Area light source device and liquid crystal display apparatus including the same

• US 20060098455A1
• Filed: 10/28/2005
• Published: 05/11/2006
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Inventors: Yasuda, Yoshinori, Ura, Toshihiko
• Granted Patent: US 7,270,463 B2
• Time in Patent Office: Days
• US Class Current: 362/615
• 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 6/0071 with elongated shape, e.g. tube
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

An area light source device includes an L-shaped cold-cathode fluorescent lamp, a wedge-shaped light guide having an incidence surface, on which emission light from the cold-cathode fluorescent lamp is incident, and a reflector that surrounds the cold-cathode fluorescent lamp, has an opening facing the incidence surface, and reflects the emission light from the cold-cathode fluorescent lamp toward the light guide, wherein the opening of the reflector has a shape corresponding to shapes of two mutually neighboring incidence surfaces of the light guide.

Claims

1. An area light source device comprising:

an L-shaped light source;

a wedge-shaped light guide having an incidence surface, on which emission light from the light source is incident, and an emission surface from which incident light that is incident from the incidence surface is emitted;

an optical sheet that is disposed on the emission surface; and

a reflector that surrounds the light source, has an opening facing the incidence surface, and reflects the emission light from the light source toward the light guide,

wherein the opening of the reflector has a shape corresponding to shapes of two mutually neighboring incidence surfaces of the wedge-shaped light guide.

2. The area light source device according to claim 1, wherein the incidence surface of the light guide includes a first incidence surface with a substantially uniform width, and a second incidence surface that neighbors the first incidence surface and has a width decreasing from one end to the other end thereof, and

the opening of the reflector includes a first opening portion that corresponds to the first incidence surface and has a substantially uniform opening width, and a second opening portion that corresponds to the second incidence surface and has an opening width gradually decreasing from one end toward the other end thereof.

3. The area light source device according to claim 1, wherein the reflector has a substantially uniform gap that accommodates the light source.

4. A liquid crystal display device comprising:

a liquid crystal display panel including an effective display section in which a plurality of display pixels are arranged; and

an area light source device that illuminates the liquid crystal display panel,

the area light source device including;

an L-shaped light source;

a wedge-shaped light guide having an incidence surface, on which emission light from the light source is incident, and an emission surface from which incident light that is incident from the incidence surface is emitted;

an optical sheet that is disposed on the emission surface; and

a reflector that surrounds the light source, has an opening facing the incidence surface, and reflects the emission light from the light source toward the light guide,

wherein the opening of the reflector has a shape corresponding to shapes of two mutually neighboring incidence surfaces of the wedge-shaped light guide.

5. The liquid crystal display device according to claim 4, wherein the incidence surface of the light guide includes a first incidence surface with a substantially uniform width, and a second incidence surface that neighbors the first incidence surface and has a width decreasing from one end to the other end thereof, and

the opening of the reflector includes a first opening portion that corresponds to the first incidence surface and has a substantially uniform opening width, and a second opening portion that corresponds to the second incidence surface and has an opening width gradually decreasing from one end toward the other end thereof.

6. The liquid crystal display device according to claim 4, wherein the reflector has a substantially uniform gap that accommodates the light source.