Ricoh A085, Manual

Page: 266 / 617

1.4.2 V
L
Pattern Detection
V
L
pattern detection is done after V
R
pattern detection, but unlike V
R
pattern
detection it is done after the copy job is finished. This means after the drum
initial setting (SP mode #66), every 200 copies for the first 2,000 copies,
every 1,000 copies after exceeding 2,000 copies, and when the drum
temperature goes over 25°C under the V
R
data correction condition.
When V
L
pattern detection starts, the exposure lamp turns on, the main
motor stays, on together with other fan motors, to rotate the drum. The
charge corona, grid bias, all the blocks of the erase lamp, the pre-transfer
lamp, and the quenching lamp turn on.
After about one revolution of the drum, the appropriate blocks of the erase
lamp turn off and on to make a V
L
pattern (20 x 20 mm) on the drum surface.
The drum surface is developed with non-image area bias for both the bare
drum and V
L
pattern.
The V sensor checks the reflectivity of the bare drum (Vlg) and that of the V
L
pattern (Vlp). The CPU calculates the ratio between Vlp and Vlg (Vlp/Vlg).
The V
L
pattern is made 4 times with 150 mm distance between each pattern.
The CPU takes the average of Vlp/Vlg (=Vdat).
V
L
Pattern
150 mm
20 mm
20 mm
Main SW on
V
R
data
correction
done ?
copy
interval ?
V
R
pattern detection
Drum Temp.
> 25°C
V
L
pattern detection
Vdat = Vlp/Vlg
Is copy
Job completed ?
N
N
N
N
Y
Y
Y
Y
Programmed
Det
a
il
ed
Descriptions
12 February 1992 PROCESS CONTROL
2-11