Regulating systems

1. A regulating system comprising:

a tricolor LED system comprising:

at least one first LED that emits light having a first color,

at least one second LED that emits light having a second color, and

at least one third LED that emits light having a third color,

at least one fourth LED that emits light having a fourth color,

a sensor that detects light emitted by the LEDs and generating sensor signals representing characteristics of the light, wherein the sensor is an RGB sensor that measures characteristics of mixed light emitted by the tricolor LED system and the fourth LED during a first time interval and generates a triple set of values representing the characteristics of the mixed light, and the sensor measures characteristics of light emitted by the fourth LED during a second time interval, where the tricolor LED system does not emit light, and generates a triple set of values representing the characteristics of the light emitted by the fourth LED,

a controller that outputs control signals depending on the sensor signals and reference values, and

LED drivers that drive the first, second, third and fourth LEDs depending on the control signals.

2. The regulating system according to claim 1 , wherein the sensor is an RGB sensor that generates a triple set of values representing the characteristics of the light.

3. The regulating system according to claim 1 , wherein the control signals are generated depending on reference 1) tristimulus values and 2) feedback tristimulus values representing characteristics of the light detected by the sensor.

4. The regulating system according to claim 3 , wherein

the reference tristimulus values comprise a triple set of tristimulus values including an X value, a Y value and a Z value and

the feedback tristimulus values comprise a triple set of tristimulus values including an X′ value, a Y′ value and a Z′ value, the triple set representing characteristics of the mixed light emitted by the tricolor LED system and the fourth LED or of the light emitted by the tricolor LED system,

the control signal that drives the first LED being generated depending on an error between an X value of the reference tristimulus values and an X′ value of the feedback tristimulus values,

the control signal that drives the second LED being generated depending on an error between a Y value of the reference tristimulus values and a Y′ value of the feedback tristimulus values, and

the control signal that drives the third LED being generated depending on an error between a Z value of the reference tristimulus values and a Z′ value of the feedback tristimulus values.

5. The regulating system according to claim 4 , wherein

the reference tristimulus values comprise a further tristimulus value being one of an X value, a Y value and a Z value and

the feedback tristimulus values comprise a further tristimulus value being one of an X′ value, a Y′ value and a Z′ value, the further tristimulus value representing the characteristic of the light emitted by the fourth LED,

the control signal that drives the fourth LEDs is generated depending on an error between at least the further tristimulus value of the reference tristimulus values and the further tristimulus value of the feedback tristimulus values.

6. The regulating system according to claim 3 , wherein

the reference tristimulus values comprise a further tristimulus value being one of an X value, a Y value and a Z value and

the feedback tristimulus values comprise a further tristimulus value being one of an X′ value, a Y′ value and a Z′ value, the further tristimulus value representing the characteristic of the light emitted by the fourth LED,

the control signal that drives the fourth LEDs is generated depending on an error between at least the further tristimulus value of the reference tristimulus values and the further tristimulus value of the feedback tristimulus values.

7. The regulating system according to claim 1 , wherein the control signals are generated depending on reference 1) tristimulus values and 2) feedback tristimulus values representing characteristics of the light detected by the sensor.

8. The regulating system according to claim 1 , wherein the controller is a proportional-integral (PI) controller.

9. The regulating system according to claim 1 , further comprising an additional controller that adjusts the reference values depending on the control signals and a reference control value.

10. The regulating system according to claim 9 , further comprising a comparator that outputs a maximum value of the control signals and a summing block outputting an error signal between the reference control value and the maximum value applied to the additional controller.

11. The regulating system according to claim 10 , wherein the additional controller is a proportional-integral (PI) controller.

12. The regulating system according to claim 9 , wherein the additional controller is a proportional-integral (PI) controller.

13. The regulating system according to claim 1 , wherein the controller generates pulse width modulation (PWM) signals.

14. The regulating system according to claim 1 , wherein the reference values represent characteristics of a predetermined power spectral density.

15. The regulating system according to claim 1 , wherein the tricolor LED system comprises a red light emitting LED, a green light emitting LED and a blue light emitting LED.

16. The regulating system according to claim 1 , wherein the fourth LED is a white light emitting broadband spectrum LED.