ISDN facsimile apparatus operable as a common terminal adapter for plural non-ISDN facsimile apparatuses

Abstract: A facsimile apparatus is connected to an ISDN and is capable of transmission/reception. When a facsimile signal received from the ISDN is one sent to a non-ISDN facsimile apparatus, the facsimile signal received from the ISDN is converted into a non-ISDN facsimile signal and this signal is capable of being transmitted to the non-ISDN facsimile apparatus. Further, the facsimile apparatus is capable of being connected to a plurality of facsimile apparatus via an exchange, and a signal can be transmitted to a facsimile apparatus among the plurality thereof that is designated by a subaddress received from the ISDN. The facsimile apparatus is such that at the time of communication with a non-ISDN facsimile apparatus, communication is performed using the D channel of the ISDN, thereby raising the efficiency of ISDN utilization.

Description: This invention relates to a facsimile apparatus connected to an ISDN (an integrated services digital network). An ISDN makes feasible a communication network employing digital transmission in place of a telephone. oriented communication network based on analog transmission, and it provides multifarious communication services such as telephone and facsimile communication and data communication services. The ISDN interface specifications are stipulated by an I-series advisory of the CCITT. Services provided by a low-level function of an ISDN include services referred to as a "bearer services" defined by CCITT advisory I.211. Among these, a 3.1 kHz audio service is used in data signal transmission of the 3.1 kHz band such as that of a G3 facsimile. A 64 kHz unlimited digital service is used in digital signal transmission such as that of a G4 facsimile. Fig. 6 is a block diagram illustrating the manner in which a conventional G3 facsimile apparatus 601 is connected to a network terminating device NT 603 via a terminal adaptor 602. Here the G3 facsimile apparatus 601 is connected to the terminal adaptor 602 via a line connection terminal, the terminal adaptor 602 is connected to the network terminating set NT 603 at a reference point T, and the network terminating set NT 603 is connected to an ISDN 604. The terminal adaptor 602 detects a current loop between itself and the G3 facsimile apparatus 601, identifies an inputted dial signal, subjects a signal received from the facsimile apparatus 601 to an A/D conversion and outputs the converted signal to the ISDN 604 via a B channel. On the other hand, when data is received from the ISDN 604 via the B data channel, the terminal adaptor 602 converts this digital data into an analog signal and forms a current loop between itself and the G3 facsimile apparatus 601, and the received facsimile signal is reproduced by the G3 facsimile apparatus 601. Thus, in the prior art, such a terminal adaptor is necessary in order to connect a G3 facsimile apparatus, which is a subscriber's apparatus for non-ISDN use, as a subscriber's apparatus for ISDN. Another problem is that with a basic access interface, a maximum of only eight subscriber's apparatus (e.g., facsimile apparatus) can be connected to one set of wiring. Patent Abstracts of Japan JP-A-63283351 discloses an integrated series digital network terminal adaptor arranged to execute mutual communication without remodelling a G3 facsimile by converting a procedure signal and a picture signal from the G3 facsimile to digital signals, transmitting them through an integrated series digital network (ISDN), and converting a procedure signal and a picture signal received from the ISDN, by the G3 facsimile, to analog signals. The present invention has been devised in view of the prior art described above and its object is to provide an ISDN facsimile apparatus which can serve as a common terminal adaptor to plural connectable non-ISDN facsimile apparatuses. According to the present invention there is provided a facsimile apparatus for connection to a digital network of an integrated services digital network (ISDN) and an analog network other than an ISDN, comprising: detecting means for detecting arrival information from said digital network; receiving means for receiving a digital facsimile signal associated with said arrival information from said digital network; and transmission means for converting the digital facsimile signal into an analog facsimile signal and transmitting the analog facsimile signal to said analog network; characterised by output means for outputting the information contained in the received digital facsimile signal on a recording medium, and control means for determining whether or not said arrival information includes address information designating a destination terminal and for determining whether or not said address information