Image forming apparatus using a contact or a proximity type of charging system including a protection substance on a moveable body to be charged

In a process cartridge removably mounted to a body of an image forming apparatus, said image forming apparatus comprising:

• a movable body to be charged;
• and
• a charger comprising a charging member contacting or adjoining said body to be charged and configured to apply a voltage, including an AC component, to said charging member for thereby charging said body;
• wherein a protection substance for protecting a surface of said body from deterioration ascribable to charging is caused to exist on said body, and
• wherein a ratio (%) of a number of particular elements, contained in the protection substance and detected by an X-ray photon spectral analyzer (XPS) in a zone where said charging member charges said body, to a total number of all elements constituting an outermost surface of said body and detected by said XPS is expressed as:
• 1.52×10−4×{Vpp−2×Vth}×f/v×Nα
• where Vpp denotes a peak-to-peak voltage (V) of an AC voltage, f denotes a frequency (Hz) of the AC component applied to said charging member, ν denotes a moving speed (mm/sec) of the surface of said body, Nα denotes the number of, among elements constituting the protection substance, the particular elements in a single molecule, and Vth denotes a discharge start voltage produced by:
• Vth=312+6.2×(d/εopc+Gp/εair)+√(77.37.6×d/εopc)
• where d denotes a film thickness (μm) of said body, εopc denotes a specific dielectric constant of said body, εair denotes a specific dielectric constant of a space between said body and said charging member, and Gp denotes a smallest distance (μm) between a surface of said charging member and the surface of said body.