JP2002259054A - Touch panel and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch panel which can satisfactorily maintain operability, regardless of the change of an environment. SOLUTION: In the touch panel 100, two substrates 104 and 130, where resistance films 111 and 131 are formed on its surfaces, are arranged by leaving a prescribed interval so that the respective resistance films 111 and 131 face each other. A polarizing plate 102 is laminated on the outer side of the substrate 104 or 130. In the polarizing plate 102, an area shrinkage factor, after it has been left standing for 24 hours in the environment of 80 deg.C is <=0.3%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch panel and a display device having the same.

[0002]

2. Description of the Related Art As a conventional touch panel, there is widely known a resistive touch panel in which two substrates each having a resistive film formed on one surface thereof are stacked via a spacer so that each resistive film faces each other. For example, it is used by being arranged on a display screen. Recently, it is often used outdoors, such as in car navigation systems and notebook computers.
In order to prevent the visibility of the display from being deteriorated due to the reflection of external light, a material in which an antiglare property is imparted by attaching a polarizing plate to the outer surface of the upper substrate is often used.

[0003]

However, since the conventional polarizing plate expands significantly at high temperatures, when the linear expansion coefficient of the polarizing plate is much larger than that of the lower substrate (for example, the lower substrate is made of glass). In such a case, a difference in the amount of expansion between the lower substrate and the lower substrate is caused. As a result, the upper substrate gradually curves and expands together with the polarizing plate. As a result, not only the appearance of the touch panel deteriorates, but also the operability of the touch panel deteriorates because the distance between the touch panel and the lower substrate increases.

For this reason, a method in which a surface film having a small linear expansion coefficient is attached to the outer surface side of the polarizing plate to suppress the swelling of the upper substrate at a high temperature can be considered, but the conventional polarizing plate has a long length at a high temperature. Since the area shrinkage after being left for a long time is large, the area shrinkage of the polarizing plate may be larger than that of the resin film on the outer surface of the polarizing plate. was there.

[0005] In particular, recently, the touch panel tends to increase in size as the size of the liquid crystal display panel increases, so that the above-mentioned problem associated with the swelling has become more prominent.

The present invention has been made to solve such a problem, and has as its object to provide a touch panel capable of maintaining good operability irrespective of environmental changes. An object is to provide a display device having a touch panel.

[0007]

The object of the present invention is to dispose two substrates, each having a resistive film formed on the surface thereof, at a predetermined interval so that the resistive films face each other, and at least one of the resistive films is arranged. A touch panel in which a polarizing plate is laminated on the outer surface side of a substrate, wherein the polarizing plate has an area shrinkage of 0.3% or less after being left in an environment of 80 ° C. for 24 hours. Is done. Here, “80 ° C
"Area shrinkage rate after standing for 24 hours in an environment" means that an object (polarizing plate) is vertically and horizontally = 100 mm × 100 m
m and cut in a dry atmosphere at 80 ° C.
After standing for a period of time, return to room temperature and measure the vertical length M
(Mm) and the lateral length T (mm). The area shrinkage thus obtained is hereinafter referred to as “area shrinkage after leaving at high temperature”.

[0008]

(Equation 1)

In this touch panel, a surface film having a smaller linear expansion coefficient than the substrate on which the polarizing plate is laminated is preferably laminated on the opposite side of the substrate with respect to the polarizing plate.

[0010] The polarizing plate may include a planar polarizer and a protective film attached to at least one surface of the polarizer.
The area shrinkage after leaving for 24 hours in a 0 ° C. environment is 0.3
% Is preferable. In addition, the area shrinkage of the protective film is a value similarly obtained by using the target object as the protective film in the definition of the area shrinkage of the polarizing plate described above.

This protective film is preferably bonded to at least the surface of the polarizer opposite to the substrate, and preferably has an optical in-plane retardation of 3 nm or less. Here, the optical in-plane retardation represents the birefringence, and is a value obtained by multiplying the difference between the refractive index in the X direction and the refractive index in the Y direction by the thickness (nm).

Further, it is preferable that the operation surface of the touch panel has a swelling of 1 mm or less after being left in an environment of 70 ° C. or an environment of 60% and 90% RH for 240 hours. Here, the swelling of the operation surface refers to the height of the operation surface of the touch panel, that is, the outermost surface of the two substrates on the side where the polarizing plate is provided, up to the most protruding position with respect to the peripheral edge.

Further, the above object of the present invention is achieved by a display device comprising the above touch panel and display means having a display surface, wherein the touch panel is arranged in front of the display surface.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described. FIG. 1 is a perspective view showing the entire configuration of the touch panel, and FIG. 2 shows a state in which the touch panel is disassembled.

