JP2002156920A - El display device with touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL display device with touch panel which enables to excellently display even under external light. SOLUTION: This EL display device with touch panel uses an EL element therein and is constituted by laminating the polarizer 111, wavelength plates 112, 113, a touch panel 120 and an EL display part 130 in order from the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an EL (electroluminescence) having a touch panel as an input device.
It relates to a display device.

[0002]

2. Description of the Related Art An EL element is a self-luminous element, and is expected to be used as a surface light emitting source because of a thin light emitting layer. It has high visibility and has been put to practical use in backlights for display elements and liquid crystal display devices.

[0003] Organic E using an organic compound as a light emitting material
The L element is an inorganic EL using an inorganic compound as a light emitting material.
It is being actively studied due to the drastic reduction in applied voltage and the high degree of freedom in material design as compared with the element. And organic EL
Various improvements have been made to use the element as a surface light source. Due to the development of blue light-emitting elements, color display has also reached the practical stage. For example, C.I. Adachi, S .; To
kito, T .; Tsutsui, S .; Saito. , J
pn. J. App1. Phys. , Vol. 27, L26
9 (1988) reports a method of providing an electron transporting layer such as phenylbiphenyloxadiazole between a light emitting layer and a cathode, and JP-A-7-90260 discloses
A method of emitting white light by emitting three colors of RGB has been proposed.

[0004] Also, P.S. Dyrek1ev et a1,
Adv. Mater. , 8, 146 (1995);
H. Wendorff et al, Liquid Cr
ysta1, Vo1.21, No. 6,903 (199
6) and the like, a method has been proposed in which an electroluminescent layer is oriented in one direction to obtain polarized light emission.

[0005]

Recently, a display device using the EL element and a touch panel as an input / output device have been used in combination. In general, a touch panel as the input / output device is formed by forming a transparent electrode on one surface of a pair of transparent substrates and facing the transparent electrode with the transparent electrode inside. At this time, a transparent spacer for preventing adhesion may be formed between the transparent electrodes. In this case, as the transparent electrode, a transparent conductive thin film such as indium tin oxide (ITO) is usually used, and its refractive index is about 2.0 or more. However, these transparent conductive films are provided in a state of direct contact with air in order to perform position detection by contact on the function as a touch panel, and have a very high light reflectance compared to the surface of an EL element panel, for example. In addition, since it is used on the front surface of the EL display device, the number of interfaces is simply increased, and the light reflection thereof causes a problem that the display contrast of the EL element panel is greatly reduced.

FIG. 3 is a cross-sectional view of a conventional EL display device with a touch panel. In the figure, the touch panel unit 320
Transparent electrode 321 for upper touch panel, transparent electrode 322 for lower touch panel, spacer 323, upper glass plate 3
24, a lower glass plate 325. Also,
The middle layer 310 includes a polarizing plate 311, a half-wave plate 312,
It is formed from a 波長 wavelength plate 313. Further, the EL display section 330 includes a glass transparent substrate 331, an ITO electrode 33
2, hole transport layer 333, fluorescent layer 334, back electrode 33
5. It is formed from a moisture-proof film 336. And
Touch panel section 320, middle layer section 310, EL display section 33
0 constitutes the EL display device 300 with a touch panel. In this conventional EL display device with a touch panel, the external light α is strongly reflected as α1 and α2 by the touch panel unit 320 because the touch panel unit 320 is on the surface layer.
It strongly affects the display light β, and makes the display extremely difficult to see.

Therefore, attempts have been made to suppress surface reflection by applying an anti-reflection treatment to the surface of the substrate or providing a low-refractive-index layer with a predetermined thickness under the transparent electrode. However, the reflection is effectively suppressed. This was not possible, resulting in higher costs.

The present invention suppresses glare and contrast deterioration due to surface reflection, which is light reflection of a touch panel,
It is an object of the present invention to provide an EL display device with a touch panel that realizes easy-to-view display.

[0009]

In order to solve the above-mentioned problems, an EL display device with a touch panel according to the present invention is a display device using an EL element, and includes a polarizing plate, a wave plate, a touch panel and an EL device in order from the outside. The display units are stacked and arranged.

In the EL display device with a touch panel according to the present invention, it is preferable that the wave plate is a laminate of a half wave plate and a quarter wave plate.

An EL display device with a touch panel according to the present invention comprises:
The EL display device provides a touch panel function by using a polarizing plate and a wave plate used for performing black display. Reflection of an interface of a transparent electrode or the like used for the touch panel is also performed by the polarizing plate or the two types. It can be significantly reduced by the combination of the wave plates, and the resulting reduction in contrast and glaring reflection do not occur, and the deterioration in display quality can be eliminated. In addition, since special components are not used for the components of the present invention, it is possible to reduce the weight and thickness of the components at the same time.

Further, in the EL display device with a touch panel according to the present invention, it is preferable that the touch panel is formed of transparent electrodes facing each other via a space.

The upper electrode of the touch panel of the present invention may be formed directly on the wave plate, or may be formed into an optically isotropic film having a retardation value of 30 nm or less, and adhered with an adhesive or an adhesive. May be combined. There is no particular limitation on the lower electrode, but a conductive thin film formed on a glass plate or a plastic plate used for an EL substrate, or a glass plate formed by forming an electrode on another film, It may be attached to a plastic substrate with an adhesive or the like.

Further, in the EL display device with a touch panel according to the present invention, the wave plate may be a half wave plate and a wave plate in order from the outside.
/ 4 wavelength plate is laminated, and the optical axis of the polarizing plate is
Assuming that the angle of the slow axis of the half-wave plate is θ, θ is 15 ° ±
5 °, and the angle between the optical axis of the polarizing plate and the slow axis of the 波長 wavelength plate is preferably (2θ + 45 °) ± 10 °.

Further, in the EL display device with a touch panel according to the present invention, the wave plate is sequentially arranged from the outside in the order of 1/4 wavelength plate and 1 wave plate.
/ 2 wavelength plates are laminated, and the optical axis of the
Assuming that the angle of the slow axis of the 波長 wavelength plate is θ, θ is 45 ° ±
It is preferable that the angle is 5 ° and the angle between the slow axis of the １ ／ wavelength plate and the slow axis of the １ ／ wavelength plate is 90 ° ± 10 °.

The materials of the half-wave plate and the quarter-wave plate of the present invention are not particularly limited, and those having excellent transparency are preferable. For example, polycarbonate-based polymers, polyester-based polymers, and polysulfone-based Molecules, polyether polymers, polystyrene polymers, polyolefin polymers, polyvinyl alcohol polymers, cellulose acetate polymers, polyvinyl chloride polymers, polymethyl methacrylate polymers, norbornene polymers, etc. No.

However, when the wave plate is formed by laminating a polarizing plate, a quarter wave plate, and a half wave plate sequentially from the outside, the thickness of the wave plate is d, and the wavelength of light is λ = 550n
When the refractive index of m is n ₅₅₀ and the refractive index of light having a wavelength of λ = 400 nm is n ₄₀₀ , the ratio of the phase difference of the half-wave plate △ n ₄₀₀
d / △ n ₅₅₀ d is the ratio of the phase difference of the 波長 wavelength plate △ n ₄₀₀ d
/ △ n ₅₅₀ d is preferred. That is, 1/2
It is preferable that the wavelength plate has low wavelength dispersion (the difference in refractive index at each wavelength is small), and the quarter-wave plate has high wavelength dispersion.

Specifically, the thickness of the wave plate is d, the refractive index at a wavelength of light λ = 550 nm is n ₅₅₀ , and the wavelength of light λ = 40.
Assuming that the refractive index at 0 nm is n ₄₀₀ , the ratio Δn ₄₀₀ d / Δn ₅₅₀ d of the retardation of the half-wave plate is preferably 1.1 or less. Is commercially available. Further, the ratio Δn ₄₀₀ d / Δn ₅₅₀ d of the retardation of the 波長 wavelength plate is preferably 1.1 or more. For example, a product of 1.16 of a polycarbonate type and a product of 1.2 of a polysulfone type are commercially available. . When the polarizing plate, the 波長 wavelength plate, and the 波長 wavelength plate are sequentially formed from the outside in this manner, the phase difference at each wavelength is laminated by crossing the slow axes having different phase differences. Can be superimposed or adjusted, a predetermined phase difference can be obtained over a wide wavelength range, and ideal circularly polarized light can be created.

The stretching of the に お い て wavelength plate and the 波長 wavelength plate are not particularly limited, but may be uniaxial stretching at a free end, uniaxial stretching at a fixed end, or biaxial stretching, such as stretching in the thickness direction described in Japanese Patent No. 2818983. Can be used. Further, the half-wave plate and the quarter-wave plate need not be a stretched film, and may be a substrate coated with an alignment film such as a polymer liquid crystal. Further, an inorganic crystal may be used.

The polarizing plate used in the present invention is not particularly limited. For example, a polarizing film obtained by stretching a normal dichroic substance-containing polyvinyl alcohol film is preferably used. Further, a polarizing element using a liquid crystal polymer may be used. Higher transmittance is preferable because brighter display can be obtained.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of Embodiment 1 of an EL display device with a touch panel according to the present invention. FIG. 1 shows an example of the case of an organic EL display device. In FIG. 1, reference numeral 100 denotes an EL display device with a touch panel according to the present invention. In the drawing, 111 is a polarizing plate, 112 is a half-wave plate, 11
Reference numeral 3 denotes a 波長 wavelength plate, and these are laminated to form a surface layer 1
10 are formed. Next, 121 is a transparent electrode for an upper touch panel made of an ITO conductive film, 122 is a transparent electrode for a lower touch panel made of an ITO conductive film, and a spacer 123 is disposed between the transparent electrodes for the touch panel section 12.
0 is formed. Further, 131 is a glass transparent substrate,
132 is an ITO electrode, 133 is N, N'-diphenyl-
N, N'-bis- (3-methylphenyl)-(1,1'-
A hole transport layer made of biphenyl) -4,4'-diamine (hereinafter, referred to as TPD); 134, a fluorescent layer made of tris (8-quinolinol) aluminum (hereinafter, A1q); 135, a back electrode; These films are used to form an EL display unit 130.
Surface section 110, touch panel section 120, EL display section 13
The EL display device 100 with a touch panel is formed by combining 0. Further, as the back electrode 135, a metal thin film layer such as a silver magnesium alloy is preferably used.

Since a metal thin film having high reflectivity is generally used for the back electrode, it is difficult to obtain a good black display by strongly reflecting external light even when light is not being emitted. Therefore, by combining a polarizing plate with a half-wave plate and a quarter-wave plate, the EL
By installing the display device in this order from the outside on the surface of the display device, reflection of external light can be significantly prevented.

In FIG. 1, when external light α is incident on the EL display device 100, the external light α is absorbed by the outer polarizing plate 111.
Becomes linearly polarized light, and passes through the half-wave plate 112 and the quarter-wave plate 113 to be converted into almost perfect circularly polarized light. E
Since the back electrode 135 of the L display device acts as a light reflection layer, the reflection reverses the circularly polarized light and reflects the circularly polarized light in the opposite phase. At this time, the ４ wavelength plate 11
When the light passes through the 3, 1/2 wavelength plate 112, it becomes linearly polarized light in a direction orthogonal to the transmission direction of the polarizing plate 111, so that most of the reflected light α3 is absorbed by the polarizing plate 111. Also,
Lights α1, α reflected by the electrode surface of the touch panel unit 120
2 is already circularly polarized by the polarizing plate and the two wavelength plates. Thus, similarly, the reflected lights α1 and α2 that reach the two wavelength plates and the polarizing plate are linearly polarized light, but have a 90 ° phase with the optical axis of the polarizing plate 111, and thus are absorbed by the polarizing plate 111. Will be done. Therefore, the reflected lights α1 and α2 are hardly observed from the outside. As described above, since the external light α does not occur except for reflection on the surface of the polarizing plate 111, a favorable black state can be formed. Therefore, only the light emitting portion of the EL element can be substantially used as the display light β. The effect of inversion of the polarization of the circularly polarized light on the reflection surface is higher as the circularly polarized light is better. In general, there is wavelength dispersion that can be approximated by Cauchy's dispersion equation in the phase difference of a quarter-wave plate, so that good circularly polarized light cannot be obtained at all wavelengths. To improve this, it is possible to obtain good circularly polarized light in almost all visible light wavelength ranges by providing a combination of a 波長 wavelength plate and a 波長 wavelength plate as disclosed in Japanese Patent Laid-Open No. 5-100114. it can.
In this case, there are a method of providing the slow axis of the quarter-wave plate at a different angle, a method of using a film having a different wavelength dispersion, and a method of using these in combination.

(Embodiment 2) FIG. 2 is a sectional view of an EL display device with a touch panel according to a second embodiment of the present invention. FIG. 2 also shows an example in the case of an organic EL display device. In FIG. 2, reference numeral 200 denotes an EL display device with a touch panel according to the present invention. In the figure, from the outermost surface, 211 is a polarizing plate, 214 is a ２１ wavelength plate, 21
2 is a half-wave plate, and these are laminated to form a surface layer 2
10 are formed. Next, 221 is a transparent electrode for an upper touch panel made of an ITO conductive film, 222 is a transparent electrode for a lower touch panel made of an ITO conductive film, and a spacer 223 is arranged between the transparent electrodes for the touch panel portion 22.
0 is formed. Further, 231 is a glass transparent substrate,
Reference numeral 232 denotes an ITO electrode; 233, a hole transport layer made of TPD; 234, a fluorescent layer made of A1q; 235, a back electrode; and 236, a moisture-proof film. An EL display device 200 with a touch panel is formed by combining the surface layer portion 210, the touch panel portion 220, and the EL display portion 230. Also,
As the back electrode 235, a metal thin film layer such as a silver magnesium alloy is preferably used.

