Patent US3843541A successfully refreshed from Google Patents.
US3843541A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic head core of large grain size and low porosity
Assignee: Panasonic Holdings Corp
•
Filing: 1973-03-14
•
Granted: 1974-10-22
•
Expires: 1993-03-14
Abstract
Abstract 1. A MAGNETIC HEAD CORE CONSISTING ESSENTIALLY OF SINTERED FERRITE CONSISTING OF A PLURALITY OF GRAINS, HAVING AN AVERAGE GRAIN SIZE GREATER THAN 30 U AND A POROSITY LESS THAN 0.1% BY VOLUME, AND HAVING A COMPOSITION CONSISTING OF NI-ZN FERRITE, MN-ZN FERRITE, LI-ZN FERRITE, CU-ZN FERRITE, MG-ZN FERRITE OR Y-IRON GARNET.
Inventors
- 👤 E Hirota
- 👤 H Chiba
- 👤 Y Tawara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:53
CPC Classifications
C; C04; C04B; C04B33/00; C04B33/32; C04B33/326; C04B35/00; C04B35/01; C04B35/26; C04B35/265; C04B35/2658; G; G11; G11B; G11B5/00; G11B5/127; G11B5/133; G11B5/187; G11B5/1871; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/34; H01F1/36; H01F1/37; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49034; Y10T29/49048
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
51 words
A MAGNETIC HEAD CORE CONSISTING ESSENTIALLY OF SINTERED FERRITE CONSISTING OF A PLURALITY OF GRAINS, HAVING AN AVERAGE GRAIN SIZE GREATER THAN 30 U AND A POROSITY LESS THAN 0.1% BY VOLUME, AND HAVING A COMPOSITION CONSISTING OF NI-ZN FERRITE, MN-ZN FERRITE, LI-ZN FERRITE, CU-ZN FERRITE, MG-ZN FERRITE OR Y-IRON GARNET.
Claim 2
Dependent Claim
51 words
A MAGNETIC HEAD CORE CONSISTING ESSENTIALLY OF SINTERED FERRITE CONSISTING OF A PLURALITY OF GRAINS, HAVING AN AVERAGE GRAIN SIZE GREATER THAN 30 U AND A POROSITY LESS THAN 0.1% BY VOLUME, AND HAVING A COMPOSITION CONSISTING OF NI-ZN FERRITE, MN-ZN FERRITE, LI-ZN FERRITE, CU-ZN FERRITE, MG-ZN FERRITE OR Y-IRON GARNET.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |