Epson Stylus Color 740 Service Manual

EPSON Stylus COLOR 440, 640, and 740 Chapter 2 Operating Principles
36
2.1.1 Printhead
The printhead of the St
y
lus COLOR 440, 640, and 740 combines the
black and CMY
(
C
y
an, Ma
g
enta, Yellow
)
heads in one unit. As shown
below, the nozzle confi
g
urations are different for each model:

St
y
lus COLOR 440:
Black Nozzle: 64 nozzles
(
90 dpi x 2 rows sta
gg
ered
)
CMY Nozzle: 21 nozzles per color
(
90 dpi x 1 row
)

St
y
lus COLOR 640:
Black Nozzle: 64 nozzles
(
90 dpi x 2 rows sta
gg
ered
)
CMY Nozzle: 32 nozzles per color
(
90 dpi x 1 row
)

St
y
lus COLOR 740:
Black Nozzle: 144 nozzles
(
120 dpi x 3 rows sta
gg
ered
)
CMY Nozzle: 48 nozzles per color
(
120 dpi x 1 row
The St
y
lus COLOR 640 and 740 print at the hi
g
hest resolution
(
720 x
1440 dpi
)
, while the St
y
lus Color 440 prints at 720 x 720 dpi.
The printhead uses an on-demand MACH-t
y
pe ink deliver
y
s
y
stem.
Refer to Fi
g
ure 1-1, Fi
g
ure 1-2, and Fi
g
ure 1-3 for the nozzle
confi
g
uration. In order to correct manufacturin
g
variations in the piezo
elements used for e
j
ectin
g
ink from the nozzles,
y
ou must input the
head volta
g
e ID to the printer whenever
y
ou replace the printhead, main
board, or printer mechanism. The head volta
g
e ID is marked on the
side of the printhead, and is stored in the EEPROM on the printer’s
main board. You can input the ID to the printer b
y
usin
g
the ad
j
ustment
pro
g
ram described in “Usin
g
the Ad
j
ustment Pro
g
ram” in Chapter 5,
Adjustments
.
Printing Process
In Fi
g
ure 2-2, the ink cartrid
g
e sensor detects the presence of the ink
cartrid
g
e; note that the sensor’s position differs between models. After
ink flows out of the cartrid
g
e throu
g
h the needle, it passes throu
g
h a
filter. The filter prevents dust or dirt from clo
gg
in
g
the ink nozzles and
causin
g
missin
g
dots or ink deflection. The ink cavit
y
then stores the ink
until it is read
y
to be dischar
g
ed. This is accomplished b
y
piezo electric
elements
(
PZTs
)
. In response to si
g
nals from the driver on the main
board, the PZTs compress the top of the ink cavit
y
, causin
g
ink to e
j
ect
throu
g
h the nozzle plate on the bottom of the printhead.
Figure 2-2. Printhead Sectional Drawing
Ink C artridge S ensor
(Stylus C O LO R 440,640)
Ink C artridge S ensor
(Stylus C O LO R 740)
(In k C a rtrid g e )
N o z z le S e le c to r B o a rd
N eedle
N
ozzle P late
PZT
In k C a v ity
F ilte r

Epson Stylus Color 740 Specifications

General

Brand	Epson
Model	Stylus Color 740
Category	Printer
Language	English