JP4486715B2 - Liquid crystal display device with low reflection touch panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device with a low-reflection touch panel that reduces the manufacturing cost of the low-reflection touch panel.
[0002]
[Prior art]
Conventionally, liquid crystal display devices are widely used in word processors, notebook computers, mobile phones, PDAs (personal digital assistants), digital cameras, and video cameras, but recently with a touch panel equipped with a touch panel on the front of the liquid crystal display. There is a liquid crystal display device. 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 with a spacer between them. By pressing a part of the contact, it is brought into contact to be electrically conducted so that input can be performed. The transparent conductive film is a metal oxide such as tin oxide, indium oxide, antimony oxide, zinc oxide, cadmium oxide, or ITO, or a metal thin film such as gold, silver, copper, tin, nickel, aluminum, or palladium.
[0003]
However, in the touch panel, when the input work is performed in a room with a fluorescent lamp or the like or outdoors, the transparent conductive film surface reflects light from the outside, and thus the display screen is very difficult to see.
[0004]
In order to solve such problems, Japanese Patent Application Laid-Open No. 10-48625 discloses a two-layer transparent conductive film 5 which is opposed to each other through a first quarter-wave plate 3 and a spacer in order from the liquid crystal display 1 side. A low-reflection touch panel is proposed in which at least a first quarter-wave plate 3 and a second quarter-wave plate 6 in which the optical axis 4 is orthogonal to each other and a polarizing plate 8 are arranged (see FIG. 2). The second quarter-wave plate 6 and the polarizing plate 8 form a circularly polarized antireflection filter, and the reflection of light incident from the outside on the transparent conductive film 5 is efficiently cut. If only one second quarter wave plate 6 is used, the linearly polarized light 2 incident for display from the liquid crystal display 1 side is also changed to circularly polarized light. The phase is canceled by disposing the first quarter-wave plate 3 whose optical axes are orthogonal to each other between the two transparent conductive films 5 and the liquid crystal display 1. That is, after being circularly polarized by the first quarter-wave plate 3, it is returned to the original linearly-polarized light again by the second quarter-wave plate 6. The transparent conductive film 5 is formed on an optically isotropic transparent plate such as an optically isotropic glass plate or an optically isotropic transparent resin film, or the first quarter-wave plate. It may be formed directly on at least one of the third and second quarter wave plates 6.
[0005]
[Problems to be solved by the invention]
However, the low reflection touch panel forming the circularly polarized antireflection filter has a linearly polarized light 2 of 45 ° or 135 with the optical axis 4 of the first quarter wave plate 3 incident from the liquid crystal display 1 side for display. However, the angle between the linearly polarized light 2 emitted from the surface of the liquid crystal display 1 for display and the side of the screen varies depending on the product. The angle formed by the optical axis 4 of the ¼ wavelength plate 3 and the side of the first ¼ wavelength plate 3 also varies depending on the product of the liquid crystal display 1. In many cases, as shown in FIG. 2, the optical axis 4 of the first quarter-wave plate 3 is not parallel or perpendicular to the side of the first quarter-wave plate 3. At this time, since the optical axis 7 of the second quarter-wave plate 6 is also orthogonal to the optical axis 4 of the first quarter-wave plate 3, similarly, the second quarter-wave plate 6 It will not be parallel or perpendicular to the side.
[0006]
In addition, the first quarter-wave plate 3 and the second quarter-wave plate 6 are usually cut from the substantially long quarter-wave plate original 12 to a desired dimension. When the transparent conductive film 5 is directly formed on at least one of the first quarter wavelength plate 3 and the second quarter wavelength plate 6 as described above, the quarter wavelength plate original 12 The transparent conductive film 5 has already been formed on the entire surface by a vacuum vapor deposition method or the like at a stage before cutting from the substrate. The optical axis of the quarter-wave plate original fabric 12 is parallel to the stretching direction during production of the original fabric, that is, the length direction of the original fabric.
[0007]
As a result, the first quarter-wave plate 3 and the second quarter-wave plate 6 are cut so that the sides thereof are inclined with respect to the length direction of the original fabric. (See FIG. 3). If only the quarter-wave plate is considered, the influence on the manufacturing cost is small. However, when the transparent conductive film 5 such as ITO is formed on the original fabric, the manufacturing cost by wasting the transparent conductive film 5 is reduced. The impact of is great.
[0008]
Therefore, an object of the present invention is to solve the above-described problem, and a low-reflection touch panel in which a transparent conductive film is directly formed on the first quarter-wave plate and the second quarter-wave plate. An object of the present invention is to provide a liquid crystal display device with a low-reflection touch panel that suppresses manufacturing costs.
[0009]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention has two layers of transparent layers facing each other through a first quarter-wave plate and a spacer in order from the liquid crystal display side having a polarizing plate for completing a display image in its configuration. A conductive film, a first quarter-wave plate, a second quarter-wave plate whose optical axes are orthogonal to each other, and a polarizing plate are disposed at least, and the first quarter-wave plate and the second quarter are arranged. in the liquid crystal display device with low reflection touch panel provided with a low reflection touch panel is already transparent conductive film made of ITO is formed directly in front of the stage in front of the liquid crystal display cut from quarter-wave plate source in the wavelength plate, wherein The optical axis of the first quarter-wave plate is parallel or perpendicular to the side of the first quarter-wave plate, and the liquid crystal display and the first quarter-wave plate of the low reflection touch panel child placed the polarization direction correction plate between Was thus the angle of about 45 ° or about 135 ° with the optical axis of the linearly polarized light and the first quarter wave plate emitted for display through the polarization direction correction plate.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. In the present invention, the first quarter-wave plate 3 and the second quarter-wave plate 6 give a temporal phase shift (phase difference) to two orthogonally polarized components obtained by decomposing linearly polarized light. Polycarbonate, polyarylate that has the function of changing linearly polarized light into circularly polarized light or substantially circularly polarized light, and has the function of delaying the phase of the polarized light by ¼ wavelength with respect to the incident light having the central wavelength in the visible light region. , A transparent resin plate or film of polyethersulfone, polysulfone, norbornene-based resin or the like. In this case, if the amplitudes of the two orthogonally polarized components are equal, the circularly polarized light is obtained. Otherwise, the elliptically polarized light is obtained. The human visible light region is about 400 nm to 700 nm, in which the peak of visibility is at the central wavelength of about 550 nm. In order to prevent the human eyes from perceiving the reflected light caused by the reflection of indoor fluorescent lamps or outside light from the outside, light reflection at this wavelength is suppressed. The phase difference is obtained by uniaxially stretching a plate material or film material made of the resin or the like in an unstretched state, and the refractive index in the x direction that is the stretching direction (optical axis direction) and the refraction in the y direction orthogonal to the x direction. By controlling the refractive index and the refractive index in the thickness direction, that is, the z direction orthogonal to the x and y directions.
[0011]
The first quarter-wave plate 3 and the second quarter-wave plate 6 are composed of one or more low-reflection touch panels from a substantially long quarter-wave plate original 12 given a phase difference by stretching. It is cut into a desired dimension such as a piece. The optical axis 4 of the first quarter-wave plate 3 of the present invention is parallel or perpendicular to the side of the first quarter-wave plate 3. Further, since the optical axis 7 of the second quarter-wave plate 6 is also orthogonal to the optical axis 4 of the first quarter-wave plate 3, it is parallel to the side of the second quarter-wave plate 6. Or it is vertical. That is, the sides of the first quarter-wave plate 3 and the second quarter-wave plate 6 can be cut without being inclined with respect to the length direction of the original fabric, and the original fabric is not wasted. I'm sorry.
[0012]
The second quarter-wave plate 6 is combined with the polarizing plate 8 on the front surface to form a circularly polarized antireflection filter. Reflection of the indoor fluorescent lamp and outdoor outside light pass through the polarizing plate 8 and become linearly polarized light and pass through the second quarter-wave plate 6 to become circularly polarized light. Since the circularly polarized light passes through the second quarter-wave plate 6 again and becomes linearly polarized light perpendicular to the transmission axis of the polarizing plate 8, the reflected light is suppressed. The second quarter-wave plate 6 is a flexible one that facilitates input with a pen or a finger.
[0013]
The first quarter-wave plate 3 cancels the phase by being disposed between the two-layer transparent conductive film 5 and the liquid crystal display 1 so that the optical axis is orthogonal to the second quarter-wave plate 6. It is something to make. That is, linearly polarized light incident on the first quarter-wave plate 3 for display from the liquid crystal display 1 side becomes circularly-polarized light by passing through the first quarter-wave plate 3, but the second 1 By passing through the / 4 wavelength plate 6, it returns to linearly polarized light again, and passes through the polarizer 8 as it is.
[0014]
The polarizing plate 8 disposed in front of the second quarter-wave plate 6 is combined with the second quarter-wave plate 6 to form a circularly polarized antireflection filter . The absorption axis of the polarizing plate 8 disposed in front of the second quarter wavelength plate 6 is formed to be 45 ° or 135 ° with the optical axis 7 of the second quarter wavelength plate 6. Further, on the polarizing plate 8, an antiglare treatment, an antifouling treatment, an antireflection treatment, or the like may be directly applied, or a film subjected to an antiglare treatment, an antifouling treatment, an antireflection treatment or the like may be attached. .
[0015]
The two layers of transparent conductive film 5 are opposed to each other via a spacer and become an electrode of a touch panel. As a material of the transparent conductive film 5, an ITO thin film is 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 is directly formed on each of the first quarter wavelength plate 3 and the second quarter wavelength plate 6 (see FIG. 1). The first quarter-wave plate 3 and the second quarter-wave plate 6 have the transparent conductive film 5 already formed at a stage before being cut from the quarter-wave plate original 12. This is because the transparent conductive film 5 can be continuously formed by making the quarter-wave plate original fabric 12 into a roll shape, so that the transparent conductive film 5 is formed after cutting from the quarter-wave plate original fabric 12. This is more advantageous in terms of productivity than
[0016]
The spacer is formed on the surface of one of the transparent conductive films 5 (not shown in the figure). The spacer can be obtained by forming a transparent photocurable resin into fine dots by a photo process. Also, a large number of fine dots can be formed by a printing method to form a spacer. In addition, the members directly forming the transparent conductive film 5 of the low-reflection touch panel are bonded only outside the display area by a double-sided adhesive tape or a transparent adhesive.
[0017]
The polarization direction correction plate 10, which is a feature of the present invention, has an optical axis 4 of the first quarter wavelength plate 3 between the liquid crystal display 1 and the first quarter wavelength plate 3 of the low reflection touch panel. 1 was arranged so as to be parallel or perpendicular to the side of the quarter-wave plate 3. That is, the polarization direction correction plate 10 passes through the optical axis 4 of the first quarter wavelength plate 3 that is parallel or perpendicular to the side of the first quarter wavelength plate 3 and the polarization direction correction plate 10. The phase difference and the optical axis direction are set according to the linearly polarized light 2 emitted from the surface of the liquid crystal display 1 for display so that the angle formed with the linearly polarized light 11 emitted for display is about 45 ° or about 135 °. The The retardation of the polarization direction correction plate 10 is a plate-like shape such as polyvinyl alcohol resin, polycarbonate resin, acrylic resin, polyester resin, polyarylate resin, polyethersulfone resin, polysulfone resin, norbornene resin, or the like. A film-like material is used, and the desired value is set by adjusting the stretching conditions as described above. The angle between the linearly polarized light 11 that has passed through the polarization direction correcting plate 10 and emitted for display and the optical axis 4 of the first quarter-wave plate 3 is about 45 ° or about 135 °. This is because the linearly polarized light incident from the liquid crystal display 1 side in the quarter wave plate 3 of 1 is changed to circularly polarized light.
