Method and apparatus for improving servo zoning for PRML detected gray code using channel bit densities

A method for optimizing the detection of servo-sector gray code in a hard disk drive, comprising:

• providing a magnetic disk having a plurality of tracks, including a first track at an inside diameter of said disk and a second track at an outside diameter of said disk;
• selecting a number of servo sector zones;
• calculating a first channel bit density, wherein said first channel bit density is a channel bit density of servo sector information associated with said first track;
• calculating a second channel bit density, wherein said second channel bit density is a channel bit density of servo sector information associated with said second track;
• calculating a difference between said first and second channel bit densities;
• dividing said difference between said first and second channel bit densities by said selected number of servo sector zones to obtain a channel bit density range per zone;
• and
• defining a first zone as extending from said first track to a third track, wherein a channel bit density of said third track is equal to said channel bit density of said first track minus said channel bit density range per zone.

A method for allocating servo sector zones in a rotating storage device, comprising:

• providing a magnetic disk having a plurality of tracks, including an inner track at an inside diameter of said disk and an outer track at an outside diameter of said disk;
• calculating a channel bit density of servo sector information at said inner track;
• calculating a channel bit density of servo sector information at said outer track;
• calculating an overall range of channel bit densities, wherein said overall range is equal to the difference in channel bit densities between said channel bit densities at said inner and outer tracks;
• dividing said range into N zones, each having a range Z of channel bit densities that are about equal to one another;
• and
• shaping a signal derived from servo sector information located within one of said N zones according to a corresponding one of N pulse shaping schemes, wherein said N pulse shaping schemes comprise N filters.

A method for allocating servo sector zones in a rotating storage device, comprising:

• providing a magnetic disk having a plurality of tracks, including an inner track at an inside diameter of said disk and an outer track at an outside diameter of said disk;
• calculating a channel bit density of servo sector information at said inner track;
• calculating a channel bit density of servo sector information at said outer track;
• calculating an overall range of channel bit densities, wherein said overall range is equal to the difference in channel bit densities between said channel bit densities at said inner and outer tracks;
• dividing said range into N zones, each having a range Z of channel bit densities that are about equal to one another;
• and
• shaping a signal derived from servo sector information located within one of said N zones according to a corresponding one of N pulse shaping schemes, wherein each of said N pulse shaping schemes is optimized to detect a signal derived from servo sector information associated with a track having a middle channel bit density for its corresponding zone.

A method for allocating servo sector zones in a rotating storage device, comprising:

• providing a magnetic disk having a plurality of tracks, including an inner track at an inside diameter of said disk and an outer track at an outside diameter of said disk;
• calculating a channel bit density of servo sector information at said inner track;
• calculating a channel bit density of servo sector information at said outer track;
• calculating an overall range of channel bit densities, wherein said overall range is equal to the difference in channel bit densities between said channel bit densities at said inner and outer tracks;
• dividing said range into N zones, each having a range Z of channel bit densities that are about equal to one another;
• and
• shaping a signal derived from servo sector information located within one of said N zones according to a corresponding one of N pulse shaping schemes, wherein each of said N pulse shaping schemes is optimized to detect a signal derived from servo sector information associated with a middle track located within its corresponding zone.

A method for allocating servo sector zones in a rotating storage device, comprising:

• providing a magnetic disk having a plurality of tracks, including an inner track at an inside diameter of said disk and an outer track at an outside diameter of said disk;
• calculating a channel bit density of servo sector information at said inner track;
• calculating a channel bit density of servo sector information at said outer track;
• calculating an overall range of channel bit densities, wherein said overall range is equal to the difference in channel bit densities between said channel bit densities at said inner and outer tracks;
• dividing said range into N zones, each having a range Z of channel bit densities that are about equal to one another;
• and
• shaping a signal derived from servo sector information located within one of said N zones according to a corresponding one of N pulse shaping schemes, wherein at least a first of said N pulse shaping schemes is optimized to detect a signal derived from servo sector information associated with a track located within a corresponding first of said zones having a channel bit density about equal to an average channel bit density in said first zone.

A method for allocating servo sector zones in a rotating storage device, comprising:

• providing a magnetic disk having a plurality of tracks, including an inner track at an inside diameter of said disk and an outer track at an outside diameter of said disk;
• calculating a channel bit density of servo sector information at said inner track;
• calculating a channel bit density of servo sector information at said outer track;
• calculating an overall range of channel bit densities, wherein said overall range is equal to the difference in channel bit densities between said channel bit densities at said inner and outer tracks;
• dividing said range into N zones, each having a range Z of channel bit densities that are about equal to one another;
• and
• shaping a signal derived from servo sector information located within one of said N zones according to a corresponding one of N pulse shaping schemes, wherein at least a first of said N pulse shaping schemes is optimized to detect a signal derived from servo sector information associated with a middle track within a corresponding first of said zones.

