Developing apparatus, process cartridge, and electrophotographic image forming apparatus

A process cartridge configured to be attachable/detachable to/from a main body of an electrophotographic image forming apparatus,

• the process cartridge comprising a developing apparatus comprising:
• a toner comprising a toner particle and external additive;
• a toner carrying member for carrying the toner;
• and
• a charge injection member configured to inject electric charge into the toner, wherein
• the external additive contains titanium atom-containing fine particles containing a compound containing titanium atoms,
• a presence ratio of the titanium atoms is 0.05 to 4.00 atomic % when a surface of the toner is measured using X-ray photoelectron spectroscopy,
• the toner carrying member is a developing roller having
• a substrate having a conductive outer surface and
• a resin layer on the outer surface of the substrate,
• a metal film is directly provided on an outer surface of the developing roller, and under an environment of 23° C. temperature and 50% relative humidity, when an AC voltage of which an amplitude is 50 V is applied between the outer surface of the substrate and the metal film with a frequency changing in a range of 1.0×10−1 to 1.0×105 Hz while a DC voltage of 50 V is applied therebetween, an impedance at the frequency of 1.0×100 to 1.0×101 Hz is 1.00× 106 Ω or more, and
• under an environment of 23° C. temperature and 50% relative humidity, a corona discharger having a grid portion of which a width is 3.0 mm is arranged such that a distance between the grid portion and the outer surface of the developing roller is 1.0 mm, and a direction of the width of the grid portion coincides with an axial direction of the developing roller, and when a voltage of 8 kV is applied to the grid portion, and the outer surface of the developing roller is charged by relatively moving the corona discharger in the axial direction of the developing roller at a speed of 400 mm/sec, a maximum value of an electric potential of the outer surface is less than 20.0 V when the electric potential is measured after 0.06 seconds from passage of the grid portion.

An electrophotographic image forming apparatus comprising a developing apparatus comprising:

• a toner comprising a toner particle and external additive;
• a toner carrying member for carrying the toner;
• and
• a charge injection member configured to inject electric charge into the toner, wherein
• the external additive contains titanium atom-containing fine particles containing a compound containing titanium atoms,
• a presence ratio of the titanium atoms is 0.05 to 4.00 atomic % when a surface of the toner is measured using X-ray photoelectron spectroscopy,
• the toner carrying member is a developing roller having
• a substrate having a conductive outer surface and
• a resin layer on the outer surface of the substrate,
• a metal film is directly provided on an outer surface of the developing roller, and under an environment of 23° C. temperature and 50% relative humidity, when an AC voltage of which an amplitude is 50 V is applied between the outer surface of the substrate and the metal film with a frequency changing in a range of 1.0×10−1 to 1.0×105 Hz while a DC voltage of 50 V is applied therebetween, an impedance at the frequency of 1.0×100 to 1.0×101 Hz is 1.00×106 Ω or more, and
• under an environment of 23° C. temperature and 50% relative humidity, a corona discharger having a grid portion of which a width is 3.0 mm is arranged such that a distance between the grid portion and the outer surface of the developing roller is 1.0 mm, and a direction of the width of the grid portion coincides with an axial direction of the developing roller, and when a voltage of 8 kV is applied to the grid portion, and the outer surface of the developing roller is charged by relatively moving the corona discharger in the axial direction of the developing roller at a speed of 400 mm/sec, a maximum value of an electric potential of the outer surface is less than 20.0 V when the electric potential is measured after 0.06 seconds from passage of the grid portion.