Operation Of Print Unit Mechanisms; Carriage Feed Mechanism; Character Selection Mechansism; Hammer Mechanism - JUKI 6100 Technical Manual

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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