Patent ID: 6434274
Filing Date: 2002-08-13
Classification: G02B,H04N

Abstract:
A focusing system of a scanner, comprising:an imaging lens; a line image sensor having a plurality of pixels arranged in a line for capturing a one-dimensional image, said one-dimensional image being a part of an image formed by said imaging lens; a lens drive system that drives said imaging lens with respect to said image sensor within a predetermined movable range; a contrast data detecting system that detects a contrast data representing brightness gradient with respect to a pixel located in a predetermined area on said line image sensor; a lens position detecting system that controls said lens drive system to sequentially change a position of said imaging lens within said predetermined movable range and controls said contrast data detecting system to repeatedly detects contrast data at each position of said imaging lens, said lens position detecting system detects a pixel with respect to which the brightness gradient is greatest and a lens position when said brightness gradient of said pixel is greatest; and a controller that controls said lens drive system to locate said imaging lens at said position detected by said lens position detecting system.