JP2945017B2 - Control system for facsimile equipment - Google Patents

Description

The present invention relates to a control system for a facsimile machine.

[Prior Art] When transmitting image information with a facsimile machine, if a transmission error occurs in the image information received by the receiving device, such as when the line condition is bad, the receiving device can reproduce accurate image information. Can not.

Therefore, conventionally, each manufacturer has realized a facsimile apparatus having an original error correction function, and by using such a facsimile apparatus, it is possible to realize error-free image information transmission.

However, with such a manufacturer-specific method, there is no compatibility between models of different manufacturers, so that the error correction function cannot be applied.

To eliminate this situation, the CCITT (International Telegraph and Telephone Consultative Committee) has added a new standard for error correction mode (error correction mode) to Recommendation T.30, which defines the functions of Group 3 facsimile machines. Added and proposed.

In this recommendation, the image information after encoding and compression is
256 bytes (octets; 1 byte (= 1 octet) =
(8 bits) or a frame size of 64 bytes, and the image information of one frame is divided into frame FLMs in the form of HDLC (high-level data link control) procedure as shown in FIG. It is transmitted in a state where it is formatted as follows.

Here, the frame FLM includes a (head) flag sequence F composed of a predetermined bit pattern, an address field A composed of a predetermined bit pattern (global address), a control field C composed of a bit pattern unique to the facsimile apparatus, and an information field. I, a frame check sequence FCS for error detection, and a (tail) flag F are sequentially arranged.

The information field I includes a facsimile control field FCF in which a facsimile transmission procedure signal is arranged, and a facsimile information field FIF in which various types of information added to the facsimile transmission procedure signal are arranged.

In this case, the facsimile control field FCF contains a facsimile transmission procedure signal FCD (Facsimile Coded Data).
Are arranged in the facsimile information field FIF, and a frame number FNo indicating a frame order and encoded frame data FDc of one frame size FSZ are arranged.

Also, since the frame number FNo is composed of an 8-bit binary number, only a serial number from 0 to 255 can be taken. Therefore, continuous 256 frames are set as one block, and a retransmission request is made from the receiving side in block units. Like that. If the image information for one page cannot be transmitted in one block, the remaining part is set in the next block and transmitted.

At the time of a reproduction request, the receiving side transmits a facsimile transmission procedure signal PPR (Partial Page Request) as shown in FIG.
est) to the sender. The facsimile transmission procedure signal is exchanged in the same frame format as the partial page request signal PPR in a state including necessary parameters, but in the following description, for example,
Simply referred to as signal PPR.

This signal PPR is transmitted to the facsimile control field FC.
F, a bit pattern (PP
R) is placed in the facsimile information field FIF 256
Bit error map data EMp is arranged.

The error map data EMp includes data “0” for a frame in which a transmission error has not occurred and data “1” for a frame in which a transmission error has occurred among the transmitted frame data of one block. , Arranged in frame order.

Upon receiving this signal PPR, the transmitting side transmits again only the frame data of the frame in which the data “1” is set in the error map data EMp to the receiving side.

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

By the way, when the state of the transmission path is poor, retransmission requests for the same block may be continuous, and in such a case, it is very difficult to eliminate transmission errors of all frames under the same transmission conditions.

In order to solve such a situation, the above-mentioned recommendation takes the following measures.

That is, for example, when the retransmission request is repeated three times, the transmitting side sends a signal CTC (Continue To Correct) to notify the receiving side that the transmission speed is reduced by one step (shift down), and the receiving side transmits the procedure signal CTR. (Respons for CTC), when the downshift is accepted, the next retransmission data is transmitted at the downshifted transmission rate.

In this way, by reducing the transmission speed, transmission errors are suppressed and transmission errors can be eliminated.

[Problems to be Solved by the Invention] However, in such a conventional method, since transmission conditions other than the transmission speed do not change before and after downshifting, transmission errors are not sufficiently suppressed and the transmission speed is reduced. For this reason, there has been a problem that the transmission time is long.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such disadvantages of the related art, and has as its object to provide a control method of a facsimile apparatus capable of shortening image information transmission time when using an error correction mode.

Means for Solving the Problems The present invention divides image information for one page into a plurality of frames, transmits the frames to the receiving side in a unit of a plurality of blocks, and transmits the information notified from the receiving side. In a control method of a facsimile apparatus having an error retransmission function of retransmitting frame data of an error frame to a receiving side,
A plurality of transmission buffers capable of storing image information of one block are provided, and at the time of transmission, when transmission of image information of one block is completed, image information of the next block is formed before a reception result is returned from the receiving device. When started, the image information is stored in an empty area of the plurality of transmission buffers.

