Patent ID: 8175473

Claim:
A charging device, comprising: a charging member disposed to be opposed to a body to be charged, the charging member including: a conductor shaft; a charging member main body that coats an outer circumferential surface of the conductor shaft; and a surface layer that coats a surface of the charging member main body and contains dispersed fine particles, the surface layer having a surface with asperities due to the dispersed fine particles; a charging power source that applies a charging voltage to the charging member, the charging voltage being produced by superimposing a constant-current-controlled AC voltage on a preset DC voltage; a temperature dependence storage unit that stores preset temperature dependence representing a relationship between a constant current value at the time the AC voltage is constant-current-controlled and an ambient temperature which is a temperature in a vicinity of the charging member; a humidity dependence storage unit that stores preset humidity dependence representing a relationship between the constant current value and the ambient temperature and an ambient humidity which is a humidity in the vicinity of the charging member; an ambient temperature detecting unit that detects an ambient temperature in the vicinity of the charging member; an ambient humidity detecting unit that detects an ambient humidity in the vicinity of the charging member; and a charging voltage control unit that applies the charging voltage to the charging member according to a selection from one of (i) a constant current value that is determined according to the temperature dependence as corresponding to the detected ambient temperature and (ii) a constant current value that is determined according to the humidity dependence as corresponding to the detected ambient temperature and the detected ambient humidity.