TECHNICAL FIELD
The present invention relates to a conductive film, a
display device equipped with the conductive film, and a method
for determining a pattern of a conductive film. Specifically,
the present invention relates to a conductive film, which is
used as a mesh transparent conductive film, and has a mesh
pattern designed in consideration of an electrode such that a
spectral intensity and a frequency of visually recognized moire
are respectively within predetermined ranges of intensity and
frequency, a display device equipped with the conductive film,
and a method for determining a pattern of a conductive film.
BACKGROUND ART
[0002]
Examples of a conductive film installed on a display unit
of a display device (hereinafter, also referred to as a display)
include a conductive film for electromagnetic wave-shielding and
a conductive film for a touch sensor (touch panel) (for example,
see Patent Literatures 1 to 3).
[0003]
Patent Literature 1 filed by the applicant of the present
application discloses a conductive film for electromagnetic
wave-shielding having an electromagnetic wave-shielding pattern
formed of a mesh-like conductive metal thin film, and discloses
that a second pattern, which is generated from second pattern
data in which the relative distance between spectral peaks of
two-dimensional Fourier spectra (2DFFT Sp) of the respective
pattern data of a first pattern such as a pixel array pattern
(for example, a black matrix (hereinafter, also referred to as
BM) pattern) of a display and the second pattern such as the
2
electromagnetic wave-shielding pattern is greater than a
predetermined spatial frequency, for example, 8 cm-1, is
automatically selected.
Patent Literature 1 also discloses that when the relative
distance is not greater than the predetermined spatial
frequency, changing of one or more of a rotation angle, a pitch,
and a pattern width of the second pattern data to generate new
second pattern data is repeated until the relative distance is
greater than the predetermined spatial frequency.
In this way, in Patent Literature 1, it is possible to
automatically select an electromagnetic wave-shielding pattern
that can suppress the occurrence of moire and that can avoid an
increase in surface resistivity or degradation in transparency.
[0004]
Meanwhile, in a conductive film for a touch panel, in view
of quick responsiveness, high resolution, increase in size, low
production cost, and the like, instead of the conventional
transparent ITO (indium tin oxide), opaque conductive materials
such as metals are used as mesh-like wiring materials. In order
to realize a touch panel by using such a conductive film, the
conductive film needs to have resolution for detecting a touched
position. For making the conductive film function as a
transparent conductive film such as ITO by using mesh-like
conductive wiring of the conductive film, with respect to the
whole surface of solid mesh-like wiring, cut portions need to be
provided in specific mesh-like wiring so as to form
disconnections, and in this way, a wiring region for detection
corresponding to the aforementioned resolution needs to be
separated from a dummy wiring region that does not contribute to
the detection.
In the touch panel disclosed in Patent Literature 2, within
each of a plurality of dummy wiring regions surrounded by 2
types of wiring for detection made of a metal (an opaque
conductive material) that are provided to cross each other via
an insulating layer on both sides thereof, isolated wiring is
3
arranged in a state of being parallel or perpendicular to the
wiring for detection or in a state of inclining by 45 with
respect to the wiring for detection. In this way, cut portions
(breaks) are formed between a wiring region for detection
composed of 2 types of wiring for detection and a dummy wiring
region, and consequently, the wiring region for detection and
the dummy wiring region are separated from each other.
According to Patent Literature 2, in this way, it is
possible to obtain a touch panel which has a high response
speed, can reduce display unevenness or moire, has high
visibility, and is easily made into a large-sized touch panel.
[0005]
Patent Literature 3 discloses a conductive film (planar
body) for a capacitive type touch panel (a touch switch). The
conductive film is divided into a plurality of regions of a
conductive portion, in which network (mesh)-like electrodes
composed of conductive wires are disposed at a predetermined
interval in a state of being approximately parallel to each
other, and regions of a non-conductive portion each of which is
disposed between the regions of a conductive portion. The
regions of a non-conductive portion include a plurality of cut
portions (breaks) that cut the conductive wires in the form of
islands, and by the cut portions, the regions of a nonconductive
portion (dummy wiring regions) can be insulated from
the regions of a conductive portion (wiring regions for
detection) adjacent thereto.
According to Patent Literature 3, in this way, it is
possible to improve visibility by preventing the visibility from
deteriorating due to the occurrence of variation of mesh density
(deviation of mesh), and to provide a planar body and a touch
switch that can be efficiently manufactured.
CITATION LIST
PATENT LITERATURE
[0006]
4
Patent Literature 1: JP 2009-117683 A
Patent Literature 2: JP 2010-097536 A
Patent Literature 3: JP 2010-262529 A
SUMMARY OF INVENTION
TECHNICAL PROBLEMS
[0007]
Patent Literature 1 discloses the technique of controlling
a moire frequency using only frequency information of a black
matrix (BM) pattern/a wiring pattern of a display in generating
a wiring pattern of the conductive film and providing a wiring
pattern having excellent moire recognition property, but the
determination of whether moire is visually recognized or not
depends on only the frequency. Since human perception of moire
is affected by intensity as well as frequency, even at a
frequency at which moire is not visually recognized in the
technique of Patent Literature 1, moire may be visually
recognized depending on the intensity, and thus there is a
problem in that the moire recognition property is not improved
satisfactorily.
Particularly, when the technique disclosed in Patent
Literature 1 is applied to a conductive film for a touch panel,
it is necessary to provide a plurality of cut portions (breaks)
in the mesh-like conductive wiring, and if the cut portions are
provided, there is a problem in that the spatial frequency
characteristics of the wiring pattern of the mesh-like
conductive wiring vary. In addition, since the conductive film
is pressed with a human finger, a minute distortion occurs
between the BM/wiring patterns, and thus there is a problem in
that visual recognition of moire due to intensity is promoted.
Accordingly, when the technique disclosed in Patent Literature 1
is applied to a conductive film for a touch panel, there is a
problem in that the improvement in moire recognition property is
not satisfactory.
Therefore, in order to design a pattern having excellent
5
moire recognition property, it is important to design the
pattern in consideration of the cut portions (breaks). However,
in the conventional technique, such a point has not been
discussed.
[0008]
Furthermore, in Patent Literature 2, within each of the
plurality of dummy wiring regions surrounded by wiring regions
for detection composed of 2 types of wiring for detection, the
isolated wiring is arranged in a state of being parallel or
perpendicular to the wiring for detection or in a state of
inclining by 45 with respect to the wiring for detection.
Therefore, the disconnections formed by the cut portions between
the 2 types of wiring for detection and the isolated wiring are
regularly provided. Consequently, the regular period of the
disconnections exerts an influence on the visually recognized
moire, and this leads to a problem in that the moire recognition
property cannot be sufficiently improved.
Moreover, in Patent Literature 3, in order to insulate the
regions of a conductive portion from the regions of a nonconducive
portion, a plurality of cut portions cutting the
conductive wires of the mesh-like electrodes is provided in a
portion in which the conductive wires of the mesh-like
electrodes cross each other. Therefore, in the mesh-like
electrodes, the cut portions are basically regularly provided.
Consequently, the regular period of the disconnections exerts an
influence on the visually recognized moire, and this leads to a
problem in that the moire recognition property cannot be
sufficiently improved.
Particularly, for increasing the size of a touch panel,
opaque conductive materials such as metals need to be used.
However, because a predetermined or a high level of resolution
is required, the moire recognition property becomes a serious
problem.
[0009]
In the specification of Japanese Patent Application No.
6
2012-082711, the present applicant calculated spatial frequency
peaks of BM (pixel matrix) of a display and spatial frequency
peaks of a wiring pattern (mesh pattern) of mesh-like wiring of
a conductive film, calculated evaluation values by convolution
of a two-dimensional frequency and spectral intensity of moire,
that are obtained as a difference between the respective spatial
frequency peaks and an integrated value of peak intensities, and
a visual transfer function, and suggested a conductive film
having a wiring pattern in which the evaluation values satisfy
predetermined conditions.
When such a conductive film is used in a touch panel, as
the aforementioned conductive films for a touch panel of the
conventional technique that are described in Patent Literatures
2 and 3 and the like, a plurality of disconnections needs to be
added to the conductive film by providing a plurality of
disconnection portions (cut portions: breaks) in the mesh-like
wiring that separates the wiring regions for detection securing
the resolution of the mesh-like wiring from the dummy wiring
regions. Generally, these disconnection portions are regularly
added to the conductive film, for the purpose of satisfying
specific resolution required for a touch panel as in the
aforementioned conventional techniques or for the purpose of
making the capacitance of the region of resolution constant.
However, the conductive film has a problem in that the moire is
visually recognized due to the regular period of the
disconnections. In this manner, the regular period of the
disconnections exerts an influence on the visually recognized
moire, and this leads to a problem in that the moire recognition
property cannot be sufficiently improved. However, such a
problem has not been discussed in any of the technique suggested
by the present applicant and the aforementioned conventional
techniques.
[0010]
An object of the present invention is to solve the problems
of the aforementioned conventional techniques and to provide a
7
conductive film, which can inhibit the occurrence of moire and
can greatly improve recognition property, a display device
equipped with the conductive film, and a method for determining
a pattern of a conductive film.
Particularly, in a case in which a conductive film
installed on a display unit of a display device has a plurality
of disconnection portions in mesh-like wiring having a mesh
pattern composed of thin metal wires, moire occurs. Accordingly,
another object of the present invention is to provide a
conductive film, which can inhibit the occurrence of moire and
greatly improve the recognition property even in such a case, a
display device equipped with the conductive film, and a method
for determining a pattern of a conductive film.
Furthermore, particularly, in a case in which a transparent
conductive film having mesh-like wiring including a plurality of
disconnection portions is used as an electrode for a touch panel
that needs to be made into a large-sized touch panel and to have
higher resolution, when the conductive film is superimposed on a
black matrix of a display unit of the display device and
visually recognized, moire occurs, and thus greatly impairs
image quality. Accordingly, the other object of the present
invention is to provide a conductive film, which can inhibit the
occurrence of moire and can greatly improve the visibility of
display on the touch panel even in such a case, a display device
equipped with the conductive film, and a method for determining
a pattern of a conductive film.
SOLUTION TO PROBLEMS
[0011]
In order to achieve the above objects, the present
inventors repeated intensive research regarding a mesh pattern
of a conductive film that prevents moire from being visually
recognized even when it is superimposed on a black matrix of a
display unit. As a result, they found that the reason why the
moire is visually recognized due to the breaks having a regular
8
period in the conductive films according to the conventional
techniques and the prior application filed by the present
applicant can be explained by a difference in spatial frequency
characteristics between a case in which the conductive film has
only a mesh pattern (without breaks) and a case in which the
conductive film has a mesh pattern (with breaks) including
breaks having a regular period as shown in FIGS. 17(A) and
17(B).
Herein, FIG. 17(A) is a view showing spatial frequency
characteristics in a case of a mesh pattern (without breaks) in
which no break (disconnection portion) is present and the moire
recognition property has been optimized, and FIG. 17(B) is a
view showing the spatial frequency characteristics in a case of
a mesh pattern (with breaks) including breaks having a regular
period. As is evident from FIGS. 17(A) and 17(B), in the mesh
pattern including breaks having a regular period, the number of
spectral peaks has increased, but the spectral intensity of the
increased spectral peaks is not so high.
In this way, from FIGS. 17(A) and 17(B), the present
inventors found that depending on the presence or absence of
breaks, the spatial frequency characteristics of the mesh
pattern change, and the change exerts an influence on the moire
recognition property. As a result, they obtained knowledge that
in order to design a pattern having excellent moire recognition
property, it is important to design the pattern in consideration
of the breaks. Based on the knowledge, the present inventors
accomplished the present invention.
[0012]
That is, the conductive film according to the first aspect
of the present invention is a conductive film installed on a
display unit of a display device, comprising: a transparent
substrate; and mesh-like wiring which is formed on at least one
surface of the transparent substrate and has a mesh pattern
formed of a plurality of patterned thin metal wires, wherein the
mesh pattern of the mesh-like wiring is superimposed on a pixel
9
array pattern of the display unit, a spectral intensity of moire
of a lowest frequency is equal to or less than -3.6 expressed in
terms of common logarithm, and the spectral intensity of moire
of the lowest frequency is represented by convolution of spatial
frequency characteristics of the mesh pattern that are obtained
at least when the mesh pattern is observed from a front side and
spatial frequency characteristics of the pixel array pattern of
the display unit that are obtained at least when the pixel array
pattern is observed from a front side.
Preferably, the mesh-like wiring has an electrode potion,
which includes an electrode wiring pattern formed of the
plurality of thin metal wires in a form of a continuous mesh,
and a non-electrode portion, which is formed of the plurality of
thin metal wires in a form of a mesh, has a plurality of
disconnection portions, includes a discontinuous non-electrode
wiring pattern, and is insulated from the electrode portion, the
mesh pattern of the mesh-like wiring is constituted with the
electrode wiring pattern of the electrode portion and the nonelectrode
wiring pattern of the non-electrode portion insulated
from the electrode wiring pattern, and the spatial frequency
characteristics of the mesh pattern are spatial frequency
characteristics of the mesh pattern including the plurality of
disconnection portions that are obtained at least when the mesh
pattern is observed from the front side.
[0013]
In order to achieve the above objects, the method for
determining a wiring pattern of a conductive film according to
the second aspect of the present invention is a method for
determining a mesh pattern of a conductive film which is
installed on a display unit of a display device and in which
mesh-like wiring having a mesh pattern formed of a plurality of
patterned thin metal wires in a form of a continuous mesh has
been formed, the method comprising the steps of: obtaining
transmittance period image data of the mesh pattern and
transmittance period image data of a pixel wiring pattern of the
10
display unit on which the mesh pattern is superimposed;
performing two-dimensional Fourier transform on the obtained
transmittance period image data of the mesh pattern and on the
obtained transmittance period image data of the pixel array
pattern to obtain spatial frequency characteristics of the mesh
pattern and spatial frequency characteristics of the pixel array
pattern, the spatial frequency characteristics of the mesh
pattern and the pixel array pattern being obtained at least when
the mesh pattern and the pixel array pattern are observed from a
front side; calculating frequencies and spectral intensities of
moires represented by convolution of the spatial frequency
characteristics of the mesh pattern and the spatial frequency
characteristics of the pixel array pattern, from the obtained
spatial frequency characteristics of the mesh pattern and the
pixel array pattern; determining a lowest frequency among the
calculated frequencies of the moires, and comparing the spectral
intensity of the moire of the lowest frequency with -3.6
expressed in terms of a common logarithm; and setting the mesh
pattern to be a mesh pattern of the conductive film when the
spectral intensity of the moire of the lowest frequency defined
by the common logarithm is equal to or less than -3.6, and when
the spectral intensity of the moire of the lowest frequency is
greater than -3.6, updating the transmittance period image data
of the mesh pattern to transmittance period image data of a new
mesh pattern, and repeating the respective steps of obtaining
spatial frequency characteristics, calculating frequencies and
spectral intensities of moires, and comparing the spectral
intensity of the moire of the lowest frequency with -3.6 until
the spectral intensity of the moire of the lowest frequency
becomes equal to or less than -3.6.
[0014]
Preferably, the mesh-like wiring has the mesh pattern
including an electrode wiring pattern, which is formed of the
plurality of thin metal wires in the form of a continuous mesh,
and a non-electrode wiring pattern, which is formed of the
11
plurality of thin metal wires in the form of a mesh, has a
plurality of disconnection portions, and is discontinuous to and
insulated from the electrode wiring pattern, the transmittance
period image data of the mesh pattern is transmittance period
image data of the mesh pattern including the non-electrode
wiring pattern having the plurality of disconnection portions,
and the spatial frequency characteristics of the mesh pattern is
spatial frequency characteristics of the mesh pattern including
the plurality of disconnection portions that are obtained at
least when the mesh pattern is observed from a front side.
Preferably, based on the obtained spatial frequency
characteristics of the mesh pattern, spectral peaks of which the
peak intensity is equal to or greater than -4.5 expressed in
terms of a common logarithm are extracted from a plurality of
spectral peaks of two-dimensional Fourier spectra of the
transmittance period image data of the mesh pattern, and peak
frequencies and peak intensities of all of the extracted
spectral peaks are calculated; based on the obtained spatial
frequency characteristics of the pixel array pattern, spectral
peaks of which the peak intensity is equal to or greater than -
4.5 expressed in terms of a common logarithm are extracted from
a plurality of spectral peaks of two-dimensional Fourier spectra
of the transmittance period image data of the pixel array
pattern, and peak frequencies and peak intensities of all of the
extracted spectral peaks are calculated; and the frequencies and
the spectral intensities of the moires are calculated from the
peak frequencies and the peak intensities of the mesh pattern
calculated as above and from the peak frequencies and the peak
intensities of the pixel array pattern calculated as above.
[0015]
In the first aspect, preferably, a frequency of the moire
is given as a difference between a peak frequency of a spectral
peak of the spatial frequency characteristics of the mesh
pattern and a peak frequency of a spectral peak of the spatial
frequency characteristics of the pixel array pattern, and a
12
spectral intensity of the moire is given as a product of a peak
intensity of the spectral peak of the mesh pattern and a peak
intensity of the spectral peak of the pixel array pattern.
In the second aspect, preferably, as the frequency of the
moire, a difference between the peak frequency of the mesh
pattern and the peak frequency of the pixel array pattern is
calculated, and as the spectral intensity of the moire, a
product of two pairs of vector intensities including the peak
intensity of the mesh pattern and the peak intensity of the
pixel array pattern is calculated.
And, in the first and second aspects, preferably, the peak
intensity is a sum of intensities in a plurality of pixels in a
vicinity of the peak position, and each peak intensity is
standardized by using transmittance period image data of each of
the mesh pattern and the pixel array pattern.
[0016]
In order to achieve the above objects, the conductive film
according to the third aspect of the present invention is a
conductive film installed on a display unit of a display device,
comprising: a transparent substrate; and mesh-like wiring which
is formed on at least one surface of the transparent substrate
and has a mesh pattern formed of a plurality of patterned thin
metal wires on one surface thereof, wherein the mesh-like wiring
has an electrode potion, which includes an electrode wiring
pattern formed of the plurality of thin metal wires in a form of
a continuous mesh, and a non-electrode portion, which is formed
of the plurality of thin metal wires in a form of a mesh, has a
plurality of disconnection portions, includes a discontinuous
non-electrode wiring pattern, and is insulated from the
electrode portion, the mesh pattern of the mesh-like wiring is
constituted with the electrode wiring pattern of the electrode
portion and the non-electrode wiring pattern of the nonelectrode
portion insulated from the electrode wiring pattern,
and is superimposed on a pixel array pattern of the display
unit, when the plurality of disconnection portions of the non-
13
electrode wiring pattern of the non-electrode portion is
connected to each other, the mesh pattern of the mesh-like
wiring prevents moire from being visually recognized, and the
non-electrode wiring pattern of the non-electrode portion is a
random wiring pattern in which the plurality of disconnection
portions have been randomly arranged.
[0017]
In the first, second and third aspects, preferably, a
frequency of the moire is equal to or less than 3 cycles/mm.
Preferably, the non-electrode wiring pattern of the nonelectrode
portion is formed of the plurality of thin metal wires
in a form of a mesh within a region excluding the electrode
portion.
And, preferably, the pixel array pattern is a black matrix
pattern.
[0018]
In order to achieve the above objects, a display device
according to the fourth aspect of the present invention
comprises: a display unit; and the conductive film according to
the first and third aspect that is installed on the display
unit.
In order to achieve the above objects, a touch panel
display device according to the fifth aspect of the present
invention comprises: the display device according to the fourth
aspect; and a transparent substrate which is disposed on an
upper side of the conductive film of the display device and has
a touch surface on the side opposite to the conductive film.
ADVANTAGEOUS EFFECTS OF INVENTION
[0019]
Being constituted as above according to the present
invention, it is possible to inhibit the occurrence of moire and
to greatly improve visibility, even in a case in which a
conductive film installed on a display unit of a display device
has a plurality of disconnection portions in mesh-like wiring
14
having a mesh pattern composed of thin metal wires.
Particularly, even in a case in which a transparent
conductive film having mesh-like wiring including a plurality of
disconnection portions is used as an electrode for a touch panel
that needs to be made into a large-sized touch panel and to have
higher resolution, according to the present invention, it is
possible to inhibit the occurrence of moire that greatly impairs
image quality and to greatly improve the visibility of display
on the touch panel, when the conductive film is superimposed on
a black matrix of a display unit of the display device and
visually recognized.
BRIEF DESCRIPTION OF DRAWINGS
[0020]
FIG. 1 is a plan view schematically showing an example of a
conductive film according to a first embodiment of the present
invention.
FIG. 2 is a partially enlarged plan view of the conductive
film shown in FIG. 1.
FIG. 3 is a partially enlarged plan view of the conductive
film shown in FIG. 2, schematically showing an example of a
plurality of disconnection portions of a mesh pattern thereof.
FIG. 4 is a schematic partial cross-sectional view of the
conductive film shown in FIG. 3.
FIG. 5 is a plan view schematically showing an example of a
wiring layer on one side of a conductive film according to a
second embodiment of the present invention.
FIG. 6 is a partially enlarged plan view of the wiring
layer of the conductive film shown in FIG. 5, schematically
showing an example of a plurality of disconnection portions of a
mesh pattern thereof.
FIG. 7 is a schematic partial cross-sectional view of the
conductive film shown in FIG. 6.
FIG. 8 is a schematic view illustrating an example of a
pixel array pattern of a portion of a display unit to which the
15
conductive film according to the present invention is applied.
FIG. 9 is a schematic cross-sectional view of an example of
a display device into which the conductive film shown in FIG. 7
has been incorporated.
FIG. 10 is a flowchart showing an example of a method for
determining a mesh pattern of the conductive film according to
the present invention.
FIG. 11(A) is a schematic view illustrating an example of a
pixel array pattern of a display unit to which the conductive
film according to the present invention is applied; FIG. 11(B)
is a schematic view illustrating an example of a wiring pattern
of the conductive film superimposed on the pixel array pattern
shown in FIG. 11(A); and FIG. 11C is a partially enlarged view
of the pixel array pattern shown in FIG. 11(A).
