JP3162777B2 - Facsimile transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a facsimile transmission method.
More particularly, the present invention relates to a facsimile transmission method for retransmitting image information of an error page when a transmission error of image information occurs between facsimile terminals that are directly transmitted from a transmission terminal and the reception terminal does not have an error correction function.

[0002]

2. Description of the Related Art Conventionally, a facsimile apparatus used in a public telephone network has been recommended and standardized by CCITT (International Telegraph and Telephone Consultative Committee). When transmitting a transmission original by facsimile, the transmission terminal reads and transmits transmission image information, and the reception terminal directly records and outputs the reception image from a plotter or the like. For this reason, it is necessary to synchronize the processing speed of the facsimile between the two terminals, and image information is normally transmitted by matching the processing speed of the terminal with the higher processing speed with the terminal with the lower processing speed.

If a transmission error occurs during transmission of a plurality of transmission originals, the transmission terminal cannot determine which transmission original has been transmitted properly.
Since it is necessary to contact the operator of the receiving terminal over the telephone to specify the original to be resent and to perform the transmission operation again, it has been very troublesome. Therefore, in recent facsimile machines, like SAF (Store And Forward) memory,
A large-capacity image memory is provided, and the transmission image information is temporarily stored in this image memory and then transmitted to the receiving terminal. It is not always necessary to synchronize the processing speed, and the transmission time can be reduced by adjusting to a terminal having a high processing speed.

If a transmission error occurs during transmission, since the transmission image information is stored in the image memory of the transmission terminal, it is necessary to read the transmission image again and transmit the transmission image information. It has the advantage of being lighter. For example, the facsimile transmission method described in JP-A-61-278272 has an image memory,
By storing the image information to be transmitted in the image memory and transmitting it to the other party at the same time, the overall transmission time is shortened.

[0005]

As described above, in the conventional facsimile transmission method , when the transmission original is directly transmitted to the other party while reading the transmission original without using the image memory, there is no accumulation of transmission data on the transmission terminal side. Therefore, when a transmission error occurs, it is necessary to transmit the error page of the transmission original again, and there is a problem that it takes much time and effort.

Further, when the receiving terminal does not have an error correction function (hereinafter, also referred to as a non-ECM device), there is a problem that even if a transmission error occurs, there is no means for correcting the transmission error. The present invention has been made in view of such conventional problems, and is directed to a receiving terminal having no error correction function.
Facsimile transmission where the transmitting terminal transmits image information directly
It is an object of the present invention to provide a facsimile transmission method capable of retransmitting transmission data when a transmission error occurs without adding hardware .

[0007]

According to the first aspect of the present invention,
The transmitting terminal has an error correction memory for performing error correction,
The transmitting terminal scans the original image and converts it into image information, encodes the image information, transmits it to the other party via the transmission image memory, and receives it at the receiving terminal that does not have an error correction function. In the facsimile transmission method, the error correction memory and the transmission image memory are initialized, and image information for each page of the transmission original read by the scanner is encoded and temporarily stored in the transmission image memory.
Send sequentially counterpart while accumulating on, the error correction menu
Memory as a memory for retransmission without using the error correction method.
Using the coded data in the empty area of the error correction memory.
The image information is stored, and when the image information transmitted to the receiving terminal results in a transmission error, the image information stored in the error correction memory of the transmitting terminal is retransmitted.

According to a second aspect of the present invention, in the case where image information read and encoded by the scanner is written into the transmission image memory, fill bits are inserted as necessary and written into the error correction memory. Is characterized in that no fill bit is inserted. According to a third aspect of the present invention, when the transmission error is detected and the image information stored in the error correction memory is retransmitted, if the encoding method is the same between the direct transmission and the retransmission, the error correction is performed. The end of the line of the coded data stored in the memory is detected, a fill bit is inserted and retransmitted, and when the coding method differs between direct transmission and retransmission, once the desired data is decoded and the desired It is characterized in that it is encoded by a method and retransmitted.

[0009]

According to the first aspect of the present invention, when the image information is directly transmitted to the other party, the image information read by the scanner is written to the transmission image memory and transmitted to the other party, and the receiving terminal is a non-ECM machine. Does not use an error correction memory, and by using this, image information can be stored for each page. Therefore, transmission data can be stored in the memory without newly adding hardware, and when a transmission error occurs, a request for data retransmission can be made using the error correction memory. Further, since the image memory is not used in the present invention, the image memory is not occupied, and the image memory is not affected by the data storage state or the like.

According to the second aspect of the present invention, when storing encoded image information in the transmission image memory, a fill bit is inserted as necessary, and when storing the encoded image information in the error correction memory, the fill bit is inserted. Not inserted. Therefore, the error correction memory can be used effectively, and overflow of the error correction memory can be reduced.

