Patent ID: 8519980

Claim:
A computer implemented method of determining one or more contact areas within a touch sensing region comprising the steps of: positioning a light source such that light emanating from said light source passes across said touch sensing region; positioning a plurality of light detectors such that at least a portion of said light source is within the field of view of each of said plurality of light detectors; providing a processor configured to identify one or more positive fans, each of said positive fans corresponding to an angular sector of the field of view of one of said light detectors in which the view of the light source is occluded; said processor configured to identify one or more negative fans, each of said negative fans corresponding to an angular sector of the field of view of one of said light detectors in which the view of the light source is not occluded; said processor configured to additively combine said positive fans with one another to determine positive regions; and said processor configured to subtractively combine said negative fans with said positive regions to determine said contact areas.