FIG. 12(A) is a view showing the intensity characteristics
of two-dimensional Fourier spectra of transmittance period image
data of the pixel array pattern shown in FIG. 11(A), and FIG.
12B is a view showing the intensity characteristics of twodimensional
Fourier spectra of transmittance period image data
of the wiring pattern shown in FIG. 11(B).
FIG. 13 is a graph showing peak frequency positions of the
pixel array pattern of the display unit shown in FIG. 11(A).
FIG. 14(A) is a graph showing an example of the intensity
characteristics of the two-dimensional Fourier spectra by using
a curve, and FIG. 14(B) is a bar graph showing an example of the
intensity characteristics of the two-dimensional Fourier spectra
by using bars.
FIG. 15 is a view schematically illustrating frequency
information and spectral intensities of moires occurring due to
the interference between the pixel array pattern shown in FIG.
11(A) and the wiring pattern shown in FIG. 11(B).
FIG. 16 is a plan view showing a simulation sample of a
mesh pattern of Comparative example 1.
FIG. 17(A) is a view showing the spatial frequency
characteristics in a case of a mesh pattern (without breaks) not
16
having breaks (disconnection portions), and FIG. 17(B) is a view
showing the spatial frequency characteristics in a case of a
mesh pattern (with breaks) including breaks having a regular
period.
DESCRIPTION OF EMBODIMENTS
[0021]
Hereinafter, a conductive film and a method for determining
a pattern of the conductive film according to the present
invention will be described in detail with reference to
preferred embodiments illustrated in the accompanying drawings.
In the following description, a conductive film for a touch
panel which has disconnection portions in mesh-like wiring will
be explained as a representative example of the conductive film
according to the present invention. However, the present
invention is not limited to this example as long as it is a
conductive film installed on a display unit of a display device
such as a liquid crystal display (LCD), a plasma display panel
(PDP), an organic electroluminescence display (OELD), an
inorganic EL display, or the like, and it is needless to say
that as long as the conductive film has the disconnection
portions in the mesh-like wiring, it may be, for example, a
conductive film for electromagnetic wave-shielding, or the like.
[0022]
FIG. 1 is a plan view schematically showing an example of
the entirety of a conductive film according to a first
embodiment of the present invention, FIG. 2 is a partially
enlarged plan view of the conductive film, and FIG. 3 is a
partially enlarged plan view schematically showing an example of
a plurality of disconnection portions of a mesh pattern of the
conductive film. FIG. 4 is a schematic partial cross-sectional
view of the conductive film shown in FIG. 3. In FIG. 1, for
better understanding, an electrode portion of the mesh-like
wiring of the conductive film is indicated as a region
surrounded by thick lines, and a dummy electrode portion is
17
indicated as a region of diagonal lines. Furthermore, in FIGS. 2
and 3, for better understanding, within the mesh pattern of the
mesh-like wiring of the conductive film, an electrode wiring
pattern is indicated by thick lines, and a dummy electrode
pattern is indicated by thin lines. However, needless to say,
the patterns are formed of the same opaque thin metal wires, and
there is no difference in the thickness between the patterns.
[0023]
As shown in the drawings, a conductive film 10 according to
this embodiment is installed on a display unit of a display
device and is a conductive film having the mesh pattern (wiring
pattern) that is excellent in suppression of occurrence of moire
with respect to a black matrix (BM) of the display unit,
particularly, a conductive film in which the mesh-like wiring
having the mesh pattern is formed, and the mesh pattern is
optimized in terms of moire recognition property with respect to
the BM pattern when the conductive film is superimposed on the
BM pattern. The conductive film 10 includes a transparent
substrate 12, a wiring layer 16 that is formed on approximately
the whole surface of the transparent substrate 10 (on the upper
surface in FIG. 4) and that is formed of a plurality of
patterned opaque thin wires made of metal (hereinafter, referred
to as thin metal wires) 14, and a protective layer 20 bonded to
approximately the whole surface of the wiring layer 16 through
an adhesive layer 18 so as to cover the thin metal wires 14.
[0024]
The transparent substrate 12 is formed of a material having
an insulating property and having a high translucency, and
examples thereof include a resin, a glass, and silicon. Examples
of the resin include Polyethylene Terephthalate (PET),
Polymethyl methacrylate (PMMA), polypropylene (PP), polystyrene
(PS), and the like.
The wiring layer 16 includes mesh-like wiring 22 formed of
the plurality of thin metal wires 14. The thin metal wire 14 is
not particularly limited as long as it is a thin wire made of
18
metal having high conductivity, and examples of the thin metal
wire include a thin wire made of gold (Au), silver (Ag), copper
(Cu), or the like. The line width of the thin metal wire 14 is
preferably small in terms of recognition property, and can be,
for example, less than or equal to 30 m. For application to a
touch panel, the line width of the thin metal wires 14
preferably ranges from 0.1 m to 15 m, more preferably ranges
from 1 m to 9 m, and even more preferably ranges from 2 m to 7
m.
[0025]
Specifically, the mesh-like wiring 22 has a wiring pattern
in which the plurality of thin metal wires 14 in two directions
has been wired so as to cross each other. That is, the mesh-like
wiring 22 has a mesh pattern 24 in which the plurality of thin
metal wires 14 have been arranged in the form of a mesh. In the
illustrated example, the mesh shape of an opening 23 formed by
the mesh pattern 24 is a rhombic and can be referred to as a
diamond pattern, but the present invention is not limited
thereto. Any polygonal shape having at least three sides may be
employed as long as it can constitute the mesh pattern 24
optimized in terms of moire recognition property with respect to
a predetermined BM pattern which will be described later. The
mesh shapes may be the same as or different from each other, and
examples thereof include polygons that are the same as or
different from each other, such as triangles, for example, a
regular triangle and an equilateral triangle, quadrangles
(rectangles), for example, a square and rectangles, pentagons,
and hexagons. That is, as long as it is a mesh pattern optimized
in terms of moire recognition property with respect to the BM
pattern, a mesh pattern formed by the arrangement of openings 23
having regularity or a mesh pattern randomized by the
arrangement of openings 23 having different shapes may be
employed.
[0026]
19
The mesh-like wiring 22 has an electrode portion 22a, which
includes an electrode wiring pattern 24a formed of the plurality
of thin metal wires 14 in the form of a continuous mesh, and a
dummy electrode portion (non-electrode portion) 22b, which is
also formed of the plurality of thin metal wires in the form of
a mesh, has a plurality of disconnection portions 26 and a
discontinuous dummy electrode (non-electrode) wiring pattern
24b, and is insulated from the electrode portion 22a. In the
example shown in the drawings, the electrode wiring pattern 24a
of the electrode portion 22a and the dummy electrode wiring
pattern 24b of the dummy electrode portion 22b are wiring
patterns having the same mesh shape (rhomboid). By the synthesis
of the electrode wiring pattern 24a and the dummy electrode
wiring pattern 24b, the mesh pattern 24 of the mesh-like wiring
22 is formed.
Herein, the electrode wiring pattern 24a of the electrode
portion 22a shown in the drawings is an electrode pattern
constituting an X electrode. However, the present invention is
not limited to such a constitution. The electrode wiring pattern
24a may be any of the conventionally known electrode patterns
such as a stripe electrode, a bar-and-stripe electrode, a
diamond electrode, and a snowflake electrode, as long as it is
an electrode pattern used in a capacitive type touch sensor
(panel).
[0027]
The thin metal wires 14 formed in the form of a mesh in the
electrode portion 22a do not have the disconnection portions 26
and are continuous to each other. In contrast, in the thin metal
wires 14 formed in the form of a mesh in the dummy electrode
portion 22b, the plurality of disconnection portions (cut
portions) 26 has been formed, and a plurality of disconnections
has been added thereto. Between the thin metal wire 14 in the
electrode portion 22a and the thin metal wire 14 in the dummy
electrode portion 22b, the disconnection portion 26 is provided
without exception. Therefore, the thin metal wire 14 of the
20
electrode portion 22a and the thin metal wire 14 of the dummy
electrode portion 22b are disconnected from each other and in a
discontinuous state. That is, the dummy electrode portion 22b
and the electrode portion 22a are electrically insulated from
each other.
As described above, the mesh pattern 24 of the mesh-like
wiring 22 is a mesh pattern including the plurality of
disconnection portions 26. The constitution necessary for the
mesh pattern 24 of the mesh-like wiring 22 of the conductive
film 10 of the present invention will be described later.
[0028]
As materials of the adhesive layer 18, a wet laminate
adhesive, a dry laminate adhesive, a hot melt adhesive, or the
like can be mentioned.
Similarly to the transparent substrate 12, the protective
layer 20 is formed of a material having a high translucency,
such as a resin, a glass, and silicon. The refractive index n1
of the protective layer 20 is preferably a value that is equal
to or close to the refractive index n0 of the transparent
substrate 12. In this case, the relative refractive index nr1 of
the transparent substrate 12 with respect to the protective
layer 20 becomes a value close to 1.
[0029]
Herein, the refractive index in this specification means a
refractive index for light with a wavelength of 589.3 nm (D line
of sodium). For example, in regard to resins, the refractive
index is defined by ISO 14782: 1999 (corresponding to JIS K
7105) that is an international standard. In addition, the
relative refractive index nr1 of the transparent substrate 12
with respect to the protective layer 20 is defined as nr1 =
(n1/n0). Herein, it is preferable that the relative refractive
index nr1 is in a range of 0.86 or more and 1.15 or less, and a
range of 0.91 or more and 1.08 or less is more preferable.
By limiting the relative refractive index nr1 to this range
and controlling light transmittance between members of the
21
transparent substrate 12 and the protective layer 20, it is
possible to further improve moire recognition property.
[0030]
The conductive film 10 according to the first embodiment
described above has the wiring layer 16 only on one surface of
the transparent substrate 12, but the present invention is not
limited to this configuration, and the conductive film 10 may
have a wiring portion on both surfaces of the transparent
substrate 12.
FIG. 5 is a plan view schematically showing an example of
one side of a conductive film according to a second embodiment
of the present invention, that is, an example of a second wiring
layer on the lower side. FIG. 6 is a partially enlarged plan
view of the second wiring layer, schematically showing an
example of a plurality of disconnection portions of the mesh
pattern. FIG. 7 is a schematic partial cross-sectional view of
the conductive film shown in FIG. 6. In FIG. 5, for better
understanding, an electrode portion of the mesh-like wiring of
the conductive film is indicated as a region of diagonal lines,
and a dummy electrode portion is indicated as a region
surrounded by dot-and-dash lines. Furthermore, in FIG. 6, for
better understanding, within a mesh pattern of the mesh-like
wiring of the conductive film, an electrode wiring pattern is
indicated by thick lines, and a dummy electrode pattern is
indicated by thin lines. However, needless to say, these
patterns are formed of the same opaque thin metal wires, and
there is no difference in the thickness between the patterns.
Herein, the plan view of the other side of the conductive
film of the second embodiment shown in FIG. 7, that is, the plan
view of a first wiring layer on the upper side is the same as
the plan view of the conductive film of the first embodiment of
the present invention shown in FIGS. 1 to 3. Therefore, the plan
view of the first wiring layer on the upper side will not be
described herein.
[0031]
22
As shown in FIG. 7, a conductive film 11 of the second
embodiment of the present invention has a first wiring layer 16a
formed on one surface (the upper side in FIG. 7) of a
transparent substrate 12, a second wiring layer 16b formed on
the other surface (the lower side of FIG. 7) of the transparent
substrate 12, a first protective layer 20a bonded to
approximately the whole surface of the first wiring layer 16a
through a first adhesive layer 18a, and a second protective
layer 20b bonded to approximately the whole surface of the
second wiring layer 16b through a second adhesive layer 18b.
As described above, the transparent substrate 12 is formed
of an insulating material, and the second wiring layer 16b and
the first wiring layer 16a are electrically insulated from each
other. Furthermore, each of the first and second wiring layers
16a and 16b can be formed of the same materials and can be
formed in the same manner as the wiring layer 16 of the
conductive film 10 shown in FIG. 4.
[0032]
Similarly to the wiring layer 16 shown in FIGS. 1 to 3, the
first wiring layer 16a of the conductive film 11 of the present
embodiment includes the mesh-like wiring 22 having the electrode
portion 22a, which is formed of the plurality of thin metal
wires 14 and includes the electrode wiring pattern 24a, and the
dummy electrode portion 22b, which includes the dummy electrode
wiring pattern 24b having the plurality of disconnection
portions 26, and the mesh pattern 24 which is a synthetic
pattern of the electrode wiring pattern 24a and the dummy
electrode wiring pattern 24b, although such a constitution is
not shown in the drawing.
Herein, the first wiring layer 16a of the conductive film
11 has the same constitution as the wiring layer 16 of the
conductive film 10 shown in FIGS. 1 to 4. Therefore, the details
thereof will not be described herein.
[0033]
In the conductive film 11, the second wiring layer 16b is
23
formed of the plurality of opaque thin metal wires 14 and has
been formed on the other surface (the lower side in FIG. 7) of
the transparent substrate 12.
As shown in FIGS. 5 and 6, the second wiring layer 16b
includes mesh-like wiring 28 formed of the plurality of thin
metal wires 14.
Specifically, similarly to the mesh-like wiring 22 shown in
FIGS.1 to 3, the mesh-like wiring 28 has a wiring pattern in
which the plurality of thin metal wires 14 in two directions has
been wired so as to cross each other. That is, the mesh-like
wiring 28 has a mesh pattern 30 in which the plurality of thin
metal wires 14 has been arranged in the form of a mesh. In the
example shown in the drawings, the mesh shape of an opening 29
formed by the mesh pattern 30 is rhombic and can be referred to
as a diamond pattern. The opening 29 of the mesh pattern 30 of
the mesh-like wiring 28 has the same mesh shape as an opening 23
of the mesh pattern 24 of the mesh-like wiring 22 shown in FIGS.
1 to 3. Therefore, the details thereof will not be described
herein.
[0034]
The mesh-like wiring 28 has an electrode portion 28a, which
includes an electrode wiring pattern 30a formed of the plurality
of thin metal wires 14 in the form of a continuous mesh, and a
dummy electrode portion 28b, which is also formed of the
plurality of thin metal wires, has the plurality of
disconnection portions 26, includes the discontinuous dummy
electrode wiring pattern 30b, and is insulated from the
electrode portion 28a. Herein, in the example shown in the
drawings, the electrode wiring pattern 30a of the electrode
portion 28a and the dummy electrode wiring pattern 30b of the
dummy electrode portion 28b are wiring patterns having the same
mesh shape (rhomboid), and by the synthesis of the electrode
wiring pattern 30a and the dummy electrode wiring pattern 30b,
the mesh pattern 30 of the mesh-like wiring 28 is formed.
Herein, in the example shown in the drawings, the dummy
24
electrode wiring pattern 30b of the dummy electrode portion 28b
has a line shape, and the electrode wiring pattern 24a of the
electrode portion 22a is an electrode pattern constituting a
stripe electrode. However, the present invention is not limited
to such a constitution, and the pattern may be any of the
conventionally known electrode patterns such as an X electrode,
a bar-and-stripe electrode, a diamond electrode, and a snowflake
electrode, as long as it is an electrode pattern used in a
capacitive type touch sensor (panel).
[0035]
The thin metal wires 14 formed in the form of a mesh in the
electrode portion 28a do not have the disconnection portions 26
and are continuous to each other. In contrast, in the thin metal
wires 14 formed in the form of a mesh in the dummy electrode
portion 28b, the plurality of disconnection portions (cut
portions) 26 has been provided, and thus a plurality of
disconnections has been added thereto. Between the thin metal
wire 14 in the electrode portion 28a and the thin metal wire 14
in the dummy electrode portion 28b, the disconnection portion 26
is provided without exception. Therefore, the thin metal wire 14
of the electrode portion 28a and the thin metal wire 14 of the
dummy electrode portion 28b are disconnected from each other and
in a discontinuous state. That is, the dummy electrode portion
28b is electrically insulated from the electrode portion 28a.
As described above, the mesh pattern 30 of the mesh-like
wiring 28 is a mesh pattern including the plurality of
disconnection portions 26. Herein, the constitution necessary
for the mesh pattern 30 of the mesh-like wiring 28 of the
conductive film 11 of the present invention will be described
later.
[0036]
The first protective layer 20a is bonded to approximately
the whole surface of the first wiring layer 16a through the
first adhesive layer 18a so as to cover the thin metal wires 14
of the first wiring layer 16a.
25
Furthermore, the second protective layer 20b is bonded to
approximately the whole surface of the second wiring layer 16b
through the second adhesive layer 18b so as to cover the thin
metal wires 14 of the second wiring layer 16b.
Each of the first adhesive layer 18a and the second
adhesive layer 18b can be formed of the same material and can be
formed in the same manner as the adhesive layer 18 of the
conductive film 10 shown in FIG. 4. However, the material of the
first adhesive layer 18a may be the same as or different from
the material of the second adhesive layer 18b.
Moreover, each of the first protective layer 20a and the
second protective layer 20b can be formed of the same material
and can be formed in the same manner as the protective layer 20
of the conductive film 10 shown in FIG. 4. However, the material
of the first protective layer 20a may be the same as or
different from the material of the second protective layer 20b.
[0037]
Both the refractive index n2 of the first protective layer
20a and the refractive index n3 of the second protective layer
20b may be a value equal or close to the refractive index n0 of
the transparent substrate 12, similarly to the protective layer
20 of the conductive film 10 according to the first embodiment.
In this case, both the relative refractive index nr2 of the
transparent substrate 12 with respect to the first protective
layer 20a and the relative refractive index nr3 of the
transparent substrate 12 with respect to the second protective
layer 20b are a value close to 1. Herein, the definitions of the
refractive index and the relative refractive index are the same
as the definitions in the first embodiment. Accordingly, the
relative refractive index nr2 of the transparent substrate 12
with respect to the first protective layer 20a is defined as
nr2=(n2/n0), and the relative refractive index nr3 of the
transparent substrate 12 with respect to the first protective
layer 20b is defined as nr2=(n3/n0).
Herein, similarly to the aforementioned relative refractive
26
index nr1, it is preferable that the relative refractive index
nr2 and the relative refractive index nr3 are in a range of 0.86
or more and 1.15 or less, and a range of 0.91 or more and 1.08
or less is more preferable.
By limiting the relative refractive index nr2 and the
relative refractive index nr3 to this range, it is possible to
further improve moire recognition property, as the limitation of
the range of the relative refractive index nr1.
[0038]
The conductive film 10 of the first embodiment and the
conductive film 11 of the second embodiment of the present
invention described above are applied to, for example, a touch
panel of a display unit 31 (display portion) of which a part is
schematically shown in FIG. 8. The conductive films have a mesh
pattern (24, 30) having been optimized in terms of moire
recognition property with respect to the pixel array pattern of
the display unit 31, that is, the black matrix (hereinafter,
also referred to as “BM”) pattern of the display unit 31.
Herein, in the present invention, the mesh pattern having
been optimized in terms of moire recognition property with
respect to the BM (pixel array) pattern refers to one, two, or
more groups of mesh patterns in which moire with respect to a
predetermined BM pattern is not visually recognized by a human
being. Furthermore, in the present invention, in two or more
groups of optimized mesh patterns, it is possible to rank the
mesh patterns from a mesh pattern which is most unlikely to be
visually recognized to a mesh pattern which is less likely to be
visually recognized, and one mesh pattern in which moire is most
unlikely to be visually recognized can also be determined.
[0039]
In the present invention, the spectral intensity of the
moire of the lowest frequency represented by the convolution of
the spatial frequency characteristics of the mesh pattern, which
are obtained at least when the mesh pattern is observed from the
front, and the spatial frequency characteristics of the BM
27
pattern of the display unit, which are obtained at least when
the BM pattern is observed from the front, needs to be at least
equal to or less than -3.6 expressed in terms of the common
logarithm (10-3.6 expressed in terms of the antilogarithm).
Herein, a case in which the mesh pattern of the conductive film
is a mesh pattern including a plurality of disconnection
portions is described as a typical example. However, as shown in
FIGS. 17(A) and 17(B), the moire is more easily visually
recognized in a mesh pattern including a plurality of
disconnection portions than in a mesh pattern not including
disconnection portions. Accordingly, needless to say, the
present invention can be applied to the mesh pattern not
including disconnection portions. That is, regardless of the
presence or absence of the disconnection portions, the present
invention can be applied to a mesh pattern in which the spectral
intensity of the moire of the lowest frequency represented by
the convolution of the spatial frequency characteristics of both
the mesh pattern and the BM pattern of the display unit is equal
to or less than -3.6 expressed in terms of the common logarithm
(10-3.6 expressed in terms of the antilogarithm).
In the present invention, the frequency of the moire as a
target is preferably equal to or less than 3 cycles/mm. This is
because, from experience, it was understood that the frequency
of the moire as an issue is within 3 cycles/mm by sensory
evaluation.
[0040]
Meanwhile, in the present invention, in a case in which the
moire recognition property has been optimized such that the
moire is not visually recognized even when the mesh pattern not
including the disconnection portions is superimposed on the BM
pattern of the display unit, if the plurality of disconnection
portions are added to the mesh pattern, at least one of the
position, length, arrangement (number), and the like of the
disconnection portions is caused to have randomness without
regularity, that is, the plurality of disconnection portions is
28
randomly arranged. In this way, it is possible to improve the
moire recognition property of a mesh pattern including the
plurality of disconnection portions, even when the mesh pattern
is superimposed on the BM pattern.
In the conductive film having the mesh pattern including
the plurality of disconnection portions, when the moire
recognition property of the mesh pattern in which the plurality
of disconnection portions is connected to each other (the mesh
pattern not including the disconnection portions) has been
optimized, it is possible to improve the moire recognition
property by forming a random wiring pattern, in which the
plurality of disconnection portions has been randomly arranged,
as the dummy electrode wiring pattern in the mesh pattern.
[0041]
As the mesh pattern not including the disconnection
portions, in which the moire recognition property has been
optimized, it is possible to use the mesh pattern of the
conductive film described in the specification of Japanese
Patent Application No. 2012-82711 filed by the present
applicant. In the specification, from the peak frequencies and
peak intensities of a plurality of spectral peaks of twodimensional
Fourier spectra of transmittance image data of the
mesh pattern, and from the peak frequencies and peak intensities
of a plurality of spectral peaks of two-dimensional Fourier
spectra of transmittance image data of a pixel array pattern,
the frequencies and spectral intensities of moires are
calculated. Thereafter, by acting visual response
characteristics of a human being on the calculated frequencies
and spectral intensities of moires, the frequencies and
intensities of moires are obtained. The mesh pattern disclosed
in the aforementioned specification is a wiring pattern in which
the sum of the spectral intensities of the moires, which have
frequencies falling into a predetermined range of a frequency
determined according to the visual response characteristics, is
equal to or less than a predetermined value with respect to the
29
obtained frequencies and intensities of moires.
The mesh pattern not including the disconnection portions,
in which the moire recognition property has been optimized, is
not limited to the mesh pattern described in the aforementioned
specification, and may be a conventionally known mesh pattern
not including disconnection portions in which the moire
recognition property has been optimized. As such a mesh pattern,
it is possible to use the mesh pattern described in Japanese
Patent Application No. 2011-221432, Japanese Patent Application
No. 2011-221434, Japanese Patent Application No. 2012-82706,
Japanese Patent Application No. 2012-166946, and the like filed
by the present applicant.
[0042]
Therefore, in the conductive films 10 and 11 of the present
invention, the mesh patterns 24 and 30 having been optimized in
terms of moire recognition property with respect to the pixel
array pattern of a display unit 31, that is, the black matrix
(hereinafter, also referred to as “BM”) pattern, and the
synthetic mesh pattern composed of the mesh patterns 24 and 30
satisfy at least one of the aforementioned conditions.
The details of the optimization of the moire recognition
property of the mesh pattern with respect to a predetermined BM
pattern will be described later.
The conductive film of the present invention is basically
constituted as above.
[0043]
FIG. 8 is a schematic view illustrating an example of a
pixel array pattern of a part of a display unit to which the
conductive film according to the present invention is applied.
As a part thereof is illustrated in FIG. 8, plural pixels
32 are arranged in a matrix shape to form a predetermined pixel
array pattern in the display unit 31. One pixel 32 has a
configuration in which three sub-pixels (a red sub-pixel 32r, a
green sub-pixel 32g, and a blue sub-pixel 32b) are arranged in
the horizontal direction. One sub-pixel has a rectangular shape
30
which is long in the vertical direction. The array pitch in the
horizontal direction (horizontal pixel pitch Ph) of the pixels
32 and the array pitch in the vertical direction (vertical pixel
pitch Pv) of the pixels 32 are substantially equal to each
other. That is, a shape formed by one pixel 32 and a black
matrix (BM) 34 (pattern material) surrounding the one pixel 32
is square (see a hatched area 36). The aspect ratio of one pixel
32 is not equal to 1, but set to be the length in the horizontal
direction (lateral) > the length in the vertical direction
(longitudinal).
[0044]
As can be apparently seen from FIG. 8, since the pixel
array pattern formed by the sub-pixels 32r, 32g, and 32b of the
plural pixels 32 is defined by the BM pattern 38 of the BM 34
surrounding the respective sub-pixel 32r, 32g, and 32b and the
moire occurring when the display unit 31 and the conductive film
10 or 11 are superimposed on each other is generated by the
interference between the BM pattern 38 of the BM 34 of the
display unit 31 and the mesh pattern 24 or 30 of the conductive
film 10 or 11, the BM pattern 38 is strictly an inverted pattern
of the pixel array pattern, but herein, both are treated to
represent the same pattern.
[0045]
For example, when the conductive film 10 or 11 is disposed
on the display panel of the display unit 31 having the BM
pattern 38 formed by the BM 34, since the mesh pattern 24 of the
conductive film 11 has been optimized in terms of moire
recognition property with respect to the BM (pixel array)
pattern 38, there is no interference in spatial frequency
between the array period of the pixels 32 and the wiring
arrangement of the thin metal wires 14 of the conductive film 10
or 11, and thus occurrence of moire is suppressed.
The display unit 31 illustrated in FIG. 8 may be configured
as a display panel such as a liquid crystal panel, a plasma
panel, an organic EL panel, and an inorganic EL panel.
31
[0046]
Next, a display device into which the conductive film
according to the present invention is assembled will be
described below with reference to FIG. 9. In FIG. 9, a projected
capacitive type touch panel into which the conductive film 11
according to the second embodiment of the present invention is
assembled will be described as a representative example of the
display device 40, but it is needless to say that the present
invention is not limited to this example.
[0047]
As shown in FIG. 9, the display device 40 includes the
display unit 31 (refer to FIG. 8) that can display a color image
and/or a monochrome image, a touch panel 44 that detects a
contact position from an input screen 42 (arrow Z1 direction
side), and a housing 46 in which the display unit 31 and the
touch panel 44 are housed. The user can access the touch panel
44 through a large opening provided on the surface (arrow Z1
direction side) of the housing 46.
[0048]
The touch panel 44 includes not only the conductive film 11
(refer to FIGS. 5, 6 and 7) described above but also a cover
member 48 laminated on the surface (arrow Z1 direction side) of
the conductive film 11, a flexible substrate 52 electrically
connected to the conductive film 11 through a cable 50, and a
detection control unit 54 disposed on the flexible substrate 52.
[0049]
The conductive film 11 is bonded to the surface (arrow Z1
direction side) of the display unit 31 through an adhesive layer
56. The conductive film 11 is disposed on the display screen
such that the other main surface side (second wiring layer 16b
side) faces the display unit 31.
[0050]
The cover member 48 functions as the input screen 42 by
covering the surface of the conductive film 11. In addition, by
preventing direct contact of a contact body 58 (for example, a
32
finger or a stylus pen), it is possible to suppress the
occurrence of a scratch, adhesion of dust, and the like, and
thus it is possible to stabilize the conductivity of the
conductive film 11.
[0051]
For example, the material of the cover member 48 may be a
glass or a resin film. One surface (arrow Z2 direction side) of
the cover member 48 may be coated with silicon oxide or the like
and may be bonded to one surface (arrow Z1 direction side) of
the conductive film 11. In order to prevent damage due to
rubbing or the like, the conductive film 11 and the cover member
48 may be pasted together.
[0052]
The flexible substrate 52 is an electronic substrate having
flexibility. In the example shown in the drawing, the flexible
substrate 52 is fixed to the inner wall of the side surface of
the housing 46, but the position fixedly set up may be changed
in various ways. The detection control unit 54 constitutes an
electronic circuit that catches a change in the capacitance
between the contact body 58 and the conductive film 11 and
detects the contact position (or the proximity position) when
the contact body 58 that is a conductor is brought into contact
with (or comes close to) the input screen 42.
The display device to which the conductive film according
to the present invention is applied basically has the abovementioned
configuration.
[0053]
Next, evaluation of moire recognition property of the mesh
pattern of the conductive film with respect to a predetermined
BM pattern of the display device in the present invention and
procedures of optimization will be described below. That is, in
the conductive film according to the present invention, the
procedures of determining a mesh pattern which is optimized so
that moire with respect to a predetermined BM pattern of the
display device is not visually recognized by a human being will
33
be described below.
FIG. 10 is a flowchart showing an example of a method for
determining a mesh pattern of the conductive film according to
the present invention.
[0054]
In the method for determining a mesh pattern of a
conductive film of the present invention, from peak frequencies
and peak intensities obtained by frequency analysis using Fast
Fourier Transform (FFT) of a BM (pixel array) pattern of a
display unit of a display device and a mesh pattern of a
conductive film, the frequencies and spectral intensities of
moires are calculated. Thereafter, the calculated frequencies
and spectral intensities of the moires are compared with the
conditions of frequencies and spectral intensities of moires
that have been determined from experience and prevent the moire
from being visually recognized. Then, a mesh pattern satisfying
the conditions is determined to be a mesh pattern which has been
optimized to prevent the moire from being visually recognized.
In the method of the present invention, FFT is generally used
for the frequency and spectral intensity of moire. However,
depending on the usage of FFT, the frequency and spectral
intensity of a target is greatly varied. Accordingly, the
following procedures are specified.
[0055]
In the method of the present invention, first, as Procedure
1, transmittance period image data (hereinafter, also referred
to as transmittance image data) of the BM pattern and the mesh
pattern is created. That is, as shown in FIG. 10, in Step S10,
transmittance period image data of the BM pattern 38 (BM 34)
(see FIG. 8) of the display unit 31 of the display device 40
shown in FIG. 9 and transmittance period image data of a mesh
pattern 62 (thin metal wires 14) (see FIG. 11(B)) of a
conductive film 60 that includes the disconnection portions 26
are created and obtained. Herein, when the transmittance image
data of the BM pattern 38 and the transmittance image data of
34
the mesh pattern 62 including the plurality of disconnection
portions 26 have already been prepared or accumulated, the
transmittance image data may be obtained from the prepared or
accumulated data.
[0056]
For example, as illustrated in FIG. 11(A) and FIG. 11C
which is a partially enlarged view of FIG. 11(A), the BM pattern
38 of the display unit 31 can be set to a pattern in which each
pixel 32 includes three color sub-pixels 32r, 32g, and 32b of
RGB, but when a single color is used and, for example, only the
sub-pixels 32g of G-channel are used, it is preferable that the
transmittance image data of R channel and B channel are set to
0. In the present invention, the image data of the BM 34, that
is, the transmittance image data of the BM pattern 38, is not
limited to a pattern having rectangular openings (sub-pixels
32r, 32g, and 32b) of the BM 34 as shown in FIG. 11(A), and a BM
pattern not having the rectangular openings of the BM 34 or a BM
pattern having arbitrary BM openings may be designated and used,
as long as it is a usable BM pattern. For example, the opening
is not limited to a simple rectangular shape, and may have an
intricately doglegged shape or a hook shape. Herein, for
example, the transmittance image data of the BM pattern 38 had
resolution of about 12,700 dpi and was in the form of binarized
data in which the opening was represented by 1.0 and other
portions were represented by 0.0.
[0057]
Meanwhile, for example, as shown in FIG. 11(B), the mesh
pattern 62 of the conductive film 60 can be in the form of
square lattices in which the thin metal wires 14 to be wiring
inclined by 45[deg]. The mesh pattern 62 is a wiring pattern in
which the plurality of thin metal wires 14 are disconnected from
each other by the plurality of disconnection portions 26. The
transmittance image data of the mesh pattern 62 is created as
period image data including the disconnection portions (breaks)
26. Herein, the transmittance image data of the mesh pattern 62
35
had resolution of about 12,700 dpi, and was in the form of
binarized data in which the internal area of the openings 23 and
29 in the mesh shape was represented by 0.0, and the portion of
the thin metal wires 14 that are wiring was represented by 1.0.
