Patent ID: 7103301

Claim:
An 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×N α 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, N α 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/ε opc +Gp/ε air )+√(77.37.6 ×d/ε opc ) where d denotes a film thickness (μm) of said body, ε opc denotes a specific dielectric constant of said body, ε air 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.