JP3057915B2 - Terminal network controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal network control device for detecting an incoming signal or a polarity reversal signal from a telephone line for performing data communication originating from a terminal or performing data communication based on no-ringing reception connected to the telephone line. It is.

[0002]

2. Description of the Related Art As shown in FIG. 1, a conventional terminal network control device 1 is connected to a telephone line 2 and a telephone 3, and is connected to the telephone line 2 to detect an off-hook of the telephone 3. A polarity reversal detection unit 5 for detecting polarity reversal and polarity recovery of the telephone line 2, an incoming detection unit 6 connected to the telephone line 2 for detecting an incoming signal from the telephone line 2, and connected to the telephone line 2. And a control unit that opens and closes a DC circuit and transmits / receives data, receives signals from an off-hook detection unit 4, a polarity inversion detection unit 5, and an incoming call detection unit 6 and controls the data transmission / reception unit 7. And a unit 8.

This terminal network control device 1 is a terminal network control device for performing automatic meter reading of a gas meter or a water meter. For this reason, a general telephone service is used when calling a terminal, and a no-ringing communication service of NTT is used when receiving a call.

[0004] First, the operation when the terminal network control device 1 makes a terminal call using a general telephone service will be described. Next, when the terminal network control device 1 makes a no ringing call using a no ringing communication service. Will be described.

When the terminal network control device 1 starts calling, the control section 8 confirms that the telephone line 2 is not in use and is idle, and then shifts to a selection signal transmitting operation. When the telephone line 2 is idle, it means that 1) the telephone 3 is not used and 2) no incoming signal from the telephone line 2 has arrived. In order to confirm the above 1) and 2), the control unit 8 confirms input signals from the off-hook detection unit 4 and the incoming call detection unit 6. If the telephone line 2 is not empty, the process waits until the telephone line 2 becomes empty, and if it is empty, the operation shifts to a selection signal transmitting operation. When transmitting the selection signal, the control unit 8 controls the data transmission / reception unit 7 to close the telephone line 2 and confirms that three seconds specified in the technical standard of the terminal network control device have passed, and then transmits the selection signal. Start sending. When the connection with the destination terminal is completed, the control unit 8 controls the data transmitting / receiving unit 7 to start data communication. On the other hand, at the end of the data communication, the control unit 8 controls the data transmitting / receiving unit 7 to open the telephone line 2 and then returns to the standby state.

Next, the connection sequence of the no-ringing communication service will be described, and the operation of each unit when the terminal network control device performs the no-ringing incoming call will be described. When you receive a call using the no-ringing communication service,
First, the polarity of the telephone line is reversed. A polarity inversion signal arrives, and then an NRS paging signal, which is a paging signal of the terminal network controller, comes from the telephone line 2. Upon receiving the NRS call signal and confirming that the terminal is called, the terminal network control device 1 transmits a response signal (ANS signal) to the telephone line 2. When the no-ringing trunk (not shown) receives the response signal transmitted by the terminal network control device 1, the connection with the destination terminal is completed, and the data communication becomes possible. When the data communication between the terminal network control device 1 and the destination terminal is completed, the polarity of the telephone line 2 is reversed again (called polarity recovery).
The link with the destination terminal is released. The operation of each unit when no-ringing is received is as follows. When the polarity of the telephone line 2 is inverted, the polarity inversion detecting unit 5 detects the polarity inversion, and the control unit 8 receives a detection signal from the polarity inversion detecting unit 5. The control unit 8 that has received the polarity inversion detection signal controls the DC circuit of the data transmission / reception unit 7 to be in a state where the NRS signal can be received. Next, when an NRS signal arrives from the telephone line 2, the data transmission / reception unit 7 receives and decodes the NRS signal. The decoded signal is input to the control unit 8, and when the decoded signal matches the preset calling signal of the own terminal, the control unit 8 controls the data transmitting / receiving unit 7 and sends out a response signal. The transmission of the response signal (ANS signal) establishes a link with the destination terminal and enables data communication. When receiving the termination message during communication with the destination terminal, the control unit 8 controls the data transmission / reception unit 7 to release the line and return to the standby state.

FIG. 5 shows a specific circuit configuration of the polarity determination detecting section 5 and the incoming call detecting section 6 in the terminal network control apparatus 1 shown in FIG. First, a circuit configuration of the polarity reversal detecting unit 5 and the incoming call detecting unit 6 will be described with reference to FIG.
In FIG. 5, a resistor R1 of the polarity reversal detection unit 5 (component number 9, hereinafter the numbers in parentheses indicate the component numbers on the drawing),
The resistor R3 (11) is connected to a first line (hereinafter referred to as L1) and a second line (hereinafter referred to as L2) of the telephone line 2. Resistance R1 (9), resistance R2 (10), resistance R3
(11) The resistance R4 (12) is the L1 and L of the telephone line 2.
The voltage between the two is divided, and the polarity detecting transistor Q1
(13) and a resistor for applying a voltage to the base of the transistor Q2 (14), and a resistor R2 (10)
The connection point of the resistor R4 (12) is grounded. Resistance R
5 (17) and the resistor R6 (18) are each connected to the power supply voltage Vdd constituted by a battery, and the other is connected to the collectors of the current controlling transistors Q3 (15) and Q4 (16). It is a pull-up resistor, and the transistors Q3 (15) and Q4
The collector and base of (16) are connected to the control unit 8, and the emitters are transistors Q1 (1) for polarity detection, respectively.
3), connected to the collector of the transistor Q2 (14), and connected to the transistors Q1 (13) and Q2 (1).
The emitters of 4) are both grounded.

[0008] On the other hand, the incoming call detection unit 7 detects the L1
Side, a diode bridge DB (21) via a capacitor C1 (19) and a resistor R7 (20) connected in series.
Is connected to the zener diode ZD1 (23) from the positive polarity side of the diode bridge DB (21) via the photodiode of the photocoupler PC1 (22), and the anode side of the zener diode ZD1 (23) is connected to the diode bridge DB (21). Is connected to the negative polarity side. Here, the Zener voltage of the Zener diode ZD1 (23) is set so as not to conduct when the polarity of the telephone line 2 is reversed, but to conduct when an incoming signal arrives.
The emitter of the phototransistor of the photocoupler PC1 (22) is grounded via a resistor R8 (24) and a capacitor C2 (25) connected in parallel, and the emitter is connected to a buffer (26) with hysteresis. Have been.

Next, the circuit operation of the incoming call detecting section 6 when an incoming signal arrives from the telephone line 2 will be described. When an incoming signal arrives, the incoming signal is superimposed on the DC voltage of the line after the polarity is inverted and arrives. The incoming signal is an AC signal having a frequency of 16 Hz and an effective value voltage of 75 V. When the incoming signal arrives, the incoming detector 6 conducts the zener diode ZD1 (23) whenever the voltage of the incoming signal becomes equal to or higher than the zener voltage of the zener diode ZD1 (23).
The photocoupler PC1 (22) emits light. Photocoupler PC
Since the capacitor C2 (25) is connected in parallel with the resistor R8 (24) to the phototransistor 1 (22), if the incoming signal arrives even if the photocoupler PC1 (22) is off, the output signal Does not fall below the threshold voltage of the buffer 26 with hysteresis, and the output of the incoming call detector 6 remains high.

On the other hand, when the polarity inversion signal arrives from the telephone line 2, the circuit operation of the polarity judgment detection unit 5 is as follows. In FIG. 5, the control unit 8 first turns on both the current limiting transistor Q3 (15) and the transistor Q4 (16) in the initial state. In this state, for example, +48 V and 0 V are applied to L2 and L1, respectively.
Is applied, when a voltage of +48 V is applied to the resistors R1 (9) and R2 (10), the voltage of + 48V is divided by the resistors R1 (9) and R2 (10) and the transistor Q1 ( 13) is turned on. On the other hand, the base potential of the transistor Q2 (14) is at the ground potential, and is therefore off. Therefore, the current path only includes the power supply voltage Vdd → the resistor R5 (17) → the transistor Q3 (15) → the transistor Q1 (13) → GND. The control unit 8 can detect that the potential on the L1 side of the telephone line 2 is higher than the potential on the L2 side when the collector potential of the transistor Q3 (15) becomes low level. When detecting that the L1 side of the telephone line 2 has a higher potential than the L2 side, the control unit 8 turns off the current control transistor Q3 (15) to prevent current consumption. However, at this time, the transistor Q4 (16) is not turned off so that the polarity inversion of the telephone line 2 can be detected.

