JPH1023232A - Facsimile equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize sure and quick facsimile communication by avoiding collision between signals. SOLUTION: When a transmission station receives a DIS signal sent from a reception station in the preparation stage of transmission of image data, the transmission station sends a DCS signal. When the transmission station receives the DIS signal again, it is discriminated that the signal is delayed by the use of a communication satellite, and the DIS signal and the DCS signal are collided with each other and the reception station cannot receive the DCS signal. Then the transmission station decreases the timing, when the DCS signal is sent after receiving the DIS signal to avoid collision of the signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus for transmitting / receiving a control signal to / from a partner station for controlling facsimile communication.

[0002]

2. Description of the Related Art Conventionally, a facsimile apparatus connected to a communication line such as a public telephone line and performing facsimile communication with a facsimile apparatus as a partner station has been used.
In order to establish facsimile communication, for example, as shown in FIG. 4, first, a facsimile apparatus serving as a transmitting station (calling terminal) is connected to a facsimile apparatus serving as a receiving station (called terminal) through a communication line. When called via the transmitting station, the receiving station is connected to the line in response to the calling (ring signal) from the transmitting station. And CNG transmitted from the transmitting station
When the receiving station detects a signal (call signal), the CE automatically
A D signal (called station identification signal) is transmitted to establish a line. Here, the receiving station transmits a group of DIS signals such as an NSF signal (non-standard function signal), a CSI signal (called terminal identification signal), and a DIS signal (digital identification signal). On the other hand, the transmitting station waits for the DIS signal, and upon receiving the DIS signal, after the elapse of a certain standby time t, according to the contents of the DIS signal, the NSS signal (non-standard function signal) and the TSI signal ( A group of DCS signals such as a transmitting terminal identification signal) and a DCS signal (digital command signal) are transmitted, and then a TCF signal (training check signal)
And waits for a CFR signal (reception preparation confirmation signal).
On the other hand, the receiving station waits for the DCS signal,
When the S signal is received, the CFR signal is transmitted, and preparation for transmission of image data such as a document is completed. When the transmitting station receives the CFR signal, the transmitting station transmits image data (image signal), and the receiving station receives the image data and transmits the image data, confirms the image data, and maintains synchronization.
After the communication of the image data, the transmitting station transmits an EOP signal (procedure end signal), and the receiving station transmits an MCF signal (message confirmation signal) in response to the EOP signal. Send a signal (disconnect command signal)
Disconnect the line.

In the above procedure, for example, if the receiving station cannot receive the DCS signal within a predetermined time, the receiving station retransmits the DIS signal at a predetermined interval S1 a predetermined number of times, and When the transmitting station fails to receive the CFR signal within a predetermined time, the transmitting station retransmits the DCS signal a predetermined number of times at a predetermined interval S2 and waits for the DIS signal. Has become.

[0004]

In the above-mentioned conventional configuration,
The standby time t from when the transmitting station receives the DIS signal to when the DCS signal is transmitted is set to a constant value such as 200 ms in consideration of the time required for the other station to prepare for receiving the signal. , And DIS signal and DCS
The intervals S1 and S2 at which the signal is retransmitted are also set to constant values, for example, 3 seconds. On the other hand, for example, in the case of overseas communication and the like, when a communication satellite is used in the middle of a communication line, the arrival of each signal may be delayed. Then, when a delay occurs in the arrival of each signal, for example,
The time when the DCS signal transmitted by the transmitting station reaches the receiving station and the time when the receiving station retransmits the DIS signal overlap,
When the DCS signal and the DIS signal collide, the receiving station
If the signals cannot be received, and the intervals S1 and S2 for retransmitting the DIS signal and the DCS signal are equal to each other, the DCS signal will not be normally received even during the subsequent retransmission, and communication will fail. I have.

[0005] In this respect, for example, as described in JP-B-6-26369, when a response signal to a transmission signal cannot be received, the interval of retransmission of the transmission signal is gradually increased. Is known. However, when a predetermined response signal cannot be received, the signal may collide, or the line may be defective. Therefore, in this configuration, it is necessary to consider a case where the line is defective and to try to communicate by gradually increasing the retransmission interval of the transmission signal, but if the retransmission interval is lengthened, it is difficult to perform quick communication. It has problems such as becoming.

An object of the present invention is to provide a facsimile apparatus capable of transmitting and receiving a control signal reliably and quickly.

[0007]

According to a first aspect of the present invention, there is provided a facsimile apparatus which transmits a second control signal when a first control signal is received and a first standby time elapses. When the first control signal is received again after transmitting the second control signal, the control means includes the first standby time and the first standby time after the first control signal is received again. The second control signal is retransmitted when a different second standby time has elapsed.

In this configuration, when the first control signal is received and the first control signal is received again after the second control signal is transmitted at the time when the first standby time elapses from the reception of the first control signal, Although the communication line is connected, it is conceivable that collision or interference between the control signals has occurred. Therefore, when a second standby time different from the first standby time has elapsed, the second control signal is output. Is transmitted, and transmission / reception of a control signal is attempted, thereby enabling reliable communication.

According to a second aspect of the present invention, in the facsimile apparatus of the first aspect, the second standby time is set shorter than the first standby time.

[0010] In this configuration, quick communication is possible by setting the second standby time shorter than the first standby time.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a facsimile apparatus according to the present invention will be described below with reference to the drawings. In FIG. 2, reference numeral 1 denotes a CPU (central processing unit) constituting a control unit.
The CPU 1 controls the entire facsimile machine. A modem 3 as a line controller is connected to the bus line 2 of the CPU 1, and the modem 3 is connected to a public telephone line 5 as a communication line via a transformer or the like. A telephone (handset) 6 is connected to 3.

The bus line 2 of the CPU 1 has a ROM 11 storing a processing program for controlling the facsimile machine and the like, a RAM 12 storing a changeable setting such as a one-touch dial, a speed dial, and the like. An image memory 14 for storing image data is connected.

Further, an image compression / decompression unit 15 is connected to the bus line 2 so that image data to be transmitted is compressed and encoded, and received image data is restored (decoded).

On the bus line 2, there are provided a keyboard 16 as an operating means provided with a numeric keypad for inputting a telephone number and the like provided on an operation panel, and a liquid crystal panel (LCD) 17 as a display means. It is connected.

Further, connected to the bus line 2 are a scanner 22 as an image reading unit for reading a transmission original or the like as image data, and a printer 23 as an image printing unit for printing image data and various lists. Have been.

In the facsimile apparatus configured as described above, at the time of transmission, image data read from a transmission original by the scanner 22 is compressed and stored in the image memory 14, and a communication line to a communication destination is transmitted to a predetermined communication line to be described later. After establishing the procedure, the image data is read from the image memory 14, encoded, and transmitted to the public telephone line 5 via the modem 3. On the other hand, at the time of reception, a signal received via the modem 3 is stored in the image memory 14 as necessary, decoded into image data, and then printed from the printer 23.

Next, the operation of the facsimile apparatus of the present embodiment when establishing communication with the transmitting station will be described.

First, the operation when communication is normally performed will be described with reference to the sequence diagram of FIG. 4 and the flowchart of FIG.

In this case, when a calling operation such as inputting a telephone number using the keyboard 16 or the like is performed by an operator or the like at the facsimile apparatus of the transmitting station, the transmitting station starts dialing from the standby state, The other station, ie, the receiving station, is called via the telephone line 5. Then, the receiving station is connected to the line in response to the call (ring signal) from the transmitting station. When the receiving station detects a CNG signal (call signal) transmitted from the transmitting station, the receiving station automatically transmits a CED signal (called station identification signal) to establish a line (step 1).

Subsequently, with the line established, the receiving station sends an NSF signal (non-standard function signal), a CSI signal (called terminal identification signal), and a DIS signal (digital identification signal) as a first control signal. Is transmitted. On the other hand, the transmitting station waits for the DIS signal (step 2), and upon receiving this DIS signal, a predetermined first standby time t1 (this embodiment) taking into consideration the time for preparing for reception after transmitting the signal. (For example, 200 ms) (step 3), and after the elapse of the first waiting time t1, according to the contents of the received DIS signal, an NSS signal (non-standard function signal) and a TSI signal (transmission terminal identification signal). , A DCS signal group such as a DCS signal (digital command signal) as a second control signal, a TCF signal (training check signal) is transmitted, and a CFR signal (reception preparation confirmation signal) is waited ( Step 4).

On the other hand, the receiving station waits for the DCS signal and the TCF signal, and upon receiving the DCS signal and the TCF signal, sends out the CFR signal or the FTT signal (training failure signal) to transmit the image data such as a document. Complete the preparation for transmission. When the transmitting station receives the CFR signal (step 5), the transmitting station transmits image data (image signal), and the receiving station receives the image data, transmits the image data, confirms the transmission, and maintains synchronization. Is performed (step 6). After the image data communication, the transmitting station transmits an EOP signal (procedure end signal), and the receiving station transmits an MCF signal (message confirmation signal) in response to the EOP signal. A signal (disconnect command signal) is transmitted, the line is disconnected, and the process ends normally (END).

In step 2, if the transmitting station has not received the DIS signal from the receiving station for a predetermined time (step 7), the transmitting station transmits a DCN signal (disconnection command signal). Then, the line is disconnected (step 8). In this case, such as when the other station is not a facsimile machine, the process ends as a non-response transmission error.

Next, referring to the sequence diagram of FIG. 1 and the flowchart of FIG. 3, in the case where the facsimile communication is an overseas communication or the like, and a communication satellite is used in the middle of a communication line and the arrival of each signal is delayed. Centering on the transmitting station,
The operation after the case where the CFR signal transmitted by the receiving station cannot be received will be described.

First, in step 5, when the transmitting station cannot receive the CFR signal transmitted by the receiving station, the transmitting station transmits not only the CFR signal but also the DIS signal (group).
Is detected for a certain period of time to determine whether or not has been retransmitted from the receiving station (steps 9 and 10). That is, if the receiving station fails to receive the DCS signal within a predetermined time,
This receiving station has a constant interval S (3 seconds in this embodiment).
Should re-transmit the DIS signal and wait for the DCS signal to attempt connection.

