Image reader and document curvature measurement using visible and infrared light

摘要

This invention relates to an image reader capable of reading document images in parallel with the measurement of the state of curvature of the document surface, and correcting image distortion caused by said curvature in real time. An illumination light source for reading documents is provided with a filter to separate infrared light and visible light. The visible light is used to read document image information, and the infrared light is used to measure the state of curvature of the document. Since document reading and document curvature measurement are accomplished using light having different characteristics, these operations can be accomplished simultaneously.