Ricoh FT5233 Service Manual page 64

12 February 1992
4.7.2 Reproduction Ratio Correction
Lamp
Reproduction
Correction
Ratio (%)
Voltage
±0V
50~120
121~140 +1V
141~160 +2V
161~180 +4V
181~200 +6V
In the reduction and enlargement modes the light path is longer than the full
size mode. The light intensity for a unit square in enlargement mode is less
than that in the full size mode and that in the reduction mode is more.
To compensate, the exposure lamp voltage is increased in the enlargement
mode according to the reproduction ratios, as shown in the above table.
The compensation in the reduction mode is done by the light shading
mechanism (see 4. 3. 2).
4.7.3 V Correction
L
Lamp
VL level
Correction
(%)
Voltage
151~ –1V
±0V
101~150
~100 +1V
According to the result of the V
is corrected as shown in the above table.
When the V level (= Vdat/Vref X 100) corresponds to the level less than
L
100%, meaning that the intensity of the light reaching the drum surface is
less than the initial condition, the lamp voltage is increased by 1V. If the V
level is within the range of 101 and 150%, no correction is applied because
the light intensity is strong enough. If the V
lamp voltage is decreased by 1V to compensate for too intense light.
This voltage correction is applied to the exposure lamp voltage till the next V
pattern detection. This means that the lamp voltage increases more and
more by 1V steps if the optics section gets dirty.
Lamp Correction
Voltage
+6
+4
+2
+1
0
50
121
Reproduction Ratio
NOTE:
Lamp correction voltage is added to the
previous correction voltage.
pattern detection, the exposure lamp voltage
L
level is more than 150%, the
L
2-35
200
141 161 181
OPTICS
(%)
L
L