Development system

#This invention relates generally to an electrostatographic printing machine, and more particularly concerns an improved development system for use therein.

#In the process of electrostatographic printing, an electrostatic latent charge pattern is recorded and reproduced in viewable form. The field of electrostatography includes electrophotographic and electrographic printing. Electrophotographic printing employs electromagnetic radiation to form the electrostatic latent image or charge pattern. Electrographic printing forms the latent image without the aid of electromagnetic radiation. In both of the foregoing processes, the latent image must be rendered viewable, i.e. developed with particles. Hereinafter electrophotographic printing will be discussed as an illustrative embodiment of the foregoing.

#An electrophotographic printing machine employs a photoconductive member which is charged to a substantially uniform level to sensitize its surface. The charged portion of the photoconductive member is exposed to a light image of the original document being reproduced. As a consequence of the exposure, the charge is selectively dissipated in the irradiated areas in accordance with the light intensity reaching the surface. This records an electrostatic latent image on the photoconductive surface. The latent image recorded on the photoconductive surface is developed by bringing a developer mix into contact therewith.

#Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

#FIG. 1 is a schematic perspective view of an electrophotographic printing machine embodying the features of the present invention therein;

#FIG. 2 is a sectional elevational view of the development system of the present invention employed in the FIG. 1 printing machine; and

#While the present invention will hereinafter be described in connection with the preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

#A general understanding of the electrophotographic printing machine, in which the features of the present invention may be incorporated, may be had by referring to the drawings, wherein like reference numerals have been used throughout to designate like elements. FIG. 1 illustrates the various components of a multi-color electrophotographic printing machine. As in all printing machines of the type illustrated, a light image of an original document is projected onto a sensitized photoconductive surface forming an electrostatic latent image thereon. The latent image is developed with toner particles forming a toner powder image. The powder image is subsequently transferred to a sheet of support material and then permanently affixed thereto.

#With continued reference to FIG. 1, the printing machine utilizes a photoconductive member comprising a drum 10 having a photoconductive surface 12 entrained thereabout. Photoconductive surface 12, preferably, is formed from a material having a relatively panchromatic response to white light. A suitable type of photoconductive material is described in U.S. Pat. No. 3,655,377 issued to Sechak in 1972. Drum 10 rotates in the direction of arrow 14 to move photoconductive surface 12 sequentially through a series of processing stations.