JPH02140055A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To reduce the missing of a received picture in the occurrence of a transmission error and to decrease the reduction in the length of recording paper by providing a line error detection means or the like detecting the presence of a date error in every line of picture information data in a data frame. CONSTITUTION:Picture information is processed into a frame in a data format of a prescribed frame and sent in a facsimile equipment 1 composed of a scanner 11, a plotter 12, a coding and decoding section 13 and a system control section 18 or the like. Then error detection is applied by an error detection code CRC code set to a frame check sequence FCS of each frame in the reception of picture information or the error detection for each a line in a frame is implemented by each EOL code, Moreover, picture information in the data error in one data frame is stored in a picture memory 14 or a data quantity less than the usual data quantity in one data frame is set to reduce the missing in the received picture and the reduction in the length of the recording paper.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a facsimile device.

[Prior Art] A facsimile device that transmits image information in accordance with the error correction mode (hereinafter abbreviated as ECM) of the G3 standard recommended by CCITT is in practical use.

Now, for example, on the sending facsimile machine, as shown in Fig. 25 (
As shown in a), if one page of the original is read and encoded data d-dn from the 1st line to the nth line are obtained, each encoded data has a line break. The EOL code shown is added. The above ECM
Now, this image information data is an HDLC of a specified format.
256 bytes or 64 bytes are set in each frame, and a maximum of 256 frames are sent as I block image information.

Then, the receiving side checks the received image information data for data errors frame by frame, and when a data error is detected, requests retransmission of the image information data of the frame in which the error occurred. In response, the transmitting side retransmits the image information data of the requested frame.

Incidentally, in recent years, facsimile communications using car telephone devices and MCA wireless devices have become commonplace. In such a case, since a wireless line is used, the line condition deteriorates and transmission errors are likely to occur. Therefore, if ECM communication is performed under such conditions, retransmission operations will be repeated many times.

Generally, in ECM, every three retransmission operations,
The data transmission speed is shifted down, but if the retransmission operation is performed three times at the lowest speed of 2400 bps, the transmission process is aborted.If the same frame is retransmitted three times and the transmission is not successful, the retransmission of that frame is stopped. Then, the next predetermined transmission is continued.

[Problems to be Solved by the Invention] Assume that the receiving side receives one page of images in one block in this manner, and, for example, transmission of a specific frame f1 is stopped. In this case, as shown in Figure (b), the image for that one frame is not recorded, and instead, a blank space is left at the error frame position to indicate, for example, an error. .

However, although a large number of lines of information are transmitted in one frame, in the past, even if there was a data error in just one line, the entire image of the frame would be lost, and the original image on the sending side would be long. There was a problem in that the length of the recorded image on the receiving side was significantly shortened compared to the length Lo.

On the other hand, in ECM, one block of image information is a maximum of 256 frames if the frame is 256 bytes, so 64
The amount of data is kilobytes. When the image information of one page exceeds 9 minutes per blower, the image information of one page is divided into a plurality of blocks as a partial page and transmitted.

4. For example, suppose that in a case where one page of image is divided into two partial pages and transmitted, the retransmission operation is aborted before error correction is completed in the transmission of the first partial page.

In this case, on the receiving side, as shown in Figure (c), not only is the image missing in the first half of one page, but the second half is not received, resulting in a problem that the image of the first page cannot be recorded. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile apparatus which eliminates the above-mentioned problems and reduces the loss of received images and shortening of recording paper length when a transmission error occurs.

[Means for Solving the Problems] To this end, the present invention provides, as a first means, that when an error in image information data within one data frame is detected when it is impossible to execute a retransmission request, The presence or absence of data errors is detected for each line of image information data in a data frame, and image information without data errors is recorded every 1 lines. As a second means, when communicating via a line where transmission errors are likely to occur, CC is added to one data frame of the data signal that transmits image information.
Image information data with an amount smaller than the normal data amount according to the ITT standard is set and communicated.

Furthermore, as a third means, when one page of a manuscript is transmitted as a partial page in multiple blocks, the receiving side can:
■In the case of the final retransmission in which a data signal of a block is received, retransmission is repeated, and the next retransmission request is canceled, and the received block is not the final image information of one page of the original image, Even if a data error is detected, the process moves on to receiving the data signal of the next block without requesting retransmission. However, if the retransmission request is not made in this way, when the data signal of the block of the final image information is received, In addition, even if no data error is detected, the sender is notified of a reception error.

Furthermore, as a fourth means, all the image information received each time, including the first time and retransmission, is stored at least until it is recorded on recording paper, but if the reception of one block of data signals is discontinued, a transmission error occurs. For the remaining data frames, image information data without errors is sequentially extracted from the image information of each of the above-mentioned times of the error frame, and
Decoding and recording are performed.

In addition, as a means for extracting error-free image information data in the above, each bit of the image information data of each time is collated, the correct data is estimated by majority vote, and the image information obtained thereby is recorded on recording paper. That's what I do.

[Operation] In the first means, by recording image information without data errors within one data frame, it is possible to reduce dropouts in received images and shortening of recording paper length.

In addition, in the second method, (1) By setting image information data in a data frame with an amount of data smaller than the normal data amount, even if an entire frame has an error, the received image can be processed as described above. It is possible to reduce the number of missing pieces and the shortening of the recording paper length.

Furthermore, with the third means, when one page of the original document is divided into a plurality of blocks and transmitted, the transmission is not stopped in the middle of one page. As a result, the receiving side can always receive the entire page, reducing the number of missing images. Furthermore, in the fourth method, if there is an error while receiving one page, the receiving side always notifies the sending side of the error after receiving the entire page, so that the sending side can successfully send the message. This will prevent you from misunderstanding that you have done it.

By the way, transmission errors in image information received multiple times due to retransmission processing usually occur at different bit positions, but with the fourth means, even if there is an error in image information data received once, it will not be detected in another time. Error-free image information data can be extracted from the image information. This makes it possible to reduce the occurrence of missing and shortened received images.

