JP3652476B2 - Object identification structure and object provided with the structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an identification structure for the purpose of preventing forgery of planar objects or various three-dimensional objects such as passports, cards, certificates, gift certificates, pictures, tickets, public competition voting tickets, etc. by recognizing the security medium having a eye vision or machine, to a structure for identifying the authenticity.
[0002]
[Prior art]
Conventionally, for example, as a method for preventing forgery of cards and certificates, a method is generally used in which a hologram is attached to the surface of an object, and the authenticity is determined by visual recognition. In addition, there has also been proposed a technique in which a hologram having specific diffraction characteristics is used to eliminate visual ambiguity, light of a predetermined wavelength is irradiated on the hologram, and authenticity is determined based on the light receiving position of the diffracted light.
[0003]
[Problems to be solved by the invention]
However, with the recent popularization of hologram manufacturing technology, hologram manufacturing becomes easier, and in particular, a reproduction hologram that is indistinguishable from an authentic hologram can be manufactured relatively easily. It has become. Therefore, it cannot be denied that the anti-counterfeit effect by the hologram is low. In addition, since other anti-counterfeiting techniques are expensive, there are few that are suitable for articles in general distribution, and the development of new anti-counterfeiting techniques has been desired.
[0004]
The present invention has been devised to solve the problems of the prior art as described above, and is an object identification structure suitable for commonly circulated articles that is extremely difficult to counterfeit and has high identification characteristics. And it aims at providing the target object provided with the structure cheaply.
[0005]
[Means for Solving the Problems]
According to the present invention, the above-described object is an object identification structure for identifying the authenticity of an object by recognizing reflected light from a security medium provided on the object. This is achieved by providing an object identification structure characterized in that one or more types of polymer cholesteric liquid crystals having a reflection wavelength are used as a medium. In particular, the reflected light from the security medium may be recognized or detected through a wave plate and a polarizing filter or through a color filter, and the role of the wave plate and the polarizing filter may be assigned to the polymer cholesteric liquid crystal . Further, the security medium may be composed of a plurality of regions in which a plurality of types of polymer cholesteric liquid crystals having different characteristics are arranged according to a predetermined rule, a region composed of polymer cholesteric liquid crystals, a pseudo region, If the authenticity of the object is identified by recognizing the arrangement pattern by arranging them according to a predetermined rule and recognizing the arrangement pattern, the distinctiveness is further improved.
[0006]
In general, the cholesteric liquid crystal has a layered structure, and the molecular long axis directions in each layer are parallel to each other and parallel to the layer surface. Each layer is rotated and overlapped little by little and has a three-dimensional spiral structure. Selectable for circularly polarized light of wavelength λ represented by λ = n · p from the distance until this directional factor rotates 360 °, that is, the pitch p and the average refractive index n in each layer It has the characteristic of reflecting. Therefore, if the direction of the liquid crystal in each layer is counterclockwise with respect to the incident light, the left circularly polarized light having the wavelength λ is reflected and the right circularly polarized light is transmitted. All other wavelengths of light are transmitted. For example, if a cholesteric liquid crystal that reflects the red wavelength λ _R is placed on a material such as black paper that absorbs visible light, and if random light such as sunlight is applied, all transmitted light is absorbed, and the wavelength λ _R Since only the left circularly polarized light is reflected, the cholesteric liquid crystal looks bright red.
[0007]
Further, cholesteric liquid crystal has a feature that the color changes depending on the viewing angle. When the incident angle with respect to the liquid crystal surface is θ, the optical path difference reflected between the surface and bottom surface of the liquid crystal, that is, the pitch p is 2 pcos θ. When this optical path difference becomes equal to an integral multiple of the wavelength λ (2p · cos θ = nλ n is an integer), the reflected lights of both overlap and strengthen each other. Therefore, the strengthening wavelength is shorter as the incident angle becomes shallower, that is, changes from red to blue.
[0008]
On the other hand, low-molecular liquid crystals are generally sensitive to temperature, electric field, and magnetism, and change their color due to their influence. However, high-molecular cholesteric liquid crystals are very stable against them and are almost affected by them. Absent. The polymer cholesteric liquid crystal can be made to have a desired pitch and be stabilized by applying a liquid crystal to a PET film, applying a temperature, and devising an electric field, a magnetic field, a pressure, an additive, and the like.
[0009]
Since the optical characteristics of holograms are determined by the groove spacing on a plane, it is relatively easy to replicate as long as the groove processing technology is available, but the optical characteristics of polymer cholesteric liquid crystals are three-dimensional. Since it is determined by the molecular spacing, its production requires high know-how in materials, processing techniques, etc., and replication is difficult. Therefore, by using the above characteristics of the polymer cholesteric liquid crystal for identification for preventing counterfeiting of cards, passports, securities, gift certificates, etc., it is possible to improve the discrimination and improve the forgery prevention effect.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described.
[0011]
As shown in FIG. 1, one or two foils 1 on which a polymer cholesteric liquid crystal having a predetermined pitch p is formed are applied to an appropriate place or the whole of an object A such as a card, a passport, a security, or a gift certificate by, for example, a hot stamp method. Paste two or more. Here, hot stamping is a method of transferring a decorative thin film to the surface of an object by instantaneous heat and pressure using an apparatus as shown in FIG. Specifically, the object A is set on the holder 61, the hot stamping wheel 64 supplied from the supply roll 62 and taken up by the take-up roll 63 is driven by an actuator such as a cylinder (not shown) and the heating plate 65. The object A is pressed by the convex mold 66 heated by the above. The hot stamping foil 64 is generally formed by superposing a release layer, a protective layer, a metal thin film layer and an adhesive layer on a base film, and a protective layer and a polymer cholesteric liquid crystal are formed from the base film by the pressure and heat when pressed. The metal thin film layer and the adhesive layer are released from the mold and transferred to the object to form the foil 1.
[0012]
Thus, the foil 1 provided on the object, that is, the polymer cholesteric liquid crystal is read or recognized visually or by a machine.
[0013]
In addition, as a method of sticking the foil 1 as a security medium to an object, there are a heat seal method, a roll-type hand-attached seal and the like in addition to the hot stamp.
[0014]
【Example】
Example 1
As shown in FIG. 2, a foil 1 as a security medium on which a polymer cholesteric liquid crystal according to the present invention is formed is transferred or pasted to an appropriate place on an object A.
[0015]
When light is applied to this, since the color corresponding to the characteristics of the liquid crystal is reflected, its authenticity can be determined by visual detection or mechanical detection. However, even when ordinary ink is applied (printed), the same effect can be obtained to some extent. Therefore, the incident angle of light is gradually changed shallower with respect to the liquid crystal surface, and it is better to discriminate by the color change. . As described above, the intensifying wavelength of the reflected light continuously changes to the short wave light side and changes the color of the reflected light, so that the authenticity can be reliably determined. Needless to say, the color (wavelength) change of the reflected light cannot be obtained by applying the normal ink due to the change of the incident angle.
[0016]
Example 2
As shown in FIG. 3, in this embodiment, at the time of identification, the reflection wavelength of this liquid crystal is set immediately above the foil 1 on which a polymer cholesteric liquid crystal is formed as a security medium that is transferred or pasted to an appropriate place of the object A. The filter 2 to be cut is disposed, and the filter 3 similar to the above is disposed in the direction of reflected light when light is incident from a direction inclined by θ with respect to the direction orthogonal to the foil 1.
[0017]
When random light is incident on the foil 1 from directly above, for example, if the liquid crystal has a characteristic of reflecting red light, the reflected light does not pass through the filter 2 and becomes dark, and the reflected light cannot be recognized. When light is incident from a direction inclined by θ with respect to the direction orthogonal to the foil 1, the strengthening wavelength is shortened (close to blue), passes through the filter 3, and the reflected light can be recognized. The authenticity may be determined by visually recognizing this, but the authenticity may be determined by arranging the light receiving element or the like at a position corresponding to each of the above directions and detecting the received light intensity of the reflected light.
