U.S. patent application number 14/305368 was filed with the patent office on 2015-12-17 for touch panel and film body.
This patent application is currently assigned to GUNZE LIMITED. The applicant listed for this patent is GUNZE LIMITED. Invention is credited to Haruya KAKUTA, Kenzo WADA.
Application Number | 20150362948 14/305368 |
Document ID | / |
Family ID | 54783143 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150362948 |
Kind Code |
A1 |
WADA; Kenzo ; et
al. |
December 17, 2015 |
TOUCH PANEL AND FILM BODY
Abstract
Provided is a touch panel and a film body, which ensure that a
region where the touch panel and a display section are in contact
with each other is hard to be conspicuous and that an apparatus
formed by the touch panel and a display device can be made thinner.
The touch panel is a transparent touch panel which is disposed with
air gaps provided at predetermined intervals between the
transparent touch panel and a surface of a display section of a
display device, wherein a back surface of the transparent touch
panel facing the surface of the display section is provided with a
projection formation layer on which a plurality of fine projections
protruding toward the surface side of the display section are
dispersively formed, the surface of the projection formation layer
is configured to have an average irregularity height (Ra) of equal
to or more than 0.01 .mu.m and equal to or less than 0.06 .mu.m and
a maximum irregularity height (Ry) of equal to or more than 0.15
.mu.m and equal to or less than 0.70 .mu.m, and the projections
having a height of equal to or more than 0.1 .mu.m are dispersed
with a density of equal to or more than 100 and equal to or less
than 180 per 1 mm.sup.2.
Inventors: |
WADA; Kenzo; (Kyoto, JP)
; KAKUTA; Haruya; (Kyoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GUNZE LIMITED |
Kyoto |
|
JP |
|
|
Assignee: |
GUNZE LIMITED
Kyoto
JP
|
Family ID: |
54783143 |
Appl. No.: |
14/305368 |
Filed: |
June 16, 2014 |
Current U.S.
Class: |
345/173 ;
428/141 |
Current CPC
Class: |
G06F 3/0446 20190501;
G06F 3/0445 20190501; G06F 2203/04103 20130101; Y10T 428/24355
20150115; G06F 3/0443 20190501; G06F 3/0412 20130101; G06F 3/044
20130101 |
International
Class: |
G06F 1/16 20060101
G06F001/16; G06F 3/041 20060101 G06F003/041 |
Claims
1. A transparent touch panel which is disposed with air gaps
provided at predetermined intervals between the transparent touch
panel and a surface of a display section of a display device,
wherein a back surface of the transparent touch panel facing the
surface of the display section is provided with a projection
formation layer on which a plurality of fine projections protruding
toward the surface side of the display section are dispersively
formed, the surface of the projection formation layer is configured
to have an average irregularity height (Ra) of equal to or more
than 0.01 .mu.m and equal to or less than 0.06 .mu.m and a maximum
irregularity height (Ry) of equal to or more than 0.15 .mu.m and
equal to or less than 0.70 .mu.m, and the projections having a
height of equal to or more than 0.1 .mu.m are dispersed with a
density of equal to or more than 100 and equal to or less than 180
per 1 mm.sup.2.
2. The transparent touch panel according to claim 1, wherein the
projection formation layer is formed by applying a resin
composition containing fine particles having an average particle
size of equal to or more than 1.5 .mu.m and equal to or less than
3.5 .mu.m.
3. A film body which is placed on a transparent touch panel, the
film body comprising: a transparent film base material; and a
projection formation layer formed on one surface of the film base
material, wherein the surface of the projection formation layer is
configured to have an average irregularity height (Ra) of equal to
or more than 0.01 .mu.m and equal to or less than 0.06 .mu.m and a
maximum irregularity height (Ry) of equal to or more than 0.15
.mu.m and equal to or less than 0.70 .mu.m, and fine projections
having a height of equal to or more than 0.1 .mu.m are dispersed
with a density of equal to or more than 100 and equal to or less
than 180 per 1 mm.sup.2.
4. The film body according to claim 3, wherein the film body has a
haze value of equal to or more than 0.3% and equal to or less than
1.0%.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a touch panel and a film
body.
[0003] (2) Description of Related Art
[0004] Touch panels have been heretofore placed on display devices
in, for example, game machines, portable information terminals,
mobile phones, ticket-vending machines, conference tables, bank
ATMs, personal computers, electronic notebooks, PDA, and so on, and
widely used for performing operations of game machines and portable
information terminals etc. Various studies have been heretofore
conducted on the configuration of the touch panel, and for example,
an electrostatic capacitance type touch panel, a resistance film
type touch panel and the like are known. The electrostatic
capacitance type touch panel is configured such that a dielectric
layer is interposed between a pair of transparent planar bodies
each including a transparent conductor having a predetermined
pattern shape, and when a finger or the like touches an operation
screen, a touch position is detected by utilizing a change in
electrostatic capacity due to connection to the ground through a
human body (for example FIG. 1 and FIG. 5 in Japanese Patent
Laid-Open No. 2003-173238). The resistance film type touch panel is
configured such that a transparent conductive film (resistance
film) is provided on each of upper and lower transparent
substrates, the transparent conductive films are made to face each
other with an air layer held therebetween, and the transparent
conductive films are brought into contact with each other by a
pressing force to detect a touch position (FIG. 7 in Japanese
Patent Laid-Open No. 2003-173238).
