Patent ID: 8803845

Claim:
A method of establishing a reference in an optical touch input system, the method comprising: emitting light by an emitter located at a first corner of a display panel and receiving direct light by a detector located at a second corner of the display panel; the detector at the second corner detecting a first impulse signal generated by the direct light of the emitter located at the first corner, the first impulse signal corresponding to a pixel position of the detector located at the second corner; correlating the pixel position of the first impulse signal with a predetermined first reference angle of the display panel; emitting light by an emitter located at the second corner of the display panel and receiving direct light by the detector located at the first corner of the display panel; the detector at the first corner detecting a second impulse signal generated by the direct light of the emitter located at the second corner, the second impulse signal corresponding to a pixel position of the detector located at the first corner; and correlating the pixel position of the second impulse signal with the predetermined second reference angle of the display panel, wherein at least one of the predetermined first and second reference angles is 0 degree or 90 degrees, and the at least one of the predetermined first and second reference angles corresponds to one end of a region of interest of the display panel.