JP2006162788A - Antireflection plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection plate, which emits light beams having no irregularity and no dark portion and good color reproducibility by maintaining uniform antireflection within a surface, at a low cost and with good productivity. <P>SOLUTION: Many minute projecting and recessing parts 16 are formed on a curved second surface 12b of an antireflection plate 12. Every one of the projecting and recessing parts is formed so that it is extended toward one point of a surface center line L which goes through the surface center of the curved second surface 12b (a curved surface). Thus, the projecting and recessing parts 16, as they are formed in the vicinity of the outer edges of the second surface 12b, are more greatly tilted and projected toward the surface center line L. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antireflection plate formed on a display surface of an electronic device such as a liquid crystal display panel, and a liquid crystal display device using the same.

  For example, liquid crystal display devices are widely used as display means in mobile terminals such as mobile phones and PDFs. In such a liquid crystal display device, the cover glass is often composed of an antireflection plate so that the light emitted from the liquid crystal display panel is reflected by the cover glass covering the surface and the display looks unclear or the contrast is not lowered. .

The antireflection plate provided on the surface of such a liquid crystal display device is a liquid crystal display for the purpose of keeping the brightness uniform at the peripheral and central portions in the surface, or for improving the strength of the surface in a touch panel type liquid crystal display device. Some of the inner side facing the display panel has a curved surface that is recessed from the outer edge toward the center of the surface. An antireflection plate having an antireflection film formed on the curved surface has been conventionally known.
JP 2002-243903 A

  However, since the conventional antireflection plate has a structure that reduces the reflection of light by adjusting the thickness of the formed reflection film, the antireflection effect becomes weaker as the emitted light is inclined from the film thickness direction of the reflection film. There was uneven illuminance in the surface, and visibility was difficult. In addition, in the method of adjusting the film thickness of the reflective film, there is a difference in the effect of antireflection for each wavelength in display light such as a full-color image having a wide wavelength range of emitted light, and the color reproducibility is reduced. There was also. Furthermore, in order to form such a reflective film with a curved surface, a vapor deposition process is required, and thus there is a problem that the cost is high and the productivity is low.

  The present invention has been made in view of the above circumstances, and an antireflection plate capable of emitting light with excellent color reproducibility without unevenness and dark portions by keeping the antireflection property in the plane low-cost is provided. And it aims at providing with good productivity.

  In order to achieve the above object, according to the present invention, a second surface that extends on a display surface of an electronic device, a first surface opposite to the display surface forms a flat surface, and a second surface that faces the display surface is provided. An antireflection plate comprising a curved surface that is recessed from the outer edge toward the center of the surface and a plurality of fine irregularities extending in the surface center line direction of the curved surface is formed on the curved surface. .

  The irregularities may be formed in a staggered arrangement on the curved surface. The formation pitch of the unevenness may be set to 150 to 300 nm. Moreover, the height of the unevenness may be set to 150 nm or more and 400 nm or less.

  According to the invention, there is provided a liquid crystal display device comprising the antireflection plate and a liquid crystal display panel.

  According to the antireflection plate of the present invention, a large number of fine irregularities formed on the curved second surface of the antireflection plate extend in the surface center line direction of the curved surface, so that the peripheral portion of the antireflection plate Even if a light beam greatly inclined from the normal direction is incident on the angle, the light can be refracted and emitted in the first surface direction without being reflected by the second surface.

  As a result, the antireflection effect is properly maintained up to the peripheral portion of the antireflection plate, the light emitted from the first surface of the antireflection plate can be kept at a uniform and uniform light amount, and the visibility of the liquid crystal display panel Can be greatly enhanced. In addition, the antireflection effect due to the unevenness extending in one direction is not dependent on the wavelength of the emitted light, unlike a conventional antireflection film by adjusting the film thickness. It becomes possible to transmit light having a wide wavelength without reducing the color reproducibility.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a touch panel type liquid crystal display device provided with the antireflection plate of the present invention. The liquid crystal display device 10 of the present embodiment includes a liquid crystal display panel 11, an antireflection plate 12 that covers the display surface side of the liquid crystal display panel 11, and a backlight 13 that illuminates the liquid crystal display panel 11 from the back surface side. Yes.

  The liquid crystal display device 10 includes, for example, a touch panel type input mechanism, and can perform operations such as selection and instruction by pressing with a pointed object such as a pen 14 from the first surface 12a side of the antireflection plate 12. it can. The backlight 13 illuminates the liquid crystal display device 10 from the back to illuminate the display of the liquid crystal display panel 11 so that the display surface 11 a of the liquid crystal display panel 11 can be clearly observed through the antireflection plate 12. Such a backlight 13 should just be comprised from light sources, such as LED, for example, and the light-guide plate which formed many cross-section triangular protrusions on the surface.

  As shown in FIGS. 1 and 2, the antireflection plate 12 is formed of, for example, a transparent resin as a whole. In the antireflection plate 12, the first surface 12a that is the opposite surface to the display surface 11a of the liquid crystal display panel 11 forms a flat surface. Further, the second surface 12b facing the display surface 11a of the liquid crystal display panel 11 forms a curved surface that is recessed from the outer edge toward the center of the surface.

  3 and 4 are enlarged cross-sectional views showing details of the antireflection plate. A large number of fine irregularities 16 are formed on the curved second surface 12 b of the antireflection plate 12. Each of the irregularities 16 is formed so as to extend toward one point of a plane center line L passing through the center of the curved second surface 12b (curved surface). For this reason, as the unevenness 16 is formed near the outer edge of the second surface 12b, the unevenness 16 protrudes with a greater inclination toward the surface center line L. Such irregularities 16 may be arranged on the second surface 12b in the form of, for example, a matrix or a staggered pattern. Such irregularities 16 may be formed at a pitch of about 150 to 300 nm. Moreover, the height of each unevenness | corrugation should just be formed in 150 nm-400 nm.

  In addition to the conical shape of the triangular section as in the embodiment described above, the shape of the irregularities 16 is, for example, as shown in FIG. 5, a projection having an elliptical section (see FIG. 5a), and the section is curved at an acute angle. Various antireflection shapes such as a protrusion (see FIG. 5b), a protrusion with a rectangular cross section (see FIG. 5c), and a protrusion with a right triangular section (see FIG. 5d) can be adopted.

  In this way, a large number of fine irregularities 16 formed on the curved second surface 12b of the antireflection plate 12 are directed toward one point of the surface center line L passing through the surface center of the curved second surface 12b (curved surface). Even if a light ray M greatly inclined from the normal direction of the first surface 12a of the antireflection plate 12 is incident on the peripheral edge portion of the antireflection plate 12, as shown in FIG. The light can be refracted in the direction of the first surface 12a without being reflected by the surface 12b.

  Accordingly, the antireflection effect is properly maintained up to the peripheral portion of the antireflection plate 12, and the light emitted from the first surface 12a of the antireflection plate 12 can be maintained at a uniform and uniform light amount. 11 can be greatly improved. Further, the antireflection effect due to the concavo-convex 16 extending in one direction is not dependent on the wavelength of the emitted light, unlike the antireflection film by adjusting the film thickness, and the full color image. It is possible to transmit light having a wide range of wavelengths without degrading color reproducibility.

  In manufacturing such an antireflection plate 12, a mold that embodies fine irregularities 16 is formed by a technique such as a semiconductor process, and the mold is used for transfer molding with resin, or a semiconductor is formed on the resin plate. What is necessary is just to form the unevenness | corrugation 16 directly by methods, such as a process.

  The present applicant verified the effect of the antireflection plate of the present invention. In the verification, an antireflection plate similar to that of the above-described embodiment was prepared. Further, as a comparative example (conventional example), an antireflection plate in which a conventional antireflection film was formed on a curved second surface of a resin plate was prepared. And the change (incidence angle dependence) of the reflectance by the incident angle of incident light of the antireflection plate of this invention and the antireflection plate which formed the conventional antireflection film was verified. Such verification results are shown in FIG.

  According to the verification results shown in FIG. 6, the antireflection plate of the present invention is different from the conventional antireflection plate (comparative example) in that the reflectance varies greatly as the incident angle of incident light increases. It was confirmed that even when the incident angle of incident light was increased, the variation in reflectance was kept low. Therefore, it was confirmed that if the antireflection plate of the present invention is used, it can be transmitted through the entire surface of the antireflection plate with a uniform amount of light without unevenness.

FIG. 1 is a cross-sectional view showing a liquid crystal display device provided with the antireflection plate of the present invention. FIG. 2 is an external perspective view showing the antireflection plate of the present invention. FIG. 3 is an enlarged cross-sectional view showing the antireflection plate of the present invention. FIG. 4 is an enlarged cross-sectional view showing the unevenness of the antireflection plate. FIG. 5 is an enlarged cross-sectional view showing unevenness variations formed on the antireflection plate. FIG. 6 is a graph showing the verification results of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 11 Liquid crystal display panel 12 Antireflection board 12a 1st surface 12b 2nd surface 16 Concavity and convexity

Claims (5)

  The first surface opposite to the display surface is a flat surface extending on the display surface of the electronic device, and the second surface facing the display surface is a curved surface recessed from the outer edge toward the surface center. An antireflection plate, wherein a large number of fine irregularities extending in the surface center line direction of the curved surface are formed on the curved surface.   The antireflection plate according to claim 1, wherein the irregularities are formed in a staggered arrangement on the curved surface.   The antireflection plate according to claim 1, wherein the uneven pitch is set to 150 to 300 nm.   The antireflection plate according to any one of claims 1 to 3, wherein the height of the unevenness is set to 150 nm or more and 400 nm or less.   A liquid crystal display device comprising the antireflection plate according to claim 1 and a liquid crystal display panel.

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