JPH08223390A - Facsimile equipment having full duplex modem - Google Patents

Abstract

PURPOSE: To reduce a communication time by a simple procedure by changing a communication speed to a designated speed to continue transmission of image data when a transmitter side receives the signal designating the communication speed from the receiver side during the transmission of image data. CONSTITUTION: A signal processing section 1 of a receiver side sequentially adds the number of lines, E, discriminated to be errors in received image data from a facsimile communication control section 2 and a RAM 3b and compares the sum with the number reference lines, R, of a ROM 3b. The number R is set to 10, 20 or 40 in advance corresponding to read accuracy and when the number E exceeds the number R, the processing section 1 interrupts the carrier for a prescribed time and designates a communication speed set depending on the number R to the transmitter side. The processing section 1 of the transmitter side revises the communication speed to the designated communication speed received via the control section 2 even on the way of transmission to continue the transmission of image data. Thus, fall-back of a modem is conducted by a simple procedure, the communication time is reduced to save the communication charge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus having a full-duplex modem which can fall back quickly by a simple procedure.

[0002]

2. Description of the Related Art As a facsimile apparatus, in addition to a facsimile communication function of a normal communication mode for transmitting image data of an original in page units, an ECM communication mode for dividing image data into a plurality of frames for facsimile transmission is provided. Are popular. Recently, a facsimile apparatus using a full-duplex modem has been developed, and at the same time, the above function can be realized by bidirectional facsimile communication.

In facsimile communication in the normal communication mode,
After receiving the image data for one page, the receiving side executes the procedure such as receiving the image data of the next page if there is no error in all the received lines, but if there is an error, do so. Is sent to the transmitting side to request the resending of the page in error. On the other hand, in the facsimile communication in the ECM communication mode, for example, image data is transmitted / received in 1 block units composed of 256 frames.
When an error occurs in a block, image data communication in frame units is repeatedly executed until the image data for one block can be correctly transmitted. Here, one frame is composed of image data divided into, for example, 256 bytes each, and CRC check (cyclic redundancy check)
Detects an error.

In this way, an error in the image data is detected and the image data is retransmitted. When the image data is retransmitted a predetermined number of times or more (for example, three times or more), the transmitter side falls back to the modem and the subsequent The probability of error in communication is reduced.

[0005]

However, in the above-mentioned conventional facsimile apparatus, when the receiving side detects many errors during the transmission of image data, the transmitting side usually needs to change the communication speed of the modem. In the case of the communication mode, it can be executed only after the communication of the image data for one page is completed, and in the case of the ECM communication mode, after the communication of the image data for one block is completed. For this reason, it is necessary to perform communication even for untransmitted image data in the middle of transmission for a while at the same communication speed at which an error is likely to occur, and as a result, transmission / reception for all image data is performed. It takes a lot of time to complete, and the receiving side had to perform extra processing.

The present invention has been proposed in view of the above points, and has a full-duplex modem in which the transmission side can quickly change the communication speed by an instruction from the reception side even during the reception of image data. The purpose is to provide a facsimile machine.

[0007]

According to a first aspect of the present invention, there is provided a facsimile apparatus according to claim 1, which is proposed for achieving the above object, when a signal specifying a communication speed is received from a receiving side during transmission of image data. On the side, the communication speed is changed to this designated speed and the transmission of the image data is continued.
This facsimile machine has a full-duplex modem that enables simultaneous bidirectional communication.

According to another aspect of the present invention, in the facsimile apparatus, the reception side determines a communication speed in accordance with the number of lines in the received image data which is determined to be an error, and the transmission side specifies the communication speed. To send. Here, the number of lines determined to be an error is stored in advance in the facsimile device,
When the number of error lines exceeds the number of reference lines compared with the number of reference lines set according to the line density of the image data, the receiving side sets the communication speed set according to the number of reference lines. Specify as the sender.

According to a third aspect of the present invention, the facsimile apparatus receives a signal specifying a communication speed from the receiving side during frame transmission during execution of an ECM communication mode in which image data is divided into a plurality of frames and transmitted by facsimile. In this case, the transmission side changes the communication speed to this designated speed and continues frame transmission. Here, the receiving side determines the communication speed according to the number of frames that are determined to be an error in the received image data.

[0010]

In the facsimile apparatus according to the first aspect of the present invention having the above-mentioned structure, the receiving side is provided with a transmitting side so as to perform a fall down of the modem when an error occurs frequently in the image data being received. Send a signal specifying the communication speed to. On the other hand, when the transmission side receives the signal specifying the communication speed, the communication speed is changed and the transmission of the image data is continued even during the transmission of the image data.

