Citizen CLP-621 Technical Manual page 42

2-2. Operation of Control Parts trol Parts
(4-3) Head driver (4-3) Head driver
The head driver is incorporated in the Head SA. The head driver is incorporated in the Head SA.
When printing, pin 116 (HDVON) of IC11 (Custom IC) goes to "High" level, and DTR1 and When printing, pin 116 (HDVON) of IC11 (Custom IC) goes to "High" level, and DTR1 and
TR1 turn ON. Thus +24V is supplied to the thermal head (Head SA). TR1 turn ON. Thus +24V is supplied to the thermal head (Head SA).
The print data is sent from the Custom IC (IC11) to the head driver to select the thermal The print data is sent from the Custom IC (IC11) to the head driver to select the thermal
elements to be heated. The data is sent via HD1 to 3, HDSTB, HDCLK and HDLAT lines elements to be heated. The data is sent via HD1 to 3, HDSTB, HDCLK and HDLAT lines
(pins 110, 111, 113, 108, 115 and 107 of IC11). (pins 110, 111, 113, 108, 115 and 107 of IC11).
According to the print data, the thermal head heats the thermal elements to print dots on According to the print data, the thermal head heats the thermal elements to print dots on
thermal transfer paper. The width of heating pulse will be changed according to the head thermal transfer paper. The width of heating pulse will be changed according to the head
temperature to keep the printing density constant. temperature to keep the printing density constant.
IC11
Custom IC
Head supply voltage ON/OFF
P167
116
HDVON
HDVON
P172
117
HCVON
HCVON
Thermal element abnormality check ON
110,
111,
113 HD1-3
HDATA1-3
HDSTB
108
HDSTB
115
HDCLK
HDCLK
107 HDLAT
HDLTH
IC1
CPU
PRT_MODE
174
P74
CLP-621 & CLP-631 CLP-621 & CLP-631
DTR1
P162
R77
DTC143EUA
P168
DTR2
P169
R82
DTC143EUA
When driving: +24V
When checking: +5V
P174-
IC21A
176
2-3
A1-3
P177
5
A4
P178
6
A5
P179
7
A6
Fixed to L.
Head power supply monitor
+24V
R76
VHEAD
P164
P163
TR1
2SJ553S
+5V
D2
R81
P170
P173
R84
TR2
2SJ647
Thermal element abnormality check
+3.3V
VHEAD
HDDAT1-3
16-18
B1-3
HDSTB1-3
15
B4
14
B5
13
B6
+3.3V
R159
2-30 2-30
+3.3V
D1
P166
R79
R78
VHEADMON
R80
+3.3V
D3
P171
R83
HEADRES
CN4
19
HDTHM1
1-4,23-26
10,14,17
7,9,15
16
HDCLK
18
HDLAT
5,6,8,11,12
20,22
27
[Main PCB]
IC1
CPU
9
ANI4
10
ANI5
Thermal
Head