JP2010141734A - Image transmitting device and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image transmitting device and communication system, which reliably transmit an image from a transmission side to a receiving one by retransmission thereof even if echo interference occurs when receiving the image through a communication line. <P>SOLUTION: A facsimile communication device of the transmission side transmits image data after a dummy signal is transmitted and a partial page signal (PPS) as a confirmation signal after the image data are transmitted. The facsimile communication device of the receiving side responds to whether or not receiving of the image data is carried out by a message confirmation signal (MCF) or a partial page request (PPR). When the partial page request (PPR) is provided, the facsimile communication device of the transmission side retransmits the image data. At this moment, the facsimile communication device of the transmission side avoids the echo interference by allowing a time length (T1) of the dummy signal prior to retransmission of the image data subsequent to the second transmission to be longer than the time length (T0) of the dummy signal prior to the transmission of the initial image data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image transmission apparatus and a communication system that can prevent a communication error from occurring due to an echo failure.

  2. Description of the Related Art Conventionally, facsimile communication apparatuses are widely used as image transmission apparatuses and image reception apparatuses that transmit and receive image data using a communication line such as a telephone line. In facsimile communication, a part of a communication signal may not be normally received by a receiving device due to the influence of external noise or the like. When a part of the communication signal cannot be received, the printed image is defective based on the received signal. For this reason, recent facsimile communication apparatuses have a function of correcting a communication defect in order to prevent the image from being lost.

  If a communication failure occurs such that it is difficult to receive a signal due to noise on the communication line due to noise on the communication side of the receiving side, and if a part or all of the image cannot be received, a retransmission request signal is sent to the transmitting side facsimile communication device. A partial page request PPR (Partial Page Request) is transmitted. The transmission-side facsimile communication apparatus to which the retransmission request signal is given retransmits the image that the reception-side facsimile communication apparatus could not receive. As a result, the facsimile communication apparatus on the receiving side can receive the image again.

Patent Document 1 proposes a modem device that can prevent misperception due to a delay failure of a tone signal and can reliably establish subsequent communication control. This modulation / demodulation device is a V.D. The tone signal transmitted following the line probing signal in phase 2 of half-duplex communication based on the 34 standard is received, and information obtained by analyzing the line state is created based on the line probing signal. In addition, the modulation / demodulation device frequency-analyzes the line probing signal, and when the analysis value of the frequency 1200 Hz corresponding to the tone signal is larger than the analysis value of the surrounding frequency 1050 Hz or 1350 Hz, the symbol rate 2400 is selected and created Information is transmitted reflecting the selected symbol rate.
JP 2003-283590 A

  The facsimile communication apparatus retransmits an image by transmitting / receiving a retransmission request signal, thereby preventing a communication failure due to external noise or the like. However, one of the communication failures that occur in facsimile communication is an echo failure. The echo failure is a failure in which a signal transmitted from the transmission side leaks to a line to transmit a signal from the reception side to the transmission side and returns to the transmission side when the telephone line has impedance mismatch. In the echo failure, the signal returns with a certain delay according to the line, so that even if the facsimile communication apparatus retransmits the image using the retransmission request signal, a defect occurs in the same portion of the image. For this reason, even when image retransmission is repeatedly performed between facsimile communication apparatuses using a retransmission request signal, there is a problem that if an echo failure occurs, image transmission / reception cannot be performed normally, resulting in a communication error.

  The modulation / demodulation device described in Patent Document 1 is a technique for reliably establishing communication control when communication delay or echo failure occurs, and the above-described case where echo failure occurs in image transmission. It cannot solve the problem.

  The present invention has been made in view of such circumstances, and the object of the present invention is to retransmit an image from the transmission side to the reception side even when an echo failure occurs. An object of the present invention is to provide an image transmission apparatus and a communication system capable of reliably performing transmission.

  An image transmitting apparatus according to the present invention is an image transmitting apparatus that transmits an image to another apparatus via a communication line, and transmits an image having a predetermined time length to the other apparatus before transmitting the image. Signal transmitting means before transmission, confirmation signal transmitting means for transmitting a confirmation signal for confirming reception of the image to the other apparatus after transmission of the image, and the other apparatus for the confirmation signal transmitted by the confirmation signal transmitting means A response signal receiving means for receiving a response signal from the receiver, and a retransmitting means for retransmitting an image according to the response content of the response signal received by the response signal receiving means. Is characterized in that a signal having a time length different from the predetermined time length is transmitted to the other device before the retransmission means retransmits the image.

  In the image transmission apparatus according to the present invention, the signal transmission unit before image transmission transmits a signal having a time length longer than the predetermined time length to the other apparatus before the retransmission unit retransmits the image. It is characterized by being transmitted.

  Further, in the image transmission apparatus according to the present invention, each time the response signal is received by the response signal reception unit, the retransmission unit performs image retransmission according to the response content of the response signal. The signal transmission means is characterized in that the time length of the signal transmitted before the image transmission is lengthened in accordance with the number of retransmissions of the retransmission means.

  The image transmission apparatus according to the present invention is configured so that the signal transmission means before image transmission receives the signal related to a retransmission request from the other apparatus as the response signal when the response signal reception means receives the predetermined time length. It is characterized in that a signal having a different time length is transmitted.

