JP2823565B2 - Facsimile machine - Google Patents

Description

The present invention relates to a flag sequence, an address field,
The present invention relates to a facsimile apparatus that transmits image information by using an HDLC frame including a control field, a facsimile control field, a facsimile information field, and a flag check sequence.

[Prior Art] A facsimile apparatus that transmits image information in accordance with an error correction mode (hereinafter abbreviated as ECM) of the G3 standard recommended by CCITT has been put to practical use.

This ECM uses HDLC (High Level Data Link Control)
l) By the data frame of the procedure, image information of up to 64 Kbytes is transmitted as one block at a time.

As shown in FIG. 6, a data signal for transmitting the image information of one block includes a synchronization signal portion in which a number of flag sequences F are arranged, an encoding information portion in which the image information is set, and an image information portion. Is completed and a return information section indicating return to the transmission control procedure. The encoded information section is composed of up to 256 frames FCDF0 to FCDFn, and the return information section is composed of three frames RCPF1 to RCPF3.

Each of the frames FCDFi and RCPFi is formed in the data format of the HDLC frame. Each frame FCDFi is composed of a flag sequence F, an address field A, a control field C, a facsimile control field FCF, a facsimile information field FIF, a frame check sequence FCS, and a flag sequence F.

In each of the above fields, except for the facsimile information field FIF, the facsimile control field FCF, and the frame check sequence FCS,
Each is 1-byte data. Flag sequence F
Is used to identify the beginning and end of the frame.
The data is “0111 1110”. In facsimile communication, since address designation is not required, in a facsimile apparatus using a normal telephone line network, the address field A is set to all "1" data.

The control field C indicates the last frame in the coded information section and the return information section, and is set to "1100 1000" in the last frame and "1100 0000" in other frames.

The facsimile control field FCF indicates the type of the frame. In the encoding information section, information "FCD" indicating an image information frame is set, and in the return information section, information "RCP" indicating the end of the image information is set. "Is set.

The facsimile information field FIF
Only in the frame of the encoded information part, a frame number No. from 0 to 255 and an encoded image information CD having a fixed number of bytes of 256 bytes or 64 bytes are set. In the case of the last frame FCDFn, after the image information CD, R
All "0" dummy data for setting the TC code and the data to be set to the above-mentioned constant bit is set.

The frame check sequence FCS has a 2-byte CR for detecting a transmission error of each data of the frame.
C code is set.

In ECM, the sender can use up to 256 frames with the above frame configuration.
The coded image information is set in each of the frames, that is, the frames FCDF0 to FCDF255, and transmitted at one time. The receiving side checks a transmission error using a CRC code for each frame FCDFi, notifies the transmitting side of the frame number in which the error has been detected, and receives retransmission.

By the way, in recent years, facsimile communication using a wireless line such as a car telephone is often performed. In the case of a wireless line, the line state deteriorates and a transmission error easily occurs. When communication is performed by the ECM under such conditions, the retransmission operation is repeated many times.

[Problems to be Solved by the Invention] As is clear from FIG. 6, in the ECM, a large number of frame data in addition to the image information is transmitted in order to transmit the image information by the HDLC frame of a fixed format.

For example, if one block of image information of 256 frames is transmitted, frames FCDF0 to FCDF255 and frame
By combining RCPF1 to RCPF3, 259 address fields A and control fields C, which are not related to image information, are transmitted at a time, and the total number of bits of each of them is 4144 bits.

Therefore, for example, if data is transmitted at a data transmission speed of 4800 bps, the transmission time T of the two fields is T =
4144/4800 = 0.863, about 0.9 per block above
Useless data is transmitted per second.

For this reason, compared with the case where image information is transmitted as it is in the normal G3 standard, it takes time to transmit a data signal, and in particular, in the case where the line condition is deteriorated, as in the case of the car phone, the retransmission operation is repeated. However, there is a problem that the transmission time becomes long. In addition, in the case of a car phone, the communication fee is higher because the call charge is higher than that of a normal phone.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile apparatus which can solve the above-mentioned problems and reduce communication time.

Means for Solving the Problems The present invention provides a flag sequence, an address field,
In a facsimile apparatus for transmitting image information by an HDLC frame comprising a control field, a facsimile control field, a facsimile information field, and a flag check sequence, a shortened frame obtained by removing an address field and a control field in the HDLC frame, or the HDLC If the receiving side has a function of transmitting the shortened frame, and the receiving side has a function of transmitting the shortened frame, the image information transmitting mode using the shortened frame is designated to the receiving side, and the image Transmission control means for designating the information transmission means to perform image information transmission using the shortened frame, and at the time of image information reception, when the image information transmission mode using the shortened frame is designated by the transmission side, The above image Those having a reception control means for designating to perform image information received with the shortened frame to the transmission means.

[Operation] Therefore, by applying the image information transmission mode using the shortened frame, the data length of the transmission data can be reduced, and as a result, the transmission time can be greatly reduced.

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

FIG. 1 shows a block diagram of an in-vehicle facsimile system according to one embodiment of the present invention. In the figure, a facsimile apparatus 1 is connected to a car telephone apparatus 3 via an interface circuit 2, and a handset 4 for a telephone call and a predetermined operation of the car telephone is connected to the interface circuit 2.

In the facsimile machine 1, a scanner 11 reads a document image and extracts image information of a predetermined resolution, and a plotter 12 records the image information on a recording sheet. The encoding / decoding section 13 encodes image information to be transmitted and decodes received image information. The image memory 14 temporarily stores image information of one block to be transmitted and received.

The modem 15 modulates and demodulates image information and transmits the same, and also transmits various procedure signals in a transmission control procedure. The communication control section 16 executes transmission control by the ECM to execute predetermined facsimile communication. In the present embodiment, in addition to transmitting the image information using the same HDLC frame as that of the related art, the image information has a shortened frame transmission function of transmitting a shortened frame in which some fields in one frame are removed.

The operation display unit 18 displays the operation state of the apparatus and the like and performs various operations. The system control unit 19 includes a microcomputer system,
Each of the above-described units is controlled to execute a predetermined operation of the facsimile machine.

Next, a case where original images are transmitted and received between the in-vehicle facsimile systems of this embodiment will be described.

In this case, each of the operators on the transmitting side and the receiving side discusses that a document image is to be transmitted by a telephone call on the handset 4 and presses a transmission or reception button on the operation display unit 17.

Thereby, a predetermined transmission control procedure by the ECM is executed. That is, the receiving side first sends out the CED signal and the NSF.DIS signal as shown in FIG.

By the way, in the CCITT recommendation, NS of the above NSF.DIS signal
In the case of transmitting information of 128 bits in the F frame and the NSS frame of the NSS.DCS signal, allocation of information of each bit is defined. According to this rule, the 17th to 24th bits are specified in the manufacture code, and for example, the 122nd to 126th bits are unused. Therefore, in this embodiment, the company code is set by the manufacture code, and the presence or absence of the shortened frame transmission function is indicated by using, for example, one bit of the 122nd bit.

The receiving side notifies the NSF.DIS signal that it has the shortened frame transmission function (process 101).

As shown in FIG. 3, when the transmitting side receives the NSF.DIS signal (Y in step 201), it determines whether or not the receiving side has the shortened frame transmission function (step 20).
2). If the receiving side has the transmission function (Y in step 202), the operation mode is set to the “shortened frame mode”, and the NSS.DCS signal is transmitted to notify the other party of the operation mode. (Process 203).

When the NSS signal is transmitted (Y in process 102) and the “shortened frame mode” is specified (Y in process 103), the receiving side sets the operation mode to “shortened frame mode” (process 104).

Thereafter, modem training or the like is performed between the transmitting side and the receiving side, and the transmitting side transmits image information using a predetermined data signal.

FIG. 4 shows the frame structure of the data signal in the "shortened frame mode". The difference from FIG. 6 is that the address field A and the control field C in each frame FCDFi and RCPFi are removed. Is a point.

On the receiving side, as shown in FIG. 5, data signals having the above-described frame configuration are sequentially received, and the received data is temporarily stored in a data buffer (not shown) (step 30).
1).

Next, the HDLC frames are discriminated and read frame by frame (process 302), and the data of each frame is checked by the CRC code of the frame check sequence FCS (process 303). If the frame data is correct (Y in step 303), the facsimile control field FCF is read (step 304). If the facsimile control field FCF is "FCD" (processing 3
From N of 04, processing 305, Y of processing 305), the frame number of the facsimile information field FIF is read (processing 306), and the image information CD is read and stored in the image memory 14 (processing 307). Then, the next frame is read (to process 302).

Thus, the image information CD of each frame FCDFi is read.

On the other hand, if a data error is detected (N in process 303) or the facsimile control field FCF is neither “FCD” nor “RCP” (N in process 305), the frame data is not read. Then, the next frame is read (process 302).
What).

In this way, next, when "RCP" of the facsimile control field FCF is detected (Y in step 304),
It is determined that the image information of one block has been completed. In this case,
Since “RCP” is set in each of the frames RCPF1 to RCPF3, it is normally detected three times. However, in consideration of a transmission error, it is determined that the image information has been completed if it is detected even once.

Next, it is determined whether there is an error frame in which a transmission error has occurred. That is, for example, one of the frames FCDF
In i, if the data check by the CRC code results in an error, and if the facsimile control field FCF is neither “FCD” nor “RCP”, the process 30
6, the process 307 has not been executed. Therefore, at the end of the image information of one block, an error frame is determined by checking the frame number No that has not been extracted (process 308). In the figure, for example, the frame RCP
If a CRC error occurs in F3, the data signal reception wait state is left (processing 302 from N in processing 303). If a data signal is not received for a certain period of time in this state, a routine (not shown) for shifting to processing 308 is provided. ing.