Also, when extracting image information data without the above errors,
By estimating the bit value of image information each time by majority vote, correct image information can be reproduced with a simple method.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a block diagram of an in-vehicle facsimile system according to a first embodiment of the present invention. In the figure, a facsimile device 1 has an interface circuit 2.
A handset 4 for operating the car phone and making calls is connected to the interface circuit 2 .

In the facsimile machine 1, a scanner 11 reads an original image and extracts image information of a predetermined resolution, and a plotter 12 records the image information on recording paper.

The encoding/decoding unit 13 encodes image information to be transmitted and decodes received image information. The image memory 14 temporarily stores image information.

The modem 15 modulates and demodulates and transmits both information and also transmits various procedure signals in transmission control procedures. The communication control unit 1G controls the transmission of the ECM and executes a predetermined facsimile transmission.

The operation display section 17 is used to display the device status, operation guidance, etc., and to perform various operations. The system control unit 18 is composed of a microcomputer system, and the scanner 11 . Block 12
．． Encoding/decoding unit 132 image memory 14. Communication control unit 1
6. It is connected to the operation display section 17 and the system control section 18, and controls these sections to execute predetermined operations of the facsimile machine.

When receiving a document image with the above configuration, the operator uses the handset 4 to discuss with the transmitting side that the document will be received by telephone, and then presses the receive button on the operation display section I7.

As a result, facsimile communication is started according to a predetermined transmission control procedure by the ECM.

By the way, in ECM, image information is transmitted in a frame using a predetermined HDLC frame data format 1-.

One frame of the image information frame in this case is shown in Fig. 2 (a
), it consists of a flag sequence F, an address field A, a control field C, a facsimile control field FCF, a facsimile information field PIF, a frame check sequence FC3, and a flag sequence F.

The facsimile control field FCF contains information indicating that it is a frame of one-stroke information.
D'' is set. The frame number NO and encoded image information CD are set in the facsimile information field PIF. A CRC code, which is an error detection code, is set in the frame check sequence FC3.

A maximum of 256 frames having such a configuration are arranged, and a preamble and an information frame for returning to transmission control are added to form one block of data signal.

The image information CD for each frame f1 to fm contains 256 bytes or 64 bytes of encoded image information data d1 to dn of each line separated by the E-code, as shown in FIG. 2(b). are set one by one. Incidentally, in the image information CD of the final frame f, an RTC code indicating the end of the image information data is set, and dummy data of all 0s is added to make the number of bits constant.

FIGS. 3(a) and 3(b) show the operation of receiving image information, in which one block of image information transmitted as described above is received and temporarily stored in a data buffer (not shown). Processing 101). Next, image information data is read frame by frame from the data buffer, and error detection is performed using the CRC code of the frame (process 102).

Here, if there is no data error (Y in process 103), the image information data of that one frame is stored in the image memory 14 (process 104). Next, it is determined whether the processing for one block has been completed (N in process 105), and if it has not been completed yet (N in process 105), the process returns to error detection for the next frame in the same way (go to process 102). ).

By the way, in this embodiment, as an example, if the sending side executes the retransmission operation three times at the lowest data transmission speed of 2400 bps, the sending side will abort the sending process, while the sending side will not be able to send the same frame even if it is retransmitted three times. If not successful, retransmission of that frame is stopped and the next predetermined transmission continues. In this case, after transmitting the final block of image information, the transmitting side transmits an Eol (signal) to notify the receiving side.

Next, if it is assumed that there is a data error in the picture information of one frame (N in process 103), it is determined whether the picture information is not the last picture information at the time of aborting retransmission (process) 06). If it is not the last time (N in process 10G), set a predetermined bit of the frame data of the PPR signal sent in a retransmission request to 1'1''', and remember that a retransmission request for that frame is required. (Process 107).

Each frame is processed in this way, and when all frames for one block have been processed (Y in process 105), a retransmission request is made if necessary. In other words, if any bit of the frame data of the PPR signal is set to 1'', not when retransmission is aborted, a predetermined PPR signal is sent to the other party to request retransmission of image information ( Process 109) from Y in process 108).

On the other hand, from the transmitting side, the image information of the requested frame is configured into one block and transmitted.

The receiving side receives this and checks it frame by frame in the same way as above, and the correct image information data is stored in the image memory 1.
If an error is detected again, frame data of the PPR signal is set for that frame. After processing l blocks, a retransmission request is issued and retransmission processing is executed.

For example, if the retransmission process is executed in this way and the same frame is retransmitted three times, the transmitting side will transmit an EOR signal indicating the termination of the retransmission. In this case (Y in process 106), by identifying the EOL code,
The image information data within one frame is extracted line by line (processing 110). If it is not the last line in that one frame (N in process 111), it is determined whether or not there is an error in the image information data of that one line.

By the way, in this embodiment, M H is used as the data compression method.
method is adopted. In the case of this MH system, one line of image information data is formed by a termination code, a makeup code, an EOL code, an RTC code, and all +j OII dummy data.

When the image information data is decoded, the original image information data with a certain number of bits is obtained by converting the termination code and the makeup code with reference to the code table.

In this case, if there is data that is not in the above code table in one line of image information data, or if there are consecutive makeup codes, or if there is an EOL code after the makeup code, each It can be determined that there is a data error.

Further, it can also be determined that there is a data error if the predetermined number of bits is not reached when the image information data is decoded into the original image information data.

Next, in this embodiment, decoding of the one line of image information extracted above is executed, and data errors are detected under the above four conditions. That is, first, it is checked whether each piece of image information data exists in the code table (process 112). If the check result is OK (processing 11
(Y of 2) Next, the sequence of makeup codes is checked (process 113). If the check result is OK (
Y of process 113), then the next E of the makeup coat
Check the OL coat (process 114). If the check result is OK (Y on processing day 4), then it is checked whether the image information data obtained by decoding has a predetermined number of bits (process 115). If the check result is OK (Y in process 115), the image memory 14
The image information of that one line is stored in (processing 116).

On the other hand, if an error is detected in any of the above checks (N in each of processes 112 to 115), the image information data of the white information is stored in the image memory 100 instead of the image information of the error.
4 (process 117).

