4.1 Outline. Fujitsu C141-E090-02EN

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4.1 Outline. Fujitsu C141-E090-02EN | Manualzz

CHAPTER 4 THEORY OF DEVICE OPERATION

4.1

Outline

4.2

Subassemblies

4.3

Circuit Configuration

4.4

Power-on sequence

4.5

Self-calibration

4.6

Read/write Circuit

4.7

Servo Control

This chapter explains basic design concepts of the disk drive. Also, this chapter explains subassemblies of the disk drive, each sequence, servo control, and electrical circuit blocks.

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 the disks with an outer diameter of 95 mm. The MPE3102AH and

MPE3136AH have 2 disks. The MPE3204AH has 3 disks. The MPE3273AH has 4 disks.

The head contacts the disk each time the disk rotation stops; the life of the disk is 40,000 contacts or more.

Servo data is recorded on each cylinder (total 72). Servo data written at factory is read out by the read/write head. For servo data, see Section 4.7.

C141-E090-01EN 4 - 1

4.2.2

Head

Figure 4.1 shows the read/write head structures. The Numerals 0 to 7 indicate read/write heads. These heads are raised from the disk surface as the spindle motor approaches the rated rotation speed.

MPE3102AH

Spindle Actuator

MPE3136AH

Spindle Actuator

MPE3204AH

Spindle

2

1

0

5

2

1

4

3

0

Actuator

MPE3273AH

Spindle

4

3

2

1

0

7

6

5

3

2

1

0

Actuator

Figure 4.1

Head structure

4.2.3

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 7,200 rpm.

The spindle is controlled with detecting a PHASE signal generated by counter electromotive voltage of the spindle motor at starting. After that, the rotational speed is kept with detecting a servo information.

4.2.4

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-E090-01EN

4.2.5

Air filter

There are two types of air filters: a breather filter and a circulation filter.

The breather filter makes an air in and out of the DE to prevent unnecessary pressure around the spindle when the disk starts or stops rotating. When disk drives are transported under conditions where the air pressure changes a lot, filtered air is circulated in the DE.

The circulation filter cleans out dust and dirt from inside the DE. The disk drive cycles air continuously through the circulation filter through an enclosed loop air cycle system operated by a blower on the rotating disk.

C141-E090-01EN 4 - 3

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