5.4.4 Vr Correction Factor
As the OPC drum is used, drum residual voltage (Vr) gradually increases. Vr
correction compensates for residual voltage on the drum. Vr correction is
done every 1,000 copies based on the data of the drum counter (SP69) and
the Vr correction ratio (L) (SP67). The following chart shows how the bias
voltage changes depending on the Vr correction ratio (L).
Vr Correction Factor
L
Change of bias 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)
NOTE: L = Vrp/Vsg x 100 (Vr correction ratio)
Vrp: ID sensor output for Vr correction pattern
Vsg: ID sensor output for bare drum
When the Vr correction is made every 1,000 copies, all blocks of erase lamps
turn on and the development bias becomes 0 volt to develop the Vr
correction pattern.
STM
2-33
FT4220/4222
Summary of Contents for FT4215
Page 1: ...FT4220 4222 4215 SERVICE TRAINING MANUAL ...
Page 12: ...SECTION 1 OVERALL MACHINE INFORMATION ...
Page 28: ...8 AC POWER AND DC POWER DISTRIBUTION FT4220 4222 1 16 STM ...
Page 31: ...SECTION 2 DETAILED SECTION DESCRIPTIONS ...
Page 114: ...SECTION 3 DOCUMENT FEEDER ...
Page 138: ...SECTION 4 SORTER ...
Page 157: ...SECTION 5 DUPLEX ...