Patent ID: 7499668

Claim:
An image forming apparatus comprising: an image carrier that is substantially drum shaped and that is rotatably disposed, the image carrier including an outer face on which a plurality of color images are formed; a plurality of roll portions; a belt member that is rotatably formed, the belt member including an inner side, an outer side, and a predetermined non-image forming area; wherein the inner side is stretched around the plurality of roll portions; the outer side includes a surface contact area for being in surface contact with a part of the outer face of the image carrier such that the plurality of color images formed on the image carrier are transferred to the surface contact area; the belt member is driven by a rotation of the image carrier and includes a predetermined non-image forming area; the belt member is operated in a slippage prevention mode in which the belt member is moved and stopped at a slippage preventing position where the predetermined non-image forming area faces the surface contact area; and a position detecting sensor that detects a position of a positioning marker that is placed on the belt member; wherein the image forming apparatus has a standby stop mode in which the belt member is moved and stopped at a standby position and the positioning marker and the position detecting sensor are separated from each other by a predetermined distance; and the standby stop mode is executed during an image formation standby period, and the slippage prevention mode is executed when a predetermined period of time has elapsed from the image formation standby period.