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REV.-A
2.4.2.9 Printer Head Drive Circuit
The printer head drive circuit is divided into two main parts, the charging/discharging circuit and the
printer head voltage supply circuit.
<
Charging/Discharging Circuit>
The charging/discharging circuit is show in Figure 2-63. Its main functions are as follows .
• Discharge pulse:
The DCU generates pulses with a length of approximately 62us duration based on the PTS signal.
Signals internally generated in the DCU are provided from head data output terminal Hn. On printing,
the head output goes HIGH. This makes LZ 1008AD of the FET come on, and the electric charge of
the piezoelectric element discharges through the source terminal of the FET. The piezoelectric
element is usually charged with voltage Vh. The discharge time depends on the drive pulse which
the DCU generates .
• Charge pulse:
High pulses are provided from CHA and CHB of the DCU. The leading edge of the pulse makes
transistors QC
1
and QC2 turn on, then the piezoelectric element is charged by the Vh voltage which
comes through the resistor RCH and diode DCH. Charging and discharging wave forms are shown
in Figures 2-64 through 2-66.
R
CH
DCH
R
Vh
LZ1008AD
( 5C,6C.7C)
s
GH
, - - -
-- -"-- -..- -- -.,------ .------ - - - - - - - l
I
I
I
Vx
Vh
I
I
I
I
-~
r------,
I
I
'-_/
\
I
QC2
I
!
I
I
I
I
I
I
rr-Charge
I
I
I I
I I
+J
I
•
DpZD
T
Discharge
GH
G
H n
I------~---,
CHA
I
B
1 - - - - + - - - - - - . - - - - - ;
PHC
( 6 B)
Figure 2-64. Charge and Discharga Circuit
2-57
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