JPH0666868B2 - Fax machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a facsimile apparatus that performs error retransmission, and more particularly, to a transmitter side of a facsimile apparatus that performs error retransmission.

[Prior Art] Conventionally, when an image data error is detected on the receiving side during transmission of image data by the transmitting side, the receiving side transmits an error retransmission request signal, and the transmitting side receiving the error retransmission request signal , The image data was retransmitted and the error was retransmitted.

However, when the arrival of the error retransmission request signal is extremely delayed due to the influence of the line delay or the like, the transmission side has determined that the retransmission request signal does not come.

At this time, the transmission side may fail to receive the retransmission request signal transmitted from the reception side for the end portion of the image data that has been transmitted, and error retransmission of the end portion of the image data may not be executed.

This is shown in FIG. In FIG. 8, the error retransmission request signal reaches the transmission side after the transmission side transmits the EOP signal. Since the transmitting side has already judged that the transmission of the image data has been normally completed, the error retransmission request signal is ignored and the DCN signal is transmitted. Then the sender disconnects the line,
Since the receiving side receives the DCN signal, it disconnects the line. As a result, the communication is ended without executing the error resending for the end portion of the image data.

In view of the above points, the present invention is a facsimile apparatus capable of error retransmission, and a facsimile apparatus capable of preventing the transmission side from failing to receive an error retransmission request signal and performing error retransmission at the end of image data. The purpose is to provide.

[Embodiment] FIG. 1 shows an outline of the operation of this embodiment.

The signals used in this embodiment are those specified by CCITT Recommendation T.30.

FIG. 1 is a diagram showing exchange of signals when error retransmission is successful.

In FIG. 1, the procedure is first performed to start transmission of image data. Then, a line failure occurs during the communication of the image data, and an error occurs in the image data received by the receiving side. Due to this error occurrence, the reception side transmits an error retransmission request signal (in this embodiment, the PIS signal is used) to the transmission side. The transmission side receives the PIS signal and interrupts the transmission of the image data. Then, when the transmitting side interrupts the transmission of the image data, the transmitting side transmits an NSF signal and indicates the retransmission start line number. The transmission side that receives this NSF signal retransmits the image data from the line number designated by the NSF signal. If the image data is successfully retransmitted, the post-procedure is performed and the communication is ended.

FIG. 2 is a block diagram showing the arrangement of the facsimile apparatus on the transmission side of this embodiment.

In FIG. 2, reference numeral 2 is a network control device for holding a loop.
NCU (Network Control Unit), which is used to connect the telephone network to data communication, controls the connection of the telephone switching network and switches to the data communication path of the telephone network. 2a is a telephone line.

Reference numeral 4 is a hybrid circuit for separating a transmission system signal and a reception system signal. The transmission signal of the signal line 28a passes through the signal line 2b and is sent to the telephone line 2a via the network control device 2.
The signal sent from the facsimile machine on the other side is output to the signal line 4a after passing through the network control device 2.

Reference numeral 6 is a circuit for detecting a retransmission request signal (a PIS signal is used in this embodiment) sent from the receiver.
That is, the signal of the signal line 4a is introduced, and when the retransmission request signal is detected, the signal of the signal level "1" is output to the signal line 6a. On the other hand, when the signal of the signal line 4a is introduced and the retransmission request signal is not detected, the signal of the signal level "0" is output to the signal line 6a.

Reference numeral 8 is a circuit for receiving a retransmission start line number and a disconnection command (DCN) signal (a signal of 300b / s) which is transmitted subsequently to the retransmission request signal from the receiving side device. When detecting the NSF signal, the binary signal receiving circuit 8 generates a pulse on the signal line 8a and outputs a retransmission start line number to the signal line 8b. The binary signal receiving circuit 8 also generates a pulse on the signal line 8C when detecting the DCN signal.

A reading device 10 reads an image signal for one line in the main scanning line direction from a transmission document and creates an example of a signal representing binary values of white or black. The reading device 10 is composed of an image pickup device such as a CCD (charge coupled device) and an optical system. Also, the control circuit 30 controls to read the image signal of one line,
The digitized data is output to the signal line 10a.

Reference numeral 14 is a counter that counts the line number inserted after the line end code (EOL). In this embodiment, since a line number is designated and error resending is performed, data indicating the line number is added to the EOL of each line and transmitted. If a pulse is generated on the signal line 30c, the line number is set to 0. Then, each time a pulse is generated on the signal line 30d, the line number value is incremented. Also, the data indicating the line number value is the signal line
It is output to 14a.

Reference numeral 16 is a circuit for inputting one line of binarized data output to the signal line 30e and outputting encoded data (modified Huffman encoding in this embodiment) to the signal line 16c.

