Abstract: A developer roll according to one example embodiment includes a core including at least one permanent magnet forming a magnetized portion of the core. A cylindrical sleeve positioned around the core is rotatable relative to the core about an axis of rotation in an operative rotational direction. A release pole of the permanent magnet is positioned to magnetically attract developer mix to an outer circumferential surface of the sleeve to transport developer mix on the surface of the sleeve in the operative rotational direction when the sleeve rotates relative to the core to a release point where a magnetic field of the permanent magnet is insufficient to retain developer mix against the surface of the sleeve. An axial length of the magnetized portion of the core decreases at both axial ends of the core as the magnetized portion of the core approaches the release point in the operative rotational direction.

Abstract: A developer roll according to one example embodiment includes a core including at least one permanent magnet forming a magnetized portion of the core. A cylindrical sleeve positioned around the core is rotatable relative to the core about an axis of rotation in an operative rotational direction. A release pole of the permanent magnet is positioned to magnetically attract developer mix to an outer circumferential surface of the sleeve to transport developer mix on the surface of the sleeve in the operative rotational direction when the sleeve rotates relative to the core to a release point where a magnetic field of the permanent magnet is insufficient to retain developer mix against the surface of the sleeve. An axial length of the magnetized portion of the core decreases at both axial ends of the core as the magnetized portion of the core approaches the release point in the operative rotational direction.

Abstract: An outer sleeve of a magnetic roll for a dual component development electrophotographic image forming device according to one example embodiment includes a series of grooves in an outer surface of the outer sleeve. The grooves extend along an axial length of the sleeve and are spaced circumferentially from each other around the outer sleeve. The outer sleeve has a diameter of between 15 mm and 30 mm, inclusive. The grooves are present on the outer surface of the outer sleeve at a groove density of at least 1.91 grooves/mm of the circumference of the outer surface of the outer sleeve and a total indicated runout of the outer sleeve is 0.05 mm or less.

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.

Abstract: An outer sleeve of a magnetic roll for a dual component development electrophotographic image forming device according to one example embodiment includes a series of grooves in an outer surface of the outer sleeve. The grooves extend along an axial length of the sleeve and are spaced circumferentially from each other around the outer sleeve. The outer sleeve has a diameter of between 15 mm and 30 mm, inclusive. The grooves are present on the outer surface of the outer sleeve at a groove density of at least 1.91 grooves/mm of the circumference of the outer surface of the outer sleeve and a total indicated runout of the outer sleeve is 0.05 mm or less.

Abstract: A magnetic roll for transporting a dual component developer mix according to one embodiment includes a core having at least one permanent magnet that has a plurality of circumferentially spaced magnetic poles generating a magnetic field. A cylindrical sleeve is positioned around the core. The sleeve is rotatable relative to the core about a rotational axis in an operative rotational direction. At portions of the magnetic roll positioned axially inward from axial ends of the core, a magnitude of a total magnetic field strength of the magnetic field decreases by 1.5 mT/degree or less in the operative rotational direction at a radius of 0.5 mm beyond an outer circumferential surface of the sleeve throughout an area of ±15 degrees from an angular position of the magnetic roll at which a tangential component of the magnetic field is equal to zero at a release pole of the plurality of magnetic poles.

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.

Abstract: A developer unit for a dual component development electrophotographic image forming device includes a housing having a reservoir for storing a developer mix that includes toner and magnetic carrier beads. An axial sealing rib projects from an inner side of the housing toward the outer surface of a sleeve of a magnetic roll. The axial sealing rib extends along an axial length of the sleeve. A distal end of the axial sealing rib is positioned in close proximity to and spaced from the outer surface of the sleeve. The axial sealing rib is positioned to impede the flow of developer mix in the reservoir in a direction counter to an operative rotational direction of the sleeve.

Abstract: A developer unit for a dual component development electrophotographic image forming device according to one example embodiment includes a housing having a reservoir for storing a developer mix that includes toner and magnetic carrier beads. An auger is positioned to convey developer mix in the reservoir toward the outer surface of a magnetic roll on a front of the housing. A ledge on an inner surface of the housing extends axially with respect to the magnetic roll along a front of the reservoir. The ledge is positioned upstream from a trim bar and downstream from a pickup pole of the magnetic roll with respect to the operative rotational direction of the magnetic roll. The ledge has a concave curved inner surface that is open to the reservoir and extends from near the trim bar to near a front side of the auger.

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.

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. At least one external shunt is composed of a magnetically permeable metal and is positioned at each axial end of the magnetic roll axially outboard of the core and in close proximity to the outer surface of the sleeve along a first circumferential portion of the core. At least one internal shunt is positioned at each axial end of the core inside of the sleeve. Each internal shunt has a shunt portion composed of a magnetically permeable metal and positioned along a second circumferential portion of the core.