Tally T2265 SprintPro, Maintenance Manual

Page: 61 / 178

3.3.24
Theory of
Adjusting Print-
head Temperature
T2170 and T2280
only
The resistance of each coil of the printhead is proportional to its internal temperature.
The temperature will change almost linear to the measured coil resistance. The
resistance is measured continuously. Therefore it is possible to monitor the printhead
for highest performance but to protect it in case of overheating. This control system
must be adjusted once in case of changing printhead or at changing main electronic
(see chapter 6.3.1).
Used formula: R ϑ = R
t2
∗
(1 +
α ∗ ∆ϑ
)
ϑ
= Temperature
R = Resistance
α
= 3,95
∗
10
-3
1
K
∆ϑ
= Difference of Temperature (t
1
- t
2
)
t
1
= calculated temperature
t
2
= adjust temperature
Example: The printhead was adjusted by 20°C (t
2
)
.
The measured resistance was 5
Ω
(Rt
2
)
.
We want calculate the temperature (t
1
) at 7
Ω
(R
ϑ
).
(
R
ϑ
R
t2
)
– 1
t
1
= 102°C + 20°C
≈
122°C
∆ϑ
=
≈
102°C
α
Functional Description Electronic Functions
3-43