CA2098364A1

CA2098364A1 - Communication apparatus, notably for a facsimile device

Info

Publication number: CA2098364A1
Application number: CA002098364A
Authority: CA
Inventors: Benjamin Schlesinger
Original assignee: Swatch AG
Current assignee: Swatch AG
Priority date: 1992-06-30
Filing date: 1993-06-14
Publication date: 1993-12-31
Also published as: JPH0698070A; CN1082795A; TW223210B; KR940006378A; FR2693061A1; EP0578070A1

Abstract

ABSTRACT

The communication apparatus (1) is connected to a telecommunication line (12) and detects if a telephone (11) connected in parallel takes the line. In this case, the apparatus (1) detects if a facsimile call signal is present on the line (12) or if the line is silent during a certain time, thereby indicating if an image signal is to be transmitted/received on the line (12). The apparatus (1) is thus able to receive/transmit an image signal on the line (12), even if the telephone (11) which is connected in parallel with the apparatus (11) is in use.

Description

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Case 969 COMMUNICATION APPARATUS. NQTA~LY FOR A FACS:[MILE DEVI~_ The present invention relates to communication apparatus such as facsimile devices, and in particular to communication apparatus including automatic switching arrangements responsive to either voice or image signals received via a communication line. The present invention is suitable for use in communication apparatus combining a facsimile device, telephone device and automatic telephone answering device and it will be convenient to hereinaEter disclose the invention in relation to that exemplary application. It is to be appreciated, however, that the invention is not limited to this application.
Communication apparatus are known which comprise a facsimile device coupled to a telephone line together with a telephone device. These devices are alternatively switched to the telephone line in order that they can respectively perform their functions. In certain of these apparatus, it is necessary to firstly disconnect the telephone line and the telephone device switched to the telephone line in order that the facsimile device can be connected to the telephone line and receive or transmit facsimile messages. When a user of this type of communication apparatus responds to a telephone call by picking up the telephone handset of the telephone device, the telephone device is connected to the telephone line and the caller and the user may talk to each other. If the user wishes to subsequently receive a facsimile message on the same telephone line, he must firstly replace the handset, thereby disconnecting the telephone device from the telephone line. The communication apparatus must then be set so that the facsimile apparatus is switched to the telephone line and when a call signal is then received by the communication apparatus, the facsimile apparatus is .: , -, ~9~3~

