JP2919634B2 - 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 controller, and more particularly, to a limitation of a line current when a plurality of terminal network controllers are connected.

[0002]

2. Description of the Related Art Conventionally, an existing telephone line network is used,
It is possible to read measured values of a gas meter, a water meter, a power meter, and the like installed in the house without ringing the bell of the telephone in the house of the telephone user. This is a kind of an automatic data communication system in a communication service using no ringing communication, and is provided as a telemeter system.

In the above system, when transmitted from the center-side network controller, the signal appears as a change in polarity between telephone lines of the terminal network controller via a no-ringing trunk. If connection is performed ignoring this polarity, that is, if connection is made to the terminal network control device with the polarity reversed, no ringing communication will not be possible. In order to perform the no-ringing communication, the installer needs to make the connection again.

[0004] Therefore, the applicant eliminates the communication inability due to the reverse connection of the telephone line polarity, eliminates the trouble of checking the polarity at the time of installation work, eliminates the re-construction at the time of reverse connection, and ensures reliable no ringing communication and efficient communication. A terminal network controller for an automatic data communication system capable of performing installation work has been proposed (see Japanese Patent Application Laid-Open No. 2-278957).

The terminal network control device is provided with a polarity detection circuit (signal detection circuit) for detecting the polarity of the telephone line, and the polarity detection circuit is provided when the line polarity is inverted and when the line is restored. It is configured to detect that the polarity has changed even in these changes.

FIG. 5 shows an electric circuit diagram of the reciprocity detection circuit (signal detection circuit). This circuit operates as shown in FIG. 6B when a voltage change as shown in FIG. 6A is applied between the telephone lines L1 and L2.

That is, a voltage is applied to the point A by a voltage change exceeding the operating voltage of the zener diode ZD1, and the transistor Q1 is turned on. At this time, the voltage level V2 is determined by the Zener diode ZD1. Further, when the voltage between the telephone lines L1 and L2 changes and reaches the level of V1, the zener diode ZD3 turns on and the photocoupler P
C1 is also turned on, and a collector current flows through the transistor Q1 to determine the polarity inversion detection level. The output signal of the photocoupler PC1 is transmitted from the telephone line L1-L2 to a secondary-side CPU circuit (not shown) which is DC-separated, and shifts to a communication control operation. Also, when the polarity is reversed as shown in FIG. 7, the circuit of FIG. 5 operates in the same manner as described above. That is, when the line voltage is restored to -48
Starting from the V, the reverse is started, and it becomes 0V, so that it detects that it has become 36V or more. From the opposite 48V → 0V → -36V
The change of the voltage time can be detected from ΔHz to about 0.33 Hz so that the reversal of the voltage is also detected.

In FIG. 6 , a and b have a voltage of -48.
Between V and 0V, b-c are between 0V and V2, c
D is a voltage between V2 and V1, and de is a voltage between V1 and + 48V.

When a ringer signal as shown in FIG. 8 is applied to the polarity reversal detection circuit, a 16 Hz sin.
Detect waves. That is, a current flows through the diode D3 → photocoupler PC1 → zener diode ZD3 → resistor R6 → transistor Q1, and the photocoupler PC1 illuminates and activates the CPU circuit to ring the home telephone.

[0010]

However, if a plurality of terminal network controllers are installed on one telephone line,
When a ringer signal of a large voltage as shown in FIG. 8 is applied to the circuit of FIG. 5, each terminal network control device has no current limiting element, and thus consumes a large amount of current.

As described above, if the applied voltage is large, the current consumption increases substantially in proportion to the applied voltage. If the applied voltage exceeds a certain amount (V _TH ), the terminal-side telephone exchange sends a ringer signal. Will stop. That is, since the home telephone is regarded as off-hook, there is a case where the normal communication operation is deviated.

[0012] In view of the above, it is an object of the present invention to provide a terminal network control device capable of installing a plurality of terminal network control devices by suppressing an increase in telephone line current.

[0013]

Means for solving the problems according to the present invention are, as shown in FIGS. 1 to 4, a home telephone 9 connected to telephone lines L1 and L2, and no ringing installed on the terminal exchange 4 side. In a terminal network control device of an automatic data communication system which is arranged between the trunk 5 and performs data communication without ringing the home telephone 9 using the no-ringing trunk 5, the polarity inversion of the telephone lines L1 and L2 is detected. A signal detection circuit 30 for detecting the signal.
When a certain voltage or more is applied to the circuit 30 at the time of ringer
Come, the current limiting circuit 31 for limiting the telephone line current by regulating the excessive voltage, the signal detecting circuit
30 .

