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2.1.2
Disk Stack Assembly
Three aluminum alloy disks (two for the Q250) are placed on the motor
hub and clamped in place.
A thin film magnetic metal is sputtered on
the surfaces of the disks, and lubricated with a carbon overcoat that
prevents head and media wear when the heads are in contact with the
head surface.
This only occurs in the landing zone outside the data
area, and when the disks are not rotating at full speed.
2.1.3
Rotary positioner Assembly (Actuator)
The positioner is a proprietary design consisting of upper and lower
permanent magnet plates, and a rotary single phase coil molded to
the headstack mounting hub shaft.
The magnets are composed of two
alternating poles bonded to the magnet plates which, in turn, are
bolted to the base casting.
Resilient crash stops are mounted to the
magnet plates.
These prevent the heads from being driven into the
spindle or off of the disk surface.
2.1.4
Headstack Assembly
The headstack assembly consists of the read/write heads, spacers,
flex circuit, and rotary positioner assembly. The head arms and rotary
positioner assembly balance each other so that the mass center of the
entire stack is at the center of the mounting hub.
The heads are
mini-composite slider-type heads, mounted to Whitney-style spring
steel flexures.
The heads and actuator are connected by the flex
circuit, which contains a read preamplifier/write driver chip.
2.1.5
Automatic Actuator Lock (AIRLOCK)
AIRLOCK is a mechanical means of locking the heads tack in the landing
zone, and is covered by
u.s.
Patents and pending patent applications.
The dedicated landing zone for the heads ensures data integrity and
prevents damage during shipment.
When dc power is removed from the
motor, an electronic return spring extracts energy from the spinning
motor and pulls the headstack into the landing zone.
AIRLOCK latches
it in place.
As dc power is applied to the motor and the disk stack
starts spinning, airflow increases, and the airvane on AIRLOCK
rotates, releasing the headstack.
2.1.6
DC Drive Motor
To achieve accurate speed control with minimum electromagnetic
interference, the Q250/Q280 uses a brushless dc spindle motor in a
closed-loop digital servo system, synchronized by a 2 MHz clock.
The
motor is dynamically balanced, four pole, three phase, and rotates at
3662 rpm.
A 12 V motor control IC commutates the motor coils in
2-2
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