Facsimile and static presentation processing – Facsimile
Reexamination Certificate
2002-03-21
2003-02-18
Grant, II, Jerome (Department: 2624)
Facsimile and static presentation processing
Facsimile
C358S405000, C358S406000, C358S407000
Reexamination Certificate
active
06522429
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a facsimile machine and a facsimile communication system for carrying out facsimile communication via a communication network, such as a packet communication network, which differs from a public telephone network.
BRIEF SUMMARY OF THE INVENTION
A communication procedure between facsimile machines connected to the telephone network is regulated by the ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) Recommendation T. 30. In this communication procedure, after a call is set, image data is transmitted and received between facsimile machines while given control signals are exchanged in order. For confirming whether the communication is normally executed, each of the facsimile machines monitors whether a response signal is received from the counterpart facsimile machine within a given time in response to a certain signal transmitted thereto. If no such a response signal is received within the given time, the foregoing certain signal is retransmitted to the counterpart facsimile machine. Then, if no such a response signal is received even after given number times repetition of the retransmission, the facsimile machine judges that a transmission failure has occurred, and forcibly stops or interrupts the communication with the counterpart facsimile machine.
In recent years, following the rapid spread of the Internet, a communication procedure for realizing facsimile communication via the Internet has been proposed. Facsimile machines are connected to the telephone network, while the telephone network is connected to the packet communication network forming the Internet via gateways.
One of the facsimile machines is connected to one of the gateways via the telephone network, while another facsimile machine is connected to another gateway via the telephone network. The gateways are connected to each other via the packet communication network.
Between the facsimile machine and the gateway connected thereto via the telephone network, communication is carried out pursuant to the communication procedure regulated by the ITU-T Recommendation T. 30. On the other hand, between the gateways connected via the packet communication network, communication is carried out pursuant to a communication procedure regulated by the ITU-T Recommendation T. 38.
The conventional communication technique, however, has the following problem to be solved.
Since the packet communication network deals with a large number of communications at a given frequency band, if the traffic amounts increase, it is possible that large communication delays are generated locally. Thus, it is possible that a significant communication delay occurs between the gateways while facsimile communication is executed. If a communication delay occurs between the gateways, such a communication delay is transferred, as it is, to the telephone network connecting between the facsimile machine and the gateway. According to the communication procedure regulated by the ITU-T Recommendation T. 30, if a communication delay larger than a given value is generated, it is judged that a communication failure has occurred so that facsimile communication is forcibly interrupted.
FIG. 19
is a sequence diagram showing an example wherein facsimile communication is interrupted due to a communication delay caused between gateways.
In this example, when the line connection is established through an exchange of various control signals after a call is made, image data is transmitted from a calling facsimile machine to a calling-side gateway. The image data should then be transmitted from the calling-side gateway to a called-side gateway and further transmitted from the called-side gateway to a called facsimile machine.
Following the transmission of the image data, the calling facsimile machine transmits an EOP (End of Procedures) signal and then goes into a standby state awaiting an MCF (Message Confirmation) signal to be sent from the called facsimile machine in response to the EOP signal.
However, if a large communication delay is caused in the packet communication network connecting between the calling-side gateway and the called-side gateway, the image data transmitted from the calling-side gateway is received, but being largely delayed, at the called-side gateway. Thus, it is possible that the called facsimile machine can not receive the image data within a lapse of a given time from the transmission of the image data by the calling facsimile machine.
If that happens, the MCF signal from the called facsimile machine can not be received at the calling facsimile machine within a lapse of, for example, three seconds from the transmission of the EOP signal as regulated by the communication procedure. In this case, the calling facsimile machine retransmits the EOP signal twice at intervals of three seconds.
If the MCF signal from the called facsimile machine is not received even after two-times retransmission of the EOP signal, the calling facsimile machine judges that a communication failure has occurred, and transmits a DCN (Disconnect) signal for forcibly interrupting the communication.
Since the communication is forcibly interrupted due to an occurrence of the foregoing communication delay, the communication can not be rendered smooth and reliable.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a facsimile machine and a facsimile communication system which can achieve smooth and reliable communication by reducing a possibility of communication errors caused by a communication delay.
It is another object of the present invention to provide a facsimile machine and a facsimile communication system which can reduce a possibility of communication errors caused by a communication delay between gateways.
According to one aspect of the present invention, there is provided a facsimile machine comprising a timing monitor section having a timer for setting a timer value representing a maximum allowable response time for a response signal to be received from a counterpart facsimile machine, the timing monitor section monitoring whether the response signal is received from the counterpart facsimile machine within the timer value; a timer value change information transmitting section which transmits first timer value change information, possessed by the subject facsimile machine, to the counterpart facsimile machine; a timer value change information detecting section which detects second timer value change information transmitted from the counterpart facsimile machine, the second timer value change information selected from the first timer value change information at the counterpart facsimile machine; and a timer value changing section which changes the timer value using the second timer value change information.
According to another aspect of the present invention, there is provided a facsimile machine comprising a timing monitor section having a timer for setting a timer value representing a maximum allowable response time for a response signal to be received from a counterpart facsimile machine, the timing monitor section monitoring whether the response signal is received from the counterpart facsimile machine within the timer value; a timer value change information detecting section which detects timer value change information transmitted from the counterpart facsimile machine, the timer value change information possessed by the counterpart facsimile machine; a timer value change information selecting section which selects, from the timer value change information detected at the timer value change information detecting section, optimum timer value change information to be used in facsimile communication to follow, the optimum timer value change information commonly possessed by the subject facsimile machine; a timer value change information transmitting section which transmits the optimum timer value change information to the counterpart facsimile machine; and a timer value changing section which changes the timer value using the
Akin Gump Strauss Hauer & Feld, L.L.P
Grant II Jerome
Oki Data Corporation
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