JUKI 6100 - 4 Operation of Print Unit Mechanisms; Carriage Feed Mechanism; Character Selection Mechansism; Hammer Mechanism

As
previously
described
in
Section
2
"Main
Component
Units", all
communications to
the
host CPU
and
all
printing
functions
are
performed by
the
control
unit.
Two
sepa-
rate
circuit
boards,
the
Master
CPU and the
Slave
CPU,
comprise the Control Unit.
The
standard
printer
comes
with
a
Centronics
compatible
Parallel
Interface. An
optional
serial
interface
board is
also
available
which
attaches
directly to
the master CPU
board.
Installation
of
the
serial
interface
over-rides
the
parallel
interface, in effect, making
the
two
interfaces
mutually
exclusive.
o
Master
CPU
Data from
the
host
CPU
received via
parallel
interface
is latched at the I/O
port
of
the
8155. The
8051
master
CPU retrieves
this
data
and stores it
into RAM.
The
master CPU
then reads
data
from RAM,
performs
computations
and transfers the
data
necessary
for
printing to the
slave CPU.
All data
retrieved from RAM is
checked
for embeded
escape
sequences or
special control
codes.
o
Slave CPU
In response
to the
commands
received from
the
master
CPU, the slave CPU
will
energize
the
appropriate
driver circuits
to
perform
the
printing function. Among
the
components
under
control of the
slave
CPU
are the
linear motor,
selection motor,
ribbon
motor,
clutch
magnet
and the
line
feed
motor. The
805
1
on the
slave CPU
board
has two
timers
which aid
the
CPU in
controlling two
of the
control compo-
nents in
an
overlap
mode.
An
example
would
be during
the
print operation
when
after a
character has
been
printed, the
CPU
operates the
linear motor to
move to the
next
print
position
while
it is
operating the
selection
motor
to
align
the next
charac-
ter to
print.
The
operation
of all
the
necessary
components for
printing being
controlled by
a
signle
slave CPU is
seen as
one
of
this printers strongest
features.
4.
Operation
of Print
Unit Mechanisms
The
print unit
mechanism may
be divided
into the following five mechanisms:
(1)
Carriage feed
mechanism
(2)
Character
selection
(3)
Hammer
mechanism
(4)
Ribbon
feed mechanism
(5)
Form
feed
mechanism
4.1
Carriage
feed
mechanism
The
carriage
feed
mechanism
is
directly
driven
by a
linear
stepping
motor. It is
controlled
by
the
CPU
according
to
the
driving
timing
which
has been
stored
beforehand,
and
is
driven by
constant-current
based on
frequency
modulation.
Further,
this
carriage
feed
mechanism
is
designed to
reduce
the driving
current
while
not in
use,
thereby
avoiding
waste
of
power.
The
resolution
of
the
lateral
feed is 1/120
inch.
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