US3889058A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone systems with reduced acoustic feedback
Assignee: A R D ANSTALT
•
Filing: 1972-12-18
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Granted: 1975-06-10
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Expires: 1992-12-18
Abstract
Abstract Feedback in an electro-acoustic transducer unit for connection into a two-way communication system is reduced or eliminated by acoustic means dependent on relative positioning of loudspeaker and one or more microphones, or electrically, by cancellation of signals due to unwanted sound components derived from a pair of microphones. The operation of the microphone and loudspeaker can be alternated at an ultrasonic frequency or a single transducer can be used as microphone and loudspeaker alternately at such a frequency. A transducer having a pair of speech coils in pushpull formation is described, as well as a laminated structure for use in the housing of the apparatus.
Inventors
- 👤 Saad Zaghoul Mohamed Gabr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:11
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/001; H04M1/00; H04M1/02; H04M1/20; H04M1/56
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
181 words
In combination, housing means, a single loudspeaker having a diaphragm having an axis of movement and an electrical input, microphone means having diaphragm means with exposed opposite sides and an electrical output, means mounting said single loudspeaker and said microphone means in close proximity in said housing means so that sound waves radiated by the loudspeaker diaphragm in response to energization of the loudspeaker travel in a direction parallel to the sides of the microphone diaphragm means directly and by a single sound path to the microphone means, the microphone diaphragm means being disposed substantially in a plane lying along the axis of movement of the loudspeaker diaphragm when the loudspeaker diaphragm moves in response to an electrical input to the loudspeaker, said opposite sides of said microphone diaphragm means being equidistant from said loudspeaker diaphragm, whereby the sound waves radiated by the loudspeaker diaphragm fall directly and substantially equally on said opposite sides of the microphone diaphragm means, so that the electrical output of the microphone means due to the sound waves from the single loudspeaker diaphragm is substantially zero.
Claim 2
Dependent Claim
181 words
In combination, housing means, a single loudspeaker having a diaphragm having an axis of movement and an electrical input, microphone means having diaphragm means with exposed opposite sides and an electrical output, means mounting said single loudspeaker and said microphone means in close proximity in said housing means so that sound waves radiated by the loudspeaker diaphragm in response to energization of the loudspeaker travel in a direction parallel to the sides of the microphone diaphragm means directly and by a single sound path to the microphone means, the microphone diaphragm means being disposed substantially in a plane lying along the axis of movement of the loudspeaker diaphragm when the loudspeaker diaphragm moves in response to an electrical input to the loudspeaker, said opposite sides of said microphone diaphragm means being equidistant from said loudspeaker diaphragm, whereby the sound waves radiated by the loudspeaker diaphragm fall directly and substantially equally on said opposite sides of the microphone diaphragm means, so that the electrical output of the microphone means due to the sound waves from the single loudspeaker diaphragm is substantially zero.
Claim 3
Dependent Claim
25 words
The combination claimed in claim 1, in which said microphone means comprises a pair of microphones back to back and having oppositely outwardly facing diaphragms.
Claim 4
Dependent Claim
11 words
The combination claimed in claim 2, said microphone diaphragms being coaxial.
Claim 5
Dependent Claim
19 words
The combination claimed in claim 1, said microphone means lying on said axis of movement of said loudspeaker diaphragm.
Claim 6
Dependent Claim
62 words
The combination claimed in claim 1 including a second microphone having a diaphragm and means mounting said second microphone in said housing means in close proximity to said loudspeaker on the side of the loudspeaker diaphragm remote from said first-mentioned microphone with the diaphragm of said second microphone disposed in a plane lying along said axis of movement of said loudspeaker diaphragm.
Claim 7
Dependent Claim
25 words
The combination claimed in claim 5 having circuit means connecting said first-mentioned and said second microphone in reverse phase to provide said common electrical output.
Claim 8
Dependent Claim
16 words
The combination claimed in claim 6 in which said circuit means includes a phase adjustment means.
Claim 9
Dependent Claim
24 words
The combination claimed in claim 1 in which said housing means includes at least one wall comprising laminations of hard and relatively soft material.
Claim 10
Dependent Claim
30 words
The combination claimed in claim 1 including electric circuit means interconnecting said microphone and said loudspeaker and adapted to operate said microphone and said loudspeaker alternately at an ultrasonic frequency.
Claim 11
Dependent Claim
53 words
The combination claimed in claim 1 including a second microphone, means mounting said second microphone in said housing means in close proximity to said loudspeaker, circuit means connecting together said first-mentioned microphone and said second microphone and providing therefor a common electrical output, and a phase adjustment means included in said circuit means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |