JPH0252906B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a facsimile communication system, and particularly to a facsimile communication system that can prevent malfunctions due to signal collisions in polling mode.

In polling mode (a mode in which the calling station receives a document), as shown in Figure 1, calling station A calls called station B by dialing (indicated by a chain line), and called station B receives CED. (Called station identification code)
When the calling station A responds with DIS (function identification code),
Since the station sends a DTC (digital transmission command), the polling mode is set when the called station B, which is waiting for polling, responds with a DCS (digital reception command). Next, phase adjustment and training signals are sent from called station B, and when calling station A returns a CFR (reception readiness confirmation), messages (FAX) are continuously sent, and then EOM is sent.
(end of message), EOP (end of procedure) or
Since one of the MPS (multipage signals) is sent, the communication ends when calling station A responds with a message confirmation signal indicating that it has been correctly received.

According to the CCITT recommendation, when sending a command using such a transmission procedure, a response must be made within 3 seconds from the end of receiving the command from the other station.

Furthermore, if there is no response command from the other station, the transmitting station repeats the same command three times and then disconnects the line. On the other hand, the receiving side is allowed to send the command any number of times.

By the way, when feeding originals to the reading section of a facsimile machine, ADF (Auto Document
There are two modes: a manual feeder mode and a manual feed mode. In the manual feed mode, as shown by the solid line in Figure 2, originals are inserted one sheet at a time from the original insertion slot 12, and the originals are driven by the transport rollers. The document is fed to the reading position 13, and after the contents are read there, it is ejected and sent to the document tray 16. Therefore, in the manual feed mode, the insertion slot 12
Since the document is read by the document width sensor 21 located nearby, the document size is determined when the document is set, and since it does not take time to set up the document, a response command can be sent immediately.

On the other hand, in ADF mode, there are various methods, but as shown by the chain line in Fig. 2, there is an automatic document feeder 1 that automatically feeds the document from above.
5, the document is automatically fed to the conveyance path 14, read at the reading position 13, and then discharged. In FIG. 2, the recording section 8 including the roll paper 17, recording head 18, developing roller 19, fixing heater 37, rotary cutter 38, etc. is built in behind the reading section 1. In this way, in the manual feed mode, the document size is detected by the sensor 21 near the insertion slot 12 at the time the original is set, whereas in the ADF mode, the original is inserted into the insertion slot after receiving the command.
Since it is automatically inserted from 2 and fed to the conveyance path 14, it takes time for the size to be detected by the sensor 21 near the insertion port 12, and it takes several seconds for the setup of the transmission data to be completed. .

Referring to FIG. 3, the polling setting operation of the facsimile device will be explained. After the operator at the transmitting station sets the original on the automatic document feeder (ADF),
Switch the line of the network control unit 5 to a telephone (TEL) and leave the room. When the network control section 5 is called by the other station, it sends out a response tone and switches the switch S from the modem 4 to the transmission control section 7. Next, when the transmission control unit 7 sends CED and DIS, a DTC is sent from the other device, so after decoding this content in the system control unit 6, commands are sent to the reading unit 1 and the operation display unit 11. By sending out the document, an automatic document feeding operation is performed, the document width is detected by the sensor 21, and the operation state of the polling button on the operation display section 11 is detected. The system control unit 6 uses the contents of the DTC and the mode such as document width selected by the operator.
DCS data is created, and the DCS and training signals are sent from the transmission control unit 7 via a line.
Note that if the mode (function) according to the DTC contents and the mode (function) such as the document width selected in the reading section 1 do not match, the system control section 6
creates DCS data by shifting down the transmission mode to a mode that is acceptable to the other device's mode.

When a CFR response is received from the other party's device, the switch S is switched to the modem 4, and the message is sent from the reading section 1.

On the other hand, the calling station (receiving station) is the called station (transmitting station).
Dial the polling standby machine using ADF mode, receive CED and DIS, and perform DTC.
The called station enters polling mode by transmitting , and the polling standby machine of the called station enters transmission mode, but it may become impossible to contact each other immediately after this (NO-HAND SHAKE). this is,
This occurs only on machines in ADF mode, and when a polling standby machine in manual feed mode is called, such a transmission failure does not occur and normal operation is possible.

