JPS59126359A - Facsimile communication system - Google Patents

Abstract

PURPOSE:To attain high-speed transmission by providing a bit for controlling the transmission between terminal devices in addition to a data bit and separating control information relating to transmission/reception and stop of phase synchronism and picture signal from other control information. CONSTITUTION:In a figure, P is a voice or FAX signal part, S is a part such as dial information between an exchange DX and a terminal, D1-D5 are parts transmitting control information between terminals, F0-F5 are parts for synchronizing systems. In the communication from an FAX11 to an FAX13, the exchange DX connects the FAX11 and FAX13 by the S bits from the FAX11. In this case, the priority of control is given to one terminal by the S bits. The control between the terminals is divided into the control of a level 1 performing the start and end of transmission/reception and the control of a level 2 to control the phase synchronism. A terminal having the leadership transmits a transmission instruction and a reception instruction to an opposite terminal and the opposite terminal starts transmission/reception according to it. That is, the start/end of the transmission/reception are performed by the control of the level 1 and the control is performed by the level 2. The control of the level 2 is performed in four state displays of transmitter and receiver of D2, D3.

Description

[Detailed Description of the Invention] The present invention relates to a facsimile communication system,
In particular, it relates to control in facsimile communications.

When multiple terminal devices that transmit and receive facsimile image signals are connected through an exchange device, the terminal device can control functions such as checking the functions of the other terminal device, synchronizing the phase of facsimile image signals, and starting and ending transmission and reception of facsimile image signals. It needs to be done in between. On the other hand, conventional signals between a terminal device and a switching device in such a system are composed of control bits between the terminal device and the switching device, and data bits exchanged and connected by the switching device and transmitted to the other terminal device. In particular, no bit was provided for controlling between terminal devices. Therefore, the control, notification, actual synchronization signal, and image signal of the control device as described above are transmitted and received using data bits in advance of each other in time, and, for example, the Gl+ connected to a public telephone line. The control is similar to the binary procedure of a FAX 7mm machine. Such control is often inconvenient because control information cannot be exchanged during the transmission/reception period of the phase signal and the image signal, so free control is not possible.

For example, it is not possible to accurately signal the start and end timing of one page, so extra signals may be recorded or some parts of the image may not be recorded.
If you temporarily stop the page in the middle of a page or perform re-phase synchronization, the image quality will deteriorate unnecessarily. However, phase synchronization in such systems is generally performed by counting the number of frames or bits, so if the frame synchronization is disrupted (ri), the phase synchronization will also be disrupted, and in such a case, the system must be temporarily stopped. , it is necessary to perform rephase synchronization.Furthermore, when transmitting in one direction, even though the data bits in the opposite direction are not used, control information cannot be exchanged.
There were problems such as not being able to transmit and receive at the same time.

In order to eliminate these drawbacks, the present invention provides a bit for controlling between terminal devices in addition to the data bit, and separates control information related to transmission, reception, and stop of phase synchronized 9 image signals from other control information. The present invention provides a facsimile communication system that enables high-speed transmission.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram for detailed explanation of the present invention. In FIG. 1, DX is an exchange device with the function of exchanging digital signals; FAX is a facsimile terminal device that captures and records facsimile information;
C0FX is a facsimile signal processing device consisting of a facsimile office line interface unit C0IF that performs redundancy compression/expansion and modulation/demodulation of facsimile information and a network control unit NCU. This is an additional information printing device used when recording. Telephone equipment, FAX 7mm terminal device FAX
, the facsimile office line interface section cOFX and the additional information printing device SIP are connected to the exchange device DX by an extension transmission line (with a maximum length of approximately IKm). The exchange connections in the system are executed as a pair of a connection for voice communication and a connection for facsimile communication. That is, in the embodiment of the present invention, the facsimile terminal fffF
Since AX does not have dialing and calling functions,
The connection is made by telephone, and facsimile communication is realized following the voice call connection. However, since the voice signal and facsimile signal are connected through separate routes, it is possible to carry out voice calls and facsimile communications simultaneously. The facsimile signal processing device C0FX is connected to the extension line and at the same time, it is also connected to the public telephone line Co (office line). When using the office line CO, it goes without saying that voice calls and facsimile communications cannot be made at the same time, so the switch to facsimile communication is made after establishing the voice communication path.

The telephone equipment, facsimile terminal FAX, facsimile signal processing device C0FX, and additional information printing device SIP that make up this system can be expanded according to the frequency of use, allowing for the optimal system configuration according to the user's needs. It is.

FIG. 2 is a diagram for explaining the format of signals when performing extension line transmission. (a) shows the switching device DX, telephone equipment, facsimile terminal device FAX, facsimile signal processing device C0FX, and additional information printing device SIP (
(hereinafter referred to as a terminal), P indicates the part where the encoded voice signal or facsimile signal is carried, and S indicates the transmission format between the exchange device DX and the terminal. The part that transmits dial information, monitoring information, etc., from Dl to D5''!f
So (D Bi.

G) is the part that transmits mutual control information from terminal to terminal, Fo to Fst (FBI, G) is the part that transmits the unique pattern [old and old 10] to synchronize the system. be. Each position of the S and D bits is automatically identified by detecting this unique pattern. A unit consisting of F, P, and S or D is called a frame, and the transmission time of one frame is 125 microseconds, but the S bit is transmitted once every 6 frames as shown in 0)), and the D bit is transmitted once every 6 frames. As shown in I'1(c), it is transmitted five times in six frames. The switching equipment DX and each terminal are actually connected by four lines, two of which transmit downlink information from the switching equipment DX to each terminal, and the other two transmit information from each terminal to the switching equipment DX. Transmit upstream information. That is, the transmission method is a full-duplex communication format. (d) shows one frame of audio information, where the audio signal is composed of 8 bits. (e) shows one frame of facsimile information.
It consists of 32 bits. Transmission in this digital format is not carried out in all parts of this system; in Figure 1, the voice signal connected from the switching equipment DX to the office line CO is a decoded analog signal, and if the telephone equipment is In the case of a telephone set having a similar configuration, an analog voice signal is also transmitted between the telephone set and the exchange apparatus DX, encoded within the exchange apparatus DX, and passed through a communication path switch.

FIG. 3 is a diagram for explaining in detail the inside of the exchange DX shown in FIG. 1. Each line from 1 to 8 is a voice signal, facsimile signal, and control signal (D bit)
1 to 4 and 5 or 8 constitute one set of data highways, 1 and 5 are receiving highways (RHW), 2 are and 6 are transmission highways (THW), 3
and 7 are D pit receiving highway (DRHW), 4,
! : 8 u D bit transmission highway (D T I
(W). Using FIG. 4, an example will be shown in which a signal is placed on the data highway, is exchanged, and is taken out. That is, FIG. 4 shows that the facsimile signal of the uplink facsimile information received by the facsimile interface unit FXIF is transferred to the transmission highway THW (for example, 2 in FIG. 3) using four channels from CHO to CH34 (facsimile signal is composed of 32 bits, so 4 of the audio signal
), Highway Switch H
Facsimile interface part FX of the other party at 8W
It is transferred to the reception highway RT (W (for example, 5 in Figure 3) connected to the IF, and is transferred to the reception highway RI (W) (for example, 5 in Fig. 3).
The 7-acn millimeter signal is extracted from W, and the audio signal is placed on CH22 of the sending highway THW (for example, placed on 2 from TIF in Figure 3), and then passed through the highway switch H8W from CH22 of the receiving highway R) IW. It shows how it is pulled out (for example, from FIG. 3 to the central office line interface section COT). In FIG. 4, the explanation is made ignoring the actual flow of time, and the channel numbers of the sending highway THW and the receiving highway RHW do not have to correspond to the same.

8- However, the transmitting highway THW and the receiving highway RJ(W (for example, 2 and 1 in Figure 3) in one set transmit and receive signals at the same time, so the channel numbers are exactly the same. The D bit used for direct control is transmitted using the highway DTHW for sending the D bit and the highway DRI (W) for receiving the D bit, as shown in Figure 4 (6(m)). In addition, the highway for the D pit also consists of 24 channels, each channel corresponds to one D bit, and is exchanged along with the transmission highway THW.Especially, in the case of facsimile signals, 4 channels are used.
The contents of the two channels are the same and are exchanged. In addition,
Although only two sets of data highways are shown in FIG. 3, in reality, more data highways are prepared, and the highway switch H8W is connected to the central processing unit MPU.
(11 is a control bus for giving instructions), the signal from the transmission highway THW or the D bit transmission highway DTHW is transferred to the reception highway R of the communication partner.
We are currently working on moving it to HW or D-pit receiving highway DRHW. 9 is a central processing unit MPU which includes a facsimile interface unit FXIF, a telephone interface unit TIF, and a central office line interface unit COT.
This is a control bus for receiving uplink control information from an interface unit such as the interface unit or for outputting downlink control information to the interface unit. Reference numeral 10 denotes a selection signal bus through which the central processing unit MPU instructs the interface unit as to the timing at which the audio signal or facsimile signal should be transferred. Facsimile interface section FX
The IF receives facsimile information from the extension uplink transmission line and decomposes it into S bit, D pit, and P bit as shown in Figure 2.
Highway DTI for bit transmission (selection signal bus 10 to W)
The S bits are decoded and organized and temporarily stored so that they can be loaded on the control bus 9 when requested by the central processing unit MPU. P pulled out
Bits and D bits are combined into a format as shown in FIG. 2, and among control signals from the central processing unit MPU, those that need to be commanded to the terminal are transmitted using S bits.

The telephone interface unit TIF operates in the same manner as the facsimile interface unit FXIF, relaying the transmission and reception of voice information, and requests the central processing unit MPU to connect with the other party in accordance with the dial from the telephone device. If the telephone device is a general telephone as shown in FIG. 3, the analog voice signal is encoded and decoded within the telephone interface section TIF to provide an interface with the data highway.

COT is an office line interface unit for voice signals, and performs input/output of control signals for call termination (incoming call detection 9 origination operation) and encoding/decoding of analog voice signals. The MPU is a central processing unit that primarily controls the inside of the exchange device DX, and manages and controls the operations of each interface unit. SET
In order for the operator to tell the central processing unit MPU the status of the device,
This is the part where you enter information. In other words, which channel of which data highway is supported by the facsimile terminal,
There is also a semi-fixed setting section to let you know which phone it is paired with.

FIG. 5 shows the structure of the S bit used for control between a terminal such as a facsimile terminal that transmits and receives facsimile image signals and the switching device DX. The synchronization information consists of 16 bits, "11111
11111111110'', the control information is composed of 16 bits from SO to 515t, and it is divided into upstream control information and downstream control information! foil 1
It is defined as In uplink control information, SO
indicates that the terminal is operational, SL indicates that the terminal requests connection, S2 indicates that the terminal requests disconnection, and S3 indicates that automatic reception is possible. In addition, S4 to 815 are undefined and fixed at 0, and the synchronization information is unique.

In the downlink control information, SO indicates that the terminal is connected to the other party, Sl indicates that connection is not possible to the other party that has requested a connection, and S2 indicates that priority is given in facsimile communication control. S3 to 815 are undefined and fixed to 0#. The check information is composed of 8 pits, and the result of adding control information in units of 8 bits is expressed as a two's complement number. The receiving side uses this check information to check whether the control information is correct or not, and if it is incorrect, it discards the received information and waits for the next information. The details within the switching device DX have been described above, and an example of their operation will be described next. Central processing unit MPU
When receiving the connection request and the other party's number from the telephone interface unit TIF, it checks whether the other party's telephone interface unit TIF can accept the connection and, if possible, instructs the highway switch H8W the data highway and channel number to be exchanged. Set up a voice communication path. After that, when a connection request is generated from the facsimile office line interface unit FXIF, the facsimile office line interface unit FXIF is connected to the facsimile station paired with the telephone interface unit TIF of the paired telephone interface unit TIF. Check whether the line interface unit FXIF can be connected, and if possible, connect these two facsimile office line interface units FXIFf: Same as in the case of g-voice...by instructing the eway switch H8W to specify the data no eway and the channel number. (In this case, 4 channels are
connect as a pair). For disconnection, the request from the 7th office line interface section T'XTF and the request from the telephone interface section TIF are independently responded to.

Figure 6 shows control signals between terminals, D-bi, 1, and
Of these, the configuration of D1 bits and g is shown. The synchronization information and check information are the same as in the case of the S bit described above. The control information consists of 64 bits from DIO to D163.

The 3 bits from DIO to D12 represent the priority level at the start of the procedure in 8 levels from 1'0'' to 7''.The priority level of the facsimile terminal and additional printing device is O'', which is the priority level of the facsimile signal processing unit COF'X. level par 1”
It is. D13 indicates that transmission and reception can be performed simultaneously. D14 indicates the end of one page from the sending side to the receiving side,
D15 notifies the transmitting side that the receiving side has recognized the end of one page in T)14. D16 is a transmission command that instructs the transmitting side to transmit, and D17 is a receiving command that instructs the receiving side to receive. DlB,
D19 indicates a transmitting/receiving function, DlB indicates a transmitting function, and D19 indicates a receiving function. Other necessary information is assigned after D110. The appropriate bits to make the synchronization information a unique pattern are ′
It is fixed at 0''.

