Information
-
Patent Grant
-
6784948
-
Patent Number
6,784,948
-
Date Filed
Wednesday, July 10, 200222 years ago
-
Date Issued
Tuesday, August 31, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Kim; Robert H.
- Nguyen; Hoan C.
Agents
- Nath & Associates PLLC
- Nath; Gary M.
-
CPC
-
US Classifications
Field of Search
US
- 349 12
- 349 62
- 345 104
- 345 173
- 178 1805
-
International Classifications
- G02F1133
- G02F11335
- G09G336
- G09G500
- G06K1116
-
Abstract
A touch panel has a reduced whole thickness when attached to a display device, increases the accuracy of the positional information, and improves the display quality and durability inexpensively. One of a pair of resistive layers facing each other across insulating dot spacers is laid on a light-transmissible flat plate formed of a PET film rather than a glass plate, and a light conductive plate of a front light unit is integrated with an outer surface of the light-transmissible flat plate. An AR film having a transparent gel layer is disposed between the PET film and the light conductive plate. The transparent gel layer is of a gel material such as silicone rubber and is applied integrally on the AR film, which is formed such that anti-reflection treatment is applied on a surface of a base material of a FET film.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a touch panel for a display device, which is disposed close to a display surface of a display device, such as a liquid crystal display device, and which outputs a predetermined signal corresponding to a position at which an operator presses on a panel surface with a pen or a finger based on information displayed on the display surface.
2. Description of the Related Art
Since, in this type of touch panel, an area corresponding to the display surface of the display device can be used for both displaying and inputting information, the utilization factor of the area is increased, and therefore the touch panel is increasingly demanded for compact information processors and communications equipments, in particular, mobile communications terminals.
FIG. 2
is a sectional view of a conventional touch panel (disclosed in FIG. 2 of Japanese Patent Laid-open No. 2000-187197 A).
As shown in
FIG. 2
, a touch panel
10
A is basically composed of a pair of resistive layers (first and second resistive layers)
12
and
13
disposed opposite to each other across a plurality of insulating dot spacers
11
, and a light-transmissible flat plate, for example, a transparent glass plate
16
, for protecting the second resistive layer
13
which is laid on the glass plate
16
. The touch panel
10
A is disposed close to a display device
30
such that the glass plate
16
faces toward the display surface of the display device
30
.
In this construction, when the outer surface of the first resistive layer
12
is touched to be pressed, a touched portion of the first resistive layer
12
is brought into contact with a portion of the second resistive layer
13
opposite thereto, and a signal corresponding to the contact position (touched position) is generated.
In a practical construction, a transparent layer, for example, a polyethylene terephthalate (hereinafter referred to as PET) film
15
, is laminated on the outer surface of the first resistive layer
12
for protection thereof, so the touching operation is implemented on this PET film
15
.
The first and second resistive layers
12
and
13
are combined at their peripheries by means of a sealing member
14
to be dustproof and waterproof.
A light unit is added to the display device
30
to illuminate the display surface brightly for easier observation. A front light unit
20
to shed light on the front face (display surface) of the display device
30
is often used as the light unit in recent years.
In
FIG. 2
, the touch panel
10
A is attached to the display device
30
having the front light unit
20
described above. The front light unit
20
comprises a light source
21
and a light conductive plate
22
disposed facing the display surface of the display device
30
and adapted to guide light emitted from the light source
21
located at an end of the light conductive plate
22
toward the display surface of the display device
30
. Light made incident on the display surface is reflected thereat or inside of the display device
30
, travels through the light conductive plate
22
and the touch panel
10
A, and exits out (refer to an arrow indicated by a broken line in the figure), whereby an image on the display surface is visualized.
The light conductive plate
22
has an array of prisms, whose respective ridges are parallel to one another, formed on a surface thereof opposite to a surface facing toward the display device
30
, thereby guiding light, which has come into the light conductive plate
22
through its end face, toward the display surface of the display device
30
.
