U.S. patent application number 14/499966 was filed with the patent office on 2015-01-15 for conductive film, display device equipped with same, and method for determining pattern of conductive film.
This patent application is currently assigned to FUJIFILM CORPORATION. The applicant listed for this patent is FUJIFILM Corporation. Invention is credited to Kazuchika IWAMI, Ryohei SATO.
Application Number | 20150015979 14/499966 |
Document ID | / |
Family ID | 49259299 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150015979 |
Kind Code |
A1 |
IWAMI; Kazuchika ; et
al. |
January 15, 2015 |
CONDUCTIVE FILM, DISPLAY DEVICE EQUIPPED WITH SAME, AND METHOD FOR
DETERMINING PATTERN OF CONDUCTIVE FILM
Abstract
The conductive film has a wiring pattern which, with respect to
the frequencies and intensities of moire obtained by applying a
human visual response characteristic to the frequency information
and intensity information of moire calculated from peak frequencies
and peak intensities of the two-dimensional Fourier spectrums of
the transmittance image data of the wiring pattern and the
transmittance image data of a pixel array pattern, causes the sum
of intensities of moire each corresponding to frequencies of moire
falling within a frequency range predetermined depending on the
visual response characteristic to be less than or equal to a
predetermined value. The conductive film allows suppression of
moire and significant improvement in visibility.
Inventors: |
IWAMI; Kazuchika;
(Ashigara-kami-gun, JP) ; SATO; Ryohei;
(Ashigara-kami-gun, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
FUJIFILM CORPORATION
Tokyo
JP
|
Family ID: |
49259299 |
Appl. No.: |
14/499966 |
Filed: |
September 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2013/055036 |
Feb 27, 2013 |
|
|
|
14499966 |
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Current U.S.
Class: |
359/893 ;
716/52 |
Current CPC
Class: |
G06F 3/0443 20190501;
G06F 2203/04112 20130101; G06F 3/0445 20190501; G02B 2207/121
20130101; G06F 2111/04 20200101; G02B 27/0012 20130101; G06F 30/398
20200101; H05K 9/0096 20130101; G06F 2203/04107 20130101; G02B
27/00 20130101; G02B 27/60 20130101 |
Class at
Publication: |
359/893 ;
716/52 |
International
Class: |
G02B 27/60 20060101
G02B027/60; G06F 17/50 20060101 G06F017/50; G02B 27/00 20060101
G02B027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2012 |
JP |
2012-082711 |
Claims
1. A conductive film adapted to be installed on a display unit of a
display device, comprising: a transparent substrate; and a
conductive portion including a plurality of thin metal wires that
is formed on at least one surface of the transparent substrate,
wherein the conductive portion has a wiring pattern which is formed
by the plurality of thin metal wires in a meshed manner and
provided with a plurality of openings arrayed, wherein the wiring
pattern is superimposed on a pixel array pattern of the display
unit, and wherein the wiring pattern is a wiring pattern which,
with respect to frequencies of moire and intensities of moire
obtained by applying a visual response characteristic of human
beings to frequency information of moire and intensity information
of moire calculated from peak frequencies and peak intensities of
plural spectrum peaks in a two-dimensional Fourier spectrum of
transmittance image data of the wiring pattern and peak frequencies
and peak intensities of plural spectrum peaks in a two-dimensional
Fourier spectrum of transmittance image data of the pixel array
pattern, causes a sum of intensities of moire each corresponding to
frequencies of moire falling within a predetermined frequency range
determined depending on the visual response characteristic to be
less than or equal to a predetermined value.
2. The conductive film according to claim 1, wherein the
predetermined frequency range of the frequencies of moire is up to
3 cycles/mm, and wherein the wiring pattern undergoes ranking for
optimization if it involves frequencies of moire less than or equal
to 3 cycles/mm, and the wiring pattern undergoing the ranking for
optimization causes the sum of intensities of moire to be less than
or equal to 0 in terms of common logarithm on condition that the
wiring pattern does not undergo the ranking for optimization if it
involves intensities of moire greater than or equal to -5 in terms
of common logarithm at frequencies of moire less than or equal to
1.8 cycles/mm and if it involves intensities of moire greater than
or equal to -3.7 in terms of common logarithm at frequencies of
moire greater than 1.8 cycles/mm but not greater than 3
cycles/mm.
3. The conductive film according to claim 1, wherein the frequency
information of moire is given as differences between the peak
frequencies of the wiring pattern and the peak frequencies of the
pixel array pattern and the intensity information of moire is given
as products of the peak intensities of the wiring pattern and the
peak intensities of the pixel array pattern.
4. The conductive film according to claim 1, wherein the
frequencies of moire and the intensities of moire are obtained by
performing convolution with a visual transfer function as the
visual response characteristic on the frequency information of
moire and the intensity information of moire.
5. The conductive film according to claim 4, wherein the visual
transfer function is a function in which attenuation in sensitivity
to low-frequency components is removed from a Dooley-Shaw function
as a basis.
6. The conductive film according to claim 1, wherein the peak
intensities are each an average of intensities in a plurality of
pixels around a peak position.
7. The conductive film according to claim 1, wherein the peak
intensities are normalized with the transmittance image data of the
wiring pattern and the pixel array pattern.
8. The conductive film according to claim 1, wherein the pixel
array pattern is a black matrix pattern.
9. A display device, comprising: a display unit; and the conductive
film according to claim 1 that is installed on the display
unit.
10. A method for determining a wiring pattern of a conductive film,
with the conductive film being adapted to be installed on a display
unit of a display device and to have a wiring pattern which is
formed by a plurality of thin metal wires in a meshed manner and
provided with a plurality of openings arrayed, comprising the steps
of: acquiring transmittance image data of a wiring pattern and
transmittance image data of a pixel array pattern of the display
unit, on which pattern the wiring pattern is superimposed;
calculating peak frequencies and peak intensities of plural
spectrum peaks in a two-dimensional Fourier spectrum of the
transmittance image data of the wiring pattern and peak frequencies
and peak intensities of plural spectrum peaks in a two-dimensional
Fourier spectrum of the transmittance image data of the pixel array
pattern by performing a two-dimensional Fourier transform on the
transmittance image data of the wiring pattern and the
transmittance image data of the pixel array pattern; calculating
frequency information of moire and intensity information of moire
from the peak frequencies and the peak intensities of the wiring
pattern and the pixel array pattern thus calculated, respectively;
calculating frequencies of moire and intensities of moire by
applying a visual response characteristic of human beings to the
frequency information of moire and the intensity information of
moire thus obtained; making comparison with respect to the
frequencies of moire and the intensities of moire thus obtained
such that a sum of intensities of moire each corresponding to
frequencies of moire falling within a predetermined frequency range
determined depending on the visual response characteristic is
compared with a predetermined value; and setting the wiring pattern
as the wiring pattern of the conductive film if the sum of
intensities of moire is less than or equal to the predetermined
value and, if the sum of intensities of moire is greater than the
predetermined value, changing the transmittance image data of the
wiring pattern to transmittance image data of a new wiring pattern
and repeating the steps of calculating the peak frequencies and the
peak intensities, calculating the frequency information of moire
and the intensity information of moire, calculating the frequencies
of moire and the intensities of moire, and making comparison
between the sum of intensities of moire and the predetermined value
until the sum of intensities of moire is less than or equal to the
predetermined value.
11. The method for determining a wiring pattern of a conductive
film according to claim 10, wherein the predetermined frequency
range of the frequencies of moire is up to 3 cycles/mm, and wherein
the wiring pattern undergoes ranking for optimization if it
involves frequencies of moire less than or equal to 3 cycles/mm,
and the wiring pattern undergoing the ranking for optimization
causes the sum of intensities of moire to be less than or equal to
0 in terms of common logarithm on condition that the wiring pattern
does not undergo the ranking for optimization if it involves
intensities of moire greater than or equal to -5 in terms of common
logarithm at frequencies of moire less than or equal to 1.8
cycles/mm and if it involves intensities of moire greater than or
equal to -3.7 in terms of common logarithm at frequencies of moire
greater than 1.8 cycles/mm but not greater than 3 cycles/mm.
12. The method for determining a wiring pattern of a conductive
film according to claim 10, wherein the frequency information of
moire is obtained as differences between the peak frequencies of
the wiring pattern and the peak frequencies of the pixel array
pattern, and wherein the intensity information of moire is obtained
as products of two sets of vector intensities, with one set
comprising the peak intensities of the wiring pattern and the other
comprising the peak intensities of the pixel array pattern.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International
Application No. PCT/JP2013/055036 filed on Feb. 27, 2013, which
claims priority under 35 U.S.C. .sctn.119(a) to Japanese Patent
Application No. 2012-082711 filed on Mar. 30, 2012. Each of the
above applications is hereby expressly incorporated by reference,
in its entirety, into the present application.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a conductive film, a
display device equipped with the conductive film, and a method for
determining a pattern of the conductive film.
[0003] Examples of a conductive film installed on a display unit of
a display device (hereinafter also referred to as "display")
include a conductive film for electromagnetic shields and a
conductive film for touch panels (for example, see JP 2009-117683 A
and JP 2011-216379 A).
[0004] JP 2009-117683 A, a published patent application filed by
the same applicant as the present application, discloses that a
second pattern, which is generated from second pattern data in
which the relative distance between spectrum peaks of
two-dimensional Fourier spectrums (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 an
electromagnetic shield pattern is greater than a predetermined
spatial frequency, for example, 8 cm.sup.-1, is automatically
selected.
[0005] JP 2009-117683 A 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 in the second pattern data to generate new second pattern
data is repeated until the relative distance is greater than the
predetermined spatial frequency.
[0006] In this way, in JP 2009-117683 A, it is possible to
automatically select an electromagnetic shield pattern that can
suppress the occurrence of moire and that can avoid an increase in
surface resistivity or degradation in transparency.
[0007] JP 2011-216379 A, another published patent application filed
by the same applicant as the present application, discloses a
transparent conductive film having a mesh pattern comprising a
plurality of polygonal meshes, in which the mesh pattern is formed
such that, in relation to a centroid spectrum of respective meshes,
an average intensity on the side of a spatial frequency band higher
than a predetermined spatial frequency, for example, a spatial
frequency at which a human visual response characteristic
corresponds to 5% of the maximum response, is greater than an
average intensity on the side of a spatial frequency band lower
than the predetermined spatial frequency.
[0008] It is stated in JP 2011-216379 A that a transparent
conductive film is provided which is capable of lowering the
sensation of granular noise caused by the pattern and significantly
enhancing the visibility of objects to be observed, and has a
stable power capability even after being cut.
SUMMARY OF THE INVENTION
[0009] In the technology as disclosed in JP 2009-117683 A, during
the generation of a wiring pattern of a conductive film, a moire
frequency is only controlled on the basis of frequency information
of a BM (black matrix) pattern of a display/the wiring pattern so
as to provide a wiring pattern excellent in visibility, that is to
say, the determination of whether moire is visually recognized or
not only depends on the frequency. Since human perception of moire
is influenced by intensity as well as frequency, moire may be
visually recognized depending on the intensity even at a frequency
at which moire is not determined to be visually recognized in JP
2009-117683 A, and thus there is a problem in that the wiring
pattern of the conductive film is not adequately improved in
visibility of moire. Particularly when the technology of JP
2009-117683 A is applied to a conductive film for touch panels,
since the conductive film is pressed with a finger or the like, a
delicate distortion occurs between the BM/wiring patterns, and
accordingly there is a problem in that visual recognition of moire
due to intensity is promoted, leading to an inadequate improvement
in moire visibility.
[0010] In JP 2011-216379 A, in relation to a centroid spectrum of
respective meshes of the mesh pattern of the transparent conductive
film, an average intensity in a mid to high spatial frequency band,
which is higher than the predetermined spatial frequency and in
which human visual response characteristic rapidly decreases, is
made greater than an average intensity in a low spatial frequency
band, in which human visual response characteristic is high, so as
to reduce the sensation of noise visually perceived by human
beings. The disclosed invention merely aims at reducing the
sensation of noise of the mesh pattern in itself of the transparent
conductive film and is not drawn to the improvement in moire
visibility by suppressing moire occurring between the BM pattern of
the display and the mesh pattern of the transparent conductive
film.
[0011] The present invention has been made in order to solve the
above-described problems with the prior art, and an object of the
present invention is to provide a conductive film capable of
suppressing the occurrence of moire to greatly improve visibility,
a display device equipped with such a conductive film, and a method
for determining a pattern of a conductive film.
[0012] In particular, the present invention aims at providing a
conductive film which is capable of suppressing the occurrence of
moire considerably deteriorating the image quality when a
transparent conductive film with wiring is used as an electrode of
a touch panel and a display unit of a display device is viewed
through the conductive film superimposed on a black matrix of the
display unit, so as to greatly improve visibility of the display on
the touch panel, a display device equipped with such a conductive
film, and a method for determining a pattern of a conductive
film.
[0013] In order to achieve the objects as above, the conductive
film according to a first aspect of the present invention is a
conductive film adapted to be installed on a display unit of a
display device, comprising: a transparent substrate; and a
conductive portion including a plurality of thin metal wires that
is formed on at least one surface of the transparent substrate,
wherein the conductive portion has a wiring pattern which is formed
by the plurality of thin metal wires in a meshed manner and
provided with a plurality of openings arrayed, wherein the wiring
pattern is superimposed on a pixel array pattern of the display
unit, and wherein the wiring pattern is a wiring pattern which,
with respect to frequencies of moire and intensities of moire
obtained by applying a visual response characteristic of human
beings to frequency information of moire and intensity information
of moire calculated from peak frequencies and peak intensities of
plural spectrum peaks in a two-dimensional Fourier spectrum of
transmittance image data of the wiring pattern and peak frequencies
and peak intensities of plural spectrum peaks in a two-dimensional
Fourier spectrum of transmittance image data of the pixel array
pattern, causes a sum of intensities of moire each corresponding to
frequencies of moire falling within a predetermined frequency range
determined depending on the visual response characteristic to be
less than or equal to a predetermined value.
[0014] In order to achieve the objects as above, the display device
according to a second aspect of the present invention is a display
device comprising: a display unit; and the conductive film
according to the first aspect that is installed on the display
unit.
[0015] In order to achieve the objects as above, the method for
determining a wiring pattern of a conductive film according to a
third aspect of the present invention is a method for determining a
wiring pattern of a conductive film, with the conductive film being
adapted to be installed on a display unit of a display device and
to have a wiring pattern which is formed by a plurality of thin
metal wires in a meshed manner and provided with a plurality of
openings arrayed, comprising the steps of: acquiring transmittance
image data of a wiring pattern and transmittance image data of a
pixel array pattern of the display unit, on which pattern the
wiring pattern is superimposed; calculating peak frequencies and
peak intensities of plural spectrum peaks in a two-dimensional
Fourier spectrum of the transmittance image data of the wiring
pattern and peak frequencies and peak intensities of plural
spectrum peaks in a two-dimensional Fourier spectrum of the
transmittance image data of the pixel array pattern by performing a
two-dimensional Fourier transform on the transmittance image data
of the wiring pattern and the transmittance image data of the pixel
array pattern; calculating frequency information of moire and
intensity information of moire from the peak frequencies and the
peak intensities of the wiring pattern and the pixel array pattern
thus calculated, respectively; calculating frequencies of moire and
intensities of moire by applying a visual response characteristic
of human beings to the frequency information of moire and the
intensity information of moire thus obtained; making comparison
with respect to the frequencies of moire and the intensities of
moire thus obtained such that a sum of intensities of moire each
corresponding to frequencies of moire falling within a
predetermined frequency range determined depending on the visual
response characteristic is compared with a predetermined value; and
setting the wiring pattern as the wiring pattern of the conductive
film if the sum of intensities of moire is less than or equal to
the predetermined value and, if the sum of intensities of moire is
greater than the predetermined value, changing the transmittance
image data of the wiring pattern to transmittance image data of a
new wiring pattern and repeating the steps of calculating the peak
frequencies and the peak intensities, calculating the frequency
information of moire and the intensity information of moire,
calculating the frequencies of moire and the intensities of moire,
and making comparison between the sum of intensities of moire and
the predetermined value until the sum of intensities of moire is
less than or equal to the predetermined value.
[0016] In each of the first, second and third aspects, it is
preferable that the predetermined frequency range of the
frequencies of moire is up to 3 cycles/mm, and that the wiring
pattern undergoes ranking for optimization if it involves
frequencies of moire less than or equal to 3 cycles/mm, and the
wiring pattern undergoing the ranking for optimization causes the
sum of intensities of moire to be less than or equal to 0 in terms
of common logarithm on condition that the wiring pattern does not
undergo the ranking for optimization if it involves intensities of
moire greater than or equal to -5 in terms of common logarithm at
frequencies of moire less than or equal to 1.8 cycles/mm and if it
involves intensities of moire greater than or equal to -3.7 in
terms of common logarithm at frequencies of moire greater than 1.8
cycles/mm but not greater than 3 cycles/mm.
[0017] Preferably, the frequency information of moire is given as
differences between the peak frequencies of the wiring pattern and
the peak frequencies of the pixel array pattern and the intensity
information of moire is given as products of the peak intensities
of the wiring pattern and the peak intensities of the pixel array
pattern.
[0018] The frequencies of moire and the intensities of moire are
preferably obtained by performing convolution with a visual
transfer function as the visual response characteristic on the
frequency information of moire and the intensity information of
moire. The visual transfer function is preferably a function in
which attenuation in sensitivity to low-frequency components is
removed from a Dooley-Shaw function as a basis.
[0019] It is preferable that the peak intensities are each an
average of intensities in a plurality of pixels around the peak
position, and are normalized with the transmittance image data of
the wiring pattern and the pixel array pattern.
[0020] The pixel array pattern is preferably the black matrix
pattern.
[0021] The frequency information of moire is preferably obtained as
differences between the peak frequencies of the wiring pattern and
the peak frequencies of the pixel array pattern, and the intensity
information of moire is preferably obtained as products of two sets
of vector intensities, with one set comprising the peak intensities
of the wiring pattern and the other comprising the peak intensities
of the pixel array pattern.
[0022] As described above, according to the present invention, it
is possible to suppress the occurrence of moire to greatly improve
visibility.
[0023] That is, in the present invention, since the
frequency/intensities of moire is calculated from the peak
frequencies/intensities obtained by frequency analysis of the pixel
array pattern of the display device and the wiring pattern of the
conductive film and the calculated intensity and frequencies of
moire are numerically limited so as to obtain excellent visibility,
it is possible to prevent the deterioration of image quality due to
the occurrence of moire and thus to achieve excellent
visibility.
[0024] Particularly, according to the present invention, it is
possible to suppress moire considerably deteriorating the image
quality when a conductive film is used as an electrode of a touch
panel and a display unit of a display device is viewed through the
conductive film superimposed on a black matrix of the display unit,
so as to greatly improve visibility of the display on the touch
panel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a plan view schematically illustrating an example
of a conductive film according to a first embodiment of the present
invention.
[0026] FIG. 2 is a partial cross-sectional view schematically
illustrating the conductive film illustrated in FIG. 1.
[0027] FIG. 3 is a partial cross-sectional view schematically
illustrating an example of a conductive film according to a second
embodiment of the present invention.
[0028] FIG. 4 is a diagram schematically illustrating an example of
a pixel array pattern in a part of a display unit to which the
conductive film according to the present invention is applied.
[0029] FIG. 5 is a cross-sectional view schematically illustrating
an example of a display device in which the conductive film
illustrated in FIG. 3 is incorporated.
[0030] FIG. 6 is a flowchart illustrating a part of an example of a
method for determining a wiring pattern of a conductive film
according to the present invention.
[0031] FIG. 7A is a diagram schematically illustrating an example
of a pixel array pattern of the display unit to which the
conductive film according to the present invention is applied, FIG.
7B is a diagram schematically illustrating an example of a wiring
pattern of the conductive film superimposed on the pixel array
pattern illustrated in FIG. 7A, and FIG. 7C is a partially enlarged
view of the pixel array pattern illustrated in FIG. 7A.
[0032] FIG. 8 is a diagram schematically illustrating an example of
flipping processing that is performed in preparing transmission
image data in the method for determining a wiring pattern
illustrated in FIG. 6.
[0033] FIGS. 9A and 9B are diagrams respectively illustrating
intensity characteristics of two-dimensional Fourier spectrums of
transmittance image data of the pixel array pattern illustrated in
FIG. 7A and the wiring pattern illustrated in FIG. 7B.
[0034] FIG. 10 is a graph illustrating frequency peak positions of
the pixel array pattern of the display unit illustrated in FIG.
7A.
[0035] FIGS. 11A and 11B are graphs illustrating an example of the
intensity characteristic of a two-dimensional Fourier spectrum with
a curve and bars, respectively.
[0036] FIG. 12 is a diagram schematically illustrating frequency
information and intensity information of moire generated by
interference of the pixel array pattern illustrated in FIG. 7A and
the wiring pattern illustrated in FIG. 7B.
[0037] FIG. 13 is a graph illustrating an example of a standard
visual response characteristic of human beings.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Hereinafter, a conductive film and a method for determining
a pattern of a conductive film according to the present invention
will be described in detail with reference to appropriate
embodiments illustrated in the accompanying drawings.
[0039] In the following description, a conductive film for a touch
panel will be explained as a representative example of the
conductive film according to the present invention, although the
present invention is not limited to this example. The conductive
film of the invention may be of any type 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 (OLED), or an
inorganic EL display. It is needless to say that the conductive
film according to the present invention may be, for example, a
conductive film for electromagnetic shields.
[0040] FIGS. 1 and 2 are respectively a plan view schematically
illustrating an example of a conductive film according to a first
embodiment of the present invention and a schematic partial
cross-sectional view thereof.
[0041] A conductive film 10 according to this embodiment
illustrated in the drawings is to be installed on a display unit of
a display device and is a conductive film having a wiring pattern
that is excellent in suppression of occurrence of moire with
respect to a black matrix (BM) of the display unit, particularly, a
wiring pattern that is optimized in terms of visibility of moire
with respect to the BM pattern when it is superimposed on the BM
pattern. The conductive film 10 includes a transparent substrate
12, a conductive portion 16 that is formed on one surface of the
transparent substrate 12 (surface on the upper side in FIG. 2) and
that is composed of plural thin wires made of metal (hereinafter
referred to as "thin metal wires") 14, and a protective layer 20
bonded to the substantially entire surface of the conductive
portion 16 via an adhesive layer 18 so as to cover the thin metal
wires 14.
[0042] The transparent substrate 12 is formed of a material having
an insulating property and having a high light-permeability, and
examples thereof include a resin, glass, and silicon. Examples of
the resin include polyethylene terephthalate (PET), polymethyl
methacrylate (PMMA), polypropylene (PP), and polystyrene (PS).
[0043] The conductive portion 16 has a wiring pattern 24 of a
meshed shape which is formed by the thin metal wires 14 with
openings 22 between neighboring thin metal wires 14. The thin metal
wires 14 are not particularly limited as long as they are made of
metal having high conductivity, with an example being those made of
gold (Au), silver (Ag) or copper (Cu). While it is more preferable
indeed in terms of visibility if the thin metal wires 14 have a
smaller line width, the line width has only to be 30 .mu.m or
smaller, for instance. For application to a touch panel, the line
width of the thin metal wires 14 preferably ranges from 0.1 .mu.m
to 15 .mu.m, more preferably from 1 .mu.m to 9 .mu.m, and still
more preferably from 2 .mu.m to 7 .mu.m.
[0044] Specifically, the conductive portion 16 has the wiring
pattern 24 in which the thin metal wires 14 are arranged in a
meshed manner. In the illustrated example, the mesh shape of the
opening 22 is a rhomboid shape, but the present invention is not
limited to this example. Any polygonal shape having at least three
sides may be employed as long as it can constitute the wiring
pattern 24 having moire visibility optimized for a predetermined BM
pattern to be described later, the mesh shapes thereof may be equal
to or different from each other, and examples thereof include equal
or different polygons such as triangles such as a regular triangle
and an equilateral triangle, quadrangles (rectangles) such as a
square and a rectangle, pentagons, and hexagons. That is, as long
as it is a wiring pattern having moire visibility optimized for a
predetermined BM pattern, a wiring pattern constituted by regular
arrangement of openings 22 or a wiring pattern randomized by
arrangement of openings 22 having different shapes may be
employed.
[0045] As a material of the adhesive layer 18, a wet lamination
adhesive, a dry lamination adhesive, a hot melt adhesive or the
like can be mentioned.
[0046] Similarly to the transparent substrate 12, the protective
layer 20 is formed of a material having a high light-permeability,
such as a resin, glass, and silicon. The refractive index n1 of the
protective layer 20 is preferably of a value equal to or close to
that of the refractive index n0 of the transparent substrate 12. In
that case, the relative refractive index nr1 of the transparent
substrate 12 with respect to the protective layer 20 is
approximately 1.
[0047] In this specification, the refractive index refers to a
refractive index for the light at a wavelength of 589.3 nm (sodium
D ray). 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. Here, it is preferable that the
relative refractive index nr1 be in a range of 0.86 to 1.15, and a
range of 0.91 to 1.08 is more preferable.
[0048] By limiting the range of the relative refractive index nr1
as above to control light transmittance between two members, the
transparent substrate 12 and the protective layer 20, improvement
in moire visibility is further promoted.
[0049] The conductive film 10 according to the first embodiment
described above has the conductive portion 16 on only one surface
of the transparent substrate 12, but the present invention is not
limited to this configuration, and the conductive film 10 may have
the conductive portion on both surfaces of the transparent
substrate 12.
[0050] FIG. 3 is a partial cross-sectional view schematically
illustrating an example of a conductive film according to a second
embodiment of the present invention. The plan view of the
conductive film according to the second embodiment illustrated in
FIG. 3 is the same as the plan view of the conductive film
according to the first embodiment illustrated in FIG. 1 and
accordingly, will be omitted.
[0051] As illustrated in the drawing, a conductive film 11
according to the second embodiment includes a first conductive
portion 16a and a dummy electrode portion 26 formed on one surface
(on the upper side in FIG. 3) of a transparent substrate 12, a
second conductive portion 16b formed on the other surface (on the
lower side in FIG. 3) of the transparent substrate 12, a first
protective layer 20a bonded to the substantially entire surface of
the first conductive portion 16a and the dummy electrode portion 26
through a first adhesive layer 18a, and a second protective layer
20b boned to the substantially entire surface of the second
conductive portion 16b through a second adhesive layer 18b.
