Developing apparatus

Claim 2

Apparatus for developing a latent electrostatic image that is recorded upon an image retaining plate including a magnetic brush forming unit for establishing a brush like structure of developer material which is placed in operative communication with the image retaining plate within a developing zone, means to move a flow of developer material into the developing zone, a development electrode positioned within the development zone and being arranged to extend into the region wherein the developer material moves into said developing zone, a conductive member complementary with the extended portion of the developing electrode and positioned adjacent thereto within the entrance region to the developing zone and being arranged to cooperate with the development electrode to provide a substantially enclosed flow path through which developer material passes as it enters said developing zone, and means to electrically bias the electrode and the conductive member to substantially the same potential to provide an electrically neutral flow path through which the developer material enters the developing zone.

Claim 3

The apparatus of claim 1 further including switching means being operatively associated with said electrical biasing means to change the bias level applied to said electrode and to said conductive member.

Claim 4

The apparatus of claim 2 wherein said switching means is arranged to bias said development electRode and said conductive member to a first potential being greater than the background potential recorded on the plate when said switching means is in a first operative position and to a potential at or below the first potential when in a second operative position.

Claim 5

The apparatus of claim 1 wherein said development electrode comprises the non-permeable cylindrical roll member substantially enclosing the brush forming unit and being arranged such that the outer surface of the roll passes sequentially through a supply of developing material and the flux field of the brush forming unit.

Claim 6

In a magnetic brush developing apparatus of the type having a stationary brush forming magnet positioned adjacent to a moving image retaining plate and having means for transporting permeable developer material through the flux field of said magnet to create a brush-like structure of developing material that is in operative communication with the moving plate within a developing zone, the apparatus further including a development electrode constructed of a conductive non-permeable material being positioned in the developing zone and extending therefrom into the regions wherein the developing material enters and leaves the developing zone, a pair of conductive members each of which is positioned adjacent to an extended portion of the development electrode within the entrance and exit regions to the developing zone, being arranged to cooperate with said electrode to provide a flow path through which the developer material moves as it enters and leaves said developing zone, and biasing means to electrically bias said development electrode and each of the conductive members to substantially the same potential.

Claim 7

In a magnetic brush developing apparatus of the type having a stationary brush forming magnet positioned adjacent to a moving image retaining plate and having means for transporting permeable developer material through the flux field of said magnet to create a brush-like structure of developing material that is in operative communication with the moving plate within a developing zone, the apparatus further including a development electrode constructed of a conductive non-permeable material being positioned in the developing zone and extending therefrom into the regions wherein the developing material enters and leaves the developing zone, a pair of conductive members each of which is positioned adjacent to an extended portion of the development electrode within the entrance and exit regions to the developing zone, being arranged to cooperate with said electrode to provide a flow path through which the developer material moves as it enters and leaves said developing zone, and biasing means to electrically bias said development electrode and each of the conductive members to substantially the same potential.

Claim 8

The apparatus of claim 5 further including switching means operatively associated with said biasing means and being arranged to vary the bias potential on said development electrode and on said conductive members.

Claim 9

The apparatus of claim 6 wherein said switching means is arranged to vary the bias potential between a first potential which is greater than the background potential recorded on the image retaining plate and a second potential which is variable up to said first potential.

Claim 10

The apparatus of claim 7 wherein said first potential is between 50 and 100 volts above the background potential recorded on the plate.

Claim 11

The apparatus of claim 5 further including a lifting means positioned adjacent to the exit to said development zone and being adapted to elevate the developing material leaving the developing zone to a height substantially above the development zone.

Claim 12

The apparatus of claim 9 wherein said lifting means has a magnetic flux generating mechanism associated therewith for magnetically coupling said lifting means to the brush forming means whereby the developer material leaving the developing zone is magnetically transferred to said lifting means.

Claim 13

The apparatus of claim 10 wherein said lifting means is electrically coupled to said biasing means and placed at a potential substantially the same as the potential on said development electrode and said conductive members.

Claim 14

In a magnetic brush developing apparatus having a conductive non-permeable roller rotatably supported about a stationary brush forming magnetic structure, the roller being arranged to move a quantity of developer material through the magnetic flux field of the magnetic structure to create a brush like structure of developer material for developing an image retaining plate within a developing zone, the apparatus further including a lifting mechanism positioned adjacent to the region wherein developer material leaves the developing zone, said lifting mechanism having a magnetic means magnetically coupled to the developing apparatus whereby developer material leaving the developing zone is transferred to said lifting mechanism and transported to an elevation substantially above the developing zone, a pair of conductive members, one of saiD members positioned adjacent to the conductive non-permeable roller at the entrance to the development zone and said other member being positioned adjacent to the lifting means at the exit to said development zone whereby the developer entrance and exit regions to the developing zone are substantially enclosed, biasing means to electrically bias said conductive members, the conductive non-permeable roller and the lifting mechanism to substantially the same potential.

Claim 15

In a magnetic brush developing apparatus having a conductive non-permeable roller rotatably supported about a stationary brush forming magnetic structure, the roller being arranged to move a quantity of developer material through the magnetic flux field of the magnetic structure to create a brush like structure of developer material for developing an image retaining plate within a developing zone, the apparatus further including a lifting mechanism positioned adjacent to the region wherein developer material leaves the developing zone, said lifting mechanism having a magnetic means magnetically coupled to the developing apparatus whereby developer material leaving the developing zone is transferred to said lifting mechanism and transported to an elevation substantially above the developing zone, a pair of conductive members, one of saiD members positioned adjacent to the conductive non-permeable roller at the entrance to the development zone and said other member being positioned adjacent to the lifting means at the exit to said development zone whereby the developer entrance and exit regions to the developing zone are substantially enclosed, biasing means to electrically bias said conductive members, the conductive non-permeable roller and the lifting mechanism to substantially the same potential.

Claim 16

The apparatus of claim 12 further including switching means operatively associated with said biasing means and being arranged to vary the bias potential applied to the bias members.

Claim 17

The apparatus of claim 12 wherein said switching means is arranged to vary the bias potential between a first potential which is greater than the background potential recorded on the image retaining plate and a second potential which is variable up to said first potential.

Claim 18

The apparatus of claim 14 wherein said first potential is between 50 and 100 volts above the background potential recorded on the plate.

Claim 19

In a magnetic brush developing apparatus having a development electrode in a development zone and means to bias the electrode to a predetermined potential, the improvement wherein said apparatus further includes: means for providing an electrically neutral flow path through which developer material enters and leaves the development zone; conductive members arranged to cooperate with the development electrode to provide substantially enclosed flow paths through which the developer material passes as it enters and leaves the developing zone, and means to bias the conductive members to substantially the same polarity and potential as the development electrode.

Claim 20

In a magnetic brush developing apparatus having a development electrode in a development zone and means to bias the electrode to a predetermined potential, the improvement wherein said apparatus further includes: means for providing an electrically neutral flow path through which developer material enters and leaves the development zone; conductive members arranged to cooperate with the development electrode to provide substantially enclosed flow paths through which the developer material passes as it enters and leaves the developing zone, and means to bias the conductive members to substantially the same polarity and potential as the development electrode.

Claim 21

The apparatus of claim 16 further including means to change the bias upon said developing electrode and said conductive members.