In the means for solving the above problems, when a signal having a large amplitude such as a ringer signal is added, the current is increasing only if the signal detecting circuit 30 does not limit the telephone line current at all. For this reason, if a plurality of terminal network control devices are installed, the current value becomes too large, and it is considered that the terminal exchange 4 has taken off hook and the transmission of the ringer signal may be stopped.

Therefore, in the present invention, the signal detection circuit 30 is provided with the current limiting circuit sections 31 and 32, so that the ringer
When the applied voltage exceeds a certain value during the operation, the current limiting circuits 31 and 32 regulate the excessive voltage applied to limit the telephone line current, so that the photocoupler PC1 does not operate.
It limits the current flowing between the telephone lines L1-L2, the current consumption is reduced, and <br/> delivery ringer signal at the terminal side switching center 4 side persists.

For this reason, the normal operation is performed during the ringer operation, and no problem occurs in using the home telephone 9. In addition, since even if a plurality of terminal network control devices are installed, they operate without consuming excessive current,
Versatility is obtained in the number of installed meters and the like, installation conditions, and the like.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(First Embodiment) FIG. 1 is an electric circuit diagram of a signal detection circuit of a terminal network control apparatus according to a first embodiment of the present invention.
1 is a block diagram showing a configuration of a data communication system to which a terminal network control device is applied.

In the data communication system of FIG.
Is a center device. The center device 19 comprises a host computer 1 and a center-side network control device (C-NC).
U) 2. The C-NCU 2 is connected to the host computer 1 via a connection line 11 and to the center-side telephone exchange 3 via a telephone line 12. Reference numeral 18 denotes a terminal device.
8 includes a terminal such as a terminal network controller (T-NCU) 6, a meter 7, a sensor 8, and a home telephone 9. The T-NCU 6 is connected to the terminal-side telephone exchange 4 via the subscriber telephone line 14. In addition, each terminal of the meter 7 or the home telephone 9 is connected to the terminal network control device 6 via the connection line 15. Further, the center-side telephone exchange 3 and the terminal-side telephone exchange 4 are mutually connected by an interoffice trunk line 13.

In the no-ringing communication system, the C-NCU 2 calls and holds the no-ringing trunk 5 according to the designation of the host computer 1. Next, after the no-ringing trunk 5 determines the reversal of the polarity of the telephone line 14, the no-ringing call signal is given to the T-NCU 6. When the T-NCU 6 detects the no-ringing call signal, the T-NCU 6 performs communication with, for example, the meter 7 or the sensor 8 without ringing the home telephone 9.

On the other hand, at the time of terminal automatic transmission, when the T-NCU 6 detects that a predetermined time has come, the T-NCU 6 automatically calls the C-NCU 2. In this case, the meter reading information in the meter 7 or the sensor 8 is transmitted to the host computer 1 via the T-NCU 6, the telephone line 14, the interoffice trunk line 13 and the telephone line 12, and the C-NCU 2. Then, the host computer 1 performs data processing such as calculation and printing of a fee based on the received information based on a predetermined program processing. As described above, the center device 19 can collect desired data when necessary.

[0022] The T-NCU6 is as described above, shall apply as to detect the polarity of the telephone line, when the polarity of the line was and recovery when inverted, detects that the polarity is changed even in the changes in each record When the telephone line voltage exceeds a certain voltage when the polarity of the telephone line is inverted, the CPU
Circuit signal detecting circuit 30 to issue a trigger signal (not shown)
It has.

That is, as shown in FIG. 1, resistors R1 and R7, a Zener diode ZD1, and a capacitor C are connected to the line L1 side.
1. The Zener diode ZD2 and the resistors R10 and R12 are connected in series, and the line L2 is connected to the other side of the resistor R12. An emitter terminal of an NPN transistor Q2 is connected to the line L1. An optical coupling element (photocoupler) PC1, zener diodes ZD3, ZD4, and a resistor R6 are connected to the collector terminal of the transistor Q2, and an NPN transistor is connected to the other side of the resistor R6. The collector terminal of the transistor Q1 is connected, and the line L2 is connected to the emitter terminal of the transistor Q1. The base terminal of the transistor Q1 is connected to a connection midpoint between the resistors R10 and R12 via a resistor R5, and the base terminal of the transistor Q2 is connected to the resistors R1 and R2.
7 is connected via a resistor R2 to a connection intermediate point. Further, a diode D2 is connected in parallel with the resistor R1, and a diode D1 is connected in parallel with the resistor R12.

If the applied voltage is large, the signal detection circuit 30 flows to the base circuit of the transistors Q1 and Q2 so as to exhibit a sufficiently low current characteristic even for a large voltage signal such as a ringer signal. Transistors Q1 and Q2 by limiting the telephone line current by bypassing the current.
Are provided.

