JPH057912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a facsimile device, and more specifically, when a control signal sent from the other party's facsimile device is detected during image transmission or procedure operation, the present invention is based on the control signal. The present invention relates to a facsimile device that performs operations.

As a control signal, we are considering an immediate stop signal (hereinafter referred to as a PIS signal).

PRIOR ART When a PIS signal is detected as a conventional facsimile device during G2 communication or mini-facsimile communication, there is a facsimile device that immediately stops operation, makes an operator call, or terminates with an error.

In such a device, if the device is a transmitter, it is necessary to detect a PIS signal whose amplitude level has been attenuated, which is sent from the other party's facsimile device while transmitting an image signal.

For this reason, the transmitting system and receiving system of the facsimile device are usually of a hybrid configuration, and the PIS signal is detected while transmitting the image signal.

However, if the impedance cannot be matched with the telephone line, the hybrid circuit will not be able to completely separate the transmitting system signal from the receiving system signal, and the transmitting system signal will inevitably go around to the receiving system. .

Therefore, the signal appearing in the receiving system is no longer a signal consisting of one frequency component.

Conventionally, the PIS signal was detected by first passing the PIS signal component through a filter, integrating this signal, and comparing the integrated signal with a reference voltage.

On the other hand, if the facsimile device is a receiver,
With the same circuit configuration as the transmitter described above,
It was detecting PIS signals.

Therefore, if there are many frequency components of the PIS signal included in the image signal, the receiver recognizes that a PIS signal has been detected and immediately stops the transmitter even though the transmitter does not have an immediate stop function. There was a serious drawback.

Purpose The present invention has been made in order to solve the above problems, and is a malfunction-free device that can reliably interrupt image communication in accordance with the transmission and reception of a control signal having a predetermined frequency for interrupting image communication. The purpose is to provide facsimile equipment.

Embodiments Hereinafter, details of the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 illustrates an embodiment of the present invention.
In the figure, the reference numeral 1 is a 2-3 value changing circuit, which takes in an image signal binarized by photoelectric conversion from a signal line 1a, converts it into a 3-value signal, and sends it to a low-pass filter via a signal line 1b. 2.

The low-pass filter 2 limits the band of the ternary signal so that aliasing distortion does not occur during modulation, and inputs the signal to the modulator 4 via the signal line 2a.

On the other hand, the one indicated by code 3 is a carrier wave generation circuit that generates a 2100Hz carrier wave, and this carrier wave is transmitted to the signal line 3.
It is input to the modulator 4 via a.

The modulator 4 modulates the signal on the signal line 2a with a carrier wave, and generates a vestigial sideband (VSB) via the signal line 4a.
Input to filter 5.

The characteristic of this VSB filter is that the amplitude level is attenuated by 6 bB at the carrier wave frequency, and it is a low-pass filter having a point-symmetrical amplitude characteristic. The signal passing through this is input to the equalizer 6 via the signal line 5a. The equalizer 6 has a function of correcting the attenuation distortion of the telephone line, and the signal passing through the equalizer 6 is sent to the signal line 6.
It is input to the hybrid circuit 7 via a.

The hybrid circuit 7 receives transmitting system signals and receiving system signals, and the signal on the signal line 6a, which is the transmitting system signal, passes through this circuit and is transferred from the network control device 8 to the telephone line 8a via the signal line 7a. Sent out.

The above is the control circuit on the transmitting side. On the other hand, the signal sent from the other party's facsimile device is input to the receiving system equalizer 9 via the network control device 8, the signal line 7a, the hybrid circuit 7, and the signal line 7b.

Note that the network control circuit 8 described above uses the telephone network for data communication, etc., so it connects to the terminal of the telephone line and controls the connection with the telephone switching network and switches to the data communication path. It also maintains line loops.

Similar to the equalizer on the transmitter side, the equalizer 9 on the receiver side also corrects the attenuation group delay distortion of the signal due to the telephone line, and the signal passing through this is sent to the band pass filter 10 via the signal line 9a. is input.

The bandpass filter 10 is a filter for removing billing pulses, hum, impulsive nozzles, etc., and the signal passing through this filter is input to an automatic gain control (AGC) circuit 11 via a signal line 10a.

This AGC circuit is transmitted from a facsimile transmitter, compensates for the attenuation while reaching the receiver, amplifies it to a certain level, and inputs it to the demodulator 12 via the signal line 11a.

The demodulator 12 extracts a carrier wave from the output signal of the AGC circuit 11, performs synchronous detection, performs full-wave rectification, and inputs it to the synchronous signal detection circuit 13 via the binarized signal line 12a. This circuit detects whether or not a synchronization signal is being received.
When a synchronizing signal is detected, a signal level "1" is output to the signal line 13a, and when a synchronizing signal is not detected, a signal level "0" is detected.

The output from this synchronization signal detection circuit 13 is input to a control circuit 18, which will be described later, via a signal line 13a. On the other hand, the output of the signal line 10a is also input to the PIS signal detection circuit 14. This detection circuit 14 is a PIS
At a certain amplitude level of the 462Hz signal,
This circuit detects whether or not it continues for a certain period of time, and is composed of a filter, an integrating circuit, a comparing circuit, etc.

And when the PIS signal is not detected,
A signal level "0" is output to the signal line 14a,
When the PIS signal is being detected, a signal level "1" is output to the signal line 14a.

The signal on this signal line 14a is also input to the control circuit 18.

Further, the signal on the signal line 10a is also input to the amplifier circuit 15.

This amplification circuit is a circuit that amplifies the attenuated signal on the signal line 10a, and the amplified signal is transmitted to the signal line 10a.
The signal is input to the binarization circuit 16 via 5a.

The binarization circuit 16 binarizes the signal on the signal line 15a with respect to a certain reference voltage, and the binarized signal is input to the tonal counter circuit 17 via the signal line 16a.

The tonal counter circuit 17 receives the signal on the signal line 16a and measures the time of one period of the tonal signal, and recognizes the frequency of the tonal signal from the time of one period.

When the measurement of one period of the tonal signal is completed, an impulse is generated on the signal line 17a, and the frequency of the tonal signal is outputted on the signal line 17b.

By the way, the tonal counter uses the tonal signals (specifically, 462Hz, 1100Hz, 1850Hz, and 2100Hz signals) sent from the other party's facsimile machine.
It is used to recognize the frequency of a signal that has continued for a certain period of time.

Two methods are considered for this recognition method.

The method is shown in FIGS. 2A and 2B.

The method shown in FIG. 2A is a method of measuring the time of one cycle P and determining the frequency.

The method shown in FIG. 2B is a method of measuring the number of tonal signals during a certain period of time P and determining the frequency. In this embodiment, the frequency is determined by the method shown in FIG. 2A.

In addition, in FIGS. 2A and 2B, the waveform located on the upper side is a tonal signal, and the waveform located on the lower side is an output waveform from the binarization circuit 16.

By the way, the control circuit 18 described above performs the control described below.

That is, if the facsimile device is a transmitter, it accepts the output of the signal line 14a, determines whether or not this output has a signal level of "1", and when the signal level becomes "1", it determines that a PIS signal has been detected. judge.

If the facsimile device is a receiver, it takes in the signal on the signal line 13a and determines whether the signal level is "0", that is, whether the synchronization signal is no longer detected.

After the signal level of the signal line 13a becomes "0", the tonal counter circuit 17 receives a tonal signal.

Here, if the frequency of the tonal signal is 462 Hz, it is determined that the PIS signal has been detected.

In other words, in the case of a receiver, the PIS signal is detected for the first time after the synchronization signal is no longer detected.

Next, a specific flow of control of the control circuit 18 in the case of communication in the G2 mode will be explained with reference to FIG.

First, in step 20, it is determined whether the device is in a transmitting state. Step if in sending state
Proceed to step 21, and if not in the transmitting state, proceed to step 23.

In step 21, it is determined whether the output of the signal line 14a is at the "1" level. That is, it is determined whether a PIS signal from the other party's facsimile device has been detected. And signal line 1
When the output of 4a becomes "1", it is determined in step 22 that the PIS signal has been detected.

On the other hand, in step 23, it is determined whether the device is in a receiving state.

If it is determined that the receiving state is not present, the process returns to step 20, and if it is determined that the receiving state is not, the process proceeds to step 24.

In step 24, it is determined whether the output of the signal line 13a is at the "0" level, that is, whether the synchronizing signal is no longer detected.

The process proceeds to step 25 only when the output of the signal line 13a reaches the "0" level, that is, when no synchronizing signal is detected.

In step 25, when a 462Hz signal is detected for a certain number of cycles, it is determined that a PIS signal has been detected.
This constant number a is stored in a memory named CNT462. Next, proceed to step 26, and when the 1100Hz signal is detected for a certain number of b periods, EOM2
It is determined that a signal (message end signal) has been detected, and a certain number b is stored in a memory named CNT 110.

The process then proceeds to step 27, where it is determined whether a pulse has occurred on the signal line 17a. That is, it is determined whether the measurement of one cycle of the tonal signal has been completed. If it is determined that a pulse has occurred on the signal line 17a, it is determined that the measurement of one cycle of the tonal signal has been completed, and the process proceeds to step 28.

If not, repeat step 27.

The process then proceeds to step 29, where it is determined whether the frequency accepted in step 28 is 462 Hz. If it is 462Hz, proceed to step 30; otherwise proceed to step 33.

On the other hand, in step 30, the memory contents of CNT 462 are decremented by one. Then, the process proceeds to step 31, and if the contents of the memory CNT462 are negative, that is,
It is determined whether a PIS signal is detected. and
The content of CNT462 is not negative, i.e. PIS
If it is determined that no signal is detected, the process returns to step 27.

Further, when the content of CNT 462 is negative, it is determined in step 32 that a PIS signal has been detected.

By the way, in step 33, it is determined whether the frequency accepted in step 28 is 1100 Hz. If it is 1100Hz, proceed to step 34; otherwise, return to step 27.

In step 34, the contents of the memory CNT 110 are decremented by one. Then proceed to step 35.
Whether the content of CNT110 is negative or not, that is, EOM2
It is determined whether a signal is detected. and
The content of CNT110 is not negative. i.e. EOM
If no signal is detected, return to step 27, and if the content of CNT110 is negative, EOM
It is determined in step 36 that two signals have been detected.

Since this embodiment is configured as described above,
In the case of image signal reception, the PIS signal, which is a control signal, is received after the synchronization signal is no longer detected, so even if the image signal sent from the transmitter contains many frequency components of the PIS signal, the PIS The inconvenience of recognizing that a signal has been detected is completely eliminated, and the disadvantage that the receiver immediately stops even though the transmitter side does not have an immediate stop function is eliminated.

By the way, in the above embodiment, when the facsimile device is a receiver, the control signal is received in the tonal counter circuit after the synchronization signal is no longer detected. This is because there is a possibility that an EOM2 signal will come.

However, if only the PIS signal is considered, the tonal counter circuit does not need to receive the control signal. That is, it is also possible to make the determination by inputting the output signal of the PIS signal detection circuit.

In other words, when a control signal is detected during image transmission or procedure operation, a facsimile device that operates based on the control signal detects the control signal only after it stops detecting the synchronization signal when receiving the image signal. become.

Effects As is clear from the above description, according to the present invention, the control signal is detected by passing the frequency component of the control signal from the received signal, integrating the passed signal, and comparing it with the reference voltage. and a second detection means for detecting a control signal by binarizing the received signal, measuring its period to recognize the frequency, and recognizing the frequency of the control signal, and transmitting the signal. While operating as a machine and transmitting an image signal, the first detection means detects a control signal;
On the other hand, while operating as a receiver, the second detection means is configured to detect the control signal on the condition that no image signal is being received. The present invention has an excellent effect in that control signals can be detected immediately, and malfunctions of the device due to erroneous detection of control signals can be reliably prevented.

[Brief explanation of the drawing]

The figure explains one embodiment of the present invention.
2 is a block diagram of the control circuit, FIGS. 2A and 2B are explanatory diagrams of different tonal signal frequency determination methods, and FIG. 3 is a flowchart diagram illustrating the control operation. 1...2-3 value conversion circuit, 2...Low pass filter, 3...Carrier wave generation circuit, 4...Modulator, 5
... Residual sideband filter, 6, 9 ... Equalizer, 7
...Hybrid circuit, 8...Network control device, 10
... Bandpass filter, 11 ... Automatic gain adjustment circuit, 12 ... Demodulator, 13 ... Synchronization signal detection circuit, 14 ... PIS signal detection circuit, 16 ... Binarization circuit, 17 ... Tonal counter circuit , 18...
control circuit.

Claims (1)

[Claims] 1. In a facsimile device that detects a control signal having a predetermined frequency for interrupting image communication while operating as a transmitter and as a receiver, a first detection means for detecting the control signal by passing a frequency component, integrating the passed signal, and comparing the integrated signal with a reference voltage; and binarizing the received signal; a second detection means for detecting the control signal by recognizing the frequency by measuring the period and detecting the control signal by recognizing the predetermined frequency; and a second detection means for detecting whether or not an image signal is being received. 3
and a detection means for causing the first detection means to detect the control signal when operating as a transmitter and transmitting an image signal, and on the other hand, when operating as a receiver and causing the above-mentioned second detection means to detect the control signal when the image signal is not being received. A facsimile apparatus comprising a control means for causing a detection means to detect the control signal.