Method and apparatus for developing electrostatic latent images

A method of developing a latent electrostatic charge image on a photoconductive member by liquid toner comprising the steps of presenting to said member along a uniform area thereof a thin viscous highly dense layer of electroscopic toner particles in a suitable carrier liquid and transferring only latent image developing portions of said layer to the photoconductive member under the sole influence of the electric field strength of said latent image, said layer is electrically deposited on an applicator roller from a liquid suspension of toner and the applicator roller surface is spaced from the photoconductive surface by a virtual displacement distance no greater than the thickness of the viscous layer, the transfer occurring upon impression of said roller upon said surface through said layer, wherein said latent image is developed at said virtual displacement.

A method of developing a latent electrostatic charge image on a photoconductive member by liquid toner comprising the steps of presenting to said member along a uniform area thereof a thin viscous highly dense layer of electroscopic toner particles in a suitable carrier liquid and transferring only latent image developing portions of said layer to the photoconductive member under the sole influence of the electric field strength of said latent image, said layer being electroplated on an applicator roller from a liquid suspension of toner and the applicator roller is mounted to bring its circumferential surface spaced from the photoconductive surface a distance no greater than the thickness of the viscous layer to define a virtual displacement therebetween, the transfer occurring upon virtual displacement impression of said roller upon said surface through said layer, wherein said latent image is developed at said virtual displacement.

A method of developing a latent electrostatic charge image on a photoconductive member by a liquid toner applicator means, said method comprising the steps of establishing a virtual displacement between said photoconductive member and the liquid toner applicator means;

• presenting to said member along a uniform area at said virtual displacement thereof a thin viscous highly dense layer of electroscopic toner particles in an insulating toner medium and transferring through said virtual displacement only latent image developing portions of said layer to the photoconductive member under the sole influence of the electric field strength of said latent image, wherein said latent image is developed at said virtual displacement, said insulating toner medium being present in said layer to the degree necessary only to maintain the separated integrity of the toner particles forming said layer.

Apparatus for developing electrostatic latent charge images formed upon the photoconductive coating of an electrophotographic member and comprising:

• a canister cartridge having a floor, side and end walls and an open top, said canister cartridge adapted to contain a suspension of electroscopic toner particles in an insulating liquid medium, an applicator roller mounted for rotation within said canister cartridge and disposed to extend partially through the open top thereof, means for forming a thin, highly dense, viscous toner particle layer on the circumferential surface of said applicator roller and means rotating said applicator roller relative to the photoconductive surface close thereto but spaced therefrom a distance at most equal to the thickness of said viscous layer and transferring only latent image developing portions of said layer to said photoconductive surface during passage under the sole influence of the electric field strength of said electrostatic latent charge image, said applicator roller being mounted to establish a virtual displacement between the circumferential surface thereof and the photoconductive coating defining a development station at said virtual displacement whereby development occurs only at said virtual displacement.

Apparatus for developing electrostatic latent charge images formed upon the photoconductive coating of an electrophotographic member and comprising:

• a canister cartridge having a floor, side and end walls and an oen top, said canister cartridge adapted to contain a suspension of electroscopic toner particles in an insulating liquid medium, an applicator roller mounted for rotation within said canister cartridge and disposed to extend partially through the open top thereof, means for electrodepositing a thin, highly dense, viscous particle layer upon the circumferential surface of said applicator roller and means rotating said applicator roller relative to the photoconductive surface close thereto but spaced therefrom a distance at most equal to the thickness of said viscous layer to define a virtual displacement transferring only a latent image developing portion of said layer to said photoconductive surface during passage under the sole influence of the electric field strength of said electrostatic latent charge image to effect development at said virtual displacement.

Apparatus for developing electrostatic latent charge images formed upon the photoconductive coating of an electrophotographic member and comprising:

• a canister cartridge having a floor, side and end walls and an open top, said canister cartridge adapted to contain a suspension of electroscopic toner particles in an insulating liquid medium, an applicator roller mounted for rotation within said canister cartridge and disposed to extend partially through the open top thereof, means for forming a thin, highly dense, viscous toner particle layer on the circumferential surface of said applicator roller and means rotating said applicator roller relative to the photoconductive surface close thereto but spaced therefrom a distance at most equal to the thickness of said viscous layer to define a virtual displacement and transferring only latent image developing portions of said layer to said photoconductive surface during passage under the sole influence of the electric field strength of said electrostatic latent charge image, the amount of residual liquid medium in said viscous layer is sufficient only to maintain the separate integrity of each particle in said layer.

An electrophotographic imaging apparatus which includes a latent electrostatic charge image carrier, a charging station, an exposure station, a toning station and a transfer station;

• said toning station comprising a canister for holding a suspension of toner particles in an insulating medium, roller means arranged mounted for rotation within the canister, means for electrodepositing a thin highly dense viscous layer of toner particles upon said roller means and means for driving said roller means to present said deposited layer to said latent electrostatic charge image carrier at said toning station along a virtual displacement, the dimension of said virtual displacement approximating the thickness of the thin highly dense viscous layer whereby to effect transfer of only latent image developing portions of said viscous layer to said latent electrostatic charge image carrier at said virtual displacement.

Apparatus for developing electrostatic latent charge images formed upon the photoconductive coating of an electrohotographic member and comprising:

• a canister cartridge having a floor, side and end walls and an open top, said canister cartridge adapted to contain a suspension of electroscopic toner particles in an insulating liquid medium, an applicator roller mounted for rotation within said canister cartridge and disposed to extend partially through the open top thereof, means for forming a thin, highly dense, viscous toner particle layer on the circumferential surface of said applicator roller and means rotating said applicator roller relative to the photoconductive surface close thereto but spaced therefrom a distance at most equal to the thickness of said viscous layer to define a virtual displacement and transferring only latent image developing portions of said layer to said photoconductive surface during passage under the sole influence of the electric field strength of said electrostatic latent charge image and extraction means are disposed proximate said photoconductive surface and downstream of said applicator roller and virtual displacement, said extraction means being operative upon said surface subsequent to the transfer of toner particles to said surface to remove therefrom excess toner particles and any liquid transferred therewith.

Apparatus for developing electrostatic latent charge images formed upon the photoconductive coating of an electrophotographic member and comprising:

• a canister cartridge having a floor, side and end walls and an open top, said canister cartridge adapted to contain a suspension of electroscopic toner particles in an insulating liquid medium, an applicator roller mounted for roration within said canister cartridge and disposed to extend partially through the open top thereof, means for forming a thin, highly dense, viscous toner particle layer on the circumferential surface of said applicator roller and means rotating said applicator roller relative to the photoconductive surface close thereto but spaced therefrom a distance at most equal to the thickness of said viscous layer to define a virtual displacement and transferring portions of said layer at said virtual displacement to said photoconductive surface during passage under the sole influence of the electric field strength of said electrostatic latent charge image, and a plate electrode disposed electrically insulated from but proximate to the floor of said canister cartridge, a source of voltage, means for connecting said plate electrode to said source of voltage and means for applying high energy voltage bursts to said plate electrode for dispersing any agglomerated toner particles present into said toner suspension.