Reference numeral 18 is a FIFO memory used for reading line data and storing encoded data. FIFO memory 18
Stores the data output to the signal line 30h.
Further, the FIFO memory 18 stores the stored data in the signal line 18a.
Output to.

Reference numeral 24 is a modulator that performs modulation based on the well-known CCITT recommendation V27ter (operating phase modulation). The modulator 24 inputs the data read from the FIFO memory by the control circuit 30 and output to the signal line 30o, modulates the data, and sends the data to the signal line 24a. Further, the modulator 24 receives data in byte units from the signal line 30o, and requests the control circuit 30 for the next data when the transmission of the received byte data is completed.

26 is on signal line 26a when a pulse occurs on signal line 30p
It is a DCN signal line sending circuit that sends a DCN signal (300b / s).

Reference numeral 28 is an adder circuit that inputs the signal of the signal line 24a and the signal of the signal line 26a and outputs the addition result to the signal line 28a.

Reference numeral 30 is a control circuit, the operation of which will be described with reference to FIG. 3, FIG. 4, and FIG.

FIG. 3 is a flowchart explaining the operation of the control circuit 30. However, FIG. 3 shows a main routine for encoding, and transmission of image data is processed by an interrupt routine (FIG. 4).

In step S104 of FIG. 3, first, the image data of one line read by the reading device 10 of FIG. 2 is read.

In step S106, the image data is encoded and written in the FIFO memory.

Next, in step S108, the PI which is the retransmission request signal from the receiving side.
Determine if S signal has arrived. If the PIS signal is detected, the transmission of the image data is interrupted and the process proceeds to step S110. If no PIS signal is detected, the process proceeds to step S114.

In step S110, the NSF signal is received. This NSF signal contains data indicating the retransmission start line number. Then, the retransmission is started from this retransmission start line number.

In step S114, it is determined whether or not the encoding of one original has been completed. When the encoding of one original has not been completed, the process returns to step S104. When the encoding of one document is completed, the process proceeds to step S118.

In step S118, the RTC signal data is written to the FIFO memory.

In step S1130, the encoding end flag MHEND is set to 1.

In step S120, it waits until all the coded image data is transmitted, and after the image data is transmitted, it is monitored whether or not an error retransmission request is made from the receiving side to the end portion of the image data. . If it is determined that there is an error retransmission request for the end portion of the image data, error retransmission of the end portion of the image data is performed, and if it is determined that there is no error retransmission request for the end portion of the image data,
Proceed to S132. Regarding the processing of this step S120,
This will be described in detail with reference to the drawings.

In step S122, a post procedure is performed.

FIG. 4 is a diagram showing a transmission process which is an interrupt process of the control circuit 30 of FIG. This interrupt is the second
This is a process that occurs each time there is no data to be transmitted in the modulator 24 in the figure.

Step S360 shows the start of image data transmission. The transmission of the image data is started when the FIFO memory 18 stores the image data to be transmitted.

In step S362, it is determined whether or not the encoding of one original image has been completed. If the flag MEND = 0, it means that the encoding has not been completed, and the process advances to step S394. Flag MH
If END = 0 is not satisfied, the encoding is completed, and the process proceeds to step S364.

In step S394, the data read from the FIFO memory 18 is output to the signal line 30o, and the data is passed to the modulator 24.

In step S364, it is determined whether or not the transmission of all the data stored in the FIFO memory 18 is completed. If the transmission is completed, the process proceeds to step S366. If the transmission is not completed,
Proceed to step S394.

In step S366, the transmission end flag TRNEND is set to 1.

Steps S402 and S368 indicate returning to the main routine.

FIG. 5 is a diagram for explaining the process of step S120 of FIG. 3 in detail. This process is a process after the encoding of the image data of the main routine is completed, and is mainly a process of monitoring whether or not an error retransmission request is made from the receiving side after the completion of the transmission of the image data.

In step 1132, the flag TRANSCHK used in step S1148 described later is set to 0.

In step S1134, T2 is set to 2 minutes. This T2
Is the time to monitor whether the error resend request signal for the end part of the transmitted image data comes from the receiving side after the image data transmission is completed. It is not necessary until the set transmission end flag TRANEND becomes 1. Further, the time from the end of the encoding of the image data in the main routine to the end of the transmission of the image data in the interrupt routine does not exceed 2 minutes. Further, when an error resend request is made to the end portion of the image data, the time required for error resending of the end portion of the image data does not exceed 2 minutes. Therefore, the transmission end flag
In step S1134, T2 is set to 2 minutes so that T2 does not time out until TRANEND becomes 1.

In step S1136, it is determined whether the PIS signal which is the error retransmission request signal is detected. If the PIS signal is detected, the process proceeds to step S1152, and if the PIS signal is not detected, the process proceeds to step S1138.

