JPH09321904A - Facsimile equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mis-detection of a reception signal due to crosstalk of a transmission signal of its own facsimile equipment to a reception end. SOLUTION: A filter 7 is a rejection filter to eliminate a specific frequency, that is, 2100Hz. When a call signal from an exchange is detected by a call detection section 5 in the standby state, a changeover device 3 is thrown to connect a line 1 to a facsimile equipment A from a telephone set 2. After the changeover, a CED 2100Hz is sent and in the private mode, a signal 800Hz for abbreviated protocol is sent from an equipment of an opposite party during the transmission of the CED and it is detected. The 2100Hz filter 7 is inserted to a post-stage of a 2/4-wire conversion section 6 and crosstalk of the transmission signal CED to a receiving end of a MODEM 9 is eliminated by the filter 7 and then the signal 800Hz from the transmitter side is easily detected. In the case that the 800Hz signal is detected, the abbreviated protocol of the private mode is proceeded, a 2nd changeover device 8 is switched and communication is conducted while bypassing the filter 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus, and more particularly, to a facsimile apparatus connected to a general public line for communication, in which a received signal is erroneously detected due to a sneak of a signal sent from itself to a receiving end. Is to prevent.

[0002]

2. Description of the Related Art Conventionally, in the sneak of a transmission signal in a facsimile machine, an operational amplifier is formed in the reception path of a 2-wire to 4-wire conversion unit to prevent the sneak of the transmission signal to the receiving end. For example, in Japanese Unexamined Patent Publication No. 5-003460 (transmission / reception apparatus), a front circuit having a frequency characteristic that amplifies a low frequency component in a transmission frequency region or less is provided, and a front circuit of a transmission unit is provided after a demodulator of a reception unit. An attenuator circuit for restoring the low frequency component amplified by the above to obtain a uniform frequency characteristic is provided to prevent the data signal generated by the modulator from being included in the receiving side data signal.

[0003]

As described above, the sneak of the transmission signal in the conventional facsimile apparatus is 2 lines 4 lines.
An operational amplifier is configured in the reception path of the line conversion unit to prevent the transmission signal from sneaking into the reception end. However, due to the difference in impedance between the transformer used and the exchange, the signal wraparound cannot be sufficiently removed, and the received signal may not be detected during signal transmission.

The present invention has been made in view of the above-mentioned circumstances, and has a filter for removing the frequency of a transmission signal in the reception path to remove the sneak-in signal regardless of the impedance of the exchange and to receive the reception signal. Elimination of false detection and omission of detection, or having a filter that passes only the frequency of the detection signal in the reception path, and further, several types of filters that are at the frequency that needs to be removed or the frequency that needs to be detected. The purpose of this is to eliminate erroneous detection and omission of detection of reception signals other than the specific signal.

[0005]

According to a first aspect of the present invention, there is provided a facsimile apparatus which is connected to a general public line to perform communication, and a first switching device for switching and connecting the line between a facsimile apparatus and a telephone, and the line. A transformer for insulatingly connecting a facsimile machine and a facsimile device to transmit a signal, a call detection unit for detecting a call signal from an exchange, and 2 of the line.
A two-wire to four-wire conversion unit for converting a line signal and a 4-wire signal from a modem, a filter for removing a specific frequency, and a second switching device for switching ON / OFF of the insertion of the filter, A modem for performing data demodulation, an I / O unit for exchanging input / output control signals, a switching control unit for controlling switching between the operation display unit and the second switching device, and control of this system. When detecting a signal during signal transmission, the second switching device is controlled, the filter is inserted, the sneak of the transmission signal to the modem receiving end is removed, and communication is performed. The second switching device is controlled so that the filter is not inserted therein. Therefore, a filter that removes a specific frequency can be inserted into and removed from the reception path to prevent the transmission signal from sneaking into the reception end. Removal , Erroneous detection of the detection signal, eliminating the detected leak, in which so as to improve the reliability.

According to a second aspect of the present invention, in the facsimile apparatus of the first aspect, the filter is a bandpass filter that passes only a specific frequency.
A filter that allows only a specific frequency to be inserted into and removed from the reception path eliminates sneaking of a transmission signal to the reception end, eliminates false detection of a detection signal, and omission of detection, thereby improving reliability.

The invention of claim 3 is characterized in that, in the facsimile apparatus of claim 1 or 2, it has several kinds of filters, and these several kinds of filters are switched and controlled for each use signal. Since it has a filter of and can be switched, erroneous detection of signals at all frequencies necessary for detection,
It eliminates detection omissions and improves reliability.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is intended to prevent erroneous detection of a received signal in a facsimile apparatus which is connected to a general public line for communication and which is caused by a sneak of a signal sent from itself to a receiving end. Shows an example thereof. In FIG. 1, A is a facsimile device, 1 is a general public line, 2 is a telephone that can be connected to the facsimile device, 3 is a first switching device for connecting the general public line 1 to the facsimile device A and the telephone 2, 4 Is a transformer for connecting the line 1 and the facsimile device A in an insulated state to transmit a signal, 5 is a call detection unit for detecting a call signal from the exchange, and 6 is a line 2 line signal and a modem 4 line A 2-wire 4-wire conversion unit for converting signals, 7 is a filter circuit, 8 is a second switching device for switching the insertion / removal (ON / OFF) of the filter circuit 7, 9 is a modem for performing re-modulation of data, 10 Is an I / O unit for inputting / outputting signals, 11 is an operating unit for performing operations such as transmission / reception, and setting functions, 12 is a switching control unit for performing switching control of the switching devices 3 and 8, 13 is a CPU, With the CPU 13, the book Do all of the control involved in the Ming.

FIGS. 2 and 3 are flow charts for explaining the embodiment of the present invention shown in FIG. 1. In FIG. 2, the incoming operation at the time of shortening protocol control in the in-house mode is shown in FIG.
Shows the normal transmission flow.

First, the operation will be described according to the flow of FIG. 2. Here, the filter section 7 of FIG. 1 in the embodiment of FIG.
Is a rejection filter for removing a specific frequency and removes 2100 Hz. In the standby state, the call signal from the exchange is monitored (S201), and when the call detection unit 5 detects the call signal (S201-Y).
ES), the first switching device 3 is changed, and the line 1 is switched from the telephone 2 to the facsimile device A side (S202). After switching, send CED2100Hz (S203)
However, in the in-house mode, the signal 800Hz for performing the shortened protocol is transmitted from the other device during CED transmission,
This needs to be detected.

In the present embodiment, a rejection filter 7 of 2100 Hz is inserted after the 2-wire / 4-wire conversion section 6, and the sneak of the transmission signal CED to the modem 9 reception end is removed by this filter 7. The signal 800 Hz from the transmitting side can be easily detected. When 800 Hz is detected (S204-YES), the short-term protocol of the in-house mode is entered (S205), the second switching device 8 is switched (S206), the filter 7 inserted in the reception path is passed, and communication is performed. Perform (S207). When 800 Hz is not detected (S204-NO), the normal protocol is entered (S210), and the switching device 8 is switched (S21).
1) to communicate (S207). After the communication is completed, the switching device 3 is switched (S208) to disconnect the line 1, the switching device 8 is switched (S209), the filter is inserted again, and the standby state is returned. With such a configuration operation, it is possible to prevent erroneous detection and omission of detection of the reception signal due to the wraparound of the transmission signal, and it is possible to surely perform the intended communication.

Next, the operation will be described with reference to the flow chart of FIG. 3. Here, the filter unit 7 of FIG. 1 in the embodiment of FIG. 3 is a rejection filter for removing a specific frequency and removes 1100 Hz. To do. When a transmission operation is performed by the operation unit 11 in the standby state, the first switching device 3 is switched (S301), the line 1 is switched from the telephone 2 to the facsimile apparatus A side, and a call operation is performed (S).
302). Calling is performed by a DTNF signal that can be sent from a dial pulse transmitting circuit or a modem (not shown). After calling, a CNG signal of 1100 Hz is sent (S30
3) If the other party is busy, the busy signal 40 from the exchange.
0 Hz is transmitted, it is necessary to release the detection line for this, and at the time of connection, it is necessary to detect the CED signal 2100 Hz from the partner device and start communication.

