US4136373A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bulk tape eraser
Assignee: Weircliffe International Ltd
•
Filing: 1977-05-09
•
Granted: 1979-01-23
•
Expires: 1997-05-09
Abstract
Abstract In a bulk tape eraser, the outer edge of one outer limb of an E shaped electromagnet on which the energizing coil is mounted is chamfered inwardly to form said outer limb with a narrow free end adjacent its inner edge which directs substantially the whole of the magnetic flux to the central limb of the magnet.
Inventors
- 👤 Raymond E. Amos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:43
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; G11B5/024; G11B5/0245; H; H01; H01F; H01F13/00; H01F13/006; H01F7/00; H01F7/06
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
185 words
A bulk tape eraser for erasing magnetic tape in bulk form, comprising an E-shaped magnet built up of laminations of magnetic material having a central limb and two outer limbs, said three limbs having free ends which are substantially colinear, said outer limbs extending substantially parallel to one another and to said central limb, and an energizing coil surrounding one of said two outer limbs, the outer edge of said one of said outer limbs being chamfered at the free end of said limb toward the inner edge of said limb at an angle between 55° and 65° to leave said limb with a narrow free end having a width equal to about one fifth of the width of the unchamfered portion of said limb, whereby magnetic flux from said one of said outer limbs is directed substantially entirely to said central limb and produces a magnetic field of high intensity which extends in an arc through a region between and above the free ends of said one outer limb and said central limb through which region a bulk tape may be passed for erasure.
Claim 2
Dependent Claim
185 words
A bulk tape eraser for erasing magnetic tape in bulk form, comprising an E-shaped magnet built up of laminations of magnetic material having a central limb and two outer limbs, said three limbs having free ends which are substantially colinear, said outer limbs extending substantially parallel to one another and to said central limb, and an energizing coil surrounding one of said two outer limbs, the outer edge of said one of said outer limbs being chamfered at the free end of said limb toward the inner edge of said limb at an angle between 55° and 65° to leave said limb with a narrow free end having a width equal to about one fifth of the width of the unchamfered portion of said limb, whereby magnetic flux from said one of said outer limbs is directed substantially entirely to said central limb and produces a magnetic field of high intensity which extends in an arc through a region between and above the free ends of said one outer limb and said central limb through which region a bulk tape may be passed for erasure.
Claim 3
Dependent Claim
20 words
A bulk tape eraser as defined in claim 1, wherein said outer limb is chamfered at an angle of 60°.
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) | 1982-01-22 | 1982-07-24 | 1983-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-01-22 | 1986-07-24 | 1987-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-01-22 | 1990-07-24 | 1991-01-23 | $7700.00 | Window Closed / Lapsed |