TECHNICAL FIELD
[0001]
The present invention relates to an anti-counterfeiting
multiple-image display body for ID cards, passports, and
banknotes.
BACKGROUND ART
[0002]
It is desirable that counterfeitingbe difficult for
items including negotiable instruments such as coupons and
checks;cards such as credit cards, cash cards, and ID cards;
certificates such as driver's licenses and passports; brand
name products; electronic gadgets; and personal
authentication media. Such itemsmay thus use display bodies
that have superior anti-counterfeiting effects.
[0003]
Such display bodies often include fine structures (i.e.,
optical elements) such as diffraction gratings, holograms,
and lens arrays. The optical elements, for example, cause
dynamic pattern changes when the observation angle changes.
This hinders analysis and counterfeiting. Accordingly, such
optical elements have a relatively high anti-counterfeiting
effect.
[0004]
3
In the prior art, there are image display bodies that
use optical elements such as those described above. For
example, patent document 1 describes an image display body
that stacks lens array layer and an icon layer to produce
continuous movement and create a sense of depth. Such an
image display body has been put to practical use due to its
high anti-counterfeiting effect.
[0005]
The image display body of patent document 1 is an
extremely thin film of 50 μm or lessto allow for
applications that watermark paper used for currency. This
requires extremely high precision for the focal distance of
lenses, the size of the lens array, and the icon size so
that a high anti-counterfeiting effect can be obtained.
[0006]
However, with a multiple-image display body including a
lens array in a surface layer, contamination of the lens
layer in the outermost surface layer by a liquid such as oil
or a chemical would result in defects such as loss of the
lens effect (condensing effect, magnifying effect) and loss
ofthe desired continuous movement and depthin a display.
Such a defect may lead to anauthentication failure during
actual use of ID cards, passports, and banknotes.
[0007]
To resolve this defect, patent document 2 proposes a
stacked display body that does not use lenses. The display
body of patent document 2 is a stacked display body that
includes a transmittive "line tone barrier layer," a "spacer
layer," and a "multiple-image formation layer." The
multiple-image formation layer is divided into multiple
images at a line tone pitch. Further, the display body is a
multiple-image display body of a parallax barrier type that
allows for the appearance of multiple images recorded on the
4
"multiple-image formation layer" when viewed over the "line
tone barrier layer" in accordance with the observed angle.
[0008]
The structure of patent document 2 does not cause a loss
in the desired continuous movement and depthof a display
even when the uppermost layer is contaminated by a liquid
such as oil or a chemical. This is sufficient for actual use
in ID cards, passports, or banknotes.
[0009]
However, the outermost "line tone barrier layer"
decreases the light intensity. Thus, it is difficult for the
multiple-image display body to show the "multiple images" of
a lower layer with sufficient contrast.
Further, authenticationthat uses transmission light(for
example, authentication using watermark) obtains
satisfactory contrast. This allows the multiple-image
display body to obtain a display effect that produces
continuous movement and depth. However, in authentication
that uses reflection light, insufficient light intensity
lowers the contrast of the lower layer images. This causes
difficulties in authentication.
PRIOR ART DOCUMENTS
PATENT DOCUMENTS
[0010]
Patent Document 1: Japanese National Phase Laid-Open
Patent Publication No. 2009-543138
Patent Document 2: WO2011/007343A1
SUMMARY OF THE INVENTION
5
PROBLEMS THAT ARE TO BE SOLVED BY THE INVENTION
[0011]
It is an object of the present invention to provide a
multiple-image display body that allows a sufficient
displayto be obtained even when the outermost layer is
contaminated with a liquid and also allows for sufficient
image recognition when observed with only reflection light.
MEANS FOR SOLVING THE PROBLEM
[0012]
One aspect of a multiple-image display body according to
the present invention includes a spacer layer including a
first surface and a second surface opposite to the first
surface. The spacer layer has the form of a thin film. A
line tone barrier layer is stacked on the first surface of
the spacer layer. A multiple-image formation layer is
stacked on the second surface of the spacer layer. The line
tone barrier layer includes first regions, which transmit
electromagnetic waves in at least some wavelength ranges,
and second regions, which absorb electromagnetic waves in at
least some wavelength ranges. The second regions in a
surface contacting the spacer layer have substantially the
same width and shape, and the second regions are arranged at
equal intervals sandwiching at least portions of the first
regions to form a line tone pattern. The multiple-image
formation layer includes images that are visible when
observed from specific angles over the first regions of the
line tone barrier. Each of the images includes a third
region, which scatters electromagnetic waves in at least
some wavelength ranges, and a fourth region, which absorbs
electromagnetic waves in at least some wavelength ranges.
The image is formed by a contrast resulting from an area
ratio of the third region and the fourth region.
6
[0013]
Another aspect of a multiple-image display body
according to the present invention includes a spacer layer
including a first surface and a second surface opposite to
the first surface. The spacer layer has the form of a thin
film. A line tone barrier layer is stacked on the first
surface of the spacer layer. A multiple-image formation
layer is stacked on the second surface of the spacer layer.
An electromagnetic wave absorbing layer is stacked on a
surface of the multiple-image formation layer opposite to
the spacer layer. The line tone barrier layer includes
first regions, which transmit electromagnetic waves in at
least some wavelength ranges, and second regions, which
absorb electromagnetic waves in at least some wavelength
ranges. The second regions in a surface contacting the
spacer layer have substantially the same width and shape,
and the second regions are arranged at equal intervals
sandwiching at least portions of the first regions to form a
line tone pattern. The multiple-image formation layer
includes images that are visible when observed from specific
angles over the first regions of the line tone barrier.
Each of the images includes a third region, which scatters
electromagnetic waves in at least some wavelength ranges,
and a fifth region, which transmits electromagnetic waves in
at least some wavelength ranges. The image is formed by a
contrast resulting from an area ratio of the third region
and the fifth region. The electromagnetic wave absorbing
layer absorbs electromagnetic waves transmitted in order
from the line tone barrier to the spacer layer and then to
the fifth region.
[0014]
A further aspect of a multiple-image display body
according to the present inventionincludes a spacer layer
including a first surface and a second surface opposite to
7
the first surface. The spacer layer has the form of a thin
film. A line tone barrier layer is stacked on the first
surface of the spacer layer. A multiple-image formation
layer is stacked on the second surface of the spacer layer.
An electromagnetic wave scattering layer is arranged on a
surface of the multiple-image formation layer opposite to
the spacer layer. The line tone barrier layer includes
first regions, which transmit electromagnetic waves in at
least some wavelength ranges, and second regions, which
absorb electromagnetic waves in at least some wavelength
ranges. The second regions in a surface contacting the
spacer layer have substantially the same width and shape,
and the second regions are arranged at equal intervals
sandwiching at least portions of the first regions to form a
line tone pattern. The multiple-image formation layer
includes images that are visible when observed from specific
angles over the first regions of the line tone barrier.
Each of the images includes a sixth region, which absorbs
electromagnetic waves in at least some wavelength ranges,
and a seventh region, which transmits electromagnetic waves
in at least some wavelength ranges. The image is formed by
a contrast resulting from an area ratio of the sixth region
and the seventh region. The electromagnetic wave scattering
layer scatters electromagnetic waves transmitted in order
from the line tone barrier to the spacer layer and then to
the seventh region.
[0015]
Preferably, the third region has a corrugated structure,
and the corrugated structure includes recesses filled with
electromagnetic wave scattering particles that scatter
electromagnetic waves in at least some wavelength ranges.
Preferably, the fourth region has a corrugated
8
structure, and the corrugated structure includes recesses
filled with electromagnetic wave absorbing particles that
absorb electromagnetic waves in at least some wavelength
ranges.
[0016]
Preferably, the sixth region has a corrugated structure,
and the corrugated structure includes recesses filled with
electromagnetic wave absorbing particles that absorb
electromagnetic waves in at least some wavelength ranges.
Preferably, the particles which the recesses are filled
with are at least one of pigments, dyes, and metal
nanoparticles.
[0017]
Preferably, the particles which the recesses are filled
with are core shell particles including cores of fine
pigments and shells of a thermoplastic or thermosetting
resin.
Preferably, the third region includes a corrugated
structure, which is undulated and has a scattering
characteristic, and an electromagnetic wave reflection
layer, which is arranged on a surface of the corrugated
structure.
[0018]
Preferably, the fourth region includes a corrugated
structure, which is undulated and has an absorbing
characteristic, and an electromagnetic wave reflection
layer, which is arranged on a surface of the corrugated
structure.
EFFECT OF THE INVENTION
[0019]
9
The present invention allows a sufficient display to be
obtained even when the outermost layer is contaminated with
a liquid and also allows for sufficient image recognition
when observed with only reflection light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020]
Fig. 1 is a cross-sectional view of a multiple-image
display body according to a first embodiment of the present
invention.
Fig. 2 is a front view of a multiple-image formation
layer in the multiple-image display body shown in Fig. 1.
Fig. 3A is a front view of a first image arranged in the
multiple-image formation layer shown in Fig. 2.
Fig. 3B is a front view of a second image arranged in
the multiple-image formation layer shown in Fig. 2.
Fig. 3C is a front view of a third image arranged in the
multiple-image formation layer shown in Fig. 2.
Fig. 4 is a cross-sectional view showing one example of
a third region in the first, second, and third images of
Figs. 3A to 3C.
Fig. 5 is a cross-sectional view showing another example
of the third region in the first, second, and third images
of Figs. 3A to 3C.
Fig. 6 is a cross-sectional view showing one example of
a fourth region in the first, second, and third images of
Figs. 3A to 3C.
Fig. 7 is a cross-sectional view showing another example
of the fourth region in the first, second, and third images
of Figs. 3A to 3C.
Fig. 8 is a cross-sectional view of a multiple-image
display body according to a second embodiment of the present
invention.
10
Fig. 9 is a front view of a multiple-image formation
layer in the multiple-image display body shown in Fig. 8.
Fig. 10A is a front view of a first image arranged in
the multiple-image formation layer shown in Fig. 9.
Fig. 10B is a front view of a second image arranged in
the multiple-image formation layer shown in Fig. 9.
Fig. 10C is a front view of a third image arranged in
the multiple-image formation layer shown in Fig. 9.
Fig. 11 is a cross-sectional view showing one example of
a third region in the first, second, and third images of
Figs. 10A to 10C.
Fig. 12 is a cross-sectional view showing another
example of the third region in the first, second, and third
images of Figs. 10A to 10C.
Fig. 13 is a cross-sectional view of a multiple-image
display body according to a third embodiment of the present
invention.
Fig. 14 is a front view of a multiple-image formation
layer in the multiple-image display body shown in Fig. 13.
Fig. 15A is a front view of a first image arranged in
the multiple-image formation layer shown in Fig. 14.
Fig. 15B is a front view of a second image arranged in
the multiple-image formation layer shown in Fig. 14.
Fig. 15C is a front view of a third image arranged in
the multiple-image formation layer shown in Fig. 14.
Fig. 16 is a cross-sectional view showing one example of
a sixth region in the first, second, and third images of
Figs. 15A to 15C.
Fig. 17 is a cross-sectional view showing another
example of the sixth region in the first, second, and third
images of Figs. 15A to 15C.
Fig. 18A is a schematic diagram showing the
characteristics of a multiple-image display body according
11
to the present invention.
Fig. 18B is a schematic diagram showing the
characteristics of a multiple-image display body according
to the present invention.
Fig. 18C is a schematic diagram showing the
characteristics of a multiple-image display body according
to the present invention.
Fig. 18D is a schematic diagram showing the
characteristics of a multiple-image display body according
to the present invention.
Fig. 19 is a front view illustrating a multiple-image
formation layer formed in the first, second, and third
embodiments.
EMBODIMENTS OF THE INVENTION
[0021]
Embodiments of the present invention will now be
described in detail with reference to the drawings.
First Embodiment
Fig. 1 is a cross-sectional view showing a first
embodiment of a multiple-image display body according to the
present invention.
[0022]
A multiple-image display body 1 includes a spacer layer
2, which is a thin film, a line tone barrier layer 3, which
is stacked on a first surface (upper surface) of the spacer
layer 2, and a multiple-image formation layer 4, which is
stacked on a second surface (lower surface) of the spacer
layer 2.
[0023]
The line tone barrier layer 3 includes first regions 5,
12
which transmit at least some electromagnetic waves, and
second regions 6, which have a predetermined thickness and
absorb at least some electromagnetic waves. The first
regions 5 and the second regions 6 are alternately arranged
in a surface that contacts the spacer layer 2 to form a line
tone pattern. In particular, the second regions 6 are
rectangular and elongated in a direction orthogonal to the
plane of Fig. 1. The second regions 6 have substantially the
same width on the surface contacting the spacer layer 2.
Further, the second regions 6 are arranged at equal
intervals so as to sandwich at least part of the surface of
each first region 5 that is in contact with the spacer layer
2. Thus, the second regions 6 form a line tone pattern.
Each second region 6 has a quadrangular cross-section but is
not necessarily limited to a quadrangular cross-section.
[0024]
The multiple-image formation layer 4 includes "multiple
images" on the surface joined with the second surface of the
spacer layer 2. The multiple images are each visible when
observed from a number of specified angles over the "first
regions 5" of the line tone barrier layer 3. More
specifically, three images, namely, a first image 7, a
second image 8, and a third image 9, are alternately
repeated and consolidated as a group of lineson planes
extending orthogonal to the plane of Fig. 1.
[0025]
The first image 7 is visible when observed along light
path P1. The second image 8 is visible when observed along
light path P2. The third image 7 is visible when observed
along light path P3.
[0026]
Fig. 2 is a front view of the multiple-image formation
layer 4 shown in Fig. 1.
13
The multiple-image formation layer 4 is configured to
form an image with the contrast obtained from the area ratio
of a third region 10, which scatters electromagnetic waves
in at least some of the wavelength ranges, and a fourth
region 11, which absorbs electromagnetic waves in at least
some of the wavelength ranges.
[0027]
Figs. 3A to 3C are front views of the first to third
images 7 to 9 in the multiple-image formation layer 4. The
first image 7, the second image 8, and the third image 9 are
each formed by linesextending parallel to one another.
[0028]
In the multiple-image formation layer 4 of Fig. 2, the
lines forming the first image 7, the lines forming the
second image 8, and the lines forming the third image 9 are
alternately and repeatedly laid out so that the three images
7, 8, and 9 are consolidated as a group of lines. The three
images 7, 8, and 9 may be separated as shown in Figs. 3A to
3C. The first image 7, the second image 8, and the third
image 9 each include the third region 10, which scatters
electromagnetic waves in at least some wavelength ranges,
and the fourth region 11, which absorbs electromagnetic
waves in at least some wavelength ranges. Further, the first
image 7, the second image 8, and the third image 9 are each
formed by the contrast obtained from the area ratio of the
third region 10 and the fourth region 11.
[0029]
Fig. 4 is a cross-sectional view of a third region 10a
and illustrates one example of the third region 10.
The third region 10a needs to function to scatter
electromagnetic waves in at least some wavelength ranges.
14
Thus, as shown in Fig. 4, the third region 10a has a
corrugated structure 12 and includes electromagnetic wave
scattering particles 13, which scatter electromagnetic
waves. Recesses of the corrugated structure 12 are filled
with the electromagnetic wave scattering particles 13.
[0030]
The scattering of electromagnetic waves caused by the
electromagnetic wave scattering particles 13 is classified
in accordance with the size parameter into Rayleigh
scattering, Mie scattering, and diffraction scattering. The
size parameter distribution that is employed scatters the
desired wavelength range in a desired manner.
[0031]
Fig. 5 is a cross-sectional view of a third region 10b
illustrating another example of the third region 10.The
third region 10b needs to function to scatter
electromagnetic waves in at least some wavelength ranges.
Thus, the third region 10b has a scattering corrugated
structure 14, which is, for example, undulated, and an
electromagnetic wave reflection layer 15, which is stacked
on the surface of the corrugated structure 14.
[0032]
Fig. 6 is a cross-sectional view of a fourth region 11a
illustrating one example of the fourth region 11.
The fourth region 11a needs to function to absorb
electromagnetic waves in at least some wavelength ranges.
Thus, the fourth region 11a includes a corrugated structure
16 and electromagnetic wave absorbing particles 17. Recesses
of the corrugated structure 16 are filled with the
electromagnetic wave absorbing particles 17.
[0033]
The electromagnetic wave absorbing particles 17 may be
15
selected from pigments, dyes, metal particles, and the like
that absorb electromagnetic waves in the desired wavelength
range.
Fig. 7 is a cross-sectional view of a fourth region 11b
illustrating another example of the fourth region 11.
[0034]
The fourth region 11b needs to function to absorb
electromagnetic waves in at least some wavelength ranges.
Thus, the fourth region 11b includes a corrugated structure
18 having electromagnetic wave absorption characteristics,
that is, a low reflective structure or a non-reflective
structure. Further, the fourth region 11b includes an
electromagnetic wave reflection layer 19 that is stacked on
the surface of the corrugated structure 18.
Layers forming multiple-image display body
Spacer layer 2
The material forming the spacer layer 2 may be a plastic
film of polyethylene terephthalate (PET), polyethylene
naphthalate(PEN), triacetyl cellulose (TAC), vinyl chloride,
polycarbonate, acrylic, polypropylene (PP), poly ethylene
(PE), or the like. However, the spacer layer 2 is not
limited to these materials. Further, the spacer layer 2 may
be a film of a thermoplastic resin, a thermosetting resin,
or an electromagnetic wave curable resin. The spacer layer 2
needs to function to send the light transmitted through the
line tone barrier layer 3 to the multiple-image formation
layer 4. Thus, it is desirable that the transparency of the
spacer layer 2 be as high as possible. Further, the spacer
layer 2 functions as a spacer that keeps a desired distance
16
between the line tone barrier layer 3 and the multiple-image
formation layer 4.
Line tone barrier layer 3
In the line tone barrier layer 3, linear electromagnetic
wave transmission regions (corresponding to first regions 5)
and linear electromagnetic wave absorption regions
(corresponding to second regions 6) are alternatively and
continuously laid out on a plane. In the multiple-image
formation layer 4, when n represents the width of each line
forming a certain image, and m represents the number of
images, the following expressions are satisfied.
