US3683273A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring fluid film bearings
Assignee: Unisys Corp
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Filing: 1970-02-27
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Granted: 1972-08-08
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Expires: 1990-02-27
Abstract
Abstract A technique particularly useful for measuring the flying characteristics of a magnetic recording head on an air bearing adjacent a rotating disk is described. According to this technique one of a plurality of magnetic transducers mounted in the moving disk records a line of signals of known amplitude and wavelength on a magnetic recording surface placed on the recording head being evaluated. The signal amplitude is read from this line of recorded signals as the disk rotates, and the relative spacing between the head and disk at two points on the head is determined from the relative amplitudes of the signals from the two points. In this way, the pitch, roll and deformation of the recording head can be measured in a dynamic situation.
Inventors
- 👤 Michael I Behr
- 👤 Robert A Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:16
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/60; G11B5/6005; G11B21/00; G11B21/16; G11B21/20; G11B21/21; G11B33/00; G11B33/10; G11B5/10; G11B5/455
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
150 words
In an apparatus for measuring relative thickness of a fluid film bearing between a rotatable member having a first fluid film bearing surface and a stationary inactive or simulated recording head having a second fluid film bearing surface and a recording medium on the head bearing surface the improvement comprising: means for mounting a stationary inactive or simulated recording head adjacent the rotatable member; means for rotating the rotatable member; a magnetic transducer in the rotatable member and adjacent the fluid film bearing surface thereof; means for applying a cyclically varying write signal of known wavelength by way of the magnetic transducer to the recording medium on the stationary inactive or simulated recording head while the rotatable member is rotating; means for receiving a read signal from the transducer while the rotatable member is rotating; and means for measuring the amplitude of the read signal as a function of time.
Claim 2
Dependent Claim
150 words
In an apparatus for measuring relative thickness of a fluid film bearing between a rotatable member having a first fluid film bearing surface and a stationary inactive or simulated recording head having a second fluid film bearing surface and a recording medium on the head bearing surface the improvement comprising: means for mounting a stationary inactive or simulated recording head adjacent the rotatable member; means for rotating the rotatable member; a magnetic transducer in the rotatable member and adjacent the fluid film bearing surface thereof; means for applying a cyclically varying write signal of known wavelength by way of the magnetic transducer to the recording medium on the stationary inactive or simulated recording head while the rotatable member is rotating; means for receiving a read signal from the transducer while the rotatable member is rotating; and means for measuring the amplitude of the read signal as a function of time.
Claim 3
Dependent Claim
22 words
An apparatus as defined in claim 1 wherein the rotatable member comprises a disk having a magnetic transducer adjacent one face thereof.
Claim 4
Dependent Claim
165 words
In an apparatus for measuring relative thickness of a fluid film bearing between a rotatable member having a first fluid film bearing surface, and a stationary inactive or simulated recording head having a second fluid film bearing surface and a recording medium on the head bearing surface the improvement comprising: means for mounting a stationary inactive or simulated recording head adjacent the rotatable member; means for rotating the rotatable member; a magnetic transducer in the rotatable member and adjacent the fluid film bearing surface thereof; means for sensing rotational position of the rotatable member; means responsive to the means for sensing for applying a cyclically varying write signal of known wavelength by way of tHe magnetic transducer to the recording medium on the stationary inactive or simulated recording head while the rotatable member is rotating; means for receiving a read signal from the transducer while the rotatable member is rotating; and means for measuring the amplitude of the read signal as a function of time.
Claim 5
Dependent Claim
165 words
In an apparatus for measuring relative thickness of a fluid film bearing between a rotatable member having a first fluid film bearing surface, and a stationary inactive or simulated recording head having a second fluid film bearing surface and a recording medium on the head bearing surface the improvement comprising: means for mounting a stationary inactive or simulated recording head adjacent the rotatable member; means for rotating the rotatable member; a magnetic transducer in the rotatable member and adjacent the fluid film bearing surface thereof; means for sensing rotational position of the rotatable member; means responsive to the means for sensing for applying a cyclically varying write signal of known wavelength by way of tHe magnetic transducer to the recording medium on the stationary inactive or simulated recording head while the rotatable member is rotating; means for receiving a read signal from the transducer while the rotatable member is rotating; and means for measuring the amplitude of the read signal as a function of time.
Claim 6
Independent Claim
120 words
A method for evaluating a fluid film bearing between a first member and a second member movable relative to each other comprising the steps of: recording magnetic signals of known wavelength lambda on the first member; reading a first signal amplitude A1 at a first point on the first member with a magnetic transducer mounted in the second member; reading a second signal amplitude A2 at a second point on the first member with the same magnetic transducer; and determining the difference in fluid film thickness at the first point and the second point from the equation A1/A2 e 2 (d d )/ , where d1-d2 is the difference in fluid film thickness at the first and second points, respectively.
