Patent ID: 7292232
Filing Date: 2007-11-06
Classification: G06F

Abstract:
1. A data input device for use with a tracking surface, said tracking surface having light-scattering properties, said device comprising: a substantially coherent light source for projecting a substantially coherent light beam onto said tracking surface during operation, said tracking surface scattering the substantially coherent light beam striking said tracking surface; an optic for guiding the projected substantially coherent light beam toward the tracking surface, said tracking surface scattering the substantially coherent light beam when the substantially coherent light beam strikes the tracking surface, said optic comprising, a first boundary facing said substantially coherent light source, and a second boundary opposite the first boundary and configured to face said tracking surface; a detector associated with the substantially coherent light source for detecting at least a portion of the substantially coherent light beam scattered by the tracking surface, said detected portion comprising a speckle pattern; said optic being arranged between the detector and the tracking surface during operation such that the tracking surface is spaced from the second boundary by a distance sufficient to inhibit any substantial retro-reflection of the substantially coherent light beam striking the second boundary from striking the detector; and a controller responsive to the detector for operating the device in a tracking mode by utilizing the detected speckle pattern to track relative movement between the device and the tracking surface.