Herein, the size of the transmittance image data of the
mesh pattern 62 and the BM pattern 38 was specified to be, for
example, 5,020 (pixels)  2,423 (pixels). Furthermore, in order
to prevent or reduce periodic artifacts at the time of the FFT
processing of Procedure 2 which will be described later, it is
preferable to extract the data in a repetition period such that
the continuity is maintained. For example, it is preferable to
set the image size such that the image includes a region
corresponding to 4 images.
[0058]
Thereafter, as Procedure 2, two-dimensional fast Fourier
transform (2DFFT (base 2)) is performed on the transmittance
image data of the mesh pattern 62 and the BM pattern 38 that are
created in Procedure 1, thereby extracting spectra (peaks) of
predetermined intensities.
That is, as shown in FIG. 10, in Step S12, the 2DFFT
processing is performed on the respective transmittance image
data of the mesh pattern 62 and the BM pattern 38 that are
created in Step S10, thereby obtaining the spatial frequency
characteristics of the mesh pattern 62 including the
disconnection portions (breaks) 26, which are obtained at least
when the mesh pattern is observed from the front, and the
spatial frequency characteristics (two-dimensional Fourier
spectra) of the BM pattern 38, which are obtained at least when
the BM pattern is observed from the front. At this time,
although the two-dimensional Fourier spectra of the respective
transmittance image data of the mesh pattern 62 and the BM
pattern 38 are represented by complex numbers (including phase
information), the spectra (complex numbers) are standardized by
being divided by the image size (length  width (pix2)). For
example, a spectrum standardized by using the image size (pix2)
36
is given in the form of spectrum (complex number)/image size
(5,020  2,433 pix2).
[0059]
Subsequently, as Procedure 3, from the spatial frequency
characteristics of the mesh pattern 62 and the BM pattern 38
obtained in Procedure 2, the frequencies and spectral
intensities of the moires represented by the convolution of the
spatial frequency characteristics of the mesh pattern 62 and the
BM pattern 38 are calculated.
That is, as shown in FIG. 10, in Step S14, from the spatial
frequency characteristics of the mesh pattern 62 and the spatial
frequency characteristics of the BM pattern 38 that are obtained
in Step S12, the frequencies and spectral intensities of the
moires represented by the convolution (integration) of the
spatial frequency characteristics of the mesh pattern 62 and the
BM pattern 38 are calculated.
In Step S14, the frequencies and spectral intensities of
the moires can be calculated by the following Steps S16 and S18.
Herein, the spectral intensity of the two-dimensional
Fourier spectrum is defined by common logarithm so as to match
with the absolute value of the complex number and with the
vision of a human being.
[0060]
As shown in FIG. 10, in Step S16, based on the respective
spatial frequency characteristics of the mesh pattern 62 and the
BM pattern 38 that are obtained in Step S12, all of the spatial
frequencies of the spectra (peaks) of which the spectral
intensity (Log10 (an absolute value of a spectrum)) defined by
the common logarithm is equal to or greater than -4.5 are
extracted from the spectra of each of the patterns 62 and 38.
That is, from a plurality of spectral peaks of two-dimensional
Fourier spectra of the mesh pattern 62 and the BM pattern 38,
all of the spectral peaks of which the peak intensity is equal
to or greater than -4.5 expressed in terms of the common
logarithm are extracted, and the peak frequencies and peak
37
intensities of all of the extracted spectral peaks are
calculated.
The information obtained at this point in time includes
spatial frequencies fx and fy of the peak values of the spectra
and information on a complex number (a + bi). Herein, the peak
intensity is handled as an absolute value.
[0061]
FIG. 12(A) is a view showing intensity characteristics of
two-dimensional Fourier spectra of the transmittance image data
of the mesh pattern 62, and FIG. 12B is a view showing intensity
characteristics of two-dimensional Fourier spectra of the
transmittance image data of the BM pattern 38.
In FIGS. 12(A) and 12(B), a white portion indicates a
spectral peak having high intensity. Accordingly, from the
results shown in FIGS. 12(A) and 12(B), the peak frequency and
peak intensity of each spectral peak are calculated for each of
the mesh pattern 62 and the BM pattern 38. That is, the position
on frequency coordinates of each of the spectral peaks which are
shown in the intensity characteristics of the two-dimensional
Fourier spectra of the mesh pattern 62 and the BM pattern 38
shown in FIGS. 12(A) and 12(B) respectively, that is, the peak
position represents the peak frequency of the spectral peak, and
the intensity of the two-dimensional Fourier spectrum in the
peak position represents the peak intensity thereof.
[0062]
The peak frequency and peak intensity of each of the
spectral peaks of the mesh pattern 62 and the BM pattern 38 are
calculated and obtained as below.
First, in calculating peaks for obtaining the peak
frequency, from the basic frequencies of the mesh pattern 62 and
the BM pattern 38, frequency peaks are calculated. This is
because the transmittance image data subjected to the 2DFFT
processing is discrete values, and thus the peak frequency
depends on the reciprocal of the image size. As shown in FIG.
13, the positions of the frequency peaks can be expressed as a
38
combination of bars a and b which are independent twodimensional
basic frequency vector components. Accordingly,
naturally, the obtained peak positions form a lattice shape.
FIG. 13 is a graph showing the positions of the frequency peaks
in case of the BM pattern 38, but the positions of the frequency
peaks of the mesh pattern 62 can be determined in the same way.
[0063]
Meanwhile, in obtaining the peak intensity, the peak
position is determined in the process of obtaining the peak
frequency as described above. Therefore, the intensity (absolute
value) of the two-dimensional Fourier spectrum that the peak
position has is obtained. At this time, because digital data has
undergone FFT processing, the peak position includes a plurality
of pixels in some cases. For example, when the intensity (Sp)
characteristics of the two-dimensional Fourier spectrum are
represented by a curve (analogue value) shown in FIG. 14(A), the
intensity characteristics of the same two-dimensional Fourier
spectrum having undergone digitalization processing is
represented by a bar graph (digital value) shown in FIG. 14(B).
Herein, a peak P of the intensity in the two-dimensional Fourier
spectrum shown in FIG. 14(A) includes two pixels in the
corresponding FIG. 14(B). Consequently, in order to obtain the
intensity in the peak position, within a region including a
plurality of pixels in the vicinity of the peak position, the
sum of spectral intensities of a plurality of pixels ranked high
in terms of the spectral intensity is preferably used as the
peak intensity (absolute value). For example, within a region of
5  5 pixels, the sum of spectral intensities of top 5 pixels
ranked high in terms of the spectral intensity are preferably
used as the peak intensity.
Herein, the obtained peak intensity is preferably
standardized by using the image size. In the aforementioned
example, as described above, the peak intensity is preferably
standardized in advance by using the image size (5,020  2,433
pix2) (Parseval’s theorem).
39
[0064]
Then, as shown in FIG. 10, in Step S18, from the peak
frequencies and peak intensities of the two-dimensional Fourier
spectra of the mesh pattern 62 and the BM pattern 38 that are
calculated in Step S16, the frequencies and spectral intensities
of moires are calculated respectively. In this case, the peak
intensities and spectral intensities of the moire are also
handled as absolute values.
In the actual space, originally, the moire is caused by the
multiplication of the transmittance period image data of the
mesh pattern 62 and the BM pattern 38. Consequently, in the
spatial frequency space, convolution integral of the patterns is
performed. However, since the peak frequencies and peak
intensities of the two-dimensional Fourier spectra of both the
mesh pattern 62 and the BM pattern 38 are calculated in Step
S16, a difference (an absolute value of the difference) in the
frequency peak between the two patterns can be calculated; the
calculated difference can be taken as the frequency of the
moire; a product of 2 pairs of vector intensities obtained by
combining the two patterns can be calculated; and the calculated
product can be taken as the spectral intensity (absolute value)
of the moire.
The frequency and spectral intensity of the moire obtained
in this way can be regarded as outcomes of the convolution
integral of the respective spatial frequency characteristics of
the mesh pattern 62 and the BM pattern 38 obtained in Step S12.
[0065]
Herein, the difference between the respective frequency
peaks of the intensity characteristics of the two-dimensional
Fourier spectra of the mesh pattern 62 and the BM pattern 38
respectively shown in FIGS. 12(A) and 12(B) corresponds to the
relative distance between the peak positions on the frequency
coordinates of the frequency peaks of the mesh pattern 62 and
the BM pattern 38 in the intensity characteristics obtained by
superimposing the intensity characteristics of the two-
40
dimensional Fourier spectra of both patterns.
Each of the mesh pattern 62 and the BM pattern 38 has a
plurality of spectral peaks in the two-dimensional Fourier
spectra thereof. Therefore, the difference of frequency peaks
that is a value of the relative distance, that is, the frequency
of the moire, is obtained in a plural number. Consequently, if
both patterns have a large number of spectral peaks in the twodimensional
Fourier spectra, the number of the obtained
frequency of the moire is also increased, and as a result, it
takes a long period of time for calculation processing. In such
a case, for the spectral peaks in the two-dimensional Fourier
spectra of both patterns, only the peaks having a high intensity
may be selected in advance. In this case, because only the
difference between the selected peaks is calculated, the time
taken for calculation can be shortened.
[0066]
FIG. 15 shows the frequencies and spectral intensities of
moires obtained in this way. FIG. 15 is a view schematically
illustrating the frequencies and spectral intensities of the
moires occurring due to the interference between the pixel array
pattern shown in FIG. 11(A) and the mesh pattern shown in FIG.
11(B). FIG. 15 can be regarded as being an outcome of the
convolution integral of the intensity characteristics of the
two-dimensional Fourier spectra shown in FIGS. 12(A) and 12(B).
In FIG. 15, the frequency of the moire is indicated by the
position on the ordinate and abscissa, and the spectral
intensity of the moire is indicated by the shade of grey
(achromatic color). As shown in FIG. 15, the darker the color,
the lower the spectral intensity, and the lighter the color,
that is, the closer the color is to white, the higher the
spectral intensity.
[0067]
Thereafter, as Procedure 4, the moire recognition property
is determined.
That is, as shown in FIG. 10, in Step S20, among the
41
frequencies of the moires calculated in Step S18 (S14), the
lowest frequency is determined, and the spectral intensity of
moire of the lowest frequency is determined. Herein, only the
frequencies of the moires in a data within 3 cycles/mm are
considered. That is, among the frequencies of the moires
calculated in Step S18 (S14), the frequencies of the moires
within 3 cycles/mm are used and ranked, the lowest frequency of
the moire is determined, and the spectral intensity thereof is
determined.
For determining the moire recognition property and the
like, the frequency and spectral intensity of the moire are
convoluted with a Visual Transfer Function (VTF) based on a
Dooley Shaw function or the like that shows standard visual
response characteristic of a human being. However, being a
function that depends on an observation distance, VTF is not
used in the present invention. In the display device equipped
with a touch panel and the like to which the conductive film of
the present invention is applied, the observation distance is
not fixed at the time of actual observation, and thus VTF is not
used in the present invention.
[0068]
Subsequently, as shown in FIG. 10, in Step S22, the
spectral intensity of the moire of the lowest frequency
determined in Step S20 is compared with -3.6, and whether or not
the spectral intensity of the moire is equal to or greater than
-3.6 is determined.
For a plurality of mesh patterns 62, in examples which will
be described later, by using a plurality of samples having
different types of the dummy electrode wiring pattern 24b
including the plurality of disconnection portions 26 in the
dummy electrode portion 22b, the spectral intensity of the moire
of the lowest frequency was determined, and the mesh pattern 62
and the spectral intensity of the moire of the lowest frequency
were evaluated by 3 researchers. As a result, as shown in Table
1 which will be described later, the sample in which the
42
spectral intensity of the moire of the lowest frequency was
equal to or less than -3.8 expressed in terms of the common
logarithm (equal to or less than 10-3.8 expressed in terms of the
antilogarithm) was evaluated to be “A” by the sensory evaluation
because the moire was not visually recognized; the sample in
which the spectral intensity thereof was greater than -3.8 and
equal to or less than -3.6 expressed in terms of the common
logarithm (greater than 10-3.8 and equal to or less than 10-3.6
expressed in terms of the antilogarithm) was evaluated to be “B”
by the sensory evaluation because the moire was just slightly
recognized but was ignorable; and the sample in which the
spectral intensity thereof was greater than -3.6 expressed in
terms of the common logarithm (greater than 10-3.6 expressed in
terms of the antilogarithm) was evaluated to be “C (unusable)”
by the sensory evaluation because the moire was visually
recognized.
Accordingly, in the present invention, the spectral
intensity of the moire of the lowest frequency is limited to be
equal to or less than -3.6 expressed in terms of the common
logarithm (equal to or less than 10-3.6 expressed in terms of the
antilogarithm).
[0069]
When the spectral intensity of the moire of the lowest
frequency is greater than -3.6 expressed in terms of the common
logarithm (greater than 10-3.6 expressed in terms of the
antilogarithm), the process moves onto Step S24, the
transmittance image data of the mesh pattern 62 is updated to
transmittance image data of a new mesh pattern, and the process
returns to Step S12.
Herein, the new mesh pattern to be updated may be prepared
in advance or newly created. When the mesh pattern is newly
created, the transmittance image data of the mesh pattern,
specifically, one or more among the position, the pitch, and the
width of the plurality of disconnection portions (breaks) 26 of
the dummy electrode wiring pattern 24b may be changed, or the
43
shape or size of the mesh pattern may be changed. Moreover,
randomness may be given to these parameters.
[0070]
Then, Step S12 as a step of obtaining the spatial frequency
characteristics, Step S14 (S18) as a step of calculating the
frequency and spectral intensity of the moire, Step S20 as a
step of calculating the spectral intensity of the moire of the
lowest frequency, Step S22 as a step of comparing the spectral
intensity of the moire of the lowest frequency with -3.6
expressed in terms of the common logarithm (10-3.6 expressed in
terms of the antilogarithm), and Step S24 as a step of updating
the transmittance image data of the mesh pattern are repeated
until the spectral intensity of the moire of the lowest
frequency becomes equal to or less than -3.6 expressed in terms
of the common logarithm (10-3.6 expressed in terms of the
antilogarithm).
[0071]
When the spectral intensity of the moire of the lowest
frequency is equal to or less than -3.6 expressed in terms of
the common logarithm (10-3.6 expressed in terms of the
antilogarithm), the process moves onto Step S26, and the mesh
pattern 62 is determined to be an optimized mesh pattern and set
to be the mesh pattern 24 (30) of the conductive film 10 or 11
of the present invention.
In this way, the method for determining a mesh pattern of a
conductive film of the present invention ends, and as a result,
it is possible to prepare the conductive film of the present
invention having an optimized mesh pattern that inhibits the
occurrence of moire even being superimposed on a BM pattern of a
display unit of a display device and has excellent moire
recognition property.
[Examples]
[0072]
A mesh pattern 70 shown in FIG. 16 was prepared as a
simulation sample of Comparative example 1. The mesh pattern 70
44
of Comparative example 1 was a wiring pattern constituted with
an electrode wiring pattern 74 of an X electrode 72 constituting
an effective electrode region and a dummy electrode wiring
pattern 78 of 4 dummy electrodes 76a, 76b, 76c, and 76d. The
mesh pattern 70 had a plurality of disconnection portions 84
each of which was regularly provided at the center of each of 4
sides composed of thin metal wires 82 that formed a mesh shape
of rhomboids of all of openings 80 formed by the dummy electrode
wiring pattern 78. In the side between the electrode wiring
pattern 74 and the dummy electrode wiring pattern 78, the
disconnection portion 84 was also provided in a central position
of each of the thin metal wires 82 between the patterns. In the
example shown in FIG. 16, for simplifying the drawing, the
disconnection portion 84 is shown only in the dummy electrode
wiring pattern 78 of a single dummy electrode 76c and is not
shown in the dummy electrode wiring pattern 78 of the 3 dummy
electrodes 76a, 76b, and 76d.
As a reference example, a mesh pattern of mesh-like wiring
not including the disconnection portions was prepared as a
simulation sample.
Furthermore, based on Comparative example 1, mesh patterns
of Examples 1 to 6 and Comparative examples 2 to 4 were prepared
as simulation samples by changing the length, the position, the
arrangement, and the number of the disconnection portions 84.
[0073]
In each mesh pattern 70 and the like, the length of one
side of all of the mesh shapes of a rhomboid was set to be 144
m, and internal angles of the rhomboid were set to be 76 and
104. Moreover, as the thin metal wires 82 constituting the
sides of each mesh pattern, metal wires having a line width of 6
m were used.
In the mesh pattern 70 of Comparative example 1, the length
of the disconnection portions (breaks) 82 was set to be 20 m (a
break length or a break interval).
45
In contrast, in each of the mesh patterns of Examples 1 and
2, the length (the break length or the break interval) of the
disconnection portions (breaks) 84 was changed with respect to
the mesh pattern 70 of Comparative example 1. However, the mesh
patterns of Examples 1 and 2 were the same as the mesh pattern
70 of Comparative example 1, except that the length of the
disconnection portions 84 was changed to 5 m (Example 1) and to
10 m (Example 2) from 20 m in Comparative example 1.
[0074]
The mesh patterns of Examples 3 to 5 were obtained by
changing the position of the disconnection portions 84 from the
central position of the sides of the rhombic mesh shape of the
mesh pattern of Comparative example 1 such that the
disconnection portions were randomly arranged.
In Example 3, the position of the disconnection portions 84
in the 4 sides of one of the rhombic mesh shapes of the dummy
electrode wiring pattern 78 of the 4 dummy electrodes 76a, 76b,
76c, and 76d was changed from the central position in
Comparative example 1, such that the disconnection portions were
placed in random positions other than the central position.
Therefore, the mesh pattern of Example 3 was a wiring pattern
repeating this pattern in other rhombic mesh shapes.
In Example 4, the position of the disconnection portions 84
in the 4 sides of all of the rhombic mesh shapes of the dummy
electrode wiring pattern 78 was changed from the central
position in Comparative example 1, such that the disconnection
portions were placed in completely random positions.
In Example 5, not only the position of the disconnection
portions 84 in the 4 sides of all of the rhombic mesh shapes of
the dummy electrode wiring pattern 78 but also the position of
the disconnection portions 84 in each side between the electrode
wiring pattern 74 and the dummy electrode wiring pattern 78 were
changed from the central position of Comparative example 1, such
that the disconnection portions were placed in completely random
positions.
46
In Example 6, the mesh pattern 70 of Comparative example 1
was changed such that all of the disconnection portions 84 were
removed from the dummy electrode wiring pattern 78 of the 4
dummy electrodes 76a, 76b, 76c, and 76d so as to make the dummy
electrodes connected to each other, and the mesh pattern had the
disconnection portion 84 only in each side between the electrode
wiring pattern 74 and the dummy electrode wiring pattern 78.
[0075]
In Comparative examples 2 and 3, the number of the
disconnection portions 84 in the dummy electrode wiring pattern
78 of all of the dummy electrodes 76a, 76b, 76c, and 76d was
reduced compared to Comparative example 1.
In Comparative example 2, in all of the dummy electrode
wiring patterns 78, the number of the disconnection portions 84
in a line direction (a horizontal direction in FIG. 16: an xdirection
on x,y coordinates) was halved such that the
disconnection portions 84 were provided in every other line of
the thin metal wires 82.
In Comparative example 3, in all of the dummy electrode
wiring patterns 78, the number of the disconnection portions 84
in a column direction (a vertical direction in FIG. 16: a ydirection
on x,y coordinates) was halved such that the
disconnection portions 84 were provided in every other line of
the thin metal wires 82.
In Comparative example 4, in all of the dummy electrode
wiring patterns 78, the number of the disconnection portions 84
in a column direction (a vertical direction in FIG. 16: a ydirection
on x,y coordinates) was halved such that the
disconnection portions 84 were provided in every other line of
the thin metal wires 82.
In Comparative example 5, in all of the dummy electrode
wiring patterns 78, the disconnection portions 84 were provided
only in a single line direction (one of the thin metal wires 82
crossing the other in FIG. 16).
[0076]
47
The simulation of the interference between each of the mesh
patterns and the BM pattern 38, which occurs when the simulation
sample of the conductive film having the mesh pattern of each of
Examples 1 to 6, Comparative examples 1 to 4, and the reference
example is superimposed on the simulation sample of the display
unit 31 having the BM pattern 38 shown in FIG. 11, was
performed. In this way, the spectral intensity of the moire of
the lowest frequency represented by the convolution of the
spatial frequency characteristics of each of the mesh patterns
and the BM pattern 38 was determined. Furthermore, the moire
(the result of the simulation of interference between the mesh
pattern and the BM pattern) occurring due to the interference
between the mesh pattern and the BM pattern 38 was presented,
and sensory evaluation was performed by 3 researchers.
The size of pixels constituting the BM pattern 38 of the
display unit 31 was 102 m  102 m because the resolution
thereof was 250 dpi, and the size of sub-pixels was 26 m  78
m.
The results are shown in Table 1.
During the sensory evaluation, by the 3 researchers, the
sample in which the moire was not visually recognized was
evaluated to be “A”, the sample in which the moire was slightly
visually recognized but was ignorable was evaluated to be “B”,
and the sample in which the moire was visually recognized was
evaluated to be “C”.
[0077]
[Table 1]
Table 1. Result
Moire of lowest
frequency
Result of sensory
evaluation
Reference example -4.008 A
Example 1 -3.868 A
Example 2 -3.625 B
48
Example 3 -4.275 A
Example 4 -4.255 A
Example 5 -4.267 A
Example 6 -3.774 B
Comparative example 1 -3.501 C
Comparative example 2 -3.504 C
Comparative example 3 -3.493 C
Comparative example 4 -3.508 C
[0078]
As is evident from the results shown in Table 1, Examples 1
and 3 to 5, in which the spectral intensity of the moire of the
lowest frequency was equal to or less than -3.8 expressed in
terms of the common logarithm (equal to or less than 10-3.8
expressed in terms of the antilogarithm), were evaluated to be
“A” by the sensory evaluation because the moire was not visually
recognized. Examples 2 and 6, in which the spectral intensity of
the moire of the lowest frequency was greater than -3.8 and
equal to or less than -3.6 expressed in terms of the common
logarithm (greater than 10-3.8 and equal to or less than 10-3.6
expressed in terms of the antilogarithm), were evaluated to be
“B” by the sensory evaluation because the moire was slightly
visually recognized but was ignorable. In contrast, Comparative
examples 1 to 4, in which the spectral intensity of the moire of
the lowest frequency was greater than -3.6 expressed in terms of
the common logarithm (greater than 10-3.6 expressed in terms of
the antilogarithm), were evaluated to be “C” by the sensory
evaluation, and the examples were unusable because the moire was
visually recognized.
