U.S. patent application number 10/584344 was filed with the patent office on 2007-04-12 for discrimination medium and discrimination method for discriminating the same.
This patent application is currently assigned to NHK Spring Co., Ltd.. Invention is credited to Hidekazu Hoshino, Itsuo Takeuchi.
Application Number | 20070081144 10/584344 |
Document ID | / |
Family ID | 34736532 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070081144 |
Kind Code |
A1 |
Hoshino; Hidekazu ; et
al. |
April 12, 2007 |
Discrimination medium and discrimination method for discriminating
the same
Abstract
A discrimination medium on which printing can be freely
performed, which cannot be easily falsified, in which the
authenticity can be easily discriminated by unique appearance, and
which can be produced at low cost, is provided. A cholesteric
liquid crystal layer 10 or a multilayer film 5, and a breakable
print recording layer are laminated in the discrimination medium.
The multilayer film 5 has plural light transparent films which are
laminated and are different from each other in refraction index.
Therefore, the discrimination medium has unique optical
characteristics such that a character, a symbol, a pattern, a
figure formed by printing by a thermal printer or the like changes
in color depending on the viewing angle. A discrimination method
using the above optical characteristics of the discrimination
medium is provided.
Inventors: |
Hoshino; Hidekazu;
(Yokohama-shi, JP) ; Takeuchi; Itsuo;
(Yokohama-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
NHK Spring Co., Ltd.
10, Fukuura 3-chome, Kanazawa-ku
Yokohama-shi
JP
236-0004
|
Family ID: |
34736532 |
Appl. No.: |
10/584344 |
Filed: |
December 27, 2004 |
PCT Filed: |
December 27, 2004 |
PCT NO: |
PCT/JP04/19525 |
371 Date: |
June 23, 2006 |
Current U.S.
Class: |
356/71 |
Current CPC
Class: |
B42D 2035/24 20130101;
B42D 2035/34 20130101; Y10T 428/24802 20150115; G09F 3/02 20130101;
G09F 2003/0257 20130101; B42D 25/364 20141001; B42D 25/00 20141001;
G09F 3/0292 20130101; B42D 2033/26 20130101; B42D 25/391
20141001 |
Class at
Publication: |
356/071 |
International
Class: |
G06K 9/74 20060101
G06K009/74 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2003 |
JP |
2003-433806 |
Claims
1. A discrimination medium comprising: a multilayer film having
plural light transparent films which are laminated and are
different from each other in refraction index, the multilayer film
having a surface; and a breakable print recording layer provided at
least a portion of at least the surface of the multilayer film,
wherein when a predetermined condition is applied to a portion of
the breakable print recording layer, the portion of the breakable
print recording layer is removed from the discrimination
medium.
2. A discrimination medium comprising: a cholesteric liquid crystal
layer having a circular polarization light selectivity of
reflecting predetermined circularly polarized light and having a
surface; and a breakable print recording layer provided at least a
portion of at least the surface of the cholesteric liquid crystal
layer, wherein when a predetermined condition is applied to a
portion of the breakable print recording layer, the portion of the
breakable print recording layer is removed from the discrimination
medium.
3. A discrimination medium according to claim 1, wherein the
discrimination medium further comprises: a printed layer provided
at least a portion of the breakable print recording layer.
4. A discrimination medium according to claim 3, wherein the
printed layer has substantially the same color as the color of the
multilayer film when the multilayer film is viewed from a
predetermined direction.
5. A discrimination medium according to claim 1, wherein the
discrimination medium further comprises: an adhesive layer which is
provided to the multilayer film includes a black pigment.
6. A discrimination medium according to claim 1, wherein at least a
portion of the multilayer film is subjected to hologram working or
embossing.
7. A discrimination medium according to claim 1, wherein the
discrimination medium further comprises: an interlayer peeling
structure or a peeling breaking structure at least a portion of the
multilayer film.
8. A discrimination medium according to claim 5, wherein the
discrimination medium is provided to an article, the adhesive layer
is composed of transformable adhesive or peelable adhesive, and one
of a character, a symbol, and a pattern is formed and discriminated
on the article or the discrimination medium when the adhesive layer
is peeled from the discrimination medium.
9. A discrimination medium according to claim 1, wherein the
breakable print recording layer and the printed layer are provided
to at least portions of both sides of the multilayer film.
10. A discrimination method for discriminating a discrimination
medium, wherein the discrimination medium comprising: a multilayer
film having plural light transparent films which are laminated and
are different from each other in refraction index, the multilayer
film having a surface; and a breakable print recording layer
provided at least a portion of at least the surface of the
multilayer film, wherein when a predetermined condition is applied
to a portion of the breakable print recording layer, the portion of
the breakable print recording layer is removed from the
discrimination medium, wherein the discrimination method
comprising: observing the discrimination medium from one or more
predetermined viewing angles.
11. A discrimination method for discriminating a discrimination
medium, wherein the discrimination medium comprising: a cholesteric
liquid crystal layer having a circular polarization light
selectivity of reflecting predetermined circularly polarized light
and having a surface; and a breakable print recording layer
provided at least a portion of at least the surface of the
cholesteric liquid crystal layer, wherein when a predetermined
condition is applied to a portion of the breakable print recording
layer, the portion of the breakable print recording layer is
removed from the discrimination medium, wherein the discrimination
method comprising: observing the discrimination medium via an
optical filter allowing a predetermined circularly polarized light
to selectively pass therethrough.
12. A discrimination medium according to claim 2, wherein the
discrimination medium further comprises: a printed layer provided
at least a portion of the breakable print recording layer.
13. A discrimination medium according to claim 12, wherein the
printed layer has substantially the same color as the color of the
cholesteric liquid crystal layer when the cholesteric liquid
crystal layer is viewed from a predetermined direction.
14. A discrimination medium according to claim 2, wherein the
discrimination medium further comprises: an adhesive layer which is
provided to the cholesteric liquid crystal layer and includes a
black pigment.
15. A discrimination medium according to claim 2, wherein at least
a portion of the cholesteric liquid crystal layer is subjected to
hologram working or embossing.
16. A discrimination medium according to claim 2, wherein the
discrimination medium further comprises: an interlayer peeling
structure or a peeling breaking structure at least a portion of the
cholesteric liquid crystal layer.
17. A discrimination medium according to claim 14, wherein the
discrimination medium is provided to an article, the adhesive layer
is composed of transformable adhesive or peelable adhesive, and one
of a character, a symbol, and a pattern is formed and discriminated
on the article or on the discrimination medium when the adhesive
layer is peeled from the discrimination medium.
18. A discrimination medium according to claim 2, wherein the
breakable print recording layer and the printed layer are provided
to at least portions of both sides of the cholesteric liquid
crystal layer.
Description
TECHNICAL FIELD
[0001] The present invention relates to techniques advantageously
used for determining whether or not passports, documents, various
types of cards, passes, bills, exchange tickets for money, security
notes, bonds, gift certificates, pictures, tickets, public game
voting tickets, recording media in which sound data and image data
are recorded, recording media in which computer software is
recorded, various industrial products, products of foods,
medicines, and sundries, and product labels applied to packages for
products are authentic.
BACKGROUND ART
[0002] Product labels, on which the contents of products,
compositions of products, place of production, production number,
production date, and barcode are printed are applied to industrial
products and packages therefor. Since the above information varies
depending on each product, mass production of one label cannot be
performed. Due to this, printing is performed on a label, which has
a breakable print recording layer facilitating production in small
lots, by a thermal printer, laser, an electric discharge printer,
or the like. However, recently, counterfeit products having
falsified product labels applied thereon or counterfeit products
having genuine product labels peeled from genuine products are on
market, and a large amount of damage is caused. In order to prevent
the above illegal use of product labels, techniques for
discriminating the authenticity of product labels are needed.
[0003] Patent Publication 1 discloses a technique in which plural
colored layers are used, although the number of colored layer is
generally one, and depth of breakage caused by a thermal head is
controlled in order to show plural mixed colors and color tone, and
the colored layer is combined with the color tone of a printed
layer in order to form a complicated pattern. Patent Publication 2
discloses a technique in which a thermal breakage type print
recording layer and an electric discharge breakage type print
recording layer are provided, and breakable print using
characteristics of the layers is simultaneously formed on a surface
and a reverse surface. Patent Publication 3 discloses a technique
in which a thermal breakage type print recording layer and a
hologram are combined and designability and difficulty of
counterfeit holograms are provided to a thermosensitive recording
paper.
[0004] The Patent Publication 1 is Japanese Unexamined Patent
Application Publication No. Hei 6-15985. The Patent Publication 2
is Japanese Unexamined Patent Application Publication No. Hei
6-106882. The Patent Publication 2 is Japanese Unexamined Patent
Application Publication No. Hei 8-80680.
DISCLOSURE OF THE INVENTION
Problems Solved by the Invention
[0005] However, since plural colored layers are used, the number of
production processes is increased, and production cost is high. In
addition, since a large number of colored layers are laminated,
material costs are high. In the technique using a hologram, in
recent years, falsification techniques for holograms have increased
in sophistication and counterfeit goods for which the authenticity
is difficult to determine may be produced, so that techniques using
holograms are becoming unreliable. Due to these, techniques are
required in which falsification is more difficult, in which it is
easy to determine whether or not goods are authentic, and in which
product labels can be produced at low cost.
[0006] An object of the present invention is to provide a
discrimination medium which has a simple composition of materials
and can be easily produced so that material costs and production
costs are low. Another object of the present invention is to
provide a discrimination medium which uses materials which are
difficult to falsify and therefore cannot be easily falsified.
Another object of the present invention is to provide a
discrimination medium in which the authenticity can be reliably and
easily determined by unique appearance of the discrimination
medium. Another object of the present invention is to provide a
discrimination method which is superior in discriminating the above
discrimination medium.
MEANS FOR SOLVING THE PROBLEMS
[0007] According to one aspect of the present invention, a
discrimination medium comprising: a multilayer film having plural
light transparent films which are laminated and are different from
each other in refraction index, the multilayer film having a
surface; and a breakable print recording layer provided at least a
portion of at least the surface of the multilayer film. When a
predetermined condition is applied to a portion of the breakable
print recording layer, the portion of the breakable print recording
layer is removed from the discrimination medium.
[0008] In the above structured discrimination medium, the
multilayer film having plural light transparent films which are
laminated and are different from each other in refraction index is
exposed on the removed portion of the breakable print recording
layer. Since a character, a symbol, or a pattern formed on the
exposed portion of the multilayer film changes in color depending
on the viewing angle, the discrimination medium is different from a
product label having a colored layer does not change in color
depending on the viewing angle, and it can be easily determined
whether or not the discrimination medium is authentic. When there
are typical coating apparatuses, the multilayer film can be easily
produced thereby at low cost. However, when there are not typical
coating apparatuses, falsification of the multilayer film is
difficult. In this case, if an attempt is made to produce the
multilayer film, production cost is very high. Thus, falsification
of the discrimination medium can be reliably prevented even though
the production cost is low.
[0009] According to another aspect of the present invention, a
discrimination medium includes: a cholesteric liquid crystal layer
having a circular polarization light selectivity of reflecting
predetermined circularly polarized light and having a surface; and
a breakable print recording layer provided at least a portion of at
least the surface of the cholesteric liquid crystal layer. When a
predetermined condition is applied to a portion of the breakable
print recording layer, the portion of the breakable print recording
layer is removed from the discrimination medium.
[0010] In the above structured discrimination medium, the
cholesteric liquid crystal layer having a circular polarization
light selectivity of reflecting predetermined circularly polarized
light is exposed on the removed portion of the breakable print
recording layer. Since a character, a symbol, or a pattern formed
on the exposed portion of the cholesteric liquid crystal layer
changes in color depending on the viewing angle, the discrimination
medium is different from a product label having a colored layer
which does not change in color depending on the viewing angle, and
it can be easily determined whether or not the discrimination
medium is authentic. Specific apparatuses and specific materials
are necessary for production of the discrimination medium. When
there are specific apparatuses and specific materials, the
cholesteric liquid crystal layer can be easily produced at low
cost. However, when there are not specific apparatuses and specific
materials, falsification of the cholesteric liquid crystal layer is
difficult. In this case, if an attempt is made to produce the
cholesteric liquid crystal layer, production cost is very high.
Thus, falsification of the discrimination medium can be reliably
prevented, even though the production cost is low.
