JPH05327790A - Modem device - Google Patents

Abstract

(57) [Abstract] [Purpose] With respect to a modem device, an object thereof is to provide a modem device that satisfies the current value standard for a telephone line even if an optional device is connected. In a modem device (1) to which an external device (9 ') having an additional function can be connected, one end of a DC loop circuit (9) which is connected to a telephone line by off-hook of a terminal device is connected to a line (L1) connected to the telephone line. The other end is connected to the terminal D of the connector 6 for connecting the external device 9 ', and the DC loop circuit 9
Of the line (L1) connecting one end of the same to the terminal C of the connector 6 and the other line (L1) connected to the telephone line.
2) is connected to the terminal E of the connector 6, and the external device 9 '
When the external device 9'is not connected, the terminal D and the terminal E of the connector 6 are short-circuited, and when the external device 9'is connected, the external device 9'is connected by the terminal C and the terminal E. Characteristic modem device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modem device for performing data communication by connecting a data terminal device to a telephone line.

Some modem devices can be connected to an external device having a function different from the original function of the modem. On the other hand, it is necessary for the modem device to form a DC loop circuit with the telephone line off-hook so that the telephone station can detect the off-hook of the terminal device from the current change caused by the off-hook. The current flowing in this DC loop circuit must be in the range of 20 mA to 120 mA DC according to the regulations. This standard must be observed even when an external device is connected to the modem device.

[0003]

2. Description of the Related Art FIG. 7 shows the configuration of a conventional modem device.
In the figure, 100 is a modem device, 101 is a data terminal device, and 101 'is an optional device, which is an external device having an additional function. Reference numeral 102 is a connector for connecting to a telephone line. 103 is connector A
That is, the connector 102 is formed integrally with the modem device. 103 'is a connector B,
This is a connector of the connector 102 that is connected to the telephone line, is formed at one end of the connection cable of the receptacle 104, and is integrally connected to the connector A (103). A receptacle 104 is connected to a telephone line connector (not shown). Reference numeral 105 denotes a connector, which is a connector for connecting an external device having an additional function (hereinafter referred to as an optional device).
Reference numeral 106 denotes a connector A, which is the side of the connector 105 integrally formed with the modem device. Reference numeral 106 'denotes a connector B, which is formed at one end of a cable connecting the optional device 101' and is integrally connected to the connector A (106).

Reference numeral 110 is a ring detection circuit, and 111 and 112.
Is a hook switch that is turned on by off-hook. Reference numeral 113 denotes a DC loop circuit, which is connected to a telephone line off-hook to flow a DC current. Reference numeral 113 'is a capacitor that blocks a direct current. 114 is a loop coil. Reference numeral 116 is a repeater transformer that separates the telephone line side and the modulation / demodulation unit (modem circuit) in terms of direct current and couples in alternating current. A modulation / demodulation unit (modem circuit) 115 converts an analog reception signal from the telephone line into a digital signal and converts a digital transmission signal input from the data terminal device 101 into an analog transmission signal.

The operation of the configuration shown in the figure will be described. The ring detection circuit 110 detects a ring signal input from the telephone line, and when it is off hooked, the hook switches 111 and 11
2 is turned on, and a current flows through the loop coil 114. As a result, the central office detects the off-hook of the terminal device.

DC current from the telephone line is generated by the capacitor 11
Repeater transformer 11 is cut off at 3'and only AC component
It is input to the modulation / demodulation unit 115 via 6. Then, the received signal is converted into a digital signal by the modulation / demodulation unit 115 and transferred to the data terminal device 101.

The transmission signal from the data terminal device 101 is
The modulation / demodulation unit 115 converts the analog signal and outputs the analog signal to the telephone line via the repeater transformer 116. When connecting an optional device (for example, a device that uses the power supplied from the telephone line as an external power source for the modem device), the connector B (106 ') at one end of the connection cable of the optional device 101' Is connected to the connector A (106) to establish connection with the modem device 100.

[0008]

The conventional modem device is
When an optional device was connected, the optional device was connected in parallel to the DC loop circuit. Therefore, the impedance to the telephone line becomes small,
In some cases, the above standards could not be observed.