The reason for this is that, as shown in Figure 4, the DTC signal from calling station A and the DCS signal from called station B are a combination of the ADF's automatic feeding time, sending frame length, and frame sending interval. By chance 3
This is because they are sent out at the same timing each time, and each device is unable to capture the frame from the other device, resulting in a mutual transmission failure. That is, in ADF mode, as shown in Figure 4, called station B
Sends CED and DIS strings from calling station A.
After sending the DTC strings from the called station B,
If the ADF original feed time takes a time equal to the transmission interval of calling station A (approximately 3 seconds), the DTC strings from calling station A will be retransmitted and the DCS strings from called station B will be retransmitted. The modem training signal is sent out at the same time and both signals compete, causing transmission failure at both stations.
Proceed to try again. In this case, the transmission frame length of DTC strings and DCS strings is 75mS.
When the interval and the total frame length of the modem training signal are equal, there is a possibility that both calling station A and called station B retransmit at almost the same interval (3 seconds), so the frames will compete again. , the first retry also ends in failure. In this case, as in the previous case, since both frame lengths are the same, there is a possibility that there will be a conflict in the second retry. After this, the called station (transmitting station) B sends a DCN and disconnects the line. Note that the document feed time here is the communication time with the operation display section (operation port) 11 in FIG. 3, and the time when the document is inserted into the insertion slot 12 from the ADF device in FIG. including the time until detection. Further, the transmission interval of the DTC strings from the calling station A is determined by the recommendation of CCITT, and unless a response frame is received from the called station B, the DTC strings are repeatedly transmitted at that interval. When receiving a frame from a partner station, it is predicted that the frame is a frame by first detecting the carrier that precedes the frame.

In Figure 4, if DTC from calling station A
The frame length of the strings and the frame length from called station B.
If the DCS strings, the 75 mS interval, and the total frame length of the modem training signal are not equal, as shown in Figure 5, if both stations take the same interval, the short frame length (DTS Strings) are received by the other station first, so the other station sends out its own frame (DCS strings and modem training signal in FIG. 5) after completing the reception process.
Therefore, if the frame lengths are different, there is almost no possibility of conflict.

In addition, in the manual feed mode, as shown in FIG. 6, when called station B receives the DTC strings from calling station A, the document size has already been detected by sensor 21, so the DCS
Strings and modem training signals can be sent without frame conflicts.

SUMMARY OF THE INVENTION An object of the present invention is to provide a facsimile communication method that can effectively prevent frame conflicts when a polling standby machine is called in ADF mode and transferred to polling mode, in order to solve the conventional problems as described above. It is about providing.

In the facsimile communication method of the present invention, after receiving DTC or DIS, if preparation for sending DCS is completed within a preset time,
If you send a DCS and it does not complete within the time,
It is characterized by sending the DCS immediately after receiving the next DTC or DIS.

First, let's examine the machine's signal sending conditions and other party's signal detection conditions in ADF mode.

In order to set up the DCS data at the called station, it is necessary to detect the document width, and in the ADF mode device shown in FIG.
Setup will not be completed unless the original is fed to the original position. The time taken to set up the DCS data at the called station and the time taken to set up the DCS data at the calling station
Since the DTC transmission retry intervals are approximately equal, there is a possibility that signals from both stations will be transmitted almost simultaneously. Furthermore, if the calling station receives the DCS from the called station before sending the DTC, a dead time of δ seconds will occur, including the flag detection time and carrier detector delay time.

That is, as shown in FIG. 7a, approximately δ from the time when the DTC strings sending interval timer times out (the next DTC sending time).
Even if a DCS is sent from the called station within seconds, it is impossible to detect it. Furthermore, when the called station detects the carrier from the calling station before sending the DCS, it takes about δ seconds to detect the carrier, including the delay time of the carrier detector and the slight delay time caused by the software. , and a dead time of about δ seconds occurs, so even if a carrier is sent from the calling station δ seconds before the DCS is sent, it will be detected as shown in Figure 5b. It is impossible to do so.

Therefore, when calling and polling a called station equipped with a machine in ADF mode,
At the end of the ADF feeding time, if both the calling and called stations send commands, both machines will be dead.
The frame will be sent within time δ, and the frame length and frame sending interval coincidentally match both the second and third times, and the dead frame will be sent again.
It turned out that there was a slump in time and both sides sent frames, resulting in a NO-HAND SHAKE.

Therefore, in the present invention, if the time from when the machine in ADF mode completes feeding the document to setting up the DCS strings is within a certain set value of 3 seconds or less, the DCS strings are immediately sent out. Furthermore, if the time until setup exceeds the set value, it waits for the next DTC strings sent from the other party, and sends out the DCS strings after the DTC strings carrier is disconnected.

FIG. 8 is a time chart of a facsimile communication system showing an embodiment of the present invention.

As shown in Figure 8a, from calling station A to called station B.
After calling, when receiving CED and DIS strings from called station B, calling station A responds by calling
By sending DTC strings, it receives DCS strings and modem training signals from called station B. Here, the DIS and DTC strings each consist of a flag (preamble) followed by a combination of NSF, CSI, and DIS, or a combination of NSC, CIG, and DTC, and a flag (FLG), as shown in Figure 9a. data strings. Also, what is DCS Strings?
As shown in Figure 9b, the flag (preamble)
followed by a combination of TSI and DCS, or TSI
It is a data string consisting of a combination of , NSS, and a flag (FLG). The subsequent modem training signal is the ninth
As shown in Figure c, it consists of a 0.25 second training signal and a continuous “0” phase adjustment signal (1.5 seconds).
The signal has a length of 1.75 seconds.

