Thin luminaire for general lighting applications

• US 7,494,246 B2
• Filed: 06/06/2007
• Issued: 02/24/2009
• Est. Priority Date: 06/06/2007
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Harbers, Gerard, Bierhuizen, Serge
• Primary Examiner(s): O'Shea; Sandra
• Assistant Examiner(s): HAN, JASON
• Application Number:
  US11/758,952
• Publication Number:
  US 20080304250A1
• Time in Patent Office: 629 Days
• Field of Search: 362/97, 362222-223, 362/225, 362/240, 362/249, 362300-301
• US Class Current: 362/249.02
• CPC Class Codes: F21S 8/04 intended only for mounting on a ceiling or the like overhead structures F21S8/02 takes precedence; details of ceiling bases F21V21/03
• CPC Class Codes: F21V 11/14 with many small apertures
• CPC Class Codes: F21V 15/01 Housings, e.g. material or assembling of housing parts F21V15/02 takes precedence housings forming signs or letters G09F13/04
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 7/0008 providing for indirect lighting
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2103/10 comprising a linear array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]

Abstract

High power white light LEDs are distributed within a thin reflective cavity. The cavity depth may be less than 3 cm and, in one embodiment, is about 1 cm. A light output surface of the cavity is a flat reflector with many small openings. A small plastic lens is positioned over each opening for causing the light emitted from each opening to form a cone of light between approximately 50-75 degrees. Alternatively, each hole may be shaped to be a truncated cone to control the dispersion. The light emitted by the LEDs is mixed in the cavity by reflecting off all six reflective walls of the cavity. The light will ultimately escape through the many holes, forming a relatively uniform pattern of light on a surface to be illuminated by the luminaire.

Claims

1. A luminaire for illuminating a remote object comprising:

a cavity having a reflective base surface and reflective side walls;

a plurality of light emitting diodes (LEDs) affixed within the cavity; and

the cavity having a flat reflective light output surface, opposite to the reflective base surface, containing a plurality of light emitting holes, there being more holes than LEDs, wherein the holes make up at least 10% of a total surface area of the top surface of the cavity, wherein light emitted by the luminaire in the vicinity of substantially each hole has a controlled dispersion angle of between about 45-90 degrees, as measured by the angle where a light brightness is one-half of a peak brightness within the angle, wherein a lens is disposed over each hole to provide the control dispersion angle,

the cavity having a depth of less than 5 cm,

wherein light emitted by the luminaire provides a substantially uniform illumination of a flat object a particular distance away from the flat reflective light output surface of the luminaire.

2. The luminaire of claim 1 wherein the substantially uniform illumination of a flat object a particular distance away from the flat reflective light output surface of the luminaire comprises:

the luminaire illuminating a flat surface of an object having a dimension equal to a dimension of the light output surface of the luminaire, the flat surface of the object being 1 foot away from the light output surface of the luminaire, the illumination of every area of the flat surface of the object being within 75% of the peak brightness of the illumination of the flat surface of the object.

3. The luminaire of claim 1 wherein substantially each hole has a controlled dispersion angle of less than about 60 degrees, as measured by the angle where a light brightness is one-half of a peak brightness within the angle.

4. The luminaire of claim 1 further comprising a circuit board supporting a plurality of the LEDs.

5. The luminaire of claim 1 wherein the LEDs are mounted over the base surface of the cavity.

6. The luminaire of claim 1 wherein the LEDs are mounted over the flat reflective light output surface of the cavity.

7. The luminaire of claim 1 wherein a pitch of the LEDs is at least about 2.5 cm.

8. The luminaire of claim 1 wherein the LEDs are arranged in a single straight line within the cavity.

9. The luminaire of claim 1 wherein the LEDs are arranged in a two-dimensional array within the cavity.

10. The luminaire of claim 1 wherein substantially each hole is shaped to be other than cylindrical to provide the controlled dispersion angle.

11. The luminaire of claim 1 wherein substantially each hole is shaped to be other than cylindrical.

12. The luminaire of claim 1 wherein the cavity has a depth of less than ten times a height of a single LED in the cavity.

13. The luminaire of claim 1 wherein the cavity has a depth of less than five times a height of a single LED in the cavity.

14. The luminaire of claim 1 wherein the cavity has a depth of less than about three cm.

15. The luminaire of claim 1 wherein the cavity has a depth of less than about one cm.

16. The luminaire of claim 1 wherein the holes are arranged in an orderly pattern.

17. The luminaire of claim 1 wherein a density of holes substantially over each LED is less than a density of holes away from over each LED.

18. The luminaire of claim 1 wherein inner walls of the cavity are substantially specular.

19. The luminaire of claim 1 wherein inner walls of the cavity are diffusing.

20. The luminaire of claim 1 wherein the cavity is rectangular and elongated.

21. The luminaire of claim 1 wherein the LEDs comprise:

LED dies that emit blue light; and

a phosphor over at least a portion of each LED die that emits a light that, when combined with blue light, produces white light.

22. The luminaire of claim 1 wherein the LEDs comprise:

LED dies that emit blue light; and

a phosphor coating over at least one inner surface of the cavity that emits a light that, when combined with blue light, produces white light.

23. The luminaire of claim 1 wherein the LEDs are side-emitting LEDs.