SYSTEM AND METHOD FOR POWER CONTROL IN A LED LUMINAIRE

• US 20070195527A1
• Filed: 02/19/2007
• Published: 08/23/2007
• Est. Priority Date: 08/18/2004
• Status: Active Grant

• Current Assignee: Remco Solid State Lighting, Inc.
• Original Assignee: Remco Solid State Lighting, Inc.
• Inventors: Russell, Ronald
• Granted Patent: US 7,658,510 B2
• Time in Patent Office: Days
• US Class Current: 362/240
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21S 8/026 intended to be recessed in a ceiling or like overhead structure, e.g. suspended ceiling
• CPC Class Codes: F21S 8/06 by suspension
• CPC Class Codes: F21S 8/086 with lighting device attached sideways of the standard, e.g. for roads and highways
• CPC Class Codes: F21V 29/506 of globes, bowls or cover glasses
• CPC Class Codes: F21V 29/74 with fins or blades
• CPC Class Codes: F21V 29/75 with fins or blades having different shapes, thicknesses or spacing
• CPC Class Codes: F21V 29/763 the planes containing the fins or blades having the direction of the light emitting axis
• CPC Class Codes: F21V 29/83 the elements having apertures, ducts or channels, e.g. heat radiation holes
• CPC Class Codes: F21V 3/02 characterised by the shape
• CPC Class Codes: F21W 2131/103 of streets or roads
• CPC Class Codes: F21Y 2107/60 on stacked substrates
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

The present invention is directed to an LED lighting source comprising a housing adapted for coupling to an AC power source; a rectifier circuit for converting the AC power to a DC supply; a power control circuit disposed in the housing and electrically connected to the DC supply; a string of LED'"'"'s electrically connected between a control node of the power control circuit and the DC supply, the LEDs in the string being connected in series and being of a number selected to produce a voltage difference across the power control circuit sufficient to power active components of said power control circuit when powered from the DC supply and the power control circuit for limiting a forward current through the string to a nominal forward current of a single LED.

Claims

1. A lighting source comprising:

a housing adapted for coupling to an AC power source;

a rectifier circuit for converting said AC power to a DC supply;

a power control circuit disposed in said housing and electrically connected to said DC supply;

a string of LED'"'"'s electrically connected between a control node of said power control circuit and said DC supply, the LEDs in the string being connected in series and being of a number selected to produce a voltage difference across said power control circuit sufficient to power active components of said power control circuit when powered from said DC supply and said power control circuit for limiting a forward current through said string to a nominal forward current of a single LED.

2. A lighting source as defined in claim 1, said power control circuit comprising a first transistor having its collector emitter terminals coupled via a current limiting resistor between said control node and ground and a voltage divider circuit coupled between said control node and ground for providing a constant base voltage bias to said transistor.

3. A lighting source as defined in claim 2, said voltage divider comprising a second transistor coupled between the base terminal of said first transistor and ground for determining said base voltage of said first transistor.

4. A lighting source as defined in claim 3, said voltage divider circuit comprising a third transistor having its collector emitter terminals coupled via a base current limiting resistor between said control node and the base terminal of said first transistor.

5. A lighting source as defined in claim 4, said transistors being bipolar junction transistors.

6. An LED light fixture comprising:

(a) an interface for connecting the fixture to a source of electrical power to provide power to an LED array producing a light of a suitable intensity and color for the task for which the fixture is to be used, the LED array including one or more strings of serially coupled LED'"'"'s;

(b) a light diffuser for diffusing the light from the LED array to produce suitable light for the task for which the fixture is to be used; and

(c) a power control section for controlling power in the LED array, at least one said string of LED'"'"'s electrically connected between a control node of said power control section and a DC power supply, the LEDs in the string being of a number selected to produce a voltage difference across said power control circuit sufficient to power active components of said power control circuit when powered from said DC supply and said power control circuit for limiting a forward current through said string to a nominal forward current of a single LED such that the power control section utilizes the dynamic resistance of the LED array as an active component of the control section.

7. An LED light fixture according to claim 6, said fixture including:

a) housing adapted for coupling to an AC power source;

b) a rectifier circuit for converting said AC power to a DC supply; and

c) said power control circuit disposed in said housing and electrically connected to said DC supply.

