JP2689745B2 - Coded data transmission processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method of transmitting and processing image data read and encoded from a transmission original in a facsimile machine.

[0002]

2. Description of the Related Art Facsimile devices capable of transmitting and receiving image information via a telephone line have been developed and used, but in such a facsimile, the data length is shorter than the original image data. In order to reduce the transmission time, as shown in FIG. 8, the image data for one line read from the transmission original is decomposed into run lengths (a continuous length of white pixels or black pixels), and Table 1 The A-bit data obtained by encoding the image data in accordance with the encoding table shown in (1) is transmitted to the receiving side.

[Table 1]

By the way, when transmitting image data,
For example, when the image data of one line is all white pixels, the make-up code (00000011) of the white run length 1728 is added to the EOL code (code represented by 000000000001 to distinguish the lines) in Table 1.
00101) is added and transmitted to the receiving side, but when the receiving side has only a reception buffer memory with a small capacity, the transmitted encoded data is decoded into the original image data and printed, and the sub-scan is performed. Even while the process is being performed, encoded data is accumulated in the reception buffer memory one after another, and printing and sub-scanning cannot catch up with reception. In order to avoid such an inconvenience, CCITT (International Telegraph and Telephone Advisory Committee) has a minimum transmission time Tmin (minimum data length Lmi) for transmitting encoded image data of one line.
n) is defined, and when the encoded data length of one line is shorter than the minimum data length Lmin, dummy data called a fill signal (consisting of 0 signals) is added by the difference data. By transmitting the data as described above, the time is secured so as not to hinder the sub-scan on the receiving side.

By the way, in order to send such coded image data to a telephone line through a modem, it is usually necessary to use the method shown in FIG.
As shown in FIG. 5, a modem buffer M (in the figure, it is configured to store each byte) for temporarily storing the image data to which the EOL code and the fill signal necessary for the encoded data are added for each line, The data is written in the modem buffer M by being arranged between the encoding circuit and the modem.
0 to 1002), the operation of incrementing the instruction address of the write pointer every time 1-byte data is written to the instruction address of the write pointer is repeated until the write data is completed.
0 (B) flowchart (steps 2000, 20
01), 1-byte data is read from the read pointer instruction address and sent to the line, and the interrupt processing operation of incrementing the read pointer instruction address is repeated until the read data is completed. It has become.

However, in the above-described data writing process, the required number of dummy data must be written by software after the encoded data, and the shorter the encoded data, the more dummy data should be added. Since it increases, it takes time to add the dummy data, and the processing speed cannot be increased.

[0006]

In the method of the present invention proposed in view of the above circumstances, the encoded data length of one line is shorter than the specified minimum data length, and a large number of dummy data are added to the encoded data. It is an object of the present invention to provide a coded data transmission processing method capable of performing high-speed data processing even when it is necessary.

[0007]

According to the method of the present invention proposed to achieve the above object, when the encoded image data is written in the modem buffer, the encoded data is stored in the address of the modem buffer designated by the write pointer. Each time storing, the coded data for one line is written while incrementing the value indicated by the write pointer,
When the writing is completed, the operation of skipping the value indicated by the write pointer by the address corresponding to the dummy data to be added to fill the minimum data length of one line is repeatedly performed, and the data stored in the modem buffer is repeated. Is read, every time the encoded data or the dummy data is read from the address of the modem buffer designated by the read pointer, the dummy data is stored in the address and the designated value of the read pointer is incremented. Such a method of the present invention uses a modem buffer which has a predetermined memory capacity and is composed of a ring memory which returns to the head address when the address pointed to by the read pointer or the write pointer reaches the final address. Can be implemented by Further, although the writing process and the reading process of the data of the modem buffer can be performed in a bit unit, it is possible to perform an efficient process in a byte unit according to the configuration of the signal processing unit.

