JP5863623B2 - Communication device, communication program, and communication method - Google Patents

Description

  The present invention relates to a T.264 standard of ITU-T recommendation determined in advance with a communication destination terminal connected via a packet network. The present invention relates to a communication apparatus that executes facsimile communication processing according to a communication protocol such as the 38 standard.

In general, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) recommendation T.C. 2. Description of the Related Art An IAF (Internet Aware FAX) that executes facsimile communication processing according to a communication protocol compliant with the 38 standard is known.
In addition, the ITU-T recommendation T.30 using the telephone network. Using G3 FAX for executing facsimile communication processing according to a communication protocol compliant with the T.30 standard, T.30. A gateway for executing facsimile communication processing according to a communication protocol compliant with the 38 standard is known. This gateway converts the modem signal received from the G3 FAX via the telephone network into a packet and transmits it via the Internet, converts the packet received via the Internet into a modem signal and transmits it to the G3 FAX.
By the way, in the facsimile communication process, the IAF performs a timeout process when a response packet is not received after a transmission packet is transmitted to the communication destination terminal until a preset response waiting time elapses. The time-out process is, for example, retransmission of a transmission packet or cancellation of facsimile communication processing.
Here, when the communication destination terminal of the IAF is the IAF, since the packet is transmitted / received via the Internet having a high communication speed, the response waiting time may be short. On the other hand, when the IAF communication destination terminal (final connection destination terminal) is a G3 FAX connected via a gateway, modem signals are transmitted / received via a telephone network with a low communication speed. For this reason, if the response waiting time is short, a response packet cannot be received within the response waiting time, and the facsimile communication processing may not be performed normally.
On the other hand, for example, Patent Document 1 discloses a technique for changing a response waiting time using communication capability information received from a communication destination terminal. Patent Document 2 discloses a technique for setting a response waiting time longer when the communication destination terminal is not IAF than when the communication destination terminal is IAF.

JP-A-11-308428 JP 2002-111952 A

However, the technique according to Patent Document 1 has a problem that the communication capability information including information used for changing the response waiting time needs to be transmitted from the communication destination terminal, and lacks versatility. In the technique according to Patent Document 2, since it is necessary to determine whether or not the communication destination terminal is an IAF every time facsimile communication processing is started, the determination processing becomes a burden and normal facsimile communication processing is performed. There is a problem that the required time becomes longer.
Accordingly, the present invention has been made in view of the above circumstances, and its purpose is to adjust the response waiting time as necessary without judging the type of the destination terminal in normal facsimile communication processing. It is an object of the present invention to provide a communication apparatus, a communication program, and a communication method that can make a facsimile communication process successful.

In order to achieve the above object, the present invention is a communication apparatus comprising a facsimile communication means, a timeout control means, and a response waiting time changing means. The facsimile communication means executes a facsimile communication process with a communication destination terminal connected via a packet network according to a predetermined communication protocol. The time-out control unit executes a predetermined time-out process when a response packet is not received between a transmission packet being transmitted by the facsimile communication unit and a predetermined response waiting time elapses. . The response waiting time changing means sets the response waiting time to be longer than the current time when the response packet is not received between the transmission packet being transmitted by the facsimile communication means and the response waiting time elapses. Change to time.
Moreover, this invention can also be grasped | ascertained as a communication program for making a computer perform a timeout control step and a response waiting time change step. The timeout control step is set in advance after a transmission packet is transmitted by a facsimile communication unit that executes a facsimile communication process according to a predetermined communication protocol with a communication destination terminal connected via a packet network. When a response packet is not received before the response waiting time elapses, a predetermined timeout process is executed. In the response waiting time changing step, when the response packet is not received between the time when the transmission packet is transmitted by the facsimile communication unit and the time when the response waiting time elapses, the response waiting time is set longer than the current state. Change to time.
Furthermore, the present invention can also be understood as a communication method for executing a timeout control step and a response waiting time changing step. The timeout control step is set in advance after a transmission packet is transmitted by a facsimile communication unit that executes a facsimile communication process according to a predetermined communication protocol with a communication destination terminal connected via a packet network. When a response packet is not received before the response waiting time elapses, a predetermined timeout process is executed. In the response waiting time changing step, when the response packet is not received between the time when the transmission packet is transmitted by the facsimile communication unit and the time when the response waiting time elapses, the response waiting time is set longer than the current state. Change to time.

