Head Driver - Citizen CL-E720DT Technical Manual

Chapter 2 Operating Principles
2-2.
Operation of Control Parts
Forcible stop of the "SA PF Motor" at an abnormally high temperature:
If the temperature of the "SA PF Motor" reaches 105°C (221°F), the "SA PF Motor" stops.
In addition, an abnormally high temperature is monitored by the abnormally high temperature
detection circuit. (Refer to
temperature is detected with this circuit, the FPGA changes the level at pin N3 from "High" to
"Low" so that +24V DC (VMT) to the motor driver (U13) stops.

(2) Head driver

The head driver is incorporated in the "SA Head".
During printing, pin T6 (VHDON) of the FPGA (U5) goes to "High" level, Q16 and Q15 turn ON,
and +24V DC (VHD) is supplied to the "SA Head".
The print data is sent from the FPGA to the head driver via the buffer (U10) and the thermal
elements to be heated are selected.
The print data is sent from HDDATA0 to HDDATA2 in synchronization with HDCLK and latched
by nHDLAT. Then, the thermal elements are energized by the strobe pulse nHDSTB.
According to the print data received, the thermal head heats the thermal elements to transfer
melted ink dots to media or to print dots on thermal transfer paper. The width of energizing
pulse (nHDSTB pulse) changes according to the head temperature to keep the printing density
constant.
U5
FPGA
Head supply voltage ON
T6
VHDON
31_T6
R132
E5 VHCON
15_E5
R163
Thermal element abnormality check ON
D8 HDDATA2
84_D8
HDDATA1
C8
83_C8
B8
HDDATA0
82_B8
D6
nHDSTB
84_D6
A8 HDCLK
81_A8
C6
nHDLAT
83_C6
CL-E720DT
"2-2-4(4) PF motor temperature
L: Turns on Q15 to supply
power to the thermal head.
R129
Q16
DTC114EM
Q2
DTC114EM
When driving: +24V
When checking: +5V
U10
Buffer
2
1A1
4
1A2
6
1A3
8
1A4
11
2A1
13
2A2
15
2A3
17
2A4
1
/1G
19
/2G
74VHCT244
sensor".) If an abnormally high
+24V
R127
C148
TJ100F06M3L
Q15
VHD
+5.0V
DTA114EM
Q1
R52
D2
VHD
VHD
18
1Y1
16
1Y2
14
1Y3
12
1Y4
R53
L1
9
2Y1
7
2Y2
5
2Y3
3
2Y4
[SA Main PCB]
2-24
+3.3V
D1
HDRES
C87
Thermal element abnormality
check
J2
+5.0V
13
VDD
1-4,23-26
10
HDDAT3
14
HDDAT2
17
HDDAT1
nHDSTB
7,9,15
HDCLK
16
nHDLAT
18
5,6,8,11,12,
19,20,22
U1A
CPU
94
AN0
Thermal
Head
[SA Head]