As shown in FIG.
Includes a planar laminate 110 and a lower substrate 130, a spacer 140 is interposed between the planar laminate 110 and the lower substrate 130, and an insertion portion 142 of the connector 120 is provided. Is formed.

As shown in FIG. 2, the planar laminate 110 is
A resistive film 111 is formed on the lower surface (the surface facing the lower substrate 130).
Is provided. The resistance film 111 is made of, for example, ITO (indium-tin oxide) and is formed by sputtering. In two places on the side of the resistance film 111,
A pair of electrodes 112 are provided so as to face each other. The electrodes 112, 112 are connected to terminals 114, 114 provided on the insertion portion 142 via a wiring pattern 113, respectively.
22 can be conducted.

The lower substrate 130 is formed of the planar laminate 11.
0, a resistive film 131 made of ITO is provided on the upper surface (the surface facing the planar laminate 110).
A pair of electrodes 132, 132 are provided facing each other at two locations on one side. As the lower substrate 130, thin glass having a thickness of about 0.5 to 2 mm is preferable.

The facing direction of the electrodes 132, 132 is orthogonal to the facing direction of the electrodes 112, 112 in the planar laminate 110, and the insertion portion 142 is provided via a wiring pattern 133.
Are connected to the terminals 134 provided on the connector 120, respectively, and can be electrically connected to the lower terminal 123 of the connector 120.

The spacer 140 is a frame-shaped member made of a polyethylene terephthalate (PET) film or the like, and is adhered to the peripheral portions of the sheet laminate 110 and the lower substrate 130 with an adhesive applied to the front and back surfaces. A predetermined interval (for example, about 100 μm) is maintained. The insertion portion 142 of the connector 120 is formed by cutting off a part of the spacer 140. The spacer 1
40 is cut away at several places other than the insertion part 142, and these function as a ventilation part 141 when the internal pressure rises.

On the upper surface of the lower substrate 130, dot-shaped insulating spacers 160 are arranged substantially uniformly. The dot-shaped insulating spacer 160 is formed at a lower height than the spacer 140.

FIG. 3 schematically shows a cross section of the touch panel 100. As shown in FIG.
10 is a surface film 10 in order from the top side (front side).
1, a polarizing plate 102, a λ / 4 retardation plate 103, and an upper substrate 104 are laminated, and these are bonded with an adhesive such as an acrylic resin.

The surface film 101 is, for example, a PET film and has a thickness of 50 to 2 from the viewpoint of strength and operability.
Preferably, the thickness is about 50 μm. λ / 4 phase difference plate 1
03 is formed using, for example, a polycarbonate (PC) film as a material. The upper substrate 104 is made of a light isotropic material having no polarization for all incident light, and examples thereof include a norbornene-based transparent thermoplastic resin having an aliphatic cyclic structure.

The surface film 101 is not particularly limited, but preferably has a smaller linear expansion coefficient than the upper substrate 104 in order to reliably prevent the touch panel from swelling at high temperatures. For example, a polyolefin resin film (linear expansion coefficient: 6.2 × 10 ⁻⁵ cm / cm)
/ ° C), the surface film 101 made of a PET film (linear expansion coefficient 1.5 × 10 ⁻⁵ cm / cm / ° C) can be exemplified.

The polarizing plate 102 has a structure in which both surfaces of a polarizer 102a are sandwiched between protective films 102b and 102b, and the above-mentioned area shrinkage after leaving at high temperature is 0.3% or less.

The polarizer 102a and the protective film 102b for obtaining the polarizing plate 102 having a small area shrinkage after leaving at such a high temperature are as follows.

The polarizer 102a is obtained by orienting a film made of polyvinyl alcohol (PVA) or a derivative thereof by uniaxial stretching, adsorbing iodine, performing a boric acid aqueous treatment, and then drying under tension. Alternatively, it can also be obtained by immersing a film made of PVA or a derivative thereof in an aqueous solution of iodine to adsorb iodine, orienting the film by uniaxial stretching in boric acid water, and drying it under tension. In each of the above production methods, an azo, anthraquinone, or tetrazine dichroic dye may be used instead of using iodine. In addition, from the viewpoint of reducing the area shrinkage after being left at a high temperature, it is preferable to perform a sufficient heat treatment in the uniaxial stretching step, and to lengthen the treatment time in the boric acid water treatment step to improve the degree of crosslinking. It is preferable to raise the temperature to the extent that the polarization performance is not affected in the tension drying step.