In the present embodiment, a rejection filter 7 of 1100 Hz is inserted in the subsequent stage of the 2-wire / 4-wire conversion section 6, and the sneak of the transmission signal CNG to the modem 9 reception end is removed by this filter 7. , 400 Hz busy signal from the exchange and CED signal 2100 from the receiver side
Hz can be easily detected. When the busy signal is detected (S304-YES), the switching device 3 is switched (S30).
5) Immediately release the line. If the CED signal is detected without the busy signal being detected (S304-NO) (S304).
306-YES), switch the switching device 8 (S30
7), pass the filter 7 inserted in the reception path,
Communication is started (S308). After the communication is completed, the first switching device 3 is switched (S309), the line 1 is released, the second switching device 8 is switched (S310), and the filter 7 is inserted again to return to the standby state. By the above-described configuration operation, it is possible to prevent erroneous detection and omission of detection of the reception signal due to the sneak of the transmission signal, and it is possible to perform a reliable operation.

[0014]

According to the first aspect of the present invention, in a facsimile apparatus connected to a general public line for communication, there is provided a first switching device for switching and connecting the line between a facsimile device and a telephone, and the line and the facsimile device. A transformer for insulatingly connecting and transmitting signals, a call detection unit for detecting a call signal from the exchange, and a two-wire and four-wire conversion unit for converting the two-wire signal of the line and the four-wire signal from the modem. , A filter for removing a specific frequency, a second switching device for switching ON / OFF of insertion of the filter, a modem for demodulating data, and an I / O for exchanging input / output control signals. An O unit, an operation display unit, a switching control unit for controlling switching of the second switching device, and a system control unit for controlling the present system are provided, and are used for detecting a signal during signal transmission. Control the second switching device, insert the filter to remove the sneak of the transmission signal to the modem receiving end, and control the second switching device not to insert the filter during communication. By doing so, by allowing a filter for removing a specific frequency to be inserted into and removed from the reception path, the sneak into the receiving end of the transmission signal is removed, erroneous detection of the detection signal, detection omission is eliminated,
The reliability can be improved.

According to a second aspect of the present invention, in the facsimile apparatus according to the first aspect, the filter is a bandpass filter that passes only a specific frequency, and the filter that passes only the specific frequency can be inserted into and removed from the reception path. Elimination of sneaking of the transmission signal to the receiving end, false detection of detection signal,
It is possible to eliminate omission of detection and improve reliability.

According to a third aspect of the present invention, in the facsimile apparatus according to the first or second aspect, there are several types of filters, and these several types of filters are switch-controlled for each use signal.
By having several types of filters and switching them, it is possible to eliminate erroneous detection and omission of detection of signals at all frequencies necessary for detection, and improve reliability.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an essential part for explaining an embodiment of a facsimile apparatus according to the present invention.

FIG. 2 is a flowchart for explaining an incoming call operation during control of a shortened protocol.

FIG. 3 is a flowchart for explaining a normal transmission flow.

[Explanation of symbols]

1 ... General public line, 2 ... Telephone, 3 ... First switching device,
4 ... transformer, 5 ... call detection unit, 6 ... 2-line 4-line conversion unit,
7 ... Filter circuit, 8 ... Second switching device, 9 ... Modem,
10 ... I / O unit, 11 ... Operations such as transmission / reception, 12 ... Switching control unit of switching device.

Claims (3)

[Claims] 1. A facsimile device for connecting a general public line to perform communication, wherein a first switching device for switching and connecting the line to a facsimile device and a telephone and an insulating connection between the line and the facsimile device for signal transmission. A transformer for performing, a call detection unit for detecting a call signal from the exchange, a 2-wire 4-wire conversion unit for converting a 2-wire signal of the line and a 4-wire signal from the modem, and for removing a specific frequency. Filter, a second switching device for switching ON / OFF of insertion of the filter, a modem for performing data demodulation, and an I / O for exchanging input / output control signals.
Section, an operation display section, a switching control section for performing switching control of the second switching device, and a system control section for controlling the facsimile system. When detecting a signal during signal transmission, Controlling the second switching device to insert the filter, removing the sneak of the transmission signal to the modem receiving end, and controlling the second switching device not to insert the filter during communication. Characteristic facsimile machine. 2. The facsimile apparatus according to claim 1,
A facsimile machine, wherein the filter is a bandpass filter that passes only a specific frequency. 3. The facsimile apparatus according to claim 1 or 2, wherein the facsimile apparatus has several kinds of filters and performs switching control for each use signal.