JPH0461542A - Terminal network controller - Google Patents

Abstract

PURPOSE:To reduce power consumption by interrupting power supply to a 1st impedance matching means in response to a prescribed signal and driving a 2nd impedance matching means with power from a communication line. CONSTITUTION:Upon the receipt of a communication connection request signal to a recording terminal equipment 9, a main control circuit 605 activates a photocoupler PC 3 and applies switching control to a part circuit 6O3b of an NRS detection circuit and a semi-loop control circuit 604 so as to be disconnected from electric connection with subscriber telephone lines 14a, 14b on the other hand and then only the circuit 603a controls semi-loop holding. Thus, only the circuit 603a keeps the impedance between the subscriber telephone lines 14a, 14b to a calculated value during the data communication period by a recording terminal equipment 9, then the main control circuit 605 is transited to the standby mode being the low power consumption mode after that.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a terminal network control device, and particularly to a terminal network control device for no-ringing communications.

[Prior Art] FIG. 2 is a block diagram showing the configuration of a data communication system to which a terminal network control device according to a conventional example and an embodiment of the present invention are applied.

In the data communication system shown in FIG.
is the host computer l and the center side network control device (C
-NCU)2. The center side network control device 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.

On the other hand, the terminal device 18 is a terminal network control unit (T-NCU)
6, a terminal such as a meter 7, a sensor 8, a recording terminal 9 for transmitting and receiving character data, and a home telephone 1
Contains 0. The terminal network control device 6 is connected to the terminal-side telephone exchange 4 via the subscriber telephone line 14. Further, each terminal from the meter 7 to the home telephone 10 is connected to the terminal network control device 6 via a connection line 15. The center-side telephone exchange 3 and the terminal-side telephone exchange 4 are interconnected by an inter-office trunk line 13.

In the no-ringing communication system, the center-side network control device 2 calls the no-ringing trunk 5 according to a command from the host computer 1 and holds it.

Next, after the no-ringing trunk 5 reverses the polarity of the subscriber telephone line 14, a no-ringing call signal (hereinafter, N
R8 signal) is given to the terminal network control device 6. When the terminal network control device 6 detects the NR8 signal, the terminal network control device 6
Communication is performed with, for example, a meter 7, a sensor 8, or a recording terminal 9 without making a sound.

On the other hand, when the terminal makes an automatic call, when the terminal network control device 6 detects that a predetermined time has arrived, the terminal network control device 6 automatically calls the center side network control device 2. In this case, the meter 7, sensor 8 or recording terminal 9
The meter reading information or character information, etc., is sent to the terminal network control device 6,
It is transmitted to the host computer l via the telephone line 14, the interoffice trunk line 13, the telephone line 12, and the center side network control device 2. The host computer 1 performs data processing such as charge calculation and printout based on the received information based on predetermined program processing.

As the NR5 signal, a single frequency signal of 2080 Hz and a mixed frequency signal including two frequency components are used, and in this system, a pushbutton (PB) signal is used.

Figure 2 shows the terminal network control device (T-
FIG. 2 is a block diagram showing the internal functional configuration of the NCU.

The terminal network control device 6 is connected to subscriber telephone lines 14a and 14b, and makes calls by itself to communicate with other terminal devices, and performs no-ringing communication. The recording terminal 9 and the home telephone 10 are connected via the terminal network control device 6 to subscriber telephone lines 14a and 14b. Further, a meter 7, a sensor 8, and the like are connected to the terminal network control device 6. Information on the meter 7, sensor 8, and recording terminal 9 is transmitted to other terminal network control devices such as the center device 19 via the terminal network control device 6 after the telephone line link is established.

This terminal network control device 6 includes a station line circuit 600.

This office line circuit 600 includes a polarity reversal detection circuit 60 connected to the subscriber telephone line 14a114b, a rectification circuit 602,
An NR5 detection circuit 603 and a half-loop control circuit 604 are included. The polarity reversal detection circuit 601 is connected to the subscriber telephone lines 14a and 14b. This polarity reversal detection circuit 601 detects reversal of the DC bias of subscriber telephone lines 14a and 14b. Further, the rectifier circuit 602 transforms the voltage of subscriber telephone lines 14a and 14b to a predetermined voltage,
Also, the AC signals on the subscriber telephone lines 14a and 14b are applied to the NR5 detection circuit 603 connected to the next stage.

