Ricoh FT4215, Service Training Manual

Page: 48 / 208

3.7 EXPOSURE LAMP VOLTAGE CORRECTION
To maintain good copy quality, the exposure lamp voltage is changed by the
following:
•
V
L
correction
•
Drum wear correction
•
Reproduction ratio correction
3.7.1 V
L
Correction
The light intensity may decrease because of dust accumulated on the optics
parts. This may cause dirty backgrounds on copies. To compensate for this
phenomenon, V
L
correction is done as follows:
The CPU keeps track of the amount of time that the main switch is on. The
exposure lamp voltage increases at set intervals, which can be changed by
SP61 (see page 2-20).
3.7.2 Drum Wear Correction
During the drum’s life, the photoconductive surface of the drum becomes
worn by contact with the cleaning brush. This affects the drop of the drum
photosensitivity. This may cause dirty backgrounds on copies.
To compensate for this phenomenon, drum wear correction is made as
follows:
The CPU keeps track of the drum rotation time. The exposure lamp voltage
increases at set intervals (see page 2-21).
3.7.3 Reproduction Ratio Correction
To compensate for the change in the concentration of light on the drum, the
exposure lamp voltage increases depending on the selected reproduction
ratio (see page 2-21).
STM 2-17 FT4220/4222