JP3313337B2 - Low reflection touch panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-reflection touch panel, which suppresses reflection at the interface between the lowermost surface of the touch panel and an air layer and has excellent visibility.

[0002]

2. Description of the Related Art Word processors, notebook computers,
2. Description of the Related Art With respect to a liquid crystal display widely used for products such as a PDA (Personal Digital Assistant), a touch panel is conventionally arranged on the front surface thereof. The touch panel has a structure in which two transparent plates on which a transparent conductive film is formed are arranged so that the transparent conductive films face each other via a spacer, and both transparent conductive films that have been insulated by the spacer are disposed on the panel surface. Are pressed to contact each other to make them electrically conductive to enable input. However, the above touch panel
When the input operation is performed in a room with a fluorescent light or the like or outdoors, light from the outside is reflected on the surface of the transparent conductive film, so that the display screen is very difficult to see.

In order to solve such a problem,
Japanese Patent Application Laid-Open No. H10-48625 discloses that a first quarter-wave plate 3, two transparent conductive films 5 facing each other via a spacer, a second quarter-wave plate 7, in order from the liquid crystal display 2 side. A touch panel having at least a polarizing plate 8 has been proposed (see FIG. 2) . The second quarter-wave plate 7 and the polarizing plate 8 form a circular polarization type anti-reflection filter, and the reflection of light incident from the outside on the transparent conductive film 5 is efficiently cut. Also, the second quarter-wave plate 7
If only one is used, the linearly polarized light 2 incident for display from the liquid crystal display 2 will also be changed to circularly polarized light.
The first quarter-wave plate 4 whose optical axis is orthogonal to the second quarter-wave plate 7 is arranged between the two transparent conductive films 5 and the liquid crystal display 2 to cancel the phase. . That is, after being made circularly polarized by the first quarter-wave plate 4, the second
Is returned to the original linearly polarized light again by the 1/4 wavelength plate 7.

[0004] The touch panel and the liquid crystal display 2 are usually provided with an air layer 9 between them by, for example, bonding with a double-sided adhesive tape outside the display area. This is to prevent the thickness of the liquid crystal of the liquid crystal display 2 from being compressed at the input location due to the close contact between the touch panel and the liquid crystal display 2, thereby preventing the display image from being blurred or distorted.

[0005]

However, since the air layer 9 is formed between the touch panel and the liquid crystal display 2, reflection of external light at the interface between the lowermost surface of the touch panel and the air layer 9 is reduced. There is a problem that occurs. In addition, at this time, since the first quarter-wave plate 4 exists between the antireflection filter formed by the second quarter-wave plate 7 and the polarizing plate 8 and the lowermost surface of the touch panel, reflection occurs. The reflected light cannot be cut off by the anti-filter.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-mentioned problems, and to provide a low-reflection touch panel excellent in visibility, in which reflection at the interface between the lowermost surface of the touch panel and the air layer is suppressed. That is.

[0007]

In order to achieve the above object, a low-reflection touch panel according to the present invention comprises, in order from a liquid crystal display, a first quarter-wave plate and two transparent layers opposed to each other via a spacer. A touch panel having at least a conductive film, a second quarter-wave plate, and a polarizing plate and having a circularly-polarized type antireflection filter, which is the lowermost surface facing the liquid crystal display surface via an air layer. one
The first quarter-wave plate made of only the axially stretched resin was configured to be directly subjected to the low reflection treatment.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an example in which a low-reflection touch panel according to the present invention is disposed on the front surface of a liquid crystal display. In the figure, 1 is a low-reflection touch panel, 2 is a liquid crystal display, 3 is a low-reflection processing layer, and 4 is the first quarter.
Wave plate 5, 5 is a transparent conductive film, 6 is a spacer, 7 is a second quarter-wave plate, 8 is a polarizing plate, 9 is an air layer, 10 is a double-sided viscous plate.
Each shows an attached tape .

First quarter-wave plate 4 and second quarter-wave plate
The wave plate 7 has a function of converting linearly polarized light into circularly polarized light or substantially circularly polarized light by giving a temporal phase shift (phase difference) to two components of orthogonally polarized light obtained by decomposing linearly polarized light. The phase of one polarized light component is delayed by a quarter wavelength from that of the other polarized light component. The 波長 wavelength is relative to the center wavelength (about 550 nm) in the visible light region (about 400 nm to 700 nm). As the first quarter-wave plate 4 and the second quarter-wave plate 7, a transparent plate or film of polycarbonate, polyarylate, polyethersulfone, polysulfone, norbornene-based resin or the like is uniaxially stretched, and the stretching direction. X (in the direction of the optical axis)
And the refractive index in the y direction orthogonal to the x direction,
What is given by controlling the refractive index in the thickness direction, that is, the z direction orthogonal to the x direction and the y direction, is used.

The second quarter-wave plate 7 is combined with the polarizing plate 8 on the front surface to form a circularly-polarized type antireflection filter. Light from the outside, such as an indoor fluorescent lamp or outdoor light, passes through the polarizing plate 8 and becomes linearly polarized light.
Although the light becomes circularly polarized light by transmitting through the wave plate 7, even if the light is reflected by the transparent conductive film 5, the circularly polarized light again passes through the second 板 wave plate 7 and is perpendicular to the transmission axis of the polarizing plate 8. Since the light is linearly polarized, reflected light is suppressed. Note that the second quarter-wave plate 7 has flexibility to facilitate input with a pen or finger.

It is preferable that the first quarter-wave plate 4 and the second quarter-wave plate 7 are arranged so that their optical axes are orthogonal to each other. With this arrangement, the linearly polarized light incident on the first quarter-wave plate 4 for display from the liquid crystal display 2 side becomes circularly polarized light by passing through the first quarter-wave plate 4. Is transmitted again through the second quarter-wave plate 7 to return to linearly polarized light.
Is displayed through.

The polarizing plate 8 disposed in front of the second quarter-wave plate 7 forms a circularly polarized antireflection filter in combination with the second quarter-wave plate 7.
The absorption axis of the polarizing plate 8 disposed in front of the second quarter-wave plate 7 is formed so as to be 45 ° or 135 ° with the optical axis 7 of the second quarter-wave plate 7. As the polarizing plate 8,
In general, a polyvinyl alcohol film impregnated with a dichroic dye such as iodine or a dye and stretched is used, and both surfaces thereof are coated with a cellulose or acrylic protection film. Further, a low reflection treatment, an antifouling treatment, a satin finish treatment and the like can be applied to the polarizing plate 8. Alternatively, the films subjected to these treatments may be bonded on the polarizing plate 8 via an adhesive or the like. Further, some of the above processes may be used in combination. Here, as the low reflection processing,
For example, a low-reflection material using a fluororesin or a silicon resin is applied, or a metal multilayer film is formed by a vacuum evaporation method, a sputtering method, or the like. As antifouling treatment,
For example, application of an antifouling material using a fluorine resin or the like can be mentioned. In addition, sand blast processing,
Embossing, mat coating, etching and the like can be mentioned.

The two layers of the transparent conductive film 5 face each other with the spacer 6 interposed therebetween and serve as electrodes of the touch panel. Examples of the material of the transparent conductive film 5 include tin oxide, indium oxide,
Metal oxides such as antimony oxide, zinc oxide, cadmium oxide, and ITO, and thin films of metals such as gold, silver, copper, tin, nickel, aluminum, and palladium are used. As a method for forming the transparent conductive film 5, a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, or the like is used. In the present invention, the transparent conductive film 5 may be directly formed on each of the first 波長 wavelength plate 4 and the second 波長 wavelength plate 7 (see FIG. 1), or the first １ ／ wavelength plate may be used. An optically isotropic glass plate, an optically isotropic resin film, or an optically isotropic resin plate between one or both of the four-wavelength plate 4 and the second quarter-wavelength plate 7 and the transparent conductive film 5 An optically isotropic transparent plate such as described above may be interposed. Also, at least one of the surfaces of the transparent conductive film 5 may be subjected to a satin finish for the purpose of preventing generation of Newton rings. The satin finish can scatter light and suppress light interference between the transparent electrodes. Further, a low reflection process may be performed.

The spacer 6 is made of one of the transparent conductive films 5
Is formed on the surface. The spacer 6 can be obtained by forming a transparent photocurable resin into fine dots by a photo process. Alternatively, the spacer 6 can be formed by forming a large number of fine dots by a printing method.
Further, between the members on which the transparent conductive film 5 of the low reflection touch panel 1 is directly formed, only the outside of the display area is adhered by the double-sided adhesive tape 10 or the transparent adhesive.

A feature of the present invention resides in that a touch panel having a circular polarization type antireflection filter is subjected to a low reflection treatment on the lowermost surface facing the surface of the liquid crystal display 2 via the air layer 9. With such a configuration, reflection of light from the outside at the interface between the lowermost surface of the touch panel and the air layer 9 is suppressed, so that the visibility is further improved. In addition, since the reflection of the transmitted light from the liquid crystal display 2 at the lowermost surface of the touch panel is suppressed, the amount of transmitted light from the liquid crystal display 2 emitted from the front surface of the touch panel is increased accordingly. Examples of the low-reflection treatment include applying a low-reflection material using a fluorine resin, a silicon resin, or the like, and a vacuum deposition method, a sputtering method, or the like of a metal multilayer film. These treatments may be performed directly on the lowermost surface of the touch panel to form the low-reflection treatment layer 3, or a film or resin plate subjected to these treatments may be adhered so that the low-reflection treatment surface is on the liquid crystal display 2 side. The low-reflection treatment layer 3 may be entirely bonded to the lowermost surface of the touch panel via an agent or the like.

[0016]

In the low-reflection touch panel having the above-described structure, the entire surface between the second quarter-wave plate 7 and the polarizing plate 8 disposed on the front surface thereof is covered with a transparent adhesive or a transparent removable sheet. Must be bonded together,
Only the outside of the display area may be stuck to the other boards with a double-sided adhesive tape.

[0018]

The low-reflection touch panel of the present invention has the following configuration and operation, and has the following effects.

That is, a uniaxially stretched tree which is the lowermost surface facing the liquid crystal display surface of a touch panel having a circular polarization type antireflection filter via an air layer.
Since the low reflection treatment is directly applied to the first quarter-wave plate made of only fat , reflection at the interface with the air layer is suppressed, and the visibility is further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example in which a low-reflection touch panel according to the present invention is disposed on a front surface of a liquid crystal display.

FIG. 2 is a cross-sectional view showing an example in which a low-reflection touch panel according to the related art is arranged on the front surface of a liquid crystal display.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 low reflection touch panel 2 liquid crystal display 3 low reflection treatment layer 4 first 処理 wavelength plate 5 transparent conductive film 6 spacer 7 second ４ wavelength plate 8 polarizing plate 9 air layer 10 double-sided adhesive tape

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-11-134112 (JP, A) JP-A-10-186136 (JP, A)

Claims (1)

(57) [Claims] 1. The first 1 /
A touch panel having a circular polarization type antireflection filter, comprising at least a four-wavelength plate, two layers of transparent conductive films facing each other via a spacer, a second quarter-wavelength plate, and a polarizing plate, Is only the uniaxially stretched resin that is the lowermost surface facing the display surface via the air layer ?
A low-reflection touch panel, wherein a low-reflection process is directly applied to a first quarter-wave plate made of the same.