Optical image scanner with adjustable focus

摘要

A scanner has an optical head that includes lenses and a photosensor array. The distance of the optical head, relative to a surface of a platen, is variable. As a result, the primary focal point for the lenses can be moved relative to a surface of the platen. The primary focal point can be continuously variable, or the primary focal point can be selected from one of multiple alternative primary focal points.