2.1 PRINTER MECHANISM OPERATION
This sectiondescribe sthe printer mechanismand explains how itworks.
2.1.1 Printing Mechanism
The printing mechanism is composed of the printhead, ink ribbon, and ribbon mask. The printhead is an
18-pin (9 pins ×2) head for impact dot printing. To improve the durability of the dot wires, they are arranged
on the printhead in2 columns.
Each wire has its own drive coil, which causes the wire to move inand out of the printhead to print each dot.
Thefour steps below describe how thesedriving wires work.
1. A drive signal, transmitted from the control circuit to the printhead drive circuit, is converted to the
proper printhead driving voltage, which energizes a corresponding coil. The energized coil then causes
theiron core to becom e magnetized.
2. The magneticforce draws theactuating platetoward the core,and the dotwire, which is connected tothe
core,rushes toward the platen.
3. When thedot wireimpacts the platen, pressing against theribbon and paper, itprints a dot.
4. When the driving voltage stops energizing the coil, the magnetic force from the iron core vanishes. The
actuating plate returns to its original position (the position before coil was energized) with spring action.
Thedot wire also returnsto its original position.
This is thesequence used to printa single dot.
The mechanism is equipped with a built-in thermistor for head temperature detection. The temperature
detected by thethermistor is converted toan electric signaland fed back to thecontrol circuit.
The printheadis alsoused as abeeper. Head drivingcoils move all thedot wires backand forth at a frequency
of 1.5K Hz for 75 ±5µsec without impacting the platen, so that the wires vibrate. The vibrating
dotwires crea tethe sound usedfor beep codes.
Platen
Ribbon Mask
Ribbon
Dot Wire
Wire Resetting Spring
Stopper
Actuating
Plate
Paper
Iron Core
Head Driving Coil
Actuating Spring
Figure 2-1 Printhead Operation Principles
FX-2170 ServiceManual Operating Principles
Rev.A 2-1