Head to track alignment in a rotating head magnetic tape unit

Claim 2

In a rotating head magnetic tape unit, improved means for maintaining head to data track alignment, comprising: a length of magnetic tape having a longitudinal servo track recorded thereon, said servo track including a constant frequency pattern interrupted by sync marks of a distinctively different pattern which define the physical location of associated transverse data tracks, reading means including said rotating head operable to read a section of said servo track as said head sweeps across said servo track, reversible means controlled by said reading means and operable to accumulate a count during said sweep, which count bears a known relationship to said constant frequency pattern, and counter control means controlled by said reading means and operable to change the counting sense of said counter means in accordance with the time of occurrence of said sync marks, such that the residual count in said counter means at the end of said sweep is a measure of the alignment of said head with a data track.

Claim 3

The rotating head tape unit defined in claim 1 wherein a single sync mark defines the center of a data track, and wherein said counter control means is operable to change the counting sense of said counter means upon detection of a sync mark.

Claim 4

The rotating head tape unit as defined in claim 2 wherein said single sync mark is physically located to define the center of a data track.

Claim 5

The rotating head tape unit as defined in claim 3 including tape servo means operable to control tape position in accordance with said residual count.

Claim 6

The rotating head tape unit defined in claim 1 wherein two spaced sync marks define the center of a data track, wherein the detection of the first sync mark enables said counter means, wherein the detecting of the second sync mark inhibits said counter means, and wherein a maximum amplitude signal from said rotating head is operable to change the counting sense of said counter means.

Claim 7

The rotating head tape unit defined in claim 5 wherein said maximum amplitude signal from said rotating head is detected by a threshold detecting network.

Claim 8

The rotating head tape unit defined in claim 6 including tape servo means operable to control tape motion in accordance with said residual count.

Claim 9

The rotating head tape unit defined in claim 1 wherein said tape includes redundant servo tracks, each one of which separately defines the physical location of said data tracks.

Claim 10

In combination: a magnetic recording tape having a longitudinal control track recorded thereon, and adapted to have transverse data tracks extending at an angle to the control track, said control track being recorded with a format having sync magnetic states positioned to identify the physical location of the data tracks, a magnetic transducer movable across said tape at an angle corresponding to the angle of said data track, an up/down counter, constant frequency clock means having an output connected to be counted by said counter, counter control means responsive to the output of said transducer as it reads said control track, said control means being operable to enable said counter to begin counting as said head begins to sweep across said control track, to thereafter change the counter''s state of counting in accordance with the relationship of said sync magnetic states to the path followed by said transducer, and to thereafter inhibit said counter as said head completes said sweep across said control track, and means operable afteR said counter is inhibited to decode the residual state of said counter as a measure of the alignment of said transducer with the data track whose position is identified by said sync magnetic states.

Claim 11

In combination: a magnetic recording tape having a longitudinal control track recorded thereon, and adapted to have transverse data tracks extending at an angle to the control track, said control track being recorded with a format having sync magnetic states positioned to identify the physical location of the data tracks, a magnetic transducer movable across said tape at an angle corresponding to the angle of said data track, an up/down counter, constant frequency clock means having an output connected to be counted by said counter, counter control means responsive to the output of said transducer as it reads said control track, said control means being operable to enable said counter to begin counting as said head begins to sweep across said control track, to thereafter change the counter''s state of counting in accordance with the relationship of said sync magnetic states to the path followed by said transducer, and to thereafter inhibit said counter as said head completes said sweep across said control track, and means operable afteR said counter is inhibited to decode the residual state of said counter as a measure of the alignment of said transducer with the data track whose position is identified by said sync magnetic states.

Claim 12

The combination defined in claim 9 wherein said control track includes a plurality of constant frequency clock magnetic states intermediate said sync magnetic states, and wherein said constant frequency clock means is defined by said clock magnetic states.

Claim 13

The combination defined in claim 10 wherein the position of each data track is identified by a single sync magnetic state, wherein said counter is enabled and thereafter inhibited by a minimum signal threshold detector responsive to the output of said transducer, and wherein the counter''s state of counting is changed upon the detection of said sync magnetic state.

Claim 14

The combination defined in claim 11 wherein each of said single sync magnetic states defines the center of one data track.

Claim 15

The combination defined in claim 12 including tape servo means controlled by the residual state of said counter and operable to control the position of said tape in accordance therewith.

Claim 16

The combination defined in claim 10 wherein the position of each data track is identified by first and second spaced sync magnetic states, and wherein said counter is enabled by said first sync magnetic state, is inhibited by said second sync magnetic state and the counter''s state of counting is changed upon the detection of a high signal amplitude in the output of said transducer.

Claim 17

The combination defined in claim 14 including tape servo means controlled by the residual state of said counter and operable to control the position of said tape in accordance therewith.

Claim 18

The combination defined in claim 9 wherein said tape includes a plurality of control tracks, each one of said separately defines the physical location of said data tracks.

Claim 19

Closed loop tape servo apparatus for use in controlling the relative tape-to-head position in a rotating head, transverse-recording magnetic tape unit, comprising: a tape processing station having a rotating head, a movable length of tape extending through said station, means applying tension to one end of said tape, motor means applying tension to the other end of said tape, said motor means being servo controllable to change the position of the tape''s transvere data tracks adjacent the path of said rotating head, at least one longitudinal servo track recorded on said tape and including distinctive sync patterns identifying the position of each transverse data track, an up/down counter, clock means connected to selectively increment or decrement said counter, control means connected to control said counter and to be controlled by said rotating head, said control means being responsive to the head signal envelope and said sync patterns during the time that the head sweeps across said servo track to cause said counter to count up for a portion of this time and to count down for a portion of this time, the respective time portions being determined by he positional relationship of the servo track''s sync patterns to said rotating head path, and servo means connecting the residual count within said counter at the end of said sweep to control the energization of said motor means in a sense to reduce said residual count to a given value.

Claim 20

Closed loop tape servo apparatus for use in controlling the relative tape-to-head position in a rotating head, transverse-recording magnetic tape unit, comprising: a tape processing station having a rotating head, a movable length of tape extending through said station, means applying tension to one end of said tape, motor means applying tension to the other end of said tape, said motor means being servo controllable to change the position of the tape''s transvere data tracks adjacent the path of said rotating head, at least one longitudinal servo track recorded on said tape and including distinctive sync patterns identifying the position of each transverse data track, an up/down counter, clock means connected to selectively increment or decrement said counter, control means connected to control said counter and to be controlled by said rotating head, said control means being responsive to the head signal envelope and said sync patterns during the time that the head sweeps across said servo track to cause said counter to count up for a portion of this time and to count down for a portion of this time, the respective time portions being determined by he positional relationship of the servo track''s sync patterns to said rotating head path, and servo means connecting the residual count within said counter at the end of said sweep to control the energization of said motor means in a sense to reduce said residual count to a given value.

Claim 21

The servo apparatus of claim 17 including means operable to rotate said head at a known constant speed.

Claim 22

The servo apparatus defined in claim 18 wherein said clock means includes a constant frequency data pattern as a portion of said servo track.

Claim 23

The servo apparatus defined in claim 19 wherein each transverse data track is identified by a single sync pattern, and wherein said counter counts said constant frequency data pattern and changes its state of counting upon the detection of a single sync pattern.

Claim 24

The servo apparatus defined in claim 19 wherein each trAnsverse data track is identified by two spaced sync patterns, and wherein said counter means begins counting said constant frequency data pattern upon the detection of the first sync pattern and stops said counting upon the detection of the second sync pattern, the state of counting being changed therebetween upon the detection of a high amplitude signal from said rotating head.

Claim 25

The servo apparatus defined in claim 17 including a plurality of longitudinal servo tracks recorded on said tape, each track functioning to independently identify the position of each transverse data tracks.