JPH0736586B2 - No ringing terminal equipment - Google Patents

Description

The present invention relates to a no ringing terminal device. More specifically, the present invention relates to a terminal device that enables meter reading and the like without making a ringing tone of a telephone by using a telephone network.

[Prior Art] In no ringing communication, the existing telephone network is used, and meter terminals installed in each telephone user's home without ringing the telephone bell from the meter reading center that performs meter reading, etc. Calls are received and the measured values are read. In particular, since it uses the existing telephone network, it works effectively when used in a low-traffic metering system with a large number of meters etc. and a short line hold time per unit time so as not to hinder the call. .

A conceptual block diagram of this no-ringing communication is shown in FIG. 2 and will be described.

The meter readings of water meters, gas meters, etc. in each home have a large number of meter reading points, although the number of times is small. The existing telephone network is used to read the meters in each home, and the meter-reading center-side device 11 such as a meter uses the originating-side exchange 12 and the receiving-side exchange 13 to measure the meters in each home. Is connected to the terminal 15. The meter terminal 15 includes a terminal device 16 that forms an interface between each of the meters M1 to Mn, its sensors SE1 to SEn, the telephone set T, and the terminating exchange 13. Further, the receiving side exchange 13 is connected with a no ringing trunk 14 required for a meter reading operation.

In order to enable the installation of the electric machines T and the sensors SE1 to SEn for a plurality of meters on one telephone line, the meter reading center side device 11 prepares a plurality of calling signals. Therefore,
From the meter reading center side device 11 to the meter terminal 15 at the telephone user's house
When calling, the desired sensor SE1 to SEn can be selected and received without ringing the bell of the telephone T.

Such a meter reading operation is performed by utilizing the idle time of the telephone. Even if the meter reading is performed, if the telephone subscriber tries to make a call, it is determined that the handset of the telephone set T has been lifted. Is detected, the called side exchange 13 is immediately contacted, and the no-ringing trunk connected thereto operates to stop the meter reading operation.

If the number of meter terminals 15 for telephone subscribers is extremely large, the meter reading center side device 15 should be installed in order to shorten the connection time.
To the no ringing trunk 14 of the terminating exchange 13 while holding the line between the no ringing trunk 14 and the many terminals connected to the terminating exchange 13 and the meter terminal 15 one after another. We are reconnecting and conducting meter reading work.

A general connection operation flow in the no-ringing communication will be described with reference to FIG.

When the meter-reading center 11 makes a call (off-hook), a dial tone (DT) is returned from the calling-side exchange 12, so the meter-reading center-side device 11 sends the first selection signal (no ringing trunk 14 to be called). After the telephone number), the first connection control signal (NRTS1) is transmitted, and the originating exchange 12 receives the no-ringing trunk 14 of the terminating exchange 13 designated by the first selection signal, and the originating side Check the caller between the exchange 12 and the no ringing trunk 14,
A fraudulent use is prevented, and a communication path between the meter reading center side terminal 11 and the no ringing trunk 14 is set in the case of an authorized user.

The no-ringing trunk 14 is the meter reading center side device 11
When the second connection control signal (NRTS2) is received, the second selection signal request signal (SDR) is transmitted.

When the meter-reading center side device 11 receives the second selection signal request signal (SDR), it disconnects the second connection control signal (NRTS2), whereby the no ringing trunk 14 sends the second selection signal request signal (SDR). I will refuse.

When the meter reading center side device 11 detects the disconnection of the second selection signal request signal (SDR), the second selection signal (a telephone number of a general household in which the meter terminal 15 is installed) and a plurality of sensors SE1 to SEn for no ringing. Sends a signal (NRS selection signal) for selecting an arbitrary sensor (NRS), and then sends a third connection control signal (NRTS3).

No ringing trunk 14 second selection signal and NR
Upon receiving the third connection control signal (NRTS3) after the S selection signal, the terminating exchange 13 receives the telephone line and no ringing.
The trunk 14 is connected, the no ringing trunk 14 sends out a signal (NRS) for calling a specific sensor SE, and the selected meter terminal 15 sends back a response signal (ANS) to the no ringing trunk 14. .

When the no ringing trunk 14 receives the response signal (ANS), it sends the response signal to the originating exchange 12.
The originating side exchange 12 displays the response of the meter terminal 15 to the meter reading center device 11 by reversing the polarity of the line to the meter reading center side device 11. The line between is set up and data communication begins.

When the data communication is completed, the meter reading center side device 11 disconnects the third connection control signal (NRTS). Third connection control signal (NR
TS) disconnects the no-ringing trunk 14 from the meter terminal 15 and sends a restoration signal to the originating exchange.
Then, the exchange 12 on the originating side restores the polarity of the line connected to the device 11 on the meter reading center side.

When the meter reading center side device 11 disconnects the DC loop, the connection between the originating exchange 12 and the no ringing trunk 14 is released.

When performing continuous meter reading, after the polarity of the line to which the meter reading center side device 11 is connected is restored, the meter reading center side device 11 sends the second connection control signal (NRTS2) again, and the no ringing trunk 14 Second selection signal request signal (SDR)
Is sent, and the meter reading center side device 11 sends the second selection signal and
The NRS selection signal connects to the next meter terminal 15.

In this way, the meter reading operation is advanced.

A specific circuit diagram of the conventional terminal device 16 will be described with reference to FIG.

L1 and L2 are office lines connecting between the terminating exchange 13 and the terminal device 16, and when the telephone set T for communication is not used, these office lines L1 and L2 are maintained at high impedance. There is a need. Therefore, even in the meter reading operation for no ringing, it is required to maintain a high impedance in the monitoring of the polarities of L1 and L2 and the communication of the meter reading data. At the same time, the station lines L1 and L2 are required to have an insulation resistance with the ground of 1 MΩ or more in order to cope with lightning strikes, and must also satisfy a predetermined withstand voltage.

Meter sensor SE from no ringing trunk 14
When a signal calling 1 to SEn is received, in order to satisfy such a condition, the oscillator 21 is operated by the power supply 22, and the alternating current is applied to the power supply 23 via the transformer TR1 and is rectified and converted to the direct current. Obtain a power source and use it as the power source for the op amp 24.

The operation amplifier 24 is a buffer amplifier so that it has a high impedance with respect to the office lines L1 and L2.
The signal from 2 is sent to the modulation circuit 26 via this operation amplifier 24.
Is applied to the demodulation circuit 27 via the transformer TR2 and is modulated by the AC signal applied from the transformer TR1 through the capacitor C1. Or R4 and op amp 25
It is amplified by the amplifier composed of and and applied to the voltage monitor 31. This voltage monitor 31 detects a signal sent from the no ringing trunk 14 to call the meter sensors SE1 to SEn, monitors the polarities of the station lines L1 and L2, and sends the result to the control circuit 50B. is doing.

Next, the operation of the control circuit 50B will be described.

The light emitting diode ED1 and the phototransistor PT1 operated by the light emission constantly monitor the usage state of the telephone T. If the hook of the telephone T is lifted, the phototransistor PT1 is turned on, so that the output 41 is output. Move from "H" to "L". At this time, if no ringing communication is performed, the input 51 of the transistor Q1 for driving the switch SW1 is set to "L", the power of the solenoid coil SL1 is turned off, and the switch SW1 is turned off. The transformer TR3 is cut off from the office lines L1 and L2, and no ringing communication is stopped.

Now, when a ringing signal is sent from the no ringing trunk 14 via the office lines L1 and L2, it is passed through the operation amplifier 24, the modulation circuit 26, the transformer TR2, the demodulation circuit 27, and the operation amplifier 25. In response to this, the voltage monitor 31 receives the station lines L1 and L2.
The polarity of and the sensor number to be connected are detected.

By the signal that specifies the sensor number from the voltage monitor 31,
For example, control circuit 5 confirms that sensor SE1 is called.
When the CPU35B detects it via 0B, the control circuit 50B sets the input terminal 51 included therein to "H" to drive the transistor Q1 by the instruction from the CPU35, and to the solenoid coil SL1 for turning on the switch SW1. Apply current to switch SW1
Turn on.

Therefore, for example, the meter sensor SE1 of the meter M1 is 2
It is connected to the office lines L1 and L2 via the line-to-four-line conversion circuit 32 and the transformer TR3. Meter / sensor SE1 is CPU (Central Processing Unit)
Sends the meter reading to the station lines L1 and L2 according to the 35B instruction.
When this data communication is completed, the switch SW1 is turned off.