Further, the image information for one page is divided into a plurality of frames, and the frames are transmitted to the receiving side in a unit of a plurality of blocks, and the frame data of the transmission error frame notified from the receiving side is retransmitted to the receiving side. In a control method of a facsimile apparatus having an error retransmission function, a plurality of transmission buffers capable of storing image information of one block are provided, and at the time of reception, the received image information is stored in an empty area of the transmission buffer. It is determined whether or not an error has occurred in the frame data of the received image information. Immediately after the reception of the image information of one block is completed, the error determination of the data frame is completed, and before the received image information is decoded. In response to normal reception to the transmitting side, and the image information transmitted thereby is stored in an empty area of the plurality of transmission buffers. It is.

[Operation] Therefore, at the time of transmission, the image information of the next block is created without waiting for the notification of the reception result, so that the transmission time can be reduced, and as a result, the transmission efficiency can be improved. Further, at the time of reception, a response to normal reception is made at the earliest point, so that the transmission time can be shortened, and as a result, transmission efficiency can be improved.

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

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

In FIG. 1, a CPU (central processing unit) 1 is for performing control processing of the entire facsimile apparatus and facsimile transmission control procedure processing, and its control program is stored in a ROM (read only memory) 2. The work area and the transmission buffer are stored in a RAM (random access memory) 3. The transmission buffer has a storage capacity of at least 64 Kbytes (K = 1024) so that one block consisting of a maximum of 256 256-byte frames can be stored.

The scanner 4 is for reading a transmission 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 for operating the facsimile apparatus, and the parameter memory 7 is for storing various parameters such as shortened dial information set uniquely for the facsimile apparatus. It consists of a storage device.

The encoding / decoding unit 8 encodes and compresses the transmission image signal and decodes the received image information into the original image signal. The modem 9 uses a public telephone line network or the like which is an analog line network as a transmission line. It modulates and demodulates digital data so that it can be used, and the network controller 10 is for connecting the facsimile apparatus to a public telephone network.

The network controller 10 has an automatic transmission / reception function, and a transmission line is connected to the modem 9 via the network controller 10.

The CPU 1, the ROM 2, the RAM 3, the scanner 4, the plotter 5, the operation display unit 6, the parameter memory 7, the encoding / decoding unit 8, the modem 9, and the network control device 10 are mutually necessary data via the system bus 11. Are exchanging.

 FIG. 2A schematically shows the modem 9.

The modem 9 is provided with an auxiliary equalizer 9a having characteristics as shown in the graph of FIG. 2B and compensating for the high-frequency characteristics of the receiving line.

Use / non-use of this function is set by a switch 9b that is switched and controlled by the modem main part 9b.

In the configuration described above, it is assumed that the operator of the transmitting apparatus has input a destination from the operation display unit 6 and started transmission in a state where the transmission document is set on the scanner 4. However, in this case, the number of transmission originals set by the operator on the scanner 4 is one, and the size of image information obtained by encoding and compressing an image recorded thereon is 64 Kbytes or less, and
Shall fit in a block.

The transmitting device and the facsimile device designated as the destination have the same functions as those of the facsimile device shown in FIG.

Thereby, the transmitting device calls the receiving device, and the receiving device that has detected the incoming call, as shown in FIG. 3, applies the signal CED indicating that the own terminal is a non-voice terminal,
Standard and optional functions provided by your device,
The transmission device 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 performs a training check.
Perform TCF.

In the receiving device, if the training result is good,
The transmitting device responds to the transmitting device with the signal CFR, thereby starting transmitting the image information PIX.

At this time, the transmitting device causes the scanner 4 to read the image of the transmitted document, encodes and compresses the image signal obtained by the encoding and decoding unit 8, and converts the obtained image information into frame data of the format described above. The frame data is stored in a transmission buffer formed in the RAM 3 in a state where the frame data is shaped, 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 ends, the signal EOP is transmitted without indicating the signal PPS and the transmission end.

On the other hand, the receiving device stores the received image information in the RAM 3, and determines whether or not a data error has occurred in each data frame by referring to the error detection code FCS.

When the receiving apparatus detects that a data error has occurred in one or more frames based on the check result of the frame check sequence FCS of each frame,
In response to the PPR, the transmitting apparatus is notified of the data frame in which the reception data error has been detected.

