JPH01295565A - Control system for facsimile equipment - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency by using an auxiliary equalizer to compensate the high frequency characteristic of a transmission line in response to the retransmission state or changing the characteristic of the auxiliary equalizer. CONSTITUTION:When a transmission error of picture information is not readily eliminated and shift-down is implemented, whether or not an improving rate of a frame error state before and after the event is larger than a prescribed value is checked. When not large, the auxiliary equalizer 9a is set to the operating state and while the deterioration in the high frequency band of the line is compensated, the succeeding retransmission request is applied. Then the optimum picture information is received corresponding to the line state and the time required for the transmission of picture information is reduced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a control method for a facsimile machine.

[Prior Art] When transmitting image information using a facsimile machine, 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 may not be able to reproduce accurate image information. Can not.

Therefore, each manufacturer has produced facsimile machines equipped with their own error correction functions.

By using such a facsimile device, 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.

In order to resolve this situation, the CCITT (International Telegraph and Telephone Consultative Committee) has introduced an error correction mode (
A standard system for error correction mode) has been newly added and proposed in Recommendation T, 30, which defines the functionality of Group 3 facsimile equipment.

In this recommendation, the image information after encoding and compression is divided into two parts from the beginning.
56 bytes (octets; 1 byte (=1 octet)
= 8 bits) or 64 bytes each, and the image information for one frame is shown in Figure 13 (a).
As shown in FIG. 3, the data is transmitted after being formatted into a frame FLM in the HDLC (High Level Data Link Control) procedure format.

Here, this frame FLM includes 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 E, Frame check sequence FC5 for error detection and (
(Tail) is 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 a facsimile transmission procedure signal FCD (FacsimileC
In the facsimile information field PIF, a frame number FNo for determining the frame order and encoded frame data FDc of one frame size FSX are arranged.

Also, since the frame number FNo is an 8-bit binary number, it can only take sequential numbers from θ to 255, so 256 consecutive frames are set as one block, and the receiving side requests retransmission for each block. That's what I do. 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.
Facsimile transmission procedure signal PPR (PartialPa
ge Request) frame 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 it is a signal PPR is arranged in the CF, and 256-bit error map data EMp is arranged in the facsimile information field PIF.

This error map data EMp assigns data "0" to frames in which no transmission error occurred among the transmitted one block of frame data, and data rlJ to frames in which a transmission error occurred. 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.

By the way, when the state of the transmission path is poor, retransmission requests for the same block may occur consecutively.

In such a case, it is extremely difficult to eliminate transmission errors in all frames under the same transmission conditions.

In order to eliminate this situation, the above-mentioned recommendations recommend taking the following measures.

That is, for example, when retransmission requests occur three times in a row, the transmitter sends a signal CTC (Continue To Corre).
ct) to notify the receiving side that the transmission speed will be reduced by one step (shift down), and the receiving side sends a procedure signal CTR.
(Respons for CTC) and accepts the downshifts, the next retransmission data is transmitted at the downshifted transmission speed.

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

[Problems to be Solved by the Invention] However, in such conventional methods, transmission errors are not sufficiently suppressed because transmission conditions other than transmission speed do not change before and after downshifting, and the transmission speed decreases. This has caused the inconvenience of increasing transmission time.

The present invention has been made to solve the problems of the prior art, and it is an object of the present invention to provide a control system for a facsimile machine that can shorten the image information transmission time when using the error correction mode.

[Means for Solving the Problems] In order to achieve this object, the present invention includes an auxiliary equalizer for compensating the high frequency characteristics of the transmission line, and depending on the retransmission situation, at least one of the transmitting side or the receiving side It determines whether or not to use the auxiliary equalizer, and changes the characteristics of the auxiliary equalizer.

[Effect] Therefore, the line characteristics are adjusted according to the retransmission situation, so the transmission error rate is reduced, and as a result, the frequency of retransmission requests is reduced without reducing the transmission speed, so the transmission efficiency is improved. .

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail 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) l 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. The capacity of the transmission buffer is set so that it can store one block consisting of a maximum of 256 256-byte frames.
A storage capacity of at least 64 bytes (K=1024) is secured.

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 line network such as a public telephone line can be used as a transmission line, and the network control device 10 is for connecting a facsimile device to the public telephone line network. It is.