A method for allocating servo sector zones in a rotating storage device, comprising:

• providing a magnetic disk having a plurality of tracks, including an inner track at an inside diameter of said disk and an outer track at an outside diameter of said disk;
• calculating a channel bit density of servo sector information at said inner track;
• calculating a channel bit density of servo sector information at said outer track;
• calculating an overall range of channel bit densities, wherein said overall range is equal to the difference in channel bit densities between said channel bit densities at said inner and outer tracks;
• dividing said range into N zones, each having a range Z of channel bit densities that are about equal to one another;
• and
• shaping a signal derived from servo sector information located within one of said N zones according to a corresponding one of N pulse shaping schemes, wherein at least a first of said N pulse shaping schemes is optimized to detect a signal derived from servo sector information associated with a track located within a first of said zones having a channel bit density about equal to a middle channel bit density of said first zone, and wherein at least a second of said N pulse shaping schemes is optimized to detect a signal from servo sector information associated with a middle track of a second of said zones.

A method for allocating servo sector zones in a rotating storage device, comprising:

• providing a magnetic disk having a plurality of tracks, including an inner track at an inside diameter of said disk and an outer track at an outside diameter of said disk;
• calculating a channel bit density of servo sector information at said inner track;
• calculating a channel bit density of servo sector information at said outer track;
• calculating an overall range of channel bit densities, wherein said overall range is equal to the difference in channel bit densities between said channel bit densities at said inner and outer tracks;
• dividing said range into N zones, each having a range Z of channel bit densities that are about equal to one another;
• and
• shaping a signal derived from servo sector information located within one of said N zones according to a corresponding one of N pulse shaping schemes, wherein at least a first of said N pulse shaping schemes is optimized to detect a signal derived from servo sector information associated with a track located within a first of said zones having a channel bit density about equal to an average channel bit density of said first zone, and wherein at least a second of said N filters is optimized to detect a signal from servo sector information associated with a middle track of a second of said zones.

A disk drive having optimized servo sector zones, comprising:

• a base;
• a magnetic storage disk assembly mounted to said base, wherein data is stored on said storage disk magnetically in concentric tracks, wherein said tracks each contain a plurality of servo sectors;
• an actuator arm pivotally mounted to said base;
• a transducer head mounted to a first end of said actuator arm, wherein said transducer head is capable of reading information from and writing information to said magnetic storage disk;
• a voice coil motor for moving said first end of said actuator arm radially across said magnetic storage disk, wherein said transducer head is capable of addressing said concentric tracks;
• a controller for actuating said voice coil motor to position said transducer head over a selected concentric track;
• a detector;
• and
• a channel for transmitting a signal from said transducer head to said detector, wherein a signal read by said transducer head and derived from at least a first servo sector located in a first zone is conditioned according to a first scheme, wherein a signal read by said transducer head and derived from at least a second servo sector located in a second zone is conditioned according to a second scheme, wherein said first zone is located towards an outer diameter of said magnetic storage disk, wherein said second zone is located towards an inner diameter of said magnetic storage disk, wherein said first zone contains more tracks than said second zone, and wherein said first scheme is optimized for a signal derived from a servo sector associated with a track located at a middle diameter of said first zone.

A disk drive having optimized servo sector zones, comprising:

• a base;
• a magnetic storage disk assembly mounted to said base, wherein data is stored on said storage disk magnetically in concentric tracks, wherein said tracks each contain a plurality of servo sectors;
• an actuator arm pivotally mounted to said base;
• a transducer head mounted to a first end of said actuator arm, wherein said transducer head is capable of reading information from and writing information to said magnetic storage disk;
• a voice coil motor for moving said first end of said actuator arm radially across said magnetic storage disk, wherein said transducer head is capable of addressing said concentric tracks;
• a controller for actuating said voice coil motor to position said transducer head over a selected concentric track;
• a detector;
• and
• a channel for transmitting a signal from said transducer head to said detector, wherein a signal read by said transducer head and derived from at least a first servo sector located in a first zone is conditioned according to a first scheme, wherein a signal read by said transducer head and derived from at least a second servo sector located in a second zone is conditioned according to a second scheme, wherein said first zone is located towards an outer diameter of said magnetic storage disk, wherein said second zone is located towards an inner diameter of said magnetic storage disk, wherein said first zone contains more tracks than said second zone, and wherein said first scheme is optimized for a signal derived from a servo sector associated with a track having a channel bit density equal to an average channel bit density of said first zone.