However, in the conventional structure shown in
FIG. 2
, since the touch panel
10
A and the front light unit
20
are constituted discretely from each other, the touch panel
10
A is handled individually and easily subjected to vibration and shock during transportation or assembly. And also the touch panel
10
A is required to be strong enough against vibration and shock even after mounted on the device body. Therefore, the glass plate
16
is increased in thickness so as to reinforce the touch panel
10
A and also to prevent itself from getting damages. However, this gives a disadvantage that the display device
30
has its whole thickness D increased when attached to the touch panel
10
A, and also a problem that since the light conductive plate
22
is brought into direct contact with the glass plate
16
, the light conductive plate
22
may be damaged or broken by the glass plate
16
when vibration or shock is applied to the touch panel
10
A.
Accordingly, a touch panel for a display device (as shown in FIG. 1 of the above-described Japanese Patent Laid-open) was disclosed, where, as shown in
FIG. 3
, a second resistive layer
13
of a touch panel
10
B is in close contact with a surface of a light conductive plate
22
, on which an array of prisms are formed.
In this touch panel, a member (the glass plate
16
in
FIG. 2
) interposed between the light conductive plate
22
and the second resistive layer
13
of the touch panel
10
B is eliminated, and the touch panel
10
B is integrated with a front light unit
20
, and thus the whole thickness D can be reduced when the touch panel and the front light unit are attached to a display device
30
. Further, the glass plate
16
in
FIG. 2
is not present, and this solves the problem that the light conductive plate
22
is damaged or broken by the glass plate
16
when vibration or shock is applied to the touch panel
10
B.
Furthermore, the present inventors proposed countermeasures to overcome the problems of the touch panel disclosed in FIG. 2 of the above-mentioned Japanese Patent Laid-open, and disclosed the details thereof in Japanese Patent Application No. 2000-387641 that was filed on Dec. 20, 2000 and has not been open to the public (therefore, the related invention in the Japanese Patent Application does not constitute prior art under 35 U.S.C. §102). In short, as shown in
FIG. 4
, a layer of a transparent gel material with a low refractive index
17
(
17
b
) is disposed between a glass plate
16
and a light conductive plate
22
, whereby vibration or shock applied to a touch panel
10
C can be absorbed, the glass plate
16
can be made thinner, and visibility of reflected light from a display device
30
can be secured. In addition, as shown in
FIG. 5
, a touch panel
10
D is also disclosed in which a layer of a transparent gel material
17
(
17
c
) and a transparent film
19
made of a material with a low refractive index are disposed between a glass plate
16
and a light conductive plate
22
thereby obtaining a similar advantage.
However, there is a problem described below in the conventional touch panel shown in FIG.
3
.
Since the second resistive layer
13
is in close contact with the surface of the light conductive plate
22
, on which the array of prisms are formed, as described above, the second resistive layer
13
is uneven corresponding to the surface of the array of prisms, and insulating dot spacers
11
are interposed between the uneven second resistive layer
13
and a flat first resistive layer
12
.
Accordingly, it becomes difficult to secure the linearity of resistance value at each position on a touch panel operation surface (the PET film
15
), and errors occur easily in positional information obtained.
In addition, this makes it difficult to dispose individual insulating dot spacers
11
with an even height on the second resistive layer
13
, whereby the PET film
15
constituting the touch panel operation surface tends to undulate deteriorating display quality.
Furthermore, this gives a problem that, with a long term use, protrusions on the array of prisms of the light conductive plate
22
and protrusions on the second resistive layer
13
covering the light conductive plate
22
are liable to damages, resulting in inferior durability.
Still furthermore, in the touch panels shown in
FIGS. 4 and 5
, the transparent gel material
17
(
17
b
) with a low refractive index and the transparent film
19
made of a material with a low refractive index have not been so fully developed as to be adapted for mass-production yet. As a result, to date, the touch panels have not been introduced on the market inexpensively and massively.
In addition, a problem is pointed out that light, which is directed toward the display device
30
, reflected at the display surface or inside thereof, and supposed to pass through the light conductive plate
22
and the touch panel
10
C or
10
D to finally exit out, is reflected at the glass plate
16
, thereby diminishing an amount of light exiting outside, and resultingly deteriorating the visibility of the display surface of the display device
30
.
