Image reading apparatus

An image reading apparatus comprising:

• a housing having a rectangular aperture on its top face;
• a flat plate shaped original table made of a transparent material and fitted to the aperture of the housing;
• a scan unit provided in an inside of the housing and moved in a first direction with facing an inner face of the original table;
• an illumination means provided on the scan unit and illuminating a predetermined area in each of the first direction and a second direction perpendicular to the first direction;
• an imaging means provided on the scan unit and imaging an image in the predetermined area illuminated by the illumination means;
• an original positioning means provided on the top face of the housing and having two sides respectively substantially parallel to the first direction and the second direction, an intersection point of the two sides serving as a reference point for starting image reading by the imaging means;
• an original cover rotatably pivoted by hinges on the top face of the housing, and covering at least the original table and the original positioning member;
• a flexible sheet attached to an inner face of the original cover via an elastic member, and substantially isometric with the original table so that the flexible sheet is tightly contact to the original table when the original cover is closed;
• and
• an original holding mechanism provided in the original cover for facing a thrust position spaced by predetermined distances from a reference position of the original positioning member in a main scanning direction and in a sub-scanning direction perpendicular to the main scanning direction when the original cover is closed,
• the original holding mechanism having a thrust pin slidably guided between a first position where a front end thereof is protruded from the inner face of the original cover and a second position where the front end thereof is positioned substantially the same level of elevation as the flexible sheet;
• the front end of the thrust pin is protruded from the inner face of the original cover by a pressing force of a spring or own weight of the thrust pin so that it has been contacting to a rear face of the original by protruding from an inner face of the original cover while the original cover is gradually lifted up from a closed state and rotated around the hinges, thereby capable of preventing floating of the original from the original table due to wind pressure when the original cover is opened.