[0005] For example, as shown in the sectional view of FIG. 8, a
touch panel 200 is mounted with a frame-shaped adhesive seal member
203, which is disposed on the outer edge portion of a display
section 202 in a display device 201, interposed between the touch
panel and the display section while an air gap (clearance) 204 is
provided between a surface of the display section 202 and a back
surface of the touch panel.
[0006] Here, surfaces of the touch panel 200 and the display
section 201 have a slight distortion, and therefore when the touch
panel 200 is placed on the display section 202 without providing
the clearance 204, there exist a contact region where a back
surface 200a of the touch panel 200 and a surface 202a of the
display section 202 are in close contact with each other and a
non-contact region where the back surface 200a and the surface 202a
are not in close contact with each other. If the contact region is
large enough to be visible, a boundary between the contact region
and the non-contact region becomes conspicuous due to a difference
between travel paths of light passing through the contact region
and the non-contact region, so that an image or the like cannot be
evenly displayed. For avoiding the above-mentioned situation, the
touch panel 200 is mounted on the display section 202 with the
clearance 204 provided between the surface of the display section
202 and the back surface of the touch panel 200.
[0007] However, concerning a touch panel placed with a clearance
provided between the touch panel and a display section of a display
device, there is the problem that it is difficult to maintain the
clearance throughout the panel. Specifically, there is the
possibility that the panel itself is warped or distorted as the
touch panel is continuously used, or the touch panel is deformed at
the time when the touch panel is pressed, and resultantly a part of
the touch panel sticks to the surface of the display section, so
that the back surface of the touch panel and the surface of the
display section partially come into contact with each other as
shown in FIG. 9. In a severe case, the touch panel persistently
sticks on the surface of the display section, and it takes a long
time until the original state is restored. In this case, there is
the problem that due to a significant difference between travel
paths of light in a region where the touch panel and the display
section are in contact with each other (contact region) and a
region where they are not in contact with each other (non-contact
region), a boundary between the contact region and the non-contact
region (hereinafter, referred to as a "water mark") becomes
conspicuous. If the water mark is generated, the contrast or color
tone of an image or the like displayed by the display section may
become uneven, thus making it impossible to evenly display the
image or the like.
[0008] For avoiding contact of the touch panel with the display
section, the thickness of an adhesive seal member may be set so
that the clearance between the touch panel and the display section
becomes relatively large, but in this case, there is the problem
that thinning of an apparatus formed by the touch panel and the
display device is restricted.
[0009] Thus, concerning a touch panel placed with a clearance
provided between the touch panel and a display section of a display
device, it is difficult to ensure both that a region where the
touch panel and the display section are in contact with each other
is hard to be conspicuous and that an apparatus formed by the touch
panel and the display device is made thinner.
SUMMARY OF THE INVENTION
[0010] Accordingly, an object of the present invention is to
provide a touch panel and a film body, which ensure that a region
where the touch panel and a display section are in contact with
each other is hard to be conspicuous and that an apparatus formed
by the touch panel and a display device can be made thinner.
[0011] The object of the present invention is achieved by a
transparent touch panel which is disposed with air gaps provided at
predetermined intervals between the transparent touch panel and a
surface of a display section of a display device, wherein a back
surface of the transparent touch panel facing the surface of the
display section is provided with a projection formation layer on
which a plurality of fine projections protruding toward the surface
side of the display section are dispersively formed, the surface of
the projection formation layer is configured to have an average
irregularity height (Ra) of equal to or more than 0.01 .mu.m and
equal to or less than 0.06 .mu.m and a maximum irregularity height
(Ry) of equal to or more than 0.15 .mu.m and equal to or less than
0.70 .mu.m, and the projections having a height of equal to or more
than 0.1 .mu.m are dispersed with a density of equal to or more
than 100 and equal to or less than 180 per 1 mm.sup.2.
[0012] Preferably, the projection formation layer is formed by
applying a resin composition containing fine particles having an
average particle size of equal to or more than 1.5 .mu.m and equal
to or less than 3.5 .mu.m.
[0013] Further, the object of the present invention is achieved by
a film body which is placed on a transparent touch panel, the film
body including:
[0014] a transparent film base material; and a projection formation
layer formed on one surface of the film base material, wherein
[0015] the surface of the projection formation layer is configured
to have an average irregularity height (Ra) of equal to or more
than 0.01 .mu.m and equal to or less than 0.06 .mu.m and a maximum
irregularity height (Ry) of equal to or more than 0.15 .mu.m and
equal to or less than 0.70 .mu.m, and fine projections having a
height of equal to or more than 0.1 .mu.m are dispersed with a
density of equal to or more than 100 and equal to or less than 180
per 1 mm.sup.2.
[0016] Preferably, the film body has a haze value of equal to or
more than 0.3% and equal to or less than 1.0%.
[0017] According to the present invention, there can be provided a
touch panel and a film body, which ensure that a region where the
touch panel and a display section are in contact with each other is
hard to be conspicuous and that an apparatus formed by the touch
panel and a display device can be made thinner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic sectional view of a transparent touch
panel according to one embodiment of the present invention;
[0019] FIG. 2 is a plan view showing a part of the transparent
touch panel shown in FIG. 1;
[0020] FIG. 3 is a plan view showing another part of the
transparent touch panel shown in FIG. 1;
[0021] FIG. 4 is a plan view showing a part of a modification of
the transparent touch panel shown in FIG. 1;
[0022] FIG. 5 is a plan view showing another part of the
modification of the transparent touch panel shown in FIG. 1;
[0023] FIG. 6 is an enlarged sectional view of a principal part of
a film body included in the transparent touch panel shown in FIG.
