Light-emitting apparatus having a plurality of adjacent, overlapping light-guide plates

• US 7,311,431 B2
• Filed: 04/01/2005
• Issued: 12/25/2007
• Est. Priority Date: 04/01/2005
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Chew, Tong Fatt, Pang, Siew It, Poh, Ju Chin, Ng, Fook Chuin
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Zettl, Mary
• Application Number:
  US11/096,950
• Publication Number:
  US 20060221638A1
• Time in Patent Office: 998 Days
• Field of Search: 362/600, 362/606, 362/612, 362/613, 362/615, 362/616, 349/58, 349/61, 349/62, 349/65
• US Class Current: 362/613
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 29/71 using a combination of separate elements interconnected by heat-conducting means, e.g. with heat pipes or thermally conductive bars between separate heat-sink elements
• CPC Class Codes: F21V 29/745 the fins or blades being planar and inclined with respect to the joining surface from which the fins or blades extend
• CPC Class Codes: F21V 29/76 with essentially identical parallel planar fins or blades, e.g. with comb-like cross-section
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/008 of the partially overlapping type
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133628 with cooling means

Abstract

In one embodiment, a light-emitting apparatus includes a plurality of adjacent, overlapping light-guide plates formed of substantially transparent material, and a plurality of light sources. Each of the light-guide plates has i) first and second ends, ii) one or more substantially transparent surfaces through which light is emitted, and iii) one or more reflective surfaces to redirect light within the light-guide plate. Where first and second light-guide plates are adjacent, the first end of the first light-guide plate A) underhangs the second end of the second light-guide plate, and B) is positioned opposite a primary light-emitting side of the apparatus. The plurality of light sources are optically coupled to the first ends of the light-guide plates so as to illuminate the interiors of the light-guide plates.

Claims

1. A light-emitting apparatus, comprising:

a plurality of adjacent, overlapping light-guide plates formed of light-transmissive material, wherein each of the light-guide plates has i) first and second ends, ii) one or more light-emitting surfaces, and iii) one or more reflective surfaces to redirect light within the light-guide plate;

wherein, where first and second light-guide plates are adjacent, the first end of the first light-guide plate A) underhangs the second end of the second light-guide plate, and B) is positioned opposite a primary light-emitting side of the apparatus;

a plurality of light sources, optically coupled to the first ends of the light-guide plates to illuminate the interiors of the light-guide plates; and

a substantially rigid and thermally conductive substrate on which the light-guide plates are assembled, the substrate comprising, for each of the light-guide plates, an elongate planar member which comprises a primary end and a secondary end, the planar member extending in a first direction from the primary end to the secondary end, the primary end comprising a stepped member which comprises;

a first planar section that extends upwardly from the elongate planar member, the first planar section comprising an upper end and a lower end; and

a second planar section at the upper end of the first planar section, the second planar section extending rearwardly from the first planar section in a second direction which is opposite from the first direction.

2. The light-emitting apparatus of claim 1, wherein each light-guide plate comprises a first reflective surface that is opposite said primary light-emitting side of the apparatus;

and

a second reflective surface that underhangs and abuts an adjacent light-guide plate.

3. The light-emitting apparatus of claim 2, wherein the first reflective surfaces are diffused reflective surfaces.

4. The light-emitting apparatus of claim 3, wherein the diffused reflective surfaces comprise dot patterns of diffused reflective surfaces.

5. The light-emitting apparatus of claim 4, further comprising a specular reflective layer positioned below the dot patterns of diffused reflective surfaces.

6. The light-emitting apparatus of claim 3, wherein at least one of the diffused reflective surfaces is a uniform diffused surface.

7. The light-emitting apparatus of claim 2, wherein the first reflective surfaces are specular reflective surfaces.

8. The light-emitting apparatus of claim 2, wherein the first reflective surfaces are polarizing reflective surfaces.

9. The light-emitting apparatus of claim 2, wherein each light source comprises a plurality of light-emitting diodes (LEDs).

10. The light-emitting apparatus of claim 9, wherein the LEDs comprise differently colored LEDs.

11. The light-emitting apparatus of claim 9, wherein one or more of the LEDs have a luminous intensity spatial distribution having rotational symmetry about its optical axis.

12. The light-emitting apparatus of claim 9, wherein one or more of the LEDs have an oval-shaped luminous intensity spatial distribution, with distinct major and minor axes in their luminous intensity spatial distribution.

13. The light-emitting apparatus of claim 12, wherein the oval-shaped luminous intensity spatial distribution has a viewing angle of between 20°

and 90°

in the minor axis, and a viewing angle of between 60° and

180°

in the major axis.

14. The light-emitting apparatus of claim 12, wherein the minor axis of the luminous intensity spatial distribution is oriented perpendicular to the first reflective surface, and wherein the major axis of the luminous intensity spatial distribution is oriented parallel to the first reflective surface.

15. The light-emitting apparatus of claim 9, wherein the LEDs that are optically coupled to a common light-guide plate comprise a plurality of LED chips formed on a common substrate, with the LED chips being covered by an encapsulant.

