US3755625A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multimicrophone loudspeaking telephone system
Assignee: AT&T Inc
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Filing: 1971-10-12
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Granted: 1973-08-28
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Expires: 1991-10-12
Abstract
Abstract A modified speakerphone conference system with a plurality of microphones employs a comparator in combination with logic circuitry that selects the microphone with the greatest output and connects it to the speakerphone input while simultaneously disconnecting the others. In the absence of other inputs, a microphone that has control retains control despite pauses. Control can be seized, however, by any microphone with an overriding signal. Switching and the transmission of background noise are both minimized.
Inventors
- 👤 D Maston
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:11
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/001; H04M3/00; H04M3/42; H04M3/56; H04M3/568; H04M3/569
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
119 words
In a conference telephone system, in combination, a loudspeaking telephone including an input point, a plurality of microphones, means automatically operative in response to signal outputs from said microphones for selecting that one of said outputs having the greatest magnitude, means for applying the selected one of said outputs to said input point, means for blocking signals from nonselected ones of said microphones from application to said input point, and means responsive to any nonselected one of said outputs that exceeds the selected one of said outputs by an adjustable level for enabling said last named nonselected output to seize control and to be applied to said input point in lieu of an earlier selected one of said outputs.
Claim 2
Dependent Claim
119 words
In a conference telephone system, in combination, a loudspeaking telephone including an input point, a plurality of microphones, means automatically operative in response to signal outputs from said microphones for selecting that one of said outputs having the greatest magnitude, means for applying the selected one of said outputs to said input point, means for blocking signals from nonselected ones of said microphones from application to said input point, and means responsive to any nonselected one of said outputs that exceeds the selected one of said outputs by an adjustable level for enabling said last named nonselected output to seize control and to be applied to said input point in lieu of an earlier selected one of said outputs.
Claim 3
Dependent Claim
37 words
Apparatus in accordance with claim 1 wherein said selecting means comprises a comparator and means including a plurality of combination rectifier-range compressor circuits each connected between one of said microphones and a respective input to said comparator.
Claim 4
Dependent Claim
73 words
Apparatus in accordance with claim 2 wherein said blocking means includes a plurality of flip-flops and a plurality of voltage controlled switches, each of said switches being connected in series relation between the output of a respective one of said microphones and said input point of said loudspeaking telephone, and means for applying a control signal from an output of each of said flip-flops to a corresponding one of said voltage controlled switches.
Claim 5
Dependent Claim
70 words
Apparatus in accordance with claim 3 further including a plurality of latching circuits each connected between the output of a respective one of said microphones and the input of a respective one of said rectifier-range compressor circuits, said latching circuit enabling said selected output to retain control and continue to be applied to said input point until one of said nonselected outputs exceeds said selected output by said adjustable level.
Claim 6
Dependent Claim
73 words
Apparatus in accordance with claim 4 including means for applying a control signal from each of said flip-flops to a respective one of said latching circuits, each of said latching circuits comprising means responsive to a respective one of said last named control signals for inserting loss in the path between a respective one of said microphones and a corresponding one of said rectifier-range compressor circuits whenever said last named microphone is nonselected.
Claim 7
Dependent Claim
35 words
Apparatus in accordance with claim 2 wherein each of said combination rectifier-range compressor circuits comprises an operational amplifier having a nonlinear circuit in its feedback path, said operational amplifier being operated in a noninverting mode.
Claim 8
Dependent Claim
67 words
Apparatus in accordance with claim 3 including a steering network connected between the outputs of said comparator and the inputs of said flip-flops, said steering network comprising logic circuitry responsive to a signal of a preselected level from said comparator for directing said last named signal to one input lead of one of said flip-flops and to the opposite input lead of all others of said flip-flops.
Claim 9
Dependent Claim
97 words
A loudspeaking telephone system comprising, in combination, a plurality of input transducers, a single output point, a respective control channel connected between each of said transducers and said output point, said control channels including means responSive to a signal from one or more of said transducers for applying that one of said signals having the greatest magnitude to said output point and further including means for subsequently applying another one of said signals having a magnitude that exceeds the previously applied signal by an adjustable level to said output point in lieu of said previously applied signal.
Claim 10
Dependent Claim
97 words
A loudspeaking telephone system comprising, in combination, a plurality of input transducers, a single output point, a respective control channel connected between each of said transducers and said output point, said control channels including means responSive to a signal from one or more of said transducers for applying that one of said signals having the greatest magnitude to said output point and further including means for subsequently applying another one of said signals having a magnitude that exceeds the previously applied signal by an adjustable level to said output point in lieu of said previously applied signal.
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) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |