Image forming apparatus and image forming method

An image forming method comprising:

• carrying an image on a transfer belt suspended by a belt suspension roller;
• transferring the image to a transfer material by passing the transfer material through a transfer nipping area formed by causing a transfer roller having a concave portion formed in a shaft direction to come into contact with the belt suspension roller with the transfer belt in between;
• and
• after transferring the image to the transfer material, causing a support member that is arranged on a shaft portion of the transfer roller and includes a first circumferential portion arranged in the concave portion of the transfer roller as seen from a shaft direction of the transfer roller, a second circumferential portion arranged at one side of the concave portion in a rotation direction of the transfer roller as seen from the shaft direction of the transfer roller, and a third circumferential portion arranged at the other side of the concave portion from the one side in the rotation direction of the transfer roller as seen from the shaft direction of the transfer roller to come into contact with a second support member arranged at a shaft end portion of the belt suspension roller.

An image forming apparatus comprising:

• a transfer belt on which an image is transferred;
• a belt suspension roller that stores the transfer belt;
• a transfer roller that is arranged so as to face the belt suspension roller with the transfer belt disposed in between, the transfer roller including a shaft portion and a concave portion formed in a shaft direction;
• a support member that is arranged on the shaft portion of the transfer roller and includes a first circumferential portion arranged in the concave portion of the transfer roller as seen from a shaft direction of the transfer roller, a second circumferential portion arranged at one side of the concave portion in a rotation direction of the transfer roller as seen from the shaft direction of the transfer roller, and a third circumferential portion arranged at the other side of the concave portion from the one side in the rotation direction of the transfer roller as seen from the shaft direction of the transfer roller;
• and
• a transfer material holding section that holds a transfer material, the transfer material holding section being arranged on the side of the third circumference portion of the concave portion of the transfer roller,
• wherein the second circumference portion has a first curvature and the third circumference portion has a second curvature different from the first curvature, and wherein the first curvature is set to be larger than the second curvature.