In the polarity inversion waiting state, when the polarity of the telephone line 2 is inverted, the voltage applied between L1 and L2 is divided by the resistors R3 (11) and R4 (12), and the divided voltage is applied. Is applied to the base of the transistor Q2 (14) to turn on the transistor Q2 (14). Therefore, the current path is from the power supply voltage Vdd to the resistor R6
(18) → Transistor Q4 (16) → Transistor Q
2 (14) → only GND. The control unit 8 can detect that the potential of the L2 side of the telephone line 2 has become higher than the potential of the L1 side by setting the collector potential of the transistor Q4 (16) to the low level. When the control unit 8 detects that the L2 side of the telephone line 2 has a higher potential than the L1 side,
Turning off the current control transistor Q4 (16) prevents current from being consumed and turns on the transistor Q3 (15) so that the inversion of the polarity of the telephone line 2 can be detected. Thus, in order to reduce the current consumption of the terminal network control device 1 composed of the battery power supply, the current flows only when the polarity is reversed.

By the way, the technical standard of a terminal network control device defines a DC resistance value between lines in a standby state.
Ω or more must be secured. Therefore, the resistor R1 (9) and the resistor R connected between L1 and L2 of the telephone line 2
2 (10), resistors R3 (11) and R4 (14) use high resistance so as to satisfy this standard.

[0013]

However, the above-mentioned conventional configuration has the following problems. 1) Since the polarity of the telephone line is detected by using a high resistance, the polarity inversion is easily erroneously detected due to external radio noise or the like. 2) Since the ground is common to the telephone line side and the control side,
Weak against surges such as lightning. 3) The control for detecting the polarity inversion is complicated.

The present invention solves the above-mentioned problems, and enables separation of a telephone line and ground, is strong against radio wave noise and lightning surge, has low current consumption, and is simple in control of polarity inversion detection and incoming call detection. It is an object of the present invention to provide a terminal network control device capable of performing such operations.

[0015]

In order to achieve the above object, a terminal network control device according to the present invention, which is connected to a telephone line, detects a voltage when a potential of a first line is higher than that of a second line of the telephone line. A first voltage holding unit for holding, and a second voltage holding unit for holding a voltage when the potential of the second line is higher than the first line of the telephone line and connected in series with the first voltage holding unit And a threshold for generating a predetermined threshold voltage for detecting a voltage between both ends of the first voltage holding unit and the second voltage holding unit connected in series.
Transmits output signal by optical coupling
A voltage detector, and the first signal based on an output signal of the voltage detector.
When the voltage between both ends of the voltage holding unit and the second voltage holding unit is
The time over the threshold voltage of the threshold voltage generator
It is provided with a control unit that makes a determination and determines whether the polarity is inverted or an incoming signal .

[0016]

According to the present invention, the first voltage holding section holds the voltage when the potential of the first line is higher than the second line of the telephone line, and is connected in series with the first voltage holding section. The second voltage holding unit holds the voltage when the potential of the second line is higher than the first line of the telephone line, and the first voltage holding unit and the second voltage holding unit are connected in series with the voltage detecting unit. The voltage at both ends of the voltage holding section is compared with the threshold voltage,
By determining the length of time you have
The incoming polarity inversion signal and the incoming signal are determined.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, the off-hook detection unit 4 and the data transmission / reception unit 7 are components having the same functions as those of the conventional example, and thus description thereof is omitted. In addition, the terminal transmission operation and the no-ringing reception operation of the terminal network control device 27 are the same as those in the conventional example, and the description is omitted. Hereinafter, only the block for detecting the polarity inversion signal and the incoming signal from the telephone line 2 will be described.

The terminal network control device 27 shown in FIG. 1 is connected to the off-hook detection unit 4, the data transmission / reception unit 7, and the telephone line 2 to hold the voltage when the potential of L1 is higher than L2 of the telephone line 2 when L1 is higher than L2. 1 and the L of the telephone line 2
A second voltage holding unit 29 that holds a voltage when the potential of L2 is higher than 1 and is connected in series with the first voltage holding unit 28
A voltage detecting unit 30 connected to both ends of a first voltage holding unit 28 and a second voltage holding unit 29 connected in series for detecting a voltage between A and B; The control unit 31 controls the data transmission / reception unit 7 using a signal from the detection unit 30 as an input signal.

FIG. 2 shows the first voltage holding unit 28 in FIG.
3 shows an example of a specific circuit configuration of the second voltage holding unit 29 and the voltage detection unit 30. FIG. 3 is a diagram showing voltage waveforms of each unit when a polarity inversion signal and an incoming signal arrive from the telephone line 2. In FIG. 2, the first voltage holding unit 28 includes a capacitor C3 (32) for holding a voltage when the potential of L1 of the telephone line is higher than the potential of L2, and a diode D1 (34) for preventing discharge. The second voltage holding unit 29 is configured to hold a voltage when the potential of L2 of the telephone line 2 is higher than the potential of L1.
And a diode D2 (35) for preventing discharge. The voltage detector 30 detects a voltage between A and B , and is a zener diode ZD2 which is a threshold voltage generator provided to conduct at a predetermined threshold voltage or more.
(36), a current limiting resistor R9 (37), and an optical coupling photocoupler PC2 (38) for detecting that the Zener diode ZD2 (36) is conductive are connected in series. The emitter of the photocoupler PC2 (38) is connected to the circuit ground via the resistor R10 (39). The output signal OUT of the voltage detector 30 is optically coupled.
Is transmitted to the control unit.

In the above configuration, the operation when the polarity inversion signal and the incoming signal arrive from the telephone line 2 will be described.
This will be described with reference to FIGS. FIG. 3 shows, in order from the top, the voltage between the telephone lines 2 (the potential of L1 based on L2), the input voltage of the voltage detector 30 (the voltage between A and B in FIG. 3), and the voltage detector. 30 output voltages are shown. The operation when the polarity of the telephone line 2 is reversed at time t1 from the state where the potential of L2 is higher than the potential of L1 in the standby state will be described. If the potential of L1 of the telephone line 2 is higher than the potential of L2 in the initial state, L1 → diode D1
A current flows through the route of (34) → the capacitor C3 (32) → L2. The first voltage holding unit 2
8, a current flows through the capacitor C3 (32), and the capacitor C3 (32) is charged until the voltage becomes about 47 V obtained by subtracting the forward voltage of the diode D1 (34) from the voltage 48V between the telephone lines 2, and the charging is completed. Then, the current stops flowing. On the other hand, in the second voltage holding unit 29, the diode D2 (35) for preventing discharge is reverse-biased and is not charged. At this time, the input voltages A and B of the voltage detection unit 30
Although the line voltage is 47 V, the Zener voltage of the Zener diode ZD2 (36) is, for example, 60 V, so that no current flows through the photocoupler PC2 (38). As a result, capacitor C3 (32) is charged to 47V and capacitor C4 (35) is in a discharged state.

