JP3551595B2 - Communication device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication device such as a facsimile device that determines connection with a partner machine based on the polarity reversal of a line, and particularly, in the case where the polarity of the line is reversed a plurality of times when connecting to the partner machine, the polarity of the line is determined for each partner machine. The present invention relates to a communication device that learns the number of inversions and can quickly and reliably determine a connection with a partner device based on the learning result.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a communication apparatus such as a facsimile apparatus configured to detect inversion of a line polarity when connecting to a partner machine and determine connection with the partner machine based on a detection result of the polarity inversion. ing.
[0003]
For example, in a facsimile apparatus, a predetermined transmission control procedure is executed when connecting to a partner machine. In order to shorten the transmission control procedure, apparatuses having various shortening procedure (shortening protocol) capabilities are required. When a call is made to a partner machine that has this shortened protocol capability, it is first detected that the line has been reversed, and it is determined that connection has been established with the partner device by reversing the line polarity. In response to this, a short procedure transition signal is transmitted, and the procedure is shifted to a predetermined short procedure in accordance with the short procedure transition signal.
[0004]
As this type of facsimile apparatus, a facsimile apparatus disclosed in JP-A-61-98064 is conventionally known. In the facsimile apparatus disclosed in Japanese Patent Application Laid-Open No. 61-98064, a polarity reversal detection circuit for detecting that a line has been connected, a telephone number of a destination and a model of the facsimile apparatus connected to the line ( Function), and a control signal sending circuit for notifying the other party that the procedure is abbreviated, and reading out the model of the corresponding partner device from the memory circuit at the time of automatic calling. Determines whether the other party's facsimile device connected to the line of the telephone number of the partner device has a control function based on the shortening procedure, and if the shortening procedure is possible, a polarity reversal signal of the line from the partner device after calling. Immediately after being detected by the polarity reversal detection circuit, the control signal transmission circuit transmits a control signal notifying the partner device of the shortened procedure. To have.
[0005]
[Problems to be solved by the invention]
By the way, in a communication device such as a facsimile device, the polarity of a line may be inverted a plurality of times during a period from when a call is made to when the communication device is connected to the other device. This phenomenon occurs depending on the configuration of the communication network to which the partner device is connected, and the number of polarity inversions that occur from this call until connection to the partner device differs for each partner device. .
[0006]
In such an environment, for example, as in a facsimile apparatus disclosed in Japanese Patent Application Laid-Open No. 61-98064, a control signal for informing the partner machine of the shortening procedure is transmitted to the partner machine when the polarity reversal of the line is detected once. In such a configuration, a control signal indicating that the procedure is the shortening procedure may be sent out even though the partner machine is not actually connected. In this case, the procedure cannot be shifted to the shortening procedure. The problem arose.
[0007]
Accordingly, it is an object of the present invention to provide a communication device capable of quickly and reliably determining a connection with a partner device even in an environment in which line polarity reversal occurs a plurality of times when connecting to the partner device. I do.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention described in claim 1 is
In a communication device that determines the connection with the partner device based on the polarity inversion of the line,
Polarity inversion detection means for detecting the polarity inversion of the line,
Polarity inversion number counting means for counting the number of polarity inversions detected by the polarity inversion detection means,
Polarity inversion number storage means for storing the number of polarity inversions that occur upon connection with the partner device corresponding to the partner device,
Connection discrimination for judging connection with the partner device when the number of polarity reversals counted by the polarity reversal number counting unit at the time of connection with the partner device reaches the number of polarity reversals stored in the polarity reversal number storage unit. Means
It is characterized by having.
[0009]
According to such a configuration, the connection with the partner device can be quickly and reliably determined even in an environment where the polarity of the line is inverted a plurality of times when connecting to the partner device.
[0010]
Also, since the number of polarity inversions is stored in the polarity inversion number storage means in correspondence with each partner device, quick and reliable operation can be performed for partner devices in which the number of line polarity inversions that occur during connection differs. The connection can be determined.
[0011]
The invention of claim 2 is the invention according to claim 1,
The other machine is
A facsimile machine,
The polarity inversion number storage means,
It stores the number of polarity inversions counted by the polarity inversion number counting means from when a call is made to the other party to when a facsimile signal is received from the other party.
[0012]
That is, in the second aspect of the invention, when the partner machine is a facsimile machine, the polarity reversal number storage means stores the number of times from when a call is made to the partner machine until a facsimile signal is received from the partner machine. Then, the number of polarity inversions counted by the polarity inversion number counting means is stored in correspondence with the counterpart device, thereby making it possible to determine an optimum connection in accordance with the counterpart device.
[0013]
The invention of claim 3 is:
When a facsimile signal is received from the partner machine before the number of polarity inversions counted by the polarity inversion number counting unit reaches the number of polarity inversions stored in the polarity inversion number storage unit during connection with the partner machine, It is characterized in that the number of polarity inversions stored in the polarity inversion number storage means corresponding to the partner machine is cleared.
[0014]
According to such a configuration, it is possible to cope with a change in the number of polarity inversions of the partner device.
[0015]
The invention of claim 4 is:
When a facsimile signal is received from the partner machine before the number of polarity inversions counted by the polarity inversion number counting unit reaches the number of polarity inversions stored in the polarity inversion number storage unit during connection with the partner machine, It is characterized in that the number of polarity inversions stored in the polarity inversion number storage means corresponding to the partner machine is updated with the number of polarity inversions counted by the polarity inversion number counting means at this time.
[0016]
According to such a configuration, the number of polarity inversions corresponding to each partner device can be learned and updated in the polarity reversal number storage means, thereby, for example, changing the configuration of the communication network to which the partner device is connected. In such a case, appropriate measures can be taken.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a communication device according to the present invention will be described in detail with reference to the accompanying drawings.
[0018]
FIG. 1 is a block diagram showing a schematic configuration of a communication device according to the present invention.
[0019]
In FIG. 1, a communication device 10 of this embodiment includes a polarity inversion detecting unit 11, a polarity inversion number counting unit 12, a polarity inversion number storage unit 13, and a connection determination unit 14.
[0020]
Here, the polarity inversion detecting means 11 detects the inversion of the polarity of the line 20 when the communication apparatus 10 calls the other party (not shown). The detection of the polarity inversion in the polarity inversion detecting means 11 may be a method of directly detecting the polarity inversion of the line 20 or a structure of detecting a polarity inversion signal transmitted from a communication network (not shown) via the line 20. It may be something.
[0021]
The polarity inversion number counting means 12 counts the number of polarity inversions detected by the polarity inversion detection means 11. Here, the counting of the polarity inversion by the polarity inversion number counting means 12 is started by calling from the communication device 10, and the counting of the polarity inversion by the polarity inversion number counting device 12 is performed by the communication device 10. It may be configured to start during a call.
[0022]
The polarity inversion number storage means 13 stores in advance the number of polarity inversions that occur upon connection to the partner device. Here, the number of polarity inversions in the polarity inversion number storage means 13 is stored in correspondence with each partner device, for example, the telephone number or abbreviated number of the partner device.
[0023]
The storage of the number of polarity inversions in the polarity inversion number storage means 13 may be configured to store the number of polarity inversions detected in advance for each partner device by some means, or may be configured in practice. A calling operation is performed, and the number of polarity inversions detected at the time of the calling operation is automatically stored in the polarity inversion number storage means 13 in correspondence with the partner machine that has performed the calling operation. You may.
[0024]
In this embodiment, the partner device in which the number of polarity inversions is stored in the polarity inversion number storage means 13 is referred to as a partner device whose polarity inversion number is “learned”, and the number of polarity inversions is stored in the polarity inversion number storage device 13. Are stored as "unlearned state".
[0025]
If the called party is a "learned" partner, the connection discriminating means 14 stores the number of polarity reversals counted by the polarity reversal number counting means 12 at the time of connection with the partner, and stores the number of polarity reversal times in the memory. When the number of times of the polarity inversion stored in step 13 is reached, it is determined that connection has been established with the partner device.
[0026]
If the communication device 10 is, for example, a facsimile device, the polarity counted by the polarity reversal frequency counting means 12 from when a call is made to the partner device until a facsimile signal is received from the partner device. The number of inversions may be stored in the polarity inversion number storage means 13 corresponding to the counterpart device.
[0027]
Here, for example, before the number of polarity inversions counted by the polarity inversion number counting means 12 at the time of connection with the partner device of “learned” reaches the number of polarity inversions stored in the polarity inversion number storage unit 13, When a facsimile signal is received from, the number of polarity inversions stored in the polarity inversion number storage means 13 corresponding to the counterpart is cleared, and the counterpart is returned to the “unlearned state”. Alternatively, the number of polarity inversions stored in the polarity inversion number storage means 13 corresponding to the partner machine may be updated with the number of polarity inversions counted by the inversion number counting means 12 at this time. You may comprise.
[0028]
FIG. 2 shows an embodiment of a facsimile apparatus constituted by applying the communication apparatus of the present invention. The facsimile apparatus is configured so as to be switchably connected to both a digital network such as an ISDN (Integrated Services Digital Network) and an analog public network, and a CPU (central processing unit) 31 for controlling the entire facsimile apparatus. , A RAM (random access memory) 32 constituting a work area used by a control program of the CPU 31, an operation display device 33 for operating the facsimile machine 3, a reading device 34 for reading a transmission original, and recording of a received image and the like. A printing device 35, an image processing device 36 for encoding, decoding, enlarging and reducing image signals, an image storage device 37 for storing image information, and a ROM (read) for storing a control program for controlling the entire facsimile device. A system control unit 38 having an on-line memory; , For example, a communication control unit having a ROM for storing a program for G4 facsimile, a communication control unit for controlling communication suitable for an analog network, for example, a ROM for storing a program for G3 facsimile 40, a modem 41 which is a modem having a low-speed mode and a high-speed mode, a line switching control device 42 for connecting a plurality of external line interfaces and a plurality of internal communication lines, and a digital network control for connecting to the digital network 21 The apparatus 43 includes an analog network controller 44 having an automatic transmission / reception function and connected to the analog network 22, and a system bus 45 for exchanging data between functional blocks.
[0029]
Here, when connecting this facsimile apparatus to the analog network 22, the communication control unit 34 and the digital network control unit 43 can be omitted. When connecting to the digital network 21, the communication control unit 40 and The modem 41 and the analog network controller 44 can be omitted.
[0030]
The polarity inversion detecting means 11 shown in FIG. 1 is realized by the analog network controller 44 shown in FIG. 2, and the polarity inversion number counting means 12, the polarity inversion number storage means 13, and the connection judging means 14 shown in FIG. Is realized by the parts of the CPU 31, the RAM 32, and the system control unit 38 shown in FIG.
[0031]
Next, the transmission operation of the facsimile apparatus of this embodiment will be described with reference to the control flowcharts of the transmission protocol shown in FIGS.
[0032]
FIG. 3 is a control flowchart showing the transmission protocol of the facsimile apparatus of this embodiment.
[0033]
First, when a call is made to the other party (step 101), it is checked whether or not the other party has a short protocol reception capability (step 102). Here, whether or not the partner machine has the shortened protocol receiving capability is previously stored in the destination data list stored in a predetermined storage area of the RAM 32 shown in FIG. Have been.
[0034]
That is, in step 102, the destination data list in the RAM 32 is searched based on the abbreviated number of the called party, and it is determined whether or not the other party has the shortened protocol receiving capability.
[0035]
If it is stored that the other party has the short protocol reception capability (YES in step 103), the transmission phase A is executed (step 112). Details of the transmission phase A will be described later with reference to FIG.
[0036]
When the transmission phase A is completed, it is determined whether or not the transmission phase A has shifted to the shortened protocol (short professional) transmission (step 113). If it has shifted to the shortened protocol transmission (YES in step 113) Then, the transmission phase B is executed (step 114). Details of the transmission phase B will be described later with reference to FIG.
[0037]
When the transmission phase B is completed, it is determined whether or not the transmission phase B has shifted to the short protocol (short professional) transmission (step 115). If the transmission phase B has shifted to the short protocol transmission (YES in step 115) Then, the transmission phase C is executed (step 116). Details of the transmission phase C will be described later with reference to FIG.
[0038]
When the transmission phase C ends, a transmission phase D is executed (step 117). Details of the transmission phase D will be described later with reference to FIG.
[0039]
When the transmission phase D is completed, it is checked whether or not to shift to the transmission phase C in the transmission phase D (step 118). Here, when shifting to transmission phase C (YES in step 118), the process returns to step 116, and when not shifting to transmission phase C (NO in step 118), next, in transmission phase D, the process proceeds to transmission phase B. It is checked whether or not to shift (step 119). Here, when shifting to the transmission phase B (YES in step 119), the process returns to step 114, and when not shifting to the transmission phase B (NO in step 119), a low-speed DCN (disconnection command signal) is transmitted. End the transmission protocol.
[0040]
If it is not stored in step 103 that the other party has the shortened protocol receiving capability, first, a CNG (calling tone) of 1100 Hz is transmitted (step 104), and then the other party sends a CED (called terminal). It is checked whether an identification signal) or any command has been received (step 105). If CED or any command has not been received (NO in step 105), the process returns to step 104, and CNG is transmitted again. If the CED or any command has been received (YES in step 105), it is checked whether an NSF (non-standard function identification signal) has been received from the partner device (step 106), and the NSF has been received. In this case (YES in step 106), it is checked whether the received NSF is the company's NSF (step 108), and the received NSF is the company's NSF. In this case, it is checked whether or not the NSF of the company includes information indicating that there is a shortened protocol transmission capability (step 108). If the NSF includes information indicating that there is a shortened protocol transmission capability (YES in step 108), In the destination data list of the RAM 32 shown in FIG. 2 described above, the fact that there is a shortened protocol receiving capability is stored corresponding to the shortened number of the partner machine (step 109), and the process proceeds to step 114 to execute the transmission phase B.
[0041]
If it is determined in step 106 that the NSF has not been received, that is, if a DIS (digital identification signal) has been received (NO in step 106), it is determined that the NSF received in step 107 is not its own NSF. In this case (NO in step 107), or when it is determined in step 108 that the NSF of the company does not include information indicating that there is a shortened protocol transmission capability (NO in step 108), the destination in the RAM 32 shown in FIG. Corresponding to the abbreviated number of the partner machine in the data list, it stores that there is no abbreviated protocol reception capability (step 110), performs normal transmission (step 111), and ends this transmission protocol.
[0042]
Also, if it is determined in step 113 that transmission mode A has not shifted to the shortened protocol transmission (NO in step 113), or if it is determined in step 115 that transmission mode B has not shifted to the shortened protocol transmission (NO in step 115), it is determined that the transmission is normal transmission, and the flow advances to step 106 to check whether NSF has been received from the partner device.
[0043]
FIG. 4 shows details of the processing in the transmission phase A of step 112 shown in FIG. In the transmission phase A, first, it is checked whether or not the partner device has a polarity reversal detection function (step 121). Here, whether or not the partner device has the polarity reversal detection function is stored in advance in the destination data list of the RAM 32 shown in FIG. 2 in correspondence with, for example, the abbreviated number of the partner device.
[0044]
That is, in step 121, the destination data list in the RAM 32 is searched based on the abbreviated number of the called party, and it is checked whether or not the called party has a polarity reversal detection function.
[0045]
Here, if the partner device has a polarity reversal detection function (YES in step 121), a CNG (calling tone) transmission start timer is started (step 127), and it is determined whether polarity reversal is detected. (Step 127). Here, the detection of the polarity inversion is determined by whether or not the number of polarity inversions has reached the number of polarity determinations learned during the previous communication with the partner device, as described later in detail. If the number of polarity determinations learned during the previous communication with the device has been reached (YES in step 127), the process shifts to the short protocol (short program) transmission (step 133).
[0046]
If no polarity reversal is detected in step 127, that is, if the number of polarity reversals has not reached the number of polarity determinations learned during the previous communication with the partner device (NO in step 127), the next CNG transmission is performed. It is checked whether or not the start timer has timed out (step 128). If the CNG transmission start timer has not timed out (NO in step 128), the process returns to step 127, and if the CNG transmission start timer has timed out (step 128). (YES at 128), CNG (calling tone) is transmitted (step 129), and it is checked again whether polarity inversion has been detected (step 130). As will be described later in detail, the detection of the polarity inversion is determined based on whether or not the number of polarity inversions has reached the number of polarity determinations learned during the previous communication with the partner device. If the polarity reversal is detected here, that is, if the number of polarity reversals has reached the number of polarity determinations learned during the previous communication with the partner device (YES in step 130), the shortened protocol (short professional) transmission is performed. (Step 133).
[0047]
If no polarity reversal is detected in step 130, that is, if the number of polarity reversals does not reach the number of polarity determinations learned during the previous communication with the partner device (NO in step 130), then the CED (called It is checked whether or not the terminal identification signal has been received (step 131). If the CED has been received (YES in step 131), the process shifts to the short protocol (short professional) transmission (step 133).
[0048]
If it is determined in step 131 that the CED has not been received (NO in step 131), it is determined whether a low-speed command has been received (step 132). If no low-speed command has been received (step 132). (NO), return to step 129, transmit CNG (calling tone) again, and if it is determined that a low-speed command has been received (YES in step 132), shift to normal transmission (step 125).
[0049]
If it is determined in step 121 that the other party does not have the polarity reversal detection function (NO in step 121), CNG (calling tone) is transmitted (step 122), and then CED (called terminal identification) is performed. (Step 123), and if a CED is received (YES in Step 123), the flow shifts to a short protocol (short professional) transmission (Step 133).
[0050]
If it is determined in step 123 that the CED has not been received (NO in step 123), it is determined whether a low-speed command has been received (step 124). If no low-speed command has been received (step 124). (NO), return to step 122, transmit CNG (calling tone) again, and when it is determined that the low-speed command has been received (YES in step 124), shift to normal transmission (step 125).
[0051]
FIG. 5 shows details of the processing in the transmission phase B of step 114 shown in FIG. In the transmission phase B, first, it is checked whether polling is performed (step 141). If not polling, a signal for instructing a shift to the shortened protocol is transmitted (step 142), and a high-speed NSS (non-standard function setting signal) is transmitted. (Step 143) is performed, and it is checked whether a response has been received from the partner device (Step 144).
[0052]
Here, if a response has been received from the partner device (YES in step 144), it is checked whether a high-speed NSF (non-standard function identification signal) has been received (step 148), and if a high-speed NSF has been received (step 148). (YES in 148), and shifts to short protocol (short program) transmission (step 150).
[0053]
If the high-speed NSF has not been received in step 148, that is, if a low-speed command such as NSF / DIS has been received (NO in step 148), the process proceeds to normal transmission (step 149).
[0054]
If it is determined in step 144 that no response has been received from the partner device (NO in step 144), it is checked whether polarity inversion has been detected (step 145).
