Ricoh FT6645 Manual page 65

OPTICS
90 mm
20 mm
A
[V]
ADS
Sensor
Output
For the first scanning of an original in ADS mode, the CPU starts sampling of
the ADS sensor output while exposing the ADS pattern at the scanner home
position. Then the CPU stores the maximum ADS sensor output as a
reference voltage. This means that every ADS check cycle, the first scanning
for the original, the ADS reference voltage is renewed by the latest exposure
light reflected by the ADS pattern.
In the full size mode, the CPU samples the ADS sensor output when the
scanner scans the original from 9.7 mm to 18 mm from the left scale edge.
The CPU takes the maximum ADS sensor output during the sampling period
and compares it with the ADS reference voltage to determine the proper
development bias voltage. (See development bias control section for details.)
The sampling length of ADS sensor output for the original differs depending
on the reproduction ratio because the scanner speed is different.
B
ADS
Original
Voltage
Peak hold
2-40
9.7
A = (mm)
M
M = 1.0 (m = 50 ~ 100)
m
M = (m = 101 ~ 200)
100
8.25
B = x 100 (mm)
m
m: reproduction ratio
(50 ~ 200)
23 April 1993