1;
[0024] FIG. 7 is a schematic sectional view for explaining a state
in which the back surface side of a transparent touch panel and a
surface of a display section are in contact with each other;
[0025] FIG. 8 is a sectional view showing a state in which a
conventional touch panel is placed on a display section of a
display device; and
[0026] FIG. 9 is a schematic sectional view for explaining a state
in which a back surface of a touch panel and a surface of a display
section are in contact with each other.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0027] Hereinafter, preferred embodiments of the present invention
will be described with reference to the attached drawings. It is to
be noted that the respective drawings are not based on an actual
dimension ratio, but are partially scaled up or scaled down for
easy understanding of the configuration.
[0028] FIG. 1 is a schematic block sectional view of a transparent
touch panel according to one embodiment of the present invention. A
transparent touch panel 101 is an electrostatic capacitance type
touch panel, and includes a touch panel main body 100 and a film
body 6. The touch panel main body 100 includes a first transparent
planar body 1 and a second transparent planar body 2, and the first
transparent planar body 1 includes a transparent substrate 11, and
a transparent conductive film 12 patterned on one surface side of
the transparent substrate 11. The second transparent planar body 2
has a configuration similar to that of the first transparent planar
body 1, and includes a transparent substrate 21, and a transparent
conductive film 22 patterned on one surface side of the transparent
substrate 21.
[0029] The first transparent planar body 1 and the second
transparent planar body 2 are bonded together with a pressure
sensitive adhesive layer 4 interposed therebetween such that the
other surface (surface that is not provided with the transparent
conductive film 12) of the transparent substrate 11 in the first
transparent planar body 1 and the transparent conductive film 22 in
the second transparent planar body 2 face each other while being
separated from each other as shown in FIG. 1. A protective layer 3
for protecting the transparent conductive film 12 is provided on
the transparent conductive film 12 in the first transparent planar
body 1 with a pressure sensitive adhesive layer 5 interposed
therebetween. For the protective layer 3, various kinds of films
subjected to surface treatment processing for improvement of
scratch resistance, abrasion resistance, fingerprint resistance,
non-glare characteristics and so on can be preferably used. The
film body 6 is bonded to the other surface (surface that is not
provided with the transparent conductive film 22) of the
transparent substrate 21 in the second transparent planar body 2
with a pressure sensitive adhesive layer 7 interposed therebetween.
The first transparent planar body 1 and the second transparent
planar body 2 may be bonded together with the pressure sensitive
adhesive layer 4 interposed therebetween such that the transparent
conductive film 12 in the first transparent planar body 1 and the
transparent conductive film 22 in the second transparent planar
body 2 face each other while being separated from each other. Other
possible configurations include a configuration in which in place
of the first transparent planar body 1 and the pressure sensitive
adhesive layer 4, a dielectric layer is provided on the second
transparent planar body 2 (transparent conductive films 12 and 22
are disposed with dielectric layer interposed therebetween so as to
face each other while being separated from each other), and a
configuration in which patterns of the transparent conductive films
12 and 22 are provided on the transparent substrate 21 in the
second transparent planar body 2 without providing the first
transparent planar body 1 and the pressure sensitive adhesive layer
4 (patterns in the X direction and the Y direction are formed in
one layer of transparent conductive film).
[0030] Preferably, the transparent substrates 11 and 21 each are a
dielectric substrate that forms an insulating layer, and are
composed of a material having high transparency. Specifically, the
transparent substrate is formed from, for example, a flexible film
made of a synthetic resin such as polyethylene terephthalate (PET),
polyimide (PI), polyethylene naphthalate (PEN), polyether sulfone
(PES), polyether ether ketone (PEEK), polycarbonate (PC),
polypropylene (PP), polystyrene (PS), polyamide (PA), polyacryl
(PAC), acryl, an amorphous polyolefin-based resin, a cyclic
polyolefin-based resin, an aliphatic cyclic polyolefin, a
norbornene-based thermoplastic transparent resin, or a laminate of
two or more thereof, or a glass sheet such as that of soda glass,
non-alkali glass, borosilicate glass or quartz glass. The thickness
of the transparent substrates 11 and 21 is not particularly
limited, but for example when the transparent substrates 11 and 21
are formed from a flexible film made of a synthetic resin, the
thickness thereof is preferably about 10 .mu.m to 500 .mu.m,
further preferably about 20 .mu.m to 250 .mu.m. When the
transparent substrates 11 and 21 are formed from a glass sheet, the
thickness thereof is preferably about 20 .mu.m to 1000 .mu.m.
Preferably, the photorefractive index of the transparent substrates
11 and 21 is set to fall within a range of equal to or more than
1.4 and equal to or less than 1.7.
[0031] When the transparent substrates 11 and 21 are formed from a
material having flexibility, a support may be bonded for imparting
rigidity to the transparent substrates 11 and 21. Examples of the
support may include glass sheets and resin materials having a
hardness comparable to that of glass, and the thickness thereof is
preferably equal to or more than 100 .mu.m, more preferably 0.2 mm
to 10 mm.
[0032] Examples of the material of the transparent conductive films
12 and 22 may include transparent conductive materials such as
indium tin oxide (ITO), indium oxide, antimony-added tin oxide,
fluorine-added tin oxide, aluminum-added zinc oxide,
potassium-added zinc oxide, silicon-added zinc oxide, zinc
oxide-tin oxide systems, indium oxide-tin oxide systems, zinc
oxide-indium oxide-magnesium oxide systems, zinc oxide and tin
oxide films, metallic materials such as those of tin, copper,
aluminum, nickel and chromium, and metal oxide materials, and two
or more thereof may be combined to form the transparent conductive
film. A metal alone can be used as a conductive material.
