Epson MX-80 Technical Manual page 36

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2.5 Operating Principles of Printer Mechanism
The M-3210 Printer Mechanism can be broadly divided into the following six functional
blocks.
(1) Print head mechanism
(2) Head carriage mechanism
(3) Paper feeding mechanism
(4) Ribbon feeding mechanism
(5) Detecting mechanism
(6) Frame section
2.5.1 Head carriage and paper feeding mechanisms
The operations of all the above mechanisms except the frame section are basically con
trolled by the two stepper motors which are driven by two two-phase excitation signals. The
turning force from each motor is decelerated by a simple gear train and is conveyed to the
timing belt for bead carriage driving or sprocket wheel for paper feeding, respectively. These
stepper motors are 4-pnase. 48-pole motors. The angle of revolution per phase of each
motor corresponds to the movement of the sprocket wheel or timing belt as follows:
(1) One pnase ol paper feeding stepper motor 11216 inch (0.12 mm)
(2) One pnase of carriage stepper motor 1/60 inch (0.42 mm)
2.5 2 Print head
Tne print head is the life and soul of the MX-80 dot matrix printer and serves as the neucleus
of tne printer operations The operating principle of tne print head is simple as explained
below by referring to Fig 2.24.
Dot wue
_z
Magnetic pole Magnet
Fig. 2.24 Operation of Print Head
Wnen tne current witn a pulse width of approx 400 usec is applied to tne magnet, tne mag
netic actuator IS attracted to tne magnet, inus causing tne collar portion of the dot wire to be
pushed out against tne force of tne spring Tne clearance between the actuator and each dot
wire nas been adjusted so tnat tne dot wire protrudes about 06mm when its collar portion is
pusned Tne dot wire tnus protruded mtne direct'On of the arrow strikes the paper through
tne inked ribbon and is caused to return to its ongmal position by tne action of tne spring and
the reaction of its impact against tne paper
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