2BT
2-1-13
(4) Correcting the toner sensor control voltage
The toner sensor control voltage is corrected based on the absolute humidity and the total drive motor time so that the
toner density is kept constant regardless of the changes in humidity and the total drive motor time.
Toner sensor control voltage after correction = A + B + C
A: Toner sensor control voltage before correction (value set by maintenance item U131)
B: Correction data based on the absolute humidity
C: Correction data based on the total drive motor time
• Correction based on the absolute humidity
Figure 2-1-17 Absolute humidity computation block diagram
Figure 2-1-16 Correction based on the absolute humidity
a
: When the absolute humidity is between 0 and 12 g/m
3
, the correction data becomes a constant value of –5, which
decreases the toner sensor control voltage.
b
: When the absolute humidity is between 12 and 91 g/m
3
, the correction data is increased according to the rise in
absolute humidity.
c
: When the absolute humidity is 91 g/m
3
, the correction data becomes 0.
d
: When the absolute humidity is between 91 and 321 g/m
3
, the correction data is increased according to the rise in
absolute humidity, which increases the toner sensor control voltage.
e
: When the absolute humidity exceeds 321 g/m
3
, the correction data becomes a constant value of +8, which increases
the toner sensor control voltage.
Computing the absolute humidity
The humidity sensor (HUMSENS) converts the relative humidity detected by the humidity sensing element into a voltage
and sends it to the main PCB (MPCB). The main PCB (MPCB) computes the absolute humidity based on this HUMSENS
signal and the temperature (ETTH signal) detected by the external temperature thermistor (ETTH).
MPCB
HUMSENS
2
HUMSENS
1
5 V DC
CN9-1
CN9-2
CN9-3
CN9-4
4
3
ETTH
ETTH
HUMSPCB
GND
Humidity
sensing
element
+8
Correction data
12
91
321
Absolute humidity (g/m
3
)
0
0
-5
a
c
e
b
d
