Lighting device with point-shaped light sources

• US 6,964,497 B2
• Filed: 01/16/2002
• Issued: 11/15/2005
• Est. Priority Date: 01/20/2001
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Greiner, Horst
• Primary Examiner(s): CARIASO, ALAN B
• Application Number:
  US10/050,260
• Publication Number:
  US 20020097578A1
• Time in Patent Office: 1,399 Days
• Field of Search: 362 26- 31, 362/240, 362/241, 362/245, 362/247, 362/248, 362/297, 362/307, 362/311, 362/555, 362/560, 362/561
• US Class Current: 362/241
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133603 with LEDs

Abstract

A lighting device is described which comprises a light emission surface (11) and a plurality of substantially point-shaped light sources (21) such as, for example, LEDs, and which is suitable in particular for backlighting liquid crystal displays such as LCD picture screens, or for use as a planar light radiator. The lighting device is characterized in particular in that an optical waveguide plate (1) is provided with a plurality of cavities (20) for the light sources (21), which cavities are covered with a first reflecting layer (204) on their upper sides (203) facing the light emission surface (11), while the coupling of the light into the optical waveguide plate takes place through side walls (201) of the cavities. A very homogeneous distribution of the luminous intensity on the light emission surface is achieved thereby.

Claims

1. A lighting device, comprising:

a light emission surface;

a plurality of substantially point-shaped light sources; and

an optical waveguide plate into which a plurality of cavities is provided, each cavity accommodating a light source and including an upper side closest to the light emission surface and side wails that allow coupling of light therethrough into the optical waveguide plate, said upper side being covered with a first reflecting layer,

said cavities extending substantially less than the entire distance through the optical waveguide plate toward the light emission surface, such that a portion of the light coupled from one of the cavities through the side walls can reach and be emitted from an area of the light emission surface directly above said one of the cavities.

2. The lighting device of claim 1, wherein the side walls of the cavities are substantially perpendicular to the light emission surface, and the upper sides of the cavities are substantially parallel to the light emission surface.

3. The lighting device of claim 1, wherein the cavities are each covered with a second reflecting layer on their lower side opposite to their upper side.

4. The lighting device of claim 1, wherein the cavities are substantially cylindrical in shape.

5. The lighting device of claim 1, wherein the cavities are provided in the lower side of the optical waveguide plate.

6. The lighting device of claim 1, wherein the light sources are light-emitting diodes.

7. A lighting device, comprising:

a light emission surface;

a plurality of substantially point-shaped light sources; and

an optical waveguide plate into which a plurality of cavities is provided, each cavity accommodating a light source and including an upper side closest to the light emission surface and side walls that allow coupling of light therethrough into the optical waveguide plate, said upper side being covered with a first reflecting layer,

wherein the cavities are each covered with a second reflecting layer on their lower side opposite to their upper side, and the second reflecting layer extends over the side faces and the lower side of the optical waveguide plate.

8. A lighting device, comprising:

a light emission surface;

a plurality of first reflecting layers;

a second reflecting layer;

a plurality of substantially point-shaped light sources; and

an optical waveguide plate having at least two side faces, and also having, between the at least two side faces, an underside into which a plurality of cavities is provided, each cavity accommodating a respective one of the light sources, which cavities each comprise an upper side and side walls, the upper side of each cavity facing the light emission surface, said upper side being covered with a respective one of the first reflecting layers, while the coupling of the light into the optical waveguide plate takes place through the side walls, wherein;

the cavities are each covered by the second reflecting layer on their lower side opposite to their upper side;

the second reflecting layer extends over the side faces and the underside of the optical waveguide plate; and

the second reflecting layer is at a distance from the optical waveguide plate, which distance constitutes an air gap.

9. A lighting device, comprising:

a light emission surface;

a plurality of substantially point-shaped light sources; and

an optical waveguide plate into which a plurality of cavities is provided, each cavity accommodating a light source, which cavities each comprise an upper side facing the light emission surface and side walls, said upper side being covered with a first reflecting layer, while the coupling of the light into the optical waveguide plate takes place through the side walls,

wherein the first reflecting layer extends further in horizontal direction with a first portion into the optical waveguide plate.

