Image forming apparatus

An image forming apparatus which transfers an image formed on an image carrier onto a transfer material at a transfer position, the image forming apparatus comprising:

• a transfer member which contacts with the image carrier at the transfer position;
• a power supply circuit which applies constant voltage to the transfer member when the transfer material is reached at the transfer position;
• and
• a processor which instructs the power supply circuit to do application to the transfer member,
• wherein at a time when the transfer material is not transferred, the power supply circuit applies constant current to the transfer member at a current value set by the processor, and measures a voltage value obtained during that constant current application, and
• the processor sets as a voltage value at a time when transfer is done to the power supply circuit a voltage value that the measures voltage value is added with a compensation voltage value corresponding to the transfer material.

An image forming apparatus which transfers an image formed on an image carrier onto a transfer material at a transfer position, the image forming apparatus comprising:

• a transfer member which contacts with the image carrier at the transfer position;
• a power supply circuit which applies constant voltage to the transfer member when the transfer material is reached at the transfer position;
• and
• a processor which instructs the power supply circuit to do application to the transfer member,
• wherein at a time when the transfer material is not transferred, the power supply circuit applies constant voltage to the transfer member at a voltage value set by the processor, and measures a current value obtained during that constant voltage application, and
• based on the applied voltage value during that constant voltage application and the measured current value, the processor calculates a voltage value when current is applied at a predetermined current value, and sets as a voltage value at a time when transfer is done to the power supply circuit a voltage value that the calculated voltage value is added with a compensation voltage value corresponding to the transfer material.