JP3689237B2 - Object identification structure - Google Patents

Object identification structure Download PDF

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Publication number
JP3689237B2
JP3689237B2 JP8073198A JP8073198A JP3689237B2 JP 3689237 B2 JP3689237 B2 JP 3689237B2 JP 8073198 A JP8073198 A JP 8073198A JP 8073198 A JP8073198 A JP 8073198A JP 3689237 B2 JP3689237 B2 JP 3689237B2
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JP
Japan
Prior art keywords
light
liquid crystal
object
hologram
cholesteric liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP8073198A
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Japanese (ja)
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JPH11277957A (en
Inventor
秀一 星野
聖也 渋谷
逸雄 竹内
Original Assignee
新日本石油株式会社
日本発条株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 新日本石油株式会社, 日本発条株式会社 filed Critical 新日本石油株式会社
Priority to JP8073198A priority Critical patent/JP3689237B2/en
Publication of JPH11277957A publication Critical patent/JPH11277957A/en
Application granted granted Critical
Publication of JP3689237B2 publication Critical patent/JP3689237B2/en
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an identification structure and an identification method for identifying authenticity for the purpose of preventing counterfeiting of paper-like objects such as passports, cards, certificates, gift certificates, pictures, tickets, public competition voting tickets, etc. The present invention relates to a structure and method for identifying the authenticity of an identification medium provided on an object by visual or mechanical recognition.
[0002]
[Prior art]
Conventionally, as a method for preventing forgery of a card or certificate, for example, a hologram is attached to the surface of an object, and the authenticity is determined by visually or mechanically identifying the hologram. In addition, there is a thread hologram as a result of inserting this hologram at the time of paper manufacture. This is used, for example, for gift certificates and banknotes.
[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, other anti-counterfeiting technologies are expensive, and there are few items that are suitable for paper items that are inexpensive and rarely distributed, such as general merchandise, especially gift certificates, tickets, etc., and development of new anti-counterfeiting technologies Was desired.
[0004]
The present invention has been devised to solve the above-described problems of the prior art, is extremely difficult to counterfeit, has high discrimination, and is suitable for a paper-like article that is generally distributed. An object is to provide an identification structure and an identification method for an object.
[0005]
[Means for Solving the Problems]
According to the present invention, there is provided an identification medium comprising a hologram having a reflective layer provided with a polymer cholesteric liquid crystal in order to optically recognize a paper-like object and identify the authenticity of the object. This is achieved by providing an object identification structure which is provided integrally with the object .
[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 integer 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, in general, a hologram forming layer is a diffraction grating with various pitches and a metal reflection layer is attached to the surface of the hologram. The light reflected by this surface has different diffraction angles depending on its pitch, so that it looks different, changes color, or looks three-dimensional. By forming the reflection layer of the hologram with cholesteric liquid crystal, the discriminability can be enhanced synergistically by utilizing both optical characteristics.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described.
[0010]
As shown in FIG. 1, one or two or more polymer cholesteric liquid crystal films 1 to which the present invention is applied are inserted into appropriate positions on a paper-like object A such as a card, passport, securities, gift certificate, etc. Provide one.
[0011]
In this way, the liquid crystal film 1 provided on the object is read or recognized visually or by a machine.
[0012]
Here, the cholesteric liquid crystal reflects only one direction of circularly polarized light (for example, right circularly polarized light) of a specific wavelength (for example, green (λ1)), and light of other wavelengths or circularly polarized light of other directions (for example, left circularly polarized light). ) Is transmitted as it is. When the film 1 made of the cholesteric liquid crystal is inserted into the object A, when viewed from a specific angle, only a portion of the light from the light source (for example, natural light) having the liquid crystal film 1 reflects λ1 (green) It will look like a color. Needless to say, even if an ordinary colored film is inserted, the color change of the reflected light due to the change of the light incident / exit angle cannot be obtained.
[0013]
Therefore, although the design of the object (such as a gift certificate) can be seen as it is with an almost transparent foil, the authenticity can be confirmed by visual observation because the pattern of λ1 color can be seen when the angle is changed.
[0014]
Here, in the case where the liquid crystal film 1 is formed in a strip shape, the liquid crystal film 1 is rolled in, as shown in FIG. Both layers may be attached to each other by crimping or the like.
[0015]
On the other hand, as another embodiment of the present invention, in order to improve the accuracy of authenticity determination, as shown in FIG. 3, a polarizing plate 2a that allows only right-handed circularly polarized light to pass through the optical path of incoming and outgoing light of the liquid crystal film 1, and The quarter-wave plate 3a may be arranged as a filter, and the polarizing plate 2b and the quarter-wave plate 3b that pass only the left circularly polarized light adjacent thereto may be arranged as a filter. By arranging these on the hologram foil 1, as shown in FIG. 4, light entering the polarizing plate 2a side from the light source becomes right circularly polarized light by the polarizing plate 2a and the quarter wavelength plate 3a. It enters the liquid crystal film 1, is reflected by the cholesteric liquid crystal, becomes the original linearly polarized light again by the quarter wavelength plate 3a, is emitted through the polarizing plate 2a, and appears bright from the outside. Further, light entering the polarizing plate 2b side from the light source becomes left circularly polarized light by the polarizing plate 2b and the quarter wavelength plate 3b, enters the liquid crystal film 1, passes through the cholesteric liquid crystal, and appears dark from the outside. . By viewing this from a specific angle, a clearer image can be obtained.
[0016]
Here, the reflection of circularly polarized light differs between, for example, a normal surface such as a mirror and a cholesteric liquid crystal. In the normal plane, right polarized light is reflected and left polarized, but cholesteric liquid crystal becomes the same right circular polarized light when right polarized light is reflected. Therefore, for example, even if a film that reflects the same color as the cholesteric liquid crystal is forged, it is cut by the polarizing plate 2a, and there is no difference in contrast.
[0017]
As shown in FIG. 5, as the liquid crystal film 1, a strip-shaped liquid crystal film 1a that reflects only left-handed circularly polarized light and a strip-shaped liquid crystal film 1b that reflects only right-handed circularly-polarized light are rolled into paper in parallel. The reflected light may be observed directly or through a polarizing plate and a quarter-wave plate. In that case, it goes without saying that one band appears bright and the other band appears dark.
[0018]
On the other hand, as still another embodiment of the present invention, automatic determination may be performed by a determination device. As shown in FIG. 6, a light source 11 such as an LED element and a light receiving element 12 such as a photodiode are provided in the optical path of light reflected by the liquid crystal film 1, and a polarizing plate similar to the above on the front surface of the light source 11 and the light receiving element 12. 13 and a quarter wavelength plate 14 are provided. Then, the authenticity of the identification medium may be determined by an electrical signal corresponding to the light receiving intensity of the light receiving element 12.
[0019]
Here, the liquid crystal film 1 may be a liquid crystal that reflects infrared rays, and the light source 11 may be an infrared laser generator. Since infrared light does not reflect visible light and is transparent to the eye, design constraints are eased. In addition, when a transparent film is simply used, reflection of infrared rays is small, and even if a film with high reflection efficiency is used, the reflected light is converted into circularly polarized light opposite to the incident light. Since it is cut with a / 4 wavelength plate and a polarizing plate, the effect of preventing forgery is enhanced.
[0020]
As yet another embodiment of the present invention, a hologram foil 21 using cholesteric liquid crystal as a reflective layer may be used as an identification medium, and this may be inserted into a paper-like object A as described above. As shown in FIG. 7, the hologram foil 21 is formed by laminating an adhesive layer 22 to the middle layer of the object A, a polymer cholesteric liquid crystal layer 23 as a reflective layer, a hologram forming layer 24, and a protective layer 25. The protective layer 25 serves as an adhesive layer to the upper layer. Thus, the hologram foil 21 provided on the object is read or recognized visually or by a machine.
[0021]
Actually, if a pattern such as a letter is recorded as a hologram, the light irradiated to the hologram foil 21 from a light source (for example, a fluorescent lamp) is diffracted, and the pattern is λ1 (green) when viewed from a specific angle. It will look like a color. The authenticity can be determined by this phenomenon. Further, the amount of light diffracted by the cholesteric liquid crystal layer 23 is small. For example, if there is a design in the middle layer under the hologram foil 21, only the design is usually visible as it is. That is, the hologram foil 21 is usually almost transparent.
[0022]
Here, in the same way as in FIG. 3, the polarizing plate 2a and the quarter-wave plate 3a that pass only the right circularly polarized light are arranged as filters in the optical path of the incoming and outgoing light of the hologram foil 21, and the left circularly polarized light is adjacent to this. If the polarizing plate 2b and the quarter-wave plate 3b that only pass through are arranged as filters, as shown in FIG. 8, the hologram image is clearly visible on the polarizing plate 2a side, and the hologram image is hardly visible on the polarizing plate 2b side. Get dark. By visually recognizing this from a specific angle, the authenticity of the identification medium can be determined.
[0023]
In addition, as shown in FIGS. 9A and 9B, a light receiving element 26 having a large number of light receiving portions 26a to 26h composed of photodiodes or the like that are divided into multiple portions so as to surround the light source 27 is provided. If it is arranged and the authenticity of the hologram foil 21 as the identification medium is determined based on the received light intensity of a specific light receiving portion (for example, 26c, 26g) corresponding to the hologram image by the hologram foil 1, the discrimination property is improved. Also in this case, it goes without saying that the same polarizing plate and ¼ wavelength plate (not shown) are provided on the front surfaces of the light source 27 and the light receiving element 26.
[0024]
In each of the above embodiments, the reflection wavelength of the cholesteric liquid crystal has been described as light of wavelength λ1 (green), but light of other wavelengths may be used.
[0025]
【The invention's effect】
As is clear from the above description, according to the identification structure and identification method of an object according to the present invention, the characteristic of polarization by cholesteric liquid crystal is obtained by inserting an identification medium having a polymer cholesteric liquid crystal into a paper-like object. Can be easily identified, and the distinctiveness is improved. In addition, since the object and the identification medium are integrated, an illegal act of peeling the identification medium from the object and attaching it to another object can be prevented. Furthermore, a polarizing plate and a wave plate are provided in this order from the incident light source side in the optical path through which the incident light and the outgoing light to the identification medium pass, and the outgoing light is confirmed visually or by a detection device. , The discrimination is further improved. In addition, since this identification medium uses only a specific polarization component of a specific wavelength of incident light for identification, that is, it can be made almost transparent in the visible region. Absent. Furthermore, since a plurality of identification methods (for example, visual observation only, polarizing plate, wave plate + visual observation, machine reading, etc.) are possible, identification according to use and cost is possible, and its versatility is high.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of an object identification structure according to the present invention.
FIG. 2 is a perspective view simply showing a manufacturing process of an object having an identification structure according to the present invention.
FIG. 3 is a cross-sectional view showing another configuration of the object identification structure according to the present invention.
FIG. 4 is a plan view showing another configuration of the object identification structure according to the present invention.
FIG. 5 is a plan view showing another configuration of the object identification structure according to the present invention.
FIG. 6 is a perspective view showing another configuration of the object identification structure according to the present invention.
FIG. 7 is a cross-sectional view of an object showing another configuration of the object identification structure according to the present invention.
8 is a plan view showing the operation of the configuration shown in FIG. 7. FIG.
9A is a side sectional view showing another configuration of the object identification structure according to the present invention, and FIG. 9B is a plan view of the light source and the light receiving element of FIG. 9A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal film 1a The strip | belt-shaped liquid crystal film 1b which reflects only left circularly polarized light The strip | belt-shaped liquid crystal film 2a, 2b which reflects only right circularly polarized light 3a, 3b 1/4 wavelength plate 11 Light source 12 Light receiving element 13 Polarizing plate 14 1 / 4 wavelength plate 21 Hologram foil 22 Adhesive layer 23 Polymer cholesteric liquid crystal layer (reflection layer)
24 Hologram formation layer 25 Protective layer 26 Light receiving element 26a-26h Light receiving part 27 Light source A Object