[0052] In the conductive film 11, the first conductive portion 16a
and the dummy electrode portion 26 are each composed of plural thin
metal wires 14 and formed on one surface (on the upper side in FIG.
3) of the transparent substrate 12, and the second conductive
portion 16b is composed of plural thin metal wires 14 and formed on
the other surface (on the lower side in FIG. 3) of the transparent
substrate 12. Here, the dummy electrode portion 26 is formed on one
surface (on the upper side in FIG. 3) of the transparent substrate
12 similarly to the first conductive portion 16a, and has the thin
metal wires 14 similarly arranged at positions corresponding to the
thin metal wires 14 of the second conductive portion 16b formed on
the other surface (on the lower side in FIG. 3), as illustrated in
the drawing.
[0053] The dummy electrode portion 26 is separated from the first
conductive portion 16a by a predetermined distance and is in the
state of being electrically insulated from the first conductive
portion 16a.
[0054] In the conductive film 11 according to this embodiment,
since the dummy electrode portion 26 composed of plural thin metal
wires 14 corresponding to the plural thin metal wires 14 of the
second conductive portion 16b formed on the other surface (on the
lower side in FIG. 3) of the transparent substrate 12 is formed on
one surface (on the upper side in FIG. 3) of the transparent
substrate 12, scattering due to the thin metal wires on the one
surface (on the upper side in FIG. 3) of the transparent substrate
12 can be controlled, and it is thus possible to improve visibility
of electrode.
[0055] Here, the first conductive portion 16a and the dummy
electrode portion 26 have a wiring pattern 24 of a meshed shape
which is formed by the thin metal wires 14 and openings 22. The
second conductive portion 16b has a wiring pattern 24 of a meshed
shape which is formed by the thin metal wires 14 and openings 22,
similarly to the first conductive portion 16a. As described above,
the transparent substrate 12 is formed of an insulating material
and the second conductive portion 16b is in the state of being
electrically insulated from the first conductive portion 16a and
the dummy electrode portion 26.
[0056] In addition, the first and second conductive portions 16a
and 16b and the dummy electrode portion 26 can be similarly formed
of the same material as the conductive portion 16 of the conductive
film 10 illustrated in FIG. 2.
[0057] The first protective layer 20a is bonded to the
substantially entire surface of the first conductive portion 16a
and the dummy electrode portion 26 with the first adhesive layer
18a so as to cover the thin metal wires 14 of the first conductive
portion 16a and the dummy electrode portion 26.
[0058] The second protective layer 20b is bonded to the
substantially entire surface of the second conductive portion 16b
with the second adhesive layer 18b so as to cover the thin metal
wires 14 of the second conductive portion 16b.
[0059] Here, the first adhesive layer 18a and the second adhesive
layer 18b can be similarly formed of the same material as the
adhesive layer 18 of the conductive film 10 illustrated in FIG. 2,
and the material of the first adhesive layer 18a may be the same as
or different from the material of the second adhesive layer
18b.
[0060] The first protective layer 20a and the second protective
layer 20b can be similarly formed of the same material as the
protective layer 20 of the conductive film 10 illustrated in FIG.
2, and the material of the first protective layer 20a may be the
same as or different from the material of the second protective
layer 20b.
[0061] The refractive index n2 of the first protective layer 20a
and the refractive index n3 of the second protective layer 20b are
each of a value equal or close to that of 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
that case, 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 each approximately
1. Here, 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 second
protective layer 20b is defined as nr3=n3/n0.
[0062] Here, similarly to the relative refractive index nr1, it is
preferable that the relative refractive index nr2 and the relative
refractive index nr3 be in a range of 0.86 to 1.15, and a range of
0.91 to 1.08 is more preferable.
[0063] By limiting the range of the relative refractive index nr2
and the relative refractive index nr3 as above, improvement in
moire visibility is further promoted, as is the case with the
limitation of the range of the relative refractive index nr1.
[0064] The conductive film 10 according to the first embodiment and
the conductive film 11 according to the second embodiment of the
present invention are applied to, for example, a touch panel of a
display unit 30 (displaying section), of which a part is
schematically illustrated in FIG. 4, and as such each have the
wiring pattern as optimized in terms of visibility of moire with
respect to the pixel array pattern, namely, black matrix
(hereinafter also referred to as "BM") pattern of the display unit
30. In the present invention, the wiring pattern as optimized in
terms of visibility of moire with respect to the BM (pixel array)
pattern refers to a wiring pattern or a group of two or more wiring
patterns making moire with respect to a predetermined BM pattern
not perceived by human visual sensation. In the present invention,
a group of two or more wiring patterns optimized may be ranked,
from a wiring pattern making moire most difficult to perceive to a
wiring pattern making moire somewhat difficult to perceive, so as
to determine one wiring pattern which makes moire most difficult to
perceive.
[0065] The optimization of moire visibility of a wiring pattern
with respect to a predetermined BM pattern will be described
later.
[0066] The conductive film according to the present invention
basically has the above-mentioned configuration.
[0067] FIG. 4 is a diagram schematically illustrating an example of
a pixel array pattern in a part of the display unit to which the
conductive film according to the present invention is applied.
[0068] As partially illustrated in FIG. 4, the display unit 30 has
plural pixels 32 arrayed therein in a matrix shape to form a
predetermined pixel array pattern. Each 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 a
horizontal direction. Each sub-pixel has a rectangular shape which
is long in a 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 each pixel 32 is not equal to 1 but
is so set as to satisfy the inequality: [the length in the
horizontal direction (lateral length)]>[the length in the
vertical direction (longitudinal length)].
[0069] Since a pixel array pattern formed by the sub-pixels 32r,
32g, and 32b of the plural pixels 32 is defined by a BM pattern 38
of the BM 34 surrounding the respective sub-pixels 32r, 32g, and
32b as can be apparently seen from FIG. 4, and the moire occurring
when the display unit 30 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 30 and the
wiring pattern 24 of the conductive film 10 or 11, the BM pattern
38 is herein considered to be identical to the pixel array pattern,
although it, strictly speaking, is identical to a reversed pixel
array pattern.
[0070] When the conductive film 10 or 11, for example, is disposed
on the display panel of the display unit 30 having the BM pattern
38 formed by the BM 34, the wiring pattern 24 of the conductive
film 11 has been optimized in terms of visibility of moire with
respect to the BM (pixel array) pattern 38, so that 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, occurrence of moire is
suppressed.
[0071] The display unit 30 illustrated in FIG. 4 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.
