AIR BEARING SLIDER FOR A TRANSDUCER

Abstract: A self-loading air bearing slider for a magnetic transduc­ er head is chamfered across its whole width from its leading edge (12) down to the cross rail (18) to provide a leading tapered section (10). A recessed section (20) trails the cross rail (18) and is defined by that rail (18) and a pair of side rails (14, 16). The lower surfaces of the three rails are co-planar. The side rails are preferably flared so that they are wider at the trailing edge (26) of the slider to provide an improved pressure profile thereby to allow fast liftoff from a record surface.

Description: AIR BEARING SLIDER FOR A TRANSDUCER This invention relates to air bearing sliders for supporting a transducer relative to a moving record medium. Magnetic head assemblies that fly relative to magnetic disks have been used extensively. The objectives for improving the transducing relationship between a magnetic transducer and a magnetic disk include a close spacing between the transducer and the disk, and to maintain such spacing constant. The close spacing, when used with very narrow transducing gaps and very thin magnetic record films, allows short wave length, high frequency signals to be recorded, thereby affording high density, high storage capacity recording. In accessing type disk drives, for example, the flying height of the magnetic head assembly varies as the head is moved radially to different data tracks because the linear speed of the rotating disk at the outer tracks is greater than that at the inner tracks. To compensate for these variations in flying height, different magnitudes of write current must be used for different radial zones to obtain a substantially constant signal amplitude of the recorded data. Therefore a constant head to disk spacing is desirable to reduce the requirements for such compensation. Some presently known magnetic disk files operate in a start-stop contact mode, i.e. the magnetic heads are in contact with the magnetic disk surface when the disk starts to rotate and when the disk rotational speed approaches and reaches zero. It is apparent that the longer it takes for the heads to lose contact with the disk surface, the more wear and shorter usage life of the heads will result. U.S. Specification No. 3,855,625 describes an air bearing slider having a recessed section between a pair of side rails and a cross rail. The present invention is concerned with a modification of that slider which has the advantage of providing faster liftoff from a rotating record surface. The slider of this invention also has improved wear characteristics and a longer life. According to the invention, there is provided an air bearing slider for supporting a transducer relative to a moving record medium, the underside of the assembly being formed to provide a pair of spaced apart side rails and a cross rail joining the side rails so that there is a recessed section trailing the cross rail and defined on three sides by the three rails, the lower surfaces of the rails being co-planar, characterised in that the slider is chamfered across its whole width from its leading edge down to the cross rail. The invention will now be described by way of example, with reference to the accompanying drawings, in which: Figures la to ld represent four alternative embodiments of an air bearing slider according to the invention; Figure 2 is a side view of an air bearing slider in accordance with this invention and supporting a transducer; and Figure 3 depicts two plots of flying height, i.e. the spacing between a slider and the rotating disk, against disk speed, and provides a comparison of the performance of a prior art slider and a slider embodying the invention. Similar reference numerals refer to similar elements throughout the drawings. Each of the four alternative configurations of air bearing sliders incorporating the invention depicted in Figures la to Id is chamfered down from the leading edge 12 to the cross rail 18 to provide a full taper section 10 across the entire width of the slider. In Figure la, two side rails 14 and 16 are connected by a cross rail 18. The lower surfaces of the side rails and cross rail are co-planar. The three rails enclose a recessed section 20 that defines a subambient pressure zone or negative pressure region. The recessed section 20 may be of constant depth or have a tapered sloping geometry (i.e. its depth progressively increases from the cross rail to the trailing edge 26 of the slider). The pressure zone provides the self loading effect of the slider, precluding the need for an external loading force, such as a spring force or hydraulic force. This negative pressure region can be formed in a single step, which may be by a machining or etching process. In accordance with this invention, the full width taper at the leading edge of the slider provides a faster lift off of the head from the disk than prior art designs. As the mean time to failure for start/stop wear is proportional to the distance travelled in contact with the disk, before reaching glide height, the slider of this invention exhibits a significant improvement in start/stop life. Figure lb illustrates an alternative configuration of an air bearing slider in which the rails 22 and 24 are flared so that the recessed area at the trailing edge 26 is narrowed and the negative pressure region is trapezoidal in form. Figure lc illustrates another alternative of an air bearing slider in which the rails 28 and 30 have parallel sections 32 and 34 up to a break point and then have flared sections 36 and 38 extending towards the trailing edge 26. The alternative design of Figure ld includes rails 40 and 42 having parallel sections 44 and 46 and ending in parallel sections 48 and 50 adjacent to the trailing edge 26. It should be understood that the location of the break point is variable, and therefore the lengths of the parallel sections and flared sections are also variable. In addition, the angle of flare of the side rails may be varied. Each of the self-loading slider configurations is characterised by a full width taper section at the leading edge. The taper section is made by lapping, as is well known in the art. The rails may have different configurations that will determine flying height, the stiffness, and stability of the air bearing slider. The slider configurations require only one step to form the recessed section, which may be ten microns in depth relative to the rail surfaces. In an implementation of the invention, a slider is formed that is about four millimeters in length, three millimeters wide and 1.0 millimeters high, with the taper section length from the leading edge to the cross rail being about 0.4 millimeters. Figure 2 represents a side view of the air bearing slider with the recessed section 20 delineated by the dotted line portion. A magnetic transducer head 52 is disposed at the trailing edge so that the transducing gap is at the air bearing surface of the slider. Figure 3 illustrates by curve 54 the fast liftoff of the self-loading slider of this invention to a substantially constant spacing from the disk surface, as compared to the prior art slider slower liftoff with greater variation in head to disk spacing, illustrated by curve 56. The self-loading, air bearing slider of this invention realises a distinct advantage over prior art heads in the fast liftoff performance with resultant increased wear life and, in addition, is easier to fabricate by the one-step processing of the recessed region. The air bearing slider serves to maintain a substantially constant flying height over all the data tracks on a disk surface, thereby minimising the need for recording channel compensation. It should be understood that the slider configuration may be modified within the scope of the invention defined in the claims For example, the side rails may be arcuate in design.

Claims: CLAIMS 1. An air bearing slider for supporting a transducer relative to a moving record medium, the underside of the assembly being formed to provide a pair of spaced apart side rails (14,16;22,24;28,30;40,42) and a cross rail (18) joining the side rails so that there is a recessed section (20) trailing the cross rail and defined on three sides by the three rails, the lower surfaces of the rails being co-planar, characterised in that the slider is chamfered across its whole width from its leading edge (12) down to the cross rail (18). 2. A slider as claimed in claim 1, in which the side rails flare (22,24) from the cross rail so that each of the side rails is wider at the trailing edge (26) of the slider than where it adjoins the cross rail. 3. A slider as claimed in claim 1, in which the side rails are formed so that they have corresponding portions (32,34) of constant width adjoining the cross rail and corresponding flared portions (36,38) extending from the constant width portions to the trailing edge (26) of the slider. 4. A slider as claimed in claim 1, in which the side rails are formed so that they have corresponding portions (Figure ld,32,34) of constant width adjoining the cross rail, intermediate corresponding flared portions (44,46) extending from the trailing ends of the constant width portions and further portions (48,50) of constant width extending from the trailing ends of the flared portions to the trailing edge (26) of the slider. 5. A slider as claimed in any preceding claim, in which the recessed section and the rails have been formed in a single processing step. 6. A slider as claimed in any preceding claim, in which the recessed section has a constant depth. 7. A slider as claimed in any of claims 1 to 5, in which the depth of the recessed section progressively increases from the cross rail to the trailing edge of the slider. 8. An assembly comprising a slider as claimed in any preceding claim and a magnetic transducer head (52) supported on the trailing edge of one of the side rails.

Inventors: GARNIER, MICHAEL FRANKLIN, WARNER, MICHAEL WALTER
Applicants: INTERNATIONAL BUSINESS MACHINES CORPORATION
Application year: 1982
Main classification: G11B21
IPC codes: G11B5, F16C32, G11B21