Patent ID: 8581852

Claim:
A touch detection system comprising: a light guiding sheet having a touch surface and a rear surface; a source arranged to couple light into an edge of the light guiding sheet, such that the light is totally internally reflected within a working area of the light guiding sheet; a reflective layer in proximity to the rear surface of the light guiding sheet; a display surface in proximity to the reflective layer; a detector arranged in front of the touch surface of the light guiding sheet and opposite to the reflective layer, to detect light emitted by the source, scattered as a result of a touch event and reflected by the reflective layer; and a computing-based device comprising: a processor; an interface to the display surface; an interface to the detector; and a memory arranged to store executable instructions to cause the processor to: perform image analysis on a signal from the detector to identify a touch event, the image analysis comprising; generating an area of interest inside the working area of the light guide sheet; filtering the signal to remove all data outside the area of interest; and converting the signal into a binary image using a threshold.