Transducer positioning system for providing both coarse and fine positioning

Claim 2

A servo system for positioning a transducer means relative to a plurality of repeating groups of tracks provided at successive radial positions on a relatively moving recording medium, each group containing at least three tracks, said system comprising: positioning means for moving said transducer means transversely relative to said tracks; a plurality of servo data manifestations recorded in each track comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having a manifestation at either a first or a second location of the cell indicative of either a first or second value for the cell, the cells and said first and second locations thereof being respectively aligned for all tracks of each group, the cells being encoded so as to provide; (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations being recorded in each track so that traversal thereof by said transducer means produces detected signals indicative of the positioning of said transducer relative to two adjacent tracks; first detecting means responsive to the detection by said transducer means of the differently encoded coarse servo data manifestations provided in each track of a group of tracks for controlling said positioning means to provide for coarse positioning of said transducer means to a target track position; and second detecting means responsive to the detection by said transducer means of said fine servo data manifestations and operable upon completion of the coarse positioning of said transducer means by said first detecting means for controlling said positioning means so as to bring and maintain said transducer means in alignment with said target track position.

Claim 3

The invention in accordance with claim 1, wherein said first detecting means includes: first means providing an output indicative of the distance between the current track position of said transducer means and said target track position; and second means for updating said first means in accordance with the detected radial movement of said transducer means.

Claim 4

The invention in accordance with claim 1, wherein said second detecting means is activated in response to the output of said first means indicating that said transducer means has been coarse positioned to said target track position.

Claim 5

The invention in accordance with claim 1, wherein said recording medium is magnetic, wherein said transducer means is a magnetic head, and wherein said servo data manifestations are provided as magnetic transistions on said medium.

Claim 6

The invention in accordance with claim 4, wherein said first detecting means includes means responsive to the reading of said magnetic transitions by said magnetic head for producing for each cell traversed by said head: (a) a single electrical signal at a time corresponding to either said first or second location of a cell when said transducer means is approximately centered over a track, and (b) two electrical signals at times respectively corresponding to both of said first and second locations of a cell when said transducer means is between two adjacent tracks and is reading a cell whose value is different for the two adjacent tracks.

Claim 7

The invention in accordance with claim 4, wherein the fine servo magnetic transitions provided in each track comprises a fine servo transition recorded at only a first location with respect to said reference transition for even tracks and at only a second location with respect to said reference transition for odd tracks, and wherein said second detecting means provides a fine positioning control signal to said control means indicative of the position of said transducer means relative to a pair of adjacent tracks by comparing the amplitudes of the signals detected by said transducer means in response to said fine servo transitions at said first and second locations of said adjacent tracks.

Claim 8

The invention in accordance with claim 6, wherein said recording medium includes a rotatable disc in transducing relationship to said magnetic head, wherein said tracks are concentrically located on said disc, and wherein said positioning means is adapted to provide for radial movement of said head.

Claim 9

The invention in accordance with claim 7, wherein said servo data transitions are provided in servo data tracks located in predetermined spaced servo data sectors of said disc.

Claim 10

The invention in accordance with claim 8, wherein work data is recorded on and reproduced from work data tracks in work data sectors located between said servo data sectors on said disc.

Claim 11

The invention in accordance with claim 9, wherein the number of servo data tracks provided in each group is chosen to be greater than the maximum radial movement of said magnetic head between servo sectors.

Claim 12

The invention in accordance with claim 10, wherein said first detecting means includes: counting means providing a count indicative of the radial distance between the current track position of said magnetic head and a target track; and means responsive to said electrical signals for determining current track position of said head relative to its respective group and for changing the count of said counting means in accordance with the radial distance that the head has moved since the previous servo sector.

Claim 13

The invention in accordance with claim 11, wherein additional means are provided operative after activation of said second detecting means and responsive to the servo data manifestations detected by said magnetic head for controlling said positioning means to return said magnetic head to said target track in response to said counting means indicating that said head has moved a predetermined radial distance from the target track after having arrived at the target track.

Claim 14

The invention in accordance with claim 12, wherein further means are provided operative after activation of said second detecting means for setting said counting means to a count indicative of a new track position to which said head is to be repositioned.

