GB930072A - Xerographic developing apparatus - Google Patents

Abstract

930,072. Development of electrostatic charge images. RANK-XEROX Ltd. July 17, 1959, No. 24682/59. Class 98 (2). To avoid the defects known as " tearing " and " streaking " which occur in powder cloud development of xerographic or other electrostatic charge images, a developing apparatus is provided with two inlet slots located in an electrode element transversely of a development zone defined by the electrode element and a closely adjacent xerographic or other electrostatic image-bearing plate for flowing developer material into the development zone and an exhaust slot between the inlet slots for withdrawing excess developer from the development zone. Preferably, as shown, the apparatus comprises a manifold assembly having inlet slots 27 on opposite sides of an exhaust slot 35 with supplementary exhaust slots 42 flanking them. Powder cloud generators 28 feed the slots 27 via conduits 30 with if required the interposition of charging devices 29, e.g. a narrow tube through which electroscopic powder is passed in turbulent flow or a corona discharge device to obtain a more uniformly charged cloud and reduced pressure is applied over exhaust ducts 40, 45, dampers 47 (Fig. 1, not shown) being provided in each duct, the extracted developer being collected at 41. Rollers 12 carried by the frame of the developing apparatus allow the xerographic plate to move past the development electrode at a constant distance. The development electrode may be curved so as to conform to a xerographic drum surface.