Epson M-T123, Designer'S Manual

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A
M-T123
Designer’s Guide
(STANDARD)
3 2
1.3 Example Power Supply Connection Circuit for the Thermal Print Head
1) The figure below shows an example circuit for the power supply connection circuit. Note that this
circuit protects the thermal print head by following the specifications to prevent malfunction of the
print head due to noise and to prevent damage to the print head IC due to surge voltage.
Print head terminal
voltage V
H
VH
VH
VH
VH
6
[User side] [Printer side]
VC
C1
+
C2
GND
GND
VD
Power supply for
print head Vp
Device which turns
the power supply
for the head on/off
VH
VH
7
8
23
24
25
20
13
14
GND
15
GND
16
GND
17
GND
18
Figure 1.3.1 Example Power Supply Connection Circuit for the Thermal Print Head
The table below shows parts used in Figure 1.3.1, Example Power Supply Circuit for the Thermal Print
Head.
Table 1.3.1 Parts Used in Example Power Supply Circuit for the Thermal Print Head
Part No. Type Specifications
C1 Electrolytic capacitor
47
µ
F, 50 V
C2 Ceramic capacitor
0.1
µ
F, 50 V
2) To prevent electrolytic corrosion of the print head electrode (see inside the dotted box line in Figure
1.3.1), a device that turns the power supply for the head on/off must be installed. This device should
have a low voltage loss.
3) Since there may be some cases that the print head is energized continuously by a CPU malfunction,
be sure to turn the power off if there is a CPU malfunction. Otherwise, it may cause a fire or smoke.
4) If the capacitor C1 is installed, design the circuitry so that its charging voltage must go down to the
ground level within 20 seconds after turning off the power to the print head.