Thereafter, one line of primary image information data is taken out and the same process is performed (proceed to process 110). As a result, among the image information data of each line within one frame, those without errors are stored in the image memory 14.

Incidentally, since the image information data for the final line is often divided into the next frame and is not complete for one line, the above process is not executed for the final line.

Therefore, in the case of the last line (Y in process 111), next 1
Determine whether block processing is completed (processing 10
5). Here, if it has not finished (N in process 105)
, the same process is repeated (to process 102).

In this way, when the processing of the block ■ is completed (Y in process 105), it is then determined whether a retransmission request is necessary or not.
8) If there is no retransmission request (N in process 108), the image information stored in the image memory 14 is sequentially read out and decoded;
It is recorded by the plotter 12 (process 118).

After this recording, if the next image information is transmitted (process 119
Y), the next block of image information is received and processed in the same manner as above (proceed to process 101). Further, when the processing of the final block is finished (N in process 119), one or more reception processes are finished.

Here, for example, the image shown in FIG. 25(a) is transmitted from the transmitting side, and the correct image information data is not received even if one frame f1 is retransmitted three times in the i process. In this case, since the image information of the error-free line in frame fl is recorded, it is necessary to record the received image to some extent for the part corresponding to the error frame f1, as shown in Figure 4. become.

As described above, in this embodiment, when an error in image information data within one data frame received in the final round of retransmission processing is detected, whether or not there is a data error is determined for each line of image information data within that data frame. is detected, and image information without data errors is recorded line by line.

As a result, as shown in FIG. 4, the received image has fewer missing parts and the length L2 of the recorded image is also reduced.

Next, a second embodiment of the present invention will be described.

In the embodiment described above, one method for transmitting image information is DLC.
As recommended by CCITT, 256 bytes or 64 bytes of image information are set in the frame, but 1
In this embodiment, image information is set in units of 32 bytes.

In this case, as shown in FIG. 5, at the start of communication,
The receiving side sends out the CED signal and the NsF and prsig signals. At this time, the NSF signal notifies the device of its own function, such as having the function of receiving image information in units of 32 bytes.

The transmitting side determines the receiving side function based on the above signal. Then, an NSS signal is sent to notify the amount of image information per frame, which is 32 bytes in this example.

Then, after executing a predetermined transmission control procedure, the sending side
As shown in FIG. 6, the image of each line of the transmitted original is read (process 201) and sequentially encoded (process 202).
. Next, the encoded image information data of each line is added with an EOL code and an RTC code as described above (process 203), and then temporarily stored in the image memory 14 (process 204).

Next, as shown in FIG. 7, for example, the stored image information data is read out one frame at a time, that is, 32 bytes (process 205), and a predetermined image information frame is constructed (process 206). Then, a data signal composed of this image information frame is sent from the modem 15 (process 207).

Next, if there is other image information data (Y in process 208)
), and similarly transmitted (to process 205).

Now, assuming that the image information to be transmitted is only one block, after the sending of the planning information data is completed (N in process 208),
PPS and EOP signals are sent to notify the end of image information (process 209).

FIG. 8 shows the processing in FIG. 3 (a) in the receiving side processing of this embodiment.
) and (b). That is, on the receiving side, if the image information frame has a data error (N in process 103) and it is time to abort retransmission (Y in process 1.06), a white line is displayed instead of the image information of the error frame. image information is stored in the image memory 14 (process 120). Others are shown in Figure 3 (a) and (b).
The image information reception and recording operations described in 2 are executed in the same manner.

Therefore, if a transmission error occurs and a data error is detected in the received image information, a PPR signal is sent out to request retransmission of the image information frame.

Figure 9 shows the image information retransmission process on the sending side.
When the transmitting side receives the PPR signal (process 301), it reads the image information data of the frame requested for retransmission from the image memory 14 (process 3o2). And, like above,
A predetermined frame is formed (process 303) and transmitted (process 304).

Furthermore, in this embodiment, similar to the above-described embodiments, the retransmission process is aborted after retransmission a certain number of times under certain conditions. Therefore, next, the condition is determined and processed 305)
, if it is not the final retransmission process (N in process 305)
, sends PPS and EOP signals indicating the end of image information (
Process 306).

Now, suppose that transmission errors occur frequently and retransmission processing is repeatedly executed. In this case, in the final round of the above retransmission process (process 305) Y), the transmitting side sends EOR and EOP to notify the end of the image information and the termination of the retransmission process.
A signal is sent (process 307).

When the receiving side receives the image information of the last episode and there is a data error (from N in process 103, process 106,
Y in process 106), as described above, the image information of the white line is stored in the image memory 14 (process 120). and 1
The next frame is processed (proceed to process 105).

When all the frames of one block have been processed (processing 105Y), in this case, a retransmission request cannot be made (processing 108, N), so the image information stored in the image memory is sequentially read out and decoded, and the received image is transferred to the recording paper. (Process 1
18).

Now, for example, in the final round of retransmission processing, one frame f1
If an error occurs, the received image of the error frame f1 will be missing, as shown in FIG.

By the way, if there is a transmission error in even one bit of data within one frame, the entire frame will not be recorded as an error frame as described above. However, in this embodiment, the image information data transmitted in one frame is 32 bytes 1 or more, instead of the conventional 256 bytes or 64 bytes 1.
- is set less than -.

Therefore, as mentioned above, in the case of a slight error from P1 to F1, the proportion of the image corresponding to the error frame f1 decreases,
The number of missing received images is reduced, and the length L2 of the recorded image on the receiving side is less shortened with respect to the length Lo of the original image.

The inventor conducted an experiment on image transmission using ECM under a line condition where transmission errors are likely to occur, and measured the reduction in communication time and data error rate due to retransmission processing.

FIG. 11 shows the results obtained from a number of experiments. When the amount of image information per frame is large, such as 256 bytes, after communication starts, the data error rate decreases due to retransmission processing. It gradually decreases over time.

