US3949178A
Expired / Lapsed
US
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Electret device having charge maintained by radioactivity
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1974-10-15
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Granted: 1976-04-06
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Expires: 1994-10-15
Abstract
Abstract An electret device has a dielectric layer containing electret charges and a radioactive layer on one of the surfaces of the dielectric layer.
Inventors
- 👤 Sten Hellstrom
- 👤 Rolf Bertil Goran Jonsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:28
CPC Classifications
H; H04; H04R; H04R19/00; H04R19/01
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
50 words
Electret device, comprising a dielectric layer containing electret charges and means for maintaining the electret charges stored therein comprising a radioactive layer of essentially the beta radiation type located opposite one of the surfaces of the dielectric layer, said radioactive layer having a radioactivity of between 0.01 and 100 μCi.
Claim 2
Dependent Claim
50 words
Electret device, comprising a dielectric layer containing electret charges and means for maintaining the electret charges stored therein comprising a radioactive layer of essentially the beta radiation type located opposite one of the surfaces of the dielectric layer, said radioactive layer having a radioactivity of between 0.01 and 100 μCi.
Claim 3
Dependent Claim
23 words
Electret device according to claim 1, wherein the radioactive layer has an energy spectrum with a maximum being between 5 and 200 keV.
Claim 4
Dependent Claim
12 words
Electret device according to claim 2, wherein the radioactive layer contains tritium.
Claim 5
Dependent Claim
19 words
Electret device according to claim 1, wherein the radioactive layer is separated from the surface of the dielectric layer.
Claim 6
Dependent Claim
18 words
Electret device according to claim 1, wherein the radioactive layer abuts to the surface of the dielectric layer.
Claim 7
Dependent Claim
19 words
Electret device according to claim 1, wherein the radioactive layer is located under the surface of the dielectric layer.
Claim 8
Dependent Claim
69 words
An electret microphone comprising a first electrode having a surface with a layer of dielectric material containing electret charges and means for maintaining the electret charges stored therein comprising a second electrode disposed opposite said first electrode, said second electrode having a surface with a layer of radioactive material and facing the surface of said first electrode with the layer of dielectric material, one of said electrodes being movable.
Claim 9
Dependent Claim
69 words
An electret microphone comprising a first electrode having a surface with a layer of dielectric material containing electret charges and means for maintaining the electret charges stored therein comprising a second electrode disposed opposite said first electrode, said second electrode having a surface with a layer of radioactive material and facing the surface of said first electrode with the layer of dielectric material, one of said electrodes being movable.
Claim 10
Dependent Claim
11 words
Electret microphone of claim 7 wherein said first electrode is movable.
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) | 1979-04-06 | 1979-10-06 | 1980-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-06 | 1983-10-06 | 1984-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-06 | 1987-10-06 | 1988-04-06 | $7700.00 | Window Closed / Lapsed |