Image forming apparatus

1. An image forming apparatus comprising:

a first unit including a first feeding member for feeding a medium;

a second unit including a second feeding member for feeding the medium; and

a medium feeding path provided between the first unit and the second unit,

wherein the second unit is movable between a closing position where the medium feeding path is formed between the first unit and the second unit and an opening position where the second unit separates from the first unit so as to open the medium feeding path;

wherein the first feeding member has a first gear;

wherein the second feeding member has a second gear that meshes with the first gear when the second unit is in the closing position;

wherein the image forming apparatus further comprises a shift mechanism; and

wherein when the second unit moves to the closing position, the shift mechanism holds one of the first gear and the second gear at a retracted position where the first gear and the second gear do not mesh with each other.

2. The image forming apparatus according to claim 1 , further comprising a rotation locking mechanism that locks the second unit at least at the closing position.

3. The image forming apparatus according to claim 2 , wherein in conjunction with an operation of the rotation locking mechanism to lock the second unit at the closing position, the shift mechanism moves the one of the first gear and the second gear from the retracted position to a meshing position where the first gear and the second gear mesh with each other.

4. The image forming apparatus according to claim 2 , wherein in conjunction with an operation of the rotation locking mechanism to release locking of the second unit at the closing position, the shift mechanism moves the one of the first gear and the second gear to the retracted position.

5. The image forming apparatus according to claim 1 , wherein the shift mechanism moves the one of the first gear and the second gear in a direction of a rotation axis of the one of the first gear and the second gear.

6. The image forming apparatus according to claim 5 , further comprising:

a gear holding portion that holds the one of the first gear and the second gear so as to be movable in the direction of the rotation axis, and

a biasing unit that biases the one of the first gear and the second gear to a position where the first gear and the second gear mesh with each other.

7. The image forming apparatus according to claim 1 , further comprising a rotation locking mechanism that locks the second unit at least at the closing position,

wherein the rotation locking mechanism includes a lever rotatably mounted to the second unit, and

wherein the lever engages an engaging portion of the first unit.

8. The image forming apparatus according to claim 7 , further comprising a shaft that extends along an axial direction of the one of the first gear and the second gear, the shaft rotating together with the lever of the rotation locking mechanism,

wherein the shift mechanism includes a cam member mounted to the shaft, the cam member being contactable with the one of the first gear and the second gear, the cam member having a cam surface ( 25 d , 75 d ), and

wherein when the shaft rotates, the cam surface ( 25 d , 75 d ) of the cam member pushes the one of the first gear and the second gear in the axial direction.

9. The image forming apparatus according to claim 8 , wherein the cam member includes a lock portion that locks the second unit at the closing position.

10. The image forming apparatus according to claim 9 , wherein when the rotation locking mechanism locks the second unit at the closing position, the lock portion also locks the second unit at the closing position.

11. The image forming apparatus according to claim 7 , wherein the lever includes:

a first portion that engages the engaging portion when the second unit is in the closing position;

a second portion that guides the engaging portion when the second unit moves between the closing position and the opening position; and

a third portion that engages the engaging portion when the second unit is in the opening position.

12. The image forming apparatus according to claim 7 , wherein the shaft is a carriage shaft configured to guide a carriage having a head unit.

13. The image forming apparatus according to claim 7 , wherein the lever functions as a stay that supports the second unit at the closing position.

14. The image forming apparatus according to claim 1 , further comprising a connecting member that connects the other of the first gear and the second gear with the first feeding member or the second feeding member so as to be movable in a direction where the first feeding member or the second feeding member mesh with each other.

15. The image forming apparatus according to claim 1 , wherein the second unit is provided above the first unit and is rotatably supported by the first unit.

16. The image forming apparatus according to claim 1 , wherein the first feeding member and the second feeding member respectively include rollers.