[0011] According to a preferred embodiment of the present
invention, the discrimination medium further includes: a printed
layer provided at least of a portion of the breakable print
recording layer. In this discrimination medium, a character, a
symbol, or a pattern which is the same as the character, the
symbol, or the pattern formed by the removed portion of the
breakable print recording layer is formed on the printed layer.
When the viewing angle is changed, a portion of the discrimination
medium changes in color. Therefore, the discrimination medium is
different from a product label having a colored layer which does
not change in color depending on the viewing angle, and it can be
easily determined whether or not the discrimination medium is
authentic.
[0012] According to a preferred embodiment of the present
invention, the printed layer has substantially the same color as
the color of the multilayer film or the cholesteric liquid crystal
layer when the multilayer film or the cholesteric liquid crystal
layer is viewed from a predetermined direction. In this
discrimination medium, when the discrimination medium is viewed at
the predetermined angle, the character, the symbol, or the pattern
formed by the removed portion of the breakable print recording
layer, and the printed layer, are the same color and cannot be
discriminated. When the viewing angle is changed, the character,
the symbol, or the pattern is visible again and can be
discriminated. Thus, the discrimination medium is different from a
product label having a colored layer which does not change in color
depending on the viewing angle, and it can be easily determined
whether or not the discrimination medium is authentic.
[0013] According to a preferred embodiment of the present
invention, the discrimination medium further includes: an adhesive
layer which is provided to the multilayer film or the cholesteric
liquid crystal layer and includes a black pigment. In this
discrimination medium, since light having color which is other than
the color of the character, the symbol, or the pattern formed by
the removed portion of the breakable print recording layer is
absorbed by the adhesive layer including a black pigment, the color
of the character, the symbol, or the pattern formed by the removed
portion thereof can be clearly seen. Thus, the difference between
the discrimination medium and the counterfeit is clear.
[0014] According to a preferred embodiment of the present
invention, at least a portion of the multilayer film or the
cholesteric liquid crystal layer is subjected to hologram working
or embossing. In this discrimination medium, the character, the
symbol, or the pattern formed by the removed portion of the
breakable print recording layer can be changed not only in color
but also in shape. Therefore, the difference between the
discrimination medium and the counterfeit is clear. In addition,
since the discrimination medium exhibits a complicated feature,
falsification of the discrimination medium is difficult.
[0015] According to a preferred embodiment of the present
invention, the discrimination medium further includes: an
interlayer peeling structure or a peeling breaking structure at
least a portion of the multilayer film or the cholesteric liquid
crystal layer. In this discrimination medium, when the
discrimination medium is applied to a product or an article once
and is then peeled therefrom, peeling occurs in the interlayer
peeling structure or the peeling breaking structure, and the
discrimination medium cannot be used as a product label again.
Therefore, misuse of the discrimination medium to make counterfeit
products appear to be real products can be prevented.
[0016] According to a preferred embodiment of the present
invention, the adhesive layer is composed of transformable adhesive
or peelable adhesive, and one of a character, a symbol and a
pattern is formed and discriminated on the article or the
discrimination medium when the adhesive layer is peeled from the
discrimination medium. In this discrimination medium, when the
discrimination medium is applied to a product or a package once and
is peeled therefrom, transforming or peeling occurs in the
interlayer peeling structure or the peeling breaking structure, so
that peeling of the discrimination medium applied to the product or
the package can be clearly discriminated, and the discrimination
medium cannot be used as a product label again. Therefore, misuse
of the discrimination medium for disguising counterfeit product as
real product can be prevented.
[0017] According to a preferred embodiment, the breakable print
recording layer and the printed layer are provided at least
portions of both sides of the multilayer film or the cholesteric
liquid crystal layer. In this discrimination medium, characters,
symbols, or patterns can be formed on both sides of the multilayer
film or the cholesteric liquid crystal layer by the removed portion
of the breakable print recording layer. Since the characters, the
symbols, or the patterns change in color depending on the viewing
angle, the discrimination medium is different from a product label
having a colored layer which does not change in color depending on
the viewing angle, and it can be easily determined whether or not
the discrimination medium is authentic.
[0018] According to another aspect of the present invention, a
discrimination method for discriminating a discrimination medium is
provided. The discrimination medium includes: a multilayer film
having plural light transparent films which are laminated and are
different from each other in refraction index, the multilayer film
having a surface; and a breakable print recording layer provided at
least a portion of at least the surface of the multilayer film.
When a predetermined condition is applied to a portion of the
breakable print recording layer, the portion of the breakable print
recording layer is removed from the discrimination medium. The
discrimination method includes: observing the discrimination medium
from one or more predetermined viewing angles.
[0019] According to another aspect of the present invention, a
discrimination method for discriminating a discrimination medium is
provided. The discrimination medium includes: a cholesteric liquid
crystal layer having a circular polarization light selectivity of
reflecting predetermined circularly polarized light and having a
surface; and a breakable print recording layer provided at least a
portion of at least the surface of the cholesteric liquid crystal
layer. When a predetermined condition is applied to a portion of
the breakable print recording layer, the portion of the breakable
print recording layer is removed from the discrimination medium.
The discrimination method includes: observing the discrimination
medium via an optical filter allowing a predetermined circularly
polarized light to selectively pass therethrough.
[0020] A discrimination medium 1 having a typical breakable print
recording layer shown in FIG. 1 will be explained hereinafter. The
discrimination medium 1 has a laminated structure in which a
separator 7, an adhesive layer 6, a colored layer (which is also
used as a substrate) 12, an anchor layer 9, a breakable print
recording layer 4, a printed layer 3, and a protection layer 2 are
laminated in turn from beneath. The separator 7 is separatable, and
is peeled from the discrimination medium 1 before discrimination
medium 1 is applied to the article. The adhesive layer 6 is formed
such that a binder is mixed with a plasticizer, a stabilizer, a
curing agent, or the like if necessary, is sufficiently kneaded
with a solvent or a diluent, and is applied to a substrate by a
coating method, for example, a gravure method, a roll method, or a
knife edge method. The binder may be composed of one selected from
the group consisting of polyvinyl chloride acetate copolymer,
ethylene vinyl acetate copolymer, vinyl chloride propionate
copolymer, rubber based resin, cyanoacrylate resin, cellulose based
resin, ionomer resin, and polyolefin based copolymer.
[0021] The colored layer 12 is composed of one selected from the
group consisting of plastic, metal, paper, and impregnated paper or
mixture thereof. The surface color of the substrate can be used.
