Patent ID: 9137871
Filing Date: 2015-09-15
Classification: H05B

Abstract:
1. Method for operating a range of LEDs, which range of LEDs generates mixed light with at least two LED types of different spectrum connected in series, wherein the movement of the colour locus of the mixed light, which is caused by the different negative gradients of the temperature dependencies of the intensity of at least two different LED types, is reduced by circuitry without using measurements and feedback variables, wherein a compensation for the different negative gradients of the temperature dependencies of the intensity is achieved by a circuit branch which is passive and in parallel to at least a portion of the range of LEDs, the current curve of which has an essentially inverse temperature gradient regarding to the intensity variation to be compensated for, wherein the circuit branch comprises at least one passive temperature-dependent component, that is a part of a network for controlling a transistor, the base-emitter path of which is within the circuit branch, and wherein the passive temperature-dependent component is provided in parallel to the base-collector path of the transistor, so as to achieve the essentially inverse temperature gradient regarding to the intensity variation to be compensated for.