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Chapter 2 Operating Principles
2-2.
Operation of Control Parts
CL-E720DT
2-20
J2
[SA Head]
HDTHM2
19
TMPHD
AN4
98
Thermistor
C91
R55
R54
+3.3V
CPU
U1A
U7A
BA2903SFVM
-
+
3
2
1
+3.3V
R34
+3.3V
R32
C49
R33
N3
K1
33_N3
21_K1
FPGA
nTMPERR
nTMPENB
TEMP ERROR Detection
L: Error
U5
TMPHD
[SA Main PCB]
Head Temperature
Sensor
21
HDTHM1
(3)
Head temperature sensor
The head temperature sensor is used to detect the temperature of the “SA Head”. This sensor
is a thermistor incorporated in the “SA Head”.
Since the resistance of the thermistor changes according to the temperature change, the
voltage at pin 98 (TMPHD) of the CPU (U1A) changes accordingly. The CPU senses the
voltage at pin 98 (TMPHD) to detect the head temperature. According to the temperature of the
“SA Head”, the CPU controls the energizing pulse width applied to the thermal elements to
keep the printing density constant.
Printing operation when the “SA Head” temperature rises:
When the temperature of the “SA Head” rises to 70
C (158
F), printing will stop after printing
the current label. In this case, the LED on the operation panel blinks in red and the LCD
displays “Alarm Head Hot”. When the temperature of the “SA Head” falls below 60
C (140
F),
the LED and LCD returns to normal display, and printing automatically resumes.
* If the temperature of the “SA Head” is too low, the LED on the operation panel blinks in red
and the LCD displays “Error Head Cold”. In this case, the printer goes off-line.
Abnormally high temperature detection:
To protect the “SA Head” from being damaged, an abnormally high temperature detection
circuit is provided. If the temperature of the “SA Head” exceeds a set temperature limit, the
LED on the operation panel blinks in red and the LCD displays “Error System Fail”, and the
printer goes off-line. To recover from the error status, turn OFF the printer once and then turn it
ON.
A reference voltage, i.e., an allowable temperature limit, is applied to pin 2 of the comparator
(U7A), while the sensor output voltage (TMPHD) from the head temperature sensor is applied
to pin 3.
60
C
(140
F)
70
C
(158
F)
Printing
(Stop)
Printing
Printing
(Stops)
Summary of Contents for CL-E720DT
Page 1: ...Technical Manual CL E720DT Direct Thermal Barcode Label Printer ...
Page 5: ...Chapter 1 Specifications 1 1 CL E720DT CHAPTER 1 SPECIFICATIONS ...
Page 15: ...Chapter 2 Operating Principles 2 1 CL E720DT CHAPTER 2 OPERATING PRINCIPLES ...
Page 75: ...Chapter 3 Disassembly and Maintenance 3 1 CL E720DT CHAPTER 3 DISASSEMBLY AND MAINTENANCE ...
Page 119: ...Chapter 4 Troubleshooting 4 1 CL E720DT CHAPTER 4 TROUBLESHOOTING ...
Page 131: ...Chapter 5 Parts Lists 5 1 CL E720DT CHAPTER 5 PARTS LISTS ...
Page 159: ...Chapter 5 Parts Lists 5 29 CL E720DT DRAWING NO 7 Unit Opepane Rev 0 ...
Page 162: ...Chapter 5 Parts Lists CL E720DT 5 32 DRAWING NO 8 Accessories Rev 0 3 2 1 1 1 2 1 3 ...
Page 164: ...Chapter 6 Circuit Diagrams 6 1 CL E720DT CHAPTER 6 CIRCUIT DIAGRAMS ...
Page 183: ...Appendices AP 1 CL E720DT APPENDICES ...
Page 186: ...Appendices A Mounting Diagrams CL E720DT AP 4 2 Solder side ...