Specifications

2.4 GRID VOLTAGE CORRECTION
There are two grid voltage correction factors. These correct for increases in
the drum residual voltage (Vr). The first such factor, Vr correction, is done
every 1,000 copies. Vr correction is based on the data of the drum counter
(SP #69) and the Vr correction ratio (L) (SP #67). The second factor, Vp
correction, corrects for changes in the photoconductor’s chargeability. (The
chargeability of a new OPC drum may change after installation, but this
stabilizes at around 2,000 copies.) Vp correction is based on the drum
counter. The counter resets to "0" when drum initial setting (SP mode #66) is
performed.
Both correction factors are applied to the copy process as follows:
1. Image area
Grid Voltage = –920 volts
+
Vr Correction Factor.
Vr Correction Factor
L Change of Grid Voltage
100 to 89 (%)
88 to 76 (%)
75 to 62 (%)
61 to 45 (%)
44 to 0 (%)
±0 (volts)
–40 (volts)
–80 (volts)
–120 (volts)
–160 (volts)
L = Vrp/Vsg x 100 (Vr correction ratio)
Vrp: ID sensor output for Vr correction pattern
Vsg: ID sensor output for bare drum
2. Non-image area
Grid Voltage = 0 volts (Fixed)
1 December 1990
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