Backlight Module and Liquid Crystal Display

• US 20100182532A1
• Filed: 05/29/2009
• Published: 07/22/2010
• Est. Priority Date: 01/20/2009
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Wang, Ying-Li, Hsu, Ya-Ling, Lin, Chun-Liang, Wang, Chun-Chieh, Liao, Chen-Hsien
• Granted Patent: US 8,152,319 B2
• Time in Patent Office: Days
• US Class Current: 349/61
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A backlight module and a liquid crystal display are disclosed. In the backlight module having a reflector base, a phosphor layer is disposed on the reflector base, and a plurality of blue light emitting diode (LEDs) are disposed above the reflector base and the phosphor layer for emitting a first light beam. An optical film is disposed above the reflector base, the phosphor layer and the blue LEDs for allowing P-polarized light of the first light beam to pass therethrough and reflecting S-polarized light of the first light beam to the phosphor layer so as to excite the phosphor layer to generate a second light beam of which the wavelengths are different from those of the first light beam. After being reflected to the optical film by the reflector base, the second light beam transmits through the optical film, and mixes with the first light beam to generate white light.

Claims

1. A backlight module, comprising:

a reflector base;

a phosphor layer disposed on the reflector base;

a plurality of light emitting diode (LED) components disposed above the reflector base and the phosphor layer for emitting a first light beam, each of the LED components comprising a blue LED; and

an optical film disposed above the reflector base, the phosphor layer and the LED components for allowing P-polarized light of the first light beam to pass through the optical film and reflecting S-polarized light of the first light beam;

wherein the phosphor layer is excited by the first light beam to generate a second light beam, and the second light beam have different wavelengths from the first light beam so as to mix with the first light beam to generate white light.

2. The backlight module as claimed in claim 1, wherein the phosphor layer is a yellow phosphor layer.

3. The backlight module as claimed in claim 2, wherein the S-polarized light has wavelengths ranging from 420 nm to 500 nm.

4. The backlight module as claimed in claim 1, wherein the strongest wavelength range of the first light beam is from 440 nm to 490 nm.

5. The backlight module as claimed in claim 1, wherein the first light beam comprises light with wavelengths ranging from 420 nm to 500 nm.

6. The backlight module as claimed in claim 1, wherein each of the LED components further comprises a green LED, and the phosphor layer is a red phosphor layer.

7. The backlight module as claimed in claim 6, wherein the S-polarized light has wavelengths ranging from 420 nm to 580 nm.

8. The backlight module as claimed in claim 1, wherein each of the LED components further comprises green phosphor, and the phosphor layer is a red phosphor layer.

9. The backlight module as claimed in claim 8, wherein the S-polarized light has wavelengths ranging from 420 nm to 580 nm.

10. The backlight module as claimed in claim 1, wherein the phosphor layer comprises a red phosphor material and a green phosphor material.

11. The backlight module as claimed in claim 10, wherein the S-polarized light has wavelengths ranging from 420 nm to 500 nm.

12. The backlight module as claimed in claim 1, wherein the optical film comprise:

a substrate having a first surface facing towards the reflector base, and a second surface opposite to the first surface;

a microprism structure disposed on the first surface; and

an optical material layer formed on the second surface, wherein the optical material layer is formed by alternately stacking at least one first dielectric layer and at least one second dielectric layer, and the first dielectric layer has a refractive index greater than the refractive index of the second dielectric layer.

13. The backlight module as claimed in claim 12, wherein the first dielectric layer is formed from a material selected from the group consisting of MgO, ZnO, SiN_x, SiON_x, TiO₂, ZnSe, ZnS, TaO_x, Al₂O₃, TeO_x, Indium Tin Oxide (ITO) and their mixtures, and the second dielectric layer is formed from a material selected from the group consisting of Si₂O₃, MgF₂, SiO₂, Al₂O₃, TeO_x, LiF, SiON_x and their mixtures.

14. The backlight module as claimed in claim 12, wherein the thickness of the first dielectric layer ranges from 5 nm to 90 nm, and the thickness of the second dielectric layer ranges from 10 nm to 130 nm.

15. The backlight module as claimed in claim 1, wherein the optical film comprises:

a substrate; and

an optical material layer formed on a surface of the substrate facing towards the reflector base, wherein the optical material layer is formed by alternately stacking at least one first material layer and at least one second material layer, and the first material layer is formed from 2,6-polyethylene naphthalate (PEN), and the second material layer is formed from co-PEN.

16. The backlight module as claimed in claim 15, wherein the thickness of the first material layer ranges from 10 nm to 130 nm, and the thickness of the second material layer ranges from 5 nm to 110 nm.

17. The backlight module as claimed in claim 1, wherein the optical film is a double brightness enhancement film (DBEF).

18. The backlight module as claimed in claim 1 wherein all of the LED components face towards the optical film.

19. The backlight module as claimed in claim 1, wherein a portion of the LED components face towards the optical film, and the other portion of the LED components face towards the phosphor layer.

20. The backlight module as claimed in claim 19, wherein the ratio of the number of the first portion of the LED components to the number of the second portion of the LED components is about 2:

1 to about 99;

1.

21. The backlight module as claimed in claim 1, wherein the LED components are spaced from the phosphor layer at a distance, and the distance ranges from 0.01 mm to 3 mm.

24. A liquid crystal display, comprising:

a backlight module as claimed in claim 1;

a polarizer disposed on a light emitting direction of the backlight module; and

a liquid crystal panel disposed above the polarizer.

22. A backlight module, comprising:

a reflector base;

a phosphor layer disposed on the reflector base;

a plurality of LED components disposed above the reflector base and the phosphor layer for emitting a first light beam, each of the LED components comprising a blue LED; and

an optical film disposed above the reflector base, the phosphor layer and the LED components, the optical film comprising;

a substrate having a first surface facing towards the reflector base, and a second surface opposite to the first surface;

a microprism structure disposed on the first surface; and

an optical material layer formed on the second surface, wherein the optical material layer is formed by alternately stacking at least one first dielectric layer and at least one second dielectric layer;

wherein the first dielectric layer is formed from a material selected from the group consisting of MgO, ZnO, SiN_x, SiON_x, TiO₂, ZnSe, ZnS, TaO_x, Al₂O₃, TeO_x, Indium Tin Oxide (ITO) and their mixtures, and the second dielectric layer is formed from a material selected from the group consisting of Si₂O₃, MgF₂, SiO₂, Al₂O₃, TeO_x, LiF, SiON_x and their mixtures; and

wherein the thickness of the first dielectric layer ranges from 5 nm to 90 nm, and the thickness of the second dielectric layer ranges from 10 nm to 130 nm.

25. A liquid crystal display, comprising:

a backlight module as claimed in claim 22;

a polarizer disposed on a light emitting direction of the backlight module; and

a liquid crystal panel disposed above the polarizer.

23. A backlight module, comprising:

a reflector base;

a phosphor layer disposed on the reflector base;

a plurality of LED components disposed above the reflector base and the phosphor layer for emitting a first light beam, each of the LED components comprising a blue LED;

an optical film disposed above the reflector base, the phosphor layer and the LED components, the optical film comprising;

a substrate having a first surface facing towards the reflector base, and a second surface opposite to the first surface; and

an optical material layer formed on a surface of the substrate facing towards the reflector base, wherein the optical material layer is formed by alternately stacking at least one first material layer and at least one second material layer;

wherein the first material layer is formed from 2,6-polyethylene naphthalate (PEN), and the second material layer is formed from co-PEN; and

wherein the thickness of the first material layer ranges from 10 nm to 130 nm, and the thickness of the second material layer ranges from 5 nm to 110 nm.

26. A liquid crystal display, comprising:

a backlight module as claimed in claim 23;

a polarizer disposed on a light emitting direction of the backlight module; and

a liquid crystal panel disposed above the polarizer.