According to the present invention, even if an optional device is connected,
It is an object of the present invention to provide a modem device that satisfies the standard of current value for a telephone line.

[0010]

SUMMARY OF THE INVENTION According to the present invention, when an optional device is connected, the DC loop circuit of the modem device is disconnected so that the internal circuit of the optional device has approximately the same resistance as the DC loop circuit. (However, if the internal impedance of the optional device is high, leave the DC loop circuit connected to the telephone line).

FIG. 1 shows a basic configuration (1) of the present invention. Reference numeral 1 is a modem device and 2 is a connector for connecting to a telephone line. Reference numeral 3 denotes a connector A, which is the side of the connector 2 formed on the modem device 1. Reference numeral 4 denotes a connector B, which is connected to the connector A (3) and is connected to the modem device 1
To connect to the telephone line. The terminals A and B are respectively connected to the terminals of the connector A (3) having the same symbol (in the connector, A, B, C, D and E represent the symbols for the terminals (connector pins)). Reference numeral 5 is a receptacle.

Reference numeral 6 denotes a connector for connecting the modem device 1 and an external device (optional device). Reference numeral 7 is a connector A'for connecting with an optional device. The terminal C is connected to the line (L1) connected to the DC loop circuit 9, the terminal D is connected to the side opposite to the side connected to the line L1 of the DC loop circuit, and the terminal E is connected to the terminal C. It is connected to the line L2 opposite to L1. The connector B'is on the side to which the optional device 9'of the connector 6 is connected, and the terminals C, D, and E are connected to the same symbols of the connector A '. Terminal C
And terminal E are connected to the optional device 9 '. Reference numeral 9 is a DC loop circuit, 9'is an optional device, and the impedance of the internal circuit 9 "is set to the same degree as that of the DC loop circuit. 9" is the internal circuit.

In (b), 8'is a connector B ", which is connected to the connector A '(7) when an external device is not connected. The terminal numbers C, D and E are respectively connector A. The terminals D and E of the connector B ″ (8 ′) are short-circuited.

The operation of the configuration shown in the figure will be described in the "Operation" section. FIG. 2 shows a basic configuration (2) of the present invention, in which a connector (connector 2 in FIG. 1) connected to a receptacle and a connector (connector 6 in FIG. 1) connected to an optional device are connected.
It shows the case where is integrally formed.

(A) shows the configuration when the internal impedance of the option device 16 is substantially equal to the impedance of the DC loop circuit. In (a), 10 is a modem device,
Reference numeral 12 is a connector, and 13 is a connector A, which is the side of the connector 2 formed on the modem device 10. 14
Reference numeral -1 is a connector B, which is connected to the receptacle 15 and the option device 16 of the connector 12. In connector B (14-1), terminal A,
B, C, D and E are respectively connected to the terminals of the connector A (13) having the same reference numeral. 15 is a receptacle,
It is connected to a telephone line. Reference numeral 16 is an external device (optional device).

(B) shows the structure of the connector when no external device is connected. The figure shows only the side connecting the receptacle and the external device. In (b), connector C (14-
2) is integrally connected to the connector A (13), and the terminals A,
B, C, D, and E are connected to the terminals of the connector A (13) having the same reference numerals. Terminal C and terminal E of connector C
Are short-circuited.

The operation of the configuration shown in the figure will be described in the "Operation" section. FIG. 3 shows the basic configuration (3) of the present invention. In the figure,
The same numbers as those in FIG. 2 represent the same parts as those in FIG.

(A) is a case where the optional device has a high impedance. In the figure, 14-3 is a connector D which is connected to the receptacle 15 and the option device 16. The connector D (14-3) is integrally connected to the connector A (13). The terminals C and E are connected to the optional device 16, and the terminals D and E are short-circuited.

(B) shows the connection cable of the receptacle pulled out from the optional device. In the figure, 1
Reference numeral 4-4 is a connector E whose terminals A, B, C and E are connected to an optional device. The connector E (14-4) is integrally connected to the connector A (13). Then, the receptacle pulled out from the option device 16 connects to the telephone line.

In this connection, since the signals of the terminals A and C connecting the option device and the modem device are the same signal, it is possible to share the terminals.

The operation of the configuration shown in the figure will be described in "Operation".

[0022]

The operation of the basic configuration (1) of FIG. 1 will be described. In the figure, connector B (4) is connected to connector A (3) to connect a telephone line and a modem device.

When connecting the optional device 9 ', the connector B' (8) is connected to the connector A '(7). As a result, telephone line-connector B (4) terminal A-connector A
(3) Terminal A-Connector A '(7) Terminal C-Connector B' (8) Terminal C-Option device 9'Internal circuit (9 ")
-Connector B '(8) terminal E-Connector A' (7) terminal E-Connector A (3) terminal B-Connector B (4) terminal B
A telephone line loop is formed. On the other hand, the DC loop circuit 9 is disconnected from the telephone line.

Therefore, if the impedance of the internal circuit of the optional device 9'is matched with the standard of the telephone line, the current flowing through the telephone line can be adapted to the standard even when the optional device 9'is connected.

When the optional device 9'is not connected,
Connect the connector B "(8 ') of (b) to the connector A' (7). As a result, telephone line-terminal B of connector B (4) -terminal A of connector A (3) -DC loop circuit 9" -Terminal D of connector A '(7) -Terminal D of connector B "(8')-Short-circuit line-Terminal E of connector B" (8 ')-Terminal E of connector A' (7) -Connector A '( 7) Terminal B-Connector B (4) terminal B-A telephone line loop is formed, and a current according to the standard flows through the telephone line.

The operation of the basic configuration (2) of the present invention shown in FIG. 2 will be described. When the option device 16 is connected to the modem device 10, the connector B (14-1) is connected to the connector A (13). As a result, connector A (13) and connector B (14
The terminals A and B of -1) are connected to each other, and the modem device 10 and the telephone line are connected via the receptacle 15. In addition, connector A (13) and connector B (14-
The terminals C and E of 1) are connected to each other, and the option device 16 and the modem device 10 are connected. Then, as in the case of FIG. 1, a DC loop of the telephone line is formed by the internal circuit of the option device 16, and the DC loop circuit (17) is disconnected from the telephone line. Therefore, if the impedance of the internal circuit of the optional device is adapted to the standard of the telephone line, it is possible to flow a current that conforms to the standard of the telephone line.

When the optional device 16 is not connected, the connector C (14-2) in (b) is connected to the connector A (13).
Connect to. Terminal C and terminal E of connector C (14-2)
The DC loop circuit 17
Is connected, and a current that matches the standard of the telephone line can flow.

The operation of the basic configuration of FIG. 3 will be described. If the internal circuit of the optional device 16 has high impedance,
As shown in (a), the connector D (14-3) is connected to the connector A (13). Since the terminal D and the terminal E of the connector D (14-3) are short-circuited, both the option device 16 and the DC loop circuit 17 are connected in parallel to the telephone line. However, since the option device 16 has a high impedance, the current determined by the DC loop circuit 17 flows through the telephone line, and the standard current can be passed through the telephone line.

When the optional device 16 is not connected in the configuration shown in the figure, the connector C (14-2) in FIG. 2B is used.
To connector A (13). FIG. 3B shows the case where the receptacle 15 is pulled out from the option device 16.

Connect the connector E (14-4) to the connector A (13)
Connect to. Further, the receptacle 15 pulled out from the option device 16 is connected to the telephone line. As a result, the connection between the telephone line and the optional device 16 and the connection between the telephone line and the internal circuit of the optional device 16 are established, and a current conforming to the standard can be supplied to the telephone line by the same operation as described above.

When the optional device 16 is not connected, the connector C (14-2) shown in FIG. 2B is connected to the connector A (13).

[0032]

EXAMPLE FIG. 4 shows an example (1) of the present invention. In the figure, (a) shows the configuration where the optional device is not connected, and (b) shows the configuration when the optional device is connected.

In (a), 30 is a modem device, 31 is a connector A, and 32 is a connector B. The connector B is connected to the receptacle and has a short-circuit wire for connection with the DC loop circuit. 33 is a receptacle, 34 is a ring detection circuit, 35 is a hook switch, 3
6 is a DC loop circuit, 37 is a loop coil, 38 is a repeater transformer, and 39 is a modem circuit.