SUMMARY OF THE INVENTION
The present invention is made to overcome these problems in the aforementioned touch panels, and its object is to provide, inexpensively in a large quantity, a touch panel for display device, which combines the advantages of each of the touch panels shown in
FIGS. 2
to
5
. Specifically, the touch panel is structured such that the whole thickness is not increased substantially when attached to the display device, the light conductive plate is not damaged by the light-transmissible flat plate when subjected to vibration, errors do not come out in obtained positional information, the operation surface does not undulate, the display quality does not deteriorate, and that the durability is excellent.
Another object of the present invention is to effectively inhibit light, which is reflected at the display surface or inside of the display device, from being reflected at the touch panel, thereby preventing the visibility of the display surface from deteriorating.
In order to solve the above problems, a first aspect of the present invention provides a touch panel for a display device, which is structured such that one of a pair of resistive layers disposed so as to face each other and to sandwich a plurality of insulating dot spacers is laid on a light-transmissible flat plate formed of a PET film, which is disposed close to a display device such that the light-transmissible flat plate faces toward a display surface of the display device and that a front light unit comprising a light source and a light conductive plate to guide light emitted from the light source toward the display surface of the display device is interposed between the light-transmissible flat plate and the display device, and in which an outer surface of the other resistive layer of the pair is touched to be pressed thereby generating a signal corresponding to a position touched, wherein a transparent cushioning member composed of a shock-absorbing layer and a base layer for supporting the shock-absorbing layer is disposed between the light conductive plate and the light-transmissible flat plate.
According to a second aspect of the present invention, in the touch panel of the first aspect, the cushioning member is a PET film having a transparent gel layer.
According to a third and fourth aspects of the present invention, in the touch panel of the second aspect, the PET film is an anti-reflection (AR) film and a low reflection (LR) film, respectively.
According to a fifth and sixth aspect of the present invention, in the touch panel of the first aspect, the cushioning member is structured such that a liquid or gel cushioning material is applied on the touch panel and that a surface of the cushioning material is hardened to eliminate stickiness thereby constituting a base layer.
According to a seventh aspect of the present invention, in the touch panel of the first to sixth aspects, the base layer has a thickness of 10 to 500 μm.
According to an eighth aspect of the present invention, in the touch panel of the first to seventh aspects, the shock-absorbing layer has a thickness of 50 to 500 μm.
According to a ninth aspect of the present invention, in the touch panel of the first to eighth aspects, a gap of 10 μm to 1 mm is provided between the cushioning member and the light conductive plate.
According to a tenth aspect of the present invention, in the touch panel of the first to eighth aspects, the cushioning member is in contact with the light conductive plate.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described with reference to the drawings, which are presented for the purpose of illustration only and do not limit the scope of the invention.
FIGS. 1A and 1B
are sectional views showing embodiments of a touch panel for display devices of the present invention.
FIG. 2
is a sectional view showing a conventional touch panel.
FIG. 3
is a sectional view showing a conventional touch panel in which a second resistive layer is disposed in close contact with a surface of a light conductive plate of a front light unit.
FIG. 4
is a sectional view of a related art touch panel in which a glass plate of its constituent elements is made thinner.
FIG. 5
is a sectional view showing another related art touch panel in which a glass plate of its constituent elements is made thinner.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be explained with reference to the drawings. Elements equivalent to those of the conventional touch panel are given the same reference numerals, and detailed explanations thereof are omitted.
Referring to
FIG. 1A
or
1
B, a touch panel
10
according to one embodiment of the present invention is basically composed of a pair of resistive layers (first and second resistive layers
12
and
13
), for example ITO films, disposed to face each other, with a plurality of insulating dot spacers
11
interposed therebetween, and a light-transmissible flat plate (hereinafter referred to as PET film, which is used in the present invention)
16
a
for protecting the second resistive layer
13
. The second resistive layer
13
is formed on the PET film
16
a
. The touch panel
10
is disposed close to a display device
30
such that the PET film
16
a
is directed toward a display surface of the display device
30
. The light-transmissible flat plate is not limited to PET film, and may be of any materials having light-transmissibility and flexibility.
