Fujitsu MAN3367FC Manual/User Guide - Page 114

W/R recovery

Page 114 highlights

Principle of Operation 4) Gray code area The gray code is an encoded area which includes the head number, servo sector number and cylinder information as gray code. Head position is recognized based on the cylinder information embedded as a gray code pattern. 5) Position area Information for recognizing head position is recorded in the position area. Head position in cylinder unit is recognized by using the cylinder information in the gray code area, and head position under one cylinder (resolution) is recognized by using the information in the position area. Outer side of disk Center of disk DS IGB DSaetravozoznoene Figure 8.5 Position of servo track OGB 8.7.3 Servo frame format W/R recovery Servo Gap mark Gray code/Position Gap Figure 8.6 Servo frame 8.7.4 Spindle motor control The MPU controls the senseless 3-phase spindle motor. It carries out start / normal rotation control and spindle synch control. (1) Activation The MPU carries out control of the spindle motor from the stopped condition to normal rotation by the following sequence. 1) DSP intermittently supplies current between specific phases (e.g., phases U and V) to force a fixed motor rotation position. This operation is called alignment. 8-12 C141-E133-02EN

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Principle of Operation
8-12
C141-E133-02EN
4)
Gray code area
The gray code is an encoded area which includes the head number, servo sector number and
cylinder information as gray code.
Head position is recognized based on the cylinder information
embedded as a gray code pattern.
5)
Position area
Information for recognizing head position is recorded in the position area.
Head position in
cylinder unit is recognized by using the cylinder information in the gray code area, and head
position under one cylinder (resolution) is recognized by using the information in the position
area.
IGB
DS
Outer side of disk
Center of disk
OGB
Figure 8.5
Position of servo track
8.7.3
Servo frame format
Gap
Gray code/Position
Gap
Servo
mark
W/R recovery
Figure 8.6
Servo frame
8.7.4
Spindle motor control
The MPU controls the senseless 3-phase spindle motor.
It carries out start / normal rotation control
and spindle synch control.
(1)
Activation
The MPU carries out control of the spindle motor from the stopped condition to normal rotation by
the following sequence.
1)
DSP intermittently supplies current between specific phases (e.g., phases U and V) to force a
fixed motor rotation position.
This operation is called alignment.
Data zone