JP2011107294A - Optical member for display device, and display device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve display quality of a display device by suppressing deterioration of visibility due to reflected light which has not been retroreflected by a retroreflective structure body, in the display devie which includes the retroreflective structure body. <P>SOLUTION: In a viewing side of the display device body 14, an optical member 11 having the retroreflective structure body 12 with a retroreflective structure on one surface, and an antireflection thin film 13 covering the retroreflective structure are arranged so that the retroreflective structure becomes the viewing side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical member used in a display device such as an organic electroluminescence (EL) display device or a liquid crystal display device, and a display device using the optical member.

  Conventionally, when a liquid crystal display device or an organic EL display device is used, the light incident from an external light source (lighting such as sunlight or a fluorescent lamp) that is not caused by the display device itself is reflected on the surface of the display device, thereby improving visibility. May be inhibited. In order to reduce such a decrease in visibility due to incident light from the outside, Patent Document 1 discloses a technique of providing a retroreflective structure on the front surface of the display device. According to this technique, light emitted to a display device from a certain light source is reflected in the direction of the original light source by the retroreflection structure. That is, incident light from the outside is not reflected in directions other than the light source. For this reason, since the incident light from the outside is not reflected in the direction of the observer, a decrease in visibility due to the reflection of the incident light from the outside is suppressed.

JP-A-11-316552

  The retroreflective structure disclosed in Patent Document 1 reflects incident light from the outside in the direction of the light source, but does not reflect all incident light in the direction of the light source. Therefore, a part of the reflected light is visually recognized by the observer, which can lead to a reduction in display quality.

  An object of the present invention is to improve a display quality of a display device by suppressing a decrease in visibility due to reflected light that has not been retroreflected even by the retroreflective structure in a display device including a retroreflective structure. There is.

  A first aspect of the present invention is an optical member for a display device having a retroreflective structure having a retroreflective structure on one side and an antireflection thin film covering the retroreflective structure.

  A second aspect of the present invention is a display device characterized in that the optical member for a display device of the present invention is arranged on the observation side of the display device main body so that the retroreflective structure is located on the observation side.

  According to the present invention, since the antireflection film is provided on the surface of the retroreflective structure, the reflectance of incident light from the outside is greatly reduced, and almost no reflected light reaches the observer. Visibility degradation due to reflection of incident light from is prevented.

It is a cross-sectional schematic diagram of one Embodiment of the display apparatus of this invention. It is explanatory drawing of the unit structure and light ray reflection of the retroreflection structure of one Embodiment of the optical member of this invention. It is explanatory drawing of the retroreflection structure and light beam reflection of other embodiment of the optical member of this invention.

  FIG. 1 is a schematic cross-sectional view of an embodiment of a display device of the present invention. The optical member 11 of the present invention is installed on the viewer side of the display device main body 14. The optical member 11 for display device of the present invention was formed on the surface of the retroreflective structure 12 so as to cover the retroreflective structure 12 and the retroreflective structure 12 provided with the retroreflective structure on one side. It is constituted by the antireflection thin film 13. The retroreflective structure includes a corner cube type disclosed in Japanese Patent Application Laid-Open No. 06-250006, an encapsulated lens type disclosed in Japanese Patent Application Laid-Open No. 5-131589, a capsule lens type disclosed in Japanese Patent Application Laid-Open No. 3-9837, and Japanese Patent Application Laid-Open No. 60-100103. It is a prism type structure of No. gazette. In addition, the antireflective film is provided with a low refractive index layer having an appropriate film thickness on the outermost surface, and a layer such as a high refractive index layer provided below the low refractive index layer as necessary. A plurality of refractive index layers and high refractive index layers may be alternately stacked.

  Light 16 irradiated to the optical member 11 from the light source 15 other than the display device itself, such as the sun or a fluorescent lamp, is retroreflected substantially in the direction of the light source 15 by the retroreflective structure 12 of the optical member 11 (17). . At this time, there is non-recursive reflected light 18 that is reflected not in the direction of the light source 15 but in the direction of the observer. Conventionally, the reflected light 18 has reached the observer and has reduced the visibility, but in the present invention, the intensity of the reflected light 18 is reduced by the antireflection thin film 13 on the retroreflective structure 12, As a result, a decrease in visibility due to the non-recursive reflected light 18 is reduced.

  Although the antireflection phenomenon using a multilayer thin film is well known in the past, the present inventors have found that the antireflection effect by the multilayer thin film can be remarkably increased by combining this with a retroreflective structure. It was. This special effect will be described below.

  FIG. 2 shows an example of a unit structure of the retroreflective structure formed on one side of the retroreflective structure 12 and has a corner cube structure. In the present invention, an antireflection film is formed on the unit structure (not shown in FIG. 2). The retroreflective structure is a collection of a plurality of unit structures having such a retroreflective action.

  In FIG. 2, the light 22 incident on the central part of the unit structure is reflected three times at the central part and reflected in the direction of the light source. However, the light incident on the periphery of the unit structure is reflected twice, not three times, and is reflected in a direction different from the direction of the light source. In addition, even if the light is reflected three times and emitted from the unit structure, the light is reflected at a portion where the edge portion of the unit structure is missing or the edge portion is worn and a desired angle cannot be obtained. Even if it is, it is reflected in a direction different from the light source.

