JP2556306B2 - Data communication method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data communication system, and more particularly to a data communication system in which communication is not possible beyond a communication time of a predetermined time length.

2. Description of the Related Art There is no ordinary wired or wireless communication system having a limited communication time except for pay public telephones, for example.

As a wireless system, there is a system for effectively using radio waves by setting a restriction on communication time, for example, an MCA (multi-channel access) system. In this method, the communication connection is forcibly disconnected when the communication time of a predetermined length elapses.

However, when facsimile communication is performed by the MCA method, the line connection may be disconnected during the communication, for example, while transmitting a page with a document. For any reason, such call recovery is difficult to judge not only on the receiving side but also on the transmitting side. Therefore, information may not be properly transmitted.

Therefore, even in a communication system with such a limited communication time, information is reliably and efficiently transmitted,
A method for efficiently using the entire system is required.

Aim of the Invention The present invention has been made in view of such a demand, and an object of the present invention is to provide a data communication system that allows a receiving side to grasp the reason why information is not normally transmitted.

In order to achieve the above object, the present invention provides a data communication method in which communication cannot be performed over a communication time of a predetermined time length, the transmitting station monitors the elapsed time from the start of communication with the receiving station, When the remaining time obtained by subtracting the elapsed time from the predetermined length of communication-enabled time is not long enough to send one unit of information, a signal indicating that fact is sent to the receiving station to disconnect the communication, and the receiving station Is characterized by outputting the signal when the signal is received.

In this specification, the term "data" is to be interpreted in a broad sense, including not only digital data in a narrow sense, but also analog image information such as facsimile information and voice information. Hereinafter, a specific description will be given based on an embodiment of the present invention.

Referring to FIG. 1, in an embodiment of the data communication system according to the present invention, a facsimile machine 100 is connected to a transceiver 200. In the present embodiment, the transmitter / receiver 200 is a wireless transmitter / receiver according to the MCA communication method in which the use of radio waves is time-limited, and it transmits radio waves in a predetermined band to other stations and receives them from other stations. Is configured. However, the present invention is effectively applied not only to the MCA communication method but also to any wireless or wired communication system with a limited communication time.

The signal line 102 from the transceiver 200 is a modulator / demodulator (MODEM) 1
Coding decoder (CODEC) 10 via 04 and buffer 106
Connected to 8. The buffer 106 is a memory that temporarily stores facsimile data to be transmitted and received facsimile data. The modulator / demodulator 104 is a modulator / demodulator that modulates a facsimile signal to be transmitted by a predetermined modulation method and demodulates a received facsimile signal. The encoding / decoding unit 108 is an encoding / decoding circuit that frames a facsimile signal to be transmitted, compression-encodes it according to a predetermined encoding method, deframes the received facsimile signal, and decodes / reproduces with the encoding method.

The facsimile data to be transmitted is sequentially read from the original by raster scanning by the photoelectric conversion element of the reading unit 116 and stored in the line buffer 118 in units of one sub-scanning line. This is sequentially read from the line buffer 118 to the encoding / decoding unit 108 and transferred to the buffer 106 through the changeover switch SW1 of the encoding / decoding unit 108.

On the other hand, the received facsimile data is stored in the buffer 106.
The data is read from the encoder / decoder 108 to the line decoder 120 through the changeover switch SW2 of the encoder / decoder 108 and stored in the sub-scanning line unit by one sub-scanning line. This is the line buffer 12
The data is sequentially read from 0 to the recording unit 122, and is recorded as a hard copy on the recording medium 500 (FIG. 4) by the recording unit 122.

The changeover switch SW1 has a transmission side terminal S and a character output terminal C, and the character output terminal C is finally connected to the image signal conversion section 124 together with the terminal C of the switch SW2. The receiving side terminal R of the changeover switch SW2 is the switch SW1.
Finally, it is connected to the buffer 106. Switching of the changeover switches SW1 and SW2 is controlled by the system control unit 136.

The image signal conversion unit 124 is a circuit that is connected to the character generation circuit (CG) 126 and converts the character pattern data generated by the character generation circuit 126 into an image signal. When the character data generated in this device is transmitted from the receiver 200, the output of the image signal conversion unit is transferred to the buffer 106 through the switch SW1, and when the character data generated in this device is output to the recording unit 122, The output of the image signal converter 124 is transferred to the line buffer 120 through the switch SW2. The character generation circuit 126 may be a normal character generator that generates character pattern data according to the character data from the system control unit 136 or the timer circuit 130.

The signal line 102 is also connected to the procedure signal detector 110, the procedure signal transmitter 112, and the call detector 114. The procedure signal detection unit 110 has a function of detecting a procedure signal received by the transceiver 200 from the partner station in a facsimile transmission control procedure such as a G3 facsimile transmission control procedure according to CCITT recommendation. The procedure signal transmission unit 112 includes a procedure signal control unit 128.
Under the control of (1), it is a functional unit that sends to the transceiver 200 a procedure signal to be transmitted from the transceiver 200 to the partner station in a facsimile transmission control procedure.

The call detection unit 114 has a function of detecting a call signal received by the transceiver 200 from the partner station and notifying the system control unit 136 when the present device is in the automatic call reception mode. The call detection unit 114 is connected to the timer circuit 130 via the changeover switch SW3 controlled by the system control unit 136.

As will be described later, the timer circuit 130, when making a call, calls the partner station to start the communication, and the system control unit 13
6 is a counting circuit which is activated in 6 and counts the passage of communication time within a predetermined communicable time T (FIG. 2) assigned to the transmitter / receiver 200 for transmitting radio waves. Its output 13
2 is connected to the encoding / decoding circuit 108, the procedure control unit 128, and the character generation circuit 126.

The function and operation of each of these parts in the device are centralized and controlled by the system controller 136. System control unit 136
Is advantageously constituted by a processing system such as a microprocessor in the present example.

A display 138 is connected to the system controller 136.
This is for displaying to the user that the connection has been cut off due to lack of remaining communication time while the original 300 to be transmitted remains. This display may be a visual display or an audio audible display.

By the way, in a communication system in which the communication time length is limited, the connection may be forcibly disconnected during the transmission of one unit of message. In this embodiment, in the case of such a line disconnection, the reason is notified to the partner station as an auxiliary message according to the stage of the communication sequence. The timer circuit 130 secures the time ta required for transmitting this auxiliary message within the communicable time T and sets a time limit for the intermediate transmission of the document information before that, that is, a predetermined period shown in FIG. It has a function of monitoring the time t.

As shown in FIG. 2, for example, when transmitting a long message that exceeds the communication available time T, if the remaining communication available time becomes short, as shown in FIG. If so, the call connection is suddenly restored, and it becomes impossible for the receiving station RX as well as the transmitting station TX to accurately grasp the situation. In order to avoid such a situation, in the present embodiment, the transmitting station TX stops the transmission of the message after the elapse of a predetermined time t, and at the remaining time ta, the reason for the transmission stop is set as an auxiliary message as the receiving station RX. Then, the receiving station RX records this as visible information such as characters or symbols on a part 502 of the recording paper 500.

More specifically, such a procedure for stopping transmission is classified into the following three types depending on where in the communication sequence the time period t occurs.

First, there is a case where it takes time t during transmission of a message. This is illustrated in FIG. 2 (a), for example. In this case, the transmission of the message is stopped after the elapse of the time t, and the auxiliary message is transmitted at the predetermined remaining time ta. This ancillary message is advantageously used, for example, that "the specified time has passed and the message still remains but cannot be sent in full".

After the transmission of this auxiliary message is completed, a normal termination procedure is performed, that is, a sequence of transmitting an EOP (procedure end) signal, returning an MCF signal, and transmitting a DCN (disconnect command) signal, that is, the process moves to x in FIG. . Therefore, the length of the predetermined time period t is selected so that these auxiliary messages can be transmitted and the termination procedure can be executed within the remaining time ta within the communicable time T. This is set in the timer circuit 130.

Next, there may be a time t after the end of message transmission. For example, this is the case shown in FIG. Generally, since the time tb required from the end of message transmission to the end of communication control procedure, that is, the end of DCN signal transmission is short, even if the normal end procedure is executed as it is, there is a problem that it is disconnected during the process. Absent. Therefore, in this case, the normal termination procedure is executed. The length of the predetermined time period t is selected so that the required execution time tb of the termination procedure falls within the remaining time ta within the communicable time T (ta = tb). This is set in the timer circuit 130.

A third possibility is disconnection before sending the message. For example, as in the point (c) in FIG. 3, it is a period y from the end of sending one message to the start of sending the next message. If the communication is configured to continue as it is even if the predetermined time t elapses during this period y, the communication available time T elapses and the line is disconnected during the transmission of the next message. Will end up. Another possibility is (d) in FIG.
There is an example that occurs just after the start of communication like
This is extremely rare in reality, and the explanation is omitted here.

Therefore, in the present embodiment, when the transmitting station TX takes a time period t in the period y, it transmits to the receiving station RX that "the communication is close to the end, and there is a next message but it cannot be transmitted" to terminate the communication. . In this notification, an EOP1 signal with a format different from the normal EOP signal is transmitted from the transmitting station TX to the receiving station RX.
This is advantageously done by sending to.

Although there is no problem in full-duplex communication, for example, in unidirectional communication using a single frequency, even if a signal is transmitted from the other station TX while the other station TX is transmitting some signal such as an MCF signal Not received correctly by station RX. For example, as shown in (c) of FIG. 3, when the time t after the MPS signal transmission is reached,
This is a sequence in which the receiving station RX transmits an MCF signal, and the transmitting station TX is waiting in a receiving state. Transmitting station TX in this state
However, if some kind of signal such as the above-mentioned auxiliary message is sent, both of them will be in a transmission state and the communication system will not be established.

Therefore, in the present embodiment, the transmitting station TX is configured to receive and detect the MCF signal, then transmit the EOP1 signal, and subsequently execute a normal termination procedure including reception of the MCF signal and transmission of the DCN signal. ing. This EOP1 signal is slightly different from the normal EOP signal,
It carries the information that there is the next message but it cannot be sent. The receiving station RX identifies this and prints a message to that effect.
It can be displayed (502) on 500 or can be displayed on the display 138.

Also, as shown in FIG. 3 (e), after the message is sent.
When a time t is reached before the MPS signal is transmitted, the procedure skips to the transmission of the EOP1 signal as indicated by the dotted line 510 in the figure, and the communication termination procedure is executed.

By the way, when the transceiver 200 uses the MCA wireless communication system, there is a time restriction of using the radio wave, and therefore the radio wave is efficiently used from the viewpoint of the entire system.

Referring to FIG. 2, a call connection flow in which the present apparatus performs typical facsimile transmission of a document of a plurality of pages according to the CCITT recommended G3 facsimile transmission control procedure will be described. In this example, the device functions as the transmitting station TX. Receiving station
RX may be this device or another device.

The system control 136 of the transmission station TX first activates the procedure signal control unit 128 in response to an instruction from the operator, and then the procedure signal transmission unit 1
Call the receiving station RX from 12 through the transceiver 200. This calling is performed by sending a calling signal in the automatic mode. In response to the ringing signal, the receiving station RX sends back a CED (Called station identification) signal to the transmitting station TX, followed by DIS.
(Digital identification) signal is returned. In the manual mode, the transmitting station TX calls by a voice signal, and the receiving station RX responds to this by operating the operation button.

