US 5,402,484 A · Telephone circuit assembly

Abstract

A circuit assembly which includes an interface circuit between a subscriber line and exchange devices of the kind with two amplifiers connected in a bridge configuration between the battery terminals and having a means of detecting the output currents; a supply circuit which includes the exchange battery and a ring generator; a switch-over means for putting the line through the interface circuit or the supply circuit; two bridge resistors which are in series with the line when the latter is connected to the supply circuit and of which one is connected permanently between one of the line terminals and the output of one of the amplifiers, which output is substantially at the potential of one of the battery poles; an additional resistor, having a much higher resistive value than that of the bridge resistors and being connected between the other of the line terminals and the output of the other of the amplifiers; and a processing means within the interface circuit, which includes said detecting means and is effective to isolate the useful signal from the line current, recognize a possible hook-off state, and send a corresponding signal to the exchange devices.

Drawings

Drawings are temporarily unavailable. Open the PDF at USPTO

Drawings

Claims25

Dependent claims

A telephone circuit assembly with a circuit for recognizing a hook-off condition during a ring step, comprising

an interface circuit connected between first and second exchange control devices and a telephone subscriber line having terminals;
a supply circuit including a DC voltage source having two terminals and a ring AC generator in series with each other;
a switch-over means effective, under control by the exchange control devices, to alternatively connect the telephone subscriber line to the interface circuit or to the supply circuit;
two resistive members having substantially the same resistive value and being each connected serially between one of the telephone subscriber line terminals and one of the DC voltage source terminals, when the telephone subscriber line is connected to the supply circuit by the switch-over means;
and
a processing circuit means responsive to current on the telephone subscriber line and effective to isolate a useful signal component from said current, recognize any DC component indicative of the hook-off condition in the useful signal component during the ring step, and send upon recognition a signal to the exchange control devices;
the interface circuit comprising a pair of amplifiers connected in a bridge configuration between the terminals of the DC voltage source and having respective outputs connected each to a terminal of the telephone subscriber line upon the switch-over means connecting the telephone subscriber line to the interface circuit, and a current detecting means associated with said amplifiers to detect output current from the amplifiers and produce a current proportional to the useful signal component of the current on the telephone subscriber line;
the processing circuit means being incorporated into the interface circuit, Such that it includes the current detecting means associated with the amplifiers, and is effective to perform a half-sum of the output currents from the amplifiers as detected by the current detecting means;
and
one of the resistive means being connected permanently between the first telephone line terminal and the output of a first one of the interface circuit amplifiers, thereby said connection to the respective terminal of the DC voltage source occurring through said first amplifier.

7 more elements

A telephone circuit assembly with a circuit for recognizing a hook-off condition during a ring step, comprising

an interface circuit connected between exchange control devices and a telephone subscriber line having terminals;
a supply circuit including a DC voltage source having two terminals and a ring AC generator in series with each other, said ring generator comprising two identical push-pull sources;
a switch-over means effective, under control by the exchange control devices, to alternatively connect the telephone subscriber line to the interface circuit or to the supply circuit;
two resistive means having substantially the same resistive value and being each connected serially between one of the telephone subscriber line terminals and one of the DC voltage source terminals, when the telephone subscriber line is connected to the supply circuit by the switch-over means;
and
a processing circuit means responsive to current on the telephone subscriber line and effective to isolate a useful signal component from said current, recognize any DC component indicative of the hook-off condition in the useful signal component during the ring step, and send upon recognition a signal to the exchange control devices;
the interface circuit comprising a pair of amplifiers connected in a bridge configuration between the terminals of the DC voltage source and having respective outputs connected each to a terminal of the telephone subscriber line upon the switch-over means connecting the telephone subscriber line to the interface circuit, and a current detecting means associated with said amplifiers to detect output current from the amplifiers and produce a current proportional to the useful signal component of the current on the telephone subscriber line;
the processing circuit means being incorporated into the interface circuit, such that it includes the current detecting means associated with the amplifiers;
and
two additional resistive means, substantially identical to each other, having much higher resistive values than that of said two resistive means and being individually connected between one of the telephone subscriber line terminals and the output terminal of one of the interface circuit amplifiers.

