Fujitsu MAH3091MC - Enterprise 9.1 GB Hard Drive, Руководство по обслуживанию

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C141-E103-01EN 8 - 13
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 SCSI control MDU controls the senseless 3-phase spindle motor. It carries out start / normal
rotation control and spindle synch control in accordance with commands from the SCSI unit.
(1) Activation
The SCSI control 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.
2) In the next timing phase of 1) above, the DSP creates a rotating magnetic field. The motor
rotates from a low rotational frequency up to about 100 min
-1
(100rpm). This is called
synchronization control.
3) When the motor reaches a high rotational frequency, a counter-electromotive voltage (back
EMF) is generated. This voltage tells the DSP the rotational frequency and angular position of
the motor. Using the rotation position detection data, the spindle controller supplies current to
the correct phase to rotate the motor. The MPU then detects the rotational frequency, and the
spindle controller accelerates the motor up to the steady-state angular frequency.
(2) Rotational speed control mode
When the activation mode terminates, the rotational speed control mode starts. The MPU controls
the controller to maintain the detected rotational speed.
8.7.5 Voice coil motor control
The voice coil motor is controlled by moving the head-mounted carriage according to the servo
data recorded on the specific data side. This control is done by firmware by digital servo control
using the DSP. This control provides return-to-zero (RTZ) operation, seek operation, and track
following operation.