JPS61135290A - Trunk line trunk circuit - Google Patents

Abstract

PURPOSE:To decrease the number of components constituting a trunk line trunk circuit by constituting the titled circuit so that an incoming detection circuit, a reverse detection circuit and dial transmission circuit of the trunk line trunk circuit are incorporated while being related mutually. CONSTITUTION:When an incoming signal is fed to trunk line terminals L1, L2, the signal is detected by a photocoupler 2 and the slope of the incoming signal is detected by an integration circuit comprising resistors 23, 24, 26 and a capacitor 25. The slope is inverted by an inverter 27 and transmitted to a CPU via a CPU port 1. A CPU outputs a signal to a CPU port 2 to actuate a relay 1, a contact rl1 is selected to the closed position, a DC loop is formed between the trunk lines L1 and L2 to acquire the trunk line. The output of the port 2 is lost intermittently at a predetermined interval by the dial operation. The relay 1 repeats restoration and operation accordingly, resulting that the contact rl1 of the relay 1 is opened intermittently, then no trunk line pulse is transmitted.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a central office line trunk circuit in a key telephone system, PBX, etc., and more specifically relates to an incoming call detection circuit, a reverse detection circuit, and a dial pulse detection circuit for a central office line trunk circuit. Regarding the sending circuit.

(Prior Art) Conventionally, an incoming call detection circuit, a reverse detection circuit, and a dial pulse sending circuit have been configured separately and independently according to their respective functions, and their CPU interface boards have also been provided independently.

FIG. 2 is a circuit diagram of a conventional office line trunk circuit configured in this manner. In the figure, one station line terminal L1 is connected to one AC input terminal of the diode bridge 11, the make side terminal of the contact r12 of the relay 2, and the transformer 21.
Connected to one end of the primary terminal of the The other station line terminal L2 is connected to one end of the photodiode of the photocoupler 2 and one end of the Zener diode 1. The other end of the photodiode of the photocoupler 2 is connected to one end of the resistor 3. The other end of the Zener diode 1, the other end of the resistor 3, and the fixed side terminal of the contact r11 of the relay 1 are connected.

The break side terminal of contact rll of relay l is connected to another AC input terminal of diode bridge 11 via capacitor 10. The meter side terminal of the contact rll of the relay 1 is connected to the break side terminal of the contact r13 of the relay 3 and one end of the resistor 5. The other end of the resistor 5 is connected to the fixed side terminal of the contact r13 of the relay 3, the fixed side terminal of the contact r12 of the relay 2, and the other end of the primary side terminal of the transformer 21 via the capacitor 6.

The phototransistor emitter side of photocoupler 2 is connected to GND.
The collector side is connected to one end of the resistor 4 and the CPU port l. The other end of the resistor 4 is connected to a power source. The secondary side of the transformer 21 is connected to a communication path switch (not shown).

The + side output of the diode bridge 11 is connected to one end of a resistor 12, and the other end of the resistor 12 is connected to one end of a photodiode of a photocoupler 13. The other end of the photodiode of the photocoupler 13 is connected to one side of the diode bridge 11. The phototransistor emitter side of the photocoupler 13 is connected to GND, and the collector side is connected to one end of the resistor 14. The other end of the resistor 14 is connected to one end of the capacitor IB, one end of the resistor 15, and one end of the resistor 17. The other end of the capacitor IB is connected to GND, the other end of the resistor 15 is connected to the power supply, and the other end of the resistor 17 is connected to the CPU boat 2. C
The output of PU port 3 is connected to the base of transistor 18. The emitter of the transistor 18 is connected to GND, and the collector is connected to one end of the winding RLI of the relay 1 and one end of the diode 7. Winding RLI of relay l and the other end of diode 7 are connected to a power supply. Similarly, CP
The U-boat 4 is connected to the winding R of the relay 2 via the transistor 18.
To L2, CPU port 5 is connected via transistor 20 to winding RL3 of relay 3.

Next, the operation will be explained.

