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10 EXPLANATION OF ELECTRONIC OPERATION
10.1. Principle of Operation
In this
chapter,
the basic
operation
of the electronic
circuitry
of the KX-W50TH
/W60
TH thermal
transfer
typewriters are
explained.
The KX-W50TH/W60TH have
two sensors.
One
sensor is a
photo
sensor, which senses a paper out
c0ndition.
The
other sensor is a
mechanical
switch, which
is the home
sensor for
the
carriage assembly.
The typewriter has five drive
circuits
which drive: the carriage motor, the
paper feed
motor
,
thermal
head, the head press solenoid and the correction motor. There is
a
three position mechanical
switch
which
is used for ribbon selection.
The KX-W50TH/W60TH
Keyboard
functions are the: type mode
selector,
keyboard
selector, type
pitch
selector
,
line space selector
,
text
switch,
print on/off
switch,
text
key
LED
,
which
indicates
the status
of
the text mode (KX-W60TH only), mathematical function
switches (KX-W50TH only),
the LCD display
and the display contrast
knob.
The mode status indicators of both machines display the
setting of
the
:
typ
in
g mode, keyboard, type
pitch,
line space
,
indent,
bold print, enlarge print,
auto
underline print
mode, auto
return, justification
mode, auto centering, the
right
margin
flush mode,
weak battery,
and
the text record
status (KX-W60TH
only).
LOGIC DIAGRAM
1
/
F
Adaptor
Interface
Control Circuit
Drive
(RP-K100)
(CPU)
Circuit
Carriage
Motor
Paper Feed
Motor
Thermal Head
Head press Solenoid
Correction
Motor
Operation Switch
LCD
Power
Indicator
Display
Supply
I
Sensor
Circuit
I
_J
C_
-
22
-
r
~
//"'
tr
10.2. Circuitry
10.2.1
.
Power Supply
Block
(1)
Power
and filter
section
The power
from
the AC
adaptor or
the
batteries is supplied to
the power
switch.
The
absorption capacitor (C116) together with the filter
remo ves noise
entering the circuit
from the power
source.
The
capacitors are also
used for eliminating noise leaving
the type-
writer
to the
power
line
.
As
a
result
,
the typewriter 's
digital
circuitry operates stable, and will
be unaffected by
noise
entering
the
circuit
from the
outside and prevents
noise
from
leaving the
typewriter.
(2)
Power
Circuitry
In
this circuit,
the Primary DC
power
passes through
a
switching
regulator circuit
,
thus
pro-
viding
the
necessary
vo
ltages for the
control circuitry and drive circuitry
.
The
voltage
for
the
thermal
head
is varied with the
density
controller (VA)
.
Variable range
is from 0-1.5 volts.
The
following voltages are supplied:
DC
+9
V
:
Stepping
motor, Head press solenoid
and DC
motor
DC
+6
~
7.5V
:
Therma
l
head
DC
+5
V
:
CMOS
logic·
and
Interface
DC
-2V
:
LCD
Display
During
correction operation the thermal
head
voltage
rises to
its
maximum
voltage,
this
will
happen regardless
of the density
control
knob setting.
Since all
the thermal heads
for
this unit do not have
the same resistance, adjustment of
thermal
head vo
lage
is required.
Set
thermal head voltage by rotating Variable resistor VR101
on Main
P.C.B
.
accord
ing
to
the
specified
voltage which corresponds with the resistance of
the
individual thermal head
(Refer
to
section
4.
Adjustment of thermal head
voltage).
-23-
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