JP2524744B2 - Transmission system - 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.

As described above, conventionally, there have been cases where inconveniences occur when transmitting highly confidential information with 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.

[Configuration] The present invention is a non-standard encoding table in which a part of the encoding table conforming to the CCITT recommendation is replaced in a facsimile transmission method in which image information is encoded and compressed based on the standard encoding table conforming to the CCITT recommendation. And a non-standard encoding selecting means for selectively inputting to encode and compress the image information using the non-standard encoding table, and the non-standard encoding by the non-standard encoding compression selecting means during transmission. When encoding compression of image information using the table is selected, when the other terminal notifies that the non-standard encoding table is provided, the compression compression is performed using the non-standard encoding table. While transmitting the image information to the other terminal, when the other terminal notifies that the non-standard encoding table is not provided, the image information transmission procedure that stops the transmission of the image information. It is those with a door.

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

FIG. 1 shows a facsimile apparatus according to an embodiment of the present invention.

In the figure, a system control unit 1 controls the entire facsimile apparatus, a scanner 2 is for reading a transmission document at a predetermined resolution, and a plotter 3 records and outputs a received image at a predetermined resolution. It is for.

The operation display unit 4 comprises various operation keys and a display necessary for operating the facsimile apparatus. The image memory 5 is for accumulating image information and the like in a coded and compressed state.

The encoding / decoding unit 6 encodes and compresses the transmission image signal and also decodes the reception image information into the original image signal. The standard encoding table 7 for standard encoding / decoding is used. And a non-standard encoding table 8 for non-standard encoding / decoding. Standard encoding table 7 is CCITT
The non-standard coding table 8 is for realizing the standard coding method defined in Recommendation T.4, and the non-standard coding table 8 uses other non-standard coding methods to transmit highly confidential image information. Is to realize.

The non-standard coding table 8 stores a code in which the relationship between the code and the run length in the standard coding table 7 is replaced by a part having the same code length, and an example thereof (part ) Is shown in the following table.

In this way, the relationship between the appearance probability of the code run length and the code length defined in the non-standard encoding table 8 is the relationship between the appearance probability of the code run length and the code length defined in the compliant encoding table 7. Since it is equal to the relation, the non-standard encoding table 8
The efficiency of the non-standard encoding using the is equal to the efficiency of the standard encoding using the standard encoding table 7. Note that the same coding rule as when using the standard coding table 7 is applied when the non-standard coding table 8 is used.

The encoding / decoding unit 6 selects one of the standard encoding table 7 and the standard encoding table 8 to be used according to a command from the system control unit 1. Further, the operator issues a command from the system control unit 1 by operating the operation display unit 4.

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 is for modulating and demodulating 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 is for connecting a facsimile device to the public telephone line network. Is. The network control device 11 has an automatic call originating / receiving function.

Also, a system control unit 1, a scanner 2, a plotter 3,
The operation display unit 4, the image memory 5, the encoding / decoding unit 6, and the communication control unit 9 exchange data with each other via the system bus 12.

A case of transmitting image information using this facsimile device will be described. In the following description, the facsimile machine shown in FIG. 1 is used for both the transmitter and the receiver.

When the transmission image information is highly confidential, the operator of the transmission device sets the transmission original on the scanner 2 and inputs the destination information, and then transmits the image in the encryption mode from the operation display unit 4. Order.

Therefore, the system controller 1 of the transmitter first
The destination information is transferred to the network control device 11 to call the destination.

As a result, when the transmission path is established between the transmitting device and the receiving device, the receiving device identifies the called station identification signal CED for indicating that the own terminal is a facsimile device, and the non-standard equipment provided in the own terminal. A non-standard device signal NSF for notifying such a function and a digital identification signal DIS for notifying a standard function provided in the terminal itself are sequentially transmitted to the transmitting device. In addition, the non-standard device signal NSF includes information indicating that the non-standard coding table 8 is provided.

As a result, the transmitting device knows that the receiving device is equipped with the non-standard encoding table 8. Therefore, encoding using the non-standard encoding table 8 is performed by transmitting the non-standard device instruction NSS. Notify the receiving device. This non-standard device command NSS includes setting information of other functions for transmitting image information.

Then, the transmitting device transmits the training check TCF for training the modem 10 at the transmission speed of the image information set at that time. When the reception result of the training check TCF is good, the reception device returns a reception preparation confirmation signal CFR.

