Electrophotographic method using hard magnetic carrier particles

A multicolor electrophotographic reproduction method of the type including the steps of

• creating a first electrostatic image on an image receiving area of a photoconductive member, said image having reduced levels of charge compared to the rest of said area,
• applying finely divided toner of a first color to said image to create a first toner image,
• creating a second electrostatic image on said image receiving area, said second electrostatic image having reduced levels of charge compared to the rest of said area, and
• without fixing said first toner image applying finely divided toner of a second color to said second electrostatic image to form a second toner image without substantially disturbing the first toner image,
• characterized in that said step of applying toner of a second color includes the steps of
• moving said second electrostatic image through a development zone at a predetermined velocity, and
• transporting developer, including hard magnetic carrier particles, said particles being sufficiently hard to flip or tumble as they pass through said development zone, and colored toner particles, through said development zone and into contact with said photoconductive member at a velocity approximating that of said photoconductive member to develop said second electrostatic image.

A multicolor electrophotographic reproduction method of the type including the steps of

• creating a first electrostatic image on an image receiving area of a photoconductive member, said image having reduced levels of charge compared to the rest of said area,
• applying finely divided toner of a first color to said image to create a first toner image,
• creating a second electrostatic image on said image receiving area, said second electrostatic image having reduced levels of charge compared to the rest of said area, and
• without fixing said first toner image, applying finely divided toner of a second color to said second electrostatic image to form a second toner image without substantially disturbing the first toner image,
• characterized in that said step of applying toner of a second color includes the steps of
• moving said second electrostatic image through a development zone, and
• transporting developer, including hard magnetic carrier particles and electrically insulative toner particles, said particles being sufficiently hard to flip or tumble as they pass through said development zone, through said development zone in contact with the second electrostatic image by rotating an alternating-pole magnetic core within a non-magnetic shell upon which shell the developer flows through said development zone.

A multicolor reproduction method of the type including the steps of

• creating a first electrostatic image on an image receiving area of a photoconductive member,
• applying finely divided toner of a first color to said image to create a first toner image,
• creating a second electrostatic image on said image receiving area,
• without fixing said first toner image, applying finely divided toner of a second color to said second electrostatic image to form a second toner image without substantially disturbing the first toner image,
• characterized in that said step of applying toner of a second color includes the steps of
• moving said second electrostatic image through a development zone at a predetermined velocity, and
• transporting developer, including hard magnetic carrier particles, said particles being sufficiently hard to flip or tumble as they pass through said development zone, and electrically insulative toner particles, through said development zone into contact with the second electrostatic image at a velocity approximating that of said second electrostatic image by rotating an alternating-pole magnetic core within a non-magnetic shell upon which shell the developer flows through said development zone and into contact with said second electrostatic image.

A multicolor reproduction method of the type including the steps of

• applying a uniform electrostatic charge of a first polarity to the surface of a moving photoconductive member,
• imagewise exposing said charged member to create a first pattern of charged and relatively discharged portions,
• applying finely divided toner of a first color and of said first polarity to said pattern to create a first toner image adhering to the relatively discharged portions,
• again imagewise exposing said charged member to create a second pattern of relatively discharged portions in the portions that were charged in the first pattern,
• without fixing said first toner image, applying finely divided toner of a second color and said first polarity to said second pattern to create a second toner image adhering to the second relatively discharged portions without substantially disturbing the first toner image to create a multicolor toner image,
• characterized in that said step of applying toner of a second color includes the steps of
• moving said photoconductive member through a development zone, and
• transporting developer, including hard magnetic carrier particles, said particles being sufficiently hard to flip or tumble as they pass through said development zone, and electrically insulative toner particles, through said development zone into contact with the second electrostatic image by rotating an alternating-pole magnetic core within a non-magnetic shell upon which shell the developer flows through said development zone and into contact with said second electrostatic image.