POLARIZED LIGHT-EMITTING DEVICE

• US 20090015758A1
• Filed: 09/29/2007
• Published: 01/15/2009
• Est. Priority Date: 07/10/2007
• Status: Active Grant

• Current Assignee: HannStar Display Corporation
• Original Assignee: HannStar Display Corporation
• Inventors: CHEN, Wei-Chou, Pei, Ting-Hang
• Granted Patent: US 7,872,706 B2
• Time in Patent Office: Days
• US Class Current: 349/69
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/3041 comprising multiple thin layers, e.g. multilayer stacks
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

Polarized light-emitting device with a light source, multiple layers of first optical thin films and second optical thin films alternately stacked is disclosed. Each first optical thin film has a number of first geometric units, and each second optical thin film has a number of second geometric units. The first geometric units and the second geometric units are arranged as a secondary periodic structure on the light-emitting surface of the light source. The polarized light-emitting device is able to provide polarized light with higher brightness and polarized light of a specified polarization characteristic.

Claims

1. A polarized light-emitting device, comprising:

a light source;

a first optical thin film disposed at the light-emitting side of the light source, having a thickness d₁, and comprising a plurality of first geometric units having a width a₁, wherein 0.2≦

d₁/a₁≦

2; and

a second optical thin film covering the first optical thin film, having a thickness d2, and comprising a plurality of second geometric units having a width a₂, wherein 0.2≦

d₂/a₂≦

2;

wherein the first geometric unit and the second geometric unit is repeatedly arranged along a first direction.

2. The polarized light-emitting device as claimed in claim 1, wherein the width a₁ equals to the width a₂.

3. The polarized light-emitting device as claimed in claim 1, further comprising n layers of the first optical thin film and m layers of the second optical thin film alternatingly and sequentially stacked each other, wherein n and m are equal or larger than 4.

4. The polarized light-emitting device as claimed in claim 1, wherein the refractive index of the first optical thin film is different from the refractive index of the second optical thin film.

5. The polarized light-emitting device as claimed in claim 1, wherein the sum of the height h₁ of the first geometric unit and the height h₂ of the second geometric unit is h, and 0.2≦

h/a≦

2.

6. The polarized light-emitting device as claimed in claim 1, wherein the refractive index of the first optical thin film or the second optical thin film is larger than 2.

7. The polarized light-emitting device as claimed in claim 1, wherein the first geometric unit or the second geometric unit are alternately arranged along a second direction perpendicular to the first direction.

8. The polarized light-emitting device as claimed in claim 1, wherein one of the first geometric unit or the second geometric unit comprises a sawtooth cross section structure.

9. The polarized light-emitting device as claimed in claim 1, further comprising an encapsulation structure disposed between the light source and the first optical thin film.

10. The polarized light-emitting device as claimed in claim 9, wherein the difference between the refractive index of the encapsulation structure and the refractive index of the first optical thin film is less than 1.

11. The polarized light-emitting device as claimed in claim 9, wherein the difference between the refractive index of the encapsulation structure and the refractive index of the light source is less than 1.

12. The polarized light-emitting device as claimed in claim 9, wherein the material of encapsulation structure is resin or silicon oxide.

13. The polarized light-emitting device as claimed in claim 1, wherein the first optical thin film is made of silicon (Si), germanium (Ge), gallium arsenide (GaAs), or combinations thereof.

14. The polarized light-emitting device as claimed in claim 1, wherein the second optical thin film is made of silicon oxide (SiO₂), magnesium oxide (MgO), aluminum oxide (Al₂O₃), silicon nitride (Si_xN_y), or combinations thereof.

15. The polarized light-emitting device as claimed in claim 1, further comprises a reflective layer disposed at another side of the corresponding light-emitting side of the light source.

16. The polarized light-emitting device as claimed in claim 15, wherein the reflective layer is made of silver (Ag), aluminum (Al), or gold (Au).

17. The liquid crystal display as claimed in claim 1, wherein the light source comprises a red light emitting device, a green light emitting device, a blue light emitting device, or a white light emitting device.

18. An liquid crystal display, comprising:

a light source;

a first optical thin film disposed on the surface of the light source, having a thickness d₁, and comprising a plurality of first geometric units having a width a₁, wherein 0.2≦

d₁/a₁≦

2; and

a second optical thin film covering the first optical thin film, having a thickness d2, and comprising a plurality of second geometric units having a width a₂, wherein 0.2≦

d₂/a₂≦

2.

an liquid crystal display panel disposed above the light source, first optical thin film, and the second optical thin film; and

an upper polarizing film disposed on the LCD panel.

19. The liquid crystal display as claimed in claim 18, wherein the light source comprises a red light emitting device, a green light emitting device, a blue light emitting device, or a white light emitting device.

20. The liquid crystal display as claimed in claim 19, wherein the light emitting device is a light-emitting diode (LED), an organic light-emitting diode (OLED), or a laser diode (LD).