Anti-reflection sheet, display element and display device

Abstract

An anti-reflection sheet is formed in a manner of forming a resin layer, which has many fine projections 12, on a flat and smooth surface of a transparent substrate 11. Transparent resin is molded into the projections 12, the projections 12 have an almost quadratic function-shaped cross section including a center axis C perpendicular to the surface of the substrate 11, and a surface of the projection 12 is preferably a rotational paraboloid. A ratio (aspect ratio) b / a of a height b and width a of the projection 12 is 1 or less. Additionally, an arranged pitch P of the projections 12 is not more than half of a wavelength of incident light.

Description

TECHNICAL FIELD[0001]The present invention relates to an anti-reflection sheet, a display element and a display device. Specifically, the present invention relates to an anti-reflection sheet for preventing reflection of light in a specified wavelength band, and to a display element, such as an organic EL or liquid crystal display (LCD) panel, and a display device, the element and device having the anti-reflection sheet or sheets.BACKGROUND ART[0002]When external light such as sunlight or indoor illumination light reflects on a screen of a display device, contrast of the screen lowers, the screen becomes white and it becomes hard to view an image. In order to prevent such a phenomenon, an anti-reflection film has been conventionally proposed which is adhered to a surface of a display device and prevents reflection of external light.[0003]Such an anti-reflection film is disclosed in, for example, Japanese Published Unexamined Patent Application No. 2002-122702 (Patent Document 1). Th...

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Benefits of technology

[0009]The present invention has been made in view of the above technical problems and aims to provide an anti-reflection sheet capable of improving wear-resistance and pressure-resistance of projections without lowering optical properties, such as a low reflectance and a low haze value, of the anti-reflection sheet.Means for Solving the Problems

[0012]Additionally, in the anti-reflection sheet of the present invention, since the shape of the cross section, which includes the center axis perpendicular to the surface of the substrate, of the projections or recesses is in the shape of the quadratic function having a correlation coefficient of 0.8 or more, a tip of the projections or recesses is not pointed differently from that of a pyramid-shaped or conic projection or recess, wear-resistance and pressure-resistance are improved and wear and damage do not easily occur. Additionally, since the shape of the cross section of the projections or recesses is in the shape of the quadratic function having a correlation coefficient of 0.8 or more, preferred optical properties equivalent to those of the pyramid-shaped projection or recess can be obtained.

[0020]In an anti-reflection sheet according to still another embodiment of the present invention, the thickness of the resin layer having the projections or recesses is 11 μm or more. According to the embodiment, light reflecting on a surface of the resin layer and light reflecting on a backside of the layer can be prevented from generating an interference fringe.

[0022]Additionally, the projections or recesses of the anti-reflection sheet of the present invention may be formed on a face, which is arranged toward an observer, of the substrate, or formed on the face, which is arranged toward an observer, and a face opposite thereto of the substrate. Since the projections and recesses are not easily crushed and are durable even if the anti-reflection sheet of the present invention is rubbed or pressed, a light anti-reflection function is not easily impaired even if the projections or recesses are formed on the face, which is arranged toward an observer, of the substrate. Additionally, when the projections or recesses are formed on both the face, which is arranged toward an observer, and the face opposite thereto of the substrate, the anti-reflection effect is further improved.

[0024]In a display element according to the present invention, the anti-reflection sheet is provided on a surface of a display panel. Since the display element includes the anti-reflection sheet of the present invention, external light such as sunlight or indoor illumination light is not easily reflected, contrast of a screen is kept, and visibility can be made excellent. Further, since the anti-reflection sheet has wear-resistance and pressure-resistance, external force does not easily impair the function of the anti-reflection sheet.

[0025]A display device according to the present invention includes a display panel and a transparent protective plate arranged opposite to a face on an image generation side of the display panel, and the anti-reflection sheet is provided on at least one of both front and back faces of the transparent protective plate. Since the display device includes the anti-reflection sheet of the present invention, external light such as sunlight or indoor illumination light is not easily reflected, contrast of a screen is kept and visibility can be made excellent. Further, since the anti-reflection sheet has wear-resistance and pressure-resistance, external force does not easily impair the function of the anti-reflection sheet.

Problems solved by technology

When external light such as sunlight or indoor illumination light reflects on a screen of a display device, contrast of the screen lowers, the screen becomes white and it becomes hard to view an image.

When a surface of the anti-reflection film is rubbed with a soft cloth or cleaner to wipe sebaceous matter, dirt deposited on the surface of the anti-reflection film, the pyramid-shaped or conic projections are easily worn down and crushed, and an anti-reflection function of the anti-reflection film is easily impaired.

Similarly, when the transparent protective plate is strongly pushed by a finger, the projections on the surface are crushed and the anti-reflection function is easily impaired.

Also in this case, when the transparent protective plate is pushed by a finger or a touch pad pen, the transparent protective plate comes into contact with the display element, and thus, in some cases, the projections of the anti-reflection film are crushed by pressure, and the anti-reflection function of the anti-reflection film is lowered and impaired.

However, in the case where the anti-reflection film having such protection poles is provided on a surface of equipment, when the anti-reflection film is wiped with a soft cloth, feathered cloth or the like, the cloth or the like passes over the protection poles and comes into contact with the projections of the anti-reflection film, and the projections are destroyed.

Additionally, also in the case where the anti-reflection film is provided on an inner face of a display device or the like, there is a possibility that the protection poles are damaged depending on the height of the protection poles or in the method of applying force.

Additionally, in the anti-reflection film disclosed in Patent Document 2, a reflectance of light becomes large owing to the protection poles thereby impairing a low reflectance property of the anti-reflection film, and a haze value becomes large owing to the protection poles thereby making an optical property poor.

Additionally, in the case where the anti-reflection film having the micron-order protection poles thereon is used for a high-definition display device, the protection poles are viewed through a screen thereby causing a defect on an image.

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