First, when an incoming signal (18Hz) is applied to Ll and L2, it is full-wave rectified by the diode bridge 11, the incoming signal current flows through the photodiode of the photocoupler 13, and the phototransistor of the photocoupler 13 receives the 18Hz of the incoming signal.
It turns on from off depending on the situation and detects an incoming call. Resistor 14,
The integrator circuit consisting of 15.17 and capacitor IB is for detecting the slope of the incoming signal. When a call is received, make sure that the call path switch system does not send out the incoming signal.
It is switched by contact rll of relay 1. CPU
When boat 2 detects an incoming call, a predetermined display is displayed, and when a response operation is performed, CPU port 3
An output is generated, transistor 18 turns from off to on, and relay l operates. Contact r11 of relay l is on the meter side, a DC loop is formed between station line terminals L1 and L2, and the station line is captured. After that, calls and communications took place,
At the end of the call, the output from the CPU port 3 disappears and the relay 1 is restored, so the DC loop between the station line terminals L1 and L2 disappears, and the system returns to the initial standby state again.

Next, when making a call from the main office line trunk, the CPU
Output is generated at port 3, relay L operates, and station line terminal L
A DC loop is formed between l and L2. When the dial is operated, an output is generated in the CPU port 4 and the relay 2 is operated, and the contact r12 of the relay 2 is metered.
Relay 3 repeats operation and recovery accordingly, Relay 3
Since the contact r13 breaks intermittently, a dial pulse is sent to the central office line. At this time, the series circuit of the resistor 5 and the capacitor 6 serves as a spark extinguishing circuit for the contact r13 of the relay 2.

Here, an exchange (not shown) operates to call the other party, and waits for the polarity of the central office line to be reversed in response to a response from the other party. The Zener diode 1 maintains the voltage of the photocoupler 2 at the Zener voltage when a signal higher than the Zener voltage is applied to the photocoupler 2. The resistor 3 is a protection resistor for the photodiode of the photocoupler 2.

When dialing is completed, the polarity of the office line is set to office line terminal Ll.
If the terminal L2 is negative, no current will flow through the photodiode of the photocoupler 2, and the photocoupler 2
The polarity of the 0 station line in the standby state of the phototransistor is reversed, and the station line terminal L1 is negative and the station line terminal L2 is negative. ,7
It is output to the CPU board 7,1. As a result, the polarity of the office line is reversed by the response from the other party, and the CPU port 1
Detected via.

(Problems to be Solved by the Invention) However, such conventional office line trunk circuits have the following problems.

First, the functions of incoming call detection, reverse detection, and dial pulse sending are mainly performed by photocoupler 2 and photocoupler 1, respectively.
3 and relay contact r13. That is, each of these functions is accomplished by a separate and independent circuit. Therefore, the number of parts constituting the central office line trunk circuit is large, and the mounting area within the package for accommodating these parts is large, resulting in high costs.

Second, the polarity reversal (reverse) detection of the office line is performed at the office line terminal L.
Since the polarity is assumed to be reversed when l is negative and the office line terminal L2 is at ground level, it is necessary to perform construction so that the above polarity is achieved when connecting the office line to the office line trunk circuit.

Therefore, the present invention aims to solve these problems.

(Means for Solving the Problems) The present invention provides a central office line trunk that is provided between a central office line and a communication path switch of an exchange, and that detects incoming calls, detects polarity reversal of the central office line, and sends out dial pulses. Targets circuits. According to this invention, in this central office trunk line,
A current detection means and a relay contact are inserted in series between the office lines, a drive means for driving the relay contact, and the drive means is controlled based on a state of a signal of the office line detected by the current detection means. Detection of incoming calls Detecting polarity reversal of the 1-station line and controlling means for sending out dial pulses.

(Function) When the incoming @ signal comes, the incoming signal is detected by the current detection means. The current sensing means provides an output while an incoming signal is present. The control signal receives this output, recognizes that there is an incoming call, and performs a response operation corresponding to the incoming call.Then, the control means controls the drive means to make the relay contact. As a result, a DC loop is formed between the office lines, and when the zero call or communication in which the office line is captured ends, the control means controls the drive means to break the relay contact. As a result, the DC loop is eliminated and the office line trunk circuit returns to its original standby state.

Next, when a call is made from the central office trunk side, the control means controls the drive means to meter the relay contact. As a result, a DC loop is formed between the station lines.The control means controls the drive means in response to the dial operation.
Breaks relay contacts intermittently. As a result, a dial pulse is sent out. When the sending of the dial pulse is completed, the control means controls the drive means to hold the relay contact in the make. In this state, the one-office line trunk circuit is waiting for polarity reversal (reversal) of the office line. The current detection means detects changes in current.