Since it operates in this way, high impedance is guaranteed for the office lines L1 and L2.

[Problems to be Solved by the Invention] The conventional terminal device 16 uses the transformers TR1 and TR2 in order to keep the impedance of the station lines L1 and L2 high, and also needs the power supply 23 for operating the operation amplifier 24. Therefore, the modulation circuit 26, the demodulation circuit 27, the operation amplifier 25, the voltage monitor 31 and the like are required, which makes the circuit extremely complicated and expensive.

[Means for Solving the Problem] In order to receive a signal from the station line, an element connected to the station line that does not require external power is used.
Using a light-emitting diode that operates with the local line current and a phototransistor that receives this light emission included in the control unit that is insulated from the local line, determine the signal from the local line received by this phototransistor. , If it is determined that it requires no ringing operation, the control unit causes the light emitting diode contained therein to emit light and turns on the phototransistor connected to the local line side, and The photo-transistor is connected to a meter sensor connected via a transformer.

[Operation] The signal from the station line is also detected and the control to connect the meter / sensor from the control section to the station line is performed by light, and the circuit connected to the station line does not require an external power supply. By doing so, the circuit configuration can be simplified, and the size and cost can be reduced.

[Embodiment] FIG. 1 shows an embodiment of a terminal device 20 according to the present invention. Here, the same symbols are used for those corresponding to the constituent elements of the terminal device 16 shown in FIG. Here, the light emitting diodes ED1, ED
3, ED4, ED5, ED6, ED7 are the phototransistors PT
Optically coupled with 1, PT3, PT4, PT5, PT6, PT7.

It is now in standby mode, no current is flowing through the station lines L1 and L2, L1 is a predetermined DC voltage (battery) L2 is at ground level (earth), and the light emitting diodes ED1, ED3, ED5, ED6, ED7 is off and does not emit light, and phototransistors PT1, PT3, PT5, PT6, PT
7 and the transistors Q3 and Q5 are off, the transistor Q4 is on because the input 54 of the transistor Q4 is “H”, the light emitting diode ED4 is emitting light, and the phototransistor PT4 receives the light. It is turned on.

When the terminating exchange 13 sends out a connection control signal for calling the terminal device 20, the polarities of the office lines L1 and L2 are reversed and the office line L
1 is the ground level (ground) and L2 is the specified DC voltage (battery). Then, the direct current flows from the office line L1 to the diode D1,
It flows to the office line L2 through the constant voltage diode ZD2, the resistor R12, the light emitting diode ED7, the diode D4, and the phototransistor PT4. Here, the constant voltage diode ZD2 is for preventing the occurrence of malfunction due to the overvoltage applied to the phototransistor PT5, and the diode D3 is for protecting the light emitting diode ED7 from the reverse voltage.

When a current flows through the light emitting diode ED7, it emits light, and the light emission turns on the phototransistor PT7, and its output 47, which has been "H" until then, becomes "L". By having the control circuit 50 monitor this output 47, the CPU (central processing unit) 35 knows that the connection control signal (NRS) is being sent from the no ringing trunk 14. Then, the CPU 35 instructs the control circuit 50 to set the input 53 to "H" to turn on the transistor Q3 to cause the light emitting diode ED3 to emit light, and the phototransistor PT3 receiving the light is turned on. Here, the phototransistor PT4 remains on and PT5 remains off.

Then, the AC connection control signal (NRS) sent from the no ringing trunk 14 is transferred from the office line L1 through the diode D1 and the DC blocking capacitor C2 to the transformer TR4,
It flows through the path of diode D4, phototransistor PT4, and office line L2. Here, the AC connection control signal (NRS) flows through the diode D1 and does not pass through the route of the light emitting diode ED6, the resistor R11, the phototransistor PT3 in the ON state, and the constant voltage diode ZD1 for malfunction prevention. This is because the voltage drop of is much larger than the voltage drop of the diode D1. Here, the resistor R11 may be connected in series with the diode D2.

