Patent US3697701A successfully refreshed from Google Patents.
US3697701A
Expired / Lapsed
US
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Improved scannable line circuit for common control telephone system
Assignee: AT&T Inc
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Filing: 1970-12-21
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Granted: 1972-10-10
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Expires: 1990-12-21
Abstract
Abstract A telephone system suitable for use as a private branch exchange with 40 lines or less comprises a switching network that establishes call connections for station line circuits, registers and trunks under common control. Each line circuit comprises amplifier and gate control facilities which cooperate in the control of the switching network. The gate facilities include an address gate and a zener diode controlled gate which initially are scanned for detecting a service request and are rescanned on a callback operation to identify the calling line following a dialing operation.
Inventors
- 👤 William Wallace Greason
- 👤 David William Weiner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:30
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/42; H04Q3/54
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
213 words
A communications switching system comprising: a plurality of line circuits, each of said line circuits capable of exhibiting a plurality of service states; a register connectable with said line circuits; common control means for selectively establishing connections to said line circuits and to said register; scanning means for routinely scanning said line circuits; means associated with said line circuits for stopping said routine scanning pursuant to the initiation of a service requesting state at one of said line circuits; said common control means thereupon establishing a dialing connection from said one of said line circuits to said register, said register thereupon applying a first magnitude potential to said one of said line circuits to maintain said dialing connection from said one of said line circuits to said register, said register replacing said first magnitude potential with a second magnitude potential of the same polarity after the completion of dialing, whereupon said common control means controls said scanning means to resume the scanning of said line circuits; and zener diode means connected to said associated means at said one of said line circuits responsive to the appearance of said second magnitude potential for again stopping said scanning means, said common control means thereupon completing a communications connection to said one of said line circuits.
Claim 2
Dependent Claim
213 words
A communications switching system comprising: a plurality of line circuits, each of said line circuits capable of exhibiting a plurality of service states; a register connectable with said line circuits; common control means for selectively establishing connections to said line circuits and to said register; scanning means for routinely scanning said line circuits; means associated with said line circuits for stopping said routine scanning pursuant to the initiation of a service requesting state at one of said line circuits; said common control means thereupon establishing a dialing connection from said one of said line circuits to said register, said register thereupon applying a first magnitude potential to said one of said line circuits to maintain said dialing connection from said one of said line circuits to said register, said register replacing said first magnitude potential with a second magnitude potential of the same polarity after the completion of dialing, whereupon said common control means controls said scanning means to resume the scanning of said line circuits; and zener diode means connected to said associated means at said one of said line circuits responsive to the appearance of said second magnitude potential for again stopping said scanning means, said common control means thereupon completing a communications connection to said one of said line circuits.
Claim 3
Dependent Claim
49 words
A communications switching system according to claim 1 wherein said zener diode means is poled to remain in a nonconducting state when said first magnitude potential is applIed by said register and is placed in a conducting state only when said second magnitude potential is applied by said register.
Claim 4
Dependent Claim
57 words
A communications switching system according to claim 2 wherein said means associated with said line circuits for stopping said routine scanning comprises a gate for generating a scanning stopping signal, said gate being energizable in response to either a service request signal or a signal generated by said zener diode means when placed in said conducting state.
Claim 5
Dependent Claim
116 words
A line circuit for a common control switching system employing a scanner, said line circuit including a sleeve conductor for receiving a holding potential to maintain switching connections extended to said circuit, comprising: gate means having an output and a plurality of inputs, a first of said inputs being energized when said circuit is in a service requesting state to produce a predetermined scannable signal at said output; and means connecting a second of said plurality of inputs to said sleeve conductor, said connecting means being selectively energizable to produce said predetermined signal at said output, said connecting means including zener diode means for blocking said holding potential from said second of said plurality of inputs.
Claim 6
Dependent Claim
116 words
A line circuit for a common control switching system employing a scanner, said line circuit including a sleeve conductor for receiving a holding potential to maintain switching connections extended to said circuit, comprising: gate means having an output and a plurality of inputs, a first of said inputs being energized when said circuit is in a service requesting state to produce a predetermined scannable signal at said output; and means connecting a second of said plurality of inputs to said sleeve conductor, said connecting means being selectively energizable to produce said predetermined signal at said output, said connecting means including zener diode means for blocking said holding potential from said second of said plurality of inputs.
Claim 7
Dependent Claim
68 words
A line circuit according to claim 4 wherein said gate means includes an enabling gate and an addressable gate, said enabling gate being energizable to enable said addressable gate in response to either said line circuit being in a service requesting state or said connecting means being energized, said addressable gate, when enabled, being energizable by the receipt of signals from said scanner to produce said predetermined signal.
Claim 8
Dependent Claim
109 words
A line circuit for a communication line in a communication system comprising: an address gate for generating an address control signal indicating the identity of the circuit, means for enabling said address gate, said means including means for applying scanning signals to said address gate and an enable gate, first means for enabling said enable gate upon a service request from the communication line, second means independent of said first means for enabling said enable gate upon a callback to the communication line, said second means including a supervisory conductor, and means for preventing other signals on said supervisory conductor not indicating a callback from enabling said enable gate.
Claim 9
Dependent Claim
109 words
A line circuit for a communication line in a communication system comprising: an address gate for generating an address control signal indicating the identity of the circuit, means for enabling said address gate, said means including means for applying scanning signals to said address gate and an enable gate, first means for enabling said enable gate upon a service request from the communication line, second means independent of said first means for enabling said enable gate upon a callback to the communication line, said second means including a supervisory conductor, and means for preventing other signals on said supervisory conductor not indicating a callback from enabling said enable gate.
Claim 10
Dependent Claim
24 words
A line circuit in accordance with claim 6 wherein said preventing means includes a Zener diode connecting said supervisory conductor to said enable gate.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-10 | 1976-04-10 | 1976-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-10 | 1980-04-10 | 1980-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-10 | 1984-04-10 | 1984-10-10 | $7700.00 | Window Closed / Lapsed |