Patent ID: 6034784
Filing Date: 2000-03-07
Classification: H04N

Abstract:
An auto-start and anti-skew system for a sheet-fed scanner including a light source, a feed roller, a linear image sensor and transparent glass disposed over the linear image sensor, the system comprising:means for detecting an approximate width and a centering of the document placed at an input side of the sheet-fed scanner;means for activating an illumination of the light source and activating an acquisition of information from the linear image sensor as soon as a document is placed in the input side of the sheet-fed scanner, to provide continuous upcoming pixel information;means for classifying the continuous upcoming pixel information as roller pixels and non-roller pixels based on a contrast between a reflectance of the feed roller and a reflectance of the document, an acceptably aligned document edge engaged between a non-rotating feed roller and the transparent glass being identified by a predetermined number of non-roller is pixels;means for maintaining a precise predetermined parallel offset distance between a focus-line of the linear image sensor and an input line of contact where the feed roller contacts the transparent glass; andmeans for controlling a rotation of the feed roller, the controlling means activating a rotation of the feed roller to seize the document from the input side of the feed roller and pull the document, without inducing an unacceptable skew, over the transparent glass as soon as the approximate width and the centering of the document are detected and the predetermined number of non-roller pixels are acquired.