LIQUID CRYSTAL DISPLAY DEVICE

• US 20090207343A1
• Filed: 02/13/2009
• Published: 08/20/2009
• Est. Priority Date: 02/20/2008
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Japan Display Incorporated
• Inventors: Mifune, Masayuki
• Granted Patent: US 8,400,584 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 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02B 6/0088 of the light guide or other optical sheets in the package

Abstract

A backlight which arranges light emitting diodes on a side surface of light guide plate adopts the structure which allows the easy removal of the light guide plate from a mold and makes it difficult for a stress or the like to influence the fine structure of a light incident portion of the light guide plate. In a liquid crystal display device having a backlight which radiates light to a liquid crystal panel, LEDs which constitute a light emitting element are mounted on a light guide plate which is mounted on a backlight, and edge portions of the light guide plate are tapered such that a width of the light guide plate is increased in the removal direction of the side surface of the light guide plate. Further, an ejector-pin mark is formed on a lower surface of the light guide plate by pushing an ejector pin in the removal direction of the light guide plate.

Claims

1. A liquid crystal display device comprising:

a liquid crystal panel; and

a backlight which radiates light to the liquid crystal panel, wherein

the backlight includes a light emitting element and a light guide plate, and

edge portions of the light guide plate are tapered such that a width of the light guide plate is increased in the direction that the light guide plate is removed from a mold for injection molding.

2. A liquid crystal display device according to claim 1, wherein an ejector pin mark is formed on the light guide plate in the vicinity of the edge portion of the light guide plate and on a back-surface side of the light guide plate with respect to the removing direction of the light guide plate.

3. A liquid crystal display device according to claim 1, wherein an ejector pin mark is formed on the light guide plate in the vicinity of the edge portion of the light guide plate and on a back-surface side of the light guide plate with respect to the removing direction of the light guide plate, and a corner portion of the ejector pin mark is chamfered.

4. A liquid crystal display device according to claim 1, wherein an ejector pin mark is formed on the light guide plate in the vicinity of the edge portion of the light guide plate and on a back-surface side of the light guide plate with respect to the removing direction of the light guide plate, and a fixing projection is formed on the light guide plate in the vicinity of the ejector pin mark.

5. A liquid crystal display device comprising:

a liquid crystal panel; and

a backlight which radiates light to the liquid crystal panel, wherein

the backlight includes a light guide plate and a plurality of light emitting diodes which is arranged along a side surface of the light guide plate,

the light guide plate is formed by injection molding,

edge portions of the light guide plate are tapered such that a width of the light guide plate is increased in the direction that the light guide plate is removed from a mold for injection molding,

an ejector pin mark is formed on the light guide plate on a back-surface side with respect to the removing direction of the light guide plate.

6. A liquid crystal display device according to claim 5, wherein a corner portion of the ejector pin mark is chamfered.

7. A liquid crystal display device according to claim 5, wherein a fixing projection is formed on the light guide plate in the vicinity of the ejector pin mark.

8. A liquid crystal display device according to claim 5, wherein a fixing projection is formed on the light guide plate in the vicinity of the ejector pin mark, and the fixing projection is chamfered.

9. A liquid crystal display device according to claim 5, wherein an ejector pin mark is formed on the light guide plate in the vicinity of the edge portion of the tapered light guide plate.

10. A liquid crystal display device comprising:

a liquid crystal panel; and

a planar lighting device which radiates light to the liquid crystal panel, wherein

the planar lighting device includes a light guide plate having a light radiation surface, a bottom surface which faces the light radiation surface in an opposed manner and side surface,

the side surface of the light guide plate has an incident surface on which a plurality of LEDs are mounted and through which light from the LEDs is incident on the light guide plate,

a scattering member is mounted on the bottom surface of the light guide plate for allowing light incident on the light guide plate to be directed toward a light-radiation-surface side, and to be radiated from the light radiation surface,

and edge portions of the light guide plate are tapered such that a width of the light guide plate is increased in the direction that the light guide plate is removed from a mold for injection molding, and

an ejector pin mark is formed on the light guide plate on a back-surface side of the light guide plate with respect to the removing direction of the light guide plate.

11. A liquid crystal display device according to claim 10, wherein a corner portion of the ejector pin mark is chamfered.

12. A liquid crystal display device according to claim 10, wherein a fixing projection is formed on the light guide plate in the vicinity of the ejector pin mark.