Patent ID: 7688477

Claim:
An image reading apparatus that reads an image in a first scanning direction and in a second scanning direction perpendicular to the first scanning direction, the image reading apparatus comprising: a document table that has a placing surface on which a document is placed; a first positioning member that is provided on the document table to extend in the first scanning direction and determines a position in the second scanning direction of an edge of the document placed on the placing surface; a light receiving unit that is provided to face one surface of the document placed on the placing surface, and receives reflected light of light emitted to the placing surface; a first reference area holding member that extends from the first positioning member over the placing surface and holds, on its surface opposing the placing surface, two reference areas extending parallel to the first scanning direction and including a first reference area and a second reference area each having a different pattern from each other; a border position detecting unit that detects a border position in the first scanning direction between at least one of the first and second reference areas and the document placed on the placing surface, based on a light quantity of the reflected light received by the light receiving unit; and a size determining unit that calculates a document length in the first scanning direction based on the border position detected by the border position detecting unit.