LIQUID CRYSTAL DISPLAY DEVICE HAVING IMPROVED VIEWING ANGLE AND BRIGHTNESS

• US 20080252816A1
• Filed: 10/26/2007
• Published: 10/16/2008
• Est. Priority Date: 04/12/2007
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: HWANG, Seong-mo, KIM, Young-chan, LEE, Moon-gyu, CHOE, Kyu-min, MIN, Jee-hong
• Granted Patent: US 7,796,212 B2
• Time in Patent Office: Days
• US Class Current: 349/64
• 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 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A liquid crystal display with an improved viewing angle and brightness is provided. The liquid crystal display includes a light source unit and a polarized light guide plate having an incident surface onto which unpolarized light from the light source unit is incident. The polarized light guide plate polarizes, collimates, and out-couples the incident light. The liquid crystal display also includes a liquid crystal panel which modulates the light out-coupled and illuminated from the polarized light guide plate to form images, and a diffusion layer which diffuses the light modulated in the liquid crystal panel.

Claims

1. A liquid crystal display comprising:

a light source unit;

a polarized light guide plate comprising an incident surface onto which unpolarized light from the light source unit is incident, wherein the polarized light guide plate polarizes, collimates, and out-couples the incident light;

a liquid crystal panel which modulates the light illuminated from the polarized light guide plate to form images; and

a diffusion layer which diffuses the light modulated in the liquid crystal panel.

2. The liquid crystal display of claim 1, wherein the light source unit comprises:

a point light source; and

a light guide bar which guides light from the point light source to the incident surface,

wherein the light guide bar comprises a prism pattern formed on a side of the light guide bar.

3. The liquid crystal display of claim 1, wherein the light source unit comprises a plurality of point light sources which face the incident surface.

4. The liquid crystal display of claim 1, wherein a polarization conversion member and a reflection member are formed at a side of the polarized light guide plate.

5. The liquid crystal display of claim 4, wherein the polarization conversion member is a quarter wavelength plate.

6. The liquid crystal display of claim 1, further comprising an anti-reflection layer on the diffusion layer.

7. The liquid crystal display of claim 1, wherein the liquid crystal panel comprises:

a first substrate upon which a first polarization plate is attached;

a second substrate upon which a second polarization plate is attached; and

a liquid crystal layer encapsulated between the two substrates;

wherein a polarization axis of the first polarization plate is perpendicular to a polarization axis of the second polarization plate.

8. The liquid crystal display of claim 7, wherein the diffusion layer and one of the first polarization plate and the second polarization plate are formed as a single body at an outer side of the liquid crystal panel.

9. The liquid crystal display of claim 7, wherein liquid crystals of the liquid crystal layer are arranged in a twisted nematic (TN) mode.

10. The liquid crystal display of claim 7, wherein liquid crystals of the liquid crystal layer are arranged in a vertical alignment (VA) mode.

11. The liquid crystal display of claim 7, wherein an optical axis of the first polarization plate is oriented at an angle of 0°

with respect to a horizontal direction of the liquid crystal panel, and an optical axis of the second polarization plate is oriented at an angle of 90°

with respect to the horizontal direction of the liquid crystal panel.

12. The liquid crystal display of claim 1, wherein the polarized light guide plate further comprises:

a first layer which guides the incident light;

a second layer formed of an optically isotropic material on the first layer, wherein out-coupling units comprising a first convex portion are repeatedly arranged on the second layer; and

a third layer formed of an optically anisotropic material on the second layer.

13. The liquid crystal display of claim 12, wherein a refractive index of the optically anisotropic material is greater than a refractive index of the second layer with respect to a first polarized light, and almost the same as the refractive index of the second layer with respect to a second polarized light;

the first polarized light is perpendicular to the second polarized light; and

the polarized light guide plate out-couples the first polarized light.

14. The liquid crystal display of claim 12, wherein the first convex portion has a shape of a prism.

15. The liquid crystal display of claim 12, wherein a plane portion is formed between neighboring out-coupling units.

16. The liquid crystal display of claim 15, wherein a width of the plane portion is gradually reduced away from the light source unit.

17. The liquid crystal display of claim 12, wherein the out-coupling units further comprise a first concave portion connected to a first side of the first convex portion.

18. The liquid crystal display of claim 17, wherein the out-coupling units further comprise a second concave portion connected to a second side of the first convex portion.

19. The liquid crystal display of claim 12, wherein the out-coupling units comprise a second convex portion connected to a side of the first convex portion.

20. The liquid crystal display of claim 19, wherein the second convex portion has a shape of a prism.