Appeal No. 1997-3923
Application 08/212,203
BACKGROUND
The subject matter on appeal is directed to an improved method for seeking tracks (i.e.,
computer files) on a disc surface by controlling the velocity and acceleration of a transducer from an
initial track to a target track by adjusting actuator coil current (see Brief, pages 4 to 6; specification,
pages 2 to 5). The acceleration of the transducer is related proportionately to the current passing
through the actuator coil, so acceleration can be controlled by changing actuator coil current. As stated
by appellants at page 3 of the specification, it is desirable to reduce the time it takes during the seek
phase for the transducer to locate the target track by using correction signals which are based on a
velocity profile. Because correction signals based on maximum acceleration and deceleration (needed
to reduce seek time) using maximum current tend to cause overshooting of the target track as well as
requiring settling time, it is conventional to base corrections on a nominal current that is a percentage of
the maximum current (typically 80 to 90 percent) for the actuator coil (see specification, page 7).
However, use of a lower, nominal current typically increases the time required to move the transducer
during the seek phase (see specification, page 8).
Appellants have recognized that the use of correction signals based on variations of the
maximum actuator coil current during acceleration and deceleration of the transducer substantially
reduces seek time (see specification, page 8). More specifically, appellants provide a scale factor
based on a ratio of maximum coil current to nominal coil current which increases the velocity over the
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