Contact charging member, image forming unit including the contact charging member and electrophotographic image forming apparatus including the image forming unit

• Main Authors: ONO; NORIKI, ABE; TETSUYA, KANASUGI; MASAKI, KOUROKU; MORIYUKI, YORIFUJI; TAKAO
• Format: Patent
• Language: English
• Published: 07.12.1999
• Edition: 6
• Subjects: BEARINGS; BLASTING; CINEMATOGRAPHY; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; ELEMENTS OR CRANKSHAFT MECHANISMS; ENGINEERING ELEMENTS AND UNITS; FLEXIBLE SHAFTS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; HOLOGRAPHY; LIGHTING; MAGNETOGRAPHY; MECHANICAL ENGINEERING; PHOTOGRAPHY; PHYSICS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; SHAFTS; THERMAL INSULATION IN GENERAL; WEAPONS

A roller-shaped contact charging member which is in contact with and electrically charges a photosensitive drum is provided on a center shaft, and includes a roller-shaped conductive foam material portion covering the shaft, and a tubular-shaped conductive resin material portion covering the foam portion. The foam portion has an electric resistance of 9x105 OMEGA or less, the resin portion includes conductive agents and has a surface electric resistance in a range from 1x105 OMEGA / &squ& or more to 9x107 OMEGA / &squ& or less, and a hardness of the charging roller as a whole is Asker F 90 DEG or less. An image forming unit includes the charging member and the drum. An electrophotographic image forming apparatus supplies a recording paper to the unit, transfers an image from the drum to the paper, and discharges the image-transferred paper.