Hereinafter, taking as an example the case of communication from FAX II to FAX 13 in FIG. 1, control between the terminals will be explained. The FAX II operator enters the number 14 on the other party's FAX 13, dials 12, presses the start button on the FAX II, and the FAX II starts.
A connection request is sent to the exchange DX using the S bit, and the exchange DX connects FAX II and FAX 13. At this time, the exchange DX notifies both FAX II and 13 that it is connected by the S bit, and also sends S to only one terminal.
Bits give priority in control.

When the terminal learns from the S bit that it is connected to the other terminal, it starts controlling the other terminal. This control is divided into level 1 control for starting or ending transmission or reception, and level 2 control for controlling transmission, reception, and stop of the phase synchronized 9 images.

Level 1 control will be explained below. When it is known that the connection has been made as described above, the priority levels are compared, and the one with the higher priority level has the initiative, and if the priority levels are the same, priority is given from the exchange device DX. The one who is in charge has the initiative.

The terminal that has the initiative checks the functions of the other terminal, sends a transmission command and a reception command, and transmission and reception begins. A terminal that does not have the initiative will receive a transmission command from the other terminal.

Start transmitting and receiving according to the receive command. When one page ends, the sending side notifies the receiving side that the first page is finished, and when the receiving side learns from the sending side that the first page is finished, it sends a message to the sending side.
The first page ends with notification that the end of the page has been confirmed. If there are a plurality of pages, the terminal with the initiative again checks the functions of the other terminal and sends out a transmission command or a reception command (16-), after which the above operations are repeated.

As described above, the start and end of transmission and reception are performed by level 1 control, and level 2 control is performed from the start to the end of transmission and reception. Level 2 control is D2. Sending D3,
Each of the receivers is provided with four status indications.

Figure 7 shows the D bit used to indicate the status of the transmitter/receiver among the D bits that are control signals between terminals.
2. This is a useless explanation of the structure of D3. D2 is used as a synchronization signal and is a series of 0011'', and when D2 is '00#', the information of D3 is ''R
DO, RDI" represents the receiver status, and D2 is '"
The information "TDO, TDI" of D3 at the time of "11" represents the state of the transmitter.

'RDO, RDI' are determined as follows.

IQ and Qll are "stop" indicating that the receiver is stopped, '0,1' indicates that the transmitter is requested to send a phase signal with '6 phase request', and '1,0' indicates that the transmitter is requested to send a phase signal. 6 Image request” indicates that the transmitter is requesting to send an image signal.
1 and 1" are "stop requests" and indicate that the transmitter is requested to stop. "TDO, TDI"
” is determined as follows.

``o, o'' indicates that the transmitter is stopped at °゛stop JBI, and ``0.1'' indicates that the transmitter is sending out the phase with ``phase sending''. °゛Image transmission''' indicates that the transmitter is transmitting an image, Ilt, 1''
is a "stop request" and indicates that the receiver is requested to stop +l2.

For RDO and RDI, D is "'0" as in section a in Figure 7.
0110011" and "h", the information in D3 of section C is set as RDO and RDI, and only if this information is the same twice or more, it is adopted, and the other information is discarded.T
Similarly, DO and TDI are D2'' 1 like the section b.
1001100'', the information of D3 in the interval d is taken as TDO and TDI, and is adopted only when this information is the same twice or more.By this, D2,
The influence of single errors and burst errors in D3 is reduced.

Also, when transmitting as described above, D2 is used as 8 pins to notify the status of the transmitter or receiver.

Although it takes time to transmit data using Dl, the data can be transmitted much faster than transmission using Dl. In these status indications, the transmitter operates according to the status indication from the receiver, stopping if the receiver is ``stopped'' and responding to ``phase request''.
In the case of ``Image request'', the image is sent out, and in the case of ``Stop request'', it is stopped. The receiver stops in response to a stop request from the transmitter, but
In other states, the receiver operates in the state required.

The transmission and reception operations will be explained below. When transmission and reception start, both the transmitter and receiver are at a 6'' stop, and the receiver sends out a ``phase request'' for phase synchronization.

The transmitter transmits the phase in response to this "phase request" and also indicates "phase transmission" D2.

