Optical touch sensing based on internal scattering in touch surface

While diffuse-illumination touch sensing has the advantage of being sensitive enough to detect an object over a touch surface, it has the drawback of being unable to distinguish touches from approaches reliably. As a solution to this problem, proposed is a novel optical sensing structure that exploits the phenomenon of internal scattering. A prototype touch surface realising the proposed concept confirmed that it is indeed effective for better touch classification while retaining proximal sensitivity.