JP2647545B2 - Communication device using cordless telephone - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a communication device using a cordless telephone.

2. Description of the Related Art In order for conventional facsimile machines and personal computers to communicate via a public telephone line, the public telephone line needs to be brought into the vicinity of a house. Furthermore, it is difficult to say that such an information communication terminal device can be connected to a telephone line.

SUMMARY OF THE INVENTION An object of the present invention is to provide a communication device using a cordless telephone that enables an information communication terminal device to be easily connected to a public telephone line to perform communication. .

Means for Solving the Problems The present invention provides (a) a base unit 19 connected to a public telephone line 61 for performing telephone communication, and (b) a pair of two-way transmitting / receiving units connectable to the public telephone line 61 for transmitting and receiving. (C) wirelessly communicates with the base unit 19, and the information communication terminal device 22 includes a transmission line, a reception line, and a common line.
And (d) a two-wire to three-wire conversion device, wherein (d1) two units connected to the bidirectional lines 44 and 46, respectively.
(D2) second terminals 47, 48, and 49, the second terminal for transmission line 47 being connected to the transmission line.
A second terminal 48 for the receiving line connected to the receiving line
And a common line second terminal 49 connected to the common line.
(D3) a DC power supply 51 having a negative electrode connected to the common line second terminal 49; and (d4) one end connected to the positive electrode of the DC power supply 51 and the other end. Is a first resistor R1 connected to one first terminal 42, and (d5) a public telephone line protection in which one end is connected to the other first terminal 43 and the other end is connected to the common line second terminal 49. (D6) one end is connected to the other end of the first resistor R1 and the first
A first capacitor C1 for line stabilization connected to a first connection point 55 with the terminal 42 and the other end connected to the second terminal 49 for common line; and (d7) the power of the DC power supply 51 is supplied. A first operational amplifier 52 having an output terminal 63 connected to the transmission line second terminal 47 and a gain of 2; (d8) one end connected to the first connection point 55 and the other end connected
A second capacitor C2 connected to the positive input terminal 58 of the first operational amplifier 52 to cut off the DC and separate the line; and (d9) the power of the DC power supply 51 is supplied, and the input terminal 62 is 2 terminal 48 is connected to the output terminal 61
A second operational amplifier 53 connected to the negative input terminal 59 of the first operational amplifier 52 at a connection point 60 and having a gain of 1; (d10) the other end of the second capacitor C2 and the second connection point 6
(D11) a fourth resistor R4 connected between the second connection point 60 and the common line second terminal 49; When the impedance of the two-wire interface 23 in the information communication terminal device 22 connected to the two-way lines 44 and 46 is R5, the two-wire to three-wire conversion device defined by R2 + R5 = R3 is included. It is a communication device using a telephone.

According to the present invention, an information communication terminal device such as a facsimile device and a personal computer has a pair of bidirectional lines connectable to a public telephone line.
A handset that communicates wirelessly with a base unit of a cordless telephone can be connected to a handset or the like through a total of three lines including a transmission line, a reception line, and a common line. Therefore, between the slave unit and the information communication terminal device, a two-wire-3
With the line converter interposed, the information communication terminal device can communicate with the 2-wire to 3-wire converter via the public telephone line via the slave unit and the base unit. Since the information communication terminal device is connected to the cordless telephone handset via the 2-wire to 3-wire conversion device, the information communication terminal device can be easily connected to the public telephone line. In the present invention, the work for bringing the public telephone line into the vicinity of the house as described in connection with the prior art described above is not necessary.

FIG. 1 is an overall block diagram of an embodiment of the present invention. The telephone company 17 is connected to a line 61 of a public telephone line of a so-called cordless telephone 18 to perform telephone communication with the base unit 19.
Is connected wirelessly. The main body 19 is wirelessly connected to the cordless handset 20. The slave 20 has 3
A line interface 21 is provided.

An information communication terminal device 22 such as a facsimile device or a personal computer has a two-wire interface 23 for a public telephone line. 2-wire-3 according to the invention
By connecting the line conversion device 24 via the lines 25 and 26, transmission / reception signals can be transmitted between the information communication terminal device 22 and the slave unit 20.