  The communication system according to the present invention is a communication system including an image transmission device and an image reception device that transmit and receive an image via a communication line, and the image transmission device has a predetermined time length before transmitting an image. A signal transmission means before transmitting the image to the image receiving apparatus, a confirmation signal transmitting means for confirming reception of the image after transmitting the image to the image receiving apparatus, and the transmission of the confirmation signal. A response signal receiving means for receiving a response signal from the image receiving apparatus for the confirmation signal transmitted by the means, and a retransmission means for retransmitting the image in accordance with the response content of the response signal received by the response signal receiving means. The signal transmission means before image transmission transmits a signal having a time length different from the predetermined time length to the image receiving apparatus before the retransmission means retransmits the image. The image receiving apparatus receives a response signal related to whether or not the receiving means can receive an image in accordance with a receiving means for receiving an image from the image transmitting apparatus and a confirmation signal from the image transmitting apparatus. Response signal transmitting means for transmitting.

  In the communication system according to the present invention, the image receiving device includes a detecting unit that detects an image area that the receiving unit could not receive from images transmitted by the image transmitting device, and the response signal transmission Means for adding information relating to the image area detected by the detection means to the response signal and transmitting the information to the image transmission apparatus, wherein the image transmission apparatus includes the signal transmission means before image transmission, The time length of the signal to be transmitted is determined according to the information related to the image area included in the response signal received by the response signal receiving means.

In the present invention, an image transmission apparatus (a facsimile communication apparatus on the transmission side) that transmits an image transmits a signal (dummy signal) having a predetermined time length before image transmission to synchronize image transmission / reception. To the receiving facsimile communication apparatus). After transmitting a unit amount of image such as a page, the transmitting facsimile communication apparatus transmits, for example, a partial page signal PPS (Partial Page Signal) to the receiving facsimile communication apparatus as a confirmation signal for confirming reception of the image. To do.
The receiving facsimile communication apparatus may receive an image after receiving the dummy signal, and correctly receive the image as a response signal to the partial page signal PPS (confirmation signal) given from the transmitting facsimile communication apparatus. If it is possible, for example, a message confirmation signal MCF (Message ConFirmation signal) is transmitted, and if the image cannot be correctly received due to disturbance noise or echo failure, for example, a partial page request PPR is transmitted.
Upon receiving the response signal from the receiving facsimile communication apparatus, the transmitting facsimile communication apparatus determines the response content of the response signal (whether it is the message confirmation signal MCF or the partial page request PPR), and the partial page request PPR. The non-received image notified at is retransmitted to the facsimile communication apparatus on the receiving side. The transmitting side facsimile communication apparatus transmits a dummy signal before retransmitting an image, and the time length of the dummy signal before retransmitting is set to a time length different from that of the dummy signal before the first image transmission.
Since the echo failure is a failure caused by the signal returning with a certain delay, the echo failure occurs at a different timing from the first time during the image retransmission by changing the time length of the dummy signal before the image transmission. . Therefore, the facsimile communication apparatus on the receiving side can receive the image that could not be received for the first time by re-transmission. Images can be received.

  In the present invention, the time length of the dummy signal before the image retransmission is set longer than the time length of the dummy signal before the first image transmission. As a result, since the time length of the dummy signal can be changed before the first image transmission and before the image retransmission, a complete image can be finally received even when an echo failure occurs. it can. In addition, since the time length of the dummy signal before the first image transmission can be shortened, communication between facsimile communication apparatuses can be performed at high speed when there is no communication failure such as disturbance noise or echo failure. The increase in communication time can be suppressed, and the increase in communication cost can be suppressed.

  In the present invention, the time length of the dummy signal before image retransmission is gradually increased according to the number of retransmissions. As a result, not only the time length of the dummy signal is changed between before the first image transmission and before the image retransmission, but also when the retransmission is repeated, the time length of the dummy signal at each retransmission is changed. Can be changed. Thereby, even when an echo failure occurs, it is possible to transmit and receive an image more reliably.

  Further, in the present invention, when a facsimile communication apparatus on the transmission side receives a signal (partial page request PPR) relating to an image retransmission request from the facsimile communication apparatus on the reception side, it transmits a dummy signal whose time length has been changed. To do. Thus, each time the partial page request PPR is received, the transmission side facsimile communication apparatus can retransmit the image by transmitting a dummy signal whose time length has been changed.

In addition, when the transmitted / received image is partially affected by an echo failure, the image received by the receiving facsimile communication apparatus is lost at the same location even if the transmitting facsimile communication apparatus repeats retransmission of the image. Occurs. That is, if the missing part of the image received by the receiving facsimile communication apparatus for the first time (the image area that could not be received) overlaps with the missing part of the image received for the second time or later, an echo failure has occurred. It can be determined that there is a high probability that it has occurred.
Therefore, in the present invention, the facsimile communication apparatus on the receiving side adds information relating to the missing portion of the received image to the partial page request PPR and transmits it to the facsimile communication apparatus on the transmitting side. The facsimile communication apparatus on the transmission side that has received this determines the time length of the dummy signal according to the information relating to the missing part. For example, the facsimile communication apparatus on the transmission side stores a history of missing portions of the received image, and when the missing portions overlap, the time length of the dummy signal is changed and lengthened.
Thereby, when the loss of the received image is not caused by the echo failure, it is possible to suppress an increase in the time required to retransmit the image from the transmission side to the reception side.

  According to the present invention, after the image transmission apparatus (transmission side facsimile communication apparatus) transmits a dummy signal or the like in response to a response signal (partial page request PPR) from the image reception apparatus (reception side facsimile communication apparatus). It is configured to perform image re-transmission, and the time length of the dummy signal before re-transmission is set to a time length different from that of the dummy signal before the first image transmission, so that the first image transmission and re-transmission have different timings. Since an image is transmitted from the transmission side to the reception side, even when an echo failure occurs, the timing of occurrence of the echo failure can be different between the first image transmission and the retransmission. Therefore, even if re-transmission is performed, there is no problem that an echo failure occurs at the same location of the image. Therefore, even if an echo failure occurs, the image can be transmitted reliably, and the printed image is not lost.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. In this embodiment, a facsimile communication system using a facsimile communication apparatus as an image transmitting apparatus and an image receiving apparatus will be described as an example. FIG. 1 is a block diagram showing a configuration of a communication system according to the present invention. In the figure, reference numerals 1 to 3 denote facsimile communication apparatuses (image transmitting apparatus / image receiving apparatus), and the plurality of facsimile communication apparatuses 1 to 3 are communicably connected via a communication line 50 such as an analog public telephone line network. Has been. Although only three facsimile communication apparatuses 1 to 3 are illustrated in FIG. 1, many more facsimile communication apparatuses are actually connected via the communication line 50.

  The facsimile communication apparatus 1 includes a control unit 10, a document reading unit 11, a printing unit 12, an operation unit 13, a display unit 14, a storage unit 15, a coding / decoding unit 16, a clock unit 17, a communication unit 20, and the like. ing. These units are connected via a bus 18 and perform processing by exchanging data with each other. Since the other configurations of the facsimile communication apparatuses 2 and 3 are substantially the same as the configuration of the facsimile communication apparatus 1, illustration and detailed description thereof are omitted.

  Specifically, the control unit 10 is configured by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like, and performs control processing of various units in the facsimile communication apparatus 1 and various arithmetic processes. The control unit 10 can perform control processing, arithmetic processing, and the like by reading and executing a program stored in advance in a ROM (Read Only Memory) or the like.

  The document reading unit 11 has an optical sensor such as a CCD (Charge Coupled Device), reads a document image with a predetermined resolution by the optical sensor according to the control of the control unit 10, and acquires image data for transmission. To do. The document reading unit 11 stores the image data read and acquired in the storage unit 15 and notifies the control unit 10 of the completion of reading.

  The printing unit 12 includes, for example, a light source such as a semiconductor laser or an LED (Light Emitting Diode), a photosensitive drum for attaching toner, and a fixing device for transferring and fixing the toner to printing paper with heat and pressure. The image received from the other facsimile communication devices 2 and 3 is printed on a medium such as printing paper by facsimile communication via the communication line 50. Image data received by facsimile communication is stored in the storage unit 15, and the printing unit 12 reads the image data from the storage unit 15 and prints the image.

  The operation unit 13 includes various switches that accept user operations such as a start switch, a numeric keypad, and various function switches. A user who uses the facsimile communication apparatus 1 can perform various operations such as inputting a transmission destination, setting a resolution for reading a document, and checking a communication result by operating a switch of the operation unit 13. When the operation unit 13 receives a switch operation by the user, the operation unit 13 notifies the control unit 10 of the operation content and the like, whereby the control unit 10 performs processing according to the user operation.

  The display unit 14 is configured by a liquid crystal display unit or the like, and displays characters, images, and the like according to the control of the control unit 10. The display unit 14 displays, for example, setting items and menus for operating the facsimile communication apparatus 1, operation states of the facsimile communication apparatus 1, various warning messages, and the like. The operation unit 13 and the display unit 14 may be integrally provided as a touch panel.

  The storage unit 15 is composed of a large-capacity rewritable memory element such as a DRAM (Dynamic Random Access Memory) or a flash memory, and data such as an image read by the document reading unit 11 or an image received by facsimile communication. Is temporarily stored. Further, when the storage unit 15 is configured by a nonvolatile memory element such as a flash memory, or the storage unit 15 further includes a nonvolatile memory such as a mask ROM (Read Only Memory) or an EEPROM (Electrically Erasable Programmable ROM). In such a case, the storage unit 15 stores in advance various programs executed by the control unit 10 and data such as tables.

  The encoding / decoding unit 16 performs encoding in a predetermined format on the image data read and acquired by the document reading unit 11, thereby reducing the data amount of image data transmitted by facsimile communication and the facsimile. A process of decoding the image data encoded from the other facsimile communication apparatuses 2 and 3 by communication and returning to the original format is performed. The encoding / decoding unit 16 encodes the image data for transmission read by the document reading unit 11 according to the control of the control unit 10, stores the encoded image data in the storage unit 15, and receives and stores it in the storage unit 15. The image data is decoded and given to the printing unit 12.

  The time measuring unit 17 measures time and notifies the control unit 10. The timer unit 17 is controlled by the control unit 10 to start and stop timing, reset the time measured, and the like.

  The communication unit 20 transmits / receives data to / from other facsimile communication apparatuses 2 and 3 via the communication line 50, and includes an NCU (Network Control Unit) 21 and a modem 22. The NCU 21 controls the closing and opening of the communication line 50 such as an analog public telephone line network, and connects the modem 22 to the communication line 50 according to the control of the control unit 10. The NCU 21 performs transmission / reception of image data, control signals, and the like according to a predetermined facsimile communication protocol, and also performs automatic call processing and automatic call reception processing of facsimile communication.

  The modem 22 modulates the image data for transmission into an analog signal suitable for transmission on the communication line 50 and demodulates the analog signals from the other facsimile communication apparatuses 2 and 3 based on the facsimile communication standard. To obtain image data.

  As a result, the facsimile communication apparatus 1 reads the document with the document reading unit 11 to acquire image data for transmission, and encodes the image data with the encoding / decoding unit 16 to reduce the data amount, thereby enabling communication. The image data can be converted into an analog signal by the unit 20 and transmitted to the other facsimile communication apparatuses 2 and 3 via the communication line 50. When receiving signals from the other facsimile communication apparatuses 2 and 3 via the communication line 50, the facsimile communication apparatus 1 obtains image data by decoding the received signal at the communication unit 20, and acquires the image data. Can be decoded by the encoding / decoding unit 16 and an image can be printed on the printing paper by the printing unit 12.

  FIG. 2 is a schematic diagram for explaining a procedure of facsimile communication performed by the facsimile communication apparatus 1. The facsimile communication apparatus 1 on the image transmission side (calling side) and the facsimile communication apparatus on the reception side (called side). 2 shows the transmission or reception of signals or data. When transmitting an image by facsimile communication, first, the transmission-side facsimile communication device 1 transmits a calling tone CNG (CalliNG tone) to the destination facsimile communication device 2 input by the user through the operation unit 13.

  When receiving the calling tone CNG from the transmitting facsimile machine 1, the receiving facsimile communication apparatus 2 first transmits a called station identification signal (CED) to the transmitting facsimile communication apparatus 1. . Next, the facsimile communication apparatus 2 on the receiving side receives a non-standard function signal NSF (Non-Standard Facilities signal) including information such as the manufacturer of the own apparatus and a called apparatus identification signal including information such as the telephone number of the own apparatus. By transmitting a CSI (Called Subscriber Identification signal) and a digital identification signal DIS (DIgital transmit command signal) including information related to the performance of the device such as a transmission rate and a maximum reception width, the transmission side facsimile communication device 1 is transmitted. Notify the function and performance of its own device. However, the non-standard function signal NSF and the called device identification signal CSI may not be transmitted.

  When receiving a signal such as the non-standard function signal NSF, the called device identification signal CSI, and the digital identification signal DIS from the reception side facsimile communication device 2, the transmission side facsimile communication device 1 receives information such as its own telephone number. Transmitting device identification signal TSI (Transmitting Subscriber Identification signal), non-standard procedure signal NSS (Non-Standard facilities Set-up) including information such as the manufacturer of the device, and the transmission rate and maximum receiving width, etc. By transmitting a digital command signal (DCS) including information related to the performance of the device, the function and performance of the device itself are notified to the facsimile communication device 2 on the receiving side. However, the transmitter identification signal TSI and the nonstandard procedure signal NSS may not be transmitted.

  Next, the facsimile communication apparatus 1 on the transmission side transmits a training check signal TCF (Training Check signal) to the facsimile communication apparatus 2 on the reception side. The facsimile communication apparatus 2 on the reception side that has received the training check signal TCF transmits a reception preparation confirmation signal CFR (Confirmation to Receive signal) to the facsimile communication apparatus 1 on the transmission side. Thereby, preparations for transmission / reception of image data between the facsimile communication apparatus 1 on the transmission side and the facsimile communication apparatus 2 on the reception side are completed.

  After receiving the reception preparation confirmation signal CFR, the transmission-side facsimile communication apparatus 1 transmits the image data PIX one page at a time, and every time image data of a predetermined data amount (specified unit amount) is transmitted. A page signal PPS (Partial Page Signal) is transmitted to the facsimile communication apparatus 2 on the receiving side. The partial page signal PPS is a confirmation signal for the facsimile communication apparatus 1 on the transmission side to confirm whether or not the image data has been correctly received.

  The partial page signal PPS includes PPS-EOM (PPS-End Of Message), PPS-EOP (PPS-End Of Procedure), PPS-MPS (PPS-MultiPage Signal), and PPS-NULL. When the remaining amount of image data to be transmitted by the transmission side facsimile communication apparatus 1 exceeds the specified unit amount, PPS-EOM, PPS-MPS, PPS-NULL, or the like is used. On the other hand, PPS-EOP is used when the remaining amount of image data is within a specified unit amount, that is, when it is the last data of image data to be transmitted.

  The facsimile communication apparatus 2 on the receiving side that has received the partial page signal PPS checks whether or not the received prescribed unit amount of image data is defective (that is, whether or not the prescribed unit amount of image data has been correctly received). Find out). If the received image data is defective, the facsimile communication apparatus 2 on the receiving side sends a partial page request PPR (Partial Page Request) for notifying this fact and requesting retransmission of the image data to a partial page signal PPS. As a response signal to the facsimile communication apparatus 1 on the transmission side.

  As a result, it is possible to notify the transmission-side facsimile communication apparatus 1 of information relating to the portion where the image data is missing, and the transmission-side facsimile communication device 1 that has received the partial page request PPR includes the portion where the loss occurred. Re-send image data of specified unit amount. The receiving side facsimile communication apparatus 2 that has received the retransmitted image data fills in the missing portion with the received image data, and when all of the prescribed unit amount of image data is complete, the message confirmation signal MCF (Message ConFirmation signal ) To the facsimile communication apparatus 1 on the transmission side. In addition, if all of the prescribed amount of image data is not completed even if the missing portion is filled with the retransmitted image data, the receiving side facsimile communication apparatus 2 transmits a partial page request PPR to the transmitting side facsimile communication apparatus 1. .

  Retransmission is repeated until all of the image data is available, and the transmission side facsimile communication apparatus 1 that has received the message confirmation signal MCF from the reception side facsimile communication apparatus 2 transmits the next specified unit amount of image data. When transmission of image data for all pages is completed, the facsimile communication apparatus 1 on the transmission side transmits a procedure end signal PPS-EOP of the partial page signal PPS. On the other hand, the facsimile communication apparatus 2 on the receiving side transmits a message confirmation signal MCF after confirming completion of reception of image data for all pages.

  As a result, transmission / reception of image data is completed, and the facsimile communication apparatus 1 on the transmission side transmits a disconnect command signal DCN (DisCoNnect signal) to the facsimile communication apparatus 2 on the reception side, and the connection with the communication line 50 by the communication unit 20 is cut off. To do. Similarly, the reception-side facsimile communication device 2 that has received the disconnection command signal DCN cuts off the connection with the communication line 50 by the communication unit 20 and performs facsimile communication by the transmission-side facsimile communication device 1 and the reception-side facsimile communication device 2. Ends. The processing related to the facsimile communication is performed by the control unit 11 of the facsimile communication apparatuses 1 to 3 controlling the operation of each unit.

