JPS6252507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a facsimile communication device.

As is well known, the principle of facsimile is that it is a communication method in which the original transmitted image is divided into pixels by scanning, these are converted into electrical signals and transmitted, and the received image, which is similar to the transmitted original image, is reproduced and recorded. However, the process from decomposing the original image into pixels and converting it into electrical signals,
In this specification, it is called a reading operation, the device for that purpose is called a reading device, the device for reproducing and recording is called an output device, and the reading device and the output device are collectively called an I/O device.

In facsimile communications, in order to send signals at high speed in a limited transmission band, it is common practice to compress information through encoding and other means before transmitting it. That's what it means. The data compression ratio is low when the original image has a complex pattern, and high when it is simple such as all white or all black, but on average it is 5 to 6 times higher.

Now, in facsimile communication, when increasing the data compression ratio in the data compressor to increase the transmission speed, the speed of the I/O device may not be able to keep up with it. The low speed of the I/O device was covered by sending the code. This was essentially the same as not being able to utilize the compression performance of the data compressor to its full potential, resulting in wastage. In particular, it has not been possible to design the speed of an I/O device to match the maximum compression ratio of a data compressor due to the cost of the I/O device.

This invention was made in view of the above-mentioned conventional circumstances, and is a novel method that does not impose excessive demands on the speed of the I/O device and does not waste the compression performance of the data compressor. The purpose is to provide a facsimile communication device that is easy to use.

Next, it will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an outline of the configuration of an embodiment of the present invention. In FIG. 1, 1 is a reading device, 2 is an encoding device, 3 is a buffer memory,
4 is a dummy code generator, 5 is a data link controller, 6 is a modem, 7 is a network control device, 8 is an operation button, 9 is a system controller, 10 is a communication controller, 11 is a recording device, 12 is a decoding device, 13 is a buffer memory, 14 is a dummy code removal device, 15 is a data link controller, 16 is a modem, 17 is a network control device, 18 is an operation button, 19 is a system controller on the receiving side, and 20 is a communication controller on the receiving side. show.

In FIG. 1, an overview of the operation of the transmitting side device will be described. The document and image information converted into a binary signal by the reading device 1 is converted into a code signal by the encoding device 2, and then stored in the buffer memory 3. A dummy code is added to the signal read from the buffer memory 3 by the dummy code generator if necessary, and the signal is input to the data link controller 5. The data link controller 5 constructs a frame by adding fields such as flag, address, control, and frame check to the information field, and then inputs the frame to the modem 6. The signal modulated by the modem 6 is sent out to a telephone line, for example, via a network control device 7. The communication controller 10 controls the network control device 7, modem 6, and data link controller 5 according to commands from the system controller 9, and establishes a call with the receiving side, exchanges digital information, trains the modem, and posts data. Exchange messages. The system controller 9 senses the states of the operation button 8, the reading device 1, the encoding device 2, the buffer memory 3, and the communication controller 10, and
Encoding device 2, buffer memory 3, dummy code generator 4, communication controller 1
Issue an operation command to 0.

The configuration of the receiving side is the same as that of the transmitting side, except that a decoding device 12 is used instead of the encoding device 2, and a dummy code removing device 14 is used instead of the dummy code generating device 4.

As stated earlier, the purpose of this invention is to
The aim was to maximize the compression performance of the data compressor and improve the transmission speed without increasing the speed of the device beyond conventional speeds. So, specifically,
In the transmitting device shown in FIG.
During the period from when the device is activated by the operation to when the message actually begins to be sent from the network control device 7 to the telephone line (this period is referred to as the protocol time), the reading device 1 has already been operated to a certain extent. By reading the calligraphy information and storing it in the buffer memory 3, the low speed of the reading device is compensated for. This explanation will be explained in more detail below.

