Developer housing with variable speed mixing for improving material life and performance

#This invention relates generally to an electrophotographic printing machine, and more particularly concerns an apparatus for controlling dispensing and mixing of marking particles into a developer unit.

#In a typical electrophotographic printing process, a photoconductive member is sensitized by charging its surface to a substantially uniform potential. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charge in the irradiated areas to record an electrostatic latent image on the photoconductive member. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are heated to permanently affix the powder image to the copy sheet.

#In most two component development processes, the developer/toner materials are at the mercy of the development housing design: auger configuration, sump geometry, magnetic brush roll size, magnetics design, roll and auger velocity, etc. to cause tribocharging of the toner against the carrier. The auger speeds and roll velocities are usually adjusted to the adequate flow balancing of the developer within the housing and developability that provides ample operating latitude, respectively.

#Other aspects of the present invention will become apparent as the following description proceeds and upon reference to the drawings, in which:

#FIG. 1 is a schematic elevational view depicting an illustrative electrophotographic printing machine incorporating the features of the present invention therein;

#FIG. 2 is a block diagram showing the control system used in the FIG. 1 printing machine;

#While the present invention will hereinafter be described in connection with a 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.

#For a general understanding of the features of the present invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to identify identical elements. FIG. 1 schematically depicts an electrophotographic printing machine incorporating the features of the present invention therein. It will become evident from the following discussion that the present invention may be employed in a wide variety of printing machines and is not specifically limited in its application to the particular embodiment depicted herein.

#Referring to FIG. 1 of the drawings, the electrophotographic printing machine employs a photoconductive belt 10. Belt 10 moves in the direction of arrow 12 to advance successive portions of the photoconductive surface sequentially through the various processing stations disposed about the path of movement thereof. Belt 10 is entrained about stripping roller 14, tensioning roller 16, and drive roller 18. Stripping roller 14 is mounted rotatably so as to rotate with belt 10. Tensioning roller 16 is resiliently urged against belt 10 to maintain belt 10 under the desired tension. Drive roller 18 is rotated by a motor coupled thereto by suitable means such as a belt drive.