US3581012A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Unidirectional microphone
Assignee: Sony Corp
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Filing: 1968-07-03
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Granted: 1971-05-25
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Expires: 1988-07-03
Abstract
Abstract A unidirectional microphone in which a second order gradient microphone and a wave-type microphone are combined so as to obtain an improved directional microphone with the low frequency components obtained from the second order gradient microphone and the medium and higher frequency components being obtained from the wave-type microphone so as to obtain a composite output signal which has a uniform and narrow directive pattern and a smooth frequency response characteristic over a wide frequency range.
Inventors
- 👤 Kanesuke Kishi
- 👤 Noboru Tsuchiya
- 👤 Kazuo Shimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:58
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/20; H04R1/32; H04R1/40; H04R1/406
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
178 words
A unidirectional microphone comprising: a directional wave-type microphone; a directional second order gradient microphone mounted adjacent said wave-type microphone and orientated so that both microphones have the same directivity; combining means connected to both microphones and comprising a high pass filter and a low pass filter with the output of the second order gradient microphone connected to the low pass filter and the output of the wave-type microphone connected to the high pass filter; output terminals connected to the low and high pass filters; said second order gradient microphone comprising a pair of microphone elements separated by a distance D1 and biasing means connected to said pair of microphone elements to provide a bias of opposite polarity on said elements; and wherein said wave-type microphone comprises an acoustic pipe with a closed end and spaced acoustic openings formed along its longitudinal axis and one of said pair of microphone elements mounted at one end of said pipe so that in addition to forming a portion of the gradient microphone pickup it also provides pickup for the wave-type microphone.
Claim 2
Dependent Claim
178 words
A unidirectional microphone comprising: a directional wave-type microphone; a directional second order gradient microphone mounted adjacent said wave-type microphone and orientated so that both microphones have the same directivity; combining means connected to both microphones and comprising a high pass filter and a low pass filter with the output of the second order gradient microphone connected to the low pass filter and the output of the wave-type microphone connected to the high pass filter; output terminals connected to the low and high pass filters; said second order gradient microphone comprising a pair of microphone elements separated by a distance D1 and biasing means connected to said pair of microphone elements to provide a bias of opposite polarity on said elements; and wherein said wave-type microphone comprises an acoustic pipe with a closed end and spaced acoustic openings formed along its longitudinal axis and one of said pair of microphone elements mounted at one end of said pipe so that in addition to forming a portion of the gradient microphone pickup it also provides pickup for the wave-type microphone.
Claim 3
Dependent Claim
148 words
A unidirectional microphone comprising: a directional wave-type microphone; a directional second order gradient microphone mounted adjacent said wave-type microphone and orientated so that both microphones have the same directivity; combining means connected to both microphones and comprising a high pass filter and a low pass filter with the output of the second order gradient microphone connected to the low pass filter and the output of the wave-type microphone connected to the high pass filter; output terminals connected to the low and high pass filters; said wave-type microphone comprising an acoustic pipe with a closed end and spaced acoustic openings formed along its longitudinal axis and a microphone element mounted at one end of said pipe; and wherein the length of said pipe is D2 and wherein said second order gradient microphone comprises a pair of microphone elements separated by a distance D1, and D2 is greater than D1.
Claim 4
Dependent Claim
148 words
A unidirectional microphone comprising: a directional wave-type microphone; a directional second order gradient microphone mounted adjacent said wave-type microphone and orientated so that both microphones have the same directivity; combining means connected to both microphones and comprising a high pass filter and a low pass filter with the output of the second order gradient microphone connected to the low pass filter and the output of the wave-type microphone connected to the high pass filter; output terminals connected to the low and high pass filters; said wave-type microphone comprising an acoustic pipe with a closed end and spaced acoustic openings formed along its longitudinal axis and a microphone element mounted at one end of said pipe; and wherein the length of said pipe is D2 and wherein said second order gradient microphone comprises a pair of microphone elements separated by a distance D1, and D2 is greater than D1.
Claim 5
Dependent Claim
48 words
A unidirectional microphone according to claim 2 wherein the wave-type microphone comprises an acoustic pipe having numerous spaced acoustic holes formed along its longitudinal direction and having one end closed, and one of said pair of gradient microphone elements linked to the other end of said acoustic pipe.
Claim 6
Dependent Claim
68 words
A unidirectional microphone according to claim 2 wherein the combining means comprises a low pass filter which receives the output of the second order gradient microphone, a high pass filter which receives the output of the wave-type microphone, and an output transformer having a primary connected to the low pass and high pass filters, and said output transformer having a secondary across which an output signal is produced.
Claim 7
Dependent Claim
77 words
A unidirectional microphone according to claim 2 comprising a first field effect transistor having three electrodes with a first electrode coupled to the output of the second order gradient microphone and the other two electrodes connected in circuit with the low pass filter, a second field effect transistor having three electrodes with a first electrode connected to the output of said wave-type microphone and with its other two electrodes connected in circuit with the high pass filter.
Claim 8
Dependent Claim
146 words
A unidirectional microphone compRising: a second order gradient microphone having a pair of gradient microphone elements spaced apart so that they have approximately equal directivity and producing a composite output signal; a wave-type microphone mounted so that it has a directivity which substantially coincides with that of said second order gradient microphone; combining means receiving the outputs of said microphones to combine the low frequency components from said second order gradient microphone with the medium and high frequency components of the wave-type microphone; said wave-type microphone comprising an acoustic pipe with a closed end and spaced acoustic openings formed along its longitudinal axis and a microphone element mounted at one end of said pipe wherein the length of said pipe is D2, and wherein said second order gradient microphone comprises a pair of microphone elements separated by a distance D1, and D2 is greater than D1.
Claim 9
Dependent Claim
146 words
A unidirectional microphone compRising: a second order gradient microphone having a pair of gradient microphone elements spaced apart so that they have approximately equal directivity and producing a composite output signal; a wave-type microphone mounted so that it has a directivity which substantially coincides with that of said second order gradient microphone; combining means receiving the outputs of said microphones to combine the low frequency components from said second order gradient microphone with the medium and high frequency components of the wave-type microphone; said wave-type microphone comprising an acoustic pipe with a closed end and spaced acoustic openings formed along its longitudinal axis and a microphone element mounted at one end of said pipe wherein the length of said pipe is D2, and wherein said second order gradient microphone comprises a pair of microphone elements separated by a distance D1, and D2 is greater than D1.
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) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |