JPH06133146A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To ensure the reception of a command by revising a turn-off threshold level of an RLSD to an opposite station stopping a carrier immediately after the transmission of the command. CONSTITUTION:When a configuration setting section 17 of a modem 4 recognizes the setting of the low speed mode, a changeover discrimination section 20 sends a command of revisit a turn-off threshold level of an RLSD (threshold level) to a modem control section 15. Or the changeover discrimination section 20 sends a command of threshold level revision based not only on the state of the configuration setting section but also on the transmission reception mode setting section set to the reception mode. Furthermore, the function of the changeover discrimination section 20 is activated when a closing flag non- detection section 21 does not detect the closing flag for a prescribed number of times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile machine, and more particularly to a facsimile machine suitable for surely detecting a control command.

[0002]

2. Description of the Related Art In facsimile communication, protocol information (control command) is alternately transmitted between a transmitting side and a receiving side to execute a protocol procedure, and the communication is performed while confirming the states of partner stations. The control command is configured in frame units, and the HDLC frame configuration is typically used in data transmission.

The HDLC frame structure control command includes a start flag indicating the start of a frame and a closing flag indicating the end. Then, when the start flag is detected, the data is fetched from the start flag, and after the closing flag is detected, it is confirmed by the frame check sequence FCS that there is no data error, and the detection of one control command is finally ended.

An example of a facsimile transmission control system for controlling a scheduled operation based on the detection result of a closing flag of a control command is disclosed in Japanese Patent Laid-Open No. 285836.

[0005]

The conventional facsimile apparatus has the following problems. FIG. 6 is a timing chart for explaining the problems of the conventional technique. In the figure, when the last bit of the command data (closing flag) is transmitted, the carrier transmission is immediately stopped at the time t1 and the signal level is lowered. When the level of this signal becomes equal to or lower than the turn-off threshold value (hereinafter, referred to as threshold value) Th of the reception line signal detector (hereinafter, referred to as RLSD) (t2), the carrier transmission stop is recognized. As an example of the threshold value, -4
8 dBm is set.

Generally, received data is temporarily stored in a data storage unit, and the data is analyzed when the predetermined number of data has been stored. Therefore, as described above, if the side sending the command stops sending the carrier immediately after sending the final bit, the side receiving the command may be delayed due to the internal processing of the modem. Before the processing of the last bit is completed, the signal level becomes the threshold value Th.
The following may occur. Therefore, there is a problem that the closing flag cannot be detected and the control command cannot be detected.

On the other hand, there is also an apparatus which sends a closing flag of a plurality of bytes. However, for a device configured to send a closing flag of only 1 byte, a threshold value Th2 (for example, -52 dBm) lower than the threshold value Th is used to recognize the stop of carrier transmission. Had to be delayed until time t3. In this case, noise that could not be detected by the conventional threshold Th is received as much as the threshold is lowered, and there is a problem that normal image information cannot be received.

The object of the present invention is to solve the above problems,
It is an object of the present invention to provide a facsimile device that can reliably detect a low-speed control command and can normally communicate image information that is high-speed data.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems and achieve the object, the present invention provides a modem having an interface of low speed mode and high speed mode which can be arbitrarily selected, and a threshold value of RLSD. The first point is that the threshold value setting means is set in a plurality of stages, and the signal detection by the RLSD is configured to be performed using the threshold value set in a predetermined correspondence relationship with the selected interface. There are features.

Further, the present invention further comprises a counter means for counting the number of times that the control command cannot be normally received, and it is selected after detecting that the count value of the counter means has reached a predetermined number of times. RLSD using the threshold set in the scheduled interface and scheduled correspondence
The second feature is that the signal is detected by the above method.

Further, the present invention is provided with means for detecting that it is in a control command waiting state, and in the control command waiting state, a signal is detected by RLSD using a low threshold value. There is a third feature in that point.

