Reading apparatus

A reading apparatus comprising:

• a unit including an image sensor for reading a document;
• and
• an auto document feeder configured to be openable and closable around a hinge with respect to the unit,
• wherein the auto document feeder includes:
• a roller configured to move the document relative to the image sensor;
• a motor;
• a gear train configured to transmit a rotation of a rotational shaft of the motor to the roller;
• and
• an encoder unit configured to detect a rotation information of the motor, and including a sensor and a code wheel,
• wherein an orientation of the rotational shaft is parallel to a rotational axis of the hinge, and the gear train is arrayed in a direction of an extension of the rotational shaft, and
• wherein a gear that is a part of the gear train is attached to one end of the rotational shaft, and the code wheel is attached to the other end of the rotational shaft.