Xerographic copying apparatus with intercepting means for carrier particles

Claim 1

In a xerographic copying apparatus wherein a moving endless cylindrical xerographic surface transports electrostatic latent images, a development unit including a magazine for a supply of intermixed toner and substantially spherical carrier particles, conveyor means for removing toner and carrier particles from the supply in said magazine and for dumping the thus removed particles onto said xerographic surface at a first level whereby at least some toner particles adhere to said xerographic surface to convert said latent images into powder images and the carrier particles descend by gravity along and some thereof adhere to said xerographic surface, and intercepting means for returning at least some of the dumped carrier particles into said magazine, said intercepting means comprising an intercepting element extending substantially radially of said xerographic surface and having an elastically deformable substantially strip-shaped portion extending close to but being spaced apart from said xerographic surface at a second level below said first level, said deformable portion of said intercepting element having an elongated edge defining with said xerographic surface a clearance whose width is between one-tenth and one-half the diameter of a carrier particle and the elasticity of said portion of said intercepting element being sufficient to enable said portion to yield to carrier particles which adhere to said xerographic surface with a predetermined force, said xerographic surface being arranged to travel in a direction from said first level to said second level so that the descending carrier particles travel toward said portion of said intercepting element by moving in the same direction as said xerographic surface and said intercepting means further comprising means for adjustably supporting said intercepting element so that the latter is movable relative to said xerograPhic surface.