Panasonic KX-B620 - Sensor Board; Control Board

KX-B620 Series
KX-B520 Series
9-10
Screen
Home
Position
Sensor
Board
1) Circuit Operation
This
circuit
is
made
up
of
a
reflective
type
optsensor
and
the
buffer
circuit.
There are 2 black marks at the bottom of the screen which absorbs light effectively.
When
the
sensor
detects
a
black
mark,
the
output
signal
“SHEND”
becomes
“L”,
and
input
into
the
CPU from D7 Port.
SENSOR BOARD CONTROL BOARD
Fp A rs ee ae SS a |
1C400
ON2173R
Fig. 41 Circuit Diagram
When
the
screen
mark
is
not
in
position,
the
optical
sensor
“ON2173-R”
{C400
receives
the
light
being
reflected
by
the
screen
and the photo-transistor
is “ON”.
The
base ®
of
transistor
Q400
is
less
than
0.6
V
and
it
remains
“OFF”.
When
the
black
screen
mark
comes,
the
light
is
not
received,
the
photo-transistor
goes
“OFF”
,
and
Q400
goes
“ON”.
Output
@®
“SHEND"”
becomes
“L”.