When the signal PPR is responded, the transmitting device transmits the designated 1
Image information PIXr consisting of only data frames of one or more frame numbers is transmitted (retransmission), and after the transmission is completed, the signal PPS,
Send EOP.

The transmitting device responds with the signal MCF when the image information PIXr can be received without data error.

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

In this manner, when the receiving device detects a reception error, the receiving device requests a retransmission of the frame in which the reception error has occurred, and the transmitting device transmits the retransmitted data frame again, and repeats it as necessary. The receiving device can record and output an accurate received image.

By the way, when retransmission of image information is repeated more than a certain number of times for the same block, as described in the section of the related art, when the transmitting side sends out the signal CTC and the receiving side responds to the signal CTR, the image is sent. Downshifting is performed to lower the information transmission speed by one step.

Here, generally, the high-speed modem function of the modem 9 includes V.
29 and V.27ter modems are used.

The V.29 modem has a modulation speed of 2400 baud and a reference transmission speed of 9600 bps. The transmission speed (fallback speed) after the downshift of 9600 bps is set to 7200 bps.

The V.27ter modem has a modulation speed of 1600 baud and a reference transmission speed of 4800 bps, and the transmission speed (fallback speed) after the downshift of 4800 bps is set to 2400 bps.

Therefore, when shifting down from the transmission speed of 9600 bps, 7200 bps, 4800 bps, and 2400 bps
The transmission speed changes step by step.

On the other hand, the V.29 modem and the V.27ter modem use different frequency bandwidths, and the energy distribution at both ends (1 KHz or less and 2.6 KHz or more) of the transmission signal band of the V.29 modem is V Greater than that of a .27ter modem.

Therefore, if the transmission line has a large attenuation in the high-frequency band and transmission errors continue, transmission errors often cannot be improved by downshifting from 9600 bps to 7200 bps, and similarly, downshifting from 4800 bps to 2400 bps. Even so, transmission errors often cannot be improved.

Therefore, in the present invention, a shift-down occurs when image information is transmitted in the error correction mode, and further, when a transmission error occurs, the degree of improvement of the transmission error before and after the shift-down is examined. When not so large, the auxiliary equalizer 9a is used to compensate for the high-frequency band, so that the degree of improvement of the transmission error can be improved.

That is, when receiving the image information of one block, the receiving apparatus performs the processing shown in FIG.

First, image information is received in a state where the auxiliary equalizer 9a is not used (process 101), and it is checked whether or not a transmission error has occurred in the received data (decision 102).

When the result of the determination 102 is YES, the frame error rate Pa as a result of dividing the number of error frames by the total number of received frames is calculated (process 103), and the transmitting apparatus is notified of the frame in which the error has occurred. A signal PPR is transmitted to request retransmission (process 104).

As a result, when only the image information of the frame in which the error has occurred is retransmitted from the transmitting side, it is received (process 105), and it is checked whether or not a reception error has occurred during this retransmission (determination 106).

When the result of the judgment 106 is YES, it is checked whether or not a downshift is set with the transmitting device at that time to reduce the image information transmission speed by one step (decision 107).
If the result of the determination 107 is NO, the process returns to the process 104 to re-execute the retransmission request.

If the result of determination 107 is YES, that is, if retransmission of image information is repeatedly performed until the downshift, the frame error rate Pb after the downshift is calculated (processing 108). An error improvement rate R obtained by dividing Pb by the frame error rate Pa is calculated (step 109), and it is checked whether the error improvement rate R is smaller than a fixed value T (decision 110).

When the result of the determination 110 is YES, the frame error occurs more than a certain value even if the downshift is performed, and the effect of the downshift is not obtained so much. Equalizer 9a
Are set (step 111), and the process returns to step 104 to request retransmission.

When the result of the determination 110 is NO, it means that the effect of the downshift has been obtained to some extent, so that the auxiliary equalizer 9a is kept in the non-use state (process 112).
Returning to the process 104, a retransmission request is made.

When the result of the judgment 102 is NO, and when the judgment 1
If the result of step 06 is NO, the process shifts to preparing for receiving the image information of the next block in response to the signal MCF (processing 11
3).

In this way, when the downshift is performed without easily removing the transmission error of the image information, whether or not the improvement rate (error improvement rate R) of the frame error rate before and after the downshift is larger than the constant value T If it is not large, the effect of the downshift does not appear and the characteristics of the transmission line are significantly degraded in the high frequency band.Therefore, set the auxiliary equalizer 9a to the use state and degrade the high frequency band of the line. , The subsequent retransmission request is made.

Further, when the error improvement rate R is larger than the fixed value T, the effect of downshifting has appeared, so that the retransmission request operation of the image information is repeated as it is.

Accordingly, an optimal image information receiving operation can be performed according to the state of the line, and the time required for image information transmission can be reduced.

In addition, except when the effect of the auxiliary equalizer 9a appears particularly, the use of the auxiliary equalizer 9a has been discontinued,
Therefore, the auxiliary equalizer 9a can be used effectively, and overcompensation by the auxiliary equalizer 9a can be limited.

In the above-described embodiment, the auxiliary equalizer 9a is always used. However, by controlling the use / non-use of the auxiliary equalizer according to the retransmission situation, it is possible to control the line characteristics to an appropriate one.

FIG. 5 shows a process executed when the receiving apparatus receives one block of image information in another embodiment of the present invention.

That is, first, before receiving the image information, the auxiliary equalizer 9a is separated by the switch 9c and set to an unused state (process 201).

In this state, one block of image information is received (step 20).
2) At that time, it is checked whether a reception error is detected (decision 203).

If a reception error is detected and the result of determination 203 is YES, an error occurrence rate Pe obtained by dividing the number of frames in which the reception error has occurred by the number of received frames is calculated (step 20).
4), the error rate Pe determine whether greater than a predetermined value T _P (decision 205).

When the result of the determination 205 is YES, there is a possibility that a reception error may occur even at the time of retransmission, so the switch 9c is switched to set the auxiliary equalizer 9a to the use state (processing 206).
In this state, a retransmission request is made to the transmitting side (process 207).

When the result of the determination 205 is NO, the process shifts to the process 207 while keeping the auxiliary equalizer 9a in the unused state, and requests the transmitting side to retransmit.

In this way, when a retransmission request is made, the frame requested by the transmission side is retransmitted, and is received (processing 20).
8) At that time, it is checked whether a reception error has occurred (decision 209).

When the result of the determination 209 is YES, the error occurrence rate Pe ′ obtained by dividing the number of error occurrence frames by the total number of received frames at the time of retransmission is calculated (processing 210), and the error occurrence rate Pe is calculated using the error occurrence rate Pe ′. The error improvement rate R obtained by the division is calculated (process 211).

Then, it is checked whether the error rate of improvement R is smaller than the predetermined value T _R (decision 212), the result of decision 212 YE
At the time of S, since the compensating action of the high frequency characteristic by the auxiliary equalizer 9a is not effectively acting, the switch 9c
To switch the auxiliary equalizer 9a to the unused state (processing
213) When the result of the determination 212 is NO, the effect of the auxiliary equalizer 9a has been sufficiently exhibited, so that the auxiliary equalizer 9a is used (the process 213 is not performed), and the process returns to the process 207 to retransmit. Execute the request repeatedly.

When the result of the judgment 203 is NO, and when the judgment 2
When the result of 04 is NO, since no reception error has occurred in the image information received at that time, the signal MCF is responded (processing 214), and the state shifts to the reception state of the next block.

Here, the predetermined value T _P and a constant value T _R, is a value obtained empirically.

In this manner, the first time more than one frame has occurred a reception error in received image information, since the error rate Pe is using an auxiliary equalizer 9a is greater than a predetermined value T _P, the line The retransmitted image information is received in a state where the high-frequency characteristics are compensated, whereby the probability of occurrence of a reception error at the time of retransmission can be suppressed.

When the effect of the auxiliary equalizer 9a does not appear, the use of the auxiliary equalizer 9a is stopped, and therefore, the auxiliary equalizer 9a can be used effectively.

In each of the embodiments described above, the auxiliary equalizer is provided only on the receiving side of the modem. However, the present invention can be applied to a case where a modem provided with the auxiliary equalizer on both the transmitting side and the receiving side is used.

Further, in the above-described embodiment, the retransmission termination is not performed on the transmission side when the retransmission request is continuous, but the present invention can be applied to the case where the retransmission termination is performed.

Also, the characteristics of the auxiliary equalizer are not limited to those described above, and two types of auxiliary equalizers are provided, one corresponding to the multi-stage link and the other corresponding to the cable length from the facsimile apparatus to the exchange. Also, the present invention can be applied.

FIG. 6 shows a facsimile apparatus according to still another embodiment of the present invention. In FIG. 6, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

In the figure, the reception signal input terminal of the modem 9 is directly connected to the reception signal output terminal of the network controller 10, and the modem 9
And the transmission signal input terminal of the network control device 10 are connected to the common terminals of switches 20, 21 having four switching terminals, respectively.

The first switching terminals of the switches 20, 21 are directly connected to each other, and the second, third, and fourth switching terminals are connected via equalizers 22, 23, 24 for compensating for the high-frequency characteristics of the transmission line. Each is interconnected.

The equalizers 22, 23, and 24 have different frequency characteristics, for example, the equalizer 23 has a higher degree of high-frequency band compensation than the equalizer 22, and the equalizer 23 has a higher degree of compensation than the equalizer 23.
14 is configured to have a higher degree of compensation in the high frequency band.

Therefore, when the switches 20 and 21 are selecting the first switching terminal, the transmission signal output terminal of the modem 9 is directly connected to the transmission signal input terminal of the network controller 10 and the switching devices 20 and 2 are connected.
When 1 selects the second, third, and fourth switching terminals, equalizers 22, 23, and 24 are inserted between the transmission signal output terminal of the modem 9 and the transmission signal input terminal of the network controller 10, As a result, the transmission signal is transmitted from the modem 9 in a state where the frequency band of the high frequency band of the transmission line can be compensated.

With the above configuration, when this facsimile apparatus calls another facsimile apparatus and performs image information transmission in the same procedure as in FIG. 2 using the error correction mode,
FIG. 7 shows a processing example executed by the CPU 1.

That is, first, the switches 20 and 21 are caused to select the first switching terminal, and the image information of one block and the signal PPS.Q are transmitted without using any of the equalizers 22, 23 and 24 (processing 301, 302), it is checked whether a retransmission request has been responded from the receiving side (decision 303).

Then, it is determined whether or not the retransmission status at that time satisfies the equalizer insertion condition (determination 304).

When the equalizer insertion condition is satisfied and the result of the determination 304 is YES, it is determined whether any of the equalizers 22, 23, and 24 has already been used at that time (determination 30).
Five).

None of the equalizers were used and the result of decision 305 is NO
, The switches 20 and 21 are caused to select the second switching terminal, and the equalizer 22 is inserted into the transmission path.
6) In this state, retransmission image information including a frame requested by the receiving device is transmitted (process 307).

If any of the equalizers is used and the result of decision 305 is YES, it is determined whether the inserted one is equalizer 12 (decision 308), and if the result of decision 308 is YES, The switches 20 and 21 select the third switching terminal, and insert the equalizer 23 into the transmission path (processing
309), the process proceeds to 307, and the retransmission image information is transmitted in that state.

When the result of the determination 308 is NO, the switches 20 and 21 are made to select the fourth switching terminal, the equalizer 24 is inserted into the transmission path (processing 130), and the processing shifts to processing 307, in which state the image is retransmitted. Submit information.

When the result of the determination 304 is NO, the immediate processing 307
Then, the retransmission image information is transmitted as it is.

Then, it is checked whether or not a retransmission request has been made for the retransmission image information transmitted in the process 307 (determination 311). When the result of the determination 311 is YES, the process returns to the determination 304 and executes the process of shifting.

When the result of the determination 303 is NO, and when the determination 3
When the result of step 11 is NO, since the image information transmitted at that time has been normally received, it is checked whether there is an image information block that has not been transmitted (decision 312), and the result of decision 312 is NO. In some cases, the process returns to step 301 to transmit the image information of the next block.

When the result of determination 312 is YES, the transmission process ends.

Here, the equalizer insertion condition may use, for example, a condition that the number of retransmissions exceeds a certain value, that the number of retransmission frames exceeds a certain value, or that the retransmission frame rate exceeds a certain value. it can.

In this way, according to the retransmission situation, whether or not to insert an equalizer in the transmission path, and the equalizer to be inserted can be selected, so that the frequency characteristics of the transmission line are deteriorated. When a transmission error occurs, the frequency characteristics of the transmission line can be appropriately compensated, and the occurrence of the transmission error can be greatly reduced.

As a result, image information transmission can be continued without reducing the transmission speed, and the frequency of retransmission requests is reduced, so that transmission efficiency is greatly improved.

By the way, in the above-described embodiment, the characteristic of the equalizer to be used is sequentially switched every time a certain equalizer insertion condition is satisfied, but the equalizer to be used is changed according to the number of retransmissions or the number of retransmission frames in a certain period. Can also be set.

Further, in the above-described embodiment, one of the three equalizers is selectively used. However, these equalizers can be used in combination, or four or more equalizers can be used.

In the above-described embodiment, the frequency characteristics of the equalizer applied to the transmission path are changed by selectively using three equalizers having fixed frequency characteristics. It can also be used to switch its characteristics as appropriate.

In the above-described embodiment, an independent equalizer is used. However, an equalizer built in a modem can be used. In this case, an increase in device cost can be suppressed.

Further, in the above-described embodiment, the equalizer is used on the transmitting side, but when the equalizer is used on the receiving side, and
Even if the equalizer is used for both the transmitting side and the receiving side,
The present invention can be applied.

By the way, when transmitting image information using such an error correction mode, a transmission buffer for storing transmission image information is required, and conventionally, the capacity of this transmission buffer is one block of image information. Since the size is set to a value that can be stored, the following inconvenience occurs.

For example, in a case where the image information for one page does not fit in one block but spans two blocks, the image information is transmitted according to the procedure shown in FIG.

That is, when the operator of the transmitting apparatus sets the transmission original and sets the destination, the destination is operated and transmission is started, and the transmitting apparatus calls the receiving apparatus.

After receiving a call, the receiving device responds with a signal CED indicating that the terminal is a non-voice terminal, and then receives standard functions, optional functions, and identification information of the terminal itself. Is the signal DIS,
The transmitting device is notified by the signal NSF and the signal.

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

In the receiving device, if the training result is good,
The transmitting device responds to the transmitting device with the signal CFR, whereby the transmitting device transmits the image information of the first block of the set transmitting original.
Form PIX1, store it in the transmission buffer and send it to the receiving device.

Then, when the transmission of the image information PIX1 is completed, a signal PPS.NULL is transmitted to notify that there is a subsequent block forming the same page.

On the other hand, the receiving device stores the received image information PIX1 in the transmission buffer, determines whether a data error has occurred in each data frame by referring to the error detection code FCS, and further, receives the received image information PIX1. The operation of decoding and recording is performed.

When the signal PPS.NULL is received, the reception of the image information of one block is completed, it is determined that there is a subsequent block of the same page, and the decoding processing of the image information PIX1 has not been completed at that time. At this time, when it is determined that no data error has occurred in all the data frames, a signal RNR is returned to the transmitting device.

Upon receiving the signal RNR, the transmitting device transmits the signal RR without performing the image information PIX2 of the next block.

The receiving apparatus responds to the signal RNR upon receiving the signal RR until the decoding processing is completed, and upon receiving the signal RR after the decoding processing is completed, a signal MCF indicating that the message has been normally received. To the transmitting device.

As a result, the transmitting device transmits the image information PIX2 of the next block.
Start sending.

In this way, the so-called flow control is performed, in which the transmission of the image information of the next block or the next page is waited until the decoding processing in the receiving device is completed.

However, when this flow control is performed, there is a disadvantage that the transmission time of the image information is lengthened and the transmission efficiency is reduced.

Next, another embodiment of the present invention which can solve such a problem will be described.

FIG. 9 illustrates a facsimile apparatus according to another embodiment of the present invention. In this figure, the same parts as those in FIG. 1 and corresponding parts are denoted by the same reference numerals.
However, in this case, the auxiliary equalizer 9a of the modem 9 is always disconnected.

In the figure, a RAM 30 can be composed of n transmission buffers each having a capacity of 64 Kbytes, and furthermore, as shown in FIG.
Is provided.

With the above configuration, for example, as shown in FIG. 11, the size of the image information of the first page is divided into two blocks BL1 and BL2 with a size of about 200 Kbytes, and the image information of the second page is divided into one block BL3. Consider transmitting a two-page transmission manuscript. In the following description, the facsimile apparatus shown in FIG. 9 is used for both the transmitting apparatus and the receiving apparatus.

The operator of the transmitting device scans the two transmitted originals with the scanner 4
When the transmission is started by inputting a destination from the operation display unit 6 in the state of being set to, the transmitting device calls the receiving device.

After receiving a call, the receiving device responds with a signal CED indicating that the terminal is a non-voice terminal, and then receives standard functions, optional functions, and identification information of the terminal itself. Is the signal DIS,
The transmitting device is notified by the signal NSF and the signal CSI.

