Image reading apparatus for determining a setback distance after reading interruption

An image reading apparatus comprising:

• a driving source that generates a driving force;
• a conveying mechanism that transmits the driving force generated by the driving source to a conveyed object so as to convey the conveyed object along a predetermined conveyance path to read image information from a read object;
• a reading control unit including:
• a constant velocity moving control portion that controls a moving velocity of the conveyed object through the conveying mechanism to move the conveyed object at a constant velocity in a conveying direction along the conveyance path, and
• a writing portion that writes, into a memory area, image data of each line on the read object generated by reading the image information when the conveyed object passes a corresponding position on the conveyance path corresponding to a reading start position on the read object where reading of the image information should be started;
• an acceleration distance measuring unit that measures an acceleration distance from a moving start position of the conveyed object to a position where the conveyed object has been shifted to the constant-velocity moving state;
• an interruption determination unit that determines whether or not to interrupt operation of the reading control unit;
• a stop control unit that, when it is determined to interrupt the operation of the reading control unit, stops the operation of the reading control unit, and decelerates the conveyed object through the conveying mechanism until the conveyed object stops moving in the conveyance direction;
• a deceleration distance measuring unit that measures a deceleration distance from a position of the conveyed object when the operation of the reading control unit has been stopped to a position where move of the conveyed object in the conveyance direction has been stopped;
• a setback control unit that moves the conveyed object, which has stopped moving in the conveyance direction, in a direction opposite to the conveyance direction through the conveying mechanism;
• and
• a setback distance setting unit that sets a setback distance to move the conveyed object by the setback control unit based on the acceleration distance measured by the acceleration distance measuring unit and the deceleration distance measured by the deceleration distance measuring unit, wherein
• a first determination velocity is set higher than a target velocity at constant-velocity control by the reading control unit,
• a second determination velocity is set lower than the target velocity,
• the acceleration distance measuring unit outputs, as a measurement result, a distance starting from the moving start position to a position where an event that a velocity of the conveyed object is converged into a range between the first determination velocity and the second determination velocity from outside the range has lastly occurred in a predetermined period of time after start of moving of the conveyed object.