For example, suppose the speed of the I/O device is 20ms/line and the transmission speed of modem 6 is 4800BPS,
Assume that the line density of the original drawing is 4 lines/mm.
Also, CCITT STUDY GROUP XIV SPECIAL
RAPPORTEUR FOR GROUP3 EQUIPMENT
(SEPTEMBER 1976), one line
The code length for an all-white run length of 1728 bits is:
Even with an EOL (end of line) code, it is compressed to 28 bits. Calculate using the above numbers and assuming an all-white manuscript.

If the total number of bits after compression of an all-white document with an original length of 300 mm is K ₁ , then K ₁ = 28 x 300 x 4 = 3.36 x 10 ⁴ bits It takes to transmit this K ₁ bit from a modem with a speed of 4800 BPS. If the time is T, then T = K ₁ /4800 = 7 seconds. If the binary signal data generated in 7 seconds by an I/O device with a speed of 20 ms/line is K ₂ , then K ₂ = 28 x 7. seconds/20ms = 9.8 x ^{10 3} bits If the I/O device and modem start operating at the same time and the missing data after 7 seconds is K ₀ , then K ₀ = K ₁ - K ₂ = 23.8 x 10 ³ bits The above relationship Figure 2 qualitatively illustrates this. Therefore, if the missing _K0 bits are read in advance into the buffer memory using a reading device and stored before starting the modem and starting transmission, the I/O speed will not be increased any higher than before, and the dummy No need to send a code,
This invention can cover the low speeds of I/O devices, and this is what the present invention proposes. and,
It is appropriate to use the protocol time as the period for reading and storing data in advance in this way.

FIG. 3 is a diagram showing the exchange of signals between the transmitting side and the receiving side according to the temporal phase, and is a diagram for illustrating the protocol. As can be seen in FIG. 3, in phase A, the operator calls the receiving station by dialing. The operator confirms the called station by voice response, etc., and presses the send button. At this point, the process moves to phase B, which queries the mode of the other machine, specifies the mode, trains the modem, and confirms readiness to receive. At this point, phase B ends and the transmission of calligraphic information (message) begins only after entering phase C. Preliminary reading in the present invention is performed during phase B. The period during this phase B is called the protocol time, and is referred to as V21 of the CCITT recommendation.
In a 300BPS modem (FSK), Phase B requires approximately 12 seconds.

FIG. 4 is a diagram showing the relationship between time and stored bits when this invention is actually applied to a system. That is, the reading device needs to pre-read _K0 bits of data and store it in the buffer memory by the end time _T1 of the protocol time during which the transmitting side and the receiving side are communicating. After the protocol end time _T1 , the modem begins to send the encoded data stored in the buffer memory onto the telephone line.
On the other hand, on the receiving side, recording is started at the same time as data is received, and when the recording speed cannot catch up with the amount of received data, the data is accumulated in a buffer.

FIG. 5 is a diagram showing in detail the interface between the encoding device 2, buffer memory 3, and dummy code generator 4 on the transmitting side, and using FIG. 5, the operation mode of the device of the present invention will be explained. explain in detail.

During the protocol time, the binary data of the drawing information that is binarized in the reading device is converted into an encoding device 2.
The data is encoded in the buffer memory 3 and transferred as coded data to the buffer memory 3 using the data go strobe signal. The buffer memory 3 notifies the system controller 9 that the buffer is full using a buffer full signal. The encoding device 2 receives binary data and a line sync signal indicating the end (or start) of each scanning line from the reading device, and reads the encoded data every time the encoding for one scanning line is completed. Next, add an EOL (end of one line) code. Buffer memory 3 is used for buffer memory with a margin for the EOL code.
Even if a full signal is output, the system controller detects a buffer full signal, and an encoding stop command is issued to the encoding device 2, the encoding device 2 will not transfer the encoded data to the buffer memory 3 in the middle of the EOL code. The transfer will not be stopped.

