Liquid crystal display device having improved viewing angle and brightness
View Patent ↗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.
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.