When the polarity inversion occurs at time t1 in this state, the potential of L2 becomes higher than the potential of L1. First
In the voltage holding unit 28, a discharge preventing diode D1
Since current does not flow because (34) is reverse biased,
The voltage of the capacitor C3 (32) is maintained at 47V. On the other hand, in the second voltage holding unit 29, the current flows through the route of L2 → capacitor C4 (33) → diode D2 (35) → L1, so that the capacitor C4 (33) is charged up to 47V as before. As a result, as shown in FIG.
To rise. Since the input voltage of the voltage detection unit 30 becomes 60 V or more, the Zener diode ZD2 of the voltage detection unit 30
Is conducted, and the capacitors C3 (32) and C4 (33) connected in series by the loop of A → Zener diode ZD2 (36) → Resistor R9 (37) → Photocoupler PC2 (38) → B are discharged. At this time, the photocoupler P
The charged charges of the capacitor C3 (32) and the capacitor (33) flow through C2 (38), and the photocoupler PC2 (38) emits light until the discharge ends.
A current also flows through the phototransistor of C2 (38), and the output OUT of the voltage detection unit 30 becomes high for a certain period of time as shown in FIG. The control unit 31 can detect that the polarity inversion signal has arrived from the telephone line 2 by detecting that the output OUT of the voltage detection unit 31 has been in the high state for a certain period of time. When a sufficient time has elapsed from the time t1, the capacitor C4 (33) is charged to 47V this time, and the capacitor C3 (32) is discharged to 0V by its own leakage current. When the polarity inversion signal arrives at time t2 from this state, the capacitor C3 is turned on in the same manner as at time t1.
(32) and the capacitor C4 (33) are both charged, and the voltage between A and B, which is the input voltage of the voltage detector 30, is 94V.
Becomes As a result, the Zener diode ZD2 (36) of the voltage detection unit 30 conducts, and the photocoupler PC2 (38) conducts for a certain period of time until the capacitors C3 (32) and C4 (33) discharge and the voltage drops. The output OUT of the detection unit 30 is in a high state for a certain time as shown in FIG. By detecting that the output OUT of the voltage detection unit 30 has been in the high state for a certain period of time, the control unit 31 can detect that the polarity inversion signal has arrived from the telephone line 2. Also, from the viewpoint of current consumption, the current flows from the power supply Vdd of the terminal network control device 27 to the ground only for a certain time after the polarity inversion occurs, and no current is consumed in the standby state.

Next, the operation when an incoming signal arrives from the telephone line 2 at time t3 will be described. The incoming signal is an AC signal having a frequency of 16 Hz and an effective value of 75 V, and the peak voltage on one side of the AC signal is 106 V. When the AC signal arrives, the capacitor C3 (32) of the first voltage holding unit 28 is charged if the potential of L1 is higher than the potential of L2, and the capacitor C3 (32) is charged if the potential of L2 is higher than the potential of L1. The capacitor C4 (33) of the second voltage holding unit 29 is charged. In addition, since each capacitor has a diode D1 (34) and a diode D2 (35) for preventing backflow, even if one capacitor is charged, the other capacitor does not discharge. As a result, the voltage detector 3
The input voltage of 0 (the voltage between A and B) is 212 V which is twice the peak voltage 106 V on one side of the incoming signal. Therefore, the Zener diode ZD2 (36) of the voltage detection unit 30 conducts, the photocoupler PC2 (38) emits light, and the capacitor C
3 (32) and the capacitor C4 (33) discharge. However, since the AC signal of the incoming signal has arrived from the telephone line 2, the battery is immediately charged, and the voltage between A and B is maintained at 212V. Then, the output OUT of the photocoupler PC2 (38)
Maintain a high state as shown in FIG. In other words, while the incoming signal is coming from the telephone line 2, the voltage detector 3
Since the output OUT of 0 maintains a high state, the control unit 3
In No. 1, it is possible to detect that the incoming signal from the telephone line 2 is an incoming signal by confirming that the output OUT of the voltage detecting section 30 is longer than the high pulse generated at the time of polarity inversion and keeps the high state. From the viewpoint of current consumption, the current flows from the power supply Vdd of the terminal network control device 27 to the ground only when the incoming signal is coming from the telephone line, and no current is consumed in the standby state.

In the standby state, L1 and L1 of the telephone line 2
Capacitor C3 (32) or capacitor C4 between
Since the direct current is cut by (33), the direct current resistance value of 1 MΩ specified in the technical standards of the terminal network control device
I am satisfied with the above. Since the capacitors C3 (32) and C4 (33) are connected between the telephone lines 2, they also play a role of absorbing high frequency radio wave noise. On the other hand, the circuit grounds on the telephone line 2 side and the control unit 31 side are electrically insulated by the photocoupler PC2 (38).