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

In the receiving device, if the training result is good,
In response to the signal CFR to the transmitting device, the transmitting device starts transmitting the image information PIX1 of the first block BL1 of the first page.

At this time, the transmitting device causes the scanner 4 to read the image of the transmitted document, encodes and compresses the image signal obtained by the encoding and decoding unit 8, and converts the obtained image information into frame data of the format described above. The frame data stored in the transmission buffer TB1 of the RAM 30 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 PIX1 of the first block BL1 of the first page is completed in this way, the signal PPS.
Send NULL.

Then, reading the next block BL2 on the first page,
Start encoding and convert the resulting image information PIX2 to RA
It is stored in the transmission buffer TB2 of M30.

On the other hand, the receiving device stores the received image information PIX1 in the transmission buffer TB1 of the RAM 30, and determines whether or not a data error has occurred in each data frame by referring to the error detection code FCS. Image information PIX1
Is decoded by the encoder / decoder 8 and then recorded and output from the plotter 5.

Here, the determination of the data error of the data frame of the receiving device is all finished immediately after the reception of the image information PIX1 is completed,
After this determination processing, the receiving device waits for a signal after the message to be transmitted from the transmitting device.

At this time, if it is determined that no data error has occurred in all the data frames, the signal PP from the transmitting device is output.
When S.NULL is received, it responds with the signal MCF.

Upon receiving the signal MCF, the transmitting device transmits the next block BL2
Is transmitted to the receiving device in the same manner as described above.

At the same time, when the image reading of the first page is completed, the transmitting apparatus starts image reading of the second page, forms the image information PIX3 of the block BL3, and stores it in the transmission buffer TB3 of the RAM 30.

When receiving the image information PIX2 of the next block BL2, the receiving device accumulates the image information PIX2 in the transmission buffer TB2 of the RAM 30 and detects an error in the data frame as described above.

At the same time, the receiving device executes the decoding and recording processing of the first block BL1 in parallel with the receiving processing, and starts the decoding and recording processing of the block BL2 when the recording of the image of the block BL1 ends.

When the transmission of the image information PIX2 ends, the transmitting device transmits a signal PPS.MPS notifying that there is a subsequent page.

The receiving device ends the data frame error detection process immediately after the reception of the image information PIX2, and waits to receive the signal after the message.When the signal PPS.MPS is received, all the signals are received at that time. If the data frame has been received without error, a signal MCF is returned to the transmitting device.

Upon receiving the signal MCF, the transmitting device transmits the image information PIX3 of the block BL3 on the second page to the receiving device in the same manner as described above, and upon ending the transmission, transmits a signal PPS.EOP indicating the end of transmission. .

The receiving device receives the received image information PIX3 in the same manner as described above.
Is stored in the transmission buffer TB3 of the RAM 30, and an error in the data frame is detected.

This data frame error detection ends immediately after the completion of the reception of the image information PIX3, and if all data frames have been received without error at that time, the signal PPS.EOP
At the time of receiving the signal, a signal MCF is returned to the transmitting device.

Upon receiving the signal MCF, the transmitting device transmits the signal DCN, disconnects the line, and ends the image information transmission.

When the recording of the received image of the first page is completed, the receiving apparatus decodes and records the image information PIX3, and
The image of the page is recorded and output from the plotter 5. At the same time, when the signal DCN is received, the line is disconnected and the receiving process is terminated.

In this way, the transmitting device can perform the reading and storing process of the document and the transmitting process of the image information in parallel, and the receiving device can perform the receiving process of the image information, the decoding and the recording process in parallel. Therefore, the time required for image information transmission is greatly reduced, and the transmission efficiency is significantly improved.

In the image information transmission example described above, the facsimile apparatus according to the embodiment of the present invention is used for the transmitting apparatus and the receiving apparatus, but the facsimile apparatus according to the embodiment of the present invention is used for either one of the transmitting apparatus and the receiving apparatus. The same effect can be obtained even in the case where it is performed.

Also, in the above-described image information transmission example, a case where no transmission error has occurred in the image information has been described. However, even when a transmission error occurs in the image information and a retransmission operation is performed, the effect of improving transmission efficiency is obtained. be able to.

