Patent ID: 7265748
Filing Date: 2007-09-04
Classification: G06F

Abstract:
1. A method for determining a location of an object substantially touching a touch pad, the touch pad having a plurality of surrounding edges, said method comprising: providing a light sheet comprising a plurality of light beams oriented to propagate in an air space over the touch pad such that the light sheet is partially blocked by the object when the object intrudes into the air space, wherein light intensity of the light sheet is spatially varying in such a manner that the light intensity of the partially blocked light sheet is dependent upon the location of the touching object, and wherein the light beams are provided by a first light providing structure disposed adjacent to a first surrounding edge and a second light providing structure disposed adjacent to a second surrounding edge opposite to the first surrounding edge, and wherein each of the first and second light providing structures has a longitudinal axis and further comprises a light source for providing a source beam along the longitudinal axis, and a plurality of partially reflecting surfaces distributed along the longitudinal axis to partially reflect the source beam for providing the light beams in the light sheet such that light intensity of the light beams varies along the longitudinal axis; disposing a first light detecting structure behind the second light providing structure for measuring the light intensity of the light beams provided by the first light providing structure, wherein the measured light intensity is reduced when the light sheet is partially blocked by the object; disposing a second light detecting structure behind the first light providing structure for further measuring the light intensity of the light beams provided by the second light providing structure, wherein the further measured light intensity is reduced when the light sheet is partially blocked by the object; and calculating the location of the object based on the measured reduced intensity and the further measured reduced intensity.