JPH01173970A - Transmission system for facsimile equipment - Google Patents

Abstract

PURPOSE:To shorten a time required for a transmission control procedure at the time of using an error correction mode by setting the size of map information to inform a transmission error corresponding to the number of frames which constitute a block transmitted from a transmission side. CONSTITUTION:When a receiver detects a reception error, a re-transmission request is issued to the frame in which the reception error is generated, and a transmitter transmits a data frame to which the re-transmission request is issued again, and by repeating such operation as needed, the receiver can record and output a reception image accurately. However, since a function to set the number of bytes of error map data EMp' arranged in a signal PPR corresponding to the number of frames is not a reference function, it is decided whether or not such function is used by the transfer of the signal NSF of a procedure before transmission and a signal NSS. In such a way, it is possible to shorten the time required for a transmission procedure in the case of setting the number of frames less than 248.

Description

[Detailed description of the invention] [Technical field] The present invention relates to a transmission system for a facsimile machine.

[Prior art] When transmitting image information using a facsimile device, if a transmission error occurs in the image information received by the receiving device, such as when the line condition is poor, the receiving device cannot reproduce accurate image information. .

Therefore, each manufacturer has conventionally produced a facsimile machine equipped with its own error correction function, and by using such a facsimile machine, error-free image information transmission can be realized.

However, in such a method unique to a manufacturer, an error correction function cannot be applied because there is no compatibility between models made by different manufacturers.

For this reason, the CCITT (International Telegraph and Telephone Consultative Committee) has established a standard system for error correction mode in order to eliminate such situations in Recommendation T, 30, which specifies the functions of Group 3 facsimile equipment. It is proposed in the form of an annex (Annex A).

In this recommendation, the image information after encoding and compression is divided into two parts from the beginning.
56 bytes (octets; 1 byte (=i octet)
= 8 bits) or 64 bytes each, and the picture information for one frame is divided into HDLC (High Level Data Link Control) procedure formats, as shown in Figure 5(a). It is transmitted in a formatted frame FLM.

Here, this frame FLMlt, a (head) flag sequence F consisting of a predetermined bit pattern, an address field A consisting of a predetermined bit pattern (global address), a control field C1 consisting of a bit pattern unique to the facsimile machine, an information field 1. Frame check sequence FC5 for error detection, and
(Tail) Formed by sequentially waving flags F.

The information field I includes a facsimile control field FCF in which a facsimile transmission procedure signal is placed, and a facsimile information field PIF in which various information added to the facsimile transmission procedure signal is placed.

In this case, the facsimile control field FCF contains facsimile encoded data F of the facsimile transmission procedure signal.
The CD is placed, and the facsimile information field PIF contains a frame number FNo that indicates the frame order,
Encoded frame data FDc of one frame size FSZ is arranged.

Also, since the frame number FNo is an 8-bit binary number, it can only take serial numbers from 0 to 255, so 256 consecutive frames are set as one block, and the block receiving side requests retransmission. ing. Furthermore, if one page's worth of image information cannot be transmitted in one block, the remaining portion is set in the next block and transmitted.

When requesting retransmission, the receiving side sends a message as shown in (b) of the same figure.
A frame of a facsimile transmission procedure signal PPR (partial page request signal) is responded to the transmitting side. Although the facsimile transmission procedure signal includes necessary parameters and is exchanged in the same frame format as the partial page request signal PPR, in the following description, it will be simply referred to as a signal PPR, for example.

This signal PPR is connected to its facsimile control field F
A bit pattern (PPR) indicating that the signal is PPR is placed in CF, and 256-bit error map data EMp is placed in facsimile information field PIF.

This error map data EMρ assigns data rQJ to frames in which no transmission error occurred, and data "1" to frames in which a transmission error occurred, among the transmitted frame data for 9 minutes. Arranged in frame order.

Upon receiving this signal PPR, the transmitting side retransmits only the frame data of the frame in which data rlJ is set in the error map data EMp to the receiving side.

By repeating this retransmission request until transmission errors in all frames are resolved, it is possible to record and output an error-free received image on the receiving side.

However, such an error retransmission method has the following disadvantages.

In other words, the size of image information for one page is generally smaller than the set block size, for example, 5
The size is such that it can be transmitted with 0 frame data.

On the other hand, the signal PPR that the receiving side responds to from the transmitting side is, as mentioned above, because the size of the error map data EMp is fixedly set to 256 bits (=32 bytes).
Data other than the part that is actually needed (in the above case,
206 bits) are wasted, and invalid data is also responded, resulting in the disadvantage that the time required for the transmission control procedure becomes longer.

[Objective] 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 transmission method for a facsimile machine that can shorten the time required for transmission control procedures when using error correction mode. There is.

[Configuration] In order to achieve this object, the present invention sets the size of map information for notifying a transmission error according to the number of frames constituting a block transmitted by the transmitting side.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

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

In the figure, a CPU (central processing unit) 1 is for controlling the entire facsimile machine and facsimile transmission control procedures, and its control program is stored in a ROM (read-only memory) 2. The work area and transmission buffer are in RAM.
(Random Access Memory) 3. Note that the transmission buffer has a storage capacity of at least 64 bytes (K=1024) so that one block of frames of maximum 256 bytes can be stored.

The scanner 4 is for reading a transmitted original at a predetermined resolution, and the plotter 5 is for recording and outputting a received image at a predetermined resolution.

The operation display unit 6 is used to operate this facsimile machine, and the parameter memory 7 is used to store various parameters such as speed dial information set uniquely to this facsimile machine, and is a non-volatile memory. It consists of a storage device.

The encoding/decoding unit 8 encodes and compresses the transmitted image signal, and decodes the received image information into the original image signal.
The modem 9 modulates and demodulates digital data so that an analog network such as the public telephone line can be used as a transmission line, and the network control bag c10 is for connecting the facsimile device to the public telephone line. It is.

Note that this network control device 10 is equipped with an automatic call/call function.

Also, CPU i, ROM 2, RAM 3, scanner 4
, plotter 5, operation display section 6, parameter memory 7, encoding/decoding section 8, modem 9, and network control device 10 exchange data with each other via a system bus 11.

Now, in the error correction mode, when one block of image information is transmitted, the transmitting side sends a signal PP5 (Partial Page Sig) as shown in FIG. 2(a).
nal)・Q to the receiving side immediately thereafter. In this case, Q is set to EOP, which indicates the end of the procedure.

This signal PP5-EOP sends a bit pattern (PPR) to the facsimile control field FCF.
) and EOP are arranged, and a page counter PC, a block counter 8C1, and a frame counter FC are arranged in the facsimile information field PIF.

Here, the page counter PC is cleared to 0 at the beginning of communication, and is incremented each time the transmission of image information for one page is completed, and the block counter BC is cleared to 0 at the beginning of the page. , is incremented each time the transmission of image information for one block is completed, and the content of the frame counter FC is set to the number of frames of image information transmitted at that time minus 1. .

Therefore, on the receiving side, by checking the contents of the frame counter FC of the signal PP5-Q received following the picture information for one block, it is possible to know the number of frames constituting the received block.

That is, as shown in FIG. 3, on the receiving side, when one block of image information is completed, it is checked whether a reception error has occurred (determination 101), and the result of determination 101 is Y.
When it becomes ES, the frame counter F of the signal PPS
Based on the value of C, the following equation (1) is calculated, and the facsimile information field PIF of the signal PPR notifying reception error is
The size (in bytes) of the error map data EMp' to be placed in is calculated.

EMP″= [(FC)/8] (1) Here, operator [x] is the largest integer not exceeding X.

For example, if the size of one block is 50 frames and the value of the frame counter FC is 49.

The size of the error map data EMp' is 7 bytes (56
bit).

When the size of the error map data EMp' is calculated in this way, the frame data of the signal PPR as shown in FIG. 2(b) is processed 103) and transmitted. It is stored in a buffer for transmitting a procedure signal (processing 104). Note that this buffer for transmitting a transmission procedure signal is formed in the RAM 3.

Then, it starts transmitting the frame data of the signal PPH (process 105), and waits for the transmission to end (judgment 10).
6), the process moves to image information reception processing.

In this way, the number of bytes of the error map data EMp' of the signal PPR that responds to the transmitting side is set according to the size of the image information block actually received, and the transmission procedure signal is 300 bps (V , 21 modem function), the time required for the transmission procedure can be reduced by the time T given by the following equation (II), compared to the transmission method specified in the Supplement to Recommendation T, 30. .

T = (32-([(FC)/8]+1))/(30
0/8) ... (II) That is, the number of frames is 2
48 or less, the time required for the transmission procedure can definitely be shortened.

Assume that in the above configuration, the operator of the transmitting apparatus sets the original to be transmitted on the scanner 4 and inputs the destination from the operation display section 6 to start transmission.

However, in this case, the number of originals to be transmitted that the operator has set in the scanner 4 is one, and the size of the image information obtained by encoding and compressing the image recorded on it is less than 64 bytes, and is 1 It must fit in the block.

Further, the facsimile device designated as the destination has the same functions as the transmitting device. Note that the operations of both the transmitting device and the receiving device are controlled by the CPUI, but in the following description, the operations will be described as those of the transmitting device and the receiving device.

As a result, the transmitting device calls the receiving device, and the receiving device, which detects the incoming call, responds with a hail signal CHD indicating that its own terminal is a non-voice terminal, as shown in FIG.
The standard functions and optional functions that your terminal has,
The transmitter is notified by the signal DIS and the signal NSF, respectively.

The transmitting device notifies the receiving device of the function to be used at that time using the signal NSF, and also performs a training check TCP.

If the training result is good, the receiving device responds with a signal CFR to the transmitting device, and the transmitting device thereby starts transmitting the image information PIX.

At this time, the transmitting device causes the scanner 4 to read the image of the transmission document, encodes and compresses the image signal obtained thereby in the encoder/decoder 8, and frames the image information obtained thereby in the above-mentioned format. The formatted data is stored in a transmission buffer formed in the RAM 3, and the frame data stored in the transmission buffer is transferred to the modem 9 and modulated, and then transmitted from the network control device 10 to the receiving device.

When the transmission of the image information PIX for one page is completed, the signal PPS and the signal EOP to notify the end of transmission are transmitted.

On the other hand, the receiving device stores the received image information in the RAM 3 and refers to the error detection code FC3 to determine whether a data error has occurred in each data frame.

When the receiving device detects that a data error has occurred in one or more frames based on the check result of the frame check sequence FC3 of each frame, the receiving device responds with a partial page request signal PPR as described above and transmits the partial page request signal PPR. Notify the device of the data frame in which a received data error has been detected. In addition, at this time, the signal PP corresponds to the frame counter FC of the signal PPS by the processing described above.
Set the number of bytes of error map data EMp' to be placed in R.

When the signal PPR is answered, the transmitting device
The image information PIXr consisting only of data frames with frame numbers greater than or equal to 1 is retransmitted), and after the transmission is completed, the signals PPS and EOP are transmitted.

When the receiving device is able to receive the image information PIXr without data error, it responds with a signal MCF.

As a result, the transmitting device confirms that the image information transmission has ended normally, sends the signal DCN to the receiving device, disconnects the line, and ends the image information transmission.

In this way, when the receiving device detects a reception error,
A retransmission request is made for the frame in which the reception error occurred, and the transmitting device retransmits the data frame for which retransmission was requested,
By repeating this as many times as necessary, the receiving device can record and output accurate received images.

By the way, the function of setting the number of bytes of the engineer data EMp' arranged in the signal PPR according to the number of frames of the image information block is not a standard function, so it is not possible to use such a function. , determined by the exchange of signals NSF and NSS in the pre-transmission procedure.

[Effects] As explained above, according to the present invention, the size of map information for notifying transmission errors is set according to the number of frames constituting a block transmitted by the transmitting side, so error correction mode cannot be used. This has the effect of reducing the time required for transmission control procedures.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a facsimile apparatus according to an embodiment of the present invention, FIG. 2(a) is a signal arrangement diagram illustrating the signals PPS and EOP, and FIG. 2(b) is a signal arrangement diagram illustrating the signal PPR. 3 is a flowchart showing an example of processing when responding with signal PPR, FIG. 4 is a time chart showing an example of a transmission procedure, and FIG. 5(a) is a frame when transmitting framed image information. A schematic diagram illustrating the format of the signal PPR. FIG. 2B is a schematic diagram illustrating a conventional example of the signal PPR. 1...cpu (central processing unit), 2...ROM
(Lead-on 1.1-, J Mori), 3...RAM
(Random Access Memory). Fig. 1 1), Ω Fig. 3 (l!!! J Kiitari C I6zuri, j!) Fig. 4

Claims (1)

[Claims] Error retransmission divides one page's worth of image information into multiple frames and transmits the frames in block units to the receiving side, and also retransmits the frame data of the transmission error frame notified by the receiving side to the receiving side. In the transmission method of a facsimile machine equipped with this function, a map size calculation means is provided to calculate the size of map information specifying transmission error frames based on the number of frames notified from the transmitting side, and configures a block transmitted by the transmitting side. A transmission method for a facsimile machine, characterized in that the size of map information for notifying a transmission error is set according to the number of frames transmitted.