Patent US3908093A successfully refreshed from Google Patents.
US3908093A
Expired / Lapsed
US
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Intercom system with an improved mechanism for preventing the interruption of conversations
Assignee: Webster Electric Co Inc
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Filing: 1973-10-18
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Granted: 1975-09-23
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Expires: 1993-10-18
Abstract
Abstract Each station in a multi-station, hands-free intercom system is equipped with D.C.-biased audio signal inputs and outputs. D. C. current sensors are connected in series with the inputs and outputs. Switches enable the output of any station to be selectively connected to the input of any other station. The current sensors disable a calling station from transmitting to a called station whenever the call would interrupt a third-party conversation that is in progress at the calling station. The current sensors do not disable the calling station, however, if the called station is switched for communication with the calling station. In this manner, the privacy of conversations is assured. The current sensors may also be used to control the illumination of a ''''BUSY'''' lamp or the like at the calling station.
Inventors
- 👤 Wayne Riley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:57
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/001
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
355 words
An intercom system including a plurality of stations each having a voice signal input channel and a separate voice signal output channel and each including channel switching means for connecting the voice signal output channel of the station to the voice signal input channel of another station at times when it is desired to establish voice communication betWeen the two stations, wherein the improvement comprises: a first node at a first potential and a second node at a second, different potential within each station; at least one first current-conductive path connecting said first node to the voice signal output channel of each station; at least one second current-conductive path connecting said second node to the voice signal input channel of each station; a first current flow sensor connected in series with said first current-conductive path and having a signal output at which a signal appears in response to any flow of current over said first current-conductive path between said first node and said voice signal output channel; a second current flow sensor connected in series with said second current-conductive path and having a signal output at which a signal appears in response to any flow of current over said second current-conductive path between said second node and said voice signal input channel; means associated with the channel switching means for breaking said second conductive path at times when the switching means is not connecting a station''s output channel to the input channel of another station so that a flow of current over said second conductive path can only occur when the station is busy communicating with some other station; and means responsive to a signal output from the first current flow sensor and the absence of a signal output from the second current flow sensor for preventing the station from supplying a voice output signal to its voice signal channel output, thereby preventing a first station from transmitting a voice signal to a second station that is busy but permitting the first station to transmit when the apparently-busy second station is switched for communication back with a first station and is thus not truly busy.
Claim 2
Dependent Claim
355 words
An intercom system including a plurality of stations each having a voice signal input channel and a separate voice signal output channel and each including channel switching means for connecting the voice signal output channel of the station to the voice signal input channel of another station at times when it is desired to establish voice communication betWeen the two stations, wherein the improvement comprises: a first node at a first potential and a second node at a second, different potential within each station; at least one first current-conductive path connecting said first node to the voice signal output channel of each station; at least one second current-conductive path connecting said second node to the voice signal input channel of each station; a first current flow sensor connected in series with said first current-conductive path and having a signal output at which a signal appears in response to any flow of current over said first current-conductive path between said first node and said voice signal output channel; a second current flow sensor connected in series with said second current-conductive path and having a signal output at which a signal appears in response to any flow of current over said second current-conductive path between said second node and said voice signal input channel; means associated with the channel switching means for breaking said second conductive path at times when the switching means is not connecting a station''s output channel to the input channel of another station so that a flow of current over said second conductive path can only occur when the station is busy communicating with some other station; and means responsive to a signal output from the first current flow sensor and the absence of a signal output from the second current flow sensor for preventing the station from supplying a voice output signal to its voice signal channel output, thereby preventing a first station from transmitting a voice signal to a second station that is busy but permitting the first station to transmit when the apparently-busy second station is switched for communication back with a first station and is thus not truly busy.
Claim 3
Dependent Claim
31 words
A system in accordance with claim 1 wherein each station further includes means for giving off a BUSY indication in response to the signal output from the first current flow sensor.
Claim 4
Dependent Claim
57 words
A system in accordance with claim 1 wherein said voice signal input and output channels comprise pairs of conductors and wherein each station includes four current-conductive paths, one path connecting said first node to each of the voice signal output channel conductors and one path connecting said second node to each of the voice signal input conductors.
Claim 5
Dependent Claim
58 words
A system in accordance with claim 1 wherein the current flow sensors in each station comprise a pair of bipolar transistors each having its emitter and base terminals connected in series with one of said conductive paths, and means for biasing said transistors so that the current flow sensor signal output appears at the collector of each transistor.
Claim 6
Dependent Claim
227 words
An intercom system including a plurality of stations each having a voice signal input and a voice signal output and each including switching means for establishing a connection between the station voice signal output and the voice signal input to any of several stations, said interconnection being capable of carrying a D. C. current in addition to a voice signal, wherein the improvement to each station comprises: a first node at a first potential and a second node at a second, different potential within each station; first means for establishing a current-conductive connection between the station''s voice signal output and the first node; second means for establishing a current-conductive connection between the station''s voice signal input and the second node at times when the station is in use; first current sensing means for generating a busy indication signal within a station in response to a net D. C. current flow between the voice signal output of the station and the first node; and second current sensing means for defeating the generation of said busy indication signal within a station in response to a net D. C. current flow between the voice signal input of the station and the second node, which curreNt flow may indicate that a called station is not busy communicating with a third party station but is attempting to communicate with the calling station.
Claim 7
Dependent Claim
227 words
An intercom system including a plurality of stations each having a voice signal input and a voice signal output and each including switching means for establishing a connection between the station voice signal output and the voice signal input to any of several stations, said interconnection being capable of carrying a D. C. current in addition to a voice signal, wherein the improvement to each station comprises: a first node at a first potential and a second node at a second, different potential within each station; first means for establishing a current-conductive connection between the station''s voice signal output and the first node; second means for establishing a current-conductive connection between the station''s voice signal input and the second node at times when the station is in use; first current sensing means for generating a busy indication signal within a station in response to a net D. C. current flow between the voice signal output of the station and the first node; and second current sensing means for defeating the generation of said busy indication signal within a station in response to a net D. C. current flow between the voice signal input of the station and the second node, which curreNt flow may indicate that a called station is not busy communicating with a third party station but is attempting to communicate with the calling station.
Claim 8
Dependent Claim
26 words
A system in accordance with claim 5 wherein each station includes means for preventing transmission from a station output in response to the busy indication signal.
Claim 9
Dependent Claim
40 words
A system in accordance with claim 5 wherein said first means comprises at least one resistive element and wherein said second means comprises a series circuit which circuit includes at least one resistive element and at least one manually-actuatable switch.
Claim 10
Dependent Claim
40 words
A system in accordance with claim 7 wherein said switch is mechanically coupled to the switching means by mechanical coupling means for closing said switch whenever said switching means connects the station output to the input of some other station.
Claim 11
Dependent Claim
227 words
A multi-station intercom system comprising: a plurality of stations; a selection means associated with each station for establishing a voice signal communications channel between the station and another station under the control of a human operator which channel is also suitable for conveying non-voice signals; means within each station for supplying a first signal such as a D. C. supply-potential signal to a channel established by the station''s selection means to signal an attempt to communicate with the station at the other end of the channel; means within each station, placed into operation when the station is in use, for supplying a second signal such as a ground-potential signal to channels established by other stations and extending to the station, said second signal informing all such other stations that the station is busy; means within each station responsive to the receipt of a second busy signal for normally preventing the station from transmitting voice signals over a channel which the station has established to another station that is busy; and means within each station responsive to the receipt of a first signal for permitting the station to transmit voice signals in spite of the fact that the station may be receiving a second signal to thereby permit the station to communicate with another station that appears to be busy but that is actually adjusted for return communication.
Claim 12
Dependent Claim
227 words
A multi-station intercom system comprising: a plurality of stations; a selection means associated with each station for establishing a voice signal communications channel between the station and another station under the control of a human operator which channel is also suitable for conveying non-voice signals; means within each station for supplying a first signal such as a D. C. supply-potential signal to a channel established by the station''s selection means to signal an attempt to communicate with the station at the other end of the channel; means within each station, placed into operation when the station is in use, for supplying a second signal such as a ground-potential signal to channels established by other stations and extending to the station, said second signal informing all such other stations that the station is busy; means within each station responsive to the receipt of a second busy signal for normally preventing the station from transmitting voice signals over a channel which the station has established to another station that is busy; and means within each station responsive to the receipt of a first signal for permitting the station to transmit voice signals in spite of the fact that the station may be receiving a second signal to thereby permit the station to communicate with another station that appears to be busy but that is actually adjusted for return communication.
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) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |