Patent ID: 8581884
Filing Date: 2013-11-12
Classification: G06F

Abstract:
1. A touch sensing apparatus, comprising: a light transmissive element having a touch surface and a second surface opposite to the touch surface; a set of emitters arranged around a periphery of the touch surface to emit beams of light into the light transmissive element, wherein the beams of light propagate inside the light transmissive element while illuminating the touch surface such that an interaction between an object touching the touch surface and the touch surface causes an attenuation of the propagating light, wherein each beam of light diverges in a plane of the touch surface as the beam propagates through the light transmissive element; a set of light detectors arranged around the periphery of the touch surface to receive light from the set of emitters on a plurality of light paths, wherein each light detector is arranged to receive light from more than one emitter; and a processing element configured to, determine, based on output signals of the light detectors, a light energy value for each light path, generate a transmission value for each light path through the light transmissive element based on the light energy value, and operate an algorithm for transmission tomography on at least part of the thus-generated transmission values so as to determine a position of the object on the touch surface; wherein the algorithm for transmission tomography generates a two-dimensional model of the interaction between the object touching the touch surface and the touch surface from the at least part of the thus-generated transmission values for light paths through the light transmissive element.