  3 to 6 are schematic diagrams for explaining detailed procedures related to transmission of image data of facsimile communication performed by the facsimile communication apparatus 1, and data or signals transmitted by the facsimile communication apparatus 1 and received data. Alternatively, the signal is shown as time elapses. 3 shows a procedure for transmitting image data by a conventional facsimile communication apparatus, FIGS. 4 and 5 show a case where an echo failure has occurred in the transmission of image data by a conventional facsimile communication apparatus, and FIG. These show the procedure for transmitting image data by the facsimile communication apparatus 1 according to the present invention.

  A conventional facsimile communication apparatus on the transmission side receives the reception preparation confirmation signal CFR from the facsimile communication apparatus on the reception side, and then the reception facsimile communication apparatus performs reception in synchronization with the image data to be transmitted. Then, a dummy signal having a predetermined time length T0 is transmitted, and then image data is transmitted (see FIG. 3). The time length T0 of the dummy signal is set to about 200 ms, for example. After transmitting the image data, the transmitting facsimile communication apparatus transmits a partial page signal PPS to the receiving facsimile communication apparatus to confirm reception of the image data.

  Some or all of the image data transmitted from the transmission side to the reception side via the communication line 50 may not be received by the reception side facsimile communication apparatus due to the influence of external noise generated in the communication line 50. . If the facsimile communication apparatus on the receiving side cannot normally receive the image data, it responds to the partial page signal PPS given from the facsimile communication apparatus on the transmitting side with a partial page request PPR. By this, it is possible to notify the transmission side facsimile communication apparatus of the loss of the received image.

  When the transmission side facsimile communication apparatus receives a partial page request PPR from the reception side facsimile communication apparatus as a response to the partial page signal PPS, the transmission side facsimile communication apparatus retransmits the image data. Since the occurrence timing of communication failures due to external noise is often random, image data that could not be normally received in the previous transmission due to retransmission of image data may be normally received by the receiving facsimile communication apparatus. It can be expected that all image data can be normally received finally by repeatedly retransmitting the image data.

  On the other hand, an echo failure occurs in the facsimile communication, and a reception signal such as a reception preparation confirmation signal CFR or a partial page request PPR from the facsimile communication device on the reception side is transmitted by a facsimile communication on the transmission side with a certain delay. When superimposed on the signal, the facsimile communication apparatus on the receiving side cannot correctly receive the image data for this superimposed portion (see FIG. 4). For this reason, the receiving facsimile communication apparatus transmits a partial page request PPR to the transmitting facsimile communication apparatus.

  However, while the occurrence timing of communication failure such as external noise is random, the occurrence timing of echo failure depends on the configuration of the communication line 50 and is constant. For this reason, even if the transmission side facsimile communication apparatus retransmits the image data in response to the partial page request PPR, an echo failure occurs at the same timing in the retransmitted image data, and the reception side facsimile communication apparatus Cannot correctly receive the same part of the image data. Therefore, even if the transmission side facsimile communication apparatus repeatedly retransmits the image data, the reception side facsimile communication apparatus cannot correctly receive the specific portion of the image data due to the echo failure.

  As a countermeasure against the echo failure of the conventional facsimile communication apparatus, it is conceivable to set the time length T0 ′ of the dummy signal before transmitting the image data sufficiently long with respect to the time when the echo failure may occur. (See FIG. 5). By setting the time length T0 ′ of the dummy signal sufficiently long, even if an echo failure occurs, the facsimile communication apparatus on the receiving side can correctly receive the image data by synchronizing with the dummy signal after the disappearance. . If the delay time in which the reception preparation confirmation signal CFR or the partial page request PPR returns due to an echo failure is about 1200 ms, the time length T0 ′ of the dummy signal may be set to a sufficiently long time, for example, about 3000 ms. it can.

  However, if the time length T0 'of the dummy signal is set long, the overall communication time required for facsimile communication becomes long. For this reason, there is a problem that the communication cost required for the facsimile communication increases, and that the communication line 50 is occupied for a long time, thereby hindering communication of other facsimile communication apparatuses.

  Therefore, the facsimile communication apparatus 1 according to the present invention sets the time length T1 of the dummy signal transmitted before the second and subsequent image data to be longer than the time length T0 of the dummy signal transmitted before the first image data. Yes (see FIG. 6). As a result, the occurrence of echo failure can be made different at the first time and the second and subsequent times. For example, even when the reception preparation confirmation signal CFR from the reception-side facsimile communication apparatus 2 is superimposed on the image data transmitted by the transmission-side facsimile communication apparatus due to an echo failure at the time of transmission of the first image data, 2 Since the time length T1 of the dummy signal is longer than the first time after the first time, there is an increased possibility that the receiving side facsimile communication apparatus can normally receive the image data without superimposing the partial page request PPR on the transmitted image data. Further, even when the partial page request PPR is superimposed on the transmission of the second and subsequent image data, the image data normally received in the first communication and the image data normally received in the second and subsequent communication By integrating these, the receiving side facsimile communication apparatus can acquire image data with no omission.

  In addition, when a communication failure such as an echo failure does not occur during transmission / reception of image data, the receiving side facsimile communication apparatus can normally acquire the image data by the first communication. For this reason, the time length T0 of the first dummy signal is made shorter than the time length T1 of the second and subsequent dummy signals, so that transmission / reception of image data when no communication failure occurs can be speeded up, and communication performance is improved. Can be increased.

  Hereinafter, processing performed by the facsimile communication system according to the present invention will be described using a flowchart. However, in order to simplify the description, the amount of image data transmitted and received between the transmission-side facsimile communication device 1 and the reception-side facsimile communication device 2 is short (for example, ECM (Error Correction Mode) standard for facsimile communication). The case of an image of a short block (shorter than 256 blocks) will be described. If the image data to be transmitted / received is long, more procedures are required, but detailed description is omitted.

  7 and 8 are flowcharts showing the procedure of image data transmission processing performed by the transmission-side facsimile communication apparatus 1 according to the present invention. The control unit 10 of the transmission-side facsimile communication apparatus 1 controls the operation of each unit. This process is performed. When transmitting the image data, the control unit 10 of the facsimile communication apparatus 1 first transmits the calling tone CNG, receives the called station identification signal CED and the digital identification signal DIS, and the digital command signal DCS and the training check signal. The TCF is transmitted to perform processing for establishing facsimile communication with the receiving facsimile communication apparatus 2 (step S1).

  Next, the control unit 10 of the transmission side facsimile communication apparatus 1 determines whether or not the reception preparation confirmation signal CFR transmitted from the reception side facsimile communication apparatus 2 has been received (step S2), and the reception preparation confirmation signal CFR. Is not received (S2: NO), it waits until the reception preparation confirmation signal CFR is received. When receiving the reception preparation confirmation signal CFR (S2: YES), the control unit 10 transmits a dummy signal having a time length T0 to the facsimile communication apparatus 2 on the receiving side (step S3), and then transmits the image data (step S3). S4). Thereafter, the control unit 10 determines whether or not transmission of one page of image data has been completed (step S5). If transmission has not been completed (S5: NO), the image data is continuously transmitted. .

  When the transmission of the image data for one page is completed (S5: YES), the control unit 10 of the transmitting facsimile communication apparatus 1 transmits the partial page signal PPS to the receiving facsimile communication apparatus 2 (step S6). Then, it is determined whether or not the message confirmation signal MCF from the receiving side facsimile communication apparatus 2 has been received (step S7).

  If the message confirmation signal MCF has not been received (S7: NO), the control unit 10 of the transmitting facsimile communication apparatus 1 further determines whether or not the partial page request PPR has been received from the receiving facsimile communication apparatus 2. (Step S8). If the partial page request PPR has not been received (S8: NO), the control unit 10 returns to step S7 and waits until a message confirmation signal MCF or a partial page request PPR is received from the receiving facsimile communication apparatus 2.

  When the partial page request PPR is received (S8: YES), the control unit 10 of the transmission side facsimile communication apparatus 1 sends a dummy signal having a time length T1 longer than the time length T0 of step S3 to the reception side facsimile communication apparatus 2. The image data is transmitted (step S9), and the image data is retransmitted (step S10). Thereafter, the control unit 10 determines whether or not the retransmission of the image data is completed (step S11). If the retransmission is not completed (S11: NO), the image data is continuously retransmitted. Do. When the retransmission of the image data is completed (S11: YES), the control unit 10 returns to step S6 and repeats the retransmission of the image data until the message confirmation signal MCF is received from the facsimile communication apparatus 2 on the receiving side. Do.

  When the message confirmation signal MCF is received (S7: YES), the control unit 10 of the transmission-side facsimile communication apparatus 1 determines whether or not all (all pages) image data has been transmitted (step S12). . When the transmission of all the image data has not been completed (S12: NO), the control unit 10 returns to step S3 and repeats the processes of steps S3 to S11 described above. When transmission of all the image data is completed (S12: YES), the control unit 10 transmits a disconnection command signal DCN to the facsimile history device 2 on the receiving side (step S13), disconnects the facsimile communication and ends the process. To do.

  FIG. 9 and FIG. 10 are flowcharts showing the procedure of image data reception processing performed by the receiving facsimile communication apparatus 2 according to the present invention. The control unit 10 of the receiving facsimile communication apparatus 2 controls the operation of each part. This process is performed. When receiving image data, the control unit 10 of the facsimile communication apparatus 2 first receives the calling tone CNG, transmits the called station identification signal CED and the digital identification signal DIS, and the digital command signal DCS and the training check signal. A process of receiving the TCF and establishing a facsimile communication with the facsimile communication apparatus 1 on the transmission side is performed (step S31).

  Next, the control unit 10 of the facsimile communication apparatus 2 on the reception side transmits a reception preparation confirmation signal CFR to the facsimile communication apparatus 1 on the transmission side (step S32) and receives a dummy signal from the facsimile communication apparatus 1 on the transmission side. Is determined (step S33). When the dummy signal is not received (S33: NO), the control unit 10 waits until the dummy signal is received.

  When the dummy signal is received (S33: YES), the control unit 10 of the facsimile communication apparatus 2 on the receiving side performs a synchronization process for receiving image data based on the received dummy signal (step S34), and the transmitting side Image data from the facsimile communication apparatus 1 is received (step S35). Thereafter, the control unit 10 determines whether or not the reception of the image data for one page has been completed (step S36). If the reception has not been completed (S36: NO), the reception of the image data is continued. Do.

  When the reception of the image data is completed (S36: YES), the control unit 10 of the receiving facsimile communication apparatus 2 determines whether or not the partial page signal PPS from the transmitting facsimile communication apparatus 1 has been received ( Step S37). When the partial page signal PPS has not been received (S37: NO), the control unit 10 stands by until the partial page signal PPS is received.

  When the partial page signal PPS is received (S37: YES), the control unit 10 integrates the already received normal image data and determines whether or not there is a defect in the image to be received (step S38). If there is a defect in the image (S38: YES), the control unit 10 transmits a partial page request PPR to the facsimile communication apparatus 1 on the transmission side (step S39), returns to step S33, and receives a dummy signal and image data. I do.