[0026]

(Example 1) A polyvinyl alcohol film having a thickness of 75 μm was treated with iodine and stretched at a temperature of 60 ° C.
The film was uniaxially stretched under the condition of a stretching ratio of 6.0 to obtain a polarizing plate.
Next, a norbornene-based polymer film having a thickness of 100 μm is uniaxially stretched at a stretching temperature of 170 ° C. and a stretching magnification of 1.7 times, and is irradiated with light having a wavelength of 550 nm based on birefringent light.
A half-wave plate giving a phase difference of two wavelengths was obtained. Further, a norbornene-based polymer film having a thickness of 50 μm is uniaxially stretched at a stretching temperature of 170 ° C. and a stretching magnification of 1.7 times to obtain a wavelength of 5 μm.
Gives a 1/4 wavelength phase difference to 50 nm light 1 /
A four-wave plate was obtained.

The above-obtained quarter-wave plate was subjected to a plasma treatment in an Ar atmosphere, and an ITO thin film was formed by sputtering to produce a transparent electrode substrate for an upper touch panel.

Next, after the glass substrate is cut into a predetermined shape, the glass substrate is subjected to a plasma treatment in an Ar atmosphere to have a thickness of 100 mm.
An ITO thin film of nm was formed by sputtering to prepare an EL panel substrate. The transparent electrode of one substrate is divided into two by etching in advance.

Similarly, as a transparent electrode for the lower touch panel, an ITO having a thickness of 25 nm is formed on the opposite surface of the glass substrate.
A thin film was formed by sputtering. After the glass substrate was subjected to ultrasonic cleaning and ultraviolet ozone cleaning, it was placed in a resistance heating type vacuum evaporation apparatus, TPD was placed in a molybdenum heating boat arranged in the apparatus, and Alq was placed in another molybdenum resistance heating boat. Into the vacuum chamber
The pressure was reduced to × 10 ⁻⁴ Pa.

Next, the resistance heating boat of TPD was heated to 220 ° C.
The hole transport layer having a thickness of 60 nm was formed by heating to a thickness of 100 μm on the ITO thin film of the glass substrate. Then, the resistance heating boat containing Alq was
After heating to 5 ° C., Alq was deposited on the hole transport layer to form an Alq layer having a thickness of 60 nm. Next, magnesium was placed in a molybdenum resistance heating boat, silver was placed in another molybdenum resistance heating boat, and the inside of the vacuum chamber was cooled for 2 hours.
The pressure was reduced to × 10 ⁻⁴ Pa, and an alloy electrode of magnesium and silver was deposited by a dual simultaneous vapor deposition method to a thickness of 140 nm to form a back electrode. The atomic ratio of magnesium to silver was 9: 1. All depositions were kept at room temperature. The deposited film is divided into two parts by masking in advance.

Thus, an EL display section was created.
The obtained EL display section is green (513 nm in main wavelength).
Of light.

Next, the IT of the transparent electrode for the upper and lower touch panels
After printing a silver electrode on the O-plane, the electrode side of the transparent conductive film is arranged with a spacer interposed therebetween so that the slow axis of the half-wave plate is 15 °, 1/4 with respect to the optical axis of the polarizing plate. A laminated touch panel was prepared such that the slow axis of the wave plate was 75 °, and an EL display device with a touch panel was prepared.

(Example 2) The order of laminating the wave plates of Example 1 was changed from the outside to a quarter wave plate and a half wave plate.
In addition, a quarter-wave plate is stretched at a stretching temperature of 150 ° C. and a stretching magnification of 1.05 times with a polycarbonate film having a thickness of 50 μm, and a wavelength of ５０ wavelength is determined based on birefringent light. Changed to give a difference. At this time, the slow axis of the quarter-wave plate is 4 with respect to the optical axis of the polarizing plate.
The adjustment is performed so that the slow axis of the half-wave plate is 90 ° with respect to the slow axis of the 5 ° and quarter-wave plate. In Example 1, the transparent electrode for the upper touch panel was formed by sputtering an ITO thin film on a quarter-wave plate, but in Example 2, the transparent electrode was formed on a half-wave plate in the same manner. Otherwise, an EL display device with a touch panel was prepared in the same manner as in Example 1.

Comparative Example 1 A polarizing plate, a wavelength plate, and an EL display portion were sequentially laminated from the outside in the same manner as in Example 1. A transparent electrode composed of an ITO thin film on which silver paste is printed and a polyethylene terephthalate (PET) film is adhered to a glass plate via an adhesive from above, and the two glass plates are transparently connected via a spacer. A touch panel is created by arranging the electrodes so that they face each other.
An L display device was created.

(Evaluation Test) As a light source, one fluorescent lamp was arranged at an interval of 1 m from the panel so as to be at a position of 20 ° from the front of the panel. An electric field was applied to one of the two divided electrodes so that half of the green color of the light emitting portion was displayed, and the display state was observed and compared.

First, when the touch panel portion was removed and observed, good display could be performed at a level that did not cause any problem in each of Example 1, Example 2, and Comparative Example 1.

Next, observation was performed with the touch panel attached. As a result, in Example 1 and Example 2, the display state did not change at all and was good. However, in Comparative Example 1, the reflection of the fluorescent lamp on the touch panel was large especially near regular reflection, and the reflected light hindered black display in particular, making it very difficult to see. In addition, even if the viewpoint was removed from the specular reflection direction, the face of the observer himself was reflected, and it was very difficult to see. In Examples 1 and 2, the light-emitting portion was very clearly displayed in green, and was very good. Further, in Examples 1 and 2, reflected light which is considered to be caused by the touch panel could be effectively prevented, and even in regular reflection, only reflected light from the antireflection film on the panel surface was visible, and the display quality was good.

The touch panel functioned without any problem in each of Example 1, Example 2, and Comparative Example 1.

[0039]

As described above, according to the present invention, since the polarizing plate, the wavelength plate, the touch panel and the EL display section are laminated and arranged in order from the outside, glare and contrast due to surface reflection, which is light reflection of the touch panel, are provided. E with a touch panel that can perform good display even when there is external light while suppressing the deterioration of
An L display device can be provided, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a sectional view of Embodiment 1 of an EL display device with a touch panel according to the present invention.

FIG. 2 is a cross-sectional view of Embodiment 2 of the EL display device with a touch panel of the present invention.

FIG. 3 is a cross-sectional view of a conventional EL display device with a touch panel.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 EL display device with touch panel 110 Surface layer 111 Polarizing plate 112 板 wavelength plate 113 波長 wavelength plate 120 Touch panel portion 121 Transparent electrode for upper touch panel 122 Transparent electrode for lower touch panel 123 Spacer 130 EL display portion 131 Glass transparent base Material 132 ITO electrode 133 Hole transport layer 134 Fluorescent layer 135 Back electrode 136 Moisture proof film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Minoru Miyatake 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Hideo Sugawara 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Takehiko Ando 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 3K007 AB17 BB06 CA01 CB01 DA01 DB03 EB00 5B087 AB04 AC09 CC12 CC16 CC18 5G006 AA04 FB14 FB17 JA01 JB06 JC01 JD01 5G435 AA01 BB05 EE12 FF01 FF05 GG25 HH02 HH12 HH14 HH18

Claims (6)

[Claims] 1. A display device using an EL element, wherein a polarizing plate, a wave plate, a touch panel, and an EL display portion are laminated and arranged in this order from the outside. 2. The EL display device with a touch panel according to claim 1, wherein the wave plate is a laminate of a half wave plate and a quarter wave plate. 3. An EL display device with a touch panel, wherein the touch panel is formed of transparent electrodes facing each other via a space. 4. The wave plate is formed by laminating a half-wave plate and a quarter-wave plate sequentially from the outside, and an angle between an optical axis of the polarizing plate and a slow axis of the half-wave plate. The angle θ is 15 ° ± 5 °, and the angle between the optical axis of the polarizing plate and the slow axis of the 波長 wavelength plate is (2θ + 45 °) ± 10 °. EL display device with touch panel. 5. The wave plate is formed by laminating a quarter-wave plate and a half-wave plate sequentially from the outside, and the angle between the optical axis of the polarizing plate and the slow axis of the quarter-wave plate. When θ is θ, θ is 45 ° ± 5 °, and the slow axis of the 波長 wavelength plate is 1 /
The EL display device with a touch panel according to claim 1, wherein the angle of the slow axis of the two-wave plate is 90 ° ± 10 °. 6. The wavelength plate has a thickness of d and a wavelength of light λ = 5.
The refractive index of 50 nm is n ₅₅₀, Light wavelength λ = 400 nm
Refractive index is n₄₀₀Where the ratio of the phase difference of the half-wave plate
△ n₄₀₀d / △ n₅₅₀d is the ratio of the phase difference of the 波長 wavelength plate △
n₄₀₀d / △ n₅₅₀The touch according to claim 5, which is smaller than d.
EL display device with panel.