[0012]

According to the present invention having the above-mentioned characteristics, the optimum relationship having a predetermined correspondence relationship with each interface is selected depending on which one of the low speed mode for the transmission procedure signal and the high speed mode for transmitting and receiving the image information is selected. The signal detection operation by RLSD can be performed by using the threshold value of.

In the present invention having the second feature, when it is determined that the control command cannot be normally received,
For the first time, it is possible to execute control in which the threshold value corresponds to the interface. Therefore, when communicating with a partner station that can receive control commands normally, for example, if the partner station is configured to send a closing flag in multiple bytes, leave the threshold fixed at a high value,
It is possible to prevent unnecessary noise from being detected.

Further, according to the present invention having the third feature, it is possible to detect whether or not the control command is awaiting,
This state changes the threshold.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a principal block diagram showing the hardware structure of the facsimile apparatus according to the present invention. In FIG. 1, a reading device 1 reads a document fed from an automatic document feeder (ADF) 2 and converts it into an electric signal (image information).
The image information is encoded by the encoding / decoding device 3 and then transmitted to the line via the modem 4 and the network control unit (NCU) 5.

The modem 4 has low-speed mode and high-speed mode interfaces. The low-speed mode uses the V.V. 21, the high-speed mode is an interface V. 27 ter, V.I. 29, V.I. Three
3, V.I. It is 17 mag. The NCU 5 controls transmission of dial signals and connection with the network.

The image information read by the reading device 1 can be temporarily stored in the image information memory 6 and can be sent to the line in response to a transmission instruction separately given. On the other hand, the image information received from the outside is recorded by the printing device 7 after being decoded by the encoding / decoding device 3.

The operation / display device 8 includes operation switches for giving an instruction to the facsimile device by an operator,
And a panel such as a liquid crystal display system for displaying the operating state. The ROM 9 stores a program for controlling the entire facsimile device and a program for controlling the modem 4 and the NCU 5. RAM10
Is a work area used to execute the program.

The CPU 11 includes the ROM 9 and the RAM
According to the program and control data stored in 10, and the instruction input from the operation / display device 8, the control process and the transmission control procedure process of the entire facsimile device are executed. Data exchange between the above-mentioned components is performed via the system bus 12.

Further, a host computer 13 and a disk device 14 can be connected to the facsimile device and the image information supplied from these can be transmitted to the partner station.
In addition, the host computer 13 and the disk device 14,
It can be connected via an appropriate interface (not shown).

The reception operation of the facsimile apparatus having the above hardware configuration will be described with reference to the flowchart.

First, a first embodiment of the present invention will be described with reference to the flow charts of FIGS. In the first embodiment, the interface condition (hereinafter, referred to as configuration) of the modem 4 is set to the low speed mode, that is, V. 21 is set, the RLSD threshold value is switched to a low value, and other high-speed configurations, that is, the V. 27 ter, V.I. 29, V.I. 33,
V. At 17 mag, the threshold value is switched to the higher one. The lower threshold was -52 dBm and the higher threshold was -48 dBm. Of course, the threshold value is not limited to these values.

In FIG. 3, in step S1, an incoming call is waited for. If an incoming call is detected, the process proceeds to step S2, the configuration is set to the tone mode of 2100 Hz, the transmission / reception mode is set to the transmission mode, and the called station identification signal CED (tone signal of 2100 Hz) is transmitted for 3 seconds. According to the CCITT recommendation, after sending the called station identification signal CED, it is put into a silent state for 75 msec.

In step S3, the configuration is set to the low speed mode for 300 bps, that is, V. 21, the threshold value is set to -52 dBm, and the non-standard function signal NSF or the digital identification signal DIS is transmitted in the transmission mode.

In step S4, the non-standard function setting signal N
Waiting for SS or digital command signal DCS,
Switch the transmission / reception mode to the reception mode. The configuration is V. 21, the threshold remains at -52 dBm.

In step S5, the non-standard function setting signal N
It is determined whether SS or digital command signal DCS is received. If the determination in step S5 is negative, the process proceeds to step S6, and it is determined whether or not the T4 time defined in the recommendation has elapsed. Step S5 until T4 time elapses
If the time T4 has elapsed, the process proceeds to step S7.

In step S7, the configuration is set to the high speed mode and the threshold value is set to -48 dBm to wait for the reception of the training check. The transmission / reception mode remains the reception mode. The high speed mode is the V. 27 ter, V.I. 29, V.I. 33, V.I. It is 17 mag.

In step S8, it is determined whether or not the reception of the training check TCF has been completed. If it is determined that the reception of the training check TCF has been completed, the process proceeds to step S9. In step S9, the configuration is set to the low speed mode V. Two
1, the threshold value is changed to -52 dBm, and the transmission / reception mode is set to the transmission mode.

In step S10, it is determined whether the training check TCF is okay, that is, whether the line condition is good. If the training check TCF is not received correctly, step S
In step 12, the training failure signal FTT is transmitted, and the flow advances to step S4.

Succeedingly, in a step S13 (FIG. 4), the configuration is set to the high speed mode, and the threshold value is set to -48.
Since it is set to dBm and waiting for image information reception, the transmission / reception mode is changed to the reception mode.

In step S14, the image information reception is started, and in step S15, it is determined whether or not the image information reception is completed. This determination is made by the presence or absence of the control return code RTC in the normal G3 mode, and by the presence or absence of the RCP frame reception in the ECM communication mode.

If the end of image information reception is detected, the process proceeds to step S16, and the configuration is set to the low speed mode V.50. 21 and the threshold value is set to -52 dBm. The transmission / reception mode remains in the reception mode because it is waiting to receive the post message command.

In step S17, the post message command is received, and the reception is completed (procedure end) based on its content.
It is determined whether there is EOP or image information, that is, whether there is a next page (MPS, EOM, etc.). End of procedure EOP
If is detected, the process proceeds to step S18, the transmission / reception mode is set to the transmission mode, and the message confirmation signal MCF is transmitted. Here, the configuration is the low-speed mode V. 21, the threshold remains at -52 dBm.

In step S19, the line disconnection command DCN
In order to receive, the transmission / reception mode is set to the reception mode.
The configuration is low speed mode V. 21, the threshold remains at -52 dBm.

In step S20, the line disconnection command DCN
Is received, and if the command is received, the process is terminated.

At step S17, the procedure end EOP
If any post message command other than
Proceeding to step S21, normal phase D processing corresponding to each post message command is performed. When the process of step S21 ends, in response to each post message command, for example, in the case of the multi-page signal MPS, the process proceeds to step S13, and the message end signal EO is sent.
If M, go to step S3. Since the processing of phase D in step S21 is the same as the processing of steps S18 and S19, detailed description thereof will be omitted.

In the first embodiment, the configuration is in the low speed mode, that is, V.S. When it is set to 21, the threshold is switched to the lower one so that the control command can be received. However, depending on the processing method of the partner station, the closing flag may be transmitted in a plurality of bytes, and in this case, it is easy to receive the control command. Therefore, in the communication with such a partner station, it is not necessary to change the threshold value.

In view of such a point, in the second embodiment shown below, communication is performed at a high threshold value at first, and when the closing flag may not be received in some cases, after that, according to the configuration. The threshold is switched to the lower one.

FIG. 5 is a flowchart showing the operation of the second embodiment, which follows FIG. In FIG.
Steps S30 to S32 are steps S13 to S in FIG.
The description is omitted because it is similar to 15.

In step S33, the configuration is set to the low speed mode V.50. Change to 21. Threshold is -4
8 dBm, the transmission / reception mode remains the reception mode.

In step S34, it is determined whether the control command has been received. If the control command has been received, then in step S35, it is determined whether the control command has been normally received. If the control command is successfully received, the process proceeds to step S36.

