CN101860632B - Communication terminal apparatus - Google Patents

Abstract

The present invention provides a simple loop structure and message receiving and transmission for a communication terminal apparatus thereby obtaining low cost of the communication terminal apparatus. DC current is supplied to a semiconductor DAA40 through DC current supplying facility 90 such as a fax device 1 in the communication terminal apparatus. For preventing the leakage of the supplied DC current to the side of the loop network 85, DC current separation facilities 32-1 and 32-2 are provided between the DC current supplying facility 90 and the side of the loop network 85. Thus the communication terminal apparatus using the fax device 1 of semiconductor DAA40, etc. in the loop I/F part 30 can perform communication even when connected with the loop network 85 (such as a private line) without DC current overlapping.

Description

Communication terminal

Technical field

The present invention relates to a kind of communication terminal, it is netting with loop the circuit interface portion (hereinafter referred to as " I/F portion, loop ") be connected, and uses semiconductor DAA (Data Access Arrangement) to carry out the transmitting-receiving of communication data.

background technology

In communication terminal in the past, the picture unit etc. that such as following patent documentation 1 is recorded, uses semiconductor DAA to receive and dispatch communication data in the I/F portion be connected with telephone wire.

[patent documentation 1] Japanese Unexamined Patent Publication 2003-298787 publication

But, in communication terminal in the past, due to semiconductor DAA be utilize come self-loop direct current and work, therefore problem is not had when there being the dissipating public loop of direct current overlap, but at use dedicated circuit or when using encryption device etc. between loop, semiconductor DAA do not have direct current overlapping in loop, so just cannot work.Therefore, employing the communication terminal of semiconductor DAA with loop-coupled I/F portion, if be connected to dedicated circuit etc. when not having in the loop of direct current overlap, communication just cannot be carried out.

summary of the invention

The feature of communication terminal of the present invention is, when such as using dedicated circuit in the net of loop and use encryption device etc. between loop, for semiconductor DAA, then make the direct current from power supply in device overlapping by loop signal, further, when use has the loop of direct current overlap as common return etc., then use the direct current of self-loop that semiconductor DAA is worked; When use does not have the loop of direct current overlap, then make from the direct current in device overlapping, thus semiconductor DAA is worked.Therefore, communication terminal of the present invention is provided with semiconductor DAA in the I/F portion, loop carrying out the transmitting-receiving of data with side, loop, for converting output resistance and output impedance makes it consistent with described loop.This communication terminal have select the selection portion of described loop classification, the direct current supply mean supplying direct current to described semiconductor DAA, the direct current separation means stoping the described direct current supplied by described direct current supply mean to flow out to side, described loop and according to the described loop selected by described selection portion, switch and the loop classification switch means of connection status of described loop and described semiconductor DAA.

Invention effect

Pass through the present invention, direct current is supplied to semiconductor DAA by the direct current supply mean of communication terminal inside, flow out to net side, loop for preventing the direct current be supplied to, again direct current separation means is set between direct current supply mean and net side, loop, therefore, even if be connected to by the communication terminal employing semiconductor DAA in I/F portion, loop in the loop net not having direct current overlap, also communication work can be carried out.So just can be controlled by fairly simple loop structure and transmitting-receiving letter, reduce the cost of communication terminal.

Accompanying drawing explanation

Fig. 1 is the block figure representing the general configuration such as embodiment of the present invention one I/F portion, loop in fig. 2;

Fig. 2 is the oblique view of communication terminal (such as picture unit) overall appearance representing embodiment of the present invention one;

Fig. 3 is the block figure of the loop structure representing Fig. 2;

Fig. 4 is the action flow chart of the picture unit representing the execution mode one shown in Fig. 1 ~ Fig. 3;

Fig. 5 is the block figure representing the general configuration such as execution mode two I/F portion, loop in figure 3;

Fig. 6 is the flow chart of the action representing the picture unit of execution mode two in Fig. 2, Fig. 3, Fig. 5;

Fig. 7 is the block figure representing execution mode three general configuration such as I/F portion, loop and control part in figure 3;

Fig. 8 is the flow chart representing the picture unit action of execution mode three in Fig. 2, Fig. 3 and Fig. 7.

Embodiment

With reference to the accompanying drawings, preferred forms of the present invention is described.But accompanying drawing is only and is described use, scope of the present invention includes but not limited to content shown in accompanying drawing.

Execution mode one

Fig. 2 is the oblique view of the communication terminal overall appearance representing embodiment of the present invention one, and Fig. 3 is the block figure of the loop structure representing Fig. 2.

The communication terminal of execution mode 1 is picture unit 1, is connected with loop net 85.The inside of picture unit 1 is provided with data/address bus 2.Data/address bus 2 with for printing the printing portion 3 of the image received, for the original copy of transmission being converted to the reading part 4 of view data, the display part 5 be made up of the liquid crystal (LCD) and light-emitting diode (LED) etc. of the working condition of indication device, operating portion 6, for storing the video memory 7 sending image information and receive image information, for remembering the reading private memory (hereinafter referred to as " ROM ") 8 of various control program, the memory (hereinafter referred to as " RAM ") 9 that can read and write at any time, coding/decoding portion 10, modulator-demodulator 11, and control part 20 etc. is connected.In modulator-demodulator 11, connect and the I/F portion, loop 30 having loop net 85 side to carry out the transmitting-receiving of data.

Here, operating portion 6 by the numeric keypad for dialling, for send various action indicate start/stop key etc. form.RAM9 is the memory for various necessary data, the overall service area controlled of picture unit etc.Coding/decoding portion 10 has transmission image information with MH (modified Huffman code), MR (modified READ:modified relativeelement address designate), the coded system of the regulation such as MMR (modified modified READ:relativeelement address designate) coded system is compressed, and by the image information of reception with MH, MR, the decoding process of the regulation such as MMR decoding process carries out the function extended.

Modulator-demodulator 11 has the function of being modulated fax (hereinafter referred to as " the FAX ") data sending information to loop net 85 and the FAX data received from loop net 85 by loop I/F portion 30 demodulation by I/F portion, loop 30.Control part 20 is made up of central processing unit (hereinafter referred to as " CPU ") etc., has the function controlled picture unit entirety according to the various control programs stored in ROM8.By this control part 20, also can control I/F portion, loop 30.When control part 20 sends instruction, I/F portion, loop 30 can carry out the network control specified.

Fig. 1 is the block figure representing the general configuration such as embodiment of the present invention one I/F portion, loop 30 in fig. 2.

The direct current opposing that control part 20 has output switching signal S21, S22 respectively switches indicatory device 21 and impedance switching indicatory device 22 etc., for control loop I/F portion 30.

I/F portion, loop 30 has the pair of terminal L1, the L2 that are connected with loop net 85, is connected with two-terminal 31T1, the 31T2 of the surge protection elements 31 such as rheostat between this terminal L1, L2.In addition, on two-terminal L1, L2, be connected to terminal 32T1,32T3 of direct current separation means 32-1,32-2 one end, on terminal 32T2,32T4 of the other end of direct current separation means 32-1,32-2, be connected with semiconductor DAA40 and direct current supply mean 90.

Each direct current separation means 32-1,32-2 are the loops stoping the direct current supplied by direct current supply mean 90 to flow out to loop net 85.The direct current separation means 32-1 of one end has capacitor 32-1a for blocking direct current and for stoping the resistance 32-1b of impulse current, they are connected in series between two-terminal 32T1,32T2; Equally, the direct current separation means 32-2 of the other end has capacitor 32-2a for blocking direct current and for stoping the resistance 32-2b of impulse current, they are connected in series between two-terminal 32T3,32T4.In addition, above-mentioned direct current separation means 32-1,32-2 are made up of capacitor 32-1a, 32-2a and resistance 32-1b, 32-2b respectively, as long as but direct current can be separated, other loop also can be used to form.

The semiconductor DAA40 be connected with terminal 32T2,32T4 of direct current separation means 32-1,32-2 is silicon semiconductor element, it has multiple resistance and multiple impedance component, based on the program control of control part, in multiple resistance and multiple impedance component, select suitable resistance and impedor combination, thus output resistance and the output impedance in the loop (such as dissipating public loop) conforming to each standard-required can be converted to.When not using semiconductor DAA40, loop net 85 is connected by transformer with I/F portion, loop 30.At this moment, the transformer loaded need conform to each standard of dissipating public loop.But when such as present embodiment one uses semiconductor DAA40, substrate then without the need to observing each standard of dissipating public loop, carries out semiconductor transformation by semiconductor DAA40 so exactly, instead of uses transformer.

The control part side loop 80 that this semiconductor DAA40 carries out the diode bridge 50 of rectification, the loop net side loop 60 being connected to the outlet side of this diode bridge 50, the insulation transport unit 70 being connected to the outlet side of this loop net side loop 60 and the outlet side that is connected to this insulation transport unit 70 by the direct current supplied by loop net 85 (such as the common network in the 2nd loop) is formed, and it can be connected to such as each direct current separation means 32-1, between two-terminal 32T2,32T4 of 32-2.

Here, diode bridge 50 has 4 diodes 51 ~ 54, they are bridged between a pair AC input terminal 50T1,50T2, the AC input terminal 50T1 of one side is connected with the terminal 32T2 of direct current separation means 32-1, and the AC input terminal 50T2 of the opposing party is connected with the terminal 32T4 of direct current separation means 32-2.Diode bridge 50+side lead-out terminal 50T3 and-side lead-out terminal 50T4 on, be connected with loop net side loop 60.

Loop net side loop 60 have with diode bridge 50+hybrid network (hybrid network) 61 that side lead-out terminal 50T3 and-side lead-out terminal 50T4 is connected, the insulation I/F portion 63 that is connected to analog/digital conversion on this hybrid network 61 and digital-to-analog transformation component (hereinafter referred to as " AD/DA converter section ") 62 and is connected on this AD/DA converter section 62.

Hybrid network 61 has D.C. resistance switch means 61-1 and impedance switch means 61-2.D.C. resistance switch means carries out the switching of D.C. resistance according to the switching signal S21 that D.C. resistance switching indicatory device 21 sends, and impedance switch means 61-2 carries out the switching of impedance according to the switching signal S22 that impedance switching indicatory device 22 sends.D.C. resistance switch means 61-1 has such as low D.C. resistance 61-1a and high D.C. resistance 61-1b, and they switch to either party by the switch 61-1c of the action based on switching signal S21.Impedance switch means 61-2 has such as Low ESR 61-2a and high impedance 61-2b, and they switch to either party by the switch 61-2c of the action based on switching signal S22.

This hybrid network 61 is connected with insulation transport unit 70 by AD/DA converter section 62 and insulation I/F portion 63.Insulation transport unit 70 is with the D.C. isolation of loop net side loop 60 and control part side loop 80 and the part transmitted data, signal etc.

Control part side loop 80 has the insulation I/F portion 81 be connected with insulation transport unit 70; Be connected with this insulation I/F portion 81, (TX) is transmitted and transmitting-receiving letter interface portion (hereinafter referred to as " TX/RXIF portion ") 82 of collect mail (RX) to modulator-demodulator 11; And be connected, for receiving the control interface portion (hereinafter referred to as " control IF portion ") 83 etc. of the control signal of control part 20 with insulation I/F portion 81.

The direct current supply mean 90 of direct current is supplied to I/F portion, loop 30, the power supply unit 91 supplied by the direct current in picture unit 1 and adjustment are (such as, increasing) power supply of this power output interface adjustment loop 92 forms, and this power supply adjustment outlet side in loop 92 is connected with AC input terminal 50T1,50T2 side of diode bridge 50.Power supply adjustment loop 92 is the loops preventing from the alternating component of self-loop net 85 to enter power supply unit 91, can be made up of such as a pair choke (choke coil) 92a, 92b.

The feature of execution mode one is, when use does not have the 1st loop (such as industrial siding) of direct current overlap as loop net 85, then overlapping in industrial siding by the direct current from the power supply in device, thus make semiconductor DAA40 carry out work.Referring to Fig. 4, the action of execution mode one is described.

Fig. 4 is in the picture unit 1 shown in Fig. 1 ~ Fig. 3 of execution mode one, and when the picture unit as originator sends calling, the picture unit 1 as destination switches to action flow chart during automatic reception.

Terminal L1, L2 of picture unit 1 are connected with the loop net 85 of the industrial siding such as not having direct current overlapping.Switching signal S21, the S22 of indicatory device 21 and the output of impedance switching indicatory device 22 is switched in advance by D.C. resistance, switch switch 61-1c, the 61-2c in D.C. resistance switch means 61-1 and impedance switch means 61-2, the setting output resistance corresponding with loop net 85 and output impedance.

Picture unit 1 is started working, and is holding state in step ST1, waits for the arrival of the collection of letters commencing signal of self-loop net 85.

In step ST2, because direct current supply mean 90 supplies direct current to semiconductor DAA40, semiconductor DAA40 is can operating state.Collection of letters commencing signal is detected by modulator-demodulator 11.When collection of letters commencing signal is after the arrival of loop net 85, input collection of letters commencing signal by terminal L1, L2.Collection of letters commencing signal, via direct current separation means 32-1,32-2, diode bridge 50 and hybrid network 61, is transferred into AD/DA converter section 62.After collection of letters commencing signal is transferred into AD/DA converter section 62, the collection of letters commencing signal being originally analog signal is converted to digital signal by AD/DA converter section 62.Be converted into the collection of letters commencing signal after digital signal via insulation I/F portion 63, side, loop, insulation transport unit 70, insulation I/F portion 81, control part side and TX/RXIF portion 82, be transferred into modulator-demodulator 11.The arrival of the collection of letters commencing signal after modulator-demodulator 11 detects and is converted into digital signal.

In step ST3, after modulator-demodulator 11 detects collection of letters commencing signal, confirm whether this collection of letters commencing signal is consistent with the frequency range of collection of letters commencing signal.When consistent with the frequency range of collection of letters commencing signal, enter step ST4.

In step ST4, modulator-demodulator 11 pairs of signal ranks confirm, check whether the rank ensuring more than threshold value.After being confirmed to be the rank ensuring more than threshold value, enter step ST5.

In step ST5, start FAX communication.FAX communication carries out according to the suggestion as international standard of ITU (International Electrical communication associating).The collection of letters signal arrived by loop net 85 inputs from terminal L1, L2.Collection of letters signal, via direct current separation means 32-1,32-2, diode bridge 50 and hybrid network 61, is transferred into AD/DA converter section 62.After collection of letters signal is transferred into AD/DA converter section 62, the collection of letters signal being originally analog signal is converted to digital signal by AD/DA converter section 62.Be converted into the collection of letters signal after digital signal via insulation I/F portion 63, side, loop, insulation transport unit 70, insulation I/F portion 81, control part side and TX/RXIF portion 82, be transferred into modulator-demodulator 11.

The letter signal exporting loop net 85 to is exported as digital signal by modulator-demodulator 11.The digital signal exported by modulator-demodulator 11, via TX/RXIF portion 82, insulation I/F portion 81, control part side, insulation transport unit 70 and insulation I/F portion 63, side, loop, is transferred into AD/DA converter section 62.Digital signal is converted into analog signal at AD/DA converter section 62, via hybrid network 61, diode bridge 50 and direct current separation means 32-1,32-1, is transferred into terminal L1, L2, and is exported to loop net 85 by as letter signal.

In step ST6, after FAX has communicated, be then back to step ST2, wait for the arrival of next signal.

Logical execution mode one, can obtain the effect described in following (a) ~ (c):

A () supplies direct current by the direct current supply mean 90 of picture unit 1 inside to semiconductor DAA40.Flow out to loop net 85 side for avoiding the direct current supplied, direct current separation means 32-1,32-2 is provided with between direct current supply mean 90 and loop net 85, therefore, the picture unit 1 of semiconductor DAA40 is used in I/F portion, loop 30, even if connect with the loop net 85 (such as industrial siding) not having direct current overlapping, also communication work can be carried out.

B () is connected with diode bridge 50, and between this diode bridge 50 and loop net 85, loop can be overlapping with the direct current from this installation's power source portion 91, therefore contrasts following comparative example, has more obvious advantage and effect.

Comparative example 1: such as, supposes one by the direct current of power supply 91 by the loop different from loop net 85, is directly supplied to the structure of semiconductor DAA40.In this comparative example 1, because diode bridge 50 does not work, can not via diode bridge 50 so receive letter signal.Namely the transmitting-receiving letter action of picture unit 1 cannot be carried out.

Comparative example 2: for solving the problem of comparative example 1, such as arrange not via another loop netting twine of diode bridge 50 (namely not via diode bridge, be connected to another loop netting twine between terminal L1, L2 and hybrid network 61), when being connected with the industrial siding only transmitting AC signal, by not via another loop netting twine described in diode bridge 50, between industrial siding and hybrid network 61, carry out transmitting-receiving believe.In this comparative example 2, owing to must arrange another loop netting twine separated mutually with diode bridge 50, become complicated so can be directed at loop structure and receive and dispatch letter control, its result is exactly cause the high cost of picture unit.

Relative with above-mentioned comparative example, execution mode one have in the common picture unit of diode bridge 50, while driving the direct current of semiconductor DAA by power supply unit 91 to AC input terminal 50T1,50T2 supply, only direct current separation means 32-1,32-2 are set between loop net 85 side and diode bridge 50, so just can control with fairly simple loop structure and transmitting-receiving letter, solve the defect of above-mentioned comparative example 1 and comparative example 2, realize the cost degradation of picture unit 1.

C () adjusts loop 92 by arranging power supply between power supply unit 91 and diode bridge 50, can increase the power supply output impedance for diode bridge 50.Therefore can prevent from the alternating component of self-loop net 85 to enter power supply unit 91 side, so just can improve the stability of power and the characteristic of low noise.

Execution mode two

The overall structure of the communication terminal (such as picture unit) 1 of embodiment of the present invention two, by the control part 20 shown in Fig. 3 of execution mode one and I/F portion, loop 30, replace with the control part 20A different from its function or structure and I/F portion, loop 30A, other structure is identical with execution mode one.

In the control part 20A of execution mode two, there is D.C. resistance switching indicatory device 21 and impedance switches except indicatory device 22 except same with the control part 20 of execution mode one, also add the selection portion 23 for selecting loop kind.Operating personnel operate operating portion 6, and after the kind in setting loop, the loop kind of information be set is preserved in selection portion 23, based on the information that this is saved, by selection portion 23 output switching signal S23.

Fig. 5 is the block figure representing the general configuration such as execution mode two I/F portion, loop 30A in figure 3, and wherein identical with I/F portion, loop 30 shown in Fig. 1 of execution mode one etc. element then marks identical symbol.

In I/F portion, the loop 30A of execution mode two, compared with loop I/F portion 30 in execution mode one, that 2 loops classification switch means (such as diverter switch) 33-1,33-2 are added for semiconductor DAA40, it is according to the switching signal S23 exported based on the loop classification information being kept at selection portion 23, for be connected with direct current supply mean 90 or make direct current separation means 32-1,32-2 effectively switches.

2 diverter switch 33-1,33-2 are made up of switch use transistor and selection selector or gating circuit respectively.Diverter switch 33-1 has 2 terminal 33T1 with 33T2 and is connected with one of terminal 33T1 or 33T2, and the switching signal S23 exported by selection portion 23 carries out 1 the terminal 33T3 switched.Equally, diverter switch 33-2 also has 2 terminal 33T4 with 33T5 and is connected with one of terminal 33T4 or 33T5, and the switching signal S23 exported by selection portion 23 carries out 1 the terminal 33T6 switched.

In diverter switch 33-1, terminal 33T1 is connected with the terminal 31T1 of the terminal L1 be connected on loop net 85, surge protection element 31 and the terminal 32T1 of direct current separation means 32-1, the choke 92a that terminal 33T2 and power supply adjust in loop 92 is connected, in addition, terminal 33T3 is connected with the terminal 32T2 of direct current separation means 32-1 and the AC input terminal 50T1 of diode bridge 50.

In diverter switch 33-2, terminal 33T4 is connected with the terminal 31T2 of the terminal L2 be connected on loop net 85, surge protection element 31 and the terminal 32T3 of direct current separation means 32-2, the choke 92b that terminal 33T5 and power supply adjust in loop 92 is connected, in addition, terminal 33T6 is connected with the terminal 32T4 of direct current separation means 32-2 and the AC input terminal 50T2 of diode bridge 50.

Fig. 6 is in the picture unit shown in Fig. 2, Fig. 3 and the Fig. 5 in execution mode two, when the picture unit as originator sends calling, as destination picture unit 1 switch to automatic reception time action flow chart, wherein, identical with the key element in flow process shown in Fig. 4 of execution mode one, then mark identical symbol, and the description thereof will be omitted.

In the Fig. 6 representing execution mode two, before being step ST1 initial in the step ST1 ~ ST6 in flow process shown in Fig. 4 of execution mode one, add step ST11 ~ ST13.

Picture unit 1 is started working, in step ST11, operating personnel operate operating portion 6, and in advance setting connects the loop classification (such as have the dissipating public loop of direct current overlap or do not have the industrial siding of direct current overlap) of the loop net 85 of picture unit 1.This setting is only carried out once when arranging picture unit 1.Loop classification information after setting is stored in selection portion 23.

Based on the information that selection portion 23 is preserved, D.C. resistance switches indicatory device 21 and impedance switches indicatory device 22 output switching signal S21, the S22 corresponding with the loop classification set, switch 61-1c, 61-2c in D.C. resistance switch means 61-1 and impedance switch means 61-2 are switched, and are set as the output resistance corresponding with the classification of loop net 85 and output impedance.

In step ST12, control part 20A checks whether the information of preserving in selection portion 23 is industrial siding.When the information of preserving in selection portion 23 is industrial siding, then enter step ST13.In step ST13, selection portion 23 exports the switching signal S23 corresponding with industrial siding.According to switching signal S23, diverter switch 33-1,33-2 are switched to direct current supply mean 90 side, and by diode bridge 50 and diverter switch 33-1,33-2, semiconductor DAA40 is connected with direct current supply mean 90.Like this, the direct current exported by direct current supply mean 90, via diverter switch 33-1,33-2 and diode bridge 50, is supplied to semiconductor DAA40, and this semiconductor DAA40 becomes can operating state.Enter step ST1 subsequently.

In step ST12, when the information that selection portion 23 is preserved is the dissipating public loop of non-dedicated, then enter step ST1.Here, step ST1 ~ step ST6 carries out almost identical FAX communication work with execution mode one.

Here, when terminal L1, L2 in I/F portion, the loop 30A of Fig. 5 are connected with the dissipating public loop as loop net 85, according to the switching signal exported from selection portion 23, diverter switch 33-1,33-2 are switched to dissipating public loop net 85 side, terminal L1, L2, by switch 33-1,33-2, are connected with AC input terminal 50T1,50T2 of diode bridge 50.Therefore, from dissipating public loop have the collection of letters commencing signal of direct current overlap to arrive terminal L1, L2 after, this collection of letters commencing signal is rectified into direct current at diode bridge 50, and semiconductor DAA40 becomes based on the direct current after being rectified can operating state.And by semiconductor DAA etc., the FAX identical with execution mode one is carried out for the FAX signal in the direct current be rectified and communicates.

By execution mode two, the effect almost identical with execution mode one can be realized.In addition, in execution mode two, add the selection portion 23 of selecting loop net 85 classification and as loop classification switch means, according to the loop selected, to diverter switch 33-1,33-2 that loop net 85 and the connection status of semiconductor DAA40 and the connection status of semiconductor DAA40 and direct current supply mean 90 switch.Therefore, by the switching of diverter switch 33-1,33-2, though the picture unit 1 employing semiconductor DAA40 in I/F portion, loop be connected to there is no direct current overlap industrial siding on, also can carry out FAX communication work.In addition, by the switching of diverter switch 33-1,33-2, make it in dissipating public loop, also can carry out FAX communication work.

Execution mode three

The overall structure of communication terminal (such as picture unit) 1 in embodiment of the present invention three, be that the control part 20A shown in Fig. 2 of expression execution mode two is replaced with the control part 20B different from its function, other structure is identical with execution mode two.

Fig. 7 is the block figure representing execution mode three general configuration such as loop I/F portion 30A and control part 20B in figure 3, wherein, the key element identical with the loop I/F portion 30A shown in the Fig. 5 representing execution mode two and control part 20A etc., then mark identical symbol, and the description thereof will be omitted.

In the control part 20B of execution mode three, have that D.C. resistance switches indicatory device 21, impedance switches indicatory device 22 and except selection portion 23, also add the automatic means of identification 24 of loop classification except same with the control part 20A of execution mode two.The automatic means of identification of this loop classification can identify the classification (such as dissipating public loop or industrial siding) in loop automatically, and allows selection portion 23 select.

Fig. 8 is that execution mode three is in the picture unit 1 shown in Fig. 2, Fig. 3 and Fig. 7, when the picture unit as originator sends calling, picture unit 1 as destination switches to action flow chart during automatic reception, wherein, for the key element identical with the flow process shown in the Fig. 6 representing execution mode two, then mark identical symbol, and the description thereof will be omitted.

Representing in the flow chart shown in Fig. 8 of execution mode three, be provided with step ST21 ~ ST23, for replacing the step ST11 in the flow chart shown in the Fig. 6 representing execution mode two.

Picture unit 1 is started working, in step ST21, the automatic means of identification of loop classification 24 carries out automatic discrimination to the kind (such as do not have the overlapping industrial siding of direct current or have the dissipating public loop of direct current overlap) of the loop net 85 that terminal L1, L2 are connected.Method of discrimination can be such as detect the voltage of loop net 85, when think have applied voltage time, be then judged as dissipating public loop; When think there is no applied voltage time, be then judged as industrial siding.This method of discrimination is only an example, also can use other method that can differentiate loop kind (such as detecting the dialing audio signal etc. in dissipating public loop).

When being judged as industrial siding, in step ST22, loop classification information saves as " industrial siding " by selection portion 23; When being judged as dissipating public loop, in step ST23, loop classification information saves as " dissipating public loop " by selection portion 23.Identical with execution mode two, based on the information that selection portion 23 is preserved, D.C. resistance switches indicatory device 21 and impedance switches indicatory device 22 output switching signal S21, the S22 corresponding with the loop classification set (such as dissipating public loop or industrial siding), switch 61-1c, 61-2c in D.C. resistance switch means 61-1 and impedance switch means 61-2 are switched, thus the setting output resistance corresponding with the classification of loop net 85 and output impedance.

After the process of step ST22, ST23, enter step ST12, identical with execution mode two, control part 20B is that industrial siding or dissipating public loop check to the information that selection portion 23 is preserved, and enters step ST13, ST1 ~ ST6 equally with execution mode two subsequently.

By execution mode three, the effect almost identical with execution mode one can be obtained.In addition, compared with execution mode two, the automatic means of identification 24 of loop classification of the classification automatically identifying loop net 85 is provided with in execution mode three, selection portion 23 is selected loop according to this recognition result, so operating personnel need not by setting loop classification to the selection portion 23 that operates in of operating portion 6, loop classification can complete automatically in the setting of selection portion 23.Therefore, by as the diverter switch 32-1 of loop classification switch means, the switching of 32-2, though the picture unit employing semiconductor DAA40 at I/F portion, loop 30A be connected to there is no direct current overlap industrial siding on, also can carry out FAX communication work.In addition, by the switching of diverter switch 33-1,33-2, make it in dissipating public loop, also can carry out FAX communication work better.

Mode of texturing

The present invention is not limited to above-mentioned execution mode, can also have multiple use forms and mode of texturing etc.Described use form and mode of texturing can be the forms of (1) as described below ~ (3):

(1) overall structure of the picture unit 1 of Fig. 3, other structure beyond diagram can be changed to, the control part 20 of picture unit 1 shown in Fig. 1, Fig. 5, Fig. 7,20A, 20B, I/F portion, loop 30,30A or direct current supply mean 90, other structure also beyond variable more diagram.

(2) such as, in power supply adjustment loop 92 in direct current supply mean 91, the switch of short circuit is connected side by side with each choke 92a, 92b, or with the impedance components such as each choke 92a, 92b contact resistance arranged side by side and capacitor, the impedance making power supply adjust loop 92 becomes variable structure, the adjustment for the power supply output impedance of diode bridge 50 can be made to become and be more prone to.In addition, the structure using other element also can be taked in power supply adjustment loop 92, and does not use above-mentioned choke 92a, 92b arranged side by side.In addition, power supply adjustment loop 92 also can be the structure of being amplified by source current, or changes to the structure etc. be arranged in I/F portion, loop 30.

(3) in execution mode one to three, communication terminal is described for picture unit 1, the various communication terminals used and the telephone set, all-in-one multifunctional machine etc. of the present invention has also been applicable to built-in FAX function are connected with loop net 85.

Claims (5)

1. a communication terminal, the circuit interface portion carrying out data transmit-receive in the loop with transmitting-receiving analog signal is provided with semiconductor DAA, for changing output resistance and output impedance, making it consistent with described loop, it is characterized in that having:

To the selection portion that the classification in described loop is selected;

For supplying the direct current feed unit of direct current to described semiconductor DAA;

Direct current separative element, flows out to described loop for the described direct current stoping described direct current feed unit to supply;

Loop classification switch unit, for the described loop selected according to described selection portion, switches the connection status of described loop and described semiconductor DAA,

Wherein, the classification in described loop refers to the 1st loop not having overlapping direct current, and overlap has the 2nd loop of described direct current,

When described selection portion have selected described 1st loop, described loop classification switch unit carries out the connection of described direct current feed unit and described semiconductor DAA, overlap is supplied to described semiconductor DAA from the described direct current of described direct current feed unit, described semiconductor DAA can be worked, switched by described direct current separative element simultaneously, the described direct current stoping described direct current feed unit to supply flows out to described 1st loop

When described selection portion have selected described 2nd loop, described loop classification switch unit does not connect described direct current feed unit and described semiconductor DAA, connects described 2nd loop with described semiconductor DAA to communicate.

2. communication terminal according to claim 1, is characterized in that, also has:

Automatically the loop classification automatic identification unit of the selection of loop classification is carried out in described selection portion.

3. communication terminal according to claim 2, is characterized in that:

Described loop classification automatic identification unit identifies the classification in described loop automatically, and makes described selection portion select described 1st loop or described 2nd loop.

4. the communication terminal according to any one of claims 1 to 3, is characterized in that:

Described direct current feed unit has the power supply adjustment loop increasing power supply output impedance.

5. the communication terminal according to any one of claims 1 to 3, is characterized in that:

Described direct current separative element is made up of the series loop of resistance and capacitor.