US3865992A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronically controlled ring-trap circuit
Assignee: International Standard Electric Corp
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Filing: 1972-11-15
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Granted: 1975-02-11
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Expires: 1992-11-15
Abstract
Abstract This circuit detects when the handset of a telephone station is lifted and energizes a conventional relay to shut off ringing, thus avoiding use of a special ringing trip relay. The circuit comprises a resistor in series with the line, a filter across the resistor, and a diode-photo-transistor couple connected to the output of the filter. The couple is controlled by the D.C. potential difference across the resistor to control a relay in series with the photo-transistor. As an alternative embodiment, a transistorized switch is inserted between the filter and the diode-phototransistor couple to shunt the filter in order to transmit a greater part of the line current to the diode. These two circuits normally consume no current, which allows them to be permanently connected to the ringing current generator.
Inventors
- 👤 Lucien Robert Bouty
- 👤 Gerard Marcel Lecardonnel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:32
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/02; H04M19/026
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
126 words
A ring-trip circuit comprising a photoemissive detecting circuit associated with a telephone line, said photo-emissive detecting circuit including photoemissive means and photosensitive means, a switching circuit optically coupled via the photo sensitive means to the photoemissve means and controlled by the latter, filter means coupling the photoemissive means to the telephone line to restrict the transmission of alternating current to the photoemissive means, said photoemissive means responding to direct current along the telephone line to emit light and complete the optical couple to the switching circuit, the switching circuit including contacts over which alternating ringing current signals are supplied to the telephone line, and the switching circuit responding to completion of said optical couple to open said contacts and remove alternating ringing current from the line.
Claim 2
Dependent Claim
126 words
A ring-trip circuit comprising a photoemissive detecting circuit associated with a telephone line, said photo-emissive detecting circuit including photoemissive means and photosensitive means, a switching circuit optically coupled via the photo sensitive means to the photoemissve means and controlled by the latter, filter means coupling the photoemissive means to the telephone line to restrict the transmission of alternating current to the photoemissive means, said photoemissive means responding to direct current along the telephone line to emit light and complete the optical couple to the switching circuit, the switching circuit including contacts over which alternating ringing current signals are supplied to the telephone line, and the switching circuit responding to completion of said optical couple to open said contacts and remove alternating ringing current from the line.
Claim 3
Dependent Claim
45 words
A circuit as defined in claim 1, in which the photoemissive detecting circuit includes a photo-emissive diode emitting light under the influence of a current flowing through it; and the switching circuit includes a phototransistor which is conductive when it receives light on its base.
Claim 4
Dependent Claim
171 words
A ring-trip circuit comprising a photo-emissive detecting circuit associated with a telephone line, a switching circuit optically coupled via photo sensitive means to the photoemissive circuit and controlled by the latter, the detecting circuit responding to direct current along the telephone line to emit light and complete the optical couple to the switch circuit, the switching circuit including contacts over which alternating current ringing signals are supplied to the telephone line, the switching circuit responding to completion of said optical couple to open said contacts and remove alternating ringing current from the line, a resistor coupled in series on one wire of the line, means connecting the detecting circuit to the terminals of that resistor in a manner such that the operation of the circuit is dependent only upon the current flowing in the resistor, and a filter connected between the line and the detecting circuit to eliminate the influence of the ringing current and to provide a current to the detecting circuit only when direct current flows along the line.
Claim 5
Dependent Claim
171 words
A ring-trip circuit comprising a photo-emissive detecting circuit associated with a telephone line, a switching circuit optically coupled via photo sensitive means to the photoemissive circuit and controlled by the latter, the detecting circuit responding to direct current along the telephone line to emit light and complete the optical couple to the switch circuit, the switching circuit including contacts over which alternating current ringing signals are supplied to the telephone line, the switching circuit responding to completion of said optical couple to open said contacts and remove alternating ringing current from the line, a resistor coupled in series on one wire of the line, means connecting the detecting circuit to the terminals of that resistor in a manner such that the operation of the circuit is dependent only upon the current flowing in the resistor, and a filter connected between the line and the detecting circuit to eliminate the influence of the ringing current and to provide a current to the detecting circuit only when direct current flows along the line.
Claim 6
Dependent Claim
34 words
A circuit as defined in claim 3, in which a protection circuit is connected between the line and the detecting circuit to protect the detecting circuit against too strong current flowing along the line.
Claim 7
Dependent Claim
34 words
A circuit as defined in claim 4, in which the protection circuit includes two diodes connected, in parallel and in opposition one with respect to the other, to the terminals of the detecting circuit.
Claim 8
Dependent Claim
57 words
A circuit as defined in claim 3, in which an additional switching circuit is coupled between one side of the transmission line and the photoemissive detector to operate when direct current flows along the line and couples the detecting circuit directly with the line, and, thus, short-circuits the filter to transmit alternating current to the detecting circuit.
Claim 9
Dependent Claim
62 words
A circuit as defined in claim 6, in which a diode is connected in series with said additional switching unit to enable the flow of direct current and alternating current in one direction through the detecting circuit, thereby altering the magnitude of the luminous flux from the photoemissive detector in accordance with the sum of the direct current and the alternating current.
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) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |