JP2001069264A - Modem - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a relay for line switching. SOLUTION: This modem comprises a modem main body 22 connected to public lines 12 and a network control circuit 24 connected between the public lines and a telephone set 60. The circuit 24 has a switching relay 70 for switching the public lines and a power supply 32 for direct current circuit formation to the set 60 connected to the relay 70. The switching state is controlled by a switching relay modem main body. The set 60 is connected to the power supply 32 for direct current circuit formation in its initial state, and when the lines are caught, the set 60 is connected to the public line. When a number display signal is detected and a speech communication mode is set, the relay 70 is switched to a state shown by a broken line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modem connected between a terminal device such as a computer and a telephone. More specifically, a network control circuit connected between a public line and a telephone set or a modem main body is provided with a reduced number of line switching means so that cost reduction and the like can be achieved.

[0002]

2. Description of the Related Art Some modems connected between a terminal device such as a computer and a telephone have recently been provided with a number display function. The number display function means that the telephone number of the caller (caller) is displayed on the telephone or related display means before the receiver (callee) answers (before picking up the handset). This is a displayed function.

FIG. 2 shows an example of a line connection relationship between a modem having such a number display function, a terminal device, and a telephone. In FIG. 2, the public line 12
Is connected to the modem 20. The modem 20 is connected to a personal computer 50, which is a terminal device, and to a telephone 60. The modem 20 is a modem body 22
And a network control circuit (NCU) 24.

In this example, the network control circuit 24 is connected to the public line 1
2 is connected to the modem 20 side or the telephone 50 side, and is provided with a ring tone detector 26 connected to both lines 12a and 12b of the public line 12. A pulse relay 28 for connecting the public line 12 to the modem body 22, a first switching means (relay) 30 connected between the pulse relay 28 and the public line 12, and a telephone 50
Switching means (relay) 31 for connecting to the side
It is composed of

[0005] First and second switching relays 30, 3
1 is a pair of changeover switches (30a, 30
b) and (31a, 31b), one of the contacts (ac) is connected to each other, and the contact b is connected to the modem body 22 side. In the second switching relay 31, one of the other contacts d is connected to a power supply (DC power supply) 32 for forming a DC circuit for the telephone 60, and the other is grounded.

[0006] A detecting means 36 for detecting the on-hook and off-hook states of the telephone 60 is connected to the line 34 connected to the power supply 32 side. The detecting means 36 is configured as a photocoupler, and includes a pair of photodiodes 38 a and 38 b connected in opposite directions and a phototransistor 40. The output of the phototransistor 40 is supplied to the modem body 22. Further, the modem main body 22 controls switching of the pulse relay 28 based on the detection output of the ring tone detector 26 and the detection output of the phototransistor 40, and controls the pair of switching relays 3.
0 and 31 are switched and controlled.

In the modem 20 and the terminal device 50 configured as described above, recently, a telephone 60 has a number display function as a service of a public line carrier.
It can be mounted on In order for this number display mode to function, a number display signal is detected, or a received telephone number is converted into a number or character signal, for example, the screen 50a of the terminal device 50 in this example.
Is installed in the terminal device 50.

When such software is installed, the first and second switching relays 3
The initial switching state is set to 0 and 31 as follows. When the terminal device 50 is powered on and its computer is started, the start-up state is detected by the modem main body 22 and the first switching relay 30 is initialized so that the first switching relay 30 is in the switching state as shown by the solid line. The state is set. The initial state of the second switching relay 31 is also set so as to be in the switching state as shown by the solid line.

Thus, when the terminal device 50 is operating, the public line 12 is connected to the modem main body 22 side. When a ring tone is detected, the control signal Sp from the modem main body 22 is transmitted. Controls the pulse relay 28 to capture the line. When the line is acquired, the modem main body 22 receives the number display signal transmitted before the incoming signal, and displays the telephone number and the name of the caller on the screen 50a.

When it is determined that the signal should be received, control signals Sa and Sb are generated from the modem main body 22, and the switching relays 30 and 31 are controlled to be switched as indicated by broken lines. By this switching, public line 1
2 is connected to the telephone set 60 by first and second switching relays 30 and 31, and a call can be made by picking up the receiver.

When the telephone is terminated and the receiver is off-hook, the detection signal (call signal) from the detecting means 36 is interrupted.
a, Sb, and the first and second switching relays 30, 3
1 is returned to the position indicated by the solid line again to automatically return to the initial state.