According to the third aspect of the present invention, when the encoded image information stored in the error correction memory has a different encoding method between direct transmission and retransmission, the image information is temporarily stored. After decoding and re-encoding, when the encoding method is the same, fill bits are inserted while detecting line breaks from the line end code (EOL). Therefore, when the encoding method is the same, decoding can be omitted, and the processing speed is improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. First, the configuration will be described. FIG. 1 is a block diagram of a facsimile apparatus according to one embodiment of the present invention. In the figure,
An NCU (network control unit) 1 is connected to a public telephone line L,
A predetermined line control is performed when making and receiving calls, and includes a modem for modulating and demodulating an image signal for transmitting and receiving data between facsimile apparatuses connected via the line.

The operation panel unit 2 displays the operation state of the apparatus and allows the operator to perform various operations. The DCR (encoding / decoding unit) 3 compresses the image information to be transmitted and restores the received image information to the original image information. RAM (Random Access Me
mory) 4 stores data such as the telephone number and name of the other party when registering a one-touch dial or abbreviated dial of the facsimile apparatus, and stores an ID code for shifting to various modes.

A ROM (Read Only Memory) 5 stores a program for executing a sequence of the facsimile machine. CPU (Central Processing Unit)
6 executes a sequence of the entire facsimile apparatus according to a program stored in the ROM 5.
FIFO (First In First Out) memory 7
For sending images to facilitate data input / output via
And temporarily stores the image information encoded by DCR3.
And outputs them sequentially to the NCU 1 .

ECM buffer ( memory for error correction ) 8
Is a memory used when executing the error correction method. In the present embodiment, the receiving terminal of the non-ECM
The ECM buffer 8
By storing the image information in the area, the ECM buffer 8
Is used as retransmission memory regardless of the error correction method.
It has become so. SAF memory (image memory) 9
Are usually divided into small blocks of about 2 KB units and managed by connecting chains. The SAF memory 9 is
Store all image information to be sent to the other party before sending.
All images sent from the other party and received from the other party
Memory reception to read out only necessary information after accumulating information
Is what you do. Note that the direct transmission in this embodiment is
Does not transmit the memory using the SAF memory 9 and
The image information encoded by CR3 is temporarily stored in the FIFO memory 7.
Image information by successively storing and sequentially outputting to NCU 1.
What to send.

The line buffer 10 sequentially sends the read document image information to the DCR 3 while storing the read document image information in line units. The scanner 11 reads a facsimile transmission original image and converts it into image information. The plotter 12 records the received image on a recording sheet.

The system bus 13 is a signal line through which the above-mentioned units exchange various control signals and data with each other. The operation of the present embodiment based on such a configuration will be described below. First, when the operator selects the direct transmission in which the original image is read by the scanner 11 and the image information is directly transmitted to the other party, the original is set on the scanner 11 and the facsimile number of the other party is input on the operation panel unit 2. A calling operation is performed from the NCU 1. Here, whether or not the receiving terminal (not shown) is a non-ECM device having no error correction function is determined on the transmitting terminal side by a digital identification signal (DIS) or a non-standard function identification signal (NSF) from the receiving terminal. be able to.

If the receiving terminal is a non-ECM machine,
Since the facsimile transmission procedure by the method cannot be used, the encoding shown in FIG. FIG. 2 is a flowchart showing encoding of the facsimile apparatus according to one embodiment of the present invention, FIG. 3 is a flowchart of one-line encoding of FIG. 2, and FIG. 4 is a flowchart of a subroutine A used in FIGS. FIG. 5 is a flowchart of a subroutine B used in FIGS. 2 and 3, and FIG. 6 is a flowchart in a case where an encoding method is different between direct transmission and retransmission of image information. FIG. 7 is a flowchart when the encoding method and the like are the same between the time of direct transmission of image information and the time of retransmission.

First, the scanner data read by the scanner 11 is transferred to the line buffer 10 line by line, then sent to the DCR 3 where it is encoded and stored in the FIFO memory 7 in order. The memories used at this time are the RAM 4, the line buffer 10, and the FIFO memory 7 shown in FIG. In the case of the present embodiment, direct transmission is selected and the receiver is a non-ECM device, so the SAF memory 9 and the ECM buffer 8 are not used.

