Heads; Actuator And Latch Assembly; Head Interface Electronics; Atmospheric Controls - HP C2246 Technical Reference Manual

Heads
Thin film data heads in the HDA write and read user data. An additional thin film head in
each unit is used to recover the servo information.
Actuator and Latch Assembly
A rotary actuator positions the heads. A shipping latch captures the actuator arm at the
inside diameter of the disks (away from user data) whenever power is removed from the disk
drive. This prevents the heads from moving over data until power is applied and the disks
are spinning, causing the heads to fly at a safe distance above the disk surfaces. During the
power-up sequence, the processor releases the latch, allowing normal movement of the heads.
Head Interface Electronics
The head interface circuits (located inside the HDA), process the data signals transferred
between the read/write heads and the drive electronics/controller PCA. These circuits include
write drivers which provide the necessary current to the heads during write operations, and
read preamplifiers that amplify data read from the disk before transferring it to the read/write
circuit on the drive electronics/controller PCA. Additional functions performed by the head
interface include head selection and write control.
Atmospheric Controls
The atmospheric controls in the HDA consist of a breather filter and a recirculating filter.
The breather filter equalizes air pressure within the HDA to ambient air pressure and
prevents contaminants from entering the HDA. The recirculating filter maintains the internal
cleanliness of the HDA.
Vibration Isolators
The HDA is mounted on vibration isolators to protect it from high frequency external
vibrations.
Spindle Assembly
The spindle assembly provides the mechanical mounting for the disks. The spindle rotates on
a bearing system and is driven by an "in hub" brushless de motor. The drive current for the
motor is supplied
by
the spindle driver circuit on the drive electronics/ controller PCA. Three
Hall-effect sensors, mounted on the spindle assembly, provide feedback signals to the spindle
control electronics for speed and phase switching control.
Product Features 3· 7