[0072] Next, a display device in which the conductive film
according to the present invention is incorporated will be
described below with reference to FIG. 5. In FIG. 5, a projected
capacitive type touch panel in which the conductive film 11
according to the second embodiment of the present invention is
incorporated will be described as a representative example of a
display device 40, but it is needless to say that the present
invention is not limited to this example.
[0073] As shown in FIG. 5, the display device 40 includes the
display unit 30 (refer to FIG. 4) that can display a color image
and/or a monochrome image, a touch panel 44 that detects a contact
position on an input surface 42 (located on the side as directed by
arrow Z1), and a housing 46 in which the display unit 30 and the
touch panel 44 are housed. The user can access the touch panel 44
through a large opening provided in one face (on the side as
directed by arrow Z1) of the housing 46.
[0074] The touch panel 44 includes not only the conductive film 11
(refer to FIG. 3) described above but also a cover member 48
stacked on one face (on the side as directed by arrow Z1) 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.
[0075] The conductive film 11 is bonded to one face (on the side
directed by arrow Z1) of the display unit 30 through an adhesive
layer 56. The conductive film 11 is disposed on the display screen
such that the other, main face side (second conductive portion 16b
side) is opposite to the display unit 30.
[0076] The cover member 48 functions as the input surface 42 by
covering one face of the conductive film 11. In addition, by
preventing direct contact with a contact body 58 (for example, a
finger or a stylus pen), it suppresses the occurrence of a scratch,
adhesion of dust, and the like, and thus stabilizes the
conductivity of the conductive film 11.
[0077] The material of the cover member 48 may be glass or a resin
film. One face (on the side as directed by arrow Z2) of the cover
member 48 may be coated with silicon oxide or the like and adhered
to one face (on the side as directed by arrow Z1) 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 formed into a
laminate.
[0078] The flexible substrate 52 is an electronic substrate having
flexibility. In the example shown in this diagram, the flexible
substrate 52 is fixed to an inner wall of the housing 46, while the
position of the substrate may be varied. 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 approach position) when
the contact body 58 that is a conductor is brought into contact
with (or comes closer to) the input surface 42.
[0079] The display device to which the conductive film according to
the present invention is applied basically has the above-mentioned
configuration.
[0080] Next, processes of evaluating a wiring pattern of the
conductive film on visibility of moire with respect to a
predetermined BM pattern of the display device, and performing
optimization, in the present invention will be described below.
That is, the processes of determining, in the conductive film
according to the present invention, a wiring pattern which is
optimized so that moire with respect to a predetermined BM pattern
of the display device is not perceived by human visual sensation,
will be described below.
[0081] FIG. 6 is a flowchart illustrating an example of a method of
determining a wiring pattern of the conductive film according to
the present invention.
[0082] In the method of determining a wiring pattern of the
conductive film according to the present invention, frequencies and
intensities of moire are calculated from the peak frequencies and
intensities obtained by frequency analysis using fast Fourier
transform (FFT) of the BM (pixel array) pattern of the display unit
of the display device and the wiring pattern of the conductive
film, frequencies and intensities of moire being not visible are
empirically determined from the calculated frequencies and
intensities of moire, and a wiring pattern satisfying these
conditions is determined as a wiring pattern optimized so that
moire is not visually recognized. In the method according to the
present invention that generally uses FFT for the frequencies and
intensities of moire, the following processes are defined because
the frequency/intensity of a target may greatly vary depending on
the way of usage.
[0083] In the method according to the present invention, first, as
Process 1, transmittance image data of the BM pattern and the
wiring pattern is prepared. That is, as illustrated in FIG. 6, in
step 910, transmittance image data of the BM pattern 38 (BM 34)
(see FIG. 4) of the display unit 30 of the display device 40
illustrated in FIG. 5 and transmittance image data of the wiring
pattern 62 (of the thin metal wires 14) of the conductive film 60
(see FIG. 7B) are prepared and acquired. When the transmittance
image data of the BM pattern 38 and the transmittance image data of
the wiring pattern 62 are provided or stored in advance, the data
may be acquired from among those provided or stored.
[0084] For example, as illustrated in FIG. 7A and FIG. 7C which is
a partially-enlarged view of FIG. 7A, the BM pattern 38 of the
display unit 30 can be set to a pattern which comprises the
sub-pixels 32r, 32g and 32b for three colors R, G and B per pixel
32. 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 be set to 0. In
the present invention, image data of the BM 34, that is, the
transmittance image data of the BM pattern 38 is not limited to the
pattern having rectangular openings of the BM 34 (for the
sub-pixels 32r, 32g, and 32b) as illustrated in FIG. 7C. A usable
BM pattern may not have the rectangular openings of the BM 34 or a
BM pattern having arbitrary BM openings may be designated and used.
For example, the BM pattern is not limited to a pattern having
simple rectangular openings, but the BM pattern may have notched
rectangular openings, strip-like openings bent at a predetermined
angle, curved strip-like openings, or hooked openings.
[0085] Meanwhile, the wiring pattern 62 of the conductive film 60
may be in a square lattice shape as illustrated in FIG. 7B,
whereupon the thin metal wires 14 forming the wiring pattern are so
arranged as to incline 45 degrees.
[0086] Here, the size of the transmittance image data of the BM
pattern 38 and the wiring pattern 62 is defined to be, for example,
4096 (pixels).times.4096 (pixels). In order to prevent or reduce
artifacts of period during the FFT processing of Process 2 to be
described later, it is preferable that the images of the BM pattern
38 and the wiring pattern 62 be each subjected to flipping
processing in all directions (eight directions) as illustrated in
FIG. 8. A new image size after the flipping processing is
preferably the image size (8192 (pixels)=4096 (pixels).times.2 for
each side) of the area surrounded with a dotted line in FIG. 8 that
corresponds to four images.
[0087] Next, as Process 2, the transmittance image data prepared in
Process 1 is subjected to a two-dimensional fast Fourier transform
(2DFFT (base 2)). That is, as illustrated in FIG. 6, in step S12,
the transmittance image data of the BM pattern 38 and the
transmittance image data of the wiring pattern 62 prepared in step
S10 are each subjected to the 2DFFT (base 2) processing, and peak
frequencies and peak intensities of plural spectrum peaks in each
of the two-dimensional Fourier spectrums of the transmittance image
data of the BM pattern 38 and the wiring pattern 62 are calculated.
Here, the peak intensities are treated as their absolute
values.
[0088] FIGS. 9A and 9B are diagrams illustrating intensity
characteristics of the two-dimensional Fourier spectrums of the
transmittance image data of the BM pattern 38 and the wiring
pattern 62, respectively.
[0089] In FIGS. 9A and 9B, the intensity is high in white parts,
that is to say, the white parts indicate spectrum peaks.
