Image forming apparatus

1. An image forming apparatus, comprising:

a transportation member rotating to transport a medium or developer;

a blade member disposed, to abut against the transportation member for removing an object adhering to a surface of the transportation member;

a retaining member disposed on an upstream side of the blade member in a direction that the transportation member rotates and abutting against the transportation member for retaining the object adhering to the surface of the transportation member; and

an image forming unit for forming a developer image on the transportation member so that the developer is supplied to the retaining member when a printing operation is not performed.

2. The image forming apparatus according to claim 1 , wherein said retaining member extends in a direction perpendicular to the direction that the transportation member rotates.

3. The image forming apparatus according to claim 1 , wherein said image forming unit is arranged to form the developer image on the transportation member so that the developer image has a length in a direction perpendicular to the direction that the transportation member rotates smaller than a width of the transportation member and larger than a width of the medium.

4. The image forming apparatus according to claim 1 , wherein said retaining member has a length in a direction perpendicular to the direction that the transportation member rotates larger than a length of the developer image in the direction.

5. The image forming apparatus according to claim 1 , wherein said image forming unit is arranged to form the developer image when the image forming apparatus is turned on or after the image forming apparatus prints on a specific number of sheets.

6. The image forming apparatus according to claim 1 , wherein said retaining member is disposed at a position corresponding to a side edge of the medium in a direction perpendicular to the direction that the transportation member rotates.

7. The image forming apparatus according to claim 1 , wherein said retaining member is disposed at least two positions corresponding to side edges of the medium in a direction perpendicular to the direction that the transportation member rotates.

8. The image forming apparatus according to claim 1 , wherein said image forming unit is arranged to form a test pattern for operational correction on the transportation member when a printing operation is not performed.

9. The image forming apparatus according to claim 1 , wherein said image forming unit is arranged to form a test pattern for color shift correction on the transportation member when a printing operation is not performed.

10. The image forming apparatus according to claim 8 , wherein said retaining member has a length in a direction perpendicular to the direction that the transportation member rotates covering the test pattern and a side edge of the medium adjacent to the test pattern.

11. The image forming apparatus according to claim 1 , further comprising a moving unit for moving the retaining member toward a position corresponding to a side edge of the medium in a direction perpendicular to the direction that the transportation member rotates.

12. The image forming apparatus according to claim 8 , further comprising a moving unit for moving the retaining member between a position corresponding to the test pattern and a position corresponding to a side edge of the medium in a direction perpendicular to the direction that the transportation member rotates.

13. The image forming apparatus according to claim 1 , wherein said transportation member includes a medium transportation belt unit.

14. The image forming apparatus according to claim 1 , wherein said retaining member is formed of a urethane foam.