  According to the present invention, the facsimile communication process can be made successful by adjusting the response waiting time as necessary without determining the type of the communication destination terminal in the normal facsimile communication process.

1 is a block diagram showing a schematic configuration of a communication system in which an MFP according to an embodiment of the present invention is used. The sequence diagram for demonstrating an example of a facsimile communication process. The flowchart for demonstrating an example of the process sequence of a response waiting time change process. The sequence diagram for demonstrating an example of the execution result of a response waiting time change process.

  Embodiments of the present invention will be described below with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

[Communication system 1]
First, a schematic configuration of the communication system 1 in which the MFP 10 according to the embodiment of the present invention is used will be described with reference to FIG. The MFP 10 is a multifunction machine having at least a facsimile function for executing facsimile communication processing and other functions such as a copy function, a print function, and a scan function.
As shown in FIG. 1, in the communication system 1, the MFP 10 is connected to communication destination terminals such as the IAF 20 and the GW 30 via the Internet 100 (an example of a packet network). The G3 FAX 40 is connected to the GW 30 via the telephone network 200. That is, the MFP 10 is connected to the G3 FAX 40 via the Internet 100, the GW 30, and the telephone network 200. The Internet 100 is only an example of a packet network, and may be another packet network such as a LAN or an intranet used for real-time communication of digital data.

[IAF20]
The IAF 20 communicates with the communication terminal connected via the Internet 100 according to ITU-T recommendation T.30. This is an internet facsimile machine (Internet Aware FAX) that executes facsimile communication processing according to a communication protocol compliant with the 38 standard. In the facsimile communication process, the IAF 20 is ITU-T recommended T.264. Packets representing control signals used in communication protocols conforming to the 30 standard in digital data are transmitted and received.

[G3FAX40]
Further, the G3 FAX 40 is connected to the communication destination terminal connected via the telephone network 200 with T.F. This is a G3 type facsimile apparatus that executes facsimile communication processing according to a communication protocol compliant with the 30 standard. In the facsimile communication process, the G3 FAX 40 is used for T.F. It transmits and receives modem signals representing control signals used in communication protocols conforming to the 30 standard in analog data.

[GW30]
The GW 30 is a gateway that relays communication processing between the packet network 100 and the telephone network 200. Specifically, the GW 30 converts the modem signal received from the G3 FAX 40 into the packet and transmits the packet from the Internet 100 to a communication destination terminal such as the MFP 10. The GW 30 converts the packet received from the communication destination terminal such as the MFP 10 via the Internet 100 into the modem signal and transmits the modem signal to the G3 FAX 40. As a result, the G3 FAX 40 communicates with the communication destination terminal connected via the telephone network 200 and the Internet 100 with T.C. Facsimile communication processing according to a communication protocol compliant with the 38 standard can be executed.

[MFP10]
The MFP 10 is an image forming apparatus that includes a main control unit 11, an operation display unit 12, an image reading unit 13, an image memory 14, an image forming unit 15, a communication IF 16, a communication control unit 17, and the like. Each of the components provided in the MFP 10 is connected by an internal bus 18. The MFP 10 is only an example of a communication apparatus according to the present invention. For example, the present invention can also be applied to a communication device such as a personal computer having a facsimile function, the IAF 20 and the GW 30.

  The main control unit 11 includes a CPU, a ROM, a RAM, an EEPROM, and the like. The main control unit 11 performs overall control of the MFP 10 by executing processing according to a control program stored in the ROM by the CPU. For example, the main control unit 11 performs a scan function for executing image reading processing for reading image data from a document by the image reading unit 13 and an image forming process for printing input image data by the image forming unit 15. Implement the print function to be executed. The main control unit 11 may be constituted by an electronic circuit such as an integrated circuit (ASIC).

The operation display unit 12 includes a touch panel that displays various types of information according to control instructions from the main control unit 11 and inputs operation signals to the main control unit 11 according to input operations by a user. .
The image reading unit 13 is an image reading unit that reads reflected light when a document is irradiated with light by an imaging element (photoelectric conversion element) such as a CCD. The image data read by the image reading unit 13 is stored in the image memory 14.
The image memory 14 is a nonvolatile memory such as a hard disk or a semiconductor memory. For example, the image data read by the image reading unit 13 is transmitted by a facsimile communication process executed by the communication control unit 17. The image memory 14 also stores image data received by facsimile communication processing executed by the communication control unit 17.
The image forming unit 15 is an electrophotographic image forming unit including a photosensitive drum, a charging device, an exposure device, a developing device, a transfer device, and a fixing device. For example, the image forming unit 15 executes an image forming process for forming an image based on the image data received by the facsimile communication process executed by the communication control unit 17.
The communication IF 16 is a communication interface for connecting the MFP 10 to the Internet 100 and executing data communication via the Internet 100. The communication IF 16 encodes image data transmitted via the Internet 100, for example, and decodes image data received via the Internet 100.

The communication control unit 17 includes a CPU 171, a ROM 172, a RAM 173, an EEPROM 174, and the like. The control unit 17 may be configured by an electronic circuit such as an integrated circuit (ASIC). The RAM 173 is a volatile storage unit, and the EEPROM 174 is a non-volatile storage unit, and is used as a temporary storage memory and an image memory for various processes executed by the CPU 171.
And the said communication control part 17 performs the below-mentioned facsimile communication process (refer FIG. 2) and the response waiting time change process (refer FIG. 3) by executing the communication program memorize | stored in the said ROM 172 by said CPU171. The communication program is recorded on a computer-readable recording medium such as a CD, a DVD, or a semiconductor memory, and is installed from the recording medium into a storage unit such as the EEPROM 174 or a hard disk (not shown). May be. The present invention may be understood as an invention of the communication program for causing the communication control unit 17 to execute the facsimile communication process and the response waiting time changing process or a computer-readable recording medium on which the communication program is recorded. .
Specifically, the communication control unit 17 communicates with a communication destination terminal connected via the Internet 100 according to a predetermined ITU-T recommendation T.30. Facsimile communication processing is executed according to a communication protocol compliant with the 38 standard. That is, the MFP 10 is directly connected to the Internet 100 in the same manner as the IAF 20 and is connected to the T.30. This is a form of IAF that performs facsimile communication processing conforming to the 38 standard. Here, the communication control unit 17 when executing such processing corresponds to a facsimile communication means. Note that a configuration in which the main control unit 11 also functions as the communication control unit 17 and the communication control unit 17 is omitted may be considered as another embodiment.

[Facsimile communication processing]
Here, an example of the facsimile communication process executed by the communication control unit 17 of the MFP 10 will be described with reference to FIG. FIG. 2 shows a communication procedure when facsimile transmission from the MFP 10 to the G3 FAX 40 is performed. Hereinafter, each communication procedure in the facsimile communication process will be referred to as phases F1, F2,.
In the present embodiment, the communication control unit 17 of the MFP 10 performs H.264 recommended by ITU-T. A case where a session establishment procedure is executed according to a session start protocol compliant with the H.323 standard will be described as an example. The communication control unit 17 of the MFP 10 executes a session establishment procedure with the GW 30 according to another session start protocol such as a session start protocol called SIP (Session Initiation Protocol) defined in RFC3261. This is also conceivable as another embodiment.

  As shown in FIG. 2, the MFP 10 receives H.264 as a communication start request. A “SETUP” message based on the H.323 procedure is transmitted to the GW 30 (phase F1). On the other hand, the GW 30 calls the G3 FAX 40 via the telephone network 200 (phase F2). When the G3 FAX 40 responds off-hook in response to the outgoing call (phase F3), the GW 30 sends an H.264 message to the MFP 10. A message “CONNECT” based on the H.323 procedure is transmitted (phase F4). As a result, a session between the MFP 10 and the IAF 20 is established. The following facsimile communication processing is started in accordance with the communication procedure based on the 38 standard.

First, the G3 FAX 40 is a T.F. A modem signal of “CED” based on the 30 standard is transmitted to the GW 30 (phase F5). Accordingly, the GW 30 transmits “CED” converted into a packet to the MFP 10 (phase F6). Subsequently, the G3FAX40 is disclosed in T.F. A modem signal of “DIS” based on the 30 standard is transmitted to the GW 30 (phase F7). Accordingly, the GW 30 transmits “DIS” converted into a packet to the MFP 10 (phase F8).
Next, the MFP 10 receives the T.P. A message “DCS” based on the 30 standard is transmitted to the GW 30 (phase F9). Thereby, the GW 30 transmits “DCS” converted into a modem signal to the G3 FAX 40 (phase F10). Subsequently, the MFP 10 receives the T.P. A message “TCF” based on the 30 standard is transmitted to the GW 30 (phase F11). Then, the GW 30 transmits “TCF” converted into a modem signal to the G3 FAX 40 (phase F12).
On the other hand, the G3 FAX 40 is a T.F. A "CFR" modem signal based on the 30 standard is transmitted to the GW 30 (phase F13). Accordingly, the GW 30 transmits “CFR” converted into a packet to the MFP 10 (phase F14).
When the above communication procedure is completed, the MFP 10 divides the image data into a plurality of packets and transmits them to the GW 30 (phase F15). The GW 30 converts the image data received from the MFP 10 into a modem signal and transmits it to the G3 FAX 40 (phase F16).

Thereafter, when the transmission of the image data is completed, the MFP 10 performs T.P. A message of “EOP” based on the 30 standard is transmitted to the GW 30 (phase F17). Thereby, the GW 30 transmits “EOP” converted into a modem signal to the G3 FAX 40 (phase F18).
Next, the G3 FAX 40 is a T.F. A "MCF" modem signal based on the 30 standard is transmitted to the GW 30 (phase F19). Thereby, the GW 30 transmits “MCF” converted into a packet to the MFP 10 (phase F20).
Then, the MFP 10 receives the T.D. A message “DCN” based on the 30 standard is transmitted to the GW 30 (phase F21). Thereby, the GW 30 transmits “DCN” converted into a modem signal to the G3 FAX 40 (phase F22).
Subsequently, the MFP 10 transmits a “Release Complete” message to the GW 30 (phase F23). As a result, the session between the MFP 10 and the GW 30 is disconnected, and the call between the GW 30 and the G3 FAX 40 is also disconnected (phase F24).

By the way, the communication control unit 17 transmits a transmission packet that requires a response such as “EOP” or the like to “MCF” corresponding to “EOP” after a preset response waiting time T elapses. ”Is not received, a preset timeout process is executed. Here, such processing corresponds to a timeout control step, and the communication control unit 17 when executing such processing corresponds to timeout control means. The timeout process is, for example, retransmission of the transmission packet. Further, when the response packet is not received even if the transmission packet is retransmitted a preset upper limit number of times (for example, twice), the communication control unit 17 executes the suspension of the facsimile communication process as the timeout process. To do.
Here, the response waiting time T is stored in advance in the ROM 172 or the EEPROM 174. Specifically, the initial value of the response waiting time T is T.264. It is 3 seconds defined by 30 standards. However, for example, even when the communication status is bad and the response packet cannot be received within the response waiting time T, the communication between the MFP 10 and the G3 FAX 40 can be performed by extending the response waiting time T. Sometimes it can be done normally.
Therefore, in the MFP 10, the response waiting time T is adjusted by executing a response waiting time changing process (see FIG. 3) described later by the communication control unit 17. Specifically, in the response waiting time changing process, when the response packet is not received during the facsimile communication process until the response waiting time T elapses after the transmission packet is transmitted, the response waiting time is changed. The time T is changed to a longer time than the current time. This processing corresponds to a response waiting time changing step, and the communication control unit 17 when executing such processing corresponds to a response waiting time changing means. Note that the response waiting time changing process may be executed by the main control unit 11. In this case, the main control unit 11 corresponds to a response waiting time control unit.

[Response waiting time change processing]
Hereinafter, an example of a response waiting time changing process executed by the communication control unit 17 of the MFP 10 will be described with reference to the flowchart of FIG. Here, the processing procedure executed by the communication control unit 17 is referred to as steps S1, S2,.

<Step S1>
First, in step S1, the communication control unit 17 determines whether or not a transmission packet set in advance as a transmission packet that requires a response from the communication destination terminal, such as “EOP”, is transmitted in the facsimile communication process. To do. Here, when the communication control unit 17 determines that the transmission packet has been transmitted (Yes side of S1), the process proceeds to step S2. Further, until the transmission packet is transmitted (No side of S1), the communication control unit 17 causes the process to wait in step S1.

<Step S2>
In step S2, the communication control unit 17 starts counting (counting) an elapsed time t1 indicating an elapsed time after transmission of the transmission packet from 0, which is an initial value. The elapsed time t1 is stored in the RAM 173 or the EEPROM 174 of the communication control unit 17, and is reset to an initial value of 0 before starting the time measurement in the step S2. The elapsed time t1 may be counted using a known timing circuit that always counts the current time.

<Step S3>
Next, in step S3, the communication control unit 17 determines whether or not the response packet corresponding to the transmission packet transmitted in step S1 has been received. Specifically, if an “EOP” transmission packet is transmitted in step S1, whether or not the communication control unit 17 receives an “MCF” response packet corresponding to the “EOP” message in step S3. Determine whether. If a “TCF” transmission packet is transmitted in step S1, the communication control unit 17 determines whether or not a “CFR” response packet corresponding to the “TCF” message is received in step S3. to decide.
Here, when the communication control unit 17 determines that the response packet has been transmitted (Yes side of S3), the communication control unit 17 determines that normal communication is being performed with the communication destination terminal, and the process proceeds to step S31. Transition. If the response packet has not been received (No in S3), the communication control unit 17 shifts the process to step S4.

<Step S4>
In step S4, the communication control unit 17 determines whether or not the elapsed time t1 has reached the response waiting time T or more. That is, in step S4, the communication control unit 17 determines whether or not the response packet corresponding to the transmission packet has been received before the response waiting time T has elapsed since the transmission packet was transmitted. It is processing of. Specifically, when the step S4 is first executed, the response waiting time T is set to an initial value of 3 seconds, so that the communication control unit 17 has passed 3 seconds from the transmission of the transmission packet. It is determined whether or not the response packet has been received.
Here, when the communication control unit 17 determines that the elapsed time t1 has reached the response waiting time T or more (Yes side of S4), the communication control unit 17 shifts the processing to the step S5. Further, when the elapsed time t1 is less than the response waiting time T (No side of S4), the communication control unit 17 shifts the process to step S3.

<Step S5>
Subsequently, in step S5, the communication control unit 17 determines whether or not the communication destination terminal of the currently executed facsimile communication process is the GW 30. That is, in the MFP 10, the communication control unit 17 communicates only when the response packet corresponding to the transmission packet is not received before the response waiting time T elapses after the transmission packet is transmitted. It is determined whether or not the terminal is the GW 30. Therefore, in the MFP 10, the processing load in normal facsimile communication processing is small in the response waiting time changing process for appropriately adjusting the response waiting time T.
Here, in the step S5, the communication control unit 17 determines whether the communication destination terminal is the GW 30 or the IAF 20 based on information included in “DIS” received from the communication destination terminal. Can be considered. For example, the GW 30 adds identification information such as its own IP address to the message “DIS”. On the other hand, identification information such as an IP address of each of the GWs 30 connected via the Internet 100 is stored in advance in storage means such as the EEPROM 174. As a result, the main control unit 11 can It is determined whether or not the communication destination terminal is the GW 30 according to identification information such as an IP address described in a DIS message based on the H.323 standard and identification information such as an IP address stored in the EEPROM 174. The determination of whether or not it is the GW 30 in step S12 is not limited to determining whether or not it is the specific GW 30, but is an unspecified gateway that relays communication with the telephone network 200. What is necessary is just to determine whether it is.
A case where the session establishment procedure of the facsimile communication process is executed according to the SIP protocol is also conceivable. In this case, the communication control unit 17 communicates with the communication destination based on information described in accordance with SDP (Session Description Protocol) added to “180 Ringing” or “200 OK” returned after transmission of the “INVITE” message. Whether the terminal is the IAF 20 or the GW 30 can be determined.
And if the said communication control part 17 determines with a communication destination terminal not being the said GW30 (No side of S5), it will transfer a process to step S7. On the other hand, when it is determined that the communication destination terminal is the GW 30 (Yes in S5), that is, when the terminal terminal of the communication partner of the MFP 10 is G3 FAX, the communication control unit 17 shifts the processing to step S6. .

<Step S6>
In step S6, the communication control unit 17 changes the value of the response waiting time T to a time longer than the current time. Specifically, the communication control unit 17 overwrites and saves the value of the response waiting time T stored in the EEPROM 174 for a time longer than the current time. Alternatively, the communication control unit 17 changes the reference address in the EEPROM 174 that reads the value of the response waiting time T to an address in which the response waiting time T longer than the current response waiting time T is stored. . The response waiting time T may be at least longer than the response waiting time T. Specifically, it is conceivable that the pre-response waiting time T after extension is a time obtained by adding 3 seconds to the current response waiting time T.
Thereafter, the response waiting time T is repeatedly extended as the number of times that the response packet is not received between the transmission packet being transmitted and the response waiting time T elapses in the facsimile communication processing. (S6). Further, the response waiting time T may be changed to a time twice, three times, four times,... Of the initial value (3 seconds) of the response waiting time T. Note that it is conceivable that the number of times that the response waiting time T is extended is limited to a preset upper limit number, or that the response waiting time T is extended within a preset maximum extension time range.

FIG. 4 is a diagram illustrating an example of an execution result of the response waiting time changing process when the transmission packet is an “EOP” message. As shown in FIG. 4, when the response packet of the “MCF” message is not received after the initial value of the response waiting time T elapses after the transmission packet of the “EOP” message is transmitted. In step S6, the response waiting time T is extended to 6 seconds. Thereby, in the facsimile communication process executed by the communication control unit 17 thereafter, after the transmission packet of the “EOP” message is transmitted, the response waiting time T after the extension is 6 seconds elapses. , The reception of the response packet of the “MCF” message is awaited. This increases the possibility that the MFP 10 can normally execute the facsimile communication process when executing the facsimile communication process with the G3 FAX 40 as the communication destination terminal.
By the way, since the real-time communication is possible when the communication destination terminal is the IAF 20, there is a low possibility that the facsimile communication process is normally performed even if the response waiting time T is extended. Therefore, in the response waiting time changing process, if it is determined in step S5 that the communication destination terminal is the IAF 20, the process of step S6 is not executed, and it is determined that the communication destination terminal is the GW 30. Only in this case, the process of step S6 is executed. This prevents the response waiting time T from being unnecessarily extended when the communication destination terminal is the IAF 20.
A configuration in which the process of step S5 is omitted is also conceivable as another embodiment. That is, when the communication control unit 17 does not receive the response packet after the transmission packet is transmitted in the step S1 until the response waiting time T elapses (Yes side of S4), In step S6, the response waiting time T may be changed to a time longer than the current time. Such processing is also an example of a response waiting time changing step, and the communication control unit 17 when executing such processing is also an example of response waiting time changing means.

<Step S31>
On the other hand, when it is determined in step S3 that the response packet has been received (Yes side of S3), in subsequent step S31, the communication control unit 17 determines whether or not the response waiting time T is an initial value. to decide. That is, in step S31, the communication control unit 17 determines whether or not the response waiting time T has been extended in step S6.
Here, if the said communication control part 17 judges that the said response waiting time T is an initial value (Yes side of S31), it will transfer a process to the said step S1. When it is determined that the response waiting time T is not the initial value (No side of S31), the communication control unit 17 shifts the process to step S32.

<Step S32>
Next, in step S32, the communication control unit 17 determines whether or not the elapsed time t1 is less than the initial value of the response waiting time T. That is, in step S32, the communication control unit 17 determines whether or not the response packet has been received after the transmission packet is transmitted and after 3 seconds, which is the initial value of the response waiting time T, has elapsed. Judging.
Here, when the communication control unit 17 determines that the elapsed time t1 is less than the initial value of the response waiting time T (Yes side of S32), the communication control unit 17 shifts the process to step S33. If the elapsed time t1 is equal to or greater than the initial value of the response waiting time T (No in S32), the communication control unit 17 shifts the process to step S7.

<Step S33>
In step S33, the communication control unit 17 continuously indicates the number of times that the elapsed time t1 from when the transmission packet is transmitted until the response packet is received is less than the initial value of the response waiting time T. The number of times N1 is counted up (N1 = N1 + 1).
The number of consecutive successes N1 is the time when the elapsed time t1 from when the transmission packet is transmitted until the response packet is received is equal to or greater than the initial value of the response waiting time T, or the response waiting time If the response packet is not received before T elapses, it is reset (S7). That is, the number of consecutive successes N1 is counted up every time the response packet is received during a facsimile communication process executed after the response waiting time T is changed and less than the initial value of the response waiting time T. Is the number of consecutive times. Therefore, the number of consecutive successes N1 is an index for determining the necessity of extending the response waiting time T, and the necessity of extending the response waiting time T is eliminated as the number of consecutive successes N1 increases. It can be judged.

<Step S34>
In step S34, the communication control unit 17 determines whether or not the number of consecutive successes N1 has reached or exceeded a preset threshold value N2. The threshold value N2 is a numerical value determined in advance for determining the timing for resetting the response waiting time T to an initial value, and is a numerical value such as 10 times, 50 times, or 100 times, for example.
Here, when it is determined that the number of consecutive successes N1 is less than the threshold value N2 (No side in S34), the communication control unit 17 shifts the processing to step S1. On the other hand, when the communication control unit 17 determines that the number of consecutive successes N1 is equal to or greater than the threshold value N2 (Yes in S34), the communication control unit 17 shifts the process to step S35.
Therefore, the communication control unit 17 changes the response waiting time T and continues until the changed response waiting time T elapses until the continuous success count N1 reaches the threshold N2 or more. If no response packet is received, the time-out process is executed. Thus, for example, when the user performs a large number of times of performing the facsimile communication process using the MFP 10 with the G3 FAX 40 as a communication destination terminal, the facsimile communication process can be successfully performed without accompanying the timeout process every time.

<Step S35>
In step S35, the communication control unit 17 resets the response waiting time T to return to an initial value. That is, the communication control unit 17 changes the response waiting time T, and after the transmission packet is transmitted in the facsimile communication processing, the time until the response packet is received is the initial value of the response waiting time T. The response waiting time T is returned to the initial value on condition that the continuous success count N1 that is less than the value has reached the threshold value N2 or more.
Thereby, after that, the communication control unit 17 executes the timeout process when the response packet is not received even after 3 seconds as the initial value of the response waiting time T has elapsed since the transmission packet was transmitted. Will do.

<Step S7>
As described above, when the response packet is not received during the response waiting time T (Yes side of S4), the elapsed time t1 when the response packet is received is equal to or greater than the initial value of the response waiting time T. (No side of S32), the communication control unit 17 shifts the process to step 7.
In step S7, the communication control unit 17 resets the continuous success count N1 to zero. Thereby, the communication control unit 17 restarts the count of the continuous success number N1 from 0, and the response packet has the response waiting time T1 until the continuous success number N1 reaches the threshold value N2 or more. The time-out process is executed when no message is received even after the elapse of time.

As described above, in the MFP 10, in the normal facsimile communication process in which the response packet is received after the transmission packet is transmitted and until the response waiting time T elapses, the communication destination terminal is the GW 30. It is not determined whether or not there is. The response waiting time T is extended only when the response packet is not received before the response waiting time T elapses. Therefore, according to the MFP 10, the facsimile communication process can be made successful by adjusting the response waiting time T as necessary without determining the type of the communication destination terminal in the normal facsimile communication process.
Further, when the communication destination terminal is the IAF 20, the facsimile communication process is performed at high speed via the Internet 100. Therefore, if the response packet is not received from the IAF 20 even after the response waiting time T has elapsed, even if the response waiting time T is extended, the waiting time is only extended unnecessarily. In this regard, the MFP 10 is a case where the response packet is not received between the transmission packet being transmitted and the response waiting time T elapses, and the communication destination terminal is the GW 30 The response waiting time T is extended only to In other words, the MFP 10 prevents unnecessary extension of the response waiting time T when the communication destination terminal is the IAF 20.

In the present embodiment, as an example of the condition for resetting the response waiting time T, the case where the number of consecutive successes N1 reaches the threshold N2 or more has been described as an example, but the present invention is not limited thereto.
For example, after the communication control unit 17 changes the response waiting time T, the response waiting time T is initialized on the condition that the facsimile communication processing that has been executed when the change is performed is completed. It is also possible to restore the value.
Further, the communication control unit 17 accumulates the number of times that the elapsed time t1 from when the transmission packet is transmitted to when the response packet is received is less than the initial value of the response waiting time T. The response waiting time T may be reset on condition that the value has reached a predetermined value or more. Further, the communication control unit 17 accumulates the number of times that the elapsed time t1 from when the transmission packet is transmitted until the response packet is received is less than the currently set response waiting time T, The response waiting time T may be reset on condition that the accumulated value has reached a predetermined value or more.
In addition, it is also conceivable as another embodiment that the threshold value N2 can be set to 0 by the main control unit 11 in the initial setting of the MFP 10 or the like. As a result, after changing the response waiting time T, the communication control unit 17 returns the response waiting time T to the initial value on condition that the response packet is normally received first. Further, the communication control unit 17 omits the processing steps of steps S31 to S34 and step S7, and resets the response waiting time T to an initial value on condition that the response packet is received in step S3. It is also conceivable as another embodiment.

1: Communication system 10: MFP (an example of a communication device)
11: Main control unit 12: Operation display unit 13: Image reading unit 14: Image memory 15: Image forming unit 16: Communication IF
17: Communication control unit 171: CPU
172: ROM
173: RAM
174: EEPROM
18: Internal bus 20: IAF
30: GW
40: G3 FAX
100: Internet (an example of a packet network)
200: Telephone networks F1, F2, ...: Communication procedure (phase) numbers S1, S2, ...: Processing procedure (step) numbers

Claims (7)

Facsimile communication means for executing facsimile communication processing according to a predetermined communication protocol with a communication destination terminal connected via a packet network;
Timeout control means for executing a predetermined time-out process when a response packet is not received after a transmission packet is transmitted by the facsimile communication means until a preset response waiting time elapses;
A response waiting time change for changing the response waiting time to a longer time than the current time when the response packet is not received after the transmission packet is transmitted by the facsimile communication means until the response waiting time elapses Means,
Equipped with a,
The response waiting time changing unit determines whether or not the communication destination terminal is a gateway that relays communication processing between the packet network and the telephone network, and the communication destination terminal is determined to be the gateway A communication apparatus that changes the response waiting time to a time longer than the current state only in the case .   The communication protocol is ITU-T recommendation T.264. The communication apparatus according to claim 1, wherein the communication protocol is based on a 38 standard. After the response waiting time changing means changes the response waiting time, a time from when the transmission packet is transmitted until the response packet is received in the facsimile communication processing executed by the facsimile communication means is the response time. 3. The communication device according to claim 1, wherein the response waiting time is returned to the initial value on condition that the number of times that was less than the initial value of the waiting time has reached a preset number of times or more. The response waiting time changing means resets the response waiting time to an initial value on condition that the facsimile communication process executed when the change is made after changing the response waiting time. The communication device according to claim 1 or 2 . The response waiting time changing means decreases the response waiting time as the number of times that the response packet has not been received after the transmission packet is transmitted by the facsimile communication means until the response waiting time elapses increases. communication device according to any one of claims 1-4 is intended to be repeatedly extended. A preset response waiting time elapses after a transmission packet is transmitted by a facsimile communication means that executes facsimile communication processing in accordance with a predetermined communication protocol with a communication destination terminal connected via a packet network. A time-out control step for executing a predetermined time-out process when a response packet is not received until
A response waiting time change for changing the response waiting time to a longer time than the current time when the response packet is not received after the transmission packet is transmitted by the facsimile communication means until the response waiting time elapses Steps,
A communication program for executing on a computer,
In the response waiting time changing step, it is determined whether or not the communication destination terminal is a gateway that relays communication processing between the packet network and the telephone network, and it is determined that the communication destination terminal is the gateway. The communication program in which the response waiting time is changed to a time longer than the current state only when A preset response waiting time elapses after a transmission packet is transmitted by a facsimile communication means that executes facsimile communication processing in accordance with a predetermined communication protocol with a communication destination terminal connected via a packet network. A time-out control step for executing a predetermined time-out process when a response packet is not received until
A response waiting time change for changing the response waiting time to a longer time than the current time when the response packet is not received after the transmission packet is transmitted by the facsimile communication means until the response waiting time elapses Steps,
A communication method for execution,
In the response waiting time changing step, it is determined whether or not the communication destination terminal is a gateway that relays communication processing between the packet network and the telephone network, and it is determined that the communication destination terminal is the gateway. The communication method in which the response waiting time is changed to a time longer than the current state only when

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