Electrostatic screen printing and cleaning

Claim 2

In an electrostatic apparatus utilizing carrier particles and toner particles, a base electrode, means for depositing carrier particles and toner particles on to said base electrode, a cleaning electrode, means for transporting said carrier particles and said toner particles from said base electrode to said cleaning electrode, and means for causing said toner particles to adhere to said cleaning electrode and said carrier particles to be expelled from said cleaning electrode.

Claim 3

In an electrostatic apparatus as defined in claim 1 wherein said base electrode comprises a conductive belt, and said carrier particles are formed of conductive material.

Claim 4

In an electrostatic apparatus as defined in claim 1 wherein said cleaning electrode has a continuous surface of conductive material.

Claim 5

In an electrostatic apparatus as defined in claim 1 wherein said base electrode and said cleaning electrode each have a continuous surface and each are comprised of conductive material, said transporting means comprising a source of electrical energy, said base electrode being connected to one side of said source and said cleaning electrode being connected to the other side of said source for creating an electric field between said base electrode and said cleaning electrode.

Claim 6

In an electrostatic apparatus as defined in claim 1 wherein said cleaning electrode comprises a rotatable drum having at least the surface thereof being formed of conductive material, and means for removing toner particles from said surface.

Claim 7

In an electrostatic apparatus as defined in claim 1 wherein said means for depositing said carrier particles and toner particles on said base electrode comprises a magnetic drum and a magnetic roller, said magnetic roller having a more intense magnetic field than said magnetic drum, said base electrode comprising an endless belt, said belt having a portion thereof disposed between said magnetic drum and said magnetic roller, whereby said carrier particles and said toner particles are attracted from said magnetic drum toward said magnetic roller and deposited upon said endless belt.

Claim 8

In an apparatus as defined in claim 5 wherein an inclined plane extends downwardly from said endless belt toward said magnetic drum, whereby particles cascading down said inclined plane are directed toward said magnetic drum and attracted by its magnetic field.

Claim 9

In an electrostatic printing apparatus, a base electrode and a stencil screen, a developer comprising toner particles and conductive carrier particles, means for depositing said developer upon said base electrode, means for establishing an electric field between said base electrode and said stencIl screen for causing said carrier particles to oscillate within said electric field between said base electrode and said stencil screen, and apparatus means for causing toner particles to be returned from said stencil screen to said base electrode subsequent to a printing operation, said apparatus means comprising means for reversing the direction of said electric field established between said base electrode and said stencil screen for oscillating said carrier particles between said base electrode and said stencil screen for dislodging toner particles from said screen whereby the reversed direction of said electric field causes the dislodged toner particles to be attracted toward said base electrode.

Claim 10

In an electrostatic printing apparatus, a base electrode and a stencil screen, a developer comprising toner particles and conductive carrier particles, means for depositing said developer upon said base electrode, means for establishing an electric field between said base electrode and said stencIl screen for causing said carrier particles to oscillate within said electric field between said base electrode and said stencil screen, and apparatus means for causing toner particles to be returned from said stencil screen to said base electrode subsequent to a printing operation, said apparatus means comprising means for reversing the direction of said electric field established between said base electrode and said stencil screen for oscillating said carrier particles between said base electrode and said stencil screen for dislodging toner particles from said screen whereby the reversed direction of said electric field causes the dislodged toner particles to be attracted toward said base electrode.

Claim 11

In an electrostatic printing apparatus as defined in claim 8, said apparatus means being further defined as including means for reducing the field intensity of said electric field.

Claim 12

In an electrostatic printing apparatus, a base electrode and a stencil screen, a developer comprising electrically non-conductive toner particles and electrically conductive carrier particles, means for depositing said developer upon siad base electrode, means for establishing an electric field between said base electrode and said stencil screen for causing said carrier particles to oscillate within said electric field between said base electrode and said stencil screen, and apparatus means for causing toner particles to be returned from said stencil screen to said base electrode subsequent to a printing operation.

Claim 13

In an electrostatic printing apparatus, a base electrode and a stencil screen, a developer comprising electrically non-conductive toner particles and electrically conductive carrier particles, means for depositing said developer upon siad base electrode, means for establishing an electric field between said base electrode and said stencil screen for causing said carrier particles to oscillate within said electric field between said base electrode and said stencil screen, and apparatus means for causing toner particles to be returned from said stencil screen to said base electrode subsequent to a printing operation.

Claim 14

In an electrostatic printing apparatus as defined in claim 10 wherein said stencil screen has openings therein for defining a pattern; and said openings, said toner particles and said carrier particles being of respective sizes for allowing said toner particles to pass through said openings and precluding passage of said carrier particles through said openings.

Claim 15

In an electrostatic printing apparatus as defined in claim 10 wherein said apparatus means comprises means for reversing the direction of said electric field and means for agitating said stencil screen for dislodging toner particles therefrom whereby the dislodged toner particles are carried by said reversed electric field to said base electrode.

Claim 16

In an electrostatic printing apparatus as defined in claim 12 wherein said stencil screen is agitated by bombardment of carrier particles against said stencil screen.

Claim 17

In an electrostatic screen printing apparatus, first means for cleaning electrically non-conductive toner particles from a stencil screen subsequent to a printing operation, said first means including said stencil screen and a base electrode, a voltage source for establishing an electric field between said stencil screen and said base electrode, and second means for causing toner particles to be freed from said stencil screen and attracted toward said base electrode.

Claim 18

In an electrostatic screen printing apparatus, first means for cleaning electrically non-conductive toner particles from a stencil screen subsequent to a printing operation, said first means including said stencil screen and a base electrode, a voltage source for establishing an electric field between said stencil screen and said base electrode, and second means for causing toner particles to be freed from said stencil screen and attracted toward said base electrode.

Claim 19

In an electrostatic screen printing apparatus as defined in claim 14 wherein said second means includes a third means for agitating said stencil screen for dislodging toner particles therefrom.

Claim 20

Apparatus as in claim 15 wherein said third means comprises a plurality of electrically conductive particles for bombarding said stencil screen.