Each frame that makes up these data strings also has more detailed fields (for example, flags), as shown in Figure 10a, b, and c.
(F), address (AF), control (CF), facsimile control (FCF), facsimile information (FIF), frame check (FCS), etc.).

Now, in FIG. 8a, when the ADF mode machine of called station B receives the first DTC string at time _t0 , a determination timer that determines the set time immediately starts. In Figure 3,
When the information is transferred from the transmission control unit 7 that received the DTC to the system control 6, the system
The control 6 gives commands to the operation display section 11 to read the reading section 1 by operating the operation display section 11.
Operate the ADF and feed the original. At time _t1 after the feeding time T _F has elapsed, the document width is detected by the sensor 21, and the setup of the DCS data is completed. At this time, if the determination timer has timed out, there is a risk of conflict with the retry signal of the other party, so the sending of the DCS strings is waited. Then, after receiving the next DTC strings from calling station A, and after detecting carrier loss,
Send out DCS strings and modem training. Since there are various machine structures in ADF mode, make sure that the carrier from the other party is not detected unless the judgment timer has timed out until the setup of the DCS data is completed. , the DCS strings may be sent out immediately.

Furthermore, as shown in Figure 8b, even if the determination timer has not timed out, the DTC is executed at an interval shorter than the retry interval recommended by calling station A.
In this case, called station B detects the carrier from the other station, receives the DTC strings, detects the loss of the carrier, and then sends the DCS strings and modem strings.
Send a training signal.

FIG. 11 is an operation flow chart of a facsimile communication system showing an embodiment of the present invention.

After called station B sends the DIS strings, the operations shown in FIG. 11 begin. At step 22,
When the DTC strings are received from the other party, the judgment timer is started in step 23, the document is fed through the ADF, the set-up of the DCS data is completed, and the judgment timer is checked in step 25 to see if it has timed out. If the time has elapsed, wait for the next DTC reception. And then the next
After DTC reception is completed and carrier disconnection is detected,
Step 30 sends out DCS strings and training.

On the other hand, if the judgment timer has not timed out in step 25, it is determined in step 27 whether or not a carrier from the other party is detected, and if it is detected, the process returns to step 26 and the DTC string is After detecting the carrier break in step 28, the DCS strings and training are sent out.

If no carrier is detected in step 27, DCS strings and training are immediately sent out in step 29. Then, called station B
prepares to receive the CFR shown in Figure 1.

As explained above, according to the present invention, the ADF
DTC from the other station at a station equipped with a mode machine.
Alternatively, by measuring the time from when DIS strings are received until preparations for sending DCS strings are completed, control is performed so that they are not sent at the same timing, so signals from both sides are not balanced. Can be reliably prevented and NO−
You can eliminate HAND SHAKE. In addition,
In the embodiment, the polling transmission from ADF mode has been described, but the present invention can be applied to all transmitting stations having machines in ADF mode where there is a possibility of signal collision.

[Brief explanation of the drawing]

Figure 1 is a sequence chart showing the transmission procedure in polling mode, Figure 2 is a cross-sectional structural diagram of the facsimile machine, Figure 3 is a block diagram of the facsimile machine, and Figures 4, 5, and 6 are respectively A time chart showing the possibility of signal collision in polling mode, FIG. 7 is an explanatory diagram of dead time when receiving a signal, and FIG. 8 is a time chart of a facsimile communication system showing an embodiment of the present invention.
9 and 10 are exploded views of a facsimile transmission control signal and each frame signal, respectively, and FIG. 11 is an operational flow chart of a facsimile communication system showing an embodiment of the present invention. 1: reading section, 2: buffer, 3: compression decoding section,
4: Modem, 5: Network control section, 6: System control, 7: Transmission control section, 8: Recording section, 9: Scanning section, 10: Mechanism control section, 11: Operation display section, 1
2: Original width sensor, 13: Reading sensor, 14: Conveyance path, 15: ADF, 16: Original tray.

Claims (1)

[Claims] 1. In the facsimile communication system of a transmitting station equipped with a machine in automatic document feeding mode, after receiving a digital transmission command or function identification signal from the other station, preparations for sending a digital reception command are completed within a preset time. If the digital reception command is not completed within the above-mentioned time, the digital reception command is transmitted immediately after the reception of the next digital transmission command or function identification signal is completed. method.