[0008]

According to the present invention, when the encoded image data is written in the modem buffer, the operation of incrementing the value indicated by the write pointer is repeated while writing the encoded data in the memory cell at the address designated by the write pointer. After writing the coded data for one line and finishing the writing process, the dummy data to be added is already written in the memory cells subsequent to the written coded data. Therefore, even if the necessary amount of dummy data is not written one by one, it is possible to skip the indicated value of the write pointer by the address corresponding to the dummy data to be added to the encoded data to fill the minimum data length of one line. A required amount of dummy data is instantly added after the encoded data. On the other hand, when reading the image data stored in the modem buffer to the modem side, the image data stored in the memory cell at the address indicated by the read pointer is read and transferred to the modem side while reading the image data. The dummy data is stored in the memory cell of the read address and the operation of incrementing the designated address of the read pointer is repeated.
The dummy data is replaced and stored in place of the written image data, and the next data is prepared for writing. Therefore, even when the encoded data is written again to the memory cell from which the data has been read, it is possible to add the dummy data to the encoded data simply by skipping the write pointer after writing the encoded data.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a flow chart for explaining the data writing process to the modem buffer in the method of the present invention, and FIG. 1B is a flow chart for explaining the data reading process from the modem buffer. The operation will be described with reference to the schematic diagrams of the modem buffers shown in FIGS. 2A and 2B. The data transfer process is performed in 1-bit units.

[0010] 1. Data write processing operation to the modem buffer (see (A) steps 100 to 105 in FIG. 1 and (A) in FIG. 2). In the initial state, dummy data (0 signal) is written in all the memory cells of the modem buffer, and the read pointer and the write pointer point to the address 0, respectively. The EOL code (line end code) is written from the write pointer instruction address, and when the writing is completed, the write pointer instruction value is changed to EOL.
Move to the next address where the code is written. The operation of incrementing the value indicated by the write pointer while writing the encoded image data in the memory cell at the address designated by the write pointer is repeated until the writing of the encoded data for one line is completed. 1
When the writing of the encoded data for the line is completed, the designated value of the write pointer is skipped by the address corresponding to the dummy data to be added to the encoded data in order to satisfy the minimum data length of the one line. By repeating the operations 1 to 3, the coded image data of each line of the transmission original is sequentially stored in the modem buffer. Then, while the process of writing data to the modem buffer is being performed, an interrupt process is performed at a predetermined cycle determined by the data transmission speed of the modem, and a process of reading data from the modem buffer is performed. To be executed.

2. A process of reading data from the modem buffer (see steps 200 to 202 in FIG. 1B and FIG. 2B). The data written in the memory cell at the address designated by the read pointer is read and sent to the modem side. After writing the dummy data to the memory cell at the address designated by the read pointer, the value designated by the read pointer is incremented. Such interrupt processing,
This is repeated for each memory cell until the read data is completed (until the indicated value of the read pointer becomes the indicated value of the write pointer). As described above, when the method of the present invention is carried out, if the dummy data is written in all the memory cells of the modem buffer in the initial state, the write address indicating the next address where the encoded data has already been written is written. The dummy data can be added to the encoded data instantly by simply skipping the pointer by a value corresponding to the dummy data to be added. In the present invention, as the dummy data to be added becomes longer, the processing speed can be improved as compared with the conventional case where the dummy data is written by software processing one by one. Also, each time data is read from the modem buffer to the modem side, dummy data is written and preparations for writing the next data are made. Therefore, the memory cell from which the data has been read can be reused for writing the data.

FIG. 3 is a block diagram showing an example of the essential configuration of a facsimile apparatus for carrying out the above-described method of the present invention. In the figure, 10 is a signal processing unit for performing signal processing of each unit, and 11 is An image sensor that reads the reflected light of the transmission original illuminated by a light source (not shown) line by line and outputs binarized image data. Reference numeral 12 converts the image data obtained by the image sensor into run length data. The run length conversion unit 13 is a run length counter that integrates the run length data values. Reference numeral 14 is an encoding circuit that refers to the encoding table 15 to convert the run length data into a code. Reference numeral 16 is a code register for temporarily storing encoded data, 17 is a code length counter for subtracting and counting the code length of encoded data, and 18 is a line code length for accumulating the code length of encoded data for one line. It is a counter. Further, 19 is a temporary buffer for transferring encoded data to the modem buffer 20 byte by byte, 21 is a modem for reading out the image data stored in the modem buffer 20 and transmitting the modulated image signal to the telephone line L, and 22 is It is a pointer register that forms a write pointer that indicates a write address of the modem buffer 20 and a read pointer that indicates a read address.

