Xerox 4890 Product Reference page 78

USER CONSIDERATIONS
Mode switching
Xerographic mode persistence
5-10
state. During printing this adjustment occurs automatically. In
some cases the operator is requested to initiate PQA.
A request for PQA can occur when:
The color developer housing has been changed. The dry
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ink must be evenly distributed within the housing, and its
electrostatic charge must be properly set.
A color developer housing has been unused for over 16
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hours. If a dry ink remains unused for a long period of time,
its electrostatic charge may dissipate. PQA is required to
reset the proper charge state.
The operator may initiate a PQA without waiting to be instructed
to do so by the system. This allows you to schedule PQA as part
of your daily routine. For example, you could schedule PQA to
be run at the beginning of the first shift of the day. As a
standard procedure, you should run PQA after the color housings
have been idle for longer than 16 hours. Routine or regularly run
PQAs reduce the number of system-initiated requests for PQA
and therefore reduce the number of delays and interruptions to
print jobs.
The 4890 has two modes of operation:
Black mode, using only the black primary color
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Highlight color mode, using black plus a highlight primary
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color.
Pages requiring highlight color must be printed in highlight color
mode. Pages requiring black ink only may be printed in either
black mode or highlight color mode. Shifts from one mode to
the other are handled automatically by the 4890 system
controller. It is possible to have a mode switch during a job.
For example, if highlight color is required for the first two pages
in a several hundred page job, the controller selects highlight
color mode, then shifts to black mode for the remaining pages.
The point when the controller actually makes the shift to black
mode depends upon the xerographic mode persistence (XMP)
setting in effect. XMP is a feature that allows you a measure of
control over mode switching.
The 4890 system controller selects and sets the xerographic
mode persistence (XMP) by evaluating the demands of the
printing job. It first determines what primary ink colors are
needed for a page and, if highlight color is required, it shifts into
highlight color mode. The controller then uses the current XMP
setting to determine the maximum number of black-only pages
to print in highlight mode. If that number of pages is printed
without encountering a page requiring highlight color, a shift-to-
black mode will occur.You can set XMP to control how long the
highlight color mode remains in effect.
The XMP system parameter instructs the controller on what basis
the xerographic mode is to be switched back to black mode:
Never (always stay in highlight color mode),
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After a specified number of pages (minimum 50 pages)
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Report (Output statement of DJDE).
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XEROX 4890 HIGHLIGHT COLOR LPS PRODUCT REFERENCE