At step S36, the procedure end EOP or
It is determined whether it is MPS or EOM indicating that there is still image information. If the procedure end EOP is detected, the process proceeds to step S37, the transmission / reception mode is set to the transmission mode, and the message confirmation signal MCF is transmitted. Here, the configuration is the low-speed mode V. 21. The threshold value is set to -48 dBm when the threshold value flag is "0" and -52 dBm when the threshold value flag is "1" according to the state of the threshold value flag described later.

In step S38, the line disconnection command DCN
In order to receive, the transmission / reception mode is set to the reception mode.
The configuration is low speed mode V. 21, the threshold value is held as it is set in step S37.

In step S39, the line disconnection command DCN
Is received, and if the command is received, the process is terminated.

At step S36, the procedure end EOP
If any post message command other than
Normal phase D processing corresponding to each post message command is performed. This process is the same as step S2.
The processing is the same as that of No. 1, and illustration and description thereof will be omitted.

On the other hand, if the control command cannot be received normally, the process proceeds from step S35 to step S40. In step S40, it is determined whether or not the closing flag has been detected. If the closing flag is detected, the process proceeds to step S41, and the threshold value flag is set to "0". Here, the configuration, the threshold value, and the transmission / reception mode remain unchanged in step S33.

When the closing flag is not detected, the process proceeds from step S40 to step S42, and it is determined whether or not the value of the counter indicating the number of times the closing flag is not detected is the same as the expected value. When this determination is negative, the process proceeds to step S43 and the count value is incremented (+1).

If the value of the counter becomes the same as the expected value, the determination at step S42 becomes affirmative and step S4.
Go to 4. In step S44, the configuration and transmission / reception mode are left unchanged, and only the threshold value is
Change to 52 dBm. In step S45, "1" is set in the threshold flag.

As described above, in the second embodiment, the configuration is V.50. 21 and the threshold flag is "1", the threshold value is low, that is, -5.
It is set to 2 dBm.

Of course, the scheduled value to be compared with the counter value is not limited to a plurality of times. Therefore, by setting the scheduled value to be compared with the value of the counter to "1", the threshold flag is set to "1" when the closing flag cannot be detected even once, and thereafter, The configuration is V. If set to 21, the threshold is set to -52 dBm.

In the embodiment described above, the configuration is in the low speed mode, that is, V.50. 21 is set as a condition for setting the threshold value to −52 dBm, but the fact that the transmission / reception mode is the reception mode may be added to this condition. By doing so, the threshold can be changed to -52 dBm only when a control command is received.

Next, the essential functions required for the operation of the above embodiment will be described with reference to the block diagram of FIG. 1, the same reference numerals as those in FIG. 2 indicate the same or equivalent parts. In the figure, the protocol procedure control unit 16 executes protocol control based on the program stored in the ROM 9 and the control data set in the RAM 10. The modem control unit 15 controls the modem 4 according to the instruction of the protocol control unit 16. That is, the configuration setting unit 17, the RLSD threshold value setting unit 18, and the transmission / reception mode setting unit 19 are instructed at predetermined timings to set the configuration, the threshold value, and the transmission / reception mode.

Of the conditions set in the modem 4, the configuration and the transmission / reception mode are first determined. Then, finally, the threshold value set in the RLSD threshold value setting unit 18 is determined. That is, the switching determination unit 2
0 identifies the set configuration by looking at the state of the configuration setting unit 17. Then, when the identified configuration is for the low speed mode, a detection signal is output to the modem control unit 15. When this detection signal is supplied, the modem control unit 15 outputs an instruction to the RLSD threshold value setting unit 18 to set a lower threshold value among a plurality of stages prepared.

In addition to the condition that the transmission / reception mode is the reception mode, the switching determination unit 20 does not output the detection signal based on only the configuration, and the modem control unit 15 outputs the detection signal. You may make it output to.