As shown in FIG. 4, the run length conversion unit 12 decomposes the image data of one line L1 of the transmission original P read by the image pickup device 11 into run lengths for each white run and black run. Data is obtained, and according to the instruction from the signal processing unit 10, the white run 450, the black run 90 ...
The run length data such as is sequentially output. The run-length counter 13 integrates the run-length data each time the run-length converter 12 outputs the run-length data, and the integrated value is the image data length for one line (1728 bits for A4 standard size paper size). Then, a line end signal is output to the signal processing unit 10. The code length counter 17 is set to the value of the data length of the encoded data transmitted to the signal processing unit 10, and each time the signal processing unit 10 transfers 1-byte code data from the code register 16 to the temporary buffer 19. Performs the operation of subtraction. The line code length counter 18 includes the encoding circuit 1
4 every time encoded data is output from the signal processing unit 10
The data lengths of the coded data obtained in step 1 are added up to count the coded data length when the coding for one line is completed. The pointer register 22 is, as described with reference to FIG. 2, a write pointer that points to the next address of a memory cell in which data has already been written in the modem buffer 20,
Next, it has a read pointer for designating an address for starting the reading of data, and when the address is sequentially incremented by the signal processing unit 10 to reach the final address of the modem buffer, it returns to the leading address again. .

The operation of the facsimile apparatus 1 having such a configuration will be described with reference to the flow charts of FIGS. 5 and 6. 1. An operation of writing encoded data into the modem buffer 20 (see steps 300 to 315 in FIG. 5). The count values of the line code length counter 18 and the run length counter 13 are initialized to 0. In the signal processing unit 10, the EOL code is read by referring to the encoding table 15, and the read EOL code is read through the code register 16 and the temporary buffer 19 into the modem buffer 20 at the address designated by the write pointer for each byte. Transfer and increment the write pointer. In the signal processing unit 10, a control signal is transmitted to the run-length conversion circuit 12, the run-length data at the head is transmitted to the encoding circuit 14 for encoding, and the encoded data is encoded register 1
6 is stored. In the signal processing unit 10, the code register 1
The code length data of the encoded data stored in 6 is obtained and set in the code length counter 17, and the obtained code length data is added to the line code length counter. In the signal processing unit 10, one byte of the encoded data stored in the code register is transferred to the address designated by the write pointer of the modem buffer 20 via the temporary buffer 19 and written, and then the write pointer is written. Code length counter 1
A series of operations for decrementing the count value of 7 is repeated until the count value of the code length counter 17 becomes 0. Thereby, the code corresponding to one run length data is written in the modem buffer. After this,
The signal processing unit 10 outputs a control signal to the run length counter 13 and outputs the run length data output from the run length conversion unit 12 to the run length counter 13.
To monitor whether or not a line end signal is output from the run length counter 13. As a result of monitoring, when the count value of the run length counter 13 has not reached the specified run length (1728 bits) and the line end signal is not output, the procedure returns to the above and the same operation is repeated. In this way, when the coded data writing process is repeated and the count value of the run length counter 13 reaches the specified run length and the line end signal is output, the signal processing unit 10 counts the line code length counter 18. When the count value is referred to and the count value does not reach the minimum data length of one line, the value indicated by the write pointer of the pointer register 22 is skipped by the difference. However, when the count value of the line code length counter 18 has reached the specified value, the write pointer is not skipped, and after that, when it is not the page end, the operation returns to the above operation again, but if it is the page end, the write operation is performed. The process ends. By performing the above operation,
The coded image data of each line of the transmission document is sequentially accumulated in the modem buffer, and during the process of writing data to this modem buffer, the interruption process from the modem buffer is performed by the interrupt process. Data read processing is executed.

2. Image data read processing operation from the modem buffer 20 (see steps 400 to 404 in FIG. 6).
When the interrupt signal is output from the modem 21 to the signal processing unit 10, the signal processing unit 10 interrupts the above-described image data writing process, and the 1-byte data of the instruction address of the read pointer of the modem buffer 20 is transferred to the modem. It is output to 21 and sent to the telephone line. Then, in the signal processing unit 10, the dummy data (0
If the read pointer instruction address and write pointer instruction address are not the same after writing a fill signal (consecutive signal), the read pointer instruction address is incremented, but when both pointer instruction addresses are the same. Do not increment the read pointer. These operations are repeated each time an interrupt signal is output until all the image data in the modem buffer 20 is read and transmitted. In the above description, when the read pointer and the write pointer have the same designated address, the read pointer is not incremented even if the read is performed. However, this processing automatically fills the fill signal of the same address. Is repeatedly sent from the modem, even if the reading process of the transmitted document is delayed due to a paper jam, for example,
The transmitted fill signal can prevent an error from occurring immediately.

As described above, according to the facsimile apparatus for carrying out the method of the present invention, the code can be instantly coded only by skipping the designated address of the write pointer according to the dummy data length to be added to the coded data. It becomes possible to add a fill signal to the encoded data, and each time data is read from the modem buffer to the modem side, dummy data is written and preparations are made as a write cell for the next data. Therefore, a ring memory or the like having a predetermined capacity can be effectively used as a modem buffer.

In the above description, the case where the fill signal is added so that the transmission time of the image data for each line matches the specified minimum transmission time has been described. This is effective when the receiving buffer memory capacity is small, but since the encoded data length may be much longer than the minimum data length, it is not always necessary to make each line the minimum data length. Therefore, for example, in the configuration in which the receiving side is provided with a receiving buffer memory capable of storing data for about 50 lines of image data, the code for 50 lines is not required to be added for each line. A method of collectively adding a required amount of dummy data after the converted data is also possible.

FIG. 7 shows a method for adding such dummy data. In the modem buffer, encoded data for each line is divided by EOL and sequentially stored for 50 lines, and the 50th line is stored. After the encoded data, dummy data (fill signal) obtained by subtracting the total data length of the encoded data from the minimum data length necessary for printing the 50 lines and adjusting the time required for the sub-scan is added together. The processing can be simplified as compared with the case where the fill is added for each line. Therefore, the dummy data can be added instantly by simply skipping the required value of the write pointer, and the processing speed of the image data can be further improved.

[0019]

As can be understood from the above description, according to the present invention, the encoded data length of one line is shorter than the specified minimum data length, and dummy data is added to the encoded data. Even if it is necessary, dummy data can be added instantly simply by skipping the write pointer indication value, so the length of dummy data to be added is longer than in the conventional writing of dummy data. The processing speed can be improved as much as possible, and when reading data from the modem buffer, dummy data is automatically written to prepare for writing the next data, so it is a modem buffer with a specified memory capacity. However, the memory cells can be used repeatedly by effectively using them.

[Brief description of the drawings]

FIGS. 1A and 1B are flowcharts illustrating the method of the present invention.

2A and 2B are explanatory views schematically showing the method of the present invention.

FIG. 3 is a diagram showing a configuration example of a main part of a facsimile apparatus for carrying out the method of the present invention shown in FIG.

4 is an operation explanatory diagram of a run length conversion unit in the facsimile apparatus shown in FIG.

5 is a flowchart illustrating an operation of a writing process to a modem buffer in the facsimile device shown in FIG.

FIG. 6 is a flowchart illustrating an operation of a read process from a modem buffer in the facsimile device shown in FIG.

FIG. 7 is an explanatory diagram of a special fill addition method different from the method of the present invention.

FIG. 8 is an explanatory diagram of encoding of image data.

FIG. 9 is an explanatory diagram of a writing process and a reading process of a conventional modem buffer.

10A and 10B are flowcharts for explaining a conventional modem buffer write process and read process.

[Explanation of symbols]

22 pointer register (write pointer, read pointer) 20 modem buffer

Claims (1)

(57) [Claims] 1. A minimum data length of one line when the write pointer is incremented every time the encoded data is stored in the address of the modem buffer designated by the write pointer and the writing of the encoded data for one line is completed. Each time the data is read from the address of the modem buffer pointed to by the read pointer, dummy data is stored in that address and the read pointer is stored while skipping the write pointer by the address corresponding to the dummy data to be added to A transmission processing method of encoded data, characterized by incrementing.