[0018]
Example 3
As shown in FIG. 4, in the present embodiment, at the time of identification, the reflected light from the foil 1 formed with the polymer cholesteric liquid crystal as a security medium transferred or pasted to an appropriate place of the object A is located at this position. A liquid crystal filter 4 made of cholesteric liquid crystal having the same characteristics as the liquid crystal, that is, the characteristic of reflecting only the same circularly polarized light component having the same wavelength as that of the polymer cholesteric liquid crystal formed on the foil 1 is disposed.
[0019]
When random light is incident on the foil 1, the reflected light does not pass through the filter 4 and becomes dark and the reflected light cannot be recognized, but when viewed without the filter 4, the reflected light of a predetermined color can be recognized. The difference may be recognized visually to determine the authenticity, but the received light intensity of the reflected light is detected by a light receiving element or the like with or without the filter 4 and the authenticity is determined from the difference. You may do it.
[0020]
Example 4
As shown in FIG. 5, in this embodiment, a foil 21 formed by superposing two kinds of polymer cholesteric liquid crystals 21a and 21b having different characteristics as a security medium is transferred or pasted at an appropriate position of the object A. Attached.
[0021]
At the time of identification, liquid crystal filters 5 and 6 made of cholesteric liquid crystal having the same characteristics as the liquid crystals 21a and 21b are arranged at positions where reflected light from the foil 21 reaches.
[0022]
For example, if the liquid crystal 21a and the liquid crystal filter 5 reflect red, and the liquid crystal 21b and the liquid crystal filter 6 reflect blue, the reflected light from the foil 21 when random light is incident first becomes purple. When the reflected light is viewed through the liquid crystal filter 5, the transmitted light is blue, and when viewed through the liquid crystal filter 6, the transmitted light is red. Therefore, the difference may be directly recognized visually to determine authenticity, but authenticity may be determined by detecting and comparing the wavelengths of the two.
[0023]
Example 5
As shown in FIG. 6A, in this embodiment, two kinds of polymer cholesteric liquid crystals 31a and 31b having different characteristics as security media are designed so as not to overlap each other at an appropriate place or the entire object A. The foil 31 formed so as to form a figure, a character or a pattern is transferred or pasted. These liquid crystals have the same reflection wavelength, but the reflected circular deflection components are contradictory. That is, the liquid crystal 31a reflects the right circular deflection component, and the liquid crystal 31b reflects the left circular deflection component.
[0024]
At the time of identification, a liquid crystal filter 7 made of cholesteric liquid crystal having the same characteristics as either one of the liquid crystals 31a and 31b is disposed at a position where the reflected light from the foil 31 reaches (FIG. 6B).
[0025]
The light reflected from the foil 31 when random light is incident has a color corresponding to the reflection wavelength of the liquid crystals 31a and 31b. However, the distinction between the liquid crystal 31a and the liquid crystal 31b, that is, recognition of design figures, characters or patterns is not possible. Can not. Therefore, when the reflected light is viewed through the liquid crystal filter 7, the reflected light from either one of the liquid crystals 31a and 31b becomes invisible, and the design figure, characters or pattern can be recognized. This is directly recognized visually to determine authenticity.
[0026]
Example 6
In this embodiment, the polymer cholesteric liquid crystal formed on the foil 41 as a security medium transferred or pasted to an appropriate place of the object A reflects infrared rays. Therefore, since it does not reflect visible light, it becomes transparent visually.
[0027]
Further, as shown in FIG. 7, at the time of identification, the infrared laser is irradiated to the foil 41 from the light emitting element 8 of the infrared laser. A λ / 4 plate 9, a polarizing filter 10, and a light receiving element 11 are arranged in this order at the position where the reflected light reaches.
[0028]
At the time of identification, the foil 41 is irradiated with an infrared laser, and the reflected light is converted into linearly polarized light by the λ / 4 plate 9 and received by the light receiving unit 11 through the polarizing filter 10 in accordance with the optical axis, thereby receiving the received light intensity. Authenticity can be determined from
[0029]
Example 7
In the present embodiment, foils 51a and 51c formed with polymer cholesteric liquid crystal that reflects infrared rays and transparent PET films 51b, 51d, and 51e are arranged at appropriate positions of the object A according to a predetermined rule. The medium is configured.
