Manifold analog/digital facsimile apparatus

description

The present invention relates to a multi-purpose facsimile apparatus capable of selectively communicating with a group 3 facsimile machine as well as a group 4 facsimile machine. Group 3 and Group 4 are standards established by the CCITT according to which facsimile machines should work or operate on the public telephone network for telecopying purposes. A Group 3 device is an analog device while a Group 4 device is a digital device. The exact standards for the latter type of device will be specified by the CCITT in the near future.

Facsimile machines for optical communication have been significantly improved in function and nowadays allow to transfer a standard A4 size document in less than a minute. The CCITT has recommended basic functions for facsimile receivers and standardized the regulations, data link controls and other related details. There are recommendations T.2, T.3, T.4 and T.30 today for group 1 to group 3 receivers, all of which are analogue devices using analog transmission networks, such as the public telephone network.

CCITT is currently preparing a recommendation prescribing specification, data link control, and other standard functions for Group 4 facsimile machines, which are an improved version of Group 3 devices. It is expected that a Group 4 facsimile machine will have a high resolution and use a system that has a higher compression efficiency than the other systems. Such a device therefore allows an optical

Transfer higher quality than a Group 3 device. Basically, a Group 4 device is a digital facsimile machine that uses a digital transmission network and for this reason has a data link control function capable of sufficiently utilizing the improved transmission function of a digital network. Digital switched networks, packet networks and other digital transmission networks have been established lately and are likely to be open to the public in the near future. Such a trend is accelerating the development of a digital facsimile receiver using a digital transmission network.

From the situation described arises the need for a mutual connection between a traditional Group 3 analog facsimile machine and a Group 4 digital facsimile machine, which will be prevalent in the future. However, since an analog facsimile machine and a digital facsimile machine can not communicate with each other because of the different networks they use, digital devices can not be connected to a facsimile transmission path set up for the existing analog devices.

A. It is therefore an object of the present invention to provide a multi-purpose facsimile apparatus capable of communicating with both an analog group 3 device and a group 4 digital device as desired. In particular, the apparatus should be able to be connected to both a public telephone network or the like analog transmission network, as well as to a digital switched network, a packet network or the like digital transmission network. In addition, it should also be possible, in particular, for the device to be compatible with both a Group 3 analogue device and a Group 4 digital device

via a public telephone network.

This object is achieved by the invention defined in claim 1. Advantageous embodiments of the invention, which in particular also solve the further tasks, are the subject of further claims.

The invention, its refinements and advantages will become ^w explained in more detail with reference to the drawings. It shows:

Fig. 1 is a block diagram of a first embodiment of the invention;

Fig. 2 is a flowchart of the operation of a transmission control unit of Fig. 1;

Fig. 3 is a flow chart of the signal processing on the receiving side;

Fig. 4 is a block diagram of a second embodiment of the invention;

Fig. 5 is a timing chart illustrating a period of time associated with the data link controller for transmission with a Group 4 facsimile machine, and

Fig. 6 is a timing chart showing a data connection control for transmission with a group 3 facsimile apparatus.

In Fig. 1, a general purpose facsimile apparatus 10 according to the present invention is shown. The device 10 includes a

System controller (SCU) 12, which serves to control the entire device. It consists of a microcomputer and a plurality of associated peripheral circuits. An operation / display panel 14 is composed of a plurality of keys that the operator can operate without operating the apparatus 10 and a display panel for displaying messages to be displayed by the apparatus 10. A scanner 16 reads an image to be transmitted at a predetermined resolution while a plotter 18 serves to produce a paper copy carrying a received image.

A transmission control unit (CCU) 20 is capable of selectively performing the data connection control using a digital network or the data connection control using an analog network such as a public telephone network. The CCU 20 consists of a microcomputer and associated peripheral circuits. A digital interface 22 fulfills the task physically to connect the CCU 20 with a digital network, such as a DDX-P network or the like. Packet network or a digitally switched network. Connected to a switch port of a switch 24, the digital interface 22 informs the CCU 20 of the receipt of a call from the digital network. A network control unit (NCU) 26 is provided to physically connect the CCU 20 to a telephone network. Connected to the other switching input of the switch 24 via a modem 28, the NCU 26 interacts directly with the CCU 20 when a call is placed or received. Usually, a telephone set 30 is connected to the NCU 26. The switch 24 is controlled by the CCU 20.