16. The light-emitting apparatus of claim 9, wherein the LEDs that are optically coupled to a common light-guide plate are mounted on a substrate that is parallel to the LEDs'"'"' optical axes.

17. The light-emitting apparatus of claim 9, wherein the LEDs that are optically coupled to a common light-guide plate are mounted on a substrate that is perpendicular to the LEDs'"'"' optical axes.

18. The light-emitting apparatus of claim 2, wherein the light sources are abutted to light-guide plate surfaces that are perpendicular to said first reflective surfaces.

19. The light-emitting apparatus of claim 2, wherein the light sources are abutted to said first reflective surfaces.

20. The light-emitting apparatus of claim 2, wherein the light sources are abutted to said second reflective surfaces.

21. The light-emitting apparatus of claim 2, wherein said first reflective surfaces form an angle of between 0°

and 20°

with said primary light-emitting surface.

22. The light-emitting apparatus of claim 1, wherein the light sources are mounted on two or more surfaces of at least some light-guide plates, at the first ends of the light-guide plates.

23. The light-emitting apparatus of claim 1, further comprising

one or more heat dissipating elements, coupled to the substrate.

24. The light-emitting apparatus of claim 1, further comprising a number of heat dissipating elements that are coupled to the light sources.

25. The light-emitting apparatus of claim 1, further comprising light conditioners positioned between the light sources and the first ends of the light-guide plates.

26. The light-emitting apparatus of claim 25, wherein at least one of the light conditioners is a light diffusing layer.

27. The light-emitting apparatus of claim 25, wherein at least one of the light conditioners is a prismatic layer.

28. The light-emitting apparatus of claim 25, wherein at least one of the light conditioners comprises a holographic light diffusing layer.

29. The light-emitting apparatus of claim 1, further comprising a light-transmissive bonding material joining said light-guide plates.

30. The light-emitting apparatus of claim 1, further comprising one or more heat dissipating elements coupled to a side of the substantially rigid and thermally conductive substrate that is opposite a side of the substrate on which the light-guide plates are assembled.

31. The light-emitting apparatus of claim 1, wherein the elongate planar member and the stepped member are physically integral with each other.

38. The light-emitting apparatus of claim 1, wherein the elongate planar member is physically separate from the stepped member.

32. A liquid crystal display, comprising:

a liquid crystal display panel having a plurality of LCD elements; and

a backlight positioned behind the display panel, the backlight comprising;

a plurality of adjacent, overlapping light-guide plates formed of light-transmissive material, wherein each of the light-guide plates has I) first and second ends, ii) one or more light-emitting surfaces, and iii) one or more reflective surfaces to redirect light within the light-guide plate;

wherein, where first and second light-guide plates are adjacent, the first end of the first light-guide plate A) underhangs the second end of the second light-guide plate, and B) is positioned opposite a primary light-emitting side of the apparatus;

a plurality of light sources, optically coupled to the first ends of the light-guide plates to illuminate the interiors of the light-guide plates; and

a substantially rigid and thermally conductive substrate on which the light-guide plates are assembled, the substrate comprising, for each of the light-guide plates, an elongate planar member which comprises a primary end and a secondary end, the planar member extending in a first direction from the primary end to the secondary end, the primary end comprising a stepped member which comprises;

a first planar section that extends upwardly from the elongate planar member, the first planar section comprising an upper end and a lower end; and

a second planar section at the upper end of the first planar section, the second planar section extending rearwardly from the first planar section in a second direction which is opposite from the first direction.

33. The LCD of claim 32, further comprising a light conditioner, positioned between the backlight and the LCD panel.

34. The LCD of claim 33, wherein the light conditioner comprises one or more light diffusing layers.

35. The LCD of claim 33, wherein the light conditioner comprises one or more prismatic layers.

36. The LCD of claim 33, wherein the light conditioner comprises one or more light polarizing layers.

37. A light-emitting apparatus, comprising:

a plurality of adjacent, overlapping light-guide plates, at least one of the light-guide plates including;

first and second ends, the first end of which is adapted to receive light emitted by a light source;

a first reflective surface extending between said first and second ends;

a second reflective surface, opposite the first reflective surface and extending from said first end;

a light-emitting surface, opposite the first reflective surface and extending from said second end;

a surface that intersects and joins said second reflective surface to said light-emitting surface;

wherein the first reflective surface forms an acute angle with said light-emitting surface; and

a substantially rigid and thermally conductive substrate on which the light-guide plates are assembled, the substrate comprising, for each of the light-guide plates, an elongate planar member which comprises a primary end and a secondary end, the planar member extending in a first direction from the primary end to the secondary end, the primary end comprising a stepped member which comprises;

a first planar section that extends upwardly from the elongate planar member the first planar section comprising an upper end and a lower end; and

a second planar section at the upper end of the first planar section, the second planar section extending rearwardly from the first planar section in a second direction which is opposite from the first direction.