Formation of uniform density patches in an electrographic reproduction apparatus for process control

Abstract

In an electrographic reproduction apparatus having a media transport mechanism for transporting media into operative association with a plurality of different color electrographic process modules, a mechanism for providing image density control signals to the logic and control unit. At least one densitometer is provided for sensing image density control patches on the media transport mechanism and producing signals representative of the density of the such image for the logic and control unit. The electrographic process modules are enabled to generate/print respectively uniform image density control patches periodically on the media transport mechanism where the patches can be read by the densitometer for providing signals to the logic and control unit for controlling print control parameters to maintain correct image density, the patches being generated/printed, one for each color, during each revolution of the media transport mechanism, in the same respective interframe following the seam on the media transport mechanism.