designates an analog terminal connected to said analog network, said control means being adapted to cause said transmission means to transmit an analog facsimile signal corresponding to said digital facsimile signal received from said digital network to the analog terminal designated by said address information when said arrival information includes the address information designating an analog terminal, and to cause said output means to output said digital facsimile signal received from the digital network when said arrival information does not include said address information, or when said address information does not designate an analog terminal. In the accompanying drawings:- Fig. 1 is a block diagram illustrating the general construction of a facsimile apparatus according to a preferred embodiment of the present invention; Fig. 2 is a diagram showing an example of a line network of the preferred embodiment; Fig. 3 is a flowchart illustrating reception processing according to the preferred embodiment; Fig. 4 is a block diagram illustrating the general construction of another facsimile apparatus for reference purposes; Fig. 5 is a flowchart illustrating transmission processing according to the another facsimile apparatus; and Fig. 6 is a diagram showing the connection between a G3 facsimile apparatus and an ISDN according to the prior art. The preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. As shown in Fig. 1, a facsimile apparatus capable of transmission/reception in accordance with either G3 or G4 specifications includes a CPU 12 for controlling the facsimile apparatus 11 and having a ROM 13 which stores a program, illustrated by the flowchart of Fig. 3, for controlling the CPU 12, as well as various data, and a RAM 14 used as the working area of the CPU 12. Also included in the facsimile apparatus are an image scanner 15 for photoelectrically reading a document image and outputting the same as a digital signal, an input unit 16 manipulated by the operator for entering the telephone number of a transmission destination, the address of a facsimile apparatus at the destination, etc, and a printing unit 17 for performing printing on a recording paper, which serves as a printing medium, based on a received image or an image signal read by the image scanning unit 15. The facsimile apparatus 11 further includes a call controller 18, which is connected to an external bus 24, for being connected with an ISDN to perform communication, an NCU (network control unit) 23 connected with a private branch exchange PBX by an analog line 25 to control outgoing and incoming calls, a modulator/demodulator (modem) 22 used at the time of a G3 transmission procedure, a G3 communication unit 21 for decoding an image signal, which is received via the NCU 23 and modem 22, and storing the decoded signal in a memory 19, and also for subjecting image data stored in the memory 19 to an MH conversion and transmitting the data to a G3 facsimile apparatus, which is connected to the private branch exchange PBX, in accordance with a G3 control procedure, and a G4 communication unit 20 for executing a control procedure for communication with a G4 facsimile apparatus connected to the ISDN, decoding image data received from the ISDN and storing the image data in the memory 19, and also for coding image data stored in the memory 19 into a G4 facsimile signal and transmitting the signal to the ISDN via the call controller 18. The memory 19 accumulates image data received from another party's facsimile apparatus or digital image signals inputted from the image scanner 15. Fig. 2 is a diagram showing the connection of the facsimile apparatus 11 interposed between the ISDN and the private branch exchange PBX. As shown in Fig. 2, a G4 facsimile machine 101 is connected to an ISDN 102 and performs transmission/reception with the facsimile apparatus 11 of the embodiment through the ISDN 102. Numeral 103 denotes a building in which a G4 facsimile signal received by the facsimile apparatus 11 is converted into a G3 facsimile signal and outputted to the analog line 25 by the facsimile apparatus 11. Numeral 105 denotes a private branch exchange, and numerals 106 - 108 designate G3 facsimile apparatus connected to the private branch exchange PBX 105. A maximum of n facsimile apparatus are connected. The value of n is unrelated to the maximum number (= 8) of terminal devices connectable to the ISDN; it may be any number so long as this number of apparatus are connectable to the PBX 105. It will be assumed that these G3 facsimile apparatus are those specified for reception by subaddresses in a layer 3 protocol. Figs. 3A and 3B are flowcharts showing processing for receiving image data from the ISDN 102 and transferring the image data to the PBX 105 from the facsimile apparatus of the present embodiment. First, at