Image forming apparatus

An image forming apparatus, comprising:

• a plurality of image bearing members;
• an intermediate transfer member onto which toner images on the plurality of image bearing members are transferred to form a composite toner image;
• and
• a power source to output a transfer bias to transfer the composite toner image from the intermediate transfer member onto a sheet,
• wherein the power source outputs a first bias including an AC component when the composite toner image includes a particular color toner, and the power source outputs a second bias including only a DC component when the composite toner image does not include the particular color toner.

An image forming apparatus, comprising:

• a plurality of image bearing members;
• an intermediate transfer member onto which toner images on the plurality of image bearing members are transferred to form a composite toner image;
• and
• a power source to output a transfer bias to transfer the composite toner image from the intermediate transfer member onto a sheet,
• wherein the power source outputs a first bias including a first AC component when the composite toner image includes a particular color toner, and the power source outputs a second bias including a second AC component having a peak-to-peak value smaller than that of the first AC component when the composite toner image does not include the particular color toner.

An image forming apparatus, comprising:

• a plurality of image bearing members respectively bearing a yellow toner, a magenta toner, a cyan toner, a black toner and a metal color toner;
• an intermediate transfer member onto which toner images on the plurality of image bearing members are transferred to form a composite toner image;
• and
• a power source to output a transfer bias to transfer the composite toner image from the intermediate transfer member onto a sheet,
• wherein the power source outputs a the transfer bias including includes a DC component in superimposition with an AC component when the composite toner image includes a transparent the metal color toner, and
• wherein the transfer bias includes the DC component and does not include the AC component when the composite toner image does not include the metal color toner.

An image forming apparatus, comprising:

• an image bearing member;
• and
• a power source to output a transfer bias to transfer a toner image onto a sheet,
• wherein the power source outputs a bias including an AC component when the toner image includes a metal color toner,
• wherein the bias is a superimposed bias in which a DC component is superimposed on the AC component, and
• wherein upon transfer of the toner image onto the sheet, the power source outputs the transfer bias in which an average potential of the superimposed bias in every cycle of the AC component has a transfer polarity that causes toner to move electrostatically from an intermediate transfer member side to a nip forming member side in a transfer nip, and the toner moves from the intermediate transfer member side to the nip forming member side with the average potential than with a center value between a maximum value and a minimum value of the superimposed bias.