Claim 7
Independent Claim
120 words
A method for evaluating a fluid film bearing between a first member and a second member movable relative to each other comprising the steps of: recording magnetic signals of known wavelength lambda on the first member; reading a first signal amplitude A1 at a first point on the first member with a magnetic transducer mounted in the second member; reading a second signal amplitude A2 at a second point on the first member with the same magnetic transducer; and determining the difference in fluid film thickness at the first point and the second point from the equation A1/A2 e 2 (d d )/ , where d1-d2 is the difference in fluid film thickness at the first and second points, respectively.
Claim 8
Dependent Claim
54 words
A method as defined in claim 4 wherein the fluid film bearing is between a recording head and a rapidly rotating disk comprising the additional steps of: providing a magnetic recording medium on the bearing face of the recording head; and reading the magnetic signal amplitudes with a magnetic transducer mounted in the disk.
Claim 9
Independent Claim
192 words
An apparatus for measuring the flying characteristics of a recording head adjacent a rapidly rotating disk comprising: a rotatable disk having at least one smooth face; means for rotating the rotatable disk; a recording head adjacent a face of the disk and adapted to form a fluid film bearing between a bearing surface of the recording head and the smooth face of the disk; a magnetic recording medium on the bearing surface of the recording head; a magnetic transducer mounted in the disk and having a magnetic gap adjacent the smooth face of the disk; means for sensing disk rotation and providing output signals indicative of disk rotation; write driver means coupled to the means for sensing and to the transducer for applying varying signals to the transducer responsive to shaft rotation for applying varying magnetic signals of known wavelength to the magnetic recording medium on the bearing surface of the recording head; means for transmitting signals to and from the transducer while the disk is rotating; and means for receiving signals sensed by the transducer from the recorded signals on the magnetic medium and for indicating amplitude of the sensed signals.
Claim 10
Independent Claim
192 words
An apparatus for measuring the flying characteristics of a recording head adjacent a rapidly rotating disk comprising: a rotatable disk having at least one smooth face; means for rotating the rotatable disk; a recording head adjacent a face of the disk and adapted to form a fluid film bearing between a bearing surface of the recording head and the smooth face of the disk; a magnetic recording medium on the bearing surface of the recording head; a magnetic transducer mounted in the disk and having a magnetic gap adjacent the smooth face of the disk; means for sensing disk rotation and providing output signals indicative of disk rotation; write driver means coupled to the means for sensing and to the transducer for applying varying signals to the transducer responsive to shaft rotation for applying varying magnetic signals of known wavelength to the magnetic recording medium on the bearing surface of the recording head; means for transmitting signals to and from the transducer while the disk is rotating; and means for receiving signals sensed by the transducer from the recorded signals on the magnetic medium and for indicating amplitude of the sensed signals.
Claim 11
Dependent Claim
83 words
An apparatus as defined in claim 6 further comprising: a plurality of magnetic transducers on the disk an having their respective magnetic gaps on the smooth face of the disk, each of the transducers being on a different radius from other of the transducers and being a different distance from the center of the disk than other of the transducers for sweeping separate concentric paths across the magnetic medium as the disk rotates and for sequentially sweeping across the paths one after another.
Claim 12
Dependent Claim
121 words
A combination comprising: a rotatable disk; a plurality of magnetic transducers in the disk, each having a magnetic gap adjacent the face of the disk, said transducers each being at a different angular position on the disk from the other transducers and at a different distance from the center of the disk from the other transducers; means for conducting write and read signals to and from the transducers; means for rotating the disk; means for applying a cyclically varying write signal of known wavelength to the transducers while the disk is rotating; means for receiving a read signal from the transducers while the disk is rotating; and means for measuring the amplitude of the read signal as a function of time.
Claim 13
Dependent Claim
121 words
A combination comprising: a rotatable disk; a plurality of magnetic transducers in the disk, each having a magnetic gap adjacent the face of the disk, said transducers each being at a different angular position on the disk from the other transducers and at a different distance from the center of the disk from the other transducers; means for conducting write and read signals to and from the transducers; means for rotating the disk; means for applying a cyclically varying write signal of known wavelength to the transducers while the disk is rotating; means for receiving a read signal from the transducers while the disk is rotating; and means for measuring the amplitude of the read signal as a function of time.
Claim 14
Dependent Claim
24 words
A combination as defined in claim 8 Wherein the plurality of transducers are arranged in a spiral path on a face of the disk.
Claim 15
Dependent Claim
28 words
A combination as defined in claim 8 further comprising means for selectively and alternatively connecting said transducers in series with each other and in parallel with each other.
Claim 16
Dependent Claim
99 words
A combination as defined in claim 10 wherein the means for connecting comprises: a non-conductive substrate connected to one face of the disk; a plurality of conductive areas on the substrate; means for connecting three of said conductive areas with each of the transducers; three conductive paths on the substrate; means for selectively interconnecting conductive areas associated with one transducer with corresponding conductive areas associated with a second transducer for connecting the transducers in series, or connecting the conductive areas associated with a plurality of transducers with selected ones of the conductive paths for connecting the transducers in parallel.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |