Configurable LED lighting apparatus
AssigneeCree, Inc.
InventorEverett Bradford
Life of this patent
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Abstract
A configurable LED lighting system and its method of operation are disclosed. A lighting system or apparatus includes a string of LEDs, wherein specific LEDs are operable to emit different colors of light. The string includes a plurality of series-connected color segments. A shunt segment includes additional LEDs. The LED shunt segment is connected in parallel with at least one of the color segments. A controller is connected to the LED shunt segment to selectively balance drive current between the LED shunt segment and the color segment to which it is connected in parallel so that a color temperature of light is controllable by a processor. The diverted power still produces light and power is not wasted. The controller can use a polynomial equation or a look-up table to calculate color output values.
Claims34
A lighting system comprising:
- a string of LEDs, wherein specific LEDs are operable to emit different colors of light, the string further comprising a plurality of series-connected color segments;
- a shunt segment connected in parallel with at least one of the color segments, the shunt segment further comprising at least one additional LED;
- and
- a controller connected to the shunt segment to selectively balance drive current between the shunt segment and the color segment to which the shunt segment is connected in parallel so that a color temperature of light emitted from the lighting system is controllable by the controller.
A lighting system comprising:
- a string of LEDs, wherein specific LEDs are operable to emit different colors of light, the string further comprising a plurality of series-connected color segments;
- a passive shunt circuit connected in parallel with a first color segment from among the plurality of series-connected color segments;
- an LED shunt segment connected in parallel with a second color segment from among the plurality of series-connected color segments;
- and
- a controller connected to the passive shunt circuit and the LED shunt segment to selectively balance drive current between the passive shunt circuit and/or the LED shunt segment, and the first and/or second color segments, so that a color temperature of light emitted from the lighting system is controllable by the controller.
A solid-state light-emitting apparatus comprising:
- first, second, and third series-connected color segments of series-connected LEDs connectable to a power supply, each color segment of LEDs operable to emit light of a differing color;
- a passive shunt circuit connected in parallel with the first color segment of LEDs;
- an LED shunt segment comprising LEDs operable to emit light of an additional color, the LED shunt segment connected in parallel with the second color segment of LEDs;
- and
- a controller connected to the passive shunt circuit and the LED shunt segment to independently and selectively divert drive current from the first and second color segments so that a color temperature of light emitted from the apparatus is controllable by the controller.
A method of setting a color temperature for an LED lighting system, the method comprising:
- determining the color temperature to be emitted by the LED lighting system based on user input, varying input current and/or voltage for a power supply, or both;
- measuring a drive current for a string of LEDs comprising a plurality series-connected color segments of series-connected LEDs;
- calculating, using a processor, output values for at least some of the plurality of color segments to achieve the color temperature;
- outputting by the processor a pulse-width modulation (PWM) signal to divert drive current from the color segments at least to an LED shunt segment comprising LEDs operable to emit light of an additional color, the LED shunt segment connected in parallel with one of the color segments;
- and
- repeating the above in response to a change in the drive current and in response to user input, input current and/or voltage for the power supply, or both.
Dependencies are inferred from the claim text.