7 more elements

A telephone circuit assembly with a circuit for recognizing a hook-off condition during a ring step, comprising:

a supply circuit including a DC voltage source;
an interface circuit connected to a telephone subscriber line having first and second terminals;
a switch-over means effective to alternatively connect the telephone subscriber line to the interface circuit or to the supply circuit;
first and second resistive members having substantially the same resistive value, the first resistance member connected serially between the first telephone subscriber line terminal and the DC voltage source and the second resistance member connected serially between the second telephone subscriber line terminal and the interface circuit, when the telephone subscriber line is connected to the supply circuit by the switch-over means;
and
a processing circuit responsive to current on the telephone subscriber line and effective to isolate a useful signal component from said current, produce a current proportional to the useful signal component, and recognize a DC component indicative of the hook-off condition in the current during the ring step and output a signal indicative of recognition.

3 more elements

Dependencies are inferred from the claim text.

Description2,754 words

Summary684 words

#This invention relates to telephone circuits, and more particularly, to an electronic subscriber link circuit assembly, i.e., one having an electronic interface between the telephone subscriber line and the telephone exchange, with a circuit for detecting the hook-off condition during the ring step.

#As is known, a telephone subscriber set, comprising essentially of a speech circuit and a bell connected in parallel to each other, is connected to a telephone exchange by means of a two-wire line. Connected in series to the speech circuit, which would be only closed on hooking off, and serially to the bell, is a capacitor operative to DC uncouple the bell from the line.

#A telephone subscriber line is supplied a direct voltage from a source, having an alternate voltage source connected serially thereto, which forms the ring signal generator, when the exchange devices control special line connection contacts to close and issue said ring signals to the subscriber.

Brief description of the drawings5 figures

#FIG. 1 illustrates diagramatically the above-mentioned conventional circuit assembly;

#FIG. 2 illustrates diagramatically a circuit assembly according to the invention;

#FIG. 3 is a diagram showing a circuit for recognizing hook-offs during the ring step which utilizes the principles of this invention;

Detailed description1,994 words

#The invention will be better understood from the following detailed description of an embodiment thereof, given by way of example and not of limitation with reference to the accompanying drawings.

#Shown in FIG. 1 is a telephone subscriber set U connected, via a line L, to a circuit assembly 1 of a telephone exchange. The assembly 1 comprises an interface circuit 3 between the telephone subscriber and the exchange control devices, basically consisting of two integrated circuits in the application shown in the aforementioned publication, and having two terminals 3A and 3B for connection to a line L, a terminal 3C for connection to the exchange control devices (not shown), and two more terminals 3D, 3F. Understandably, the interface circuit 3 would actually include a multiplicity of additional terminals, not shown in the diagram of FIG. 1 because immaterial to the function to be illustrated.

#In addition, a supply circuit 5 has been shown which comprises a battery or direct voltage source UB having its positive pole connected to the ground connection of the circuit assembly, and a ring current generator in series with the battery UB, being in the form of two identical, push-pull alternate current sources shown at AC. Switch-over means, such as a relay and respective contacts, generally indicated at 7, are represented by two switches 7A and 7B arranged to connect terminals A and B, respectively, of the telephone line L to the output terminals 3A and 3B or the interface circuit 3 of the terminals of the supply circuit 5. The last-named connection is established through two resistors RP having the same resistive value, e.g., 300 Ohms, and forming the so-called bridge resistances which, as is known, are required for the coupling at the exchange between the supply circuit and the subscriber line.

Telephone circuit assembly

Life of this patent

Telephone circuit assembly

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims25

Description2,754 words

Drawings

Classification2 codes

Life of this patent

Description2,754 words