Patent ID: 7703766

Claim:
A method for sensing a paper skew adapted for a device having a paper feeding mechanism, wherein the device has a feed sensor which is fixed at a start position of paper feeding; and, a position sensor which moves in a direction perpendicular to a direction of paper feeding and passes through a first position and a second position, wherein the first position is the intersection of a moving path of the position sensor and a line, wherein the feed sensor is on the line, and the line is parallel to the direction of paper feeding, the method for sensing the paper skew comprising: the device having a first distance which is a moving distance of a measure paper fed, starting when the measure paper is sensed by the feed sensor and ending when the measure paper is sensed by the position sensor at the first position; moving the position sensor to the second position; feeding a work paper into the device; obtaining a second distance which is a moving distance of the work paper fed, starting when the work paper is sensed by the feed sensor and ending when the work paper is sensed by the position sensor at the second position; and determining whether the work paper is skewed or not according to the difference between the first distance and the second distance, the work paper being not skewed if the difference is zero, and the work paper being skewed if the difference is not zero.