US4527480A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Means for the deactivation of electric blasting caps
Assignee: United States, TRANSPORATION, Secretary of, Department of
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Filing: 1981-07-14
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Granted: 1985-07-09
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Expires: 2001-07-14
Abstract
Abstract An electric blasting cap designed to be permanently disabled by the application of an external magnetic field. The cap contains a magnetic reed switch which creates an open circuit or a short circuit to prevent current from reaching the bridge wire. One embodiment of the switch is operated by a magnetizing field, the other is operated by a demagnetizing field.
Inventors
- 👤 Gerald Carp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:22
CPC Classifications
F; F42; F42C; F42C19/00; F42C19/06; F42B; F42B3/00; F42B3/10; F42B3/12; F42B3/124
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
51 words
A blasting cap comprising: an explosive charge; electrical ignition means to ignite said explosive charge, said ignition means comprising a normally continuous electric circuit; and nonexplosive means within said electrical ignition means to permanently disable said ignition means, said means to permanently disable said ignition means comprising a magnetic reed switch.
Claim 2
Dependent Claim
51 words
A blasting cap comprising: an explosive charge; electrical ignition means to ignite said explosive charge, said ignition means comprising a normally continuous electric circuit; and nonexplosive means within said electrical ignition means to permanently disable said ignition means, said means to permanently disable said ignition means comprising a magnetic reed switch.
Claim 3
Dependent Claim
25 words
A blasting cap as in claim 1 wherein said magnetic reed switch moves to its disabling position upon the application of an external magnetizing field.
Claim 4
Dependent Claim
25 words
A blasting cap as in claim 1 wherein said magnetic reed switch moves to its disabling position upon the application of an external demagnetizing field.
Claim 5
Dependent Claim
30 words
A blasting cap as in claim 1 wherein said magnetic reed switch creates an open circuit within said electrical ignition means when said magnetic switch is in its disabling position.
Claim 6
Dependent Claim
29 words
A blasting cap as in claim 1 wherein said magnetic reed switch creates a short circuit within said ignition means when said magnetic switch is in its disabling position.
Claim 7
Dependent Claim
42 words
A blasting cap as in claim 1 wherein said magnetic switch creates both a short circuit at a first point and an open circuit at a second point within said ignition means when said magnetic reed switch is in its disabling position.
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) | 1988-07-08 | 1989-01-07 | 1989-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-08 | 1993-01-07 | 1993-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-08 | 1997-01-07 | 1997-07-09 | $7700.00 | Window Closed / Lapsed |