a stereoscopic vision tool can be distinguished clearly.
Accordingly, the stereoscopic image forming body of the present invention can clearly distinguish the difference in the observed image depending on the presence or absence of the stereoscopic tool, and thus has a design effect different from the stereo image by the conventional color filter, and is used in the field of forgery prevention. It is suitable for.

Configuration diagram of stereoscopic image forming body of the present invention The figure which shows the production | generation and arrangement | positioning of the stereoscopic image of this invention Configuration diagram of stereoscopic tool of the present invention Diagram showing the effect of light during stereoscopic viewing The figure which shows the lamination structure of the optical anisotropic layer Schematic diagram explaining the aspect of optical anisotropy

<Configuration of stereoscopic image forming body>
FIG. 1 is a configuration diagram of a stereoscopic image forming body of the present invention, FIG. 1 (A) is a plan view of the stereoscopic image forming body 1 of the present invention, and FIG. 1 (B) is a plan view of FIG. It is an enlarged view of the XX section of).
The stereoscopic image forming body 1 has a reflective layer 14 and an optically anisotropic layer 13 formed on a base material 10.
On the optically anisotropic layer 13, a first image 5a which is one of the images constituting the stereoscopic image 5 is formed of a color material exhibiting a predetermined color as the image pattern A121, and the optically anisotropic layer 13, the second image 5b constituting the stereoscopic image is recorded as an image pattern B131, and the region of the image pattern B131 is formed with optical anisotropy exhibiting a predetermined phase difference.
The intermediate layer 15 in the figure is a functional layer selected and formed as necessary, such as a protective layer, an adhesive layer, and an alignment layer, and is not necessarily required. The reflective layer 14 is a reflective layer provided so that incident light is efficiently reflected in order to observe the first and second images with reflected light.

<Formation of Optical Anisotropic Image Pattern (Second Image)>
As a material having the above optical anisotropy and suitable for the formation of an image pattern, there is a liquid crystal ink, and the formation of the image pattern B131 using the liquid crystal ink will be described below.

  The liquid crystal ink is obtained by dispersing liquid crystal compound molecules in a solvent to form an ink, and a liquid crystal layer is formed by applying it to a substrate. The liquid crystal layer can impart optical anisotropy by aligning liquid crystal compound molecules contained therein.

Optical anisotropy refers to the so-called birefringence in which the refractive index in the direction perpendicular to the optical axis differs depending on the direction of incident light, and the light incident on a material having optical anisotropy is The light is separated into two lights having vibration directions perpendicular to each other. These two lights are emitted with a phase difference due to the difference in refractive index,
Refractive index No for normal light, Refractive index Ne for extraordinary light,
When the thickness of the substance is d and the wavelength of light is λ, the phase difference is R (θ) = 2π (Ne−No) · d / λ [angle]
Or R (l) = (Ne-No) · d [length]
It is represented by

  FIG. 6 is a schematic diagram for explaining optical anisotropy. The linearly polarized light incident on the material 60 having optical anisotropy is decomposed as a wave that vibrates in two directions due to birefringence. That is, in the same material 60, light is in two directions, Ne (referred to as the slow axis) and No (referred to as the fast axis), and the propagation speed of the light varies depending on the difference in refractive index. The phase axis indicates that a phase difference occurs.

In order to bring the liquid crystal ink into a desired alignment state, an alignment layer is first formed on some substrate, and the liquid crystal ink is applied thereon. Since the alignment direction of the liquid crystalline compound molecules is defined by the alignment layer, the alignment state is fixed when irradiated with heat, light, electron beam, or the like.
The alignment layer is obtained by subjecting a layer formed of a polymer resin to rubbing treatment. Rubbing is a method in which the surface of the layer is rubbed in a single direction with felt or rubber.

Next, a procedure for forming an image pattern B131 that is an image pattern having optical anisotropy on the liquid crystal layer 13 will be described.
In order to form the image pattern B131 on the liquid crystal layer 13, first, an alignment layer is formed on the reflective layer 14, and then liquid crystal ink is applied.

Next, exposure is performed with ultraviolet rays or the like using a mask having the shape of the image pattern B131. Thereby, the alignment state of the exposed part is fixed.
At this time, the image pattern B131 needs to be formed so as to have a desired phase difference. For this, there is a method of adjusting the exposure amount or the density of the mask.
Further, the region 132 without the image pattern is different from the image pattern B131 by orienting with a phase difference different from the phase difference of the image pattern B131, or by eliminating the phase difference by using the anisotropic disappearance temperature. Give optical properties.

