JPS5925417B2 - line switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line switching device, and more particularly to a switching device between a dedicated line and a subscriber telephone line in data communications.

Data communications, including facsimile communications, include dedicated communications between specified subscribers using dedicated lines set up by business entities and companies, and communications between unspecified subscribers using subscribed telephone lines (public communication lines). There is a subscription communication that takes place between.

When using subscriber telephone lines, various technical standards have been established to prevent interference with telephone and other communications.
For example, when a converter is connected to a subscriber telephone line to switch between a data terminal and a main telephone, and the data terminal is installed by a private company, a line protection device PD must be connected. There are two types of dedicated lines for data transmission: long-distance dedicated lines and local dedicated lines. Direct current data transmission is possible on local dedicated lines, but high-speed transmission causes a lot of noise. , transmitted as an alternating current signal using a modulator and demodulator.

On long-distance dedicated lines, an amplifier is installed along the way to prevent signal attenuation, and a modulation/demodulation device is used to transmit AC signals. For example, in order to connect a facsimile device to a subscriber telephone line and transmit facsimile signals, the facsimile control unit is usually equipped with a communications control unit (CCU) and a modem unit (modulator/demodulator).
MODEM) and network control unit (NCU) are connected as a set to the subscriber telephone line.

The communication control unit provides an interface with the data line, converts serial bit strings on the data line from serial to parallel, provides data signal speed matching, performs error checking, detects and inserts control codes, and transmits connection confirmation and termination, etc. Perform control functions. In addition, the subscriber telephone line network control device controls the connection of the subscriber telephone exchange network, that is, starts and restores the central office exchange, sends selection signals, detects paging signals, etc., as well as switches to data communication paths and maintains loops. This device has the following functions. In addition, in order to connect the same facsimile device to a dedicated line and transmit facsimile signals, it is not possible to connect the subscriber telephone line set as is, and the network controller NC
U) 17) Instead, control the connection of the dedicated line, that is, sending out the selection signal, detecting the paging signal, switching to the data communication path,
It is also necessary to connect a line control unit (LCU) that has functions such as switching with a leased line telephone, and this must be built into the set.

On the other hand, in a subscriber telephone line facsimile equipped with a network control unit (NCU), this method is used to switch the line to a dedicated line. As shown in Figure 1, there are cases where the facsimile's built-in modem and external modem are switched and connected to a dedicated line, and as shown in Figure 2, when the facsimile's internal network control unit (NCU) and the modem are switched. In some cases, the data line from the modem is switched between the subscriber telephone circuit and the leased line using an external switching device.

That is, in FIG. 1, in the facsimile device 10, the facsimile control unit 5 is connected to the subscriber telephone line LN via the communication control unit 4, model switching control unit 3, modem device 2, and network control device 1. ing. Connection to the dedicated line PL is made via an external modulation/demodulation device 6, and line switching is performed by switching between the built-in modulation/demodulation device 2 and the external modulation/demodulation device 6 in the modem switching control section 3. Switching control is performed manually during transmission, and is automatically switched using a code signal when a call is received from the dedicated line PL. Also,
In response to an incoming call from subscriber telephone line LN, network control device 1
Received by this phone connected to. However, in the switching method shown in FIG. 1, when switching to the dedicated line PL side, an external modulation/demodulation device 6 is required, which increases the cost accordingly.

Furthermore, analog signals are transmitted from the dedicated line PL to the modem 6, but between the modem 6 and the facsimile device 10,
Since the interface between the two is a digital signal, it is not possible to perform voice communication over a dedicated line. Usually, a time division device (TDM) is inserted after the modem 6 and a digital telephone is used to make calls. Also,
The facsimile device 10 shown in FIG. 1 is a modified facsimile device for subscriber telephone lines, in which the printed circuit board of the modem switching control section 3 is inserted, and the modem switching device 2 and the communication control section 4 are connected to each other.
It is also necessary to change the input/output wiring.

If possible, it is desirable to use the facsimile equipment for subscriber lines as is. Next, in FIG. 2, between the back of the network control device 1, that is, between the network control device 1 and the modem device 2, the data line from the modem device 2 is connected to the subscriber telephone line LN and the dedicated line by an external switching device 8. Switch and connect the PL. This switching method is used to switch between the subscriber telephone line LN and the international diesel line PL, and includes a manual switch in the external switching device 8, a hybrid coil 18 for 2-wire to 4-wire conversion, and a It is connected to an international diesel line via a transmitting facsimile signal level adjustment unit 9 and an international diesel adapter 11.

Also, when receiving a call via an international diesel line,
an automatic facsimile reception unit 12 for converting the received signal into a digital signal and displaying the incoming call on the facsimile control unit 5;
will be provided. However, if the switch in the switching device 8 is not manually switched to the dedicated line side, the automatic facsimile receiving unit 12 will not be able to receive the facsimile device 10! cannot be put into reception status.

When the switch is not switched to the leased line side, the operator of the facsimile machine 10' accepts incoming calls from the international line using the handset connected to the international diesel adapter 11, and the operator switches the switch on the panel to the leased line side. , press the receive button on the facsimile to enter reception mode. Three automatic facsimile reception units 12, signal level adjustment units 9, and switching devices 8 are combined into one set.

In this way, in the switching method shown in Fig. 2, the subscriber telephone line and the dedicated line are switched at the rear of the network control device 1, so the network control device 1 cannot be shared, and an external signal level adjustment unit is installed. 9 and a device 12 for activating reception of the facsimile device, the cost is high.

Furthermore, line switching during reception is not performed automatically, which is extremely inconvenient. It is an object of the present invention to eliminate such drawbacks and to connect a subscriber telephone line and a dedicated line to a facsimile machine by switching and connecting both lines without using separate network control devices and with a simple configuration. An object of the present invention is to provide a line switching device capable of arbitrarily switching connections when receiving or outgoing calls.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a system diagram when a facsimile device is switched and connected to a 2-wire or 4-wire dedicated line using the present invention.
FIG. 4 is a system diagram when the present invention is used to switch and connect a facsimile device to a dedicated line via an extension telephone of a private branch exchange. In the line switching device of the present invention, the interface of the dedicated line connection section differs depending on the form of the dedicated line.

In FIG. 3, a facsimile device 20 is connected to a connection point of a two- or four-line dedicated line PL via a line switching device 30 of the present invention, and the line switching device 30 switches and connects it to a subscriber telephone line LN. Facsimile device 20 for subscriber telephone line
can be connected to the dedicated line PL without any modification. Connected to the line switching device 30 are a main telephone 13 that accepts incoming calls on the subscriber telephone line LN while communicating with the leased line PL, and a leased line telephone 14 that responds by voice to incoming calls on the leased line PL while communicating with the subscriber telephone line LN. be done. In addition, the facsimile device 20
An attached telephone 7 is connected to the network control device inside. Fourth
The figure shows a case where private branch exchanges 16 are connected by a long-distance leased line PLN, and an in-band ringer 17 that converts dial pulses into in-band (in-band frequency 1900 to 2400 Hz) is inserted into the leased line. be done.

Of course, in the case of a local dedicated line, in-band ringer 1
7 is unnecessary.

When the facsimile device 20 is connected only to the dedicated line PLN via the extension telephone of the private branch exchange 16, the facsimile device 20 is directly connected to the extension telephone. On the other hand, when connecting the subscriber telephone line LN and the private line PLN by switching, the facsimile device 20 is connected to the extension telephone via the line switching device 40 of the present invention. It is also connected to the subscriber's telephone line LN via the line switching device 40. In addition, 15 is
It is an extension phone. FIG. 5 is a detailed configuration diagram of the line switching device shown in FIG. 3. The subscriber telephone line LN is normally connected to the network control device 1 of the facsimile device 20 via a line switching device 30.

Facsimile communication on the subscriber telephone line LN is carried out by a subscriber telephone line facsimile device 20 incorporating a normal MA type (manual transmission, automatic reception) network control device 1 for both transmission and reception. If the line switching device 30 fails or the power is cut off, the relay contact n'S,
Since the subscriber telephone line LN and the facsimile device 20 are connected on the normal contact side of y, facsimile communication is possible. From the PD terminal of the facsimile device 20, that is, the data output side of the modem device 2, the attenuator 26, the disconnector 21, and the line protection device (PD) 19 in the line switching device 30 are connected.
Since it is connected to the PD terminal of the facsimile device 20, that is, to the data input side of the network control device, the existing terminal of the facsimile device 20 can be used, and there is no need to modify the facsimile device 20 at all. The output level of the signal sent to the subscriber telephone line LN is adjusted by an attenuator 26. Next, when transmitting to the dedicated lines PL4W and PL2W, the dedicated line selection switch 25 of the line switching device 30
By operating the sequence control circuit 32, the relay Y. ! :． Operate NS.

When contact y switches, the line switching device 30 is switched from the modem 2 to the
The attenuator 26, the separator 21, and the protector 19 inside are released and connected to the network control device 1 through a direct path that short-circuits them, and further connects the other contact y, relay K2, contact X1, hybrid coil H1 transmission Amplifier 39, leased line attenuator 28
, a 4-wire separator 27, and a line protection device 22 to connect to the 4-wire dedicated line PL4W. In that case, the transmission level is adjusted by attenuator 28. In addition, a transmission amplifier 39, a hybrid coil H, a two-wire separator 2
3, and the 2-line dedicated line PL via the line protection device 24
Connected to 2W. At this time, the transmission level is determined by the transmission level attenuated by the hybrid H.
This is corrected by adjusting the gain of No. 9, and adjusted by the dedicated line attenuator 28 to match the line conditions of the dedicated line. In this way, a call to the 4-line or 2-line opposing leased line terminal is initiated. In this case, the line switching device 30 provides the facsimile device 20 with the same interface conditions as the subscriber telephone line LN even when the leased line is connected. When the contact Ns is switched by the operation of the relay NS, the subscriber telephone line LN is switched to the main telephone set 13, and the main telephone set 13 responds with voice to an incoming call from the subscriber telephone line LN.

Calls between subscriber telephone line LN and this telephone 13 are made via relay K.
1, while the dedicated line PL and facsimile device 20
Communication with is monitored by relay K2. When the communication of facsimile device 20 ends, relay K2 detects this and opens contact K2, and sequence control circuit 32 detects this and restores relays Y and NS. As a result, the contacts y and Ns are opened to connect the subscriber's telephone line LN and the facsimile device 20, returning to the normal state. However, if the relay K1 is operating at that time, the contact kl remains closed, so the sequence control The circuit 32 maintains the operation of the relay NS and ensures that the telephone 13 can make a call. Next, when a call is received from the leased line PL, the detector 29 detects the calling signal (two-wave frequency signal) from the opposing leased line terminal via the reception amplifier 41, so the sequence control circuit 32
Under the control of , relays Y and NS are operated to switch and connect the facsimile device 20 from the subscriber's telephone line LN to the private line PL.

That is, the contact y of the DC circuit at the front of the network control device 1 switches and connects both lines, and the contact y of the AC circuit between the modem 2 and the network control device 1 allows attenuation to be performed in the same way as during transmission. device 26, separating device 21, line protection device 1
9 to form a short circuit path. After connection, relay S
By operating G2 and sending a 16 Hz paging signal from the oscillator 31 to the facsimile device 20, the facsimile device 20 shifts to a receiving state. In addition, after connecting to the dedicated line PL and immediately before starting communication, the relay CA is operated to close the contact Ca and form a reception path. Also,
While the facsimile device 20 is communicating with the subscriber telephone line LN,
When a call arrives on the private line PL, the sequence control circuit 32 operates the relay SGl to call the private line telephone 14.
When the leased line operator off-hooks, the relay L detects this and drives the sequence control circuit 32, which operates the relay X to close the contact X and respond by voice to the opposing leased line. In addition, facsimile device 2
When a call is received from the leased line PL while 0 is communicating with the subscriber telephone line LN, and the operator is absent, the sequence control circuit 32 receives a signal from the detector 29 and the contact kl of the monitoring relay K1 is closed. It is also possible to detect this, operate relay SG3, close contact Sg3, and send a busy tone from signal generation circuit 38 to dedicated line PL. Further, the signal generation circuit 38 generates a selection signal and sends it to the dedicated line PL at the time of a call. Note that the 16 Hz calling signal is sent to either the leased line telephone 14 or the facsimile device 20 by operating either relay SGl or SG2. In this way, the line switching device 30 in FIG.
By using the network control device 1 with built-in facsimile
can be shared by the subscriber telephone line LN and the dedicated line PL, so there is no need to improve the facsimile device for the subscriber telephone line.

Further, level adjustment during transmission to subscriber telephone line LN and private line PL is performed by separate attenuators 26 and 28, and line protectors 19, 22, 24 and separators 21, 24, 2
7 can also be connected separately according to the standard. Note that the dotted connection lines of Hybrid H are points that are disconnected or connected during construction or delivery testing. FIG. 6 is a detailed configuration diagram of the line switching device shown in FIG. 4.

In this case as well, the subscriber telephone line LN is normally connected to the network control device 1 of the facsimile device 20 via the line switching device 40.
It is connected to the.

The route for communicating with subscriber telephone line LN is exactly the same as in FIG. Next, the dedicated line side (private branch exchange extension, hereinafter PB)
When transmitting via the X extension, first operate the changeover switch 25,
is driven to operate relay Y1 and switch contact y1 to connect facsimile device 20 to dedicated line PL.

That is, the line is switched and connected by the contact y1 of the DC circuit at the front of the network control device 1, and the facsimile device 2
0 PD element, that is, an attenuator 26, a divider 21, and a line protection device (PD) 1 connected to the AC circuit on the data output side of the modem device 2 and the data input side of the network control device 1.
9 is disconnected by the contact y1, and is switched and connected to the path to which the dedicated line attenuator 37, disconnector 36, and line protection device 35 are connected. However, in this case, when it is a local leased line, the short circuit path is separated by an Construction will be carried out so that signals can be transmitted via the short-circuit path without having to disconnect at the X mark when using a dedicated long-distance line. In the case of a dedicated long-distance line, level adjustment and line protection are performed within the in-band ringer 17 shown in FIG. 4, so they are not necessary on the extension side. After the facsimile device 20 is connected to the PBX extension, check the dial tone of the PBX extension using the attached telephone 7,
Perform a dial operation to call the terminal on the opposite leased line.

