Liquid Crystal Display Device

• US 20080297695A1
• Filed: 05/30/2008
• Published: 12/04/2008
• Est. Priority Date: 05/31/2007
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Konno, Akitoyo, Sasaki, Hiroshi, Sekiguchi, Yoshifumi
• Granted Patent: US 8,089,582 B2
• Time in Patent Office: Days
• US Class Current: 349/65
• 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 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays
• CPC Class Codes: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

An object of the present invention is to provide a liquid crystal display device having a light guide plate that is capable of providing improved liquid crystal display performance without generating a striped image. The liquid crystal display device includes a light guide plate, which illuminates a liquid crystal panel from its rear surface, and light sources, which shed a light ray on the light guide plate. The rear surface of the light guide plate is separated into a plurality of rear surface divisions by concave grooves. The light sources can adjust the brightness of each rear surface division. The display performance of the liquid crystal panel is improved by individually managing a plurality of regions of the liquid crystal panel, which correspond to the rear surface divisions, and darkening a rear surface division that corresponds to a region where the black color is predominant.

Claims

1. A liquid crystal display device comprising:

a liquid crystal panel;

a light guide plate mounted on the rear surface of the liquid crystal panel;

a light source positioned so that a light ray is incident on the light guide plate from an incidence plane formed on at least either of the right and left side surfaces of the light guide plate; and

light source driving means for driving the light source;

wherein the light guide plate guides the light ray incident from the incidence plane, outputs the light ray from an output plane facing the liquid crystal panel, and illuminates the liquid crystal panel from the rear surface; and

wherein at least either the output plane or the rear surface of the output plane is divided by a concave groove that is formed the output plane or the rear surface of the output plane toward the side to face the incidence plane from the incidence plane formed by one side of the light guide plate.

2. The liquid crystal display device according to claim 1, wherein the concave groove forms a concave section and a convex section at one end of the incidence plane;

wherein light sources are positioned relative to the convex section formed at one end of the incidence plane; and

wherein the light source driving means individually controls the light sources positioned relative to the convex section.

3. The liquid crystal display device according to claim 1, wherein at least either the output plane or the rear surface of the output plane is divided by forming the concave groove from one side of the incidence plane to about halfway toward the other side of the incidence plane.

4. The liquid crystal display device according to claim 2, wherein the liquid crystal panel displays videos by periodically rewriting the image data to be displayed;

wherein the light source becomes extinguished during a extinguishment period, which a part of a frame period that is required to rewrite one image data displayed on the display surface of the liquid crystal panel; and

wherein the timing with which the extinguishment period begins varies from one individually-controlled light source to another.

5. The liquid crystal display device according to claim 2, wherein the liquid crystal panel displays videos by periodically rewriting the image data to be displayed;

wherein the light source becomes extinguished during a extinguishment period, which a part of a frame period that is required to rewrite one image data displayed on the display surface of the liquid crystal panel; and

wherein the timing with which the extinguishment period begins varies between at least two of the individually-controlled light sources.

6. The liquid crystal display device according to claim 1, wherein the concave groove forms a concave section and a convex section at one end of the incidence plane;

wherein the light source is positioned relative to the convex section formed at end of the incidence plane; and

wherein the light guide plate is such that the convex section near one end of the incidence plane is wider than the convex section near the center.

7. The liquid crystal display device according to claim 1, wherein the concave groove forms a concave section and a convex section at one end of the incidence plane;

wherein the light source is composed of a plurality of LEDs and positioned relative to the convex section formed at end of the incidence plane; and

wherein the light source LEDs for a convex section near one end of the incidence plane of the light guide plate are smaller in number than the light source LEDs for a convex section near the center.