JPH08116423A - Facsimile equipment - Google Patents

Abstract

PURPOSE: To minimize a size of a re-transmission frame by inserting page number information and block number information into an image information frame to be sent. CONSTITUTION: Image information is transferred in a form of an FCD frame. The FCD frame adopts an HDLC frame structure and an identification code in one byte representing the FCD frame is in existence to a head of its I(information) field, and then page number information in one-byte, block number information in one-byte, frame number information in one byte, and an image information area in 256-bytes are in existence succeedingly in the frame. The FCD frame is sent from a transmission terminal equipment and even when a 2nd block 131-th frame is received next to a 1-block 130-th frame, since it is discriminated that 13- to 255-th frames of 1st block and 0 to 130-th frames of 2nd block are not received, a re-transmission request may be made for the frames of the concerned sections by means of a PPR command.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile machine, and more particularly to a transmission control system in a facsimile machine for transmitting image information in frame units.

[0002]

2. Description of the Related Art Conventionally, as a facsimile transmission method, a transmission control method for analog lines, which is called G3 protocol, has been widely used. The G3 protocol is configured to send the next block (page) after confirming that one block (page), which is a transmission unit of image information, has been correctly transmitted. In this regard,
For example, Japanese Examined Patent Publication (Kokoku) No. 5-48013 discloses a full-duplex error retransmission control method, which is also 1
This is a proposal of an error retransmission method within a block. While I
There is G4 protocol as a transmission method for SDN line,
This enables high-speed transmission, but requires expensive hardware to realize high-speed processing. Therefore,
In 1993, ITU-T Recommendation T. 30, newly ANN
EXC (G3C) recommendations have been added. The G3C is a method of transmitting image information in frame units with a frame number indicating the order within a block (page) using a digital line, and the transmission procedure is based on G3 (ECM). And in G3C, MCF and PPR
It is stipulated that the next block can be sent without receiving a response command such as.

[0003]

When the G3C protocol as described above is used, a post message command (PPS ...
NULL) and post message command between pages (P
Even if the PS / MPS) cannot be received, the sender facsimile sends the next block. Therefore, if the post message command or image information frame is destroyed due to noise, etc., in the receiving facsimile, is the received frame the same block as the frame received immediately before, or the frame of the next block? In some cases, it cannot be determined based on the frame number alone, and received frames of different blocks may be stored in the same buffer. In such a case, the page number and block number of the post message command are inconsistent, and all the corresponding blocks are retransmitted, so that there is a problem that the communication time becomes long. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a facsimile apparatus that transmits image information in frame units and that can minimize the number of retransmission frames. .

[0004]

According to a first aspect of the present invention, there is provided a facsimile apparatus for transmitting image information divided by a page number and a block number dividing a page in a predetermined unit in a frame smaller than the block unit.
It is characterized in that it comprises means for generating image information frames by dividing the image information, means for inserting page number information and block number information in the image information frames, and means for transmitting the image information frames. A second aspect of the present invention is a facsimile apparatus that transmits image information divided by a page number and a block number that divides a page by a predetermined unit in a frame smaller than a block unit. Extraction means for extracting page number information and block number information, storage means for storing page number information and block number information of the image information frame received immediately before, comparison for comparing output of the extraction means and contents of the storage means Means and a storing means for storing the received image information in another buffer means when the comparison result does not match, and a resending request for making a resending request to the partner device based on the contents of the storing means and the output of the extracting means. And means.

[0005]

In the first aspect of the invention, since the page number information and the block number information are inserted in the image information frame to be transmitted, it is possible to know which page and block the frame is on the receiving side. It is possible to specify only the missing frame. Also, the second
In the invention, the page number information and the block number information are extracted from the received image information frame and compared with the page number information and the block number information of the image information frame received immediately before, and when the comparison result does not match. Since the received image information is stored in another buffer means and a resend request is made to the partner device, only a minimum required number of frames can be resent, and the communication time is shortened.