Furthermore, an AR film
24
is disposed under the PET film
16
a
, that is, toward the display device
30
, and a transparent gel layer
23
is sandwiched therebetween. The transparent gel layer
23
is of a transparent gel substance, such as silicone resin, and integrated with the AR film
24
such that the transparent gel layer
23
is coated on the AR film
24
. Furthermore, in this embodiment, the AR film
24
is formed such that an anti-reflection treatment is applied on a surface of a PET film substrate. The transparent gel layer
23
functions as a shock absorber and the AR film
24
braces the transparent gel layer
23
. The transparent gel layer
23
and the AR film constitute a cushioning member that is discrete from a light conductive plate
22
, which gives a favorable effect with regard to refractive index to be described hereinlater.
As the transparent gel layer
23
is sticky, the AR film
24
is disposed so as to have close contact with the PET film
16
a
via the transparent gel layer
23
, thereby making the PET film
16
a
and the AR film
24
dustproof and waterproof.
In such a configuration, when the outer surface of the first resistive layer
12
is touched to be pressed, the touched portion comes into contact with a portion of the second resistive layer
13
opposite thereto, and a signal corresponding to the contacted portion is generated.
Actually, a transparent layer, a PET film
15
in this case, for protecting the resistive layer
12
is laminated on the outer surface of the first resistive layer
12
. Accordingly, the touching operation is implemented on this PET film
15
.
The first and second resistive layers
12
and
13
are combined at their peripheries by a sealing member
14
to be dustproof and waterproof.
In addition, in the present invention, the light conductive plate
22
, which, together with a light source
21
, constitutes a front light unit
20
, and guides light emitted from the light source
21
toward the display surface of the display device
30
, is integrally attached on the outer surface of the AR film
24
.
The touch panel
10
and the front light unit
20
are integrated, as shown in
FIG. 1A
, by means of a binding material
18
, such as a double sided tape or resin. The binding material
18
combines a housing frame
25
for holding together the light conductive plate
22
, the light source
21
and so on, with the AR film
24
at their peripheries. This binding material
18
also plays the role of waterproofing and dustproofing the space between the AR film
24
and the light conductive plate
22
.
Accordingly, the touch panel
10
according to this embodiment of the present invention is structured such that the PET film
15
, the first and second resistive layers
12
and
13
which are disposed to face each other across the plurality of insulating dot spacers
11
, the PET film
16
a
(the light-transmissible flat plate), the transparent gel layer
23
, and the AR film
24
are integrated in this order.
An array of prisms whose respective ridges are parallel to one another are formed on a surface of the light conductive plate
22
opposite to a surface facing toward the display device
30
so that light emitted from the light source
21
can travel toward the display surface of the display device
30
.
In order to direct (reflect) the light emitted by the light source
21
toward the display surface of the display device
30
by means of the light conductive plate
22
, the relationship: n1>n2 must be satisfied, where n1 is the refractive index of the light conductive plate
22
and n2 is the refractive index of a medium in contact with the prisms.
In this embodiment, the light conductive plate
22
is formed of, for example a transparent acrylic resin and has a refractive index (n1) of about 1.5, and the medium is air just like in the conventional touch panel shown in FIG.
2
and has a refractive index (n2) of 1. Thus, the above-mentioned relationship (n1>n2) is satisfied.
Accordingly, light emitted from the light source
21
passes through the light conductive plate
22
, and is reflected at the array of prisms toward the display surface of the display device
30
, and thereby the display surface is illuminated. Light having reached the display device
30
is reflected at its display surface or inside, passes through the light conductive plate
22
, a layer of air present between the light conductive plate
22
and the PET film
24
, and the touch panel
10
, and exits out (refer to an arrow indicated by a broken line in the figure). Thus, an image on the display surface is visualized.
Various coatings are optionally applied on the PET film
16
a
or the AR film
24
when required to improve their properties. For example, hard coating may be applied on the AR film
24
, thereby providing the surface of the AR film
24
with a certain degree of hardness for scratchproofing.
According to the touch panel described above, the light-transmissible flat plate is formed of the PET film
16
a
which is flexible, excellent in vibration and shock resistance, and accepts various coatings. As a result, the light-transmissible flat plate can be made thinner than the conventional one (glass plate). In addition, due to the mechanical property of the transparent gel layer
23
and the AR film
24
which are disposed between the light conductive plate
22
and the PET film
16
a
, vibration or shock applied to the touch panel
10
is transmitted with attenuation to the light conductive plate
22
.
The AR film for bracing the transparent gel layer
23
, when set to have a thickness of 10 to 500 μm, preferably 10 to 100 μm, obtains necessary flexibility, and works to disperse force generated when the touch panel
10
hits against the light conductive plate
22
, thereby effectively preventing damages to the touch panel
10
and the light conductive plate
22
.
It is found that the transparent gel layer
23
, when set to have a thickness of about 50 to 500 μm, preferably 50 to 200 μm, depending on the characteristics thereof, can provide significant cushioning effect with little influence on the whole thickness of the touch panel.
Furthermore, according to the related art touch panel (FIG.
4
), a transparent gel substance
17
(
17
b
) is in direct contact with a light conductive plate
22
. As a result, it is necessary to use a gel material having a low refractive index. However, according to the present invention, the transparent gel layer
23
is disposed between the PET film
16
a
and the AR film
24
, and therefore does not come into contact with the light conductive plate
22
, so the refractive index of the transparent gel substance does not constitute restriction when selecting the kind of gel substance.
In
FIG. 1A
, the AR film
24
is in contact with ridges of the prisms formed on the light conductive plate
22
. This can minimize the whole thickness D when the touch panel
10
is attached to the front light unit
20
. It may alternatively be that the AR film
24
is in contact partly with the ridges of the prisms (not illustrated). In another example shown in
FIG. 1B
, an AR film
24
is apart from ridges of prisms formed on a light conductive plate
22
. When a gap between the AR film
24
and the light conductive plate
22
is set to 10 μm to 1 mm, damages to the touch panel
10
and the light conductive plate
22
can be surely prevented, thereby achieving a longer life of the product.
Furthermore, the AR film
24
, which is disposed integrally with the transparent gel layer
23
between the light conductive plate
22
and the PET film
16
a
, eliminates effectively the problem that light, which is reflected toward the display device
30
, made incident thereon, reflected at the display surface or inside thereof, and which passes through the light conductive plate
22
and the touch panel
10
, is reflected at the PET film
16
a
failing to exit out the touch panel
10
. As a result, deterioration in visibility of the display surface of the display device
30
, which is caused due to reduced amount of light exiting out, can be prevented.
When such an anti-reflection function is performed by other means than the AR film
24
, a plain PET film having a surface without anti-reflection treatment may replace the AR film
24
. Furthermore, the AR film
24
may be replaced by an LR (Low Reflection) film which is relatively inexpensive and exhibits anti-reflection characteristics.
The transparent gel layer
23
and the AR film integrated therewith may be replaced by a structure formed such that a liquid or gel cushioning material is coated on the surface of the PET film
16
a
facing toward the display device
30
and that the surface of the coating of the liquid or gel cushioning material is hardened thereby eliminating its stickiness. With this structure, vibration or shock applied to the touch panel
10
accidentally or by touching pressure during touching operation is transmitted with attenuation to the light conductive plate
22
due to mechanical properties of the liquid or gel cushioning material. And the hardened surface of the coating of the liquid or gel cushioning material works to brace a portion thereof which remains intact without hardening to work as a shock-absorbing layer. This alternative structure corresponds to the structure integrally constituted by the transparent gel layer
23
and the AR film
24
as shown in
FIGS. 1A and 1B
, and therefore can be handled safely without difficulty.
The touch panel of the present invention, configured as described above, realizes the following effects. Firstly, the touch panel of the first aspect is configured basically similar to the conventional touch panel shown in
FIG. 2
where one of a pair of resistive layers disposed so as to face each other across insulating dot spacers is laid on the light-transmissible flat plate, and therefore retains the advantages of the conventional touch panel in FIG.
2
and at the same time overcomes the problems associated with another conventional touch panel in FIG.
3
. Specifically, since the resistive layer that is pressed by the insulating dot spacers is formed on the light-transmissible flat plate (PET film), the linearity of resistance values at individual positions on the operational surface of the touch panel can be sufficiently secured, and the accuracy of the positional information to be obtained is not deteriorated.
In addition, since the individual insulating dot spacers can be easily arranged with an even height on the second resistive layer, the transparent film (PET film or the like) as the operational surface of the touch panel does not undulate, and the display quality is not deteriorated.
Furthermore, since the insulating dot spacers are pressed against the inner surface of the resistive layer formed on the light-transmissible flat plate, that is, against a flat surface, the light conductive plate and the second resistive layer do not suffer damages thereby improving the durability.
In the present invention, since the light conductive plate of the front light unit is attached integrally with the outer surface of the light-transmissible flat plate formed of a PET film, the touch panel does not require such a large mechanical strength against vibration and shock in transportation as conventionally required. In addition, the PET film itself is flexible, excellent in vibration and shock resistance, and accepts various kinds of coatings.
As a result, the thickness of the PET film as the light-transmissible flat plate can be reduced to about one half to one quarter of about 0.4 mm which is the thickness of the conventional glass plate. Thus, when the touch panel and the front light unit are attached to the display device, the whole thickness D can be made smaller than conventionally, whereby the problems with the conventional touch panel shown in
FIG. 2
can be eliminated. In addition, the PET film is not damaged by the light conductive plate.
Furthermore, since the light conductive plate is not so hard as the glass plate, and since the PET film is lighter than the glass plate, the light conductive plate is no longer damaged or destroyed when the touch panel is subjected to vibration or shock.
In addition, since the medium in contact with the array of prisms on the light conductive plate is air as in the conventional touch panel shown in
FIG. 2
so as to satisfy the relationship: n1>n2 where n1 is the refractive index of the light conductive plate and n2 is the refractive index of the medium, it is not necessary to use transparent gel materials with a low refractive index or films formed of a transparent material with a low refractive index, which are used in the related art touch panels shown in FIG.
4
and FIG.
5
. Accordingly, the touch panel can be supplied at low costs and in large quantities.
Further, due to the mechanical properties of the shock-absorbing layer of the transparent cushioning member interposed between the light conductive plate and the light-transmissible flat plate and being discrete from the light conductive plate, vibration and shock applied accidentally to the touch panel during touching operation is transmitted with attenuation to the light conductive plate. Therefore, the touch panel is free from damages to the light conductive plate, and therefore is excellent in durability and can be fabricated at low costs and in large quantities.
According to the second aspect of the present invention, due to the mechanical properties of the transparent gel layer and the PET film which are interposed between the light conductive plate and the light-transmissible flat plate, vibration or shock applied to the touch panel is transmitted with attenuation to the light conductive plate. Thus, the touch panel has the advantages of each of the touch panels shown in
FIGS. 2
to
5
. Specifically, the touch panel does not have its whole thickness increased substantially when attached to a display device, and the light conductive plate is not damaged by the light-transmissible flat plate when the touch panel is subjected to vibration or shock, errors in positional information are not caused, the touching operation surface does not undulate, and the display quality does not deteriorate. Further, the touch panel having the above advantages can be fabricated at low costs and in large quantities.
According to the third or fourth aspect of the present invention, it is prevented by means of the AR film or the LR film interposed between the light conductive plate and the PET film, that light, which is directed toward the display device, reflected at the display surface or inside thereof, and passes through the light conductive plate and the touch panel to finally exit out, is reflected by the touch panel at the PET film side failing to exit out. As a result, deterioration in visibility of the display surface of the display device due to a reduced amount of light exiting out can be suppressed.