2, the workflow in the CCU 20 is shown.

The CCU 20 usually repeats a control loop consisting of receive processing and send processing. More specifically, when a call intended for the device 10 is input to the digital network or the telephone network, it enters the reception processing, and enters the transmission processing when the SCU 12 generates a transmission command.

Fig. 3 shows an example of the reception processing. First, the CCU 20 determines whether a call has been received from the digital network (step 1). If the result is YES, meaning that a call has been received, the CCU 20 operates the selector switch 24 to select the digital interface 22 (step. 2) and at the same time provides an inhibit signal to the NCU 26 to reject a call that could possibly be received over the telephone network (step 3). After establishing the connection between the device 10 and the digital network, the CCU 20 starts the data link control for the digital network (step 4). The data link controller for the digital network is the same as a group 3 link except the link level and the transport level.

However, if in step 1 the result is NO, then the CCU 20 determines whether a call has been received over the telephone network (step 5). If the result is NO, then the CCU 20 immediately returns to the determination that a call destined for the device 10 has not been entered in one of the two networks. If the result of step 5 is a YES, meaning that a call has been entered into the telephone network, then the CCU 20 causes the selector switch 24 to select the modem 28 and the NCU 26 and simultaneously issue a disabling signal to the digital interface 22 to reject calls over the digital network

(Step 7). Upon completion of the connection of the device to the (analog) telephone network, the CCU 20 enters the telephone network data connection control, ie, group 3 processing (step 8).

As described above, in this particular embodiment, digital network data transmission is prioritized over analog or telephone network data transmission so that data transmission over the digital or analog network is free from conflicting situations.

On the other hand, received data is transmitted from the CCU 20 to the SCU 12. The SCU 12 performs a sequence of operations such as decoding the received data to retrieve the original video signals from them. The plotter 18 to which the video signals are supplied prints out a received image in accordance with the video signals.

When the operator for transmission sends an address of a desired remote party to the operation / display part 14, the SCU 12 transmits it to the CCU 20. The CCU 20 controls the select switch 24 according to the inputted address, then retrieves the address and transmits then the data to be transmitted to this from the SCU 12. Here, the data to be transmitted is conditioned by the SCU 12 by encoding or other processing to video signals read by the scanner 16.

Thus, according to the illustrated embodiment, there is provided a facsimile apparatus capable of selectively communicating with an analog facsimile apparatus and a digital facsimile apparatus. This advantage results from the presence of an analog and a digital

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talen interface, which are set up for connection to an analog or digital network and are optionally connected to a transmission control unit. If the multifunction device is given certain calls simultaneously to both the analog and the digital network, then the digital network is given priority over the analog network.

4, a second embodiment of the present invention is shown. In this embodiment, the facsimile apparatus 40 is provided with the capability of selectively communicating with a Group 3 analog facsimile machine and a Group 4 digital facsimile machine over a telephone network. As shown, a system controller (SCU) 42 serves to control the entire facsimile machine 40 and includes a microcomputer and peripheral circuitry associated therewith. An operation / display part 44 is composed of a plurality of buttons that the operator can operate to operate the device 40, and a display device for displaying messages that the device 40 can display to the operator. A scanner 46 is provided for scanning an image to be transmitted at a predetermined resolution while a plotter 48 is for producing a paper copy carrying a received image.

A transmission control unit (CCU) 50 is capable of performing data connection control for both a group 4 facsimile machine and a group 3 facsimile machine. The CCU 50 also includes a microcomputer and associated peripheral circuitry. A modem 52 modulates, according to a predetermined modulation system, the transmission signals (which are encoded as described below) and demodulates received signals into them

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original signals. The modem 52 is connected to a telephone network via a network control unit (NCU) 54. The NCU 54 serves to connect the device 40 to the telephone network. An encoder / decoder (codec) 56 compresses video signals supplied by the sampler 46 to encode them, and expands received signals to decode them into the original signals. The codec 56 is capable of selectively performing coding for a group 3 facsimile machine and for a group 4 facsimile machine.