  The anisotropy disappearance temperature is a temperature at which the optical anisotropy is disturbed by heating and the phase difference is greatly decreased from the initial value (for example, 20% of the initial value). The disappearance of the optical anisotropy 132 and the fixing of this state can be performed simultaneously. At this time, since the region of the exposed image pattern B131 is already fixed and the anisotropy disappearance temperature of the region has increased, the image pattern can be selected by selecting a temperature that maintains the orientation of the region. The optical anisotropy of B131 remains, and the region 132 and the region of the image pattern B131 can be distinguished.

  Note that the formation of the image pattern B131 is not limited to the above, and it is also possible to draw directly with an electron beam, for example. Although an electron beam drawing apparatus is extremely expensive, it is particularly effective for creating a large variety of image patterns.

<Formation of First Image Pattern>
The image pattern A121 is configured by forming the shape of the first image 5a with a color material exhibiting a predetermined color under visible light. In the example of FIG. 1, an intermediate layer superimposed on the liquid crystal optical anisotropic layer 13 is used. 15 is formed. As the coloring material used here, any of commonly used dyes and pigments can be used, and the image pattern A121 can be formed by converting the ink into ink and printing or ink jet.

  In the image pattern formed in this way, the image pattern A121 is visually colored with the color of the color material, but the image pattern B131 is invisible in observation under normal natural light. The image pattern B131 becomes invisible because the phase characteristics are different between the area of the image pattern B131 and the area 132 without the image pattern, but there is no difference in the wavelength characteristics and the amount of light transmitted through both areas. This is because the two cannot be distinguished under the conditions.

<Generation of stereoscopic image>
FIG. 2 is a diagram showing generation and arrangement of a stereoscopic image used for the stereoscopic image forming body of the present invention. In the example shown in FIG.
First, three-dimensional information such as the original image 4 is generated from the solid 3. In the illustrated example, the original image 4 represents the shape by a skeleton image represented by the ridge line portion of the solid 3.
Next, two images (a first image 5a and a second image 5b) assigned to the right eye and the left eye are generated from the original image 4. The first image 5a and the second image 5b are images having parallax, and the shapes corresponding to the parallax are different.
Note that there are two methods of stereoscopic viewing using two images, the parallel method and the intersection method. In the example of FIG. 2, the first image 5a and the second image 5b are shown in an arrangement suitable for observation by the parallel method. is there.

  The first image 5a and the second image 5b are arranged on the substrate 10 in parallel (usually horizontal) with a line connecting the eyes of the observer. The interval between the two images in the arrangement may be a distance that allows stereoscopic viewing. For example, arrangements such as arrangement 1x, arrangement 1y, and arrangement 1z are possible. That is, since the perception of the stereoscopic effect depends on the parallax based on the shapes of both images, the arrangement of the first image 5a and the second image 5b may be overlapped or separated.

  In the stereoscopic image forming body of the present invention, as shown in FIG. 1, the first image 5a is recorded on the first image layer 12, and the second image 5b is recorded on the liquid crystal layer. At this time, in a visual state under natural light, the first image 5a is recorded as a visible image by the color material, and the second image 5b is recorded as an invisible image (latent image).

  The generation of the stereoscopic image 5 can be easily realized by a three-dimensional computer graphic technique. Further, the stereoscopic image 5 is not limited to a line drawing as shown in the figure, but may be an image having light and shade like a natural image. In that case, there is a method of expressing the light and shade by the size of halftone dots. In this case, the stereoscopic image 5 can be created by a stereo camera or the like.

<Stereoscopic tools>
FIG. 3 is a diagram showing the stereoscopic tool of the present invention.
The stereoscopic device 20 is a glasses-like device for binocular vision, and is provided with a filter A 20 a and a filter B 20 b each having specific transmission characteristics. FIG. 3B is a partially enlarged view of the BB cross section of FIG.

The filter A 20 a has a configuration in which a color filter layer A 23 a that transmits a specific color of visible light is overlaid on the transparent substrate 21. On the other hand, the filter B20b has a configuration in which a linear polarizing layer 22 and a color filter layer B23b having transmission characteristics different from those of the color filter layer A23a are sequentially stacked on the transparent substrate 21.
As will be described in detail later, the color filter layer A23a is not necessarily indispensable, and stereoscopic viewing is possible even without the color filter layer A23a.

<Method of stereoscopic viewing>
FIG. 4 is a diagram illustrating the action of light during stereoscopic viewing.
In stereoscopic viewing, the stereoscopic image forming body 1 and the stereoscopic viewing tool 20 are used in combination, but in the illustrated example, only the filter A20a and the filter B20b related to the optical function are shown as the stereoscopic viewing tool 20.

