Toner pattern density correction in an image forming apparatus

An image forming apparatus comprising:

• an endless belt-shaped image bearer that is rotatably supported and entrained around rollers;
• a transfer member positioned to contact an outer surface of the image bearer;
• a transfer device to transfer a toner image conveyed while being carried on the outer surface of the image bearer onto a transfer medium conveyed between the image bearer and the transfer member, and to transfer medium conveyed between the image bearer and the transfer member, and to transfer a toner pattern for inspection of an image density on the outer surface of the image bearer onto the transfer member;
• a toner image sensor to detect the image density of the toner pattern transferred onto the transfer member;
• a conveyance speed controller to tune a conveyance speed of the transfer member in accordance with a type of the transfer medium, wherein detection result of the toner image sensor is corrected based on the conveyance speed of the transfer member, and image forming conditions are corrected based on the corrected detection result of the toner image sensor;
• and
• a potential controller to implement a first toner image density control in which density control is performed regularly, when the image forming apparatus is not forming and image;
• the potential controller to implement a second toner image density control in which the density control is performed regularly in synchrony with image formation but between successive sheets.