JPH06303280A - Modem equipment for facsimile - Google Patents

Abstract

PURPOSE:To prevent the extension of a communication time caused by an reception error by monitoring the reception of a picture data signal by means of a fast modem function and monitoring the reception of a procedure signal by means of a slow modem function to always and surely receive the procedure signal. CONSTITUTION:A slow modem 4 executing transmission control by transmitting/ receiving the procedure signal and a fast modem 4 transmitting/receiving a picture data signal are provided to be connected to CPU 7 to execute facsimile communication. Then, when the procedure signal is transmitted in the period of waiting for the transmission of picture data by the fast modem 4, the slow modem 7 receives the transmitted procedure signal without being controlled by CPU 7 so as to temporarily store received signal information in a memory 9 and to report the reception of the procedure signal to CPU 7 to send the signal to CPU 7. Consequently, the transmitted procedure signal can always be received and not sent to a transmission side again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to CCITT Recommendation G3.
(Group 3) The present invention relates to a modem device suitable for facsimile.

[0002]

2. Description of the Related Art A modem of a G3 facsimile apparatus which is generally used is CCITT Recommendation V.3. 21 compliant low speed modem and Recommendation V.21. 29 and V.I. It has two communication functions with a high-speed modem compliant with 27ter.

The CPU of the main body of the facsimile apparatus controls the above-mentioned modem to appropriately select the two communication functions. Then, the low-speed modem transmits and receives a procedure signal to perform transmission control, and the high-speed modem transmits and receives an image data signal.

FIG. 6 shows an example of a transmission control procedure of such a facsimile machine. That is, assuming that a call is made from the transmitting side to the receiving side, the receiving side first sends out a DIS signal by the low speed modem.

The transmitting side also receives the DIS signal by the low speed modem and sends out the DCS signal. Then use a high speed modem
Send a CF signal.

When the receiving side receives the DCS signal, the receiving side receives the TCF signal by the high speed modem and executes a predetermined modem training operation. If this training operation is successful, the low speed modem sends out a CFR signal. Then, the high-speed modem waits for the image data signal to be transmitted from the transmitting side.

By the way, it is assumed that a transmission error occurs in the transmitted CFR signal and the transmission side cannot correctly receive the signal. In this case, the transmitting side waits for a certain period of time and then repeats DC
It sends out an S signal and a TCF signal.

At this time, the receiving side is set to the receiving state of the high speed modem, but when the DCS signal is sent out at this time,
The signal is determined to be a procedure signal, and the mode is switched to the reception state of the low speed modem.

This switching control is executed by the CPU of the facsimile apparatus main body. At this time, the CPU may delay the switching control of the modem due to other control operations. If this switching control is delayed, the DCS signal cannot be received correctly. In this case, the received procedure signal is DC
Since it cannot be determined that the signal is the S signal, it becomes impossible to switch to the receiving state of the high speed modem. Therefore, the receiving side cannot receive the subsequent TCF signal either, and as a result, cannot send the predetermined response signal.

When there is no response from the receiving side, the transmitting side sends the DCS signal and the TCF signal again after a certain period of time.

Since the receiving side has switched to the receiving state of the low speed modem at this time, it is possible to finally receive the DCS signal correctly and switch to the high speed modem. Then, after that, the TCF signal can be received and a predetermined response signal such as a CFR signal can be transmitted.

When the transmitting side receives the CFR signal, it sends out the image data signal, and the receiving side receives the image data signal.

As described above, when the transmitting side fails to receive the CFR signal, the time T at which the DCS signal or the like is retransmitted twice is given.
Only 1, it took extra communication time.

By the way, the RTC code is set at the end of the image data signal sent from the transmitting side, and when the receiving side receives the RTC code, it switches to the receiving state of the low speed modem.

Here, for example, as shown in FIG. 7, it is assumed that a transmission error occurs at the end of the image data signal and the receiving side fails to detect the RTC code.

After transmitting the image data signal, the transmitting side transmits an EOP signal or the like by a low speed modem. The receiving side is RTC
When the code detection is unsuccessful, the EOP signal is received and the mode is switched to the low speed modem.

However, in this case, as described above, the CP
There was a case where the switching control of U was delayed and the EOP signal could not be correctly received. Then, the response signal cannot be sent to the transmitting side.

