Sharp FDD-412A - Page 35

FDD412A/B
The
correction
values
enter
the
pulse
width
modulator
via
the
phase
compensator
for
varying
voltages
that
flow
in
the
motor
winding.
This
keeps
the
rotational
speed
constant.
Phase R
Fig. 2.29 Spindle Motor Operating Principles
‘ |
wih ayes een nues
output Hy
voltages
Hy
|
|
5
Y
|
1 4 ! ‘
Deawe
We
.
ag
(eae
ies
circuit
Vv
abe
|
OUEPEE
.
+
aaae
om
ei
Pe
voltages
Hw
mime
=e
_]
ee
(ene
a
ae
a
Ee
r
|
fd
anit
ri
|
Motor ROO Press PEE PEER
coil
Is
a=
p=
4
currents | qq canes Fe ert
Fig.
2.30
Spindle
Motor
Drive
Signal
Time
Chart
2.5.7
Overall
FDD
Operations
(Timing
Charts)
All
operations
mentioned
in
2.5.1
through
2.5.6
are
coordinated
for
overall
FDD
control.
The
timing
charts
of
major
operations
are
presented
below
for
a
better
understanding
of
them.
(1)
Initial
seek
(O
track
seek)
(2)
1
track
positioning
(3)
Multi-track
positioning
(4) Write and read
—29—