Accordingly, the peak frequencies and the peak intensities of the
spectrum peaks are calculated for each of the BM pattern 38 and the
wiring pattern 62 from the results illustrated in FIGS. 9A and 9B.
In other words, with respect to the spectrum peaks found in the
intensity characteristics of the two-dimensional Fourier spectrums
of the BM pattern 38 and the wiring pattern 62 as illustrated in
FIGS. 9A and 9B, respectively, positions of the spectrum peaks,
namely peak positions, on the frequency coordinates represent peak
frequencies, and intensities of the two-dimensional Fourier
spectrums at the peak positions are peak intensities.
[0090] Here, the peak frequencies and the peak intensities of the
spectrum peaks of the BM pattern 38 and the wiring pattern 62 are
calculated and acquired as follows.
[0091] First, in calculation of peaks for acquiring the peak
frequencies, frequency peaks are calculated from the basic
frequencies of the BM pattern 38 and the wiring pattern 62. This is
because the transmittance image data to be subjected to the 2DFFT
processing is acquired as discrete values and thus the peak
frequency depends on the reciprocal of the image size. As
illustrated in FIG. 10, frequency peak positions can be expressed
by a combination of independent two-dimensional basic frequency
vector components a(bar) and b(bar). Consequently, the acquired
peak positions form a lattice shape. While FIG. 10 is a graph
illustrating the frequency peak positions in the case of the BM
pattern 38, the frequency peak positions for the wiring pattern 62
can be calculated in the same way.
[0092] Meanwhile, in acquiring of peak intensities, since the peak
positions are calculated in the aforementioned acquisition of the
peak frequencies, the intensities (absolute values thereof) of the
two-dimensional Fourier spectrums at the peak positions are
acquired. At this time, since digital data is subjected to the FFT
processing, a peak position may be located on plural pixels at a
time. For example, when the intensity (Sp) characteristics of a
two-dimensional Fourier spectrum are expressed by the curve (analog
values) illustrated in FIG. 11A, the digitized intensity
characteristics of the same two-dimensional Fourier spectrum are
expressed by the bar graph (digital values) illustrated in FIG.
11B, and the intensity peak P of the two-dimensional Fourier
spectrum illustrated in FIG. 11A is on the boundary between two
pixels in FIG. 11B corresponding to FIG. 11A. Accordingly, at the
time of acquiring the intensity present at a peak position, the
average of spectral intensities of some pixels selected in
descending order of spectral intensity from an area including
plural pixels around the peak position, for example, five pixels
selected in descending order of spectral intensity from an area of
5.times.5 pixels, is preferably set as the peak intensity (absolute
value).
[0093] Here, it is preferable that the acquired peak intensity be
normalized with the image size. In the above-mentioned example, it
is preferable that the peak intensity be normalized with an image
size of 8192.times.8192 (Parseval's theorem).
[0094] Then, as Process 3, frequency information and intensity
information of moire are calculated. That is, as illustrated in
[0095] FIG. 6, in step S14, the frequency information and the
intensity information of moire are respectively calculated from the
peak frequencies and the peak intensities of the two-dimensional
Fourier spectrums of the BM pattern 38 and the wiring pattern 62
calculated in step S12. Here, the peak intensities and the
intensity information of moire are also treated as their absolute
values.
[0096] Since moire is essentially caused by the multiplication of
the transmittance image data of the wiring pattern 62 and the BM
pattern 38 in the real space, a convolution of the two patterns is
to be performed in the frequency space. However, since the peak
frequencies and the peak intensities of the two-dimensional Fourier
spectrums of the BM pattern 38 and the wiring pattern 62 are
calculated in step S12, the difference (absolute value of the
difference) between the frequency peaks of the two patterns may be
calculated so as to determine the calculated difference to be the
frequency information of moire, and the product of two combinations
of vector intensities of the patterns may be calculated so as to
determine the calculated product to be the intensity information
(absolute value) of moire.
[0097] Here, the difference between the frequency peaks found in
the intensity characteristics of the two-dimensional Fourier
spectrums of the BM pattern 38 and the wiring pattern 62
respectively illustrated in FIGS. 9A and 9B corresponds to the
relative distance between the peak positions on the frequency
coordinates of the frequency peaks of the two patterns that are
found in the intensity characteristics acquired by superimposing
the intensity characteristics of the two-dimensional Fourier
spectrums of the patterns on each other.
[0098] Since the number of spectrum peaks in the two-dimensional
Fourier spectrums of the BM pattern 38 and the wiring pattern 62 is
two or more for each spectrum, differences between the frequency
peaks as values of the relative distance are also two or more in
number, that is to say, the frequency information of moire is
obtained as two or more pieces of information.
[0099] Accordingly, when a large number of spectrum peaks are
present in the two-dimensional Fourier spectrums, the number of
pieces of frequency information of moire to be calculated also
becomes large, and the time is required for the calculation
thereof. In that case, only spectrum peaks with high peak
intensities may be selected in advance from among the spectrum
peaks in the respective two-dimensional Fourier spectrums. Since
only the differences between the peaks respectively selected are
calculated, the calculation time can be shortened.
[0100] The frequency information of moire and the intensity
information of moire acquired in this way are illustrated in FIG.
12. FIG. 12 is a diagram schematically illustrating the frequency
information and the intensity information of the moire generated by
interference between the pixel array pattern illustrated in FIG. 7A
and the wiring pattern illustrated in FIG. 7B, and it can be said
that FIG. 12 illustrates the result of the convolution between the
intensity characteristics of the two-dimensional Fourier spectrums
illustrated in FIGS. 9A and 9B.
[0101] In FIG. 12, the frequency information of moire is expressed
by positions on the vertical and horizontal axes and the intensity
information of moire is expressed by a gray scale (achromatic
colors), where a darker color indicates a lower intensity and a
lighter color, namely, a color closer to white indicates a higher
intensity.
[0102] Then, as Process 4, a visibility limit value of moire is
determined.
[0103] Specifically, first, as illustrated in FIG. 6, in step S16,
a standard visual response characteristic of human beings
illustrated in FIG. 13 is applied to the frequency information of
moire and the intensity information (absolute value thereof) of
moire acquired in step S14, that is to say, the acquired frequency
information and intensity information of moire are multiplied by
the standard visual response characteristic, and the frequencies of
moire and the intensity (absolute value) of moire are calculated.
In other words, the acquired frequency information and intensity
information of moire are convoluted with a visual transfer function
(VTF) illustrated in FIG. 13 as an exemplary standard visual
response characteristic of human beings. The visual transfer
function has a Dooley-Shaw function as a basis and removes
attenuation of sensitivity to low-frequency components.