[0035]
line width of "electromagnetic wave absorption region"
in line tone barrier layer 3 = (m-1) × n (expression 1)
line width of "electromagnetic wave transmission region"
in line tone barrier layer 3 = n (expression 2)
"thickness" of spacer layer 2 ≥ mn (expression 3)
"image number" in multiple-image formation layer 4
required to show continuous change ≥ 3 (expression 4)
When the four expressions are satisfied, the effect in
which the images 7 to 9 change continuously may be obtained
over the line tone barrier layer 3.
[0036]
When the spacer layer 2 has a thickness that is greater
than or equal to the line tone pitch of the "line tone
barrier layer 3," the images 7 to 9 become visible at a
slight angle of vision. This improves the visibility.
17
When the multiple-image display body is used as a
security film watermarked on paper, the "thickness" of the
spacer layer 2 obtained in expression 3 needs to be 50 μm or
less and, further preferably, 25 μm or less. The thickness
of a film watermarked on paper is related to the formation
of creases during offset printing or intaglio printing
during paper manufacturing or during a subsequent process.
This affects the quality. Thus, it is preferred that the
film be as thin as possible. In this case, however, high
precision is required for the "line tone barrier layer 3"
and the "images 7 to 9" to satisfy the four expressions.
[0037]
For example, when the "thickness" of the spacer layer 2
is 25 μm and the "image number" is 3, that is, when m=3 and
mn=25 μm are satisfied, n=8.3 μm is satisfied. Thus, the
line width of the "electromagnetic wave absorption region"
in the line tone barrier layer 3 obtained from expression 1
is 16.6 μm, and the line width of the "electromagnetic wave
transmission region" in the line tone barrier layer 3
obtained from expression 2 is 8.3 μm. Further, the line
width of each line forming any single image in the multipleimage
formation layer 4 is 8.3 μm. Thus, high-contrast lines
having a resolution of 8.3 μm is necessary in the line tone
barrier layer 3 and the images 7 to 9.
[0038]
Non-uniform transfer of a cell pattern shape during the
transfer of ink, the blotting of ink, and the splattering of
ink usually occur in offset printing, gravure printing,
relief printing, inkjet printing, and the like. Thus, it is
difficult to print such high-contrast lines with high
precision.
[0039]
18
Thus, in the "line tone barrier layer 3" and the
"multiple-image formation layer 4" of the present invention,
corrugated structures (e.g., corrugated structures 12 and
16) having accurate patterns are duplicated by imprinting
highly precise pixels of 10 μm or less. Then, for example,
the recesses of the corrugated structureare filled with the
"electromagnetic wave scattering pigments" or
"electromagnetic wave absorbing pigments."
[0040]
When the "electromagnetic wave absorption region (second
region)" of the line tone barrier layer 3 includes a metal
reflection layer of aluminum or the like, it becomes
difficult to view the reflection light of the images in the
multiple-image formation layer 4 with the reflection light
of the line tone barrier layer 3. Accordingly, the line tone
of the line tone barrier layer 3 need to use structural
color or pigment that absorbs electromagnetic waves.
Multiple-image formation layer 4
In the multiple-image formation layer 4, the separated
lines are consolidated. The images 7 to 9 are shown by the
contrast obtained from the combination of the
electromagnetic wave scattering regions and transmission
regions, the combination of the electromagnetic wave
absorption regions and transmission regions, or the
combination of electromagnetic wave scattering regions and
electromagnetic wave absorption regions.
Second Embodiment
Fig. 8 is a cross-sectional view showing a second
embodiment of a multiple-image display body according to the
19
present invention.
[0041]
A multiple-image display body 20 includes thespacer
layer 2, theline tone barrier layer 3, which is stacked on
the first surface of the spacer layer 2, and the multipleimage
formation layer 4 and an electromagnetic wave
absorbing layer 21, which are sequentially stacked on the
second surface (lower surface) of the spacer layer 2.
[0042]
The line tone barrier layer 3 includes the first regions
5, which transmit at least some electromagnetic waves, and
the second regions 6, which absorb at least some
electromagnetic waves. The second regions 6 are rectangular
and elongated in a direction orthogonal to the plane of Fig.
8. The second regions 6 have substantially the same width on
the surface contacting the spacer layer 2. Further, the
second regions 6 are arranged at equal intervals so as to
sandwich at least part of the surface of each first region 5
that is in contact with the spacer layer 2. Thus, the second
regions 6 form a line tone pattern. That is, the first
regions 5 and the second regions 6 are alternately arranged
on the surface that contacts the spacer layer 2 to form a
line tone pattern.
[0043]
The multiple-image formation layer 4 includes "multiple
images" on the surface joined with the second surface of the
spacer layer 2. The multiple images are each visible when
observed from a number of specified angles over the "first
regions 5" of the line tone barrier layer 3. More
specifically, three images, namely, a first image 22, a
second image 23, and a third image 24, are alternately
repeated and consolidated as a group of lines on planes
extending orthogonal to the plane of Fig. 8.
20
[0044]
The first image 22 is visible when observed along light
path P4. The second image 23 is visible when observed along
light path P6. The third image 24 is visible when observed
along light path P5.
[0045]
The layers 2, 3, and 4 of the multiple-image display
body 20 in the second embodiment have been described in
detail in the first embodiment and thus will not be
described below.
It is preferred that the electromagnetic wave absorbing
layer21 include a corrugated structure that absorbs
electromagnetic waves or include electromagnetic wave
absorbing particles as described above. The electromagnetic
wave absorbing layer 21 absorbs electromagnetic waves
transmitted through the multiple-image formation layer 4.
[0046]
Fig. 9 is a front view of the multiple-image formation
layer 4 shown in Fig. 8.
The multiple-image formation layer 4 forms an image with
the contrast obtained from the area ratio of a third region
25, which scatters electromagnetic waves in at least some of
the wavelength ranges, and a fifth region 26, which
transmits electromagnetic waves in at least some of the
wavelength ranges.
[0047]
Figs. 10A to 10C are front views of the three images 22
to 24 in the multiple-image formation layer 4. The first
image 22, the second image 23, and the third image 24 are
each formed by lines extending parallel to one another.
[0048]
In the multiple-image formation layer 4 of Fig. 9, the
21
lines forming the first image 22, the lines forming the
second image 23, and the lines forming the third image 24
are alternately and repeatedly laid out so that the three
images are consolidated as a group of lines. The three
images 22, 23, and 24 may be separated as shown in Figs. 10A
to 10C. The first image 22, the second image 23, and the
third image 24 each include the third region 25, which
scatters electromagnetic waves in at least some wavelength
ranges, and the fifth region 26, which transmits
electromagnetic waves in at least some wavelength ranges. An
image is formed with the contrast obtained from the area
ratio of the third region25 and the fifth region 26.
[0049]
Fig. 11 is a cross-sectional view of a third region 25a
and illustrates one example of the third region 25.
The third region 25a needs to function to scatter
electromagnetic waves in at least some wavelength ranges.
Thus, the third region 25a has a corrugated structure27 and
includes electromagnetic wave scattering particles 28.
Recesses of the corrugated structure27 are filled with the
electromagnetic wave scattering particles 28.
[0050]
The scattering of electromagnetic waves caused by the
electromagnetic wave scattering particles 28 is classified
in accordance with the size parameter into Rayleigh
scattering, Mie scattering, and diffraction scattering. The
size parameter distribution that is employed scatters the
desired wavelength range in a desired manner.
[0051]
Fig. 12 is a cross-sectional view of a third region 25b
illustrating another example of the third region 25. The
third region 25b needs to function to scatter
22
electromagnetic waves in at least some wavelength ranges.
Thus, the third region 25b has a scattering corrugated
structure 29, which is, for example, undulated, and an
electromagnetic wave reflection layer 29', which is stacked
on the surface of the corrugated structure 29.
Third Embodiment
Fig. 13 is a cross-sectional view showing a third
embodiment of a multiple-image display body according to the
present invention.
[0052]
A multiple-image display body 30 includes the spacer
layer 2, the line tone barrier layer 3, which is stacked on
the first surface of the spacer layer 2, and the multipleimage
formation layer 4 and an electromagnetic wave
scattering layer 31, which are sequentially stacked on the
second surface (lower surface) of the spacer layer 2.
[0053]
The line tone barrier layer 3 includes the first regions
5, which transmit at least some electromagnetic waves, and
the second regions 6, which absorb at least some
electromagnetic waves. The second regions 6 are rectangular
and elongated in a direction orthogonal to the plane of Fig.
13. The second regions 6 have substantially the same width
on the surface contacting the spacer layer 2. Further, the
second regions 6 are arranged at equal intervals so as to
sandwich at least part of the surface of each first region 5
that is in contact with the spacer layer 2. Thus, the second
regions 6 form a line tone pattern. That is, the first
regions 5 and the second regions 6 are alternately arranged
on the surface that contacts the spacer layer 2 to form a
line tone pattern. Each second region 6 has a quadrangular
23
cross-section but is not necessarily limited to a
quadrangular cross-section.
[0054]
The multiple-image formation layer 4 includes "multiple
images" on the surface joined with the second surface of the
spacer layer 2. The multiple images are each visible when
observed from a number of specified angles over the "first
regions 5" of the line tone barrier layer 3. More
specifically, three images, namely, a first image 32, a
second image 33, and a third image 34, are alternately
repeated and consolidated as a group of lines on planes
extending orthogonal to the plane of Fig. 13.
[0055]
The first image 32 is visible when observed along light
path P7. The second image 33 is visible when observed along
light path P9. The third image 34 is visible when observed
along light path P8.
[0056]
The layers 2, 3, and 4 of the multiple-image display
body 30 in the third embodiment have been described in
detail in the first embodiment and thus will not be
described below.
[0057]
It is preferred that the electromagnetic wave scattering
layer 31 include a corrugated structure that scatters
electromagnetic waves or include electromagnetic wave
scattering particles as described above. The electromagnetic
wave scattering layer 31 scatters electromagnetic waves
transmitted through the multiple-image formation layer 4.
[0058]
Fig. 14 is a front view of the multiple-image formation
layer 4 shown in Fig. 13.
24
The multiple-image formation layer 4 forms an image with
the contrast obtained from the area ratio of a sixth region
35, which absorbs electromagnetic waves in at least some of
the wavelength ranges, and a seventh region 36, which
transmits electromagnetic waves in at least some of the
wavelength ranges.
[0059]
Figs. 15A to 15C are front views of the three images 32
to 34 in the multiple-image formation layer 4. The first
image 32, the second image 33, and the third image 34 are
each formed by lines extending parallel to one another.
[0060]
In the multiple-image formation layer 4 of Fig. 14, the
lines forming the first image 32, the lines forming the
second image 33, and the lines forming the third image 34
are alternately and repeatedly laid out so that the three
images are consolidated as a group of lines. The three
images 32, 33, and 34 may be separated as shown in Figs. 15A
to 15C. The first image 32, the second image 33, and the
third image 34 each include the sixth region 35, which
absorbs electromagnetic waves in at least some wavelength
ranges, and the seventh region 36, which transmits
electromagnetic waves in at least some wavelength ranges. An
image is formed with the contrast obtained from the area
ratio of the sixth region35 and the seventh region 36.
[0061]
Fig. 16 is a cross-sectional view of a sixth region 35a
illustrating one example of the sixth region 35.
The sixth region 35a needs to function to absorb
electromagnetic waves in at least some wavelength ranges.
Thus, the sixth region 35a includes a corrugated structure
37 and electromagnetic wave absorbing particles 38. Recesses
25
of the corrugated structure 37 are filled with the
electromagnetic wave absorbing particles 38.
[0062]
The electromagnetic wave absorbing particles 38 may be
selected from pigments, dyes, metal particles, and the like
that absorb electromagnetic waves in the desired wavelength
range.
Fig. 17 is a cross-sectional view of a sixth region 35b
illustrating another example of the sixth region 35. The
sixth region 35b needs to function to absorb electromagnetic
waves in at least some wavelength ranges. Thus, the sixth
region 35b includes a corrugated structure 39 having
electromagnetic wave absorption characteristics, that is, a
low reflective structure or a non-reflective structure.
Further, the sixth region 35b includes an electromagnetic
wave reflection layer 39' that is stacked on the surface of
the corrugated structure 39.
[0063]
Figs. 18A to 18D are schematic diagrams showing how a
multiple-image display according to the present invention is
observed.
First, referring to Fig. 18A, an observation condition
82a is set in which the multiple-image display bodies 1, 20,
and 30 are slightly tilted toward an observation side from a
direction orthogonal to a horizontal line of sight of an
observer 81. Under this observation condition 82a, the
observer 81 observes a first image 83a, which is shown at
the right side of the drawing, from the line tone barrier
layer 3.
[0064]
Then, referring to Fig. 18B, an observation condition
26
82b is set in which the multiple-image display bodies 1, 20,
and 30 are arranged in a direction orthogonal to a
horizontal line of sight of the observer 81. Under this
observation condition 82b, the observer 81 observes a second
image 83b, which is shown at the right side of the drawing,
from the line tone barrier layer 3.
[0065]
Further, referring to Fig. 18C, an observation condition
82c is set in which the multiple-image display bodies 1, 20,
and 30 are slightly tilted away from the observation side in
a direction orthogonal to a horizontal line of sight of the
observer 81. Under this observation condition 82b, the
observer 81 observes a third image 83c, which is shown at
the right side of the drawing, from the line tone barrier
layer 3.
[0066]
Further, referring to Fig. 18D, an observation condition
82d is set in which the multiple-image display bodies 1, 20,
and 30 are almostlaid down away from the observation side in
a direction orthogonal to a horizontal line of sight of the
observer 81. Under this observation condition 82d, the
observer 81 observes the first image 83a, which is shown at
the right side of the drawing, from the line tone barrier
layer 3.
[0067]
A change in the observation angle of the multiple-image
display bodies 1, 20, and 30 changes the image. This allows
for the observation of changes in an image including
continuous movement.
Layer structure, used material, and manufacturing method
of multiple-image display bodies 1, 20, and 30
27
Details of method for forming corrugated structurefilled
with electromagnetic wave scattering particles or
electromagnetic wave absorbing particles
Representative processes for continuously duplicating
vast amounts of molded resin products having corrugated
patterns that form the corrugated structures 12, 16, 27, and
37 (hereafter, referred to as the corrugated structure 12
for the sake of brevity) includea"hot embossing process,"
"casting process," "photopolymer process," and the like.
[0068]
Among these processes, the "photopolymer process" (2P
process, photosensitive resin process) is a process that
pours radiation-curable resin into between a relief mold
(duplication mold of fine corrugated pattern) and a flat
base material (plastic film etc.), cures the radiationcurable
resin, and then removes the cured film together with
a substrate from the duplication mold. This obtains a highly
precise fine corrugated pattern. Further, an optical element
obtained through such a process has a better corrugated
pattern molding accuracy than a "pressing process" or a
casting process" that use thermoplastic resin and has
superior heat resistance and chemical resistance. New
manufacturing methods also include a process that performs
molding using a solid or highly viscous photo-curable resin
under normal temperatures or a process that adds a release
agent.
[0069]
Examples of materials used to form the corrugated
structure 12 include a sole material or a composite material
of a thermoplastic resin such as an acrylic resin, an epoxy
resin, a cellulose resin, and a vinyl resin; and a thermoset
resin such as an urethane resin in which polyisocyanate is
28
added and cross-linked as a cross-linking agent to acrylic
polyol, polyester polyol, or the like that have a hydroxyl
group, a melamine resin, an epoxy resin, and a phenol resin.
As long as the corrugated structure 12 can be formed,
materials other than those listed above may be used.
[0070]
Materials of the corrugated structure 12 used in the
photopolymer process include monomer, oligomer, polymer, and
the like that have an ethylene unsaturated bond or an
ethylene non-saturated group. Examples of a monomer include
1,6-hexane diol, neopentyl glycol diacrylate,
trimethylolpropanetriacrylate, pentaerythritoltriacrylate,
pentaerythritoltetraacrylate,
dipentaerythritolpentaacrylate, and
dipentaerythritolhexaacrylate. Examples of an oligomer
include epoxy acrylate, urethane acrylate, and polyester
acrylate. Examples of a polymer include a urethane modified
acrylic resin and an epoxy modified acrylic although there
is no limitation to such substances.
[0071]
When employing light cationic polymerization, a monomer,
an oligomer, and a polymer that include an epoxy group; a
compound containing an oxetane frame; and a vinyl ether may
be used. When curing the ionizing radiation-curable resin
with light such as ultraviolet rays, a photopolymerization
initiator may be added. In accordance with the resin, a
light radical polymerization initiator, a light cationic
polymerization initiator, or a combination (hybrid) of these
initiators may be selected.
[0072]
Further, a mixture of a monomer, an oligomer, a polymer,
and the like having an ethylene unsaturated bond or an
ethylene non-saturated group may be used; a reactive group
29
may be prepared in these substances and these substances may
be cross-linked with each other using an isocyanate
compound, a silane coupling agent, an organic titanate
cross-linking agent, an organozirconium cross-linking agent,
organic aluminate, or the like; and a reactive group may be
prepared in these substances and these substances may be
cross-linked with other resin frames using an isocyanate
compound, a silane coupling agent, an organic titanate
cross-linking agent, an organozirconium cross-linking agent,
organic aluminate, or the like. With such a method, an
ethylene unsaturated bond or an ethylene non-saturated group
exists as a solid under normal temperatures and has few
tucks. This allows for a polymer to be obtained having good
molding characteristics and a relatively clean original
plate.
[0073]
Examples of a light radical polymerization initiator
include a benzoin compound such as
benzoin,benzoinmethylether,andbenzoinethylether; a
anthraquinone compound such as anthraquinone and
methylanthraquinone; a phenyl ketone compound such as
acetophenone,diethoxyacetophenone,benzophenone,hydroxyacetop
henone,1-hydroxycyclohexyl phenyl ketone,α-
aminoacetophenone, and 2-methyl-1-(4-methylthiophenyl)-2-
morpholinopropane-1-one; benzil dimethyl ketal;thioxanthone;
acyl phosphine oxide;and Michler's ketone.
