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-3-
Ni-cd terminal
Approx. 6.5V
Approx.
7.5V
Approx. 7.75V
voltage
(initial stage of
(Typ.)
(last stage
of
charging)
charging)
Charging
About 117mA
About
51
mA
About
5.3mA
current
Fig. 5
Circuit section
B in
the
block
diagram
1)
This is a circuit used to charge Ni-cd battery by flowing
approx. 50
mA on
RO
when a printer
is
not
operated.
2)
Charging
current
varies depending on the status of
Ni-cd
battery capacity (terminal
voltage). The
range of
the
variation
is
given
below.
-:- Ni-Cd
_:_AAx
5
I
I
03
I
I
l----
J
Power
supply
,___
__.t--'-A~s~e-ct~io~n
..._~GND
DO
01
ADAPTOR
•
Section B: Power supply
circuit
This is a control circuit in which the output current
of
the AC
adapter
is control l
e
d not to
exceed
max.
500mA
using the
R1
and
Tr1.
C3,
R3
and
02 are used to rise the
power
supply
circuit
by
flowing
base current (03-+02-+Tr3-+R4) on
the
Tr3
when the
AC
adapter is connected.
2)
When
the
Ni-cd
terminal
voltage
is
6.0V
or more, this
circuit
is scarcely
operated.
3)
When the
battery capacity
is small,
if a printer
is
operated, this circuit
is
operated
full toward detecting
l
o w
battery (5.3V). That
is;
when
the
battery vol
t age
is
lowered
to 5.5V by
printer operation,
the
el
e ctric
potential
in
the cathode side (Tr3
col
l ector)
of the
zener
diode
03 is al
s
o
lowered,
and the emitter
electric
potential
of Tr3 is more lowered (get near to GNO
level) on account of constant-voltage
effect
of the
zener diode
03.
Accordingly,
the increase of the
collector current
of
Tr3
causes
the increase
of the
current
of the collector and the
emitter
of
Tr2. There-
fore,
current
supply is passible when the battery
capa-
city is smal
I.
4)
When
the
supply
current is
i
n creased
and
the
AC
adapter
output
current
is 500mA
or more, Tr1 cut-off
electric
potential
is
exceeded (R1 x 500mA), and Tr1
is
ON- Tr2 is
OFF,
so that the current supply
is
stopped.
Since the
printer
operation
vol
t age is the same as that
of
the Ni-cd discharge voltage,
the
Ni-cd terminal voltage Vp
is
connected
directly.
Section
A:
When the capacity
of a Ni-cd battery
is small,
(when the
low-battery
is
not detected),
the
voltage
same
as the battery voltage is directed
from
the
adapter to suppress
bettery
consump-
tion.
Section
B: This
is
a
circuit used exclusively for charging a
Ni-cd
battery.
Section C:
This
is a Vee power supply circuit used for a
logic circuit (printer
control circuit).
Fig.
3
GND
B
~Vp
-=-
'
tlvcc
NI-Cd
A
s.w.
1.
Power
supply circuit
Fig.
3
shows
the
block
diagram of
a
power supply
circuit.
5. EXPLANATION OF CIRCUIT
OPERATION
Fig. 2
-+---;>o.VCC
AC
Adaptor
EX-150
----
Power
supply
(Nl-cd
AA
x 5 PCS)
Low
battery
15
PIN
COIL
Fig.
4 Circuit section A in the block
diagram
Clock INK
1)
SIO
8
Motor
8
dri
v er
dot
plotter-
Printer
Head
4
briver
M-3740
:::t-!
Ni-Cd
!
:
IAAx 5
L
-=r•
_
_j_J
I
I
01
04
R1
ADAPTOR
• Section
A:
Power
supply
circuit
-
CE-140P
15 PIN
Vp
SC6305Y1 A39P
CPU
SIO
INK
Pf
PRINTER
SIO
vcc
0
4. CE-140P CIRCUIT BLOCK
DIAGRAM
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