This network control device 10 is equipped with an automatic call origination/reception function, and the transmission line is connected to the modem 9 via the network control device 10.

CPUI, ROM2, RAM3. Scanner 4, plotter 5, operation display section 6, parameter memory 7, encoding/decoding section 8, modem 9. The network control devices 10 exchange necessary data with each other via the system bus 11.

FIG. 2(a) shows an outline of the modem 9.

The modem 9 has the characteristics as shown in the graph shown in FIG. 2(b), and is provided with an auxiliary equalizer 9a for compensating for the high frequency characteristics of the receiving line.

The use/non-use of this function is set by a switch 9b which is switched and controlled by the modem main section 9b.

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.

Note that both the transmitting device and the facsimile device designated as the destination have the same functions as the facsimile device shown in FIG.

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 transmitted document, encodes and compresses the image signal obtained thereby in the encoder/decoder 8, and converts the image information thus obtained into frame data in the above-mentioned format. 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, it responds with a signal PPR to the transmitting device to detect a received data error. Notify the created data frame.

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, when image information is repeatedly retransmitted for the same block more than a certain number of times, as explained in the prior art section, when the transmitting side sends out the signal CTC and the receiving side responds with the signal CTR, the image is transmitted. A downshift is performed to reduce the information transmission speed by one step.

Here, in general, the high-speed modem function of the modem 9 includes v,
29 modem and V,27ter modem are used.

v,29 modem has a modulation rate of 2400 baud and a standard transmission rate of 9600 bps, and this 9600 bps
Transmission speed after downshifting of s (fall pack speed)
is set to 7200 bps.

Also, the V,27ter modem has a modulation rate of 1600
The standard transmission speed for baud is 4800 bps, and the transmission speed after this 4800 bps downshift (fall pack speed) is set to 2400 bps.

Therefore, when shifting down from a transmission speed of 9600 bps, the transmission speed is 7200 pbs, 4800 bps,
s, and the transmission rate changes step by step to 2400 bps.

On the other hand, the frequency bandwidth used by the V,29 modem and the V,27ter modem is different, and the energy distribution at both ends of the band (bands below IKHz and above 2.6KHz) of the transmission signal of the V,29 modem is as follows. V, 27ter
Bigger than that of a modem.

Therefore, if the attenuation in the high frequency band of the transmission line is large and transmission errors occur continuously, the speed will change from 9600 bps to 7
In many cases, even if you shift down to 200 bps, transmission errors cannot be improved;
In many cases, transmission errors cannot be improved even by downshifting to bps.

Therefore, in the present invention, a downshift occurs when image information is transmitted in error correction mode, and further,
When a transmission error occurs.

The degree of improvement in transmission error before and after downshifting is checked, and if it is not so large, the auxiliary equalizer 9a is used to compensate for the high frequency band, thereby improving the degree of improvement in transmission error. .

That is, when receiving one block of image information, the receiving apparatus performs the processing shown in FIG. 4.

First, without using the auxiliary equalizer 9a, image information is processed 101) to check whether a transmission error has occurred in the received data (determination 102).

When the result of judgment 102 is YES, the frame error rate Pa is calculated by dividing the number of error-occurring frames by the total number of received frames (process 103), and a signal is sent to notify the transmitting device of the error-occurring frame. A PPR is transmitted to request retransmission (process 104).

As a result, when only the image information of the frame in which the error occurred is retransmitted from the transmitting side, it is processed to ensure that it is received (105).
It is checked whether a reception error has occurred during this retransmission (decision 106).

When the result of 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 10).
7), if the result of judgment 107 is NO, process 104
Go back and re-execute the retransmission request.

When the result of the judgment 107 is YES, that is, when the image information is repeatedly retransmitted until the downshift, the frame error rate pb after the downshift is calculated (step 108), and then the frame error rate pb is calculated. An error improvement rate R is calculated as a result of dividing by the frame error rate Pa (process 109), and it is checked whether the error improvement rate R is smaller than a constant value T (determination 110).

When the result of judgment 110 is YES, it means that even if downshifting is performed, a frame error of more than a certain value occurs and the downshifting is not very effective.
The modem 9 is operated to switch the switch 9c to set the modem 9 to use the auxiliary equalizer 9a (step 111), and the process returns to step 104 to request retransmission.

