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Fingertip detection for camera based multi-touch systems

  • US 8,581,852 B2
  • Filed: 11/15/2007
  • Issued: 11/12/2013
  • Est. Priority Date: 11/15/2007
  • Status: Active Grant
First Claim
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1. 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.

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