Patent ID: 8676069

Claim:
An image forming apparatus, comprising: a development unit that forms a toner image; an intermediate transfer belt which includes a circumferential surface to which the toner image formed by the development unit is transferred and which travels endlessly by being tightly stretched across a plurality of rollers; a transfer unit that transfers the toner image from the development unit to the intermediate transfer belt; a secondary transfer roller part for secondarily transferring, onto recording paper, the toner image that has been transferred to the circumferential surface of the intermediate transfer belt by the development unit; a second movement mechanism that moves the secondary transfer roller part in a direction of coming in contact with and separating from the intermediate transfer belt, and pressing the secondary transfer roller part against the intermediate transfer belt; a toner pattern concentration detection unit that detects a concentration of a toner pattern being a concentration detection toner image that has been transferred from the development unit to the circumferential surface of the intermediate transfer belt; a second control part that performs bidirectional toner pattern transfer control between the intermediate transfer belt and the secondary transfer roller by causing, in a state where the secondary transfer roller is pressed against the intermediate transfer belt by the second movement mechanism, the development unit to form the toner pattern and causing the transfer unit to transfer the toner pattern to the intermediate transfer belt, causing the secondary transfer roller part to transfer the toner pattern on the circumferential surface of the intermediate transfer belt to the secondary transfer roller part side, and thereafter once again transferring the toner pattern from the secondary transfer roller part to the intermediate transfer belt; and a second determination unit that determines that a pressing state of the intermediate transfer belt and the secondary transfer roller part moved by the second movement mechanism is normal when, after the toner pattern transfer control is performed by the second control part, the concentration of the toner pattern on the circumferential surface of the intermediate transfer belt detected by the toner pattern concentration detection unit has reached a predetermined concentration value.