BIXOLON SMP690, User Manual, Page: 27 / 60

Rev. 1.04 - 27 -
SMP690/691
5-9 Peak Current
Most cases in the following equation can be used to calculate the peak current of the
printer head operation. Pay special attention to voltage drop of the circuit.
N
х
Vset
I
P
= ------------------
Rave
Rave
:
Average resistance (176
Ω
)
I
P
: Peak current (A)
N : Number of dots running simultaneously
Vset: Head drive voltage
5-10 Head Pulse Width Control
5-10-1 Voltage pulse width
Control the pulse width depending on the head operation voltage in order to maintain
consistent printing quality. The head pulse width can be obtained using the following
equation.
(N x R
COM
+ Rave + R
IC
)
2
T
o
= E
o
х
---------------------------------------------
Vset
2
х
Rave
T
O
: Pulse width (ms)
E
O
: Supply energy (mJ/dot)
R
COM
: Common resistance (0.05
Ω
)
R
IC
: Driver saturation resistance (15
Ω
)
5-10-2 Pulse width calibration for temperature change
Temperature change can be processed by reading the value of thermister installed in the
thermal head. It is recommended to adjust the pulse width and energy depending on the
changes of the installation ambient temperature and thermal head temperature. Stop
printing if the detected temperature is over 60
℃
. Pulse width should be calculated using
the following equation
(25-T
X
)
х
C
T
on
= T
25
х
{ 1+ -------------------}
230
T
on
: Pulse width at the operating temperature
T
25
: Pulse width at 25
℃
T
X
: Operating temperature
C : Thermal paper coefficients
(C=1 if Hansol 65 GSM is used)