The NR5 detection circuit 603 detects the subscriber telephone line 14.
When the arrival of the NR5 signal is detected from a or 14b, a half-loop holding circuit (not shown) built in the half-loop control circuit 604 connected to the next stage prevents deterioration of transmission characteristics due to impedance imbalance. Therefore, the DC and AC impedance should be set to the specified value of the predetermined technical standards (
For example, keep it at 600Ω). Below, subscriber telephone line 14a
, 14b and the terminal network control device 6, maintaining the DC and AC impedances at specified values according to technical standards is called half-loop maintenance.

Note that this half-loop holding state continues until an immediate polarity reversal (communication is completed and the line is disconnected) is detected.

The NR5 detection circuit 603 is composed of a frequency detection circuit, a filter at the preceding stage, and the like, and detects the frequency of one preset PB multiplied signal among the received frequencies. N.R.
5 detection circuit 603 provides an interrupt signal I to main control circuit 605 when detecting a predetermined frequency. This interrupt signal I
is a signal for switching the operation mode of main control circuit 605.

The main control circuit 605 is constantly supplied with power from a power supply circuit 610 that supplies power to each circuit of the terminal network control device 6. During standby, this power supply circuit 610 generates a minimum voltage sufficient to keep the main control circuit 605 in a standby state (a state in which the built-in timer continues to operate), but the control signal C1 output from the main control circuit 605 is The main control circuit 605 generates an operating mode voltage in response to the application of the voltage. In addition, the main control circuit 60
5, in response to the time measured by the timer reaching a predetermined time, shifts from the standby state to an operating mode in which an operating mode voltage is supplied, and enters a data communication state such as terminal transmission.

A reset circuit 608 resets the main control circuit 605 periodically or as needed.

The transmitting circuit 609 transmits the PB double signal, and the modem 613 connects the subscriber telephone lines 14a, 14b and the main control circuit 60.
It performs modulation and demodulation processing of signals transmitted and received to and from 5.

Interface circuits 606 and 607 couple main control circuit 605 with meter 7 and sensor 8.

The off-hook detection circuit 611 detects whether the home telephone 10 is being used when the terminal automatically makes a call.

Further, the connection switching circuit 612 connects the subscriber telephone lines 14a, 14
A connection switching operation is performed to connect the recording terminal 9 and the home telephone 10 to the terminal b. Specifically, normally, the connection switching circuit 612 connects the recording terminal 9 and the home telephone 10 to the subscriber telephone lines 14a, 14b, but when data from the meter 7 or sensor 8 is sent, the recording terminal 9
and connection of the home telephone 10 to subscriber telephone lines 14a, 1.
4b.

Next, the operation of the terminal network control device 6 shown in FIG. 2 when a no-ringing signal is received will be explained. Note that a description of the operation when a ringing signal arrives will be omitted.

First, the polarity reversal detection circuit 601 detects the subscriber telephone line 14a,
14b is detected, and if the DC bias satisfies a predetermined voltage value (for example, 48■), the main control circuit 605 enters the standby mode, which is a low power consumption mode, in response to the polarity reversal detection. to NR8 detection mode. In parallel with this, subscriber telephone line 14
The power from a and 14b is passed through the rectifier circuit 602 to the NR8
The signal is supplied to a detection circuit 603. As a result, the NR8 detection circuit 603 is activated, and it is detected whether or not one frequency signal of the predetermined PB multiplied signal is being applied to the subscriber telephone line 14a114b. When the NRS detection circuit 603 detects one predetermined frequency signal, it provides an interrupt signal I to the main control circuit 605. The main control circuit 605 controls the half-loop control circuit 604 to maintain the half-loop in response to the application of the interrupt signal ■.

A half-loop holding circuit built into the half-loop control circuit 604 maintains the DC and AC impedance at a predetermined value (for example, 600Ω) determined by technical standards until the immediate polarity reversal is detected in order to optimize the transmission characteristics. to hold. After that, after receiving a no-ringing trunk control signal (hereinafter referred to as NRTS) from the center device 19,
A circuit link is established. Thereafter, data communication is started with the center device 19 via the modem 613 in an asynchronous manner.

During this data communication, the terminal network control device 6
When a connection command to the recording terminal 9 is received from the 9 side, a recording terminal activation signal is sent out, and the recording terminal 9 is connected to the subscriber telephone lines 14a and 14b via the connection switching circuit 612. From then on, the recording terminal 9 uses the main control circuit 605.
subscriber telephone lines 14a, 14b connected independently by a connection switching circuit 612 without data communication control by
Sends text information, etc.

FIG. 4 is a circuit diagram for explaining the half-loop hold function of a conventional terminal network control device.

Next, the power supply circuit 61 in the above-described half-loop holding state
The consumption of power supplied from 0 will be explained in detail with reference to FIG.

The illustrated half-loop holding circuit is a half-loop control circuit 6
04 and a partial circuit 603b of the NR5 detection circuit 603, these circuits include a main control circuit 605 and a rectifier circuit 60.
It is composed between 2 and 2.

In the figure, a circuit 603b includes a transistor Q1 for detecting NR8, a photocoupler PCI provided for applying a bias signal to the base side of transistor Q1, bias resistors R1 and R2, and a circuit provided for matching impedance when detecting NR5. Includes resistor R3.

The half-loop control circuit 604 includes a half-loop holding transistor Q2, a photocoupler PC2 connected to the base side of the transistor Q2, and a photocoupler PC2 provided for applying a bias signal to the base side of the transistor Q2, and a bias resistor R4.
and R5, half-loop holding resistors R6, R7 and R8
, and half-loop holding capacitors CI and C2.

Further, the half-loop control circuit 604 includes the main control circuit 60
5, an amplifier circuit A1 whose driving power supply is on/off controlled by A1, a half-loop holding capacitor C5 and a half-loop holding resistor R9 connected to the input/output side of the amplifier circuit A1.
and a bias resistor R13, and further includes a bias resistor R13.
It includes a transformer TR that connects a circuit 603b to the secondary coil side and connects the amplifier circuit A1 to the secondary coil side.

As shown in the figure, the rectifier circuit 602 connects power supplied from subscriber telephone lines 14a and 14b connected to the next stage via a polarity reversal detection circuit 601 (not shown) connected to the previous stage. The detected NR3 is applied to the detected circuit 603. Here, in order to simplify the explanation, regarding the NR8 detection circuit 603, the circuit 603 which is a part of the circuit will be described.
Only b is shown. When the NR3 detection circuit 603 detects the arrival of the NR3 signal, the main control circuit 605 controls the half-loop control circuit 604 in response to this detection, and thereafter operates to maintain the half-loop.

In other words, all the circuits between the rectifier circuit 602 and the main control circuit 605 in FIG. to maintain transmission characteristics.

The details will be explained below.

In the figure, a photocoupler PCI is provided in the circuit 603b and a photocoupler PC2 is provided in the half-loop control circuit 604 to electrically isolate the subscriber telephone lines 14a, 14b and the control circuit.

The photocoupler PCI of the circuit 603b is connected to the base side of the NR3 detection transistor Q1, and controls conduction of this via the bias resistors R1 and R2. When the polarity reversal of subscriber telephone lines 14a and 14b is detected and a predetermined voltage value (for example, 48V) is supplied from the line 14 side, this photocoupler PCI responds to main control circuit 605. It is controlled “ON” by

In response to this ON operation of the photocoupler PCI, the transistor Ql becomes conductive. As a result, the main control circuit 605 changes from the standby mode of the low power consumption mode to the NR
3. Move to detection mode.

The photocoupler PC2 of the half-loop control circuit 604 is connected to the base side of the half-loop holding transistor Q2,
This is controlled to be conductive via bias resistors R4 and R5. This photocoupler PC2 is controlled "ON" by the main control circuit 605 in response to reception of the selection number (PB double signal) of the terminal network control device 6. A driving voltage is also applied to the circuit A1. In response to this "ON" operation of the photocoupler PC2, the transistor Q2 becomes conductive.

As a result, the amplifier circuit A1 connected to the secondary coil side of the transformer TR becomes conductive.

By the above circuit operation, the circuit 603b and the half-loop control circuit 604 are connected to the main control circuit 605 and the subscriber telephone line 14a.
, 14b, a half-loop holding state is established.

During this half-loop holding period, the current supplied from power supply circuit 610 is consumed in photocouplers PCI and PC2, amplifier circuit A1, and main control circuit 605. This current consumption state continues until the next polarity reversal, that is, the detection of a polarity reversal caused by line disconnection at the end of the data communication.

FIG. 5 is a diagram for explaining the no-ringing communication procedure between the center device and the recording terminal in the data communication system shown in FIG. 2 above.

Next, the no-ringing communication operation between the center device and the recording terminal will be explained with reference to FIGS. 2 to 5.

At ■ in Figure 5, the center device 19 side makes a call and sends an NRS
When the signal arrives at the terminal-side telephone exchange 4, the no-ringing trunk 5 reverses the polarity of the telephone lines 14a, 14b connected to the terminal network control device 6, and sends out a PB double signal for calling the terminal network control device 6. Terminal network control device 6
When the main control circuit 605 detects the arrival of this PB signal,
The transition from the standby mode of the low power consumption mode to the operating mode results in a half-loop holding state.
For example, a PB double signal corresponding to "#" is transmitted from 09 and sent to the telephone line 14.

The above-mentioned PB double signal #'' is received at the center side telephone exchange 3, and the polarity of the telephone line 12 connected to the center side network control device 2 is inverted.

As a result, a line link is established between the center device 19 side and the terminal network control device 6. Thereafter, asynchronous data communication is performed via this established communication line.

First, at (2) in FIG. 5, a terminal selection signal (including the communication mode and terminal number) is transmitted from the center device 19 side to the terminal network control device 6. The terminal network control device 6 identifies this communication mode and terminal number and performs the following processing.

First, the terminal network control device 6 transitions to a state for processing downlink (from the center device 19 to the terminal device 18) or upstream (from the terminal device 18 to the center device 19) message according to the received communication mode, and also The connection terminal specified by the specified terminal number is set to logic "ON". That is, control is performed so that information from a designated terminal among the meter 7, sensor 8, and recording terminal 9 is sent to the telephone line 14.

For example, when a terminal selection signal requesting communication with the recording terminal 9 is received, the main control circuit 605 identifies the content of this signal, and after receiving the terminal selection signal, approximately 1000
For example, 1650Hz (200msec) + 1850Hz to the recording terminal 9 within ~101510l5
(400msec)+1650Hz (200msec
) sends a start signal.

As a result, the terminal network control device 6 enters a half-loop holding state from (■) onward in FIG. Data communication is performed in an asynchronous manner.

When the data communication is completed, a line disconnection signal is sent from the calling side, ie, the center equipment 19, at (3) in FIG. The polarity of the existing subscriber telephone lines 14a and 14b is reversed and restored. By this polarity reversal, the half-loop holding state of the terminal network control device 6 is released, and the main control circuit 605 can return from the operation mode to the standby mode, which is a low power consumption mode.

[Problem to be Solved by the Invention] Now, even when terminal network control devices communicate data with each other via a no-ringing line, it is possible to maintain the transmission characteristics of normal ringing communication and achieve an optimal data communication situation. is important.

To this end, as described above, the terminal network control devices maintain the DC and AC impedances of the lines connected to each other at prescribed values of technical standards, thereby achieving impedance matching and maintaining transmission characteristics.

In this no-ringing communication state, one terminal network control device selects and communicates with the other terminal network control device itself or any terminal such as a meter, sensor, or recording terminal connected thereto. At this time, if there is a line connection request to the recording terminal connected to the terminal network control device and the connection is switched to the recording terminal in response to this request, the terminal network to which this recording terminal is connected The control device itself is not involved in this communication and only maintains the impedance matching. However, data communication using a recording terminal is
The content of the communication is text information, etc., and the amount of information is extremely large, so the communication time per communication tends to be longer than that of data communication of meters or sensors.

As a result, although the terminal network control device is unrelated to this data communication, it continues to operate in the power-consuming operation mode explained in Figure 4 for a long time. There was a problem in that a large amount of power was consumed by the batteries used, and batteries had to be replaced frequently.

Therefore, an object of the present invention is to provide a terminal network side 8 device that consumes less power.

[Means for Solving the Problems] A terminal network control device according to the present invention is a terminal network control device that performs no-ringing communication in response to a no-ringing paging signal given via a communication line. Specifically, a terminal network control means, a first detection means for detecting a no-ringing paging signal given via the communication line, and a predetermined signal given subsequent to the no-ringing paging signal given via the communication line. a second detection means for detecting; a first impedance matching means that is supplied with power in response to the detection output of the first detection means and impedance-matches the communication line and the terminal network control means;
power supply cutoff means for cutting off the power supply to the first impedance matching means in response to the detection output of the second detection means; A second impedance matching means is driven by electric power supplied from a communication line to perform impedance matching between the communication line and the terminal network control means.

[Operation] Since the terminal network control device according to the present invention is configured as described above, when the first detection means detects a no-ringing paging signal, the first impedance matching means connects the communication line and the terminal network control means. are impedance matched.

Thereafter, when the second detection means detects the arrival of a predetermined signal given subsequent to the no-ringing call signal, the power supply cutoff means cuts off the power supply to the first impedance matching means, and the second detection means cuts off the power supply to the first impedance matching means. The impedance matching means is driven by the power supplied from the communication line and operates to impedance match the communication line and the terminal network control means.

That is, when the arrival of a predetermined signal following a no-ringing paging signal applied via a communication line is detected, the power supply to the first impedance matching means is immediately cut off, and the second impedance matching means receives power from the communication line. It is driven by the electric power generated. Therefore, power consumption in the device is reduced, and transmission characteristics in data communication are maintained by the first and second impedance matching means.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The configuration of the data communication system according to this embodiment, the functional configuration of the terminal network control device, and the no-ringing communication procedure between the center device side and the recording terminal device are the same as those shown in FIGS. 2, 3, and 5 described above. Therefore, detailed explanations regarding these will be omitted.

FIG. 1 is a circuit diagram for explaining a half-loop holding function of a terminal network control device according to an embodiment of the present invention.

Comparing the half-loop holding circuit according to the embodiment of the present invention shown in FIG. 1 with the conventional half-loop holding circuit shown in FIG. 4, the difference is that the circuit shown in FIG. Half-loop holding circuit 60 that operates in the recording terminal communication state
3a is additionally provided. This half-loop holding circuit 603a is a circuit provided to maintain a half-loop state during the no-ringing communication period of the recording terminal 9 of the terminal network control device 6 in which this circuit is adopted.

The half-loop holding circuit according to an embodiment of the present invention includes a half-loop holding circuit 603a that operates in the recording terminal communication state, and a partial circuit 60 of the NR8 detection circuit, as shown in the figure.
3b and a half-loop control circuit 604, these circuits are configured between the main control circuit 605 and the rectifier circuit 602.

In the figure, a half-loop holding circuit 603a that operates in the recording terminal communication state includes half-loop holding transistors Q3 and Q4 during recording terminal communication. A photocoupler PC3 is connected to the base side of the transistor Q3, and the conduction of the transistor Q3 is controlled by the on/off operation of the photocoupler PC3. Also, bias resistors R18 and R19 are connected to the base side of the transistor Q4.
A series circuit consisting of a Zener diode ZD1 and a Zener diode ZD1 for line voltage determination is connected, and the collector current of the transistor Q3 is applied to the base side of the transistor Q4 via the Zener diode ZD1. Therefore, transistor Q4 is a 0N10FF of Zener diode ZD1.
Conduction is controlled according to the state. Circuit 603a further includes biasing resistors R14 and R15, half-loop holding resistors R16 and R17, and half-loop holding capacitor C4.

