US 5,689,384 A · Timing based servo system for magnetic tape systems

A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:

a head assembly having at least one servo read head for reading the servo pattern on the storage medium in a transducing direction and generating a read head signal representative of the servo pattern;
a servo decoder that receives the read head signal and decodes it to generate a position signal that indicates the position of the read head relative to the servo pattern;
a translation assembly that is activated to position the head assembly relative to the storage medium;
and
a servo controller that activates the translation assembly in accordance with the position signal;
the servo decoder including means for decoding a read head signal produced from a servo pattern that comprises a cyclic sequence of magnetic flux transitions that extend continuously across the width of the track and define servo pattern stripes such that the servo read head signal varies as the magnetic head is moved across the width of the track, the stripes including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation, and the servo decoder includes means for determining time intervals between a plurality of predetermined pairs of transitions in the servo pattern and generating a substantially speed invariant position signal that is a function of the time intervals.

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A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:

a head assembly having at least one servo read head for reading the servo pattern on the storage medium in a transducing direction and generating a read head signal representative of the servo pattern;
a servo decoder that receives the read head signal and decodes it to generate a position signal that indicates the position of the read head relative to the servo pattern;
a translation assembly that is activated to position the head assembly relative to the storage medium;
and
a servo controller that activates the translation assembly in accordance with the position signal;
the servo decoder including means for decoding a read head signal produced from a servo pattern that comprises a cyclic sequence of magnetic flux transitions that extend continuously across the width of the track and define servo pattern stripes such that the servo read head signal varies as the servo read head is moved across the width of the track, the stripes including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation, such that the servo decoder means for decoding decodes a read head signal representative of a pattern in which the stripes are arranged in groups containing a plurality of sequential stripes at the first azimuthal orientation followed by a plurality of sequential stripes at the second azimuthal orientation.

3 more elements

A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:

a head assembly having at least one servo read head for reading the servo pattern on the storage medium in a transducing direction and generating a read head signal representative of the servo pattern;
a servo decoder that receives the read head signal and decodes it to generate a position signal that indicates the position of the read head relative to the servo pattern;
a translation assembly that is activated to position the head assembly relative to the storage medium;
and
a servo controller that activates the translation assembly in accordance with the position signal;
the servo decoder including means for decoding a read head signal produced from a servo pattern that comprises a cyclic sequence of magnetic flux transitions that extend continuously across the width of the track and define servo pattern stripes such that the servo read head signal varies as the servo read head is moved across the width of the track, the stripes including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation, such that the servo decoder means for decoding decodes a read head signal representative of a pattern in which the stripes are arranged in groups containing a plurality of sequential stripes at the first azimuthal orientation followed by a plurality of sequential stripes at the second azimuthal orientation;
wherein the servo decoder means for decoding decodes a read head signal produced from a servo pattern having stripes that are arranged in groups having a plurality of sequential stripes at a first orientation followed by a plurality of sequential stripes at a second orientation and that are separated by synchronization features detectable by the servo decoder;
wherein the synchronization features of the servo pattern comprise transition-free spaces that are free of transitions of at least one polarity and whose minimum length in the transducing direction exceeds the maximum length in the transducing direction between consecutive transitions of that polarity within a group of stripes of the same azimuthal orientation;
and
wherein each pattern period of the cyclic sequence of transitions comprises a plurality of groups of stripes, each group containing stripes of a single azimuthal orientation and at least one group within a period contains a different number of stripes from the number contained within the other groups.

7 more elements

A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:

a head assembly having at least one servo read head for reading the servo pattern on the storage medium in a transducing direction and generating a read head signal representative of the servo pattern;
a servo decoder that receives the read head signal and decodes it to generate a position signal that indicates the position of the read head relative to the servo pattern;
a translation assembly that is activated to position the head assembly relative to the storage medium;
and
a servo controller that activates the translation assembly in accordance with the position signal;
the servo decoder including means for decoding a read head signal produced from a servo pattern that comprises a cyclic sequence of magnetic flux transitions that extend continuously across the width of the track and define servo pattern stripes such that the servo read head signal varies as the servo read head is moved across the width of the track, the stripes including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation, such that the servo decoder means for decoding decodes a read head signal representative of a pattern in which the stripes are arranged in groups containing a plurality of sequential stripes at the first azimuthal orientation followed by a plurality of sequential stripes at the second azimuthal orientation;
wherein one or more pluralities of adjacent servo tracks on the storage medium form one or more servo track bands;
and
wherein adjacent servo tracks on the storage medium within a band comprise patterns that are reflections of one another in a line in the transducing direction, such that all transitions in a servo track band are continuous across the width of the band.

6 more elements

A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:

a head assembly having at least one servo read head for reading the servo pattern on the storage medium in a transducing direction and generating a read head signal representative of the servo pattern;
a servo decoder that receives the read head signal and decodes it to generate a position signal that indicates the position of the read head relative to the servo pattern;
a translation assembly that is activated to position the head assembly relative to the storage medium;
and
a servo controller that activates the translation assembly in accordance with the position signal;
the servo decoder including means for decoding a read head signal produced from a servo pattern that comprises a cyclic sequence of magnetic flux transitions that extend continuously across the width of the track and define servo pattern stripes such that the servo read head signal varies as the servo read head is moved across the width of the track, the stripes including at least a first azimuthal orientation and a second azimuthal orientation, such that the first azimuthal orientation is not parallel to the second azimuthal orientation and the stripes are arranged in groups containing a plurality of sequential subgroups, each subgroup containing stripes at more than one azimuthal orientation, the groups being separated by synchronization features detectable by the servo decoder.

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