US3818226A
Expired / Lapsed
US
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Identity document and a method and an apparatus for checking such a document
Assignee: ID KORT AB
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Filing: 1971-06-07
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Granted: 1974-06-18
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Expires: 1991-06-07
Abstract
Abstract An identity document contains a small quantity of a nonradioactive trace element. The trace element may be an element which absorbs thermal neutrons. In this case the identity document is checked by sending a flow of thermal neutrons through the document and measuring the absorption of the neutrons. Alternatively, the trace element may be an element which, upon being exposed to neutron radioation, creates a secondary radiation. In this case the identity document is checked by exposing the document to thermal neutrons and measuring the secondary radiation.
Inventors
- 👤 O Strindehag
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:53
CPC Classifications
G; G07; G07F; G07F7/00; G07F7/08; G07F7/086; G06; G06K; G06K19/00; G06K19/06; G06K19/08; G06K19/10
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
57 words
A document subject to identification by production of secondary radiation and which incorporates isotopes of a trace element which after neutron irradiation emits beta or gamma radiation, said isotopes having a beta or gamma radiation of higher intensity than has the natural isotope composition thereof, and which is selected from the group consisting of silver and rhodium.
Claim 2
Dependent Claim
57 words
A document subject to identification by production of secondary radiation and which incorporates isotopes of a trace element which after neutron irradiation emits beta or gamma radiation, said isotopes having a beta or gamma radiation of higher intensity than has the natural isotope composition thereof, and which is selected from the group consisting of silver and rhodium.
Claim 3
Dependent Claim
61 words
A document subject to identification by absorption of neutron radiation to which it is exposed and which incorporates isotopes of a neutron absorbing trace element, said trace element having an isotopic composition different from the natural element and having higher neutron absorbability than has the natural isotopic composition thereof, and which is selected from the group consisting of cadmium and lithium.
Claim 4
Dependent Claim
61 words
A document subject to identification by absorption of neutron radiation to which it is exposed and which incorporates isotopes of a neutron absorbing trace element, said trace element having an isotopic composition different from the natural element and having higher neutron absorbability than has the natural isotopic composition thereof, and which is selected from the group consisting of cadmium and lithium.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-17 | 1977-12-17 | 1978-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-17 | 1981-12-17 | 1982-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-17 | 1985-12-17 | 1986-06-18 | $7700.00 | Window Closed / Lapsed |