According to the fifth or sixth aspect of the present invention, due to the mechanical properties of the liquid or gel shock-absorbing material applied on the surface of the touch panel, vibration and shock applied to the touch panel is transmitted with attenuation to the light conductive plate. Therefore, deterioration in performance due to damages to the light conductive plate can be prevented. And the surface of the shock-absorbing material is hardened so as to take away stickiness thereby constituting a base layer, and therefore can be handled just like the PET film having a transparent gel layer.
According to the seventh aspect of the present invention, the base layer has necessary flexibility, and can disperse the stress generated when the touch panel comes into contact with the light conductive plate, thereby effectively preventing damages to the touch panel. Thus, the touch panel can be prevented from deteriorating in performance due to damages to the light conductive plate.
According to the eighth aspect of the present invention, the shock-absorbing layer can provide significant cushioning effect with little influence on the whole thickness of the touch panel. Therefore, the touch panel can be produced with a smaller size and a lower profile and without deterioration in performance due to damages to the light conductive member.
According to the ninth aspect of the present invention, the gap provided between the cushioning member and the light conductive plate can surely prevent damages to the touch panel and the light conductive plate, thereby preventing deterioration in performance due to damages to the light conductive plate.
According to the tenth aspect of the present invention, the touch panel can minimize the whole thickness when equipped with the front light unit, and provide significant cushioning effect as well. Therefore, the touch panel can be produced with a smaller size and a lower profile, and at the same time prevent deterioration in performance due to damages to the light conductive plate.
It is to be understood that the invention is not restricted to the particular embodiments set forth herein as illustrated, but embraces all such modified forms thereof that come within the scope of the following claims.
Claims
- 1. A touch panel for a display device: which is structured such that one of a pair of resistive layers disposed so as to face each other and to sandwich a plurality of insulating dot spacers is laid on a light-transmissible flat plate formed of a polyethylene terephthalate film; which is disposed close to a display device such that the light-transmissible flat plate faces toward a display surface of the display device and that a front light unit comprising a light source and a light conductive plate to guide light emitted from the light source toward the display surface of the display device is interposed between the light-transmissible flat plate and the display device; and in which an outer surface of the other resistive layer of the pair is touched to be pressed thereby generating a signal corresponding to a position touched,wherein a transparent cushioning member composed of a shock-absorbing layer and a base layer for bracing the shock-absorbing layer is disposed between the light conductive plate and the light-transmissible flat plate.
- 2. A touch panel according to claim 1, wherein the cushioning member is a polyethylene terephthalate film having a transparent gel layer.
- 3. A touch panel according to claim 2, wherein the polyethylene terephthalate film is an anti-reflection film.
- 4. A touch panel according to claim 2, wherein the polyethylene terephthalate film is a low reflection film.
- 5. A touch panel according to claim 1, wherein the cushioning member is structured such that a liquid cushioning material is applied on the touch panel and that a surface of the cushioning material is hardened so as to eliminate stickiness thereby constituting the base layer.
- 6. A touch panel according to claim 1, wherein the cushioning member is structured such that a gel cushioning material is applied on the touch panel and that a surface of the cushioning material is hardened so as to eliminate stickiness thereby constituting the base layer.
- 7. A touch panel according to claim 1, wherein the base layer has a thickness of 10 to 500 μm.
- 8. A touch panel according to claim 1, wherein the shock-absorbing layer has a thickness of 50 to 500 μm.
- 9. A touch panel according to claim 1, wherein a gap of 10 μm to 1 mm is provided between the cushioning member and the light conductive plate.
- 10. A touch panel according to claim 1, wherein the cushioning member is in contact with the light conductive plate.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2001-213731 |
Jul 2001 |
JP |
|
2002-014420 |
Jan 2002 |
JP |
|
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Date |
Kind |
5907375 |
Nishikawa et al. |
May 1999 |
A |
6130658 |
Yamamoto et al. |
Oct 2000 |
A |
6456279 |
Kubo et al. |
Sep 2002 |
B1 |
6639163 |
Fukui et al. |
Oct 2003 |
B2 |
Foreign Referenced Citations (1)
Number |
Date |
Country |
2000-187197 |
Jul 2000 |
JP |