KR100713369B1 - Caller id detection central office interface circuit - Google Patents

Abstract

A trunk line interface circuit of a private switching system of the present invention includes a first relay connected to a loop controller and a transformer for transmitting a signal to a codec side and forming a loop for applying a caller number signal input to a loop controller to a transformer when a caller number signal is input, A first resistor connected in parallel with the first relay for providing a path of a signal when a signal other than the caller number signal is applied, and a second resistor connected to the ring side of the transformer and the lightning protection unit to output a caller number signal output from the transformer, And a second resistor connected in parallel with the second relay for providing a path of a signal output from the transformer except for the caller number signal to provide the caller number to the called party .

Caller ID signal, relay, loop

Description

{CALLER ID DETECTION CENTRAL OFFICE INTERFACE CIRCUIT}             

1 is a block diagram of a conventional line interface circuit of a conventional private branch exchange,

2 is a block diagram of a trunk line interface circuit according to the present invention;

The present invention relates to a private branch exchange, and more particularly to a trunk line interface circuit.

In recent communication services, caller identification (hereinafter referred to as "CID") services are becoming common. CID service is a service that provides caller's phone number to the called party.

In general, the trunk line interface circuit of the private branch exchange is configured such that it can not receive the CID information transmitted from the old side after the loop is broken. 1, a conventional trunk line interface circuit of a private branch exchange comprises a lightning protection unit 10, a loop control unit 20, a loop detection unit and a DC bypass unit 30. 1 is a block diagram of a conventional line interface circuit of a conventional private branch exchange. When the ring signal enters the tip end (T) from the trunk line side, the signal is input to the loop control unit (20) through the lightning strike protection unit (10). When the ring signal is inputted, the relay 1 (RL1) of the loop controller 20 is connected to the contact a and b, the relay 2 (RL2) is connected to the contact d and f, and the ring signal is connected to the capacitor 1 (Z1), Zener diode 2 (ZD2), and relay 2 (RL2) to the loop detection and DC bypass unit 30, respectively. The ring signal input to the loop detection and DC bypass unit 30 is detected by the ring signal / loop detection circuit 35. Thereafter, when a hook is turned off, a call loop is formed. When the call is completed, the loop is broken by the relay 1 (RL1) and the relay 2 (RL2).

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Accordingly, an object of the present invention is to provide a trunk line interface circuit for receiving a caller number signal input from the trunk line side.

According to an aspect of the present invention, there is provided a trunk line interface circuit of a private switching system, the trunk line interface circuit comprising: a loop controller; and a transformer connected to a codec for transmitting a signal, A first resistor connected in parallel with the first relay to provide a path for the signal when a signal other than the caller number signal is applied; A second relay connected to the negative ring side to form a loop for applying the caller number signal output from the transformer to the ring side of the lightning protection unit; and a second relay connected in parallel with the second relay, And a second resistor for providing a path of the output signal.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be noted that like elements in the drawings are denoted by the same reference numerals and the same reference numerals as possible. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

In the trunk line interface circuit, the ring signal is generally input for 2 seconds. Then, the CID signal having the CID data is transmitted from 2.9 to 3.7 seconds after the waiting time of 0.5 second, and the next ring signal is inputted after the waiting time of 0.2 second. The present invention adds a relay to provide a CID signal to the called party even after the loop is broken or a loop is not formed. And forms a loop that is input directly to the codec side without passing through the loop detection and DC bypass unit 30 while the CID signal is inputted through the added relay.

2, a description will be given of a trunk line interface circuit to which the present invention is applied. FIG. 2 is a circuit diagram of a trunk line interface circuit according to the present invention. 2, the trunk line interface circuit according to the present invention includes a lightning protection unit 10, a loop control unit 20, a loop detection and DC bypass unit 30, and a CID signal processing unit 40.                     

The lightning protection unit 10 includes a surge protector 1 (SP1), a surge protector 2 (SP2), a surge protector 3 (SP3), a switch 1 (S1), and a switch 2 The surge voltage and current of the signals input / output to the ring stage R are removed. The surge protector 1 (SP1) and the surge protector 2 (SP2) surge protector 3 (SP3) are surge protector elements that are connected to the tip end and the FGND (Foreground), the ring terminal and the FGND, . The switch 1 (S1) and the switch 2 (S2) are polyswitches. When a DC current exceeds a certain current, both terminals of the switch are opened according to the negative resistance characteristic to prevent the input of surge current.

The loop control unit 20 includes a relay 1 (RL1), a relay 2 (RL2), a capacitor 1 (C1), a capacitor 2 (C2), a resistor 1 (R1), a resistor 2 (R2), a zener diode 1 And a diode 2 (ZD2), forming a loop according to the input signal. The relay 1 (RL1) generates a dial pulse under the control of a relay driver (not shown). When the signal inputted to the loop controller 20 is a ring signal or a CID signal, the relay 1 (RL1) And when a dial pulse signal is generated, the contact a and the contact c are connected. The resistor 2 (R2) and the capacitor 2 (C2) absorb and remove the impulse generated when the dial pulse is generated. When the ring signal is input, relay 2 (RL2) connects the d contact and f contact under the control of the relay driver. When the hook-off or dial pulse signal is generated, the contact e and f contact do. The capacitor 1 (C1) and the resistor 1 (R1) are the path of the ring signal when the ring signal is input to the loop controller 20 and the zener diode 1 (ZD1) and zener diode 2 (ZD2) Clamping.                     

The loop detection and DC bypass unit 30 includes a constant current circuit 31, a rectification circuit 33, a ring signal / loop detection circuit 35, a capacitor 3 (C3), and a TSV (Transient Voltage Suppressor) Thereby detecting the ring signal and the loop, and bypassing the direct current. A rectifying circuit 33 composed of four diodes rectifies an input signal. The constant current circuit 31 includes a transistor Q1, a diode D1, a diode D2, a resistor R4, a resistor R5, a zener diode ZD4, a capacitor C5, 6 (C6) to bypass the direct current of the signal inputted through the rectifying circuit 33. [ The ring signal / loop detection circuit 35 includes a light emitting diode (LED), a phototransistor Q2, a resistor 7 (R7), a resistor 8 (R8) and a capacitor 4 (C4) do. TSV (Transient Voltage Suppressor) (TSV1) is a device having characteristics similar to Zener diodes. It prevents loop detection due to surge voltage at the time of hook-off and damages of diodes constituting DC bypass unit 30. Capacitor 3 (C3) processes the alternating current of the input signal.

A CID signal processing unit 40 including a relay added according to the present invention includes a relay 3 (RL3), a relay 4 (RL4), a resistor 9 (R9), and a resistor 10 So that the signal is inputted to the transformer T1 without going through the loop detection and DC bypass unit 30. [ The relay 3 (RL3) is connected between the node 1 (N1) between the capacitor 1 (C1) and the resistor 1 (R1) of the loop control unit 20, the capacitor 3 (C3) of the loop sensing and DC bypass unit 30, (N2) and the node 3 (N3) between the nodes T1 and T1. When the CID signal is input, relay 3 (RL3) connects the g contact of node 1 (N1) and the contact of i2 of node 2 (N2) under the control of the relay driver and transmits the CID signal directly to the booster. Resistor 9 (R9) is a 0Ω resistor connected in parallel to relay 3 (RL3), and is the path through which other signals pass when the CID signal is not input. The relay 4 (RL4) is connected between the node 4 (N4), the node 5 (N5), the rectifier 33 and the switch 2 (S2) between the transformer T1 and the resistor 5 (R5) of the loop sensing and DC bypass unit 30, ) Node 6 (N6). The relay 4 (RL4) is connected to the j contact and the l contact under the control of the relay driver so that the CID signal that has passed through the transformer T1 passes through the loop sensing and DC bypass unit 30, . The resistor 10 (R10) is connected to the relay 4 (RL4) as a 0-ohm resistor and is a path through which the signals pass when the CID signal is not inputted.

The transformer T1 transmits an applied signal to a codec (not shown). When the codec converts the input signal to a digital signal and applies it to the controller, the controller interprets the signal.

The ring signal inputted through the tip end T of the trunk line interface circuit having the above structure is input to the loop control unit 20 via the lightning protection unit 10. The ring signal inputted to the loop control unit 20 passes through the d contact point of the capacitor 1 (C1), the resistor 1 (R1), the zener diode 1 (ZD1), the zener diode 2 (ZD2) and the relay 2 (RL2) And is applied to the rectifier 33 of the loop detection and DC bypass unit 30. The ring signal outputted from the positive terminal of the rectifier 33 is DC-bypassed by the constant current circuit 31 and applied to the light emitting diode (LED) of the ring signal / loop detection circuit 35 to be supplied to the phototransistor Q2 Is turned on to sense the ring signal. Thereafter, when the CID signal is applied to the tip end T after 0.5 seconds, the CID signal is input to the loop control unit 20 through the lightning protection unit 10. The CID signal is applied to the transformer T1 via the g contact and the I contact of the relay 1 (C1) of the loop controller 20 and the relay 3 (RL3) of the CID signal processor 40 and is transmitted to the codec, And is transmitted to the control unit. The CID signal output from the transformer T1 is applied to the ring side of the lightning protection unit 10 through the j contact and the l contact of the relay 4 (RL4).

Therefore, the CID signal is directly transmitted to the codec side without going through the loop detection and DC bypass unit 30. [

In the above description of the present invention, specific examples have been described. Therefore, the scope of the present invention should not be limited by the described embodiments but should be determined by the equivalents of the claims and the claims.

As described above, the present invention provides a circuit for forming a transmission loop of a CID signal in the trunk line interface circuit, so that the called party can receive the calling party number.

Claims (1)

In a trunk line interface circuit of a private switching system, A first relay connected to the transformer for transmitting a signal to the codec side and a loop connected to the loop controller to form the loop for applying the caller number signal inputted to the loop controller when the caller's number signal is inputted to the transformer, A first resistor connected in parallel with the first relay and being a path through which the signal is inputted from the loop detection and DC bypass unit to the transformer when a signal other than the caller number signal is applied, A second relay connected to the ring side of the transformer and the lightning protection unit to form a loop for applying the caller number signal outputted from the transformer to the ring side of the lightning protection unit; And a second resistor connected in parallel to the second relay and being a path through which a signal excluding the caller number signal output from the transformer is input to the loop detection and DC bypass unit, Circuit.

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