[0006]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of a facsimile apparatus to which the present invention is applied. The CPU 1 performs control processing of the entire facsimile apparatus, and the RAM 2 is a memory used as a work area for a control program.
The operation display device 3 is composed of an information input device including switches and the like mounted on the panel, and a display device of characters and figures using, for example, liquid crystal. The reading device 4 is a device that reads a document using a CCD image sensor or the like, and the printing device 5 is a device that prints image data. The image processing device 6 is a device that performs encoding / decoding of image data or enlargement / reduction processing. The image storage device 7 is a large-capacity memory for storing image data, and the ROM 8 is a non-volatile memory in which a program for controlling the entire facsimile is stored.

The communication control unit 1 (9) is a device for performing communication control (for example, G3C, G4) using a digital network, and the communication control unit 2 (10) is for communication control using an analog network (for example, G3). ) Is a device for performing. The digital network control device 11 is an interface circuit with a digital line such as ISDN. The modem 12 is a modulator / demodulator having a low-speed modem (V21) for facsimile transmission control signals and a high-speed modem (V27ter, V29, V33, V17, etc.) for transmitting and receiving image information. The analog network control device 13 is an interface circuit with an analog line such as a telephone network, and has an automatic call originating / receiving function. The bus 14 is for transferring data between each circuit in the device, and the line switching control device 15 is a device for selectively connecting a plurality of network control devices and an internal communication control device.

FIG. 1 is an explanatory diagram showing the format of an image information frame according to the present invention. In the above-mentioned G3C, all image information is transferred by the FCD frame as shown in FIG. This FCD frame has an HDLC frame structure, and at the beginning of its I (information) field, there is a 1-byte identification code indicating that it is an FCD frame, followed by 1-byte page number information,
There is 1-byte block number information, 1-byte frame number information, and 256-byte image information area.

FIG. 3 is a procedure diagram showing an example of a communication procedure according to the G3C protocol. When the terminals are connected, an XID (digital capability display including G3C) command is sent from the sending terminal, and subsequently, XID and DIS commands are repeatedly sent from the receiving terminal until a DCS command is received. With this, the negotiation is completed, and the FCD frame is transmitted from the transmitting terminal. F in the figure
The numbers in parentheses of the CD frame represent the page number, block number, and frame number from the left. In FIG. 1, up to the frame number 130 of the transmitted FCD frame is received by the receiving terminal, but after that, it is destroyed due to noise and the inter-block post message command P is received.
PS / NULL is not received either, 1 page 2 blocks 13
It is assumed that the data is received again from the first frame.

When such a situation occurs, if only the frame number is given as in the conventional case, the frame number 131 is received next to the frame number 130, so that the receiving terminal normally receives. It is regarded as a thing and stored in the same buffer. After receiving the inter-page post message command PPS / MPS, 2
It is known that up to the block has been transmitted, but since it is unknown which frame is up to the first block, it is necessary to retransmit all from the first block. According to the method of the present invention, when the second block, the 131st frame, is received after the 1st block, the 130th frame, the first block 131-255 and the second block 0-
Since it is found that the 130th frame has not been received, it is only necessary to request retransmission of that part of the frame by the PPR command.

FIG. 4 is an explanatory view showing the structure of the receiving buffer in the facsimile to which the present invention is applied. G3C
In the case of (1), if the data amount of one page is 64 kilobytes or more, the data is divided into blocks every 64 kilobytes and transmitted. Since one frame consists of 256 bytes, the maximum number of frames in one block is 256. The receive buffer is configured to store data in block units, and corresponds to a 64-kilobyte image information buffer, a 1-byte page number storage area, a 1-byte block number storage area, 5 bytes (= 256 bits). There is a receiving frame map storage area of). In the page number and block number area, the page and block number to which the buffer is assigned is written. Each bit in the reception frame map storage area corresponds to the frame number, and is set to 0 when the frame is normally received.

When the procedure as shown in FIG. 3 is executed, the received data of FIG. 3a is stored in the image information buffer of the buffer 1 of FIG. 4 corresponding to the block number 1, and the received data of FIG. The reception data of b corresponds to the block number 2 of FIG.
Stored in the image information buffer of the buffer 2. Therefore, it is found that the data in the portions (c) and (d) of FIG. 4 are not received, and the receiving side facsimile sends the received frame map information (P) of each buffer to the PPR command.
(Q) is inserted and responded, and a resend request is made.