connected to the telephone line and can receive the facsimile message from the user.
In other communication apparatus, a signal identifying the type of message to be transmitted from the caller to the user is employed. The presence or absence of a CNG signal or facsimile calling tone is used to indicate whether the message which follows will be a facsimile message or a voice message. Thus, when a CNG signal is detected in a call signal received by the communication apparatus, the facsimile apparatus is automatically switched to the telephone line. I`he communication apparatus is then connected to the telephone line and a facsimile message received. Similarly, during a telephone conversation between a caller and the user of a communication apparatus of this type, the caller can cause a CNG signal to be sent to the user, so that upon detection of the CNG signal, the communication apparatus of the user causes the facsimile apparatus to be switched to the telephone line thereby enabling a facsimile message to be received without the disconnection of the communication apparatus from the telephone line.
The convenience of communication apparatus including facsimile devices is widely appreciated today, and such communication apparatus are found increasingly in homes for personal or business use. Most homes are provided with only a single telephone line and one or more telephone devices coupled to this telephone line. However, existing communication apparatus are designed to be used with a dedicated telephone line. For example, if an in-coming call is answered by a user using a separate telephone device coupled to the same telephone line as an existing communication apparatus, only the separate telephone device is connected to the telephone line. In order to send or receive a facsimile message using the communication apparatus, it is necessary Eor the user to firstly hang-up and break the connection of the separate . ~ . .: : : -:
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telephone device to the telephone line, and then for the caller to redial the user's telephone number so that the communication apparatus can respond to the call signal and switch the facsimile device of the communication apparatus to the telephone line.
The object of the present invention is to provide a communication apparatus which overcomes or alleviates the disadvantages of known communication apparatus.
With that object in mind, the present invention provides a communication apparatus Eor use with a telephone device connectable to a communication line, comprising communication means for receiving and transmitting an image signal from said communication line, call detecting means provided between said communication line and said communication means for detecting a call signal on said communication line, a connecting switch for connecting said communication apparatus to said communication line to thereby enable communication between said communication means and said communication line, signal identification means for detecting an image signal identifier from said communication line, said image signal identifier preceding an image signal, and control means for enabling said image signal to be received by said communication means upon detection of said image signal identifier, characterised in that said communication apparatus further comprises means to detect the connection of said telephone device to said communication line in response to said call signal, such that upon the detection of said connection, said connecting switch is caused to close and thereby enable said signal identification means to monitor said communication line for said image signal identifier without disconnecting said telephone device from said communication line.
When a user responds to an in-coming call on a telephone which is separate from the communication apparatus of the present invention, and the separate .
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telephone is connected to the telephone line, the communication apparatus is adapted to also be connected to the telephone line. If a signal identifying a facsimile message is detected, the facsimile message can be received by the communication apparatus wlthout firstly disconnecting the separate telephone Erom the telephone line.
The following description refers in more detail to the various features of the communication device of the present invention. In order to facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the communication apparatus is illustrated in a preferred embodiment. It is to be understood that the communication apparatus of the present invention is not limited to the preferred embodiment as illustrated in the drawings.
In the drawings:
Figure 1 is a schematic block diagram of one embodiment of the communication apparatus of the present invention; and Figure 2 to 4 are flow charts for explaining the operation of the communication apparatus of figure 1.
Referring now to figure 1 of the drawings, there is shown a schematic block diagram of a communication device 1 constructed in accordance with the present invention.
Functional blocks representing circuitry such as a dial pulse generator, necessary for initiating the calling, and circuitry associated with a facsimile other than the facsimile controller have been omitted for the sake of clarity of explanation. The communication apparatus 1 comprises a facsimile device 2, a telephone device 3, a telephone line interface circuit 4, a switching circuit 5, a signal detection circuit 6, a facsimile controller 7, a voice message recording section 8, a voice message generator 9 and a controller 10. A separate telephone device 11, comprising a standard handset and base, is : , ' , ~: ' ~ :,' ,:,,; ' ' , ~:. ': . ` ' :
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coupled to a telephone line 12 together with the communication apparatus 1. The relationship between the communication apparatus 1 and the separate telephone device 1 will be explained later.
The telephone line interface circuit 4 comprises a call detector circuit 20 connected to the telephone line 12. An output 20a of the call detector circuit 20 provides the controller 10 at an input lOk a signal indicative of the presence of a call or ring signal on the telephone line 12. Such a call or ring signal may typically be a 16 Hz signal generated from a telephone exchange (not shown) in a waiting state, however as the frequency and nature of such call signals vary from region to region it is to be understood that the characteristics of the call detector 20 will also vary. The controller 10 is provided with a counter 32 for monitoring the period that the input lOk indicates a call signal is present on the telephone line 12.
The telephone line interface circuit 4 also comprises a connecting switch circuit 21, a switch energising circuit 22 and an isolation device 23. The connecting switch circuit 21 comprises a switching transistor 21.1, the collector of which is connected to the isolation device 23 and the emmitter of which is connected to the telephone line 12. A silicon phototransisitor 21.2 is also provided and has an emmitter connected to the base of the switching transistor 21.1 and a collector connected to the collector of the switching transistor 21.1. A biasing resistor 21.3 is also connected between the emmitters of the switching transistor 21.1 and the phototransistor 21.2. The switch energising ciruit 22 comprises an infrared LED 22.1 for coupling with the phototransistor 21.2. The switching transistor 21.1 is normally in a non-conducting state, thereby preventing communication between the communication apparatus 1 and the telephone line 12.
When the infrared ~ED transmits light to the .