As described above, according to the terminal network control apparatus of one embodiment of the present invention, the first voltage holding unit 28 detects the voltage when the potential of the first line of the telephone line 2 is higher than that of the second line. Hold and
A second voltage holding unit 29 connected in series with the first voltage holding unit 28 holds the voltage when the second line is higher than the first line of the telephone line 2, and the voltage detecting unit 30 connects in series. Since the polarity inversion signal and the incoming signal coming from the telephone line 2 are detected by detecting the voltage between both ends of the connected first and second voltage holding units, the telephone line 2 and the ground can be separated. As a result, there is an effect that it is possible to provide a terminal network control device which is strong against radio wave noise, lightning surge, and the like, consumes a small amount of current, and can easily detect polarity inversion detection and incoming call detection. In addition, since the polarity inversion detection unit and the incoming call detection unit, which are conventionally configured by two circuit blocks, can be integrated into one circuit block, the number of components can be reduced, and cost and mounting area can be reduced. There is also an advantageous effect.

Although the present invention has been described with respect to an example in which a polarity inversion signal or an incoming signal is detected from the telephone line 2, the present invention is not limited to the above-described embodiment, and the polarity can be changed by changing the threshold voltage of the voltage detector. It can also be used for detecting abnormal high voltage when an abnormal high voltage of 150 V or more occurs after inversion. In addition, a configuration is also conceivable in which the voltage detection unit 30 discriminates the polarity inversion signal from the incoming signal by connecting a plurality of circuits having different threshold voltages in parallel.

[0026]

As described above, according to the terminal network control device of the present invention, the first voltage holding unit holds the voltage when the potential of the first line is higher than the second line of the telephone line. A second voltage holding unit connected in series with the first voltage holding unit holds a voltage when the second line is higher than the first line of the telephone line, and the first voltage holding unit connected in series A threshold value for generating a predetermined threshold voltage by applying a voltage between both ends of the unit and the second voltage holding unit;
The voltage that transmits the output signal by optical coupling
A first voltage based on an output signal of the voltage detector and the voltage detector.
Voltage across the voltage holding unit and the second voltage holding unit
The time during which the threshold voltage of the threshold voltage generator is exceeded is determined.
It consists of a controller that determines whether the polarity is inverted or the incoming signal.
The simple configuration allows for polarity reversal detection and incoming call detection.
There on can determine, ground and a telephone line is to be separated, there is an effect that it is possible to provide a strong yet terminal network controller against radio noise and lightning surge or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of a terminal network control device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a circuit example of a first voltage holding unit, a second voltage holding unit, and a voltage detection unit of the device.

FIG. 3 is a diagram showing waveforms at various parts of the apparatus.

FIG. 4 is a block diagram of a conventional terminal network control device.

FIG. 5 is a circuit diagram of a polarity reversal detection unit and an incoming call detection unit of the device.

[Explanation of symbols]

 27 terminal network control device 28 first voltage holding unit 29 second voltage holding unit 30 voltage detection unit

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masaaki Sakata 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-52-127012 (JP, A) JP-A-62- 163446 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04M 11/00-11/10

Claims (1)

(57) [Claims] A first line connected to a telephone line for holding a voltage when a potential of a first line is higher than a second line of the telephone line;
And a second voltage holding unit that holds a voltage when the potential of the second line is higher than the first line of the telephone line and is connected in series with the first voltage holding unit; A predetermined threshold voltage is generated for detecting a voltage between both ends of the first voltage holding unit and the second voltage holding unit connected in series.
Transmits output signal by optical coupling with threshold voltage generator
A voltage detection unit that performs the operation and the output signal of the voltage detection unit.
The voltage between both ends of the first voltage holding unit and the second voltage holding unit is
When the threshold voltage of the threshold voltage generator is exceeded
A terminal network control device comprising a control unit for determining a time interval and determining whether the polarity is inverted or an incoming signal .