Notify with D3. The receiver waits for the transmitter to transmit the phase signal and performs phase synchronization, and when the synchronization is completed,
Request an image''' and wait for the transmitter to say 'send image'. At this time, the transmitter sends an image in response to the 'request for image' and when it says 'send image', the receiver starts receiving the image. Start. When the transmitter finishes one page (19-), it stops transmitting images and stops, sends out a stop request, and this stop request also causes the receiver to stop.

In this stopped state, a procedure for ending one page is performed under level 1 procedural control, and one page is completed.

If you want to temporarily stop both the transmitter and receiver during this one page, you can stop them by clicking the stop request button. For example, if the transmitter wants to stop, it sends out a 'stop request', the receiver stops and also sends a 'stop' message, and the transmitter stops when it receives the 'stop' request.

If you want to restart, the transmitter will “stop” from the stop request pa.
In this case, the receiver switches from "Stop" to "Request facsimile image" and thereafter operates in the same manner as above and resumes transmission and reception. If the signals are deemed to be out of synchronization, phase synchronization can be performed again after stopping as described above.

In the above explanation, control signals are provided independently for transmission and reception, and factor -20 = millimeter image signals can also be sent independently in both directions, so
If both terminals have sending and receiving functions, they can send and receive at the same time.

As described above, according to the present invention, control information can be sent simultaneously and independently of image information, so that transmission and reception can be performed simultaneously. Furthermore, the control information is transmitted separately from other control information, such as phase synchronization 9 image information transmission/reception, stop, etc., and is transmitted with a sufficiently small delay compared to the image information, so the image may not be interrupted or unnecessary. This has the advantage that problems such as images being recorded are eliminated and rapid control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining the overall outline of the system of the present invention, FIG. 2 is a time chart for explaining the signal format between a terminal and a switching device, and FIG. 3 is a diagram of a switching device used in the present invention. A block diagram showing one example, FIG. 4 is a time chart for explaining how signals are exchanged by the switching device used in the present invention, and FIG. 5 is primarily used for control between the terminal and the switching device in the present invention. FIG. 6 is a diagram explaining the signal format of the D1 bit, which is used for control between terminals in the present invention, and FIG. 7 is a diagram explaining the signal format of the S bit. FIG. 2 is a diagram illustrating the signal format of D2 and D3 bits used for control between terminals in FIG. C0FX...FAC 7mm signal processing device, CO■F・
・・Factory office line interface section, NCU・・
・Network control unit, STP...additional information printing device, installation...
Telephone, FAX...Facsimile terminal device, Dx...
・Switching equipment, CO...office 1i, FXIF...off 7mm interface section, TIF...telephone interface section, COT...office line interface section,
MPU...Central processing unit, SET...Information input unit, H8W...Highway switch. h, l, 5...reception highway (RT(W), 2.
6...Transmission highway (TI-IW), 3,7...
・Highway for D bit reception (DRI (W), 4, 8
...D-bi. Highway for delivery (DTHW), 9...jl+ll
If'11 bus, 10... selection signal bus. Patent applicant: Iwasaki Tsushinki Co., Ltd. Representative: Inuzuka, 1 external person

Claims (2)

[Claims] (1) In a system consisting of a plurality of terminal devices that transmit and receive facsimile image signals and a switching device that performs exchange connections between these terminal devices, the signals of the terminals and the switching device are transmitted from the 0th frame to the 5th frame. Consists of 6 frames, the bits in each frame are data bits and control bits, and the control bit of the 0th frame is S bit,
The control bit of the first frame is the D1 bit, the control bit of the second frame is the D2 bit, the control bit of the third frame is the D3 bit, the control bit of the fourth frame is the D4 bit, and the control bit of the fifth frame is D5. As bits, the data bits are used for transmitting and receiving facsimile image signals; A facsimile communication system characterized in that pits 1 to D5 are used for control between the terminal equipment and the exchange equipment, and pits 1 to D5 are used for control between the terminal equipment. (2) The D1 bit controls the start and end of transmission and reception, and the D2. The D3 bit displays the four states of stop, stop request 1 phase sending, 9 image sending from the transmitting side to the receiving side, and also displays the four states of stopping from the receiving side to the transmitting side, stop request 9 phase request 9 image request. Transmission and reception of phase-synchronized 9 image signals from the start to the end of transmission and reception. The facsimile communication system according to claim 1, characterized in that control such as stopping is performed.