Development apparatus employing magnetic field shapers

Claim 1

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic means, generating a magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone; first magnetic field shaping means, coupled to said magnetic means for enhancing the magnetic field generated by said magnetic means in a direction toward the photoconductive surface and for attenuating the magnetic field in the release zone so that substantially all the carrier beads moved to the release zone are released from said magnetic means; and second magnetic field shaping means positioned proximate to said magnetic means for attenuating the magnetic field generated by said magnetic means in an area after the release zone to release the carrier beads adhering to the magnetic means after passing through the release zone.

Claim 2

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic means, generating a magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone; first magnetic field shaping means, coupled to said magnetic means for enhancing the magnetic field generated by said magnetic means in a direction toward the photoconductive surface and for attenuating the magnetic field in the release zone so that substantially all the carrier beads moved to the release zone are released from said magnetic means; and second magnetic field shaping means positioned proximate to said magnetic means for attenuating the magnetic field generated by said magnetic means in an area after the release zone to release the carrier beads adhering to the magnetic means after passing through the release zone.

Claim 9

A method of developing a latent image recorded on a moving photoconductive surface comprising the steps of: moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; positioning a cylindrical housing downstream from the development zone adjacent the photoconductive surface; generating, in a cleaning zone, a magnetic field from within the cylindrical housing, for attracting magnetic carrier beads adhering to the photoconductive surface after the photoconductive surface passes through the development zone, and moving such carrier beads to a release zone; decreasing the magnetic field intensity in the release zone so as to release substantially all of the carrier beads from the cylindrical housing; and reducing the magnetic field generated in a region between the release zone and the cleaning zone to release the carrier beads in this region to limit carrier bead attraction and adhesion on the housing in all areas remote from the photoconductive surface.

Claim 10

A method of developing a latent image recorded on a moving photoconductive surface comprising the steps of: moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; positioning a cylindrical housing downstream from the development zone adjacent the photoconductive surface; generating, in a cleaning zone, a magnetic field from within the cylindrical housing, for attracting magnetic carrier beads adhering to the photoconductive surface after the photoconductive surface passes through the development zone, and moving such carrier beads to a release zone; decreasing the magnetic field intensity in the release zone so as to release substantially all of the carrier beads from the cylindrical housing; and reducing the magnetic field generated in a region between the release zone and the cleaning zone to release the carrier beads in this region to limit carrier bead attraction and adhesion on the housing in all areas remote from the photoconductive surface.

Claim 11

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for delivering magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; a bead removal device positioned adjacent the photoconductive surface and downstream from the development zone; said device having a rotatable outer shell and fixed magnetic means positioned within the shell; a first magnetic shunt disposed in the shell to shape the magnetic field to urge capture of any beads passing between the photoconductive surface and the bead removal device and to urge release of such captured carriers into a sump as the shell rotates; and a second magnetic shunt positioned to shape the magnetic field to urge release of beads captured during reverse rotation of the shell and to shape the magnetic field to minimize the magnetic field on a portion of the shell to inhibit bead chain formation.

Claim 12

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for delivering magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; a bead removal device positioned adjacent the photoconductive surface and downstream from the development zone; said device having a rotatable outer shell and fixed magnetic means positioned within the shell; a first magnetic shunt disposed in the shell to shape the magnetic field to urge capture of any beads passing between the photoconductive surface and the bead removal device and to urge release of such captured carriers into a sump as the shell rotates; and a second magnetic shunt positioned to shape the magnetic field to urge release of beads captured during reverse rotation of the shell and to shape the magnetic field to minimize the magnetic field on a portion of the shell to inhibit bead chain formation.

Claim 13

An apparatus for developing a latent image recorded on a moving photoconductive surface, comprising: a developer roller for developing the latent image with toner of predetermined polarity, said roller being selectively rotatable in a first direction and in a second direction reversed from the first direction; magnetic means for generating a magnetic field, said magnetic means being mounted stationarily interiorly of said roller; ferromagnetic field shaping means disposed within said roller to shape the magnetic fields induced by the magnetic means, said field shaping means being mounted stationarily interiorly of said roller; said magnetic means and said field shaping means being positioned to attract carrier beads having toner adhering triboelectrically thereto for delivery to a development zone and to release the carrier beads from the roller in a release zone during rotation of said roller in the first direction and to inhibit transporting carrier beads through the development zone during rotation of said roller in the second direction; and a bead removal device positioned adjacent the photoconductive surface and downstream from the development zone, said device having a rotatable outer shell and fixed magnetic means positioned within the shell, a first magnetic shunt disposed in the shell to shape the magnetic field to urge capture of any beads passing between the photoconductive surface and the bead removal device and to urge release of such captured carriers into a sump as the shell rotates, and a second magnetic shunt positioned to shape the magnetic field to urge release of beads captured during reverse rotation of the shell and to shape the magnetic field to minimize the magnetic field on a portion of the shell to inhibit bead chain formation.

