BACKLIGHT AND DISPLAY

• US 20100061087A1
• Filed: 03/04/2008
• Published: 03/11/2010
• Est. Priority Date: 03/05/2007
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Stevens, Oliver Andrew Charles, Montgomery, David James
• Granted Patent: US 8,950,884 B2
• Time in Patent Office: Days
• US Class Current: 362/97.300
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors

Abstract

A backlight is provided for a direct-view display. The backlight comprises a plurality of discrete light sources (11), such as light emitting diodes, spaced from a diffuser (5). The light sources are arranged as sets cooperating with a mirror structure (101), which surrounds the set to form a region. The regions substantially tessellate the area of the backlight. Each mirror structure (101) comprises a plurality of mirror segments which are curved and concave in cross-section perpendicular to the diffuser (5). The mirror segments extend from around the light sources (11) towards the diffuser (5). The edges of adjacent mirror segments of adjacent regions meet at a meeting line such that all of the meeting lines are at the diffuser (5) or between the diffuser (5) and the light sources (11).

Claims

1. A display backlight comprising a plurality of discrete light sources spaced from a diffuser, the sources being arranged as sets, each of at least some of which comprises a plurality of the sources, cooperating with a mirror structure which surrounds the set to form a region, the regions being arranged as a two-dimensional array which substantially tessellates the area of the backlight, each mirror structure comprising a plurality of mirror segments, of curved concave cross-section in a plane substantially perpendicular to the diffuser, extending from around the sources of the set towards the diffuser, the edges of adjacent mirror segments of adjacent regions meeting at a meeting line with all of the meeting lines being at the diffuser or between the diffuser and the sources.

2. A backlight as claimed in claim 1, in which each mirror segment is arranged to reflect light incident thereon, at least from the sources adjacent the mirror segment, directly onto the diffuser.

3. A backlight as claimed in claim 1, in which each of the at least some sets comprises at least three sources.

4. A backlight as claimed in claim 1, in which the sources are all of substantially the same type.

5. A backlight as claimed in claim 1, in which the sources are substantially point-sources.

6. A backlight as claimed in claim 1, in which the sources are of Lambertian type.

7. A backlight as claimed in claim 1, in which the sources are light emitting diodes.

8. A backlight as claimed in claim 1, in which the light sources are substantially white light sources.

9. A backlight as claimed in claim 1, in which the adjacent ends of adjacent mirror segments of each region meet at curved lines.

10. A backlight as claimed in claim 1, in which the meeting lines are straight lines.

11. A backlight as claimed in claim 10, in which all of the meeting lines are in a first common plane.

12. A backlight as claimed in claim 1, in which the diffuser is a plane diffuser.

13. A backlight as claimed in claim 12, in which the first common plane is substantially at the diffuser plane.

14. A backlight as claimed in claim 11, in which each plane, which intersects the mirror segments and which is parallel to the first common plane, intersects each of the mirror segments at a straight line of intersection.

15. A backlight as claimed in claim 14, in which each mirror segments of substantially constant cross-sectional shape along each line of intersection.

16. A backlight as claimed in claim 15, in which the cross-sectional shape is substantially defined by the lateral distance with respect to an origin at the meeting line being proportional to distance perpendicularly from the first common plane raised to the power 1.2.

17. A backlight as claimed in claim 1, in which the sources are disposed substantially in a second common plane.

18. A backlight as claimed in claim 17 when, in which the diffuser is a plane diffuser and the second common plane is substantially parallel to the diffuser plane.

19. A backlight as claimed in claim 17, in which the mirror segments of each region meet the second common plane at a polygon.

20. A backlight as claimed in claim 19, in which the sources of each of the at least some sets are arranged in a pattern having an outline, which is similar to the polygon.

21. A backlight as claimed in claim 1, in which the regions are all of the same shape and have the same number of sources.

22. A backlight as claimed in claim 21, in which the regions are one of triangular, square and hexagonal.

23. A backlight as claimed in claim 1, in which the regions comprise a first set of regions, each of which is of a first shape and/or has a first number of sources, disposed in an inner area of the backlight and a second set of regions, each of which is of a second shape different from the first shape and/or has a second number of sources different from the first number of sources, disposed in an outer area of the backlight.

24. A backlight as claimed in claim 23, in which the regions of the first and second sets are triangular and square, respectively.

25. A backlight as claimed in claim 23, in which the second number is larger than the first number.

26. A display comprising a backlight as claimed in claim 1 disposed behind a spatial light modulator.

27. A display as claimed in claim 26, in which the modulator comprises a liquid crystal device.

28. A backlight as claimed in claim 13, in which each plane, which intersects the mirror segments and which is parallel to the first common plane, intersects each of the mirror segments at a straight line of intersection.

29. A backlight as claimed in claim 28, in which each mirror segment is of substantially constant cross-sectional shape along each line of intersection.

30. A backlight as claimed in claim 29, in which the cross-sectional shape is substantially defined by the lateral distance with respect to an origin at the meeting line being proportional to distance perpendicularly from the first common plane raised to the power 1.2.