Then, if a predetermined time, for example, 3 seconds, elapses without the transmitting station receiving either the CFR signal or the DIS signal from this state (step 10),
Since it is considered that the DCS signal has not reached the receiving station due to a line failure or the like, the transmitting station transmits the DCS signal again, and repeats steps 4, 5, 9, and 10 three times (step 11). And even if the DCS signal is transmitted three times,
If a prescribed signal cannot be received from the receiving station, the transmitting station transmits a DCN signal (disconnection command signal) and disconnects the line (step 12). In this case, the DI from the transmitting station
This is the case where the S signal was detected once, but the DCS signal could not be detected by the receiving station, and the DIS signal could not be detected thereafter, and the process is terminated as the number of retransmissions is exceeded.

On the other hand, in step 9, the retransmission DI
If the S signal can be detected, it is considered that the line is normal and the receiving station retransmits the DIS signal at regular intervals S and waits for the DCS signal to attempt connection. In this case, since the communication satellite is used for the connection with the partner, the signal is delayed, the DCS signal does not reach the partner within the retransmission interval S of the DIS signal, and the DIS signal and the DCS It is possible that the signal interfered with the signal due to collision or the like. Therefore, in this case, the waiting time for transmitting the DCS signal after detecting the DIS signal is shortened, and for example, the second waiting time t2 (this embodiment is shorter than the first waiting time t1 (200 ms) by 120 ms). After the elapse of 80 ms in the embodiment, the DCS signal is transmitted (step 14). Then, this DCS signal arrives at the receiving station at a timing 120 ms earlier than the time of transmission of the first DCS signal, and it is expected that the receiving station can avoid the signal collision and normally receive the DCS signal. You. And the receiving station is DCS
If the signal is received normally, the receiving station transmits the CFR signal, so that the transmitting station receives the CFR signal (step 5), and the image data is transmitted (step 6). In addition, even if the retransmission DIS signal can be detected in step 9, if the DCS signal has already been transmitted three times, the process ends as the number of retransmissions is exceeded (step 13).

As described above, according to the present embodiment, when a DIS signal is transmitted again in response to a DIS signal from a receiving station, the DC signal is transmitted again.
By shortening the timing of transmitting the S signal, even if there is a signal delay due to the use of a communication satellite, DI
The DCS signal can be expected to arrive before the S signal is retransmitted, and signal collision can be avoided, and facsimile communication can be reliably established.

Further, the interval between transmissions of the DCS signal is shortened at the retransmission stage, so that facsimile communication can be quickly established.

Further, the timing of the first transmission of the DCS signal is set so that the reception preparation time of the other station can be secured in communication without using a communication satellite, that is, communication with small delay. In this case, a smooth connection for facsimile communication can be ensured.

In the above embodiment, the relationship between the DIS signal and the DCS signal has been described. However, the present invention can be similarly applied to the transmission timing of other control signals in facsimile communication. In particular, when communication is established by changing the transmission timing of one control signal, the transmission timing of another control signal in the same facsimile communication procedure is similarly changed to ensure reliable quick communication. It can be established. Further, in one facsimile communication, when the communication is established by changing the transmission timing, the communication destination of the facsimile communication is stored in the RAM 12, and the same communication destination is also used for the subsequent separate facsimile communication. First, transmit the control signal at the changed transmission timing,
It is possible to reliably and quickly establish communication.

In the above embodiment, the DIS
When the signal is received, the interval until the transmission of the DCS signal is shortened by one step, but this interval may be gradually shortened in a stepwise manner, or may be sequentially increased in the opposite direction, or Considering the possibility of changing the transmission interval, it is possible to set so as to change the interval at random.

[0032]

According to the facsimile apparatus of the first aspect, after the second control signal is transmitted at the time when the first standby time has elapsed since the first control signal was received, the first control signal is again transmitted. When the control signal is received, the communication line is connected, but it is considered that interference such as collision between the control signals has occurred. Therefore, when the second standby time different from the first standby time elapses, , The second control signal is retransmitted, transmission and reception of the control signal are attempted while avoiding interference between the control signals, and communication can be ensured.

According to the facsimile apparatus of the second aspect, in addition to the effect of the first aspect, the second standby time is set to the first time.
By setting the time shorter than the standby time, communication can be speeded up.

[Brief description of the drawings]

FIG. 1 is a sequence diagram showing an operation of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of the facsimile apparatus according to the first embodiment;

FIG. 3 is a flowchart showing an operation of the facsimile apparatus.

FIG. 4 is a sequence diagram showing a normal operation of the facsimile machine.

[Explanation of symbols]

 1 CPU constituting control means

Claims (2)

[Claims] 1. A control means for transmitting a second control signal when a first standby time has passed when a first control signal is received, wherein the control means transmits the second control signal. After sending,
When the first control signal is received again, the second control signal is transmitted at a point in time when a second standby time different from the first standby time has elapsed since the first control signal was received again. A facsimile machine for retransmitting. 2. The facsimile apparatus according to claim 1, wherein the second standby time is set shorter than the first standby time.