JPH08251377A - Facsimile equipment - Google Patents

Abstract

PURPOSE: To prevent a communication time from being longer more than a required time even when a rate of occurrence of an error frame is high by falling back a transmission rate of a modem when fallback is decided based on a total number of transmission frames and number of re-transmission request frames. CONSTITUTION: A read section 7 reads image information to be sent and sends the image information by one block, then a sender side sends a block end signal. When the sender side receives a re-transmission request(PPR) from the receiver side and it is discriminated that the PPR received this time is not a 4th consecutive PPR, the sender side decides whether or not fallback is made at a point of present time based on the total frame number and error frame number subject to re-transmission request after the transmission of one block. When the fallback is decided, the sender side sends a CTC even when the 4th consecutive PPR is not received yet and applies the fallback to the modem after the reception of a reply signal and sends a training signal and then sends the error frame data subject to re-transmission request.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile machine having an error correction function.

[0002]

2. Description of the Related Art ITU-T Recommendation T. According to No. 30, the error correction function (Error Correcting Mod) that checks the transmission data for each block and, when a transmission error occurs in the block, retransmits the frame in which the transmission error has occurred.
A conventional facsimile apparatus having e, hereinafter referred to as ECM) sends a block of transmission data and then a retransmission request (Partial Page Request, hereinafter referred to as PPR) from the receiving side.
Is received four times in a row, it is configured to decide to decrease the communication speed by one step (fallback).

FIG. 3 shows the ITU-T recommendation T.264. 30 is a flowchart showing a communication procedure of a conventional facsimile apparatus having an ECM function according to 30.

When transmission is started by a normal procedure and image information for one block is transmitted (step S31), the transmitting side transmits a block end signal (PPS) (step S32) and a response from the receiving side is sent. Wait (step S3
3). If there is a response, it is determined whether or not the response is PPR (step S34). Here, the response is P
If it is determined that the image is not PR, it is confirmed in step S41 whether or not the transmission of all the image information is completed. If the transmission of all the image information is completed, the transmission operation is completed according to a predetermined procedure. If there is a next block to be transmitted, the process returns to step S31 and the image information for the next one block is transmitted.

On the other hand, when it is determined in step S34 that the received response is PPR, the PPR
Is the fourth consecutive PPR (step S35), and if it is the fourth consecutive PPR, whether further error correction is continued, that is, a transmission error occurs. It is determined whether or not the error frame being processed should be transmitted again (step S36). For example, when the fourth PPR has been sent continuously, the operator can set in advance whether or not to continue the retransmission.
According to this, it is determined whether or not to retransmit. Here, if it is determined that the setting is such that the retransmission is not continued, the process proceeds to step S41 described above. If it is determined that the settings are set to continue re-sending, the mode set command (CT
C), and waits for a response from the receiving side (step S3
7) After receiving the response, reduce the transmission speed of the modem (fallback) and send out training (step S3).
8). Then, the requested error frame is transmitted (step S39), and the partial page control return signal (RCP) is transmitted (step S40).

If it is determined in step S35 that the PPR received this time is not the fourth consecutive PPR, training is transmitted without fallback (step S42), and the error frame requested to be retransmitted is transmitted. (Step S39), RCP is transmitted (step S40). After transmitting the RCP, the process proceeds to step S41 described above, and if there is a block to be transmitted, step S31
~ The operation of step S40 is repeated.

That is, in the conventional facsimile apparatus,
Only the number of PPRs sent from the receiving side is the condition for determining whether or not to perform fallback.
The number of frames in which there was was not related to the fallback condition.

[0008]

However, even when the error frame occurrence rate is high, such as when the condition of the communication line is bad, after the error frame is retransmitted three times, the fourth PPR is received. Until that happens, fallback is not performed, so there was the problem that the communication time would become unnecessarily long.

The present invention has been made in order to solve the above-mentioned problems, and the communication time becomes longer than necessary even when the error frame occurrence rate is high such as when the condition of the communication line is bad. It is an object of the present invention to provide a facsimile device capable of preventing the above.

[0010]

To achieve the above object, a facsimile apparatus of the present invention counts the total number of transmission frames included in one block transmitted at the time of transmission in a facsimile apparatus having an error correction function. 1 counting means, 2nd counting means for counting the number of retransmission request frames when there is a retransmission request for a frame in which a transmission error has occurred from the receiving side after sending the 1 block, and the 1st counting means Fallback determining means for determining whether or not to fall back the transmission rate of the modem based on the total number of transmission frames counted by the above and the number of retransmission request frames counted by the second counting means, If the fallback decision means decides to perform a fallback, a fallback to fallback the transmission rate of the modem. Means, characterized in that it comprises a sending means for sending said retransmission request frame at a transmission speed of the modem fallback by the fallback device.

[0011]

According to the above structure, the first counting means counts the total number of frames to be transmitted at the time of transmission, and when a retransmission request is made from the receiving side after the frames are transmitted, the second counting means. The number of retransmission request frames is counted, and the fallback determining means determines the number of retransmission frames counted by the first counting means and the number of retransmission request frames counted by the second counting means. Whether or not to perform fallback of the transmission rate is determined, and when it is determined to perform the fallback, at the transmission rate of the modem fallback by the fallback means,
A resend request frame is sent.

[0012]

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

FIG. 1 is a block diagram showing the arrangement of a facsimile apparatus according to this embodiment.

In the figure, a facsimile machine 100
Is a network control unit 1 connected to an external communication line network, a modem 2 that performs modulation / demodulation and analog / digital conversion of image information to be transmitted or received, and a main control unit (CPU that controls the operation of the entire facsimile apparatus 100). ) 3 and the CPU3
ROM 4 for storing programs and the like for the operation of
A RAM 5 used as a work area of the PU 3, an operation panel 6 including a keyboard for an operator to operate the facsimile apparatus 100, a reading unit 7 that reads image information of a transmission document, and image information is printed out on a recording sheet. The recording unit 8 includes a recording unit 8, a display unit 9 for displaying a message such as a communication status, and a call unit 10 for an operator to talk.

FIG. 2 shows the above-mentioned facsimile apparatus 100.
5 is a flowchart showing a communication processing procedure by the. A program for executing this processing procedure is stored in the ROM 4 and controlled by the CPU 3.

In this embodiment, the transmission of the original document is started by the operator placing the original document on the reading section 7 and pressing a start key (not shown) on the operation panel 6.

When the image information to be transmitted is read by the reading unit 7 and the image information for one block is transmitted (step S1), the transmitting side transmits a block end signal (PPS) (step S2), and the receiving side transmits. Wait for a response (step S3). If there is a response, it is determined whether or not the response is PPR (step S4). Here, the response is P
If it is determined not to be PR, it is confirmed whether or not the transmission of all the image information is completed (step S11), and if the transmission of all the image information is completed, the transmission operation is ended according to a predetermined procedure. . If there is a next block to be transmitted, the process returns to step S1 and the next one block is transmitted.

When it is determined in step S4 that the received response is the PPR, it is determined whether the PPR is the fourth consecutive PPR (step S5) and the fourth consecutive consecutive PPR. If it is determined to be PPR, it is further determined whether or not to continue error correction (step S6). For example, when the fourth consecutive PPR is sent, the operator can set beforehand whether or not to continue the error correction, and it is determined whether or not to perform the error correction based on the setting. If it is determined that the error correction is not continued, the process proceeds to step S11 to determine whether or not the transmission of all the image information is completed, and the transmission of all the image information is completed. If it is determined, the transmission operation is ended according to a predetermined procedure. If there is a next block to be transmitted, the process returns to step S1 and the image information for the next one block is transmitted. Furthermore, in step S6,
When it is determined that the error correction is set to continue, the CTC is transmitted and the response from the receiving side is waited (step S7). After the response is received, the fallback is performed and the training is transmitted (step S8). ). After transmitting the requested error frame (step S9), R
The CP is transmitted (step S10), and the processes after step S11 are performed.

On the other hand, if it is determined in step S5 that the PPR received this time is not the fourth consecutive PPR, it is determined whether fallback is to be performed at the present time or not by a method described later (step S12). If it is decided to perform fallback, the CTC is transmitted in step S7 described above to wait for a response from the receiving side, and after the response is received, fallback is performed and training is transmitted (step S8). Then, the requested error frame is sent (step S9), the RCP is sent (step S10), and the processes after step S11 are performed.

If it is determined in step 12 that fallback is not to be performed, training is sent out without fallback (step S13), and the processing in step S9 and subsequent steps described above is performed.

The determination as to whether or not fallback should be performed in step S12 is performed by one of the following methods.

(1) If the number of frames for which the receiving side has requested a retransmission request, that is, the number of error frames n is equal to or greater than a predetermined value a, or if the number of error frames n is greater than a predetermined value a, it is determined to execute fallback . In this case, the total number N of frames transmitted by the transmission side is not considered.
ITU-T Recommendation T. According to No. 30, since the maximum value of the number of frames included in one block of image information transmitted by the facsimile apparatus having the ECM function is 256 frames, the fallback execution condition is n ≧ a (where 0 <n ≦ 256,0 <a ≦ 256) or n> a (where 0 <n ≦ 256, 0 ≦ a <256). The predetermined value a is a value stored in the ROM 4 in advance. The value of the predetermined value a may be freely changeable by the operator.

(2) When the ratio of the error frame number n to the total frame number N when the transmitting side sends one block is a predetermined value p or more, or the ratio of the error frame number n to the total frame number N is the predetermined value p Decides to perform fallback if greater. That is, the fallback execution condition is (n / N) ≧ p (0 <N ≦ 256, 0 <n ≦ 256,
0 <p ≦ 1) or (n / N)> p (0 <N ≦ 256, 0 <n ≦ 256,
0 ≦ p <1). The predetermined value p is a value stored in the ROM 4 in advance. The value of the predetermined value p may be freely changeable by the operator.

(3) If it is expected that an error frame exists even in the fourth transmission of the same block, it is decided to execute fallback. Here, the “fourth transmission of the same block” refers to the third error frame retransmission of the block after the transmission of the first one block.

ITU-T Recommendation T. According to the conventional facsimile apparatus according to No. 30, fallback is performed when an error frame exists even in the fourth transmission of the same block, but even if the fourth transmission is not actually performed, If fallback is performed when it is expected that an error frame exists at the time of retransmission of an error frame, it is possible to prevent the total communication time from becoming longer than necessary.

When the total number of frames transmitted by the transmitting side is N and the number of error frames is n, the expected value of the number of error frames in the fourth transmission of the same block is n · (n / N) ³ , The condition in the case where it is expected that an error frame is present even in the fourth transmission, that is, the fallback execution condition is: n · (n / N) ³ = n ⁴ / N ³ ≧ 1 (0 <N ≦ 256,
0 <n ≦ 256).

As described above, according to this embodiment,
When the number of error frames is relatively large and it is considered that it is necessary to spend a long time for retransmission of error frames (case (1) or (2) above), or the number of error frames is relatively large and the same. If it is expected that fallback will be required after the fourth transmission of the block (case (3) above), the fallback can be performed immediately before receiving the fourth consecutive RCP. As a result, even when there are many error frames,
It is possible to prevent the communication time from becoming longer than necessary.

[0028]

As described above, according to the facsimile apparatus of the present invention, in the facsimile apparatus having the error correction function, the first counting means for counting the total number of transmission frames included in one block transmitted at the time of transmission. And a second counting means for counting the number of retransmission request frames when the receiving side requests retransmission of a frame in which a transmission error has occurred after the transmission of one block, and the first counting means. Fallback determining means for determining whether or not to fall back the transmission rate of the modem based on the total number of outgoing frames and the number of retransmission request frames counted by the second counting means, and the fallback determining means. If the means decide to do a fallback,
When the state of the communication line is bad by providing fallback means for falling back the transmission speed of the modem and sending means for sending the retransmission request frame at the transmission speed of the modem fallbacked by the fallback means Even if there are many occurrences of equal error frames, it becomes possible to perform fallback promptly before receiving the fourth retransmission request, and therefore,
The effect that the communication time can be prevented from becoming longer than necessary is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a communication procedure in the facsimile apparatus shown in FIG.

FIG. 3 is a flowchart showing a communication procedure in a conventional facsimile apparatus having an error correction function.

[Explanation of symbols]

1 network control unit (sending means) 2 modem 3 CPU (first counting means, second counting means, fallback determining means, fallback means, sending means)

Claims (6)

[Claims] 1. In a facsimile apparatus having an error correction function, a first counting means for counting the total number of transmission frames included in one block transmitted at the time of transmission, and a transmission error occurs from the receiving side after the transmission of the one block. Second counting means for counting the number of retransmission request frames when there is a request for retransmission of the generated frame, the total number of transmission frames counted by the first counting means, and the total number of transmission frames counted by the second counting means. Fallback determining means for determining whether or not to fallback the transmission rate of the modem based on the number of retransmission request frames; and the modem when the fallback determining means determines to perform fallback. A fallback means for falling back the transmission speed of the modem, and the modem fallback by the fallback means. Facsimile apparatus characterized by at feed rate and a sending means for sending said retransmission request frame. 2. The fallback determination means determines to perform fallback when the ratio of the number of retransmission request frames to the total number of the transmission frames is a predetermined value or more. The described facsimile machine. 3. The fallback determining means determines to perform fallback when the ratio of the number of retransmission request frames to the total number of transmission frames is larger than a predetermined value. Fax machine. 4. The fallback determining means sets the total number of the transmission frames to N and the number of the retransmission request frames to n.
The facsimile apparatus according to claim 1, wherein fallback is determined to be performed when (n ⁴ / N ³ ) ≧ 1. 5. The fallback determining means determines to perform fallback when the number of retransmission request frames is equal to or greater than a predetermined value.
The described facsimile machine. 6. The fallback determining means determines to perform fallback when the number of retransmission request frames is larger than a predetermined value.
The described facsimile machine.