Claim 15

A recording and reproducing medium for use in a servo system for positioning a relatively moving transducer means transversely with respect to a plurality of groups of tracks provided on said medium, each group containing at least three tracks, each track having servo data manifestations comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestations; said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having a manifestation at either a first or a second location of the cell indicative of either a first or a second value for the cell, the cells and said first and second locations thereof being respectively aligned for all tracks of each group, the cells of the tracks of each group being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence for each group of tracks chosen so that the value of only one cell is different on adjacent tracks; said fine servo data manifestations recorded in each track comprising a first fine servo manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transistion for odd tracks.

Claim 16

A recording and reproducing medium for use in a servo system for positioning a relatively moving transducer means transversely with respect to a plurality of groups of tracks provided on said medium, each group containing at least three tracks, each track having servo data manifestations comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestations; said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having a manifestation at either a first or a second location of the cell indicative of either a first or a second value for the cell, the cells and said first and second locations thereof being respectively aligned for all tracks of each group, the cells of the tracks of each group being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence for each group of tracks chosen so that the value of only one cell is different on adjacent tracks; said fine servo data manifestations recorded in each track comprising a first fine servo manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transistion for odd tracks.

Claim 17

The invention in accordance with claim 14, wherein said encoding sequence employs a Gray code.

Claim 18

The invention in accordance with claim 15, wherein said recording medium is a magnetic disc, wherein said tracks are concentrically located on said disc, and wherein each of said servo data manifestations is provided as a magnetic transition.

Claim 19

In a method for positioning a transducer means transversely relative to a plurality of groups of tracks provided at successive radial positions on a relatively moving recording medium, each group containing at least three tracks, the improvement comprising: recording servo data manifestations in each track so as to provide a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having a manifestation at either a first or a second location of the cell indicative of either a first or second value for the cell, the cells and said first and second locations thereof being respectively aligned for all tracks of each group, the cells being encoded so as to provide (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations recorded in each track comprising a manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks.

Claim 20

In a method for positioning a transducer means transversely relative to a plurality of groups of tracks provided at successive radial positions on a relatively moving recording medium, each group containing at least three tracks, the improvement comprising: recording servo data manifestations in each track so as to provide a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having a manifestation at either a first or a second location of the cell indicative of either a first or second value for the cell, the cells and said first and second locations thereof being respectively aligned for all tracks of each group, the cells being encoded so as to provide (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations recorded in each track comprising a manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks.

Claim 21

The invention in accordance with claim 17, wherein said recording medium is magnetic, and wherein said servo data manifestations are recorded in said medium as magnetic transitions.

Claim 22

The invention in accordance with claim 18, wherein work data and servo data are recorded in alternate sectors of said magnetic disc.

Claim 23

In a method for positioning a magnetic transducer means transversely relative to a plurality of concentric tracks provided on a rotatable magnetic disc, the improvement comprising: recording work data and servo data in alternate sectors of a magnetic disc, said servo data recorded in each track comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having a manifestation at either a first or a second location of the cell indicative of either a first or second value for the cell, the cells and said first and second locations thereof being respectively aligned for all tracks of each group, the cells being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations recorded in each track comprising a first manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks; providing an indication of the number of tracks and direction that said transducer means is to be moved from its current track position to a target track position; moving said transducer means in said direction towards said target track; detecting during said moving the current track position of said transducer means by detecting the coarse servo magnetic transitions traversed thereby during a servo sector, the number of servo tracks provided in each group being chosen greater than the maximum radial movement of said transducer means between servo sectors; updating said indication during each sector based on the difference between the current detected position of said transducer means and that detected during the previous servo sector; determining arrival of said transducer means at said target track position in response to said indication; detecting said fine servo transitions after arrival of said transducer means at said target track position; and moving said transducer means in response to the detecting of said fine servo transitions to precisely position and maintain said transducer means in alignment with said target track position.

Claim 24

In a method for positioning a magnetic transducer means transversely relative to a plurality of concentric tracks provided on a rotatable magnetic disc, the improvement comprising: recording work data and servo data in alternate sectors of a magnetic disc, said servo data recorded in each track comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having a manifestation at either a first or a second location of the cell indicative of either a first or second value for the cell, the cells and said first and second locations thereof being respectively aligned for all tracks of each group, the cells being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations recorded in each track comprising a first manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks; providing an indication of the number of tracks and direction that said transducer means is to be moved from its current track position to a target track position; moving said transducer means in said direction towards said target track; detecting during said moving the current track position of said transducer means by detecting the coarse servo magnetic transitions traversed thereby during a servo sector, the number of servo tracks provided in each group being chosen greater than the maximum radial movement of said transducer means between servo sectors; updating said indication during each sector based on the difference between the current detected position of said transducer means and that detected during the previous servo sector; determining arrival of said transducer means at said target track position in response to said indication; detecting said fine servo transitions after arrival of said transducer means at said target track position; and moving said transducer means in response to the detecting of said fine servo transitions to precisely position and maintain said transducer means in alignment with said target track position.