On the other hand, it has been found that when the amount of image information is small, such as 32 bytes, the data error rate decreases rapidly after the start of communication, but it takes time until it reaches zero.

Normally, retransmission processing is aborted under certain conditions.1 For example, if retransmission processing is aborted at time t after a certain period of time, the data error rate at that time t is, when the amount of data per frame is 256 bytes. The error rate becomes smaller as the amount of data decreases, such as when the error rate is e1.32 bytes, the error rate is e2.

Therefore, by reducing the amount of image information per frame as in this embodiment, data errors when retransmission processing is aborted can be made smaller than in the past.

Next, a third embodiment of the present invention will be described.

In this embodiment, image information for one line is set for each frame. Furthermore, at the start of communication, as shown in Fig. 5, the receiving side notifies the function of its own device using the NSF signal, while the transmitting side uses this to determine the function of the receiving side, and uses the NSS signal to notify the function of its own device. Notify communication mode.

Furthermore, the transmitting side transmits image information using the same procedure as in FIG. In this case, the image memory 14 contains the image shown in FIG.
As shown in a), EOL code and image information data
dI, and rlTc code. When storing these pieces of information, as shown in FIG. 3(b), the start address ^□~A-, of the image memory 14 storing each image information data d, ~do, is changed to the frame number. It is stored in correspondence with the following. The image information of each frame f□-f is composed of one line of encoded image information di and an EOL code, as shown in FIG. 2(c).

Further, the RTC coat is also assumed to be one frame fn+x.

The transmitting side transmits such image information using a predetermined HDLC frame.

FIG. 13 shows the processing in the receiving side of this embodiment as shown in FIG.
This figure shows the different parts from a) and (b). That is, on the receiving side, if there is no data error in the image information frame (Y in process 103), the received one frame of image information data is extracted and decoded (process) 21), and then stored in the image memory 14 (process 104). Note that what is decoded here is that when one line of image information data is decoded, it becomes a certain amount of data, for example, 1728 bits in the case of an A4 size document, and after being stored in the image memory 14. This is because data management becomes easier.

Also, if the image information frame has a data error (processing 1
03, N), and if it is the final retransmission process (Processing 106, Y), the image information of the white line is stored in the image memo January 4 instead of the image information of the error frame (
Process 120).

Other processing is performed in the same way as the receiving and recording processing described in FIGS. 3(a) and 3(b).

As a result, similar to the above-described embodiment, a retransmission request is executed as necessary, and image information is received.

Even in this case, retransmission processing is aborted under certain conditions.

However, in this embodiment, for one frame error,
Only one line of the received image is missing, and similarly to the previous embodiment, the recorded image is less likely to be missing or shortened.

Also, since the amount of data per frame is reduced,
This is advantageous when the data error rate decreases in a short period of time and retransmission processing is aborted midway.

Next, a fourth embodiment of the present invention will be described.

In this embodiment, it is assumed that the transmitting side is the same as in the first embodiment described above. FIG. 14 shows the response process to the transmitting side after the receiving side receives one block of image information. That is, when the receiving facsimile device receives the image information of one partial page (processing 401
), the next procedure signal is the PP5-NULL signal or PP5-E
Determine whether one page has ended depending on the OP signal (
Processing 402). If the image information is not the end of the page (N in process 402), then it is determined whether this is the third retransmission of 24008 PS, that is, the final retransmission (process 40
3). If it is not the last time (N in process 403), it is determined whether or not there is a transmission error (process 404), and if there is no error (
If there is an error (Y in process 404), a predetermined PPR signal is sent to request retransmission (process 406). ).

On the other hand, if it is the final retransmission (Y in process 403),
If there is no error (N in process 407), an MCF signal is transmitted (process 406). On the other hand, when an error occurs (processing 40
7 Y), after turning on the error flag provided to remember that there was an error in the partial page (process 408), in order to prevent communication from being interrupted by the sending side, (Processing 405)
).

On the other hand, if it is the end of one page (Y in process 402),
If there is an error (Y in process 409), PPR as usual
A signal is transmitted (process 406). Here, if there is no error (N in process 409), the error flag is checked (process 410). If the error flag is off (N in process 410), the MCF signal is sent (process 405), while if it is on (Y in process 410), the MCF signal is sent (process 405).
), sends a DCN signal notifying line disconnection (processing 4
11).

In FIG. 15(a), many transmission errors occurred while transmitting the image information PIX of the first half page of one page of transmitted images.

This shows a state in which the partial page has caused a transmission error all three times after the transmission speed has been downshifted to 24008 PS by the downshift procedure of the CTC signal and CTR signal. In this case, since the MCF signal is sent after the third reception of the image information PIX, the image information FIX of the second half page is then transmitted from the transmitting side.

FIG. 6B shows a state in which the image information PIX of the second half page has all been retransmitted for the first time and three times, resulting in an error. Further, FIG. 2C shows a state in which normal reception is achieved in the first retransmission, and in this case, a DCN signal is being transmitted.

In this embodiment, when a transmission error occurs in the final retransmission of a partial page, communication is continued by transmitting an MCF signal, so that one page of images can always be received, and the received image will be less likely to be missing.

On the other hand, if there is a partial page error.

Even if the last reception was normal, the DCN signal is sent, so if the receiving side receives an incomplete image, the sending side may misunderstand that the receiving side sent it normally. It can be prevented.

In the above embodiment, the sending side is notified of the reception error by the DCN signal, but even if there is no data error, the PPR signal is sent and the retransmission request is repeated until the transmission is interrupted. Good too. In this case, if a request for retransmission of the first frame is made using a PPP signal, the transmission side can accept the request.

Furthermore, in each of the above embodiments, the amount of image information per frame is 32 bytes and one line in addition to the standard 256 or 64 bytes.
It goes without saying that any other number of bits or number of lines can be set as desired.

Moreover, although the case where image information is transmitted by ECM has been described in both cases, the present invention is similarly applicable not only to ECM but also to cases where error detection is performed in units of image information of multiple lines.

Furthermore, although the description has been given by taking the case of a facsimile machine using a car telephone as an example, the present invention can of course be similarly applied to a case where a normal telephone line or a wireless device is used. For example, in recent years, facsimile communication using MCA wireless equipment has become popular;
In wireless communication, a time limit such as 1 minute is specified for data communication. Therefore, in such a case, (1) reduce the amount of image information per frame and
As explained in the figure, it is very effective to reduce the data error rate in a short time.

Now, next, a fifth embodiment of the present invention will be described.

FIG. 16 shows a block diagram of the in-vehicle facsimile system of this embodiment. In the figures, the same symbols as in FIG. 1 indicate the same devices or blocks,
The difference from FIG. 1 is that a main image memory 19 and a sub-image memory 20 are provided instead of the image memory 14.

The main image memory 19, like the image memory 14 described above, temporarily stores one block of image information to be transmitted and received. When the image information of an error frame is retransmitted, the sub-image memory 20 saves and stores the previously received image information of the same frame.

With this configuration, the image receiving operation of the facsimile device I will be described next. In this case, the operator
The user then discusses with the sender that the document will be received by telephone, and then presses the receive button on the operation display section 17.

As a result, a predetermined transmission control procedure by the ECM is executed, and one block of data signals in which image information is set is transmitted from the other party.

The frame structure of this data signal is the same as in the first to fourth embodiments described above. That is, as shown in FIG. 17, there is a synchronization signal section in which a large number of flag sequences F are arranged, an encoded information section in which image information is set, and a signal indicating that the image information is finished and a return to the transmission control procedure is performed. It is composed of a return information section.

The encoded information section contains up to 256 frames FCDFO-
FCDFn, and the return information section consists of three frames R.
It consists of CPI to RCP3.

Further, each of the frames FCDFi and RCPi is formed in the data format of an HDLC frame. Frame FCDFi consists of flag sequence F, address field A, control field C
, facsimile control field FCF, facsimile information field PIF, frame check sequence FC3, and flag sequence F.
It is composed of

Among the above fields, all except the facsimile information field PIF and the facsimile control field FCF are 1-byte data. Flag sequence F is used to identify the beginning and end of a frame, and is the data '01111110.'Facsimile communication does not require addressing, so facsimile machines that use a normal telephone line can Address field A is all '''l
I+ data is set.

Control field C indicates the last frame in the encoded information section and return information section, and is set to "11001000" in the last frame, and set to "11000000" in other frames.

The facsimile control field FCF indicates the type of frame and is in the encoded information section.

Information indicating that it is a picture information frame “F CD”
is set, and in the return information section, information "RCP" indicating the end of image information is set.

The facsimile information field PIF is
It is present only in frames of the encoded information section, and a frame number number from 0 to 255 and encoded image information CD of a fixed number of bits, 256 bits or 64 bits, are set. Further, in the case of the final frame FCDFn, all "0" dummy data is set after the image information CD to make the data set with the RTC code the above-mentioned constant bits.

A CRC code for detecting transmission errors in each data of the frame is set in the frame check sequence FC3.

The facsimile machine 1 receives a data signal transmitted from the other party in the above format, and executes a predetermined reception process. This reception process consists of an image information reception process that extracts image information from the data signal and stores it, and a decoding process that reads out the stored image information, decodes it, and records it on recording paper.
This is due to recording processing.

That is, FIGS. 18(a) and 18(b) show the above-mentioned image information receiving process. When the facsimile machine 1 receives the above-mentioned data signal transmitted from the other party (process 501),
), are sequentially stored in a data buffer (not shown). and,
Synchronization is achieved by detecting the flag sequence F of the preamble (processing 502), and the
The LC frame is determined (processing 503).

First, for each frame FCDFi of frames FCDFO to FCDFn, the address field is detected, the control field C is detected, and the information 1FCD of the facsimile information field PIF is detected.
” is sequentially detected (processes 504 to 506), and if each is correctly detected (from Y in process 504, process 505.
From Y in process 505, process 506, Y in process 506), read the frame number NO (process 507).

Next, if it is not the first reception, that is, reception in response to a retransmission request (N in process 508), the image information CD of each frame is taken out and sequentially stored in the main image memory 9 (process 509).

By the way, when data is received in this manner, the reception result of the image information of each frame within one block is stored as error frame data as 256-bit data corresponding to the frame.

At the start of the reception process, all bits of the 256-bit data are set to the "error present" state.

Therefore, each frame is checked for transmission errors using the CRC code of the frame check sequence FC3 (process 110), and if there is no error, the corresponding bit of the error frame data is reset (process 511). Then, the same operation is repeated for the next frame (proceed to process 501). If a transmission error is detected by the above check (N in process 510), the next frame is processed in the same way (proceed to process 501).

When the reception of the encoded information section is completed, the return information section is received. In this case, the information "F CD" is not detected in the facsimile information field PIF, but the information "RCP" is detected. this"
RCP” is detected (from N in process 506, process 5
12° processing 512 Y), each frame RCPI~3
Check the data using the CRC code (processing 51
3).

If there is no error in the data (Y in process 513), next, based on the error frame data, it is determined whether or not there is a transmission error in the received data signal (process 51).
4). If there is a transmission error (Y in process 514)
), it is determined whether a retransmission request is possible (processing 515). If the retransmission request is repeated a preset retransmission limit number of times, the retransmission request becomes impossible, and if the retransmission request is possible (Y in process 515), a PPR signal is sent to the other party,
Requesting retransmission of the error frame (processing 516);
The next data signal to be retransmitted is received (proceed to process 501). Furthermore, if there is no error frame (N in process 514), the reception routine is ended.

On the other hand, if address field A or control field C is not detected in each frame FCDFi (N in process 504, N in process 505), and if the information "RCP" is not detected (N in process 512), then The detection state up to that point is cleared (processing 517), and the process returns to data signal reception (proceeding to processing 501). Further, if an error is detected in frames RCP 1 to 3 (N in process 513), the process similarly returns to data signal reception (proceeds to process 501). Note that due to such various detection errors, the final frame of one block may not be correctly identified, and the reception state may be held in the old process 5.