When there is a change in the current, the control means regards it as a response from the other party, and proceeds to a predetermined operation thereafter.

(Example) Hereinafter, the present invention will be described in detail based on an example with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the invention. In the figure, one station line terminal L1 is connected to the transformer 21.
Connected to one end of the primary terminal of the One of the station line terminals L2 is connected to one end of the photodiode of the photocoupler 2, one end of the Zener diode 1, and one end of the resistor 22. The other end of the photodiode of the photocoupler 2 is connected to one end of the resistor 3. The other end of the resistor 3, the other end of the Zener diode 1, the other end of the resistor 22 is connected to the make side terminal of the contact rll of the relay l, and one end of the resistor 5. The other end of the resistor 5 is connected to one end of the capacitor 6. The other end of the capacitor 6 is connected to the fixed side terminal of the contact rll of the relay l and the other end of the primary side terminal of the transformer 21. The secondary side of the transformer 21 is a communication path switch (not shown).
connected to. The phototransistor side emitter of the photocoupler 2 is connected to GND. Also, on the collector side, resistor 2
It is connected to one end of 3. The other end of the resistor 2a is connected to one end of a capacitor 25, one end of a resistor 24, and one end of a resistor 2B. The other end of the capacitor 25 is connected to GND, and the other end of the resistor 24 is connected to the power supply. The other end of the resistor 2B is connected to the input terminal of the inverter 27.
The output of is connected to CPU port l. The output of CPU port 2 is connected to the base side of transistor 18, the emitter is connected to GND, and the collector is connected to relay 1.
is connected to one end of the winding RLI and one end of the diode 7. The other end of the winding MRLI to the relay and the other end of the diode 7 are connected to the power supply.

Next, the operation will be explained.

First, a description will be given of a call receiving operation for the central office line trunk circuit shown in FIG. First, when an incoming signal (18Hz) is applied to the office line terminals LL and L2, an incoming signal current (AC signal) flows through the photodiode of photocoupler 2, and the phototransistor of photocoupler 2 turns from off to on to detect an incoming call. . Here, when a signal higher than the Zener voltage is applied to the photodiode of the photocoupler 2, the Zener diode 1
The resistor 3, which maintains the Zener voltage, limits the current of the photodiode of the photocoupler 2 and protects it. Further, the resistor 22 is a resistor for setting an incoming call detection sensing voltage. Furthermore, the capacitor 6 functions to prevent direct current signal components from being sent to a communication switch system (not shown).

The incoming signal is detected by photocoupler 2 and resistor 23°24
, 28 and a capacitor 25, the slope of the incoming signal is detected. This slope is reversed by an inverter 27. Therefore, the inverter 27 outputs "H" only while the incoming signal is coming. This signal is sent to a CPU (not shown) via CPU port 1. The CPU displays that an incoming signal has arrived, and responds accordingly.Next, the CPU displays the incoming signal.
Outputs a signal to U port 2. As a result, the transistor changes from off to on, and current flows through winding RLI of relay 1. Therefore, contact rll of relay l becomes the make side, and a DC loop is formed between station 1 line terminals L1 and L2,
The central office line is captured.

After that, calls and communications are made, and when these are completed, CP
Since the output of U port 2 disappears and relay l is restored (contact r11 breaks), the DC loop between station line terminals L1 and L2 is eliminated, and the system returns to the initial standby state again.

Next, when making a call from this central office trunk line,
An output is generated at the CPU port 2, current flows through the winding RLI of the relay 1, the contact r11 of the relay 1 is made, and a DC loop is formed between the station line terminals L1 and L2. By operating the dial, the output of the CPU port 2 is intermittently turned off at predetermined intervals. In response to this, relay 1 repeats recovery and operation, and as a result, contact rll of relay 1 breaks intermittently, and a central office line dial pulse is sent out. At this time, the series circuit of the resistor 5 and the capacitor 6 serves as a spark extinguishing circuit for the contact r11 of the relay 1.

When the transmission of the dial pulse is completed, an output is continuously generated at the CPU port 2, and the contact rll of the relay l is maintained at the meter. At this point, the exchange operates and calls the other party.
Waiting for polarity reversal (reverse) of the station line in response to a response from the other party.

When the dial is completed, the polarity of the office line is changed to the office line terminal L.
When L is negative and the station line terminal L2 is at ground level, a current flows through the photodiode of the photocoupler 2, the phototransistor of the photocoupler 2 is turned on, and an “H” signal is sent to the CPU port 1 via the integrating circuit and the inverter 27. ” appears. On the other hand, if the polarity of the station line is negative when the dialing is completed, the 1st station line terminal LL is negative and the 1st station line terminal L2 is negative.
By the operation opposite to the above, air appears at the CPU port l. However, regardless of the polarity of the office line terminals L1 and L2, in order for the polarity of the office line to be reversed when there is a response from the other party, the input to CPU port 1 must be grounded when it is "H". If it is earth ki, it changes to "H" 0 The CPU (not shown) regards this change as the other party's response,
The process moves on to subsequent predetermined operations.

The first embodiment of this invention has been described above. As can be seen from the above description, in the first embodiment, the resistor 5 and capacitor 6 function as a DC separation circuit at the time of incoming calls and a spark cancellation circuit at the time of dial pulses. Therefore, of the circuit shown in FIG. 2 described above, the relay 1, the transistor 18 that controls it, the CPU port 3, etc. are unnecessary.

Further, since the photocoupler 2 has a function of detecting incoming calls and polarity reversal, the CPU port 2 and related components in the circuit shown in FIG. 2 are unnecessary. Furthermore, since the configuration is such that polarity reversal is detected by a change in the polarity of the CPU port 1, there is no need to consider polarity when connecting the office line to the office line terminals L1 and L2 of the office line trunk.

In the first embodiment, a photocoupler is used to detect the current, but the same structure can be obtained by inserting a two-winding relay between the station wires instead.

Next, the circuit diagram of the second embodiment of the present invention is shown in FIG. 3. The characteristics of the circuit shown in the same figure are as follows. A relay 2 is added to the circuit shown in Figure s1, a contact of the relay 2 is inserted in parallel to the primary side of a transformer 21, and a transistor 18 is provided for controlling this. That is, if the primary side of the transformer 21 is not shunted during dialing, the pulse waveform will be adversely affected by the influence of the inductance of the transformer 21, so the relay 2 is provided to prevent this. In this circuit operation, the incoming operation is the first
The 0 transmission operation, which is similar to the embodiment of By doing this, the dial palace is sent to the other party.

When dialing is completed, relay 2 is restored.

(Effects of the Invention) As explained above, according to the present invention, the incoming call detection circuit, reverse detection circuit, and dial transmission of the central office line trunk circuit are interconnected and integrated, so that the central office line trunk circuit can be integrated. The number of constituent parts is small, the mounting area within the package for accommodating these parts is small, and an economically superior central office line trunk circuit can be provided. Further, according to the present invention, there is no need to consider polarity during the construction work to connect the office line to the office line terminals L1 and L2, and the construction work is simplified. Therefore, even if the central office line is swapped between the exchange and the subscriber due to a construction error, there will be no problem according to the present invention.

The present invention is suitable for application to office line trunk circuits in key telephone systems, PBXs, and the like.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of this invention, FIG. 2 is a circuit diagram of a conventional central office line trunk circuit, and FIG. 3 is a circuit diagram showing a second embodiment of this invention. . l... Zener diode, 2... Photocoupler, 3
...Resistor, 4...Resistor, 5...Resistor, 6...Capacitor, 7...
Diode, 8... Diode, 9... Diode, 10... Capacitor, 11... Diode bridge, 12... Resistor, 13... Photocoupler, 14... Resistor, 15... Resistor ,
IB...Capacitor, 17...Resistor, 1B
...Transistor, 18...Transistor, 2
0...Transistor, 21...Transformer, 22
...resistance, 23...resistance, 24...resistance, 25...capacitor, 2B...resistance, 27...
...Inverter, RLI...Relay winding, 1'lL2...Relay winding, RL3...Relay 3 winding, rll...Relay 1 contact, r12...Relay 2 contact , r13...Relay 3 contact.

Claims (1)

[Claims] In a central office line trunk circuit that is installed between a central office line and a communication path switch of an exchange, and detects incoming calls, detects polarity reversal of the central office line, and sends out dial pulses, it is inserted in series between the central office lines. A current detecting means, a relay contact, a driving means for driving the relay tangent, and a control means for controlling the driving means based on a state of a signal of the central office line detected by the current detecting means to detect an incoming call and to determine the polarity of the central office line. A central office line trunk circuit comprising control means for detecting reversal and sending out dial pulses.