Also, when the result of judgment 110 is NO, it means that the effect of downshifting has been achieved to some extent.
The auxiliary equalizer 9a remains unused (processing 11).
2) Return to step 104 and request retransmission.

Further, if the result of judgment 102 is No, and if the result of judgment 106 is No, the process moves to preparation for receiving the image information of the next block by responding with signal MCF (
Process 113).

In this way, when a downshift is performed without the image information transmission error being removed easily, check whether the improvement rate of the frame error rate before and after the shift down (error improvement rate R) is greater than a constant value T. If it does not increase, it means that the transmission line characteristics have deteriorated significantly in the high frequency band due to the lack of downshifting effect.
The auxiliary equalizer 9a is set to be in use, and subsequent retransmission requests are made while compensating for deterioration in the high frequency band of the line.

Further, when the error improvement rate R is larger than the constant value T, the effect of downshifting has been exhausted, so the image information retransmission request operation is repeated in that state.

As a result, it is possible to perform an optimal image information reception operation in accordance with the line condition, and it is possible to shorten the time required for image information transmission.

In addition, the use of the auxiliary equalizer 9a is discontinued unless the auxiliary equalizer 9a is particularly effective. Therefore, the auxiliary equalizer 9a can be used effectively, and overcompensation by the auxiliary equalizer 9a is limited. be able to.

By the way, in the embodiment described above, the auxiliary equalizer 9a is always used, but by controlling the use/non-use of the auxiliary equalizer depending on the retransmission situation, it is possible to control the line characteristics to an appropriate value6. FIG. 5 shows the processing executed by the receiving device when receiving one block of image information in another embodiment of the present invention.

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

In this state, process 202 to receive one block of image information.
), it is checked whether a reception error was detected at that time (decision 203).

When a reception error is detected and the result of judgment 203 is YES, an error occurrence rate Pe is calculated by dividing the number of frames in which a reception error has occurred by the number of received frames (process 204), and this error occurrence rate Pe is calculated. is larger than a constant value TR (determination 205).

When the result of the judgment 205 is YES, since there is a possibility that a reception error will occur during retransmission, the switch 9c is switched to set the auxiliary equalizer 9a to the active state (process 206), and in that state, the transmitting side Request resend to (
Processing 207).

Further, when the result of the judgment 205 is NO, the process proceeds to process 207 and requests retransmission to the transmitting side while leaving the auxiliary equalizer 9a in an unused state.

In this way, when a retransmission request is made, the requested frame will be retransmitted from the transmitting side, so it will be processed 208 to ensure that it is received.
), it is checked whether a reception error has occurred at that time (decision 209).

When the result of judgment 209 is YES, the error occurrence rate Pe' is calculated by dividing the number of error frames by the total number of received frames at the time of retransmission (process 210), and the error occurrence rate Pe is divided by the error occurrence rate Pe'. The error improvement rate R obtained by doing this is calculated (process 211).

Then, it is checked whether the error improvement rate R is smaller than the constant value TR (determination 212), and when the result of determination 212 is YES, the high frequency characteristic compensation effect by the auxiliary equalizer 9a is working effectively. Since the auxiliary equalizer 9a is not in use, the switch 9c is switched to disable the auxiliary equalizer 9a. When the result of the judgment 212 is No, the auxiliary equalizer 9a is fully effective. The process returns to process 207 and repeatedly executes the retransmission request while leaving the ``process 213'' in use (process 213 is not performed).

Further, when the result of 1 judgment 203 is No, and when the result of judgment 204 is No, since no reception error has occurred in the image information received at that time, the signal MCF is processed responsively (214). , transition to the reception state for the next block.

Here, constant value TP and constant value TR are values determined empirically.

In this way, when one or more frames have a reception error in the initially received image information, if the error occurrence rate Pe is greater than the fixed value Tp, the auxiliary equalizer 9a
, the retransmitted image information is received while compensating for the high frequency characteristics of the line, thereby suppressing the probability of reception errors occurring during retransmission.

Furthermore, when the effect of the auxiliary equalizer 9a cannot be achieved, 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, but the present invention can also be applied to a modem in which auxiliary equalizers are provided on both the transmitting side and the receiving side.

Further, in the above-described embodiment, the transmitting side does not abort retransmission when retransmission requests are made consecutively, but the present invention can also be applied to a case where retransmission is aborted.

Furthermore, the characteristics of the auxiliary equalizer are not limited to those described above, and when two types of auxiliary equalizers are provided, one corresponding to multi-stage links and the other corresponding to the cable length from the facsimile machine to the exchange. The present invention can also be applied to.

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

In the figure, the receiving signal input terminal of modem 9 is a network control bag!
! It is directly connected to the received signal output terminal of modem 9, and the transmission signal output terminal of modem 9, and the network control device! The transmission signal input terminal of 10 is connected to a switching device 20.10 having four switching terminals.
21 common terminals, respectively.

The first switching terminals of the switching device 20.21 are directly connected to each other and the second, third . The fourth switching terminal includes equalizers 22, 23, . . . for compensating the high frequency characteristics of the transmission line.
Each of them is interconnected via 24.

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

Therefore, when the switch 20.21 selects 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 control device 110, and the switch 20.21 selects the second switching terminal. , when the third and fourth switching terminals are selected, equalizers 22 and 23 are connected between the transmission signal output terminal of the modem 9 and the transmission signal input terminal of the network control device 10.
．． 24 is inserted, whereby a transmission signal is sent out from the modem 9 in a state where the frequency band of the high frequency band of the transmission line can be compensated for.

With the above configuration, when this facsimile device makes a call to another facsimile device and uses the error correction mode to transmit image information in the same procedure as shown in FIG.
FIG. 7 shows an example of the processing executed by put.

That is, first, the switch 20.21 selects the first switching terminal, and without using any of the equalizers 22, 23.24, a process 301 is performed to transmit one block of image information and the signals PPS and Q. , 302), and checks whether the retransmission request has been responded to by the receiving side (decision 303).
).

Then, it is determined whether the retransmission situation at that time satisfies the equalizer insertion condition (determination 304).

If the equalizer insertion conditions are met and the result of judgment 304 is YES, then the equalizers 22, 2
It is determined whether any of 3.24 has already been used (determination 305).

Neither equalizer is used, and the result of judgment 305 is N.
When it becomes O, the switch 20, 21 selects the second switching terminal, the equalizer 22 is inserted into the transmission path, and (
Process 306) In this state, retransmission image information consisting of the frame requested by the receiving device is transmitted (Process 307).

If either equalizer is used and the result of judgment 305 is YES, it is judged whether the inserted one is equalizer 12 (308), and if the result of judgment 308 is YES, switching Vessel 20.2
1 selects the third switching terminal and inserts the equalizer 23 into the transmission path (step 309), the process moves to step 307, and in that state, retransmission image information is transmitted.

When the result of judgment 308 is No, the switch 20-21 selects the fourth switching terminal and inserts the equalizer 24 into the transmission path (process 130), and the process moves to process 307, where retransmission image information is sent. Send.

Further, when the result of the determination 304 is No, the process moves to an immediate process 307, and the retransmission information is transmitted in that state.

Then, it is checked whether or not a retransmission request has been made for the retransmission image information transmitted in process 307 (determination 311).1 Determination 311
When the result is YES, the process returns to decision 304 and the subsequent processes are executed.

Also, when the result of 1 judgment 303 is No, and when the result of judgment 311 is NO, the image information transmitted at that time was received normally, so whether there is any image information block that has not been transmitted. (determination 312), and when the result of determination 312 is NO, the process returns to step 301 and the image information of the next block is transmitted.

Further, when the result of determination 312 is YES, the transmission process is ended.

Here, the equalizer insertion condition is 1. For example, the number of retransmissions exceeds a certain value, the number of retransmitted frames exceeds a certain value, or the retransmission frame rate exceeds a certain value. can.

In this way, we have made it possible to select whether or not to insert an equalizer in the transmission path, and which equalizer to insert, depending on the retransmission situation, so we can eliminate problems caused by poor frequency characteristics of the transmission line. If a transmission error occurs,
The frequency characteristics of the transmission line can be appropriately compensated, and the occurrence of transmission errors can be significantly reduced.

This makes it possible to continue transmitting image information without reducing the transmission speed, and reduces the frequency of retransmission requests, resulting in a significant improvement in transmission efficiency.

By the way, in the embodiment described above, the characteristics of the equalizer to be used are sequentially switched each time a certain equalizer insertion condition is satisfied, but the characteristics of the equalizer to be used are changed depending on the number of retransmissions or the number of retransmitted frames in a certain period. You can also set the characteristics of

Further, in the above embodiment, one of the three equalizers is selectively used, but a combination of these equalizers may be used, or four or more equalizers may be used.

In addition, in the above embodiment, the frequency characteristics are fixed.
By selectively using two equalizers, the frequency characteristics of the equalizer applied to the transmission path are changed, but it is also possible to use an equalizer that can vary one frequency characteristic and switch the characteristics as appropriate.

Further, although an independent equalizer is used in the above embodiment, an equalizer built into the modem may also be used, and in that case, an increase in device cost can be suppressed.

Further, in the above embodiment, an equalizer is used on the transmitting side, but the present invention can be applied even when an equalizer is used on the receiving side, or even when equalizers are used on both the transmitting side and the receiving side. I can do it.

By the way, when transmitting image information using such an error correction mode, a transmission buffer for storing the transmitted image information is required, which is conventional.

Since the capacity of this transmission buffer is set to be large enough to store one block's worth of image information, the following problems have occurred.

For example, if one page's worth of image information does not fit in one block but spans two blocks,
Image information is transmitted according to the procedure shown in the figure.

That is, when the operator of the transmitting device sets a transmission document in the device and inputs a destination to start transmission, the transmitting device calls the receiving device.

The receiving device that detects the incoming call responds with a signal CHD indicating that its own terminal is a non-voice terminal, and then responds with the standard functions and optional functions of its own terminal.
Then, the identification information of the own terminal is notified to the transmitting device by a signal DIS, a signal NSF, and a signal, respectively.

The transmitting device notifies the receiving device of the function to be used at that time using a signal DC8, and also performs a training check TCF.

If the training result is good, the receiving device responds with the signal CFR to the transmitting device, and the transmitting device thereby forms image information PIXI for the first block of the set transmission document and transmits it. It is stored in the buffer and transmitted to the receiving device.

When the transmission of the image information PIXI is finished, signals PPS and NULL are transmitted to notify that there is a subsequent block constituting the same page.

On the other hand, the receiving device stores the received image information PIXI in a transmission buffer, refers to the error detection code FC3 to determine whether a data error has occurred in each data frame, and further stores the received image information PIXI in a transmission buffer. performs the operation of decoding and recording.

When the signals PPS and NULL are received, the reception of the image information of one block is completed, and it is determined that there is a subsequent block of the same page, and at that point, the image information P
When the IXI decoding process has not been completed and it is determined that no data error has occurred in any data frame, a signal RNR is sent as a response to the transmitter.

When the transmitting device receives the signal RNR, it transmits the signal RR without transmitting the image information PIX2 of the next block.

Until the receiving device finishes the decoding process, when it receives the signal RR, it responds with the signal RNR, and when it receives the signal RR after finishing the decoding process, it responds with a greeting signal indicating that it has successfully received the message. The MCF is responded to the transmitting device.

With this, the transmitting device transmits the image information PIX of the next block.
Start sending 2.

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

However, when this flow control is performed, the time required to transmit the image information becomes longer, resulting in a disadvantage that the transmission efficiency decreases.

Next, another embodiment of the present invention that can eliminate such inconveniences will be described.

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

In the same figure, the RAM 30 can configure n transmission buffers each having a capacity of 64 bytes, and a 10th transmission buffer.
As shown in the figure, it has the capacity to configure area OA used for other work areas and the like.

With the above configuration, for example, as shown in FIG.

The size of the image information on the first page is 200 bytes.
Consider transmitting a two-page original that is divided into two blocks BLI and BL2, and the image information of the second page becomes one block BL3. In addition, in the following explanation,
The facsimile machine of FIG. 9 is used as both a transmitter and a receiver.

When the operator of the transmitting device sets two documents to be transmitted on the scanner 4 and inputs the destination from the operation display section 6 to start transmission, the transmitting device calls the receiving device.

The receiving device that detects the incoming call responds with a signal CHD indicating that its own terminal is a non-voice terminal, and then uses the standard functions of its own terminal, the opsimin function,
And identification information of own terminal.

Signal DIS, Signal NSF, and Signal C5I, respectively.
Notify the transmitting device by

The transmitting device notifies the receiving device of the function to be used at that time using a signal DC3, 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 transmits the image information PIXI of the first block BLI on the first page.
Start sending.

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 thereby in the encoder/decoder 8, and converts the image information thus obtained into frame data in the above-mentioned format. The formatted state is stored in the transmission buffer TBI of the RAM 30, and this transmission buffer TBI
The frame data stored in is transferred to the modem 9 and modulated, and then transmitted from the network control device 10 to the receiving device.

In this manner, when the transmission of the image information PIXI of the first block BLI of the first page is completed, the signals PPS and NULL are transmitted to notify that there are subsequent blocks constituting the same page.

Then, reading the next block BL2 of the first page,
Start encoding and obtain image information PIX2
is stored in the transmission buffer TB2 of the RAM3G.

On the other hand, the receiving device stores the received image information PIXI in RAM3.
0 transmission buffer TBI, and determines whether or not a data error has occurred in each data frame by referring to the error detection code FC5. Furthermore, the received image information PIXI is decoded by the encoding/decoding unit 8. After that, the plotter 5 performs the operation of recording and outputting.

Here, the determination of data errors in the data frame by the receiving device is completed immediately after the reception of the image information PIXI is completed, and after this determination process, the receiving device is unable to receive the signal after the message from the transmitting device. I'm waiting for it to come.

At this time, if it is determined that no data error has occurred in any data frame, the signal PP from the transmitter
When receiving S, NULL, it responds with signal MCF.

Upon receiving the signal MCF, the transmitting device transmits the next block B.
The L2 image information PIX2 is transmitted to the receiving device in the same manner as described above.

At the same time, the transmitting device reads the image of the first page.
When the printing is completed, it starts reading and printing the image of the second page to form the image information PIX3 of the block BL3, and then reads the image of the second page.
It is accumulated in the transmission buffer TB3 of AM30.

When the receiving device receives the image information PIX2 of the next block BL2, the receiving device stores the transmission buffer T of the RAM 30 in the same way as described above.
Errors in the data frame are detected while accumulating in B2.

At the same time, the receiving device executes the decoding and recording processing of the first block BLI in parallel with the receiving processing, and when the recording of the image of the block BLI is completed, the receiving device decodes and records the first block BLI.
The decoding and recording process begins.

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

Immediately after receiving the image information PIX2, the receiving device finishes the data frame error detection process and waits to receive the post-message signal. When receiving the signals PPS and MPS, all If the data frame can be received without error, a signal MCF is sent as a response to the transmitting device.

When the transmitting device receives the signal MCF, it 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 when the transmitting device finishes the transmission, it transmits signals PPS and EOP to announce the end of the transmission. do.

The receiving device receives the received image information PIX in the same manner as described above.
3 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 reception of the image information PIX3 is completed, and if all data frames have been received without error at that time, the signal PPS
, HOP, it responds with a signal MCF to the transmitting device.

When the transmitting device receives the signal MCF, it transmits the signal DCN, disconnects the line, and ends the one-stroke information transmission.

When the receiving device finishes recording the first page of the received image, it decodes and records the image information PIX3, and
The image of the second page is recorded and output from the plotter 5. At the same time, upon receiving the signal DCN, the line is disconnected and the reception process is terminated.

In this way, the transmitting device can perform document reading and storage processing and image information transmission processing in parallel, and the receiving device can perform image information reception processing and decoding and recording processing in parallel. Therefore, the time required for image information transmission is significantly shortened, and transmission efficiency is greatly improved.

In the image information transmission example described above, the facsimile device according to an embodiment of the present invention is used as the transmitting device and the receiving device, but it is possible to use the facsimile device according to the embodiment of the present invention for either one. The same effect can be obtained even if

In addition, in the image information transmission example described above, the case where no transmission error occurred in the image information was explained, but even if a transmission error occurs in the image information and a retransmission operation is executed, the effect of improving the transmission efficiency can be obtained. be able to.

[Effects of the Invention] As described above, according to the present invention, an auxiliary equalizer for compensating for high frequency characteristics of a transmission line is installed, and an auxiliary equalizer is installed at least on either the transmitting side or the receiving side depending on the retransmission situation. Since the characteristics of the auxiliary equalizer are changed, the characteristics of one line are adjusted according to the retransmission situation and the transmission error rate is reduced. As a result, the transmission error rate is reduced without reducing the transmission speed. Since the frequency of retransmission requests is reduced, transmission efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a facsimile machine according to an embodiment of the present invention, FIG. 2(a) is a block diagram showing a schematic configuration of a modem, and FIG. 2(b) is a graph showing an example of characteristics of an auxiliary equalizer. , FIG. 3 is a time chart showing how image information is transmitted in error correction mode, FIG. 4 is a flowchart showing an example of processing when image information is received, and FIG. 5 is a time chart showing image information according to another embodiment of the present invention. FIG. 6 is a flowchart showing an example of processing 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.
Flowchart showing an example of processing at the time of transmission of the device shown in FIG.
The figure is a time chart for explaining a conventional example of processing in 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 an example of the configuration of a RAM storage area. 11 is a schematic diagram showing an example of a transmitted original, FIG. 12 is a time chart showing an example of the transmission procedure of the device in FIG. 9, and FIG. FIG. 3B is a schematic diagram illustrating the frame format of the signal PPR. 1...cpu (central processing bag R), 2...ROM
(Read-only memory), 3, 30...RAM
(Random access memory), 9...modem, 9
a...Auxiliary equalizer, 9b...Modem main part, 9
c, 20, 21...switcher, 22, 23, 24...
equalizer. Fig. 1 Fig. 2 (b) Number of field tears M3 Fig. 4 Fig. 5 ■ - N One \J Fig. 8 Fig. 11 Fig. 1z Fig. AQc% -

Claims (6)

[Claims] (1) A facsimile equipped with an error retransmission function that transmits one page of image information divided into multiple frames to the receiving side, and retransmits the frame data of the transmission error frame notified by the receiving side to the receiving side. A control system for a facsimile device, comprising an auxiliary equalizer for compensating frequency characteristics in a high frequency band of a transmission line, and determining whether or not to use the auxiliary equalizer depending on retransmission conditions. control method. (2) A facsimile equipped with an error retransmission function that transmits one page of image information divided into multiple frames to the receiving side, and retransmits the frame data of the transmission error frame notified by the receiving side to the receiving side. In the control method of the device, an auxiliary equalizer is provided to compensate for the frequency characteristics in the high frequency band of the transmission line, and depending on the retransmission situation, the use of the auxiliary equalizer when receiving retransmission image information/
A control method for a facsimile machine characterized by determining non-use. (3) A facsimile equipped with an error retransmission function that transmits one page of image information divided into multiple frames to the receiving side, and retransmits the frame data of the transmission error frame notified by the receiving side to the receiving side. In the control method of the device, an auxiliary equalizer is provided to compensate for the frequency characteristics in the high frequency band of the transmission line, and depending on the retransmission situation, the auxiliary equalizer is used or not used on the transmitting side, and
A control method for a facsimile machine, characterized in that it is determined whether or not the auxiliary equalizer is used on the receiving side. (4) A facsimile equipped with an error retransmission function that transmits one page of image information divided into multiple frames to the receiving side, and retransmits the frame data of the transmission error frame notified by the receiving side to the receiving side. The control system of the device includes an auxiliary equalizer for compensating the frequency characteristics in the high frequency band of the transmission line, and an equalizer characteristic changing means for changing the frequency characteristics of the equalizer, and is equipped with an auxiliary equalizer for compensating the frequency characteristics in the high frequency band of the transmission line, and an equalizer characteristic changing means for changing the frequency characteristics of the equalizer. A control method for a facsimile machine, characterized in that the characteristics of the equalizer are changed by the equalizer characteristics changing means. (5) Divide one page of image information into multiple frames,
In the transmission method of a facsimile machine that has an error retransmission function that transmits multiple frames to the receiving side in blocks and also retransmits the frame data of the transmission error frame notified by the receiving side to the receiving side, one block is transmitted to the receiving side. Provides multiple transmission buffers that can store image information.
When transmitting, once one block of image information has been transmitted,
A transmission method for a facsimile machine, characterized in that, before a reception result is responded from a receiving device, formation of image information for the next block is started and the image information is stored in another transmission buffer. (6) Divide one page of image information into multiple frames,
In the transmission method of a facsimile machine that is equipped with an error retransmission function that transmits multiple frames to the receiving side in blocks and also retransmits the frame data of the transmission error frame notified from the receiving side to the receiving side, when receiving , when the received image information does not contain a transmission error, it responds with normal reception immediately after obtaining the inspection result, and the transmitted image information is thereby stored in another transmission buffer. Transmission method for facsimile equipment.