[0033] A composite material obtained by dispersing ultrafine
conductive carbon fibers such as carbon nanotubes, carbon
nanohorns, carbon nanowires, carbon nanofibers or graphite fibrils,
or ultrafine metallic fibers composed of a metallic base material
such as silver in a polymer material serving as a binder can also
be used as a material of the transparent conductive films 12 and
22. Here, as the polymer material, a conductive polymer can be
employed such as polyaniline, polypyrrole, polyacetylene,
polythiophene, polyphenylene vinylene, polyphenylene sulfide,
poly-p-phenylene, poly-heterocyclic vinylene or PEDOT:
poly(3,4-ethylenedioxythiophene). A non-conductive polymer can be
employed such as polyethylene terephthalate (PET), polyethylene
naphthalate (PEN), polyether sulfone (PES), polyether ether ketone
(PEEK), polycarbonate (PC), polypropylene (PP), polyamide (PA),
polyacryl (PAC), polyimide, an epoxy resin, a phenol resin, an
aliphatic cyclic polyolefin or a norbornene-based thermoplastic
transparent resin.
[0034] Particularly when a carbon nanotube composite material
obtained by dispersing carbon nanotubes in a non-conductive polymer
material is employed as a material of the transparent conductive
films 12 and 22, since the carbon nanotube is generally has a very
small diameter of 0.8 nm to 1.4 nm (around 1 nm), it is preferred
for securing transparency of the transparent conductive films 12
and 22 to disperse carbon nanotubes in the non-conductive polymer
material one by one or on a bundle-to-bundle basis because the
possibility is reduced that carbon nanotubes hinder light
transmission.
[0035] Examples of the method for forming the transparent
conductive films 12 and 22 may include PVD methods such as a
sputtering method, a vacuum vapor deposition method and an ion
plating method, CVD methods, coating methods and printing methods.
Preferably, the thickness of the transparent conductive films 12
and 22 is set to fall within a range of equal to or more than 15 nm
and equal to or less than 50 nm. Preferably, the photorefractive
index of the transparent conductive films 12 and 22 is set to fall
within a range of equal to or more than 1.9 and equal to or less
than 2.3.
[0036] The transparent conductive films 12 and 22 are formed as
assemblies of a plurality of belt-shaped conductive portions 12a
and 22a extending in parallel as shown in FIG. 2 and FIG. 3,
respectively, and the belt-shaped conductive portions 12a and 22a
of the respective transparent conductive films 12 and 22 are
disposed so as to orthogonally cross each other. The transparent
conductive films 12 and 22 are each connected to an external drive
circuit (not illustrated) through a drawing circuit (not
illustrated) composed of a conductive ink or the like. The pattern
shapes of the transparent conductive films 12 and 22 are not
limited to those of this embodiment, and can be any shape as long
as a contact point of a finger or the like can be detected. For
example, as shown in FIG. 4 and FIG. 5, the transparent conductive
films 12 and 22 may be configured such that a plurality of
diamond-shaped conductive portions 12b and 22b are linearly
coupled, where the coupling directions of the diamond-shaped
conductive portions 12b and 22b in the respective transparent
conductive films 12 and 22 orthogonally cross each other and the
upper and lower diamond-shaped conductive portions 12b and 22b do
not overlap one another in plane view. Operation performance, such
as a resolution, of the transparent touch panel 101 is better when
such a configuration is employed that regions having no conductive
portion are decreased when the first transparent planar body 1 and
the second transparent planar body 2 are superimposed on each
other. In view thereof, as the pattern shape of the transparent
conductive films 12 and 22, a configuration in which a plurality of
the diamond-shaped conductive portions 12b and 22b are linearly
coupled is more desirable than a rectangular configuration.
[0037] Patterning of the transparent conductive films 12 and 22 can
be performed in the following manner: a mask portion having a
desired pattern shape is formed on a surface of each of the
transparent conductive films 12 and 22 formed on the transparent
substrates 11 and 21, respectively, and exposed portions are etched
away with an acid liquid or the like, followed by dissolving the
mask portion with an alkali liquid or the like.
[0038] For the pressure sensitive adhesive layers 4, 5 and 7,
general transparent adhesives (including pressure sensitive
adhesives) can be used, and the layers may contain a core material
composed of a transparent film of a norbornene-based resin. A
plurality of sheet-shaped pressure sensitive adhesive materials are
superimposed on one another to form the pressure sensitive adhesive
layers 4, 5 and 7, and a plurality of different kinds of
sheet-shaped pressure sensitive adhesive materials may also be
superimposed on one another to form the pressure sensitive adhesive
layers. The thickness of the pressure sensitive adhesive layers 4,
5 and 7 is not particularly specified, but is preferably equal to
or less than 200 .mu.m, particularly preferably 10 .mu.m to 100
.mu.m from a practical point of view.