[0104] In this embodiment, the Dooley-Shaw function at an
observation distance of 300 mm under conditions of distinct vision
is used as a standard visual response characteristic of human
beings. The Dooley-Shaw function is a kind of visual transfer
function (VTF) and is a representative function simulating a
standard visual response characteristic of human beings.
Specifically, the Dooley-Shaw function corresponds to the square of
the contrast ratio characteristic of luminance. The horizontal axis
of the graph represents the spatial frequency (unit: cycles/mm) and
the vertical axis represents the VTF value (unit:
dimensionless).
[0105] When the observation distance is 300 mm, the VTF value is
constant (equal to 1) in a range of 0 cycle/mm to 1.0 cycles/mm and
the VTF value tends to decrease as the spatial frequency increases.
That is, this function serves as a low-pass filter that cuts off
mid-to-high spatial frequency bands.
[0106] The actual visual response characteristic of human beings
has a value smaller than 1 in the vicinity of 0 cycle/mm and thus
shows a so-called band-pass filter characteristic. However, in this
embodiment, the attenuation of sensitivity to low-frequency
components is removed by setting the VTF value to 1 even in a very
low spatial frequency band, as illustrated in FIG. 13. Accordingly,
it is possible to suppress periodicity due to the repeated
arrangement of the wiring pattern 62.
[0107] Then, as illustrated in FIG. 6, in step S18, with respect to
the frequencies of moire and the intensities (absolute values
thereof) of moire acquired in step S16, the sum of the intensities
(absolute values thereof) of moire which are each corresponding to
frequencies of moire falling within a predetermined frequency range
determined depending on the standard visual response characteristic
is calculated. That is, the convolution with the VTF is performed
and then, with respect to the frequencies and intensities of moire,
ranking for optimization is performed. Here, for the matching with
the visual sensitivity, after the convolution with the VTF (step
S16), conversion to the density is performed and the common
logarithm is applied to the intensities. Further, in order to
efficiently perform ranking in visibility of moire, the following
conditions are empirically set up. That is, in the conditions
below, the intensities of moire refers to the density as converted
therefrom.
[0108] The conditions for the above ranking of patterns are as
follows.
[0109] 1. The ranking should be performed using only data in which
the spatial frequencies of moire is up to 3 cycles/mm.
[0110] 2. A pattern involving intensities of moire greater than or
equal to -5 at a spatial frequency of 1.8 cycles/mm or less should
not undergo the ranking.
[0111] 3. A pattern involving intensities of moire greater than or
equal to -3.7 at a spatial frequency greater than 1.8 cycles/mm but
not greater than 3 cycles/mm should not undergo the ranking.
[0112] Under these conditions, a smaller sum of the intensities of
moire is more preferable, and the wiring pattern 62 which causes
the sum of the intensities of moire to be less than or equal to 0
in terms of common logarithm (less than or equal to 1 in terms of
antilogarithm) is set as the optimized wiring pattern 24 of the
present invention. When plural optimized wiring patterns 24 are
acquired, needless to say, the wiring pattern causing the smallest
sum of the intensities of moire is set as the best wiring pattern
24, and the plural optimized wiring patterns 24 are ranked.
[0113] With respect to a large number of wiring patterns 62, the
sum of the intensities of moire was calculated using simulation
samples and actual samples, and three researchers evaluated the
wiring patterns 62 and the sums of the intensities of moire. When
the sum of the intensities of moire was less than or equal to -4 in
terms of common logarithm (less than or equal to 10.sup.-4 in terms
of antilogarithm), moire was not visually recognized at all through
sensory evaluation, which was evaluated to be excellent (++). When
the sum of the intensities of moire was greater than -4 but not
greater than -2.5 in terms of common logarithm (greater than
10.sup.-4 but not greater than 10.sup.-2.5 in terms of
antilogarithm), moire was hard to visually recognize through
sensory evaluation, which was evaluated to be good (+). When the
sum of the intensities of moire was greater than -2.5 but not
greater than 0 in terms of common logarithm (greater than
10.sup.-25 but not greater than 1 in terms of antilogarithm), moire
was visually recognized through sensory evaluation but to a slight
and negligible extent, which was evaluated to be fair (+-). When
the sum of the intensities of moire was greater than 0 in terms of
common logarithm (greater than 1 in terms of antilogarithm), moire
was visually recognized through sensory evaluation, which was
evaluated to be no good (unacceptable).
[0114] Therefore, in the present invention, the sum of the
intensities of moire is limited to be less than or equal to 0 in
terms of common logarithm (less than or equal to 1 in terms of
antilogarithm).
[0115] Then, as illustrated in FIG. 6, in step S20, the sum of the
intensities of moire calculated in step S18 is compared with a
predetermined value so as to determine whether it is true or not
that the sum of the intensities of moire is less than or equal to
the predetermined value, for example, 0.
[0116] When it is determined as a result of comparison that the sum
of the intensities of moire is greater than the predetermined
value, the transmittance image data of the wiring pattern 62 is
renewed to transmittance image data of another wiring pattern in
step S22, and the routine is returned to step S12.
[0117] Here, the wiring pattern for data renewal may be provided in
advance or may be prepared newly. When the wiring pattern is newly
prepared, one or more of the rotation angle, the pitch and the
pattern width in the transmittance image data of the wiring pattern
may be changed, or the shape or the size of the openings of the
wiring pattern may be changed. In addition, randomness may be given
to such factors.
[0118] Thereafter, the calculation of the peak frequencies and the
peak intensities in step S12, the calculation of the frequency
information and intensity information of moire in step S14, the
calculation of the frequencies and intensities of moire in step
S16, the calculation of the sum of the intensities of moire in step
S18, the comparison of the sum of the intensities of moire with the
predetermined value in step S20, and the renewal of the
transmittance image data of the wiring pattern in step S22 are
repeatedly performed until the sum of the intensities of moire is
less than or equal to the predetermined value.
[0119] On the other hand, when it is determined that the sum of the
intensities of moire is less than or equal to the predetermined
value, the wiring pattern 62 is set in step S24 as an optimized
wiring pattern, and then is determined to be the wiring pattern 24
of the conductive film 10 or 11 according to the present
invention.
[0120] In this way, the method for determining the wiring pattern
of the conductive film according to the present invention ends,
whereby it is possible to manufacture the conductive film according
to the present invention having an optimized wiring pattern in
which the occurrence of more is suppressed and the visibility of
moire is excellent even when the wiring pattern is superimposed on
the BM pattern of the display unit of the display device.
[0121] Hereinbefore, while the conductive film according to the
present invention, the display device equipped with the conductive
film, and the method for determining a pattern of the conductive
film have been described with reference to various embodiments and
examples, the present invention is not limited to the embodiments
and the examples and may be improved or modified in various forms
without departing from the gist of the present invention.
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