Liquid crystal display device

• US 20030206255A1
• Filed: 07/11/2001
• Published: 11/06/2003
• Est. Priority Date: 04/01/1998
• Status: Active Grant

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Aoki, Kunimitsu, Matsushita, Junichi
• Granted Patent: US 6,864,930 B2
• Time in Patent Office: Days
• US Class Current: 349/113
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

An LCD provided with an edge light type back light unit which is arranged in a manner that the light emitted from a CCT in the form of a linear light source is condensed at the end portion of a light conduction plate, then the light reflected by a reflecting sheet and then ejected from the light conduction plate transmits through a light diffusion plate thereby to indirectly irradiate on a liquid crystal panel from the rear direction thereof in the form of planar light with uniform luminance. A light reflecting plate having a curved surface is disposed in the vicinity of the CCT. A light shielding plate is disposed in a manner that a part of the light emitted from the CCT and reflected by the light reflecting plate is condensed at the end portion of the light conduction plate. Another part of the light emitted from the CCT and reflected by the light reflecting plate is directed upward and directly irradiates a part of the display area of the liquid crystal panel thereby to form a high luminance irradiation portion. Accordingly, thus configured LCD is improved in its visibility and so can be formed as a vehicle-mounted alarm display device for displaying various alarms.

Claims

1. A liquid crystal display device including an edge light type back light unit in which light emitted from a linear light source is condensed at an end portion of a light conduction plate, then conducted and reflected, and a reflected light ejected from the light conduction plate is transmitted through a light diffusion plate to form a planar light source with a uniform luminance thereby to indirectly irradiate a liquid crystal panel from a rear side thereof,

wherein a reflecting plate having a curved surface is disposed in a vicinity of the linear light source, and a light shielding plate is disposed so that a part of the light emitted from the linear light source and reflected by the reflecting plate is condensed at the end portion of the light conduction plate, whereby another part of the light emitted from the linear light source and reflected by the reflecting plate is directly irradiated with a higher luminance on a part of a display area of the liquid crystal panel than that of another part of the display area.

2. The liquid crystal display device according to claim 1, wherein the linear light source is disposed so as to face on at least one end portion of the light conduction plate.

3. The liquid crystal display device according to claim 1, wherein the light diffusion plate is extended to be positioned between the linear light source and the liquid crystal panel, whereby another part of the light emitted from the linear light source and reflected by the reflecting plate is transmitted through the extended portion of the light diffusion plate and irradiated with a higher luminance on apart of the display area of the liquid crystal panel than that of another part of the display area.

4. A liquid crystal display device including an under light type back light unit in which light emitted from a plurality of linear light sources is reflected by a reflecting sheet disposed at a rear side of the plurality of linear light sources, then transmitted through a light modulation film and a light diffusion plate to form a planar light source with a uniform luminance thereby to indirectly irradiate a liquid crystal panel from a rear side thereof,

wherein one end portion of the light modulation film is shielded by a light shielding plate, and light emitted from one of the plurality of linear light sources is shielded by the light shielding plate and transmitted through only the light diffusion plate thereby to directly irradiate with a higher luminance on a part of a display area of the liquid crystal panel than that of another part of the display area.