Paddle-wheel development system

Claim 1

An electrophotographic printing machine, including: a photoconductive member; corona generating means for charging said photoconductIve member to a substantially uniform level; exposure means for producing a light image which irradiates said photoconductive member to selectively discharge portions thereof recording an electrostatic latent image thereon of an original document to be reproduced; a housing member storing a supply of developer mix comprising carrier granules and toner particles; a hub member mounted rotatably in said housing member; a plurality of substantially equally spaced longitudinally extending vanes mounted fixedly on the circumferential surface of said hub member; drive means for rotating said hub member to form a flow of developer mix moving from a first region below said hub member to a second region above said hub member; a deflection plate disposed above said hub member and within said deflection plate having an undersurface extending transversely to said photoconductive member for intercepting and directing the flow of developer mix impacting thereon towards the electrostatic latent image recorded on said photoconductive member; a control plate having opposed end portions, said control plate being disposed in closely spaced relation to said photoconductive member with one end portion in an adjacent spaced relation to the portion of the undersurface of said deflection plate closest to said photoconductive member such that the developer mix directed by the undersurface of said deflection plate towards said photoconductive member cascades within the space defined by the control plate and the photoconductive member and over the electrostatic latent image recorded on said photoconductive member; and a recovery plate disposed adjacent the end portion of said control plate opposed from the undersurface of said deflection plate and arranged to direct the flow of unused developer mix and carrier granules into the first region of said housing member for subsequent re-use.