Led lighting system

• US 20040135522A1
• Filed: 01/15/2003
• Published: 07/15/2004
• Est. Priority Date: 01/15/2003
• Status: Active Grant

• Current Assignee: Luminator Holding LP (LTG Acquisition, Inc.)
• Original Assignee: Luminator Holding LP (LTG Acquisition, Inc.)
• Inventors: Berman, George, Gunter, John Bartholomew, Graves, Jerry Haden
• Granted Patent: US 7,148,632 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A lighting device that can generate light of variable color and intensity under processor control is described. Multiple lighting devices can be incorporated into a lighting system to illuminate larger areas. Each lighting device may have a modular architecture in which a lighting module is coupled to one or more additional modules that provide power and control the operation of the lighting module. The lighting module includes three groups of LEDs each of which generates light of a different color whose intensity can be controlled. In one version, the colors of the three groups are green, red and blue and the LEDs are arranged in a line in a repeating pattern. A lighting system can be formed by coupling multiple lighting devices to a central controller comprising an operator interface panel and an interface to an external computer. The external computer can be provided with programming tools that allow the creation of lighting programs for controlling the operation of the lighting system. The lighting programs developed on the external computer can then be downloaded to the central controller which then carries out the downloaded programs in conjunction with the lighting devices coupled thereto. A user can select programs or modify the operation of the lighting system from the operator interface panel provided at the central controller. A user can also control the operation of the lighting system directly from the external computer while it is coupled to the central controller. Procedures are provided for calibrating the color and power output of each lighting device.

Claims

1. A light emitting diode (LED) lighting device comprising:

a first group of LEDs of a first color;

a second group of LEDs of a second color; and

a third group of LEDs of a third color;

wherein;

each group of LEDs comprises a plurality of LED strings coupled in parallel, each LED string comprising one or more LEDs coupled in series, and

the first, second and third groups of LEDs are arranged substantially along a line so that LEDs of the same LED string are separated by one or more LEDs of a different LED string.

2. The LED lighting device of claim 1, wherein:

each LED string has a forward voltage that is a function of the number of LEDs in the LED string; and

the number of LEDs in each LED string is selected so that the forward voltages of all LED strings are substantially the same.

3. The LED lighting device of claim 2, wherein at least one of the first, second and third groups of LEDs includes a ballast LED.

4. The LED lighting device of claim 1, wherein the first, second and third colors are selected from the group of colors consisting of red, orange, green and blue.

5. The LED lighting device of claim 1, wherein the first, second and third colors have respective wavelengths that are at least 30 nm apart.

6. The LED lighting device of claim 1 comprising:

a control circuit, the control circuit being coupled to each of the groups of LEDs and comprising a data interface, wherein the control circuit independently controls each group of LEDs in accordance with data received at the data interface.

7. The LED lighting device of claim 6, wherein the control circuit includes:

a processor, the processor being coupled to the data interface;

a controllable current source for each group of LEDs, the controllable current source being controlled by the processor.

8. The LED lighting device of claim 7, wherein the control circuit includes:

a current monitor for each group of LEDs, the current monitor monitoring the current through its respective group of LEDs and providing a reading of the current to the processor.

9. The LED lighting device of claim 6 comprising:

a power circuit, the power circuit being coupled to each of the groups of LEDs and to the control circuit.

10. The LED lighting device of claim 9, wherein the power circuit includes a variable power supply, the variable power supply generating a voltage whose magnitude is controlled by the processor.

11. A lighting system comprising the LED lighting device of claim 1 and a central controller coupled to the LED lighting device.

12. The lighting system of claim 11, wherein the central controller includes:

an operator interface panel;

a computer interface; and

a switch for selectively coupling the operator interface panel and the computer interface to the LED lighting device.

13. The lighting system of claim 11 comprising an additional LED lighting device.

14. A method of calibrating power provided to one or more light emitting diodes (LEDs), wherein a voltage is applied across the one or more LEDs, the method comprising the steps of:

measuring a current through the one or more LEDs;

comparing the measured current to a predetermined current level;

adjusting the voltage in accordance with the comparison.

15. The method of claim 14, wherein the adjusting step includes increasing the voltage if the measured current is less than the predetermined current level.

16. The method of claim 14, wherein the measuring step includes measuring a voltage across a known resistance in series with the one or more LEDs.

17. A method of calibrating a color of light formed by a combination of light emitted by a plurality of light emitting devices of at least three different colors, the method comprising the steps of:

measuring first and second parameters of the combined light;

comparing the first and second parameters to first and second desired ranges of values, respectively;

adjusting the light emitted by the plurality of light emitting devices so that the measured first and second parameters are within the first and second desired ranges of values, respectively.

18. The method of claim 17, wherein the first and second parameters are color rendering index (CRI) and correlated color temperature (CCT).

19. The method of claim 17, wherein the first and second parameters include tristimulus values.