Maxtor D540X-4K - Manual (Page 52)

Basic Principles of Operation
5-4 Maxtor D540X-4K 20.4/40.0/60.0/80.0 GB AT
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The headstack assembly consists of read/write heads, head arms, and a coil joined
together by insertion molding to form a rotor subassembly, bearings, and a flex circuit.
Read/write heads mounted to spring-steel flexures are swage mounted onto the rotary
positioner assembly arms.
The flex circuit connects the headstack assembly to the PCB through a compression
connector. The flex circuit contains a read preamplifier/write driver IC.
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The rotary positioner, or rotary voice-coil actuator, is a Maxtor-proprietary design
that consists of upper and lower permanent magnet plates, a rotary single-phase coil
molded around the headstack mounting hub, and a bearing shaft. The single bi-polar
magnet consists of two alternating poles and is bonded to the magnet plate. A resilient
crash stop prevents the heads from being driven into the spindle or off the disk surface.
Current from the power amplifier induces a magnetic field in the voice coil.
Fluctuations in the field around the permanent magnet cause the voice coil to move.
The movement of the voice coil positions the heads over the requested cylinder.
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To ensure data integrity and prevent damage during shipment, the drive uses a
dedicated landing zone, an actuator magnetic retract, and Maxtor’s patented Airlock
®
.
The Airlock holds the headstack in the landing zone whenever the disks are not
rotating. It consists of an air vane mounted near the perimeter of the disk stack, and a
locking arm that restrains the actuator arm assembly.
When DC power is applied to the motor and the disk stack rotates, the rotation
generates an airflow on the surface of the disk. As the flow of air across the air vane
increases with disk rotation, the locking arm pivots away from the actuator arm,
enabling the headstack to move out of the landing zone. When DC power is
removed from the motor, an electronic return mechanism automatically pulls the
actuator into the landing zone, where the magnetic actuator retract force holds it until
the Airlock closes and latches it in place.