US3789153A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Call park circuit for an automatic telephone switching system
Assignee: U S Holding Co Inc
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Filing: 1972-06-08
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Granted: 1974-01-29
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Expires: 1992-06-08
Abstract
Abstract In a telephone switching system in which automatic operator access is provided, a further system is provided to assure that incoming calls to an operator are treated on a first-come firstserve basis during periods of heavy traffic in which the operators are busy. This further system is minimized in size, in cost and in complexity according to the present invention through use of circuits which complete a single call when an operator becomes available.
Inventors
- 👤 M Malm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:32
CPC Classifications
H; H04; H04Q; H04Q3/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
121 words
A call park circuit for automatic telephone switching systems, comprising first switch means operable in response to a call signal demanding an operator, means coupled to said first switch means and responsive to operation of said first switch means to generate a first demand voltage, longest waiting detector means coupled to receive said demand voltage, means coupling said longest waiting detector means to second switch means, said longest waiting detector means responding to said demand voltage and to an indicaTion from said second switch means that an operator is available to provide a second demand voltage, and third switch means coupled to the longest waiting detector means responsive to said second demand voltage to institute a connection to an available operator.
Claim 2
Dependent Claim
121 words
A call park circuit for automatic telephone switching systems, comprising first switch means operable in response to a call signal demanding an operator, means coupled to said first switch means and responsive to operation of said first switch means to generate a first demand voltage, longest waiting detector means coupled to receive said demand voltage, means coupling said longest waiting detector means to second switch means, said longest waiting detector means responding to said demand voltage and to an indicaTion from said second switch means that an operator is available to provide a second demand voltage, and third switch means coupled to the longest waiting detector means responsive to said second demand voltage to institute a connection to an available operator.
Claim 3
Dependent Claim
45 words
A call park circuit as claimed in claim 1, in which said first demand voltage is employed as a source of time signals, indicator means are supplied to indicate time lapse, and means are provided coupling said indicator means to receive said first demand voltage.
Claim 4
Dependent Claim
33 words
A call park circuit as claimed in claim 1, in which the means to generate the first voltage includes a linear ramp generator, and the first demand voltage is a linear ramp voltage.
Claim 5
Dependent Claim
87 words
A call park circuit as claimed in claim 1, in which the means to generate a demand voltage includes a linear ramp generator providing a linear ramp voltage, said linear ramp generator including a transistor circuit responsive to ground potential applied over said first switch means to start conducting, a capacitor coupled in a network across said transistor circuit, said network providing a charging voltage to said capacitor, charging it at a linear rate, said charging voltage causing said transistor circuit to produce said linear ramp voltage.
Claim 6
Dependent Claim
109 words
A call park circuit as claimed in Claim 1, in which said means to generate a demand voltage includes a linear ramp generator, said linear ramp generator includes a transistor circuit formed by first and second transistors coupled in emitter follower configuration to the longest waiting detector means, means coupling the collector units of said transistors to said first switch means, means coupling the output emitter of said transistor circuit to a source of potential, and capacitor and resistor means coupling the input base circuit of said transistor circuit across said source of potential and ground circuits to provide a linearly variable input signal to drive said transistor circuit.
Claim 7
Dependent Claim
82 words
A call park circuit as claimed in claim 1, in which the means to generate a demand voltage includes a linear ramp generator providing a linear ramp voltage, said linear ramp generator includes a Darlington circuit responsive to the demand voltage to start conducting, a capacitor coupled in a neework across said Darlington circuit, said network providing a charging voltage to said capacitor, charging it at a linear rate, said charging capacitor causing said Darlington circuit to produce said linear ramp voltage.
Claim 8
Dependent Claim
104 words
A call park circuit as claimed in claim 1, in which said means to generate a demand voltage includes a linear ramp generator, said linear ramp generator includes a Darlington circuit coupled in emitter follower configuration to the longest waiting detector means, means coupling the collector units of said Darlington circuit to said first switch means, means coupling the emitter circuits of said Darlington circuit to a source of potential, and capacitor and resistor means coupling the input base circuit of said Darlington circuit across said source of potential and ground circuits to provide a linearly variable input signal to drive said Darlington circuit.
Claim 9
Dependent Claim
37 words
A call park circuit as claimed in claim 7, in which a zener diode is coupled between the emitter follower circuit and the input base circuit of said Darlington circuit to provide a source of constant voltage.
Claim 10
Dependent Claim
43 words
A call park circuit as claimed in claim 1, in which the longest waiting detector means includes transistor circuits responsive to coincidence in said demand voltage and in a biasing voltage supplied over said second switch means to provide said second demand signal.
Claim 11
Dependent Claim
63 words
A call park circuit as claimed in claim 1, in which the indication from the second switch means that an operator is available is in the form of a bias potential, and the longest waiting detector means incluDes transistor circuits responsive to coincidence in said demand voltage and in the bias potential over said second switch means to provide said second demand signal.
References Cited (Backward Citations)
US3692950A
Cited
US3692948A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |