# US 5,710,673 A · Azimuth record head for minimizing and equalizing crosstalk between tracks of opposite azimuths

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- Number: US 5,710,673 A
- Document ID: US5710673A
- Status: Granted
- Kind: A
- Application number: 08/660,355
- Filed: 1996-06-07
- Granted: 1998-01-20
- Earliest claimed: 1996-06-07
- Assignees: Ampex Corporation
- Inventors: George R. Varian
- Web page: https://patentgrep.com/patent/US5710673A

## CPC

- G11B 5/53: Disposition or mounting of heads on rotating support
- G11B 5/0086: {using cyclically driven heads providing segmented tracks}
- G11B 5/02: Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
- G11B 5/187: Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features (G11B5/265, {G11B5/29} , G11B5/31 take precedence)
- G11B 5/23: Gap features {(G11B5/1871, G11B5/1875, G11B5/265, G11B5/29, G11B5/488 and subgroups, G11B5/4907 and subgroups, G11B5/4969 and subgroups take precedence)}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

In an azimuth recording format, the crosstalk of the A channel into the B channel is higher than the crosstalk of the B channel into the A channel because, at the ends of a magnetic recording where the switching contour of constant magnetic field strength is equal to the media magnetization switching field, the switching contour follows a curve. The resulting curvature at the ends of the magnetic recording vary accordingly the angle of azimuth rejection between the B to A azimuth relative to the A to B azimuth at the edges of the track. The use of a record head of a unique design wherein the trailing pole face of the head extends laterally beyond its leading pole face at the over-writing side of the head, removes the curvature at the ends of the transition recordings forming the recorded tracks. In such record heads, the switching contour generated at the trailing pole face of the gap at the over-writing side of the head enters and exits the trailing core generally normal to the pole face and at points thereon which are spaced beyond the corresponding end of the leading core face. Thus, no curvature is generated at the end of the recordings which perform over-writing of the previous adjacent tracks recorded in the media. Thus, the record heads show the same minimized level of crosstalk between the A to B or the B to A azimuth channels.

## Claims

### Claim 1

A record head for providing an azimuth recording format of magnetic tracks of a selected width in a magnetic media while generating minimized and equal crosstalk between the tracks upon subsequent readout of the tracks, wherein over-writing of a previous track is performed by an over-writing side of the head, comprising:
a first magnetic material core having a first pole face of a preselected width formed therein;
a second magnetic material core having a second pole face of a second preselected width formed therein;
said first and second cores being bonded together with the faces thereof in generally confronting relation to define a magnetic gap of selected gap length therebetween, with the second pole face of the second core extending beyond the first pole face of the first core at said over-writing side; and
said record head being oriented during the recording process with the second pole face of the second core trailing the first pole face of the first core.

### Claim 2 (depends on 1)

The record head of claim 1 including:
a contour of constant magnetic field strength generated between said confronting pole faces in the region of the magnetic gap, said contour extending generally along said trailing pole face beyond the end of said leading pole face at said over-writing side of the head.

### Claim 3 (depends on 2)

The record head of claim 2 wherein the second core extends in width at said over-writing side a distance sufficient to generate the contour of constant magnetic field strength in a straight line along the extended trailing pole face.

### Claim 4 (depends on 3)

The record head of claim 3 wherein the side of the second core relative to the corresponding side of the first core at the non-over-writing side, are generally in register or the leading pole face extends laterally beyond the trailing pole face.

### Claim 5 (depends on 3)

The record head of claim 3 wherein the trailing pole face of the second core extends beyond the leading pole face of the first core by an amount greater than a gap length.

### Claim 6 (depends on 5)

The record head of claim 5 wherein the head is moved transversely a distance equal to a track pitch after recording a track, wherein the trailing pole face has a width of at least a track pitch through a width of the leading pole face plus at least the gap length.

### Claim 7 (depends on 2)

The record head of claim 2 including:
transport means for moving the record head relative to the media with the record head oriented so that the second core trails the first core, and said over-writing side overlaps a previously recorded track on a subsequent adjacent track recording to define the track width.

### Claim 8

A record head for providing an azimuth recording of magnetic tracks of a selected width and track pitch in a magnetic media while generating minimized and equal crosstalk between the recorded tracks upon their subsequent readout, the record head including a pair of bonded magnetic cores having a transducing gap of selected gap length formed therebetween by a first facing edge of preselected width in a first core in generally confronting relation with a second facing edge of second preselected width in a second core, comprising:
means for orienting the record head relative to the magnetic media to cause an over-writing side of the head to overlap and thus over-write a portion of a previous track to generate the azimuth recording;
said second core being laterally offset relative to said first core at said over-writing side of the head so that the second facing edge extends laterally beyond the end of the first facing edge a preselected distance at said over-writing side; and
transport means for moving the record head relative to the media with the second facing edge trailing the first facing edge to provide the partially over-written recorded tracks in the media.

### Claim 9 (depends on 8)

The record head of claim 8 including:
a contour of constant magnetic field strength generated within the transducing gap and extending generally in a straight line along the laterally extended second facing edge of the second core at the over-writing side.

### Claim 10 (depends on 9)

The record head of claim 9 wherein:
said second facing edge extends beyond the end of the first facing edge of the first core at the over-writing side by an amount equal to at least a gap length.

### Claim 11 (depends on 10)

The record head of claim 10 wherein:
said second facing edge of the second core, at the non-over-writing side, is in general register with the first facing edge or is shy of the first facing edge of the first core; and
the confronting portions of the first and second facing edges forming the transducing gap have a width equal to or greater than the track pitch.

### Claim 12

A method of providing an azimuth recording of magnetic tracks of selected track pitch in a magnetic media while generating minimized and equal crosstalk between the tracks upon their subsequent readout, utilizing a record head whose transducing gap is of a given gap length and is formed with a first facing edge of preselected width in generally confronting relation with a second facing edge of a second preselected width, comprising the steps of:
orienting the record head relative to the magnetic media to provide the azimuth recording, wherein an adjacent portion of a previously recorded track is over-written by an over-writing side of the head on a next head pass;
generating at the over-writing side of the head a generally straight switching contour of constant magnetic field strength extending at least a gap length beyond the first facing edge; and
moving the record head relative to the magnetic media with the straight switching contour at the over-writing side of the head overlapping the adjacent portion of the previously recorded track, to provide the azimuth recording of recorded tracks in the media.

### Claim 13 (depends on 12)

The method of claim 12 wherein the step of generating includes:
generating the generally straight switching contour of constant magnetic field strength along the second facing edge and extending at the overwriting side beyond the preselected width of the first facing edge said at least gap length.

### Claim 14 (depends on 13)

The method of claim 13 wherein the width of the confronting portions of the first and second facing edges is at least as wide as the track pitch, and the step of moving includes recording successive adjacent tracks while overlapping with said straight switching contour at the over-writing side the previously recorded track to thus reduce the width of each previously recorded track.

### Claim 15 (depends on 13)

The method of claim 13 wherein the second facing edge is the trailing edge of the transducing gap.

### Claim 16

A method of recording an azimuth recording of recorded tracks of selected track pitch and of selected width in a magnetic media via a transducing gap of selected length while generating minimized and generally equal crosstalk between the tracks upon a subsequent readout process, comprising;
generating via the transducing gap a generally straight switching contour of constant magnetic field strength representing a bit of data;
generating at an over-writing side of the transducing gap an extension of the straight switching contour of at least the selected length of the gap; and
successively recording the generally straight switching contour in the magnetic media with at least the extension of the straight switching contour overlapping and thus over-writing a portion of a previously recorded track to record successive substantially straight transition recordings defining said azimuth recording.

### Claim 17 (depends on 16)

The method of claim 16 wherein said transducing gap is formed of a first facing edge of preselected width in generally confronting relation with a second facing edge of a second width, the method including;
generating the extension of the straight switching contour along the second facing edge the gap length beyond the first facing edge at the over-writing side of the gap; and
moving the transducing gap relative to the magnetic media with the second facing edge trailing the first facing edge to over-write with the extension the adjacent edge of the previously recorded track.