JPH0797792B2 - Network control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In a network control circuit for selectively and connecting the telephone line to a telephone and a modem, the telephone line is connected to the telephone line by a modem. A hook switch and dial pulse generation function are added to the relay that switches to the telephone, and the hook state of the telephone when switched to the modem side can be identified by the output of the hook state detection circuit. The present invention relates to an improvement of a network control circuit which has a function of manually transmitting to a telephone line and an automatic transmitting function and which switches and connects the telephone line to a telephone and a modem.

[Conventional technology]

 FIG. 3 is a diagram showing an example of a conventional data terminal.

FIG. 4 is an explanatory diagram of the switching operation of the conventional network control circuit.

In the figure, 1 is a switchboard, 2 is a modem, 3 is a network control circuit, 4 is a terminal, 5 is a telephone, 10 is a modem transmitter, 11 is a modem receiver, 12 is DTMF, 13 is a DT detector, and 14 Is a HYB, 15 is a transformer, 16 is RD, 17 is RI, 18 is HO, 19 is a DP switch, 20 is a switching relay, and 20a and 20b are both contacts of the switching relay 20. The same symbols represent the same objects throughout the drawings.

In the above explanation of symbols, HYB is a hybrid, DTMF is a multi-frequency oscillator, RD is a polarity inversion detection circuit, RI is a ringer detection circuit, and HO.
Is an abbreviation for hook-off detection circuit and DT detector for dial tone detector.

As shown in FIG. 3, a conventional data terminal is composed of a terminal 4, a telephone 5, a modem 2, and a network control circuit 3, and the modem 2 and the network control circuit 3 often have an integrated structure.

The network control circuit 3 is provided with a switching relay 20 as shown in FIG. 4, and operates according to a command from the network control circuit 3. This switching relay 20 operates and its contacts 20a, 20b move,
The telephone 5 is connected to the communication line to set the telephone mode, or the modem 2 is connected to set the data transmission mode.

The contact positions of the contacts 20a and 20b of the switching relay 20 shown in FIG. 4 represent the telephone mode state.

In the case of manual call, the operator hooks the telephone 5 in the telephone mode. The hook-off of the telephone 5 is transmitted to the network control circuit 3 by HO18.

If the operator subsequently transmits a dial signal to perform data transmission, when the other party comes out, the switching relay 20 is operated to enter the data transmission mode. By this operation, a loop is formed via the transformer 15, the hook-off state is continued, and data transmission is performed.

In the case of automatic transmission, the operator operates the switching relay 20 to enter the data transmission mode. By this operation, a loop is formed through the transformer 15, the hook is turned off, and when the dial tone is sent from the exchange 1, the DT detector 13 operates and the network control circuit 3
Tell.

Then, when a dial signal is sent from the terminal 4 side, the network control circuit 3 switches the DR switch 19 on and off to send the dial signal to the line side. If a multi-frequency signal is used, the network control circuit 3 drives the DTMF 12 and sends the multi-frequency signal to the line via the HYB 14 and the transformer 15.

When the partner terminal responds, the exchange 1 side reverses the polarity and the RD16
When this is detected, it switches to the telephone side in the case of an automatic telephone call, and in the case of data transmission, the data transmission is started with the connection kept.

[Problems to be solved by the invention]

However, the circuit shown in FIG. 4 has a drawback that it is complicated, and when the telephone is switched to the telephone side after the automatic transmission in the data transmission mode, the switching relay is operated during the hook-on of the telephone to enter the telephone mode. There was a drawback that the line was cut.

[Means for solving problems]

The above-mentioned problem is that the network control circuit 30 for selectively and connecting the telephone line to the telephone and the modem has the functions of manually transmitting and automatically transmitting the telephone line as shown in FIG. The second switching relays 20 and 21 and the hook state detection circuit 25 are provided, and the hook state detection circuit 25 detects the hook-on and hook-off states of the telephone connected to the circuit and outputs a signal corresponding to the state. The contact 20a, 20b of the first switching relay 20 is arranged so as to switch the connection between the telephone line and the modem side, and the contact 21a of the second switching relay 21 is arranged. , 21b are arranged so as to switch the connection between the telephone side and the hook state detection circuit 25, and the contact 20 of the first switching relay is arranged.
When the telephone line is connected to the modem side by a and 20b, the telephone is connected to the hook state detection circuit 25 by the contacts 21a and 21b of the second switching relay to detect the hook state of the telephone. This is solved by discriminating by the output of the circuit 25 and transmitting the dial pulse by intermittently operating only the first switching relay 20 in the switching connection state.

[Action]

According to the present invention, the circuit is simplified as compared with the conventional method, not only the number of parts is reduced, but also the hook state of the telephone 5 can be detected during the data transmission mode to be used for determining whether to switch to the telephone mode. There is also the effect of saying.

〔Example〕

 FIG. 1 is a principle diagram of the present invention.

In the figure, 21 is a switching relay, 21a and 21b are contacts of the switching relay 21, 22 is a detection circuit according to the present invention, 23 is RI, and 30 is a network control circuit according to the present invention.

In the present invention, both the switching relay 21 and the switching relay 20 are driven by the network control circuit 30.

The contact positions of the switching relay 20 and the switching relay 21 in FIG. 1 are in the telephone mode.

In the case of manual call, the operator hooks the telephone 5 in the telephone mode. The hook-off of the telephone 5 is transmitted to the network control circuit 30 by the detection circuit 22.

If the operator subsequently sends a dial signal to perform data transmission, when the other party comes out, the switching relays 20 and 21 are operated to enter the data transmission mode. By this operation, a loop is formed via the transformer 15, the hook-off state is continued, and data transmission is performed.

In case of automatic transmission, the operator controls the network control circuit 30 to switch the relays 20 and 21.
To drive the data transmission mode.

A loop is formed through the transformer 15 by the operation of the switching relay 20, the hook-off state is reached, and when the dial tone is sent from the exchange 1, the DT detector 13 operates and the network control circuit.
Tell 30

The operation of the switching relay 21 disconnects the telephone 5 from the line, and the telephone 5 is connected between the + 5V and the ground of the hook state detection circuit 25. Therefore, when the telephone 5 is in the hook-off state, the potential at the point x is grounded, and when the telephone 5 is in the hook-on state, the potential at the point x is +5, so that the network control circuit 30 outputs the signal PR from the hook state detection circuit 25. The hook on / off state of the telephone 5 can be determined by the potential of the output point x.

Then, when a dial signal is sent from the terminal 4 side, the network control circuit 30 intermittently operates the switching relay 20 to send the dial signal to the line side. At this time, the switching relay 21 maintains the data transmission mode.

If multi-frequency signals are used, the network control circuit 30 uses DTMF
12 is driven to send a multi-frequency signal to the line via HYB 14 and transformer 15.

When the partner terminal responds, the switch 1 side reverses the polarity, the detection circuit 2 detects this, and in the case of data transmission, data transmission is started with the connection kept, and in the case of automatic call origination of the telephone line. To connect to the telephone side.

In the present invention, as described above, the network control circuit 30 can identify the hook on / off state of the telephone 5 during data transmission by the output of the hook state detection circuit 25. Therefore,
If this identification is used to determine whether to switch from the data transmission mode to the telephone mode, it is possible to avoid the inconvenience of disconnecting the line by switching the line connected in the data transmission mode to the telephone in the hook-on state. .

When the data transmission is completed, the network control circuit 30 switches the switching relay 2
Drive 0, 21 to return to phone mode.

FIG. 2 is a diagram showing an embodiment of a network control circuit according to the present invention.

In the figure, 31, 32, and 33 are varistors, 34, 35, 38, 39, and 40, respectively.
Are resistors, 36, 37, 44 and 45 are photocouplers, 41 is a capacitor, and 42 and 43 are zener diodes.

2 is a detailed view of a part of FIG. 1, the detection 22 surrounded by a chain line is a detailed view of the detection circuit 22 of FIG. 1, and RI23 surrounded by a chain line is RI23 of FIG. FIG.

The detection circuit 22 is a circuit that detects whether or not a current flows through the varistor 33 and the direction of the current.

When a current flows in the direction of the arrow, a current flows through the light emitting element of the photocoupler 36, the light receiving element is turned on, and the terminal a becomes the ground potential.

When a current flows in the direction opposite to the arrow, a current flows in the light emitting element of the photocoupler 37, the light receiving element is turned on, and the terminal b becomes the ground potential.

When no current flows, the light receiving elements of both photocouplers are both turned off, and the potentials of terminals a and b are both + 5V.
Any such information is sent to the network control circuit 30.

RI23 is a ringer detection circuit that extracts only the ringer voltage (AC voltage) generated between the terminals c and d. That is, the capacitor
The DC component is cut off by 41, and only the ringer voltage is taken out,
Similarly to the case of the detection circuit 22, the photo couplers 44 and 45 detect the same. The Zener diodes 42 and 43 are for protection.

〔The invention's effect〕

As described above in detail, according to the present invention, the hook state of the telephone in the data transmission mode can be accurately determined by using the same amount of used parts as the circuit of the conventional system, and whether or not the telephone mode can be switched. There is a great effect that it can be identified.

Further, according to the present invention, when the telephone line is switched to the modem side and the telephone line is switched to the telephone side after connecting to the other party by the automatic call, it is possible to confirm the hook-off of the telephone and switch the telephone line in the hook-on state. The inconvenience of connecting the line to and disconnecting the line can be prevented.
Further, according to the present invention, since the switching relay can also be used for sending dial pulses, it is not necessary to provide another relay dedicated to sending dial pulses, and the number of relays is not increased. In addition, automatic transmission can be performed by sending dial pulses using a switching relay, and manual and automatic transmission functions can be switched. Therefore, in the network control circuit for connecting the telephone line by switching between the modem and the telephone, there is a great effect that the automatic call operation for telephone conversation can be surely performed.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention. FIG. 2 is a diagram showing an embodiment of a network control circuit according to the present invention. FIG. 3 is a diagram showing an example of a conventional data terminal. FIG. 4 is an explanatory diagram of the switching operation of the conventional network control circuit. In the figure, 1 is a switchboard, 2 is a modem, 3 is a network control circuit, 4 is a terminal, 5 is a telephone, 10 is a modem transmitter, 11 is a modem receiver, 12 is DTMF, 13 is a DT detector, and 14 Is HYB, 15 is a transformer, 16 is RD, 17 is RI, 18 is HO, 19 is a DP switch, 20 is a switching relay, 20a and 20b are both switching relay 20 contacts, 21 is a switching relay, and 21a and 21b are both Switching relay 21 contact point, 22 is a detection circuit, 23 is RI, 25 is a hook state detection circuit, 30 is a network control circuit according to the present invention, 31, 32, 33 are varistors, 34, respectively.
35, 38, 39, 40 are resistors, 36, 37, 44, 45 are photocouplers, 41 is a capacitor, and 42, 43 are zener diodes.

Claims (1)

[Claims] 1. A network control circuit (30) for selectively and connecting the telephone line to a telephone and a modem, which has a function of manually and automatically making a call to a telephone line, and a first and a second switching. Relays (20, 21) and hook state detection circuit (2
5) is provided, and the hook state detection circuit (25) is a circuit that detects a hook-on state and a hook-off state of the telephone connected to the circuit and outputs a signal corresponding to the state. The contacts (20a, 20b) of (20) are arranged so as to switch the connection between the telephone line and the modem side, and the contacts (21a, 21b) of the second switching relay (21) Is arranged so as to switch the connection between the telephone line side and the hook state detection circuit (25), and the telephone line is connected to the modem side by the contacts (20a, 20b) of the first switching relay. In the case of doing, the hook state detection circuit (25) of the telephone is set by the contact of the second switching relay.
And a hook state of the telephone is identified by an output of the hook state detection circuit, and a dial pulse is transmitted by intermittently operating the first switching relay (20) in the switching connection state. A network control circuit characterized in that