Since the partial circuit 603b of the NR3 detection circuit and the half-loop control circuit 604 are similar to the conventional circuit explained in FIG. 4, detailed explanation of the circuit configuration thereof will be omitted.

As shown in the figure, the rectifier circuit 602 receives power supplied from subscriber telephone lines 14a and 14b connected through a polarity reversal detection circuit 601 (not shown) connected to the front stage of the rectifier circuit 602 through a circuit 603a to an NR8. It is applied to the detection circuit 603. Here, to simplify the explanation, the NRS detection circuit 603 will be referred to as a partial circuit 603 of the NR8 detection circuit.
Only b is shown.

When the NR5 detection circuit 603 detects the arrival of the NRS signal, in response to this detection, the main control circuit 605 controls the half-loop control circuit 604 to operate to maintain the half-loop as in the conventional art.

After that, when the main control circuit 605 receives a communication connection request signal with the recording terminal 9, it makes the photocoupler PC3 conductive, and connects the partial circuit 603b of the NR8 detection circuit and the half loop control circuit 604 to the subscriber telephone lines 14a, 14b. Switching control is performed so as to disconnect from the electrical connection with the circuit 603a, and from then on, control is performed so that a half loop is maintained only by the circuit 603a. As a result, during the period of data communication by the recording terminal 9, the impedance between the subscriber telephone lines 14a and 14b can be maintained at the standard value (600Ω) according to technical standards using only the circuit 603a. can enter standby mode, a low power consumption mode.

The details will be explained below with reference to FIGS. 1 to 3 and 5.

In FIG. 1, in order to electrically isolate the subscriber telephone lines 14a, 14b side and the control circuit side, a photocoupler PC3 is installed in the circuit 603a, a photocoupler PCI is installed in the circuit 603b,
Each half-loop control circuit 604 is provided with a photocoupler PC2.

The photocoupler PCI of the circuit 603b is connected to the base side of the NR3 detection transistor Q1, and controls the conduction of this transistor Q1 via the bias resistors R1 and R2. This photocoupler PCI is connected to subscriber telephone lines 14a and 1 by the polarity reversal detection circuit 601 at
When the polarity reversal of 4b is detected and it is also detected that a predetermined voltage value (for example 48■) is being supplied from the line 14 side, this detection output is given to the main control circuit 605. The main control circuit 605
“ON” control.This photocoupler PCI “ON”
Depending on the operation, transistor Q1 becomes conductive. Therefore, main control circuit 605 can shift from standby mode, which is a low power consumption mode, to NR3 detection mode.

A photocoupler PC2 of the half-loop control circuit 604 is connected to the base side of the half-loop holding transistor Q2, and controls conduction of this transistor Q2 via bias resistors R4 and R5. In this photocoupler PC2, the main control circuit 605 selects the selection number (P
In response to receiving the B-fold signal, the main control circuit 605
It is controlled “ON” by At this time, the main control circuit 60
5 applies a driving voltage to the amplifier circuit A1. In response to the “ON” operation of this photocoupler PC2, the transistor Q2
becomes conductive. As a result, the amplifier circuit A1 connected to the secondary coil side of the transformer TR becomes conductive.

Through the circuit operation described above, the circuit 603b and the half-loop control circuit 604 are electrically connected between the main control circuit 605 and the subscriber telephone lines 14a and 14b, thereby establishing a half-loop state. Thereafter, asynchronous data communication is performed.

5, when the main control circuit 605 detects the reception of a terminal selection signal requesting communication with the recording terminal 9 via the subscriber telephone lines 14a, 14b, the photocoupler PCI and PC2 are controlled "OFF" to turn transistors Q1 and Q2 into a cutoff state, and photocoupler PCB is controlled "ON" to turn transistor Q3 into a conductive state.At this time, a driving voltage is applied to amplifier circuit A1. Since it is not necessary, the main control circuit 605 connects the photocoupler P for a short period of time to provide the bias signal necessary for the conduction to the base side of the transistor Q2.
By controlling C3 to ON, it is possible to immediately return to the standby state. This is because once the photocoupler PC3 is turned on, the transistor Q3 becomes conductive, and a negative signal is applied to the base side of the transistor Q4 via the Zener diode ZDI. In other words, when the bias signal is applied to the transistor Q4, the transistor Q3 acts to bring the transistor Q3 into a deeper conduction state, so even if the photocoupler PC3 is controlled to be "OFF", the transistor Q3 remains on the base side of the transistor Q4. This is because the conductive state is maintained until the applied bias signal disappears, and the half-loop state can be maintained only by the circuit 603a.

