US3582656A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Time base combining radioactive source and solid-state detector
Assignee: Bulova Watch Co Inc
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Filing: 1968-03-21
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Granted: 1971-06-01
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Expires: 1988-03-21
Abstract
Abstract A radioactive timekeeping standard constituted by a radioactive source of alpha particles combined with a solid-state radiation detector, the source being in the form of a backing having a planar array of discrete islands of a radioactive isotope, the alpha particles emitted therefrom passing through an apertured mask and impinging on the sensitive surface of a solid-state radiation detector, the geometry of the mask apertures, which are in a matching array, being such as to restrict emanations impinging on the detector surface to substantially normal angles of incidence and in addition preventing particles emanating from any one island from impinging on a neighboring portion of the detector surface associated with another island.
Inventors
- 👤 Dale R Koehler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:13
CPC Classifications
G; G04; G04C; G04C10/00; G04C10/02; G04F; G04F5/00; G04F5/16
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
22 words
A standard as set forth in claim 1, wherein said array of islands is deposited on a backing having protective shielding properties.
Claim 2
Dependent Claim
27 words
A standard as set forth in claim 1, wherein said islands are formed of a thin film of radioactive material to prevent a spread of energy distribution.
Claim 3
Dependent Claim
43 words
A standard as set forth in claim 1, wherein each aperture in said mask is composed of a first zone adjacent its associated island having a relatively large cross section and a second zone adjacent the detector surface having a constricted cross section.
Claim 4
Dependent Claim
25 words
A standard as set forth in claim 4, wherein said second zone of each aperture is flared outwardly in the direction of the detector surface.
Claim 5
Dependent Claim
27 words
A standard as set forth in claim 1, wherein said radioisotope is selected from a class consisting of uranium 238, uranium 235, neptunium 237 and plutonium 239.
Claim 6
Dependent Claim
36 words
A standard as set forth in claim 2, wherein said backing is a metal disc and said mask is composed of at least one circular plate of the diameter, said detector also having the same configuration.
Claim 7
Dependent Claim
33 words
A standard as set forth in claim 7, wherein said mask is composed of two circular plates, one having apertures defining the first zone and the second having apertures defining the second zone.
Claim 8
Dependent Claim
35 words
A standard as set forth in claim 1, wherein said detector is formed by an array of individual cells, each disposed to intercept radiation from a respective island, the cells being connected unidirectionally in parallel.
Claim 9
Dependent Claim
21 words
A standard as set forth in claim 9, wherein said cells are connected in parallel through diodes and are reverse biased.
Claim 10
Dependent Claim
149 words
A radioactive timekeeping standard comprising: a. a planar array of discrete islands of a radioactive isotope emitting alpHa particles, said isotope having a prolonged half-life. b. a solid-state radiation detector having a sensitive surface in parallel relationship to said planar array, and c. a mask interposed between said array and said surface, having a matching array of circular apertures whose geometry is such as to restrict the emanations impinging on the detector surface to nearly normal angles of incidence and furthermore preventing particles emanating from any one island from impinging on a neighboring portion of the detector surface associated with another island, wherein the diameter of the circle circumscribing such islands is not greater than twice the distance between the surface of the islands and the plane of the detector and furthermore that the diameter of each of said apertures is not less than the diameter of said circle.
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) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |