Patent US3249987A successfully refreshed from Google Patents.
US3249987A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing magnetic heads
Assignee: US Philips Corp
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Filing: 1962-03-05
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Granted: 1966-05-10
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Expires: 1982-03-05
Abstract
No abstract record available.
Inventors
- 👤 Duinker Simon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:59
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/1871; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49036; Y10T29/49041; Y10T29/49048; Y10T29/49055; Y10T29/49057; Y10T29/49787
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
216 words
A METHOD OF MANUFACTURING POLE PIECES OF A MAGNETIC HEAD HAVING A VERY SHORT GAP LENGTH AND A PRECISE GAP HEIGHT, COMPRISING: CUTTING A CROSS GROOVE IN A FIRST FERRITE PLATE SURFACE AND SPACED FROM ONE END THEREOF, SAID GROOVE EXTENDING ACROSS THE ENTIRE LATERAL DIMENSION OF SAID PLATE, SECURING PERMANENTLY A COOPERATING REINFORCING BAR OF NON-MAGNETIC MATERIAL LONGER THAN SAID LATERAL DIMENSION IN SAID GROOVE, SAID BAR THUS HAVING A LIMB EXTENDING BEYOND SAID PLATE TO ACT AS A REFERENCE TO ATTAIN SAID GAP HEIGHT, MACHINING A PORTION OF SAID PLATE AND A PORTION OF SAID BAR TO A PREDETERMINED CONFIGURATION TO FORM A FIRST SURFACE EXTENDING FROM SAID ONE END, THEREBY DEFINING COIL MOUNTING MEANS, GRINDING AND POLISHING THE REMAINING PORTIONS OF SAID PLATE SURFACE AND BAR TO FORM A SECOND CONTINUOUS PLANAR SURFACE, GRINDING AND POLISHING ONE PLANAR SURFACE OF A SECOND MAGNETIC PLATE, SECURING PERMANENTLY SAID GROUND AND POLISHED SURFADES TO EACH OTHER WITH THE INTERPOSITION OF A GAP-FORMING THIN LAYER OF NONMAGNETIC ADHESIVE TO DEFINE THE GAP LENGTH, CUTTING THE RESULTANT ASSEMBLY THROUGH THE PLATES SUBSTANTIALLY PARALLEL TO SAID LIMB TO FORM A POLEFACE, AND GRINDING AND POLISHING SAID POLEFACE UNTIL THE CORRECT GAP HEIGHT IS REACHED BY USING SAID EXTENDING LIMB AS A REFERENCE TO ATTAIN SAID CORRECT GAP HEIGHT.
Claim 2
Independent Claim
216 words
A METHOD OF MANUFACTURING POLE PIECES OF A MAGNETIC HEAD HAVING A VERY SHORT GAP LENGTH AND A PRECISE GAP HEIGHT, COMPRISING: CUTTING A CROSS GROOVE IN A FIRST FERRITE PLATE SURFACE AND SPACED FROM ONE END THEREOF, SAID GROOVE EXTENDING ACROSS THE ENTIRE LATERAL DIMENSION OF SAID PLATE, SECURING PERMANENTLY A COOPERATING REINFORCING BAR OF NON-MAGNETIC MATERIAL LONGER THAN SAID LATERAL DIMENSION IN SAID GROOVE, SAID BAR THUS HAVING A LIMB EXTENDING BEYOND SAID PLATE TO ACT AS A REFERENCE TO ATTAIN SAID GAP HEIGHT, MACHINING A PORTION OF SAID PLATE AND A PORTION OF SAID BAR TO A PREDETERMINED CONFIGURATION TO FORM A FIRST SURFACE EXTENDING FROM SAID ONE END, THEREBY DEFINING COIL MOUNTING MEANS, GRINDING AND POLISHING THE REMAINING PORTIONS OF SAID PLATE SURFACE AND BAR TO FORM A SECOND CONTINUOUS PLANAR SURFACE, GRINDING AND POLISHING ONE PLANAR SURFACE OF A SECOND MAGNETIC PLATE, SECURING PERMANENTLY SAID GROUND AND POLISHED SURFADES TO EACH OTHER WITH THE INTERPOSITION OF A GAP-FORMING THIN LAYER OF NONMAGNETIC ADHESIVE TO DEFINE THE GAP LENGTH, CUTTING THE RESULTANT ASSEMBLY THROUGH THE PLATES SUBSTANTIALLY PARALLEL TO SAID LIMB TO FORM A POLEFACE, AND GRINDING AND POLISHING SAID POLEFACE UNTIL THE CORRECT GAP HEIGHT IS REACHED BY USING SAID EXTENDING LIMB AS A REFERENCE TO ATTAIN SAID CORRECT GAP HEIGHT.
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) | 1969-05-09 | 1969-11-08 | 1970-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1973-05-09 | 1973-11-08 | 1974-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1977-05-09 | 1977-11-08 | 1978-05-10 | $7700.00 | Window Closed / Lapsed |