JPS5831071B2 - Error correction method in facsimile equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the correction of transmission errors in a facsimile machine that transmits image information, and in particular is an effective method for shortening the extension of transmission time caused by providing an error correction function. .

Hereinafter, a conventionally used transmission error correction method will be briefly explained.

FIG. 1 is a simple block diagram of the conventional system, in which 1 is a transmitter, 2 is a receiver, and 3 is an ACK.

NAK control circuit, 4 is a data source, 01 to G4 are gates, A and B are gate terminals, Ml is a retransmission block memory, 5 is a transmitter interface,
S is the transmitter, R is the receiver, 6 is the transmission path, 1 is the receiver interface, S is the transmitter, R is the receiver,
8 is an error detector, 9 is an ACK response circuit, 10 is a NAK response circuit, 11.12 is a control circuit, 13 is a recording section, and M is a reception memory.

Here, the ACK response circuit 9 outputs an acknowledgment character ACK when the error detector 8 does not detect an error in the transmitted data.
is derived.

The NAK response circuit 10 derives a negative response character NAK when the error detector 8 detects an error in the transmitted data.

Now, in transmitter 1, in some way, ACK, NA
When the K control circuit 3 gives a command to send data to the data source 4 and the gates G1 to G3 receive a command to send data to the terminal A side, data D1 is sent from the data source 4, and the data D1 is sent to the gates G1. G2
is supplied to terminal A of

On the other hand, since the gates Gl and G2 are input to the terminal A side by the above command, the data D1 is stored in the retransmission block memory M1 via the gate G1, and at the same time
The signal is supplied to the transmitter S of the interface 5 via G2, where it is subjected to appropriate processing and then sent to the transmission line 6.

By the way, the data D1 is divided into appropriate blocks as shown in FIG. 3, and when one block is sent out, the control circuit 3 issues a command to the data source 4 to stop data sending and a command to input the terminal B side to the gate G3. is given and the transmitter is switched to the receive state.

On the other hand, in the receiver 2, the control circuit 11 gives the terminal B side pitching command to the terminal B side G4 by some method, and the receiver 2 is placed in a receiving state.

Therefore, data D1 from the transmitter 1 via the transmission line 6 reaches the receiving section R1 of the interface γ.

After being subjected to appropriate processing in the receiving section RI, the signal is stored in the receiving memory M and simultaneously supplied to the error detector 8.

At the same time that one block of data D1 is completely stored in the reception memo IJM, the error detector 8 detects whether or not the now received data D1 has caused an error on the transmission path.

There are various methods for this detection, but since they are not related to the present invention, their explanation will be omitted.

If there is no transmission error as a result of the detection, a control signal is supplied from the error detector 8 to the ACK response circuit 9 and the control circuit 11.

The control circuit 11 is driven by this control signal, and the recording section 1
A recording command is given to gate G4 and a command to input the terminal A side to gate G4, and at the same time data D1 in the receiving memory MI is recorded, gate G4 is switched to terminal A, and the receiver 2 is put into a transmitting state.

On the other hand, the ACK response circuit 9 is driven by the control signal supplied to the ACK response circuit 9, and an ACK signal indicating that there was no transmission error is supplied from the interface 7 to the transmitter S.

From the above explanation, get G4 is input to terminal A and receiver 2
is in the transmitting state, the ACK signal is sent to the transmitter St.
After being appropriately processed here, it is sent out through the transmission line 61.

By the way, the transmitter 1 is in the receiving state as described above, and the ACK signal sent from the receiver 2 is transmitted through the transmission line 6.
The signal reaches the receiving section R of the interface 5.

The ACK signal processed here is ACK NA
The signal is supplied to the K control circuit 3, and again a data sending command is given to the data source 4, and a terminal A side command is given to the gate G3 to send out the data D1.

It is assumed that the retransmission block memo IJ M 1 is designed so that when new data is stored, the previous data is erased unless the gate G1 is input to the terminal B side.

The above explanation is based on the case where there is no transmission error on the transmission path, but if there is a transmission error as a result of the detection, the error detector 8 sends a NAK response circuit 10 and the control circuit 12.
A control signal is supplied to the

The control circuit 12 is driven by this control signal, and the recording section 1
Give a recording stop command to 3 and write the memo IJ to the received memo IJM.
A command to set IJ is given, and a command to close terminal A side is given to gate G4.

In response, the recording unit 13 stops recording.

The reception memory M stores the data D stored up to that point.
Clear 1.

The gate G4 switches to the terminal A side and puts the receiver 2 into the transmitting state.

On the other hand, the control signal l supplied to the NAK response circuit 10r drives the NAK response circuit 10, and a NAK signal indicating that there has been a transmission error is supplied to the transmitter S of the interface 1.

From the above explanation, since G-1-G4 is input to terminal A, the NAK signal is as in the case of the ACK signal.
It is sent out to the transmission line 6.

Also in the transmitter 1, the NAK signal is supplied to the ACK NAK control circuit 3 in the same manner as the ACK signal.

However, when the ACK and NAK control circuit 3 receives the NAK signal, it does not give a data sending command to the data source 4, but instead sends a command to the terminal B side to the gate Gl and the gate G2, respectively. Give a terminal A side closing command to 1-03,
The data D1 previously stored in the retransmission memory M1 at the same time as the data transmission, that is, the data D1 for which a transmission error was detected in the receiver 2, is retransmitted from the retransmission memo IJMI via the gate G2.

The signal read from the retransmission block memory lJM1 at this time is stored in the retransmission memory M1 again through the gate G1, so that it can be retransmitted if a transmission error occurs again in the retransmission data D1.

When an ACK signal is sent from the receiver 2 in response to the retransmitted data D1, the ACK and NAK control circuit 3 gives a data sending command to the data source 4I and a terminal B side throw command to the gates G1 to G3. Perform normal data transmission again.

FIG. 3 explains the data transmission/reception relationship in the conventional method, where Dl is the data D1 sent from the transmitter 1;
is the ACK or NAK signal received by transmitter 1, D3 is the data D1 received by receiver 2, D4 is the ACK or NAK signal sent by receiver 2, and t is the data sent from transmitter 1 received. Delay time until it is received by machine 2, t
2 is the delay time until the signal sent from receiver 2 is received by transmitter 1, RTART is the start signal, 10.20
, 21... are the block signals of data D1,
The number on the right side retransmits data D1.

As can be seen from the above description and FIG. 3, according to the conventional system, each time a data block is sent out, a response is received from the receiver, and after confirmation, the next data block is sent out.

Even if such a method does not require data retransmission,
Data transmission must be temporarily stopped until a response is confirmed, which not only wastes transmission time, but also makes the sequence complicated as the transmitter and receiver are alternately switched between the transmitting state and the receiving state. When switching, it is necessary to train the transmission system interface, which also takes a considerable amount of time and increases the transmission time.

This has the disadvantage of increasing transmission cost and greatly affecting the amount of transmission.

The present invention has been made in view of this point, and is configured such that a response is returned only when data needs to be retransmitted, and the transmitter temporarily stops transmitting data and switches to retransmission only when this response is received. This invention provides a time-saving error correction method for facsimile machines.

FIG. 2 is a block diagram showing one embodiment of the present invention, and in the figure,
The structure of the parts different from those in FIG. 1 will be explained.

In FIG. 2, 05 to G1 are gates, M2 is a retransmission memory, T1 is a TONB detector, and T2 is a TONE transmitter.

Here, the TONE transmitter T2 derives a TONE signal for requesting retransmission of an erroneous data block when the NAK response circuit 10 derives a negative acknowledgment character.

The TONE detector T1 detects that the TONE signal has been returned via the transmission path 6, and provides the ACK/NAK control subcircuit 3 with a signal indicating that a retransmission request has been made.

