DISPLACEMENT DIAGNOSING METHOD APPLIED TO AN IMAGE READ-OUT APPARATUS

A scanner unit as an image read-out apparatus has a document glass on which a document is placed, an exposure lamp for illuminating the document with light, a CCD line sensor for receiving reflected flight from the document and converting the light to electric signal, first to third mirrors for conducing the reflected light from the document to the CCD sensor and a light condensing lens for allowing the reflected light which is conducted through the first to the third mirrors to condense on the CCD line sensor. In a position away from a document effective area at which the document is set on a document glass a chart is printed or attached to allow diagnosis to be made for the “displacements” of scanner unit's respective constituent elements, that is, optical members such as the exposure lamp, first to third mirrors, lens and CCD line sensor.