27
Calibration Offset Function
Outline of Function
In the controller, the relationship between the temperature T
detected by the sensor and the
display temperature of the operation panel D is expressed by the equation of the line which passes
the two points (T
0
, D
0
) and (T
s
, D
s
) shown in Fig.1.
D
S
T
0
T
S
D
0
y=ax+b
Fig. 1
Here, T
0
is the sensor detecting temperature when the
chamber
central temperature becomes the zero
adjusting temperature (normally room temperature is adopted)
D
0
at the time of no load, T
s
is the sensor detecting
temperature when the chamber central temperature becomes
the span adjustment temperature (normally working maximum
temperature is adopted) D
s
at the time of no load in the same
way.
As it is clear from the facts above, conforming of the chamber
central temperature and the display temperature is guaranteed
only when there is no load and at two points shown above.
In other words, it is possible for a temperature measured at a point in the chamber does not conform
to the display temperature of the operation panel at a voluntary temperature without load. This is the
function to move the line which passes above two points to the Y axis direction in parallel (increase
or decrease y intercept of the line). The parallel movement amount including a sign is defined as the
calibration offset. This function can conform the display temperature of the operation panel to the
measurement temperature of a voluntary point in the chamber at a voluntary temperature.
Calibration Offset Function
D
SV
D
PV
T
i
T
V
Parallel
movement
△
D
CAL
Fig. 2
In Fig. 2 D
sv
is a display temperature of the operation panel
nder the condition hat temperature in the chamber is constant
for a set temperature. It is natural to say that this value is equal
to the target set temperature. D
PV
is a measurement
temperature of a voluntary point in the chamber under this
condition. The difference between D
PV
and D
sv
including the
sign is defined as the calibration offset. Therefore offset is
shown as
Δ
D
D
D
b
PV
SV
=
−
Equation 1
In Fig. 2,
△
D
b
becomes the negative value since the target set
temperature D
SV
is larger than the actually measured
temperature D
PV
.
NOTE: Setting Tolerance of Calibration Offset
・
The setting tolerance of the calibration offset is
±
14
℃
for DE610. Initial off set value has
been set to 0
℃
when shipping.
Sensor detection temperature
Sensor detection temperature
Display temperature
(Controlled temperature)
Display temperature
(Controlled temperature)
