Light redirecting film and method for manufacturing the same

• US 10,642,057 B2
• Filed: 11/21/2017
• Issued: 05/05/2020
• Est. Priority Date: 07/20/2017
• Status: Active Grant

• Current Assignee: BENQ Materials Corporation
• Original Assignee: BENQ Materials Corporation
• Inventors: Kuo, Chen-Kuan, Hong, Cyun-Tai, Shen, Chuen-Nan, Chien, Chung-Hung, Shieh, Hung-Jiun, Yeh, Tsung-Chi, Wu, Fung-Hsu
• Primary Examiner(s): Chang, Audrey Y
• Application Number:
  US15/820,413
• Publication Number:
  US 20190025605A1
• Time in Patent Office: 896 Days
• Field of Search: 359576, 359569, 359566, 349112, 349118, 349 62
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 27/4272 having plural diffractive elements positioned sequentially along the optical path
• CPC Class Codes: G02B 5/0252 using holographic or diffractive means
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/1823 in an overlapping or superposed manner
• CPC Class Codes: G02B 5/1842 Gratings for image generation G02B5/1847 takes precedence
• CPC Class Codes: G02B 5/1847 Manufacturing methods
• CPC Class Codes: G02B 5/1852 using mechanical means, e.g. ruling with diamond tool, moulding
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence

Abstract

A light redirecting film and a method for manufacturing the same are provided. The light redirecting film comprises a substrate, a first diffraction grating layer of a first curable resin on the substrate and a second diffraction grating layer of a second curable resin on the first diffraction grating layer. Wherein the grating directions of the first diffraction grating layer and the second diffraction grating layer cross each other at an angle of 90±10°, and the difference of the refractive index of the first curable resin and the second curable resin is no less than 0.1 and no more than 0.3.

Claims

1. A light redirecting film comprising:

a substrate;

a first diffraction grating layer formed on the substrate, and the first diffraction grating layer comprising a plurality of first gratings along with first direction; and

a second diffraction grating layer formed on the first diffraction grating layer, and the second diffraction grating layer comprising a plurality of second gratings along with second direction;

wherein the first direction and the second direction cross each other at an angle of 90±

10°

;

wherein the first diffraction grating layer includes a first curable resin having a first refractive index of n1, and the second diffraction grating layer includes a second resin having a second refractive index of n2, and the difference of n1 and n2 is no less than 0.1 and no more than 0.3, and when the light redirecting film is attached in front of a displaying side of a liquid crystal display (LCD), gamma values reflecting to the contrast ration and color saturation of the liquid crystal display (LCD) are greater than 0.9 at different horizontal and/or vertical viewing angles ≤

80 degrees.

2. The light redirecting film according to claim 1, wherein n1 is in the range of 1.4 to 1.7.

3. The light redirecting film according to claim 1, wherein the widths of each of the first gratings and each of the second gratings are independently in the range of 0.3 μ

m to 1.5 μ

m.

4. The light redirecting film according to claim 1, wherein the gaps between adjacent two of the first gratings and the gaps between adjacent two of the second gratings are independently in the range of 0.3 μ

m to 1.5 μ

m.

5. The light redirecting film according to claim 1, wherein the heights of each of the first gratings and each of the second gratings are independently in the range of 0.5 μ

m to 1.5 μ

m.

6. The light redirecting film according to claim 1, wherein n2 is in the range of 1.4 to 1.7.

7. The light redirecting film according to claim 1, further comprising a third curable resin with a third refractive index of n3 formed on the second diffraction grating layer.

8. The light redirecting film according to claim 7, wherein n3 is in the range of 1.4 to 1.7.

9. The light redirecting film according to claim 7, wherein the difference of n2 and n3 is no less than 0.1 and no more than 0.3.

10. The light redirecting film according to claim 7, wherein n2 is greater than n1 and n3.

11. The light redirecting film according to claim 7, further comprising an optical film adhered to the third curable resin, wherein the optical film is selected from one of a group consisting of a polarizing film, a hard-coating film, a low reflective film, an anti-reflective film, an anti-glaring film and a protective film or combinations thereof.

12. A method for manufacturing a light redirecting film comprising the steps of:

providing a substrate;

coating a first curable resin on the substrate;

embossing the first curable resin and curing thereafter to form a first diffraction grating layer comprising a plurality of first gratings along with first direction;

coating a second curable resin on the first diffraction grating layer; and

embossing the second curable resin and curing thereafter to form a second diffraction grating layer comprising a plurality of second gratings along with second direction;

wherein the first direction and the second direction cross each other at an angle of 90±

10°

;

wherein, the first curable resin has a first refractive index of n1, and the second resin has a second refractive index of n2, and the difference of n1 and n2 is no less than 0.1 and no more than 0.3, and when the light redirecting film is attached in front of a displaying side of a liquid crystal display (LCD), gamma values reflecting to the contrast ration and color saturation of the liquid crystal display (LCD) are greater than 0.9 at different horizontal and/or vertical viewing angles 80 degrees.

13. The method according to claim 12, wherein the first curable resin is an UV curable resin or a thermal curable resin, and n1 is in the range of 1.4 to 1.7.

14. The method according to claim 12, wherein the embossed first curable resin is cured by UV radiation or heating treatment.

15. The method according to claim 12, wherein the second curable resin is an UV curable resin or a thermal curable resin, and n2 is in the range of 1.4 to 1.7.

16. The method according to claim 12, wherein the embossed curable second resin is cured by UV radiation or heating treatment.

17. The method according to claim 12, further comprising a step of coating a third curable resin with a third refractive index of n3 on the second diffraction grating layer.

18. The method according to claim 17, wherein the third curable resin is an UV curable resin or a thermal curable resin, and n3 is in the range of 1.4 to 1.7.

19. The method according to claim 17, wherein the difference of n2 and n3 is no less than 0.1 and no more than 0.3.

20. The method according to claim 17, wherein n2 is greater than n1 and n3.

21. The method according to claim 17, further comprising a step of adhering an optical film, selected from one of a group consisting of a polarizing film, a hard-coating film, a low reflective film, an anti-reflective film, an anti-glaring film and a protective film or combinations thereof, on the third curable resin.

22. A liquid crystal display (LCD) comprising:

a liquid crystal panel; and

a light redirecting film attached in front of the displaying side of the liquid crystal panel, comprising;

a substrate;

a first diffraction grating layer formed on the substrate, and the first diffraction grating layer comprising a plurality of first gratings along with first direction; and

a second diffraction grating layer formed on the first diffraction grating layer, and the second diffraction grating layer comprising a plurality of second gratings along with second direction;

wherein the first direction and the second direction cross each other at an angle of 90±

10°

;

wherein the first diffraction grating layer includes a first curable resin having a first refractive index of n1, and the second diffraction grating layer includes a second resin having a second refractive index of n2, and the difference of n1 and n2 is no less than 0.1 and no more than 0.3;

wherein gamma values reflecting to the contrast ration and color saturation of the liquid crystal display (LCD) are greater than 0.9 at different horizontal and/or vertical viewing angles ≤

80 degrees.

23. The liquid crystal display (LCD) according to claim 22, wherein n1 is in the range of 1.4 to 1.7.

24. The liquid crystal display (LCD) according to claim 22, wherein the widths of each of the first gratings and each of the second gratings are independently in the range of 0.3 μ

m to 1.5 μ

m.

25. The liquid crystal display (LCD) according to claim 22, wherein the gaps between adjacent two of the first gratings and the gaps between adjacent two of the second gratings are independently in the range of 0.3 μ

m to 1.5 μ

m.

26. The liquid crystal display (LCD) according to claim 22, wherein the heights of each of the first gratings and each of the second gratings are independently in the range of 0.5 μ

m to 1.5 μ

m.

27. The liquid crystal display (LCD) according to claim 22, wherein n2 is in the range of 1.4 to 1.7.

28. The liquid crystal display (LCD) according to claim 22, further comprising a third curable resin with a third refractive index of n3 formed on the second diffraction grating layer, and n3 is in the range of 1.4 to 1.7.

29. The liquid crystal display (LCD) according to claim 28, wherein the difference of n2 and n3 is no less than 0.1 and no more than 0.3.

30. The liquid crystal display (LCD) according to claim 28, wherein n2 is greater than n1 and n3.

31. The liquid crystal display (LCD) according to claim 28, further comprising an optical film adhered to the third curable resin, wherein the optical film is selected from one of a group consisting of a polarizing film, a hard-coating film, a low reflective film, an anti-reflective film, an anti-glaring film and a protective film or combinations thereof.