JP2000174918A - Facsimile communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a facsimile communication equipment capable of performing the polarity inversion detection, the AC signal detection of a telephone line and simplifying constitution for facsimile communication and capable of attaining reduction in size and weight. SOLUTION: An AC line terminating part 100 and a DC line terminating part 110 share a transformer 3. In a state where the switch 10 of the part 110 is opened, a signal from a diode bridge 1 is supplied for one terminal on the primary side of the transformer via a capacitor 2 to detect polarity inversion by the part 120 on the secondary side. In a state where the switch 10 is opened, an AC signal is detected by a modem part 26 via a two-wire to four-wire conversion circuit provided on the secondary side. In a state where the switch 10 is closed, the bridge 1 and the transformer 3 are connected in the state of DC and facsimile communication is executed by the part 26 through the two-wire to four-wire conversion circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile communication apparatus capable of inverting the polarity of a telephone line, detecting an AC signal (such as a CNG signal), and performing facsimile communication with a partially shared circuit configuration. It is.

[0002]

2. Description of the Related Art Conventionally, in a facsimile communication apparatus of this type, reversal of the polarity of a telephone line, detection of an AC signal (such as a CNG signal), and facsimile communication are performed by separate circuits.

FIG. 5 is a circuit diagram showing a configuration example of an NCU unit in such a conventional facsimile communication apparatus.

As shown in the figure, in the facsimile communication apparatus, in the polarity reversal detection unit 60, the photocoupler 6
A configuration is used in which the polarity inversion of the telephone lines L1 and L2 is detected by an optical element such as 1 and transmitted to the CPU 27 through the transistors 62 and 63.

In the AC signal detecting section 50, an AC signal propagating through the telephone lines L1 and L2 is input to a frequency detecting circuit 52 via a capacitor 51 and a high impedance transformer 52, and the frequency detecting circuit 52 detects the AC signal. A configuration for transmitting a signal to the CPU 27 is used.

Further, the facsimile communication uses a telephone line L
1, a signal obtained from L2 via the diode bridge 1 is supplied to the primary side of the communication transformer 70 via the switch 10 and the transistors 5 and 6, and the output of the secondary side of the communication transformer 70 is output on two wires-4. A configuration is used in which the signal is input to the modem unit 26 via the line conversion circuit 23 to receive the signal, and the signal is transmitted through the reverse route.

The other configuration shown in FIG. 5 is common to the configuration of an embodiment (FIG. 1) described later, and will be described in detail in the embodiment.

[0008]

However, the conventional facsimile communication apparatus has the following problems.

(1) The operation of the optical element becomes unstable because a high impedance resistor is used in the polarity inversion detecting section.

(2) In the AC signal detecting section, a high impedance transformer is used separately from the communication transformer, so that the circuit configuration becomes large and heavy.

(3) The circuit configuration becomes complicated to stabilize the above-described unstable operation polarity inversion detection in the secondary circuit, and the communication circuit and the control circuit are required to detect the AC signal. Separately, an interface circuit and an amplifier circuit had to be used, and the circuit became complicated and large in this respect.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile communication apparatus which can simplify the configuration for detecting the inversion of the polarity of a telephone line, detecting an AC signal, and further performing facsimile communication, and achieving a reduction in size and weight. .

[0013]

SUMMARY OF THE INVENTION The present invention provides an AC line terminating means for terminating a telephone line in an AC manner with a certain impedance, a DC line terminating means for terminating a telephone line in a DC manner, and the AC line. Polarity reversal detecting means for detecting polarity reversal of a telephone line by using a terminating means; AC signal detecting means for detecting an AC signal propagating through a telephone line by using the AC line terminating means; Facsimile communication means for performing facsimile communication using the terminating means.

The present invention also provides a polarity matching bridge circuit for inputting a signal from the telephone line, and a transformer for insulating the bridge circuit from the polarity inversion detecting means, the AC signal detecting means, and the facsimile communication means. The AC line termination means inputs a signal from the bridge circuit to one terminal of a primary winding of the transformer via a capacitor, and the DC line termination means Switch means for opening and closing between a circuit and an intermediate terminal of a primary winding of the transformer, and a signal from the bridge circuit is applied to an intermediate terminal of a primary winding of the transformer via the switch means. The polarity inversion detection means inputs a signal from one terminal of the secondary winding of the transformer to detect polarity inversion, and the AC signal detection means outputs In a state where is open, a signal from an intermediate terminal of the secondary winding of the transformer is input to detect an AC signal, and the facsimile communication means detects the facsimile signal by the AC signal detection means. Thus, transmission and reception of facsimile signals are performed via the intermediate terminal of the secondary winding of the transformer while the switch means is closed.

