JP2561092B2 - Facsimile transmission method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a facsimile transmission system.

[Prior Art] Generally, a facsimile machine has a function according to a recommendation of CCITT (International Telegraph and Telephone Consultative Committee). For example, regarding the group 3 device, the standard of the device is defined by Recommendation T.4, and the standard of the transmission control procedure is defined by Recommendation T.30. Then, data transmission between the devices according to these recommendations is guaranteed.

However, from the viewpoint of security of data transmission, there is a possibility that important data may be stolen by a device that meets the same standard, which may cause an unfavorable situation.

For example, if an eavesdropping device is connected to a telephone line used as a transmission line to eavesdrop a transmission signal, and the transmission signal is given to a facsimile device having the same standard as the transmission device, the transmission image information is transmitted to the facsimile device on the eavesdropping device side. It can be reproduced on the device.

In this way, conventionally, a problem may occur when transmitting highly confidential information using a facsimile machine.

[Object] The present invention has been made in order to eliminate the disadvantages of the prior art, and an object of the present invention is to provide a facsimile transmission system capable of appropriately transmitting highly confidential image information.

[Structure] In order to achieve this object, the present invention uses a non-standard coding table for a transmission device and image information coded and compressed based on this non-standard coding table as an original image signal. While the non-standard decoding table for decoding is provided, the receiving device is provided with the decoding table storage means for storing the non-standard decoding table, and the transmitting device uses the decoding table in the pre-transmission procedure. The contents are transmitted to the receiving device, the receiving device stores the contents of the received decoding table in the decoding table storage means, and the transmitting device compresses the image information based on the non-standard encoding table to the receiving device. The image data is transmitted and the receiving device decodes the received image information into the original image signal based on the decoding table stored in the decoding table storage means.

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

FIG. 1 shows a facsimile transmitter (hereinafter, simply referred to as transmitter) TX according to an embodiment of the present invention.

In the figure, a system control unit 1 controls the entire transmission device TX, a scanner 2 reads a transmission document at a predetermined resolution, and an operation display unit 3
Is composed of various operation keys and a display necessary for operating the transmitter TX. The image memory 4 is for accumulating image information and the like in a coded and compressed state.

The encoding unit 5 encodes and compresses the transmission image signal, and includes a standard encoding table 6 for standard encoding and a non-standard encoding table 7 for non-standard encoding. . The non-standard decoding table 8 is for decoding the image information coded and compressed based on the non-standard coding table 7 into the original image signal, and is transmitted to the receiving device RX as described later. Are reconfigured by the receiving device.

The communication control unit 9 is for executing a predetermined facsimile transmission control procedure to execute image transmission with the partner station,
The modem 10 modulates and demodulates digital data so that a public telephone line network, which is an analog line network, can be used as a transmission line, and the network control device 11 connects the transmission device TX to the public telephone line network. It is a thing. The network control device 11 has an automatic transmission function.

Further, the system control unit 1, the scanner 2, the operation display unit 3, the image memory 4, the decoding unit 5, the non-standard decoding table 8 and the communication control unit 9 exchange data with each other via the system bus 12. There is.

FIG. 2 shows a facsimile receiver (hereinafter, simply referred to as a receiver) RX according to an embodiment of the present invention.

In the figure, a system control unit 21 controls the entire receiving device RX, a plotter 22 records and outputs a received image at a predetermined resolution, and an operation display unit 23 controls the receiving device RX. It consists of various operation keys and indicators required to operate the RX. The image memory 24 is for accumulating image information and the like in a coded and compressed state.

The decoding unit 25 is for decoding the received image information into the original image signal, and is a standard decoding table for standard decoding.
26, and a non-standard table storage unit 27 for accumulating and reconstructing a non-standard decoding table for non-standard decoding.

The communication control unit 28 is for executing a predetermined facsimile transmission control procedure to execute image transmission with the partner station,
The modem 29 modulates / demodulates digital data so that a public telephone line network or the like which is an analog line network can be used as a transmission circuit, and the network control device 30 connects the receiving device RX to the public telephone line network. It is a thing. The network control device 30 has an automatic incoming call function.

In addition, the system control unit 21, the plotter 22, the operation display unit 2
3, image memory 24, encoding unit 25, non-standard table storage unit 2
The 7 and the communication control unit 28 exchange data with each other via the system bus 31.

Here, the standard encoding table 6 of the transmitting device TX and the standard decoding table 26 of the receiving device RX are for realizing the standard one-dimensional encoding method defined in CCITT Recommendation T.4. .

Further, the non-standard coding table 7 and the non-standard decoding table 8 of the transmitting device TX are for realizing highly confidential image information transmission by the non-standard one-dimensional coding method. As will be described later, the contents of the non-standard decoding table 8 are transmitted to the receiving device RX and reconfigured in the non-standard table storage unit 27, so that the receiving device RX includes the non-standard decoding table 8. Is able to.

The non-standard coding table 7 includes the standard coding table 6
In FIG. 3, a code in which the relationship between the code and the run length is formed by replacing a part of the code length with the same code length is stored. An example (part) is shown in the following table.

As described above, the relationship between the appearance probability of the code run length and the code length defined in the non-standard coding table 7 and the non-standard decoding table 8 is defined in the standard coding table 6 and the standard decoding table 26. Since the relationship between the appearance probability of the run length of the code and the code length is equal, the efficiency of the non-standard coding using the non-standard coding table 7 and the non-standard decoding table 8 is It is equal to the efficiency of standard encoding using the standard encoding table 26.

Note that the encoding unit 5 applies the same encoding rule when using the non-standard encoding table 7 as when using the standard encoding table 6. The decoding unit 25 also uses the standard decoding table 26 and the non-standard table storage unit 27.
The same decoding rule is applied as in the case of using the non-standard decoding table 8 reconstructed in 1.

A case where image information is transmitted from the transmission device TX to the reception device RX will be described.

If the transmission image information is highly confidential, the transmission device
The operator of the TX sets the transmission original on the scanner 2 and inputs the destination information, and then instructs the operation display unit 3 to transmit the image in the encryption mode.

As a result, the system control unit 1 of the transmission device TX first transfers the destination information to the network control device 11 to call the destination.

As a result, when a transmission path is established between the transmitting device TX and the receiving device RX, the receiving device RX, as shown in FIG. 3, displays the called station identification signal for indicating that its own terminal is a facsimile device. CED, non-standard device signal NSF for notifying non-standard functions of own terminal, digital identification signal DIS for notifying standard functions of own terminal are sequentially transmitted to the transmitter. . Further, the non-standard device signal NSF includes information indicating that the non-standard decoding table 8 has a function capable of being internally reconfigured.

As a result, it can be seen that the transmitting device TX has the function of allowing the receiving device RX to reconfigure the non-standard decoding table 8. The setting signal NSS (T) is transmitted to the receiving device RX.

In the receiving device RX, this non-standard device setting signal NSS (T)
The contents of the non-standard decoding table 8 added to the are stored in the non-standard table storage unit 27 in sequence. As a result, the nonstandard decoding table 8 is reconfigured in the nonstandard table storage unit 27. Further, it is checked whether or not the non-standard device setting signal NSS (T) has been received without error, and if there is no reception error, a reception preparation confirmation signal CFR is returned to the transmission device TX. In addition, this non-standard device setting signal NSS
Frame check sequence FCS added to the signal frame for transmitting (T) (see CCITT Recommendation T.30)
By a cyclic redundancy check based on

As a result, the transmitter TX receives the non-standard device setting signal NSS including the setting information of the function for transmitting other image information.
(S) is transmitted to the receiver RX to set the transmission function, and the training check TCF for training the modems 10, 29 is transmitted at the transmission speed of the image information set at that time. If the reception result of the training check TCF is good, the reception device returns a reception preparation confirmation signal king CFR.

As a result, the system control unit 1 of the transmission device TX commands the encoding unit 5 to use the non-standard encoding table 7. Then, the scanner 2 is operated to read the image of the transmission original, and the image signal is encoded by the encoding unit 5,
The image information PIX formed thereby is transferred to the communication control unit 9 and sent to the transmission path.

On the other hand, the system control unit 21 of the reception device RX has the decoding unit 25.
Then, the non-standard table storage unit 27 is instructed to use the reconstructed non-standard decoding table 8. Then, after the received image information is decoded by the decoding unit 25 into the original image signal, the image signal is sequentially transferred to the plotter 22 and
The received image is recorded and output to 22.

When the transmission of the image information PIX is completed, the transmitter TX sends the procedure end signal EOP and the receiver RX receives the message confirmation signal MOP.
Reply CF. As a result, the transmission device TX transmits the line disconnection command signal DCN, then disconnects the line and ends the image information transmission. The receiving device RX also disconnects the line and ends the image information transmission.

In this way, when the encryption mode is set in the transmission device TX, image information transmission using a non-standard code is executed in the transmission device TX and the reception device RX. This gives, for example,
Even if the wiretapping device eavesdrops the signal on the transmission path, the eavesdropping side facsimile device cannot properly reconstruct the image information, so that the confidentiality of the image information can be maintained.

By the way, for example, when the receiving device RX determines that the reception state is bad in the received non-standard device setting signal NSS (T), the receiving device RX is
A train failure signal FTT is returned to TX (see FIG. 4).

At this time, the transmitter TX sends the line disconnection command signal DCN to terminate the transmission of the image information, calls the same destination again, and performs the same operation as described above.

Therefore, when transmitting the image information in the encryption mode, the correct non-standard decryption table 8 is always sent to the receiving device RX.
Is reconfigured, the receiving device RX can record and output accurate image information.

On the other hand, when the operator does not specify the encryption mode, the system control unit 1 of the transmission device TX instructs the encoding unit 5 to use the standard encoding table 6. In this case, the non-standard device setting signal NSS (T) is not transmitted to the receiving device RX.

In this way, the non-standard device setting signal NSS
When (T) is not transmitted, the system control unit 21 of the reception device RX instructs the decoding unit 25 to use the standard decoding table 26.

As a result, the transmission device TX and the reception device RX can perform image information transmission using a standard encoding method.

Note that, for example, if the operator mistakenly inputs the destination information and connects to a facsimile machine that does not have the function of internally reconfiguring the non-standard decryption table even though the encryption mode is set, The device TX suspends its transmission when it learns that its destination facsimile device does not have the capability to reconstruct the non-standard decoding table internally.

By the way, as the non-standard coding table, ones other than those shown in the above-mentioned embodiments can be used. For example, in the standard encoding table, the relationship between the code and the run length can be configured by exchanging all of them at the portions having the same code length.

Further, as in the above-described embodiment, it is preferable to use a code that uses the same coding rule as the standard coding method for the non-standard code because the coding / decoding unit can be commonly used.

Further, the image information transmission in the encryption mode can also be used for the broadcast transmission using the storage function of the image memory.

Although one non-standard decryption table is provided in the above-described embodiment, two or more non-standard decryption tables are provided, and when transmitting in the encryption mode, any one of the non-standard decryption tables is provided to the operator. You can also choose to select a table.

[Effect] As described above, according to the present invention, a non-standard coding table for a transmission device and image information coded and compressed based on this non-standard coding table are used as the original image signal. While the non-standard decoding table for decoding is provided, the receiving apparatus is provided with the decoding table storage means for storing the non-standard decoding table, and the transmitting apparatus stores the decoding table in the pre-transmission procedure. The contents are transmitted to the receiving device, the receiving device stores the contents of the received decoding table in the decoding table storage means, and the transmitting device compresses the image information based on the non-standard encoding table to the receiving device. Since the image information is transmitted and the receiving device decodes the received image information into the original image signal based on the decoding table stored in the decoding table storage means, it can be said that the highly confidential image information can be appropriately transmitted. The effect obtain.

[Brief description of drawings]

FIG. 1 is a block diagram showing a facsimile transmitting apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a facsimile receiving apparatus according to an embodiment of the present invention, and FIG. 3 is an example of transmission control. Time chart, FIG. 4 is a time chart showing another example of the transmission control. 1,21 ... System control unit, 3,23 ... Operation display unit, 5 ... Encoding unit, 7 ... Non-standard encoding table, 8 ... Non-standard decoding table, 9,28 ... Communication control 25 ... Decoding unit, 27 ... Non-standard table storage unit, TX ... Transmitting device, RX ... Receiving device.

Claims (1)

(57) [Claims] 1. A facsimile transmission system for encoding and compressing image information for transmission, and a non-standard encoding table for a transmitter and image information encoded and compressed based on this non-standard encoding table. Is provided with a non-standard decoding table for decoding the original picture signal, while the receiving device is provided with a decoding table storage means for storing the non-standard decoding table. The transmitting device transmits the contents of the decoding table to the receiving device, the receiving device stores the contents of the received decoding table in the decoding table storage means, and the transmitting device stores the contents in the non-standard encoding table. Image information is compressed based on the image information and transmitted to the receiving device, and the receiving device decodes the received image information into the original image signal based on the decoding table stored in the decoding table storage means. Facsimile transmission method characterized.