[0039] As shown in FIG. 6, the film body 6 includes a film base
material 61, and a projection formation layer 62 formed on at least
one surface of the film base material 61. The film base material 61
is bonded to the second transparent planar body 2 with the pressure
sensitive adhesive layer 7 interposed therebetween such that the
projection formation layer 62 is situated on a display device 9
side. The exposed surface of the projection formation layer 62 is
provided with a plurality of fine projections 62a, and is
configured such that the average irregularity height (Ra) in JIS
B0601 (1994), a surface roughness standard, is equal to or more
than 0.01 .mu.m and equal to or less than 0.06 .mu.m. Further, the
maximum irregularity height (Ry) in JIS B0601 (1994) is equal to or
more than 0.15 .mu.m and equal to or less than 0.70 .mu.m. On the
surface of the projection formation layer 62, projections 62a
having a height of equal to or more than 0.1 .mu.m are dispersed
with a density of equal to or more than 100 and equal to or less
than 180 per 1 mm.sup.2. Here, the height of the projection 62a is
a parameter actually measured by VK-X100 manufactured by KEYENCE
CORPORATION. The interval between the projections 62a falls within
a range of equal to or more than 10 .mu.m and equal to or less than
35 .mu.m. The interval between the projections 62a is a parameter
corresponding to an average interval (Sm) between irregularities in
JIS B0601 (1994), a surface roughness standard.
[0040] The projection formation layer 62 is formed by applying a
predetermined resin composition to one surface of the transparent
film base material 61. Examples of the application method include a
roll coating method, a spin coating method, a coil bar method, a
dip coating method and a die coating method. A method capable of
continuous application, such as a roll coating method, is preferred
from the viewpoint of productivity and production costs. Examples
of the preferred resin composition applied to the film base
material 61 may include resin compositions containing fine
particles having an average particle size of equal to or more than
1.5 .mu.m and equal to or less than 3.5 .mu.m and a binder resin
component. The average particle size is measured using a laser
diffraction method (measurement apparatus: LA-920 manufactured by
HORIBA, Ltd.). As the binder resin, a thermosetting resin, an
ionizing radiation curable resin and the like can be used, and a
single resin may be used, or a plurality of resins may be used in
combination. Examples of the thermosetting resin may include resins
such as thermosetting acrylic resins, thermosetting polyurethane
resins, phenolic resins and thermosetting polyester resins. As the
ionizing radiation curable resin, particularly ultraviolet curable
resins are suitably used, and examples may include acryl-based
ultraviolet curable resins, acryl urethane-based ultraviolet
curable resins, polyester acrylate-based ultraviolet curable
resins, epoxy acrylate-based ultraviolet curable resins and polyol
acrylate-based ultraviolet curable resins. A photopolymerization
initiator may be added as necessary. When an ultraviolet curable
resin is used as the binder resin, the projection formation layer
62 can be formed in the following manner: the ultraviolet curable
resin is applied to the film base material 61, dried for a
predetermined period of time, and then irradiated with ultraviolet
rays to be cured. Preferably, the thickness of the ultraviolet
curable resin applied to the film base material 61 is set to fall
within a range of, for example, equal to or more than 2 .mu.m and
equal to or less than 10 .mu.m. Examples of the fine particles for
formation of projections may include silica fillers, acryl beads
and alumina fillers. For the fine particles contained in the resin
composition, fine particles having an average particle size of 1.5
.mu.m to 3.5 .mu.m are set in an amount of preferably equal to or
more than 1.0 part by weight and equal to or less than 5.0 parts by
weight, more preferably equal to or more than 2.0 parts by weight
and equal to or less than 4.0 parts by weight based on 100 parts by
weight of the binder resin component. A coupling agent and a
dispersant may be used for improving dispersibility of fine
particles. Examples of the dispersant may include amide resins,
acrylic resins and silicone resins. Here, the film base material 61
that forms the projection formation layer 62 can be formed from,
for example, a flexible film made of a synthetic resin such as
polyethylene terephthalate (PET), polyimide (PI), polyethylene
naphthalate (PEN), polyether sulfone (PES), polyether ether ketone
(PEEK), polycarbonate (PC), polypropylene (PP), polystyrene (PS),
polyamide (PA), polyacryl (PAC), acryl, an amorphous
polyolefin-based resin, a cyclic polyolefin-based resin, an
aliphatic cyclic polyolefin, a norbornene-based thermoplastic
transparent resin, or a laminate of two or more thereof, or a glass
sheet such as that of soda glass, non-alkali glass, borosilicate
glass or quartz glass. For example, the thickness of the film base
material 61 is preferably about 30 .mu.m to 250 .mu.m.
[0041] The touch panel 101 having the above-mentioned configuration
is placed on display devices in, for example, game machines,
portable information terminals, mobile phones, ticket-vending
machines, conference tables, bank ATMs, personal computers,
electronic notebooks, PDA, and so on, and used for performing
operations of game machines and portable information terminals etc.
As shown in the sectional view of FIG. 1, the transparent touch
panel 101 is mounted on display device with a frame-shaped adhesive
seal member 8, which is disposed on the outer edge portion of a
display section 9, interposed between the touch panel and the
display section while an air gap G (clearance) is provided between
a surface 9a of the display section 9 and a back surface 101b of
the transparent touch panel 101. When the transparent touch panel
101 is placed on the surface side of the display section 9, a
surface of the projection formation layer 62 (surface provided with
a plurality of fine projections 62a) forms the back surface 101b of
the transparent touch panel which faces the surface of the display
section. The method for detecting a touch position on the
transparent touch panel 101 is similar to that for a conventional
electrostatic capacitance type touch panel, and a finger or the
like touches the touch panel at any position on the surface side of
the first transparent planar body 1, the transparent conductive
films 12 and 22 are connected at the contact position to the ground
through an electrostatic capacitance of a human body. A value of
current through the transparent conductive films 12 and 22 is
detected to calculate coordinates of the contact position.
[0042] The transparent touch panel 101 having the above-mentioned
configuration is configured such that the exposed surface of the
film body 6 (surface of the projection formation layer 62), on
which a plurality of the fine projections 62a are dispersively
formed, faces the surface of the display section of the display
device with the air gap (clearance) interposed therebetween.
