US Patent 7184699 Cleaning blade for image formation apparatus

A cleaning device and process cartridge including the same for an image formation apparatus, which prevents cleaning failures due to toner slipping past a blade, based on an equation for the force of toner particle rotation and the restraining force. Toner on an image carrier is removed by a blade. The relation between the blade and the image carrier satisfies the equation f(θ)=μ2−μ1×(Ntp/Nbt+cosθ)>0. Here μ1 is the friction coefficient between toner and image carrier, μ2 is the friction coefficient between toner and blade, Ntp is the adhesive force between toner and image carrier, Nbt is the force received by the toner from the blade, and θ is the angle formed by the blade and image carrier (the cleaning angle).