Liquid crystal display device

• US 6,864,930 B2
• Filed: 07/11/2001
• Issued: 03/08/2005
• Est. Priority Date: 04/01/1998
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Matsushita, Junichi, Aoki, Kunimitsu
• Primary Examiner(s): Plynn, Nathan J.
• Assistant Examiner(s): Sefer, Ahmed N.
• Application Number:
  US09/901,913
• Publication Number:
  US 20030206255A1
• Time in Patent Office: 1,336 Days
• Field of Search: 349/65, 349/61, 349/62, 349 64-110
• US Class Current: 349/65
• 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 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 first uniform luminance indirectly irradiating a first portion of 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 to irradiate a second portion of the liquid crystal panel from the rear side thereof with a second luminance higher than the first luminance.