[0074]
The light cationic polymerization initiator when using a
compound that can undergo light cationic polymerization may
be aromatic diazonium salt, aromatic iodonium salt, aromatic
sulfonium salt, aromatic phosphonium salt, mixed ligand
metal salt, and the like. When light radical polymerization
and light cationic polymerization are combined in a hybrid
30
material, the polymerization initiator for each
polymerization may be used in combination. Further,
aromatic iodonium salt, aromatic sulfonium salt, and the
like that function to start both polymerization with a
single initiator may be used.
[0075]
The compounding ratio of a radiation-curable resin and a
light polymerization initiator is generally 0.1 to 15 mass%
but may be set in accordance with the material. For a resin
composition, a sensitizing dye may be further used in
combination with the light polymerization agent. Further,
when necessary, dye, pigment, various types of additives
(polymerization inhibitor, leveling agent, defoamer, sagging
agent, adhesion improving agent, coating surface modifier,
plasticizer, nitrogen-containing compounds, etc.) and a
cross-linking agent (e.g., epoxy resin) may be included.
Further, to improve the molding characteristics, a nonreactive
resin (including the thermoplastic resin and the
thermosetting resin described above) may be added.
[0076]
Further, the material that is selected may be one that
can be molded in the employed manufacturing method, has a
certain degree of fluidity, and is able to obtain a molded
film having the desired heat resistance and chemical
resistance.
[0077]
A coating process may be employed for a layer that forms
the corrugated structure 12 (hereafter referred to as the
corrugated structure formation layer). In such a case, a
support base material may be coated with the material of the
"corrugated structure formation layer." In particular, the
application of a wet coating would lower costs. Further, a
coating diluted with a solvent that adjusts the thickness of
31
the applied film may be applied and dried.
[0078]
The preferred support base material is a film base
material. For example, a plastic film such as polyethylene
terephthalate (PET), polyethylene naphthalate (PEN), and
polypropylene (PP) may be used. It is preferred that
deformation and modification caused by heat, pressure, and
electromagnetic waves be small in the material used when
molding a fine corrugated pattern. Paper, synthesized
paper, plastic multiple-layer paper, resin-impregnated
paper, or the like may be used as the support base material
when necessary.
[0079]
The "corrugated structure formation layer" has a
thickness that is 1.5 to 10 times greater than the depth of
the recesses in the corrugated structure 12, and more
preferably, 2 to 5 times greater than the depth. Depending
on the manufacturing method, an excessively thick applied
film may result in resin being squeezed out or creased when
pressurized. When the thickness is too small, the fluidity
would be poor and sufficient molding would be hindered.
[0080]
The "depth of the recesses in the corrugated structure
12" may be selected in accordance with the diameter of the
desired filling particles. The recess has a depth that is
preferably 1 to 10 times greater than the maximum diameter
of the filling particles. The thickness of the "corrugated
structure formation layer" prior to the formation of the
corrugated structure 12 is preferably 1.5 to 10 times
greater than the "depth of the recesses," and more
preferably, 2 to 5 times greater than the thickness of the
"depth of the recesses."
[0081]
32
After the obtained "corrugated structure formation
layer" comes into contact with a "relief original plate," on
which a relief shape having the desired corrugated structure
is formed, the shape of the relief original plate is
transferred to one side of the fine corrugated structure
formation layer using heat, pressure, and electromagnetic
waves when necessary. The relief shape may be formed on
opposite sides of the "corrugated structure formation
layer."
[0082]
The relief original plate may be formed through a known
method. When the relief original plate is of a roll type,
continuous molding may be performed.
Details of process for filling corrugated structurewith
particles
After forming the corrugated structure 12 in which one
side of the corrugated structure formation layer is filled
with particles, the entire surface of the corrugated
structure 12 is coated with a diluted solution of the
filling particles. Here, when the particles need to be
fixed, a binder, which is soluble in the diluted solution,
may be added. The used binder may be any one of a
thermoplastic resin, a thermal-curable resin, and an
electromagnetic wave-curable resin or a mixture of these
resins.
[0083]
Then, wiping is performed with an air knife, a doctor,
or a squeegee to fill only the recesses of the corrugated
structure 12 with particles. The solvent using for the
diluted solution of particles may be volatilized, and the
binder may be hardened by applying heat or irradiating
33
electromagnetic waves.
Details of process for forming corrugated structure 14
having electromagnetic wave scattering function
The corrugated structure 14 has an electromagnetic wave
scattering function and scatters electromagnetic waves. The
electromagnetic wave scattering performed by the corrugated
structure 14 is in accordance with the corrugation cycle.
When the corrugated structure has a fixed corrugation cycle,
the scattering strength increases in a specific direction
during diffraction scattering. However, the corrugated
structure has a directivity that greatly decreases the
scattering strength in a specific direction. This is not
suitable for a multiple-image display body according to the
present invention.
[0084]
In a corrugated structure having a random cycle in a
range of approximately 1.0 to 10 times greater than the
wavelength of the scattered electromagnetic waves and a
cycle having a random directivity on a plane,
electromagnetic waves of any incident angle (electromagnetic
waves in any wavelength range) has a feature in that the
scattering relative to the plane is isotropic (semispherical
scattering relative to incident point). This is preferable
for the corrugated structure 14.
[0085]
The process for forming a corrugated structure 14 having
an electromagnetic wave scattering function is the same in
detail as the process for forming the corrugated
structurefilled with the electromagnetic wave scattering
particles or the electromagnetic wave absorbing particles.
That is, a process that embosses an original plate including
34
a corrugated structure having the scattering characteristics
allows for the formation of the corrugated structure 14
having an electromagnetic wave scattering function.
Details of process for forming corrugated structure
(e.g., corrugated structure 18) having electromagnetic wave
absorbing function
A corrugated structure having an electromagnetic wave
absorbing function absorbs electromagnetic waves.
Generally, a diffraction grating having a shorter cycle than
the wavelength of the electromagnetic wave that is to be
absorbed obtains a corrugated structure having an
electromagnetic wave absorbing function. A structure known
as a subwavelength grating has an effect that encloses
electromagnetic waves and thus can be used as an
electromagnetic wave absorptive corrugated structure in the
present invention.
[0086]
Further, a high aspect, fly's eye non-reflection
structure may also be used as an electromagnetic wave
absorptive corrugated structure in the present invention.
The process for forming a corrugated structure having an
electromagnetic wave absorbing function is the same in
detail as the process for forming the corrugated
structurefilled with the electromagnetic wave scattering
particles or the electromagnetic wave absorbing particles.
That is, a process that embosses an original plate including
a corrugated structure having the scattering characteristics
allows for the formation of a corrugated structure having an
electromagnetic wave absorbing function.
35
Electromagnetic wave scattering particles 13
When adding a binder to particles or when containing
particles in specific resin layers, if there is a difference
between the refractive index of the particles and the
refractive index of the binder or between the refractive
index of the particles and the refractive index of the resin
layer holding the particles, a scattering characteristic is
obtained at the interface of the particles and the binder or
the resin. This scatters electromagnetic waves. The
preferred difference in the refractive index in this case is
0.2 or greater. Scattering occurs when the difference in
the refractive index is 0.2 or greater. The particles may
be air or gas. The difference in the refractive index also
causes scattering when the resin includes fine air bubbles
or gas bubbles.
[0087]
The scattering of electromagnetic waves caused by the
particles is classified in accordance with the size
parameter into Rayleigh scattering, Mie scattering, and
diffraction scattering. The size parameter distribution that
is employed scatters the desired wavelength range in a
desired manner.
Electromagnetic wave reflection layers 15, 19, 29', and
39'
The electromagnetic wave reflection layers 15, 19, 29',
and 39' arranged along the corrugated surface of the
electromagnetic wave scattering corrugated structures 14 and
29 and the electromagnetic wave absorbing corrugated
structures 18 and 39 have electromagnetic wavereflection
characteristics. When reflecting light, a material having a
36
refractive index that is higher than the refractive index of
the resin layer that forms the corrugated structuremay be
used. When the difference in the refraction index is 0.2 or
greater, refraction and reflection occur at the interface of
the "corrugated structure formation layer" and the
"reflective layers 15, 19, 29', and 39'.
[0088]
Examples of the material of a reflection film include
metal materials such as Al, Sn, Cr, Ni, Cu, Au, and Ag used
solely or in combination as a compound.
The reflection layers 15, 19, 29', and 39' need to be
formed as thin layers having a uniform surface density on a
plane of a fine corrugation formation layer. Thus it is
preferred that the reflection layers 15, 19, 29', and 39' be
formed through a dry coating process. For example, a known
process such as a vacuum deposition process, a sputtering
process, and a CVD process may be employed.
