Patent ID: 6950139

Claim:
An image reading device comprising: an infrared component separator that separates color components of an image light flux passing through a transmissive original into an infrared component; an infrared image-capturing device that outputs an infrared image signal by capturing the infrared component of the image light flux that has been separated by said infrared component separator; a visible component separator that separates the color components of the image light flux passing through the transmissive original into a visible component; a visible image-capturing device that outputs a visible image signal by capturing the visible component of the image light flux that has been separated by said visible component separator; an image forming optical system that forms the image of the light flux passing through the transmissive original at said infrared image-capturing device or at said visible image-capturing device; a focal adjustment device that adjusts a position of said image forming optical system relative to the transmissive original; means for image forming position decision-making that determines the position of said image forming optical system relative to the transmissive original as a visible image forming position at which the visible light component of the image light flux is formed at said visible image-capturing device, based upon said infrared image signal;, and a control device that implements control on said focal adjustment device based upon a decision made by said means for image forming position decision-making.