This invention relates generally to an imaging apparatus, and is particularly, although not exclusively, concerned with a xerographic copying apparatus.  The invention is more especially concerned with an imaging apparatus having a process unit adapted to be removably mounted in a main assembly of the imaging apparatus, the process unit including an imaging member and optionally one or more process means. 
Such a process unit might comprises a xerographic process cassette of the kind which includes only the photoreceptor, or the photoreceptor and at least one of the process means such as a charge corotron, a development device, a transfer corotron, and a cleaning device.  An example of such a xerographic process cassette is described in U.S. Pat.  No.  3,985,436.  The use of a cassette of this kind enables the easy replacement of those parts of a xerographic machine which are most likely to deteriorate with use, especially the photoreceptor, but also the development and cleaning systems as well as the corotron wires.  A further advantage of containing the major xerographic process elements within a cassette is that interchangeable cassettes may be used in a given copying machine, to provide different development characteristics, or different coloured development.