Ricoh FT 4015, Service Manual

Page: 27 / 229

4) V
L
Correction 1 Factor
The light intensity may decrease because of dust accumulated on the optics
parts. Additionally, the drum sensitivity gradually decreases during the drum’s
life. This may cause dirty background on copies. To compensate for this, V
L
corrections 1 and 2 are done.
The exposure lamp voltage is increased by two steps at the set copy count
interval (a step is +2.0 V for 230 V machines, and +1 V for 120 V machines).
The table below shows the relationship between the SP setting and the
interval.
SP62 Setting V
L
Correction Interval
0 2 steps/8,000 copies
1 2 steps/6,000 copies
2 2 steps/4,000 copies
3 2 steps/2,000 copies
4 2 steps/1,000 copies
5 No correction
(Default setting: 2)
V
L
correction 1 compensates for the decrease of drum sensitivity and the
decrease in reflectivity of the 4th, 5th, and 6th mirrors due to dust.
5) V
L
Correction 2 Factor
V
L
correction 2 compensates for dust on the lens and mirrors 1 to 3, but is
independent of the drum condition.
The ADS sensor receives the light reflected through the 1st, 2nd and 3rd
mirrors from the white plate located under the middle part of the left scale.
The photosensor circuit converts this light intensity to a voltage, and the CPU
stores this in memory as the white plate reference voltage. This is done every
time SP56 (ADS reference voltage adjustment) is done, before sampling
starts for the ADS sensor adjustment.
Every 500 copies, the machine reads the intensity of light reflected from the
white plate and compares it with the white plate reference voltage.
If the measured voltage difference is more than 0.1 volt, +2 steps will be
added to the exposure lamp setting as the V
L
correction 2 factor.
The sum of V
L
correction factors 1 and 2 cannot 40 steps.
V
L
correction factors 1 and 2 are automatically reset every time the light
intensity is adjusted with SP48. (SP56 must be done immediately after SP48;
see Service Remarks for details.)
Det
ailed
Descript
ions
20 December 1996 OPTICS
2-13