A disk drive having optimized servo sector zones, comprising:

• a base;
• a magnetic storage disk assembly mounted to said base, wherein data is stored on said storage disk magnetically in concentric tracks, wherein said tracks each contain a plurality of servo sectors;
• an actuator arm pivotally mounted to said base;
• a transducer head mounted to a first end of said actuator arm, wherein said transducer head is capable of reading information from and writing information to said magnetic storage disk;
• a voice coil motor for moving said first end of said actuator arm radially across said magnetic storage disk, wherein said transducer head is capable of addressing said concentric tracks;
• a controller for actuating said voice coil motor to position said transducer head over a selected concentric track;
• a detector;
• and
• a channel for transmitting a signal from said transducer head to said detector, wherein a signal read by said transducer head and derived from at least a first servo sector located in a first zone is conditioned according to a first scheme, wherein a signal read by said transducer head and derived from at least a second servo sector located in a second zone is conditioned according to a second scheme, wherein said first zone is located towards an outer diameter of said magnetic storage disk, wherein said second zone is located towards an inner diameter of said magnetic storage disk, wherein said first zone contains more tracks than said second zone, and wherein said second scheme is optimized for a signal derived from a servo sector associated with a track located at a middle diameter of said second zone.

A disk drive having optimized servo sector zones, comprising:

• a base;
• a magnetic storage disk assembly mounted to said base, wherein data is stored on said storage disk magnetically in concentric tracks, wherein said tracks each contain a plurality of servo sectors;
• an actuator arm pivotally mounted to said base;
• a transducer head mounted to a first end of said actuator arm, wherein said transducer head is capable of reading information from and writing information to said magnetic storage disk;
• a voice coil motor for moving said first end of said actuator arm radially across said magnetic storage disk, wherein said transducer head is capable of addressing said concentric tracks;
• a controller for actuating said voice coil motor to position said transducer head over a selected concentric track;
• a detector;
• and
• a channel for transmitting a signal from said transducer head to said detector, wherein a signal read by said transducer head and derived from at least a first servo sector located in a first zone is conditioned according to a first scheme, wherein a signal read by said transducer head and derived from at least a second servo sector located in a second zone is conditioned according to a second scheme, wherein said first zone is located towards an outer diameter of said magnetic storage disk, wherein said second zone is located towards an inner diameter of said magnetic storage disk, wherein said first zone contains more tracks than said second zone, and wherein said second scheme is optimized for a signal derived from a servo sector associated with a track having a channel bit density equal to an average channel bit density of said second zone.

A disk drive having optimized servo sector zones, comprising:

• a base;
• a magnetic storage disk assembly mounted to said base, wherein data is stored on said storage disk magnetically in concentric tracks, wherein said tracks each contain a plurality of servo sectors;
• an actuator arm pivotally mounted to said base;
• a transducer head mounted to a first end of said actuator arm, wherein said transducer head is capable of reading information from and writing information to said magnetic storage disk;
• a voice coil motor for moving said first end of said actuator arm radially across said magnetic storage disk, wherein said transducer head is capable of addressing said concentric tracks;
• a controller for actuating said voice coil motor to position said transducer head over a selected concentric track;
• a detector;
• and
• a channel for transmitting a signal from said transducer head to said detector, wherein a signal read by said transducer head and derived from at least a first servo sector located in a first zone is conditioned according to a first scheme, wherein a signal read by said transducer head and derived from at least a second servo sector located in a second zone is conditioned according to a second scheme, wherein said first zone is located towards an outer diameter of said magnetic storage disk, wherein said second zone is located towards an inner diameter of said magnetic storage disk, wherein said first zone contains more tracks than said second zone, and wherein said second scheme is optimized for a signal derived from a servo sector associated with a track having a channel bit density equal to a middle channel bit density of said second zone.

A disk drive having optimized servo sector zones, comprising:

• a base;
• a magnetic storage disk assembly mounted to said base, wherein data is stored on said storage disk magnetically in concentric tracks, wherein said tracks each contain a plurality of servo sectors;
• an actuator arm pivotally mounted to said base;
• a transducer head mounted to a first end of said actuator arm, wherein said transducer head is capable of reading information from and writing information to said magnetic storage disk;
• a voice coil motor for moving said first end of said actuator arm radially across said magnetic storage disk, wherein said transducer head is capable of addressing said concentric tracks;
• a controller for actuating said voice coil motor to position said transducer head over a selected concentric track;
• a detector;
• and
• a channel for transmitting a signal from said transducer head to said detector, wherein a signal read by said transducer head and derived from at least a first servo sector located in a first zone is conditioned according to a first scheme, wherein a signal read by said transducer head and derived from at least a second servo sector located in a second zone is conditioned according to a second scheme, wherein said first zone is located towards an outer diameter of said magnetic storage disk, wherein said second zone is located towards an inner diameter of said magnetic storage disk, wherein said first zone contains more tracks than said second zone, and wherein a range of channel bit densities of said first zone is about equal to a range of channel bit densities of said second zone.