Fujitsu MHW2040AT - Mobile 40 GB Hard Drive, Product Manual

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Theory of Device Operation
4.1 Outline
This chapter consists of two parts. First part (Section 4.2) explains mechanical
assemblies of the disk drive. Second part (Sections 4.3 through 4.7) explains a
servo information recorded in the disk drive and drive control method.
4.2 Subassemblies
The disk drive consists of a disk enclosure (DE) and printed circuit assembly
(PCA).
The DE contains all movable parts in the disk drive, including the disk, spindle,
actuator, read/write head, and air filter. For details, see Subsections 4.2.1 to 4.2.4.
The PCA contains the control circuits for the disk drive. The disk drive has one
PCA. For details, see Sections 4.3.
4.2.1 Disk
The DE contains disks with an outer diameter of 65 mm and an inner diameter of
20 mm.
Servo data is recorded on each cylinder (total 172). Servo data written at factory is
read out by the read head. For servo data, see Section 4.7.
4.2.2 Spindle
The spindle consists of a disk stack assembly and spindle motor. The disk stack
assembly is activated by the direct drive sensor-less DC spindle motor, which has
a speed of 4,200 rpm
±
1%. The spindle is controlled with detecting a PHASE
signal generated by counter electromotive voltage of the spindle motor at starting.
4.2.3 Actuator
The actuator consists of a voice coil motor (VCM) and a head carriage. The VCM
moves the head carriage along the inner or outer edge of the disk. The head
carriage position is controlled by feeding back the difference of the target position
that is detected and reproduced from the servo information read by the read/write
head.
4-2 C141-E250