FIG. 5 is a flow chart showing the processing of the facsimile apparatus on the transmitting side according to the present invention. Step S1
In step S, the called facsimile is called, and step S
In 2, PN (page number) is 1, BN (block number) is 1, FN (frame number is 0, PMA
Set P (map for transmission page or block) to all 0s. In step S3, a negotiation about the transmission method is performed, and in step S4, the FCD frame for transmitting the image information is PN,
BN, FN, and image information are set to generate an FCD frame, which is transmitted in step S5. Step S
In 6, it is determined whether or not a response signal from the facsimile of the other party is received, and if the result is negative, the process proceeds to step S10. In step S10, it is determined whether or not it is a block end, and if negative, the process proceeds to step S11, and it is determined whether or not it is a page end. Then, if the result is negative, the process proceeds to step S12. In step S12, it is determined whether or not it is the document end. If the result is negative, in step S17 F
N is incremented by 1 and the process returns to step S4 to send the next FCD frame.

If it is the block end in step S10, the process proceeds to step S18 and the inter-block post message command PPS.NULL is transmitted.
In step S19, BN is incremented by 1 and FN is set to 0. In step S20, PMAP
The corresponding bit of is set to 1. In step S21, if retransmission processing is necessary, it is retransmitted, and in step S21.
Return to 4. If it is the page end in step S11, the process proceeds to step S22, and the inter-page post message command PPS / MPS is transmitted. In step S23, PN is incremented by 1, BN and FN are both set to 0, and the process proceeds to step S20. When a response is received in step S6, the process proceeds to step S7. In step S7, it is determined whether or not retransmission is necessary, that is, whether or not the response is a PPR (partial page request) command, and the result is affirmative. In that case, the process proceeds to step S9, and the retransmission flag indicating that retransmission is necessary is turned on. The actual retransmission processing is performed in step S21 after the block or page end. Response is MC
If there is no need to retransmit with the F command, step S8
Then, the corresponding bit of PMAP is reset to 0. If it is the document end in step S12, the process proceeds to step S13, the PPS / EOP command is transmitted, and in step S14, the corresponding bit of PMAP is set to 1. In step S15, the process waits until the response signals for all the transmitted pages or blocks are received, and if necessary, the retransmission process is performed.

FIG. 6 is a flow chart showing the processing of the receiving side facsimile apparatus according to the present invention. Step S
In step 30, an incoming call is detected, and in step S31, PN (page number) is set to 0, BN (block number) is set to 0, a frame counter is set to 0, and RMAP (reception page or block correspondence map) is set. Set all to 1, respectively. In step S32, a negotiation regarding the transmission method and the like is performed. In step S33, it is determined whether or not an FCD frame is received, and if it is received, the process proceeds to step S34 and the FCD receiving process described later is performed. In step S35,
It is determined whether or not PPS / NULL is received, and if negative, the process proceeds to step S36, and it is determined whether or not PPS / MPS is received. If the result is negative, the process proceeds to step S37, it is determined whether PPS / EOP is received, and if the result is negative, the process returns to step S33.

In step S35, PPS / NULL
If it is received, the process proceeds to step S41, and it is determined whether or not there is a missed reception due to an error or the like of a frame in the block. If the result is affirmative, the process proceeds to step S47. The process moves to S42, and the currently opened reception buffer is closed. In step S43, BN is 0 and frame counter is 0.
And the MCF command is transmitted in step S44. On the other hand, if there is a frame reception failure in the block, the process proceeds to step S47, the frame counter is set to 0, and in step S48, the PPR in which the reception frame map (RMAP) data of FIG. 4 is inserted.
The command is sent. In step S36, the PPS
If the MPS command is received, step S45
In, it is determined whether there was an error in the frame,
If there is an omission due to an error, the process proceeds to step S47, but if not, the process proceeds to step S46, PN is set to 0, and the process proceeds to step S42. P in step S37
When PS / EOP is received, it is determined in step S38 whether or not there is an error in the frame. If there is a gap due to an error, the process proceeds to step S47, but if not, the process proceeds to step S39. The reception buffer is closed in step S39, and the MCF command is transmitted in step S40.

FIG. 7 is a flow chart showing details of the FCD receiving process in step S34 of FIG. Step S
At 50, it is determined whether PN is 0, that is, the frame is the first frame of the page. If the result is affirmative, the process proceeds to step S51, and the page number in the received frame is set to PN. In step S52, the block number in the received frame is set to BN. In step S53, one free buffer among the buffers shown in FIG. 4 is selected and the reception buffer is opened, and in step S54, PN is stored in the page number area and BN is stored in the block number area. .
In step S55, the frame number is read from the frame, and in step S56, the image information in the received frame is written in the image information buffer at the position corresponding to the frame number read in step S55.
The frame counter is incremented by 1 in step S57, and the corresponding bit of RMAP is set to 0 (received state) in step S58.

If PN is not 0 in step S50, the process proceeds to step S59, it is determined whether BN is 0, and if the result is affirmative, the process proceeds to step S52. Control goes to step S60. In step S60, it is determined whether or not the page number in the received frame is equal to PN. If negative, the process proceeds to step S62, but if positive, step S6.
Move to 1. In step S61, it is determined whether the block number in the received frame is equal to BN,
If the result is affirmative, the process proceeds to step S55, but if the result is negative, the process proceeds to step S62. In step S62, it is determined whether or not the frame counter is 0. If it is 0, the process proceeds to step S51 without sending PPR, but if it is not 0, the process proceeds to step S63.
Insert the RMAP data into the PPR frame. And
The PPR command is transmitted in step S64, and the process proceeds to step S51. With the above-described processing, the receiving facsimile can detect missing frames, and can request retransmission of the minimum necessary frames.

[0019]

As described above, in the first aspect of the invention, the page number information and the block number information are inserted in the image information frame to be transmitted. Therefore, it is possible to identify only the missing frame, and thus it is possible to take appropriate measures. Further, in the second invention, the page number information and the block number information are extracted from the received image information frame and compared with the page number information and the block number information of the image information frame received immediately before. If they do not match, the received image information is stored in another buffer means and a resend request is sent to the partner device, so that all normally received frames are effectively saved and the minimum required Only the frame can be requested to be retransmitted, and the communication time can be shortened.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a format of an image information frame of the present invention.

FIG. 2 is a block diagram showing a configuration of a facsimile apparatus to which the present invention is applied.

FIG. 3 is a procedure diagram showing an example of a communication procedure according to the G3C protocol.

FIG. 4 is an explanatory diagram showing a structure of a reception buffer in the facsimile of the present invention.

FIG. 5 is a flowchart showing a process of a transmitting side facsimile apparatus according to the present invention.

FIG. 6 is a flowchart showing a process of the receiving side facsimile apparatus according to the present invention.

FIG. 7 is a flowchart showing details of FCD reception processing.

[Explanation of symbols]

1 ... CPU, 2 ... RAM, 3 ... Operation display device, 4 ... Reading device, 5 ... Printing device, 6 ... Image processing device, 7 ... Image storage device, 8 ... ROM, 9 ... Communication control unit 1, 10 ... Communication Control unit 2, 11 ... Digital network control device, 12 ... Modem, 13
... Analog network control device, 14 ... System bus, 15 ... Line switching control device

Claims (2)

[Claims] 1. A facsimile apparatus for transmitting image information divided by a page number and a block number obtained by dividing the page by a predetermined unit in a frame smaller than the block unit, and generating the image information frame by dividing the image information. And a means for inserting page number information and block number information in the image information frame, and a means for transmitting the image information frame. 2. A facsimile apparatus for transmitting image information divided by a page number and a block number obtained by dividing a page by a predetermined unit in a frame smaller than the block unit, the page number information from the received image information frame. And extraction means for extracting the block number information, storage means for storing the page number information and block number information of the image information frame received immediately before, and comparison means for comparing the output of the extraction means with the contents of the storage means.
If the comparison result does not match, the storage means for storing the received image information in another buffer means, and the resend request means for making a resend request to the partner device based on the contents of the storage means and the output of the extraction means. A facsimile machine characterized by being provided.