Here, if there is an error frame (Y in process 308), a PPR signal is transmitted to request retransmission of the error frame (process 309), and the retransmitted data signal is similarly received (to process 301).

In addition, when reception is possible without an error frame (step 308).
N), the image information of each frame is decoded, and the received image is recorded (process 310).

The transmitting side and the receiving side execute transmission of image information in a predetermined transmission procedure as described above (FIG. 2, process 105, FIG. 3, process 204).

On the other hand, when a document is transmitted to a conventional facsimile apparatus not having the shortened frame transmission function, the receiving side first transmits only the DIS signal or the NSF.DIS signal.

Here, when the NSF signal is not received (N in process 201), the conventional "normal mode" for transmitting image information in the frame configuration shown in FIG. 6 is set (process 205). Further, even if the NSF signal is received (Y in processing 201), in this case, since the shortened frame transmission function is not specified (processing 202).
N), similarly, the “normal mode” is set (process 205). Then, the normal mode is notified by only the DCS signal or the NSS.DCS signal (FIG. 3, processing 20).
5) The image information is transmitted in a predetermined procedure (process 204).

When an image is received from a conventional facsimile machine, if the NSS signal is not received (N in process 102), the mode is immediately set to the "normal mode" (process 106). Further, even if the NSS signal is received (Y in process 102), in this case, since the shortened frame transmission function is not specified (N in process 103), the mode is similarly set to the “normal mode” (process 106). Then, the image information is received in a predetermined procedure (process 105).

Also in this case, the image information is received by the processing shown in FIG.

As described above, in the present embodiment, when the “shortened frame mode” is set, the image information CD is transmitted in a frame configuration in which the address field A and the control field C in the HDLC frame are removed.

As a result, the data amount of the data signal for transmitting the image information is reduced. For example, when the image information of one block is 256 frames and the data transmission speed is 4800 bps, the above-described transmission time of about 0.9 seconds is reduced.

As described above, the transmission time of the data signal is shortened, and the communication time is shortened compared to the related art. In this case, the effect of shortening the communication time increases as the number of frames decreases and as the number of repetitions of the retransmission process increases.

In addition, by shortening the communication time, the communication cost can be reduced in the case of a car phone whose call charge is higher than that of a normal phone. Furthermore, conventionally, when data in the address field A or the control field C causes a transmission error, the data is retransmitted as an error frame. However, in the present embodiment, since these are removed, the frequency of occurrence of the error frame decreases. Become like

In each of the above embodiments, when both the transmitting side and the receiving side have the transmission function using the shortened frame, the transmission is always performed in the “shortened frame mode”. May be performed.
Also, in the case of the "normal mode", the reception processing shown in FIG. 5 is executed. However, in the case of the "normal mode", the address field A is obtained by a known technique.
It is needless to say that the image information CD may be taken out by discriminating the control field C from the control field C.

Also, the case where image information is transmitted using the G3 standard ECM has been described. However, the present invention can be similarly applied to a case where image information is transmitted using an HDLC frame instead of the ECM. Not only facsimile machines connected to car phones,
It is needless to say that the present invention can be similarly applied to a case where connection is made to a normal subscriber telephone line or a wireless device.

[Effects of the Invention] As described above, according to the present invention, it is possible to apply the image information transmission mode using the shortened frame in which the address field and the control field in the HDLC frame are removed, and use the shortened frame. By applying the image information transmission mode, the data length of the transmission data can be reduced, and as a result, the transmission time can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an in-vehicle facsimile system according to an embodiment of the present invention, FIG. 2 is a schematic operation flowchart of a reception process, FIG. 3 is a schematic operation flowchart of a transmission process, and FIG. FIG. 5 is an operation flowchart showing a process of extracting image information from a data signal, and FIG. 6 is a conventional frame configuration diagram of a data signal transmitting image information. 1 ... facsimile machine, 2 ... interface circuit,
3 ... car phone device, 4 ... handset, 11 ... scanner, 12 ... plotter, 13 ... encoding / decoding unit, 14 ...
... Image memory, 15 ... Modem, 16 ... Communication control unit, 18 ...
... Operation display unit, 19 ... System control unit.

Claims (1)

(57) [Claims] A flag sequence, an address field,
In a facsimile apparatus for transmitting image information by an HDLC frame including a control field, a facsimile control field, a facsimile information field, and a flag check sequence, a shortened frame in which the address field and the control field in the HDLC frame are removed, or
An image information transmitting means for transmitting image information using the HDLC frame, and, if the receiving side has a function of transmitting a shortened frame, designating an image information transmitting mode using the shortened frame to the receiving side; A transmission control unit for designating the image information transmitting unit to perform image information transmission using the shortened frame, and an image information transmission mode using the shortened frame is designated by the transmitting side when receiving image information. A facsimile apparatus comprising a reception control unit for designating the image information transmission unit to receive image information using the shortened frame.