The above results clearly show the effects of the present
invention.
[0079]
Hitherto, the conductive film of the present invention, the
49
display device equipped with the conductive film of the present
invention, and the method for determining a pattern of a
conductive film of the present invention have been described
based on various embodiments and examples. However, the present
invention is not limited to the embodiments and examples.
Needless to say, the present invention may be improved in
various ways, or the design thereof may be changed, as long as
the improvement and change do not depart from the gist of the
present invention.
DESCRIPTION OF SYMBOLS
[0080]
10, 11, 60: CONDUCTIVE FILM
12: TRANSPARENT SUBSTRATE
14, 82: THIN WIRE MADE OF METAL (THIN METAL WIRE)
16, 16a, 16b: WIRING LAYER
18, 18a, 18b: ADHESIVE LAYER
20, 20a, 20b: PROTECTIVE LAYER
22, 28: MESH-LIKE WIRING
22a, 28a: ELECTRODE PORTION
22b, 28b: DUMMY ELECTRODE PORTION (NON-ELECTRODE PORTION)
23, 29, 80: OPENING
24, 30, 62, 70: MESH PATTERN
24a, 30a, 74: ELECTRODE WIRING PATTERN
24b, 30b, 78: DUMMY ELECTRODE WIRING PATTERN
26, 84: DISCONNECTION PORTION (BREAK)
31: DISPLAY UNIT
32, 32r, 32g, 32b: PIXEL
34: BLACK MATRIX (BM)
38: BM PATTERN
40: DISPLAY DEVICE
44: TOUCH PANEL
72: X ELECTRODE
76a, 76b, 76c, 76d: DUMMY ELECTRODE

We Claim:
[Claim 1]
A conductive film installed on a display unit of a display
device, comprising:
a transparent substrate; and
mesh-like wiring which is formed on at least one surface of
the transparent substrate and has a mesh pattern formed of a
plurality of patterned thin metal wires,
wherein the mesh pattern of the mesh-like wiring is
superimposed on a pixel array pattern of the display unit,
a spectral intensity of moire of a lowest frequency is
equal to or less than -3.6 expressed in terms of common
logarithm, and
the spectral intensity of moire of the lowest frequency is
represented by convolution of spatial frequency characteristics
of the mesh pattern that are obtained at least when the mesh
pattern is observed from a front side and spatial frequency
characteristics of the pixel array pattern of the display unit
that are obtained at least when the pixel array pattern is
observed from a front side.
[Claim 2]
The conductive film according to claim 1,
wherein the mesh-like wiring has an electrode potion, which
includes an electrode wiring pattern formed of the plurality of
thin metal wires in a form of a continuous mesh, and a nonelectrode
portion, which is formed of the plurality of thin
metal wires in a form of a mesh, has a plurality of
disconnection portions, includes a discontinuous non-electrode
wiring pattern, and is insulated from the electrode portion,
the mesh pattern of the mesh-like wiring is constituted
with the electrode wiring pattern of the electrode portion and
the non-electrode wiring pattern of the non-electrode portion
insulated from the electrode wiring pattern, and
the spatial frequency characteristics of the mesh pattern
51
are spatial frequency characteristics of the mesh pattern
including the plurality of disconnection portions that are
obtained at least when the mesh pattern is observed from the
front side.
[Claim 3]
The conductive film according to claim 1 or 2,
wherein a frequency of the moire is given as a difference
between a peak frequency of a spectral peak of the spatial
frequency characteristics of the mesh pattern and a peak
frequency of a spectral peak of the spatial frequency
characteristics of the pixel array pattern, and a spectral
intensity of the moire is given as a product of a peak intensity
of the spectral peak of the mesh pattern and a peak intensity of
the spectral peak of the pixel array pattern.
[Claim 4]
The conductive film according to claim 3,
wherein the peak intensity is a sum of intensities in a
plurality of pixels in a vicinity of the peak position.
[Claim 5]
The conductive film according to any one of claims 1 to 4,
wherein each peak intensity is standardized by using
transmittance period image data of each of the mesh pattern and
the pixel array pattern.
[Claim 6]
A conductive film installed on a display unit of a display
device, comprising:
a transparent substrate; and
mesh-like wiring which is formed on at least one surface of
the transparent substrate and has a mesh pattern formed of a
plurality of patterned thin metal wires on one surface thereof,
wherein the mesh-like wiring has an electrode potion, which
includes an electrode wiring pattern formed of the plurality of
thin metal wires in a form of a continuous mesh, and a nonelectrode
portion, which is formed of the plurality of thin
metal wires in a form of a mesh, has a plurality of
52
disconnection portions, includes a discontinuous non-electrode
wiring pattern, and is insulated from the electrode portion,
the mesh pattern of the mesh-like wiring is constituted
with the electrode wiring pattern of the electrode portion and
the non-electrode wiring pattern of the non-electrode portion
insulated from the electrode wiring pattern, and is superimposed
on a pixel array pattern of the display unit,
when the plurality of disconnection portions of the nonelectrode
wiring pattern of the non-electrode portion is
connected to each other, the mesh pattern of the mesh-like
wiring prevents moire from being visually recognized, and
the non-electrode wiring pattern of the non-electrode
portion is a random wiring pattern in which the plurality of
disconnection portions have been randomly arranged.
[Claim 7]
The conductive film according to any one of claims 1 to 6,
wherein a frequency of the moire is equal to or less than 3
cycles/mm.
[Claim 8]
The conductive film according to any one of claims 1 to 7,
wherein the non-electrode wiring pattern of the nonelectrode
portion is formed of the plurality of thin metal wires
in a form of a mesh within a region excluding the electrode
portion.
[Claim 9]
The conductive film according to any one of claims 1 to 8,
wherein the pixel array pattern is a black matrix pattern.
[Claim 10]
A display device comprising:
a display unit; and
the conductive film according to any one of claims 1 to 9
that is installed on the display unit.
[Claim 11]
A touch panel display device comprising:
the display device according to claim 10; and
53
a transparent substrate which is disposed on an upper side
of the conductive film of the display device and has a touch
surface on the side opposite to the conductive film.
[Claim 12]
A method for determining a mesh pattern of a conductive
film which is installed on a display unit of a display device
and in which mesh-like wiring having a mesh pattern formed of a
plurality of patterned thin metal wires in a form of a
continuous mesh has been formed, the method comprising the steps
of:
obtaining transmittance period image data of the mesh
pattern and transmittance period image data of a pixel wiring
pattern of the display unit on which the mesh pattern is
superimposed;
performing two-dimensional Fourier transform on the
obtained transmittance period image data of the mesh pattern and
on the obtained transmittance period image data of the pixel
array pattern to obtain spatial frequency characteristics of the
mesh pattern and spatial frequency characteristics of the pixel
array pattern, the spatial frequency characteristics of the mesh
pattern and the pixel array pattern being obtained at least when
the mesh pattern and the pixel array pattern are observed from a
front side;
calculating frequencies and spectral intensities of moires
represented by convolution of the spatial frequency
characteristics of the mesh pattern and the spatial frequency
characteristics of the pixel array pattern, from the obtained
spatial frequency characteristics of the mesh pattern and the
pixel array pattern;
determining a lowest frequency among the calculated
frequencies of the moires, and comparing the spectral intensity
of the moire of the lowest frequency with -3.6 expressed in
terms of a common logarithm; and
setting the mesh pattern to be a mesh pattern of the
conductive film when the spectral intensity of the moire of the
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lowest frequency defined by the common logarithm is equal to or
less than -3.6, and when the spectral intensity of the moire of
the lowest frequency is greater than -3.6, updating the
transmittance period image data of the mesh pattern to
transmittance period image data of a new mesh pattern, and
repeating the respective steps of obtaining spatial frequency
characteristics, calculating frequencies and spectral
intensities of moires, and comparing the spectral intensity of
the moire of the lowest frequency with -3.6 until the spectral
intensity of the moire of the lowest frequency becomes equal to
or less than -3.6.
[Claim 13]
The method for determining a mesh pattern of a conductive
film according to claim 12,
wherein the mesh-like wiring has the mesh pattern including
an electrode wiring pattern, which is formed of the plurality of
thin metal wires in the form of a continuous mesh, and a nonelectrode
wiring pattern, which is formed of the plurality of
thin metal wires in the form of a mesh, has a plurality of
disconnection portions, and is discontinuous to and insulated
from the electrode wiring pattern,
the transmittance period image data of the mesh pattern is
transmittance period image data of the mesh pattern including
the non-electrode wiring pattern having the plurality of
disconnection portions, and
the spatial frequency characteristics of the mesh pattern
is spatial frequency characteristics of the mesh pattern
including the plurality of disconnection portions that are
obtained at least when the mesh pattern is observed from a front
side.
[Claim 14]
The method for determining a mesh pattern of a conductive
film according to claim 12 or 13,
wherein based on the obtained spatial frequency
characteristics of the mesh pattern, spectral peaks of which the
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peak intensity is equal to or greater than -4.5 expressed in
terms of a common logarithm are extracted from a plurality of
spectral peaks of two-dimensional Fourier spectra of the
transmittance period image data of the mesh pattern, and peak
frequencies and peak intensities of all of the extracted
spectral peaks are calculated;
based on the obtained spatial frequency characteristics of
the pixel array pattern, spectral peaks of which the peak
intensity is equal to or greater than -4.5 expressed in terms of
a common logarithm are extracted from a plurality of spectral
peaks of two-dimensional Fourier spectra of the transmittance
period image data of the pixel array pattern, and peak
frequencies and peak intensities of all of the extracted
spectral peaks are calculated; and
the frequencies and the spectral intensities of the moires
are calculated from the peak frequencies and the peak
intensities of the mesh pattern calculated as above and from the
peak frequencies and the peak intensities of the pixel array
pattern calculated as above.
[Claim 15]
The method for determining a mesh pattern of a conductive
film according to claim 14,
wherein as the frequency of the moire, a difference between
the peak frequency of the mesh pattern and the peak frequency of
the pixel array pattern is calculated, and
as the spectral intensity of the moire, a product of two
pairs of vector intensities including the peak intensity of the
mesh pattern and the peak intensity of the pixel array pattern
is calculated.
[Claim 16]
A method for determining a mesh pattern of a conductive
film according to any one of claims 12 to 15,
wherein the frequency of the moire is equal to or less than
3 cycles/mm.
[Claim 17]
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The method for determining a mesh pattern of a conductive
film according to any one of claims 12 to 16,
wherein the non-electrode wiring pattern is formed of the
plurality of thin metal wires in the form of a mesh, within a
region in which the electrode wiring pattern has not been
formed.