The thickness of the polarizer 102a is not particularly limited, but is usually about 10 to 40 μm. In addition, polarizer 1
The degree of polarization of 02a is preferably 95.0% or more, more preferably 99.0% or more, and still more preferably 99.7%.
That is all. Here, the degree of polarization is obtained by the following method. That is, two polarizing plates are superimposed so that the polarization axes are in the same direction, and the wavelength range is 400 to 7 using a spectrophotometer.
The average value T1 of the light transmittance obtained by continuously measuring 00 nm was obtained, and two polarizing plates were superimposed so that the polarization axes were orthogonal to each other. The average value of the light transmittance measured in the same manner was defined as T2. Then, from these T1 and T2, the degree of polarization is calculated by the following equation.

[0028]

(Equation 2)

Examples of the protective film 102b include cyclic olefin, polyester, polyolefin, cellulose acetate, polycarbonate, polyvinyl alcohol, polyethersulfone, polyarylate, polyimide, and polyamideimide. And a resin film of polyamide or the like.
In order to maximize the performance of the polarizer 102a, among them, the film appearance is excellent, the surface smoothness is good, the optical in-plane retardation is small cellulose acetate-based or cyclic olefin-based resin film. Preferably, there is.

As the cellulose acetate resin, for example,
Examples include a triacetyl cellulose (TAC) film and a cellulose diacetate film. Examples of the cyclic olefin resin include a polymer obtained by hydrogenating a ring-opening (co) polymer of a cyclic olefin, an addition (co) polymer of a cyclic olefin, and an α-olefin such as ethylene and propylene. Or a graft-modified product obtained by modifying these (co) polymers with an unsaturated carboxylic acid or a derivative thereof. Examples of the cyclic olefin include norbornene, tetracyclododecene, and derivatives thereof (for example, those having a carboxyl group or an ester group).

The thickness of the protective film 102b is
From the viewpoint of reducing the area shrinkage ratio after leaving No. 02 at high temperature, the thickness is preferably 20 μm or more, but is not particularly limited. In consideration of handling properties, the thickness of the protective film 102b is preferably 100 μm or less. This protective film 102b preferably has an optical in-plane retardation determined by the above definition of 30 nm or less, more preferably 15 nm or less, and more preferably 3 nm or less so as not to impair the polarizing function. More preferred. In the present embodiment, the measurement of the optical in-plane retardation was performed using an automatic birefringence meter (“KOBRA” manufactured by Oji Scientific Instruments).

In order to obtain the protective film 102b having a very small optical in-plane retardation of 3 nm or less, it is necessary to correct the distortion of the internal molecular chains of the protective film by an appropriate method. For example, a method of heating the film with a minus draw before winding the film or a method of leaving a loosely wound roll-shaped film in a heating chamber can be exemplified. In the case of the solution casting method, it is preferable to reduce the residual solvent, and one method is to lengthen the drying oven. Incidentally, the addition of a plasticizer such as dioctyl adipate, dioctyl phthalate, isodecyl adipate to the resin component tends to increase the photoelastic coefficient,
Therefore, the optical in-plane retardation tends to increase, which is not preferable.

In order to obtain a polarizing plate 102 having an area shrinkage of 0.3% or less after being left at a high temperature, at least one of the protective films 102b, 102b adhered to the front and back surfaces of the polarizer 102a must be left at a high temperature. It is preferable that the area shrinkage rate after that satisfies the condition of 0.3% or less.
It is preferable that the protective film 102b on the upper side of 02a (the surface film 101 side) satisfies such a condition.

In order to obtain such a protective film 102b having a small area shrinkage after being left at a high temperature, the heat deformation temperature is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, and more preferably 120 ° C. or higher. Is more preferable. Here, the heat distortion temperature means ASTM D648.
Is a value measured under a load of 182.2 N (18.6 kgf) according to

On the other hand, if the amount of the residual volatile components is too large, the volatile components are removed during heating, causing volume shrinkage and an increase in the area shrinkage.
Or less, more preferably 6% or less, and even more preferably 4% or less. Here, the residual volatile component is 160 ° C. with respect to the weight at normal temperature before heating.
X It is a value calculated from the rate of weight change after 4 hours.

The water absorption of the protective film 102b is preferably 3% or less, more preferably 1% or less, and more preferably 0.8% or less in order to suppress an increase in the area shrinkage during humidification. Is more preferable. Here, the water absorption means 23 ° C. in accordance with ASTM D570.
The sample was left standing in water for 1 week.

Protective film 102b on polarizer 102a
Can be performed using an adhesive capable of obtaining an appropriate adhesive strength, such as an ultraviolet-curable adhesive, a solvent-based adhesive, a water-based adhesive, and a thermosetting adhesive, and other known adhesives ( (Adhesion) means.

