US3681682A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for testing gap surface finish and winding characteristics of a magnetic head subassembly
Assignee: International Business Machines Corp
•
Filing: 1970-12-21
•
Granted: 1972-08-01
•
Expires: 1990-12-21
Abstract
Abstract Surface flatness, magnetic characteristics, electrical connections, etc. of one section of a multi-track magnetic recording head are tested during manufacture and before final assembly. A multi-track head section is mounted in a rotating fixture with the section''s gap faces abutting a dummy block which closes the magnetic circuit. As the fixture is rotated, each track''s winding is connected, in turn, to a vector impedance meter. The meter reading is compared with a predetermined value to indicate whether the head track winding, material, gap surface, etc. are within acceptable limits. A winding around the dummy block aids in determining whether the head windings are properly oriented and additional continuity tests identify open and shorted windings.
Inventors
- 👤 Conrad M Cox
- 👤 Robert B Fischer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:31
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/455; G11B5/127; G11B5/1272; G11B5/17; G11B5/187; G11B5/1871; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49036
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
142 words
Apparatus for simultaneously testing the gap surface finish and winding characteristics of a magnetic head subassembly, comprising: a fixture for firmly holding the head subassembly having a plurality of head windings in a predetermined position; a block, associated with said fixture, firmly held in a predetermined position, mating with the gap surface of the head subassembly, and closing the head magnetic circuit; impedance measuring means, connected to a head winding, for indicating the magnitude and phase of the winding impedance; comparison means, connected to the impedance measuring means, for comparing the impedance measured with a predetermined acceptable impedance; indicating means, connected to the comparison means for indicating when the measured impedance and the acceptable impedance bear a predetermined relationship to identify acceptable and non-acceptable head subassemblies; and switching means for connecting each of the windings in turn to the impedance measuring means.
Claim 2
Dependent Claim
142 words
Apparatus for simultaneously testing the gap surface finish and winding characteristics of a magnetic head subassembly, comprising: a fixture for firmly holding the head subassembly having a plurality of head windings in a predetermined position; a block, associated with said fixture, firmly held in a predetermined position, mating with the gap surface of the head subassembly, and closing the head magnetic circuit; impedance measuring means, connected to a head winding, for indicating the magnitude and phase of the winding impedance; comparison means, connected to the impedance measuring means, for comparing the impedance measured with a predetermined acceptable impedance; indicating means, connected to the comparison means for indicating when the measured impedance and the acceptable impedance bear a predetermined relationship to identify acceptable and non-acceptable head subassemblies; and switching means for connecting each of the windings in turn to the impedance measuring means.
Claim 3
Dependent Claim
57 words
The apparatus of claim 1 wherein the switching means includes contacts and brushes and provides a pedestal for the fixture, rotation of the switching means together with the fixture relative to the brushes presenting the contacts, corresponding to one winding at a time, to the brushes through which the impedance measuring means are connected to the windings.
Claim 4
Dependent Claim
46 words
The apparatus of claim 1 wherein the switching means has a set of contacts for each winding, a plurality of concentric rings and a rotatable central cam, each contact set being made available in turn to a number of the rings by rotation of the cam.
Claim 5
Dependent Claim
48 words
The apparAtus of claim 1 wherein the block includes a notch for carrying a fixed winding, and there are provided phase detection means connected to the switching means and the fixed winding operable to indicate a predetermined relationship between the fixed winding and the head winding under test.
Claim 6
Dependent Claim
46 words
The apparatus of claim 1 wherein there are provided a frame contact to the head subassembly and a continuity testing means connected to the switching means and the frame contact for measuring the existence of undesirable circuits between the head winding under test and the frame.
Claim 7
Independent Claim
145 words
The method of testing a magnetic transducer subassembly, containing a plurality of windings, for electrical, magnetic and material defects, comprising the steps of: fastening the subassembly in a fixed relationship to a dummy component representing another portion of the transducer; connecting a first winding contained in said subassembly to a common set of wires; measuring, at the common set of wires, the magnitude and phase of the impedance of the first winding; comparing the measured impedance with a predetermined impedance; connecting additional windings contained in said sub-assembly, one at a time, to the common set of wires and measuring and comparing the magnitude and phase of the impedance of each of the windings in turn; and passing transducers having windings which are all within a fixed range of the predetermined impedance and rejecting transducers having any one winding which is not within said fixed range.
Claim 8
Independent Claim
145 words
The method of testing a magnetic transducer subassembly, containing a plurality of windings, for electrical, magnetic and material defects, comprising the steps of: fastening the subassembly in a fixed relationship to a dummy component representing another portion of the transducer; connecting a first winding contained in said subassembly to a common set of wires; measuring, at the common set of wires, the magnitude and phase of the impedance of the first winding; comparing the measured impedance with a predetermined impedance; connecting additional windings contained in said sub-assembly, one at a time, to the common set of wires and measuring and comparing the magnitude and phase of the impedance of each of the windings in turn; and passing transducers having windings which are all within a fixed range of the predetermined impedance and rejecting transducers having any one winding which is not within said fixed range.
Claim 9
Dependent Claim
33 words
The method of claim 6 wherein the dummy component carries a winding and the polarity of each transducer subassembly winding is determined by comparing it to the polarity of the dummy subassembly winding.
