Hybrid development of electrostatic latent image

Claim 3

An apparatus as recited in claim 1, further including: first conveyor means for moving the developer mix from a first region to a second region for discharge into the feed chute; and second conveyor means for moving the developer mix from the first region to a third region for discharge into the retrieval zone where the developer mix interacts with the cloud of unused toner particles formed therein to return therewith to the first region for subsequent reuse.

Claim 4

An apparatus as recited in claim 2, wherein said first side wall is electrically biased to a DC potential ranging from about 150 volts to aBout 300 volts above the potential of said second side wall.

Claim 5

An apparatus as recited in claim 2, wherein said second side wall is electrically biased to a DC potential ranging from about 150 volts to about 300 volts above the potential of said first side wall.

Claim 6

An apparatus as recited in claim 2, further including means for imparting relative movement between the image bearing member and the cloud of toner particles moving toward the electrostatic latent image in the development zone.

Claim 7

An improved electrophotographic printing machine of the type wherein a corona generating device charges a photoconductive surface to a substantially uniform charge potential, and wherein an exposure mechanism produces a light image which selectively discharges the charged photoconductive surface forming an electrostatic latent image of an original document to be reproduced, wherein the improvement includes: a guide member; a pair of opposed, spaced, side walls defining a chute therebetween for feeding a developer mix comprising carrier granules and toner particles therethrough, said pair of side walls being disposed spaced from and intermediate said guide member and the image bearing member forming a development zone between the image bearing member and said first side wall opposed therefrom and a retrieval zone between said guide member and said second side wall opposed therefrom, said pair of side walls each having a perforated region extending substantially co-extensive with the latent image and adapted to prevent carrier granules from passing therethrough while permitting toner particles to pass therethrough; and means for applying a voltage to said pair of side walls so that initially said first side wall is electrically biased to a potential above said second side wall to move toner particles through the perforated region in said first side wall forming a cloud of toner particles in the development zone for developing the latent image, and after developing the latent image, said second side wall is electrically biased to a potential above said first side wall to move unused toner particles through the perforated region in said second side wall forming a cloud of unused toner particles in the retrieval zone for intermingling with developer mix passing therethrough.

Claim 8

An improved electrophotographic printing machine of the type wherein a corona generating device charges a photoconductive surface to a substantially uniform charge potential, and wherein an exposure mechanism produces a light image which selectively discharges the charged photoconductive surface forming an electrostatic latent image of an original document to be reproduced, wherein the improvement includes: a guide member; a pair of opposed, spaced, side walls defining a chute therebetween for feeding a developer mix comprising carrier granules and toner particles therethrough, said pair of side walls being disposed spaced from and intermediate said guide member and the image bearing member forming a development zone between the image bearing member and said first side wall opposed therefrom and a retrieval zone between said guide member and said second side wall opposed therefrom, said pair of side walls each having a perforated region extending substantially co-extensive with the latent image and adapted to prevent carrier granules from passing therethrough while permitting toner particles to pass therethrough; and means for applying a voltage to said pair of side walls so that initially said first side wall is electrically biased to a potential above said second side wall to move toner particles through the perforated region in said first side wall forming a cloud of toner particles in the development zone for developing the latent image, and after developing the latent image, said second side wall is electrically biased to a potential above said first side wall to move unused toner particles through the perforated region in said second side wall forming a cloud of unused toner particles in the retrieval zone for intermingling with developer mix passing therethrough.

Claim 9

A machine as recited in claim 6, further including; first conveyor means for moving the developer mix from a first region to a second region for discharge into the feed chute; and second conveyor means for moving the developer mix from the first region to a third region for discharge into the retrieval zone where the developer mix interacts with the cloud of unused toner particles formed therein to return therewith to the first region for subsequent reuse.

Claim 10

A machine as recited in claim 7 wherein said first side wall is electrically biased to a DC potential ranging from about 150 volts to about 300 volts above the potential of said second side wall.

Claim 11

A machine as recited in claim 7, wherein said second side wall is electrically biased to a DC potential ranging from about 150 volts to about 300 volts above the potential of said first side wall.

Claim 12

A machine as recited in claim 7, further including means for imparting relative movement between the photoconductive surface and the cloud of toner particles moving toward the electrostatic latent image in the development zone.