The presently described embodiments relate to improving system
productivity where maintenance purge routines are required through use of
a digital front end (DFE) job scheduler. This approach utilizes knowledge
of future jobs to maximize productivity. So, even if a low coverage area
job is being processed, and a purge routine is scheduled, the purge
routine may be avoided. This is achieved by projecting the system
evolution over a future time horizon and determining the schedule of
toner purge events (a non productive dead cycle) to minimize a cost
function that penalizes the purge event (dead cycling and material loss
should be minimized) and the deviation of average toner resident time in
the sump from some desired set point of range. In this regard, knowledge
that a high coverage area job is downstream and average toner residient
time may be advantageously used to effectively perform the purge itself
while in productive mode. The system gains knowledge of whether low
coverage area jobs or high coverage area jobs are pending by using
information stored within the print job file (e.g., a page description
language job file). For example, a page description language (PDL) file
typically includes information on the area coverage trajectory over time.
This will allow a system to generate a predictive model which can
constantly recalculate statistics based on knowledge of currently running
jobs, new jobs or a change in customer criteria.