Therefore, even if the transparent touch panel 101 is deformed by
the pressing force of the touch panel 101, or the panel itself is
warped or distorted due to continuous use of the transparent touch
panel 101, so that the back surface side of the transparent touch
panel 101 (exposed surface side of the film body 6) and the surface
of the display section partially come into contact with each other,
the surface of the display section and the fine protrusions 62a
come into contact with each other as shown in the schematic
sectional view of FIG. 7, so that contact between smooth surfaces
is prevented, thus making it possible to effectively prevent
generation of a water mark which has been a problem heretofore. As
a result, the contrast or color tone of an image or the like
displayed by the display section can be prevented from becoming
uneven, so that visual recognizability of an image or the like can
be improved. Further, since the film body 6 includes a film
excellent in transparency, which has a haze value (parameter
related to transparency of the film) of equal to or less than 1.0%,
character information and image information displayed by the
display section can be properly visually recognized.
[0043] The present inventors prepared a sample of the film body 6,
attached the sample to a glass sheet having a thickness of 0.7 mm,
placed the same on a display section of a liquid crystal display
device (power source: OFF state) with the projections 62a situated
on the liquid crystal display device side, and conducted a test for
determining whether a so called water mark was generated or
not.
[0044] Five kinds of samples (samples 1 to 5) were prepared. For
explanation of individual samples, first the sample 1 was prepared
in the following manner: a hard coat material, which did not
contain fine particles for formation of projections, was formed in
a thickness (thickness after curing) of 3.0 .mu.m on one surface of
the 50 .mu.m-thick film base material 61 made of PET using a bar
coater. The hard coat material was prepared by dissolving an
acryl-based ultraviolet curable resin (100 parts by weight) and
photopolymerization initiator (4 parts by weight) in a
predetermined amount of an organic solvent (mixed solvent of methyl
ethyl ketone (MEK) and methyl isobutyl ketone (MIBK)). Here, as the
acryl-based ultraviolet curable resin, pentaerythritol triacrylate
was used. As the photopolymerization initiator, IRGACURE 184 from
BASF Ltd. was used. The hard coat material was applied to one
surface of the film base material 61, and then dried with hot air
for 2 minutes at a temperature ranging from 60 degrees to 100
degrees, and after completion of the drying step, ultraviolet rays
were applied to cure the hard coat material. The integrated light
amount of ultraviolet rays is 400 mJ/cm.sup.2.
[0045] The sample 2 was prepared by including fine particles for
formation of projections in the hard coat material of the sample 1.
As the fine particles included in the hard coat material, a silica
filler having an average particle size of 0.1 .mu.m was used. The
fine particles were included in an acryl-based ultraviolet curable
resin (binder resin component) in an amount of 5 parts by weight
based on 100 parts by weight of the acryl-based ultraviolet curable
resin. The sample 2 was formed in the same manner as in the case of
the sample 1 except that fine particles having an average particle
size of 0.1 .mu.m were added in an amount of 5 parts by weight
based on 100 parts by weight of the acryl-based ultraviolet curable
resin as described above. A layer formed from the hard coat
material containing fine particles corresponds to the projection
formation layer 62.
[0046] The sample 3 was prepared by including fine particles for
formation of projections and a dispersant in the hard coat material
of the sample 1. As the fine particles included in the hard coat
material, a silica filler having an average particle size of 2
.mu.m was used. The fine particles were included in an acryl-based
ultraviolet curable resin (binder resin component) in an amount of
3 parts by weight based on 100 parts by weight of the acryl-based
ultraviolet curable resin. As the dispersant, a silicone-based
dispersant was included in an acryl-based ultraviolet curable resin
in an amount of 0.3 parts by weight based on 100 parts by weight of
the acryl-based ultraviolet curable resin. The sample 3 was formed
in the same manner as in the case of the sample 1 except that fine
particles having an average particle size of 2 nm were added in an
amount of 3 parts by weight based on 100 parts by weight of the
acryl-based ultraviolet curable resin and the silicone-based
dispersant was added in an amount of 0.3 parts by weight based on
100 parts by weight of the acryl-based ultraviolet curable resin as
described above. A layer formed from the hard coat material
containing fine particles corresponds to the projection formation
layer 62.
[0047] The sample 4 was prepared by including fine particles for
formation of projections in the hard coat material of the sample 1.
As the fine particles included in the hard coat material, a silica
filler having an average particle size of 2 .mu.m was used. The
fine particles were included in an acryl-based ultraviolet curable
resin (binder resin component) in an amount of 4 parts by weight
based on 100 parts by weight of the acryl-based ultraviolet curable
resin. The sample 4 was formed in the same manner as in the case of
the sample 1 except that fine particles having an average particle
size of 2 .mu.m were added in an amount of 4 parts by weight based
on 100 parts by weight of the acryl-based ultraviolet curable resin
as described above. A layer formed from the hard coat material
containing fine particles corresponds to the projection formation
layer 62.
[0048] The sample 5 was prepared by including fine particles for
formation of projections in the hard coat material of the sample 1.
As the fine particles included in the hard coat material, a silica
filler having an average particle size of 2 .mu.m was used. The
fine particles were included in an acryl-based ultraviolet curable
resin (binder resin component) in an amount of 6 parts by weight
based on 100 parts by weight of the acryl-based ultraviolet curable
resin. The sample 5 was formed in the same manner as in the case of
the sample 1 except that fine particles having an average particle
size of 2 .mu.m were added in an amount of 6 parts by weight based
on 100 parts by weight of the acryl-based ultraviolet curable resin
as described above. A layer formed from the hard coat material
containing fine particles corresponds to the projection formation
layer 62.
