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 190). 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
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.
