End sealing and magnetic field truncation of a magnetic roll of a dual electrophotographic image forming device

US9188907B1 · kind B1 · utility

Assignee

• Lexmark International, Inc. · US

Inventors

• Robert Dan Bennett, III · Paris, US
• Gary Allen Denton · Lexington, US
• Katherine Marie Gilliam · Lexington, US
• Elliott Vincent Jernigan · Indian Trail, US
• Matthew Lee Rogers · Los Gatos, US
• Dominique Renee Rowe · Lexington, US
• Daniel Alonzo · Manvel, US
• Royden Thomas Kern · Lexington, US

Key dates

• Filing date: Nov 10, 2014
• Grant date: Nov 17, 2015
• Expiry date: Nov 10, 2034

Classification

• Technology area (CPC G): Physics
• CPC primary: G03G15/0942
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A developer unit according to one example embodiment includes a housing having a reservoir for storing a developer mix that includes toner and magnetic carrier beads. A magnetic roll includes a stationary core and a sleeve positioned around the core that is rotatable relative to the core. The stationary core includes at least one permanent magnet having circumferentially spaced magnetic poles. An upper and a lower magnetically permeable metal shunt are positioned at each axial end of the magnetic roll. Each upper shunt and each lower shunt is positioned axially outboard of the core and in close proximity to the outer surface of the sleeve. A combination of the upper shunt and the lower shunt at each axial end of the magnetic roll surrounds greater than 180 degrees of the outer surface of the sleeve.