Alternatively, various coatings or various inks may be formed by a
coating method or a printing method such as a gravure method, a
roll method, a knife edge method, and an offset method. The plastic
may be selected from the group consisting of nylon, cellulose,
diacetate, cellulose triacetate, polystyrene, polyethylene,
polypropylene, polyester, polyimide, and polycarbonate, etc. The
metal may be selected from copper and aluminum, etc. The allowable
heat resistance temperature limit of the colored layer 12 is
preferably relatively higher than that of the printed layer 3.
[0022] The anchor layer 9 can be composed of one selected from the
group consisting of thermoplastic resin, polyurethane resin,
epoxide resin, and ketone resin, can be transparent, and can have
a: thickness of about 0.005 to 0.5 mm. The thermoplastic resin may
be selected from polyvinylchloride, polystyrene, and acrylic. The
breakable print recording layer 4 is of a thermosensitive breakage
type or an electronic discharge breakage type. The breakable print
recording layer 4 is composed of one selected from metal and alloy,
or mixture thereof. The metal is selected from Te, Sn, In, Al, Bi,
Pb, Zn, Cu, Ni, Cr, and Ti, etc. The alloy is an Fe--Co alloy. The
breakable print recording layer 4 can be formed on the colored
layer 12 by vacuum deposition, sputtering, or plating.
[0023] The printed layer 3 is composed of the same material as the
above coating and the ink coated on the above colored layer 12. The
protection layer 2 can be formed by laminating synthetic resin,
extrusion coating or coating of synthetic resin. In consideration
of purpose or adhesion to another layer, the synthetic resin of the
protection layer 2 generally uses the same synthetic resin as that
for forming the substrate of the colored layer 12. In particular,
when thermosetting synthetic resin is used, surface hardness and
prevention of pollution are advantageous. When a coating including
an ultraviolet curable synthetic resin is used, curing can be
performed quickly. Thus, the coating is favorably used.
[0024] The surface of the above discrimination medium 1 is
subjected to local heating by a thermal printer or electric
discharge printer, and it is thereby melted and broken. Thus, as
shown in FIG. 2, a removed portion 8 can be formed. A character, a
symbol, a pattern, or a design can be visually formed by the
removed portion 8. The character may be the date of production or
production number. The symbol may be a brand mark. The pattern may
be a barcode.
[0025] Optical characteristics of cholesteric liquid crystal layer
will be explained. FIG. 3 is a conceptual diagram showing a
structure of the cholesteric liquid crystal layer. The cholesteric
liquid crystal has a stacked structure. The molecular long axes of
respective layers of the stacked structure are parallel to each
other, and are parallel to the plane thereof. The respective layers
are rotated slightly with respect to the adjacent layer and are
stacked. The cholesteric liquid crystal thereby has a
three-dimensional spiral structure.
[0026] Denoting that, in a direction perpendicular to the layer,
pitch P is a distance needed when the molecular long axis is
rotated through 360 degrees and returns to the initial state, and
an average refraction index of the respective layers is index N,
the cholesteric liquid crystal layer selectively reflects
circularly polarized light having a center wavelength .lamda.s
satisfying the equation .lamda.s=N.times.P. That is, when light
(natural light) which is not predetermined circularly polarized
light is irradiated on the cholesteric liquid crystal layer, the
cholesteric liquid crystal layer selectively reflects circularly
polarized light having a center wavelength .lamda.s. The
polarization direction of the circularly polarized light reflected
by the cholesteric liquid crystal layer is clockwise or
counterclockwise depending on the rotation direction of the
cholesteric liquid crystal layer. That is, circularly polarized
light having the above predetermined center wavelength and the
above predetermined circular polarization direction is selectively
reflected by the cholesteric liquid crystal layer. Circularly
polarized light having another wavelength and the above
predetermined circular polarization direction, linearly polarized
light, and circularly polarized light having circular polarization
direction opposite to the above predetermined circular polarization
direction passes through the cholesteric liquid crystal layer.
[0027] FIG. 4 is a conceptual diagram showing a condition in which
light having a predetermined wavelength and a predetermined
circular polarization direction is selectively reflected by a
cholesteric liquid crystal layer 10. For example, FIG. 4 shows a
cholesteric liquid crystal layer 10 having a spiral structure in
which the molecular long axes of the respective layers are rotated
in a clockwise direction (right-handed direction). When natural
light enters the cholesteric liquid crystal layer 10, right-handed
circularly polarized light having the predetermined center
wavelength is selectively reflected by the cholesteric liquid
crystal layer 10. Another polarization light (linearly polarized
light and left-handed circularly polarized light) and right-handed
circularly polarized light having another center wavelength pass
through the cholesteric liquid crystal layer 10.
[0028] For example, a cholesteric liquid crystal layer having a
structure shown in FIG. 3 and reflecting light having a center
wavelength .lamda.s of red light is disposed on a member such as a
black sheet absorbing visible light. When random light such as
sunlight is irradiated on the cholesteric liquid crystal layer,
transmission light of the cholesteric liquid crystal layer is
absorbed in the black sheet, and right-handed circularly polarized
light having the predetermined center wavelength is selectively
reflected by the cholesteric liquid crystal layer. As a result, the
cholesteric liquid crystal layer is clearly seen to be red. The
above characteristic of selectively reflecting predetermined
circularly polarized light having a predetermined center frequency
is called circularly polarized light selectivity.
[0029] The color of the cholesteric liquid crystal changes
depending on the viewing angle. When incident light obliquely
enters the cholesteric liquid crystal, the apparent pitch P
decreases, and the center wavelength .lamda.s is thereby short. For
example, reflection light reflected by the cholesteric liquid
crystal is seen to be red at an angle perpendicular to the
cholesteric liquid crystal. As the viewing angle is increased, the
color of light shifts to orange, yellow, green, blue-green, and
blue in turn. This phenomenon is called blue shift. The viewing
angle is an angle between a line of vision and a line perpendicular
to a viewing surface.
[0030] Optical characteristics of a multilayer film having plural
light transparent films which are different from each other in
refraction index will be explained. FIG. 5 is a conceptual diagram
showing a condition in which the multilayer film reflects light.
FIG. 5 shows one example in which films 5a (A layers) having a
first refraction index and films 5b (B layers) having a second
refraction index are alternately laminated.
[0031] When white light is irradiated on the multilayer film 5,
incident light is reflected at the interfaces of the films
different from each other in refraction index based on Fresnel's
law. In this case, a portion of the incident light is reflected at
the interface between the A layer and the B layer, and another
portion of the incident light passes therethrough. Since each
interface between the A layer and the B layer repeatedly exists,
interferences between reflection light reflected at each interface
occur. The larger the angle of the incident light, the shorter the
optical path difference of the reflection light reflected by each
interface. The interference of each light of the shorter wavelength
occurs, and the intensity of the light of the shorter wavelength is
thereby strong. Therefore, the more obliquely the multilayer film 5
on which white light is irradiated is viewed, that is, the more
parallel to the plane of the multilayer film 5 the multilayer film
5 on which white light is irradiated is viewed, the shorter the
wavelength of the light reflected strongly by the multilayer film
5. For example, the more oblique the multilayer film 5 on which
white light is irradiated, the bluer the reflection light reflected
by the multilayer film 5. This phenomenon is called blue shift. The
incident angle is an angle between incident light and a line
perpendicular to the incident surface.
[0032] The multilayer film having plural light transparent films
which are different from each other in refraction index is
structured such that at least two kinds of light transparent films
which are different from each other in refraction index are
laminated, and at least one interface between the light transparent
films which are different from each other in refraction index
exists. For example, the multilayer film is structured such that
two light transparent films which are different from each other in
refraction index are alternately laminated. Alternatively, the
multilayer film is structured such that the first to the Nth light
transparent films having the first to the Nth refraction indexes
are laminated in turn as one unit and plural units are laminated.
The N in Nth denotes a natural number.
EFFECTS OF THE INVENTION
[0033] In the present invention, printing can be freely performed
as needed. Since complicated optical characteristics of the
discrimination medium are combined, falsification of discrimination
is difficult, and it can be reliably and easily determined whether
or not discrimination medium is authentic. The production cost is
low. The discrimination method for discriminating the
discrimination medium is superior in determining whether or not
discrimination medium is authentic.
[0034] In the present invention, since the discrimination medium
can be discriminated by complicated combination of the left-handed
circularly polarized light, right-handed circularly polarized
light, the color, the figure, and the optical phenomenon of the
color shift, falsification cannot be performed by using a copy in
which images are scanned. The discrimination medium is superior in
color, and is thereby superior in design, so that the
discrimination medium is advantageous for an article having
superior design as the article to be discriminated.
BRIEF DESCRIPTION OF DRAWINGS
[0035] FIG. 1 is a cross sectional view showing a discrimination
medium such as a label having a conventional breakable print
recording layer.
[0036] FIG. 2 is a cross sectional view showing a discrimination
medium of which a portion of a conventional breakable print
recording layer is removed.
[0037] FIG. 3 is a conceptual diagram for explaining a structure of
a cholesteric liquid crystal layer.
[0038] FIG. 4 is a conceptual diagram for explaining optical
characteristics of a cholesteric liquid crystal layer.
[0039] FIG. 5 is a conceptual diagram for explaining optical
characteristics of a multilayer film.
[0040] FIG. 6 is a cross sectional view showing a discrimination
medium of the First Embodiment.
[0041] FIG. 7 is a cross sectional view showing a discrimination
medium after printing of the First Embodiment.
[0042] FIG. 8 is a schematic diagram showing a discrimination
medium 1 applied to production label and a perspective view showing
a condition in which a character and a pattern emerges on the
production label.
[0043] FIG. 9 is a cross sectional view showing a discrimination
medium of the Second Embodiment.
[0044] FIG. 10 is a cross sectional view showing a discrimination
medium of the Third Embodiment.
[0045] FIG. 11 is a cross sectional view showing a discrimination
medium having an example of a breakable print recording layer.
EXPLANATION OF REFERENCE NUMERALS
[0046] 1 denotes a discrimination medium, 1' denotes a
discrimination medium after printing, 2 denotes a protection layer,
3 denotes a printed layer, 4 denotes a breakable print recording
layer, 5 denotes a multilayer film, 6 denotes an adhesive layer, 7
denotes a separator, 8 denotes a removed portion, 9 denotes an
anchor layer, 10 denotes a cholesteric liquid crystal layer, 11
denotes a substrate, 12 denotes a colored layer, 13 denotes a roll
discrimination medium, and 14 denotes a low melting point metal
removed region.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0047] FIG. 6 is a cross sectional view showing a discrimination
medium 1 of the First Embodiment. For example, the discrimination
medium 1 can be used as a product label which is applied on a
product or a package of a product and is used for discriminating
the product. The discrimination medium 1 has a laminated structure
in which a separators 7, an adhesive layer 6, a multilayer film 5,
a breakable print recording layer 4, a printed layer 3, and a
protection layer 2 are laminated in turn from beneath. When the
discrimination medium 1 is applied to a product or the like, the
separator 7 is peeled from the discrimination medium 1, and the
discrimination medium 1 is adhered thereto by the adhesive layer
6.
[0048] The separator 7 is a paper or a film which is subjected to
surface processing using silicone, fluororesin, wax, or the like
and is thereby separatable. The adhesive layer 6 secures the
discrimination medium 1 to an article. The adhesive layer 6 can be
composed of an adhesive used in a typical discrimination medium,
ultraviolet curable resin, or thermosetting resin.
[0049] The adhesive layer 6 functions as a light absorption layer.
Thus, the adhesive layer 6 includes a black pigment of carbon or a
dark pigment of carbon, and thereby has a light absorption
characteristic. A light absorption layer absorbing visible light,
which is different from the adhesive layer 6, may be provided. The
adhesive layer 6 may be processed such that a character is formed
when the adhesive layer 6 is peeled.
[0050] The multilayer film 5 has 201 layers structured such that
first films 5a are composed of polyethylene-2,6-naphthalate and
second films 5b are composed of polyethylene terephthalate. The
multilayer film 5 has a thickness of 20 .mu.m. In a production
method for the multilayer film 5, 101 layers (A layers) are
composed of polyethylene-2,6-naphthalate and 100 layers (B layers)
are composed of polyethylene terephthalate including 12 mol % of
isophthalic acid copolymerized therewith. The 101 layers (A layers)
and the 100 layers (B layers) are laminated alternately, so that an
unstretched sheet having 201 layers is produced. The sheet is
stretched at a temperature of 140 degrees C. so as to be 3.5 times
as long as the initial sheet in a longitudinal direction, and the
sheet is stretched at a temperature of 150 degrees C. so as to be
5.7 times as long as the initial sheet in a lateral direction.
Next, the sheet is subjected to heating at a temperature of 210
degrees C., and a laminated structure having a thickness of 20
.mu.m is obtained. In the above manner, the multilayer film 5 is
obtained. In this example, when incident light enters the
multilayer film 5 at an incident angle of 0 degrees, red light is
reflected by the multilayer film 5. The material of the multilayer
film 5 is not limited to the above material. Instead of using the
films composed of different kinds of materials described above,
films composed of the same materials and having different
refraction indexes can be used. The multilayer film 5 can be
antistrophic by changing the stretch ratio of longitudinal and
lateral directions. The anisotropic multilayer film in the case in
which the discrimination medium is inclined in a longitudinal
direction is different in color change from that in the case in
which the discrimination medium is inclined in a lateral direction.
When adhesion between the multilayer film 5 and the breakable print
recording layer 4 is not good, an anchor layer 9 is appropriately
provided therebetween, so that the adhesion can be improved.
[0051] The breakable print recording layer 4 can be formed by
depositing Sn at a thickness of 800 .ANG. at a temperature of 230
degrees C. The material of the breakable print recording layer 4 is
not limited to the above material. The breakable print recording
layer 4 can be appropriately composed of material used for the
breakable print recording layer of the typical discrimination
medium described above.
[0052] For example, the printed layer 3 can be formed by coating a
red urethane based coating having a thickness of 10 .mu.m. The
printed layer 3 can be appropriately composed of coating or ink
used for the colored layer of the typical discrimination medium
described above. Alternatively, the printed layer may not be
provided.
[0053] For example, the protection layer 2 can be composed of
isotopic triacetylcellulose (TAC) having a thickness of 40 .mu.m.
The protection layer 2 has an isotropic refraction index in order
to maintain polarization condition of circularly polarized light
passing therethrough. The protection layer 2 can be appropriately
composed of material used for the protection layer of the typical
discrimination medium described above. The protection layer 2 may
not be provided.
[0054] FIG. 7 shows a discrimination medium 1' obtained by
performing printing on the discrimination medium 1 having the above
laminated structure by a thermal printer, an electric discharge
printer, or the like. Portions of the protection layer 2, the
printed layer 3, and the breakable print recording layer 4 are
melted, broken, and removed, so that a removed portion 8 is
formed.
[0055] When the discrimination medium 1' after the printing is
viewed from the side of the protection layer 2 under white light or
the like, the discrimination medium 1' appears to be red overall,
so that the character cannot be discriminated. However, when the
discrimination medium 1' is gradually inclined and the incident
angle is increased, as shown in FIG. 8, since the color of the
removed portion 8 gradually shifts to orange, green, blue, and
violet in turn, the removed portion 8 can be seen as a character.
The color of the printed layer may not be the same as that of the
multilayer film, and may be a color such that the printed layer and
the multilayer film can be clearly discriminated. Various
characters, symbols, figures, or patterns may be printed on the
printed layer.
[0056] In mass production of the discrimination mediums, the
discrimination mediums are sequentially produced in a long sheet
shape, and they are rolled by a roller 13 shown in the lower part
of the drawing of FIG. 8. A portion of the discrimination medium
above the separator 7 is cut to a size of a product label or the
like, an extra portion therearound is removed, and the separator 7
is peeled, so that the discrimination medium can be applied to an
article.
Second Embodiment
[0057] FIG. 9 is a cross sectional view showing a discrimination
medium 1 of the Second Embodiment. For example, the discrimination
medium 1 can be used as a product label applied on a product or a
package of a product and used for discriminating the product. The
discrimination medium 1 has a laminated structure in which a
separator 7, an adhesive layer 6, a substrate 11, cholesteric
liquid crystal layer 10, an anchor layer 9, a breakable print
recording layer 4, a printed layer 3, and a protection layer 2 are
laminated in turn from beneath. When the discrimination medium 1 is
applied to a product or the like, the separator 7 is peeled from
the discrimination medium 1, and the discrimination medium 1 is
adhered thereto by the adhesive layer 6.
[0058] Next, a production method for the cholesteric liquid crystal
layer 10 will be explained hereinafter. For example, a low
molecular cholesteric liquid crystal is dissolved and held in a
polymerized monomer, so that cholesteric liquid crystals grow.
After that, the low molecular liquid crystals are joined by
photoreaction or thermal reaction, so that the molecular
orientation thereof is fixed, and the low molecular liquid crystal
is formed into a polymer thereof. As a result, raw liquid of
cholesteric liquid crystal is obtained. The raw liquid is applied
to a surface of polyethylene terephthalate (PET) to have a
predetermined thickness. The polyethylene terephthalate is the
substrate 11 and has a thickness of 50 .mu.m. The raw liquid is
oriented in a cholesteric orientation, and molecular orientation
thereof is fixed. In this case, for example, the cholesteric liquid
crystal has a uniform torsion pitch P extending in a molecular
layered direction thereof, and has a layered thickness of 2 .mu.m.
The cholesteric liquid crystal layer appropriately has a thickness
of about 0.5 to 5.0 .mu.m. In this example, the pitch p is
controlled such that the cholesteric liquid crystal layer 10
appears to be red when right-handed circularly polarized light
enters the cholesteric liquid crystal layer 10 and the viewing
angle is 0 degrees.
[0059] Regarding another method for obtaining raw liquid of
cholesteric liquid crystal, polymer thermotropic polymer liquid
crystal of branched-chain type or straight-chain type may be heated
to a temperature of the liquid crystal transition point thereof or
higher, so that a cholesteric liquid crystal structure thereof
grows, and may be then cooled to a temperature of the liquid
crystal transition point or lower, so that the molecular
orientation thereof is fixed. Alternatively, polymer lyotropic
liquid crystal of the branched-chain type or straight-chain type
may be oriented in a cholesteric orientation in a solvent, and the
solvent may be gradually evaporated, so that molecular orientation
thereof is fixed.