The system control unit 136 of the transmitting station TX connects the switch SW3 to the terminal TX side together with the calling of the partner station, and the timer circuit 1
Start 30. As a result, counting of the already communicated time is started. The procedure signal detection unit 110 of the transmission station TX detects the CED and DIS signals, and the system control unit 136 responds to this and sends out a DCS (digital command) signal in the same manner as described above.
After that, a predetermined modem training pattern signal is transmitted to the receiving station RX according to a normal facsimile transmission control procedure, and training of the modulation / demodulation device of the receiving station RX is performed.
When the receiving station RX finishes the training, it returns a CFR (reception preparation confirmation) signal to the transmitting station TX.

When the transmitting station TX detects the CFR signal in the procedure signal detection unit 110, the system control unit 136 causes the encoder / decoder 108 to switch.
SW1 is connected to the S terminal side, and the reading unit 116 is controlled to start reading the image information of the document. The image information, that is, the message read from the manuscript is compression-encoded via the line buffer 118, the encoder / decoder 108, the buffer 106, and the modulator / demodulator 104, assembled into a transmission frame, modulated, and transmitted as a radio wave from the transceiver 200. Sent out.

The receiving station RX receives this message, demodulates it, deframes it, reproduces the code, and finally outputs it as a hard copy 504 from the recording unit to the recording paper 500.

Generally, at the beginning of reception, sender information and date / time information 506 are recorded. For this, for example, the sender display function described in JP-A-54-106110 is advantageously applied. At that time, the system control unit 136 sets the switch SW1 of the encoder / decoder 108 to the terminal C.
To the side. As for the data of the transmission source, a necessary message is assembled from the system control unit 136 and the timer circuit 130 of the transmission station TX, expanded by the character generation circuit 126 as dot pattern data, and transmitted. At the receiving station RX, this is recorded on the recording paper 500 by the recording unit 122 in the same manner as a normal message.

In this embodiment, the image information message for one unit, that is, one page in this embodiment is transmitted from the transmitting station. When the next transmission original does not exist, the system control unit 136 of the transmission station TX sends an EOP (procedure end) signal in the end processing, and the reception station RX returns an MCF signal in response to this. When the TX of the transmitting station detects the MCF signal, it returns a DCN (disconnect command) signal to the receiving station RX to restore this connection.

Meanwhile, during that time, the system control unit 136 of the transmitting station TX monitors the count value of the timer circuit 130. When this count value, that is, the already-communication time reaches the above-mentioned predetermined reference value t, if the message is being transmitted, the transmission is stopped and the above-mentioned auxiliary message addition or EOP1 signal transmission, etc., is necessary. The call connection is finally restored by performing the processing.

For example, as in the case of FIG. 2 (a), when it takes time t while transmitting a normal message from the transmitting station TX,
The system control unit 136 suspends the transmission of the message and connects the switch SW1 of the encoding / decoding unit 108 to the terminal C side. The above-mentioned auxiliary message is assembled from the system control unit 136 and the timer circuit 130, expanded by the character generation circuit 126 as dot pattern data, and transmitted. At the receiving station RX, this is done in the same way as a normal message.
2 is used to record on a part 502 of the recording paper 500.

After that, the system control unit 136 of the transmission station TX performs a normal termination process x (FIG. 2). That is, the EOP signal is sent out, and the receiving station RX sends back the MCF signal in response to this.
When TX of the transmitting station detects the MCF signal, it receives the DCN signal and RX of the receiving station
Return to and restore this connection.

In FIG. 4, when the facsimile information of the original having the length L is being transmitted from the transmitting station TX, the length L1 of the recording paper 506 in the sub-scanning direction takes a time t and the remaining portion cannot be transmitted. It is shown that. This length L1 part
504 is the communication time, that is, the time limit t that has already passed.
It is a portion transmitted from the transmitting station TX during the period and recorded in the recording unit 122 of the receiving station RX. The length L2 is the remaining time
This is the part transmitted from the transmitting station TX during ta and recorded by the recording unit 122 of the receiving station RX. Strictly speaking, the time ta is different from the time when the information corresponding to L2 can be transmitted, and the termination procedure x (second
Figure) time is also included.

