Liquid Crystal Display Device

• US 20080303977A1
• Filed: 06/10/2008
• Published: 12/11/2008
• Est. Priority Date: 06/11/2007
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Kaneko, Hiroki, Hiyama, Ikuo, SEKIGUCHI, Yoshifumi
• Granted Patent: US 8,212,963 B2
• Time in Patent Office: Days
• US Class Current: 349/64
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G02F 1/133628 with cooling means

Abstract

An object of the present invention is to provide a liquid-crystal display device which includes a diffuser board that does not produce striped mura on the surface of a liquid crystal panel even if point light sources are used as light sources of a backlight.

A backlight apparatus 103 is provided with a diffuser board 103b having diffusion portions 103b1. At each of the diffusion portions 103b1, the light L emitted by a LED module 104 included in a light source unit 103a is reflected by prism patterns P and diffused around the LED module 104. Then, the diffused light is reflected again by a reflecting surface formed on the inner surface of a housing 103c and emitted from the backlight apparatus 103, thereby achieving illuminating light without mura.

Claims

1. A liquid-crystal display device comprising:

a liquid crystal panel;

a light source unit which illuminates the liquid crystal panel from the back surface thereof; and

a diffuser board which is provided between the light source unit and the liquid crystal panel to diffuse the light emitted by the light source unit;

wherein the light source unit includes a housing having an open surface and also includes a plurality of point light sources arranged on a surface in the housing opposing the open surface to emit light toward the open surface;

wherein the diffuser board is provided so as to cover the open surface of the housing, and diffusion portions formed by diffusion patterns, the surfaces of which are convexly raised, are formed on the surface of the diffuser board opposite to the housing according to the number of the plurality of point light sources; and

wherein the diffusion portions are arranged at positions corresponding to the positions of the point light sources.

2. The liquid-crystal display device according to claim 1, wherein:

each of the diffusion patterns includes a prism pattern in which the apex of a convex formed by the surface of the diffuser board being raised to have a triangular cross-section is continuously formed to form a circle; and

when a plurality of prism patterns are arranged, they are concentrically arranged.

3. The liquid-crystal display device according to claim 1, wherein:

each of the diffusion patterns includes

a micro lens formed by the surface of the diffuser board being raised to have a circular cone or a pyramid and

a prism pattern in which a convex formed by the surface of the diffuser board being raised to have a triangular cross-section is continuously formed so as to surround the micro lens; and

when a plurality of prism patterns are arranged, they are arranged so as to extend outwardly with the micro lens as a center.

4. The liquid-crystal display device according to claim 1, wherein:

each of the diffusion patterns includes a micro lens formed by the surface of the diffuser board being raised to have a circular cone or a pyramid; and

when a plurality of micro lenses are arranged, they are arranged so that the apexes thereof are arranged on the circumference of a circle, when viewed from a normal-line direction with respect to the surface of the diffuser board, the normal-line direction being defined as a direction perpendicular to and heading toward the surface of the diffuser board.

5. The liquid-crystal display device according to claim 1, wherein:

each of the diffusion patterns includes a micro lens formed by the surface of the diffuser board being raised to have a circular cone or a pyramid; and

when a plurality of micro lenses are arranged, they are arranged so that the apexes thereof surround a predetermined point on the diffuser board, when viewed from a normal-line direction with respect to the surface of the diffuser board, the normal-line direction being defined as a direction perpendicular to and heading toward the surface of the diffuser board.

6. The liquid-crystal display device according to claim 5, wherein:

the point light sources are LEDs each covered by a lens;

each of the diffusion patterns includes a micro lens formed by the surface of the diffuser board being raised to have a circular cone or a pyramid; and

when a plurality of micro lenses are arranged, the diffuser board is arranged so as to cover the open surface of the housing, and the micro lenses are arranged around the central portion of the lens so that the apexes of the micro lenses surround the central portion of the lens, when viewed from the normal-line direction with respect to the surface of the diffuser board.

7. The liquid-crystal display device according to claim 1, wherein:

each of the diffusion patterns includes a micro lens formed by the surface of the diffuser board being raised to have a circular cone or a pyramid; and

the micro lenses are arranged around a central position corresponding to the position of the point light source, the micro lenses differing in shape at a position near the central position and at a position distant from the central position, the micro lenses equidistant from the central position having almost the same shape.

8. A liquid-crystal display device comprising:

a liquid crystal panel;

a light source unit which illuminates the liquid crystal panel from the back surface thereof; and

a diffuser board which is provided between the light source unit and the liquid crystal panel and has diffusion patterns for diffusing the light emitted by the light source unit formed thereon;

wherein the light source unit includes a housing having an open surface and also includes a plurality of LEDs arranged on a surface in the housing opposing the open surface so as to emit light toward the open surface;

wherein each of the LEDs is covered by a lens which diffuses the light emitted therefrom; and

wherein each of the diffusion patterns includes a micro lens formed by the surface of the diffuser board being raised to have a circular cone or a pyramid.