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CF5001 Ver.1.0 Sep. 2003 DEVELOPING UNIT
2-27
II UNIT EXPLANATION
4.2.4 Developing bias control
A. Control path
The developing bias /Y, /M, /C and /K are supplied from the high voltage unit /1 (HV1) and controlled by the
printer control board (PRCB). Each developing bias is supplied with AC + DC to secure the uniformity of
developing.
4.2.5 Durability of the developer
A. Concept of the durability of the developer
The durability (deterioration) of the developer depends on the developing sleeve drive distance (the mov-
ing distance of the developing sleeve surface) in the developing unit.
The developing sleeve drive distance includes the distance at idle time (the time when the developing
sleeve does not perform the developing operation but rotates) and the job output pattern has a significant
effect on it.
The idle time has a significant effect on the drive distance in such cases as followings.
• Continuous copy count in a job: the rate of the idle time increases if the continuous copy count is
small.
• Switching the processing speed in a job: There is the idle time at switching the processing speed.
• Switching mode in ACS: There is the idle time at switching between the color mode and the black and
white mode.
• The color mode operation of the black and white original in ACS: There is the idle time for the color
developing sleeves when the black and white original is printed in the color mode.
• Double-sided operation: The operation is circulated in set of 4 sheets if the paper size is A4 If the copy
count is not an integral multiple of 4, for example if it is 9, only 1 sheet is circulated for the operation,
so the idle time is increased.
The relationship between the drive distance and actual copy/print count is affected by those output pat-
terns and it is hard to be defined. The count could be significantly different even if the drive distance is
same.
B. Specification of the durability of the developer
The durability of the drive distance for all color is specified as below.
Durability: 83,000km/color
As described in the previous section, the relationship between the drive distance and actual copy/print
count is hard to be defined; however, 83,000km of drive distance corresponds to 100,000 copies/prints if 5
sheets are printed intermittently in the A4 single-sided copy mode as defined for the maintenance.