Servo Control; Figure 4.7 Block Diagram Of Servo Control Circuit - Fujitsu MHR2010AT Product Manual

Theory of Device Operation

4.7 Servo Control

The actuator motor and the spindle motor are submitted to servo control. The
actuator motor is controlled for moving and positioning the head to the track
containing the desired data. To turn the disk at a constant velocity, the actuator
motor is controlled according to the servo data that is written on the data side
beforehand.
4.7.1 Servo control circuit
Figure 4.7 is the block diagram of the servo control circuit. The following
describes the functions of the blocks:
(1)
(2)
Servo
Head
burst
capture
Position Sense
CSR: Current Sense Resister
VCM: Voice Coil Motor

Figure 4.7 Block diagram of servo control circuit

(1) Microprocessor unit (MPU)
The MPU uses DSP and executes startup of the spindle motor, movement to the
reference cylinder, seek to the specified cylinder, and calibration operations.
Main internal operation of the MPU are shown below.
4-14
MPU
(3)
MPU
DAC
core
(5)
Spindle
motor
control
SVC
(4)
Power
VCM current
Amp
CSR
(7)
VCM
(6)
Spindle
Driver
motor
C141-E145-02EN