Therefore, when the CPU 35 detects from the output 47 that data communication is requested from the no ringing trunk 14, that is, the terminal is a terminal to which the response should be made,
The input 55 is turned from "L" to "H" to turn on the transistor Q5, causing the light emitting diode ED5 to emit light, and turning on the phototransistor PT5. At this time, the phototransistor P
T3 and PT4 remain on, and the polarities of the station lines L1 and L2 are such that L1 remains at the ground level (ground) and L2 remains at a predetermined DC voltage (battery). Then, the DC current from the office line L1 is
Via D1, two paths, photo transistor PT
5, divided into resistor R13, constant voltage diode ZD2, and resistor R12,
Both flow to the central line L2 through the light emitting diode ED7, the diode D4, and the phototransistor PT4.

Here, the path of the phototransistor PT5 and the resistor R13 is formed by the diode D1, the light emitting diode ED7, and the diode D.
It is provided to reduce the non-linear distortion of the signal due to 4, and does not affect the basic operation of the present invention.

The connection control signal (NRS), which is an alternating current superimposed on the direct current from the office line L1, flows to the office line L2 via the diode D1 and the capacitor C2, the transformer TR4, the diode D4, and the phototransistor PT4.

Therefore, the data communication path between the meter sensor such as SE1 and the no ringing trunk 14 is set up, and the CP
U35 instructs the meter sensor SE1 and the meter sensor SE1 via the transformer TR4 and the two-wire / four-wire conversion circuit 32,
Data communication is performed with the ringing trunk 14.

Here, since the direct current does not flow through the light emitting diode ED6 but flows through the ED7, the phototransistor PT6 in the control circuit 50 is off, PT7 is on, and the output 46 is "H" and the output 47 is "L". It has become.

If the data communication with the no ringing trunk 14 is completed and the polarities of the station lines L1 and L2 change, the DC current will be
2 to the central line L1 through the diode D2, the constant voltage diode ZD1, the phototransistor PT3 which is already on, the resistor R11, and the light emitting diode ED6. Then, the light emitting diode ED6 starts emitting light and the ED7 stops emitting light, so that the output 46 of the control circuit 50 is inverted to “L” and 47 is inverted to “H”. By this inversion, the CPU 35 detects that the data communication between the meter sensor SE1 and the no ringing trunk 14 has ended, and the input 53 is “L”, the input 54 is “H”, and the input 55 is “ As L ", the phototransistor PT3 is turned off, PT4 is turned on, and PT5 is turned off to return to the standby state and monitor the states of the outputs 46 and 47.

When the terminal device 20 receives a connection signal (NRS) which is an alternating current superimposed on the direct current from the station lines L1 and L2, the CPU 35 should not respond because it is a signal for calling another terminal device. That is, when it is determined that the terminal is not the terminal that should respond, the CPU 35 instructs the control circuit 50 to set the input 54 to "L" while keeping the input 53 at "H". Then, since the phototransistor PT3 remains on but PT4 turns off, it does not matter whether the phototransistor PT5 is on or off, and the station line L1 is at the ground level (ground), L2
Is a predetermined DC voltage (battery), diode D2
Is blocked by, and no current flows in the station lines L1 and L2.

When the other terminal device responds by the connection signal for calling the other terminal device and the data communication is completed, the station lines L1 and L2 are respectively inverted to the predetermined DC voltage (battery) and the ground level (ground). Since the CPU 35 can be commonly used for monitoring and controlling other terminal devices, the status of data communication between the other terminal device and the no ringing trunk 14 can be easily known.

However, when the CPU 35 does not monitor or control other terminal devices, the direct current is generated because the station lines L1 and L2 are inverted to the predetermined DC voltage (battery) and ground level (earth), respectively. The current flows from the office line L2 to the office line L1 through the diode D2, the constant voltage diode ZD1, the phototransistor PT3, the resistor R11, and the light emitting diode ED6, so that the light emitting diode ED6 that was off until then emits light, and as a result, Since the output 46 of the control circuit 50 is inverted from "H" to "L", the CPU 35 can detect the inversion of the polarities of the station lines L1 and L2.

When the telephone set T is off-hook while the terminal device 20 is operating, the light emitting diode ED1 emits light and the control circuit 50
Since the photo transistor PT1 of is turned on and its output 41 changes from “H” to “L”, the CPU 35 immediately changes the inputs 53 and 54, for example, from “H” to “L”, and the photo transistor PT1 is turned on. Turn off PT3 and PT4 to interrupt communication with the no ringing trunk 14.

