Patent ID: 8792795

Claim:
An image forming apparatus comprising: a conveyor member; a process unit comprising: a photosensitive member; an image forming portion configured to form a developer image with a developer on the photosensitive member; a transfer member configured to transfer the developer image formed on the photosensitive member onto the conveyor member, wherein the developer remaining on the photosensitive member after transferring the developer image from the photosensitive member is transfer residual developer; and a catching portion configured to catch the transfer residual developer from the photosensitive member, wherein the catching portion is configured to return the transfer residual developer caught by the catching portion to the photosensitive member, and wherein the transfer member is configured to transfer the transfer residual developer returned to the photosensitive member from the catching portion onto the conveyor member; and a controller configured to: determine whether the transfer residual developer is present or absent on a surface of the conveyor member using a sensor; and change an image formation criteria based on the presence or absence of the transfer residual developer on the surface of the conveyor member determined by the controller, wherein the image formation criteria comprises at least one of: an amount of bias applied to the developer for forming the developer image, an amount of bias applied to the transfer member for transfer of the developer image, and an exposure intensity of light irradiated on the photosensitive member.