[0049] Each of the samples 1 to 5 prepared in the manner described
above was placed on a glass sheet regarded as the display section
of the display device, and a water mark generation state was
visually evaluated when each sample was pressed with a finger. Each
sample was placed without providing the air gap G (clearance)
between the sample and the glass sheet. Evaluation results are
shown in Table 1. Here, in Table 1, a sample, in which a water mark
was not generated, was rated ".largecircle.", and a sample, in
which visually slightly recognizable water mark was generated, was
rated "A". A sample, in which a water mark large enough to be
visually sufficiently recognizable was generated, was rated "x".
The average irregularity height of the projections 62a (Ra), the
maximum irregularity height of the projections 62a (Ry), the
average distance between irregularities of the projections 62a (Sm)
and the number of the projections 62a per 1 mm.sup.2 (the number of
the projections 62a in each of randomly selected three regions
(region A, region B and region C) and the average number thereof)
in each sample are collectively shown in Table 1. The average
irregularity height of the projections 62a (Ra), the maximum
irregularity height of the projections 62a (Ry) and the average
distance between irregularities of the projections 62a (Sm) were
measured using VK-X100 manufactured by KEYENCE CORPORATION, and an
average value of measurements at ten locations was determined. The
measurement method is based on JIS B0601 (1994). The number of the
projections 62a per 1 mm.sup.2 was determined in the following
manner: points recognized as projections (those having a size of
equal to or more than about 0.1 .mu.m) in a region of 0.5
mm.times.0.7 mm were visually counted at a magnification of 400
using VK-X100 manufactured by KEYENCE CORPORATION, and an average
value of measurements at three locations was calculated, and then
corrected to a number per 1 mm.sup.2.
[0050] For each of the samples 1 to 5, a haze value (%), i.e. a
ratio of diffused and transmitted light to total transmitted light
at the time of irradiating a film with visible light, and a
transmittance (%) of visible light were measured, and optical
characteristics of each sample were evaluated. Measurement results
for the values are shown in Table 2. Since the haze value is a
parameter related to transparency of the film, a sample having a
haze value of equal to or less than 1.0% was rated ".largecircle."
as a sample having a satisfactory haze value, a sample having a
haze value of more than 1.0% and less than 2.0% was rated
".DELTA.", and a sample having a haze value of more than 2.0% was
rated "x". For the transmittance, a sample having a transmittance
of equal to or more than 90% was rated "0" as a sample having a
satisfactory transmittance, and a sample having a transmittance of
less than 90% was rated "A". Here, the haze value and the
transmittance were obtained by performing measurements using NDH
5000 manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD. The haze
value was measured in accordance with JIS K7136, and the
transmittance was measured in accordance with JIS K-7361-1. The
results of visually evaluating glare with each sample placed on a
liquid crystal display (LCD) are also collectively shown in Table
2. For glare, a sample having unnoticeable glare was rated
".largecircle.", a sample having slightly glare was rated
".DELTA.", and a sample having intense and hence noticeable glare
was rated "x".
TABLE-US-00001 TABLE 1 Ra (.mu.m) Ry (.mu.m) Sm (.mu.m) Presence/
Average Maximum Distance absence of irregularity irregularity
between Number of projections/mm.sup.2 water height height
irregularities Region A1 Region B Region C Average mark Sample 1 0
0 0 0 0 0 0 x Sample 2 0.01 0.1 36 0 0 0 0 .DELTA. Sample 3 0.04
0.4 20 151 134 169 151 .smallcircle. Sample 4 0.07 0.87 15.7 320
320 331 324 .smallcircle. Sample 5 0.18 1.6 11.4 8194 7491 8023
7903 .smallcircle. ".smallcircle.": no water mark generated
".DELTA.": water mark slightly generated "x": water mark large
enough to be visually sufficiently recognizable generated
TABLE-US-00002 TABLE 2 Transmittance Haze (%) (%) LCD glare Sample
1 0.2 .largecircle. 91.6 .largecircle. .largecircle. Sample 2 0.3
.largecircle. 91.3 .largecircle. .largecircle. Sample 3 0.4
.largecircle. 91.5 .largecircle. .largecircle. Sample 4 1.5 .DELTA.
91.1 .largecircle. .DELTA. Sample 5 6.8 X 89.6 .DELTA. X
[0051] As shown in Table 1, it is apparent that for samples 3 to 5,
a water mark is not generated, and good results can be obtained.
That is, it is apparent that when one related to the sample 3 is
used as the film body 6 of a transparent touch panel that may come
into contact with a surface of a display section, a region where
the transparent touch panel and the display section are in contact
with each other can be made hard to be conspicuous, and as a
result, an apparatus formed by the touch panel and the display
device can be made thinner.
[0052] As shown in Table 2, it is apparent that for samples 1 to 3,
good results are obtained for all of the haze value, the
transmittance and the glare. From these results, it is apparent
that the sample 3 according to the present invention is a film body
having extremely excellent optical characteristics because not only
generation of a water mark can be prevented, but also a
satisfactory haze value and transmittance are achieved, and also
glare can be suppressed. When such a film body is applied to a
touch panel main body, extremely satisfactory visual
recognizability can be secured.
