WO2011158692A1

WO2011158692A1 - Input device

Info

Publication number: WO2011158692A1
Application number: PCT/JP2011/062998
Authority: WO
Inventors: 好史舛本
Original assignee: アルプス電気株式会社
Priority date: 2010-06-18
Filing date: 2011-06-07
Publication date: 2011-12-22
Also published as: JPWO2011158692A1

Abstract

Provided is an input device capable of effectively preventing internal reflection of the light from the outside, and capable of preventing drawbacks regarding coloring, etc., even if a substrate, etc., of an input panel is structured by a biaxial stretched film. An external light (1) becomes a linearly-polarized light by a polarizing film (22a), and becomes a circularly-polarized light (2) by a λ/4 phase difference film (22b). If the circularly-polarized light (2) is reflected by a surface (30a) of a display panel (30) or an electrode layer in the display panel (30), the light becomes a linearly-polarized light by the λ/4 phase difference film (22b) and is blocked by the polarizing film (22a). If an input panel (21) is formed by a biaxial stretched film and has a birefringence property, because the circularly-polarized light does not pass through the biaxial stretched film, drawbacks regarding coloring, etc., of the reflection light can be prevented.

Description

Input device

The present invention relates to an input device which is disposed on the front side of a display panel such as an electroluminescence panel or a liquid crystal display panel and in which an input operation is made possible by an input panel such as a capacitance detection type.

The operation unit of various electronic devices such as portable devices is provided with an input device having a translucent input panel on the surface of the display panel. The input panel is, for example, an electrostatic capacitance detection type, and includes translucent electrodes crossing each other, and detects an electrostatic capacitance formed between the electrode and the finger when the finger contacts the panel surface. , To identify the contact position of the finger.

In the operation unit, there is a problem that external light is reflected at the boundary of each layer, and the reflected light overlaps the display image of the display panel and is viewed.

In the touch panel described in Patent Document 1 below, a touch panel of capacitance detection type is installed on the surface of a liquid crystal display element, and a 1⁄4 wavelength retardation plate and a polarizing plate are provided on the front side of the touch panel. A quarter wave retarder is provided on the back side of the touch panel facing the display panel. Light entering from the outside is converted into linearly polarized light by the polarizing plate, passes through the front retardation plate, and becomes circularly polarized light. When circularly polarized light is reflected by the inside of the touch panel or the display panel, the reflected light passes back through the front retardation plate to become linearly polarized light whose polarization direction is orthogonal to the transmission axis of the wave plate, and is reflected. It is blocked so that the light does not go out.

Further, the display light of linearly polarized light emitted from the liquid crystal display element can be returned to linearly polarized light and can pass through the polarizing plate by transmitting both of the retardation plate on the back side and the retardation plate on the front side. Thereby, the loss of display light is reduced.

In the transparent touch switch described in Patent Document 2 below, a linear polarization plate and a λ / 4 retardation plate are provided on the front side of the touch switch, and a λ / 4 retardation plate is provided on the back side of the touch switch. Like the invention of Patent Document 1, this invention can block the reflection of light incident from the outside and can reduce loss of display light emitted from the liquid crystal display device.

JP, 2008-262326, A WO 2006/126604 Reissue Patent

If an input device in which a touch panel, a polarizing plate, and a λ / 4 retardation plate are integrated in the conventional operation unit is to be adhered to the entire surface of the display panel via the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer There is a problem that a defect in which air bubbles remain tends to occur, and the yield of the assembly becomes worse.

By forming a thin gap without interposing the adhesive between the surface of the touch panel and the input device, it is possible to solve the problem that air bubbles are formed in the adhesive. However, in this case, light from the outside is likely to be reflected at the interface between the thin air gap and the surface of the touch panel, so the amount of reflected light increases.

Furthermore, as for what was described in patent document 1 and patent document 2, as for the front side of the touch panel, the λ / 4 wavelength plate and the polarizing plate are provided. Therefore, it is necessary to form the substrate of the touch panel with a light isotropic material. If a birefringent substrate is used, the reflected light of circularly polarized light reflected inside the touch panel or on the surface of the display panel or inside the display panel becomes elliptically polarized light by transmitting through the birefringent substrate, and this elliptically polarized light When the light passes through the phase difference plate on the front side and the polarizing plate, coloring such as iridescence occurs, and the display quality is degraded.

The present invention solves the above-mentioned conventional problems, and even if there is a gap between the display panel and the input device, an input device capable of reducing the influence of light reflected from the interface between the gap and the display panel. It is intended to be provided.

Another object of the present invention is to provide an input device capable of reducing problems such as coloring of reflected light even when the input panel is formed of a birefringent substrate.

The present invention relates to an input device having a translucent input panel,
The input panel is disposed in front of a display panel via an air layer, and converts light from the input panel from linearly polarized light to circularly polarized light between the input panel and the air layer. A light conversion layer to be provided to the air layer is provided.

According to the input device of the present invention, the air layer is formed between the input panel and the display panel and the pressure-sensitive adhesive layer is not interposed, whereby the problem of air bubbles entering the pressure-sensitive adhesive layer can be solved. In addition, by disposing the light conversion layer in front of the air layer, it is possible to block the light reflected by the interface between the air layer and the display panel, and the state where the display quality is degraded by the reflected light from the interface It becomes difficult.

In the present invention, the input panel can be configured of a translucent base formed of a biaxially stretched resin film, and a translucent electrode layer.

Even if external light is reflected at the boundary surface or inside the display panel, it is not blocked by the light conversion layer and does not return to the input panel, and the display light does not become circularly polarized. Therefore, the problem of coloring of the reflected light does not occur.

In the present invention, preferably, the input panel is a capacitance detection type that does not include an air layer.

Further, according to the present invention, the display panel emits display light of linearly polarized light and artificial light which is not circularly polarized light.

Alternatively, in the present invention, the display panel emits display light of linear polarization, and a λ / 4 retardation layer is provided between the display panel and the light conversion layer.

The input device of the present invention can block reflected light from the interface between the air layer and the display panel by the light conversion layer even if an air layer is provided between the display panel and the display quality due to the reflected light. It becomes easy to prevent.

Further, the substrate of the input panel can be formed of a biaxially stretched resin film, and the range of selection of the material of the input panel can be broadened to facilitate cost reduction.

An exploded perspective view of a portable device equipped with the input device according to the embodiment of the present invention; FIG. 6 is a cross-sectional view showing an input device and a display panel according to a first embodiment of the present invention; Sectional drawing which shows the input device and display panel of 2nd Embodiment of this invention. A sectional view showing an example of the input panel;

The mobile device 10 illustrated in FIG. 1 is used as a mobile phone, a portable information processing device, a portable storage device, a portable game device, or the like.

The portable device 10 has a case 2 made of synthetic resin. The case 2 has a recess 3 whose upper side is open, and the circuit board on which the electronic circuit is mounted and the display panel 30 are accommodated in the recess 3. The opening of the recess 3 is closed by the input device 20 according to the embodiment of the present invention. The input device 20 has a display area 20a through which display light from the display panel 30 passes and a non-display area 20b surrounding the display area 20a.

The display panel 30 shown in FIG. 2 is a self-luminous panel such as an electroluminescent panel. The display light emitted from the display panel 30 is artificial light in a state close to natural light, not linearly polarized light, circularly polarized light, or elliptically polarized light.

The spacer 31 is fixed to the surface 30 a of the display panel 30, and the input device 20 is fixed to the surface of the spacer 31. The spacer 31 has a frame shape surrounding the display area 20a of the input device 20. In the display area 20a, a thin air layer 32 is formed between the surface 30a and the input device 20.

As shown in FIG. 2, the input device 20 has a translucent input panel 21. Translucency in the present specification means a state capable of transmitting light, such as transparent or semitransparent, and means that the total light transmittance is 50% or more and preferably 80% or more.

The input panel 21 is a capacitance detection type. As shown in FIG. 4, the input panel 21 includes a translucent substrate 21a, a first electrode layer 21b formed on the back of the substrate 21a, and a second electrode layer 21c formed on the surface of the substrate 21a. have.

The substrate 21 a is formed of a biaxially stretched translucent resin film such as polyethylene terephthalate (PET). The first electrode layer 21 b and the second electrode layer 21 c are both formed of a translucent conductive material such as ITO. The first electrode layer 21b and the second electrode layer 21c are insulated from each other and provided in a plurality of rows in parallel in directions orthogonal to each other.

Voltages are sequentially applied to the plurality of first electrode layers 21b, and voltages are sequentially applied to the plurality of second electrode layers 21c at different timings. When a person's finger, which is a conductor at substantially the ground potential, approaches any electrode layer, a capacitance is formed between the electrode layer and the finger. By detecting this change in capacitance, it is possible to detect the position at which the finger approaches.

As shown in FIG. 2, the light conversion layer 22 is entirely bonded to the back surface of the input panel 21 via the light transmitting pressure-sensitive adhesive layer 23. The pressure-sensitive adhesive layer 23 is formed of an acrylic pressure-sensitive adhesive.

In the light conversion layer 22, a polarizing film 22a which is a polarizing layer is provided on the input panel 21 side, and a λ / 4 retardation film 22b which is a λ / 4 retardation layer is provided on the display panel 30 side. The polarizing film 22a and the λ / 4 retardation film 22b are bonded to each other.

In the λ / 4 retardation film 22 b, the incident light is separated into two orthogonal linear polarization components by birefringence, and a phase shift of 1⁄4 wavelength is given to the two linear polarization components. The optical axis of the λ / 4 retardation film 22b is combined to be inclined at an angle of 45 degrees or 135 degrees with respect to the transmission axis of the polarizing film 22a. When the external light passes through the polarizing film 22a, it becomes linearly polarized light, and when the linearly polarized light passes through the λ / 4 retardation film 22b, it is converted into circularly polarized light. Conversely, when circularly polarized light passes through the λ / 4 retardation film 22b, it is converted back to linearly polarized light.

As shown in FIG. 2, on the front side of the input panel 21, a translucent cover layer 24 is entirely bonded via an acrylic translucent adhesive layer 25. The cover layer 24 is formed of glass, or a light transmitting resin such as PMMA (methyl methacrylate resin), PC (polycarbonate), or COP (cyclic olefin copolymer). A decorative film is provided on the surface of the cover layer 24, and as shown in FIG. 1, the decorative film is colored so as not to transmit light in the non-display area 20b.

The right side of FIG. 2 shows the path of the external light (1) entering the display area 20a of the input device 20 from the outside.

Outside light (1) which is natural light transmitted through the cover layer 24 and the input panel 21 passes through the polarizing film 22a of the light conversion layer 22 to be linearly polarized light, passes through the λ / 4 retardation film 22b, and is circularly polarized (2 ). When the circularly polarized light (2) is reflected by the surface 30a of the display panel 30, which is the interface between the air layer 32 and the display panel 30, it turns back as circularly polarized light (3) in the opposite direction. Although this circularly polarized light (3) passes through the λ / 4 retardation film 22b to be linearly polarized light, the reflected light is polarized because the optical axis of this linearly polarized light is 90 ° different from the transmission axis of the polarizing film 22a. It is absorbed by the film 22a and shut off without returning to the outside.

A part of the circularly polarized light (2) converted from the external light (1) by the light conversion layer 22 enters the inside of the display panel 30, and is reflected by the electrode layer provided on the display panel 30, The reflected light also becomes reverse circularly polarized light (3) and is blocked by the light conversion layer 22.

On the other hand, since display light emitted from a self-luminous display panel 30 such as an electroluminescence panel is artificial light which is close to natural light instead of linearly polarized light, the λ / 4 retardation film 22 b of the light conversion layer 22 optically Although it does not receive any influence, it becomes linearly polarized light by transmitting through the polarizing film 22a, and transmits through the input panel 21 and the cover layer 24 to go forward. The substrate 21a of the input panel 21 is formed of a biaxially stretched translucent resin film and has birefringence, but the linearly polarized light passes through the substrate 21a, causing problems such as coloring and the like. It does not occur.

The input device 20 shown in FIG. 2 receives the reflected light from the surface 30 a which is the interface between the air layer 32 and the display panel 30 when the external light (1) is incident, and the electrode layer in the display panel 30. It is possible to prevent adverse effects such as reflected light being blocked by the common light conversion layer 22 and the reflected light from the surface 30a being superimposed on the display light from the display panel 30, or the pattern of the electrode layer of the display panel 30 being projected. . Therefore, as compared with the structure in which the antireflective film is formed on the surface 30a of the display panel 30, the influence of the light reflected by the surface 30a can be effectively prevented.

As shown in FIG. 2, when the input device 20 formed by laminating each layer is installed at the front of the display panel 30, the spacer 31 is provided instead of the whole surface bonding to interpose the air layer 32. However, the light conversion layer 22 can block the reflected light on the surface 30a which is the interface between the air layer 32 and the display panel 30, and the problem of the air layer 32 being present is eliminated. Therefore, it is not necessary to adhere the display panel 30 and the input device 20 to the entire surface through the adhesive layer, and it is possible to solve the problem that air bubbles intervene in the adhesive layer and the number of defective products increases.

The substrate 21 a of the input panel 21 is formed of a biaxially stretched film and thus has birefringence. However, since the light conversion layer 22 is disposed on the back side of the input panel 21, the circularly polarized light (3) of the reflected light does not reach the substrate 21a. Therefore, the conventional problem that coloring occurs when circularly polarized light which is reflected light passes through the birefringent substrate 21a can be solved. Therefore, the input panel 21 can be made of a resin film other than the light isotropic material, and the input panel 21 can be made thin and inexpensive.

FIG. 3 shows a portable device 110 according to a second embodiment of the present invention.
The display panel 130 used in the portable device 110 shown in FIG. 3 includes a liquid crystal display panel. The input device 20 having the same structure as that of FIG. 2 is fixed to the front side of the display panel 130 via the spacer 31. Thus, in the display area, the air layer 32 is formed between the display panel 130 and the input device 20.

The display panel 130 has a backlight unit that provides light from LEDs and lamps from behind the liquid crystal display panel.

In the liquid crystal display panel, transparent electrodes face each other with the liquid crystal material layer interposed therebetween, and an alignment layer and a polarization layer facing each other with the liquid crystal material layer interposed therebetween are provided. Therefore, the display light given from the backlight unit and transmitted through the liquid crystal display panel is linearly polarized light. For that purpose, the second λ / 4 retardation film 131 is provided on the front side of the display panel 130 that is the display light transmission side. The λ / 4 retardation film 22 b provided in the input device 20 and the second λ / 4 retardation film 131 are disposed such that the optical axes are orthogonal to each other. In addition, the directions of the light transmission axes of the polarizing layer provided on the side of the liquid crystal display panel that transmits display light and the polarizing film 22 a in the input device 20 coincide with each other.

In FIG. 3, (A) shows the path of light when the external light (1) is incident, and (B) shows the path of the display light (4) emitted from the display panel 130.

As shown in FIG. 3A, when external light (1) is incident, the reflected light from the surface 131a of the second λ / 4 retardation film 131 or the reflection from the electrode layer of the liquid crystal display panel The light is blocked as in the case of the operation panel 10 shown in FIG.

As shown in FIG. 3B, the light emitted from the backlight section in the display panel 130 is transmitted through the liquid crystal display panel and sent out as linearly polarized display light (4). The linearly polarized light (4) passes through the second λ / 4 retardation film 131 to become circularly polarized light (5), and further passes through the λ / 4 retardation film 22b in the input device 20 and is linearly polarized. Return to (6). Since the polarizing layer on the transmission side of the liquid crystal display panel and the polarizing film 22a in the input device 20 have the same direction of the transmission axis, the display light is given upward as linearly polarized light (7) with little loss.

Even if the substrate 21a of the input panel 21 located above the light conversion layer 22 is formed of a biaxially stretched film and has birefringence, the display light of the linearly polarized light (7) passes through the substrate 21a and thus the optical Are not affected by

From the above, also in the embodiment shown in FIG. 3, it is possible to prevent the light reflected by the boundary surface between the air gap and the display panel or the electrode layer in the display panel from being sent out together with the display light. In addition, the loss of display light from the display panel can be minimized.

2 case 10 portable device 20 input device 21 input panel 21a substrate 21b first electrode layer 21c second electrode layer 22 light conversion layer 22a polarizing film 22b λ / 4 retardation film 24 cover layer 30 display panel 31 spacer 32 air layer 110 Portable device 130 Display panel 131 λ / 4 retardation film

Claims

In an input device having a translucent input panel,
The input panel is disposed in front of a display panel via an air layer, and converts light from the input panel from linearly polarized light to circularly polarized light between the input panel and the air layer. An input device provided with a light conversion layer to be provided to the air layer.
The input device according to claim 1, wherein the input panel is configured of a translucent base formed of a biaxially stretched resin film, and a translucent electrode layer.
The input device according to claim 1, wherein the input panel is a capacitance detection type that does not include an air layer.
The input device according to any one of claims 1 to 3, wherein the display panel emits display light of linearly polarized light and artificial light which is not circularly polarized light.
The display panel according to any one of claims 1 to 3, wherein the display panel emits linearly polarized display light, and a λ / 4 retardation layer is provided between the display panel and the light conversion layer. Input device.