When there is no response from the receiving side, the transmitting side sends the EOP signal again after a certain period of time. The receiving side receives the retransmitted EOP signal and sends a predetermined response signal such as an MCF signal. When the transmitting side receives the MCF signal, it transmits the DCN signal and ends the communication.

As described above, when the receiving side fails to detect the RTC code, an extra communication time is required for the time T2 at which the EOP signal is retransmitted.

[0020]

As described above, conventionally, there is a problem in that the procedure signal cannot be correctly received and the communication time becomes long due to the delay in switching from the high speed modem to the low speed modem. was there.

It is an object of the present invention to solve the above problems and to provide a facsimile modem device capable of reducing the extension of communication time.

[0022]

To this end, the present invention, in a high-speed modem, controls the CPU when a procedure signal is transmitted during the period of waiting for the image data signal to be transmitted. Without receiving the procedure signal, the low-speed modem receives the procedure signal transmitted, temporarily stores the received signal information in the memory, notifies the CPU of the receipt of the procedure signal, and sends the signal information to the CPU. I have to.

[0023]

The transmitted procedure signal can always be reliably received, and it is not necessary for the transmitting side to retransmit the signal, so that the extension of the communication time can be reduced.

[0024]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a facsimile apparatus according to an embodiment of the present invention. In the figure, a scanner 1 reads a document image, and a plotter 2 records and outputs a received image. The encoding / decoding unit 3 compresses the image data to be transmitted by various encoding methods, while decoding the received data signal to restore the original image data.

The modem 4 is a CCITT recommendation V. 21 compliant low speed modem and Recommendation V.21. 29 and V.I. 27t
It has two communication functions with a high-speed modem compliant with er. The network control device 5 is connected to a telephone line and performs predetermined line control when making or receiving a call. Operation display section 6
Indicates that the operator performs various operations and the device displays an operating state and the like.

The CPU 7 monitors and controls each of the above parts, and the ROM 8 stores a control program for the CPU 7 and fixed data. The RAM 9 temporarily stores various data during the communication operation as necessary. The system bus 10 is a signal line for exchanging various control signals and data between the above respective units.

The modem 4 is composed of a transmitting circuit and a receiving circuit. FIG. 2 shows the receiving circuit. In the figure, a signal reception demodulation section 41 demodulates a received modulated wave signal into a baseband signal. The high-speed modem data reproducing section 42 reproduces training check data and image data.

The low speed modem receiving section 43 receives the procedure signal. Although the procedure signal is transmitted in the HDLC frame structure, the low-speed modem receiving unit 43 receives HDL.
Data reproducing means 43 for reproducing the received data of the C frame
a and flag detection means 43b for detecting the flag of the HDLC frame. The RAM 44 temporarily stores the signal information of the received procedure signal, that is, the data of the HDLC frame. The switch 45 is for selecting the output of the high speed modem data reproducing section 42 or the RAM 44. The low-speed mode switching unit 46 determines that a procedure signal has been received and switches to the reception mode of the low-speed modem when a certain number of the above flags are detected.

When the facsimile apparatus of the present embodiment is used with the above configuration, the operator must perform a predetermined operation beforehand.
The number of flags for determining that a procedure signal has been received is set arbitrarily. Now, let the set count value be N.

First, the operation of the receiving circuit of the modem 4 will be described.

This receiving circuit starts the operation shown in FIG. 3 every time it is initialized by the CPU 7. That is, the receiving circuit first initializes to the high speed communication mode.
In this high speed communication mode, the switch 45 is switched to the high speed modem data reproducing unit 42 side. Further, the respective operations of the signal receiving / demodulating section 41, the high speed modem data reproducing section 42, the flag detecting means 43b and the low speed mode switching section 46 become effective (process 201).

Then, the reception of the data signal is monitored by the high speed modem function (process 202, N of the process 202), and the reception of the procedure signal is monitored by the low speed modem function (process 203, from process N to process 202). ).

Here, for example, assume that a TCF signal or an image data signal is transmitted from the other party. In this case (Y of process 202), the signal reception demodulation unit 41 receives the transmitted signal and demodulates it into a baseband signal. Then, the high speed modem data reproducing unit 42 reproduces and outputs the received data (process 204). The output data is sent to the CPU 7 via the switch 45.
When this receiving operation ends, the process returns to the monitoring of the received signal (Process 2).
03).

Further, it is assumed that the procedure signal is transmitted. Since the procedure signal is transmitted in the HDLC frame structure, a plurality of flags are first received. This flag is 1
It is known 1-byte data in hexadecimal notation “7E”.

The flag detecting means 43b detects the flag to be received, and the low speed mode switching section 46 counts the number of received flags. When the set count value N is received, it is determined that the procedure signal is received. In this case (Process 2
03), and switch to the low speed communication mode. In the low speed communication mode, the switch 45 is switched to the RAM 44 side,
The operation of the data reproducing means 43a becomes effective (process 20).
5). Next, the CPU 7 is notified that the procedure signal has been received (process 206).

The data reproducing means 43a uses the HDL
The signal information of the procedure signal received in the C frame is reproduced to R
It is stored in the AM 44 (process 207). After this, CPU7
Thus, the reading control of the RAM 44 is executed.
In that case, the signal information stored in the RAM 44 is output to the CPU 7 according to the reading control (process 208). When this operation ends, the process returns to the monitoring of the received signal (to step 203).

The receiving circuit of the modem 4 operates as described above. On the other hand, the transmission circuit of the modem 4 is controlled by the CPU 7 as in the conventional case, and transmits the TCF signal, the image data signal and the procedure signal.

Next, the operation when the facsimile apparatus of this embodiment receives an image by receiving an image from another facsimile apparatus will be described.

FIG. 4 shows an example of the transmission control procedure in this case. That is, when receiving a call, the facsimile apparatus of the present embodiment initializes the modem 4 and then transmits a DIS signal by the transmission circuit.

When the DIS signal is sent, DC is sent from the sending side.
The S signal and the TCF signal are transmitted. When the DCS signal is received, the receiving circuit of the modem 4 enters the low speed communication mode and receives the DCS signal, as described in FIG.
Then, the CPU 7 is notified that the procedure signal has been received. Based on this notification, the CPU 7 reads the signal information stored in the RAM 44, determines that the signal is a DCS signal, and initializes the receiving circuit of the modem 4 again. This puts the receiving circuit in the high-speed communication mode. Then, it receives the subsequent TCF signal, reproduces and outputs the received data. The CPU 7 reads the output reproduction data and executes a predetermined training process. When this training process is successful, the CFR signal is transmitted.

Here, it is assumed that a transmission error occurs in the transmitted CFR signal and the transmitting side fails to receive the signal. In this case, the transmitting side retransmits the DCS signal and the TCF signal after a lapse of a certain time.

In this embodiment, at this time, the high-speed communication mode is in a state of waiting for the reception of the image data signal. However, similarly to the above, the reception of the DCS signal switches to the low-speed communication mode, and the DCS signal is changed. Receive correctly.

As a result, the CPU 7 causes the received signal to be DC.
It is determined that the signal is the S signal, and the receiving circuit of the modem 4 is initialized. Here, the receiving circuit enters the high-speed communication mode and correctly receives the TCF signal. This allows the CPU
7 executes a predetermined training process and, if the training process is successful, sends out a CFR signal.

After this, the image data signal is transmitted from the transmitting side.

Since the modem 4 is in the high speed communication mode at this time, it receives the image data signal and reproduces and outputs the image data. The CPU 7 decodes the output image data by the encoding / decoding unit 3 and records the image on the plotter 2.

By the way, an RTC code for instructing switching to the low speed communication mode is added to the end of the image data signal of each page. Now, assume that the facsimile apparatus fails to detect the RTC code due to a transmission error as shown in FIG.

Then, the receiving circuit of the modem 4 receives, for example, the EOP signal in the high speed communication mode. In this case, receiving the EOP signal causes the receiving circuit to
Similar to the above, switch to the low speed communication mode and
Receive the signal correctly.

As a result, the CPU 7 correctly determines the EOP signal and sends a predetermined response signal such as the MCF signal. When the transmitting side receives the MCF signal, it transmits the DCN signal. Then, both ends the communication.

As described above, in the present embodiment, the receiving circuit of the modem 4 sends the CP when the procedure signal is transmitted even while waiting for the image data signal in the high speed communication mode.
The procedure signal is automatically received by automatically switching to the low-speed communication mode without the control of U7. Then, while the reception information of the procedure signal is temporarily stored in the RAM 44, the CPU 7 is notified that the procedure signal is received, and C
The signal information is transmitted according to the reading operation of the PU 7.