[Effects of the Invention] As is apparent from the above description, according to the present invention, the structure can be made remarkably simple as compared with the conventional device, so that the reduction in size, weight and cost can be realized. Therefore, the effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a terminal device according to the present invention, FIG. 2 is a conceptual configuration diagram of a conventional no ringing communication system, and FIG. 3 is an operation of the conventional system shown in FIG. FIG. 4 is a flow chart showing the flow, and FIG. 4 is a circuit diagram of a conventional terminal device. 11 …… Meter reading center side device 12 …… Sending side exchange, 13 …… Reception side exchange 14 …… No ringing trunk 15 …… Meter terminal, 16,20 …… Terminal device 21 …… Oscillator, 22,23 ...... Power supply 24,25 …… Operation amplifier 26 …… Modulation circuit, 27 …… Demodulation circuit 31 …… Voltage monitor 32 …… 2-wire to 4-wire conversion circuit 35,35B …… CPU, 41,46,47… Output 50,50B Control circuit 51,53 ~ 55 Input C1, C2 ... Capacitor D1 ~ D4 ... Diode ED1, ED3 ~ ED7 ... Light emitting diode L1, L2 ... Station line PT1, PT3 ~ PT7 …… Phototransistors Q1, Q3 to Q5 …… Transistors R1 to R4, R11 to R13 …… Resistors SE1 to SEn …… Meter / sensor SL1 …… Solenoid coil SW1 …… Switch, T …… Telephones TR1 to TR4… … Transformers ZD1, ZD2… Constant voltage diodes.

Claims (1)

[Claims] 1. A station including a first light emitting element (ED6) and a first light receiving switch element (PT3) as a series element for one station line (L1) capable of passing only a station line current in a predetermined direction. Polarity detection means for detecting the polarity of the line, and first diode means (D1) connected in parallel to the polarity detection means for flowing the local line current in the direction opposite to the local line current in the predetermined direction. And is connected in series to the first diode means to transmit an AC signal for no ringing communication contained in the station line current from the primary side to the secondary side, and applied from the secondary side. The transformer means (TR4, C2) for transmitting the alternating current signal to the primary side and superimposing it on the station line current, and the direct current of the station line current from the first diode means is flowed to At least resistance (R12) and second light emission for detecting the presence or absence A direct current detecting means for detecting a direct current from the first diode means at the time of no ringing communication in which an element (ED7) is connected in series and connected in parallel to the transformer means; and the direct current detecting means The DC current from the transformer means and the AC signal for the communication signal from the transformer means to the other station line (L
2) a signal switch means including a second light receiving switch element (PT4) for controlling the flow to the second line, and when the reverse direction of the reverse line current is reversed, the reverse line is reversed from the other line. A second diode means (D2) for causing a station line current having a predetermined direction to flow to the one station line via the polarity detecting means without flowing to the signal switch means; By receiving light from each of the second light emitting elements, monitoring the state of the local line current, and emitting light to each of the first and second light receiving switch elements, the first light receiving switch element is on standby during communication. (PT3) is turned off, the second light receiving switch element (PT4) is turned on, and the local line current from the reverse direction from the first diode means (D1) is supplied to the first direct current detecting means of the direct current detecting means. It is detected by the light emission of the 2nd light emitting element (ED7). When the transformer means (TR4, C2) detects from the AC signal for the no-ringing communication that the terminal is a response terminal, the communication is started, and the terminal is a response terminal that should respond. When judged, the second light receiving switch element (PT4) is kept on and the first light receiving switch element (PT3) is turned on to operate the polarity detecting means to operate the first light emitting element (ED6). The polarity of the local line is detected from the extinction state of No. 1 and it is known that communication is in progress, and the first light emitting element (ED6)
The termination is detected by the emission of light or the extinction of the second light-emitting element (ED7), and the terminal is detected even though the reverse local line current is detected by the light emission of the second light-emitting element (ED7). When it is detected that the terminal is not the one to respond to, the first light receiving switch element (PT3) is turned on and the second light receiving switch element (PT4) is turned off so that another terminal (T) can respond. Then, when the end of the call is detected by the light emission of the first light emitting element (ED6), a control means (50) for controlling to return to the communication standby state and enabling no ringing communication is included. Ringing terminal equipment.