  If there is no defect in the received image (S38: NO), the control unit 10 of the facsimile communication device 2 on the reception side transmits a message confirmation signal MCF to the facsimile communication device 1 on the transmission side (step S40). Next, the control unit 10 determines whether or not reception of all (all pages) image data to be received has been completed (step S41). If reception has not been completed (S41: NO), step S33 is performed. Returning to the step of receiving dummy signals and image data.

  When the reception of all the image data is completed (S41: YES), the control unit 10 of the receiving facsimile communication apparatus 2 determines whether or not the disconnection command signal DCN from the transmitting facsimile communication apparatus 1 has been received. (Step S42). When the cutting command signal DCN is not received (S42: NO), the control unit 10 waits until the cutting command signal DCN is received. When the disconnection command signal DCN is received (S42: YES), the control unit 10 disconnects the line of facsimile communication with the facsimile communication apparatus 1 on the transmission side (step S43), and ends the process.

  In the facsimile communication apparatus 1 (2 and 3) having the above configuration, the time length T0 of the dummy signal to be transmitted before transmission of the first image data and the transmission of the second and subsequent (that is, retransmission) image data are transmitted. By setting the time length T1 of the dummy signal to a different time length, it is possible to shift the timing at which an echo failure occurs with respect to the image data to be transmitted / received, so that the image data can be reliably transmitted / received. Further, by making the time length T1 of the second and subsequent dummy signals longer than the time length T0 of the first dummy signal, the transmission / reception of image data when no communication failure occurs can be speeded up. Communication performance can be improved. Further, when the reception side facsimile communication apparatus 2 receives the reception preparation confirmation signal CFR from the reception side facsimile communication apparatus 1, the transmission side facsimile communication apparatus 1 transmits a dummy signal having a time length T0, and when the partial page request PPR is received. A dummy signal having a time length T1 may be transmitted.

  In the present embodiment, the time length of dummy signals after the second time is uniformly set to T1 (> T0). However, the present invention is not limited to this, and the second time, the third time, the fourth time, and so on. The time length of the dummy signal may be increased stepwise (see Modification 1), the dummy signal may be changed randomly within a predetermined time range, and the time length of the dummy signal may be set according to other rules. It may be changed. In addition, the time length T0 of the first dummy signal is the shortest. However, the present invention is not limited to this, and the time length of the second and subsequent dummy signals may be short. However, in order to improve the performance of facsimile communication, it is desirable that the first dummy signal has the shortest time length T0.

  In the present embodiment, the facsimile communication system including the facsimile communication apparatuses 1, 2, and 3 as the image transmitting apparatus and the image receiving apparatus has been described as an example. However, the present invention is not limited to this, and an echo failure occurs. A similar effect can be obtained by applying the present invention to any communication system that is likely to do so. For example, as the image transmission device and the image reception device, not only the facsimile communication devices 1, 2, and 3, but also other devices such as a digital multi-function peripheral having a facsimile communication function or a PC (Personal Computer) may be used.

(Modification 1)
FIG. 11 is a schematic diagram for explaining a detailed procedure related to transmission of image data of facsimile communication performed by the facsimile communication apparatus 1 according to the first modification. Data or a signal transmitted by the facsimile communication apparatus 1 and reception The data or signal to be displayed is shown as time elapses. The facsimile communication apparatus 1 according to the first modification increases the time length T1 of the second dummy signal from the time length T0 of the first dummy signal, and sets the time length T2 of the third dummy signal from the second dummy signal T1. Lengthen. In other words, the time length of the dummy signal is gradually increased each time the number of image data retransmissions increases.

  If the time length of the dummy signal after the second time is uniform, when an echo failure occurs, the missing part of the image in the image data transmitted / received for the first time and the missing part of the image in the image data transmitted / received after the second time There is a risk that and will partially overlap. Therefore, as in the facsimile communication apparatus 1 shown in the first modification, the time length of the dummy signal is increased in accordance with the number of retransmissions of the image data, so that the echo for the image data is performed each time the image data is retransmitted. Since the failure occurrence timing can be shifted, image data can be transmitted and received more reliably.

(Modification 2)
As described above, in the case where image data is transmitted and received and partially affected by an echo failure, this echo failure gives an image loss to the same timing from the beginning of the image data. In other words, if the missing part of the image received for the first time by the facsimile communication apparatus 2 on the receiving side overlaps with the missing part of the image received after the second time, there is a possibility that an echo failure has occurred. high.

  Therefore, when receiving image data, the facsimile communication device 2 on the receiving side of the facsimile communication system according to the modified example 2 detects a missing portion of the image (image region that could not be received), and stores information relating to this missing portion. The partial page request PPR is added to the partial page request PPR, and the partial page request PPR including information on the missing part is transmitted to the facsimile communication apparatus 1 on the transmission side.

  For example, in the flowcharts shown in FIG. 9 and FIG. 10, after the reception of the image data is completed in step S36, a step of detecting a missing portion and a step of generating information on the detected missing portion are added. If it is determined in step S38 that there is a missing image, a step of adding information relating to the missing portion to the partial page request PPR is added, and a partial page signal to which information relating to the missing portion is assigned in step S39. Just send it.

  In addition, the transmission side facsimile communication apparatus 1 that has received the partial page request PPR from the reception side facsimile communication apparatus 2 stores information on the missing portion included in the partial page request PPR and receives the partial page request PPR. If it is the second time or later, the missing part received this time is compared with the missing part received and stored last time to determine whether or not they overlap. The facsimile communication apparatus 1 on the transmission side transmits a dummy signal having a time length T1 when it is determined that the missing portion is overlapped, and transmits a dummy signal having a time length T0 when it is determined that the missing portion is not overlapped. The data may be retransmitted.

