Patent ID: 7113619

Claim:
An image reading method which reads an image on an image recording medium by a visible light, comprising the steps of: scanning an invisible light in a first direction using an optical path of the visible light and simultaneously reading the invisible light one-dimensionally in a second direction which is perpendicular to the first direction after a focusing position of the invisible light is set on a position of an optical element disposed in the optical path of the visible light, the focusing position being different from a position of the image recording medium; determining from the read invisible light whether light quantity data of the one-dimensionally read invisible light contains a portion where the light quantity data changes at a reading position during the one-dimensional reading; and detecting at least one of a foreign matter and a scratch on the optical element based on a result of the determining operation; scanning an invisible light on the recording medium and reading the scanned invisible light; and detecting, by the invisible light, the at least one of the foreign matter and the scratch on the recording medium, wherein focusing positions of the invisible light are different from one another between the time when at least one of the foreign matter and the scratch on the optical element disposed in the optical path is detected by the invisible light and the time when at least one of the foreign matter and the scratch on the image recording medium is detected by the invisible light.