OPTICAL FILM FOR INCREASING THE VIEWING ANGLE OF LIQUID CRYSTAL DISPLAY DEVICES

• US 20120274873A1
• Filed: 04/27/2011
• Published: 11/01/2012
• Est. Priority Date: 04/27/2011
• Status: Active Grant

• Current Assignee: Finity Labs
• Original Assignee: Finity Labs
• Inventors: Lee, Wai-Hon
• Granted Patent: US 8,553,168 B2
• Time in Patent Office: Days
• US Class Current: 349/62
• CPC Class Codes: G02F 1/133331 Cover glasses
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses

Abstract

Techniques and devices are disclosed to enhance or increase the viewing angle of liquid crystal display (LCD) device through the use of one or more types of optical films. Such optical films can include arrays of prism structures and/or diffractive elements that redirect light that has passed through an LCD panel. The prism structures and/or diffractive elements can be spaced on an optical film to enable at least a portion of the light travelling through the LCD panel to pass through the optical film without being redirected. Various types of prism structures and/or diffractive elements can be used, and they can be configured on the optical film differently to enable different functionality.

Claims

1. A liquid crystal display (LCD) device comprising:

a back light unit;

a first polarizer;

an LCD panel;

a second polarizer;

a transparent cover; and

a film for redirecting light, the film having;

a first refractive index,

a plurality of structures for redirecting light, the plurality of structures located on a surface of the film, and

a plurality of areas on the surface of the film without structures for redirecting light;

wherein the film is located between the second polarizer and the transparent cover.

2. The LCD device recited in claim 1, wherein:

the film is a prism film; and

the plurality of structures includes a plurality of prism structures.

3. The LCD device recited in claim 2, wherein the plurality of prism structures are periodically spaced along at least one dimension of the prism film.

4. The LCD device recited in claim 3, wherein:

each of the plurality of prism structures has a certain width; and

a distance between each of the plurality of prism structures is greater than the certain width of the prism structure.

5. The LCD device recited in claim 4, wherein, for a period equal to the width of a first prism structure plus the distance between the first prism structure and a second prism structure, the distance between the first prism structure and the second prism structure comprises 75% to 85% of the period.

6. The LCD device recited in claim 2, wherein an apex of each of the plurality of prism structures faces the second polarizer.

7. The LCD device recited in claim 2, further including a media between the prism film and the second polarizer, the media having a second refractive index lower than the first refractive index.

8. The LCD device recited in claim 2, wherein each of the plurality of prism structures is triangular.

9. The LCD device recited in claim 2, for a period equal to the width of a first prism structure plus the distance between the first prism structure and a second prism structure, the period is less than a width of a color element in the LCD panel.

10. A liquid crystal display (LCD) device comprising:

a back light unit;

a first polarizer;

an LCD panel;

a second polarizer;

a transparent cover; and

a diffractive film having;

a first refractive index, and

a plurality of diffractive structures;

wherein the diffractive film is located between the second polarizer and the transparent cover.

11. The LCD device recited in claim 10, wherein the plurality of diffractive structures comprises a plurality of groups of diffractive structures periodically spaced along at least one dimension of the diffractive film.

12. The LCD device recited in claim 11, wherein, for a period equal to the width of a first group plus the distance between the first group and a second group, the period is less than a width of a color element in the LCD panel.

13. The LCD device recited in claim 11, wherein:

each group of the plurality groups of diffractive structures has a certain width; and

a distance between each group of the plurality groups of diffractive structures is greater than the certain width of the group.

14. The LCD device recited in claim 13, wherein, for a period equal to the width of a first group plus the distance between the first group and a second group, the distance between the first group and the second group comprises 75% to 85% of the period.

15. The LCD device recited in claim 10, wherein the plurality of diffractive structures are located on a surface of the diffractive film facing the second polarizer.

16. The LCD device recited in claim 15, further including a media between the diffractive film and the second polarizer, the media having a second refractive index different from the first refractive index.

17. The LCD device recited in claim 10, wherein the plurality of diffractive structures are located on a surface of the diffractive film facing away from the second polarizer.

18. The LCD device recited in claim 17, further including a media between the diffractive film and the second polarizer, the media having a second refractive index different from the first refractive index.

19. A liquid crystal display (LCD) device comprising:

a diffractive film having a plurality of groups of diffractive structures, wherein;

the plurality of groups of diffractive structures are periodically spaced along at least one dimension of the diffractive film;

a distance between each group of diffractive structures is greater than the width of each group; and

the diffractive film is disposed in relation to an LCD panel such that, after light that travels through the LCD panel, a portion of the light is redirected by the diffractive structures of the diffractive film.

20. The LCD device recited in claim 19, wherein, for a period equal to the width of a first group plus the distance between the first group and a second group, the period is less than a width of a color element in the LCD panel.

21. The LCD device recited in claim 19, wherein the diffractive structures are configured to redirect light in two mutually orthogonal dimensions.