Method and apparatus for reducing track switch latency in a disk drive

Apparatus for reducing track switching latency in a disk drive where track switching involves selecting among a number of read/write heads on a single head arm actuator, said latency reducing apparatus comprising:

• means for calculating time remaining until an end of data transfer between a read/write head and a present track;
• means for calculating a leadoff time interval corresponding to the time required to complete track-switch preparations by a track-switch preparation means;
• means for detecting when said leadoff interval is greater than said time remaining until said end of data transfer for said present track;
• and
• said track-switch preparation means responsive to said detecting means for starting track-switch preparations when said leadoff interval is greater than said time remaining.

Apparatus for reducing track switching latency in a disk drive when switching from a presently active read/write head on a present track to a next selected read/write head on a new track, the disk driving having a plurality of read/write heads on a head arm actuator, said apparatus comprising:

• means for pre track-switch processing during a phase 1 time interval;
• means for energizing said actuator during a phase 2 time interval to build up energy in said actuator prior to movement of said actuator;
• said actuator in response to energization by said energizing means moving during a low-displacement phase 3a time interval to exit the present track;
• means for accumulating one or more of the phase 1, 2 or 3a time intervals to determine a leadoff interval;
• means for monitoring time remaining for the present active head to reach end of track on the present track;
• means for comparing said leadoff interval to said time remaining;
• and
• means responsive to said comparing means for starting said pre track-switch processing means when said leadoff interval is greater than said time remaining.

Apparatus for reducing track switching latency in a disk drive when switching from a presently active read/write head on a present track to a next selected read/write head on a new track, the disk driving having a plurality of read/write heads on a head arm actuator, said apparatus comprising:

• means for pre track-switch processing during a phase 1 time interval;
• means in response to completion of pre track-switch processing for energizing said actuator during a phase 2 time interval to build up energy in said actuator prior to movement of said actuator;
• means for combining phase 1 and 2 time intervals to determine a leadoff interval indicating time required for pre track-switch processing and actuator energy build up;
• means for monitoring time remaining for the present active head to reach end of track on the present track;
• means for comparing said leadoff interval to said time remaining;
• and
• means responsive to said comparing means for starting said pre track-switch processing means when said leadoff interval is greater than said time remaining whereby said pre track-switch processing and actuator energy build up is overlapped with the end of the read/write operation by the presently active head on the present track.

In a disk drive having a plurality of read/write heads on a head arm actuator, a method for reducing track switching latency in the disk drive when switching from a presently active read/write head on a present track to a next selected read/write head on a new track, said method comprising the steps of:

• pre track-switch processing during a phase 1 time interval;
• energizing said actuator during a phase 2 time interval to build up energy in said actuator prior to movement of said actuator, said actuator in response to energization by said energizing step moving during a low-displacement phase 3a time interval to exit the present track;
• accumulating one or more of the phase 1, 2 or 3a time intervals to determine a leadoff interval;
• monitoring time remaining for the present active head to reach end of track on the present track;
• comparing said leadoff interval to said time remaining;
• and
• starting said pre track-switch processing means when said leadoff interval is greater than said time remaining.

In a disk drive having a plurality of read/write heads on a head arm actuator, a method for reducing track switching latency in a disk drive when switching from a presently active read/write head on a present track to a next selected read/write head on a new track, said method comprising the steps of:

• pre track-switch processing during a phase 1 time interval;
• after completion of pre track-switch processing step, energizing said actuator during a phase 2 time interval to build up energy in said actuator prior to movement of said actuator;
• combining phase 1 and 2 time intervals to determine a leadoff interval indicating time required for pre track-switch processing and actuator energy build up;
• monitoring time remaining for the present active head to reach end of track on the present track;
• comparing said leadoff interval to said time remaining;
• and
• starting said pre track-switch processing means when said leadoff interval is greater than said time remaining whereby said pre track-switch processing and actuator energy build up is overlapped with the end of the read/write operation by the presently active head on the present track.