Primary transfer device and image forming apparatus having the same

A primary transfer device comprising:

• a primary transfer roll that is capable of being engaged with and disengaged from an intermediate transfer member to which a developer image formed on an image holding member is primarily transferred;
• and
• a setting-changing unit that changes a setting of pressure of the primary transfer roll to the intermediate transfer member in accordance with kind of a recording medium to which the developer image primarily transferred to the intermediate transfer member is secondarily transferred,
• wherein
• the setting-changing unit an irregular medium transfer mode for a case where the recording medium to which the developer image is a recording medium having irregularities formed on a surface thereof, and an ordinary transfer mode for a case where the recording medium is a recording medium other than the recording medium having the irregularities,
• a pressure set in the irregular medium transfer mode is smaller than that set in the ordinary transfer mode,
• the intermediate transfer member is an endless belt,
• the primary transfer device further comprises a movable tightening roll that tightens the belt-shaped intermediate transfer member in the vicinity of the primary transfer roll,
• the primary transfer roll is supported at both ends in an axial direction of the primary transfer roll by elastic members that apply the pressure to the primary transfer roll, and
• the primary transfer roll and the movable tightening roll are configured to be moved in cooperation with a common driving member that moves in a given direction.