Patent ID: 8531436

Claim:
A specific wavelength selecting method for an optical input device, comprising: placing one end of the optical input device on a working surface; providing at least two light sources disposed within the optical input device, for emitting light rays having different wavelength regions respectively; emitting the at least two light rays having different wavelength regions to the working surface to obtain at least two reflected light rays respectively; detecting and comparing optical signals of the at least two reflected light rays, so as to obtain a preferred optical result, by: detecting a first of said at least two light rays to determine a first distance D 1 between the working surface and a first of the two light sources, and detecting a second of said at least two light rays to determine a second distance D 2 between the working surface and a second of the two light sources to the working surface, said preferred optical result being a distance change, wherein said distance change is a difference between said first distance D 1 from said first of the two light sources to the working surface and said second distance D 2 from said second of the two light sources to the working surface, said distance change (D 2 -D 1 ) being caused by at least one of a changing angle and a vertical movement of the optical input device or light sources relative to the working surface; and selecting one of the at least two light sources to be enabled to continuously emit according to the preferred optical result.