Magnetic disc apparatus with thin film head suitable for high-density recording

A magnetic disc apparatus comprising:

• a magnetic disc for recording thereon information at a track density Tr of 1800 or more tracks per inch;
• and
• a thin film magnetic head having a main surface facing said magnetic disc and including a magnetic pole structure having an upper magnetic pole tip and a lower magnetic pole tip disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from said magnetic disc by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is longer than a side of said upper tip face extending along said magnetic gap at each of opposite ends thereof by a difference .DELTA.CW' expressed in .mu.m which satisfies a relation
• 0.1.ltoreq..DELTA.CW'.ltoreq.2500/Tr.

A magnetic disc apparatus comprising:

• a magnetic disc for recording thereon information at a track density Tr of 1800 or more tracks per inch;
• and
• a thin film magnetic head having a main surface facing said magnetic disc and including a magnetic pole structure having an upper magnetic pole tip and a lower magnetic pole tip disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from said magnetic disc by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is different in length from a side of said upper tip face extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0.2.ltoreq..DELTA.CW.ltoreq.5000/Tr.

A magnetic disc apparatus comprising:

• a magnetic disc for recording thereon information at a track density Tr of 1800 or more tracks per inch;
• and
• a thin film magnetic head having a main surface facing said magnetic disc and including a magnetic pole structure having an upper magnetic pole tip and a lower magnetic pole tip disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from said magnetic disc by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap;
• said upper and lower magnetic pole tip having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is different in length from a side of said upper tip face extending along said magnetic gap at each of opposite ends thereof by a difference .DELTA.CW' expressed in .mu.m which satisfies a relation
• 0.1.ltoreq..DELTA.CW'.ltoreq.2500/Tr.

A thin film magnetic head for use with a magnetic disc adapted to record thereon information at a track density Tr of 1800 or more tracks per inch, said magnetic head comprising:

• a main surface which faces the magnetic disc when in use;
• and
• a magnetic core structure for providing a magnetic circuit having a magnetic gap extending across said main surface, said magnetic core structure having upper and lower magnetic pole tips made of magnetic material and disposed to provide said magnetic gap therebetween for at least one of writing and reading information in and from said magnetic disc by effectively utilizing fringe magnetic fields generated at opposite ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is different in length from a side of said upper tip face extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0.2.ltoreq..DELTA.CW.ltoreq.5000/Tr.

A recording system comprising:

• a head/disc assembly for performing at least one of magnetic write and read operations;
• a write/read circuit for switching between said write and read operations;
• and
• an interface for coupling said head/disc assembly to a host apparatus through said write/read circuit;
• said head/disc assembly including:
• a magnetic disc adapted for recording thereon information at a track density Tr of 1800 or more tracks per inch;
• and
• a thin film magnetic head having a main surface facing said magnetic disc and including a magnetic core structure having upper and lower magnetic pole tips disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from said magnetic disc by effectively utilizing fringe magnetic fields generated at opposite ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is different in length from a side of said upper tip face extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0.2.ltoreq..DELTA.CW.ltoreq.5000/Tr.

A method of recording and reproducing information on a magnetic disc adapted to record thereon information at a track density Tr of 1800 or more tracks per inch, said method comprising the steps of:

• rotating said magnetic disc;
• and
• recording information on said magnetic disc with a thin film magnetic head having a main surface disposed such that said main surface is facing said magnetic disc, said magnetic head including a magnetic core structure having upper and lower magnetic pole tips arranged to form therebetween a magnetic gap extending across said main surface, said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of one of said upper and lower tip faces extending along said magnetic different in length from a side of the other of said upper and lower tip faces extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0.2.ltoreq..DELTA.CW.ltoreq.5000/Tr.
• such that the information is recorded on the magnetic disc along a track by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap corresponding to the difference .DELTA.CW such that a width of the track is increased by the fringe magnetic fields;
• and
• reading information recorded on said magnetic disc with said magnetic head disposed such that said main surface is facing said magnetic disc and effectively utilizing a whole length of the magnetic pole tip having said one of said upper and lower tip faces.

A method of recording and reproducing information on a magnetic disc adapted to record thereon information at a track density Tr of 1800 or more tracks per inch, said method comprising the steps of:

• rotating said magnetic disc;
• recording information on said magnetic disc with a thin film magnetic head having a main surface disposed such that said main surface is facing said magnetic disc, said magnetic head including a magnetic core structure having upper and lower magnetic pole tips arranged to form therebetween a magnetic gap extending across said main surface, said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of one of said upper and lower tip faces extending along said magnetic different in length from a side of the other of said upper and lower tip faces extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0.2.ltoreq..DELTA.CW.ltoreq.5000/Tr.
• such that the information is recorded on the magnetic disc along a track by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap corresponding to the difference .DELTA.CW such that a width of the track is increased by the fringe magnetic fields;
• and
• reading information recorded on said magnetic disc with a magnetoresistance-type magnetic head.

A magnetic disc apparatus comprising:

• a magnetic disc for recording information thereon;
• and
• a thin film magnetic head for recording information on said magnetic disc at a track density Tr of 1800 or more tracks per inch, said magnetic head having a main surface facing said magnetic disc and including a magnetic core structure having upper and lower magnetic pole tips disposed to form a magnetic gap therebetween extending across said main surface, said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of one of said upper and lower tip faces extending along said magnetic gap is longer than a side of the other of said upper and lower tip faces extending along said magnetic gap at each of opposite ends thereof by a difference .DELTA.CW' expressed in .mu.m which satisfies a relation
• 0.1.ltoreq..DELTA.CW'.ltoreq.2500/Tr,
• such that fringe magnetic fields generated at opposite ends of said magnetic gap are effectively utilized for recording information on said magnetic disc.

A magnetic disc apparatus comprising:

• a magnetic disc for recording information thereon;
• a thin film magnetic head for recording information on said magnetic disc at a track density Tr of 1800 or more tracks per inch, said magnetic head having a main surface facing said magnetic disc and including a magnetic core structure having upper and lower magnetic pole tips disposed to form a magnetic gap therebetween extending across said main surface, said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of one of said upper and lower tip faces extending along said magnetic gap is longer than a side of the other of said upper and lower tip faces extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0. 2.ltoreq..DELTA.CW.ltoreq.5000/Tr.
• such that fringe magnetic fields generated at opposite ends of said magnetic gap are effectively utilized for recording information on said magnetic disc.

A magnetic disc apparatus comprising:

• a spindle;
• a plurality of magnetic discs rotatably mounted on said spindle, each of said magnetic discs for recording thereon information at a track density Tr of 1800 or more tracks per inch;
• and
• a plurality of thin film magnetic heads disposed to face associated ones of said magnetic discs, each of said magnetic heads having a main surface facing the associated magnetic disc and including a magnetic pole structure having an upper magnetic pole tip and a lower magnetic pole tip disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from the associated magnetic disc by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is different in length from a side of said upper tip face extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0.2.ltoreq..DELTA.CW.ltoreq.5000/Tr.

A magnetic disc apparatus comprising:

• a magnetic disc adapted for recording thereon information at a track density Tr of 1800 or more tracks per inch;
• and
• a thin film magnetic head having a main surface facing said magnetic disc and including a magnetic pole structure having an upper magnetic pole tips and a lower magnetic pole tip disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from said magnetic disc by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is longer than a side of said upper tip face extending along said magnetic gap at least one of opposite ends thereof by a difference .DELTA.CW' expressed in .mu.m which satisfies a relation
• 0.1.ltoreq..DELTA.CW'.ltoreq.2500/Tr,

A magnetic disc apparatus comprising:

• a magnetic disc for recording thereon information at a track density Tr of 2500 or more tracks per inch;
• and
• a thin film magnetic head having a main surface facing said magnetic disc and including a magnetic pole structure having an upper magnetic pole tip and a lower magnetic pole tip disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from said magnetic disc by effectively utilizing fringe magnetic fields generated at ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is longer than a side of said upper tip face extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0. 2.ltoreq..DELTA.CW.ltoreq.5000/Tr.

A magnetic disc apparatus comprising:

• a magnetic disc adapted for recording thereon information at a track density Tr of 1800 or more tracks per inch;
• and
• a thin film magnetic head having a main surface facing said magnetic disc and including a magnetic core structure having an upper magnetic pole tip and a lower magnetic pole tip disposed to form therebetween a magnetic gap extending across said main surface for at least one of writing and reading information in and from said magnetic disc by utilizing fringe magnetic fields generated at ends of said magnetic gap;
• said upper and lower magnetic pole tips having upper and lower tip faces, respectively, exposed on said main surface and adjacent to said magnetic gap, wherein a side of said lower tip face extending along said magnetic gap is longer than a side of said upper tip face extending along said magnetic gap by a difference .DELTA.CW expressed in .mu.m which satisfies a relation
• 0.2.ltoreq..DELTA.CW.ltoreq.5000/Tr.