EDGE LIGHTED BACKLIGHT UNIT FOR LIQUID CRYSTAL DISPLAY DEVICE

• US 20170261675A1
• Filed: 05/13/2015
• Published: 09/14/2017
• Est. Priority Date: 05/16/2014
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Dannoux, Thierry Luc Alain, Gollier, Jacques, Li, Shenping, Zhang, Ying
• Granted Patent: US 10,018,765 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects

Abstract

A light guide plate suitable for use in a liquid crystal display device, the light guide plate comprising a glass plate and a light coupler bonded to a major surface of the light guide plate. Also disclosed is a backlight unit for a liquid crystal display device employing the light guide plate, and a display device employing the backlight unit.

Claims

1. A backlight unit comprising:

a glass plate comprising a first major surface, a second major surface and a thickness Th1 therebetween; and

a light coupler coupled to the glass plate comprising at least one taper portion extending over and bonded to at least one of the first major surface or the second major surface along an edge portion of the glass plate; and

a light source positioned adjacent an input facet of the light coupler.

2. The backlight unit according to claim 1, wherein the light coupler comprises a base portion adjacent an edge surface of the glass plate.

3. The backlight unit according to claim 1, wherein Th1 divided by a width Th2 of the input facet is in a range from about 0.5 to 1.0.

4. The backlight unit according to claim 1, wherein the light coupler includes a pair of taper portions bonded to the first and second major surfaces, respectively.

5. The backlight unit according to claim 4, wherein the light coupler includes a channel and the glass plate is positioned within the channel.

6. The backlight unit according to claim 4, wherein the glass plate comprises an index of refraction n_L, the light coupler comprises an index of refraction n_e, and n_e−

n_L is in a range from about −

0.4 to about 0.8.

7. The backlight unit according to claim 1, wherein a width Th2 of the input facet is in a range of 1 to 1.5 times a width Wd of the light source.

8. The backlight unit according to claim 5, wherein the channel includes a bottom surface, and wherein a length L_t of the light coupler is equal to the sum of a distance L1 between the input facet and the bottom surface of the channel and a depth L2 of the channel, and a ratio L2/L_t is in a range from about 0.1 to about 0.9.

9. The backlight unit according to claim 5, wherein L_t is in a range from about 1 millimeter to about 20 millimeters.

10. The backlight unit according to claim 5, wherein L_t is in a range from about 1 millimeter to about 10 millimeters.

11. The backlight unit according to claim 4, further comprising a base portion extending between the pair of taper portions.

12. The backlight unit according to claim 5, wherein a width Wx of the channel is in a range of 1 to 1.1 times Th1.

13. A display device comprising:

a display panel;

a backlight unit configured to illuminate the display panel, the backlight unit comprising;

a glass plate comprising a first major surface, a second major surface and a thickness Th1 therebetween; and

a light coupler bonded to the first major surface along an edge portion of the glass plate, the light coupler including at least one taper portion; and

a light source positioned adjacent an input facet of the light coupler.

14. The display device according to claim 13, wherein the light coupler comprises a base portion adjacent an edge surface of the glass plate.

15. The display device according to claim 13, wherein Th1 divided by a width Th2 of the input facet is in a range from about 0.5 to 1.0.

16. The display device according to claim 15, wherein the light coupler includes a pair of taper portions bonded to the first and second major surfaces, respectively.

17. The display device according to claim 16, wherein the light coupler includes a channel and the glass plate is positioned within the channel.

18. The display device according to claim 16, wherein the glass plate comprises an index of refraction n_L, the light coupler comprises an index of refraction n_e, and n_e−

n_L is in a range from about −

0.4 to about 0.8.

19. The display device according to claim 16, wherein a width Th2 of the input facet is in a range of 1 to 1.5 times a width Wd of the light source.

20. The display device according to claim 17, wherein the channel includes a bottom surface, and wherein a length L_t of the light coupler is equal to the sum of a distance L1 between the input facet and the bottom surface of the channel and a depth L2 of the channel, and a ratio L2/L_t is in a range from about 0.1 to about 0.9.

21. The display device according to claim 17, wherein L_t is in a range from about 1 millimeter to about 20 millimeters.

22. The display device according to claim 16, wherein the light coupler further comprises a base portion extending between the pair of taper portions.

23. The display device according to claim 17, wherein a width Wx of the channel is in a range of 1 to 1.1 times Th1.

24. A light guide plate configured for use in a liquid crystal display device comprising:

a glass plate including a first major surface, a second major surface opposite the first major surface, and a thickness Th1 therebetween; and

a light coupler including at least one taper portion bonded to at least one of the first major surface and the second major surface.

25. The light guide plate according to claim 24, wherein the light coupler comprises a base portion adjacent an edge surface of the glass plate.

26. The light guide plate according to claim 24, wherein the light coupler includes an input facet with a width Th2, and Th1 divided by Th2 is in a range from about 0.5 to 1.0.

27. The light guide plate according to claim 24, wherein the light coupler includes a pair of taper portions bonded to the first and second major surfaces, respectively.

28. The light guide plate according to claim 27, wherein the light coupler includes a channel and the glass plate is positioned within the channel.

29. The light guide plate according to claim 27, wherein the glass plate comprises an index of refraction n_L, the light coupler comprises an index of refraction n_e, and n_e−

n_L is in a range from about −

0.4 to about 0.8.

30. The light guide plate according to claim 28, wherein the channel includes a bottom surface, and wherein a length L_t of the light coupler is equal to the sum of a distance L1 between an input facet and the bottom surface of the channel and a depth L2 of the channel, and a ratio L2/L_t is in a range from about 0.1 to about 0.9.

31. The light guide plate according to claim 27, further comprising a base portion extending between the pair of taper portions.

32. The light guide plate according to claim 27, wherein a width Wx of the channel is in a range of 1 to 1.1 times Th1.

33. A method of making a light coupler comprising:

applying a mold assembly to an edge portion of a glass plate, the mold assembly including a cavity for receiving a polymer material;

injecting the polymer material into the mold assembly;

removing the mold assembly; and

wherein the glass plate after removal of the mold assembly comprises a light coupler including at least one taper portion bonded to at least one of a first major surface and a second major surface of the glass plate along the edge portion.

34. The method according to claim 33, wherein the polymer material is a PMMA material or a polycarbonate material.

35. The method according to claim 33, wherein the polymer material is a UV curable material.