WO2004080047A1

WO2004080047A1 - Line power-supply modem with backup function

Info

Publication number: WO2004080047A1
Application number: PCT/JP2003/002512
Authority: WO
Inventors: Nobuharu Iinuma
Original assignee: Fujitsu Limited
Priority date: 2003-03-04
Filing date: 2003-03-04
Publication date: 2004-09-16

Abstract

A modem line connection apparatus comprises a line power-supply modem that operates by utilizing a line current flowing through a telephone line; current detecting means that detects the line current during the use of the telephone line and outputs a switch signal when the value of the detected current is less than the operatable current of the line power-supply modem; and current supplying means that is caused to be conductively coupled to the telephone line in response to the switch signal and supply a constant current to the line power-supply modem.

Description

Specification

Line-fed modem with backup function

The present invention relates to a computer system provided with a line-feeding modem that operates using line current flowing through a telephone line. More specifically, the line-feeding modem of the computer system is connected to a private telephone line network or a general public network. The present invention relates to a modem line connection device for ensuring the operation of a line feed modem when connected to a telephone line. Background art

Portable information devices such as notebook personal computers often have a built-in modem, so they carry notebook personal computers (hereinafter referred to as PCs) and connect them to telephone lines in offices and other places where they go. Usage forms for communicating over networks are increasing.

Telephone lines include analog telephone lines such as public telephone lines and private telephone lines such as digital PBX lines.When connecting a modem to a network, connect the modem to a telephone line that supports the modem. Must.

2. Description of the Related Art In recent years, a line-powered soft modem (hereinafter referred to as a line-powered modem) has been put into practical use as a modem built in a notebook personal computer or the like. A line feed modem is a modem having a line interface that operates using line current supplied to a telephone line, and achieves low cost and low power consumption.

Some private telephone networks used by companies, such as those that do not supply any current to private telephone lines in order to reduce costs and reduce power consumption, and that the line current values of public telephone lines (Specified value) When set to supply a lower line current.

The line current of analog lines such as public telephone lines is set to 20-120 mA according to the standard, so when connecting to public telephone lines, the line-powered modem works without any problem. However, when connecting to a private telephone network such as a company, The problem that the dem does not work can occur.

For example, assume that the line power supply modem is set to operate if the line current flowing through the telephone line is 15 mA or more. When connecting to a private telephone network where line current is not supplied, or when the line current is set to a current level lower than the standard value of the public telephone line (for example, about 10 to 13 mA) This line-powered modem does not work when connected to the local telephone network.

In the conventional method, when a line-fed modem is connected to a private telephone line network to which no current is supplied or a private telephone line network to which a lower line current is supplied than a public telephone line, the line power is supplied to the line-supplying modem. There was a problem that the modem did not work and communication on the network was not possible.

As a conventional technique related to the present invention, a line current limiting circuit is disclosed in Japanese Patent Laid-Open Publication No. 2001-309930. This line current limiting circuit limits the overcurrent flowing through the modem if the modem is mistakenly connected to an unsupported telephone line, and if the modem is reconnected to a compatible telephone line, Facilitates its return.

Further, Japanese Patent Application Laid-Open No. 2000-3242453 discloses a modem line connection circuit for protecting an internal circuit of a public telephone line modem. This modem line connection circuit prevents overcurrent from flowing through the modem in order to prevent damage to the circuit if the public telephone line modem is accidentally connected to the private telephone network. To the user that the overcurrent is flowing to the user. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a backup function even when connected to a private telephone network that does not satisfy the line current specification of a public telephone line. It is an object of the present invention to provide a modem line connection device capable of operating a power feeding modem.

In order to solve the above 1 problem, the modem line connection device of the present invention detects a line feeding modem that operates by using a line current flowing through a telephone line, and detects the line current when using an IB telephone line. The detected current value is less than the operable current of the line-fed modem And a current supply unit that supplies a constant current to the line feed modem in accordance with the signal output from the current detection unit.

Further, in order to solve the above-mentioned problems, a modem line connection device of the present invention includes a line feed modem that operates using a line current flowing through a telephone line, and a line current detected when the telephone line is used. Current detection means for outputting a signal when the detected current value is less than the operable current of the line-powered modem; and setting to a conductive state with the telephone line according to the signal output from the current detection means. And a normal modem that operates independently of the line current.

In the modem line connection device of the present invention, the line current is detected when the telephone line is used, and if the detected current value is a current value at which the line-powered modem cannot operate, a predetermined current is supplied to the line-powered modem. To enable communication. According to the modem line connection device of the present invention, even when connected to a telephone line network to which line current is not supplied or a current is lower than that of a public telephone line and power is not supplied, the line power supply modem can be used. Operable, enabling communication over a network. BRIEF DESCRIPTION OF THE FIGURES

Other objects, features, and advantages of the present invention will become apparent from the following detailed description of the invention with reference to the accompanying drawings.

FIG. 1 is a diagram showing a modem line connection device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a modem line connection device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a schematic configuration of a computer system having a built-in modem. FIG. 4 is a block diagram showing an example of a line feed modem in the modem line connection device of the present invention.

FIG. 5 is a block diagram showing an example of the current detection circuit in the modem line connection device of the present invention.

FIG. 6 is a block diagram showing a functional configuration of the modem.

Figure 7 illustrates the differences between the components of a normal modem and a line-fed modem. FIG.

FIG. 8 is a flowchart for explaining a line-powered modem control procedure executed by the modem line connection device of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

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

Figure 3 shows the schematic configuration of a computer system with a built-in modem.

The computer system 100 shown in FIG. 3 includes a CPU 50, a north bridge 51, a south bridge 52, a graphics controller 53, an input device 54 such as a mouse and a keyboard, an audio device 55, a modem card 20, a memory, and the like. 5, a drive 57 such as a hard disk drive (HDD) or a CD-ROM drive, a LAN interface 58, and an IEEE 1394 interface 59.

The north bridge 51 and the graphics controller 53 are connected to each other by an AGP (Acce1eRated-GrapHics-Port) bus. The south bridge 52 and the input device 54 such as a mouse and a keyboard are connected by a USB (Universal1_Serial1_Bus) node. Further, the south bridge 52 and the hard disk drive (HDD) 57 are connected to each other by an IDE (Integra ate d e D e v i c e L e c e t r on i c s). The LAN interface 58 and the IEE 1394 interface 59 and the south bridge 52 are connected by a PCI (Peripheral_Compo- nent) node. Further, the audio device 55 and the modem port 20 and the south bridge 52 are connected by an AC link path or a PCI bus.

Here, in the computer system 100 of FIG. 3, the modem line connection device of the present invention is provided on a modem card 20 provided with a line feed modem. The modem card 20 built in the computer system 100 is connected to the AC link path or the PCI path of the computer system 100.

FIG. 1 shows a modem line connection device according to a first embodiment of the present invention. 1 is configured as an integrated circuit on a modem card 20 including a line feeding modem 10. The modem card 20 includes a line feed modem 10, a constant current circuit 12, and a current detection circuit 14.

As shown in Figure 1, the system terminal 13 of the modem card 20 is connected to the computer system bus 22 (AC link bus or PCI bus), and the line terminal of the modem card 20 is a public telephone. It is connected to the telephone network of the line network or local telephone line network. For convenience of explanation, in the example of FIG. 1, it is assumed that the line side terminal of the modem card 20 is connected to the telephone lines 19a and 19b of the extension exchange 24 in the private telephone line network.

In the modem line connection device of FIG. 1, the line feed modem 10 is a line feed type software modem (to be described later) that operates using the line current flowing through the telephone line. The specifications of the line-powered modem 10 of this embodiment are set to operate when the line current flowing through the telephone line is equal to or more than the operable current (for example, 15 mA). As mentioned earlier, when connecting to a private telephone network where line current is not supplied, or when the line current is lower than the normal level of the public telephone line (for example, 10-13 mA) ), This line-powered modem 10 does not operate.

Therefore, in the modem line connection device of this embodiment, the constant current circuit 12 is connected to the telephone line 19a via the switch 16 while the first terminal 12a is connected to the second terminal 1a. 2 b is connected to the bus 22 of the computer system via the system side terminal 13.

The current detection circuit 14 has an input terminal 14 a connected to the telephone line 19 a and an output terminal 14 b connected to the switch 16. The current detection circuit 14 detects the line current of the telephone line 19a when using the telephone line, and switches the switching signal when the detected current value is less than the operable current of the line feeding modem 10. Output to 16 and switch 16 is turned on to operate. If the detected current value is equal to or greater than the operable current of the line feed modem 10, the switch 16 is not switched and the conduction between the telephone line 19a and the constant current circuit 12 is turned off. It is kept as it is. The constant current circuit 12 responds to the switching signal output from the current detection circuit 14 Since it is set to a conductive state with the line 19a, the constant current circuit 12 uses a current supplied from the computer bus 22 via the system side terminal 13 to generate a constant current (a line feed modem). (Current value greater than the operable current of 10) to the line feed modem 10.

