16
AH-S22DP2
AH-S25DP2
AH-S32DP2
2. DESCRIPTION OF ODOR SENSOR
(1) Outline of the odor sensor
The odor sensor is used to cluster display during
operation. This odor sensor sensitively reacts to
the various air contaminations such as a volatile
organic solvent, fragrant materials and tabacco
burning gas. In the figure on the right, RS
indicates a sensor resistance, RL a load
resistance, VRS a sensor output voltage, and
VC a sensor power supply voltage. Their relation
is expressed in the following formula.
When the air contamination level increases, the
value of the sensor resistance RS drops, which
also lowers the value of the sensor output voltage.
While detecting contamination, the microcomputer
outputs the following pulse to the transistor Q8,
which drives the heater with the built-in odor sensor
using the pulse.
Basic circuit
Microcomputer
output
Microcomputer
input
Odor sensor
3
1
2
R
RL
C31
R41
R65
R64
R52
C32
Q7
Q8
R66
5V
S
V
RS
V
C
V
RS =
C
R
V
S
R
L +
R
S
512(
µ
s)
12.8(ms)
