Patent attributes
An illumination device comprising a plurality of light emitting diodes (LEDs) and a method for controlling the illumination device, so as to maintain a desired luminous flux and/or a desired color point of the device over variations in temperature and process, is provided herein. According to one embodiment, the method may include measuring a forward voltage developed across a first LED of the illumination device upon applying a first drive current to the first LED, determining a drive current needed to achieve a desired luminous flux from the first LED using the measured forward voltage, a table of stored calibration values correlating forward voltage and drive current to luminous flux at a plurality of different temperatures, and one or more interpolation techniques, and driving the first LED with the determined drive current to produce illumination having the desired luminous flux. The steps of measuring, determining and driving may be performed for each of the plurality of LEDs.