Claim 14

An apparatus for developing a latent image recorded on a moving photoconductive surface, comprising: a developer roller for developing the latent image with toner of predetermined polarity, said roller being selectively rotatable in a first direction and in a second direction reversed from the first direction; magnetic means for generating a magnetic field, said magnetic means being mounted stationarily interiorly of said roller; ferromagnetic field shaping means disposed within said roller to shape the magnetic fields induced by the magnetic means, said field shaping means being mounted stationarily interiorly of said roller; said magnetic means and said field shaping means being positioned to attract carrier beads having toner adhering triboelectrically thereto for delivery to a development zone and to release the carrier beads from the roller in a release zone during rotation of said roller in the first direction and to inhibit transporting carrier beads through the development zone during rotation of said roller in the second direction; and a bead removal device positioned adjacent the photoconductive surface and downstream from the development zone, said device having a rotatable outer shell and fixed magnetic means positioned within the shell, a first magnetic shunt disposed in the shell to shape the magnetic field to urge capture of any beads passing between the photoconductive surface and the bead removal device and to urge release of such captured carriers into a sump as the shell rotates, and a second magnetic shunt positioned to shape the magnetic field to urge release of beads captured during reverse rotation of the shell and to shape the magnetic field to minimize the magnetic field on a portion of the shell to inhibit bead chain formation.

Claim 15

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: magnetic means, generating a magnetic field, for attracting and moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic field shaping means, coupled to said magnetic means, for attenuating the magnetic field generated by said magnetic means after the development zone so that the carrier beads release from said magnetic means after passing through the development zone; second magnetic means, generating a second magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone; second magnetic field shaping means, coupled to said second magnetic means for enhancing the second magnetic field generated by said second magnetic means in a direction toward the photoconductive surface and for attenuating the second magnetic field in the release zone so that substantially all the carrier beads moved to the release zone are released from said second magnetic means; and third magnetic field shaping means positioned proximate to said second magnetic means for attenuating the second magnetic field generated by said second magnetic means in an area after the release zone to release the carrier beads adhering to the magnetic means after passing through the release zone.

Claim 16

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: magnetic means, generating a magnetic field, for attracting and moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic field shaping means, coupled to said magnetic means, for attenuating the magnetic field generated by said magnetic means after the development zone so that the carrier beads release from said magnetic means after passing through the development zone; second magnetic means, generating a second magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone; second magnetic field shaping means, coupled to said second magnetic means for enhancing the second magnetic field generated by said second magnetic means in a direction toward the photoconductive surface and for attenuating the second magnetic field in the release zone so that substantially all the carrier beads moved to the release zone are released from said second magnetic means; and third magnetic field shaping means positioned proximate to said second magnetic means for attenuating the second magnetic field generated by said second magnetic means in an area after the release zone to release the carrier beads adhering to the magnetic means after passing through the release zone.

Claim 17

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic means, generating a magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone, said magnetic means includes a first and a second magnetic field sources positioned contiguous to one another and having substantially opposite polarity orientations for generating the magnetic field for attracting carrier beads proximate the photoconductive surface; and a housing in which said moving means and magnetic means are positioned.

Claim 18

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic means, generating a magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone, said magnetic means includes a first and a second magnetic field sources positioned contiguous to one another and having substantially opposite polarity orientations for generating the magnetic field for attracting carrier beads proximate the photoconductive surface; and a housing in which said moving means and magnetic means are positioned.

Claim 21

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic means, generating a magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone, said magnetic means includes a first and a second magnetic field source positioned adjacent one another and having substantially opposite polarity orientations for generating the magnetic field for attracting carrier beads proximate the photoconductive surface, wherein said magnetic means further includes a rotating outer shell positioned downstream from the development zone and proximate to the photoconductive surface and said first and second magnetic field source means are stationary permanent magnets disposed within said shell and a first and second ferromagnetic strip disposed generally on the sides of the first and second magnetic means opposite the photoconductive surface to enhance the magnetic field generated by the first and second permanent magnets in a direction toward the photoconductive surface and to attenuate the magnetic field emanating from said magnets in substantially all other radial directions; and a housing in which said moving means and magnetic means are positioned.