Further, according to the present invention, the switch means is provided between the positive and negative output terminals of the bridge circuit, and opens and closes a DC loop between the telephone line and the facsimile communication apparatus. And a transistor circuit for turning on and off between the bridge circuit and an intermediate terminal of the primary winding of the transformer.

Further, the invention is characterized in that the AC signal detecting means and the facsimile communication means are constituted by a common circuit having a 2-wire to 4-wire conversion circuit and a modem unit.

[0017]

FIG. 1 is a block diagram showing a configuration of a facsimile communication apparatus according to one embodiment of the present invention.

The diode bridge 1 is connected to a telephone line 39
(L1, L2) to match the polarities of the input signals.

The transformer 3 is shared by the AC line terminating unit 100 and the DC line terminating unit 110, and includes a line primary side (diode bridge 1) and a secondary side (polarity reversal detecting unit 120, two lines). -4 line conversion circuit 23).

The AC line terminating unit 100 connects a signal from a positive output terminal of the diode bridge 1 to one terminal 4 of a primary winding of a transformer 3 via a capacitor 2.

The DC line terminator 110 has transistors 5, 6, resistors 8, 9, 11, and a switch 10 arranged between the diode bridge 1 and the primary winding of the transformer 3.

The switch 10 is provided between the positive and negative output terminals of the diode bridge 1 and opens and closes a DC loop between the telephone line 39 and the facsimile communication apparatus.
Opening and closing control is performed by the CPU 27.

The transistors 5 and 6 are operated by the voltage dividing resistors 8 and 9 when the switch 10 is turned on to close the connection between the diode bridge 1 and the intermediate terminal 7 of the primary winding of the transformer 3. It is.

The negative output terminal of the diode bridge 1 is connected to the other terminal 12 of the primary winding of the transformer 3.

On the secondary side of the transformer 3, a polarity inversion detecting section 120 is provided. This polarity reversal detector 1
The transistor 20 includes a Zener diode 16, a capacitor 18, resistors 17, 18, and a transistor 20. The collector of the transistor 20 is supplied with Vcc via a collector resistor 21.

The Zener diode 16 is connected to the transformer 3
The output voltage obtained from one terminal 13 of the secondary winding is sliced into an appropriate voltage.
The charge from the Zener diode 16 is accumulated via the resistor 17 and the transistor 20 is turned on.

The transistor 20 is turned on and off in accordance with the potential of the capacitor 18, outputs a Vcc level collector output to the CPU 27 in the off state, and outputs a GND level collector output to the CPU 27 in the on state. When the transistor 20 is turned on, the capacitor 18 is discharged, and the transistor 20 is turned off after a predetermined time.

Further, in this embodiment, the AC signal detection section and the facsimile communication section are constituted by the 2-wire to 4-wire conversion circuit 23 and the modem section 26.

The two-wire to four-wire conversion circuit 23 includes a telephone line 39.
The modem unit 26 performs two-wire / four-wire conversion between the facsimile apparatus side and the facsimile apparatus side.

The CPU 27 controls the entire facsimile communication apparatus. The ROM 28 stores a control program of the CPU 27 and the like. RAM29
Stores data for the CPU 27 to perform various processes. The non-volatile RAM 30 is for storing data to be stored even when the power is turned off. The character generator (CG) 31 is a ROM that stores character fonts.

The recording section 32 prints out a received image or the like, and the reading section 33 reads out a transmission original or the like. The operation unit 34 is for the operator of the facsimile communication device to perform various key inputs, and the display unit 35 is an LCD for displaying various information.
And so on. The power supply unit 36 outputs power to be supplied to each unit of the facsimile communication apparatus.
It has an output 37 for c.

The call signal detecting section 38 detects a call signal from the telephone line 39, and is provided with an external telephone terminal 40.
Is a terminal for connecting an external telephone (not shown).

Next, the operation of the facsimile communication apparatus described above will be described.

(1) First, the operation of detecting polarity inversion will be described.

In a normal standby state, the switch 10 is open. That is, the telephone line 39 is not captured in a DC manner. At this time, a case where the polarity of the telephone line 39 is reversed will be described. FIG. 2 is a timing chart showing a specific example of the signal waveform in this case. FIG. 3 is a flowchart showing the control of the CPU 27 during the polarity inversion detection operation.

Here, the polarity reversal of the telephone line 39 means L
1-reversal of the polarity of L2.
From a state where 1 is + and L2 is-, over a certain time T, L
1 changes to-and L2 changes to +.

The change in the polarity inversion is given a polarity by passing through the polarity matching diode bridge 1, and is input to the terminal 4 of the transformer 3 via the capacitor 2. Then, the change of the polarity inversion is output to the terminal 13 on the secondary side of the transformer 3. Since the terminal 13 has a large winding ratio on the secondary side, the waveform of the change time T is output as a large voltage.

Then, the voltage is sliced to an appropriate voltage by the Zener diode 16,
The electric charge stored in 8 turns on the transistor 20 through the resistor 19. When the transistor 20 is turned on, the charge stored in the capacitor 18 is discharged,
After a certain time, transistor 20 turns off.

With such an operation, the transistor 20
, And a signal line 22 which is a collector output of the transistor 20, one of the Vcc and GND levels is input to the CPU 27 as a detection signal.
Accordingly, in the CPU 27, as shown in FIG. 3, the output level of the signal line 22 becomes Lo for a certain time t or more.
When it is confirmed that w (GND level) is reached, it is determined that polarity inversion has occurred (S1).

Thereafter, the next operation is performed. For example, in the example shown in FIG. 3, the switch 10 is closed (S2), facsimile reception is performed (S3), and after the reception is completed (S4), the switch 10 is opened (S5) and the process returns to the standby mode.

(2) Next, the operation of detecting an AC signal using the AC line termination unit 100 will be described. FIG. 4 is a diagram showing C signals during the operation of detecting an AC signal and the operation of facsimile communication.
4 is a flowchart illustrating control of a PU 27.

As described in (1) above, since the switch 10 is open during standby, the telephone line 39 does not capture the line when viewed from the exchange side.

Therefore, in this state, the external telephone terminal 40
Is connected to an answering machine. And telephone line 3
When the ringing signal propagates from the ringing signal 9, the ringing signal detection unit 38
And an answering machine connected to the external telephone terminal 40 detects a calling signal. The answering machine activates and sends a message to the telephone line 39 with two to five ringing signals. At the same time, the call signal detected by the call signal detection unit 38 is output to the CPU 27 as a detection signal (S1).
1).

Thus, the CPU 27 sets the reception line 2
The modem unit 26 is controlled so as to detect a signal input to the modem unit 26 from Step 4 (S12).

Here, the capacitor 2 and the transformer 3 are connected to the telephone line 39 through the polarity matching diode bridge 1.
Is connected in parallel with the line from the external telephone terminal 40 to the answering machine.

As a result, the transmission and reception signals of the answering machine connected to the external telephone terminal 40 are monitored. Then, it passes through the capacitor 2 and the terminal 4 of the transformer 3
Is transmitted to the terminal 14 on the secondary side of the transformer 3,
A receiving signal is transmitted. The terminal 14 is input to the 2-wire / 4-wire conversion circuit 23 and is input to the modem unit 26 via the reception line 24.

Here, a fax signal (CN) is sent to the answering machine.
When the G signal is sent from the other party (S13), the modem unit 26 determines that the signal is a CNG signal, closes the switch 10, and the DC line termination unit 110 operates (S13).
14).

(3) Next, the facsimile communication operation using the DC line termination unit 110 will be described.

In the DC line termination unit 110, when the switch 10 is closed as described above, the DC potential divided by the resistors 8 and 9 is applied to the base of the transistor 6, and the transistor 6 is turned on. When the transistor 6 is turned on, the base of the transistor 5 is connected to the negative output terminal of the polarity matching diode bridge 1 through the resistor 11. As a result, the transistor 5 is turned on, so that a DC signal and an AC signal are input to the intermediate terminal 7 of the transformer 3.

By operating the DC line terminating unit 110 in this manner, facsimile communication becomes possible via the terminals 7 and 14 of the transformer 3 (S15). This facsimile communication is separated into a reception line 24 and a transmission line 25 by a two-wire to four-wire conversion circuit 23 via a terminal 14, and is connected to a modem unit 26 to be performed. Then, the CPU 27
M28, RAM 29, nonvolatile RAM 30, character generator 31, and recording unit 32 are controlled to execute a receiving operation. Thus, when the receiving operation is completed (S1)
6) Open the switch 10 to end the operation (S17),
Return to standby.

On the contrary, the CNG signal is supplied to the terminal 14, the 2-wire to 4-wire conversion circuit 2 via the AC line termination section 100.
3. If the modem unit 26 cannot detect the call through the receiving line 24 (S13), the CPU 27 determines that the call is a normal call and keeps the switch 10 open.
That is, the operation of the answering machine is continued. When the call ends (S18), the process returns to the standby mode.

In the transmission operation of facsimile communication, the switch 10 is closed to capture the direct current of the telephone line 39, and then the transmission operation is started. However, since this is the same as the conventional operation, the detailed description is omitted. I do.

As described above, according to the present embodiment, it is possible to use a large number of circuit components conventionally used in facsimile communication devices, and to achieve an effect at low cost.

[0054]

As described above, according to the present invention,
Since the AC line terminating means is shared and the polarity of the telephone line is inverted and the AC signal sent from the telephone line is detected, the circuit configuration can be simplified, and the facsimile communication device can be reduced in size and weight.

Further, by sharing a transformer between the AC line terminating means and the DC line terminating means, the configuration for facsimile communication can be simplified in addition to the detection of polarity inversion and the detection of an AC signal. A small size and light weight can be achieved, and a stable operation can be easily obtained without using an optical element.

Further, by adopting a configuration in which the AC signal detecting means and the facsimile communication means are performed by a shared circuit (a 2-wire to 4-wire conversion circuit and a modem unit), the structure can be further simplified, and the facsimile communication apparatus can be reduced in size. Weight reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a facsimile communication apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart showing a specific example of a signal waveform for polarity inversion detection in the embodiment.

FIG. 3 is a diagram showing C in the polarity inversion detecting operation in the embodiment.
6 is a flowchart illustrating control of a PU.

FIG. 4 is a flowchart showing control of a CPU during an AC signal detection operation and a facsimile communication operation in the embodiment.

FIG. 5 is a block diagram showing a configuration of a facsimile communication apparatus in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diode bridge, 2 ... Capacitor, 3 ... Transformer, 10 ... Switch, 26 ... Modem part, 27 ... CPU, 38 ... Call signal detection part, 39 ... Telephone line, 100 ... AC line termination part, 110 ... DC Line termination section, 120 ... Polarity inversion detection section.

Claims (4)

[Claims] 1. An AC line terminating means for terminating a telephone line in an AC manner with a certain impedance, a DC line terminating means for terminating a telephone line in a DC manner, and a telephone line using the AC line terminating means. Polarity inversion detection means for detecting polarity inversion, AC signal detection means for detecting an AC signal propagating through a telephone line using the AC line termination means, and facsimile communication using the DC line termination means. Facsimile communication means, comprising: 2. A circuit according to claim 1, wherein a polarity matching bridge circuit for inputting a signal from the telephone line is insulated from the bridge circuit and the polarity inversion detecting means, the AC signal detecting means and the facsimile communication means. The AC line terminating means inputs a signal from the bridge circuit to one terminal of a primary winding of the transformer via a capacitor, and the DC line terminating means comprises: Switch means for opening and closing between the bridge circuit and an intermediate terminal of a primary winding of the transformer; and a signal from the bridge circuit is connected to the intermediate of the primary winding of the transformer via the switch means. Input to a terminal, the polarity inversion detection means inputs a signal from one terminal of the secondary winding of the transformer to detect polarity inversion, and the AC signal detection means In a state where the switch means is opened, a signal from an intermediate terminal of the secondary winding of the transformer is input to detect an AC signal, and the facsimile communication means detects a facsimile signal by the AC signal detection means. Thus, the facsimile communication apparatus transmits and receives a facsimile signal via an intermediate terminal of a secondary winding of the transformer in a state where the switch means is closed. 3. The switch according to claim 2, wherein the switch is provided between the positive and negative output terminals of the bridge circuit and opens and closes a DC loop between the telephone line and the facsimile communication device.
A facsimile communication apparatus comprising: a transistor circuit that turns on and off between the bridge circuit and an intermediate terminal of a primary winding of the transformer by an off operation. 4. A facsimile communication apparatus according to claim 2, wherein said AC signal detection means and said facsimile communication means are constituted by a common circuit having a 2-wire to 4-wire conversion circuit and a modem unit. .