JP3379681B2 - Communication terminal switching control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal switching control device for efficiently and accurately switching a plurality of communication terminals such as a facsimile and a telephone when connecting them to a communication line.

[0002]

2. Description of the Related Art Facsimile machines are widely used not only for business use but also for general household use. Since telephone calls are made to such a facsimile terminal using the same telephone line, the telephone terminals are usually connected simultaneously. In this case, a telephone integrated with the facsimile terminal may be used, or a telephone terminal may be externally attached to the facsimile terminal. In such a case, for example, when a facsimile is received, the tone for facsimile connection is heard when the receiver of the telephone terminal is lifted. At this time, before lowering the handset, a previously designated key is pressed to notify the switch to the facsimile terminal, and then the handset is taken down. Conventionally, a telephone terminal and a facsimile terminal are generally switched by such a procedure. When a computer and other communication terminals are simultaneously connected to a general communication line, almost the same control operation is performed.

[0003]

By the way, in the communication terminal switching control device as described above, connecting a plurality of communication terminals to the same communication line generally brings about a decrease in the line impedance and the transmission at the communication terminal. Not only the quality may be deteriorated, but also the communication line itself may be adversely affected. For example, considering the case where a telephone and a facsimile are connected to the same line as described above, a high impedance is desirable in order to avoid the influence on the line impedance during the specific terminal communication mode of the facsimile, but in order to adapt to the line impedance during operation, In addition, there is a dilemma that it is desirable to have a low impedance in order to improve the transmission quality.

As a communication terminal switching technique as described above, a capacitor and a protection resistor for cutting a line DC current are inserted on the primary side of a line transformer of a facsimile.
In the facsimile mode (during communication), technologies such as using a relay to disconnect these are introduced (Japanese Patent Publication No. 7-
No. 12188). However, in this method, since an AC loop can always be established even during standby, connecting a plurality of communication terminals to the same communication line brings about a decrease in line impedance and not only a decrease in transmission quality at the communication terminal,
It may also affect the communication line itself. Also,
Because the special number can always be verified, when dialing from another terminal, if the number matches the special number, it will operate and seize the line.

To increase the line impedance, it is necessary to increase the insertion resistance. However, if the insertion resistance is large, the voltage drop at that resistance becomes large when a special number signal etc. for identifying the facsimile comes in during the telephone mode,
This may affect the signal detection ability on the secondary side of the input transformer and cause a malfunction. At the same time, impedance matching between the communication line and the facsimile in the facsimile mode sometimes becomes difficult. Further, since the user has switched the mode, it may cause an operation error and may be a source of annoyance.

[0006]

The present invention adopts the following constitution in order to solve the above points. <Structure 1> The present invention is a communication terminal switching control device for switching and connecting another communication unit to a communication line when a communication unit connected to the communication line outputs a special signal for instructing switching to another communication unit. And a first switching mode for connecting a communication unit to a communication line and a second switching mode for connecting another communication unit to the communication unit.
Switching mode and a third switching mode in which another communication unit is connected to the communication line are controllable, and a call signal sent from the communication line in the first switching mode is detected. A call signal detection unit that outputs a call detection signal, a special number signal detection unit that outputs a special number detection signal when the special number signal output from the communication unit in the second switching mode is detected, and a switching unit when the call detection signal is received To a second switching mode, and when the special number detection signal is received, the switching unit is controlled to switch to the third switching mode.

<Structure 2> In Structure 1, between the switching means and the other communication section.
The line impedance is high impedance and low.
Impedance that can be set to any of the impedances
The conversion unit is further provided, and the control unit operates in the second switching mode.
Set the impedance converter to high impedance and
In the switching mode of 3
It is characterized by setting to dance.

[0008] In <Configuration 3> Configuration 2, between the impedance transform unit and the other communication unit, converts the amplification factor of the signal is possible amplification section is further provided, the control unit is a second switching mode The amplification unit is set to a high amplification factor, and the amplification unit is set to a low amplification factor in the third switching mode. <Structure 4> In Structure 3, a resistance setting unit capable of converting a resistance value is further arranged between the impedance conversion unit and the amplification unit, and the control unit sets the resistance setting when the amplification unit is set to a high amplification factor. The part is also set to a high resistance value.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to specific examples. FIG. 1 is a connection diagram showing a main part of the device of the present invention. The present invention is implemented, for example, by a functional block having a configuration as shown in FIG. A communication terminal T1 and another communication terminal T2 are connected to the communication line 1. Then, these communication terminals T1, T
A bypass switch SR3, a changeover switch CML4, an impedance changeover switch DP5, and an amplification factor changeover switch PP6 are provided between the communication line 2 and the communication line 1. The bypass switch SR3 is a switch that performs an operation of directly connecting or disconnecting the communication line 1 and the communication terminal T1. When the bypass switch SR3 is on (ON), both are directly connected, and when it is off (OFF), both are connected. Is separated. The changeover switch CML4 is a switch that can be switched to select either a state in which the communication line 1 and the communication terminal T1 are connected or a state in which the communication line 1 and another communication terminal T2 are connected. The impedance changeover switch DP5 is a switch for changing over the impedance between the communication line 1 and another communication terminal T2. The amplification factor changeover switch PP6 is an input signal amplification degree conversion switch from the line to the communication terminal T2.

A call signal detector RI7 is inserted in the line connecting the communication terminal T1 and the communication line 1. The call signal detector 7 is configured to detect a call signal from the communication terminal T1 and transmit it to the signal controller 8. The signal control unit 8 is the calling signal detector 7
By receiving the output of the bypass switch SR3, changeover switch CML4, impedance changeover switch D
P5, a signal control unit 8 for controlling the operation of the amplifier changeover switch PP6, and the like. In the present invention, the signal control unit 8 has three types of the specific terminal communication mode shown in FIG. 1 (a), the other terminal communication mode shown in FIG. 2 (b), and the special number verification mode shown in FIG. 2 (c). Control each switch to be in one of the three modes. The control result is transmitted from the signal control unit 8 to another communication terminal T2 as necessary.

In the specific terminal communication mode (a), the bypass switch SR3 is turned on to connect the communication line 1 and the communication terminal T1, and the impedance changeover switch D
P5 is the high-impedance side, amplification factor switch P
P6 is connected to the low amplification factor side, and the changeover switch CML
Reference numeral 4 connects the communication line 1 and the communication terminal T1. Also,
In the other terminal communication mode (b), the bypass switch SR
3 is off, the impedance changeover switch DP5 is on the low impedance side, and the amplification factor changeover switch PP6
Is on the low amplification factor side, the communication terminal T1 is disconnected from the communication line 1, and the changeover switch CML4 connects the communication terminal T2 and the communication line 1. In the special number verification mode (c), the bypass switch SR3 is turned on and the communication line 1
And the communication terminal T1 are connected, and the changeover switch CML4
Connects the communication line 1 to the communication terminal T2, the impedance changeover switch DP5 is connected to the high impedance side, and the amplification rate changeover switch PP6 is connected to the high amplification rate side.

The calling signal detector RI7 is connected to the communication line 1 and detects a calling signal. Signal controller 8
Has a CPU (Central Processing Unit) inside, and based on the output from the call signal detector 7, the bypass switch SR3, the changeover switch CML4, the impedance changeover switch DP5, the amplification rate changeover switch PP6.
Switch.

Next, the operation of the present invention will be described with reference to FIGS. In order to help understanding of the explanation, it is assumed that the communication line is a telephone line, the communication terminal T1 is a telephone, and the communication terminal T2 is a facsimile. In the specific terminal communication mode (a), the changeover switch CML4 is set to the telephone side, and the bypass switch S
R3 is turned on to connect to the telephone, and either the impedance changeover switch DP5 or the amplification rate changeover switch PP6 may be used. Since the facsimile terminal is cut off by waiting in the above state, there is no fear of lowering the line impedance. Next, when a call signal flows into the line, the call signal detector 7 detects the signal and the signal control unit 8 sets the changeover switch CML4 to the facsimile side and the amplification factor changeover switch PP6 to high based on the output thereof. The bypass switch SR3 is connected to the telephone set side on the amplification factor side, and the special number verification mode (c) is entered.

In this special number verification mode, the communication terminal T1 and the other communication terminal T2 are connected in parallel to the communication line 1, but the input impedance to the facsimile seen from the communication line is the impedance changeover switch DP5 on the high impedance side. Since it is connected to (usually 30KΩ
It is possible to avoid lowering the line impedance. In this state, the special number signal flowing from the communication line 1 or the communication terminal T1 is transmitted to the facsimile through the high impedance side of the changeover switch CML4 and the impedance changeover switch DP5 and the high amplification rate side of the amplification rate changeover switch PP6. At this time, since the signal attenuation amount due to the high impedance is compensated by switching the amplification factor to the high amplification factor, it is possible to avoid a decrease in sensitivity.

Next, the facsimile receiving this special number signal internally sends an answer signal to the signal controller 8 after confirming that this signal is a special number. Upon receiving the answer signal, the signal control unit 8 sets the impedance changeover switch DP5 to the low impedance side, the amplification rate changeover switch PP6 to the low amplification rate side, and turns off the bypass switch SR3 to shift to another terminal communication mode (b).

In this mode, the impedance between the communication line 1 and the facsimile terminal 10 matches the communication line impedance (normal line impedance is 600).
Around Ω). Since the telephone is disconnected from the line and the amplification factor changeover switch is switched from the high amplification factor to the low amplification factor in the above (c), unnecessary noise and the like are not picked up.

<Specific Circuit Configuration> A specific circuit configuration of the device of the present invention will be described below. FIG. 3 shows a connection diagram of the device according to the invention. This example is based on the communication terminal T1 described above.
The telephone terminal 9 is used as, the telephone terminal 9A is added in parallel to the telephone terminal 9, and the facsimile terminal 10 is used as the communication terminal T2. The communication line 1 is a public telephone line. The facsimile terminal 10 is thus connected to the communication line 1. As shown in this figure, an internal circuit of a facsimile terminal and a telephone terminal 9 are connected in parallel to the communication line 1. The internal circuit 11 of the facsimile terminal means the modulator and tone transmitter 13 and the demodulator and tone detector 12 inside the facsimile.

A changeover switch CML4 is provided to connect the communication line 1 and the internal circuit of the facsimile terminal 10. When the changeover switch CML4 is changed over, the communication line 1 and the facsimile terminal side of the facsimile terminal 10 are connected. A bypass switch SR3 is provided so as to bypass the changeover switch CML4. When this is ON, the communication line 1 and the telephone terminal 9 are connected regardless of the connection of the changeover switch CML4. Further, an impedance changeover switch DP5 and an amplification rate changeover switch P for changing over the impedance between the communication line 1 and the facsimile.
P6 is provided. Here, the impedance changeover switch DP5 interrupts the DC loop intermittently to generate a dial pulse. However, this operation is performed only when the transformer T17 can pass a direct current.

FIG. 6 shows another specific circuit example (No. 2) of the device of the present invention. When a direct current cannot flow, it can be achieved by cutting the direct current path to the transformer T17 by C0 and turning on the switch DP to connect the direct current circuit DC, as shown in FIG. In this case, the impedance changeover switch DP5 is divided into a MUTE having a function of changing impedance and a DP having a function of generating a DP waveform.

The facsimile terminal 10 demodulates a facsimile reception signal and detects a tone, a demodulator and tone detector 12, modulates a facsimile transmission signal, and transmits a tone, a modulator and a tone transmission. 13, an amplifier 15 for amplifying a transmission signal, an amplifier 16 for amplifying a reception signal, a ringing signal detector 7 for detecting a ringing signal by connecting to a line, and controlling each switch using the ringing signal. A signal control unit 8, a relay drive unit 14, and a transformer 17 that electrically isolates the line from the facsimile are provided. Next, the operation of the specific example will be described in detail with reference to the timing chart shown in FIG.

In explaining the operation below, the numbers in parentheses indicate the timings shown in FIG.
The same. When a telephone call signal flows from the communication line 1, the bell of the telephone terminal 9 rings (1), and at the same time, the call signal detector RI7 detects the call signal (2). At this time, the bypass switch SR3 and the changeover switch CML4 are connected to the telephone, the impedance changeover switch DP5 is connected to the high impedance side, and the amplification factor changeover switch PP6 is connected to the low amplification factor side (3) (the specific terminal communication mode). (A)). The output of the call signal detector RI7 is guided to the signal control unit (CPU) 8 where it issues a relay control signal, passes through the relay drive unit 14, the changeover switch CML4 to the facsimile side, and the amplification factor changeover switch PP6 is highly amplified. Switch to the rate side. Now, by closing the switch, R2 and R
The amplification factor can be increased by connecting 4 in parallel and changing the impedance ratio with R3. At this point, the special number verification mode (c) is changed.

At this time, the impedance changeover switch DP5 is open until there is a request for line supplement (sending a special number), so the calling signal is the resistance R, the capacitor C,
Although it also flows through the transformer 17, since the value of the resistance R is large, the current of the calling signal is minute and does not affect the line request. In addition, the changeover switch CML
4, the amplification factor changeover switch PP6 is closed at the same time, so that the amplification factor is increased to compensate for the attenuation of the line signal determined by the ratio of the resistance R, the capacitor C and the additional impedance of the transformer 17. Next, when I picked up the telephone, I heard a fax transmission signal, or when making a call to receive the fax at the request of the other party during a call,
A special number signal (tone signal) is transmitted by a push button (a button determined as a special number in advance) of the telephone (4).

The special signal passes through the communication line 1, the changeover switch CML4, the resistor R, the capacitor C, the transformer, and is amplified by the amplifier AMP15 and input to the demodulator and tone detector 12. The tone detector detects that it is a special number and informs the signal controller 8. The signal control unit 8 drives the relay driving unit 14 to close the impedance changeover switch DP5, open the amplification factor changeover switch PP6 (5), and send an answer signal to the line to open the bypass switch SR3 (6). Further, the telephone confirms the answer signal and turns on-look (7). This state becomes the other terminal communication mode (b), and the communication line 1 and the facsimile are connected.

<Other Line Examples> FIG. 5 shows another specific circuit example (No. 1) of the device of the present invention. In a specific example,
The amplification factor changing switch PP6 is replaced with a two-contact switch, and one of the contacts is a terminating resistor R1 of the transformer T17.
The other is selectively connected to the resistor R4 for switching the amplification factor. By doing so, when the amplifier changeover switch PP6 is connected to the high amplification factor side (R4 side in FIG. 5), the secondary impedance of the transformer T17 is high, and the amplification factor is further increased as compared with the above specific example. Therefore, the impedances of the resistor R and the capacitor C can be set higher, and the influence on the line can be reduced. Other configurations and operations are the same as those in the above specific example.

[0025]

As described above, according to the first specific example, in the specific terminal communication mode, the changeover switch CML4,
Since the bypass switch SR3 is also connected to a specific communication terminal (telephone) and disconnected from other communication terminals (facsimile), not only the line impedance is lowered, but also the facsimile has a bad influence on the line. Absent. In the specific communication terminal mode, the specific communication terminal (telephone) and the other communication terminal (facsimile) are connected in parallel to the line, but since the high impedance is connected between the line and the other communication terminal, the line impedance You can avoid a decline. When the special number signal flows in this state, at the same time, the amplification factor changeover switch PP6 operates to compensate for the signal attenuation amount at high impedance, so that the decrease in the detection sensitivity of the special number signal can be avoided. Further, since each signal is switched by the signal control unit having a CPU inside, accurate and efficient switching can be performed, and remote switching from a distant place becomes possible. Further, the same operation can be performed from another telephone 9A connected in parallel to another communication terminal (facsimile).

[Brief description of drawings]

FIG. 1 is a circuit diagram (No. 1) of a main part of a device of the present invention.

FIG. 2 is a circuit diagram (No. 2) of the main part of the device of the present invention.

FIG. 3 is a specific circuit example of the device of the present invention.

FIG. 4 is a timing chart of a specific circuit example of the device of the present invention.

FIG. 5 is another specific circuit example (No. 1) of the device of the present invention.

FIG. 6 is another specific circuit example (No. 2) of the device of the present invention.

[Explanation of symbols]

1 communication line 3 Bypass switch 4 changeover switch 5 Impedance changeover switch 6 Amplification factor switch 7 Call signal detector 8 signal controller T1, T2 communication terminal

Continuation of front page (51) Int.Cl. ⁷ identification code FI H04N 1/32 H04N 1/32 Z (58) Fields investigated (Int.Cl. ⁷ , DB name) H04M 11/00-11/10 H04N 1 / 00 H04N 1/32-1/36 H04N 1/42-1/44

Claims (4)

(57) [Claims] 1. A communication unit connected to a communication line outputs a special number signal for instructing switching to another communication unit,
A communication terminal switching control device for switching and connecting the other communication unit to the communication line, comprising: a first switching mode for connecting the communication unit to the communication line; and connecting the other communication unit to the communication unit. Switching means capable of controlling switching between a second switching mode for switching and a third switching mode for connecting the other communication unit to the communication line, and a transmission means for transmitting from the communication line in the first switching mode. A call signal detection unit that outputs a call detection signal when detecting an incoming call signal, and a special number signal detection unit that outputs a special number detection signal when the special number signal output from the communication unit in the second switching mode is detected When the call detection signal is received, the switching means is controlled to switch to the second switching mode, and the special number detection signal is transmitted. A communication terminal switching control device comprising: a control unit which, upon reception, controls the switching unit to switch to the third switching mode. 2. The communication terminal switching control device according to claim 1, wherein the impedance conversion is arranged between the switching means and the other communication unit, and the line impedance can be set to either high impedance or low impedance. The control unit sets the impedance conversion unit to a high impedance in the second switching mode,
The communication terminal switching control device, wherein the impedance conversion unit is set to a low impedance in the switching mode. 3. The communication terminal switching control device according to claim 2, wherein between the impedance conversion unit and the other communication unit,
An amplification unit capable of converting the amplification factor of a signal is further arranged, and the control unit sets the amplification unit to a high amplification factor in the second switching mode, and sets the amplification unit in the third switching mode. A communication terminal switching control device characterized by setting to a low amplification factor. 4. The communication terminal switching control device according to claim 3, further comprising a resistance setting unit capable of converting a resistance value between the impedance conversion unit and the amplification unit, wherein the control unit is The communication terminal switching control device, wherein when the amplification section is set to a high amplification factor, the resistance setting section is also set to a high resistance value.