In this case, a timer routine (not shown) is provided, and if a data signal is not received for a certain period of time, processing 5
Processing starts from step 14.

As a result, if address field A and control field C are not detected, the bit of the corresponding frame of error frame data remains set to the "error present" state. In addition, the said information “RCP
” is not detected, or frame RCPI~3
Even if an error is detected, if the previous block of image information has been received normally without errors,
The image information becomes valid.

As a result of the above receiving operation, the image information f0 to fo of each received frame of one block is stored in the main image memory 19, as shown in FIG. 19(a).

Now, if a transmission error is detected in the image information f and f2, a request is made to retransmit the frame, and the frame is retransmitted from the other party.

The retransmitted data signal of one block is received in the same manner as above, and the information "F CD" is detected (processing 50).
6), the frame number is read (processing 5o7). In the case of reception by retransmission (Y in process 508), it is determined based on the error frame data whether the read frame number matches the frame number requested for retransmission (process 518).

Here, if both match (Y in process 518),
The storage position of the image information corresponding to the frame number in the main image memo IJ19 is determined (processing 519). Next, the previous image information previously stored in that position is transferred to the sub-image memory 20 (process 120).

Then, the image information received this time is stored in the storage location of the main image memory 19 (processing 121) - After this, similarly to the above, an error frame data is set as necessary by checking the error of the received image information. (Processing 1
to 50).

On the other hand, if the read frame number does not match the frame number requested for retransmission (N in process 518), the image information is not extracted and the detection result is returned to the initial state (proceed to process 517). This is because the frame number data is considered to be in error, and in this case, the retransmission operation etc. will be executed again.

As a result, as shown in FIG. 19(b), the error frame requested for retransmission is retransmitted, the previous image information f□ and f2 are transferred to the sub image memory 20, and the first image information received this time is The retransmission image information f-' and f-' are stored at predetermined positions in the main image memo January 4.

Here, if there is another transmission error in the currently received image information f' and f2I, a similar retransmission request is made again and the second retransmitted image information f' and f2 are received.

At this time, if there is a transmission error in the image information f□'', the third retransmission image information f'' is received.

As a result, as shown in FIG. 3(c), the sub-image memory 20 stores each image information f0. f2. f□l
f2'lf4'' are stored in sequence.

Assuming that the number of retransmissions is currently limited to three, it is determined that subsequent retransmission requests are impossible (N in process 515).
The retransmission process is aborted.

When the execution of the above image information reception routine is completed, next
The image information decoding/recording process shown in FIGS. 20(a) and 20(b) is executed.

That is, first, image information f1 to fn of each frame stored in the main image memory 19 is sequentially read out (processing 60).
1).

By the way, an EOL code indicating a break is added to the image information for each line. Further, for example, if it is assumed that the image information is encoded using the MI-1 (Modified Huffman) method, the image information is composed of a makeup code and a termination code.

Therefore, next, we will introduce the EOL that indicates the beginning of one line of image information.
A code is detected (process 602). Then, when an EOL code is detected (Y in process 602), the subsequent encoded image information is determined in units of the above-mentioned codes,
The data is sequentially decoded by code conversion according to the set code table (processing 604).

Next, referring to the error frame data, it is determined whether the frame 11 of the image information currently being decoded is an error frame (processing 605). Here, if it is not an error frame (N in process 605), the next code of the image information is determined (process 606), and if it is not an EOL code (N in process 606), the above decoding is repeated (process 6
to 04).

When the decoding for l lines is completed, the next IEO
L code is detected. Note that the RTC code indicating the end of 51 blocks of image information is six consecutive EOL codes, so when the above EOL code is detected (Y in process 606), it is determined whether it is not an RTC code (process 607). ).

Here, if it is not an RTC code (N in process 607)
, the image information of the I line decoded by the plotter 12 is recorded on the recording paper (process 6o8), and the next line is processed in the same way (proceed to process 604).

In the example shown in FIG. 19(c), the image information f. teeth.

Since it was not an error, by the above operation, first,
The received image of the frame is recorded.

Further, in this example, the image information f″' of the next first frame is in error. The error in the image information occurs in the EOL code, makeup code, termination code, etc.

Therefore, during the decoding, the following cases are determined to be 5 data errors. In other words, when each code above is an undefined bit pattern,
When makeup codes are continuous, when there is an EOL code after the makeup code, or when decoding one line of image information sandwiched between EOL codes, the predetermined constant number of bits cannot be obtained. Such as time.

Therefore, after the above decoding (process 604), if it is an error frame (Y in process 605), the presence or absence of a data error is determined as described above (process 609), and if it is not a data error (N in process 609) , is processed in the same manner as above (proceed to process 606).

By the way, in this embodiment, as shown in FIG. 19(C), when image information is received by retransmission, the received image information is stored in the sub-image memory 20 each time.

Therefore, if there is a data error in the decoding (Y in process 609), it is determined whether the image information of the frame is stored in another memory location (process 610).
).

In this embodiment, the image information "f" stored in the main image memory 19 is currently being decoded, but the sub-image memory 19
0 stores image information f□, f', f''' of the frame.

In this way, if there is other image information of the same frame (Y in process 610), for example, as shown in FIG. (processing 611).

At this time, if an error in each code is detected in the memory area before switching, as shown in Figure 22, in the memory area after switching, the reading start address is set so that reading starts again from the same code. Set. Also, if a predetermined constant number of bits cannot be obtained by decoding the image information sandwiched between EOL codes,
Set the read start address so that reading starts again from the previous EOL code (process 612)
.

Then, decoding and recording are performed in the same manner as above (process 60
4).

As a result, each time an error is detected, another image information is read and processed, for example, if another error is detected in image information f, then image information f is read and processed. . Also, if an error is detected in the image information f□″,
Return to image information f again.

In this case, if the same code or the same line is in error in each of the image information f□ to f, III, the memory area will be switched by -, but after that, there will be no other memory area to switch to.

In this case (N in process 610), image information for one line of the white image is created (process 613), and image information for one line up to the next EOL code is created (process 614).