In the facsimile apparatus according to the second aspect,
On the receiving side, the number of lines determined as an error in the received image data is sequentially added and compared with a preset reference number of lines. Here, when the number of error lines exceeds the reference line number, the communication speed set according to the reference line number is designated to the transmission side. In the facsimile apparatus according to claim 3, when executing the ECM communication mode,
On the receiving side, if many errors occur in the frame being received, a signal specifying the communication speed is transmitted to the transmitting side in order to fall down the modem. On the other hand, on the sending side,
When the signal specifying the communication speed is received, the communication speed is changed and the image data transmission is continued even during the frame transmission.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of a facsimile apparatus F according to the present invention. The facsimile apparatus F includes a full-duplex modem for the signal processing section 1 including a CPU, and a facsimile communication control section 2 for communicating with an external facsimile apparatus or the like via a communication line L. A ROM 3a that stores reference data and the like necessary for speed change, a storage unit 3 that includes a RAM 3b that temporarily stores the number of errors in the received image data,
An image reading unit 4 for reading and scanning an original image, a print output unit 5 for printing and outputting an image on a recording sheet, a key operation unit 6 having various operation keys, a display unit 7 including a liquid crystal display or the like. Etc. are connected.

Of the above-mentioned units, the facsimile communication control unit 2 is capable of communicating in the normal communication mode and the ECM communication mode, and at the same time, capable of bidirectionally communicating image data and a predetermined control signal. A heavy modem, a circuit for mutual transmission of protocol signals, a line control unit for controlling line connection with the communication line L, and the like are provided. FIG. 2 is a diagram for explaining the basic operation of the facsimile apparatus F when executing the normal communication mode (for example, G3 mode).

In the signal processing unit 1 on the receiving side, when there are many errors in the image data being received via the facsimile communication control unit 2, the carrier is turned off and the transmission side is set to fall down the modem. Send a signal specifying the communication speed to. On the other hand, when the signal processing unit 1 on the transmission side receives the signal specifying the communication speed via the facsimile communication control unit 2, the communication speed is changed and the image data is transmitted even during the transmission of the image data. Continue (Claim 1). The continuous transmission of the image data may be continued from the current line where the communication speed is changed, or may be traced back by a predetermined line.

In the judgment of changing the communication speed on the receiving side, the number of lines in the received image data determined as an error is sequentially added to the RAM 3b, and each time is compared with the reference line number set in the ROM 3a in advance. . This reference line number is
It is set according to the linear density (reading accuracy). For example, 10 lines for normal and 2 for fine.
0 line, 40 lines for Super Fine. When the number of error lines exceeds the reference line number, the communication speed set according to the reference line number is designated to the transmission side.

In this method of changing the communication speed, the communication speed may be reduced stepwise every time the number of error lines exceeds the reference number of lines, or the number of error lines within a predetermined number of lines within one page The communication speed may be reduced to a corresponding one. Here, the communication speed is, for example, 2400
From 2 bps to 28.8 kbps, there are 12 steps in units of 2400 bps, and it is possible to arbitrarily select from these in accordance with the line status and the like.

FIG. 3 is a diagram for explaining the basic operation of the facsimile apparatus F when executing the ECM communication mode.
On the receiving side, when there are many errors in the frame being received, the carrier is turned off and a signal specifying the communication speed is transmitted to the transmitting side in order to perform the fall down of the modem. On the other hand, when the transmission side receives the signal specifying the communication speed, the communication speed is changed and the frame transmission is continued even during the frame transmission. This frame transmission may be continued from the current frame whose communication speed has been changed, or may be traced back by a predetermined frame.

To determine the communication speed on the receiving side, the number of frames in the received image data determined as an error is sequentially added to the RAM 3b, and each time, the number of frames is compared with the reference number of frames set in the ROM 3a. . The number of reference frames is set according to the linear density (reading accuracy),
For example, the number of frames is 2 for normal, 3 for fine, and 4 for super fine. When the number of error frames exceeds the reference frame number, the communication speed set according to the reference frame number is designated to the transmission side.

In this method of changing the communication speed, the communication speed may be reduced stepwise every time the number of error frames exceeds the reference number of frames, or the number of error frames within a predetermined number of frames within one block The communication speed may be reduced to a corresponding one. Further, in the ECM communication mode, when the change of the communication speed is judged by the number of error frames, when the image data is decoded into the dot data, the line in which the error occurs is judged and judged by the number of the lines. You can also do it.

Next, the above-mentioned operation will be described with reference to a flow chart. FIGS. 4 and 5 show the execution of the normal communication mode. Steps 100 to 108 show the operation on the transmitting side, and steps 110 to 121 show the operation on the receiving side. The communication speeds are mutually determined by opening the modem (steps 101 and 111), and the communication of image data is started.
When the number of error lines exceeds the reference number of lines on the receiving side, the carrier is turned off (step 120). On the transmission side, when carrier off is detected, resynchronization processing (resync) is performed,
The communication speed designated by the receiving side is received, and the communication speed is changed (steps 105 and 106).

FIG. 6 shows the execution time of the ECM communication mode.
Steps 200 to 206 are shown in FIG. 4 in the normal communication mode.
Corresponding to steps 104 to 107. In the figure, one block has 256 frames, and re-synchronization processing is performed when carrier off on the receiving side is detected. The receiving side is similar to the case of the normal communication mode, and the carrier is turned off by the number of error frames.

Next, the procedure for changing the communication speed from the receiving side will be described with reference to FIG. On the receiving side, when changing the communication speed, first, the carrier being transmitted is about 7
Stop for 0 ms. The transmitting side detects the carrier stop on the receiving side and enters the resynchronization sequence. On the transmitting side, the carrier is stopped for about 70 ms, and then the tone A signal is transmitted. The tone A signal includes information indicating the communication speed capability of the transmitting side and a training signal. The receiving side discriminates the training signal and temporarily determines the communicable communication speed including the capability of the transmitting side. . If the tentatively determined communication speed is equal to or faster than the speed before the carrier is stopped, the communication speed is determined to be slow. Then, the communication speed determined by the receiving side is sent to the transmitting side as information of the tone B signal.

Here, the training signal is 150 Hz.
Each tone signal is transmitted up to 3.4 KHz for a predetermined time, and the receiving side determines the optimum communication speed by discriminating the characteristics of the line for each frequency. In the above explanation,
The case where the communication speed is slowed down when many errors occur is shown, but the invention is not limited to this, and the communication speed can be increased by reducing many errors that have occurred.

[0024]

As can be understood from the above description, according to the facsimile apparatus according to the first aspect of the present invention, it is not necessary to stop the communication during the image data communication by designating the communication speed from the receiving side. , Modem fallback can be done with a simple procedure. Also, because the communication time can be shortened,
Communication charges associated therewith can also be saved.

According to the second aspect of the present invention, the communication speed is determined according to the frequency of occurrence of error in the image data, so that appropriate fallback can be performed. According to the facsimile apparatus of the third aspect, the fallback of the modem can be appropriately and promptly performed when the ECM communication mode is executed, so that the communication time can be shortened particularly in the communication with the area where the communication error is likely to occur. Operation can be performed.

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating an example of a basic operation when executing a normal communication mode.

FIG. 3 is a diagram illustrating an example of a basic operation when executing an ECM communication mode.

FIG. 4 is a flowchart showing an example of a basic operation procedure when executing a normal communication mode.

FIG. 5 is a flowchart showing an example of a basic operation when executing a normal communication mode.

FIG. 6 is a flowchart showing an example of a basic operation procedure when executing an ECM communication mode.

FIG. 7 is a diagram illustrating an example of a procedure for changing a communication speed.

[Explanation of symbols]

 F ... Facsimile device 1 ... Signal processing unit 2 ... Facsimile communication control unit 3 ... Storage unit 3a ... ROM 3b ... RAM 4 ... Image reading unit 5 ... Print output Part 6 ... Key operation part 7 ... Display part L ... Communication line

Claims (3)

[Claims] 1. In a facsimile apparatus having a full-duplex modem, when a signal specifying a communication speed is received from a receiving side during transmission of image data, the transmitting side changes the communication speed to the specified speed. Then, the facsimile apparatus is characterized in that the transmission of the image data is continued. 2. The receiving side determines the communication speed according to the number of lines in the received image data that are determined to be in error, and transmits a signal specifying the communication speed to the transmitting side. The facsimile apparatus according to claim 1. 3. When executing a ECM communication mode in which image data is divided into a plurality of frames and transmitted by facsimile, when a signal specifying a communication speed is received from the receiving side during frame transmission, the transmitting side The facsimile apparatus according to claim 1, wherein the communication speed is changed to a designated speed and the frame transmission is continued.