Medium ejection device and image forming apparatus

1. A medium ejection device comprising:

an ejection member configured to eject a medium toward a medium ejection direction;

a stacking member configured to stack the medium ejected from the ejection member; and

a rib disposed in a substantially up and down direction configured to be contacted by a tailing end of the medium ejected from the ejection member, the rib including at an upper portion thereof a convex portion protruding toward the stacking member and a lower portion defining a peripheral surface, wherein the convex portion protrudes away from the rib such that a plane which is parallel to the peripheral surface and passes through an outermost end of the convex portion, is spaced from the peripheral surface.

2. The medium ejection device according to claim 1 , wherein the ejection member comprises:

an ejection roller configured to convey the medium in the medium ejection direction; and

a driven roller configured to sandwich and convey the medium with the ejection roller.

3. The medium ejection device according to claim 2 , wherein the rib is disposed to a wall disposed in such a manner to stand toward the driven roller from directly below a vicinity of a pair of ejection rollers having the ejection roller and the driven roller.

4. The medium ejection device according to claim 3 , wherein the rib is disposed to the wall in such a manner to protrude across the substantially up and down direction and toward a direction perpendicular to the medium ejection direction.

5. The medium ejection device according to claim 1 , wherein the rib is disposed in such a manner to extend toward the ejection member from the stacking member.

6. The medium ejection device according to claim 1 , wherein an upper surface of the convex portion is inclined to the medium ejection direction.

7. A medium ejection device comprising:

an ejection member configured to eject a medium toward a medium ejection direction;

a stacking member configured to stack the medium ejected from the ejection member; and

a rib disposed in a substantially up and down direction configured to be contacted by a tailing end of the medium ejected from the ejection member, the rib including at an upper portion thereof a convex portion protruding toward the stacking member, wherein a distance protruded by the convex portion of the rib increases as toward a middle portion of the ejection member in a direction perpendicular to the medium ejection direction.

8. The medium ejection device according to claim 3 , wherein the outermost end of the convex portion is positioned at an upstream side in the medium ejection direction relative to a tangent line provided at a downmost stream of the driven roller in the medium ejection direction.

9. The medium ejection device according to claim 1 , wherein the convex portion includes a gradient area inclined with respect to a side of the ejection member.

10. The medium ejection device according to claim 9 , wherein the gradient area is inclined substantially between 45 degrees to 80 degrees with respect to a horizontal direction.

11. The medium ejection device according to claim 10 , wherein the gradient area is preferably inclined at substantially 72 degrees with respect to the horizontal direction.

12. A medium ejection device comprising:

an ejection member configured to eject a medium toward a medium ejection direction;

a stacking member configured to stack the medium ejected from the ejection member; and

a rib disposed in a substantially up and down direction configured to be contacted by a tailing end of the medium ejected from the ejection member, the rib including at an upper portion thereof a convex portion protruding toward the stacking member, wherein the rib comprises a plurality of ribs, each convex portion of the plurality of ribs having an uneven distance protruded toward the medium ejection direction.

13. The medium ejection device according to claim 12 , wherein the distance protruded by the convex portion of each of the plurality of ribs increases toward a middle portion in a direction perpendicular to the medium ejection direction.

14. An image forming apparatus comprising the ejection medium device according to claim 1 .