Hereinafter, the operation of the present invention will be explained in detail with reference to FIG.

Now, in the transmitter 1, a command to send data is sent from the control circuit 3 to the data source 4 using the method described above.
06 Terminal A side closing command to G7, 9 9
9 When a terminal B side command is given to gate G5, data source 4
The data D1 is sent out from the gate G1 and stored in the retransmission block memory M1 via the gate Gl.
The signal is supplied to the transmitter S of the interface 5 via the .

After being subjected to appropriate processing here, it is sent out to the transmission line 6.

By the way, the data D1 is divided into appropriate blocks as shown in FIG. A terminal B side closing command is given to the gate G5, and a terminal A side closing command is given to the gate G5, and the data D1 continues to be stored in the block memory M2tζ for retransmission through the gate G5, and then to the transmission line 6 through the gate G2 as described above. Sent out.

Similarly to the above, when one block of data D1 has been transmitted, the control circuit 3 issues a terminal A side input command to the gate G1.
Game) A command to send to terminal B is given to G5, and data D1 is subsequently sent out to the transmission path via gate G1 and stored in retransmission block memory M1.

Note that the data D1 previously stored in the retransmission memory M1 is erased when new data D1 is stored.

The above operations are repeated in order, and the data D1 is rubbed so that it is continuously sent to the transmission 6.

On the other hand, in the receiver 2t, data D1 is supplied from the transmission path 6 to the interface 1.

Interface 1 includes a receiver R and a TONE transmitter T2.
is connected, and after the data D1 is appropriately processed in the receiving section R, it is stored in the receiving block memory M, and at the same time, it is supplied to the error detector.

At the same time that one block of data D1 is completely stored in the reception block memory M, an error detector 8 detects whether or not the currently received data D1 has caused an error on the transmission path.

As a result of the detection, if there is no transmission error, the error detector 8 supplies a control signal to the control circuit 11, gives a recording command to the recording section 13, and records the data D1 in the reception block memory M.

At this time, no response is made to the transmitter, the receiving state is continuously maintained, and the received data D1 is recorded.

If there is a transmission error as a result of the detection, the error detector 8
A control signal is supplied to the NAK response circuit 10 and the control circuit 12, which gives a recording stop command to the recording unit 13 and a reset command to the reception block memo IJM to stop recording and transfer the reception block memo IJM to the next data D1. Reset until the start of the block is detected.

On the other hand, a TONE sending command is supplied from the NAK response circuit 10 to the TONE sending unit T2, and the TONE signal is sent to the transmission line 6.

Note that this TONE signal is a signal that can sufficiently pass through the transmission line 6.

In the transmitter 1, during the transmission of a block of data D1 following the block of data D1 in which a transmission error was detected in the receiver 2, the TONE detector Tl) of the ink-face 5 detects a TONE. When a signal is detected, for example, gate G1. G2. If G6 and Gl are input to the terminal A side and gate G5 is input to the terminal B side, the data D whose transmission error was detected in the receiver 2
The data D1 following 1, that is, the data D1 sent from the transmitter 1 at the time of TONE detection, is in the memory in the retransmission block memo UM1, and is stored in the retransmission block memory UM1.
Data D1 in which a transmission error was detected in the receiver 2 is stored in JM2.

Therefore, supplying the TONE detection signal to the control circuit 3,
Control circuit 3 connects gate 02 G5 06.
2 Give a command to the terminal B side, send data D1 from the retransmission block memory IJM2, retransmit the data that caused the transmission error, and at the same time send the data to the gate G5 in preparation for retransmission.
The data is then stored in the retransmission block memory M2 again.

On the other hand, when the control circuit 3 finishes storing the data D1 in the memory in the retransmission block memory IJ M 1, it gives a data transmission stop command to the data source 4.

