US3796859A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic ink recording system to both magnetize and read ink
Assignee: International Business Machines Corp
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Filing: 1971-12-27
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Granted: 1974-03-12
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Expires: 1991-12-27
Abstract
Abstract A magnetoresistive recording head is employed to both magnetize magnetic ink on a document as well as to read the magnetized ink prior to its loss of magnetism. A strong magnet produces the desired bias field along the easy axis of the ink to magnetically polarize the ink, but such strong field is applied perpendicular to the magnetoresistive sensing element, which strong field serves only to bias that sensing element, not switch it.
Inventors
- 👤 D Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:41
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; G11B5/39; G06; G06K; G06K7/00; G06K7/08
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
138 words
A recording head for reading magnetic ink on a document in which the ink is magnetized by the same structure that reads the document comprising: a magnet for magnetizing said magnetic ink on the document, a magnetoresistive recording element located within the field of said magnet and in flux-coupling proximity to said document, said magnet being oriented with respect to said magnetoresistive recording element and said document so that substantially the full strength of its magnetic field is imparted to said ink in said document passing under said recording element, but only a small fraction of said magnetic field being effective to supply a magnetic bias in the plane of said magnetoresistive element, wherein said magnetoresistive element is located adjacent said magnet so as to sense said magnetic ink on said document soon after it has been magnetized.
Claim 2
Dependent Claim
138 words
A recording head for reading magnetic ink on a document in which the ink is magnetized by the same structure that reads the document comprising: a magnet for magnetizing said magnetic ink on the document, a magnetoresistive recording element located within the field of said magnet and in flux-coupling proximity to said document, said magnet being oriented with respect to said magnetoresistive recording element and said document so that substantially the full strength of its magnetic field is imparted to said ink in said document passing under said recording element, but only a small fraction of said magnetic field being effective to supply a magnetic bias in the plane of said magnetoresistive element, wherein said magnetoresistive element is located adjacent said magnet so as to sense said magnetic ink on said document soon after it has been magnetized.
Claim 3
Dependent Claim
22 words
The recording head of claim 1 wherein said magnetoresistive element lies in a plane perpendicular to the plane of the inked document.
Claim 4
Dependent Claim
33 words
The recording system of claim 1 wherein means for sensing the change in resistance in said magnetoresistive element as a function of said magnetized ink passing there-under is connected to said magnetoresistive strip.
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) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |