Copy Image Control - Ricoh A156 Service Manual

1.2 COPY IMAGE CONTROL

Copy image control adjusts the development bias and exposure lamp
voltage to take account of the reproduction ratio and image density. The
image density is either selected by the user or detected automatically.
1.2.1 Manual ID Correction
If the user selects the image density manually, the selected manual ID level
affects the exposure lamp voltage and the development bias as follows.
- Exposure Lamp Voltage -
As the ID level increases from 1 to 7, the exposure lamp voltage is increased
as shown in the following table.
Table 1. Exposure lamp voltage control by manual ID level
ID Level Lamp Voltage
1
2
3
4
5 Vexp +1.5 V
6 Vexp +4.0 V
7 Vexp +6.0 V
Vexp = Lamp voltage selected with SP4-001. It can be between 50 and 75
V. It is factory set, and varies from copier to copier.
- Development Bias -
The greater the negative voltage, the paler the image on the drum. However,
the development bias is adjusted only at the extreme light and dark ends of
the manual ID range.
Table 2. Development bias control by manual ID level
ID Level Development Bias
1
2
3
4
5
6
7 SP2-201-002 (see below)
Note: The base development bias voltage is -240 Volts.
A156/A160/A162
Vexp –4.0 V
Vexp –3.0 V
Vexp –1.5 V
Vexp ±0.0 V
+80 V
±0 V
±0 V
±0 V
±0 V
±0 V
2-8 STM