10. A lighting device, comprising:

a light emission surface;

a plurality of substantially point-shaped light sources; and

an optical waveguide plate into which a plurality of cavities is provided, each cavity accommodating a light source, which cavities each comprise an upper side facing the light emission surface and side walls, said upper side being covered with a first reflecting layer, while the coupling of the light into the optical waveguide plate takes place through the side walls,

wherein the first reflecting layer extends further with a second portion along the side walls of the cavity.

11. The lighting device of claim 10, wherein the edges of the cavities situated opposite the upper side are surrounded by another reflecting layer.

12. A liquid crystal display device incorporating the lighting device of claim 10.

13. A lighting device, comprising:

a light emission surface;

first and second reflecting layers;

an optical waveguide plate including side faces and an underside therebetween into which at least one cavity is provided that extends substantially less than the entire distance through the optical waveguide plate toward the light emission surface, the cavity including an upper side closest to the light emission surface, a lower side opposite the upper side, and at least one side wall allowing coupling of light into the optical waveguide plate; and

at least one light source accommodated within the cavity,

the upper side being substantially covered by the first reflecting layer and the lower side being substantially covered by the second reflecting layer.

14. The lighting device of claim 13, wherein the light source is a light-emitting diode.

15. The lighting device of claim 13, wherein the second reflecting layer extends over the underside and the side faces of the optical waveguide plate.

20. The lighting device of claim 13, wherein the side wall of the cavity is substantially perpendicular to the light emission surface, and the upper side of the cavity is substantially parallel to the light emission surface.

21. A display device incorporating the lighting device of claim 13.

16. A lighting device, comprising:

a light emission surface;

first and second reflecting layers;

an optical waveguide plate including side faces and an underside therebetween into which at least one cavity is provided, the cavity including an upper side closest to the light emission surface, a lower side opposite the upper side, and at least one side wall allowing coupling of light into the optical waveguide plate; and

at least one light source accommodated within the cavity,

the upper side being substantially covered by the first reflecting layer and the lower side being substantially covered by the second reflecting layer,

wherein the light source is a light-emitting diode, the second reflecting layer extends over the underside and the side faces of the optical waveguide plate, and the second reflecting layer is at a distance from the optical waveguide plate, which distance constitutes an air gap.

17. A lighting device comprising:

a light emission surface;

first and second reflecting layers;

an optical waveguide plate including side faces and an underside therebetween into which at least one cavity is provided, the cavity including an upper side closest to the light emission surface, a lower side opposite the upper side, and at least one side wall allowing coupling of light into the optical waveguide plate; and

at least one light source accommodated within the cavity,

the upper side being substantially covered by the first reflecting layer and the lower side being substantially covered by the second reflecting layer,

wherein the first reflecting layer extends beyond the cavity into the optical waveguide plate.

18. A lighting device comprising;

a light emission surface;

first and second reflecting layers;

an optical waveguide plate including side faces and an underside therebetween into which at least one cavity is provided, the cavity including an upper side closest to the light emission surface, a lower side opposite the upper side, and at least one side wall allowing coupling of light into the optical waveguide plate; and

at least one light source accommodated within the cavity,

the upper side being substantially covered by the first reflecting layer and the lower side being substantially covered by the second reflecting layer,

wherein the first reflecting layer extends along the side wall of the cavity.

19. A lighting device, comprising:

a light emmission surface;

first and second reflecting layers;

an optical waveguide plate including side faces and an underside therebetween into which at least one cavity is provided, the cavity including an upper side closest to the light emission surface, a lower side opposite the upper side, and at least one side wall allowing coupling of light into the optical waveguide plate; and

at least one light source accommodated within the cavity,

the upper side being substantially covered by the first reflecting layer and the lower side being substantially covered by the second reflecting layer,

wherein an edge of the cavity situated opposite the upper side is surrounded by a third reflecting layer.