[0030]
At the time of identification, the foil 51a, the PET film 51b, the foil 51c, the PET films 51d, 51e are sequentially scanned, and the reflected light is received by the light receiving unit through the λ / 4 plate and the polarization filter in the same manner as in the sixth embodiment. , 51c, only the received light intensity is increased. For example, in the case of the arrangement pattern, the received light intensity equal to or greater than a predetermined value is set to “1”, and the other data “10100” is obtained. By comparing this with previously stored data, the authenticity can be determined. The combinations are 2 ⁿ −1, where n is the number of foils or films.
[0031]
Instead of the PET film, a foil in which a polymer cholesteric liquid crystal having different characteristics from the polymer cholesteric liquid crystals of the foils 51a and 51c is used, and binary data may be read as described above from the difference in the characteristics.
[0032]
【The invention's effect】
As is apparent from the above description, according to the present invention, by using a polymer cholesteric liquid crystal having one or a plurality of reflection wavelengths as a security medium provided on an object, in addition to its high discrimination and stability. The authenticity of the object can be easily and reliably determined due to the high manufacturing difficulty, and the effect of preventing forgery can be improved. Further, since the polymer cholesteric liquid crystal is inexpensive, there is no fear that the manufacturing cost will increase.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a basic configuration of an object provided with an identification structure according to the present invention.
FIG. 2 is a perspective view showing a configuration in Embodiment 1 of an object identification structure according to the present invention.
FIG. 3 is a perspective view showing a configuration of an object identification structure according to a second embodiment of the present invention.
FIG. 4 is a perspective view showing a configuration in a third embodiment of an object identification structure according to the present invention.
FIG. 5 is an enlarged cross-sectional view showing the structure of an object identification structure according to the present invention in Example 4;
FIGS. 6A and 6B are plan views showing the structure of an object identification structure according to the present invention in Example 5 according to the present invention.
FIG. 7 is a perspective view showing a configuration in a sixth embodiment of an object identification structure according to the present invention.
FIG. 8 is a perspective view showing a configuration in a seventh embodiment of an object identification structure according to the present invention.
FIG. 9 is a side view showing a schematic configuration of a hot stamping apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Foil 2, 3 Filter 4-7 Liquid crystal filter 8 Infrared laser light emitting element 9 λ / 4 board 10 Polarizing filter 11 Light receiving element 21 Foil 21a, 21b Liquid crystal 31 Foil 31a, 31b Liquid crystal 41, 51 Foil 51a, 51c Foil 51b, 51d 51e PET film 61 Holder 62 Supply roll 63 Winding roll 64 Hot stamping foil 65 Heating plate 66 Convex mold

Claims (7)

An object identification structure for recognizing the authenticity of an object by recognizing reflected light from the security medium provided on the object, wherein the security medium has one or more reflection wavelengths. An object identification structure using a high molecular weight cholesteric liquid crystal. The object identification structure according to claim 1, wherein reflected light from the security medium is recognized or detected through a wave plate and a polarizing filter or through a color filter. The object identification structure according to claim 2, wherein the functions of the wave plate and the polarizing filter are provided by a polymer cholesteric liquid crystal . The security medium is composed of a plurality of regions in which a plurality of types of polymer cholesteric liquid crystals having different characteristics are arranged according to a predetermined rule, and the authenticity of the object is confirmed by recognizing the arrangement pattern. 4. The object identification structure according to claim 1, wherein the object identification structure is configured to identify an object. The security medium is formed by arranging a region made of a polymer cholesteric liquid crystal and a pseudo region according to a predetermined rule, and the authenticity of an object is identified by recognizing the arrangement pattern. The object identification structure according to any one of claims 1 to 3, wherein the object identification structure is provided. 6. The object identification structure according to claim 4, wherein the array pattern is read as binary data, and the authenticity of the object is identified by the binary data. An object provided with the identification structure according to any one of claims 1 to 6.

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