Epson FX 1170 Service Manual - Page 44

Printer Mechanism Operation, Mechanism - ink

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2.1 Printer Mechanism Operation REV.-A This section describes the printer mechanism of the FX-870/l 170 printer and explains how the printer works. The FX-870/l 170 printer mechanism features a 9-pin impact dot printhead for seriaI Printin9. It has four main parts: 1) the printhead mechanism, 2) the carriage movement mechanism, 3) the paper feed mechanism, and 4) the ribbon advance mechanism. Each of these is described below. 2.1.1 Printhead Mechanism The printhead mechanism consists of the printhead itself, the ink ribbon, and the platen. The printhead contains a column of 9 wires. Each of these wires has a drive coil which causes the wire to move in and out of the printhead to print each dot. The four steps below describe how these driving wires work. (1) The control circuit outputs drive signals to the printhead drive circuit. This changes the printhead drive voltage, and current flows through the corresponding printhead coil. The coil acts as a solenoid and generates a magnetic force. (2) Thisinducedforce causesthe plate toapproach the coil rod andtheassociated dotwire is rapidly ejected to impact on the platen. (3) The dot wire presses the ink ribbon up against the paper as it hits the platen and in this way prints a dot on the paper. (4 As soon as the current through the coil is switched off, the force induced in the coil rod stops. The plate then returns to its original position (the position assumed before the coil was energized) through the action of the plate spring. After the dot wire hits the platen, the rebounding force of hitting the platen works with the wire resetting spring to pull the wire back to its original position. 2-1

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REV.-A
2.1 Printer Mechanism Operation
This section describes the printer mechanism of the
FX-870/l
170 printer and explains how the printer works.
The
FX-870/l
170 printer mechanism features a 9-pin impact dot
printhead
for
seriaI
Printin9.
It
has four main
parts: 1) the
printhead
mechanism, 2) the carriage movement mechanism, 3) the paper feed mechanism, and
4) the ribbon advance mechanism. Each of these is described below.
2.1.1
Printhead
Mechanism
The
printhead
mechanism consists of the
printhead
itself, the ink ribbon, and the platen. The
printhead
contains
a column of 9 wires. Each of these wires has a drive coil which causes the wire to move in and out of the
printhead
to print each dot. The four steps below describe how these driving wires work.
(1) The control
circuit
outputs drive signals to the
printhead
drive circuit. This changes the
printhead
drive
voltage, and current flows through the corresponding
printhead
coil. The coil acts as a solenoid and
generates a magnetic force.
(2)
Thisinducedforce
causesthe
plate
toapproach
the coil rod andtheassociated dotwire is rapidly ejected
to impact on the platen.
(3) The dot wire presses the ink ribbon up against the paper as it hits the platen and in this way prints a dot
on the paper.
(4
As
soon as the current through the coil is switched off, the force induced in the coil rod stops. The plate
then returns to its original position (the position assumed before the coil was energized) through the
action of the plate spring. After the dot wire hits the platen, the rebounding force of hitting the platen works
with the wire resetting spring to pull the wire back to its original position.
2-1