FIG. 2 is a block diagram showing a configuration of the slave unit 20. The child device 20 is provided with a child device main body 27.
Can wirelessly communicate with the base unit 19 by the operation of the control circuit 28. The audio signal received from the slave unit main body 27 is amplified by the amplifier circuit 30 from the changeover switch 29, and is sounded by the speaker 31. The audio signal from the microphone 32 is provided from the changeover switch 33 to the child device main body 27, and transmitted to the parent device 19 wirelessly. 3-wire interface
21 has matching circuits 34 and 35 connected to changeover switches 29 and 33, respectively, and further connected to a common terminal 40 and a transmission terminal 37 connected to a transmission line 36 and a reception terminal 39 connected to a reception line 38. Common terminal 41.

FIG. 3 is a specific electric circuit diagram of the 2-wire to 3-wire converter 24. The two-wire to three-wire conversion device 24 has first terminals 42 and 43 for connection to the line 25 connected to the two-wire interface 23 of the information communication terminal device 22. The first terminals 42 and 43 are connected to bidirectional lines 44 and 46 with which the information communication terminal device 22 performs transmission and reception. These bidirectional lines 4
4 and 46 are indicated by reference numeral 25 in FIG. This 2
The wire-to-wire converter 24 has second terminals 47,48,49. The second terminal 47 is connected to the transmission terminal 37 of the transmission line 36 of the three-wire interface 21 in the child device 20. Another second terminal 48 is a terminal to be connected to the receiving terminal 39 of the receiving line 38. Still another second terminal 49 is a terminal for connecting to the common terminal 41 of the common line 40. Between these first terminals 42, 43 and second terminals 47, 48, 49, an electric circuit 50 for transmitting and receiving signals between them is provided.
Is provided. Each terminal 37, 39, of the 3-wire interface 21
41 and the second terminals 47, 48, 49 of the 2-wire to 3-wire converter 24 are connected via the line 26 as described above.

The electric circuit 50 in the two-wire to three-wire converter 24 includes a DC power supply 51. This DC power supply 51 is connected to operational amplifiers 52, 5
While supplying power to 3, a voltage is applied to the bias supply resistor R1. One first terminal 42 is connected via a line 54 to a connection point 55 of the resistor R1. Another first terminal
43 is grounded via line 56 and a public telephone line protection resistor R2. A line stabilizing capacitor C1 is connected between the connection point 55 and the resistor R2.

The connection point 55 has a gain of 2 through a capacitor C2 for performing a DC cutoff and separating a line, and further through a line 57.
Is connected to a positive input terminal 58 having a high input impedance. The negative input terminal 59 of the operational amplifier 52 is connected to a connection point
At 60, it is connected to the output terminal 61 of another operational amplifier 53. An input terminal 62 of the operational amplifier 53 is connected to a second terminal 48 for the receiving line. The gain of the operational amplifier 53 is 1. A resistor R3 is connected between line 57 and connection point 60.
Is connected, and a resistor R4 is connected between the connection point 60 and the ground. These resistors R3 and R4 function to separate the transmission and reception bidirectional signals. The operational amplifiers 52 and 53 have a high input impedance. The operational amplifiers 52 and 53 have low output impedance. The output terminal 63 of the operational amplifier 52 is connected to the second terminal 47 for the transmission line. One more
The two second terminals 49 are grounded.

Two-wire interface 23 in information communication terminal device 22
Is indicated by reference numeral R5 in FIG.

Here, R2 + R5 = R3 (1). The voltage of a signal derived from the second terminal 48 of the receiving line to the output terminal 61 of the operational amplifier 53 is VM, and the voltage between the ground level of the second terminal 49 of the common line of one first terminal 42 and VL is The voltage VL includes the information communication terminal device 22
The transmission signal VTX from Since the output of the operational amplifier 52 is VS, the voltage of the positive input terminal 58 of the operational amplifier 52 is VL, and the voltage of the negative input terminal 59 is VM, VS = VL + VM = (2 · VTX + VM) −VM = 2VTX ... (3) Therefore, the transmission signals from the first terminals 42 and 43 are
It can be seen that the signal can be sent between the second terminals 47 and 49.

