Liquid crystal display device having improved viewing angle and brightness

• US 7,796,212 B2
• Filed: 10/26/2007
• Issued: 09/14/2010
• Est. Priority Date: 04/12/2007
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Moon-gyu, Hwang, Seong-mo, Kim, Young-chan, Min, Jee-hong, Choe, Kyu-min
• Primary Examiner(s): STAHL, MICHAEL J
• Application Number:
  US11/925,176
• Publication Number:
  US 20080252816A1
• Time in Patent Office: 1,054 Days
• Field of Search: None
• 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 6/0051 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, 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,

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;

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; and

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.

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 liquid crystals of the liquid crystal layer are arranged in a twisted nematic (TN) mode.

8. The liquid crystal display of claim 1, wherein liquid crystals of the liquid crystal layer are arranged in a vertical alignment (VA) mode.

9. The liquid crystal display of claim 1, 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.

10. The liquid crystal display of claim 1, wherein the first convex portion has a shape of a prism.

11. The liquid crystal display of claim 1, wherein a plane portion is formed between neighboring out-coupling units.

12. The liquid crystal display of claim 11, wherein a width of the plane portion is gradually reduced away from the light source unit.

13. The liquid crystal display of claim 1, wherein the out-coupling units further comprise a first concave portion connected to a first side of the first convex portion.

14. The liquid crystal display of claim 13, wherein the out-coupling units further comprise a second concave portion connected to a second side of the first convex portion.

15. The liquid crystal display of claim 1, wherein the out-coupling units comprise a second convex portion connected to a side of the first convex portion.

16. The liquid crystal display of claim 15, wherein the second convex portion has a shape of a prism.