As a result, the system control unit 1 of the transmission device instructs the encoding / decoding unit 6 to use the non-standard encoding table 8 and sets the operation mode of the encoding / decoding unit 6 to the encoding mode. Then, the scanner 2 is operated to read the image of the transmission original, the image signal is encoded by the encoding signal conversion unit 6, and then the image information PIX communication control unit 9 is used.
And send it to the transmission line.

On the other hand, the system control unit 1 of the receiving device instructs the encoding / decoding unit 6 to use the non-standard encoding table 8 and sets the operation mode of the encoding / decoding unit 6 to the decoding mode. Then, after the received image information is decoded into the original image signal by the encoding / decoding unit 6, the image signal is sequentially transferred to the plotter 3, and the plotter 3 records and outputs the received image.

When the transmission of the image information PIX is completed, the transmission device transmits the procedure end signal EOP, and the reception device responds with the message confirmation signal MCF. This causes the transmitter to disconnect the line disconnection signal DC
After sending N, the line is disconnected and the image information transmission ends. The receiving device also disconnects the line and ends the image information transmission.

In this way, when the encryption mode is set in the transmitting device, the non-standard coding table 8 is selected in the transmitting device and the receiving device. Therefore, for example, even if the wiretapping device eavesdrops on the transmission line, Since the image information cannot be properly reconstructed by the eavesdropping side facsimile apparatus, the confidentiality of the image information can be maintained.

Also, for example, when the operator mistakenly inputs the destination information and connects to the receiving device that does not have the function of the non-standard coding system, the transmitting device determines that the receiving device has the function of the non-standard coding system. The transmission can be interrupted when it is learned that it does not have it.

If the operator does not specify the encryption mode, the system control unit 1 instructs the encoding / decoding unit 6 to use the standard encoding table 7. in this case,
The non-standard device instruction NSS does not include information indicating that the non-standard encoding table 8 is used for encoding.

Therefore, when the operator does not specify the encryption mode, the image information can be transmitted to the facsimile device which does not have the non-standard encoding table 8.

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 non-profiling rule as the standard coding method for the non-standard code because the coding / decoding unit can be used in common.

Further, even if the operator does not specify the encryption mode, the nonstandard coding table may be used when it is determined that the receiving device has the nonstandard coding function.

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 the above-described embodiment includes both the non-standard coding table and the standard coding table, the confidentiality of the transmission image information can be maintained even when only the non-standard coding table is provided. .

[Effect] As described above, according to the present invention, image information is CCIT
In the facsimile transmission method that performs coding compression based on the standard encoding table compliant with the T recommendation, a non-standard code replacement table in which a part of the coding table compliant with the CCITT recommendation is replaced Non-standard coding selection means for selectively inputting to code and compress information, and at the time of transmission, coding compression of image information using the non-standard coding table is selected by the non-standard coding compression selection means. If the other terminal notifies that the non-standard coding table is provided,
While transmitting the image information coded and compressed using the non-standard coding table to the partner terminal, the image information transmission is stopped when the partner terminal notifies that the non-standard coding table is not provided. Since the information transmission means is provided, it is possible to obtain the effect of appropriately transmitting highly confidential image information.

[Brief description of drawings]

FIG. 1 is a block diagram showing a facsimile apparatus according to an embodiment of the present invention, and FIG. 2 is a time chart showing an example of transmission control. 1 ... System control unit, 4 ... Operation display unit, 6 ... Encoding / decoding unit, 8 ... Non-standard encoding table.

Claims (1)

(57) [Claims] 1. A non-standard encoding table in which a part of the encoding table conforming to the CCITT recommendation is replaced in a facsimile transmission system in which image information is encoded and compressed based on the standard encoding table conforming to the CCITT recommendation. Non-standard encoding selecting means for the user to selectively input to encode and compress image information using the non-standard encoding table; and the non-standard encoding by the non-standard encoding compression selecting means during transmission. When encoding compression of image information using the table is selected, when the other terminal notifies that the non-standard encoding table is provided, the compression compression is performed using the non-standard encoding table. While transmitting the image information to the partner terminal, when the partner terminal notifies that the non-standard coding table is not provided, the transmission of the image information is stopped A facsimile transmission method comprising means.