Conventionally, in the case of memory transmission, this SAF
Although the image information was transmitted using the memory 9, the SAF memory 9 may have stored image information such as other received originals, and the SAF memory generally has a small block of about 2 KB. There is a problem that it is difficult to handle because it is divided and managed by connecting chains. For this reason, the present inventors have paid attention to the fact that the ECM buffer 8 is not used when the receiving terminal is a non-ECM device,
The ECM buffer 8 is normally vacant for two blocks and at worst one block, and one block is about 64 KB.
Since the addresses can be accessed continuously, it was found that handling was very easy.

Therefore, as shown in the flowcharts of FIGS. 2 and 3, the encoding procedure of this embodiment includes a subroutine A (FIG. 4) for writing data to the ECM buffer, and a write address of the ECM buffer. Is performed while appropriately calling a subroutine B (FIG. 5) for initializing
Stored in the O memory 7 and transmitted to the other party,
The image information stored in the M buffer 8 is also stored, and when a transmission error occurs, the image information stored in the ECM buffer 8 is read out and retransmitted.

As shown in FIG. 2, the specific encoding procedure is to initialize the address of the FIFO memory 7, clear the line buffer 10, and initialize the DCR 3 in step 100, as shown in FIG. The subroutine B shown is called, and the address of the ECM buffer 8 in step 400 is initialized. Next, in step 101, the scanner 11 is started to start reading a document image,
In step 102, it is determined whether or not there is data in the line buffer 10. If one line of data is stored in the line buffer 10, at step 103
Line coding is performed.

FIG. 3 details the procedure of this one-line encoding. As shown in FIG.
At 0, the line end code (EOL) is stored in the FIFO memory 7, and the subroutine A is called. The subroutine A stores predetermined data in the ECM buffer 8 as shown in FIG. In this embodiment,
There are two blocks of ECM buffer, one of which is the first EC
An M buffer is used, and the other is called a second ECM buffer. Therefore, in step 300, it is determined whether or not there is a free space in the first ECM buffer.
Data (here, EOL) is written to the ECM buffer, and the address of the first ECM buffer is incremented (+1). If there is no free space in the first ECM buffer, it is determined in step 303 whether or not there is free space in the second ECM buffer. If it is free, data (EOL) is written in step 304 and the address is incremented in step 305. In step 303, the second E
If there is no room in the CM buffer, the overflow flag is set in step 306, and it is found that there is no room in all ECM buffers.

Returning again to step 200 in FIG.
OL is stored in both the FIFO memory 7 and the ECM buffer 8. Next, at step 201, a0
By color initialization, the first color is set to white, and in step 202, encoding of image information is started by DCR3. In this encoding, two-dimensional mode detection is performed in step 203, or run-length detection is performed in the case of one dimension, and the encoded code is stored in the FIFO memory 7 in step 204. Then, here, the subroutine A is called to store the encoded code in the ECM buffer 8 as well. In step 205, the a0 color is inverted.
In step 206, it is determined whether the encoding for one line has been completed. If the encoding for one line has not been completed yet, the process returns to step 202 and the above encoding procedure is repeated.

After the encoding of one line is completed in step 206, the necessity of a fill bit is determined in step 207.
If necessary, the fill bit is stored only in the FIFO memory 7. In this case, the subroutine A is not called and the ECM
No fill bit is inserted into the buffer 8. this is,
The fill bit is necessary only when transmitting data, and the data to be stored in the ECM buffer is used so that the fill bit is not written and the memory area is effectively used.

As described above, when the encoding for one line in step 103 in FIG.
At 04, the presence or absence of the next line is determined, and if there is the next line, the above-described encoding is repeated for each line.
If there are no more lines to read, the control return symbol (RTC) is stored in the FIFO memory 7 in step 105, and the subroutine A is called to store the RTC in the ECM buffer 8 as well.

After the encoded image information has been transmitted to the other party and a transmission error is detected on the receiving terminal side, the receiving terminal sends a retraining denial signal (RT
N) to the transmitting terminal to request retransmission of image information. When the transmitting terminal receives this RTN signal, the encoded image information stored in the ECM buffer 8 is read and retransmitted.

FIG. 6 is a flowchart showing an encoding procedure when the encoding method and the like are different between the direct transmission and the retransmission when retransmitting the image information. FIG. 7 is a flowchart showing the encoding procedure when the image information is retransmitted. 10 is a flowchart illustrating an encoding procedure when the encoding method and the like are the same at the time of retransmission. In the case of FIG. 6, the encoding method , original size,
This is the case when the linear densities are different. First, in step 500, the address of the FIFO memory 7 is initialized, the line buffer 10 is cleared, and the DCR 3 is initialized. Next, in step 501, one line of the encoded image information stored in the ECM buffer 8 is read, and
And stored in the line buffer 10. In step 502, the presence or absence of data in the line buffer 10 is determined. If there is data, in step 503, one line is encoded by the DCR3 by a predetermined encoding method . Then, in step 504, the presence or absence of the next line is determined, and the above encoding is repeated until there is no more line.
Then, in step 505, the control return signal (RTC) is stored in the FIFO memory 7, and the encoding is completed. This encoded image information is retransmitted to the receiving terminal. In the case of FIG. 6, since retransmission is performed, the subroutines A and B are not called unlike the encoding of FIG.

In the case of FIG. 7, the encoding method , the original size, and the line density are the same at the time of direct transmission and at the time of retransmission. First, in step 600, the address of the FIFO memory 7 is initialized. In step 601, data in the ECM buffer 8 is read. In step 602, the presence or absence of a line end code (EOL) is searched for a line break. If there is no EOL in step 603, the EOL is stored in the FIFO memory 7 as it is, and the processing is continued until the EOL is found. If there is an EOL at step 602, control return signal (RTC) is sent at step 604.
The presence or absence of a fill bit is determined in step 605, and the necessity of a fill bit is determined.
The specified number of fill bits are stored in the O memory 7, and if not necessary, the EOL is stored in the FIFO memory 7 in step 607 without storing the fill bits, and the process returns to step 601 to read the data in the ECM buffer 8. Repeated. If the RTC is detected in step 604, the RTC is stored in the FIFO memory 7 in step 608, and the encoding ends.

[0030]

According to the first aspect of the present invention, since the image information to be transmitted is left in the ECM buffer even at the time of direct transmission, even if a transmission error occurs, it can be easily retransmitted. When the receiving terminal is a non-ECM device, since the ECM buffer of the transmitting terminal is not used, the image data to be transmitted is stored using the ECM buffer, so that the transmission data can be transmitted without newly adding hardware. Can be stored in the memory, and it is possible to respond to a data retransmission request when a transmission error occurs. Further, since the image memory is not used in the present invention, it is hardly affected by the occupation of the image memory and the data storage state of the image memory.

According to the second aspect of the present invention, when the encoded image information is stored in the ECM buffer, no fill bit is inserted, so that the ECM buffer can be used effectively and the ECM buffer overflows. Can be reduced. In the invention of claim 3, wherein, directly if the transmission time and having different coding methods and retransmission is again encoded from the temporarily decoded image information, coding side
If the method is the same, the EOL of the encoded data is searched to detect a line break, and a fill bit is inserted.
Decoding can be omitted, and processing speed can be improved.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing encoding of the facsimile apparatus according to one embodiment of the present invention.

FIG. 3 is a flowchart of one-line encoding of FIG. 2;

FIG. 4 is a flowchart of a subroutine A used in FIGS. 2 and 3;

FIG. 5 is a flowchart of a subroutine B used in FIGS. 2 and 3;

FIG. 6 is a flowchart in a case where an encoding method and the like are different between direct transmission and retransmission of image information.

FIG. 7 is a flowchart in a case where an encoding method and the like are the same at the time of direct transmission and retransmission of image information.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 NCU 2 Operation panel part 3 DCR 4 RAM 5 ROM 6 CPU 7 FIFO memory (memory for transmission image) 8 ECM buffer (memory for error correction) 9 SAF memory (image memory) 10 Line buffer 11 Scanner 12 Plotter 13 Data bus

Claims (3)

(57) [Claims] A transmission terminal has an error correction memory for performing error correction, a transmission original image is read by a scanner on the transmission terminal side, converted into image information, and the image information is encoded and transmitted. A facsimile transmission method for transmitting to the other party via a receiving terminal having no error correction function and initializing the error correction memory and the transmission image memory, and transmitting the original read by the scanner. The image information for each page is encoded and temporarily stored in the transmission image memory.
From the error correction memory for retransmission without using the error correction method.
In the empty area of the error correction memory
Storing the encoded image information, and retransmitting the image information stored in the error correction memory of the transmitting terminal when the image information transmitted to the receiving terminal side becomes a transmission error. Facsimile transmission method. 2. A facsimile transmission method according to claim 1, wherein fill bits are inserted as necessary when writing image information read and encoded by said scanner into said transmission image memory. A facsimile transmission method , wherein a fill bit is not inserted when writing to the error correction memory. 3. The facsimile transmission method according to claim 2, wherein when the transmission error is detected and the image information stored in the error correction memory is retransmitted, a direct transmission and a retransmission are performed. If the encoding method is the same, and detects the line end part of the encoded data of the error correction memory, by inserting a fill bit retransmits encoding method is different between the time of transmission directly and at retransmission In this case, the facsimile transmission method is characterized in that the data is once decoded and then coded by a desired method and retransmitted.