BASF 6106 - Index Detector

2.2.7.
INDEX/SECTOR-
and
READY
DETECTOR
2. 2.
7.1.
INDEX/SECTOR
DETECTION
The
index/sector
detector
comprises
a
photo
transistor
mounted
on the
deck
assembly
,
a
light
emmitting
diode
(LED)
on
the PWB
and
a
comparator
(see
Fig.
2-24
).
As
the
index
hole
or
sector
(optional)
hole
passes
between
LED
and
phototransistor,
light
from
the
LED
is
passes
to
the
phototransistor.
This
results
in a
negative
pulse of
about
1,5
msec
on the
inverting
input
of
the
comparator.
The
output
pulse
of
the
comparator
is sent
to
the
host
system
by
the
output
interface
when
I/O ENA
is
activ.
Also
the
INDEX-
pulse
is
used
as
input
signal
for the
ready
detector
logic.
5V
PHOTO
TRANSISTOR
OUTPUT
INTERFACE
INDEX
I
HOST
»
TO
THE
sysTEM
FROM
INPUT
INTERFACE
fr-
FIGURE
2
-
24
. INDEX
DETECTOR
18