step S1, when the call controller 18 informs of the fact that a call has been received from the ISDN 102, the program proceeds to step S2, where it is determined whether or not there is a subaddress in the incoming information. If there is a call subaddress, the program proceeds to step S3, at which it is determined whether the subaddress is the address of a G3 facsimile apparatus connected to the private branch exchange PBX 105. When the subaddress is the address of a G3 facsimile apparatus, the program proceeds to step S4, at which the received image data are successively decoded and stored in the memory 19 by the G4 communication unit 20. When the reception operation is found to end at step S5 and the image data have been stored in the memory 19, the program proceeds to step S6. At step S6 an outgoing call is placed to the G3 facsimile apparatus designated by the subaddress, which is the destination of the data transfer, and it is determined at step S7 whether there is a response from the other party's G3 facsimile apparatus. If there is a response, transmission is started at step S8 by a G3 communication procedure. The program then proceeds to step S9, at which the image data are read out of the memory 19, MH-coded for G3 by the G3 communication unit 21 and then transmitted to any of the G3 facsimile apparatus 106 - 108, designated by the subaddress, in accordance with the G3 communication control procedure. When transmission is thus completed at step S10, the program proceeds to step S11. Here a G3 transmission ending procedure is executed, after which the system makes a transition to a standby state. If no subaddress is found at step S2, or if none of the G3 facsimile apparatus are designated at step S3, the program proceeds to step S12. Here an image signal is received and decoded by the G4 communication unit 20 as a G4 facsimile signal, and the image is recorded on the recording paper by the printing unit 17. When reception processing is thus ended at step S13, the system again makes a transition to the standby state. Thus, in accordance with the preferred embodiment as described above, a plurality of G3 facsimile apparatus can be connected to an ISDN. In addition, if, in a case where a call is placed from an ISDN to a G3 facsimile apparatus connected to the ISDN, an address which is the destination of an image data transfer is designated by a subaddress, the image data can be transferred, by a G3 procedure, to the facsimile apparatus which is the destination of the transfer. Fig. 4 is a block diagram showing the general construction of a facsimile apparatus 41 for reference purposes. In the prior art, facsimile signals are transmitted and received over a B channel of an ISDN at all times. With the facsimile apparatus 41, however, a G3 facsimile signal can be transmitted using the D channel of an ISDN in a case of transmission/reception of a G3 facsimile signal whose communication rate is low. In Fig. 4, numeral 61 denotes a G3 facsimile apparatus connected to the facsimile apparatus 41, and numerals 62, 63 designate G4 facsimile apparatuses. The facsimile apparatus 41 includes a CPU 42 for controlling the overall apparatus in accordance with a control program, which is stored in a ROM 43 and illustrated by the flowchart of Fig. 5), as well as various data. Numeral 44 denotes a RAM used as the working area of the CPU 42. A G3 communication controller 45, which is for effecting a connection with the G3 facsimile apparatus 61, possesses a function equivalent to the functions of the G3 communication unit 21, modem 22 and NCU 23 of Fig. 1, described above. G4 communication controllers 46, 47 each possess a function identical with that of the G4 communication controller 20 of Fig. 1, described above. These communication controllers 46, 47 are connected to corresponding ones of the G4 facsimile apparatus 62, 63 and control transmission/reception in accordance with G4 specifications. Numeral 48 denotes a G3 protocol converter, and 49 a G4 protocol converter. In a case where a transmission is made to the ISDN 102 from the G3 facsimile apparatus 61, the facsimile signal from the G3 facsimile apparatus 61 enters the G3 communication controller 45, the signal is converted into a signal corresponding to the D channel of the ISDN by the G3 protocol converter 48, and the converted signal is transmitted to the ISDN 102 through a line controller 50. In a case where a transmission is made to the ISDN 102 from each of the G4 facsimile apparatus 62, 63, the G4 communication controllers 46, 47 receive the facsimile signals from the respective G4 facsimile apparatus 62, 63 and output the signals to the G4 protocol converter 49. The latter subjects these signals to a protocol conversion and outputs the result to the ISDN 102 through the line controller 50. Fig. 5 is a flowchart illustrating the operation of the facsimile apparatus 41. The control program for executing this processing is stored in the ROM 43. It is determined at step S21 whether a "call request" has been received from the G3 facsimile apparatus 61 or the G4 facsimile apparatus 62, 63 connected to the apparatus 41. If a call request has been received, then the program proceeds to step S22, at which it is determined whether there is a call request from the G3 facsimile apparatus 61. When there is a call request from the G3 facsimile apparatus 61, the program proceeds to step S23, at which a flag 44a in the RAM 44 is turned on. Next, at step S24, the line controller 50 is actuated and a call command is sent to the ISDN 102. The system waits for entry of a "response" command from the ISDN 102 at step S25. When the response command is received, the program proceeds to a step S26. It is determined at step S26 whether the flag 44a of RAM 44 is on, namely whether there is a transmission request from the G3 facsimile apparatus 61. When there is a transmission request from the G3 facsimile apparatus 61, the program proceeds to a step S27, at which the G3 protocol converter 48 and line controller 50 are so instructed as to carry out transmission upon selecting the D channel of the ISDN 102. On the other hand, when there is a transmission request from the G4 facsimile apparatus 62 or 63, the program proceeds to step S29, at which the G4 protocol converter 49 and line controller 50 are so instructed as to carry out transmission upon selecting the B channel of the ISDN 102. Thus, the program proceeds to step S28, at which data are transmitted to the ISDN 102. Processing is then terminated. Thus, as described above, the D channel of the ISDN 102 is selected and the transmission is made when communication is carried out by a G3 facsimile apparatus connected to the facsimile apparatus. When a transmission request is received from a G4 facsimile apparatus, on the other hand, communication is performed by the B channel of the ISDN, whereby each channel of the ISDN can be utilized effectively.

Claims: A facsimile apparatus for connection to a digital network of an integrated services digital network (ISDN) (102) and an analog network (25) other than an ISDN, the apparatus comprising: detecting means (18) for detecting arrival information from said digital network (102); receiving means (18, 20) for receiving a digital facsimile signal associated with said arrival information from said digital network (102); and transmission means (21, 22, 23) for converting the digital facsimile signal into an analog facsimile signal and transmitting the analog facsimile signal to said analog network (25); characterised by output means (17) for outputting the information contained in the received digital facsimile signal on a recording medium, and control means (12, 13) for determining whether or not said arrival information includes address information designating a destination terminal and for determining whether or not said address information designates an analog terminal connected to said analog network, said control means being adapted to cause said transmission means to transmit an analog facsimile signal corresponding to said digital facsimile signal received from said digital network to the analog terminal (106-108) designated by said address information when said arrival information includes the address information designating an analog terminal, and to cause said output means to output said digital facsimile signal received from the digital network (102) when said arrival information does not include said address information, or when said address information does not designate an analog terminal. A facsimile apparatus as claimed in claim 1, characterised in that said receiving means (20) is adapted to receive the digital facsimile signal in accordance with a predetermined communication protocol and decodes the digital facsimile signal, and in that memory means (19) are provided for storing the signal decoded by said receiving means. A facsimile apparatus as claimed in claim 2, characterised in that said transmission means (21, 22, 23) encodes the signal stored in said memory means (19) and converts the encoded signal into an analog facsimile signal. A facsimile apparatus as claimed in claim 2 or 3, characterised in that said receiving means (20) is adapted to receive the digital facsimile signal in accordance with a group 4 facsimile protocol. A facsimile apparatus as claimed in claim 2, 3 or 4, characterised in that said transmission means (21, 22, 23) transmits the analog facsimile signal to the analog network in accordance with a group 3 facsimile protocol.

Inventors: KOTANI TAKASHI, KOTANI, TAKASHI
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1990
Main classification: H04N1
IPC codes: H04N1, H04Q11