Compact corona charging device

In combination:

• a conductive member;
• a corona electrode spaced from said member no more than about 0.15 cm, said electrode comprising a conductive wire coated with a thick dielectric material, the thickness of the dielectric being sufficient to prevent the flow of conduction current through said wire;
• an imaging surface carried on a conductive substrate, said surface located adjacent said electrode,
• means for establishing a corona producing a.c. electric field adjacent said electrode;
• and
• means for generating a d.c. electric field in the space intermediate said wire and said substrate.

A corona device for depositing charge on a chargeable surface comprising:

• a conductive member;
• a corona electrode in contact with said conductive member, said electrode comprising a conductive wire coated with a thick dielectric material, said dielectric preventing the flow of conduction current through said wire;
• means for generating a corona causing a.c. field adjacent the surface of said electrode;
• and
• means for generating d.c. fields between the chargeable surface and the electrode and between the conductive member and the electrode, whereby charge is moved from the area adjacent said electrode as a function of the relative strength of said d.c. fields.

A corona charging arrangement for depositing charge on a photoconductive imaging surface comprising:

• an electrode including a conductor coated with a thick dielectric, the dielectric acting to prevent the flow of conduction current therethrough,
• said imaging surface located adjacent said electrode and carried on a conductive substrate, said imaging surface located adjacent said electrode and carried on a conductive substrate,
• a conductive member in contact with said electrode,
• means for applying an a.c. corona generating field to create a corona discharge adjacent the surface of said electrode, and
• means for applying a d.c. potential between said substrate and said member to produce a charge directing field to move charge from the surface of said electrode toward said imaging surface.