US Patent 7639976 Image forming apparatus

An image forming apparatus includes an image carrier that carries toner images, and an intermediate transfer member onto which the toner images are primarily transferred, sequentially from a first toner image, from the image carrier. A primary transfer bias applied upon primary transfer of the first toner image is higher than a primary transfer bias applied upon primary transfer of other toner images. The intermediate transfer member has a surface potential attenuation ratio such that residual potential of the intermediate transfer member applied with a voltage of 500 volts becomes equal to or lower than 250 volts after five seconds.