[0018]
Further, in order to give rigidity to the low reflection touch panel itself, an optically isotropic glass plate or an optically isotropic resin is further provided as a support between the first quarter-wave plate 3 and the liquid crystal display 1 side. It is good also as a structure which has arrange | positioned the board.
[0019]
Moreover, in the liquid crystal display device with a low-reflection touch panel having the above-described configuration, one or more pairs of the front and rear members may be bonded to each other except between the members directly forming the transparent conductive film 5 of the low-reflection touch panel. It may be simply arranged. Lamination can be performed only outside the display area with a double-sided adhesive tape, or over the entire surface with a transparent adhesive or a transparent re-peeling sheet.
[0020]
【The invention's effect】
Since the liquid crystal display device with a low reflection touch panel according to the present invention is configured and operated as described above, the following effects can be obtained.
[0021]
That is, in the liquid crystal display device with low reflection touch panel provided with a low reflection touch panel first quarter-wave plate and the second transparent conductive film to a quarter wavelength plate is formed directly on the front face of the liquid crystal display, wherein The optical axis of the first quarter-wave plate is parallel or perpendicular to the side of the first quarter-wave plate, and the liquid crystal display and the first quarter-wave plate of the low reflection touch panel By arranging a polarization direction correction plate between them, the angle between the linearly polarized light that has passed through the polarization direction correction plate and emitted for display and the optical axis of the first quarter-wave plate is about 45 ° or about Since the angle is set to 135 °, when a large number of first quarter-wave plates or second quarter-wave plates are cut from a quarter-wave plate original on which a transparent conductive film made of ITO has been entirely formed. The first quarter-wave plate or the second 1 / By making the sides of the four-wavelength plate parallel to the length direction of the original fabric, it is possible to eliminate a wasteful portion. Therefore, since the transparent conductive film is not wasted, it is possible to obtain a liquid crystal display device with a low reflection touch panel that suppresses the manufacturing cost of the low reflection touch panel.
[Brief description of the drawings]
FIG. 1 is an exploded view showing an optical arrangement of a main part in an example of a liquid crystal display device with a low-reflection touch panel according to the present invention.
FIG. 2 is an exploded view showing an optical arrangement of main parts in an example of a liquid crystal display device with a low-reflection touch panel according to the prior art.
FIG. 3 is a cut-out of a first quarter-wave plate or a second quarter-wave plate having a desired optical axis angle in a quarter-wave plate original with a manufacturing width in which a transparent conductive film is formed on the entire surface . FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal display 2 Linearly polarized light 3 1st 1/4 wavelength plate 4 Optical axis 5 Transparent electrically conductive film 6 2nd 1/4 wavelength plate 7 Optical axis 8 Polarizing plate 9 Optically isotropic transparent plate 10 Polarization direction correction plate 11 Linearly polarized light 12 1/4 wave plate original

Claims (1)

A first quarter-wave plate, a two-layer transparent conductive film facing each other through a spacer, a first quarter-wave plate and light in order from the liquid crystal display side having a polarizing plate for completing a display image in its configuration Before the first quarter-wave plate and the second quarter-wave plate are cut from the quarter-wave plate original, with at least a second quarter-wave plate and a polarizing plate having orthogonal axes. In the liquid crystal display device with a low-reflection touch panel provided with a low-reflection touch panel in which a transparent conductive film made of ITO is directly formed at the stage of the liquid crystal display, the optical axis of the first quarter-wave plate is By arranging a polarization direction correction plate between the liquid crystal display and the first quarter wavelength plate of the low reflection touch panel , which is parallel or perpendicular to the side of the first quarter wavelength plate , It passes through the polarization direction correction plate The emitted linearly polarized light and the first quarter-wave plate liquid crystal display device with low reflection touch panel, characterized in that the angle was about 45 ° or about 135 ° with the optical axis of the use.

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