Patent ID: 6915087

Claim:
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, said media transport mechanism being an endless web having a seam and a plurality of frames separated by interframes, and a logic and control unit for controlling operation of said electrographic process modules for faithfully reproducing multi-color information on such media, a mechanism for providing image density control signals to said logic and control unit, said mechanism comprising: at least one densitometer for sensing an image density control patch on said media transport mechanism and producing signals representative of the density of said such image density control patch for said logic and control unit; and apparatus for enabling said electrographic process modules to generate/print respective uniform image density control patches periodically on said media transport mechanism where said patches can be read by said densitometer for providing signals to said logic and control unit for controlling print control parameters to maintain correct image density, said patches being generated/printed, one for each color electrographic process module, during each revolution of said media transport mechanism, in the same respective interframe following said seam on said media transport mechanism, and can selectively change said same respective interframe following seam to a different interframe.