Therefore, according to the modem line connection apparatus of the embodiment shown in FIG. 1, when the line current is not supplied, or when connected to a telephone line network which is lower in power than the public telephone line and is not supplied with power! Also, the line-powered modem 10 is operable and enables communication over the network. Further, when communication by the line feed modem 10 is not performed, the conduction state between the constant current circuit 12 and the telephone line 19a is set to the off state, so that power consumption can be reduced.

FIG. 2 shows a modem line connection device according to a second embodiment of the present invention.

As shown in FIG. 2, the modem line connection device of this embodiment is also configured as an integrated circuit on a modem card 20 including a line feed modem 10. The modem card 20 includes a line-powered modem 10, a normal modem 11, and a current detection circuit 14. The system-side terminal 13 of the modem card 20 is connected to a bus 22 of the computer system, and the line-side terminal of the modem card 20 is connected to a telephone line of a public telephone network or a private telephone network. For convenience of explanation, in the example of FIG. 2, it is assumed that the line side terminal of the modem card 20 is connected to the telephone lines 19a and 19b of the extension 24 in the private telephone network.

In the modem line connection device of FIG. 2, the line feed modem 10 is a line feed type soft-modem that operates using line current flowing through the telephone line. The specifications of the line-powered modem 10 of this embodiment are set to operate when the line current flowing through the telephone line is equal to or higher than the operable current (for example, 15 mA). As described above, if the line current is not supplied, if the terminal is connected to the private telephone network, or if the line current is lower than the standard value of the public telephone line (for example, 10-1 This line feed modem 10 does not operate when connected to the private telephone network set to about 3 mA).

In the modem line connection device of this embodiment, the normal modem 11 is connected in parallel with the line feed modem 10, and the first terminals 11a, 11b of the normal modem 11 are connected. While being connected to the telephone lines 19a and 19b via the first switches 18a and 18b, the second terminal 11c is connected to one end of the second switch 15 and I have. The second switch 15 is connected to a bus 22 of the computer system via a system terminal 13.

As in the embodiment of FIG. 1, the current detection circuit 14 has an input terminal 14a connected to the telephone line 19a, and an output terminal 14b. It is connected to both the first switch 18 a, 18 b and the second switch 15. The current detection circuit 14 detects the line current of the telephone line 19a when using the telephone line, and outputs a switching signal when the detected current value is less than the operable current of the line feeding modem 10. The first switch 18a, 18b and the second switch 15 are output, and both the switches 18a, 18b and the switch 15 are turned on to operate.

If the detected current value is equal to or greater than the operable current of the line feed modem 10, the switches 18a, 18b and 15 are not switched and the telephone lines 19a, 1 are not switched. The conduction state between 9b and the normal modem 11 is kept off. In this state, the line feed modem 10 can operate by using the line current flowing through the telephone lines 19a and 19.

Therefore, when the detected current value is less than the operable current of the line-powered modem 10, the modem 11 normally responds to the switching signal output from the current detection circuit 14 by using the first terminal 1. The 1a and lib sides are set to the conductive state with the telephone lines 19a and 19b, and the second terminal 11c side is set to the conductive state with the bus 22 of the computer system. In this state, the modem 11 can operate normally regardless of the line current of the telephone line, and can start communication on the network.

Therefore, according to the modem line connection device of the embodiment shown in FIG. 2, when the line current is lower than that of the public telephone line or the line is connected to a telephone line network which is not supplied with the current, the line is not supplied. Instead of the power-supply modem 10, the normal modem 11 is set to a conductive state and is operable, thereby enabling communication on the network. Further, when the communication by the line feed modem 10 is not performed, the conduction state between the normal modem 11 and the telephone lines 19a and 19b is set to the off state, so that power consumption can be reduced. Next, the difference between the configuration of the normal modem 11 and the configuration of the line feed modem 12 in the embodiment of FIG. 2 will be described.

FIG. 6 is a diagram for explaining a functional configuration of a general modem.

As shown in FIG. 6, the modem 80 includes a controller section 81, a modulation / demodulation section 82, and a line interface section 83. The controller section 81 is a control section (including the CPU) of the modem 80, and controls the operation of the modem 80. The modulation / modulation unit 82 is a function block that provides a function of modulating the signal transmitted to the computer system (PC) telephone line and a function of demodulating the signal received from the telephone line to the computer system (PC). is there. The line interface unit 83 is a functional block for performing a communication interface function between a computer system (PC) and a telephone line.

FIG. 7 is a diagram for explaining a difference between components of a normal modem and a line-powered modem.

Fig. 7 shows the transition of the modem components from the initial system to the latest.Specifically, the differences in the components of the initial modem, DSP modem, controllerless modem, software modem, and line-powered software modem are shown. It is shown schematically. The initial modem consists of a controller unit 81 using an MPU (microprocessor unit), a modulating / modulating unit 82 using a DSP (microprocessor dedicated to digital signal processing) and a dedicated LSI (large-scale integrated circuit), and analog LSI and DAA ( It is composed of a line interface unit 83 and power by D irect—Access—Arrangement). Early modems have high power consumption and cost disadvantages.

The DSP modem includes a controller section 81 and a variable tone section 82 using a general-purpose DSP, and a line interface section 83 using a CODEC (encoding / decoding unit) and DAA. DSP modems consume less power and cost less than early modems.

The controllerless modem is composed of a controller section 81 using a CPU, a modulating / modulating section 82 using a dedicated DSP, and a line interface section 83 using CODEC and DAA. Controllerless modems are less than DSP modems. In addition, power consumption is low and costs are reduced. The normal modem 11 in the embodiment of FIG. 2 is composed of, for example, components of the controllerless modem. This controllerless modem is a common example of a modem that operates regardless of the line current flowing through the telephone line.

The software modem is composed of a controller unit 81 and a modulating and multi-toning unit 82 using a CPU, and a line interface unit 83 using a CODEC and DAA, etc., and operates based on a program (software) stored in the memory of the CPU. I do. Software modems consume even less power and cost less than controllerless modems.

The line-powered software modem is composed of a controller unit 81 and a modulator / demodulator unit 82 using a CPU, and a clock and interface unit 83 using a CODEC and silicon DAA. Works. This time, the power supply software modem is the line power supply modem 10 of the present invention, and realizes the lowest power consumption and the lowest cost among the various modems in FIG. However, as described above, the line-powered software modem operates by using the line current flowing through the telephone line. Therefore, when the line current of the telephone line is less than the operable current, the line interface unit 83 is activated. There is a problem that it does not work. FIG. 4 shows an example of the line feed modem 10 in the modem line connection device of the present invention. Specifically, FIG. 4 shows a configuration example of the CODEC and silicon DAA unit 60 corresponding to the line interface unit 83 (FIG. 6) in the above-described line-powered software modem.

As shown in FIG. 4, the CODEC and silicon DAA unit 60 includes a system-side chip 61 connected to the computer system side, a line-side chip 62 connected to the telephone line side, and a capacitance connected between both chips. Including 63.

In the circuit shown in FIG. 4, the system-side chip 61 includes a clock circuit (CLK) 64, a digital interface circuit 65, a controller interface circuit 66, and an isolation interface circuit 67. Including. The line-side chip 62 includes a ringing signal detection circuit (RI NG—DETECT) 68, an ACZDC termination circuit 69, an ADZDA converter 70, Line 4-wire hybrid circuit 71 and isolation interface circuit 72 are included.

As described above, the line interface of the line-fed modem in FIG. 4 is set to operate if the line current flowing through the telephone line is equal to or greater than the operable current (for example, 15 mA).

FIG. 5 shows an example of the current detection circuit 14 in the modem line connection device of the present invention. The current detection circuit 14 shown in FIG. 5 has an input signal line 14a connected to a telephone line and an output signal line 14 connected to a switch 16 (or a switch 18a, 18b). b. The current detection circuit 14 includes a determination data section 41, a determination section 42, and a current sensor 43.

The current sensor 43 detects the line current from the input signal line 14a, and outputs a signal indicating the level of the detected current value to the determination unit 42. The determination data section 41 is a storage section that holds a reference value of the operable current of the line feed modem 10.

The determination unit 42 compares the detected value of the line current indicated by the signal output from the current sensor 43 with the reference value of the operable current held in the determination data unit 41, and outputs a signal indicating a determination result. To the output signal line 14b. The output signal of the determination unit 42 functions as a switching signal for controlling the switching operation of the switch 16 (or the switches 18a and 18b).

That is, when the detected value of the line current is less than the reference value of the operable current of the line-powered modem 10, the determination unit 42 outputs an on-state switching signal. In this case, in response to the switching signal, the switch 16 is switched to the on state, the conduction state between the constant current circuit 12 and the telephone line is turned on, and the line feeding modem 10 has the constant current circuit 12 Is supplied.

Conversely, when the detected value of the line current is equal to or larger than the reference value of the operable current of the line-powered modem 10, the determination unit 42 outputs an off-state switching signal. In this case, the switch 16 remains off, and the constant current circuit 12 and the telephone line are set to a non-conductive state. When communication by the line feed modem 10 is not performed, the current from the constant current circuit 12 is not supplied to the line feed modem 10, so that power consumption can be reduced. FIG. 8 is a flowchart for explaining a line-powered modem control procedure executed by the modem line connection device of the present invention.

The line-powered modem control procedure in FIG. 8 is executed by causing a control unit (hereinafter, referred to as a CPU) of the modem line connection device of the present invention to execute according to a program recorded in a recording unit (not shown). Each part of the modem line connection device shown in Fig. 1 or Fig. 2 is controlled. Alternatively, the configuration may be such that the modem line connection device shown in FIG. 1 or 2 executes the line feeding modem control procedure of FIG. 8 as hardware.

Hereinafter, a case where the modem line connection device of the first embodiment of FIG. 1 is controlled will be described. The same applies to the case where the modem line connection device of FIG. 2 is controlled, so the description thereof is omitted.

In the control procedure of FIG. 8, first, when a signal indicating an off-hook state is detected from the telephone line, execution of line-powered modem control is started (step Sl). Step S1 is repeatedly performed until a signal indicating the off-hook state is detected.

When a signal indicating the off-hook state is detected in step S1, the current detection circuit 14 determines that the detection value of the line current by the sensor unit 43 is the reference value of the operable current of the line feed modem 10 (the judgment data unit 4). It is determined whether the value is equal to or greater than (the value held in 1) (step S2).

If it is determined in step S2 that the detected value of the line current is less than the reference value of the operable current of the line-powered modem 10 (NO), the current detection circuit 14 is activated so that the line current backup function operates. Outputs an on-state switching signal (Switch ON) to the switch 16. Switch 16 switches on, constant current circuit 12 conducts with the telephone line, and supplies a constant current to line-powered modem 10 using the current supplied from PC path 22 (Step S3).

In step S3, a display indicating that the line current is less than the reference value of the operable current of the line feed modem 10 may be sent to the user.

On the other hand, if it is determined in step S2 that the detected value of the line current is equal to or greater than the reference value of the operable current of the line-powered modem 10, (YES;), the line current backup function is not required, The switching signal output from the current detection circuit 14 to the switch 16 remains off. In this case, switch 16 remains off and There is no conduction between the current circuit 12 and the telephone line. The line feed modem 10 can operate using the line current flowing through the telephone line.

After step S3 is executed, or when the determination result of step S2 is YES, the line-powered modem 10 starts operating and sends a dial signal of a communication partner on the network. (Step S 4). Then, the communication according to the normal communication procedure is started (step S5).

As described above, according to the modem line connection device of the present invention, even when connected to a telephone line network in which line current is not supplied or a current is lower than a public telephone line and power is not supplied, The line-powered modem is operable and enables communication over the network. Also, when communication is not performed by the line feed modem, the conduction state between the constant current circuit and the telephone line is set to the off state, so that power consumption can be reduced.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made within the scope described in the following claims.

Claims

The scope of the claims

1. A line-powered modem that operates using the line current flowing through the telephone line, and when the line current is detected when the telephone line is used, and the detected current value is less than the operable current of the line-powered modem. Current detection means for outputting a signal; current supply means for supplying a constant current to the line power modem in accordance with the signal output from the current detection means.

A modem line connection device comprising:

2. A line-powered modem that operates using the line current flowing through the telephone line, and when the line current is detected when the telephone line is used, and the detected current value is less than the operable current of the line-powered modem. A current detecting means for outputting a signal to the telephone line according to the signal output from the current detecting means, and a normal modem operating independently of the line current.

A modem line connection device comprising:

3. The current supply means includes a switch for setting a conduction state between the current supply means and the telephone line to an ON state in accordance with the signal output from the current detection means. The modem line connection device described in 1.

4. The current supply means has a switch for setting a conduction state between the current supply means and the telephone line to an off state when communication by the line power supply modem is not performed. The modem line connection device described in the above.

5. A first switch for setting a connection state between the normal modem and the system to an off state when the communication by the line-powered modem is not performed; and a normal switch when the communication by the line-powered modem is not performed. The modem according to claim 2, further comprising a second switch for setting a conduction state between the modem and the telephone line to an off state.

Ten

Fifteen

20

twenty five