[0089]
Further, examples of materials that may be used as the
transparent reflection layers 15, 19, 29', and 39' are
listed below. The numeric value in the parenthesis
following the chemical formula or the compound name
indicates the refractive index n. Examples of ceramics
include Sb2O3 (3.0), Fe2O3 (2.7), TiO2 (2.6), CdS (2.6), CeO2
(2.3), ZnS (2.3), PbCl2 (2.3), CdO (2.2), Sb2O3 (5), WO3 (5),
SiO (5), Si2O3 (2.5), In2O3 (2.0), PbO (2.6), Ta2O3 (2.4), ZnO
(2.1), ZrO2 (5), MgO (1), SiO2 (1.45), Si2O2 (10), MgF2 (4),
CeF3 (1), CaF2 (1.3 to 1.4), AlF3 (1), Al2O3 (1), and GaO (2).
Examples of organic polymers include polyethylene (1.51),
polypropylene (1.49), polytetrafluoroethylene (1.35),
polymethyl methacrylate (1.49), and polystyrene (1.60).
However, there is no limitation to these compounds.
37
[0090]
Protection layers (not shown) are formed on the
reflection layers 15, 19, 29', and 39' when necessary. A
protection layer needs to be a continuous film that is able
to protect a reflection layer on an inclined surface where a
reflection film remains. Further, it is preferred that a
protection layer on a "surface where a reflection film is
removed" be extremely thin with respect to the thickness of
a protection layer on an "inclined surface where a
reflection film remains."
[0091]
Such a structure allows for the formation of an inclined
"reflection film" in a process such as etching for removing
the reflection layer.
Electromagnetic wave absorbing particles 17
Examples of ceramics include Sb2O3 (3.0), Fe2O3 (2.7),
TiO2 (2.6), CdS (2.6), CeO2 (2.3), ZnS (2.3), PbCl2 (2.3),
CdO (2.2), Sb2O3 (5), WO3 (5), SiO (5), Si2O3 (2.5), In2O3
(2.0), PbO (2.6), Ta2O3 (2.4), ZnO (2.1), ZrO2 (5), MgO (1),
SiO2 (1.45), Si2O2 (10), MgF2 (4), CeF3 (1), CaF2 (1.3 to
1.4), AlF3 (1), Al2O3 (1), and GaO (2). Examples of organic
polymers include polyethylene (1.51), polypropylene (1.49),
polytetrafluoroethylene (1.35), polymethyl methacrylate
(1.49), and polystyrene (1.60). However, there is no
limitation to these compounds.
[0092]
The electromagnetic wave absorbing particles 17 may be a
metal oxide, such as iron oxide or tin oxide, or metal
nanoparticles that generate plasma oscillation. Further,
general colorant pigments and colorant dyes also have
characteristics in which they absorb specific wavelengths.
38
[0093]
The above materials may be mixed and combined. Further,
plural types of different particles may be used in any
region.
In the multiple-image display body configured as
described above, even when the outermost line tone barrier
layer 3 is contaminated with a liquid such as oil or a
chemical, there is no loss in the desired continuous
movement and depth in a multiple-image display. Further,
the contrast of the light intensity of the line tone barrier
layer 3 and the multiple-image formation layer 4 is
improved, and a high contrast can be obtained from any
observation angle. Thus, an image can be recognized with
high visibility under an observation condition in which
there is only reflection light.
Examples
[0094]
Examples of multiple-image display bodies according to
the present invention will now be described.
Example 1
An ink composition of a "corrugated structure formation
layer" such as that described below was prepared to form a
corrugated structure of a line tone barrier layer 3 in a
multiple-image display body according to the present
invention through a photopolymer process.
[0095]
"Corrugated structure formation layer ink composition"
(ultraviolet-curable resin)
Urethane (meth)acrylate (polyfunctional, molecular
weight 6,000) 50.0 parts by weight
39
Methyl ethyl ketone 30.0 parts by weight
Ethyl acetate 20.0 parts by weight
Photoinitiator(IRGACURE 184 manufactured by Ciba
Specialty) 1.5 parts by weight
A roll photopolymer process was employed as a method for
forming a corrugated structure on a corrugated structure
formation layer.
[0096]
Gravure printing was performed to apply an "ink
composition of a fine corrugated structure formation layer,"
with a thickness of 5 μm when dried, to a support base
material formed by a transparent polyethylene terephthalate
(PET) film having a thickness of 23 μm. Then, a tubular
original plate having a corrugated structure was pressed
against the surface to which the ink composition was applied
to perform molding under a pressing pressure of 2 Kgf/cm2, a
pressing temperature of 80°C, and a pressing speed of
10m/min.
[0097]
At the same time as when the molding was performed,
ultraviolet exposure was performed at 300 mJ/cm2 with a highpressure
mercury lamp over the support base materialformed
by a PET film. This transcribed the corrugated shape on the
original plate to the "corrugated structure formation layer"
and simultaneously cured the transcription. The "corrugated
structure" in the molded fine corrugated structure formation
layer had a projection width of 10 μm, a recess width of
5μm, and a recess depth of 2 μm.
[0098]
The corrugated structure for forming the line tone
barrier layer 3 was obtained in this manner.
40
Then, an ink composition of a "corrugated structure
formation layer" such as that described below was prepared
to form the multiple-image formation layer 4 on the surface
of the support base material opposite to the surface where
the corrugated structure for forming the line tone barrier
layer 3 was formed, and gravure printing was performed to
obtain a dried film having a thickness of 5 μm.
[0099]
"Corrugated structure formation layer ink composition"
(ultraviolet-curable resin)
Urethane (meth)acrylate (polyfunctional, molecular
weight 6,000) 50.0 parts by weight
Methyl ethyl ketone 30.0 parts by weight
Ethyl acetate 20.0 parts by weight
Photoinitiator (IRGACURE 184 manufactured by Ciba
Specialty) 1.5 parts by weight
A roll photopolymer process was employed as a method for
forming a corrugated structure on a corrugated structure
formation layer.
[0100]
As described above, gravure printing was performed to
apply an "ink composition of a corrugated structure
formation layer," with a thickness of 5 μm when dried.
Then, a tubular original plate having a corrugated structure
shown in Fig. 19 was pressed against the surface to which
the ink composition was applied to perform molding under a
pressing pressure of 2 Kgf/cm2, a pressing temperature of
80°C, and a pressing speed of 10m/min.
[0101]
In the corrugated structure of Fig. 19, the pixel width
of lines was 5 μm, white portions had a scattering
corrugated structure (depth of 0.2 μm and random cycle), and
41
black portions had an absorbing corrugated structure (depth
of 0.3 μm and cycle of 0.2 μmgrid).
[0102]
At the same time as when the molding was performed,
ultraviolet exposure was performed at 300 mJ/cm2 with a highpressure
mercury lamp over the support base material formed
by a PET film. This transcribed the corrugated shape on the
original plate to the "corrugated structure formation layer"
and simultaneously cured the transcription.
[0103]
Then, aluminum vapor deposition was performed to form an
electromagnetic wave reflection layer so that an aluminum
film obtained a thickness of 0.05 μm (500 Å) at a flat
portion.
Then, a "solution of electromagnetic wave absorbing
particles," in which carbon black pigments having an average
particle diameter of 1 μm was scattered in methyl ethyl
ketone (MEK) and to which a vinyl chloride-vinyl acetate
copolymer was added at a solid weight ratio of 5%, was
applied to the entire surface of the corrugated structure
for forming the line tone barrier layer 3. Then, the
recesses were filled electromagnetic wave absorbing
particles by a doctor blade and dried for 30 seconds in an
oven at 120° to obtain the "line tone barrier layer 3."
[0104]
This formed a multiple-image display body having a total
thickness of 33 μm.
Example 2
An ink composition of a "corrugated structure formation
layer" such as that described below was prepared to form a
42
corrugated structure of a line tone barrier layer 3 in a
multiple-image display body according to the present
invention through a photopolymer process.
[0105]
"Corrugated structure formation layer ink composition"
(ultraviolet-curable resin)
Urethane (meth)acrylate (polyfunctional, molecular
weight 6,000) 50.0 parts by weight
Methyl ethyl ketone 30.0 parts by weight
Ethyl acetate 20.0 parts by weight
Photoinitiator (IRGACURE 184 manufactured by Ciba
Specialty) 1.5 parts by weight
A roll photopolymer process was employed as a method for
forming a corrugated structure on a corrugated structure
formation layer.
[0106]
Gravure printing was performed to apply an "ink
composition of a fine corrugated structure formation layer,"
with a thickness of 5 μm when dried, to a support base
material formed by a transparent polyethylene terephthalate
(PET) film having a thickness of 23 μm. Then, a tubular
original plate having a corrugated structure was pressed
against the surface to which the ink composition was applied
to perform molding under a pressing pressure of 2 Kgf/cm2, a
pressing temperature of 80°C, and a pressing speed of
10m/min.
[0107]
At the same time as when the molding was performed,
ultraviolet exposure was performed at 300 mJ/cm2 with a highpressure
mercury lamp over the support base material formed
by a PET film. This transcribed the corrugated shape on the
original plate to the "corrugated structure formation layer"
43
and simultaneously cured the transcription. The "corrugated
structure" in the molded fine corrugated structure formation
layer had a projection width of 10 μm, a recess width of
5μm, and a recess depth of 2 μm.
[0108]
The corrugated structure for forming the line tone
barrier layer 3 was obtained in this manner.
