Process cartridge

A process cartridge that is attachable to and detachable from an image forming apparatus, the process cartridge comprising:

• a developing chamber,
• wherein the developing chamber includes
• a toner,
• a developing roller that develops an electrostatic latent image with the toner,
• a regulating member that is disposed in contact with the developing roller and regulates a layer thickness of the toner carried by a surface of the developing roller, and
• a toner supplying roller that is disposed in contact with the developing roller and supplies the toner to the developing roller;
• a driving force receiving unit provided at an axial end portion of the toner supplying roller;
• a first driving force transmitting unit for transmitting a driving force from the driving force receiving unit to the toner supplying roller;
• a second driving force transmitting unit provided in the toner supplying roller and used to transmit the driving force received by the first driving force transmitting unit to the developing roller;
• and
• a third driving force transmitting unit provided in the developing roller and used to transmit the driving force from the second driving force transmitting unit to the developing roller,
• wherein a movement direction of the surface of the developing roller is opposite to a movement direction of a surface of the toner supplying roller in a position where the surface of the developing roller is in contact with the surface of the toner supplying roller,
• wherein the developing roller and the toner supplying roller are configured such that a peripheral speed ratio R represented by Equation (E1) satisfies
• 1.1≤R≤2.5,
• R
• =
• ⁢
• V
• RS
• /
• V
• D
• (
• E
• ⁢
• 1
• )
• (in Equation (E1), VRs represents an absolute value [m/sec] of a peripheral speed of the surface of the toner supplying roller, and VD represents an absolute value [m/sec] of a peripheral speed of the surface of the developing roller),
• wherein the toner contains a toner particle and an external additive A,
• wherein the toner has an average circularity of 0.955 or greater and 0.975 or less, a proportion of the particle having a circularity of 0.900 or greater and 0.930 or less in a circularity distribution of the toner is 2.0% by number or greater and 15.0% by number or less, and
• wherein the external additive A is a needle-like inorganic fine particle having a major axis of 100 nm or greater and 3000 nm or less, and a proportion of the toner particle having a surface where the external additive A is confirmed to be present is 30% by number or greater when the toner is observed using a scanning electron microscope.