Claim 22

An apparatus for developing a latent image recorded on a moving photoconductive surface comprising: means for moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; magnetic means, generating a magnetic field, for attracting magnetic carrier beads proximate the photoconductive surface after passing through the development zone and moving such carrier beads to a release zone, said magnetic means includes a first and a second magnetic field source positioned adjacent one another and having substantially opposite polarity orientations for generating the magnetic field for attracting carrier beads proximate the photoconductive surface, wherein said magnetic means further includes a rotating outer shell positioned downstream from the development zone and proximate to the photoconductive surface and said first and second magnetic field source means are stationary permanent magnets disposed within said shell and a first and second ferromagnetic strip disposed generally on the sides of the first and second magnetic means opposite the photoconductive surface to enhance the magnetic field generated by the first and second permanent magnets in a direction toward the photoconductive surface and to attenuate the magnetic field emanating from said magnets in substantially all other radial directions; and a housing in which said moving means and magnetic means are positioned.

Claim 24

A method of developing a latent image recorded on a moving photoconductive surface, comprising the steps of: moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; positioning a cylindrical housing downstream from the development zone adjacent the photoconductive surface; generating, in a cleaning zone, a magnetic field from within the cylindrical housing, for attracting magnetic carrier beads adhering to the photoconductive surface after the photoconductive surface passes through the development zone, and moving such carrier beads to a release zone; decreasing the magnetic field intensity in the release zone so as to release substantially all of the carrier beads from the cylindrical housing; reducing the magnetic field generated in a region between the release zone and the cleaning zone to release the carrier beads in this region to limit carrier bead attraction and adhesion on the housing in all areas remote from the photoconductive surface; and cleaning the cylindrical housing wherein the step of moving includes rotating the cylindrical housing and the step of cleaning includes retaining carrier beads in a substantially constant position to act as a brush as the cylindrical housing rotates.

Claim 25

A method of developing a latent image recorded on a moving photoconductive surface, comprising the steps of: moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; positioning a cylindrical housing downstream from the development zone adjacent the photoconductive surface; generating, in a cleaning zone, a magnetic field from within the cylindrical housing, for attracting magnetic carrier beads adhering to the photoconductive surface after the photoconductive surface passes through the development zone, and moving such carrier beads to a release zone; decreasing the magnetic field intensity in the release zone so as to release substantially all of the carrier beads from the cylindrical housing; reducing the magnetic field generated in a region between the release zone and the cleaning zone to release the carrier beads in this region to limit carrier bead attraction and adhesion on the housing in all areas remote from the photoconductive surface; and cleaning the cylindrical housing wherein the step of moving includes rotating the cylindrical housing and the step of cleaning includes retaining carrier beads in a substantially constant position to act as a brush as the cylindrical housing rotates.

Claim 26

A method of developing a latent image recorded on a moving photoconductive comprising the steps of: moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; positioning a cylindrical housing downstream from the development zone adjacent the photoconductive surface; generating a magnetic field from within the housing; attracting magnetic carrier beads from the photoconductive surface proximate a portion of the housing; moving the attracted carrier beads to a release zone away from the photoconductive surface which includes rotating the housing; attenuating the magnetic field generated in the area of the housing away from the photoconductive surface to promote release of the attracted carrier beads in the release zone and to limit carrier bead attraction and adhesion on the housing in all areas away from the photoconductive surface; cleaning the housing which includes retaining carrier beads in a substantially constant position to act as a brush as the housing rotates; enhancing the magnet field generated in the area of the housing proximate the photoconductive surface to encourage migration of carrier beads from the photoconductive surface to the housing so that said step of shaping the generated magnetic field and said step of attenuating the generated magnetic field include inhibiting carrier beads from moving proximate the photoconductive surface when said cylindrical housing is rotated in a reverse angular direction.

Claim 27

A method of developing a latent image recorded on a moving photoconductive comprising the steps of: moving magnetic carrier beads having toner particles adhering triboelectrically thereto to a development zone proximate to the photoconductive surface so that the latent image attracts toner particles from the carrier beads thereto; positioning a cylindrical housing downstream from the development zone adjacent the photoconductive surface; generating a magnetic field from within the housing; attracting magnetic carrier beads from the photoconductive surface proximate a portion of the housing; moving the attracted carrier beads to a release zone away from the photoconductive surface which includes rotating the housing; attenuating the magnetic field generated in the area of the housing away from the photoconductive surface to promote release of the attracted carrier beads in the release zone and to limit carrier bead attraction and adhesion on the housing in all areas away from the photoconductive surface; cleaning the housing which includes retaining carrier beads in a substantially constant position to act as a brush as the housing rotates; enhancing the magnet field generated in the area of the housing proximate the photoconductive surface to encourage migration of carrier beads from the photoconductive surface to the housing so that said step of shaping the generated magnetic field and said step of attenuating the generated magnetic field include inhibiting carrier beads from moving proximate the photoconductive surface when said cylindrical housing is rotated in a reverse angular direction.