Image forming apparatus featuring control voltages applied to magnetic particle carrying members

An image forming apparatus comprising:

• a rotatable image bearing member;
• charging means for charging said image bearing member, said charging means including a first magnetic particle carrying member for carrying electroconductive magnetic particles and a second magnetic particle carrying member for carrying electroconductive magnetic particles, said second magnetic particle carrying member being disposed downstream of said first magnetic particle carrying member with respect to a rotational direction of said image bearing member, wherein the magnetic particles are in contact with said image bearing member while charging said image bearing member;
• latent image forming means, disposed downstream of said charging means with respect to the rotational direction of said image bearing member, for forming a latent image on said image bearing member;
• potential detecting means for detecting a surface potential of said image bearing member, said potential detecting means being disposed downstream of said charging means with respect to the rotational direction of said image bearing member;
• phase detecting means for detecting information relating to a rotational phase of said second magnetic particle carrying member;
• and
• control means for controlling voltages applied to said first magnetic particle carrying member and to said second magnetic particle carrying member,
• wherein said control means is capable of executing an operation in a control mode for controlling the voltages applied to said first magnetic particle carrying member and to said second magnetic particle carrying member, on the basis of a result of detection by said potential detecting means and a result of detection by said phase detecting means.