Patent ID: 8368381
Filing Date: 2013-02-05
Classification: G06F

Abstract:
1. A method for measuring the movement of an optical pointing device on a work surface, said optical pointing device comprising a light source controlled by a motion detection processing circuit in order to illuminate a portion of the work surface, a photo-detector array including a plurality of rows and columns of pixels respectively aligned along first and second axes to pick-up reflected light on the work surface, a window comparator array for receiving input pixel voltages from the photo-detector array and to provide comparison signals to the motion detection processing circuit for calculation of the movement of said optical pointing device on the work surface, said method comprising the steps of: a) detecting by means of said photo-detector array a first light intensity pattern of said illuminated portion of the work surface following a first flash from the light source, b) comparing light intensity between neighbouring pixels of said photo-detector array on the basis of input pixel voltages, provided to the window comparator array, and determining along each of said first and second axes, first edge direction data from said detected first light intensity pattern, which edge direction data is descriptive of light intensity differences between said neighbouring pixels, said edge direction data being defined as: c) storing said first extracted edge direction data therefrom, d) detecting a second light intensity pattern of said illuminated portion of the work surface following a second flash from the light source, e) comparing light intensity between neighbouring pixels of said photo-detector array on the basis of input pixel voltages, and determining along each of said first and second axes, second edge direction data from said detected second light intensity pattern, f) determining a measurement of the relative motion between said optical pointing device and said illuminated portion of the work surface in part based on a comparison of said first and second edge direction data determined at steps b) and e).