US3851183A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrets, to methods and devices for manufacturing them and to assemblies comprising electrets
Assignee: Bpifrance Financement SA
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Filing: 1972-06-29
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Granted: 1974-11-26
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Expires: 1992-06-29
Abstract
Abstract The invention relates to electrets, i.e. dielectric foil on the surfaces of which charges are stored. In an electret according to the invention, the charged surface of the foil is in permanent contact with a fluid having a high dielectric strength (e.g. CCl4, a rarified gas or liquid nitrogen) maintained against the surface by a peripherally welded second dielectric foil. Applications: biasing of a wide variety of electric circuits, more particularly ultrasonic transducers.
Inventors
- 👤 J Lewiner
- 👤 D Legros
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:55
CPC Classifications
H; H04; H04R; H04R19/00; H04R19/01; H01; H01G; H01G7/00; H01G7/02; H01G7/021; H01G7/023
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
71 words
A foil electret, comprising an electrically-charged dielectric foil having a charged surface, a fluid medium of high dielectric strength permanently in intimate contact with said charged surface, and means for maintaining said fluid medium in intimate contact with said charged surface comprising a further member which is imperious to said fluid medium and which sealed in fluid tight relationship to said foil along a continuous line which surrounds said charged surface.
Claim 2
Dependent Claim
71 words
A foil electret, comprising an electrically-charged dielectric foil having a charged surface, a fluid medium of high dielectric strength permanently in intimate contact with said charged surface, and means for maintaining said fluid medium in intimate contact with said charged surface comprising a further member which is imperious to said fluid medium and which sealed in fluid tight relationship to said foil along a continuous line which surrounds said charged surface.
Claim 3
Dependent Claim
30 words
An electret according to claim 1, wherein the fluid medium of high dielectric strength is a rarefied gas selected from the group consisting of carbon tetrachloride, sulphur hexafluoride and freon.
Claim 4
Dependent Claim
18 words
An electret according to claim 1, wherein the fluid medium of high dielectric strength is a rarefied gas.
Claim 5
Dependent Claim
18 words
An electret according to claim 1, wherein the fluid medium of high dielectric strength is a cryogenic liquid.
Claim 6
Dependent Claim
48 words
An electret according to claim 1, wherein said further member comprises a second dielectric foil sealed to the first foil, each dielectric foil being between 5 and 100 microns thick and each being made of a substance of high dielectric strength, adapted to preserve electric charges stored therein.
Claim 7
Dependent Claim
46 words
An electret according to claim 5, wherein the first dielectric foil is charged on both surfaces, both of which are permanently kept in intimate contact with a fluid medium of high dielectric strength enclosed between the aforementioned foil and another dielectric foil sealed to the first.
Claim 8
Dependent Claim
29 words
An electret according to claim 5, wherein the dielectric foils sealed to one another are circularly welded along the periphery of the charged surface which is to be stored.
Claim 9
Dependent Claim
14 words
An electret according to claim 1, wherein the dielectric foil is made of polypropylene.
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) | 1977-11-25 | 1978-05-27 | 1978-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-25 | 1982-05-27 | 1982-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-25 | 1986-05-27 | 1986-11-26 | $7700.00 | Window Closed / Lapsed |