U.S. patent application number 13/950180 was filed with the patent office on 2015-01-29 for stitched pole having a tapered tip.
This patent application is currently assigned to HGST Netherlands B.V.. The applicant listed for this patent is HGST Netherlands B.V.. Invention is credited to Venkata R. K. Gorantla, Wen-Chien D. Hsiao, Yimin Hsu, Terence T. L. Lam, Yansheng Luo, Aron Pentek, Katalin Pentek.
Application Number | 20150029611 13/950180 |
Document ID | / |
Family ID | 52390327 |
Filed Date | 2015-01-29 |
United States Patent
Application |
20150029611 |
Kind Code |
A1 |
Gorantla; Venkata R. K. ; et
al. |
January 29, 2015 |
STITCHED POLE HAVING A TAPERED TIP
Abstract
In one general embodiment, a magnetic head includes a stitch
pole; and a main pole formed adjacent the stitch pole, wherein an
end region of the stitch pole closest to an air bearing surface of
the head tapers towards the main pole. In another general
embodiment, a magnetic head includes a stitch pole being a laminate
of at least two magnetic layers separated b a nonmagnetic layer;
and a main pole formed adjacent the stitch pole. An end region of
the stitch pole closest to an bearing surface of the bead tapers
towards the main pole. An average angle of the taper of the end
region of the stitch pole is between about 20 and about 45 degrees.
Such head may be implemented in a data storage system.
Inventors: |
Gorantla; Venkata R. K.;
(Dublin, CA) ; Hsiao; Wen-Chien D.; (San Jose,
CA) ; Hsu; Yimin; (Sunnyvale, CA) ; Lam;
Terence T. L.; (Cupertino, CA) ; Luo; Yansheng;
(Fremont, CA) ; Pentek; Aron; (San Jose, CA)
; Pentek; Katalin; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HGST Netherlands B.V. |
Amsterdam |
|
NL |
|
|
Assignee: |
HGST Netherlands B.V.
Amsterdam
NL
|
Family ID: |
52390327 |
Appl. No.: |
13/950180 |
Filed: |
July 24, 2013 |
Current U.S.
Class: |
360/75 ;
360/235.4 |
Current CPC
Class: |
G11B 5/3116 20130101;
G11B 5/1278 20130101 |
Class at
Publication: |
360/75 ;
360/235.4 |
International
Class: |
G11B 5/187 20060101
G11B005/187; G11B 21/02 20060101 G11B021/02 |
Claims
1. A magnetic head, comprising: a stitch pole; and a main pole
formed adjacent the stitch pole, wherein an end region of the
stitch pole closest to an air bearing surface of the head tapers
towards the main pole; wherein a tip of the end region of the
stitch pole closest to the bearing surface of the head is recessed
from a tip of an end region of the main pole closest to the air
bearing surface of the head.
2. The magnetic head as recited in claim 1, wherein an average
angle of the taper of the end region of the stitch pole is between
about 20 and about 45 degrees.
3. The magnetic head as recited in claim 1, wherein the stitch pole
is a single layer.
4. The magnetic head as recited in claim 1, wherein the stitch pole
is a laminate of at least two magnetic layers separated by a
nonmagnetic layer.
5. The magnetic head as recited in claim 4, wherein the ends of the
laminated layers are both in direct magnetic contact with the main
pole.
6. The magnetic head as recited in claim 1, wherein the end region
of the stitch pole has a faceted end, a first edge of the end
closest to the air bearing surface being aligned about parallel
with the air bearing surface.
7. The magnetic head as recited in claim 6, wherein the faceted end
has second edges extending from the first edge, and third edges
extending from the second edges, wherein an angle of each of the
second edges relative to a line extending along the first edge is
between about 30 and about 45 degrees, wherein an angle of each of
the second edges relative to a line extending perpendicular to the
ABS is between about 45 and about 60 degrees.
8. The magnetic head as recited in claim 6, wherein a width of the
first edge is between 1/4 and 1/2 a width of the main pole measured
along a line extending along the first edge.
9. A magnetic head, comprising: a stitch pole; and a main pole
formed adjacent the stitch pole, wherein an end region of the
stitch pole closest to an air bearing surface of the head tapers
towards the main pole, wherein sides of the main pole taper towards
each other in a cross track direction as they approach the air
bearing surface, wherein sides of the stitch pole extending along
the sides of the main pole also taper towards each other in the
cross track direction as they approach the air bearing surface.
10. The magnetic head as recited in claim 9, wherein the sides of
the stitch pole are recessed from the sides of the main pole.
11. A magnetic data storage system, comprising: at least one
magnetic head as recited in claim 1; a magnetic medium; a drive
mechanism for passing the magnetic medium over the at least one
magnetic head; and a controller electrically coupled to the at east
one magnetic head for controlling operation of the at least one
magnetic head.
12. A magnetic head, comprising: a stitch pole being a laminate of
at least two magnetic layers separated by a nonmagnetic layer; and
a main pole formed adjacent the stitch pole, wherein an end region
of the stitch pole closest o an air bearing surface of the head
tapers towards the main pole, wherein an average angle of the taper
of the end region of the stitch pole is between about 20 and about
45 degrees.
13. The magnetic head as recited in claim 12, wherein the ends of
the laminated layers are both in direct magnetic contact with the
main pole.
14. The magnetic head as recited in claim 12, wherein the end
region of the stitch pole has a faceted end, a first edge of the
end closest to the air bearing surface being aligned about parallel
with the air bearing surface.
15. The magnetic head as recited in claim 14, wherein the faceted
end has second edges extending from the first edge, and third edges
extending from the second edges, wherein an angle of each of the
second edges relative to a line extending along the first edge is
between about 30 and about 45 degrees, wherein an angle of each of
the second edges relative to a line extending perpendicular to the
ABS is between about 45 and about 60 degrees.
16. The magnetic head as recited in claim 14, wherein a width of
the first edge is between 1/4 and 1/2 a width of the main pole
measured along a line extending along the first edge.
17. The magnetic head as recited in claim 12, wherein sides of the
main pole taper towards each other in a cross track direction as
they approach the air bearing surface, wherein sides of the stitch
pole extending along the sides of the main pole also taper towards
each other in the cross track direction as they approach the air
bearing surface.
18. The magnetic head as recited in claim 17, wherein the sides of
the stitch pole are recessed from the sides of the main pole.
19. A magnetic data storage system, comprising: at least one
magnetic head as recited in claim 12; a magnetic medium; a drive
mechanism for passing the magnetic medium over the at least one
magnetic head; and a controller electrically coupled to the at
least one magnetic head for controlling operation of the at least
one magnetic head.
20. The magnetic head as recited in claim 12, wherein a tip of the
end region of the stitch pole closest to a media facing surface of
the head is recessed from a tip of an end region of the main pole
closest to the media facing surface of the head.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to data storage systems, and
more particularly, this invention relates to magnetic heads having
a tapered stitch pole for improved efficiency.
BACKGROUND
[0002] The heart of a computer is a magnetic hard disk drive (HDD)
which typically includes a rotating magnetic disk, a slider that
has read and write heads, a suspension arm above the rotating disk
and an actuator arm that swings the suspension arm to place the
read and/or write heads over selected circular tracks on the
rotating disk. The suspension arm biases the slider into contact
with the surface of the disk when the disk is not rotating but,
when the disk rotates, air is swirled by the rotating disk adjacent
an air bearing surface (ABS) of the slider causing the slider to
ride on an air bearing a slight distance from the surface of the
rotating disk. When the slider rides on the air bearing the write
and read heads are employed for writing magnetic impressions to and
reading magnetic signal fields from the rotating disk. The read and
write heads are connected to processing circuitry that operates
according to a computer program to implement the writing and
reading functions.
[0003] The volume of information processing in the information age
is increasing rapidly. In particular, it is desired that HDDs be
able to store more information in their limited area and volume. A
technical approach to this desire is to increase the capacity by
increasing the recording density of the HDD. To achieve higher
recording density, further miniaturization of recording bits is
effective, which in turn typically requires the design of smaller
and smaller components.
[0004] The further miniaturization of the various components,
however, presents its own set of challenges and obstacles.
[0005] As the size of the various magnetic head components continue
to become smaller, conventional products are forced to move their
stitch poles farther away from the ABS to prevent leakage of flux
while writing to a magnetic medium. However, this increased spacing
between the stitch pole and the ABS results in weaker write fields,
longer delays, and decreased efficiency of the head. Thus, it is
desirable to produce a design which overcomes such
disadvantages.
[0006] Various approaches described and/or suggested herein
preferably include a magnetic head having a tapered stitch pole
which improves efficiency of the head. The tapered stitch pole
preferably allows for a reduction in the distance between the
stitch pole and the ABS without causing flux leakage.
[0007] A magnetic head according to one embodiment includes a
stitch pole; and a main pole termed adjacent the stitch pole,
wherein an end region of the stitch pole closest to an air bearing
surface of the head tapers towards the main pole.
[0008] A magnetic head according to one embodiment includes a
stitch pole being a laminate of at least two magnetic layers
separated by a nonmagnetic layer; and a main pole formed adjacent
the stitch pole. An end region of the stitch pole closest to an air
bearing surface of the head tapers towards the main pole. An
average angle of the taper of the end region of the stitch pole is
between about 20 and about 45 degrees.
[0009] Any of these embodiments may be implemented in a magnetic
data storage system such as a disk drive system, which may include
a magnetic head, a drive mechanism for passing a magnetic medium
(e.g., hard disk) over the magnetic head, and a controller
electrically coupled to the magnetic head.
[0010] Other aspects and advantages of the present invention will
become apparent from the following detailed description, which,
when taken in conjunction with the drawings, illustrate by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For a fuller understanding of the nature and advantages of
the present invention, as well as the preferred mode of use,
reference should be made to the following detailed description read
in conjunction with the accompanying drawings.
[0012] FIG. 1 is a simplified drawing of a magnetic recording disk
drive system.
[0013] FIG. 2A is a schematic representation in section of a
recording medium utilizing a longitudinal recording format.
[0014] FIG. 2B is a schematic representation of a conventional
magnetic recording head and recording medium combination for
longitudinal recording as in FIG. 2A.
[0015] FIG. 2C is a magnetic recording medium utilizing a
perpendicular recording. format.
[0016] FIG. 2D is a schematic, representation of a recording head
and recording medium combination for perpendicular recording on one
side.
[0017] FIG. 2E is a schematic, representation of a recording
apparatus adapted for recording, separately on both sides of the
medium.
[0018] FIG. 3A is a cross-sectional view of one particular
embodiment of a perpendicular magnetic head with helical coils.
[0019] FIG. 3B is a cross-sectional view of one particular
embodiment of a piggyback magnetic head with helical coils.
[0020] FIG. 4A is a cross-sectional view of one particular
embodiment of a perpendicular magnetic head with looped coils.
[0021] FIG. 4B is a cross-sectional view of one particular
embodiment of a piggyback magnetic head with looped coils.
[0022] FIG. 5A is a partial cross sectional view of a magnetic head
according to one embodiment.
[0023] FIG. 5B is a partial side view of the magnetic head of FIG.
5A taken along Line 5B of FIG. 5A.
[0024] FIG. 6A is a graph of the wrap angle shield corner field
relative to the stitch pole taper angle according to one
embodiment.
[0025] FIG. 6B is a graph of the efficiency improvement relative to
the stitch pole taper angle according to one embodiment.
[0026] FIG. 7 is a graph of the write field relative to the write
current of two head designs
[0027] FIG. 8 is a partial side view of a magnetic head according
to one embodiment.
DETAILED DESCRIPTION
[0028] The following description is made for the purpose of
illustrating the general principles of the present invention and is
not meant to limit the inventive concepts claimed herein. Further
particular features described herein can be used in combination
with other described features in each of the various possible
combinations and permutations.
[0029] Unless otherwise specifically defined herein, all terms are
to be given their broadest possible interpretation including
meanings implied from the specification as well as meanings
understood by those skilled in the art and/or as defined in
dictionaries, treatises, etc.
[0030] It must also be noted that, as used in the specification and
the appended claims, the singular forms "a," an and The include
plural referents unless otherwise specified.
[0031] The following description discloses several preferred
embodiments of disk-based storage systems and/or related systems
and methods, as well as operation and/or component parts
thereof.
[0032] In one general embodiment, a magnetic head includes a stitch
pole; and a main pole formed adjacent the stitch pole, wherein an
end region of the stitch pole closest to an air bearing surface of
the head tapers towards the main pole.
[0033] In another general embodiment, a magnetic head includes a
stitch pole being a laminate of at least two magnetic layers
separated b a nonmagnetic layer; and a main pole formed adjacent
the stitch pole. An end region of the stitch pole closest to an air
bearing surface of the head tapers towards the main pole. An
average angle of the taper of the end region of the stitch pole is
between about 20 and about 45 degrees.
[0034] Referring now to FIG. 1, there is shown a disk drive 100 in
accordance with one embodiment of the present invention. As shown
in FIG. 1, at least one rotatable magnetic medium (e.g., magnetic
disk) 112 is supported on a spindle 114 and rotated by a drive
mechanism, which may include a disk drive motor 118. The magnetic
recording on each disk is typically in the form of an annular
pattern of concentric data tracks (not shown) on the disk 112.
Thus, the disk drive motor 118 passes the magnetic disk 112 over
the magnetic read/write portions 121, described immediately
below.
[0035] At least one slider 113 is positioned near the disk 112,
each slider 113 supporting one or more magnetic read/write portions
121, e.g., of a magnetic head according to any of the approaches
described and/or suggested herein. As the disk rotates, slider 113
is moved radially in and out over disk surface 122 so that portions
121 may access different tracks of the disk where desired data are
recorded and/or to be written. Each slider 113 is attached to an
actuator arm 119 by means of a suspension 115. The suspension 115
provides a slight spring force which biases slider 113 against the
disk surface 122. Each actuator area 119 is attached to an actuator
127. The actuator 127 as shown in FIG. 1 may be a voice coil motor
(VCM). The VCM comprises a coil movable within a fixed magnetic
field, the direction and speed of the coil movements being
controlled by the motor current signals supplied by controller
129.
[0036] During operation of the disk storage system, the rotation of
disk 112 generates an air hearing between slider 113 and disk
surface 122 which exerts an upward force or lift on the slider. The
air bearing thus counterbalances the slight spring force of
suspension 115 and supports slider 113 off and slightly above the
disk surface by a small, substantially constant spacing during
normal operation. Note that in some embodiments, the slider 113 may
slide along the disk surface 122.
[0037] The various components of the disk storage system are
controlled in operation by control signals generated by controller
129, such as access control signals and internal lock signals.
Typically, control unit 129 comprises logic control circuits,
storage (e.g., memory), and a microprocessor. In a preferred
approach, the control unit 129 is electrically coupled (e.g., via
wire, cable, line, etc.) to the one or more magnetic readwrite
portions 121, for controlling operation thereof. The control unit
129 generates control signals to control various system operations
such as drive motor control signals on line 123 and head position
and seek control signals on line 128. The control signals on line
128 provide the desired current profiles to optimally move and
position slider 113 to the desired data track on disk 112. Read and
write signals are communicated to and from readwrite portions 121
by way of recording channel 125.
[0038] The above description of a typical magnetic disk storage
system, and the accompanying illustration of FIG. 1 is for
representation purposes only. It should be apparent that disk
storage systems may contain a large number of disks and actuators,
and each actuator support a number of sliders.
[0039] An interface may also be provided for communication between
the disk drive and a host (integral or external) to send and
receive the data and for controlling the operation of the disk
drive and communicating, the status of the disk drive to the host,
all as will be understood by those of skill in the art.
[0040] In a typical head, an inductive write portion includes a
coil layer embedded in one or more insulation layers (insulation
stack), the insulation stack being located between first and second
pole piece layers. A gap is formed between the first and second
pole piece layers by a gap layer at an air bearing surface (ABS) of
the write portion. The pole piece layers may be connected at a back
gap. Currents are conducted through the coil layer, which produce
magnetic fields in the pole pieces. The magnetic fields fringe
across the gap at the ABS for the purpose of writing bits of
magnetic field information in tracks on moving media, such as in
circular tracks on a rotating magnetic disk.
[0041] The second pole piece layer has a pole tip portion which
extends from the ABS to a flare point and a yoke portion which
extends from the flare point to the back gap. The flare point is
where the second pole piece begins to widen (flare) to form the
yoke. The placement of the flare point directly affects the
magnitude of the magnetic field produced to write information on
the recording medium.
[0042] FIG. 2A illustrates, schematically, a conventional recording
medium such as used with magnetic disc recording systems, such as
that shown in FIG. 1. This medium is utilized for recording
magnetic impulses in or parallel to the plane of the medium itself.
The recording medium, a recording disc in this instance, comprises
basically a supporting substrate 200 of a suitable nonmagnetic
material such as glass, with an overlying coating 202 of a suitable
and conventional magnetic layer.
[0043] FIG. 2B shows the operative relationship between a
conventional recording/playback head 204, which may preferably be a
thin film head, and a conventional recording medium, such as that
of FIG. 2A.
[0044] FIG. 2C illustrates, schematically, the orientation of
magnetic impulses substantially perpendicular to the surface of a
recording medium as used with magnetic disc recording systems, such
as that shown in FIG. 1. For such perpendicular recording the
medium typically includes an under layer 212 of a material having a
high magnetic permeability. This under layer 212 is then provided
with an overlying coating 214 of magnetic material preferably
having a high coercivity relative to the wider layer 212.
[0045] FIG. 20 illustrates the operative relationship between a
perpendicular head 218 and a recording medium. The recording medium
illustrated in FIG. 2D includes both the high permeability under
layer 212 and the overlying coating 214 of magnetic material
described with respect to FIG. 2C above. However, both of these
layers 212 and 214 are shown applied to a suitable substrate 216.
Typically there is also an additional layer (not shown) called an
"exchange-break" layer or "interlayer" between layers 212 and
214.
[0046] In this structure, the magnetic lines of flux extending
between the poles of the perpendicular head 218 loop into and out
of the overlying coating 214 of the recording medium with the high
permeability under layer 212 of the recording medium causing the
lines of flux to pass through the overlying coating 214 in a
direction generally perpendicular to the surface of the medium to
record information in the overlying coating 214 of magnetic
material preferably having a high coercivity relative to the under
layer 212 in the form of magnetic impulses having their axes of
magnetization substantially perpendicular to the surface of the
medium. The flux is channeled by the soft underlying coating 212
back to the return layer (P1) of the head 218.
[0047] FIG. 2E illustrates a similar structure in which the
substrate 216 carries the layers 212 and 214 on each of its two
opposed sides, with suitable recording heads 218 positioned
adjacent the outer surface of the magnetic coating 214 on each side
of the medium, allowing for recording on each side of the
medium.
[0048] FIG. 3A is a cross-sectional view of a perpendicular
magnetic head. In FIG. 3A, helical coils 310 and 312 are used to
create magnetic flux in the stitch pole 308, which then delivers
that flux to the main pole 306. Coils 310 indicate coils extending
out from the page, while coils 312 indicate coils extending into
the page. Stitch pole 308 may be recessed from the ABS 318.
Insulation 316 surrounds the coils and may provide support for some
of the elements. The direction of the media travel, as indicated by
the arrow to the right of the structure, moves the media past the
lower return pole 314 first, then past the stitch pole 308, main
pole 306, trailing shield 304 which may be connected to the wrap
around shield (not shown), and finally past the upper return pole
302. Each of these components may have a portion in contact with
the ABS 318. The. ABS 318 is indicated across the right side of the
structure.
[0049] Perpendicular writing is achieved by forcing flux through
the stitch pole 308 into the main pole 306 and then to the surface
of the disk positioned towards the ABS 318.
[0050] FIG. 3B illustrates a piggyback magnetic head having similar
features to the head of FIG. 3A. Two shields 304, 314 flank the
stitch pole 308 and main pole 306. Also sensor shields 322, 324 are
shown. The sensor 326 is typically positioned between the sensor
shields 322, 324.
[0051] FIG. 4A is a schematic diagram of one embodiment which uses
looped coils 410, sometimes referred to as a pancake configuration,
to provide flux to the stitch pole 408. The stitch pole then
provides this flux to the main pole 406. In this orientation, the
lower return pole is optional. Insulation 416 surrounds the coils
410, and may provide support for the stitch pole 408 and main pole
406. The stitch pole may be recessed from the ABS 418. The
direction of the media travel, as indicated by the arrow to the
right of the structure, moves the media past the stitch pole 408,
main pole 406, trailing shield 404 which may be connected to the
wrap around shield (not shown), and finally past the upper return
pole 402 (all of which may or may not have a portion in contact
with the ABS 418). The ABS 418 is indicated across the right side
of the structure. The trailing shield 404 may be in contact with
the main pole 406 in some embodiments.
[0052] FIG. 4B illustrates another type of piggyback magnetic head
having similar features to the head of FIG. 4A including a looped
coil 410, which wraps around to form a pancake coil. Also, sensor
shields 422, 424 are shown. The sensor 426 is typically positioned
between the sensor shields 422, 424.
[0053] In FIGS. 3B and 4B, an optional heater is shown near the
non-ABS side of the magnetic head. A heater (Heater) may also be
included in the magnetic heads shown in FIGS. 3A and 4A. The
position of this heater may vary based on design parameters such as
where the protrusion is desired, coefficients of thermal expansion
of the surrounding layers, etc.
[0054] Except as otherwise described herein, the various components
of the structures of FIGS. 3A-3B may be of conventional materials
and design, as would be understood by one skilled in the art.
[0055] As previously mentioned, conventional writers must have
their stitch poles positioned far away from the ABS to prevent
leakage of flux while writing to a magnetic medium thereby
resulting, in weaker write fields, longer delays, and decreased
efficiency of the bead. In sharp contrast, various approaches
described and/or suggested herein preferably include a magnetic
head having a tapered stitch pole which improves efficiency of the
head. The tapered stitch pole preferably allows for a reduction in
the distance between the stitch pole and the ABS without causing,
flux leakage, thereby improving head functionality.
[0056] FIGS. 5A-5B depict a magnetic head 500 having improved
writer efficiency, in accordance with one embodiment. As an option,
the present magnetic head 500 may be implemented in conjunction
with features from any other embodiment listed herein, such as
those described with reference to the other FIGS. Of course,
however, such magnetic head 500 and others presented herein may be
used in various applications and/or in permutations which may or
may not be specifically described in the illustrative embodiments
listed herein. Further, the magnetic head 500 presented herein may
be used in any desired environment.
[0057] Referring now to FIGS. 5A-5B, the magnetic head 500 has an
upper return pole 516 and trailing shield 518, e.g., see also 302,
402 and 304, 404 of FIGS. 3A-3B and 4A-4B respectively.
[0058] Moreover, the magnetic head 500 also includes a stitch pole
502 and a main pole 504 formed adjacent to the stitch pole 502 as
illustrated. According to various approaches, the stitch pole 502
and/or main pole 504 may be constructed of conventional materials,
such as CoFe, NiFe, etc. However, according to other approaches,
the stitch pole 502 and/or main pole 504 may have similar or the
same material construction, methods of forming, etc. as the
variations described above with reference to stitch poles 308, 408
and main poles 306, 406 respectively.
[0059] As shown in FIG. 5A, the end region 506 of the stitch pole
502 closest to an air bearing surface 508 of the head 500 tapers
towards the main pole 504, at an angle .beta.. Depending on the
desired approach, the average angle .beta. of the taper of the end
region 506 of the stitch pole 502 may be between about 20.degree.
(degrees) and about 45.degree. where "about" refers to .+-.10% of
the stated value, but may be higher or lower. Through testing of
various illustrative embodiments, the inventors have discovered
that implementing such a tapered angle .beta. can desirably
increase the efficiency of magnetic head operations, as will be
discussed in further detail below with reference to the description
of FIGS. 6A-7.
[0060] Referring again to FIGS. 5A-5B, the stitch pole 502 may be a
single layer, though various embodiments may include stitch poles
having multiple layers, e.g., at least two, at least three, at
least 5, multiple, etc. layers. However, in preferred approaches
the stitch poles may have from two to four laminated layers. Thus,
according to a preferred approach, the stitch pole 502 may be a
laminate of at least IWO magnetic layers 510, 512. Furthermore,
adjacent pairs of the potentially multiple magnetic layers of the
stitch pole 502 may be separated by a nonmagnetic layer 514,
including, but not limited to alumina, copper, tantalum, etc. The
nonmagnetic layer 514 may be nonconductive. For example, the two
magnetic layers 510, 512 of the embodiment illustrated in FIG. 5A
are separated by a nonmagnetic layer 514. In various approaches,
each of the magnetic layers and/or nonmagnetic layers of the stitch
pole may be the same, similar and/or different than others
therein.
[0061] In yet other approaches, no magnetic layer may be present
between at least some of the adjacent pairs of the magnetic
layers.
[0062] A multi-layer stitch pole, e.g., as shown in FIG. 5A, may
have a thickness t measured in a direction parallel to the ABS 508
from about 0.2 .mu.m to about 0.5 .mu.m, but could be higher or
lower depending on the desired embodiment. Moreover, stitch poles
having a different number of layers may have a thickness higher or
lower than this range, depending on materials used, number of
magnetic layers, number of nonmagnetic layers, desired magnetic
characteristics, etc.
[0063] Moreover, although the stitch pole 502 of FIGS. 5A-5B is
shown having two magnetic layers 510, 512, the ends of the
laminated layers are both in direct magnetic contact with the main
pole 504, i.e., there is no layer of nonmagnetic material between
the ends of the laminated layers and the main pole. According to
other approaches, there may be an intervening layer between at
least one of the ends of the stitch pole layers and the main pole.
Where the intervening layer is magnetic, a direct magnetic
connection is present between the stitch pole 502 and the main pole
504. Where the intervening layer is nonmagnetic, an indirect
magnetic connection may be present between the stitch pole 502 and
the main pole 504. Moreover, at least some of the layers of a
stitch pole may be in direct contact with the main pole, while one
or more other layers may have an intervening layer
therebetween.
[0064] As mentioned above, the inventors have discovered that
implementing a tapered end region 506 of the stitch pole 502
enables a large increase in the efficiency of magnetic head
operations. Looking to FIGS. 6A-6B, the graphs 600, 650 illustrate
the effect that different angles for the tapered end region 506
have on the wrap angle shield (WAS) corner field, and efficiency
improvement percentage of the magnetic head, respectively.
[0065] The graph 600 of FIG. 6A shows that the steeper (larger) the
tapered angle for the stitch pole (e.g., the closer to being
parallel to the ABS), the higher the WAS corner field. Increases to
the WAS corner field raise the likelihood of having flux leak from
the stitch pole, thereby potentially overwriting adjacent tracks on
a medium at the ABS. Thus, the WAS corner field is preferably kept
to a minimum value. However, looking now to FIG. 6B, the graph 650
illustrates the efficiency improvement increasing as the tapered
angle increases. Thus, by balancing the propensity of flux leakage,
with the efficiency improvement percentage, the inventors were able
to ascertain that desired range for the angle .beta. of the tapered
end region 506 of the stitch pole 502 is from about 20.degree. to
about 45.degree.. Thus, the inventors were able to improve the
output of a magnetic head having a stitch pole with a tapered end
region.
[0066] Looking to FIG. 7, the graph 700 illustrates the saturation
curve for a magnetic head having a stitch pole with a tapered end
portion. As depicted in the graph 700, the write performance of the
head having a tapered stitch pole (Tapered) experienced a 10%
increase in writer efficiency over an otherwise identical reference
head (Reference) without the novel features discussed herein,
particularly, the tapered end portion.
[0067] The inventors have found that the tapered stitch pole allows
the main pole of the magnetic head to be spaced about 0.3 .mu.m to
about 1.3 .mu.m away from the ABS, which is much closer than
achievable with a magnetic head without said tapered stitch pole.
As a result, the performance and efficiency of the magnetic head
are improved without experiencing the aforementioned issue of flux
leakage and overwriting of data. Additionally, the reduced spacing
between the tapered stitch pole and the ABS reduces the time lag
from when a write current is initiated in the magnetic head, to
when the head actually begins to write, thereby desirably lowering
wait time and operating costs.
[0068] Referring back now to FIG. 5B, the end region 506 of the
stitch pole 502 is shown as having a faceted end according to one
preferred approach. As illustrated in FIG. 5B, the faceted end may
be characterized by several relatively straight edges extending
along the intersection of the periphery of the stitch pole 502 with
the main pole 504 and meeting each other at predefined angles.
According to various approaches, the angles may be predefined by a
user, industry standards, calculated values, etc. prior to
formation of the magnetic head 500, depending on the desired
configuration.
[0069] With continued reference to FIG. 5B, a first edge 520 of the
faceted end closest to the air bearing surface 508 is preferably
aligned about parallel with the air bearing surface 508.
Furthermore, the faceted end preferably has second edges 522
extending from the first edge 520, and third edges 524 extending
from the second edges 522. According to various approaches, the
angle .phi. of each of the second edges 522 relative to a line
extending along the first edge 520 may be between about 30 and
about 45.degree.. Moreover, according to other approaches, the
angle .theta. of each of the second edges 522 relative to a
reference line extending perpendicular to the ABS may be between
about 45.degree. and about 60.degree.. However, depending on the
desired embodiment, the angles .phi., .theta. may be higher or
lower than the aforementioned ranges.
[0070] According to another approach, the sides of the main pole
504 preferably taper towards each other in a cross track direction
X as they approach the air bearing surface 508. Moreover, the sides
of the stitch pole 502 extending along the sides of the main pole
preferably also taper towards each other in the cross track
direction X as they approach the ABS 508.
[0071] According to yet another approach, the width W.sub.1 of the
first edge 520 may be between about 1/4 and about 1/2 a width
W.sub.2 of the main pole measured along a line extending along the
first edge 520. Thus, according to a preferred approach, the sides
of the stitch pole 502 may be recessed from the sides of the main
pole 504 as illustrated in FIG. 5B.
[0072] This recessed shape of the stitch pole is preferred as it
reduces the chance of having flux leak from the stitch pole to the
return pole, thereby traveling through the magnetic media itself
and potentially overwriting adjacent data tracks. Rather, the
recessed stitch pole as shown in FIG. 5B allows for the flux from
the stitch pole to be absorbed and focused b the tapered main pole.
Thus, the aforementioned design allows for the magnetic head to be
positioned even closer to the media when reading data therefrom
and/or writing data thereto with higher precision.
[0073] FIG. 8 illustrates a partial side view of a magnetic head
800 having writer coils 808 below a main pole 804 and bilayer
stitch pole 802 with a tapered end portion having an angle .alpha.
taken along some point of the tapered end portion. As described
above, the average angle .alpha. of the tapered stitch pole is
preferably from about 20.degree. to about 45.degree., but may be
higher or lower depending on the desired embodiment. Moreover, the
illustrative dimensions shown in FIG. 8 are in no way intended to
limit the invention, but rather have been added to show the details
of the exemplary embodiment depicted therein.
[0074] The various approaches described and/or suggested herein
allow for an optimized efficiency and data density on a magnetic
medium. Moreover, any of the designs and/or approaches described
herein may be formed using processes which are known in the art,
such as sputtering, plating, chemical vapor deposition,
planarizing, etc.
[0075] It should be noted that methodology presented herein for at
least some of the various embodiments may be implemented, in whole
or m part, in computer hardware, software, by hand, using specialty
equipment, etc. and combinations thereof.
[0076] Moreover, any of the structures and/or steps may be
implemented using known materials and/or techniques, as would
become apparent to one skilled in the art upon reading the present
specification.
[0077] While various embodiments have been described above, it
should be understood that they have been presented by way of
example only, and not limitation. Thus, the breadth and scope of an
embodiment of the present invention should not be limited by any of
the above-described exemplary embodiments, but should be defined
only in accordance with the following claims and their
equivalents.
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