Printer Mechanism Driver Circuits; Print Head Driver Circuit - Casio UP-250 Technical Manual

Printer Mechanism Driver Circuits

Print head driver circuit

The head driver signal is output from CPU (U5) pins 64 to 72. Receiving this drive signal,
transistor array QM1 and QM2 and transistor array QM3 turn On, Off, and drive the head.
Power supply time to the head is adjusted by the supplied power voltage. The CPU (U5)
changes the power voltage between analog and digital at AN0 (pin 7) and decides and controls
the head power supply time according to the internal time table.
To prevent damage to the head during excessive printing, a heat sensor has been installed in the
print head. An analog-digital conversion of the partial pressure difference between the heat
sensor and R18 is carried out in AN1 (pin 8) of the CPU (U5) and the temperature is calculated. If
the head is overheating or working improperly, the ERROR LED flashes.
R46
U5
7 V DTC
P60/ANO
8 HD TEMP
P61/AN1
5
AVCC
6
AVSS C31 C30
71
P47
67
P43
66
P42
70
P46
68
P44
69
P45
65
P41
72
P50
64
P40
+24DT +5V
D50
+5V
R8
C29
+
R45
C33
_
R19
+5V
C19
Q4
HEAD1
Q5
HEAD5
Q6
HEAD6
Q7
HEAD2
D40
Q12
HEAD4 D44
Q8
HEAD3
Q9
HEAD7
Q10
HEAD9
Q11
HEAD8
D45
Figure 2-25 Print head driver circuit
R18
D27 D28
D32
D38
QM1
1
RM3
7 8 8 9
5 6
3 4
6 7
1 2
D39
4 5
2 3
1
0
R20
Q13
D41
D42
QM2 1
RM4
7 8 8 9
5 6
3 4
6 7
1 2
D43
4 5
2 3
1
0
— 50 —
Print head unit
CN7
FG
1
# 2
2
# 4
3
# 6
4
# 8
5
COM (# 4.6.8 )
6
# 9
7
C0M ( # 1.2.9 )
8
THEM1
9
THEM2
10
COM (# 3.5.7 )
11
# 5
12
# 7
13
# 1
14
# 3
15
D7
+24A