Medium carrying device and image forming apparatus

1. A medium carrying device, comprising:

an apparatus body;

a medium guide unit that is detachable with respect to the apparatus body;

a carrying roller that is disposed in the apparatus body, and is configured to rotate to carry a print medium passing through the medium guide unit; and

a driven roller that is disposed in the medium guide unit at a position corresponding to the carrying roller in a contacting manner so that the driven roller rotates in accordance with a rotation of the carrying roller, wherein

the medium guide unit is slidably pulled out from the apparatus body,

the medium guide unit is movable between a pulled-out position at which the medium guide unit is held outside the apparatus body while being connected to the apparatus body, and a carryable position at which the medium guide unit is installed inside the apparatus body and carries the print medium,

the driven roller in the medium guide unit and the carrying roller in the apparatus body contact each other when the medium guide unit is at the carryable position, and

the contact between the driven roller and the carrying roller is released when the medium guide unit is at the pulled-out position.

2. The medium carrying device of claim 1 , wherein

the medium guide unit includes an opening through which the driven roller contacts the carrying roller.

3. The medium carrying device of claim 1 , wherein

the medium guide unit includes a bias member that provides a bias force pushing the driven roller toward the drive roller.

4. The medium carrying device of claim 1 , wherein

the medium guide unit includes

a first guide member that guides the print medium along a medium carrying route, and

a second guide member that is swingably attached to the first guide member.

5. The medium carrying device of claim 4 , wherein

the first guide member includes a first supporting part around which the second guide member swings, and

the second guide member includes a first supported part that is engaged with the first supporting part.

6. The medium carrying device of claim 4 , further comprising:

a unit lead part, wherein

the unit lead part is configured to create a gap between the first and second guide members when the medium guide unit is completely fit in the apparatus body, and

the unit lead part is configured to narrow the gap while the medium guide unit is being pulled out and being inserted into the apparatus body.

7. The medium carrying device of claim 1 , further comprising:

a medium detection part that is swingably attached to the medium guide unit at a medium carrying route along which the print medium passes so that the medium detection part is swung by the print medium passing through the carrying route, and the medium detection part detects the print medium in correspondence with the swing caused by the print medium, wherein

the medium detection part includes a contact surface that is inclined with respect to a direction in which the medium guide unit is pulled out from the apparatus body.

8. An image forming apparatus, comprising

the medium carrying device of claim 1 .

9. A medium carrying device, comprising:

an apparatus body;

a medium guide unit that is detachable with respect to the apparatus body and includes

a first guide member guiding a print medium, and

a second guide member swingably attached to the first guide member; and

a unit lead part that is configured to create a gap between the first and second guide members when the medium guide unit is fully fit in the apparatus body, and that is configured to narrow the gap, compared to a condition under the medium guide unit is fully fit in the apparatus body, while the medium guide unit is being pulled out and being inserted into the apparatus body.

10. The medium carrying device of claim 9 , wherein

the unit lead part includes a lead surface and a projection part,

the lead surface includes first and second lead parts that change the gap created between the first and second guide members, and

the projection part projects and is fit in the lead surface.

11. The medium carrying device of claim 10 , wherein

the lead surface creates the gap when the first lead part is in contact with the projection part, and

the lead surface narrows the gap when the second lead part is in contact with the projection part.

12. The medium carrying device of claim 10 , wherein

when the first lead part is in contact with the projection part, the lead surface holds the first guide member at a first position where the first and second guide members create the gap, and

when the second lead part is in contact with the projection part, the lead surface narrows the gap between the first and second guide members.

13. The medium carrying device of claim 12 , further comprising:

a carrying roller that carries the print medium passing through the medium guide unit, wherein

the first guide member includes an opening in which the carrying roller sits when the first guide member is positioned at the first position.

14. The medium carrying device of claim 13 , wherein

the carrying roller is positioned out of the opening when the first guide member is positioned at a second position.

15. The medium carrying device of claim 13 , wherein

the medium guide unit includes a flange that is configured to position the first guide member between the first and second positions,

the apparatus body includes a projection, and

the flange includes a valley part and a body part, by contacting the projection, the valley part holding the first guide member at the first position, and the body part holding the first guide member at the second position.

16. An image forming apparatus, comprising

the medium carrying device of claim 9 .

17. A medium carrying device, comprising:

an apparatus body having a side wall; and

a medium guide unit that guides a print medium in a medium carrying direction and that is pulled out through the side wall of the apparatus body, the medium guide unit including a first guide, a second guide, and a swing axis that extends in a direction perpendicular to the medium carrying direction and that connects the first guide and the second guide, wherein

the second guide is swingable about the swing axis with respect to the first guide,

the medium guide unit has a first end and a second end in the medium carrying direction, the first end being closer to the side wall of the apparatus body than is the second end when the medium guide unit is at a pulled-out position at which the medium guide unit is held outside the apparatus body while being connected to the apparatus body,

the swing axis is located in the vicinity of the first end.

18. The medium carrying device according to claim 17 , wherein

the first guide and the second guide each have a first side and a second side,

the first side is a side on which the swing axis is provided,

the second side is on the opposite side from the first side, and

the second side of the first guide projects further from the swing axis than the second side of the second guide.

19. The medium carrying device according to claim 17 , wherein

the first guide and the second guide each have a first side and a second side,

the first side is a side on which the swing axis is provided,

the second side is on the opposite side from the first side, and

the second side of the first guide is inclined in a direction towards the second guide.

20. The medium carrying device according to claim 17 , wherein

the first guide is longer in than the second guide along a longitudinal direction of the medium guide unit.

21. The medium carrying device according to claim 17 , wherein

the first guide includes an opening through which a driven roller contacts a carrying roller.

22. The medium carrying device according to claim 17 , wherein

the second guide includes a through hole located near a driven roller.

23. The medium carrying device according to claim 17 , wherein

the apparatus body includes a cover, and

the cover is opened to pull out the medium guide.

24. The medium carrying device according to claim 17 , wherein

the apparatus body includes a drive roller, and

the medium guide includes a driven roller.