In the configuration shown in the figure, by connecting the connector B (32) to the connector A (31), the modem device 30 and the telephone line are connected, and the loop coil 37 and the telephone line are connected off-hook. The operation in this case is similar to that in FIG. The operation of each part of the circuit (ring detection circuit 34, repeater transformer 38, modem circuit 39) is the same as in FIG.

(B) shows a case where the option device 40 is connected to the modem device 30. In the figure, 32 'is a connector B', to which the receptacle 33 and the optional device 40 are connected.

When connecting the option device 40 to the modem device 30, connect the connector B '(32')) to the connector A (3
Connect to 1). The operation is similar to that of FIG.

FIG. 5 shows an embodiment configuration (2) of the present invention. The figure shows a DC loop circuit composed of a pseudo-inductance circuit with active elements.

(A) shows the case where the input side of the pseudo inductance circuit 52 is pulled out to the connector A, and (b) shows the case where the output side of the pseudo inductance circuit 52 is pulled out to the connector A.

In (a), 50 is a modem device, 51 is a connector A, 52 is a pseudo-inductance circuit, and 53 is a diode bridge. Pseudo-inductance circuit 52
In the above, TR1 and TR2 are transistors and form a DC loop in the telephone line. R1, R2
Is a voltage dividing resistor, and includes a transistor TR1 and a transformer T.
It determines the bias voltage of R2. R3 is TR2
Is the emitter resistance of. C1 is a capacitor, which bypasses the AC component and prevents the bias voltages of TR1 and TR2 from varying due to the AC component.

In the configuration shown in the figure, when the terminal C and the terminal D of the connector A (51) are short-circuited, the DC voltage of the telephone line is divided by the resistors R1 and R2 and applied as a bias voltage to TR1 and TR2. , Telephone line-D1-TR1-
TR2-resistor R3-D4-telephone line or telephone line-
D2-TR1-TR2-Resistor R3-D3-A substantially constant DC current flows through the telephone line circuit.

When connecting an optional device, the optional device is connected to the terminals C and E and the terminal C is connected.
And the terminal D are opened (if the optional device has high impedance, the terminals C and D may be short-circuited). As a result, no current flows through the resistors R1 and R2, the base voltage of TR1 becomes equal to the emitter voltage of TR2, and no current flows through the transistors TR1 and TR2.

The diode bridge 53 is a circuit for keeping the direction of the current flowing through the pseudo inductance circuit constant.
In (b), the same numbers as in (a) represent the same parts.

When the optional device is not connected, the terminal D and the terminal E of the connector A (51) are short-circuited. The operation of the pseudo inductance circuit 52 in that case is the same as that in FIG.

When connecting an optional device, terminal C
The optional device is connected to the terminal E and the terminal E, and the terminal D and the terminal E are opened (the terminal D and the terminal E may be short-circuited if the optional device has high impedance). As a result, the outputs of TR1 and TR2 are disconnected from the telephone line, and the telephone line and the option device are connected. If the resistance values of the resistors R1 and R2 are set high, the current can be ignored.

FIG. 6 shows an embodiment (3) of the present invention. The figure is
The direct current circuit in the conventional modem device is configured by the pseudo inductance circuit 63, the function of the repeater transformer is configured by a hybrid circuit of active elements, and the entire modem device is housed in an IC card.

In the figure, 60 is a modem device, 61 is a connector A, 62 is a ring detection circuit, 63 is a pseudo-inductance circuit, and 64 is a hybrid circuit. A balanced circuit on the telephone line side is an unbalanced signal and a modem circuit 65 is provided. And the unbalanced signal output from the modem circuit 65 is output to the telephone line side as a balanced signal. Reference numeral 65 is a modem circuit.

In the hybrid circuit 64, 70 is a differential circuit A, 71 is a differential circuit B, and 72 is a transmission signal cutoff circuit, which prevents the transmission signal from being output from the differential circuit 70 as a reception signal. It is a thing. 80 is a non-inverting input terminal, 81 is an inverting input terminal, 82 is an inverting output terminal, 83
Is a non-inverting output terminal, 84 is a reception signal output terminal, and 85 is a transmission signal input terminal. Reference numerals 86, 87 and 88 are an operational amplifier 1, an operational amplifier 2 and an operational amplifier 3, respectively.

In the configuration of FIG. 6, the connector A (61)
The terminals A and B are connected to the telephone line. When the optional device is not connected, the terminal D and the terminal E of the connector A (61) are short-circuited, and the telephone line and the pseudo inductance circuit 63 are connected (same as the case of the configuration of FIG. 5). Also,
When connecting an optional device, use connector A (6
The optional device is connected to the terminal C and the terminal E of 1) and the terminal D and the terminal E are released (when the optional device has a high impedance, the terminal D and the terminal E are short-circuited) (FIG. 5).
Same as for the configuration).

Next, the operation of the hybrid circuit will be described.
The DC current from the telephone line is cut off by the capacitors C1 and C2. (1) The operation when receiving a signal will be described.

The AC signal component sent from the telephone line is input to the differential circuit A (70) via the capacitors C1 and C2. The received signal is substantially a balanced signal. Then, the signal from the capacitor C1 is input to the non-inverting input terminal 80 of the differential circuit A (70). The signal from the capacitor C2 is input to the inverting input terminal 81 of the differential circuit A (70). The signal input to the inverting input terminal 81 is inverted in polarity and output from the reception signal output terminal 84 with the input signal of the non-inverting input terminal 80 as a reference voltage. Therefore, the differential circuit A (70) outputs the input balanced signal as an unbalanced signal.

(2) The operation of transmitting will be described. The unbalanced transmission signal converted into an analog signal by the modem circuit 65 is the operational amplifier (2) 87 of the differential circuit B (71).
Is inverted, the polarity is inverted, and the inverted signal is output from the inverted signal output terminal. The output of the operational amplifier 87 is input to the inverting input terminal of the operational amplifier 88, the polarity of which is inverted, and the signal of the same polarity as that of the signal input to the transmission signal output terminal 85 is output from the non-inversion output terminal 83. And
The outputs of the operational amplifiers 87 and 88 are output from the telephone line as balanced signals via the capacitors C1 and C2.

[0052]

According to the present invention, it is possible to realize with a simple structure a modem device capable of automatically keeping the current value of a telephone line off-hook within the range of the standard even if an optional device is connected.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration (1) of the present invention.

FIG. 2 is a diagram showing a basic configuration (2) of the present invention.

FIG. 3 is a diagram showing a basic configuration (3) of the present invention.

FIG. 4 is a diagram showing an embodiment (1) of the present invention.

FIG. 5 is a diagram showing an embodiment (2) of the present invention.

FIG. 6 is a diagram showing an embodiment (3) of the present invention.

FIG. 7 is a diagram showing a conventional modem device.

[Explanation of symbols]

 1: Modem device 2: Connector 3: Connector A 4: Connector B 5: Receptacle 6: Connector 7: Connector A'8: Connector B'8 ': Connector B "9': External device (optional device)

Claims (5)

[Claims] 1. In a modem device (1) to which an external device (9 ') having an additional function can be connected, one end of a DC loop circuit (9) for connecting to a telephone line off-hook of a terminal device is connected to the telephone line. Line (L1) and the other end is connected to the terminal D of the connector (6) that connects the external device (9 '), and one end of the DC loop circuit (9) is connected (L
1) is connected to the terminal C of the connector (6), the other line (L2) connected to the telephone line is connected to the terminal E of the connector (6), and the external device (9 ') is not connected Time is
When the terminal D and the terminal E of the connector (6) are short-circuited and an external device (9 ') is connected, the terminal C and the terminal E are connected.
A modem device, characterized in that an external device (9 ') is connected by. 2. A connector (6) for connecting an external device (9 ') and a connector for connecting a telephone line according to claim 1.
A modem device (2) is an integrated connector (12). 3. The external device (9 ') according to claim 1 or 2, which has an internal impedance substantially equal to that of the DC loop circuit (9), and when the external device (9') is connected, the external device (9 ') is connected to the terminal D. A modem device characterized in that the terminal E is released. 4. The terminal D according to claim 1 or 2, when a high impedance external device (9 ') is connected.
And the terminal E are short-circuited. 5. The modem device according to any one of claims 1, 2, 3 and 4, wherein the pseudo inductance circuit and the hybrid circuit are constituted by active elements and are integrated into an IC card.