8. An LED light fixture according to claim 7 wherein the light diffuser comprises an optical waveguide for diffusion of the light from the LED array.

9. An LED light fixture according to claim 8 wherein the fixture includes a thermal core to which the LED array is thermally coupled for thermal collection and dispersion of heat output of the LED array.

10. An LED light fixture according to claim 9 wherein the LED array comprises LEDs providing a white light of a CRI of 85+.

11. An LED light fixture according to claim 10 wherein the interface is a screw base to allow the light fixture to replace a standard incandescent bulb.

12. An LED light fixture according to claim 11 wherein the thermal core comprises a ceramic disk sized to provide for the required dispersion of the heat output of the LED array when used at said suitable intensity.

13. An LED light fixture according to claim 12 wherein the light diffuser wave-guide has a generally cylindrical exterior surface and a generally conical interior surface with the apex of the conical interior surface arranged proximate the LED array.

14. An LED light fixture according to claim 13 wherein the light diffuser wave guide comprises a plurality of individual segments symmetrically arranged in a circular pattern, each of the segments having a generally convex exterior surface, a sloping inner surface sloping inwardly toward a center of the light fixture and generally vertical planar side surfaces.

15. An LED light fixture according to claim 10 wherein the LED array comprises a plurality of planar LED arrays, each said planar array arranged along one surface of an elongate rectangular thermal core to project a light substantially perpendicularly away from said surface.

16. An LED light fixture according to claim 15 including a light diffuser comprising an elongate prism arranged to couple light from said planar arrays and to refract a portion of said light in a direction generally planar with said surface.

17. An LED light fixture according to claim 16, wherein the light diffuser includes an elongate diffuser panel being of a generally right angled triangle in cross section with one side of the triangular diffuser abutting said elongate prism and an adjacent side of the diffuser lying in a plane with said surface said arrangement for optically coupling said refracted light from said elongate prism to said diffuser panel to diffuse said light in a direction generally perpendicular to said plane of said surface.

18. An LED light fixture according to claim 17, the thermal cores being a plurality of rectangular tubes, each having a plurality of apertures through at least two sides, such that when in use the apertures are on a top side and a side adjacent said top side of said rectangular tubes, further the apertures being arranged to align with corresponding apertures on adjacent rectangular tubes so as to allow for air flow through and across adjacent tubes.

19. An LED light fixture according to claim 18, including a pair of said elongate rectangular thermal cores and associated light diffuser and each light diffuser being arranged as a mirror image of the other.

20. An LED light fixture according to claim 10 wherein the LED array comprises a planar LED array, said planar array arranged on one surface of a rectangular thermal core to project a light substantially perpendicularly away from said surface.

21. An LED light fixture according to claim 14 including a light diffuser comprising a prism arranged to couple light from said planar array and to refract a portion of said light in a direction generally planar with said surface.

22. An LED light fixture according to claim 15, wherein the light diffuser includes an elongate diffuser panel being of a generally triangular cross section with one side of the triangular diffuser abutting said prism and an adjacent side of the diffuser lying in a plane with said surface said arrangement for optically coupling said refracted light from said prism to said diffuser panel to diffuse said light in a direction generally perpendicular to said plane of said surface.

23. An LED light fixture according to claim 22 including a light diffuser comprising a prism arranged to couple light from said planar array and to reflect said light in a direction generally planar with said surface.

24. An LED light fixture according to claim 23, wherein the light diffuser includes an elongate diffuser panel being of a generally triangular cross section with one side of the triangular diffuser abutting said prism and an adjacent side of the diffuser lying in a plane with said surface said arrangement for optically coupling said reflected light from said prism to said diffuser panel to diffuse said light in a direction generally perpendicular to said plane of said surface.

25. A high voltage LED light source comprising:

an LED array including a series coupled string of LED'"'"'s;

an ac to dc converter for converting said Ac supply to a DC supply;

a power control section for controlling power in the LED array, said series coupled string of LED'"'"'s electrically connected between a control node of said power control section and said DC power supply, the LEDs in the string being of a number selected to produce a voltage difference across said power control circuit sufficient to power active components of said power control circuit when powered from said DC supply and said power control circuit for limiting a forward current through said string to a nominal forward current of a single LED such that the power control section utilizes the dynamic resistance of the LED array as an active component of the control section.