Patent ID: 8218204

Claim:
An image reading apparatus for optically reading a document, comprising: a carriage including a first end portion and a second end portion facing each other in a main scanning direction of the document and accommodating an optical unit for image reading, a driving member mounted on a plurality of pulleys for moving the carriage in a sub scanning direction orthogonal to the main scanning direction of the document; a guide rail extending in the sub scanning direction; a guide-rail engaging portion provided on the first end portion of the carriage and engaged with the guide rail; a holding portion provided on the first end portion of the carriage for holding the driving member; a guide plate for supporting the carriage by being held in sliding contact with the lower surface of the second end portion of the carriage and guiding a movement of the carriage in the sub scanning direction; and a claw portion for pressing the guide-rail engaging portion against the guide rail by partially deforming the driving member to produce a tensile force in the driving member and causing the tensile force to act on the first end portion of the carriage, and producing such a rotation moment for biasing the first end portion of the carriage in a first direction parallel with the sub scanning direction and, on the other hand, biasing the second end portion of the carriage in a second direction opposite to the first direction and parallel with the sub scanning direction.