Patent US4101735A successfully refreshed from Google Patents.
US4101735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-way loudspeaking device for telephone stations
Assignee: U S Holding Co Inc
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Filing: 1977-03-21
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Granted: 1978-07-18
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Expires: 1997-03-21
Abstract
Abstract A handsfree telephone set uses a single transducer as microphone and speaker. A switching arrangement senses and compares the relative strength between received and transmit signals, and switches signal paths accordingly. By sensing the input of the receive path versus the output of the transmit path, the detectors are thus asymmetrically coupled, to provide a break-in capability from one side (the telephone central or calling party) only.
Inventors
- 👤 Edwin Redmond Bridenbaugh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:12
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/08; H04M9/10
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
221 words
An audio signal controlled switching circuit for interfacing between a telecommunications system and a bidirectional transducer, said circuit including a first unidirectional audio path coupled at its input to receive audio signals from said system and coupled at its output to said transducer to transmit signals to said transducer, a second unidirectional audio path coupled at its input to the transducer and at its output to the system , swithing means for enabling transmission of signals through one or the other of said paths on operation thereof, a comparator network having a first and a second input means for comparing signals in said audio paths for operating the switching means responsive to audio signal received from said paths to enable the audio path from which signals of greater amplitude have been received by comparator network and to disable the other audio path, said first input means coupled to said system to continuously receive signals directed to said first audio path, said second input means coupled to the output of said second audio path to receive signals therefrom only with said first audio path disabled by said switching means whereby to provide signals to said switching means to enable said first audio path on the occurrence of signals of greater amplitude from said system than those transmitted from said second audio path.
Claim 2
Dependent Claim
221 words
An audio signal controlled switching circuit for interfacing between a telecommunications system and a bidirectional transducer, said circuit including a first unidirectional audio path coupled at its input to receive audio signals from said system and coupled at its output to said transducer to transmit signals to said transducer, a second unidirectional audio path coupled at its input to the transducer and at its output to the system , swithing means for enabling transmission of signals through one or the other of said paths on operation thereof, a comparator network having a first and a second input means for comparing signals in said audio paths for operating the switching means responsive to audio signal received from said paths to enable the audio path from which signals of greater amplitude have been received by comparator network and to disable the other audio path, said first input means coupled to said system to continuously receive signals directed to said first audio path, said second input means coupled to the output of said second audio path to receive signals therefrom only with said first audio path disabled by said switching means whereby to provide signals to said switching means to enable said first audio path on the occurrence of signals of greater amplitude from said system than those transmitted from said second audio path.
Claim 3
Dependent Claim
33 words
A circuit as claimed in claim 1, in which the output coupling of said second audio path is further coupled to said system and to said first input means through signal attenuating means.
Claim 4
Dependent Claim
61 words
A switching circuit as claimed in claim 1, in which said second input operational amplifier with one input to said amplifier coupled to the output of said second audio path and in which the second input to said amplifier has coupled thereto means for normally biasing said second input to establish a threshold level for the operation of said operational amplifier.
Claim 5
Dependent Claim
36 words
A switching circuit as claimed in claim 1, in which said first and second input means each comprises an operational amplifier for rectifying an audio signal received to produce direct current signals for said comparator network.
Claim 6
Dependent Claim
142 words
A loudspeaking telephone circuit for selectively transmitting audio signals between a telephone system and a bidirectional transducer comprising: first and second audio paths coupling said system and said transducer, switching means operative to enable one of said audio paths and disable the other of said audio paths; first means for detecting audio signals from said telephone system and for operating said switching means to enable said first audio path and inhibit said second audio path when said telephone system audio signals are above a first predetermined level, and second means for detecting audio signals from said telephone system and from said transducer for operating said switching means to enable said second audio path and inhibit said first audio path when said transducer audio signals are above a second predetermined level and said telephone system audio signals are below said first predetermined level.
Claim 7
Dependent Claim
142 words
A loudspeaking telephone circuit for selectively transmitting audio signals between a telephone system and a bidirectional transducer comprising: first and second audio paths coupling said system and said transducer, switching means operative to enable one of said audio paths and disable the other of said audio paths; first means for detecting audio signals from said telephone system and for operating said switching means to enable said first audio path and inhibit said second audio path when said telephone system audio signals are above a first predetermined level, and second means for detecting audio signals from said telephone system and from said transducer for operating said switching means to enable said second audio path and inhibit said first audio path when said transducer audio signals are above a second predetermined level and said telephone system audio signals are below said first predetermined level.
Claim 8
Dependent Claim
34 words
A loudspeaking telephone circuit as claimed in claim 5, in which each said detecting means comprises a rectifying amplifier for feeding direct current signals to said switching means for comparison of amplitude of signals.
Claim 9
Dependent Claim
33 words
A loudspeaking telephone system as claimed in claim 6, in which said switching means comprises an operational amplifier acting as a comparator for controlling individual switching elements for each of said audio paths.
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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) | 1981-07-17 | 1982-01-16 | 1982-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-17 | 1986-01-16 | 1986-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-17 | 1990-01-16 | 1990-07-18 | $7700.00 | Window Closed / Lapsed |