Contoured magnetic recording head/slider assembly

A magnetic head/slider assembly for flying a magnetic head on a fluid bearing relative to magnetic recording media moving in a predetermined direction, as a fluid bearing surface which is convexly curved longitudinally of the assembly. A magnetic recording head extends rearwardly of the slider body with at least a portion of its bottom surface also being convexly curved. The head/slider assembly is supported such that the portion of the assembly closest to the magnetic recording media when the media is stopped is a portion of the slider body forward of the trailing edge thereof, whereby the magnetic head gap remains spaced above the media when the media contacting portion of the assembly is resting thereupon.

BACKGROUND OF THE INVENTION 
In the magnetic recording art, particularly that directed to recording on 
rotating magnetic discs such as are commonly used in the data processing 
field, it is well known to utilize assemblies which support the magnetic 
recording head or transducer on the moving film of air entrained with the 
moving media. In more recent equipment utilizing what is known as 
"Winchester" technology, it is well known to utilize a slider to carry the 
magnetic heads, with this slider being configured to provide the necessary 
support on the fluid bearing created by the moving media. Numerous 
configurations of such head/slider assemblies have been developed and 
utilized, including those illustrated in various United States patents, 
such as U.S. Pat. No. 3,855,625 to Garnier et al. and U.S. Pat. No. 
3,823,416 to Warner. Each of these structures, along with numerous others, 
have provided for more or less satisfactory operation. However, each of 
them has suffered from various disadvantages resulting both from their 
configurations and from their operating characteristics. 
In the prior art the slider bodies have each included an extended, planar 
or flat portion which cooperates with the film of air entrained with the 
moving media to provide an air bearing supporting the slider and the 
magnetic head attached thereto some distance above the surface of the 
media. In these prior art structures these flat fluid bearing surfaces 
have extended rearwardly and having included as a portion thereof the 
lowermost surface of the magnetic transducer along with its read/write 
gap. Since the gap, along with the remainder of the head or transducer, 
extends rearwardly from the back edge of the slider, the head and gap are 
placed lower than any portion of the slider when the leading edge of the 
slider is tilted upwardly as occurs during operation when the head and 
slider are flying above the media. Since the head and gap are lower than 
any portion of the slider, any dust, grit or other foreign objects on the 
surface of the media will tend to strike and possibly damage the head, if 
it strikes any portion of the head/slider assembly. Additionally, when the 
head/slider assembly lands, as when the movement of the media is slowed 
and stopped, the first portion of that assembly which contacts the surface 
of the media again is the head and its gap, thus tending to cause abrasion 
and undesirable wear and possible damage to the head and the read/write 
gap causing degradation of the magnetic recording performance of the head. 
Heretofore, that has been considered simply a normal disadvantage of the 
flying head/slider assemblies which are used in the contact start/stop 
mode. Methods of lubricating disc surfaces do not overcome this physical 
structure defect. 
SUMMARY OF THE INVENTION 
In view of the disadvantages of the prior art head/slider assemblies, it is 
an object of the present invention to provide an improved head/slider 
assembly in which the magnetic transducer and its read/write gap are 
better protected from damage and wear during operation and initial 
start/stop conditions. 
It is a further object of this invention to provide such an assembly in 
which, when the assembly is flying above the media, the lowermost portion 
of the magnetic transducer and its read/write gap are not significantly 
lower than the lowermost portion of its associated slider. 
It is yet another object of this invention to provide such a head/slider 
assembly in which, when the relative movement between the media and the 
assembly is stopped to permit the assembly to land on the surface of the 
media, the magnetic transducer and its gap are displaced above the surface 
of the media when the fluid bearing surface of the slider is at rest upon 
the media. 
To achieve these and other important objects of this invention, which will 
become more apparent from the following detailed description of a 
preferred embodiment, there is provided a magnetic head/slider assembly 
for flying a magnetic head on a fluid bearing relative to magnetic 
recording media moving at a predetermined direction in the fluid, with the 
head/slider assembly including a slider body having leading and trailing 
edges with respect to such relative movement and at least one magnetic 
head including a read/write gap affixed to the slider body and extending 
rearwardly of the trailing edge thereof. The slider body has a bottom 
surface facing the media and extending longitudinally of the slider body 
with at least a portion of that bottom surface forming a fluid bearing 
surface which is convexly curved in the longitudinal direction from the 
slider body trailing edge to a point forward thereof. The bottom surface 
of the magnetic head is also convexly curved in the longitudinal direction 
from the slider body trailing edge to a point rearward thereof. The 
head/slider assembly is supported such that the portion of the assembly 
closest to the media when the movement of the media is stopped is a 
portion of the slider body forward of the trailing edge, whereby the 
magnetic head remains spaced above the media when the media-contacting 
portion of the assembly is resting on the media surface to protect the 
read/write gap from contact with the media.

DESCRIPTION OF A PREFERRED EMBODIMENT 
FIGS. 1, 3, 4 and 6 generally illustrate a particularly preferred 
embodiment of the head/slider assembly of the present invention. These 
illustrations are of such a device at a considerably enlarged scale for 
purposes of illustrations, since the actual devices may be only about one 
quarter of an inch long, or less. 
This embodiment of the invention is generally similar in overall 
configuration to the head/slider assembly disclosed in detail in U.S. Pat. 
No. 3,823,416 and is of the configuration generally referred to as the 
three-rail or trimaran. The assembly comprises, generally, the slider body 
2 and the magnetic transducer 4 attached to the trailing edge of that 
slider body. 
Slider body 2 is formed of a suitable material, such as ferrite, and 
includes three downwardly depending longitudinal rails 6, 8 and 10 which 
are parallel to and generally level with one another. At least a portion 
14, 18 and 22 of the bottom of each rail 6, 8 and 10 are convexly curved 
from the trailing edge to a point forward thereof. Preferably, this 
curvature may be cylindrical about an axis which extends transverse to the 
slider body and generally parallel to the plane of the recording media, 
and which axis is spaced well above the slider body. The cylindrical 
curvature may be very gradual, suitably being defined by a radius R of 
some fifty inches on this slider which may be on the order of 0.22 inches 
long. The axis may suitably be positioned about mid-way between the front 
and rear of the slider body 2. 
The convex curvature of the slider body preferably may be continuous from 
the rear of the slider body to a point near the front thereof. 
Alternatively, the convex curvature may extend only part way to the center 
of the body from both the front and the rear thereof, providing for a flat 
planar area in the center with the curved portions at the edges thereof. 
At the front of each rail additional beveled surfaces 12, 16 and 20 may be 
provided, angling upwardly from the convexly curved portions 14, 18 and 
22, as shown in FIGS. 1, 4 and 6. 
As shown most clearly in FIG. 4, the outside rails 6 and 10 are located 
adjacent the outer extremities of the slider body 2 and are wider than the 
width of the center rail 8, so as to provide substantially the entire air 
bearing surface. The three rails are separated by bleed slots 24 and 26, 
which provide paths for the undesired air to bleed off from the air 
bearing outside rail surfaces during flying operations without 
contributing to the effective air bearing surface of the slider or 
changing the flying height thereof. 
Transducer 4 comprises a magnetic core 30, which is formed into a generally 
C-shaped configuration, and which may be formed of generally the same 
ferrite material as the slider body 2. The core 30 may suitably be glass 
bonded to the trailing edge 32 of the slider body 2 in longitudinal 
alignment with the center rail 8. Upper leg portion 34 of the core is 
greater in cross-sectional area than the tapered lower leg portion 36, 
which forms the transducing gap, a substantial portion of which is filled 
with bonding glass 38. A suitable excitation winding 40 is provided, as 
illustrated in phantom in FIG. 2. Also as shown most clearly in FIG. 2, 
the bottom surface of the head 4 is also convexly curved in the 
longitudinal direction from the slider body trailing edge to a point 
rearward thereof. Suitably, this convex curvature is an extension of the 
cylindrical curvature defined by the radius R that forms the convex 
configuration of the air bearing support rails. An additional, upwardly 
beveled area 42 may be provided in the rearmost portion of the head. 
The desired, convexly curved configuration of the air bearing support rails 
and the magnetic head of this embodiment preferably provide for a smoothly 
blended and continuous curved surface along the bottom rails and extending 
continuously at least part way back along the magnetic head bottom surface 
beyond the read/write gap G. As noted above, in an alternative embodiment 
the convexly curved configuration may be formed at the forward and 
rearward edges of a planar or flat portion of the bottom of the slider. 
FIG. 5 illustrates a slight variation on the embodiment of FIGS. 1 through 
4, in which the lower surface of the slider body rails and of the portion 
of the magnetic head 4 are provided with a curvature which is generally 
spherical instead of the cylindrical curvature of FIGS. 1 through 4. 
Suitably, this spherical radius R may be substantially the same as the 
cylindrical radius described above, and may be taken about a point on the 
same axis which is generally centered with respect to the lateral edges of 
the slider body. While the cylindrical curvature may be slightly 
preferable from a functional standpoint, such a spherically curved lower 
surface of the slider and head assembly has the practical advantage of 
simpler manufacture, since it may be formed through conventional lens 
grinding and lapping techniques used for forming convex lenses. 
Nonetheless, while only cylindrically and spherically curved embodiments 
are illustrated, it is to be understood that numerous other variations on 
convex curvature may be used equally well within the scope of this 
invention, and are to be included therein. 
As illustrated in FIG. 6, the head/slider assembly of the present invention 
may be conventionally supported within a known type of flexure mount 46, 
in which a transversely extending torsion arm 48 is attached to the notch 
50 in the top portion of the slider body 2. The flexure in turn may be 
mounted, suitably by the extension 52 extending longitudinally outwardly 
thereof to a conventional support arm. This suspension system, well known 
in the art, provides stiffness in a plane parallel to the recording media, 
which is the plane of accessing and frictional forces. However, the 
flexure mounting will permit the head to pivot about both the axis defined 
by the cross member 48 and that defined by the tabs 52, when torsional 
stresses are applied through the head, as by the air bearing during 
flying. This mounting arrangement is attached to the head/slider assembly 
such that the portion of the assembly closest to the recording media when 
the movement of the media is stopped is a portion of the slider body 
forward of the trailing edge, by virtue of the convex curvature of the air 
bearing surfaces of the slider body 2. This mounting arrangement provides, 
as illustrated in FIG. 2, for the magnetic head and its read/write gap G 
to remain spaced above the media some distance D when the media contacting 
portion of the assembly, the lowermost portion of the convexly curved 
rails, is resting on the media surface. By this arrangement, the 
read/write gap is spaced from contact with the media and is thus protected 
from the abrasive effects of the media moving at slow speed. 
The flying characteristics, and advantages, of the present invention 
compared with the prior art, such as Warner U.S. Pat. No. 3,823,416, are 
shown in the parallel sets of FIGS. 7 through 9 and 10 through 12. With 
the prior art, such as Warner, the bottom surfaces of the air bearing 
rails have taper-flat configuration, with most of the rail being flat from 
its juncture with the forward tapered portion all the way to a point past 
the read/write gap. In this prior art structure the read/write gap is 
essentially co-planar with the bottom of the rails, and thus rests upon 
the media when the rails themselves are resting upon the media. 
As shown in FIG. 8, when the media surface S begins to move faster and 
faster, thus creating an entrained layer of air to coact with the bottom 
rails of the slider and provide an air bearing arrangement, the forward 
portion of the slider body B will begin to rotate upwardly as it begins to 
take off from the media surface S. This rotation then causes the magnetic 
head H, and its read/write gap, to become the last portions of the 
head/slider assembly to lift off the media surface S. During this time, 
substantially all abrasive contact with the media surface is placed upon 
the head and its gap, thus exposing them to substantial wear. 
When the head is fully flying, as illustrated in FIG. 9, it remains at a 
slightly pitched up attitude, as illustrated. In this attitude, the head 
and its gap are still the points of closest contact of the assembly with 
the media surface, with the head being somewhat closer to the media 
surface than any portion of the slider body. Thus, any particles of grit, 
dust or other foreign matter on the moving media surface that are larger 
than the flying height E will crash into the head and its gap, likely 
causing serious damage to both the head and the media. 
In contrast, a head/slider assembly according to the present invention is 
illustrated in FIGS. 10 through 12. Due to the convexly curved fluid 
bearing surface of the slider rails, this improved head/slider assembly 
will not land flat on the media surface S in the manner of the prior art, 
but will contact it over a substantially reduced area, approximating line 
contact. As illustrated in FIG. 10, and also FIG. 2, this improved 
assembly when resting on the media surface S under the influence of 
loading force F from the flexure and suspension will contact the media 
surface S at a point generally around the center of a slider body B. This 
is occasioned by the general manner of mounting the slider to its flexure 
such that the portion of the assembly closest to the media when it is 
stopped is a portion of the slider forward of the trailing edge thereof. 
As described above, this contact of the slider body with the immediate 
surface S, along with the above described convexly curved bottom surface 
of the slider body 2 and the head 4 will place the sensitive head gap a 
small distance D above the surface S of the media, thus protecting the gap 
from abrasive engagement with the media surface. 
As the media begins moving and picking up speed (or as it slows to a stop), 
as when rotation of a recording disc is initiated, fluid, such as the air, 
entrained with the media surface S begins to establish the air bearing 
support which cooperates with the fluid bearing surfaces on the bottoms of 
the rails of the slider body 2. The force F which loads the head/slider 
assembly toward the media surface is centered at a position L along the 
slider body such that the head/slider assembly will rotate bringing its 
leading edge upward during this take-off procedure from the media surface 
S. The positioning of the loading force F is selected in a manner well 
known and easily determined by minor experimentation with any selected 
assembly design, to bring the recording gap to a position in which the gap 
is the portion of the assembly closest to the moving media at the moment 
of take-off and during the continued flying of the head, as illustrated in 
FIGS. 11 and 12. Such positioning of the loading force simply involves 
placing the force an easily determined distance behind the center of lift 
of the fluid bearing on the slider body fluid bearing surface. By this 
arrangement conventional control of the flying height E of the assembly 
above the disc surface S will place the recording/playback gap at the 
desired optimum operating position with respect to the magnetic media 
surface. By this positioning, with the gap closest to the media surface, 
but essentially tangent to a line parallel with that surface, it may be 
seen that any foreign objects on the disc or media surface large enough to 
cause interference and potential damage to the head will first strike a 
portion of the slider body fluid bearing support rails, thus tending to 
move the sensitive gap out of the way of any such foreign object. By this 
arrangement the gap is further protected against damage. 
The operation of the alternative preferred embodiment described above 
combines features of both the prior art and of the present invention. Like 
the prior art, it provides a flat or planar portion for landing on the 
media, and thus distributing pressure from the loading force over a larger 
area. However, unlike the prior art and like the present invention, it 
also provides the convex curvature which spaces the gap above the media 
surface upon landing and provides greater protection and enhanced 
operating characteristics as compared with the prior art devices. From the 
foregoing description of the novel configuration and the manner of 
mounting and operating the improved head/slider assembly of this 
invention, it is apparent that this structure provides such an assembly 
which is less susceptible to damage and wear of the sensitive recording 
head gap than is the prior art. This arrangement provides such improved 
protection not only during the flying operation, but, importantly, during 
the landing and taking-off stages of the operation, when the slider body 
contacts the moving media surface and thus experiences potential abrasion. 
While the foregoing describes a particularly preferred embodiment of the 
improved magnetic head/slider assembly of the present invention, it is to 
be recognized that such description is intended to be illustrative only of 
the principles of this invention, and is not to be considered limitative 
thereof. Since numerous variations and modifications, all within the scope 
of the present invention, will readily occur to those skilled in the art, 
the scope of the invention is to be limited solely by the claims appended 
hereto.