REV.-A
2.1 OVERVIEW OF PRINTER
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This section describes the printer mechanism of the Model-5J10 printer unit and explains how the printer works.
main parts to the printer mechanism: 1) the printhead mechanism, 2) the carriage movement mechanism, 3) the
paper advance 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 mntains 24
wires in a zigzag arrangement in two rows of 12. A drive coil is provided for each of these wires to make the wires
move in and out of the printhead and print dots independently of each other. The basic way that the wires are driven
is described in the four steps below.
1.
The control circuit outputs the drive signal to the printhead drive circuit. This changes the printhead drive
voltage, and current flows through the corresponding pnnthead coil. The coil acts as a solenoid and generates
a magnetic force.
2.
This induced force causes the plate to approach the coil md and the associated dot wire 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 mil rod stops. The plate then
returns to its original position-(its position before the coil was energized) through the action "of the p~te spring.
After the dot wire hits the platen, the rebounding force of hitting the platen works together with the wire return
spring to pull the wire back to its original position in relation to the plate.
Figure
shows the action of the printer mechanism when a single dot is printed.
2-1
The printhead tends to heat up aftera period of mntinuous printing. To minimize the possibility of the dot wire drive
coils overheating within the printhead and any loss of performance, the head is equipped with a thermistor that
detects the head temperature. When this thermistor detects changes intheprinthead temperature, thevoltagesignal
changes. This signal change is read by the control circuit for feedback mntrol.
MECHANISM OPERATION
Oot
Wire
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Figure 2-1. How the Printhead Works
RIBBON MASK
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Ribbon
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PLATEN
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