When the retransmission from the retransmission block memory IJM2 is completed, the control circuit 3 gives a terminal B side input command to the gate Gl and G7, and a terminal A side input command to the gate G6, and transfers the data of the retransmission block memory IJM2. Following D1, the data D1 in the retransmission block memory M1 is retransmitted.

This data D1 is data whose transmission was interrupted when the TONE detection retransmission was started.

In this way, when the retransmission from the retransmission block memory M2°Ml is completed, the control circuit 3 again gives a data transmission command to the data source 4, while the gates G2, G5. G
6. Issue a terminal A side closing command to Gl and return to normal state.

In the receiver 2, recording is stopped and the reception memo IJM is reset until the start of the data D1 block retransmitted from the transmitter 1 is detected. When this happens, they are released, normal operation resumes, and recording begins.

FIG. 4 explains the data transmission/reception relationship of the present invention, and in the figure, the same reference numerals as in FIG. 2 represent the same or the same operations.

Note that TONE means the TONE signal described above.

As can be seen from the above description and FIG. 4, according to the present invention, blocks of data D1, for example, 1020 blocks of data D1...
・It is possible to continuously transmit the response from the receiver 2 without receiving and confirming it, and only when the receiver 2 detects a transmission error and the transmitter 1 detects it, The data being sent at the time of detection is interrupted and retransmission is started immediately. Therefore, the wasted transmission time due to correcting transmission errors by retransmission is eliminated.
For example, in Fig. 4, there is no need to switch the transmitter 1 and receiver 2 to the transmitting state and the receiving state, and training of the transmission system interface is required only by interrupting the transmission of 3.0 blocks of data D1. Therefore, if there is no transmission error and there is no need to retransmit, the transmission time is exactly the same as that of a facsimile machine without an error correction function.

The above is a detailed description of one embodiment of the present invention, and the method of using the retransmission block memory and reception memory, and the length and format of the data block are not limited to these.

Also, the receiving section R1 and the transmitting section S of the interface 5゜6 may not be particularly required, so the format of the TONE signal and the return method can be changed, for example, by switching the transmitter and receiver to the transmitting/receiving state as in the past and returning the TONB signal. It's okay.

The point is, if no transmission errors occur, it is sufficient to send this data continuously.

According to the present invention, normal data is sent out continuously,
By having the receiver send a message back to the transmitter and retransmitting the data only when a transmission error occurs, the overall transmission time is reduced by minimizing the transmission time required while maintaining the error correction function. This has the advantage of shortening the time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional transmission format, FIG. 2 is a block diagram showing a transmission format according to the present invention, FIG. 3 is an explanatory diagram for explaining the conventional transmission format, and FIG. 4 is a block diagram showing a transmission format according to the present invention. 1 is an explanatory diagram illustrating the transmission format. 1 is a transmitter, 2 is a receiver, 3 is a control circuit, 4 is a data source, 5 is a transmitter interface, 6 is a transmission path, 1 is a receiver interface, 8 is an error detector, Ml and M2 are block memories for retransmission, M is a reception memory, GI G2
There are 9 gates from G5 to Gγ.

Claims (1)

[Claims] A facsimile device including a transmitter and a receiver connected by 11 transmission paths (wherein, the transmitter blocks image information into a plurality of broadcast blocks and transmits the blocks to the receiver. The receiver detects the presence or absence of a transmission error for each block (and returns a retransmission request to the receiver when detecting a transmission error), and the transmitter receives the retransmission request. By transmitting information blocks continuously until the end of the process, interrupting the transmission of information blocks only when a retransmission request is received, and retransmitting the information block that caused the transmission error, and then retransmitting the information block whose transmission was interrupted. , characterized by error correction,
Error correction method in facsimile machines. 2. The retransmission request is multiplexed with image information during transfer of image information and sent back from the receiver to the transmitter without converting the transmitter into a receiving state and the receiver into a transmitting state. An error correction system in a facsimile machine according to claim 1.