  When the antireflection film is formed at a place where such undesirable non-recursive reflection is performed, the present inventors reflect the incident light 23 a plurality of times, and the effect of the antireflection film is a power. I found out that That is, it is generally known that when an antireflection film is formed on the surface of a parallel plate, the reflectance is generally about 0.1% to 2%. Therefore, when an antireflection film is provided on the retroreflective structure as in the present invention, for example, when incident light is reflected twice, the reflectance becomes the square, that is, 0.0001% to 0.04%, The reflected light can be reduced.

  Therefore, by using the optical member of the present invention for the display device, most of the incident light from the outside is retroreflected and returned to the light source direction, and then enters the peripheral part of the unit structure and is emitted outside the light source direction. Most of the reflected light can be almost eliminated by two reflections on the antireflection film. As a result, the reflected light reaching the observer out of the reflected light on the observation side surface of the display device can be almost eliminated, and good visibility can be obtained.

  As described above, since the optical member of the present invention prevents a decrease in visibility due to incident light incident from the outside on the observation side of the display device, the retroreflective structure is observed on the observation side of the display device body. It arrange | positions so that it may be located in the side. When a protective plate or a circularly polarizing plate for protecting the display surface is provided on the observation side of the display device body, it is provided on the observation side from these.

  As the display device of the present invention, in addition to an organic EL display device and a liquid crystal display device, a field emission display device, an MIM display device, a surface conduction display device using a surface conduction electron-emitting device, a CRT, a fluorescence It is preferably applied to a display tube display device, a plasma display device, and the like.

  Hereinafter, modes for carrying out the present invention will be described.

(Embodiment 1)
In this example, the case where the corner cube shown in FIG. 2 is used as the unit structure of the recursive structure will be described. First, an aluminum plate is excavated using a diamond bite having a tip angle of about 70 ° to form a shape in which convex triangular pyramid shapes are aligned. A concave mold is produced from this aluminum plate by electroforming, and then inverted to produce a convex nickel mold. Using the obtained nickel mold, polymethyl methacrylate (PMMA) resin is injection-molded to produce a PMMA plate having a retroreflective structure on the surface where corner cube structures are aligned.

  Next, an antireflection thin film is formed on the surface of the obtained PMMA plate to obtain the optical member of the present invention. As the antireflection thin film, a single layer or a plurality of layers of materials having a refractive index different from that of PMMA used for the retroreflective structure is used. The film thickness of each layer is preferably determined so that the optical path length is λ / 4 or λ / 2. The value of λ is preferably set between 500 nm and 600 nm, which is the peak of the human visibility curve. As a material, a metal thin film or a dielectric thin film can be used, and magnesium fluoride, magnesium oxide, silicon oxide, or the like may be used.

  In the optical member of the present invention, the surface shape of the antireflection thin film reflects the surface shape of the retroreflective structure as the lower layer, that is, the retroreflective structure.

  In order to measure the surface reflectance of the obtained optical member alone, a sample for reflectance measurement is prepared by applying a black paint (for example, acrylic black paint) on the back surface of the optical member so that reflection on the back surface does not occur. To do. When the surface reflectance of such a sample is measured, a value of 0.1% or less can be obtained, and the effect of reflection multiple times on the antireflection thin film can be confirmed.

  Next, the display member of the present invention is obtained by applying a transparent silicon resin to the observation side surface of a display device body such as an organic EL display device and attaching the optical member to the optical member.

  When the obtained display device is installed under illumination conditions of 100,000 lux and an evaluation image is displayed, it is possible to observe the image satisfactorily without being affected by reflection by external light.

  In this example, silicon resin is applied between the optical member and the display device main body to eliminate the gap between them, but in order to use the optical member also as an impact-resistant structure of the display device, An antireflection film may be further formed on the back surface of the optical member and the display device main body surface.

(Embodiment 2)
In this example, a retroreflective structure in which hemispherical structures having a semicircular cross section are arranged as shown in FIG.

  First, a photosensitive transparent PMMA monomer solution is applied on a parallel plate made of PMMA resin. Next, the coated silica beads are put into a solution and deposited on parallel plates. Next, the solution is irradiated with ultraviolet rays to cure the PMMA resin. When this parallel plate is immersed in a hydrofluoric acid solution, the silica beads are dissolved and only the inverted opal structure of PMMA remains on the parallel plate. When the surface of the obtained PMMA parallel plate is polished to half of the first layer of the inverted opal structure, a PMMA plate having a retroreflective structure having a cross-sectional shape as shown in FIG. 3 can be produced. When the obtained PMMA plate is used as a retroreflective structure and an antireflection film is formed on the surface in the same manner as in Embodiment 1, the optical member of the present invention is obtained. And the display apparatus of this invention is obtained by installing the obtained optical member in the observation side of a display apparatus main body similarly to Embodiment 1. FIG. When the visibility of such a display device is evaluated, it is confirmed that a display image can be observed well without being affected by reflection by external light.

  11: optical member, 12: retroreflective structure, 13: antireflection thin film, 14: display device main body

Claims (5)

  An optical member for a display device, comprising: a retroreflective structure having a retroreflective structure on one side; and an antireflection thin film covering the retroreflective structure.   The optical member for a display device according to claim 1, wherein a surface shape of the antireflection thin film reflects a surface shape of the retroreflective structure.   The optical member for a display device according to claim 1, wherein the retroreflective structure is a corner cube structure.   The optical member for a display device according to claim 1, wherein the retroreflective structure is a hemispherical structure.   5. A display device, wherein the optical member for a display device according to any one of claims 1 to 4 is arranged on the observation side of the display device main body so that the retroreflective structure is located on the observation side.

Images