Further, as shown in the flow chart of FIG. 5, it is also possible to make the judgment by the switching judgment section 20 on condition that the closing flag cannot be received normally. Therefore, the closing flag non-detecting unit 21 monitors the communication control unit 22 and outputs a signal for incrementing the count value to the counter 23 when the closing flag cannot be detected and the control command cannot be normally received. The case where the control command cannot be normally received is, for example, when the carrier of the post message command is disconnected without performing the flag check sequence FCS after receiving the preamble of the post message command and receiving the data. .

When the counter 23 reaches the preset value, it outputs a count-up signal to the switching determination section 20. When the time-up signal is supplied, the switching determination unit 20 thereafter determines whether the configuration is in the low-speed mode or in the low-speed mode and the reception mode in the communication currently being executed. Then, a detection signal for setting the threshold value to a low value is output to the modem control unit 15.

In the embodiment of the present invention described above, when the control command cannot be normally received, the threshold value is set to be suitable for receiving the control command based on the configuration or the configuration and the transmission / reception mode. I changed it. However, as described above, the selection of whether or not to change the threshold value so as to be suitable for receiving the control command does not depend on whether or not the control command can be received, but is set in the RAM 10 as system data in advance. It may be performed based on the setting.

In this embodiment, only the operation on the side of receiving the image information is shown, but the protocol procedure is the same on the side of transmitting the image information, and the same processing as in this embodiment can be performed. Of course.

[0059]

As is apparent from the above description, according to the present invention, when the modem configuration is set to the mode for receiving the control command, or in addition thereto, the modem is set to the receiving mode. In the meantime, the threshold set in RLSD, that is, the turn-off threshold is changed to facilitate detection of the closing flag of the control command. Therefore, the control command cannot be detected due to the internal control of the modem.

According to the second aspect of the invention, only when the control command cannot be received, it is judged for the first time whether the configuration is set to the control command receiving mode or the receiving mode. The threshold value is changed according to the result of the judgment to facilitate detection of the closing flag of the control command. Therefore, according to the partner station, the switching process for changing the threshold value can be performed only when necessary.

Further, according to the invention of claim 3, since the threshold value is lowered only when the control command is received, it is possible to sufficiently deal with the image information which is a high speed signal, and the normal image information is displayed. Can receive.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main function of a facsimile apparatus.

FIG. 2 is a block diagram showing a hardware configuration of a facsimile apparatus.

FIG. 3 is a flowchart showing an operation (No. 1) of the first embodiment.

FIG. 4 is a flowchart showing an operation (No. 2) of the first embodiment.

FIG. 5 is a flowchart showing the operation of the second embodiment.

FIG. 6 is a timing chart showing carrier transmission stop timing.

[Explanation of symbols]

4 ... Modem, 5 ... NCU, 15 ... Modem control unit,
16 ... Protocol procedure control unit, 17 ... Configuration setting unit, 18 ... RLSD threshold setting unit,
19 ... Transmission / reception mode setting unit, 20 ... Switching determination unit, 21
... Closing flag non-detection section, 23 ... Counter

Claims (3)

[Claims] 1. A modem comprising a low-speed and high-speed mode interface which can be arbitrarily selected, and threshold setting means for setting a turn-off threshold value of a reception line signal detector in a plurality of stages. A facsimile machine characterized in that signal detection by the line signal detector is performed by using a turn-off threshold value set in a predetermined correspondence relationship with the selected interface. 2. A counter means for counting the number of times a control command could not be normally received, further comprising a counter means for detecting the number of times the count value of the counter means has reached a predetermined number, and then selecting the selected interface with the selected interface. 2. The facsimile apparatus according to claim 1, wherein the turn-off threshold value set by the correspondence relationship is used to perform signal detection by the reception line signal detector. 3. A control command waiting means is provided, and in the control command waiting state,
The signal detection by the reception line signal detector is performed by using a lower value among the turn-off threshold values set in a plurality of steps.
Alternatively, the facsimile machine according to the item 2.