Image forming apparatus

An image forming apparatus comprising:

• a plurality of image forming portions that include image carrying members and developing devices feeding toner to the image carrying members, the plurality of image forming portions forming images of different colors;
• an intermediate transfer belt that is an endless belt, the intermediate transfer belt moving along the image forming portions, the intermediate transfer belt having an elastic layer;
• a plurality of primary transfer members that are arranged opposite the image carrying members across the intermediate transfer belt, the plurality of primary transfer members primarily transferring toner images formed on the image carrying members to the intermediate transfer belt;
• a contact-separation mechanism that moves the primary transfer members in a direction approaching the intermediate transfer belt to put the intermediate transfer belt into pressed contact with the image carrying members, the contact-separation mechanism moving the primary transfer members in a direction away from the intermediate transfer belt to move the intermediate transfer belt away from the image carrying members;
• a secondary transfer member that makes contact with the intermediate transfer belt to secondarily transfer the toner images primarily transferred on the intermediate transfer belt to a recording medium;
• a driving device that drives the image carrying members and the intermediate transfer belt to rotate individually;
• a voltage applying device that applies a voltage to the primary transfer members and the secondary transfer member;
• and
• a control portion that controls the image forming portions, the contact-separation mechanism, the voltage applying device, and the driving device,
• wherein
• the contact-separation mechanism is switchable between
• an all-color pressure state where the primary transfer members are all in pressed contact with the image carrying members via the intermediate transfer belt, and
• an all-color apart state where the primary transfer members are all away from the intermediate transfer belt, and
• the control portion can execute, at first power-on, a reduced friction coefficient mode in which the control portion starts to drive the image carrying members and the intermediate transfer belt in the all-color apart state, then transits to the all-color pressure state, and then ejects toner from the developing device to the image carrying members to reduce a surface friction coefficient on the image carrying members and the intermediate transfer belt.