Ricoh FT7770 Service Manual page 91

Bias Compensation Factors -
-
As discussed previously, the bias base level (Vl or V2) is set either by the
automatic image density system or by the operator through the image den-
sity keys.
The CPU increases
sate for the rest time between
which. affect drum sensitivity.
Rest Time Compensation (V3):
The drum sensitivity often drops slightly over the first few cycles of a copy
run. This is because the light from the exposure lamp fatigues the drum
slightly. The amount that it drops depends on the rest time between copy
runs; the longer the rest time, the greater the change.
This copier increases the bias at the beginning of each copy run to prevent
variations in the image density of the first few copies produced.
amount of total bias increase is shown in the above table..
When the main switch is turned on, the CPU will automatically select the
greater than three hours rest time compensation level.
-
the bias base level as necessary to compen-
copy runs and the drum temperature, both of
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April, '89
The