Ricoh FT5233 Service Manual page 40

12 February 1992
1.4.2 V Pattern Detection
L
Main SW on
V data
R
N
correction
done ?
Y
N
Drum Temp.
> 25°C
Y
V pattern detection
R
N
Job completed ?
V pattern detection
L
Vdat = Vlp/Vlg
V pattern detection is done after V
L
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
When V pattern detection starts, the exposure lamp turns on, the main
L
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
The drum surface is developed with non-image area bias for both the bare
drum and V pattern.
L
The V sensor checks the reflectivity of the bare drum (Vlg) and that of the V
pattern (Vlp). The CPU calculates the ratio between Vlp and Vlg (Vlp/Vlg).
The V pattern is made 4 times with 150 mm distance between each pattern.
L
The CPU takes the average of Vlp/Vlg (=Vdat).
Programmed
copy
interval ?
Y
Is copy
Y
pattern detection, but unlike V
R
pattern (20 x 20 mm) on the drum surface.
L
2-11
PROCESS CONTROL
N
V Pattern
L
data correction condition.
R
150 mm
20 mm
20 mm
pattern
R
L