LED lighting apparatus with colour mixing
In comparison with thermal light sources, LED lighting has the advantage that it is very small and at the same time commercially available in different colors, so that colored lighting can be produced inexpensively and at the same time in a manner that saves installation space. It is an object of the present invention to equip an LED lighting apparatus with a color mixing functionality that is distinguished by high efficiency and at the same time a small number of components.
1. An LED lighting apparatus comprising:
a colour mixing unit, wherein the colour mixing unit comprises at least a first colour group of LEDs and a second colour group of LEDs, wherein the LEDs in the colour groups differ by virtue of the light colour;
a power supply for supplying a supply voltage to the colour mixing unit, wherein the supply voltage is in the form of a rectified AC voltage, wherein a repetition rate of half cycles of the supply voltage defines a voltage frequency; and
a control device for selectively activating and deactivating the colour groups, wherein the colour mixing unit produces a mixed colour by means of the selectively activated and deactivated colour groups,
wherein a repetition rate of a colour time window defines a colour mixing frequency, wherein the control device is configured to actuate the colour groups, such that the colour groups are activated within the colour time window in succession to produce the mixed colour during the colour time window.
2. The LED lighting apparatus according to claim 1 , wherein no more than a single colour group is activated at the same time in the colour mixing unit within the colour time window.
3. The LED lighting apparatus according to claim 1 , wherein for a mixed colour, at least one changeover operation between the colour groups is effected during the colour time window.
4. The LED lighting apparatus according to claim 1 , wherein the colour mixing frequency is greater than 30 hertz.
5. The LED lighting apparatus according to claim 1 , wherein the colour mixing frequency corresponds to the voltage frequency or wherein the colour time window is in a form with the same temporal length as one of the half-cycles.
6. The LED lighting apparatus according to claim 1 , wherein the half-cycles and the colour time windows are arranged in a manner staggered over time in relation to one another by a phase angle.
7. The LED lighting apparatus according to claim 6 , wherein the phase angle is chosen on the basis of the mixed colour.
8. The LED lighting apparatus according to claim 1 , wherein the colour mixing frequency is lower than the voltage frequency or wherein the colour time window is in a form with greater temporal length than one half-cycle.
9. The LED lighting apparatus according to claim 8 , wherein the quotient between voltage frequency and colour mixing frequency or the quotient between colour time window and half-cycle is in the form of a rational number.
10. The LED lighting apparatus according to claim 8 , wherein the value of the voltage frequency is an integer multiple of the value of the colour mixing frequency or wherein the length of the colour time window is an integer multiple of the value of the temporal length of the half-cycle.
11. The LED lighting apparatus according to claim 8 , wherein a number of x successive colour time windows are associated with a number of y successive half-cycles, wherein the x colour time windows form a colour period and the y half-cycles form a voltage period, wherein the colour period and the voltage period are in a form with the same length and arranged or arrangeable in a manner staggered over time in relation to one another by a phase angle.
12. The LED lighting apparatus according to claim 1 , further comprising a switching arrangement, wherein the switching arrangement is configured to put the LEDs in a colour group into at least two switching states, wherein the switching states differ by virtue of the on-state voltage of the colour group.
13. The LED lighting apparatus according to claim 12 , wherein the control device actuates the colour groups in the event of activation, such that a switching state with an on-state voltage is activated, wherein the on-state voltage is less than or equal to the instantaneous value of the supply voltage.
14. The LED lighting apparatus according to claim 12 , wherein the switching state, which has the highest on-state voltage that is less than or equal to the instantaneous value of the supply voltage, is activated.
15. A method for operating the LED lighting apparatus according to claim 1 ,
wherein the control device selectively activates and deactivates the colour groups, so that a mixed colour is produced,
wherein the colour groups are actuated within the colour time window, such that the colour groups are activated in succession to produce the mixed colour during the colour time window.