KR900008495Y1 - Subscriberis line circuit - Google Patents

Abstract

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Description

Switch line detection circuit of exchange

1 is a circuit diagram according to the present invention.

* Explanation of symbols for main parts of the drawings

R1-R8: Resistor ZD1-ZD2: Zener Diode

D1-D4: Diode PC1-PC2: Photocoupler

B1-B2: buffer

The present invention relates to a switch pressurized line monitoring circuit, and more particularly to a subscriber line monitoring circuit of the public telephone subscriber circuit.

Conventional switch subscriber line monitoring circuit has been monitoring the loop, charging signal, dial signal, etc. of the telephone line with the presence or absence of current in the telephone line.

However, the conventional circuit for monitoring a line has a problem in that it is indistinguishable from loops and dialing signals on the telephone side when the voltage is cut due to the characteristics of the switch, and there are many problems in detecting loops and dialing signals on the telephone line.

Accordingly, an object of the present invention is to provide a circuit capable of accurately monitoring loops and dialing of a line by monitoring current and voltage states on a subscriber line.

Another object of the present invention is to provide a circuit for monitoring a voltage break in a subscriber subscriber line.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a circuit diagram according to the present invention, in which one input (a) of an exchange subscriber circuit is input to an anode and a connection line of a cathode inputs an input of an exchange subscriber line b. Second zener diode ZD2 and the first and second zener diodes ZD1 and ZD2 connected in parallel with the first zener diode ZD1 and the first diode ZD1 in parallel with each other. In a direction opposite to the first photocoupler PC1 and the first photocoupler PC1 in which the resistor R1 connected in parallel to the second zener diode ZD2 and the internal light emitting diode LED1 are connected in the same direction. One side is connected in series to the second photocoupler PC2 to which the internal light emitting diode LED2 is connected and the resistor R1, and the other end is connected to the anode of the light emitting diode LED of the first photocoupler PC1. Current loop and pulse die of subscriber And a voltage divider for outputting a charge detection signal, resistance divider between resistors R3-R6 and a predetermined power supply voltage VCC directly connected at both ends of the switch subscriber line (a) and (b). Resistors R7 and R8 input to the connection node C of R5 and diodes D1 and D2 for clamping the voltages of the connection node A and the resistor R3 and R4; A buffer B1 for buffering the output signals of the diodes D1 and D2, a diode D3 and D4 for clamping the voltage of the connection node B of the resistors R5 and R6, and the diode And a voltage detector for detecting a voltage break in the switch subscriber line and outputting a detection signal.

Unexplained reference numeral (C) (D) is a connection terminal to be connected to the telephone, (e) (f) is a microprocessor (not shown) to recognize the loop state, dial state, charging pulse, etc. of the subscriber (G) and (H) are terminals connected to the microprocessor for recognizing the voltage state of the subscriber line (a) and (b).

Line a by the call current supplied from the exchange to the subscriber line (a) (b) in the " hook-on " state in which the handset of the subscriber's telephone (not shown), which is now connected to terminal (C) (D), is lowered. Ground (GND) and b line -48V.

As described above, if the ground (GND) and -48V voltage or the opposite voltage is input to the subscriber line (a) and (b), the handset of the telephone is continuously lowered. The light emitting diodes (LED1) (LED2) of (PC1) (PC2) are in the " off " state, whereby the connection points (e) or (f) of the microprocessor detecting loop signals, dial signals, charging signals, etc. The state of "high" is maintained and the subscriber is judged to be "hook-on".

On the other hand, when the subscriber telephone connected to the terminals C and D is "hooked off" in the above state, that is, when the handset is lifted, the signal of the subscriber line b is transferred to the telephone connection terminal D from the line (a). The signal becomes a constant voltage by the first zener diode ZD1 or the second zener diode ZD2 and is inputted to the terminal of the subscriber telephone C to form a current loop.

At this time, if the voltage of the subscriber line (a) is detected as a constant DC voltage by the first zener diode (ZD1), its constant voltage is limited to a current in a predetermined state by the resistors (R1) (R2) to the light emitting diode ( It is input to the anode of LED1).

Therefore, the light emitting diode LED1 of the first photocoupler PC1 emits light by the voltage of the first zener diode ZD.

The light emission of the light emitting diode LED1 causes the phototransistor Q1 of the first photocoupler PC1 to be "on", whereby the connection point e of the microprocessor which detects a predetermined state falls to "low".

The "low" of the connection point e causes the microprocessor to monitor the subscriber's loop condition.

In this state, when the subscriber performs pulse dialing, the logic of the connection point (e) repeatedly transitions to the "high" and "low" states by switching the loop, and in this logic transition state, the microprocessor performs the dialing of the subscriber. Will be detected.

When the current flowing in the loop is reversed by the charging pulse of the air exchanger operated as described above for the predetermined time (in case of domestic, the charging pulse time is 300mSec), the second zener diode ZD2 becomes the loop current. The voltage at the time of inversion is constantly detected, and the light emitting diode LED2 of the second photocoupler PC2 is "on" and the light emitting diode LED1 of the first photocoupler PC2 is "off".

Accordingly, the phototransistor Q1 of the first photocoupler PC1 is "off" and the phototransistor Q2 of the second photocoupler PC2 is "on" so that the connection point e of the microprocessor is "high", ( f) becomes " low ".

As described above, when the signals of the connection points (e) and (f) are incompatible for a predetermined time, the microprocessor detects the charging from the exchange.

On the other hand, a predetermined divided voltage of the resistors R7 and R8 in which the ground is separated overlaps the connection node C of the resistors R3-R6 connected in series across the telephone subscriber preferences (a) and (b). Is entered.

Therefore, the voltages applied across the subscriber lines (a) and (b) and the voltages applied to the resistors R7, R8, diodes D1-D2, D3-D4, and the buffer gates B1, B2 are mutually different. The voltage is superimposed on the resistors R3-R6 with the ground separated.

As described above, the voltages of the resistors R7 and R8 with the ground separated are superimposed on the connection node points C of the resistors R3-R6 so that the respective voltages output from the node points A and B are each. The maximum voltage is clamped by the diodes D1-D2 and D3-D4 connected to the node points A, B and input to the respective buffer gates B1, B2.

At this time, the voltage detection of the subscriber line uses a resistor (R3-R6) connected in series at both ends of the line (a) and (b) as a high resistance to increase the impedance seen from the input terminals (a) and (b), and increases the buffer B1 ( B2) is detected using CMOS.

Therefore, when the subscriber line current is not supplied to the subscriber line (a) (b) due to the characteristic operation of the exchange, the connection point (G) (H) of the microprocessor is all in a "high" state, and the applied subscriber call when voltage is applied. When a current is input across the subscriber lines (a) and (b), the output of any one of the connection terminals G and H becomes "low" due to the overlapping voltage difference.

Therefore, it can be seen that the microprocessor can accurately monitor the voltage breakdown of the exchanger, so that the loop and dial signals of the subscriber can be accurately detected.

As described above, the present invention installs a current detection circuit in series on a subscriber line, and installs a voltage detection circuit in parallel to accurately detect a loop dialing signal without error by detecting the state of the subscriber line by monitoring the state of voltage and current. There is an advantage to this.

Claims (1)

In a circuit for monitoring an exchange subscriber line using a microprocessor, one side input (a) of the exchange subscriber line (a) is input to the anode and the cathode inputs the input of the switched subscriber line (b) to the terminal (d). The second Zener diode ZD2 and the first and second Zener diodes connected in parallel with the first Zener diode ZD1 and the first diode ZD1 connected to a connection terminal C (not shown) The first photocoupler PC1 and the first photocoupler PC having the resistor R1 connected in parallel with each other and the second zener diode ZD2 and the internal light emitting diode LED1 connected in the same direction. One side is connected in series with the second photocoupler PC2 to which the internal light emitting diode LED2 is connected in a direction opposite to the PC1 and the resistor R1, and the other end thereof is the light emitting diode of the first photocoupler PC1. LED) consists of a resistor (R2) connected to the anode A current detector which detects a charging signal and the like by the inversion of the pulse dial current loop due to the interruption of the current loop of the particle and the current loop and outputs it to the microprocessor, and is connected in series with both ends of the exchanger pressure line (a) (b) The resistors R3-R6 and the predetermined power supply voltage VCC to divide the resistors and input them to the connection node C of the resistors R4 and R5. R4) A connection between the diodes D1 and D2 for clamping the voltage of the connection node A and the buffer B1 and the resistors R5 and R6 that buffer the output signal of the diodes D1 and D2. The diode (D3) (D4) for clamping the voltage of the node (B) and (B2) for buffering the output signal of the diode (D3) (D4) to detect the voltage cut-off phenomenon of the switch subscriber line to detect the detection signal A circuit comprising a voltage detector for outputting to a microprocessor.