Claim 10
Dependent Claim
151 words
In combination: a first subassembly of a magnetic transducer comprising a plurality of windings retained in a housing having a flat face intended to intimately mate with a flat face on a second sub-assembly of the transducer; a substantially metallic block, representing the second subassembly, having a face of known flatness matable with the flat face of the first subassembly and a winding upon the block having a known winding direction; a fixture for fixing in position the first subassembly and metallic block with the flat faces intimately mated and providing, for external utilization, electrical connections to the transducer windings; impedance measuring means connected to the fixture electrical connections to establish the flatness of the first subassembly face; and winding direction determining means connected to the fixture electrical connections and the block winding for comparing the transducer winding directions with the known block winding direction to establish each transducer winding''s direction.
Claim 11
Dependent Claim
151 words
In combination: a first subassembly of a magnetic transducer comprising a plurality of windings retained in a housing having a flat face intended to intimately mate with a flat face on a second sub-assembly of the transducer; a substantially metallic block, representing the second subassembly, having a face of known flatness matable with the flat face of the first subassembly and a winding upon the block having a known winding direction; a fixture for fixing in position the first subassembly and metallic block with the flat faces intimately mated and providing, for external utilization, electrical connections to the transducer windings; impedance measuring means connected to the fixture electrical connections to establish the flatness of the first subassembly face; and winding direction determining means connected to the fixture electrical connections and the block winding for comparing the transducer winding directions with the known block winding direction to establish each transducer winding''s direction.
Claim 12
Dependent Claim
99 words
The combination of claim 8 wherein the winding direction determining means includes: a pulse source connected to a selected one of the fixture electrical connections and the block winding, for supplying a pulse of known polarity; a pulse detector, connected to one of the fixture electrical connections and the block winding, other than the one selected for connection to said source, for detecting the polarity of a signal induced by aforesaid pulse; and comparison means, associated with the pulse source and detector for determining the relative polarities of the generated pulses and induced signal thereby deducing transducer winding direction.
Claim 13
Dependent Claim
143 words
Apparatus for testing the gap surface finish of a magnetic head subassembly, having a number of head windings, comprising: a fixture for firmly holding a head subassembly to be tested in a predetermined position; a dummy head subassembly, firmly held in a predetermined position in said fixture, mating with the gap surface of the head subassembly; impedance measuring means, connected to a selected one a said number of head windings, for indicating the magnitude and phase of the winding impedance; comparison means, connected to the imPedance measuring means, for comparing the impedance measured with a predetermined acceptable impedance; indicating means, connected to the comparison means for indicating when the measured impedance and the acceptable impedance bear a predetermined relationship to identify acceptable and non-acceptable tested head subassemblies; and switching means for connecting each of the windings in turn to the impedance measuring means.
Claim 14
Dependent Claim
143 words
Apparatus for testing the gap surface finish of a magnetic head subassembly, having a number of head windings, comprising: a fixture for firmly holding a head subassembly to be tested in a predetermined position; a dummy head subassembly, firmly held in a predetermined position in said fixture, mating with the gap surface of the head subassembly; impedance measuring means, connected to a selected one a said number of head windings, for indicating the magnitude and phase of the winding impedance; comparison means, connected to the imPedance measuring means, for comparing the impedance measured with a predetermined acceptable impedance; indicating means, connected to the comparison means for indicating when the measured impedance and the acceptable impedance bear a predetermined relationship to identify acceptable and non-acceptable tested head subassemblies; and switching means for connecting each of the windings in turn to the impedance measuring means.
Claim 15
Dependent Claim
51 words
The apparatus of claim 10 wherein the switching means provides contacts and brushes and a pedestal for the fixture, whereby rotation of the switching means together with the fixture presents the contacts, corresponding to one winding at a time, to the brushes to connect the impedance measuring means to the windings.
Claim 16
Dependent Claim
46 words
The apparatus of claim 10 wherein the switching means further includes concentric rings and a central cam, there being a set of contacts for each winding, each set of contacts being made available in turn to a set of concentric rings by rotation of the cam.
Claim 17
Independent Claim
141 words
The method of testing a subassembly of a magnetic transducer having a plurality of windings, comprising the steps of: fastening the subassembly in a fixed relationship to a dummy component representing another portion of the transducer; connecting a first of said plurality of windings to a common set of wires; measuring, at the common set of wires, the magnitude and phase of the impedance of the first winding; comparing the measured impedance with a predetermined impedance; connecting others of said plurality of windings, one at a time, to the common set of wires and measuring and comparing the magnitude and phase of the impedance of each of the windings in turn; and passing transducers giving measurements which are all within a fixed range of the predetermined impedance and rejecting transducers having any one measurement which is not within said fixed range.
Claim 18
Independent Claim
141 words
The method of testing a subassembly of a magnetic transducer having a plurality of windings, comprising the steps of: fastening the subassembly in a fixed relationship to a dummy component representing another portion of the transducer; connecting a first of said plurality of windings to a common set of wires; measuring, at the common set of wires, the magnitude and phase of the impedance of the first winding; comparing the measured impedance with a predetermined impedance; connecting others of said plurality of windings, one at a time, to the common set of wires and measuring and comparing the magnitude and phase of the impedance of each of the windings in turn; and passing transducers giving measurements which are all within a fixed range of the predetermined impedance and rejecting transducers having any one measurement which is not within said fixed range.
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) | 1975-08-01 | 1976-01-31 | 1976-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-01 | 1980-01-31 | 1980-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-01 | 1984-01-31 | 1984-08-01 | $7700.00 | Window Closed / Lapsed |