When the receiver of the telephone 60 is lifted off-hook in this initial state, the power supply 32 and the telephone 6 are turned off.
A direct current circuit is formed by the line 34 between the zero point and the zero point. The current flowing at this time activates the detecting means 36, and the detecting current flows through the transistor 40. Since this detection current is supplied to the modem main body 22, the modem main body 22 recognizes the off-hook state of the telephone 60 by this. As a result, control signals Sa and Sb are generated, and
4 is connected to the public line 12 so that the telephone 60 can talk to an outside line.

[0013]

By the way, if the number display function is added in this way, the network control circuit 2
4 includes two switching relays 30 and 31 for switching the public line 12 between the modem body 22 side and the telephone 60 side.
Is required, which leads to an increase in the number of electronic components and a corresponding increase in cost. A configuration that does not increase the cost even when the number display function is added is desired.

The present invention has been made to solve such a conventional problem, and allows a public line to be switched between a modem main body and a telephone without increasing the number of parts, thereby adding a number display function and the like. The present invention proposes a modem that achieves a simplified configuration even in such a case.

[0015]

In order to solve the above-mentioned problems, in a modem according to the present invention, a modem main body connected to a public line and a network control circuit connected between the public line and a telephone are provided. The network control circuit has switching means for switching the public line, and a DC circuit forming power supply for the telephone connected to the switching means, and the switching means is switched by the modem main body. The state is controlled, and in an initial state, the telephone is connected to the DC circuit forming power supply, and the telephone is connected to the public line when a line is captured.

In the present invention, only one line switching means 70 is provided not on the public line 12 but on the line 34 on the telephone 60 side. Then, the public line 12 is connected to one contact of the switching means 70, and the other contact is used as a line for forming a DC circuit for the telephone 60.
Therefore, a power supply 32 for forming a DC circuit is connected to the other contact 60 side.

The initial state of the switching means 70 is shown by a solid line. When the number display function is added, the initial state is the state shown by the solid line. When a ring tone is detected, the pulse relay 28 is controlled, and in the case of a normal modem without a number display function, a control signal Sc is immediately generated from the modem body 22. The switching means 70 is switched to the state shown by the broken line by the control signal Sc, and the line 3 on the telephone 60 side is switched.
4 is connected to the public line 12, and a normal communication state is established.

When the number display signal is transmitted following the ring tone, the modem main body 22
If the terminal device 50 has a number display function, the terminal device 50 receives and analyzes the number display signal and displays the telephone number on the terminal device 50. When a call is desired, a control signal Sc is given from the modem body 22 to switch the switching means 70 to the state shown by the broken line. The telephone 60 is connected to the public line 12 by this switching.

In the initial state, the switching means 70 is in the state shown by the solid line, so that when the telephone 60 goes off-hook, the DC circuit by the power supply 32 is closed, and the state is detected by the detecting means 3.
6, the switching means 70 is switched to the state shown by the dashed line, thereby transiting to the normal call mode.

[0020]

Next, an embodiment of a modem according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a modem according to the present invention.
Is connected to the public line 12 and to a microcomputer 50 in this example, which is a terminal device. Modem 20 is further connected to telephone 60.

The modem 20 includes a modem body 22 as in FIG.
And a network control circuit (NCU) 24 for line control. The network control circuit 24 controls both lines 12 of the public line 12.
a, a ring tone detector 26 connected to the 12b side;
A pulse relay 28 connected to one of the lines 12a for connecting the public line 12 to the modem body 22, and a switching means 70 for connecting the telephone set 60 to the public line 12.
It is composed of

As the switching means 70, a normal electronic switch (such as a transistor) can be used, or a two-circuit, two-contact relay can be used. FIG. 1 shows a case where a relay is used. Switching relay 7
0 has a pair of changeover switches 70a, 70b, one contact f of which is connected to the public lines 12a, 12b, and one of the other contacts e, a power supply (DC power supply) 32 for forming a DC circuit for the telephone 60. Connected to
The other is grounded.

A detecting means 36 for detecting an on-hook state and an off-hook state of the telephone 60 is connected to a line 34 connected to the power supply 32 side. This detection means 36
In this embodiment, a photocoupler is used as in the case of FIG. 2, and a pair of photodiodes 38a and 38b and a phototransistor 40 connected in opposite directions are provided. The detection output of the phototransistor 40 is supplied to the modem main body 22.

