Patent ID: 8366100

Claim:
A discharge tray apparatus wherein a plurality of sheets of recording paper that have been successively transported at a fixed speed and a fixed interval, released and discharged in approximately the horizontal direction from a discharge opening, and have landed on a discharge tray from the leading edge to the trailing edge, are received and placed onto the discharge tray, the discharge tray apparatus comprising a discharge tray moving means that performs a tray shift operation that moves the discharge tray in a horizontal direction approximately perpendicular to the discharge direction, such that after a preceding paper successively transported earlier has been placed on the discharge tray, a succeeding paper succeedingly transported after the preceding paper is placed at a position different from the placement position of the preceding paper on the discharge tray, wherein the discharge tray moving means biases the discharge tray with a biasing member from a first side to a second side in the horizontal direction, approximately perpendicular to the discharge direction, performs a first tray shift operation that causes the discharge tray to move in a first direction from the second side toward the first side in the horizontal direction by rotating an eccentric cam having an outer surface that is in contact with the discharge tray a half turn at a fixed speed, and performs a second tray shift operation that causes the discharge tray to move in a second direction that is opposite to the first direction by rotating the eccentric cam in the same direction a further half turn at a fixed speed, and wherein the outer shape of the eccentric cam is such that during the first half turn of the eccentric cam, during the first ⅙ turn, the cam diameter increment, which is the increment of the distance from the rotational axis of the eccentric cam until arriving at a point on the outer circumference of the eccentric cam whenever advancing a unit rotation angle of the eccentric cam, increases, and during the next ⅙ turn, the cam diameter increment whenever advancing the unit rotation angle is fixed, and further, during the next ⅙ turn, the cam diameter increment whenever advancing the unit rotation angle decreases, and in the remaining half turn of the eccentric cam, during the first ⅙ turn, the cam diameter decrement, which is the decrement of the distance from the rotational axis of the eccentric cam until arriving at a point on the outer circumference of the eccentric cam whenever advancing a unit rotation angle of the eccentric cam, increases, and during the next ⅙ turn, the cam diameter decrement whenever advancing the unit rotation angle is fixed, and further, during the next ⅙ turn, the cam diameter decrement whenever advancing the unit rotation angle decreases.