Development system using electrically field dependent developer material

Claim 3

An apparatus according to claim 1, further including means for generating a constant electrical field between said first transporting means and the photoconductive surface with the alternating electrical field being superimposed thereover.

Claim 6

An apparatus according to claim 3, further including second means, spaced from said first transporing means, for transporting the developer material closely adjacent to the photoconductive surface so that the toner particles are attracted from the carrier granules to the image region forming a toner powder image thereon.

Claim 7

An apparatus according to claim 4, wherein said second transporting means includes: a second magnetic member; and a second non-magnetic tubular member.

Claim 8

An apparatus according to claim 3, wherein the charge on the photoconductive surface induces a charge on said first transporting means that biases said first transporting means to a floating constant electrical bias.

Claim 9

An apparatus according to claim 6, further including means for limiting the upper and lower values of the constant electrical bias applied on said first transporting means.

Claim 10

An electrophotographic printing machine of the type having an electrostatic latent image and a background region recorded on a photoconductive surface with the latent image being developed by a developer material comprising at least carrier granules and toner particles with the resistivity of the developer material varying continuously as a function of the electrical field applied thereto, wherein the improvement includes: first means for transporting the developer material closely adjacent to the photoconductive surface so that the toner particles are attracted from the carrier granules to the latent image forming a toner powder image thereon; means for generating an alternating electrical field between said first transporting means and the photoconductive surface with the alternating field having an amplitude sufficient to change the resistivity of the developer material to a more conductive state; and means for sensing the conductivity of the developer material and controlling the alternating electrical field generated by said generating means.

Claim 11

An electrophotographic printing machine of the type having an electrostatic latent image and a background region recorded on a photoconductive surface with the latent image being developed by a developer material comprising at least carrier granules and toner particles with the resistivity of the developer material varying continuously as a function of the electrical field applied thereto, wherein the improvement includes: first means for transporting the developer material closely adjacent to the photoconductive surface so that the toner particles are attracted from the carrier granules to the latent image forming a toner powder image thereon; means for generating an alternating electrical field between said first transporting means and the photoconductive surface with the alternating field having an amplitude sufficient to change the resistivity of the developer material to a more conductive state; and means for sensing the conductivity of the developer material and controlling the alternating electrical field generated by said generating means.

Claim 12

A printing machine according to claim 8, further including means for generating a constant electrical field between said first transporting means and the photoconductive surface with the alternating electrical field being superimposed thereover.

Claim 13

An electrophotographic printing machine of the type having an electrostatic latent image and a background region recorded on a photoconductive surface with the latent image being developed by a developer material comprising at least carrier granules and toner particles with the resistivity of the developer material varying continuously as a function of the electrical field applied thereto, wherein the improvement includes: first means for transporting the developer material closely adjacent to the photoconductive surface so that the toner particles are attracted from the carrier granules to the latent image forming a toner powder image thereon, said first transporting means comprising a first magnetic member and a first non-magnetic tubular member having said first magnetic member disposed interiorly thereof and spaced therefrom, said first tubular member and said first magnetic member having a relative angular velocity with respect to one another to advance the developer material closely adjacent to the photoconductive surface; means for generating an alternating electrical field between said first transporting means and the photoconductive surface with the alternating field having an amplitude sufficient to change the resistivity of the developer material to a more conductive state; means for generating a constant electrical field between said first transporting means and the photoconductive surface with the alternating electrical field being superimposed thereover; and means for sensing the conductivity of the developer material and controlling the alternating electrical field generated by said generating means.

Claim 14

An electrophotographic printing machine of the type having an electrostatic latent image and a background region recorded on a photoconductive surface with the latent image being developed by a developer material comprising at least carrier granules and toner particles with the resistivity of the developer material varying continuously as a function of the electrical field applied thereto, wherein the improvement includes: first means for transporting the developer material closely adjacent to the photoconductive surface so that the toner particles are attracted from the carrier granules to the latent image forming a toner powder image thereon, said first transporting means comprising a first magnetic member and a first non-magnetic tubular member having said first magnetic member disposed interiorly thereof and spaced therefrom, said first tubular member and said first magnetic member having a relative angular velocity with respect to one another to advance the developer material closely adjacent to the photoconductive surface; means for generating an alternating electrical field between said first transporting means and the photoconductive surface with the alternating field having an amplitude sufficient to change the resistivity of the developer material to a more conductive state; means for generating a constant electrical field between said first transporting means and the photoconductive surface with the alternating electrical field being superimposed thereover; and means for sensing the conductivity of the developer material and controlling the alternating electrical field generated by said generating means.

Claim 15

A printing machine according to claim 10, further including second means, spaced from said first transporting means, for transporting the developer material closely adjacent to the photoconductive surface so that the toner particles are attracted from the carrier granules to the image region forming a toner powder image thereon.

Claim 16

A printing machine according to claim 11, wherein said second transporting means includes: a second magnetic member; and a second non-magnetic tubular member.

Claim 17

A printing machine according to claim 10, wherein the charge on the photoconductive surface induces a charge on said first transporting means that biases said first transporting means to a floating constant electrical bias.

Claim 18

A printing machine according to claim 13, further including means for limiting the upper and lower values of the constant electrical bias applied on said first transporting means.