The touch panel 10 configured as described above
According to 0, since the area shrinkage of the polarizing plate 102 after being left at a high temperature is very low at 0.3% or less, there is no possibility that the polarizing plate 102 shrinks more than the surface film 101, and the swelling of the planar laminate 110 does not occur. Can be reliably prevented. Therefore, the operability of the touch panel 100 can be favorably maintained even after being left at a high temperature.

Further, by making the linear expansion coefficient of the surface film 101 laminated on the upper surface side of the polarizing plate 102 smaller than that of the upper substrate 104, the upper substrate 104 expands more than the surface film 101 at a high temperature. Therefore, the planar laminate 110 is in a concave state. As a result,
Even in a high temperature state, the operability of the touch panel 100 can be improved. Note that a malfunction caused by the proximity of the planar laminate 110 and the lower substrate 130 is as follows.
This can be prevented by the dot-shaped insulating spacer 160.

As shown in FIG. 3, the touch panel 100 is provided on the upper surface (display surface) of a liquid layer display plate 200 as a display means. The liquid crystal display panel 200 includes an upper polarizer 202 and a lower polarizer 20 on the front and back surfaces of a liquid crystal cell 201.
3 is provided, and a λ / 4 retardation plate 204 is attached to the upper surface of the upper polarizing plate 202 (the touch panel 100 side). The λ / 4 retardation plate 204 may be attached to the lower surface (the lower substrate 130) of the touch panel 100 instead of being attached to the upper polarizing plate 202.

As described above, one embodiment of the present invention has been described in detail.
Various modifications are possible as long as it is 3% or less. For example, the protective film 102b of the polarizing plate 102 may include a hard coat layer, a barrier layer, and a polarizer 102a as necessary.
And an adhesive layer, an adhesive layer, and the like.

Further, λ / 4 forming the planar laminate 110
The retardation plate 103 can be configured without such a structure, and even in this case, a certain degree of antiglare property can be obtained.

In the present embodiment, the polarizer 10
2a, the protective film 102b is stuck on both upper and lower surfaces, but the protective film 10b is only attached to one side of the polarizer 102a.
2b may be attached. For example, polarizer 1
The protective film 102b is not provided on the lower surface side of the optical film 02a, and the function of this protective film is changed to the λ / 4 retardation plate 103 (λ /
If the four-phase plate 103 is not provided, the upper substrate 104)
It is also possible to use

The liquid crystal display panel 200 is not limited to the above embodiment. For example, when the λ / 4 retardation plate 103 of the touch panel 100 is not provided, the liquid crystal display panel 2
Regarding 00, it is preferable to adopt a configuration in which the λ / 4 retardation plate 204 is not provided. Further, instead of using the liquid crystal display panel 200, various display means such as a cathode ray tube (CRT), electroluminescence (EL), and plasma (PDP) can be used. Can be obtained.

[0045]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples.

Example 1 A polarizer was obtained by bonding a protective film made of a cyclic olefin film (thickness: 50 μm) to both sides of a polarizer made of a PVA film (thickness: 20 μm) on which iodine was adsorbed. . The area shrinkage of the cyclic olefin film after high temperature storage is 0.05%
The area shrinkage ratio of the thus obtained polarizing plate after being left at a high temperature was 0.10%.

Then, as shown in FIG.
A PET film (thickness: 75 μm) as the surface film 101 is attached to the upper surface of the substrate 02 with an acrylic adhesive, and the panel size is 275 × 200 mm (1 mm).
2.1 inches). Upper substrate 1
04 is an arton film (thickness 18) manufactured by JSR Corporation.
8 μm), and the lower substrate 130 was made of ITO glass having a thickness of 0.7 mm. In FIG. 4, the same components as those in FIG. 3 are denoted by the same reference numerals.

Next, the touch panel was subjected to a high-temperature storage test. That is, 90 ° C in a 70 ° C environment and 60 ° C
After leaving for 240 hours in each environment of% RH, the temperature was returned to room temperature, and the swelling of the operation surface (surface film) after 24 hours was measured. As a result, there was no swelling under any environment and the operability was good.

Example 2 A touch panel was manufactured in the same manner as in Example 1, except that the protective film on the lower surface side (upper substrate side) of the polarizer was a TAC film widely used as a conventional protective film. did. This TAC film had an area shrinkage of 0.35% after being left at a high temperature, and had a large shrinkage after being left at a high temperature. However, the area shrinkage of the protective film on the upper surface side (surface film side) of the polarizer was large. However, since it was extremely small as shown in Example 1, the polarizing plate had a small area shrinkage of 0.15% after being left at a high temperature, which was a small value. As a result, in the above-described high-temperature storage test, no swelling of the operation surface was observed.

