Epson Stylus Color 740 Service Manual

EPSON Stylus COLOR 440, 640, and 740 Chapter 2 Operating Principles
61
Common Voltage Drive Circuit
The common volta
g
e drive circuit
g
enerates the volta
g
e waveform for
drivin
g
the PZTs
(
piezo-electric elements
)
in the printhead. The
g
ate
arra
y
outputs si
g
nals to the common drive IC
(
H8D2813, H8D2889, or
CXA20995 in the St
y
lus COLOR 440, 640, or 740
)
. The common drive
IC then drives 2 power transistors arran
g
ed in a push-pull confi
g
uration
(
see Fi
g
ures 2-32 throu
g
h 2-34 below
)
. The waveform produced b
y
these transistors is called the “trapezoidal” waveform, because it looks
like an irre
g
ularl
y
shaped trapezoid with a small step in the middle. The
trapezoidal waveform can be observed an
y
time the printer is on,
whether somethin
g
is bein
g
printed or not.
Table 2-9. Common Voltage Driver Characteristics
Nozzle Selector Drive Circuit
The nozzle selector IC is located in the printhead itself. Data from the
g
ate arra
y
is sent seriall
y
to the IC and latched in one-b
y
te units. After
the IC interprets the data, it sends print si
g
nals in parallel to the
appropriate PZTs. These si
g
nals are s
y
nchronized with the trapezoidal
waveform produced b
y
the common volta
g
e driver, and determine
which PZTs
g
et actuated b
y
the common volta
g
e in each c
y
cle.
Fi
g
ure 2-32, Fi
g
ure 2-33, and Fi
g
ure 2-34 show printhead driver
dia
g
rams for each printer.
Figure 2-32. Head Drive Circuit for Stylus COLOR 440
Items Characteristics
Drive voltage 42 volts
±
5%
Waveform appears after voltage rises above 5 volts.
Final drive element
(power transistors)
2S
C3746
(PNP)
2S
A1469
(NPN)
Operation during reset Both transistors are off.
H8D2813(IC6)
XOVM
CTB
COM
DTB
GND
GND
25
1
20
+5
F1
+42
22
23
VHV
VHV
+5
GND
GND
GND
GND
GND
GND
VDD
15
14
12
10
8
6
4
COM
COM
COM
19
21
20
GND2
GND2
GND2
16
18
17
E05B44(IC2)
VHCTL
2
4
6
199
CCO
LAT
SI1
SI2
CLK
NCHG
BCO
THM
1
2
5
9
7
11
3
13
200
198
SW7
SW8
90
LP
99
100
BIEN
BHSO
YCMHSO
97
96
YCMIEN
ICLK
BCHCLK
/NCHG
93
92
89
TMP95C061(IC1)
AN0
20
CN8
CHG
KC1
ND1
ND2
MD1
MD2
Data
CLK
/STB
/CLR
VRF
VK
CHG
KC1
ND1
ND2
MD1
MD2
Data
CLK
/STB
/CLR
VRF
VK
VHCTL
Vcc

Epson Stylus Color 740 Specifications

General

Brand	Epson
Model	Stylus Color 740
Category	Printer
Language	English