[Effects of the Invention] As described above, according to the present invention, one page of image information is divided into a plurality of frames, and the frames are transmitted to the receiving side in a unit of a plurality of combined blocks. In a control method of a facsimile apparatus having an error retransmission function of retransmitting frame data of a notified transmission error frame to a receiving side, a plurality of transmission buffers capable of storing image information of one block are provided. When the transmission of the image information of the block is completed, the formation of the image information of the next block is started before the reception result is returned from the receiving apparatus, and the image information is stored in the empty area of the plurality of transmission buffers. Therefore, at the time of transmission, the image information of the next block is created without waiting for the notification of the reception result,
The transmission time can be reduced, and as a result, the transmission efficiency can be improved.

Further, the image information for one page is divided into a plurality of frames, and the frames are transmitted to the receiving side in a unit of a plurality of blocks, and the frame data of the transmission error frame notified from the receiving side is retransmitted to the receiving side. In a control method of a facsimile apparatus having an error retransmission function, a plurality of transmission buffers capable of storing image information of one block are provided, and at the time of reception, the received image information is stored in an empty area of the transmission buffer. It is determined whether or not an error has occurred in the frame data of the received image information. Immediately after the reception of the image information of one block is completed, the error determination of the data frame is completed, and before the received image information is decoded. Responds to the transmission side with normal reception, and stores the image information transmitted thereby in the empty area of the plurality of transmission buffers. , During reception, is performed at the earliest responses of normal reception, it is possible to shorten the transmission time. As a result, such an effect that the transmission efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a facsimile apparatus according to one embodiment of the present invention, FIG. 2 (a) is a block diagram showing a schematic configuration of a modem, and FIG. 1 (b) is a graph showing characteristics of an auxiliary equalizer. FIG. 3 is a time chart showing a state of image information transmission in an error correction mode, FIG. 4 is a flowchart showing a processing example at the time of image information reception, and FIG. 5 is an image information according to another embodiment of the present invention. FIG. 6 is a flowchart showing a processing example at the time of reception, FIG. 6 is a block diagram showing a facsimile apparatus according to still another embodiment of the present invention, and FIG.
8 is a flowchart showing an example of processing performed by the apparatus shown in FIG.
FIG. 9 is a time chart for explaining a conventional example of processing in the error correction mode, FIG. 9 is a block diagram showing another embodiment according to the present invention, and FIG. 10 is a schematic diagram showing a configuration example of a storage area of a RAM. FIG. 11, FIG. 11 is a schematic diagram showing an example of a transmission document, FIG. 12 is a time chart showing an example of a transmission procedure of the apparatus of FIG. 9, and FIG. 13 (a) transmits framed image information. FIG. 4B is a schematic diagram illustrating the frame format at the time, and FIG. 4B is a schematic diagram illustrating the frame format of the signal PPR. 1 CPU (central processing unit), 2 ROM (read only memory), 3, 30 RAM (random access memory), 9 modem, 9a auxiliary equalizer, 9b
Main part of modem, 9c, 20,21 ... Switch, 22,23,24 ... Equalizer.

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 63-12629 (32) Priority date January 25, 1988 (33) (33) Priority claim country Japan (JP) (58) Investigation Field (Int.Cl. ⁶ , DB name) H04N 1/32-1/34 H04L 1/00 H04L 1/08-1/24

Claims (2)

(57) [Claims] An image information for one page is divided into a plurality of frames, and the plurality of frames are transmitted to a receiving side in a unit of a plurality of blocks, and frame data of a transmission error frame notified from the receiving side is received. In a control method of a facsimile apparatus having an error retransmission function of retransmitting the image data, a plurality of transmission buffers capable of storing image information of one block are provided.
A facsimile apparatus control method characterized by starting formation of image information of a next block before a reception result is returned from a reception apparatus and storing the image information in an empty area of the plurality of transmission buffers. . 2. The image information of one page is divided into a plurality of frames, the frames are transmitted to the receiving side in a unit of a plurality of blocks, and the frame data of the transmission error frame notified from the receiving side is received. In a control method of a facsimile apparatus having an error retransmission function of retransmitting a block, a plurality of transmission buffers capable of storing image information of one block are provided, and upon reception, the received image information is stored in an empty area of the transmission buffer. At the same time, it is determined whether or not an error has occurred in the frame data of the received image information. Immediately after the reception of the image information of one block is completed, the error determination of the data frame is completed, and the received image information is decoded. Responding to the transmission side with normal reception before the transmission, and storing the image information transmitted thereby in an empty area of the plurality of transmission buffers. Control system of the facsimile apparatus according to claim.