  Of the light incident on the stereoscopic image forming body 1 and reflected by the reflective layer 10, the light passing through the image pattern A121 is emitted with the color of the color material forming the same pattern. Further, the light passing through the image pattern B131 is divided into two components (the fast axis and the slow axis) and emitted by birefringence. Further, the light passing through the region 132 having no image pattern is emitted as light having no specific bias (no birefringence) since the optical anisotropy of the region has disappeared.

  Here, when the observer observes the stereoscopic tool 20 without using the stereoscopic tool 20, the first image 5a is visually colored, but the image pattern B131 of the second image 5b is: Since it cannot be distinguished from the region 132 having no image pattern, the second image 5b is not visually recognized. This is because the human eye cannot sense the phase difference between the fast axis and the slow axis.

Next, the action of light when using the stereoscopic tool 20 will be described.
When the stereoscopic image forming body 1 is observed on the filter A 20a side of the stereoscopic vision tool 20, the first image 5a is observed as a visible image and the second image 5b is observed as an invisible image. That is, only the first image 5a is visually recognized.

  On the other hand, on the filter B20b side, only the light having a specific polarization plane is transmitted by the linearly polarizing layer 22 out of the light reaching the filter B20b, so that the image pattern B131 (separated into a fast axis and a slow axis) and A difference in brightness occurs between the pattern-free region 132 (no birefringence) and the second image 5b appears. The light / dark difference can be maximized by adjusting the relative angle between the polarization plane of the linearly polarizing layer 22 and the orientation direction of the image pattern B131.

  At this time, if an appropriate color is set in the color filter layer B23b, the first image 5a can be made invisible. That is, only the second image 5b is visually recognized on the filter B20b side. For example, if the image pattern A121 is formed of a green color material, when the color filter layer B23b is set to a green color, the light from the image pattern B131 and the light from the non-patterned area 132 are both color filters. When the light passes through the layer B23b, only the green component is obtained, and the image pattern A121 is assimilated with the region 132 having no pattern, so that the first image 5a becomes invisible. Accordingly, when the stereoscopic image forming body 1 is observed through the filter B20b, only the second image 5b appears.

  As described above, when the stereoscopic tool 20 is observed through the stereoscopic tool 20, one of the first image 5a and the second image 5b is visually recognized in each of the eyes, and thus the stereoscopic shape is perceived. Is done.

Note that stereoscopic viewing is possible even if the filter A20a does not have the color filter layer A23a, but in this case, there is a large difference in the amount of transmitted light between the color filter layer A23a and the filter B20b, and it may be difficult to obtain a stereoscopic effect. Therefore, if the image pattern A121 is green as described above, when the magenta color (opposite color of green) is set in the color filter layer A23a,
Since the amount of light transmitted through the color filter layer A 23a is adjusted and the green color of the image pattern A121 is not transmitted, the first image 5a is more clearly visible with respect to the region 132 having no pattern. can get.

As described above, the stereoscopic image forming body of the present invention can perceive an image seen in a normal viewing state as a stereoscopic image by combining it with a simple stereoscopic tool. For this reason, the difference in the observed image depending on the presence or absence of the stereoscopic tool can be clearly distinguished, and one of the stereoscopic images 5 is recorded as an invisible latent image, so that a design effect different from the stereo image by the conventional color filter is obtained. give.
Further, the stereoscopic image 5 recorded on the stereoscopic image forming body of the present invention cannot be copied by a copying machine or the like.
Therefore, the stereoscopic image forming body of the present invention is particularly suitable for use in the field of forgery prevention.

DESCRIPTION OF SYMBOLS 1 Stereoscopic image formation body 5 Stereoscopic image 5a 1st image 5b 2nd image 10 Base material 13 Liquid crystal layer 14 Reflective layer 15 Intermediate | middle layer 20 Stereoscopic tool 20a Filter A
20b Filter B
21 Transparent substrate 22 Linearly polarizing layer 23a Color filter layer A
23b Color filter layer B
40a One eye of the observer 40b The other eye of the observer 50 Optical anisotropic layer 60 Material having optical anisotropy 121 Image pattern A
131 Image pattern B

Claims (1)

A stereoscopic imaging member that can be distinguished difference in the observation image due to the presence of stereoscopic equipment, the stereoscopic imaging member has a first and second images occupying resulting binocular parallax ,
In the stereoscopic image forming body, a reflective layer and a liquid crystal layer are laminated in this order on a base material,
In the liquid crystal layer, a second image having optical anisotropy exhibiting a predetermined phase difference and not visible under natural light is recorded,
Stereoscopic imaging member characterized that you have a first image is recorded, which can be viewed by under natural light coloring material exhibiting a predetermined color on the surface of the liquid crystal layer.

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