[0053] Embodiments of the transparent touch panel according to the
present invention and the film body 6 in the transparent touch
panel have been described above, but specific configurations are
not limited to the embodiments described above. For example, the
film body 6 may be configured such that an antireflection layer is
further provided on a surface (surface provided with fine
projections 62a) of the projection formation layer 62 in the film
body 6. When such an antireflection layer is provided, light
emitted from the display section provided with the transparent
touch panel easily passes through the transparent touch panel, so
that character information and image information displayed by the
display section can be made easier to see. Here, the antireflection
layer is formed by curing a coating solution for formation of
low-refractive index layer, which contains silica fine particles, a
binder component and so on. As the silica fine particles, a silica
sol, porous silica fine particles, hollow silica fine particles and
the like can be used. As the binder component, a single substance
or a mixture of fluorine-containing organic compounds, or a single
substance or a mixture or a polymer of fluorine-free organic
compounds, etc. can be used. Examples of the method for forming an
antireflection layer include a method in which the coating solution
is applied onto a base material film by a roll coating method, a
spin coating method, a coil bar method, a dip coating method, a die
coating method or the like, dried, and then irradiated with
ultraviolet rays. A method capable of continuous application, such
as a roll coating method, is preferred from the viewpoint of
productivity and production costs. Preferably, the thickness of the
antireflection layer is designed so as to satisfy the relational
expression of nd=.lamda./4 (where n represents a refractive index
of the antireflection layer, d represents a thickness of the
antireflection layer, and .lamda. represents a detection center
sensitivity wavelength of reflected light in the antireflection
layer) from the viewpoint of an antireflection (low reflection)
function.
[0054] Here, the present inventors prepared a sample 6 by forming
an antireflection layer on the surface of the projection formation
layer 62 in the sample 3, place the sample to a glass sheet
regarded as the display section of the display device, and
conducted a test for determining whether a so called water mark was
generated or not. The results thereof are shown in Table 3. The
average irregularity height of the projections 62a (Ra), the
maximum irregularity height of the projections 62a (Ry), the
average distance between irregularities of the projections 62a (Sm)
and the number of the projections 62a per 1 mm.sup.2 (the number of
the projections 62a in each of randomly selected three regions
(region A, region B and region C) and the average number thereof)
in the sample 6 are collectively shown in Table 3 as in the case of
Table 1. The average irregularity height of the projections 62a
(Ra), the maximum irregularity height of the projections 62a (Ry)
and the average distance between irregularities of the projections
62a (Sm) were measured using VK-X100 manufactured by KEYENCE
CORPORATION. The measurement method is based on JIS B0601 (1994).
For the sample 6, the haze value (%) and the transmittance (%) of
visible light were measured, and glare was visually evaluated with
the sample 6 placed on a liquid crystal display (LCD). The results
thereof are shown in Table 4. Here, the haze value and the
transmittance were obtained by performing measurements using NDH
5000 manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD. The haze
value was measured in accordance with JIS K7136, and the
transmittance was measured in accordance with JIS K-7361-1. For
"0", ".DELTA." and "x", i.e. symbols showing evaluation results in
Table 3 and Table 4, results of rating samples are shown based on
the same criteria as the evaluation criteria described above with
regard to Table 1 and Table 2. The antireflection layer was formed
on the surface of the projection formation layer 62 of the sample 3
so as to have a thickness of 0.1 .mu.m using a coating solution
obtained by dissolving an acryl-based ultraviolet curable resin
(100 parts by weight of pentaerythritol triacrylate) and a
photopolymerization initiator (4 parts by weight of IRGACURE 184
from BASF Ltd.) in a predetermined amount of an organic solvent
(mixed solvent of methyl ethyl ketone (MEK) and methyl isobutyl
ketone (MIBK)) and adding a hollow filler.
TABLE-US-00003 TABLE 3 Ra (.mu.m) Ry (.mu.m) Sm (.mu.m) Presence/
Average Maximum Distance absence of irregularity irregularity
between Number of projections/mm.sup.2 water height height
irregularities Region A1 Region B Region C Average mark Sample 6
0.02 0.24 23 151 151 114 139 .smallcircle. ".smallcircle.": no
water mark generated ".DELTA.": water mark slightly generated "x":
water mark large enough to be visually sufficiently recognizable
generated
TABLE-US-00004 TABLE 4 Haze (%) Transmittance (%) LCD glare Sample
6 0.3 .largecircle. 94.3 .largecircle. .largecircle.
[0055] As shown in Table 3, it is apparent that the sample 6 does
not generate a water mark, and shows good results. That is, it is
apparent that when one related to the sample 6 is used as the film
body 6 of a transparent touch panel that may come into contact with
a surface of a display section, a region where the transparent
touch panel and the display section are in contact with each other
can be made hard to be conspicuous, and as a result, an apparatus
formed by the touch panel and the display device can be made
thinner.
[0056] As shown in Table 4, the sample 6 shows good results for all
of the haze value, the transmittance and the glare. It is apparent
that particularly the sample 6 has a high transmittance of 94.3%,
so that character information and image information displayed by
the display section can be made easier to see.
[0057] In the embodiment described above, the film body 6 with the
projection formation layer 62 formed on one surface of the film
base material 61 is configured to be bonded to the second
transparent planar body 2 with the pressure sensitive adhesive
layer 7 interposed therebetween, but the film body 6 and the
pressure sensitive adhesive layer 7 may be omitted to form the
projection formation layer 62 directly on the other surface of the
transparent substrate 21 in the second transparent planar body 2.
Even in this configuration, the fine projections 62a on the
projection formation layer 62 provided on the transparent substrate
21 and the surface of the display section come into contact with
each other, so that contact between smooth surfaces is prevented,
thus making it possible to effectively prevent generation of a
water mark which has been a problem heretofore.
* * * * *