Ricoh FT4227 Manual page 306

12 February 1992
6.5.2 ADS Data Correction
When in the ADS mode, original
background density is detected by the
ADS sensor board. According to the
original background ratio, the CPU
decides the appropriate development
bias voltage, as shown in the table at
right.
This is to prevent the original
background from appearing on copies.
The image and background density on
copies in the ADS mode are controlled
only by changing the development bias
voltage.
Development Bias Voltage
–400 V
–360 V
–320 V
–280 V
–240 V
–200 V
–160 V
Original Background
Ratio
Copy image and background density in the ADS mode can be selected from
three levels by SP mode #34.
The normal and darker settings have the same development bias voltage
table and the difference is made through the grid bias voltage (–50V). The
development bias voltage difference between the lighter and normal settings
is 40V.
ADS Data Correction
Original
Background
Ratio (%)
80~
75~79
70~74
60~69
45~59
0~44
70
60 75 80 100 (%)
45
2-51
DEVELOPMENT
Development Bias
Voltage
SP34: ADS Density
0: Normal
2: Lighter
1: Darker
–160V –200V
–200V –240V
–240V –280V
–280V –320V
–320V –360V
–360V –400V
Lighter
Normal/Darker