Patent US4610731A successfully refreshed from Google Patents.
Patent US2919745A successfully refreshed from Google Patents.
Patent US5576085A successfully refreshed from Google Patents.
US5576085A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thin-film recording medium with soft magnetic layer
Assignee: HMT Technology Corp
•
Filing: 1993-11-01
•
Granted: 1996-11-19
•
Expires: 2013-11-01
Abstract
Abstract A magnetic thin-film medium having improved magnetic recording properties, including an increased magnetic remanence and high frequency signal amplitude, is disclosed. The magnetic recording medium has a 10-100 Å soft ferromagnetic layer in addition to a substrate, a chromium underlayer, a thin-film magnetic recording layer and a protective overcoat.
Inventors
- 👤 Brij B. Lal
- 👤 Tadashi Shinohara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:56
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/7368; G11B5/7373; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
140 words
A magnetic recording system, comprising; a magnetic recording medium having a substrate, a sputtered chromium underlayer, a sputtered thin-film recording magnetic layer, a sputtered soft ferromagnetic film having a thickness between about 10-100 Å, and a sputtered carbon overcoat, said medium having an inner diameter edge and an outer diameter edge, means for rotating the medium, and a zero-bias read-write head, effective to read and write magnetic signals to the medium, when the head is positioned above the rotating medium, wherein said system is characterized by a high frequency signal amplitude, measured at a region adjacent said outer edge using a zero-bias read-write head operating at 18 MHz, that is greater than the high frequency signal amplitude of a medium having a substrate, a chromium underlayer, a magnetic recording layer and a carbon overcoat, but lacking said soft ferromagnetic film.
Claim 2
Dependent Claim
140 words
A magnetic recording system, comprising; a magnetic recording medium having a substrate, a sputtered chromium underlayer, a sputtered thin-film recording magnetic layer, a sputtered soft ferromagnetic film having a thickness between about 10-100 Å, and a sputtered carbon overcoat, said medium having an inner diameter edge and an outer diameter edge, means for rotating the medium, and a zero-bias read-write head, effective to read and write magnetic signals to the medium, when the head is positioned above the rotating medium, wherein said system is characterized by a high frequency signal amplitude, measured at a region adjacent said outer edge using a zero-bias read-write head operating at 18 MHz, that is greater than the high frequency signal amplitude of a medium having a substrate, a chromium underlayer, a magnetic recording layer and a carbon overcoat, but lacking said soft ferromagnetic film.
Claim 3
Dependent Claim
17 words
The system of claim 1, wherein said soft ferromagnetic film has a thickness between about 20-60 Å.
Claim 4
Dependent Claim
16 words
The system of claim 1, wherein said soft ferromagnetic film is composed of a nickel/iron alloy.
Claim 5
Dependent Claim
88 words
The system of claim 1, wherein said soft ferromagnetic film has a thickness of about 20-40 Å, and said magnetic recording medium is further characterized by one or more of the following: (a) reduction in bit-shift, as measured by recording a ditbit pattern; (b) increase in overwrite, as measured at two frequencies using a read-write analyzer; and (c) increase in DC-signal to noise ratio, taken as the ratio of peak-to-peak amplitude of a single pulse as a function of recording frequency to the recording noise at that frequency.
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) | 1999-11-19 | 2000-05-20 | 2000-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-19 | 2004-05-20 | 2004-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-19 | 2008-05-20 | 2008-11-19 | $7700.00 | Window Closed / Lapsed |