Patent ID: 7738813

Claim:
A corona charger, comprising: a case provided in the vicinity of the device to be charged, including an opening facing the device; a discharge electrode provided inside the case and supplied with a voltage so as to generate a corona discharge, and configured to charge a surface of the device from the opening by supplying the corona discharge to the surface; a first charging region including a first grid electrode to which a predetermined voltage is applied at a position upstream of the opening in the surface moving direction of the device and charged to a first grid potential (Vg 1 ); and a second charging region including a second grid electrode to which a predetermined voltage is applied at a position downstream of the opening and charged to a second grid potential (Vg 2 ) substantially near a target charge potential of the device, wherein the voltage applied to the discharge electrode is an alternating current (AC) voltage superimposed on a direct current (DC) voltage, and wherein both of the following relations are satisfied: | Vg 1|>| Vg 2| and | Vp 1|>| Vg 2|, wherein |Vg 1 | is an absolute value of the first grid potential, |Vg 2 | is an absolute value of the second grid potential, and |Vp 1 | is an absolute value of a surface potential of the device after passing the first charging region.