LED control utilizing dynamic resistance of LEDs

• US 7,712,925 B2
• Filed: 08/18/2005
• Issued: 05/11/2010
• Est. Priority Date: 08/18/2004
• Status: Expired due to Fees

• Current Assignee: Remco Solid State Lighting, Inc.
• Original Assignee: Remco Solid State Lighting, Inc.
• Inventors: Russell, Ronald James
• Primary Examiner(s): Payne; Sharon E
• Application Number:
  US11/573,931
• Publication Number:
  US 20080219001A1
• Time in Patent Office: 1,727 Days
• Field of Search: 362/373, 362/650, 362/249.02, 362/294, 315/185.S, 327/544, 327/318
• US Class Current: 362/294
• 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 29/507 of means for protecting lighting devices from damage, e.g. housings
• 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 29/89 Metals
• CPC Class Codes: F21V 3/02 characterised by the shape
• CPC Class Codes: F21V 3/04 characterised by materials, surface treatments or coatings
• 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: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/3574 Emulating the electrical or functional characteristics of incandescent lamps
• CPC Class Codes: H05B 45/3578 Emulating the electrical or functional characteristics of discharge lamps
• CPC Class Codes: H05B 45/395 : Linear regulators
• CPC Class Codes: Y02B 20/30 : Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The present invention is directed to an LED light fixture. The LED light fixture comprises an interface for connecting the fixture to a source of electrical power, a power control section for supplying and controlling 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 and a light diffuser for diffusing the light from the LED array. The present invention is also directed to a novel power control for supplying and controlling power to an LED array comprising a non switching linear design based on a monolithic approach of power control whereby the load (the LED array) becomes part of the power control system.

Claims

1. An LED light fixture comprising an interface for connecting the fixture to a source of electrical power and providing power to an LED array producing a light of a suitable intensity and color, a power control section for controlling power in the LED array and a light diffuser for diffusing the light from the LED array, the power control section comprising an active bootstrap circuit connected to a low voltage side of the LED array, the active bootstrap circuit comprising a means for sensing current in the LED array and providing sensed current, which varies as a function of the dynamic resistance of the LED array, to a current regulator means to regulate current through said LED array to compensate for variations from a desired level caused by said dynamic resistance of said LED array.

2. An LED light fixture according to claim 1 wherein the light diffuser comprises an optical waveguide which provides for diffusion of the light from the LED array.

3. An LED light fixture according to claim 2 wherein the fixture includes a thermal core to which the LED array is thermally connected for thermal collection and dispersion of heat output of the LED array.

4. An LED light fixture according to claim 3 wherein the LED army comprises a mixture of LED bulbs providing a white light of a CRI of 85+.

5. An LED light fixture according to claim 4 wherein the interface is a screw base to allow the light fixture to replace a standard incandescent bulb.

6. An LED light fixture according to claim 5 wherein the thermal core comprises a ceramic disk sized to provide for the required dispersion of the heat output of the LED array.

7. An LED light fixture according to claim 6 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 adjacent the LED array.

8. An LED light fixture according to claim 7 wherein the LED array comprises a plurality of LED bulbs arranged on the surface of the ceramic thermal core.

9. An LED light fixture according to claim 4 wherein the LED array comprises a plurality of LED bulbs arranged in an elongate rectangular pattern to imitate a standard fluorescent fixture.

10. An LED light fixture according to claim 9 wherein the light diffuser wave guide includes an elongate prism adjacent the LED array to reflect the light generally perpendicularly sideways.

11. An LED light fixture according to claim 10 wherein the light diffuser wave guide further includes a diffuser panel having a generally triangular aoss section with the base of the generally triangular cross section optically coupled to the elongate prism.

12. An LED light fixture according to claim 1 wherein the bootstrap circuit includes a means for providing a predetermined fixed reference voltage to the current regulator means.

13. An LED light fixture according to claim 12 wherein the interface for connecting the fixture to a source of electrical power includes a means of connecting to a source of AC and a linear non-switching power supply to supply DC directly to a high side of the LED array.

14. A high voltage LED light source comprising an LED array in series with a low voltage power control section for current regulation through said LED array;

said LED array having sufficient LED'"'"'s in series to form a combined high intensity light source and a voltage step down device producing a low voltage supply powering said low voltage power control section;

said LED array having a dynamic resistance, said power control section comprising an active bootstrap circuit connected to a low voltage side of the LED array, the active bootstrap circuit comprising a means for sensing current in the LED array and providing the sensed current, which varies as a function of the dynamic resistance of the LED array, to a current regulator means to regulate current through said LED array to compensate for variations from a desired level caused by said dynamic resistance of said LED array.