The first current limiting circuit section 31 has a Zener diode ZD6 and a resistor R11 connected in series at a connection point between the capacitor C1 and the Zener diode ZD2 .
An NPN for current limiting is provided at a connection midpoint between the resistors R11 and R13.
The base terminal of transistor Q3 is connected. And
The emitter terminal of the current limiting transistor Q3 is connected to the line L2, and the collector terminal is connected to the transistor Q1.
And a resistor R12 connected to the line L2. Further, a diode D6 is connected in parallel to the resistor R13.

The second current limiting circuit 32 has a zener diode ZD5 and a resistor R9 connected in series at a connection midpoint between the capacitor C1 and the zener diode ZD1, and a current limiter at a connection midpoint between the resistors R9 and R8. The base terminal of NPN transistor Q4 is connected. The emitter terminal of the current limiting transistor Q4 is connected to the line L1, and the collector terminal is connected to a connection point between the resistor R2 connected to the base terminal of the transistor Q2 and the resistor R1 connected to the line L1. Have been. The resistance R
8, a diode D5 is connected in parallel.

In the signal detection circuit 30, when a no ringing signal is issued from the exchange, a voltage change (reciprocal signal) as shown in FIG. 6A is applied between the telephone lines L1 and L2. The operation as shown in B) is performed. That is, when a voltage change exceeding the operating voltage of the zener diode ZD1 occurs, the transistor Q1 turns on. The voltage level V2 at this time is determined by the Zener diode ZD1. Further, the voltage between the telephone lines L1 and L2 changes and V
1, the Zener diode ZD3 becomes O
N turns on the photocoupler PC1, and the collector current flows through the transistor Q1 to determine the polarity reversal detection level. The output signal of the photocoupler PC1 is supplied to a secondary CPU separated from the telephone lines L1-L2 in a DC manner.
It is transmitted to a circuit (not shown) and shifts to a communication control operation. In addition, the signal detection circuit 30 performs the same operation as described above even when the polarity is reversed as shown in FIG.

Thus, the polarity of the telephone line is L1-L2
In either case, the plurality of T-NCUs are L1-L2
Regardless of the location, communication using no-ringing communication is possible.

When a ringer signal for ringing the home telephone 9 is added to the signal detection circuit 30 as shown in FIG. 8, a sine wave having an effective value of 75 V and 16 Hz is detected.
That is, a current flows through the diode D3, the photocoupler PC1, the Zener diode ZD3, the resistor R6, and the transistor Q1, and the photocoupler PC1 emits light. By counting the "H" signal from the photocoupler PC1, the CPU circuit outputs a ringer signal. Is detected, the telephone line is switched and the home telephone 9 rings.

However, when a plurality of T-NCUs 6 are installed, when a large-amplitude signal such as a ringer signal shown in FIG. The current consumption increases in proportion to the applied voltage. When the applied voltage exceeds a certain amount (V _TH ), the current consumption becomes large, and the terminal-side telephone exchange 4 stops transmitting the ringer signal, assuming that the home telephone 9 is off-hook. May deviate from normal communication operation.

Therefore, in the present embodiment, the signal detection circuit 30
Current limiting circuits 31 and 32 for limiting the telephone line current are provided. When the applied voltage exceeds a certain level, the current flowing to the base circuit of the transistors Q1 and Q2 is bypassed to turn off the transistors Q1 and Q2, and the photocoupler PC1
Turn off and respond to this.

[0032] That is, V _TH in FIG. 8 where the voltage between the telephone lines L1-L2 is determined by the Zener diode ZD5 or ZD6
Is exceeded, the current limiting transistor Q3 or Q4 is turned on to stop the base current of the transistors Q1 and Q2 from flowing. As a result, the photocoupler PC1 does not operate, and the flow of current between the lines L1 and L2 is limited. for that reason,
The current consumption is small, and the terminal-side exchange 4 continues to transmit the ringer signal. The transistor Q
Even if the base current of 1 to Q4 is an extremely small value, the circuit operation may be allowed.

Accordingly, the T-NCU including the circuit of FIG.
If a plurality of 6 are used, the collector current flowing through the transistors Q1 and Q2 is limited when the applied voltage becomes large.
At the time of the ringer operation, the normal normal operation is performed, and no problem occurs in using the home telephone 9.

(Second Embodiment) FIG. 3 is an electric circuit diagram of a signal detection circuit according to a terminal network control device of a second embodiment of the present invention.