In other words, a predetermined voltage sufficient to turn on the Zener diode ZD1 continues to be supplied between subscriber telephone lines 14a and 14b until the next polarity reversal.

As described above, since the transistors Q3 and Q4 can be maintained in the "ON" state and the half-loop state can be maintained using the current supplied from the subscriber telephone lines 14a and 14b, the power consumption of the battery on the control circuit side, that is, the power supply circuit 610 is It can be seen that it is possible to save. In this way, transistors Q3 and Q
A circuit element (resistance R1
4, R16 and capacitor C4), it is possible to maintain the impedance (600Ω) specified by the technical standards and maintain a half-loop.

Thereafter, when the communication by the recording terminal 9 ends, polarity reversal of the subscriber telephone lines 14a and 14b occurs as shown in (2) in FIG. In other words, the voltage level applied between this line 14 gradually decreases to level 0, and finally increases in the negative direction, and the polarity of subscriber telephone lines 14a and 14b is completely reversed, and the half-loop holding circuit is on the line 14 side. be separated from

As described above, after the terminal network control device 6 switches to the communication connection to the recording terminal 9, it immediately shifts to the standby mode, which is a low power consumption mode, but even if the communication time by the recording terminal 9 is long, Since impedance matching with the line 14 can be maintained by the current supplied from the subscriber telephone line 14 side, consumption of the power supply circuit 610 provided in the terminal network control device 6 is also suppressed, and the terminal network control device 6 The operational efficiency of the applied data communication system is improved.

[Effects of the Invention] As described above, according to the present invention, when the first detection means detects the arrival of a no-ringing call signal, power is supplied to the first impedance matching means,
Impedance matching between the communication line and the terminal network control means is achieved. Thereafter, when the second detection means detects the arrival of a predetermined signal following the no-ringing call signal, in response to this, the power supply to the first impedance matching means is cut off, and the first impedance matching A second impedance matching means, which replaces the means, is driven by power supplied from the communication line to maintain the impedance matching. Therefore, after detecting the predetermined signal,
The energy saving effect of the device itself can be effectively achieved.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining a half-loop holding function of a terminal network control device according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a data communication system to which a terminal network control device according to a conventional example and an embodiment of the present invention are applied. FIG. 3 is a block diagram showing the internal functional configuration of the terminal network control unit (T-NCU) shown in FIG. 2. FIG. 4 is a circuit diagram for explaining the conventional half-loop holding function. FIG. 5 is a diagram for explaining a no-ringing communication procedure between the center device and the recording terminal in the data communication system shown in FIG. In the figure, 6 is a terminal network control device, 14 is a telephone line, 6
01 is a polarity reversal detection circuit, 603a is a half-loop holding circuit that operates in the recording terminal communication state, and 603b is NR.
3 a partial circuit of the detection circuit, 604 a half loop control circuit,
605 is a main control circuit, and 610 is a power supply circuit. In each figure, the same reference numerals indicate the same or corresponding parts. Applicant Sharp Corporation (and 2 others)

Claims (1)

[Scope of Claims] A terminal network control device that performs no-ringing communication in response to a no-ringing paging signal given via a communication line, comprising: a terminal network control means; and a no-ringing paging signal given via the communication line. a first detection means for detecting; a second detection means for detecting a predetermined signal applied subsequent to a no-ringing call signal applied via the communication line; and in response to a detection output of the first detection means. first impedance matching means that is supplied with power and impedance-matches the communication line and the terminal network control means; power supply cutoff means for cutting off the power supply; and impedance matching between the communication line and the terminal network control means driven by the power supplied from the communication line in response to the detection output of the second detection means. A terminal network control device comprising: second impedance matching means.