Example 3 A touch panel was manufactured in the same manner as in Example 2 except that the PET film of the surface film was changed to a low shrinkage PET film. The area shrinkage after the polarizing plate was left at a high temperature was 0.15%, which was the same as in Example 2, and was not affected by the difference in the surface film. As a result, there was no swelling of the operation surface in the high-temperature storage test described above.

Example 4 A touch panel was manufactured in the same manner as in Example 3 except that the pressure-sensitive adhesive used for attaching the surface film to the polarizing plate was a pressure-sensitive adhesive. The area shrinkage after the polarizing plate was left at a high temperature was 0.15%, which was the same as in Example 3, and was not affected by the difference due to the adhesive. As a result, there was no swelling of the operation surface in the high-temperature storage test described above.

Example 5 A polarizing plate was formed without providing a protective film on the lower surface side (upper substrate side) of the polarizer.
A touch panel was manufactured in the same manner as in Example 4. The area shrinkage of the polarizing plate after leaving at high temperature was 0.20%, and in the above-mentioned high temperature leaving test, there was no swelling of the operation surface.

(Comparative Example 1) A touch panel was manufactured in the same manner as in Example 1 except that both protective films to be attached to both surfaces of the polarizer were TAC films. This TAC
As described above, the area shrinkage rate of the film after being left at a high temperature was 0.35%, and thus the polarizing plate had an area shrinkage rate of 0.35% after being left at a high temperature, and showed a large shrinkage.
As a result, in the high-temperature storage test described above, in both the 70 ° C. environment and the 60 ° C. × 90% RH environment, the central portion swelled by 2.0 mm with respect to the peripheral portion of the surface film,
Operability deteriorated.

[0054]

As is apparent from the above description, according to the present invention, two substrates having a resistive film formed on one surface are arranged at a predetermined interval so that the resistive films face each other. In a touch panel in which a polarizing plate is laminated on the outer surface side of at least one of the substrates, the area shrinkage of the polarizing plate after being left for 24 hours in an environment of 80 ° C. is 0.3% or less. Is suppressed. Therefore, regardless of the lamination state of the polarizing plates, the swelling of the operation surface is prevented, and the operability of the touch panel can be favorably maintained.

By laminating a surface film having a smaller coefficient of linear expansion than the substrate on which the polarizing plate is laminated, on the opposite side to the substrate with respect to the polarizing plate, swelling of the operation surface at high temperatures is reliably prevented. Operability can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a touch panel according to an embodiment of the present invention.

FIG. 2 is a diagram showing a disassembled state of the touch panel.

FIG. 3 is a cross-sectional view schematically showing a laminated structure of the touch panel.

FIG. 4 is a cross-sectional view schematically illustrating a laminated structure of a touch panel according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 touch panel 101 surface film 102 polarizing plate 103 λ / 4 retardation plate 104 upper substrate 110 planar laminate 111 resistive film 130 lower substrate 131 resistive film 140 spacer 160 dot-shaped insulating spacer 200 liquid crystal display panel

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H089 HA18 QA06 TA15 2H091 FA08X FA11X FD06 FD15 GA11 GA16 LA04 5B068 AA04 AA32 BB06 BC07 5B087 AA02 AC09 CC01 CC05 CC14

Claims (7)

[Claims] 1. A touch panel in which two substrates each having a resistive film formed on the surface are arranged at a predetermined interval so that the resistive films face each other, and a polarizing plate is laminated on an outer surface side of at least one of the substrates. The touch panel, wherein the polarizing plate has an area shrinkage of 0.3% or less after being left in an environment of 80 ° C. for 24 hours. 2. The polarizing plate according to claim 1, wherein a surface film having a smaller linear expansion coefficient than the substrate on which the polarizing plate is laminated is laminated on the opposite side of the substrate with respect to the polarizing plate. Touch panel. 3. The polarizing plate includes a planar polarizer and a protective film attached to at least one surface of the polarizer, wherein the protective film is left at 80 ° C. for 24 hours. The touch panel according to claim 1, wherein an area shrinkage rate is 0.3% or less. 4. The touch panel according to claim 3, wherein the protective film is attached to at least a surface of the polarizer opposite to the substrate. 5. The touch panel according to claim 3, wherein the protective film has an optical in-plane retardation of 3 nm or less. 6. 90% RH at 70 ° C. or at 60 ° C.
The swelling of the operation surface after being left for 240 hours in the above environment is 1 mm or less.
The touch panel according to any one of the above. 7. A display device comprising: the touch panel according to claim 1; and display means having a display surface, wherein the touch panel is arranged in front of the display surface.