Measuring and testing – Surface and cutting edge testing – Roughness
Reexamination Certificate
1998-05-05
2001-08-07
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Surface and cutting edge testing
Roughness
Reexamination Certificate
active
06269687
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a force sensing disc drive slider, and more particularly to a disc drive slider having a capacitance sensor responsive to forces acting on a contact pad that does not affect the aerodynamic characteristics of the slider.
In a disc drive system, the contact force between a slider carrying a transducing head and a disc media perpendicular to the surface of the disc media is a very important parameter. It is desirable to accurately measure this force in order to obtain a quantitative understanding of a variety of head-to-disc interface phenomena such as friction, vibration and wear, for example, particularly in planar slider systems where the transducing head is somewhat exposed at the air-bearing surface. These measurements enable slider glidability, seek and take-off characteristics to be analyzed for potential improvements in the slider architecture. The debris generation and wear characteristics of the head-to-disc interface could also be measured through mapping of the contact force measurements. The uniformity of the surface of the disc media could be tested and certified by analyzing these measurements. Other applications utilizing quantitative measurements of the contact force between the slider and disc media perpendicular to the disc surface will be apparent to one skilled in the art.
In order for the contact force measurements to be useful, the slider incorporating the contact force sensor must exhibit the same aerodynamic behavior as an actual slider for carrying a transducing head. Therefore, the contact force sensor must be implemented within the physical dimensions of an actual slider. The fabrication of the contact force sensor should not affect the fabrication process used in forming the air-bearing surface (ABS) of the slider. The resulting slider containing the contact force sensor must be attachable to a suspension in the same manner as a head-carrying slider, and the wire leads of the force-sensing slider should be located in a manner similar to the head-carrying slider.
Attempts have been made to estimate the contact force between the slider and disc media indirectly using acoustic emission signals. However, the physical phenomena occurring in this acoustic emission process are extremely complicated, such that some sort of direct measurement is necessary as a reference or calibration point for this method to yield results with any level of accuracy.
Another approach to measuring the contact force at the head-to-disc interface has been to incorporate a piezoelectric element onto a test slider, with the voltage across the piezoelectric element representing a strain force applied to the piezoelectric element due to forces acting on the test slider. While this approach is able to detect forces acting on the slider, such as forces due to the slider contacting debris or an asperity on the disc surface, it is difficult to isolate the z-component of the force (perpendicular or normal to the nominal disc surface) from the overall signal. The signal interpretation process to determine this perpendicular force component is extremely complex, and involves significant material research.
Therefore, there is a need in the art for a readily implemented contact force sensor for use with a standard slider, with minimal signal interpretation involved in analyzing the contact force at the head-to-disc interface perpendicular to the surface of the disc media.
BRIEF SUMMARY OF THE INVENTION
The present invention is a disc drive test slider apparatus for measuring contact force perpendicular to a surface of a rotating disc media. A slider body is positioned proximate the surface of the rotating disc. An air-bearing surface of the slider body is substantially parallel to the nominal surface of the disc and is separated from the surface of the disc by a glide height. The slider body includes a cavity having a side wall substantially normal to the surface of the disc and a wall substantially parallel to the surface of the disc. A beam flexure is attached to the side wall of the cavity. A plate is attached to the beam flexure in the cavity, and the beam flexure has a spring resiliency to permit movement of the plate in the cavity substantially normal to the surface of the disc. A contact rod is attached to the plate, and extends through the cavity and a via in the slider body. The contact rod has a distal tip projecting from the air-bearing surface. A force applied to the contact rod perpendicular to the surface of the rotating disc media causes displacement of the plate normal to the surface of the disc.
In one embodiment, metal films are formed on the plate and on the wall of the cavity substantially parallel to the surface of the disc. The metal films confront one another, and a change in capacitance between the metal films due to changes in a gap distance between the metal films caused by displacement of the plate normal to the surface of the disc is determined.
Another aspect of the present invention is a process of forming a disc drive test slider for measuring contact force perpendicular to a surface of a rotating disc media. A slider body is provided, and a cavity is formed in the slider body through the air-bearing surface between the leading edge surface and the trailing edge surface of the slider body. The cavity has a first wall substantially parallel to the air-bearing surface and a second wall substantially normal to the air-bearing surface. A first metal film is deposited on the first wall of the cavity. A sacrificial layer is formed over the first metal film. A second metal film is deposited on the first sacrificial layer. A first slider body material layer is deposited over the first sacrificial layer and the second metal film to fill the cavity, with the first slider body material layer projecting beyond the level of the air-bearing surface. The first slider body material layer is etched to form a beam flexure attached to the second wall of the cavity, a plate attached to the beam flexure, and a contact rod projecting from the plate beyond the level of the air-bearing surface. A second sacrificial layer is deposited on the beam flexure, plate and first sacrificial layer. A second slider body material layer is deposited on the second sacrificial layer to the level of the air-bearing surface, leaving a gap around the contact rod. The features of the air bearing surface of the slider body are defined. The first and second sacrificial layers are then removed, so that the plate is movable normal to the air-bearing surface in response to a force applied to the contact rod normal to the air-bearing surface of the slider body.
A further aspect of the invention is a method of measuring contact force between a disc drive test slider and a rotating disc media. A mechanical assembly is provided in the slider that is displaceable in response to the contact force, the assembly providing a mechanical force to oppose the contact force. The mechanical force increases with displacement of the assembly. The disc drive test slider is operated so that contact force is applied to the mechanical assembly, and the displacement of the mechanical assembly is measured.
REFERENCES:
patent: 4605977 (1986-08-01), Matthews
patent: 4620251 (1986-10-01), Gitzendanner
patent: 4651242 (1987-03-01), Hirano et al.
patent: 4853810 (1989-08-01), Pohl et al.
patent: 4962391 (1990-10-01), Kitahara et al.
patent: 5021906 (1991-06-01), Chang et al.
patent: 5034828 (1991-07-01), Ananth et al.
patent: 5065268 (1991-11-01), Hagen
patent: 5072240 (1991-12-01), Miyazawa et al.
patent: 5079659 (1992-01-01), Hagen
patent: 5105408 (1992-04-01), Lee et al.
patent: 5189578 (1993-02-01), Mori et al.
patent: 5255016 (1993-10-01), Usui et al.
patent: 5276573 (1994-01-01), Harada et al.
patent: 5552809 (1996-09-01), Hosono et al.
patent: 5657188 (1997-08-01), Jurgenson et al.
patent: 5915271 (1999-06-01), Berg et al.
patent: 6016692 (2000-01-01), Schaenzer et al.
patent: 6053057 (2000-04-01), Okada
“Silicon Micromachined Electromagnet Microactuators for Rigid
Schaenzer Mark J.
Segar Peter R.
Zhang Jing
Zhang Lei
Fuller Benjamin R.
Kinney & Lange
Seagate Technology LLC
Thompson Jewel V.
LandOfFree
Force sensing slider does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Force sensing slider, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Force sensing slider will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2488878