[0060] Regarding raw materials of the above materials, a
branched-chain type polymer having a liquid crystal forming group
in a branched-chain, for example, polyacrylate, polymethacrylate,
polysiloxane, or polymalonate may be used. Alternatively, a
straight-chain type polymer having a liquid crystal forming group
in a straight chain, for example, polyester, polyester amide,
polycarbonate, polyamide, or polyimide, may be used.
[0061] A thermal printer prints on the protection layer 2 of the
discrimination medium 1 of the Second Embodiment produced in the
above manner, so that a barcode pattern is formed. When the
discrimination medium 1' after the printing is viewed from the side
of the protection layer 2 under white light or the like, the
discrimination medium 1' appears to be red overall, so that the
barcode cannot be discriminated. However, when the discrimination
medium 1' is gradually inclined and the incident angle is
increased, as shown in FIG. 8, since the color of the removed
portion 8 gradually shifts to orange, green, blue, and violet in
turn, the removed portion 8 can be seen as the barcode.
[0062] When a film having a right-handed circular polarization
light selectivity is disposed on the protection layer 2 of the
discrimination medium 1' after the printing, the barcode cannot be
seen. When a film having a left-handed circular polarization light
selectivity is disposed on the protection layer 2 of the
discrimination medium 1' after the printing, the bar code can be
seen.
Third Embodiment
[0063] FIG. 10 is a cross sectional view showing a discrimination
medium 1 of the Third Embodiment. The discrimination medium 1 can
be the entirely or a portion of a product, for example, a card, a
security note, an exchange tickets for money, or a public game
voting ticket, and it can be used for discriminating whether or not
the product is authentic. The discrimination medium 1 has a
laminated structure which has a multilayer film 5 at a center
portion thereof, breakable print recording layers 4 on the upper
and lower sides of the multilayer film 5, and printed layers 3a and
3b on the upper and lower sides of the breakable print recording
layers 4. The discrimination medium 1 has protection layers 2
laminated on the upper and lower sides of printed layers 3a and 3b,
which are not shown in FIG. 10, if necessary. The printed layers 3a
and 3b can be different from each other in materials of which they
are formed, color, and pattern formed thereon. In order to
recognize the color of the multilayer film, printed color which is
as dark as possible so as to absorb light is preferably used.
Alternatively, a dark light absorption layer may be provided
between the printed layer and the breakable print recording layer.
A thermal printer can print different characters, different
symbols, or different patterns on both sides of the discrimination
medium 1 of the Third Embodiment.
Modification Example of First to Third Embodiments
[0064] An embossed portion may be provided to the multilayer film 5
or the cholesteric liquid crystal layer 10 by embossing or the
like, so that a transparent hologram-forming layer is provided.
When the multilayer film 5 is composed of a material on which it is
difficult to form an embossed portion, a hologram-forming layer may
be formed, if necessary. The upper surface or the lower surface of
the cholesteric liquid crystal layer may be subjected to
embossing.
[0065] When the hologram-forming layer is used as a reflecting
hologram, a reflecting hologram is composed of at least one
selected from the group of metal, oxide thereof, and nitride
thereof, or a metal compound, and it is formed by deposition,
sputtering, ion plating, electrolytic plating, electroless plating,
or the like. The metal is selected from the group consisting of Cr,
Ti, Fe, Co, Ni, Cu, Ag, A, Ge, Al, Mg, Sb, Pb, Pd, Cd, Bi, Sn, Se,
In, Ga, and Rb, etc. In this case, the reflecting hologram film is
provided between the multilayer film and the adhesive layer,
between the adhesive layer and the cholesteric liquid crystal
layer, or on the substrate 11. In the discrimination medium 1
having the hologram forming layer, a pattern can be formed on a
region of the character or the symbol after the printing, and the
color of the pattern changes depending on the viewing angle.
Modification of First to Third Embodiments
[0066] A cut may be provided at a portion of the discrimination
medium. In this discrimination medium, when the discrimination
medium is forcibly peeled from the article to reuse it, the
discrimination medium is broken due to the cut. Thus, the
discrimination medium cannot be reused. This structured
discrimination medium can be applied to a breakable discrimination
seal for determining whether or not a package has been
unsealed.
Another Modification of Embodiments
[0067] The discrimination medium favorably has an interlayer
peeling structure or a peeling breaking structure at least a
portion thereof. For example, it is favorable that interlayer
peeling easily occur in the cholesteric liquid crystal layer. For
example, when the discrimination medium is peeled from the article,
interlayer peeling favorably occurs in a layered structure of the
cholesteric liquid crystal layer 10 before the adhesion strength of
the adhesive layer 6 is lost. In this discrimination medium,
illegal reuse of the discrimination medium can be prevented. For
example, a control method for easy interlayer peeling of the
cholesteric liquid crystal layer can be performed by controlling
the temperature in production therefor.
[0068] It is preferable that in peeling of the adhesive layer from
the discrimination medium, a character or the like is transferred
to the article or the structure of the discrimination medium is
changed, so that traces by the peeling appear. A cut is formed to
the multilayer film or the cholesteric liquid crystal layer, and
the substrate, and the adhesive layer in shape of the characters
indicating "Unsealing". Alternatively, a partial peeling layer
having a thickness of 0.2 to 5 .mu.m is formed between the adhesive
layer or the multilayer film and the substrate in the shape of the
characters. In the above manners, the above adhesive layer is
formed. The partial peeling layer is composed of ink containing
silicone, fluorine compound, and wax, etc.
[0069] When this structured discrimination medium is peeled from
the article, separation occurs between the multilayer film or the
cholesteric liquid crystal layer, and the substrate, and the
adhesive layer, so that the characters are formed and remains on
the article. Alternatively, interlayer displacement occurs in the
partial peeling layer by stress in the peeling, and bubbles enter,
so that the feature of the discrimination medium changes in
appearance.
[0070] The breakable print recording layer can have a structure of
which a portion is lost when heating is performed thereon. For
example, a film composed of low melting point metal can be used as
the breakable print recording layer. When a portion of the film
composed of low melting point metal is heated by a head (thermal
head) of a thermal printer, the portion is locally melted, and the
melted material is moved to be absorbed therearound. As a result, a
structure in which low melting point metal is removed can be
obtained. A predetermined figure can be formed by using this
removed portion of the film.