Then, an ink composition of a "corrugated structure
formation layer" such as that described below was prepared
to form the multiple-image formation layer 4 on the surface
of the support base material opposite to the surface where
the corrugated structure for forming the line tone barrier
layer 3 was formed, and gravure printing was performed to
obtain a dried film having a thickness of 5 μm.
[0109]
"Corrugated structure formation layer ink composition"
(ultraviolet-curable resin)
Urethane (meth)acrylate (polyfunctional, molecular
weight 6,000) 50.0 parts by weight
Methyl ethyl ketone 30.0 parts by weight
Ethyl acetate 20.0 parts by weight
Photoinitiator (IRGACURE 184 manufactured by Ciba
Specialty) 1.5 parts by weight
A roll photopolymer process was employed as a method for
forming a corrugated structure on a corrugated structure
formation layer.
[0110]
As described above, gravure printing was performed to
apply an "ink composition of a corrugated structure
formation layer," with a thickness of 5 μm when dried.
Then, a tubular original plate having a corrugated structure
44
shown in Fig. 19 was pressed against the surface to which
the ink composition was applied to perform molding under a
pressing pressure of 2 Kgf/cm2, a pressing temperature of
80°C, and a pressing speed of 10m/min.
[0111]
In the corrugated structure of Fig. 19, the pixel width
of lines was 5 μm, white portions had a scattering
corrugated structure (depth of 0.1μm and random cycle), and
black portions had an absorbing corrugated structure (depth
of 0.3 μm and cycle of 0.3μmorthogonal grid).
[0112]
At the same time as when the molding was performed,
ultraviolet exposure was performed at 300 mJ/cm2 with a highpressure
mercury lamp over the support base material formed
by a PET film. This transcribed the corrugated shape on the
original plate to the "corrugated structure formation layer"
and simultaneously cured the transcription.
[0113]
Then, aluminum vapor deposition was performed to form an
electromagnetic wave reflection layer so that a thickness of
0.05 μm (500 Å)was obtained at a flat portion. Further,
magnesium fluoride was vapor-deposited to form a vapor
deposition mask layer so that a thickness of 0.03 μm (300
Å)was obtained at a flat portion. (In this case, the
surface area of black portions having a high aspect is
larger than the surface area of the white portions. Thus,
the aluminum film had a small thickness and the magnesium
fluoride vapor deposition mask layer had a small thickness.
This allows for the removal of only the black portions in
the drawing through alkali immersion.)
[0114]
Then, immersion was performed for 30 seconds in an
etching liquid at 50°C having 0.2% of sodium hydroxide to
45
remove the reflection layer of the black portions in Fig. 19
and obtain transparency. Then, black ink was applied to
cover the multiple-image formation layer 4. This obtained
the electromagnetic wave absorbing layer.
[0115]
Then, a "solution of electromagnetic wave absorbing
particles," in which carbon black pigments having an average
particle diameter of 1 μm was scattered in methyl ethyl
ketone (MEK) and to which a vinyl chloride-vinyl acetate
copolymer was added at a solid weight ratio of 5%, was
applied to the entire surface of the corrugated structure
for forming the line tone barrier layer 3. Then, the
recesses were filled with electromagnetic wave absorbing
particles by a doctor blade and dried for 30 seconds in an
oven at 120° to obtain the "line tone barrier layer 3."
[0116]
This formed a multiple-image display body having a total
thickness of 33 μm.
Example 3
An ink composition of a "corrugated structure formation
layer" such as that described below was prepared to form a
corrugated structure of a line tone barrier layer 3 in a
multiple-image display body according to the present
invention through a photopolymer process.
[0117]
"Corrugated structure formation layer ink composition"
(ultraviolet-curable resin)
Urethane (meth)acrylate (polyfunctional, molecular
weight 6,000) 50.0 parts by weight
Methyl ethyl ketone 30.0 parts by weight
Ethyl acetate 20.0 parts by weight
46
Photoinitiator (IRGACURE 184 manufactured by Ciba
Specialty) 1.5 parts by weight
A roll photopolymer process was employed as a method for
forming a corrugated structure on a corrugated structure
formation layer.
[0118]
Gravure printing was performed to apply an "ink
composition of a fine corrugated structure formation layer,"
with a thickness of 5 μm when dried, to a support substrate
formed by a transparent polyethylene terephthalate (PET)
film having a thickness of 23 μm. Then, a tubular original
plate having a corrugated structure was pressed against the
surface to which the ink composition was applied to perform
molding under a pressing pressure of 2 Kgf/cm2, a pressing
temperature of 80°C, and a pressing speed of 10m/min.
[0119]
At the same time as when the molding was performed,
ultraviolet exposure was performed at 300 mJ/cm2 with a highpressure
mercury lamp over the support base material formed
by a PET film. This transcribed the corrugated shape on the
original plate to the "fine corrugated structure formation
layer" and simultaneously cured the transcription. The
"corrugated structure" in the molded fine corrugated
structure formation layer had a projection width of 10 μm, a
recess width of 5μm, and a recess depth of 2 μm.
[0120]
The corrugated structure for forming the line tone
barrier layer 3 was obtained in this manner.
Then, an ink composition of a "corrugated structure
formation layer" such as that described below was prepared
to form a"multiple-image formation layer" on the surface of
47
the support base material opposite to the surface where the
corrugated structure for forming the line tone barrier layer
3 was formed, and gravure printing was performed to obtain a
dried film having a thickness of 5 μm.
[0121]
"Corrugated structure formation layer ink composition"
(ultraviolet-curable resin)
Urethane (meth)acrylate (polyfunctional, molecular
weight 6,000) 50.0 parts by weight
Methyl ethyl ketone 30.0 parts by weight
Ethyl acetate 20.0 parts by weight
Photoinitiator (IRGACURE 184 manufactured by Ciba
Specialty) 1.5 parts by weight
A roll photopolymer process was employed as a method for
forming a corrugated structure on a corrugated structure
formation layer.
[0122]
As described above, gravure printing was performed to
apply an "ink composition of a fine corrugated structure
formation layer," with a thickness of 5 μm when dried.
Then, a tubular original plate having a corrugated structure
shown in Fig. 19 was pressed against the surface to which
the ink composition was applied to perform molding under a
pressing pressure of 2 Kgf/cm2, a pressing temperature of
80°C, and a pressing speed of 10m/min.
[0123]
In the corrugated structure of Fig. 19, the pixel width
of lines was 5 μm, white portions had a particle filled
corrugated structure (depth of 0.1μm and random cycle), and
black portions were flat.
At the same time as when the molding was performed,
48
ultraviolet exposure was performed at 300 mJ/cm2 with a highpressure
mercury lamp over the PET film. This transcribed
the corrugated shape on the original plate to the
"corrugated structure formation layer" and simultaneously
cured the transcription.
[0124]
The "particle filled corrugated structure (white
portions)" in the molded fine corrugated structure formation
layer had a recess width of 5 μm and a recess depth of 2 μm.
Then, a"solution of electromagnetic wave absorbing
particles," in which carbon black pigments having an average
particle diameter of 1 μm was scattered in methyl ethyl
ketone (MEK) and to which a vinyl chloride-vinyl acetate
copolymer was added at a solid weight ratio of 5%, was
applied to the entire surface of the corrugated structure
for forming a multiple-image formation layer. Then, the
recesses were filled with electromagnetic wave absorbing
particles by a doctor blade and dried for 30 seconds in an
oven at 120° to obtain a "multiple-image formation layer."
Further, paper was adhered so as to cover the multiple-image
formation layer and form an electromagnetic wave scattering
layer.
[0125]
Then, a "solution of electromagnetic wave absorbing
particles," in which carbon black pigments having an average
particle diameter of 1 μm was scattered in methyl ethyl
ketone (MEK) and to which a vinyl chloride-vinyl acetate
copolymer was added at a solid weight ratio of 5%, was
applied to the entire surface of the corrugated structure
for forming the line tone barrier layer 3. Then, the
recesses were filled with electromagnetic wave absorbing
particles by a doctor blade and dried for 30 seconds in an
49
oven at 120° to obtain a "line tone barrier layer."
[0126]
This formed a multiple-image display body having a total
thickness of 33 μm.
Comparative Example 1
The manufacturing method is similar to that of example
2. However, pixels of a multiple-image formation layer were
used to form a stacked body that is shown by the contrast of
a smooth aluminum region and a transparent region, which is
free from aluminum, when forming a multiple-image display
body having a total thickness of 33 μm.
Comparative Example 2
An image display body (security thread) that uses a lens
and is watermarked on Danish banknotes (100 Krone) was
subject to comparison.
Evaluation method of anti-counterfeiting structures
formed in examples and comparative examples
* Visual evaluation of multiple images in normal
situation
The multiple-image display bodies formed in examples 1,
2, and 3 and comparative example 1 were prepared. Then, the
multiple images were viewed changing the observation angle.
Cases in which the multiple images were readable are
indicated by "OK" and not readable are indicated by "NG."
* Visual evaluation of multiple images onto which salad
50
oil has been dropped
The multiple-image display bodies formed in examples 1,
2, and 3 and comparative example 1 were prepared. Then, 10
g of salad oil was dropped onto the surface of the stacked
body (surface of line tone barrier layer in examples, and
surface of lens array in comparative example), and the
multiple images were left for 30 seconds. Then, the
multiple images were viewed changing the observation angle.