Claims (1)

  1.     In order to optically recognize a paper-like object and identify the authenticity of the object, an identification medium comprising a hologram having a reflective layer provided with a polymer cholesteric liquid crystal is integrally provided on the object. A feature identification structure.
JP8073198A 1998-03-27 1998-03-27 Object identification structure Expired - Lifetime JP3689237B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP8073198A JP3689237B2 (en) 1998-03-27 1998-03-27 Object identification structure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8073198A JP3689237B2 (en) 1998-03-27 1998-03-27 Object identification structure

Publications (2)

Publication Number Publication Date
JPH11277957A JPH11277957A (en) 1999-10-12
JP3689237B2 true JP3689237B2 (en) 2005-08-31

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Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100708510B1 (en) 1999-04-21 2007-04-16 니폰 오일 코포레이션 (신 니혼 세키유 가부시키 가이샤) Optical laminate
AT483590T (en) 1999-05-24 2010-10-15 Toppan Printing Co Ltd Composite composite body, information storage medium and device for applying impact-safe features
JP2002127647A (en) * 2000-10-19 2002-05-08 Nhk Spring Co Ltd Discriminating medium of object and manufacturing method thereof
JP2005325482A (en) * 2004-05-17 2005-11-24 Dainippon Printing Co Ltd Counterfeit-preventing form and method for discriminating genuineness or spuriousness
JP5310983B2 (en) * 2007-12-04 2013-10-09 凸版印刷株式会社 Anti-counterfeit medium having flexibility and its verification method
JP5310984B2 (en) * 2007-12-06 2013-10-09 凸版印刷株式会社 Anti-counterfeit medium having flexibility and its verification method
JP5381023B2 (en) * 2008-11-06 2014-01-08 凸版印刷株式会社 Image forming body
WO2018235674A1 (en) * 2017-06-22 2018-12-27 富士フイルム株式会社 Optical device and laminate film

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