Patent ID: 6420723
Filing Date: 2002-07-16
Classification: H04N

Abstract:
A method of determining the position of an object relative to a surface, said method comprising:providing a two-dimensional photosensor array associated with said object; directing light from a first focal plane portion of said surface to said two-dimensional photosensor array for a period; directing light from a second focal plane portion of said surface to said two-dimensional photosensor array during a period when light is not being directed from said first focal plane portion of said surface to said two-dimensional photosensor array; generating image data with said two-dimensional photosensor array representative of an image received by said two-dimensional photosensor array; causing relative movement between said surface and said two-dimensional photosensor array; and performing an analysis of said image data to determine the displacement of said two-dimensional photosensor array relative to said surface.