Image forming apparatus with condensation control

An image forming apparatus comprising:

• a photosensitive drum configured to bear a toner image on the photosensitive drum;
• a charging roller configured to charge a surface of the photosensitive drum;
• an intermediate transfer belt configured to be movable, wherein the intermediate transfer belt forms a first transfer portion in contact with the photosensitive drum;
• a development unit including a development roller in contact with the photosensitive drum and configured to develop an electrostatic latent image formed on the photosensitive drum using toner, wherein the toner image borne on the photosensitive drum is transferred onto the intermediate transfer belt at a position where the first transfer portion is formed, and toner from the toner image remaining on the photosensitive drum after passing through the position is collected by the development unit;
• a secondary transfer roller configured to transfer the toner image on the intermediate transfer belt onto a recording material at a second transfer portion;
• a collection unit disposed downstream of the second transfer portion and upstream of the first transfer portion in a movement direction of the intermediate transfer belt, wherein the collection unit includes a cleaning blade in contact with the intermediate transfer belt and is configured to collect toner remaining on the intermediate transfer belt adjacent to the cleaning blade;
• a detector configured to detect a first environment inside the image forming apparatus and a second environment around a location at which the image forming apparatus is set up;
• a transfer power source configured to apply a transfer voltage to the intermediate transfer belt at the first transfer portion;
• and
• a controller configured to control the transfer power source,
• wherein the controller controls to perform a first operation to form the toner image onto the recording material at the second transfer portion in a state of driving of the intermediate transfer belt in such a manner that the intermediate transfer belt moves at a second surface speed which is faster than a first surface speed, while driving the photosensitive drum in such a manner that the photosensitive drum rotates at the first surface speed, and to perform a second operation to rotate the intermediate transfer belt and the photosensitive drum in contact with each other, the second operation being different from the first operation,
• wherein, based on the first environment and the second environment of detection by the detector, the controller controls to perform predetermined control to move the development roller to separate the development roller from the photosensitive drum and drive the intermediate transfer belt in such a manner that the intermediate transfer belt moves at the second surface speed while driving the photosensitive drum in such a manner that the photosensitive drum rotates at the first surface speed in a state where the photosensitive drum is in contact with the intermediate transfer belt, and
• wherein the controller controls a potential difference between a surface potential of the photosensitive drum and the transfer voltage in the second operation to be smaller than a potential difference between the surface potential of the photosensitive drum and the transfer voltage in the first operation at the first transfer portion.