Specifications

21-8. CPM Control
•
The CPM (copies/minute) control is provided to keep good fusing
performance even in multi-copy cycles and with the system power sourced
from a single power outlet.
<What is CPM Control?>
•
As we noted earlier, only Upper Fusing Roller Main Heater Lamp H1 is
ON during a copy cycle. Because of that, the Fusing Roller surface
temperatures go down in a multi-copy cycle, resulting in degraded fusing
performance. The copier therefore estimates the fusing performance
based on the Fusing Roller surface temperature and, when the fusing
performance is considered to be degraded, it decreases the CPM by
25% in an attempt to recover good fusing performance.
(When the CPM is decreased, it provides a greater interval between
sheets of paper, which helps increase the Fusing Roller surface
temperature. This recovers the fusing performance. When good fusing
performance is recovered, the copier resumes the normal CPM.)
<CPM Control>
•
When the normal CPM is 60 copies/min., for example, and when the
copier determines that fusing performance has been degraded, it
reduces the CPM by 25% to 45 copies/min.
•
During the CPM control, the copier provides a greater interval between
scan motions and between sheets of paper, thereby increasing the
Fusing Roller temperature. (The system speed is not varied.)
•
The CPM control can be activated if a multi-copy cycle is run
immediately after the power has been turned ON in the morning (when
the Fusing Rollers remain cool). In this condition, only the surface of the
Lower Fusing Roller is heated by the heat which comes from the Upper
Fusing Roller. If multiple copies are made in such a condition, the CPM
control is activated. Since the inside of the Lower Fusing Roller remains
cool, it tries to take more heat from the Upper Fusing Roller, thus
decreasing the temperature of the Upper Fusing Roller. In times other
than early morning, however, the Lower Fusing Roller is heated by
Lower Fusing Roller Heater Lamp H3 from the inside and, even with a
multi-copy cycle, the CPM control is not readily activated. (For paper
with a large weight and size, however, the CPM control can be activated
even at times other than early morning.)
M-176