US3573399A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Directional microphone
Assignee: AT&T Inc
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Filing: 1968-08-14
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Granted: 1971-04-06
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Expires: 1988-08-14
Abstract
Abstract A directional microphone with toroidal or truncated toroidal sensitivity characteristics is constructed from a plurality of concentric transducer elements, the outputs of which are combined in accordance with a predetermined formula.
Inventors
- 👤 Manfred R Schroeder
- 👤 Gerhard M Sessler
- 👤 James E West
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:19
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/20; H04R1/32; H04R1/40; H04R1/406
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
37 words
A directional microphone of order 2n comprising, an inner electroacoustic transducer element and n concentric outer electroacoustic transducer elements, each of said transducer elements producing individual electrical signals, and means for selectively combining said individual electrical signals.
Claim 2
Dependent Claim
37 words
A directional microphone of order 2n comprising, an inner electroacoustic transducer element and n concentric outer electroacoustic transducer elements, each of said transducer elements producing individual electrical signals, and means for selectively combining said individual electrical signals.
Claim 3
Dependent Claim
30 words
A directional microphone as defined in claim 1 wherein said individual electrical signals from adjacent ones of said inner and said outer transducer elements are combined with opposite signal polarities.
Claim 4
Dependent Claim
76 words
A directional microphone as defined in claim 1 wherein said means for combining said individual electrical signals comprises for adjusting the amplitudes of said individual electrical signals so that the relative weight of the signal produced by said inner transducer element is proportional to and so that the relative weight of the signal produced by each annular outer element r 1 through r n is proportional to and means for summing said weighted individual electrical signals.
Claim 5
Dependent Claim
34 words
A second order directional transducer comprising, an inner electroacoustic transducer element, an outer electroacoustic transducer element approximately concentric with said inner element, and circuit means for differentially interconnecting said inner and outer transducer elements.
Claim 6
Dependent Claim
34 words
A second order directional transducer comprising, an inner electroacoustic transducer element, an outer electroacoustic transducer element approximately concentric with said inner element, and circuit means for differentially interconnecting said inner and outer transducer elements.
Claim 7
Dependent Claim
34 words
A directional transducer as defined claim 4, said transducer further including scattering means located intermediate said first and second transducer elements for preventing standing waves from forming between said first and second transducer elements.
Claim 8
Dependent Claim
31 words
A directional transducer as defined in claim 4 wherein said inner and outer transducer elements are circular, said outer element having a radius greater than the radius of said inner element.
Claim 9
Dependent Claim
22 words
A directional transducer as defined in claim 6 wherein said first and second circular transducer elements comprise sections of two concentric cylinders.
Claim 10
Dependent Claim
22 words
A directional transducer as defined in claim 6 wherein said first and second annular transducer elements lie horizontally in a single plane.
Claim 11
Dependent Claim
62 words
A directional foil electret microphone having a layer of foil-dielectric material maintained in close proximity to a perforated metallic baCkplate which encloses an acoustic cavity, said microphone being characterized in that said metallic backplate is divided into a central region and at least one electrically insulated concentric annular region, said regions being interconnected so as to generate a truncated toroidal sensitivity pattern.
Claim 12
Dependent Claim
62 words
A directional foil electret microphone having a layer of foil-dielectric material maintained in close proximity to a perforated metallic baCkplate which encloses an acoustic cavity, said microphone being characterized in that said metallic backplate is divided into a central region and at least one electrically insulated concentric annular region, said regions being interconnected so as to generate a truncated toroidal sensitivity pattern.
Claim 13
Dependent Claim
76 words
A directional transducer comprising, an inner annular foil electret transducer element for converting acoustic signals into electrical signals, an outer annular foil electret transducer element for converting acoustic signals into electrical signals, an annular scattering element of approximately triangular cross section intermediate said inner transducer element and said outer transducer element, subtractive circuit means, and electrical interconnecting means for conducting signals from said inner annular transducer and said outer annular transducer to said subtractive circuit means.
Claim 14
Dependent Claim
76 words
A directional transducer comprising, an inner annular foil electret transducer element for converting acoustic signals into electrical signals, an outer annular foil electret transducer element for converting acoustic signals into electrical signals, an annular scattering element of approximately triangular cross section intermediate said inner transducer element and said outer transducer element, subtractive circuit means, and electrical interconnecting means for conducting signals from said inner annular transducer and said outer annular transducer to said subtractive circuit means.
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) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |