EP0035318A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Improvements in electroacoustic transducers
Assignee: C Tape Developments Ltd
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Filing: 1981-01-15
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Granted: —
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Expires: 2001-01-15
Abstract
Abstract An electroacoustic transducer is provided in the form of a flexible tape formed of an inner flat metal foil 10 surrounded by a metal foil 14 and separated from the latter by an electret 12. The outer metal foil 14 is in turn surrounded by a PVC outer layer 20. This construction provides a flexible electret type of microphone with the additional advantage of immunity from ambient acoustic waves and electrical and magnetic fields.
Inventors
- 👤 Andre Peter John Bendyshe Walton
- 👤 Francis Henry Townsend
- 👤 John Noel Ribet
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 17:57
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/16; G01V1/20; G01V1/201; G01V1/208; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/296; G01F23/2968; G08; G08B; G08B13/00; G08B13/02; G08B13/04; H; H04; H04R; H04R19/00; H04R19/01
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
117 words
A transducer in the form of a flexible tape conformable to a surface to detect acoustic waves propagating along the surface, the transducer comprising two electrodes (10, 14) spaced apart by an electret, characterised in that a first electrode is in the form of a flat metal foil (10) and the second electrode (14) is wrapped around the metal foil constituting the first electrode and is separated therefrom by a dielectric material acting as an electret, in that means (18) are provided for applying a DC voltage during operation across the electret in a sense to enhance the polarisation within the electret and in that the outer metal foil (14) is maintained during operation, at earth potential.
Claim 2
Dependent Claim
117 words
A transducer in the form of a flexible tape conformable to a surface to detect acoustic waves propagating along the surface, the transducer comprising two electrodes (10, 14) spaced apart by an electret, characterised in that a first electrode is in the form of a flat metal foil (10) and the second electrode (14) is wrapped around the metal foil constituting the first electrode and is separated therefrom by a dielectric material acting as an electret, in that means (18) are provided for applying a DC voltage during operation across the electret in a sense to enhance the polarisation within the electret and in that the outer metal foil (14) is maintained during operation, at earth potential.
Claim 3
Dependent Claim
27 words
A transducer as claimed in Claim 1, characterised in that the outer metal foil (14) has on its inner surface a coating (16) of a dielectric resin.
Claim 4
Dependent Claim
24 words
A transducer as claimed in Claim 1 or Claim 2, wherein the outer metal foil (14) is surrounded by an insulating plastics envelope (20).
Claim 5
Independent Claim
48 words
A system for detecting imminent mechanical failure of a structure characterised by a transducer as claimed in any preceding claim adhered to a solid surface of the structure and a circuit responsive to detected acoustic signals lying within a predetermined frequency band for producing an alarm indication. -
Claim 6
Dependent Claim
52 words
A burglar alarm system incorporating means for detecting breakage of a glass panel, characterised in that the means for detecting breakage of the glass panel, comprises an electro- acoutic transducer as claimed in any of claims 1 to 3 connected to a circuit responsive to signals lying within a predetermined frequency range.
Claim 7
Dependent Claim
75 words
A level detecting apparatus for detecting the level of a liquid within a container, characterised by a first electro-acoustic transducer for transmitting an acoustic signal into a wall of the container, a second electro acoustic transducer as claimed in any of claims 1 to 3 for detecting an acoustic signal transmitted through the walls of the container and means for measuring the attenuation of the acoustic signal to provide an indication of the fluid level.
References Cited (Backward Citations)
US3763482A
Cited
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