[0055]
As will be described later in detail, the detection of the polarity inversion is also made based on whether or not the number of polarity inversions has reached the number of polarity determinations learned during the previous communication with the partner device.
[0056]
If the polarity inversion is not detected in step 145 (NO in step 145), the fallback parameter is set (step 146), the process returns to step 142, and a signal for instructing the shift to the shortened protocol is sent again (step 142). High-speed NSS (non-standard function identification signal) transmission (step 143) is performed.
[0057]
If the polarity reversal is detected in step 147 (YES in step 147), the communication speed of the initial value is reset (step 147), and the process returns to step 142 to transmit a signal for instructing the shift to the shortened protocol again. (Step 142), high-speed NSS (non-standard function identification signal) transmission (Step 143).
[0058]
In other words, if the partner machine has a polarity reversal detection function, it detects polarity reversal even when waiting for a response from the partner machine, and sets the initial communication speed when polarity reversal is detected. Perform the process again.
[0059]
If it is determined in step 141 that polling has been performed (YES in step 141), a signal for instructing a shift to the shortened protocol is sent (step 151), and a high-speed NSC (non-standard function command signal) is sent (step 152). Then, it is checked whether a response has been received from the partner device (step 153).
[0060]
Here, if a response has been received from the partner device (YES in step 153), it is checked whether a high-speed NSS (non-standard function setting signal) has been received next (step 157), and if a high-speed NSS has been received (step 157). (YES at 157), and proceeds to reception phase B described later with reference to FIG. 9 (step 159).
[0061]
If the high-speed NSS has not been received in step 157, that is, if a low-speed command such as NSS / DIS has been received (NO in step 157), the process proceeds to normal transmission (step 158).
[0062]
If it is determined in step 153 that no response has been received from the partner device (NO in step 153), it is determined whether polarity inversion has been detected (step 154).
[0063]
As will be described later in detail, the detection of the polarity inversion is also made based on whether or not the number of polarity inversions has reached the number of polarity determinations learned during the previous communication with the partner device.
[0064]
If the polarity inversion is not detected in step 154 (NO in step 154), the fallback parameter is set (step 155), the process returns to step 151, and a signal for instructing the shift to the shortened protocol is sent again (step 151). A high-speed NSC (non-standard function setting signal) is transmitted (step 152).
[0065]
If the polarity inversion is detected in step 154 (YES in step 154), the communication speed of the initial value is reset (step 156), and the process returns to step 151 to send a signal for instructing the shift to the shortened protocol again. (Step 151), high-speed NSC (non-standard function setting signal) transmission (Step 152) is performed.
[0066]
FIG. 6 shows details of the processing in the transmission phase C of step 116 shown in FIG. In this transmission phase C, it is first checked whether or not the image information is to be retransmitted (step 161). If it is determined that the image information is not to be retransmitted (NO in step 161), the NSS (No. A non-standard function setting signal is input and transmitted (step 162), and then the image information is transmitted in a frame (step 163), and it is checked whether the transmission of the image information has been completed (step 164). If not completed (NO in step 164), the process returns to step 163. If completed (YES in step 164), the contents of the post message command are put into an RCP (partial page control return) frame and transmitted (step 164). 165), then return.
[0067]
In step 161, if the image information is retransmitted (YES in step 161), the image information to be retransmitted is put in a frame and transmitted (step 166), and it is determined whether the retransmission of this image information has been completed. (Step 167) If not completed (NO in Step 167), the process returns to Step 166. If completed (YES in Step 167), the contents of the post message command are added to the RCP (partial page control return signal) frame. And send it out (step 165), and then return.
[0068]
FIG. 7 shows details of the processing in the transmission phase D of step 117 shown in FIG. In this transmission phase D, first, it is checked whether a response from the partner device has been received (step 171). If no response has been received (NO in step 171), the low-speed post by PPS-Q or PPS-PriQ is performed. The message command is transmitted, and the process returns to step 171.
[0069]
If a response from the partner machine has been received in step 171 (YES in step 171), it is checked whether a low-speed MCF (message confirmation signal) has been received next (step 173), and if a low-speed MCF has been received (step 173). YES), and proceed to step 186.
[0070]
If it is determined in step 173 that a low-speed MCF has not been received (NO in step 173), it is checked whether a low-speed PPR (partial page request signal) has been received (step 174). If a PPR has been received (YES in step 174), it is checked whether a CTC (correction continuation signal) needs to be transmitted (step 177). If necessary (YES in step 177), a low-speed CTC is transmitted (step 178). If a low-speed CTR (correction continuation response signal) is received (YES in step 179), the process proceeds to transmission phase C (step 187).
[0071]
If it is determined in step 177 that transmission of CTC (correction continuation signal) is not necessary (NO in step 177), it is next checked whether transmission of EOR (retransmission end signal) is necessary (step 180). If necessary (YES in step 180), the low speed EOR is transmitted (step 181), and when the low speed ERR (retransmission end response signal) is received (YES in step 182), the process proceeds to step 186.
[0072]
If it is determined in step 182 that a low-speed ERR (retransmission end response signal) has not been received, it is checked whether a low-speed PIN (procedure interruption denial signal) has been received (step 183). (YES at 183), a line hold procedure is performed (step 184), and the routine proceeds to step 186.
[0073]
If the low-speed PPR is not received in step 174 (NO in step 174), it is checked whether a low-speed PIP (procedure interruption acknowledgment signal) has been received next (step 175). (YES at 175), a line hold procedure is performed (step 185), and the routine proceeds to step 186.
[0074]
When the low-speed PIP is not received in step 175 (NO in step 175), a predetermined error process is performed (step 176), and the process proceeds to step 186.
[0075]
In step 186, the next procedure determines which of the transmission phase C, the transmission phase D, and the transmission phase E is based on the transmitted post message command. When it is determined that the next procedure is the transmission phase C, the process proceeds to the transmission phase C (step 189), and when it is determined that the next procedure is the transmission phase D, the process proceeds to the transmission phase D (step 190). When it is determined that the transmission phase is E, the process proceeds to the transmission phase E (step 191).
[0076]
Next, the receiving operation of the facsimile apparatus of this embodiment will be described with reference to the control flowchart of the receiving protocol shown in FIGS.
[0077]
FIG. 8 is a control flowchart showing the reception protocol of the facsimile apparatus of this embodiment.
[0078]
When there is an incoming call from the other party (step 201), a 1.8-second timer is started (step 202), and it is checked whether a signal instructing a shift to the shortened protocol is received (step 203).
[0079]
Here, when a signal is received (YES in step 203), first, reception phase B is executed. Details of the reception phase B will be described later with reference to FIG.
[0080]
When the receiving phase B ends, the receiving phase C is executed next. Details of the reception phase C will be described later with reference to FIG.
[0081]
When the receiving phase C ends, the receiving phase D is executed next. Details of the receiving phase D will be described later with reference to FIG.
[0082]
When the reception phase D is completed, it is checked whether or not the reception phase D shifts to the reception phase C (step 207). Here, in the case of shifting to the receiving phase C (YES in step 207), the process returns to step 205, and in the case of not shifting to the receiving phase C (NO in step 207), the receiving phase B is next set in the receiving phase D. It is checked whether or not the process has shifted to the receiving phase (Step 208). If the process has shifted to the receiving phase B (YES in Step 208), the process returns to Step 204. Since the transition is to E, a low-speed DCN (disconnection command signal) is received (step 209), and this reception protocol ends.
[0083]
If it is not determined in step 203 that the received signal is not a signal instructing a shift to the shortened protocol (NO in step 203), it is next checked whether CNG (calling tone) is received (step 210). (NO in step 210) It is checked whether or not the 1.8 second timer has timed out (step 211). If it has not timed out (NO in step 211), the process returns to step 203, and if it has timed out (YES in step 211). , CED (called terminal identification signal) is transmitted (step 212).
[0084]
If it is determined in step 210 that CNG has been received, the process proceeds to step 212, where CED (called terminal identification signal) is transmitted.
[0085]
When the CED is transmitted in step 212, it is checked again whether a signal instructing the shift to the shortened protocol is received (step 213). Here, when it is determined that the signal instructing the shift to the shortened protocol is received (YES in step 213), the transmission of the CED is stopped (step 214), and the receiving phase B of step 204 is executed.
[0086]
If it is determined in step 213 that the signal for instructing the shift to the abbreviated protocol is not received, it is determined whether the CED transmission is completed (step 215). If not, the CED transmission is not completed (NO in step 215). Returning to 212, when it is determined that the CED transmission has been completed (YES in step 215), NSF / DIS is transmitted (step 216), and it is checked whether a signal instructing the shift to the shortened protocol has been received (step 217). . Here, if it is determined that the received signal is a signal instructing the shift to the shortened protocol (YES in step 217), the process proceeds to step 204 to execute the receiving phase B.
[0087]
If it is determined in step 217 that the received signal is not a signal instructing a shift to the shortened protocol (NO in step 217), normal reception is performed (step 218), and the reception protocol is terminated.
[0088]
FIG. 9 shows details of the processing in the reception phase B of step 204 shown in FIG. In the reception phase B, first, it is checked whether or not a high-speed NSS (non-standard function setting signal) is received (step 211). If the high-speed NSS is received (YES in step 211), a high-speed NSF (non-standard function identification signal) is transmitted (step 222), and the process returns.
[0089]
If the high-speed NSS is not received in step 211 (NO in step 211), it is checked whether the high-speed NSC (non-standard function command signal) is received (step 223). Here, if the reception is not high-speed NSC (NO in step 223), the process returns to step 221. If the high-speed NSC is received (YES in step 223), it is checked whether polling is OK (step 224). Here, in the case of polled OK (YES in step 224), the process proceeds to transmission phase B shown in FIG. 5 (step 225), and in the case of not polled OK (NO in step 224), a predetermined error process is executed (step 224). Step 226).
[0090]
FIG. 10 shows details of the processing in the reception phase C of step 205 shown in FIG. In the receiving phase C, first, it is checked whether an FCD (facsimile coded data) frame is received (step 231). If the FCD frame is received (YES in step 231), the NSS (non-standard function) It is checked whether information of the setting signal has been received (step 232). If the information is received from the NSS (YES in step 232), the NSS is analyzed (step 235), and the process returns to step 231.
[0091]
If it is determined in step 232 that NSS information has not been received (NO in step 232), the received image information is accumulated (step 233), and it is checked whether or not frame reception has been completed (step 234). If the frame reception has not been completed (NO in step 234), the process returns to step 231. If the frame reception has been completed (YES in step 234), the process returns.
[0092]
If it is determined in step 231 that the received message is not an FCD frame (NO in step 231), the received message is an RCP frame, so the contents of the post message command of the RCP frame are analyzed (step 236). To return.
[0093]
FIG. 11 shows details of the processing in the reception phase D of step 206 shown in FIG. In the receiving phase D, first, it is checked whether an RCP (partial page control return signal) frame has been received (step 241). Here, if an RCP frame has been received (YES in step 241), the flow advances to step 243. If it is determined in step 241 that an RCP frame has not been received (NO in step 241), it is checked whether a low-speed command has been received (step 242). If a low-speed command has been received (step 242). YES), and proceed to step 243.
[0094]
In step 243, it is checked whether the FCD (facsimile coded data) frame is OK. If the FCD frame is OK (YES in step 243), then it is checked whether it is line hold (step 244). (YES in step 244), executes a line hold procedure (step 246), and proceeds to step 256.
[0095]
If it is determined in step 244 that it is not line hold (NO in step 244), a low-speed MCF (message confirmation signal) is transmitted (step 245), and the flow advances to step 256.
[0096]
If it is determined in step 243 that the FCD frame is not OK (NO in step 243), a low speed PPR (partial page request signal) is transmitted (step 247), and then a CTC (correction continuation signal) is received. Investigation (step 248). When the CTC is received (YES in step 248), a low-speed CTR (correction continuation response) is transmitted (step 249), and the process proceeds to the reception phase C (step 250).
[0097]
If the CTC has not been received in step 248 (NO in step 248), it is checked whether an EOR (retransmission end signal) has been received (step 251). If the EOR has not been received (step 251). NO), and the process proceeds to the receiving phase C (step 252).
[0098]
If it is determined in step 251 that the EOR has been received (YES in step 251), it is checked whether the line is held (step 253). If the line is held (YES in step 253), the line is held. The procedure is executed (step 255), and the process proceeds to step 256.
[0099]
If it is determined in step 253 that it is not line hold (NO in step 253), a low-speed ERR (retransmission end response signal) is transmitted (step 254), and the flow proceeds to step 256.
[0100]
In step 256, it is determined whether the next procedure is any of the reception phase C, the reception phase D, and the reception phase E based on the received post message command (step 256). If it is determined that the next procedure is the reception phase C, the process proceeds to the reception phase C (step 257), and if it is determined that the next procedure is the reception phase D, the process proceeds to the reception phase D (step 258). If it is determined that the receiving phase is E, the process proceeds to receiving phase E (step 259).
[0101]
Next, a basic transmission / reception protocol procedure of the facsimile apparatus realized by the control flowcharts shown in FIGS. 3 to 11 will be described with reference to sequence charts shown in FIGS. Here, FIGS. 12 to 15 show basic transmission / reception protocol procedures in three cases of mode transition to the shortened protocol.
[0102]
FIG. 12 shows a first case of mode transition to the abbreviated protocol. In this first case, the transmitting side first makes a call (Calling) and stores the transmitting side storage means (FIG. 2). In the destination data list of the RAM 32), it is checked whether or not the shortened protocol receiving capability is stored corresponding to the abbreviated number of the partner device (receiving side) (step 103 in FIG. 3). If so, it is checked whether the other party (reception side) is actually measuring the polarity reversal detection function (step 121 in FIG. 4). If the polarity reversal detection function is actually measured, the polarity reversal is checked. (Steps 127 and 130 in FIG. 4), when the polarity inversion is detected, a signal instructing the shift to the shortening protocol is transmitted (Step 142 in FIG. 5). It proceeds to executes the simplified protocol.
[0103]
On the other hand, on the receiving side, upon receiving the call, it is checked whether or not a signal instructing the shift to the shortened protocol has been received from the transmitting side until the transmission of the CED (called terminal identification signal) (step 203 in FIG. 8). Upon receiving a signal instructing a shift to the shortened protocol, the process shifts to the shortened protocol and executes the shortened protocol.
[0104]
In the abbreviated protocol, the transmission side first sends a high-speed NSS (non-standard function setting signal) following a signal indicating the communication speed of the high-speed command (a signal instructing a shift to the abbreviated protocol) (see FIG. 5). Step 143) Waiting for a high-speed NSF (non-standard function identification signal) from the partner device (receiving side), and receiving a high-speed NSF from the partner device (receiving side) (step 148 in FIG. 5), the image information transmission phase (Transmission phase C in FIG. 6).
[0105]
When the receiving side receives a high-speed NSS having a communication speed indicated by a signal indicating the communication speed of the high-speed command from the transmission side (a signal instructing the transition to the shortened protocol) (step 221 in FIG. 9), (Step 222 in FIG. 9), and the process proceeds to the image information reception phase (reception phase C in FIG. 10).
[0106]
In the image information transmission phase (transmission phase C) on the transmission side, the image information is divided into ECM (error correction mode) frames and transmitted. Here, the following image information parameters are set in the first frame of the ECM frame, and image information is transmitted in the second and subsequent frames (FCD frames). The first frame may be the content of the previously transmitted NSS itself, or may be only the parameter indicating the image information to be transmitted.
[0107]
When the transmission of the image information is completed in this way, an RCP frame in which the content corresponding to the post message command is set in the facsimile information field is transmitted (step 165 in FIG. 6), and a response command waiting phase (the transmission phase in FIG. 7) Go to D).
[0108]
In the image information reception phase (reception phase C) on the reception side, the image information transmitted from the transmission side while being divided by the ECM frame is received. When the reception of the image information is completed, an RCP frame in which the content corresponding to the post message command is set in the facsimile information field is received, and the content of the post message command of the RCP frame is analyzed (step 236 in FIG. 10). The process proceeds to a response command waiting phase (reception phase D in FIG. 11).
[0109]
In the response-side command waiting phase (transmission phase D) on the transmission side, when the MCF (message confirmation signal) is received (step 173 in FIG. 7), the image is matched with the contents of the post message command set in the destination RCP frame. It is determined whether to shift to the information transmission frame (transmission phase C), to the transmission phase B, or to the transmission phase E (Step 186 in FIG. 7), and to shift to each transmission phase.
[0110]
Also, in the receiving-side response command waiting phase (transmission phase D), if an MCF (message confirmation signal) is transmitted (step 245 in FIG. 11), the MCF is matched with the content of the post message command set in the received RCP frame. It is determined whether to shift to the image information reception frame (reception phase C), to the reception phase B, or to the reception phase E (step 256 in FIG. 11), and to shift to each reception phase. .
[0111]
Then, when the transmission side shifts to the transmission phase E, it transmits a DCN (disconnection command signal) (step 120 in FIG. 3), and ends this transmission protocol.
[0112]
When the receiving side shifts to the receiving phase E, when receiving the DCN from the transmitting side, the receiving protocol ends.
[0113]
FIG. 13 shows a second case of mode transition to the abbreviated protocol. In this second case, the transmitting side first performs calling (Calling), and the transmitting side storage means (FIG. 2). In the destination data list in the RAM 32), it is checked whether or not the shortened protocol receiving capability is stored corresponding to the abbreviated number of the partner device (reception side) (step 102 in FIG. 3), and stored as the abbreviated protocol receiving capability. If so, it is checked whether the other party (reception side) is actually measuring the polarity reversal detection function (step 121 in FIG. 4). If the polarity reversal detection function is actually measured, the polarity reversal is checked. If the CED (called terminal identification signal) is detected before the polarity reversal is detected (steps 127 and 130 in FIG. 4), the short protocol is started. By sending a signal indicating the transition shifts to the simplified protocol (step 142 in FIG. 5), it executes the simplified protocol.
[0114]
If the other party (reception side) has not actually measured the polarity reversal detection function, it performs CED detection while transmitting CNG (calling tone) (steps 122 and 123 in FIG. 4). Then, a signal for instructing the transition to is transmitted (step 142 in FIG. 5), and the procedure shifts to the shortened protocol, and the shortened protocol is executed.
[0115]
On the other hand, on the receiving side, upon receiving the call, it is checked whether or not a signal instructing the shift to the shortened protocol has been received from the transmitting side until the transmission of the CED (called terminal identification signal) (step 203 in FIG. 8). If the CED must be transmitted without receiving the signal, the CED is transmitted (step 212 in FIG. 8), and while transmitting the CED, it is checked whether a signal instructing the shift to the shortened protocol is received. (Step 213 in FIG. 8), upon receiving a signal instructing the shift to the shortened protocol, stops sending the CED, shifts to the shortened protocol, and executes the shortened protocol.
