Two-component developer, container filled with the two-component developer, and image formation apparatus

US6544704B1 · kind B1 · utility

Assignee

• RICOH COMPANY, LTD. · JP

Inventors

• Hiroaki Matsuda · Osaka, JP
• Masanori Suzuki · Hanamaki, JP
• Akemi Sugiyama · Numazu, JP
• Hiroto Higuchi · Numazu, JP
• Tsunemi Sugiyama · Kashiwa, JP
• Fumihiro Sasaki · Nanbu, JP
• Yasuaki Iwamoto · Numazu, JP
• Hiroshi Nakai · Hamamatsu, JP
• Kumi Hasegawa · Numazu, JP

Key dates

• Filing date: Aug 30, 2002
• Grant date: Apr 8, 2003
• Expiry date: Aug 30, 2022

Classification

• Technology area (CPC G): Physics
• CPC primary: G03G9/1085
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A two-component developer comprises a toner which contains at least a resin and a colorant and to which an external additive is added, and a carrier. The toner has a number average molecular weight (Mn) not greater than 3,000 and contains particles having a molecular weight not greater than 1,000 in an amount not less than 40 number %. The carrier satisfies the relation3,000,000≦&sgr;1000×Dc3≦20,000,00  (1)where &sgr;1000 represents a magnetization (emu/g) of the carrier at 1,000 oersted, and Dc represents a volume average particle diameter (&mgr;m) of the carrier.