JPH0744639B2 - Fax machine - 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 device that operates based on a predetermined protocol, and more particularly to a facsimile device that uses an international line to perform communication in accordance with CCITT V.21 Recommendation.

[0002]

2. Description of the Related Art Echo is an obstacle to callers, so "echo suppressor" is used for international telephone lines with delays of 45 msec or more and domestic lines with long transmission lines (US etc.).
A device called is attached. This is a device with a special switch for cutting off the voice signal reflected on the receiver side while the speaker is talking, and is equipped for each channel.

However, the echo suppressor, which is indispensable for general telephone calls, also has a problem in performing full-duplex data communication. Therefore, the echo suppressor has a built-in device called a "disabler" for controlling itself.

This disabler operates with a signal (echo suppressor disable tone) in the range of 2100 ± 21 Hz, which continues for 300 ± 100 msec or more, so that an echo is generated.

If no signal continues for more than 100 ms, the echo suppressor is restored.

Since the called station identification signal (CED) which appears first in the facsimile procedure has a frequency of 2100 Hz, the function of the echo suppressor is stopped and an echo is generated.

When the receiving side device sends the called station identification signal, the echo suppressor is stopped and the first initial identification signal (NSF / CSI / D) following the called station identification signal.
When the (IS signal) is transmitted, the echo suppressor is in a stopped state. Then, when an NSS / TSI / DCS signal is sent from the transmitting side device to this initial identification signal, a signalless state of 100 ms or more does not occur between procedure signals, so the echo suppressor function remains stopped. The following steps will be carried out.

[0008]

Therefore, in the above-mentioned case, if many echoes occur, there is a drawback that a pre-procedure error is caused.

In view of the above points, an object of the present invention is to provide a facsimile apparatus for performing communication by causing the data line terminating device to operate the echo suppressor function.

[0010]

In order to achieve the above object, the facsimile apparatus according to the present invention includes a first detecting means for detecting that a signal has not arrived through a line for a predetermined time or more, and a CCITT initial stage. Second detecting means for detecting the identification signal and the called station identification signal, transmitting means for transmitting a CCITT reception command signal in response to the initial identification signal, and the first detecting means for receiving signals for a predetermined time or more. If the initial identification signal is detected without detecting the called station identification signal after detecting that the signal is not present, the sending means is caused to respond to the initial identification signal, while the first detection means outputs a signal. When detecting that the called station identification signal has been detected and the initial identification signal has been detected after detecting that it has not arrived for a predetermined time or more, a control means that does not cause the sending means to respond to the initial identification signal Those having.

[0011]

According to the above configuration of the present invention, when the first detection means detects that the signal has not arrived for a predetermined time or more and then detects the initial identification signal without detecting the called station identification signal, When the first identification means detects that the signal has not arrived for a predetermined time or more and then detects the called station identification signal to detect the initial identification signal, the initial identification signal is changed to the initial identification signal. You can choose not to respond.

[0012]

EXAMPLES The present invention will be described in detail below based on examples.

Here, a facsimile apparatus to which the present invention is applied will be taken as an example, and its configuration and operation will be described.

A transmitting side device (transmitter) to which the present invention is applied is an initial identification signal (N) transmitted from a partner side device (receiver).
After receiving the SF / CSI / DIS signal), the NSS / TSI / DCS signal is transmitted. At this time, when the international communication button provided on the transmitter is pressed, a predetermined signal is transmitted so that the echo suppressor function is always activated. More specifically, the transmitter controls to send NSS / TSI / DCS signals for the second and subsequent initial identification signals sent from the receiver.

FIG. 1 is a block diagram showing in more detail the transmitter side configuration of a facsimile apparatus according to an embodiment of the present invention. This embodiment is based on a CCITT recommendation T4 conforming G3 facsimile machine.

In FIG. 1, 2 is a network control unit NCU (Networ
k Control Unit), which is used to connect the telephone network to terminals on the line to control the connection of the telephone switching network in order to use it for data communication, or to switch to the data communication path and maintain a loop. Fulfill. The signal line 2a is a telephone line. The NCU 2 inputs the signal of the communication line 26a, and when the signal level is "0", the telephone line is connected to the telephone side, that is, the signal line 2a is connected to the signal line 2b. Also NC
U2 inputs the signal of signal line 26a, and this signal level is "1.
", The telephone line is connected to the facsimile machine side, that is, the signal line 2a is connected to the signal line 2c. However, in a normal state, the telephone line 2a is connected to the telephone side.

Reference numeral 4 is a telephone.

Reference numeral 6 is a hybrid circuit for separating a transmission system signal and a reception system signal. This hybrid circuit
6, the transmission signal of signal line 16a is transmitted to signal line 2c and NCU2.
Via the telephone line 2a. The signal sent from the communication partner is output to the signal line 6a via the NCU2 and the signal line 2c.

Reference numeral 8 denotes a reading circuit, which sequentially reads an image signal for one line in the main scanning direction from a document to be transmitted, and creates a signal string representing binary values of white or black. This reading circuit 8
Is composed of an image pickup device such as a CCD (charge coupled device) and an optical system. Then, the binarized signal string representing white or black is output to the signal line 8a.

Reference numeral 10 is an encoding circuit, which inputs the binarized data output to the signal line 8a and performs encoding.
Data that has been MH (Modified Huffman) encoded or MR (Modified Read) encoded in this encoding circuit 10 is output to the signal line 10a.

Reference numeral 12 denotes a modulator, which is a known CCITT recommendation V27t.
Modulation based on er (differential phase modulation) or V29 (quadrature modulation) is performed. The modulator 12 receives the signal on the signal line 10a, modulates the signal, and outputs the modulated data to the signal line 12a.

Reference numeral 14 is a modulator for performing the modulation based on the well-known CCITT recommendation V21. The modulator 14 receives the procedure signal on the signal line 26b, performs modulation, and outputs the modulated data to the signal line 14a.

Reference numeral 16 is an adder circuit which inputs the signals of the signal line 12a and the signal line 14a and outputs the addition result to the signal line 16a.

Reference numeral 18 denotes a signal disconnection detection circuit, which inputs a signal from the signal line 6a and outputs a signal having a signal level "1" to the signal line 18a when no signal arrives continuously for 100 ms or longer.

Reference numeral 19 denotes a 2100 Hz detection circuit, which inputs a signal on the signal line 6a and, for example, over 200 msec during 500 msec.
When the 2100 Hz signal is detected, the signal of signal level "1" is output to the signal line 19a. This 2100 Hz signal is a called station identification signal.

Reference numeral 20 denotes a GI signal detection circuit, which inputs a signal on the signal line 6a and which receives a group identification signal (GI1 / 2 signal, GI1 signal, GI signal).
2 signal), the signal level “1
Signal is output.

Reference numeral 22 is a demodulator that performs demodulation based on the well-known CCITT Recommendation V21. The demodulator 22 receives the signal on the signal line 6a, performs V21 demodulation, and outputs the demodulated data to the signal line 22a.

Reference numeral 24 is a circuit for detecting whether or not the international communication button in the operation section (not shown) is pressed. This international communication button press detection circuit 24 outputs a signal of signal level "1" to the signal line 24a when the international communication button is pressed, and outputs a signal to the signal line 24a when the international communication button is not pressed. Level "0
Signal is output.

Reference numeral 26 is a control circuit for performing control so that the echo suppressor function is always operated according to a predetermined protocol when the international communication button is pressed. As a method to make sure this echo suppressor function works,
The second and subsequent initial identification signals (NSF) sent from the receiver side
/ CSI / DIS signal) and NSS / TSI / DCS signal should be sent. Therefore, the easiest way to activate the echo suppressor function is to detect the NSF / CSI / DIS signal twice and then
It is sufficient to send S / TSI / DCS signals.

FIG. 2 is a diagram showing an example of the above-mentioned pre-procedure. However, when the echo suppressor function is activated by the above method, when the start key is pressed on the transmitter side at the time of (A) or (A), NSS / TSI /
The timing of sending the DCS signal is delayed once (the NSS / TSI / DCS signal is sent in response to the NSF / CSI / DIS signal sent after symbol 36 in Fig. 2). Therefore, in this embodiment, even when the start key is pressed on the transmitter side at the time of (a) or (a) in FIG. 2, the NSS / TSI / DCS signal can be transmitted at the timing of reference numeral 38. To control.

Specifically, when the international communication button is pressed, the GI signal is detected and then the NSF / CSI / DIS signal is detected, or the signal disconnection is detected and 2100 Hz is not detected thereafter. When the NSF / CSI / DIS signal is detected or when the NSF / CSI / DIS signal is detected twice, NSS / TSI / DC
Sends the S signal and controls to activate the echo suppressor function.

FIG. 3 is a flowchart showing a control procedure to be executed by the control circuit 26 shown in FIG.

In FIG. 3, in step S40, the telephone line is connected to the telephone side. That is, the signal of the signal level "0" is output to the signal line 26a.

In step S42, it is determined whether transmission is selected. When transmission is selected, step
Continue to S44.

In step S44, the telephone line is connected to the facsimile machine side. That is, the signal of the signal level "1" is output to the signal line 26a.

In step S46, "0" is set in the counter COUNT used to count the number of times the NSF / CSI / DIS signal is detected.

In step S48, the timer T1 is set to 35.
Set the seconds.

In step S50, it is determined whether or not the international communication button is pressed, that is, whether or not the signal line 24a is at the signal level "1". When the international communication button is pressed, that is, when the signal line 24a is at the signal level "1", the process proceeds to step S52. When the international communication button is not pressed, that is, when the signal level of the signal line 24a is "0", the process proceeds to step S54.

In step S52, it is determined whether or not the GI signal is detected, that is, whether or not the signal line 20a is at the signal level "1". When the GI signal is detected, that is, when the signal line 20a is at the signal level "1", the process proceeds to step S54. When the GI signal is not detected, that is, when the signal line 20a is at the signal level "0", the process proceeds to step S70.

In step S54, it is determined whether the NSF / CSI / DIS signal is detected. This judgment is based on the signal line
Input the signal of 22a. At this time, if the NSF / CSI / DIS signal is detected, the process proceeds to step S62. NSF / CSI / DI
If the S signal is not detected, the process proceeds to step S56.

In step S56, it is determined whether or not the timer T1 has timed out. When the timer T1 has not timed out, the process proceeds to step S54. When the timer T1 times out, the process proceeds to step S58.

In step S58, the telephone line is connected to the telephone side. That is, the signal of the signal level "0" is output to the signal line 26a.

Step S60 represents an error state.

In step S62, the NSS / TSI / DCS signal is output to the line by outputting the signal to the signal line 26b.

Step S64 represents the subsequent pre-procedure.

Step S66 represents image transmission.

Step S68 represents a post procedure.

In step S70, it is determined whether or not a signal break has been detected, that is, whether or not the signal line 18a is at the signal level "1". When the signal disconnection is detected, that is, when the signal line 18a is at the signal level "1", the process proceeds to step S72.

When the signal disconnection is not detected, that is, when the signal line 18a is at the signal level "0", step S8 is performed.
Go to 0.

In step S72, it is determined whether or not the NSF / CSI / DIS signal is detected once or more, that is, whether or not COUNT is 1 or more. When the NSF / CSI / DIS signal is detected once or more, that is, when COUNT is 1 or more, the process proceeds to step S54. When the NSF / CSI / DIS signal has never been detected, that is, when COUNT = 0, the process proceeds to step S74.

In step S74, it is determined whether or not a 2100 Hz signal is detected, that is, the signal line 19a is at the signal level "1".
, ”Is determined. When the signal of 2100 Hz is detected, that is, when the signal line 19a is at the signal level "1", the process proceeds to step S86. When the 2100 Hz signal is not detected, that is, when the signal line 19a is at the signal level "0", the process proceeds to step S76.

In step S76, it is determined whether the NSF / CSI / DIS signal is detected. This judgment is based on the signal line
Input the signal of 22a. If the NSF / CSI / DIS signal is detected, the process proceeds to step S62. When the NSF / CSI / DIS signal is not detected, the process proceeds to step S78.

In step S78, it is determined whether or not the timer T1 has timed out. When the timer T1 has not timed out, the process proceeds to step S74. When the timer T1 times out, the process proceeds to step S58.

In step S80, it is determined whether the NSF / CSI / DIS signal is detected. This judgment is based on the signal line
Input the signal of 22a. If the NSF / CSI / DIS signal is detected, the process proceeds to step S82. When the NSF / CSI / DIS signal is not detected, the process proceeds to step S86.

In step S82, the counter COUNT used to count the number of times the NSF / CSI / DIS signal is detected is incremented by 1.

In step S84, it is determined whether or not the NSF / CSI / DIS signal is detected twice or more, that is, whether or not COUNT is 2 or more. When the NSF / CSI / DIS signal is detected twice or more, that is, when COUNT is 2 or more, the process proceeds to step S62. NSF / CSI / DIS signal detection is 2
When it is less than the number of times, that is, when COUNT is less than 2, the process proceeds to step S86.

In step S86, it is determined whether the timer T1 has timed out. When the timer T1 has not timed out, the process proceeds to step S52. When the timer T1 times out, the process proceeds to step S58.

In the above-described embodiments, whether or not the international communication is performed is detected by the pressed state of the international communication button. However, the present invention is not limited to this embodiment, and it is also possible to receive the initial identification signal NSF / CSI / DIS signal and automatically identify whether or not it is an international communication.

[0059]

As described above, according to the present invention,
When the first detecting means detects that the signal has not arrived for a predetermined time or more and then detects the initial identification signal without detecting the called station identification signal, the first identification means is caused to respond to the initial identification signal.
If the first detection means detects that the signal has not arrived for a predetermined time or more and then detects the called station identification signal and detects the initial identification signal, it does not respond to the initial identification signal.
The communication can be controlled so that the echo suppressor function is activated during communication, and a good communication state is ensured without causing a pre-procedure error even under adverse conditions in which many echoes occur. Will be possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a facsimile apparatus to which the present invention is applied.

FIG. 2 is a diagram showing an example of a pre-procedure.

FIG. 3 is a flowchart showing a control procedure of a control circuit 26 shown in FIG.

[Explanation of symbols]

 2 NCU (Network control unit) 4 Telephone 6 Hybrid circuit 8 Reading circuit 10 Encoding circuit 12 V27ter or V29 Modulator 14 V21 Modulator 16 Addition circuit 18 Signal loss detection circuit 19 2100Hz detection circuit 20 GI signal detection circuit 22 V21 Demodulator 24 International communication button press detection circuit 26 Control circuit

Claims (2)

[Claims] 1. A first detecting means for detecting that a signal has not arrived through a line for a predetermined time or more, a second detecting means for detecting an initial identification signal of CCITT and a called station identification signal, and the initial means. Sending means for sending a CCITT reception command signal in response to an identification signal; and the first detecting means, after detecting that the signal has not arrived for a predetermined time or more, without calling the called station identification signal. When the initial identification signal is detected, the sending means is caused to respond to the initial identification signal, while the first detection means detects that the signal has not arrived for a predetermined time or more A facsimile machine, comprising: a control means for preventing the sending means from responding to the initial identification signal when the initial identification signal is detected. 2. A setting means for setting to perform international communication, wherein the control means does not detect the called station identification signal when the setting means sets to perform international communication. When the initial identification signal is detected, the sending means is made to respond to the initial identification signal. On the other hand, when the setting means is not set to perform international communication, the result of detection of the called station identification signal and 2. The facsimile apparatus according to claim 1, wherein the sending means is caused to respond to the initial identification signal regardless of the detection result of the first detecting means.