Transfer device and image forming apparatus provided with the transfer device

An image forming apparatus comprising:

• an image forming portion configured to form an image;
• an image carrier configured to carry the image formed by the image forming portion;
• a driving portion configured to drive the image carrier;
• a drive transmitting portion configured to transmit a drive from the driving portion to the image carrier;
• a supporting portion disposed on the drive transmitting portion;
• and
• a transfer portion configured to transfer the image carried by the image carrier to a recording medium, wherein
• the transfer portion includes:
• a transfer roller including a roller base member opposing the image carrier that rotates about an axis of rotation and having a concaved portion formed on an outer circumference thereof, the transfer roller being configured to transfer the image carried by the image carrier when the concaved portion does not oppose the image carrier;
• a pressing portion configured to press the transfer roller to the image carrier;
• and
• a contact portion provided at an end of the roller base member in a direction of the axis of rotation at a position corresponding to the concaved portion, the contact portion including an outer circumference that contacts with the supporting portion, the outer circumference of the contact portion having an elastic member formed therein.

An image forming apparatus comprising:

• an image forming portion configured to form an image;
• an image carrier belt configured to carry the image formed by the image forming portion;
• a driving roller configured to drive the image carrier belt;
• a transfer portion configured to transfer the image carried by the image carrier belt to a recording medium, wherein
• the transfer portion includes:
• a transfer roller including a roller base member opposing the image carrier belt that rotates about an axis of rotation and having a concaved portion formed on an outer circumference thereof, the transfer roller being configured to transfer the image carried by the image carrier belt when the concaved portion does not oppose the image carrier belt;
• a pressing portion configured to press the transfer roller to the image carrier belt;
• and
• a contact portion provided at the end of the roller base member in a direction of the axis of rotation at a position corresponding to the concaved portion, the contact portion including an outer circumference that contacts with a supporting portion located on the driving roller, the outer circumference of the contact portion having an elastic member formed therein,
• wherein the elastic member of the contact portion contacts the supporting portion disposed on the driving roller that transmits the drive to the image carrier belt when the concaved portion opposes the image carrier belt so that a load from the contact portion contacting the support portion is substantially equal to a load from the image carrier belt contacting the transfer roller.