As shown, in the present embodiment, the first current limiting circuit 31 is provided between the line L2 and the intermediate point between the connection between the transistor Q1 and the resistor R5 and the current limiting zener diode ZD.
5, the diode D5 is connected, and the second current limiting circuit 32
Is connected to the connection midpoint between the transistor Q2 and the resistor R2 and the line L.
1, a current limiting zener diode ZD6 and a diode D6 are connected to form a constant current circuit for limiting the current flowing through the transistor Q1 or Q2.

In the above configuration, the current flowing through the transistor Q1 or Q2 is
D5 or ZD6 and resistor R7 or R8. Therefore, if these values are calculated as appropriate values from the operating conditions of the photocoupler PC and the multiple installation conditions of the T-NCU 6, the current can be reduced even for a large amplitude voltage at the time of ringer. Therefore, the home telephone operates normally during the ringer operation.

The diode D5 or D6 is for matching the temperature characteristics with the transistor Q1 or Q2, and functions to bring the temperature characteristics of the forward voltage of the diode closer to the temperature characteristics of the DC base voltage of the transistor.

(Third Embodiment) FIG. 4 is an electric circuit diagram of a signal detection circuit of a terminal network control apparatus according to a third embodiment of the present invention.

As shown in the figure, in the present embodiment, the current limiting circuit units 31 and 32 have current limiting constant current diodes CD1 and CD2 inserted into the emitters of the transistors Q1 and Q2, respectively.

In the above configuration, since the collector current of the transistor Q1 or Q2 is suppressed to a constant current value by the current limiting constant current diode CD1 or CD2, the telephone operates normally even at the time of the ringer signal.

When a ringer signal is input as shown in FIG. 8, the photocoupler PC1 operates at the voltage value of V _TH . Since this signal has a period of 16 to 20 Hz and has a sufficiently low speed when viewed from the operation of the microcomputer, it is possible to detect the presence or absence of a ringer signal by counting this signal.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

[0043]

As is apparent from the above description, according to the present invention, regardless of the polarity of the telephone line, L1-L2, or where a plurality of terminal network controllers are installed in either L1-L2. Communication with no ringing communication is possible, and when multiple terminal network controllers are installed,
Which of L1-L2 is the large applied voltage
In the current limiting circuit that operates in both polarities even if
Control and apply the signal to the signal detection circuit during ringer operation.
To reduce the ringer signal.
Ensure that the home telephone always operates normally without interruption.
Door is Ru can.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a signal detection circuit of a terminal network control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a data communication system to which a terminal network control device is applied.

FIG. 3 is an electric circuit diagram of a signal detection circuit of a terminal network control device according to a second embodiment of the present invention.

FIG. 4 is an electric circuit diagram of a signal detection circuit of a terminal network control device according to a third embodiment of the present invention.

FIG. 5 is an electric circuit diagram of a signal detection circuit of a conventional terminal network control device.

FIG. 6 is a timing chart illustrating the operation of the signal detection circuit.

FIG. 7 is a diagram showing a waveform at the time of no ringing corresponding to the case where the polarity is opposite to that of FIG. 6 (A).

FIG. 8 is a voltage waveform diagram of a ringer signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host computer 2 Center side network control unit (C-NCU) 3 Center side telephone exchange 4 Terminal side network telephone exchange 5 No ringing trunk 6 Terminal network control unit (T-NCU) 7 Meter 8 Sensor 9 Home telephone 11 Connection line DESCRIPTION OF SYMBOLS 12 Telephone line 13 Inter-office trunk line 14 Subscriber telephone line 15 Connection line 18 Terminal device 19 Center device 30 Signal detection circuit 31, 32 Current limiting circuit part C1 Capacitor CD1, CD2 Constant current diode D1 to D6 Diode L1, L2 Line PC1 Photocoupler Q1 to Q4 NPN transistor R1 to R13 Resistance ZD1 to ZD6 Zener diode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-220850 (JP, A) JP-A-2-70165 (JP, A) JP-A 62-43979 (JP, A) JP-A 63-439 277423 (JP, A) Japanese Utility Model 1-90240 (JP, U) (58) Fields studied (Int. Cl. ⁶ , DB name) H04M 11/00 H04Q 9/00

Claims (1)

(57) [Claims] 1. A home telephone connected to a telephone line and a no-ringing trunk installed at a terminal-side exchange, and performing data communication without ringing the home telephone using the no-ringing trunk. In a terminal network control device of an automatic data communication system, a signal detection circuit for detecting polarity reversal of the telephone line is provided, and when a certain voltage or more is applied to the signal detection circuit at the time of ringer, excessive voltage is regulated. A terminal network control device, wherein a current limiting circuit unit operating in both polarities for limiting a telephone line current is provided in the signal detection circuit.