In step S1138, the time over of T2 is monitored and T2
If the time is over, the process proceeds to step S1140. If T2 is not over, the process proceeds to step S1144.

In step S1144, it is detected whether or not the transmission of the image data is completed by the interrupt processing described with reference to FIG.
When the transmission end flag TRANEND becomes 1, the transmission is completed. T
If RANEND is 0, the transmission of the image data has not been completed, so the process returns to step S1136. If TRANEND is not 0, the transmission of the image data has been completed, so the process proceeds to step S1146.

In step S1146, after the end of the transmission of the image data, the error retransmission request signal for the end portion of the transmitted image data, preset the time T2 to monitor whether it comes from the receiving side, whether the timer is started or not. Indicates flag TRNC
Check HK. If TRNCHK flag is 0, step
Proceed to S1148, and if the TRNCHK flag is 1, step S1136
Return to.

In step S1148, the TRNCHK flag is set to 1.

In step S1150, after the end of the transmission of the image data, the time T2 for monitoring whether or not the error retransmission request signal for the end portion of the transmitted image data comes from the receiving side is preset to 1.5 seconds, and the timer is started. In this embodiment,
After the end of the transmission of the image data, the time until the error retransmission request signal for the end portion of the transmitted image data comes from the receiving side is set to 1.5 seconds in consideration of the influence of the line delay. After presetting T2 and starting the timer, step S1136 (PIS detection), step S1138 (T2
1.5 seconds have passed), and the routine of step S1146 is repeated.

In step S1152 and subsequent steps, error transmission of the image data is performed, so in step S1152, the transmission end flag TRNEND is set to 0.
To

In step S1154, the flag TRNCHK is set to 0.

In step S1156, if the image data is being transmitted, the transmission of the image data is interrupted.

In step S1158, it waits for 30 seconds until the NSF signal is received. If the NSF signal is received, the process proceeds to step S1164. If the NSF signal cannot be received even after 30 seconds have passed, it is determined that the error retransmission has failed, and the processing ends in error in step S1162.

In step S1164, the retransmission start line number designated by the receiving side by the NSF signal is input.

In step S1168, the image data of the retransmission start line number is read from the FIFO memory and output to the modulator 24, and the transmission of the image data from the retransmission start line number is started.

If 1.5 seconds expires in step S1138, step
In S1140, it is detected whether a signal is coming from the receiving side.
If there is a signal, the process proceeds to step S1142, and if there is no signal, it is determined that the image data transmission has succeeded and step S1170.
Proceed to.

In step S1142, it is detected whether the signal coming from the receiving side is the PIS signal. If it is a PIS signal, the process proceeds to step S1152 to perform error retransmission. If the PIS signal cannot be detected even after 2 seconds, it is determined that the image data has been successfully transmitted, and the process proceeds to step S1170.

Step S1170 shows the end of transmission of the image data. After that, the control circuit 30 performs a post procedure.

FIG. 6 is a block diagram showing the configuration of the facsimile apparatus on the receiving side according to this embodiment.

40 is a network control unit (NCU). 40a indicates a telephone line.

42 is a hybrid circuit. The signal sent to the signal line 54a passes through the signal line 40b and the network control device 40,
It is sent to the telephone line 40a. The signal sent from the facsimile machine on the other side is output to the signal line 42a after passing through the network control device 40.

Reference numeral 44 is a circuit that inputs the signal of the signal line 42a and detects whether or not there is a signal. The circuit 44 outputs a signal of signal level "1" to the signal line 44a when receiving a signal of -43dbm or more, and when receiving a signal of less than -43dbm,
A signal having a signal level "0" is output to the signal line 44a.

46 is a demodulator. The demodulator 46 receives the signal on the signal line 42a, demodulates it, and outputs the demodulated data to the signal line 46a.

Reference numeral 50 is a circuit for transmitting an NSF signal. NSF signal transmission circuit
50 is NS on signal line 50a when a pulse occurs on signal line 66b.
Send the F signal. The NSF signal contains the line number. The value output to the signal line 66a is set to this line number. The signal line 66a includes the signal line 58a.
A value obtained by adding 1 to the value of the line number output to is output. The NSF signal transmission circuit 50 generates a pulse on the signal line 50b when the transmission of the NSF signal is completed.

52 is a circuit for transmitting a PIS signal as an error resend request signal. The PIS signal transmission circuit 52 is a circuit for transmitting a PIS signal (a 462 Hz signal for 3 seconds) to the signal line 52a when a pulse occurs on the signal line 66c. The PIS signal transmission circuit 52 is
When the signal transmission is completed, a pulse is generated on the signal line 52b.

Reference numeral 54 is an adder circuit that inputs the signal of the signal line 50a and the signal of the signal line 52a and outputs the addition result to the signal line 54a.

Reference numeral 56 is a FIFO memory used to store the demodulated data obtained by demodulating the data sent from the facsimile machine on the other side by the demodulator 46. FIFO memory 56 uses signal line 66e
The stored demodulated data is stored in the signal line 56a and is output to the signal line 56a.

Reference numeral 58 is a line number storage memory for storing the latest line number of correctly received data. The line number storage memory 58 describes the latest line number input via the signal line 58a by the write control of the control circuit 66, and outputs to the signal line 58a by the read line control by the control circuit 66. To do.

Reference numeral 60 is a compound device that combines the demodulated data stored in the FIFO memory. The combiner 60 combines the demodulated data input from the signal line 60a and outputs the combined data obtained by combining the demodulated data to the signal line 60a.

64 is a recording device. The recording device 64 inputs the demodulated data demodulated by the demodulator 60 from the signal line 66n and records it on the recording paper.

Reference numeral 66 denotes a control circuit, which performs control described later.

FIG. 7 shows a flowchart of the image receiving process of this embodiment.

This flowchart is executed by the control circuit 66 shown in FIG.

Step S1036 represents the start of image data reception after the completion of all the procedures.

While detecting whether or not there is an error in the image data received in step S1041, the image data is received until RTC is detected in step S1046.

If RTC is detected in step S1046, post-procedure is executed in step S1048.

If it is detected in step S1041 that the image data has an error, in step S1056, the PIS signal is transmitted in full-duplex operation in order to suspend the transmission of the image data to the transmitting side.

NSF for which the retransmission start line number was set in step S1074
Send a signal. This retransmission start line number is the 6th
It is a value obtained by adding 1 to the value of the line number stored in the line number storage memory in the figure.

[Effect] According to the present invention, if there is an error in the received image data, an error resend request signal that is a full-duplex procedure signal is transmitted during reception of the image data, and if there is no error in the received image data. , Until the end of reception of the page, in the facsimile device that transmits the image data to the facsimile receiving device that receives the image data without transmitting the procedure signal to the transmitting side, The period until the error retransmission request signal for the end part of the data arrives from the facsimile receiving device is
Wait for arrival of the retransmission request signal without transmitting the procedure signal, and if the error retransmission request signal is not received by the receiving means within the period, the procedure signal to be transmitted is transmitted after the transmission of the image data is transmitted. It is possible to prevent the side from failing to receive the error resend request signal and failing to perform error resend at the end portion of the image data.

[Brief description of drawings]

FIG. 1 is a diagram showing a signal procedure of the present embodiment, FIG. 2 is a block diagram of a transmitting side of the present embodiment, FIG. 3 is a flowchart of a main routine of the transmitting side of the present embodiment, and FIG. Is a flowchart of the interrupt routine on the transmitting side of the present embodiment, FIG. 5 is a flowchart showing the features of the present embodiment, FIG. 6 is a block diagram of the transmitting side of the present embodiment, and FIG. FIG. 8 is a flowchart of the receiving side of the example, FIG. 8 is a diagram showing a signal procedure of the conventional example, 2 is an NCU 4, a hybrid circuit 6, a retransmission request signal detection circuit 8, a binary signal receiving circuit 10, and a reading device. Reference numeral 14 is a line number counter circuit 16, an encoding circuit 18, a FIFO memory 24, a modulator 26, a DCN signal sending circuit 28, an adding circuit 30 and a control circuit. 40, NCU 42, hybrid circuit 44, signal presence / absence detection circuit 46, demodulator 50, NSF signal transmission circuit 52, PIS signal transmission circuit 54, addition circuit 56, FIFO memory 58, line number The storage memory 60, the decoder 64, and the recording device 66 are control circuits.

Claims (1)

[Claims] 1. If there is an error in the received image data, an error resend request signal which is a full-duplex procedure signal is transmitted during the reception of the image data, and if there is no error in the received image data, the page Until the end of reception, a facsimile device that transmits image data to a facsimile receiving device that receives image data without transmitting a procedure signal to the transmitting side receives an error resend request signal transmitted from the facsimile receiving device. A receiving unit and an error retransmitting unit for transmitting the image data requested for error retransmission when the error retransmitting request signal is received by the receiving unit are provided, and after the transmission of the image data is completed, the end of the transmitted image data is completed. In the period until the error resend request signal for the portion of arrives from the facsimile receiving apparatus, the resend request signal is transmitted without transmitting the procedure signal. Us wait, if the error retransmission request signal by the reception unit is received within the time period, the facsimile apparatus characterized by transmitting a procedure signal to be transmitted after the transmission completion of the image data.