Outline; Subassemblies; Disk; Head - Fujitsu MHA2021AT Product Manual

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 4.2.5.
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. The MHA2032 has three disks and MHA2021AT has two disks.
The head contacts the disk each time the disk rotation stops; the life of the disk is
50,000 contacts or more. Servo data is recorded on top disk.
Servo data is recorded on each cylinder (total 54). Servo data written at factory is
read out by the read/write head. For servo data, see Section 4.7.

4.2.2 Head

Figure 4.1 shows the read/write head structures. MHA2021AT has 4 read/write
heads and MHA2032AT has 6 read/write heads. These heads are raised from the
disk surface as the spindle motor the rated rotation speed.
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