For the transmission of image data, the address data input via the operation / display part 44 is transmitted from the SCU 42 to the CCU 50 and from there to the NCU 54 to be abandoned to the telephone network and thereby to call the desired party. After the connection is made in this manner, the CCU 50 sends an image data read command to the system controller (SCU) 42. As a result, the SCU 42 operates the scanner 46 to generate image signals associated with the image data. The image signals are passed from the SCU 42 to the codec 56, which then compresses the input video signals. The coded signals are supplied to the CCU 50. The CCU 50 supplies the incoming signals to the modem 52 so that the signals are modulated and then sent out via the NCU 54 to the desired remote party.

When the device 40 is called by a remote party, the CCU 50 receives signals in accordance with a predetermined data link control flow and transmits the received signals to the SCU 42. This feeds the incoming signals to the codec 56, which then decodes them into the original image signals. These image signals are supplied to the plotter 48, which prints them as an image.

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If the multi-purpose facsimile machine 40 is used to transmit image data, then it must be decided at the beginning of the transmission whether the group 3 data transfer control or the group 4 data transfer control is to be used. If the operator uses the device 40 as the sender, then he must be informed of the nature of the receiving device in the subscriber to be called. The operator can therefore input function data using the keys of the control / display part 44 associated with the subscriber to be called, thereby causing the SCU 42 to notify the CCU 50 of the function. On the other hand, if the facsimile machine 40 serves as the receiver, then the data link controller that provides the adaptation to a sending party can not be executed until the device 40 does not know for itself whether the sending party is from the group 3 or the group 4, what is detected from a data link control signal sent by the sending party.

In the illustrated embodiment, the above requirement is met by programming the workflow at the beginning of a call setup so that the device 40 can enter the group 4 data transfer control only before a predetermined period of time has elapsed after receiving a call and then only to the group -3 data transfer control occurs.

In the case where the apparatus 40 operates as a transmitting apparatus and the receiver is a group 4 facsimile machine, it sends a transport connection command signal TCR (see Fig. 5) to the receiving party before a period T. after a call has elapsed to execute the group 4 data link control. If the receiving party is a group 3 facsimile machine, then the sending machine 40 enters the group 3 data link control

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at the moment the call is generated, and then awaits the return of a digital identification signal DIS (see Fig. 6) from the receiving station. Since it is prescribed that the group 3 data link controller receive a digital identification signal DIS within a predetermined period of time T₂ sends back after the call, the transmitting device 40 continuously waits for the return of a digital identification signal DIS until the time period T₂ has passed (see Fig. 6).

Suppose next that the facsimile machine 40 operates as a receiver under the above conditions. If the receiving device 40 has not received a transport connection command signal TCR before the time T. after the reception of a call, then it may decide that the transmitting subscriber is a group 3 device. When the receiving device 40, a transport connection command signal TCR within the period T. after receiving the call, then it may decide that the sending party is a group 4 party. In this way, the data link control to be executed in the receiving apparatus 40 is set.

Since the time period T₂ 30 + _ 50 seconds according to the group 3 data control, may be as the time period T₁ a period of time not longer than T₂that is shorter than 30 seconds.

In this way, the facsimile machine 40 is able to communicate with both group 3 and group 4 subscribers without requiring any change to the existing group 3 data link control.

It can be seen that the facsimile machine in this special

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Embodiment is able to connect with Group 3 and Group 4 facsimile participants as desired. This advantage stems from the connection setup controllers that can selectively perform data link control necessary for connection to a Group 3 subscriber or connection to a Group 4 subscriber. A predetermined period of time after a call is generated is provided as a time period within which the device 40 can enter the group 4 data link control, and after expiration of the mentioned time period, the device 40 enters the group 3 data link control.

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