In addition, as shown in FIG. 3 (c) or (e), the transmitting station TX
When it takes time t after the normal message has been transmitted and the next message to be transmitted is present, the system control unit 136 receives from the reading unit 116 information that the transmission original remains, The EOP1 signal is generated via the procedure signal control unit 128 and the procedure signal transmission unit 112 and transmitted.

In order for the receiving station RX to fully utilize the function of this EOP1 signal, the receiving station RX is still advantageous if it is this device. In this case, the device may be configured as follows. Ie the receiving station
In RX, the EOP1 signal is identified by the procedure signal detection unit 110,
The system control unit 136 is notified accordingly. System control unit 1
At 36, the switch SW2 of the encoder / decoder 108 is switched to the terminal C side to assemble the above-mentioned auxiliary message. This is expanded as dot pattern data by the character generation circuit 126, and is recorded on the part 502 of the recording paper 500 by the recording unit 122 through the line buffer 120 as in a normal message.

In any case, in this embodiment, when the communication is restored while there is such a remaining document, the system control unit 136 of the transmitting station TX activates the display device 138 to display that effect. In addition, such a display by the display unit 138 is
The system control unit 136 may decode the EOP1 signal and the auxiliary message, and the like, and the receiving station RX may also perform the decoding.

As described above, the transmitting station TX has the time limit function, which allows the receiving station to monitor the communication time and keep track of the communication available time.
We are trying to improve the service so that it will not give the impression of sudden disconnection to the callee by calling RX. Therefore, the reliability of information transmission is improved.

In the illustrated embodiment, the present invention has been described with respect to the standard transmission procedure of the CCITT recommendation G3 facsimile, but the present invention is effectively applied to the facsimile according to other transmission procedures such as the same G2 facsimile and other data transmission. It

Effect According to the present invention, in the data communication method in which the communication time length is restricted, the transmitting station has a time limit function to monitor the communication time, and when the communicable time elapses, it notifies the receiving station to that effect. By doing so, the service is improved so as not to give the recipient the impression of a sudden disconnection. Therefore, the operability of the device and the reliability of information transmission are improved. Therefore, the uncertainty of information transmission and the inconvenience of the user in the conventional method are eliminated, and for example, facsimile information can be reliably and efficiently transmitted. In particular, the wireless communication system is also effective for effective use of radio waves.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of a data communication system according to the present invention, and FIG. 2 is a CCITT recommendation G in the embodiment shown in FIG.
3 Flow chart showing an example of a call connection flow for performing typical facsimile transmission of a document of a plurality of pages according to a facsimile transmission control procedure, and FIG. 3 is a partial flow partially showing another procedure example of the flow of FIG. FIG. 4 and FIG. 4 are explanatory views showing an example of recording facsimile information in the recording unit in the embodiment shown in FIG. Description of main part code 112 …… Procedure signal sending unit 116 …… Reading unit 122 …… Recording unit 126 …… Character generation circuit 128 …… Procedure signal control unit 130 …… Timer circuit 136 …… System control unit 138 …… display

Claims (1)

(57) [Claims] 1. A data communication apparatus for transmitting an image message in page units via a communication system which cannot continue communication for a period longer than a predetermined communicable time, and a message sending means for transmitting the image message and communication. Auxiliary message creating means for creating an auxiliary message for visually outputting to the other party after the image message that the interruption is to be performed, and a time limit for securing at least the time for sending the auxiliary message within the communicable time is set. A timer means for measuring an elapsed time from the start of communication, and when the timer means measures the time limit during transmission of an image message, transmission of the image message is interrupted and an auxiliary message is sent via the message sending means. Is sent, and then a procedure end signal is sent to notify the other party of the termination processing. A data communication device, comprising: a control unit that executes a transmission end procedure.