Service manual
DFx-5tW(h
Sewka
Manual Oparathg
Prfncipka
2.1 OVERVIEW OF PRINTER MECHANISM OPERATION
This section describes the Model
3C11
printer mechanism and explains how the printer works. The
Model
3C11
printer mechanism features a 9-pin, impact dot
printhead
for serial printing.
The
printer mechanism is the main component of the printer and is supported by the other
mmponents
(the power supply and control
arcuits).
Figure 2-1 shows the Model
3C11
printer mechanism.
PAPER
BA~L
ASSEMBLY
Plunger
TIMING
BEL
Connector
Junction
Board
TRACTOR ASSEMBLY (FRONT)
D MOTOR
\
PLATEN GAP ADJUSTMENT MOTOR
Figure 2-1. Model
3C11
Printer Mechanism
The printer mechanism consists
of
the following main components:
22
Printhead
The
printhead
is the component that actually pMts characters (dot matrix patterns). Printing is
performed by striking the pins (arranged in a vertical line) against the surface of the paper and the
ribbon. A character is printed by repeating this printing operation in the horizontal direction (as the
printhead
moves).
The
printhead
includes a head fan and temperature sensor.
The
head fan also
has a thermistor. When the
printhead
or fan is too hot, the printer stops printing until it cools.
(Refer to Section 1.4.12,
Themud
Probation.)
L1
Carnage mechanism
The carriage mechanism moves the
printhead
in the horizontal direction. The CR motor drives the
carriage, with the
printhead
on it. The CR sensor detects the CR motor speed and carriage position.
The CR motor is closed-loop controlled. Because the CR motor is driven at a very high speed, it
includes an isolation resistance sensor to detect abnormal resistance. The sensor detects an error if
the resistance is less than 1
I@.
Cl Interlock switch
Because the carnage moves at a very high speed, it would be dangerous if a hand or finger were
inserted inside the printer mechanism during printing. Therefore, as a safety measure, when the
top cover is opened, the interlock switch cuts the drive voltage to the CR motor to slow down the
carriage speed and prevent
acadents.
A control circuit
controIs
CR motor driver deceleration.
(Refer to Section 2.3.4.,
CR Motor Dine Circuit.)
Printing resumes when the top cover is closed.
LI
Auto platen gap adjustment mechanism
The printer mechanism has an automatic platen gap adjustment function that measures the
thickness of the paper and provides the appropriate gap between the platen and
printhead.
The
platen gap is adjusted by moving the carriage (and
printhead)
either forward or backward. Because
the front and rear carriage guide shafts which hold the
@rriage
are purposely mounted off-center,
the carriage moves as the
PC
motor rotates the shafts. The PG
sensor transmits the amount of
movement (= gap) to the control circuit.
Rev.
A
2-1