Epson Stylus Color 640 Service Manual page 48

EPSON Stylus Color 440/640/740
See Figure 2-6 which shows the carriage mechanism.
Paper Feed Motor
Paper guide(Front)
Eject Roller
Figure 2-6. Carriage Mechanism (Top view)
The printhead, a core of the printing mechanism, is stored in the
carriage unit. When the adjustment lever is moved up and down, this
printhead maintains the printhead tilt in a flexible and adjustable
structure, using a tilt adjustment mechanism. Also, the parallelism
adjustment lever, mounted on the left and right sides of the carriage
guide shaft, adjusts parallelism between the platen and shaft when the
shaft is installed to the printer mechanism. After this adjustment is
completed, moving PG adjustment lever changes space between the
platen surface and the print head surface to one of two possibilities:
either 1.04 mm or 1.74mm. It is possible to vary the space between
platen surface and print head by rotating the shafts of the carriage guide
shaft which itself is decentralized, with the operation of PG lever. This is
the mechanism that the user can use to adjust the appropriate PG value
Chapter 2 Operating Principles
Carriage home position Sensor
PF Roller Timing Belt
Carriage Unit
Front Side
Rear Side
Parallelism
Adjust Lever
Carriage
Guide Shaft
according to the printing result or any other environmental conditions
such as paper curl.
Carriage lock mechanism is to prevent the carriage from being left at an
uncapped position for a long time because of vibration during the printer
Carriage Motor
transport or mishandling by the users. If the carriage is left uncapped for
long time, ink on the print head surface gradually becomes thick. As a
result, the nozzle will be unable to discharge ink.
To make matters worse, the holes (crater) of nozzle may be completely
clogged by the thick ink and it may not be able to return to the normal
condition just by cleaning operation. In order to prevent this, printer
goes to carriage lock state at the following conditions. (See the following
page.)


After Power OFF operation:
If the power is turned off on the way of printing or any other
performance, carriage lock will be performed in the end after
Fixing Bush
completing initialize operation.


After power ON operation:
After power is turned on and automatic P-On Cleaning is performed,
then carriage lock will be performed. P-On Cleaning is an automatic
head cleaning that is performed when the power is turned on. The
timer IC always calculates printer's power OFF time by the power of
lithium battery mounted on the C206 Main-B/C255/C256/C257 Main
board. P-on cleaning function automatically selects the cleaning
level according to the time which the printer is not in
used.


After Eject the paper:
After Load/Eject button is pressed and the paper is ejected, if the
data is not input, the printer performs carriage lock and goes to
standby state. However, if the paper is loaded to the printer inside
by Load/Eject button, the printer does not perform carriage lock
operation.
Revision A
48