[0071] One example of the above feature will be explained
hereinafter. FIG. 11 is a cross sectional view showing a
discrimination medium having an example of a breakable print
recording layer. In this example, a film composed of a low melting
point metal is used as the breakable print recording layer. For
example, deposited Sn can be used as the low melting point metal.
The low melting point metal preferably has a melting point of 300
degrees C. or less.
[0072] One example of a production method for the above example
will be explained hereinafter. The details of the multilayer film
and the adhesive layer are the same as those in the embodiments
described above.
[0073] First, a film composed of Sn as the breakable print
recording layer 4 is formed on a surface of the multilayer film 5
by vacuum deposition. For example, the film has a thickness of 0.4
.mu.m. The thickness is appropriately 0.1 to 1 .mu.m.
[0074] When the breakable print recording layer 4 is formed, the
protection layer 2 composed of optically transparent resin or the
like is applied thereon. A separator 7 having an adhesive layer 6
provided on a peeling surface thereof is prepared. Then, this
adhesive layer 6 is adhered to another surface on which the
multilayer film 5 is exposed. As a result, a structure shown in
FIG. 11A is obtained. The adhesive layer contains a black pigment
absorbing visible light and functions as a light absorption
layer.
[0075] After the structure shown in FIG. 11A is obtained, a thermal
printer prints on the protection layer 2. In the printing, melting
and deforming do not occur in the protection layer 2 by heat
locally applied thereto, and printing is performed on the breakable
print recording layer 4 which is a portion of the film composed of
Sn based on melting condition. As shown in FIG. 11B, a portion of
the film composed of Sn is lost or thinned by the printing. As a
result, a low melting point metal removed region 14 is formed such
that the film of Sn does not partially exist (or the film is seen
such that the film of Sn does not partially exist). This phenomenon
is understood as follows. That is, the portion of the film of Sn is
subjected to heating by the thermal head and is melted, and the
melted material is absorbed by the film of Sn therearound which has
a temperature which is lower than that of the melted portion, so
that the portion (low melting point metal removed region 14) which
is seen such that the film of Sn does not partially exist is
formed.
[0076] The temperature of the thermal head, the distance between
the thermal head and the protection layer 2, the material of the
protection layer 2, the thickness of the protection layer 2, the
material of the breakable print recording layer 4, and the
thickness of the breakable print recording layer 4 influence the
effects of the printing which can obtain the above phenomenon.
Therefore, printing conditions are preferably obtained by
tests.
[0077] Optical functions in the case in which the character is
formed by using the low melting point metal removed region 14 will
be explained hereinafter. In this case, when the surface of the
protection layer 2 is viewed, metallic luster of Sn is seen on a
region other than the low melting point metal removed region 14.
The film of Sn does not exist on the low melting point metal
removed region 14, and the multilayer film can be seen
therefrom.
[0078] Therefore, when the protection layer 2 is viewed from the
vertical direction, the character and the figure formed by the low
melting point metal removed region 14 is seen on the metallic
luster surface. When the discrimination medium is inclined overall,
the character and the figure exhibit a blue shift, and the color
thereof changes. On the other hand, the region other than the low
melting point metal removed region 14 is seen such that reflection
light reflected by the metallic luster surface is seen when the
viewing angle is changed. As a result, the low melting point metal
removed region 14 exhibiting a blue shift is distinguished. Thus,
the optical functions of the discrimination medium can be
obtained.
[0079] The structure shown in FIG. 11 is superior in that the
structure having the protection layer 2 remaining on the surface
can be obtained. Therefore, when processes are not performed after
the printing, the observing surface can be covered with the
protection layer. In the structure shown in FIG. 11, the
cholesteric liquid crystal layer can be used instead of the
multilayer film. In this case, the cholesteric liquid crystal layer
can be seen from the low melting point metal removed region 14, and
the figure can be displayed by using the optical characteristics of
the cholesteric liquid crystal layer.
[0080] When the cholesteric liquid crystal layer is used instead of
the multilayer film 5, the cholesteric liquid crystal layer is
viewed via an optical filter allowing a predetermined circularly
polarized light to selectively pass therethrough, so that unique
optical functions can be obtained.
[0081] For example, in this case, reference numeral 5 denotes the
cholesteric liquid crystal layer, and the cholesteric liquid
crystal layer selectively reflects right-handed circularly
polarized red light. In this case, when the discrimination medium
shown in FIG. 11 is viewed via an optical filter allowing a
right-handed circularly polarized light to selectively pass
therethrough, red reflected light from the cholesteric liquid
crystal layer via the low melting point metal removed region 14 is
seen. Therefore, the figure formed by the low melting point metal
removed region 14 is seen to be red.
[0082] On the other hand, when the discrimination medium shown in
FIG. 11 is viewed via an optical filter allowing a left-handed
circularly polarized light to selectively pass therethrough, red
reflected light from the cholesteric liquid crystal layer via the
low melting point metal removed region 14 is blocked by the optical
filter. Therefore, the discrimination medium is different in
appearance between the case in which the viewing is performed via
the optical filter allowing a right-handed circularly polarized
light to selectively pass therethrough and the case in which the
viewing is performed via the optical filter allowing a left-handed
circularly polarized light to selectively pass therethrough. Thus,
the visual discrimination can be performed by using two kinds of
the optical filters. The determination of the authenticity can be
effectively performed by using the visual discrimination.
[0083] In the structure shown in FIG. 11, the multilayer film 5 or
the cholesteric liquid crystal layer which is used instead of the
multilayer film 5 may be subjected to hologram working. Thus, the
figure formed by the low melting point metal removed region 14 can
be combined with the figure of the hologram.
[0084] A thin printed layer may be formed on the film of Sn which
is used as the breakable print recording layer 4. For example, when
a thin and yellow ink is printed on the film of Sn, luster of Sn is
seen via the white layer, and gold color can be substantially seen.
The color and the luster of the breakable print recording layer 4
can be controlled by forming this thin film.
INDUSTRIAL APPLICABILITY
[0085] The present invention can be applied to techniques for
determining whether or not passports, documents, various cards,
passes, bills, exchange tickets for money, bonds, security notes,
gift certificates, pictures, tickets, public game voting tickets,
recording media in which sound data and image data are recorded,
recording media in which computer software is recorded, various
products, and packages of the products are authentic. The
discrimination medium of the present invention can be used for
opening discrimination seals for discriminating whether or not a
package has been unsealed.
* * * * *