Ricoh FT4215, Service Training Manual

Page: 50 / 208

The method of control is different depending on whether the image density is
manually selected or the auto image density mode is selected.
The exposure lamp voltage consists of the following factors:
Exposure lamp voltage = Base exposure lamp voltage factor
(Manual or auto image density mode)
+
V
L
correction factor
+
Drum wear correction factor
+
Reproduction ratio correction factor
3.8.1 Base Lamp Voltage Factor in Manual Image Density Mode
Manual ID level 1 2 3 4 5 6 7
Exposure lamp data Vo –4 Vo Vo Vo Vo +4 Vo +8 Vo +12
The above table shows changes in the exposure lamp data in manual image
density mode.
SP48 sets the exposure lamp data for level 4 (Vo) of manual image density
mode. A value from 100 to 150 can be selected.
3.8.2 Base Lamp Voltage Factor in Auto Image Density Mode
In auto ID mode, the CPU selects the level 4 (Vo) exposure lamp data
regardless of the input from the auto image density sensor. When the auto
image density level is set to lighter in SP34, the exposure lamp data changes
to that of manual ID level 5 as shown below. When the auto image density
level is set to darker, the development bias 40 volts. Only the
development bias varies according to the input from the auto image density
sensor. (See page 2-31.)
Auto Image Density Level (SP34)
Auto image density level SP data (SP34) Exposure lamp data Development bias shift
Normal 0
Same as level 4
(Vo
±
0)
±
0 volts
Darker 1
Same as level 4
(Vo
±
0)
+40 volts
Lighter 2
Same as level 5
(Vo +4)
±
0 volts
Darker Lighter
STM 2-19 FT4220/4222