US 2009/0153075 A1 · COLOR CONTROL METHOD FOR LED LIGHTING SYSTEMS

Abstract

When temperature variation occurs to the LED dice of an LED lighting system, a feedback control mechanism is applied to compensate temperature-related wavelength shift for precisely controlling the light generated by the LED dice based on the voltage drop variation or current variation of the LED dice. The color control method for the LED lighting system includes a preliminary detection phase and a feedback control phase. In the preliminary detection phase, voltage drop signals or current signals together with corresponding color and hue signals of each LED module of the LED lighting system are detected. In the feedback control phase, signal compensating processes are performed to precisely control the light generated by the LED lighting system based on the voltage drop variation or the current variation in conjunction with the corresponding color and hue signals generated in the preliminary detection phase.

A color control method for an LED lighting system, the LED lighting system comprising a red LED module, a green LED module, and a blue LED module, the color control method comprising:

providing a first driving current to the red LED module during a first interval;
generating a first feedback voltage corresponding to the red LED module based on a first voltage drop corresponding to the red LED module, and generating a first red light signal, a first green light signal, a first blue light signal, and a first set of CIE tristimulus values corresponding to the red LED module through detecting light emitted from the red LED module at a first time of the first interval;
generating a second feedback voltage corresponding to the red LED module based on a second voltage drop corresponding to the red LED module, and generating a second red light signal, a second green light signal, a second blue light signal, and a second set of CIE tristimulus values corresponding to the red LED module through detecting light emitted from the red LED module at a second time of the first interval;
providing a second driving current to the green LED module during a second interval;
generating a first feedback voltage corresponding to the green LED module based on a first voltage drop corresponding to the green LED module, and generating a first red light signal, a first green light signal, a first blue light signal, and a first set of CIE tristimulus values corresponding to the green LED module through detecting light emitted from the green LED module at a first time of the second interval;
generating a second feedback voltage corresponding to the green LED module based on a second voltage drop corresponding to the green LED module, and generating a second red light signal, a second green light signal, a second blue light signal, and a second set of CIE tristimulus values corresponding to the green LED module through detecting light emitted from the green LED module at a second time of the second interval;
providing a third driving current to the blue LED module during a third interval;
generating a first feedback voltage corresponding to the blue LED module based on a first voltage drop corresponding to the blue LED module, and generating a first red light signal, a first green light signal, a first blue light signal, and a first set of CIE tristimulus values corresponding to the blue LED module through detecting light emitted from the blue LED module at a first time of the third interval;
generating a second feedback voltage corresponding to the blue LED module based on a second voltage drop corresponding to the blue LED module, and generating a second red light signal, a second green light signal, a second blue light signal, and a second set of CIE tristimulus values corresponding to the blue LED module through detecting light emitted from the blue LED module at a second time of the third interval;
providing the first driving current to the red LED module, providing the second driving current to the green LED module, and providing the third driving current to the blue LED module;
generating a third feedback voltage corresponding to the red LED module based on a third voltage drop corresponding to the red LED module;
generating a third set of CIE tristimulus values corresponding to the red LED module based on the third feedback voltage, the first feedback voltage, the second feedback voltage, the first set of CIE tristimulus values, and the second set of CIE tristimulus values corresponding to the red LED module;
generating a third red light signal, a third green light signal, and a third blue light signal corresponding to the red LED module based on the third feedback voltage, the first feedback voltage, the second feedback voltage, the first red light signal, the first green light signal, the first blue light signal, the second red light signal, the second green light signal, the second blue light signal corresponding to the red LED module;
generating a third feedback voltage corresponding to the green LED module based on a third voltage drop corresponding to the green LED module;
generating a third set of CIE tristimulus values corresponding to the green LED module based on the third feedback voltage, the first feedback voltage, the second feedback voltage, the first set of CIE tristimulus values, and the second set of CIE tristimulus values corresponding to the green LED module;
generating a third red light signal, a third green light signal, and a third blue light signal corresponding to the green LED module based on the third feedback voltage, the first feedback voltage, the second feedback voltage, the first red light signal, the first green light signal, the first blue light signal, the second red light signal, the second green light signal, the second blue light signal corresponding to the green LED module;
generating a third feedback voltage corresponding to the blue LED module based on a third voltage drop corresponding to the blue LED module;
generating a third set of CIE tristimulus values corresponding to the blue LED module based on the third feedback voltage, the first feedback voltage, the second feedback voltage, the first set of CIE tristimulus values, and the second set of CIE tristimulus values corresponding to the blue LED module;
generating a third red light signal, a third green light signal, and a third blue light signal corresponding to the blue LED module based on the third feedback voltage, the first feedback voltage, the second feedback voltage, the first red light signal, the first green light signal, the first blue light signal, the second red light signal, the second green light signal, the second blue light signal corresponding to the blue LED module;
calculating a first coefficient matrix based on the third set of CIE tristimulus values, the third red light signal, the third green light signal, and the third blue light signal corresponding to the red LED module, the third set of CIE tristimulus values, the third red light signal, the third green light signal, and the third blue light signal corresponding to the green LED module, and the third set of CIE tristimulus values, the third red light signal, the third green light signal, and the third blue light signal corresponding to the blue LED module;
calculating a first control signal, a second control signal, and a third control signal based on the first coefficient matrix and a set of preset CIE tristimulus values;
and
regulating the first driving current based on the first control signal, regulating the second driving current based on the second control signal, and regulating the third driving current based on the third control signal;
wherein the first interval, the second interval, and the third interval are not overlapped between each other.

21 more elements

Color control method for led lighting systems

Life of this patent

Color control method for led lighting systems

Life of this patent

Abstract

Claims25