Appeal 2007-3939
Application 10/448,725
appropriate windings to rotate the rotor in the correct direction every time.
However, such sensors must be precisely positioned and the sensor
components are expensive and take up physical space in the motor (col. 2, ll.
46-57).
4. Calfee provides for a method for accelerating the motor of the
disk drive from standstill to a threshold speed by determining a rotational
position of the rotor relative to the phase windings during a time period,
selectively establishing current paths through selected windings capable of
providing maximum torque to the rotor based on the rotational position of
the rotor and applying a current to the selected windings for a time period to
provide maximum torque to rotate the rotor (col. 5, ll. 39-52; col. 8, ll. 38-
42).
5. In order to start the spindle motor and free the slider in case of
stiction, the drive performs closed loop commutation of the spindle motor by
periodically sampling the rotor position, and then driving the spindle motor
by energizing appropriate phase windings relative to the rotor position that
provide maximum forward torque to the rotor (col. 8, ll. 21-31).
6. The rotor position detection (RPD) procedure uses indirect
inductance measurements to identify one of the six stable equilibrium
positions as the closest stable equilibrium position to the rotor's current
position (col. 11, ll. 32-36). The procedure includes the steps of measuring
the relative inductance of each phase winding by measuring the current rise
times in the phase winding in response to step voltages of opposite polarities
applied across the phase windings at, preferably, one rotor position (col. 11,
ll. 40-44).
4
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Last modified: September 9, 2013