Image forming apparatus

An image forming apparatus comprising:

• an image bearing member configured to rotate;
• a charging unit configured to charge the image bearing member at a charging portion;
• a developing unit configured to develop an electrostatic latent image formed on the image bearing member into a toner image using toner at a developing portion;
• a transfer unit configured to transfer the toner image to a transfer material at a transfer portion;
• and
• a brush member arranged to be in contact with the image bearing member at a position downstream of the transfer portion and upstream of the charging portion in a direction of rotation of the image bearing member,
• wherein the image forming apparatus is configured such that residual toner that has not been transferred to the transfer material at the transfer portion is collected by the developing unit at the developing portion,
• wherein the brush member includes a base body, and a filament portion that is supported by the base body and that is configured to come into contact with the image bearing member,
• wherein in a case where:
• (i) one of end points of a curved line obtained by subjecting a filament of the filament portion to parallel projection from a predetermined direction is referred to as a starting point of the curved line,
• (ii) a length measured from the starting point to an arbitrary point p on the curved line along the curved line is referred to as variable x, and
• (iii) a distance between the point p and a straight line connecting both end points of the curved line is referred to as function ƒ(x) of x,
• 50% or more of filaments of the filament portion are each a filament of which the function ƒ(x) has an inflection point, and are arranged in a dispersed manner over an entire range of the filament portion in the direction of rotation of the image bearing member.