In the present invention, it is important that communication can be performed using the conversion unit shown in FIGS. 2 and 3 by providing the interface 21 conforming to the three-wire interface specification also in the cordless phone handset shown in FIG. It is. Third
The specific configuration shown in the figure is only one example, and the present invention may be implemented using a processing device such as a three-wire interface information communication terminal device from the beginning. The important point of the present invention is that the cordless phone handset has a three-wire interface specification,
It is especially important to adopt a configuration with standard specifications.

Effect of the Invention As described above, according to the present invention, an information communication terminal device is connected to a slave unit that wirelessly communicates with a base unit of a cordless telephone via a 2-wire to 3-wire conversion device. There is no need to draw the public telephone line described in connection with the prior art described above, and the information communication terminal device can communicate via the public telephone line, and can easily perform communication using the information communication terminal device. It becomes possible.

In particular, by using the 2-wire to 3-wire conversion apparatus of the present invention, 2-wire to 3-wire conversion can be easily performed, that is, 2-wire to 3-wire conversion can be realized with a simple configuration. The excellent effect of being able to do so is achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
FIG. 3 is a block diagram showing a specific configuration of 20. FIG.
FIG. 2 is an electric circuit diagram of the wire conversion device 24. 17… Telephone company, 18… Cordless telephone, 19 …… Master unit, 20 …… Slave unit, 21 …… Three-wire interface, 22 ……
Information and communication terminal equipment, 23 ... 2-wire interface, 24 ...
... 2-wire to 3-wire converter, 42,43 ... First terminal, 47-49 ...
... second terminal, 50 ... electric circuit

Claims (1)

(57) [Claims] 1. An information communication terminal having (a) a base unit 19 connected to a public telephone line 61 for performing telephone communication and (b) a pair of bidirectional lines for transmission and reception connectable to the public telephone line 61. And (c) wireless communication with the base unit 19, and an information communication terminal device using a total of three lines of a transmission line, a reception line, and a common line.
(D) a two-wire to three-wire conversion device, which is connected to the bidirectional lines 44 and 46, respectively.
(D2) second terminals 47, 48, and 49, the second terminal for transmission line 47 being connected to the transmission line.
A second terminal 48 for the receiving line connected to the receiving line
(D3) a DC power supply 51 having a negative electrode connected to the common line second terminal 49; and a second terminal 47, 48, 49 comprising a common line second terminal 49 connected to the common line. (D4) a first resistor R1 having one end connected to the positive electrode of the DC power supply 51 and the other end connected to one first terminal 42; and (d5) one end connected to the other first terminal 43 and the other end. And (d6) one end of which is connected to the other end of the first resistor R1 and the first end of the first resistor R1.
A first capacitor C1 for line stabilization connected to a first connection point 55 with the terminal 42 and the other end connected to the second terminal 49 for common line; and (d7) the power of the DC power supply 51 is supplied. A first operational amplifier 52 having an output terminal 63 connected to the transmission line second terminal 47 and a gain of 2; (d8) one end connected to the first connection point 55 and the other end connected
A second capacitor C2 connected to the positive input terminal 58 of the first operational amplifier 52 to cut off the DC and separate the line; and (d9) the power of the DC power supply 51 is supplied, and the input terminal 62 is 2 terminal 48 is connected to the output terminal 61
A second operational amplifier 53 connected to the negative input terminal 59 of the first operational amplifier 52 at a connection point 60 and having a gain of 1; (d10) the other end of the second capacitor C2 and the second connection point 6
(D11) a fourth resistor R4 connected between the second connection point 60 and the common line second terminal 49; When the impedance of the two-wire interface 23 in the information communication terminal device 22 connected to the two-way lines 44 and 46 is R5, the two-wire to three-wire conversion device defined by R2 + R5 = R3 is included. A communication device using a telephone.