Thus, as shown in FIG. 4, even if the transmission side fails to receive the CFR signal, the extension of the communication time is
Time T at which the transmitting side retransmits the DCS signal and the TCF signal once
Only 3 is required, and the time T1 in the case of FIG. 6 can be shortened.

Further, as shown in FIG. 5, even if the detection of the RTC code of the image data signal fails, the communication time is not extended unlike the case of FIG.

In this embodiment, when a fixed number of flags of the HDLC frame transmitted prior to the procedure signal are received, it is determined that the procedure signal has been received, and the fixed number can be set by the operator. ing.

The number of flags of the above HDLC frame is not necessarily constant depending on the device specifications. Further, if the count value is set to a large value, erroneous determination can be prevented, but it takes time to make the determination. Therefore, by setting the above-mentioned fixed number according to the device of the communication partner, it becomes possible to judge the reception of the procedure signal under appropriate conditions.

The RAM 44 shown in FIG. 2 is arranged exclusively for storing the signal information of the procedure signal, but an empty memory of the modem circuit may be used. Generally, such a modem circuit has a DSP (Digit).
RO with al Signal Processor)
M and RAM are provided. In this case, in the low speed communication mode, a part of the RAM used in the high speed communication mode becomes empty. The empty area of the RAM can be used for storing the reception information of the procedure signal. By utilizing the free area of the RAM, it is not necessary to provide a dedicated memory as the RAM 44.

In the above embodiment, the communication function of the high speed modem is based on Recommendation V.34. 29 and V.I. Although it is made to comply with the V.27ter, for example, V.27ter. Of course, other recommendations such as 17 may be complied with.

Although an example of the basic transmission control procedure has been described with reference to FIGS. It goes without saying that it can be similarly applied to various transmission control procedures conforming to 30.

[0058]

As described above, according to the present invention, when the procedure signal is transmitted while the high speed modem is waiting for the image data signal, the procedure is performed by the low speed modem without the control of the CPU. While receiving the signal and temporarily storing the received information in the memory, the CPU is notified that the procedure signal is received,
Since the signal information received is sent to the CPU,
The procedure signal can always be reliably received, and the extension of the communication time can be reduced.

[Brief description of drawings]

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

FIG. 2 is a circuit configuration diagram of a receiving circuit of a modem.

FIG. 3 is an operation flowchart of the receiving circuit.

FIG. 4 is an explanatory diagram showing an example of a transmission control procedure.

FIG. 5 is an explanatory diagram showing another example of a transmission control procedure.

FIG. 6 is an explanatory diagram showing an example of a conventional transmission control procedure.

FIG. 7 is an explanatory diagram showing another example of a conventional transmission control procedure.

[Explanation of symbols]

 1 Scanner 2 Plotter 3 Encoding / Decoding Section 4 Modem 5 Network Control Device 6 Operation Display Section 7 CPU 8 ROM 9,44 RAM 10 System Bus 41 Signal Reception Demodulation Section 42 High Speed Modem Data Reproduction Section 43 Low Speed Modem Reception Section 43a Data Reproduction Means 43b Flag detecting means 45 Switch 46 Low speed mode switching unit

Claims (3)

[Claims] 1. A facsimile modem device having a low-speed modem for transmitting / receiving a procedure signal to execute transmission control and a high-speed modem for transmitting / receiving an image data signal, and executing facsimile communication under the control of an external CPU, If the procedure signal is transmitted while the high-speed modem is waiting for the image data signal to be transmitted from the other party, the procedure signal transmitted without the control of the CPU is transmitted to the low-speed modem. Receiving means for receiving by
A memory for temporarily storing the received signal information, and the external C
A facsimile modem device comprising: a notification means for notifying the PU that a procedure signal has been received; and a sending means for sending the signal information to an external CPU thereof. 2. The HDLC indicates that the procedure signal is transmitted.
2. The facsimile modem apparatus according to claim 1, further comprising: a unit for determining by receiving a fixed number of frame flags and a unit for arbitrarily setting the fixed number in advance. 3. The memory is a memory that is used during the communication operation of the high-speed modem and is not used during the communication operation of the low-speed communication modem and is vacant.
The described facsimile modem device.