Claim 25

A servo system for positioning a transducer means relative to a group of at least three tracks provided on a relatively moving recording medium, said system comprising: positioning means for moving said transducer means transversely relative to said tracks; a plurality of servo data manifestations recorded in each track comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having either a first or second value, the cells being respectively aligned for all tracks of each group and being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells; and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations being recorded in each track so that traversal thereof by said transducer means produces detected signals indicative of the positioning of said transducer relative to two adjacent tracks; first detecting means responsive to the detection by said transducer means of the differently encoded coarse servo data manifestations provided in each track of said group of tracks for controlling said positioning means to provide for coarse positioning of said transducer means to a target track position; and second detecting means responsive to the detection by said transducer means of said fine servo data manifestations and operable upon completion of the coarse positioning of said transducer means by said first detecting means for controlling said positioning means so as to bring and maintain said transducer means in alignment with said target track position.

Claim 26

A servo system for positioning a transducer means relative to a group of at least three tracks provided on a relatively moving recording medium, said system comprising: positioning means for moving said transducer means transversely relative to said tracks; a plurality of servo data manifestations recorded in each track comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having either a first or second value, the cells being respectively aligned for all tracks of each group and being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells; and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations being recorded in each track so that traversal thereof by said transducer means produces detected signals indicative of the positioning of said transducer relative to two adjacent tracks; first detecting means responsive to the detection by said transducer means of the differently encoded coarse servo data manifestations provided in each track of said group of tracks for controlling said positioning means to provide for coarse positioning of said transducer means to a target track position; and second detecting means responsive to the detection by said transducer means of said fine servo data manifestations and operable upon completion of the coarse positioning of said transducer means by said first detecting means for controlling said positioning means so as to bring and maintain said transducer means in alignment with said target track position.

Claim 27

A recording and reproducing medium for use in a servo system for positioning a relatively moving transducer means transversely with respect to a plurality of groups of tracks provided at successive radial positions on said medium, each track having servo data manifestations comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation; said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having either a first or a second value, the cells of the tracks of each group being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence for each group of tracks chosen so that the value of only one cell is different on adjacent tracks; said fine servo data manifestations recorded in each track comprising a first fine servo manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks.

Claim 28

A recording and reproducing medium for use in a servo system for positioning a relatively moving transducer means transversely with respect to a plurality of groups of tracks provided at successive radial positions on said medium, each track having servo data manifestations comprising a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation; said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having either a first or a second value, the cells of the tracks of each group being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence for each group of tracks chosen so that the value of only one cell is different on adjacent tracks; said fine servo data manifestations recorded in each track comprising a first fine servo manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks.

Claim 29

In a method for positioning a transducer means transversely relative to a plurality of groups of tracks provided on a relatively moving recording medium, the improvement comprising: recording servo data manifestations in each track so as to provide a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having either a first or second value, the cells being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations recorded in each track comprising a manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks.

Claim 30

In a method for positioning a transducer means transversely relative to a plurality of groups of tracks provided on a relatively moving recording medium, the improvement comprising: recording servo data manifestations in each track so as to provide a like located reference manifestation and spaced fine servo data manifestations and coarse servo data manifestations precisely located relative to said reference manifestation, said coarse servo data manifestations being recorded in each track so as to constitute a plurality of adjacent cells each having either a first or second value, the cells being encoded so as to provide: (a) a different identifying representation for each track of a group so that each track of the group is identifiable from the coding provided for its respective plurality of adjacent cells, and (b) an encoding sequence chosen for each group of tracks so that the value of only one cell is different on adjacent tracks, said fine servo data manifestations recorded in each track comprising a manifestation provided at a first location with respect to said reference manifestation for even tracks and at a second location with respect to said reference transition for odd tracks.