Head Driver - Citizen CL-S6621 Technical Manual

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(3) Head drive
The head driver is incorporated in the "SA, Head".
During printing, pin P16 (VHDON) of U14 (FPGA) goes "High" level, Q28 and Q26 turn ON,
and +24V (VHD) is supplied to the "SA, Head".
The print data is sent fromU14 (FPGA) to the head driver in the "SA, Head" to select the
thermal elements to be heated. The data is sent from HD1-HD4, nHDSTB, HDCLK and
nHDLAT signal lines (pins K15, K16, M16, M14, N16, N15 and P14 of U14).
According to the print data received, the "SA, Head" heats the thermal elements to print dots
on paper. The width of heating pulse will be changed according to the head temperature to
keep the printing density constant.
U14
FPGA
Head supply voltage ON/OFF
P16
B3_43
VHDON
P15 nHCVON
B3_42
Thermal element abnormality
check ON
HD1
K15
B3-26
HD2
K16
B3-27
M16
HD3
B3_35
M14 HD4
B3_33
N16 nHDSTB
B3_40
N15
HDCLK
B3_39
P14
nHDLAT
B3_41
R113
R115
Q28
DTC114EM
R117
+3.3V
Q1
DTA114EM
R52 L1
+24V
VHD
C122
Q26
2SJ505S
D2
R45
When checking:
+3.3V
+3.3V
2-33
Operation of Control Parts
Head power supply monitor: Not used.
+3.3V
D3
R48
R47
VHDMON
R49
C75
+3.3V
D1
R46
HDRES
VHD
C74
Thermal element
abnormality check
When printing:
+24V
J3
1-5
6-10
+3.3V
J5
17,21,22
R55
13
HD1
HD2 14
HD3
12
HD4
10
2,15
nHDSTB
HDCLK
16
nHDLAT
18
5,19,20
[SA, Main PCB]
U1A
CPU
9
ANI4
10
ANI5
VHD
GND
VDD
SA, Head
(Thermal
Head)
GND
CL-S6621