  For example, in the flowchart shown in FIG. 7 and FIG. 8, when the partial page request PPR is received in step S8, the step of storing the information related to the missing portion included in the partial page request PPR, and the partial page request What is necessary is just to add the step which determines whether reception of PPR is after the 2nd time. Further, when the partial page request PPR is received for the first time instead of the second time or later, a step of transmitting a dummy signal having a time length T0 is added. When the partial page request PPR is received for the second time or later, After transmitting the dummy signal having the time length T1 in step S9, the image data may be retransmitted in step S10.

  The facsimile communication system according to the modified example 2 having the above configuration retransmits image data when a communication failure that causes a loss in an image received by the receiving facsimile communication device 2 is not caused by an echo failure. The time length of the dummy signal transmitted before can be set to a short time of T0. Therefore, when the communication failure is other than the echo failure, the image data can be retransmitted in a short time.

It is a block diagram which shows the structure of the communication system which concerns on this invention. It is a schematic diagram for demonstrating the procedure of the facsimile communication which a facsimile communication apparatus performs. It is a schematic diagram for demonstrating the detailed procedure which concerns on the transmission of the image data of the facsimile communication which a facsimile communication apparatus performs. It is a schematic diagram for demonstrating the detailed procedure which concerns on the transmission of the image data of the facsimile communication which a facsimile communication apparatus performs. It is a schematic diagram for demonstrating the detailed procedure which concerns on the transmission of the image data of the facsimile communication which a facsimile communication apparatus performs. It is a schematic diagram for demonstrating the detailed procedure which concerns on the transmission of the image data of the facsimile communication which a facsimile communication apparatus performs. 6 is a flowchart showing a procedure of image data transmission processing performed by the facsimile communication apparatus on the transmission side according to the present invention. 6 is a flowchart showing a procedure of image data transmission processing performed by the facsimile communication apparatus on the transmission side according to the present invention. 4 is a flowchart showing a procedure of image data reception processing performed by a reception-side facsimile communication apparatus according to the present invention. 4 is a flowchart showing a procedure of image data reception processing performed by a reception-side facsimile communication apparatus according to the present invention. FIG. 10 is a schematic diagram for explaining a detailed procedure related to transmission of image data of facsimile communication performed by the facsimile communication apparatus according to Modification 1.

Explanation of symbols

1, 2, 3 Facsimile communication device (image transmission device, image reception device)
10 Control unit (pre-image transmission signal transmission means, confirmation signal transmission means, response signal reception means, re-transmission means, reception means, response signal transmission means)
DESCRIPTION OF SYMBOLS 11 Document reading part 12 Printing part 13 Operation part 14 Display part 15 Storage part 16 Encoding / decoding part 17 Time measuring part 18 Bus 20 Communication part 21 NCU
22 Modem 50 Communication line

Claims (6)

In an image transmission apparatus that transmits an image to another apparatus via a communication line,
Before transmitting an image, a signal transmission means before image transmission for transmitting a signal having a predetermined time length to the other device;
Confirmation signal transmitting means for transmitting a confirmation signal for confirming reception of the image to the other device after transmission of the image;
Response signal receiving means for receiving a response signal from the other device for the confirmation signal transmitted by the confirmation signal transmitting means;
Resending means for resending the image according to the response content of the response signal received by the response signal receiving means,
The signal transmission means before image transmission is configured to transmit a signal having a time length different from the predetermined time length to the other device before the retransmission means retransmits the image. An image transmitting device. The signal transmission means before image transmission transmits a signal having a time length longer than the predetermined time length to the other device before the retransmission means retransmits the image. The image transmission apparatus according to claim 1. Each time the response signal receiving means receives the response signal, the retransmission means performs image retransmission according to the response content of the response signal,
The signal transmission means before image transmission increases the time length of a signal to be transmitted before image transmission according to the number of retransmissions of the retransmission means. Item 3. The image transmission device according to Item 2. The signal transmission unit before image transmission transmits a signal having a time length different from the predetermined time length when the response signal receiving unit receives a signal related to a retransmission request from the other device as the response signal. The image transmission device according to any one of claims 1 to 3, wherein the image transmission device is configured as described above. In a communication system including an image transmission device and an image reception device that transmit and receive an image via a communication line,
The image transmission device includes:
Before transmitting an image, a signal transmission means before image transmission for transmitting a signal having a predetermined time length to the image receiving device;
Confirmation signal transmitting means for transmitting a confirmation signal for confirming reception of the image to the image receiving device after transmitting the image;
Response signal receiving means for receiving a response signal from the image receiving apparatus with respect to the confirmation signal transmitted by the confirmation signal transmitting means;
Resending means for resending an image according to the response content of the response signal received by the response signal receiving means,
The signal transmission means before image transmission is configured to transmit a signal having a time length different from the predetermined time length to the image reception device before the retransmission means performs image retransmission.
The image receiving device includes:
Receiving means for receiving an image from the image transmitting device;
Response signal transmitting means for transmitting a response signal related to whether or not an image can be received by the receiving means in response to a confirmation signal from the image transmitting apparatus. The image receiving device includes:
Among the images transmitted by the image transmission device, the image processing apparatus includes a detection unit that detects an image area that the reception unit could not receive,
The response signal transmission unit adds information related to the image area detected by the detection unit to the response signal and transmits the information to the image transmission device;
The image transmission device includes:
The signal transmission means before image transmission determines a time length of a signal to be transmitted according to information relating to the image area included in the response signal received by the response signal reception means. The communication system according to claim 5.

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