[0116]
The processing after shifting to the shortened protocol is the same as that shown in FIG.
[0117]
FIG. 14 shows a third case of mode transition to the abbreviated protocol. In this third case, the transmitting side first makes a call (Calling) and stores the transmitting side storage means (FIG. 2). In the destination data list of the RAM 32), it is checked whether or not the shortened protocol receiving capability is stored corresponding to the abbreviated number of the partner device (receiving side) (step 102 in FIG. 3), and it is stored that there is no abbreviated protocol receiving capability. If it is detected, the CED or command is detected while transmitting CNG (step 105 in FIG. 3), and when NSF (non-standard function identification signal) is received (step 106 in FIG. 3), the received NSF It is checked whether the NSF is the NSF of the device (step 107 in FIG. 3). 108), if the abbreviated protocol reception capability is available, the storage means on the transmission side (the destination data list in the RAM 32 in FIG. 2) stores the abbreviated protocol reception capability corresponding to the abbreviated number of the partner device (reception side). (Step 109 in FIG. 3), and thereafter, a signal instructing the shift to the shortened protocol is transmitted (Step 142 in FIG. 5), the shift to the shortened protocol is performed, and the shortened protocol is executed. If the above condition is not met, transmission is performed by a normal protocol.
[0118]
On the other hand, on the receiving side, upon receiving the call, it is checked whether or not a signal instructing the shift to the shortened protocol has been received from the transmitting side until the transmission of the CED (called terminal identification signal) (step 203 in FIG. 8). If the CED must be transmitted without receiving the signal, the CED is transmitted (step 212 in FIG. 8), and while transmitting the CED, it is checked whether a signal instructing the shift to the shortened protocol is received. (Step 213 in FIG. 8) If the transmission of the CED is terminated without receiving the signal, the NSF and DIS (CIS if necessary) indicating the capability of receiving the shortened protocol are transmitted (Step 216 in FIG. 8). Further, it is checked whether a signal instructing the transition to the shortened protocol has been received (step 217 in FIG. 8). To run the col. If the above conditions are not met, reception is performed using a normal protocol.
[0119]
The processing after shifting to the shortened protocol is the same as that shown in FIG.
[0120]
By the way, in the case of the first case shown in FIG. 12 among the three cases of the mode transition to the shortened protocol described above, when the polarity inversion is detected before the connection with the partner device, at this point, the switch to the shortened protocol is performed. A signal for instructing the transition is transmitted, and the transition to the shortened protocol is performed.
[0121]
Here, in this embodiment, the number of polarity inversions that have occurred in the past up to the connection with the counterpart machine with respect to the same counterpart machine is learned, and the learned number of polarity inversions is stored in the RAM 32 shown in FIG. In the destination data list, for example, each of the partner devices is stored in correspondence with the abbreviated number of the partner device, and when a call is made to the partner device, the number of line reversals of the line is the learned polarity reversal stored in the destination data list. When the number of times has been reached, a signal for instructing the transition to the shortened protocol is transmitted to shift to the shortened protocol.
[0122]
Hereinafter, the detailed processing of the characteristic portion of the above embodiment will be described with reference to the flowcharts shown in FIGS.
[0123]
FIG. 15 is a flowchart showing the details of the processing performed by the facsimile apparatus of this embodiment when making a call.
[0124]
In FIG. 15, first, when a call is made (step 301), counting of the number of reverse (polarity inversion) detected by the digital network controller 43 or the analog network controller 44 of FIG. 2 is started (step 302). ). Then, the destination data list of the partner device having the shortened protocol (short program) reception capability of the RAM 32 shown in FIG. 2 is searched (step 303).
[0125]
Here, if it is stored that the other party has the shortened protocol receiving capability (step 304), then the other party has learned the number of polarity inversions, that is, the polarity inversion corresponding to this other party. It is checked whether or not the number of times is stored (step 305). If the number of times of polarity inversion has been learned (YES in step 305), the reverse (polarity inversion) is detected every time a reverse (polarity inversion) is detected (YES in step 306). ) Count the number of times (step 306).
[0126]
Then, it is checked whether the counted number of reverse (polarity inversion) has reached the learned number of reverse (polarity inversion) occurrences stored in the destination data list of the RAM 32 shown in FIG. 2 (step 308). (NO in step 308), the process returns to step 306, and continues counting the number of times of reverse (polarity inversion).
When it arrives (YES in step 308), it sends out a signal instructing a shift to the shortened protocol, that is, a special tone (step 309).
[0127]
Next, based on the NSF (non-standard function setting signal) from the partner machine, it is checked whether or not the partner machine has a short protocol (short professional) reception capability (step 310). If there is, communication is performed using the shortened protocol (step 311). If there is no communication, the communication is performed by the normal protocol (step 316), and this process ends.
[0128]
Also, if it is stored in step 304 that there is no shortened protocol receiving capability for this partner machine (NO in step 304), or if it is determined in step 305 that this partner machine has not learned the polarity reversal frequency. (NO in step 305), every time reverse (polarity inversion) is detected (YES in step 312), the number of reverse (polarity inversion) is counted (step 313), and CED (called terminal identification Signal (YES in step 314), it is next checked whether or not the other party has a shortened protocol (short professional) reception capability based on the NSF (non-standard function setting signal) from the other party (step 315). In this case (YES in step 315), the other party is registered in the destination data storing the other party having the shortened protocol (short professional) reception capability. Step 317) further stores a polarity reversal number counted at this point in the destination data (step 318), the process proceeds to step 309, sends a special tone is a signal that instructs the transition to the simplified protocol.
[0129]
If it is determined in step 315 that the partner machine does not have the short protocol (short program) reception capability (NO in step 315), communication is performed using the normal protocol (step 316), and this process ends.
[0130]
FIG. 16 shows one method of countermeasures in the case where the number of reverses (polarity inversions) generated before connection with the partner device is different from the number of learned reverses (polarity inversions) in the processing shown in FIG. It is a thing.
[0131]
In the configuration shown in FIG. 16, in step 308 shown in FIG. 15, the count value of the number of times of reverse (polarity inversion) is determined by the occurrence of the learned reverse (polarity inversion) stored in the destination data list of the RAM 32 shown in FIG. If the CED (Called Terminal Identification Signal) is detected before the number of times is reached, that is, if the terminal is actually connected to the destination (YES in step 319), the polarity in the destination data of the RAM 32 shown in FIG. The storage of the number of inversions is cleared to return to the non-learned state (step 320), and the process proceeds to step 309. Other processes are the same as the processes shown in FIG.
[0132]
In this case, the number of occurrences of the reverse (polarity inversion) with respect to the partner machine is re-learned.
[0133]
FIG. 17 shows another method of countermeasures in the case where the number of reverses (polarity inversions) generated before connection with the counterpart machine is different from the number of learned reverses (polarity inversions) in the processing shown in FIG. It is a thing.
[0134]
In the configuration shown in FIG. 17, in step 308 shown in FIG. 15, the count value of the number of times of reverse (polarity inversion) is determined by the occurrence of the learned reverse (polarity inversion) stored in the destination data list of the RAM 32 shown in FIG. If the CED (Called Terminal Identification Signal) is detected before the number of times has been reached, that is, if the terminal is actually connected to the other terminal (YES in step 319), the number of polarity inversion occurrences counted this time is shown in FIG. It is stored in the destination data of the RAM 32 (step 321), and the process proceeds to step 309. Other processes are the same as the processes shown in FIG.
[0135]
According to this configuration, the number of occurrences of the reverse (polarity inversion) for this counterpart machine stored in the destination data of the RAM 32 shown in FIG. There is no.
[0136]
According to the facsimile apparatus of this embodiment, since the number of times of polarity reversal occurring until connection to the partner machine is learned, the connection with the partner machine in which polarity reversal occurs a plurality of times before connection is achieved. It is possible to accurately determine the timing of connecting to the other party's machine, and it is also possible to use ITU-T. In addition to preventing the inconvenience of transmitting a special signal not specified in 30 and transmitting a special signal instructing to immediately shift to the shortened protocol by connecting to the partner device, an opportunity for shifting to the shortened protocol can be provided. Can be more.
[0137]
【The invention's effect】
As described above, according to the present invention, the polarity reversal frequency counting means for counting the number of local line polarity reversals detected by the polarity reversal detecting means at the time of connection with the partner device is provided, and A polarity reversal frequency storage means is provided which learns the number of times of polarity reversal occurring upon connection with the partner device and stores the number in advance and stores the number of polarity reversals counted by the polarity reversal frequency counting means upon connection with the partner device. When the number of polarity inversions stored in the means has been reached, it is configured to determine that connection has been established with the counterpart device, so even in an environment where line polarity reversal occurs multiple times when connecting to the counterpart device, This has the effect that the connection with the partner device can be determined quickly and reliably.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a communication device according to the present invention.
FIG. 2 is a block diagram showing one embodiment of a facsimile apparatus configured by applying the communication device of the present invention.
FIG. 3 is a control flowchart showing a transmission protocol of the facsimile apparatus shown in FIG.
FIG. 4 is a flowchart showing details of processing in a transmission phase A shown in FIG. 3;
FIG. 5 is a flowchart showing details of processing in a transmission phase B shown in FIG. 3;
FIG. 6 is a flowchart showing details of processing in a transmission phase C shown in FIG. 3;
FIG. 7 is a flowchart showing details of processing in a transmission phase D shown in FIG. 3;
FIG. 8 is a control flowchart showing a transmission protocol of the facsimile apparatus shown in FIG.
FIG. 9 is a flowchart showing details of processing in a reception phase B shown in FIG. 8;
FIG. 10 is a flowchart showing details of processing in a reception phase C shown in FIG. 8;
FIG. 11 is a flowchart showing details of processing in a reception phase D shown in FIG. 8;
FIG. 12 is a sequence chart showing a first case of a mode transition to a shortened protocol in the facsimile apparatus shown in FIG. 2;
FIG. 13 is a sequence chart showing a second case of mode transition to the shortened protocol in the facsimile apparatus shown in FIG. 2;
FIG. 14 is a sequence chart showing a third case of a mode transition to a shortened protocol in the facsimile apparatus shown in FIG. 2;
FIG. 15 is a flowchart showing details of processing at the time of calling in the facsimile apparatus shown in FIG. 2;
FIG. 16 is a flowchart showing another example of the details of the processing at the time of calling in the facsimile apparatus shown in FIG. 2;
FIG. 17 is a flowchart showing still another example of the details of the processing at the time of calling in the facsimile apparatus shown in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Communication apparatus, 11 ... Polarity reversal detection means, 12 ... Polarity reversal frequency counting means, 13 ... Polarity reversal frequency storage means, 14 ... Connection discriminating means, 20 ... Line, 31 ... CPU (Central Processing Unit), 32 ... RAM (random access memory), 33 operation display device, 34 reading device, 35 printing device, 36 image processing device, 37 image storage device, 38 system control unit, 39 communication control unit, 40 communication Control unit, 41: Modem, 42: Line switching controller, 43: Digital network controller, 44: Analog network controller, 45: System bus

Claims (4)

In a communication device that determines the connection with the partner device based on the polarity inversion of the line,
Polarity inversion detection means for detecting the polarity inversion of the line,
Polarity inversion number counting means for counting the number of polarity inversions detected by the polarity inversion detection means,
Polarity inversion number storage means for storing the number of polarity inversions that occur upon connection with the partner device corresponding to the partner device,
Connection discrimination for judging connection with the partner device when the number of polarity reversals counted by the polarity reversal number counting unit at the time of connection with the partner device reaches the number of polarity reversals stored in the polarity reversal number storage unit. And a communication device. The partner machine is a facsimile machine,
The polarity inversion number storage means,
2. The number of polarity inversions counted by the polarity inversion number counting means between the time when a call is made to the partner device and the time when a facsimile signal is received from the partner device is stored. Communication device. When a facsimile signal is received from the partner device before the number of polarity inversions counted by the polarity inversion number counting unit reaches the number of polarity inversions stored in the polarity inversion number storage unit upon connection with the partner device, 3. The communication device according to claim 2, wherein the number of polarity inversions stored in the polarity inversion number storage means in correspondence with the partner device is cleared. When a facsimile signal is received from the partner device before the number of polarity inversions counted by the polarity inversion number counting unit reaches the number of polarity inversions stored in the polarity inversion number storage unit upon connection with the partner device, 3. The method according to claim 2, wherein the number of polarity inversions stored in the polarity inversion number storage means corresponding to the partner machine is updated with the number of polarity inversions counted by the polarity inversion number counting means at this time. A communication device as described.

Images