As a result, if the same line has an error in all the image information f--f□''', a white line will be recorded.

In this way, the image information f-f1 of each frame is recorded, and when the RTC code is detected (Y in process 615),
The recording paper on which the received image has been recorded is cut and ejected, and the above process ends (process 615).

On the other hand, in the above, the first EOL indicating the start of image information
If the code is not detected (N in process 603), and if there is other image information for the same frame (Y in process 616), the memory area is switched to read out that image information ( Process 617), and the process continues (to process 602). Furthermore, if all of the - ways of switching are errors (N in process 616), this process is canceled.

As described above, in this embodiment, when image information is received by requesting retransmission, all previously received image information with errors is also stored in each memory area. and,
If an error is detected while sequentially decoding and recording the received image information, the system switches to another memory area.

In this case, transmission errors in the image information received each time usually occur at different bit positions. Therefore,
Switching to another memory area means that correct data can be retrieved, so image information can be sequentially decoded and recorded, and the occurrence of missing and shortened received images is reduced.

Note that in this embodiment, if an error is detected during decoding,
Although switching is performed sequentially to each memory area, it is also possible to use one memory area as a reference and compensate for an error portion in that memory area with data from another memory area.

Next, a sixth embodiment of the present invention will be described.

In this embodiment, the transmitting side is the same as in the fifth embodiment described above, and FIG. 23 shows the processing on the receiving side in this case.

That is, when the receiving side receives the data signal (processing 7
01), as in the case of Figs. 18(a) and (b), HD
Each field of the LC frame is determined and the transmitted image information is extracted (processing 702).

Then, as in the above embodiment, if the reception is not due to a retransmission request (N in process 703), the received image information is stored in the main image memory 19 (process 704). In addition, in the case of reception due to a retransmission request (Y in process 703), after the image information of the same frame received last time is transferred to the sub-image memory 20 (process 705), the image information of the frame received this time is transferred to the main image memory 19. It is stored in a predetermined area (process 704).

As a result, as shown in FIGS. 19(a) to (c),
All received image information of each frame is stored.

Next, check the transmission error of the image information of the received frame using the CRC.
Check from the code (processing 706). Here, if there is no error (Y in process 706), the received one block of image information is sequentially decoded from the first frame (process 70
7) Record the received images sequentially on recording paper (process 708)
.

On the other hand, if there is a transmission error in the image information of the received frame (N in process 706), the number of times the image information of the frame has been received is checked (process 709). Here, if the number of receptions is less than three times (N in process 709), the PPR
A signal is sent to request retransmission (process 710), and the data signal of the frame is received again (proceed to process 701).

Here, as in the above embodiment, image information f of frame 1
□ resulted in an error and the image information was resent 1. It is assumed that both the "f" and "f" also result in an error.

In this way, if an error frame is received three or more times (Y in process 709), image information f1. f□' and f1'''' are read out, and as shown in FIG. 24, each bin is compared one by one. Then, for bits that match all three, the value is set as the corrected image information cf□, and for bits that do not match, it is estimated whether +1011 is II II II by majority vote, and this is set as the estimated image information cf (processing 711).

Next, this estimated image information cf is checked using the received CRC code (processing 712). Then, if there is no error, it is decrypted and recorded (to process 707),
If there is an error, a retransmission request is made (process 71o), and the same is received (proceed to process 701).

As a result, after the first and fourth image information f□'' is received, estimated image information cf1 is similarly created by majority vote using the three pieces of image information f1' to f-work''.

Then, if the error is no longer present, it will be recorded.

As described above, in this embodiment, a retransmission request is made and the image information is
When the frame is received more than once, the value of each bit of the image information of the frame is determined by majority vote based on the bits received each time, and 11 estimated image information is created.

Therefore, for example, when retransmission is aborted after a certain limit number of times, accurate estimation can be made as long as the same bits of image information in the past three times are not in error. As a result, as in the embodiment described above, it is possible to reduce the occurrence of missing and shortened received images.

In the above embodiment, the majority decision process is performed every three times, but this may be done any number of times.
After the final retransmission has been performed for the limited number of times, the majority decision process may be performed using all the image information that has been received up to that point. Further, although the estimated image information created by majority vote is checked using a CRC code, since the CRC code may have an error, it is also possible to similarly estimate the CRC code received each time by majority vote.

Furthermore, in each of the above embodiments, a case has been described in which image information is transmitted by ECM of the G3 standard.

Not limited to ECM, when retransmitting the same image information,
The invention is equally applicable.

[Effects of the Invention] As described above, according to the present invention, as a first means, when an error in image information data within one data frame is detected when it is impossible to execute a retransmission request, The presence or absence of data errors is detected for each line of image information data in a data frame, and image information without data errors is recorded for each line. Shortening of recording paper length can be reduced.

In addition, as a second method, we set image information data in an amount smaller than the normal amount of data in one data frame, so even if an entire frame has an error, the same method as above can be applied. In addition to being effective, the data error rate at the time of aborting retransmission can be reduced.

In addition, as a third method, when one page of a manuscript is divided into multiple blocks and sent, one block is received, the retransmission is repeated, and the next retransmission request cancels the final retransmission. , and if that block is not the final image information of one page, the retransmission request is not made even if a data error is detected, so the entire page can always be received, and there will be no missing images in the received image. becomes less. Furthermore, in this case, after receiving the entire page, the receiving side always notifies the sending side of the error, thereby preventing the sending side from misunderstanding that the transmission was successful.

Furthermore, as a fourth means, all received image information is stored each time, and if retransmission is aborted due to a transmission error, the error 311 data is extracted from the image information each time, so it is the same as above. It is possible to reduce the occurrence of dropouts and shortening of received images. In addition, as a means of extracting the error-free data, each bit of the image information data of each time is collated and the correct data is estimated by majority vote, so it is possible to reproduce the correct image information data with a simple method. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of an in-vehicle facsimile system according to a first embodiment of the present invention, FIG. 2(a) is a frame configuration diagram of an image information frame, and FIG. 2(b) is an explanatory diagram of image information.
3(a) and 3(b) are operation flowcharts showing recording processing on the receiving side, FIG. 4 is an explanatory diagram of received images, and FIG. 5 is a procedure signal at the start of communication in the second embodiment of the present invention. FIG. 6 is an operational flowchart of the transmission process in the embodiment, FIG. 7 is an explanatory diagram of image information in the embodiment, and FIG. 8 is a flow chart of the reception process in the embodiment.
) and (b), FIG. 9 is an operational flowchart I~ of retransmission processing in the embodiment, and FIG. 10 is an explanatory diagram of a received image in the embodiment. FIG. 11 is a graph showing the relationship between communication time and data error rate, FIG. 12(a) is an explanatory diagram showing data stored in the image memory in the third embodiment of the present invention, and FIG. An explanatory diagram showing storage information when image information is stored in the image memory in the embodiment, FIG. 13 (C) is an explanatory diagram of the image information in the embodiment, and FIG. 14 is an operation flowchart showing the response processing on the receiving side in the fourth embodiment of the present invention, and FIG. 15 is an example of the transmission procedure in that embodiment. FIG. 16 is a block configuration diagram of an in-vehicle facsimile system according to a fifth embodiment of the present invention, FIG. 17 is a frame configuration diagram of a data signal that transmits image information in this embodiment,
FIGS. 18(a) and 18(b) are operation flowcharts showing image information reception processing in the embodiment, and FIGS. 19(a) to
FIG. 20(C) is an explanatory diagram showing the storage state of image information of each frame in the image memory in the embodiment, and FIG. 20(a). (b) is an operation flowchart showing the image information decoding/recording process in the embodiment, FIG. 21 is an explanatory diagram showing the memory area switching operation of the image memory in the embodiment, and FIG. 22 is an operation flowchart showing the memory area switching operation of the image memory in the embodiment. An explanatory diagram showing the readout position of the next image information, FIG. 23 is the sixth embodiment of the present invention.
Operation flowchart of reception processing in the embodiment, second
FIG. 4 is an explanatory diagram showing the majority decision processing of image information in this embodiment, FIG. 25(a) is an explanatory diagram of the original image and image information, and FIG. It is. ■...Facsimile device, 2...Interface device, 3...Car telephone device, 4...Handset, 1
DESCRIPTION OF SYMBOLS 1... Scanner, 12... Plotter, 13... Encoding/decoding section, 14... Image memory, 15... Modem, 16... Communication control section, 17... Operation display section, 18
...System control unit, 19...Main image memory,
20...Sub image memory. Figure (b) Figure (a) Figure f+ (32 heights) Figure Ma-onj! To 105 Figure Figure Figure Texture +05 Figure 18 Figure 19 Figure 18 Figure □ Wa Figure 20 (o) Sky Figure 20<b) Figure 22 7' Figure 28 Figure 24 Figure 25 Figures (a) (b) ■-f

Claims (6)

[Claims] (1) Receive a data signal in which multiple lines of image information data of a document image and an error detection code for the image information data are set in one data frame, and detect errors in the image information data in the data frame. Then, it is determined whether or not a retransmission request can be made to the sending side, and if the retransmission request is possible, the facsimile machine receives the retransmission of the image information data of the data frame from the sending side. If an error is detected in the picture information data in the data frame, a line error detection means detects the presence or absence of a data error for each line of picture information data in the data frame, and A facsimile apparatus comprising: line recording means for recording information data line by line. (2) When communicating over a line where errors in the image information data are likely to occur, the sending side of the data signal sets a smaller amount of image information data than usual in one data frame and transmits the data signal. 2. The facsimile machine according to claim 1, further comprising a transmitting means for transmitting a message. (3) Receive the data signal of each block in which the image information of one page of the original image is divided into multiple partial pages and set, and each time a block is received, image information in which a data error has been detected is sent to the sending side. On the other hand, if a retransmission request is made and the image information is retransmitted, but if a retransmission request is made a certain number of times under certain conditions, the transmission of the data signal will be stopped.After receiving the one block of data signal, the facsimile machine will stop transmitting the data signal due to a data error. a counting means for counting the number of times the image information has been retransmitted; a determining means for determining the final retransmission at which transmission will be stopped when the next retransmission request is made; Manuscript image 1
1. A facsimile apparatus comprising: a control means for proceeding to receiving a data signal of the next block without requesting retransmission even if a data error is detected if the image information is not the last image of the page. (4) If no retransmission request is made even if the above data error is detected, when the data signal of the last image information block is received, the sending side will receive a reception error even if no data error is detected. 4. The facsimile machine according to claim 3, further comprising means for notifying the user of the fact. (5) When receiving one block of data signal transmitted with encoded image information set in each data frame in a fixed format, and detecting a transmission error in each data frame, a retransmission request is made to the transmitting side. , in a facsimile device that receives the retransmission of the data signal of the data frame and, when the data signal is retransmitted up to a set limit number of times, terminates reception of the data signal of the one block even if there is a data frame in which a transmission error remains. ,
An image information storage means for storing all the image information taken out each time the data signal is received at least until it is recorded on a recording paper, and data in which a transmission error remains when reception of the one block of data signals is discontinued. An image information reading means for sequentially reading out error-free image information data from the image information of each time stored in the frame; an image information decoding means for decoding the read image information data; 1. A facsimile device comprising: image recording means for recording image information on recording paper. (6) When receiving one block of data signal transmitted with encoded image information set in each data frame in a fixed format and detecting a transmission error in each data frame, a retransmission request is made to the transmitting side. , in a facsimile apparatus that receives the retransmission of the data signal of the data frame, image information storage means for storing all the image information taken out each time the data signal is received at least until it is recorded on recording paper; and retransmission of the data signal. image information estimating means for estimating correct data by majority vote by comparing each bit of the image information data of each of the above-mentioned times of the data frame if there is a data frame in which a transmission error remains after receiving the image information a certain number of times or more; 1. A facsimile apparatus comprising: image recording means for recording image information obtained by estimation on recording paper.