Backlight device and liquid crystal display device

• US 20040125592A1
• Filed: 12/03/2003
• Published: 07/01/2004
• Est. Priority Date: 12/06/2002
• Status: Active Grant

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Yamamoto, Koichi, Nagakubo, Hideaki
• Granted Patent: US 6,981,792 B2
• Time in Patent Office: Days
• US Class Current: 362/31
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0048 with stepwise taper
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Abstract

A backlight device 10 wherein a light source 13 and a light guide plate 12 for introducing light components from the light source 13 from the incident surface 12a provided on an end surface to emit the light from the surface 12b are included, a plurality of the wedge-shaped grooves 12e are formed on the surface 12b of the light guide plate 12 in stripes in plan view, and micro-irregularities 12g are formed between adjacent wedge-shaped grooves 12e is disclosed. A liquid crystal display device 1 having the backlight device 10 formed on the back surface of the liquid crystal display unit 20 is disclosed.

Claims

1. A backlight device, comprising:

a light source, and

a light guide plate for introducing light components from the light source from an incident surface provided on an end surface to emit from a surface thereof,

wherein the surface of the light guide plate has a plurality of wedge-shape grooves in stripes in a plan view and a light diffusion surface having micro-protrusions formed between adjacent wedge-shaped grooves.

2. A backlight device according to claim 1, wherein the extended direction of the wedge-shaped grooves formed in the surface of the light guide plate is parallel to the incident surface of the light guide plate.

3. A backlight device according to claim 1, wherein the extended direction of the micro-protrusions formed in the surface of the light guide plate is parallel to the incident surface of the light guide plate or is perpendicular to the incident surface of the light guide plate.

4. A backlight device according to claim 1, wherein a depth D_b of the wedge-shaped grooves formed in the surface of the light guide plate and/or a distance P_b between adjacent wedge-shaped grooves varies in accordance with the distance from the light source or the brightness distribution of the in-plane direction of the light guide plate.

5. A backlight device according to claim 4, wherein the depth D_b of the wedge-shaped grooves far from the light source is deeper than that of the wedge-shaped grooves close to the light source.

6. A backlight device according to claim 4, wherein the distance P_b between adjacent wedge-shaped grooves far from the light source is shorter than that between adjacent wedge-shaped grooves close to the light source.

7. A backlight device according to claim 1, wherein a diffusive reflector having micro-irregularities having light reflectivity formed on a base surface is formed such that the micro-irregularities-formed surface is opposite to another surface of the light guide plate.

8. A backlight device according to claim 1, wherein a light directivity adjusting sheet having a plurality of pyramid-shaped bodies formed on a base body is formed on the surface of the light guide plate such that the tips of the pyramid-shaped bodies are directed to the opposite direction to the light guide plate, and the light directivity adjusting sheet controls the directivities of the transmitted light components in at least two different directions among the light components emitted from the surface of the light guide plate and transmitted through the light directivity adjusting sheet.

9. A backlight device according to claim 8, wherein micro-irregularities having light diffusivity are formed on the surface of the light directivity adjusting sheet facing the light guide plate.

10. A backlight device according to claim 1, wherein the thickness of the light guide plate far from the light source is thinner than that of the light guide plate close to the light source.

11. A backlight device according to claim 1, wherein the light source comprises a middle light guide body arranged along the end surface of the light guide plate and a point light source arranged in the end surface of the longitudinal direction of the middle light guide body.

12. A liquids crystal display device, comprising:

a backlight device according to claim 1, and

a liquid crystal display unit illuminated from the back surface by the backlight device.