The modem body 22 includes a ring tone detector 26
The switching control of the pulse relay 28 and the switching control of the switching relay 70 are performed based on the detection output of the photo transistor 40 and the detection output of the phototransistor 40. This is a case where a modem equipped with a number display function is used as the modem body 22, and software for implementing the number display function using the terminal device 50 is installed in the terminal device 50. By installing this function, the telephone number and name of the caller can be stored in the terminal device 50.
Can be displayed on the screen 50a, and it can be instructed whether or not to connect the public line 12 by an instruction from the terminal device 50 side.

The modem main body 22 determines whether or not to control the switching relay 70 in accordance with an instruction from the terminal device 50 side. When it is desired to connect a line, the switching relay 70 is controlled to connect the telephone 60 to the public line 12, and when the call is rejected, the switching relay 70 is left as it is (initial state).

Now, in the modem 20 configured as described above, the initial state of the switching relay 70 is shown by a solid line. That is, regardless of whether the terminal device 50 is in the operating state or not and whether or not the number display function is added, the initial state is the state shown by the solid line.

When a ring tone is detected by the ring tone detector 26, the pulse relay 28 is controlled and the public line 12 is connected to the modem body 22. In the case of a normal modem to which the number display function is not added, the control signal Sc is immediately generated from the modem main body 22. By this control signal Sc, the switching relay 70 is switched to the state shown by the dashed line, the line 34 on the telephone 60 side is connected to the public line 12, and by going off-hook, a normal communication state is established.

When the number display signal is transmitted following the ring tone, and the modem main body 22 and the terminal device 50 have a number display function, the number display signal is received, analyzed, and transmitted to the terminal. The device 50 displays the telephone number on the screen 50a. When a call is desired, the control signal Sc is given from the modem body 22 to switch the switching relay 70 to the state shown by the broken line. By this switching, the telephone set 60 is connected to the public line 12, and if the telephone goes off-hook, a telephone call state is established.

In the initial state, the switching means 70 is in the state shown by the solid line, so that when the telephone 60 is off-hook, the DC circuit by the power supply 32 is closed with the telephone 60. When the DC circuit is formed, the photodiodes 38a and 38b are excited by the current flowing through the line 34, the light is received by the phototransistor 50, and the detection current flows. As a result, the off-hook state of the telephone set 60 is detected by the modem main body 22, and the switching relay 70 is switched to the state shown by the broken line, and the normal communication mode is set.

In the above-described embodiment, the number display function cannot be exhibited unless the terminal device 50 is operating. However, when the terminal device 50 is turned off, the modem 20 operates as a number display adapter. This modem 20 can also be set to cause this. However, in this case, since the number display is not displayed, it is necessary to register the telephone number of the caller to be accepted in advance.

[0031]

As described above, in the present invention, the line on the telephone side is provided with switching means for switching to the public line. According to this, even if the number of the switching means is reduced, the number display function can be supported, so that the cost can be reduced due to the reduction in the number of parts. By reducing the number of switching means by one, the power consumption of the modem itself can also be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of a main part showing an embodiment of a modem according to the present invention.

FIG. 2 is a system diagram of a conventional modem having a number display function.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Public line 20 Modem 22 Modem main body 24 Network control circuit 32 DC circuit power supply 34 Line 36 Detecting means 50 Terminal device 60 Telephone 70 Switching relay

Claims (5)

[Claims] 1. A modem comprising: a modem connected to a public line; and a network control circuit connected between the public line and a telephone. The network control circuit includes a switching unit for switching the public line; A power supply for forming a DC circuit for the telephone connected to the switching means, wherein the switching state of the switching means is controlled by the modem main body, and in an initial state, the telephone is connected to the DC circuit forming power supply side. A modem, wherein the telephone is connected to the public line when the line is connected and the line is seized. 2. The modem according to claim 1, further comprising a function of receiving a number display signal from a public line and transmitting a display signal related to the number to a terminal device. The stated modem. 3. The modem according to claim 1, wherein said switching means is a relay. 4. A signal line between the power supply for forming a DC circuit and a telephone is provided with signal detecting means, and the signal detecting means detects an off-hook state and an on-hook state of the telephone. The modem according to claim 1, wherein 5. The modem according to claim 4, wherein said signal detecting means is a photocoupler.