Patent ID: 8581837

Claim:
Method for tracking sweet spots of a sweet spot unit of a display, where the sweet spot unit comprises an illumination matrix with a multitude of controllable illumination elements, and imaging means in order to image directed light in the form of sweet spots on to the eyes of at least one observer, said light being modulated with an image information by pixels of an image matrix, and where a position finder detects position information of the observer eyes to be transmitted to a control unit, which uses the position information to determine illumination elements to be activated for generating sweet spots for the detected observer eye positions, wherein the control unit defines reference points around each observer eye with the help of the position information, said reference points defining the geometry of an extended sweet spot, and performs for each reference point an inverse ray tracing starting at each reference point through selected pixels of the image matrix and through the imaging means to the illumination matrix, in order to determine address information of the illumination elements which are to be activated by the control unit to emit light for generating the defined sweet spot together with the imaging means.