Process cartridge and image forming apparatus

An image forming apparatus configured to form an image on a recording medium, the apparatus comprising:

• a process cartridge mountable to and removable from an apparatus main body of the image forming apparatus, the process cartridge including:
• an electrophotographic photosensitive member;
• a developing roller configured to develop an electrostatic latent image formed on the electrophotographic photosensitive member by a developer;
• a cleaning blade configured to remove the developer from the electrophotographic photosensitive member;
• a developer container including an opening through which the developer is supplied to the developing roller and configured to contain the developer;
• a developer conveyance member rotatably supported by the developer container and configured to convey the developer to the developing roller;
• a driving force transmission member having a driving force transmitted from the developer conveyance member;
• a seal member configured to seal the opening;
• and
• a winding member configured to wind the seal member such that the opening is opened,
• wherein the driving force transmission member is configured to take a first position at which the driving force is not transmitted to the winding member and a second position at which the driving force is transmitted to the winding member, and wherein the driving force transmission member is further configured to move from the first position to the second position after rotation of the developer conveyance member, and
• a conveying unit configured to convey the recording medium.