Cases in which the multiple images were readable are
indicated by "OK" and not readable are indicated by "NG."
* Evaluation of watermark on security paper
Generally, a film having a thickness of 50 μm or less
can be watermarked onto a security paper, and the
watermarked paper can undergo printing. Accordingly, in the
examples, when the image display body has a total thickness
of 50 μm or less, watermarking can be performed. Such cases
are indicated by "OK." Cases in which the total thickness
exceeds 50 μm are indicated by "NG." Comparison example 1
is indicated as "OK" since the paper has already been
watermarked.
[0127]
The above evaluation methods were used to evaluate the
examples and the comparative examples. The results are
shown in table 1.
[0128]
Table 1
Structure Visual
evaluation of
multiple images
Visual
evaluation of
multiple images
Evaluation of
watermark on
security paper
51
in normal
situation
onto which
salad oil has
been dropped
(OK when total
thickness is 50
μm or less)
Example 1 OK OK OK
Example 2 OK OK OK
Example 3 OK OK OK
Com.
Example 1
NG (image
visible in only
regular
reflection)
NG OK
Comp.
Example 2
OK NG OK (paper
watermarked)
It may be understood from table 1 that the visibility in
a normal situation in examples 1 to 3 is superior to
comparative example 1. This is because the display body
uses a scattering structure and thus allows the image
contrast to be maintained even in an observation environment
other than regular reflection of a light source. The
examples obtained superior results.
[0129]
Further, in examples 1 to 3, "visual evaluation of
multiple images onto which salad oil has been dropped" is
OK. However, the visibility was insufficient in comparative
example 2. As a result, the examples are superior to the
comparative example.
INDUSTRIAL APPLICABILITY
[0130]
In a multiple-image display body according to the
present invention, even when an outermost layer is
contaminated by a liquid such as oil or a chemical, the
desired continuous movement and depth is not lost from the
52
display of multiple images. Further, the contrast of the
light intensity is improved even under a regular reflection
light source, and a high contrast is obtained from any
observation angle. Accordingly, even under an observation
condition in which there is only reflection light, high
visibility and special light effects are obtained. Thus,
the multiple-image display body according to the present
invention may be used as an image display body having
sufficient anti-counterfeiting effects when applied to, for
example, ID cards, passports, and banknotes.
[0131]
The embodiments and the examples described above are
considered to be illustrative and are not intended to
restrict the scope of the invention. The embodiments and
the examples may be implemented in other various forms and
are subject to omissions, substitutions, and changes within
the scope of the invention. The embodiments and the
examples include the scope of the invention and equivalence
of the invention recited in the claims.
DESCRIPTION OF REFERENCE CHARACTERS
[0132]
1) multiple-image display body, 2) spacer layer, 3) line
tone barrier layer, 4) multiple-image formation layer, 5)
first region, 6) second region, 7) first image, 8) second
image, 9) third image, 10, 10a, 10b) third region, 11, 11a,
11b) fourth region, 12) corrugated structure, 13)
electromagnetic wave scattering particles, 14)
electromagnetic wave scattering corrugated structure, 15)
electromagnetic wave reflection layer, 16) corrugated
structure, 17) electromagnetic wave absorbing particles, 18)
electromagnetic wave absorbing corrugated structure, 19)
electromagnetic wave reflection layer, 20) multiple-image
53
display body, 21) electromagnetic wave absorbing layer, 22)
first image, 23) second image, 24) third image, 25, 25a,
25b) third region, 26) fifth region, 27) corrugated
structure, 28) electromagnetic wave scattering particles,
29) electromagnetic wave scattering corrugated structure,
29') electromagnetic wave reflection layer, 30) multiple
image display body, 31) electromagnetic wave scattering
layer, 32) first image, 33) second image, 34) third image,
35) sixth region, 36) seventh region, 37) corrugated
structure, 38) electromagnetic wave scattering particles,
39) electromagnetic wave absorbing corrugated structure,
39') electromagnetic wave reflection layer, 82a to 82d)
observation condition, 83a to 83c) observation image
(observation pattern).
54
We Claim:
1. A multiple-image display body comprising:
a spacer layer including a first surface and a second
surface opposite to the first surface, wherein the spacer
layer has the form of a thin film;
a line tone barrier layer stacked on the first surface
of the spacer layer, wherein the line tone barrier layer
includes first regions, which transmit electromagnetic waves
in at least some wavelength ranges, and second regions,
which absorb electromagnetic waves in at least some
wavelength ranges, the second regions in a surface
contacting the spacer layer have substantially the same
width and shape, and the second regions are arranged at
equal intervals sandwiching at least portions of the first
regions to form a line tone pattern; and
a multiple-image formation layer stacked on the second
surface of the spacer layer, wherein the multiple-image
formation layer includes images that are visible when
observed from specific angles over the first regions of the
line tone barrier, wherein each of the images includes a
third region, which scatters electromagnetic waves in at
least some wavelength ranges, and a fourth region, which
absorbs electromagnetic waves in at least some wavelength
ranges, and the image is formed by a contrast resulting from
an area ratio of the third region and the fourth region.
2. A multiple-image display body comprising:
a spacer layer including a first surface and a second
surface opposite to the first surface, wherein the spacer
layer has the form of a thin film;
a line tone barrier layer stacked on the first surface
of the spacer layer, wherein the line tone barrier layer
includes first regions, which transmit electromagnetic waves
55
in at least some wavelength ranges, and second regions,
which absorb electromagnetic waves in at least some
wavelength ranges, the second regions in a surface
contacting the spacer layer have substantially the same
width and shape, and the second regions are arranged at
equal intervals sandwiching at least portions of the first
regions to form a line tone pattern;
a multiple-image formation layer stacked on the second
surface of the spacer layer, wherein the multiple-image
formation layer includes images that are visible when
observed from specific angles over the first regions of the
line tone barrier, wherein each of the images includes a
third region, which scatters electromagnetic waves in at
least some wavelength ranges, and a fifth region, which
transmits electromagnetic waves in at least some wavelength
ranges, and the image is formed by a contrast resulting from
an area ratio of the third region and the fifth region; and
an electromagnetic wave absorbing layer stacked on a
surface of the multiple-image formation layer opposite to
the spacer layer, wherein the electromagnetic wave absorbing
layer absorbs electromagnetic waves transmitted in order
from the line tone barrier to the spacer layer and then to
the fifth region.
3. A multiple-image display body comprising:
a spacer layer including a first surface and a second
surface opposite to the first surface, wherein the spacer
layer has the form of a thin film;
a line tone barrier layer stacked on the first surface
of the spacer layer, wherein the line tone barrier layer
includes first regions, which transmit electromagnetic waves
in at least some wavelength ranges, and second regions,
which absorb electromagnetic waves in at least some
56
wavelength ranges, the second regions in a surface
contacting the spacer layer have substantially the same
width and shape, and the second regions are arranged at
equal intervals sandwiching at least portions of the first
regions to form a line tone pattern;
a multiple-image formation layer stacked on the second
surface of the spacer layer, wherein the multiple-image
formation layer includes images that are visible when
observed from specific angles over the first regions of the
line tone barrier, wherein each of the images includes a
sixth region, which absorbs electromagnetic waves in at
least some wavelength ranges, and a seventh region, which
transmits electromagnetic waves in at least some wavelength
ranges, and the image is formed by a contrast resulting from
an area ratio of the sixth region and the seventh region;
and
an electromagnetic wave scattering layer arranged on a
surface of the multiple-image formation layer opposite to
the spacer layer, wherein the electromagnetic wave
scattering layer scatters electromagnetic waves transmitted
in order from the line tone barrier to the spacer layer and
then to the seventh region.
4. The multiple-image display body according to claim 1
or 2, wherein the third region has a corrugated structure,
and the corrugated structure includes recessesfilled with
electromagnetic wave scattering particles that scatter
electromagnetic waves in at least some wavelength ranges.
5. The multiple-image display body according to claim
1, wherein the fourth region has a corrugated structure, and
the corrugated structure includes recesses filled with
electromagnetic wave absorbing particles that absorb
57
electromagnetic waves in at least some wavelength ranges.
6. The multiple-image display body according to claim
3, wherein the sixth region has a corrugated structure, and
the corrugated structure includes recesses filled with
electromagnetic wave absorbing particles that absorb
electromagnetic waves in at least some wavelength ranges.
7. The multiple-image display body according to claim 5
or 6, wherein the particles which the recesses are filled
with are at least one of pigments, dyes, and metal
nanoparticles.
8. The multiple-image display body according to claim 5
or 6, wherein the particles which the recesses are filled
with are core shell particles including cores of fine
pigments and shells of a thermoplastic or thermosetting
resin.
9. The multiple-image display body according to claim 1
or 2, wherein the third region includes a corrugated
structure, which is undulated and has a scattering
characteristic, and an electromagnetic wave reflection
layer, which is arranged on a surface of the corrugated
structure.
58
10. The multiple-image display body according to claim
1, wherein the fourth region includes a corrugated
structure, which is undulated and has an absorbing
characteristic, and an electromagnetic wave reflection
layer, which is arranged on a surface of the corrugated
structure.