JP2003069798A - Facsimile equipment and facsimile communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide facsimile equipment and a facsimile communication method, with which a partial page signal (PPS) can be surely received during the communication operation utilizing an ECM function. SOLUTION: After an error is confirmed in a STEP 3, when the occurrence period of the error is longer than a prescribed time in a STEP 6, processing is moved to a STEP 7 and in order to receive PPS-EOP, the communication state of a MODEM is transited to an FSK communication mode. When the PPS-EOP is received, a PPR is transmitted for requesting the retransmission of image signals for all the frames after a frame where the error occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus and a facsimile communication method in which a modulation system of a received signal is switched, and more particularly, an ECM which is an error retransmission system.
The present invention relates to a facsimile apparatus having an (Error Correction Mode) function and a facsimile communication method of this facsimile apparatus.

[0002]

2. Description of the Related Art Conventionally, in facsimile machines,
When the image signal is not correctly received at the receiving side due to the influence of noise on the telephone line during communication, a request to retransmit the image signal is sent to the transmitting side, and the image signal that was not correctly received is retransmitted. , ECM function. When communication is being performed using this ECM function, FIG.
As described above, after transmitting 256 256-byte image frames, the mode is switched to the phase D and the PPS-EOP (Pertial Page Signal-EndOf Pr
Occurrence) is sent from the sending facsimile machine.

The facsimile machine on the receiving side, which receives the PPS-EOP, recognizes that the transmission of the transmission signal of the last page is completed from the EOP, and the ECM is transmitted from the PPS.
Recognize that it is communication. At this time, 25 sent
When there is a frame that is not correctly received due to noise being superimposed in the image signal of 6 frames, a PPR (Pertial Page Request) for designating the frame that was not correctly received is sent as shown in FIG. Is sent to the facsimile machine.

The facsimile apparatus on the transmitting side which receives the PPR recognizes the frame which is not correctly received by the facsimile apparatus on the receiving side from the PPR, retransmits the image signal of the frame, and then transmits PPS-EOP. Upon receiving the image signal of the retransmitted frame, the facsimile apparatus on the reception side transmits PPR again if there is a frame that was not correctly received, and the above-described communication operation is repeated on the facsimile apparatuses on the reception side and the transmission side. Be done.

On the other hand, when the image signal is correctly received by the facsimile apparatus on the receiving side, the MCF indicating that the image signal is correctly received as shown in FIG.
(Message Confirmation) is sent. When the facsimile machine on the transmission side receives the MCF and recognizes that the image signal is correctly received, as shown in FIG.
A facsimile machine on the receiving side is notified that a CN (Disconnect) is transmitted to disconnect the line.

When facsimile communication is performed using the ECM function in this way, the image signal of the frame that was not correctly received is retransmitted until it is correctly received, so that the image is reliably sent to the receiving side facsimile device. A signal can be transmitted.

[0007]

However, when the noise superimposed on the transmitted image signal is temporary and an error occurs intermittently, the ECM function can be used. If an error occurs continuously due to a momentary interruption or a signal received by a modem provided in the facsimile machine diverges, the last frame of the image signal, RCP (Return to Control Part).
ial) The frame may not be detected and PPS-EOP may not be detected. This is because the image signal is 14400b
While it is transmitted at the communication speed of ps, PPS-
Since EOP is transmitted at a communication speed of 300 bps, the communication speed is different.
This is because it is necessary to switch the reception mode of the modem to receive S-EOP.

That is, when the image signal is being received in the receiving state corresponding to the communication speed of 14400 bps, when the normal operation is performed, 300b after the RCP frame is detected.
Switch to the receiving state according to the communication speed of ps, but if errors occur continuously during the reception of image signals, RCP
Since the frame cannot be detected, the reception state cannot be switched and the reception of PPS-EOP cannot be confirmed. Therefore, the PPR cannot be transmitted from the facsimile machine on the receiving side, and the retransmission request cannot be made. Incidentally, PP
A signal such as S-EOP or PPR that is transmitted and received at a communication speed of 300 bps in phase B and phase D is called an FSK (Frequency Shift Keying) signal.

In view of these problems, the present invention provides an EC
An object of the present invention is to provide a facsimile apparatus and a facsimile communication method capable of surely receiving a partial page signal (PPS) during a communication operation using the M function.

[0010]

In order to achieve the above object, a facsimile apparatus according to a first aspect of the present invention includes a modem for transmitting / receiving a signal to / from another facsimile apparatus and a received image signal for each frame. And a frame which is not correctly received by the modem is confirmed by the error check unit, the frame is not correctly received by the facsimile device as a communication partner. In a facsimile apparatus equipped with an ECM function for requesting retransmission of a frame image signal, when the error check unit confirms that frames that are not correctly received by the modem are continuous, the communication operation of the modem is stopped. , From the first state of receiving the image signal transmitted and received at the first communication speed, to the transmission and reception at the second communication speed And wherein the switching forced to a second state for receiving signals.

In such a facsimile apparatus, when the error check unit continuously detects frames that are not correctly received and have an error, the communication speed of the modem is set to, for example, an image signal having a high communication speed of 14400 bps. 300 bp from the first state of receiving
The state is switched to the second state in which an FSK signal having a slow communication speed such as s is received. By doing so, when the modem is in a divergent state where it cannot receive the image signal normally, it is possible to receive the FSK signal even if the RCP frame that is the final frame of the image signal cannot be detected. Therefore, it is possible to recognize that the communication state of the facsimile apparatus as the communication partner has changed to phase D.

In such a facsimile apparatus, as described in claim 2, when the image signal is not correctly received by the modem in the error check unit for a predetermined time, the frames that are not correctly received are continuously received. You may regard it as having done it. At this time,
By setting this predetermined time to, for example, 4 seconds, it means that the image signal of about 28 frames was not correctly received.

Further, as described in claim 3, when the error check section confirms that the frames which are not correctly received by the modem are consecutive, the communication operation of the modem is set to the second state. After switching, when a signal is received from the communication partner facsimile machine, the modem will receive in the first state from a frame that was not correctly received by the communication partner facsimile machine. By transmitting the PPR for requesting the retransmission of the image signal up to the last frame, it is possible to request the retransmission of the image signal for all the frames after the frame in which the error starts.

Further, as described in claim 4, when the error check section confirms that the frames which are not correctly received by the modem are consecutive, the communication operation of the modem is set to the second state. After the switching, in order to receive a signal from the facsimile device as the communication partner, the modem is made to wait in the second state for a time period corresponding to the maximum number of frames of the image signal received by the modem in the first state. By doing so, even when an error occurs from the first frame of the image signal and all the image signals cannot be received, the PPS can be received. Note that the time corresponding to the maximum number of frames of the image signal received in the first state may be the time for the flag for each frame of the image signal omitted.

According to a fifth aspect of the present invention, there is provided a facsimile communication method, which has a modem for transmitting / receiving to / from another facsimile apparatus, confirms whether or not the image signal received by the modem is correctly received for each frame, and corrects it. When the unreceived frame is confirmed, the facsimile communication method in the facsimile device having the ECM function for requesting the facsimile device as a communication partner to retransmit the image signal of the frame not correctly received is received correctly. If it is confirmed that the unsuccessful frames are continuous, the communication operation of the modem is changed from the first state of receiving the image signal transmitted / received at the first communication speed to the signal transmitted / received at the second communication speed. It is characterized in that it is forcibly switched to the second state in which it is turned on.

In such a facsimile communication method, as described in claim 6, when the image signal is not correctly received by the modem for a predetermined time, it is considered that the frames which are not correctly received are continuous. It doesn't matter.

Further, as described in claim 7, when it is confirmed that the frames which are not correctly received by the modem are consecutive, the communication operation of the modem is switched to the second state, and then the communication is performed. When a signal is received from a partner facsimile machine, an image from a frame that is not correctly received by the partner facsimile machine to the last frame that the modem will receive in the first state PPR for requesting signal retransmission
Is transmitted, it is possible to request retransmission of the image signal of the frame that has not been received.

Further, as described in claim 8, when it is confirmed that the frames which are not correctly received by the modem are consecutive, the communication operation of the modem is switched to the second state, and then the communication is performed. In order to receive a signal from a partner facsimile machine, the modem may wait in the second state for a time period corresponding to the maximum number of frames of the image signal received by the modem in the first state. .

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the internal configuration of the facsimile apparatus of this embodiment. FIG. 2 is a flowchart showing the operation of the facsimile apparatus of FIG.

The facsimile apparatus of FIG. 1 has a main control section 1 for controlling the entire apparatus, an encoding section 2 for encoding image data, a decoding section 3 for decoding a received signal, and a signal NCU (Networ) that switches the connection between the modem 4 that performs modulation and demodulation and the telephone line between the facsimile and the telephone.
k Control Unit) 5, an image reading unit 6 configured by a photoelectric conversion element such as a CCD (Charge Coupled Device) sensor for reading the content of a transmission document, and image data obtained by the electric signal obtained by the image reading unit 6. An image processing unit 7 that performs image processing such as shading correction, binarization processing, or halftone processing; a recording processing unit 8 that performs image processing such as smoothing processing on the decoded image data; An output unit 9 that prints a received document on a recording paper according to the image data subjected to image processing by the processing unit 8 and discharges the printed recording paper, an operation unit 10 that gives an instruction for transmission / reception, and a destination telephone. A display unit 11 for displaying numbers and the like, a memory 12 for storing destination numbers and the like, and an image memory 13 for storing image data of a received document are provided. .

The facsimile apparatus having such a structure performs communication as shown in FIG. That is, when the operation unit 10 of the facsimile machine on the transmission side is operated to dial the destination telephone number, a calling operation is performed, and a CNG (Calling Tone) is used by the modem 4 and NCU
5 is transmitted. N of the facsimile machine on the receiving side
When CNG is received by CU5, it is recognized that facsimile communication is performed. Then, the facsimile machine on the receiving side sends CED (Called Tone) to the modem 4 and the NCU.
The data is transmitted to the facsimile machine on the transmission side through 5. still,
The CNG and CED identify the sender and the receiver as facsimile machines.

In this way, when the operation of phase A is performed and the communication connection is established between the transmitting side and the receiving side facsimile machines, the receiving side facsimile machine transmits the NSF.
(Non-Standard Facilities), CSI (Called Subscr
iber Identification), DIS (Digital Identificat)
ion Signal) is transmitted. At this time, NSF indicates the function of the facsimile device unique to the manufacturer, CSI indicates the telephone number of the receiving side, and DIS indicates the function of the G3 standard facsimile device. What is the function of the facsimile machine?
Indicates the type of modem, the width of the recording paper for documents to be sent and received, the communication speed, etc.

On the other hand, the facsimile machine on the transmission side sends NSS (Non-Standard Facilities Set-up) or TSI (Transmitting Subscriber Identificatio).
n) and DCS (Digital Command Signal) are transmitted. At this time, the transmission conditions of the manufacturer's own facsimile device in which NSS is set, TSI indicates the telephone number of the sender, and the transmission conditions of the G3 standard facsimile device in which DCS is set are shown. NSS and DCS are
It represents the transmission condition set according to the function of the receiving side recognized by the received NSF and DIS. Also, NSS, N
The SF is a signal that is recognized when the sending and receiving facsimile machines are manufactured by the same manufacturer.

Then, in order to test whether normal communication is possible, a TCF (Training
Check Field) is transmitted. When the receiving TCF receives this TCF, when no error is confirmed in the received TCF, a CFR (Confirmation to Receive) indicating that the transmitting operation is normally performed is sent to the transmitting facsimile. To send. This Phase A
In Phase B, the facsimile machine uses the FSK signal as a signal for communication, so
The state is set according to the transmission rate of bps. The TCF is
Since it is a test signal, it is transmitted at the same transmission speed as the phase C image signal.

In this way, the communication operation of the phase B is performed, and after the transmission side facsimile apparatus is set to transmit under the transmission condition according to the function of the reception side facsimile apparatus, the communication is normally performed. Is confirmed,
Transition to Phase C. In this phase C, the image signal is transmitted from the transmitting side facsimile device to the receiving side facsimile device as a transmission signal. At this time, the facsimile machine on the receiving side brings the modem 4 into a state corresponding to the transmission speed of 14400 bps.

The operation of the facsimile apparatus on the receiving side after the communication state of the facsimile apparatus transits to Phase C in this way will be described with reference to the flowchart of FIG. In the following, among the communication operation states of the modem 4, a communication state for transmitting / receiving an image signal having a communication speed of 14400 bps is referred to as an “image signal communication mode”, and a transmission / reception of an FSK signal having a communication speed of 300 bps is performed. The communication state is called "FSK communication mode".

When the communication state transitions from phase B to phase C as described above, the modem on the receiving side switches the modem 4 from the FSK communication mode to the image signal communication mode (STEP 1). Like this modem 4
Is set to the image signal communication mode, an image signal of 256 bytes per frame is transmitted from the transmitting side facsimile apparatus and received by the modem 4 (STEP 2). At this time, the received image signal is demodulated by the modem 4. This image signal is a QAM (Quadrature Amplitude Modulation) which is a modulation method capable of transmitting many bit data.
modulation) and DPSK (Different Phase Shift Key)
ing) system is modulated.

In this way, when the image signal is demodulated by the modem 4, it is confirmed whether or not a communication error has occurred (ST.
EP3). At this time, since noise is superimposed on the received image signal, it becomes impossible to demodulate the modem 4 as in the normal state, and when an error occurs, the main control unit 1 passes through the decoding unit 3 and It is recognized that a communication error has occurred. When the main control unit 1 does not recognize such a communication error (No), it is confirmed whether or not the received image signal is an RCP frame after being decoded by the decoding unit 3 (STEP 4). .

When it is confirmed that the final RCP frame has been received since the start of the image signal reception (Yes), after this RCP frame, the FSK signal is transmitted from the transmitting facsimile machine. Some P
Since PS-EOP is transmitted, the status of the modem 4 is FS.
Switch to the K communication mode (STEP 5). Therefore, the communication state transitions to phase D. If the frame is not the RCP frame (No), the operations after STEP 2 are performed again.

When an error is confirmed in STEP 3, the main control unit 1 confirms whether or not the error continues for a predetermined time (STEP 6). At this time, if the error occurs temporarily, (N
o), the process shifts to STEP 4 to confirm whether or not the RCP frame is received. On the contrary, if it is confirmed that the error continues to occur for the predetermined time (Yes), the error continues to occur and the reception signal at the modem 4 is likely to diverge, and the RCP frame is confirmed. Is not performed, and there is a possibility that the switching to the FSK communication mode will not be performed. Therefore, the FSK communication mode is forcibly switched to (STEP 7).

The predetermined time defined for confirming the continuation of the error in STEP 6 may be, for example, about 4 seconds. In this 4 seconds, 4 × 14400 = 576
00 bits, that is, 7200 bytes of data are received. That is, since one frame has 256 bytes, an image signal of about 28 frames is received in 4 seconds. Therefore, the state transitions to Phase C, and the maximum 256
Considering that the image signal of the frame is transmitted and received,
By defining 4 seconds in this manner, it can be considered that an error of a sufficient amount that the modem 4 can be recognized to have diverged has occurred.

In this way, the communication status of the modem 4 is changed to FSK.
Upon switching to the communication mode, reception of PPS-EOP is confirmed (STEP 8). At this time, when the reception of the PPS-EOP is confirmed (Yes), the state transitions to the phase D, and the PPR for requesting the transmission of all the frames after the frame in which the error is detected in STEP3 is requested. Send (STEP 9).

When the reception of PPS-EOP is not confirmed (No), it is confirmed whether or not a predetermined time has passed after switching the communication state of the modem 4 to the FSK communication mode (STEP 10). ). At this time, if the predetermined time has not elapsed (No), reception of PPS-EOP is confirmed again in STEP 8. On the other hand, when the predetermined time has elapsed (Yes), it is regarded as a communication error, and the communication line with the facsimile machine on the transmission side is disconnected (STE).
P11).

The predetermined time confirmed in STEP 10 can be defined as follows. Since a maximum of 256 frames of 256 bytes are transmitted after the transition to phase C, a maximum of 256 × 256 = 6553
6 bytes of data are transmitted after transitioning to phase C. Therefore, since the communication speed is 14400 bps, the time required to transmit this maximum frame is 65536 × 8/14400 = 36.4 seconds.
That is, the predetermined time confirmed in STEP 10 is at least 3
It may be 6.4 seconds. It should be noted that the predetermined time calculated in this way excludes the time for the flags arranged between the frames in the image signal received in phase C, and is therefore a little longer when the flag sending time is taken into consideration. There is a need to.

As described above, after the communication state transitions to the phase C, the communication state transitions to the phase D after the receiving side facsimile machine operates according to the flowchart of FIG. 2, as described in the prior art. In the case where the received image signal has an error, when the PPS-EOP is received, as shown in FIG. 3, the PPR for requesting the retransmission of the frame in which the error has occurred is transmitted to the facsimile apparatus on the transmission side. At this time, if the received signal in the modem 4 is considered to have diverged, as described above, the PPR for requesting retransmission of all frames after the frame in which the error is first confirmed to occur. Is transmitted to the facsimile machine on the transmitting side.

Further, when the communication state transits to the phase D and the image signal received by the facsimile apparatus on the receiving side has no error, when PPS-EOP is received, the MCF is transmitted to the transmitting side as shown in FIG. Notify the facsimile device that communication has been normally performed. Then, the facsimile machine on the transmission side which has received the MCF transmits DCN to the facsimile machine on the reception side to disconnect the line.

In order to simplify the description, in the present specification, as described above, when an image signal for the final page is transmitted such that EOP is transmitted together with PPS after the image signal has been transmitted. However, the same applies to the operation when the image signal of the page in the middle of the document to be transmitted is transmitted. That is, even when one block or one page of image signal is transmitted, the state transits to phase D, and even when NULL or EOM (End Of Message) is transmitted together with PPS from the transmitting side facsimile apparatus, NULL is transmitted. When the facsimile machine on the receiving side transmits the MCF, the state transitions to the phase C, and when the EOM is transmitted, the facsimile apparatus on the receiving side transitions to the phase B after transmitting the MCF. Other than that, the same operation is performed.

Although the communication speeds of the image signal and the FSK signal have been described as 14400 bps and 300 bps, respectively, the communication speeds are not limited to this.

[0039]

According to the present invention, when an error occurs continuously and image signals of a plurality of consecutive frames are no longer received, the communication state of the modem is forced to the second state. Even if the image signal cannot be received due to impulse noise or momentary interruption, it can be recognized that the FSK signal has been received and the state has transitioned to phase D. That is, the PPS can be received.

In addition, since the PPR for transmitting the image signal from the first frame of the consecutive frames which are not correctly received to the last frame which the modem will receive in the first state is transmitted, an error occurs. It is possible to request the retransmission of the image signal for all the frames after the frame in which the occurrence of? Furthermore, since the modem is switched to the second state and put on standby for a time corresponding to the maximum number of frames of the image signal received in the phase C which is the first state, an error occurs from the first frame of the image signal Even when all cannot be received, the PPS can be made receivable.

[Brief description of drawings]

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

2 is a flowchart showing the operation of the facsimile apparatus of FIG.

FIG. 3 is a time chart showing a communication operation of the facsimile device.

[Explanation of symbols]

1 Main control unit 2 Encoding section 3 Decoding section 4 modem 5 NCU 6 Image reading section 7 Image processing unit 8 Recording processor 9 Output section 10 Operation part 11 Display 12 memories 13 Image memory

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Hashizume             1-22 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Prefecture             Kyocera Mita Co., Ltd. (72) Inventor Katsuaki Yasui             1-22 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Prefecture             Kyocera Mita Co., Ltd. (72) Inventor Hitoshi Asaka             1-22 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Prefecture             Kyocera Mita Co., Ltd. F term (reference) 5C075 CA01 CD22 CE04 CE10 CE11                       FF04                 5K014 AA03 BA05 DA02 FA03 HA07

Claims (8)

[Claims] 1. A modem for transmitting / receiving a signal to / from another facsimile apparatus, and an error check unit for confirming whether or not a received image signal is correctly received for each frame, and the modem is properly received. An ECM for requesting a facsimile apparatus as a communication partner to retransmit an image signal of a frame that has not been correctly received when the unsuccessful frame is confirmed by the error check unit.
In a facsimile apparatus having an (ErrorCorrection Mode) function, when the error check unit confirms that frames that are not correctly received by the modem are consecutive, the communication operation of the modem is transmitted and received at a first communication speed. Facsimile apparatus forcibly switching from a first state in which a received image signal is received to a second state in which a signal transmitted and received at a second communication speed is received. 2. The error checking unit, when the image signal is not correctly received by the modem for a predetermined time, considers that the frames that are not correctly received are continuous. Fax machine. 3. When the error check unit confirms that the frames that were not correctly received by the modem are continuous, after switching the communication operation of the modem to the second state,
When a signal is received from the communication partner facsimile machine, from the frame which is not correctly received to the communication partner facsimile machine to the last frame which the modem will receive in the first state. PPR (Pertial Page) for requesting retransmission of the image signal of
Request) is transmitted, The facsimile apparatus of Claim 1 or Claim 2 characterized by the above-mentioned. 4. When the error check unit confirms that the frames that were not correctly received by the modem are continuous, after switching the communication operation of the modem to the second state,
In order to receive a signal from the facsimile device as the communication partner, the modem is made to stand by in the second state for a time period corresponding to the maximum number of frames of the image signal received by the modem in the first state. The facsimile apparatus according to any one of claims 1 to 3. 5. A modem for transmitting / receiving data to / from another facsimile machine is provided, and it is confirmed whether or not the image signal received by the modem is correctly received for each frame, and a frame which is not correctly received is confirmed. At this time, in the facsimile communication method in the facsimile apparatus having the ECM function for requesting the facsimile apparatus as a communication partner to retransmit the image signal of the frame that was not correctly received, it is possible that the frames that are not correctly received are consecutive. When confirmed, the communication operation of the modem is forcibly switched from the first state of receiving the image signal transmitted / received at the first communication speed to the second state of receiving the signal transmitted / received at the second communication speed. A facsimile communication method characterized by the above. 6. The facsimile communication method according to claim 5, wherein when the image signal is not correctly received by the modem for a predetermined time, it is considered that the frames that are not correctly received are continuous. 7. When it is confirmed that the frames that were not correctly received by the modem are continuous, after switching the communication operation of the modem to the second state,
When a signal is received from the communication partner facsimile machine, from the frame which is not correctly received to the communication partner facsimile machine to the last frame which the modem will receive in the first state. 7. The facsimile communication method according to claim 5, further comprising transmitting a PPR for requesting retransmission of the image signal. 8. When it is confirmed that the frames which are not correctly received by the modem are continuous, after switching the communication operation of the modem to the second state,
In order to receive a signal from the facsimile device as the communication partner, the modem waits in the second state for a time period corresponding to the maximum number of frames of the image signal received by the modem in the first state. Claim 5 to claim 7
Facsimile communication method described in.