Upon receiving the buffer full signal, the system controller 9 not only issues an encoding stop command to the encoding device 2, but also simultaneously sends a command to the reading device to interrupt the reading scan. Therefore, it is necessary for the reading device to be able to interrupt the reading operation in the middle of a scanning line. If the reading operation can only be interrupted in units of scanning lines, the encoding device 2 must be provided with a line buffer for two scanning lines.
Upon receiving a response signal indicating that the protocol time has ended from the communication controller, the system controller 9 turns on the start signal in order to transfer the coded data stored in the buffer memory 3 to the dummy code generator 4 for the first time.

Once data transfer to the modem is started, this transfer continues without interruption until the transfer of one document's worth of data is completed. System controller 9
always monitors the full state of the buffer memory 3 and controls the start and stop of the reading device and the encoding device 2.

The system controller 9 also constantly monitors the buffer/empty signal, and if the content of the buffer memory 3 becomes empty due to a longer than expected document or high line density transmission, the system controller 9 sends a dummy code. A dummy start command is issued to the generator 4 to control it to send out a dummy code instead of coded data. Naturally, the dummy code must be distinguishable from coded data and must have an expandable code length. The transfer clock from the buffer memory 3 to the dummy code generator 4 and from the dummy code generator 4 to the data link controller is the modem
A clock is used.

On the other hand, on the receiving side, a dummy code removing device (14 in FIG. 1) removes a dummy code from the output data of the data link controller and transfers it to a buffer memory (13 in FIG. 1). If the capacities of the transmitting side buffer memory and the receiving side buffer memory are the same and the recording speed is the same as or faster than the reading speed, the receiving side buffer memory can record the received data on the receiving side without overflowing. In FIG. 1, placing the dummy code removing device 14 in front of the buffer memory 13 is an effective means to avoid increasing the capacity of the buffer memory 13.

As is clear from the above detailed explanation, according to the present invention, by skillfully utilizing the protocol time, sufficient document and image information to cover the low speed of the reading device is stored in the buffer memory in advance during this time. Since transmission is started after data is stored in the data compressor, high-speed transmission is possible without sacrificing the compression performance of the data compressor. It has the great advantage of not putting any extra burden on you.

In the above-described embodiment, the buffer memory is located after the compressor, but this is to make the memory size even smaller; it goes without saying that it may also be located before the compressor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of the configuration of an embodiment of the present invention. FIG. 2 is a diagram qualitatively showing the missing data amount K ₀ based on the difference between the speed of the 1/0 device and the transmission speed of the modem, and is a diagram necessary for explaining the principle of the present invention. FIG. 3 is a diagram showing a situation in which signals are exchanged between a transmitting side and a receiving side in facsimile communication, and is a diagram for explaining protocol time. FIG. 4 is a diagram showing the principle of this invention. FIG. 5 is a diagram for explaining the operation mode of an embodiment of the present invention. In the figure, 1 is a reading device, 2 is an encoding device,
3 is a buffer memory, 4 is a dummy code generator, 5 is a data link controller, 6 is a modem, 7 is a network control device, 8 is an operation button, 9 is a system controller, 10 is a communication controller, 11 is a recording device, 12 1 is a decoding device, 13 is a buffer memory, 14 is a dummy code removing device, 15 is a data link controller, 1
6 is a modem, 17 is a network control device, 18 is an operation button, 19 is a system controller, and 20 is a communication controller.

Claims (1)

[Scope of Claims] 1. A facsimile communication device that includes a reading device, a modem, and a system controller, and modulates and transmits the document and image information read by the reading device by the modem under the control of the system controller, which comprises a buffer memory and a facsimile communication device. starting the reading operation of the calligraphy information by the reading device at a desired time within a protocol time which is a time length from activation to the actual start of transmission of the calligraphy information, and storing the read information in the buffer memory; A facsimile communication device characterized by comprising: the system controller which reads out the calligraphic information stored in the buffer memory and starts transmitting it when the protocol time ends.