4 8
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.
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.
In Fig. 2, D
SV
is a display temperature of the operation
panel under the condition that the 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 below.
In Fig. 2,
△
D
CAL
becomes the negative value since the target set temperature D
SV
is larger than the
actually measured temperature D
PV
. In order to conform the display temperature to the actually
measured temperature, let the controller to recognize that the temperature in the chamber differs
from the target set temperature by
△
D
CAL
.
N O T E : S e t t i n g T o l e r a n c e o f C a l i b r a t i o n O f f s e t
・
The calibration offset can be set within ±5% of the maximum working temperature of the oven.
(Therefore, the setting tolerance of the calibration offset is
±
19°C.)
・
Initial off set value has been set to 0°C when shipping.
D
S
Sensor detection temperature
Display temperature
(Controlled temperature)
T
0
T
S
D
0
y=ax+b
Fig. 1
D
SV
D
PV
T
i
T
V
Parallel movement
△
D
CAL
Display temperature
(Controlled temperature)
Sensor detection temperature
Fig. 2
△
D
C A L
＝
D
P V
−
D
S V
Equation 1