After the PBX sends a ring tone, communication begins when the other party is connected. During communication with the PBX extension, the contact Ns is switched by the operation of the relay NS, so that the subscriber telephone line LN is connected to the main telephone set 14, and the main telephone set 14 responds with voice to an incoming call from the subscriber telephone line LN. As in the case of FIG. 5, communications with the leased line are monitored by relay K2, and calls with subscriber telephone line LN are monitored by relay K1.

When the communication with the leased line ends, relay K2 detects this, and sequence control circuit 33 restores relay Y1 and switches and connects facsimile device 20 to subscriber telephone line LN, but relay K1 detects that a call is in progress. Relay NS while
will not be restored. Next, when a call is received from the dedicated line side (PBX extension), the 16Hz signal sent to the PBX extension
The ringing detection circuit 34 detects the ringing signal.

Here, the ring trip is not performed, but the relay Y1 is operated under the control of the sequence control circuit 33, and the contact y
1, the facsimile device 20 is switched and connected from the subscriber telephone line LN to the dedicated line. After switching and connecting, the 16 Hz calling signal from the PBX extension is sent to the facsimile device 20 as is. As a result, the facsimile device 20 shifts to a receiving state. In addition, in the same way as when transmitting, relay N
S operates to switch contact Ns, and when there is an incoming call from the subscriber telephone line LN, the telephone 14 responds by voice. Also, relay K1 performs busy monitoring on the subscriber telephone line side, and relay K2 performs busy monitoring on the leased line side. Further, if a call is received on the PBX extension while the facsimile device 20 is communicating with the subscriber telephone line LN, the sequence control circuit 33 detects that the communication is in progress by the operation of the relay K1, and relay Y2
is operated to switch contact Y2 and cause the extension telephone 15 to respond by voice.

As explained above, according to the present invention, line switching between the leased line and subscriber telephone line is performed by the line-side DC circuit which is the front part of the network control device, so that the network control device for the subscriber telephone line is It can also be used for lines, and lines can be switched without any modification to data terminal equipment such as facsimile machines.

Furthermore, by using the line switching device of the present invention, a dedicated line connection can have the same interface conditions as a subscriber telephone line, and line selection at the time of transmission can be performed manually, while switching at the time of reception can be performed automatically. Moreover, even if the line switching device fails or the power is cut off, communication is always possible because it is based on the subscriber telephone line connection. Note that the present invention is not limited to facsimile, but can also be applied to general data communication.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing a conventional line switching method, FIG. 3 is a block diagram showing a first embodiment of the line switching device of the present invention, and FIG. 4 is a block diagram of the line switching device of the present invention. FIG. 5 is a detailed block diagram of the line switching device of FIG. 3, and FIG. 6 is a detailed block diagram of the line switching device of FIG. 4. 1: Network control device, 2: Modulation/demodulation device, 5: Facsimile control section, 7: Attached telephone, 13: Subscriber telephone line main telephone,
14: Dedicated line telephone, 15: Extension telephone, 16: Private branch exchange, 17: In-band ringer, 19, 22, 24,
35: line protection device, 20: facsimile device, 21,
23, 27, 36: Separator, 26, 28, 37: Attenuator, 29: Calling signal detector, 30, 40: Line switching device, 31: 16Hz signal generator, 32, 33: Sequence control circuit, 34 : Ringing detection circuit, 38: Selection signal, busy signal generator, 39, 41: Transmission, reception amplifier.

Claims (1)

[Scope of Claims] 1. A switching connection means having a line protection device for a subscriber telephone line and a line protection device for a dedicated line, and connecting the subscriber telephone line and the dedicated line via a network control device common to the switching connection means. A line switching device characterized in that when switching and connecting a line to a facsimile machine, when either line is connected, the corresponding one of the two line protection devices is switched and inserted. 2. The switching connection means always connects the subscriber telephone line to the facsimile machine, and when an incoming call is received on the dedicated line, it sends a ringing bell signal to the facsimile machine, and when the facsimile machine responds, the incoming call is terminated. 2. The line switching device according to claim 1, wherein the facsimile device is connected to a dedicated line. 3. The switching connection means always connects the subscriber telephone line to the facsimile machine, and when a call is requested to the dedicated line, the switching connection means is switched on by pressing a switch provided on the switching connection means. 3. The line switching device according to claim 1, wherein a facsimile device is connected to the outgoing dedicated line via the line.