LED lighting system
View Patent ↗A lighting device that can generate light of variable color and intensity under processor control. Multiple lighting devices of a modular design can be incorporated into a lighting system to illuminate larger areas. A lighting module includes three groups of LEDs each of which generates light of a different color whose intensity can be controlled. 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. A user can select programs or modify the operation of the lighting system from the operator interface panel provided at the central controller or from the external computer. Procedures are provided for calibrating the color and power output of each lighting device.
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;
a third group of LEDs of a third color; and
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 and includes:
a processor, the processor being coupled to the data interface, and
a controllable current source for each group of LEDs, the controllable current source being controlled by the processor,
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
at least one of the first, second and third groups of LEDs includes one or more ballast LEDs, and the light emitted from each of the one or more ballast LEDs is obscured from combining with light emitted by other LEDs in the first, second and third groups of LEDs.
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 and ballast 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 1 , wherein the first, second and third colors are selected from the group of colors consisting of red, orange, green and blue.
4. The LED lighting device of claim 1 , wherein the first, second and third colors have respective wavelengths that are at least 30 nm apart.
5. A lighting system comprising the LED lighting device of claim 1 and a central controller coupled to the LED lighting device.
6. The lighting system of claim 5 comprising an additional LED lighting device.
7. The LED lighting device of claim 1 , wherein 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.
8. 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;
a third group of LEDs of a third color;
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 and 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, and
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, and
a power circuit, the power circuit being coupled to each of the groups of LEDs and to the control circuit, and including
a variable power supply, the variable power supply generating a voltage whose magnitude is controlled by the processor,
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 processor controls the variable power supply to adjust a voltage V Reg supplied at a common anode of each of the plurality of LED strings to set the voltage V Reg at a lowest level required to produce a first predetermined current for the first group of LEDs, a second predetermined current for the second group of LEDs and a third predetermined current for the third group of LEDs, wherein the currents produced by each of the first, second and third groups of LEDs as respectively measured by the current monitor of each of the first, second and third groups.
9. The lighting system of claim 8 , 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.
10. The LED lighting device of claim 8 , wherein the processor controls the variable power supply to incrementally increase the voltage V Reg over a low range value until the measured currents for each of the first, second and third groups of LEDs respectively equal or exceed the first, second and third predetermined currents.
11. The LED lighting device of claim 8 , wherein each predetermined current value represents a nominal current value for its respective group.
12. The LED lighting device of claim 11 , wherein each nominal current value is a determined as a function of the number of LED strings in its respective group and the number of LEDs in each string of the respective group.