Microfield donor with continuously reversing microfields

Claim 1

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield doner member adated to transport toner particles on the outer face thereof to said latent image comprising, a dielectric layer sandwiched between and separating first conductive electrode means from second conductive film electrode means with said first electrode means being on the outer face of said dielectric layer and said film electrode means being on the inner face of said dielectric layer; said first electrode means being arranged in a pattern to set up microfields with said film electrode means for attracting said toner particles to said donor member; b. means to transport said donor member past a plurality of treating stations, said treating stations including: 1. a toner loading station including a supply of toner particles at which toner particles are contacted by and a layer of toner particles retained by said donor member in response to microfields set up between said electrode means and said film electrode; and 2. a developing station at which said layer of toner particles is presented in developing relation to an electrostatic latent image on an image-retaining member, and c. means adapted to maintain a potential difference between said electrodes sufficient to create voltage induced microfields extending into the region beyond the surface of said donor member and of a magnitude sufficient to attract to and hold toner particles on the surface of said donor member carrying said electrode means, said last defined means being further adapted to effect a voltage induced field reversal of said microfields at a time after toner loading of the donor, said reversal being effective to remove charges from the dielectric accrued during the time period of toner loading, said last defined means being further adapted, after charge removal, to return the microfields to their former direction.

Claim 2

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield doner member adated to transport toner particles on the outer face thereof to said latent image comprising, a dielectric layer sandwiched between and separating first conductive electrode means from second conductive film electrode means with said first electrode means being on the outer face of said dielectric layer and said film electrode means being on the inner face of said dielectric layer; said first electrode means being arranged in a pattern to set up microfields with said film electrode means for attracting said toner particles to said donor member; b. means to transport said donor member past a plurality of treating stations, said treating stations including: 1. a toner loading station including a supply of toner particles at which toner particles are contacted by and a layer of toner particles retained by said donor member in response to microfields set up between said electrode means and said film electrode; and 2. a developing station at which said layer of toner particles is presented in developing relation to an electrostatic latent image on an image-retaining member, and c. means adapted to maintain a potential difference between said electrodes sufficient to create voltage induced microfields extending into the region beyond the surface of said donor member and of a magnitude sufficient to attract to and hold toner particles on the surface of said donor member carrying said electrode means, said last defined means being further adapted to effect a voltage induced field reversal of said microfields at a time after toner loading of the donor, said reversal being effective to remove charges from the dielectric accrued during the time period of toner loading, said last defined means being further adapted, after charge removal, to return the microfields to their former direction.

Claim 5

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield donor member adapted to transport toner particles on the outer face thereof to said latent image comprising an endless dielectric layer sandwiched between and separating a plurality of mutually electrically isolated conductive screen pattern electrodes from a conductive continuous film electrode with said screen electrodes being on the outer face of said dielectric layer for attracting said toner particles to said donor member and said film electrode being on the inner face of said dielectric layer; b. means to transport the surface of said donor member past a plurality of treating stations, said treating stations including:

Claim 6

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield donor member adapted to transport toner particles on the outer face thereof to said latent image comprising an endless dielectric layer sandwiched between and separating a plurality of mutually electrically isolated conductive screen pattern electrodes from a conductive continuous film electrode with said screen electrodes being on the outer face of said dielectric layer for attracting said toner particles to said donor member and said film electrode being on the inner face of said dielectric layer; b. means to transport the surface of said donor member past a plurality of treating stations, said treating stations including:

Claim 13

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield donor member adapted to transport toner particles on the outer face thereof to said latent image comprising an endless dielectric layer sandwiched between and separating a continuous, electrically conductive, screen pattern electrode from a plurality of mutually electrically isolated conductive film electrodes with said screen electrode being on the outer face of said dielectric layer for attracting said toner particles to said donor member and said film electrodes being on the inner face of said dielectric layer; b. means to transport the surface of said donor member past a plurality of treating stations, said treating stations including:

Claim 14

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield donor member adapted to transport toner particles on the outer face thereof to said latent image comprising an endless dielectric layer sandwiched between and separating a continuous, electrically conductive, screen pattern electrode from a plurality of mutually electrically isolated conductive film electrodes with said screen electrode being on the outer face of said dielectric layer for attracting said toner particles to said donor member and said film electrodes being on the inner face of said dielectric layer; b. means to transport the surface of said donor member past a plurality of treating stations, said treating stations including:

Claim 15

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield donor member adapted to transport toner particles on the outer face thereof to said latent image comprising an endless dielectric layer sandwiched between and separating a plurality of mutually electrically isolated conductive screen pattern electrodes from a plurality of mutually electrically isolated conductive film electrodes with said screen electrodes being on the outer face of said dielectric layer for attracting said toner particles to said donor member and said film electrodes being on the inner face of said dielectirc layer; b. means to transport the surface of said donor member past a plurality of treating stations, said treating stations including:

Claim 16

An apparatus for developing an electrostatic latent image formed on the surface of an image-retaining member, said apparatus comprising: means for developing said latent image, said means including: a. a microfield donor member adapted to transport toner particles on the outer face thereof to said latent image comprising an endless dielectric layer sandwiched between and separating a plurality of mutually electrically isolated conductive screen pattern electrodes from a plurality of mutually electrically isolated conductive film electrodes with said screen electrodes being on the outer face of said dielectric layer for attracting said toner particles to said donor member and said film electrodes being on the inner face of said dielectirc layer; b. means to transport the surface of said donor member past a plurality of treating stations, said treating stations including: