Patent ID: 8712267

Claim:
An image forming apparatus comprising: a rotatable image carrier configured to carry a toner image developed with toner on a surface of the image carrier; a rotatable transfer member configured to form a transfer nip by contacting the image carrier surface; and a power supply configured to output a voltage to transfer the toner image formed on the image carrier surface to a recording material captured in the transfer nip, wherein the voltage is switched alternately between a voltage in a transfer direction to transfer the toner image from the image carrier to the recording material and a voltage opposite to the voltage in the transfer direction when the toner image formed on the image carrier surface is transferred to the recording material, wherein a time average value (Vave) of the voltage has a polarity of the transfer direction to transfer the toner image from the image carrier to the recording material and is set to a value closer to a transfer voltage side, and wherein the image forming apparatus has a mode to change a cycle of the voltage output from the power supply based on toner information indicating a state of deterioration of the toner.