TOUCH SURFACE WITH TWO-DIMENSIONAL COMPENSATION

摘要

An apparatus for determining an interaction (A1) between an object (3) and a touch surface (4)of a panel (2). An illumination arrangement (12x, 12y) introduces light (L) into the panel (2) for propagation by internal reflection between the touch surface (4) and an opposite surface (5) and towards a receiving light detection arrangement. A processor unit (26) is configured to iteratively i) determine, based on the received light (L), a current light status (Ci) representing a two-dimensional distribution of light in the panel (2), ii) determine the interaction (A1) with the object (3) as a function of the current light status (Ci) and a previously updated background status (Bk-1) representing a two-dimensional distribution of light in the panel (2) caused by contaminations, and iii) update the background status (Bk-1) as a function of the interaction (A1). A method and computer readable medium are also described.