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phototransistor 21.2 which in turn causes the switching transistor 21.1 to conduct and thereby connect the communication apparatus 1 to the telephone line 12, communication is enabled between the communication apparatus 1 and the telephone line 12 so that voice, image and other communication signals can be received and transmitted by the communication apparatus 1.
The infrared LED 22.1 which thus controls the conducting or non-conducting state of the switching transistor 21.1, has one side connected to an ouput lOa of the controller 10 via a resistor 22.2 and the other side connected to a ground supply. When the output lOa goes high, light is transmitted from the infrared LED 22.1 to the phototransistor 21.2 and the switching transistor 21.1 is caused to conduct; when the output lOa goes low the swithcing transistor 21.1 ceases to conduct and the communication apparatus 1 is disconnected from the telephone line 12.
The isolation circuit 23 is connected between the connecting switch 21 and the switching circuit 5 in order to provide electrical isolation between the communication apparatus 1 and the telephone line 12. The telephone handset 3, facsimile device 2 and other detection, control and message circuitry of the communication apparatus 1 are thus provided with protection against power surges and voltage spikes appearing on the telephone line 12. The line isolation circuit 23 may comprise optical coupling devices, transformer coils or other known electrical isolation devices The telephone device 3 comprises a communication circuit 3.1, a handset having a transmitter 3.2 and a receiver 3.3, and a hookswitch 3.4. When a user of the communication apparatus speaks into the receiver 3.3, voice signals are sent to the communication circuit 3.1 which amplifles the voice signal. An output 3a is provided for the transmission of these amplified voice signals to a . . ..
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third party via the telephone line 12. Similarly, an input 3b is provided by the communication circuit 3.1 at which are received communication signals transmitted from a third party via the telephone line 12. The thus received signals are amplified by the communication circuit 3.1 and sent to the transmiiter 3.2 in order that they may be heard by the user of the commmunication apparatus 1.
One terminal of the hookswitch 3.4 of the telephone device 3 is connected to the positive terminal of a power supply and the other terminal is connected to an input 10j of the controller 10. A resistor is also provided between the other terminal of the hookswitch 3.4 and a ground supply. When the telephone handset comprising the receiver 3.3 and the transmitter 3.2 is raised from a support, the hookswitch is caused to close and a high logic level signal is applied to the input 10j.
The facsimile device 2 of the communication apparatus 1 is well known and will not be described in detail, but is capable of receiving, printing and transmitting image signals via the telephone line 12. The facsimile controller 7 controls the operation of the facsimile device 2 according to a facsimile start instruction received at an input/ouput 7a from an input/output 10i of the controller 10. Upon completion of a facsimile communication by the facsimile device 2, a facsimile communication end signal is also sent from the input/output 7a to the controller 10. The facsimile controller receives image signals at an input 7b which have been transmitted by a third party via the telephone line 12, which signals can then demodulated and sent from an input/output 7c to an input/output 2a of the facsimile device 2. Similarly, image signals sent from the input/output 2a of the facsimile device 2 are amplified and modulated by the facsimile controller 7 from transmission at an output 7d.

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The switching circuit 5 is adapted to switch the facsimile device 2 and/or at the same time the telephone device 2 to the telephone llne 12 via the telephone interface circuit 4. The switching circuit 4 comprises four switch devices 24, 25, 26 and 27. The switch devices 24 and 27 are adapted to enable the telephone device 3 and the facsimile device 2 respectively to receive communication signals from the telephone line 12, whilst the switch devices 25 and 26 are adapted to enable the telephone device 3 and the facsimile device 2 respectively to transmit comunication signals to the telephone line 12.
The switch device 24 is provided with a contact 24.1, one terminal of which is connected to the input 3a of the telephone device 3 and the other terminal of which is connected to an input 23a of the isolation circuit 23 of the telephone line interface circuit 4. The switch device 25 is provided with a contact 25.1, one terminal of which is connected to the output 3a of the telephone device 3 and the other terminal of which is connected to an input 23b of the isolation circuit 23.
Similarly, the switch device 26 is provided with a contact 26.1, one terminal of which is connected to the output 7d of the facsimile controller 7 and the other terminal of which is connected together with the other terminal of the contact 25.1 to the input 23b of the isolation circuit 23. The switch device 27 is provided with a contact 27.1, one terminal of which is connected to the input 7b of the facsimile controller 7 and the other terminal of which is connected together with the other terminal of the contact 24.1 to the output 23a of the isolation circuit 23.
Further, the switch devices 24, 25, 26 and 27 are respectively provided with inputs 24a, 25a, 26a and 27a for receiving control signals from ouputs lOb, lOc, lOd and lOe of the controller 10. These control si~nals cause the contacts 24.1, 25.1, 26.1 and 27.1 to adopt either an ,- . ~ .

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open or a closed position. The switch devices 24, 25, 26 and 27 may be embodied as analog devices using energising coils to control the position of a contact, digital devices wherein control signals are applied to the base of switching transistors, or other appropriate devices as will be appreciated by those skilled in the art.
The signal detection circuit 6 comprises a CNG
detector 28, a silence detector 29 and a busy detector 30, each of which is connected together at inputs 28a, 29a and 30a respectively to the input 7b of the facsimile controller 7. The CNG detector 28 detects a CNG signal sent from a caller after a call signal is detected and enables the facsimile device 2 and facsimile controller 7 to be switched to the telephone line 12 by the switching circuit 5. Upon detection of the CNG signal, the CNG
detector 28 sends a CNG detect signal from an ouput 28b to an input lOf of the controller 10 which subsequently controls the operation of the switching circuit 5.
Although this particular embodiment of the communication apparatus is adapted to detect and respond to CNG signals, it is to be appreciated that other signals distinguishing an image signal from a voice signal may be used and that the detector 28 should be adapted to detect and provide an output in response to these other signals.
The silence detector 29 detects the absence of voice or image signals on the telephone line 12, thereby enabling the communication apparatus to automatically detect when an image message is sent from a caller using a manually operated facsimile station i.e. where a signal such as a CNG signal is not transmitted prior to the transmission of a facsimile message. When neither a voice nor image signal is detected by the silence detector 29, an ouput 29b provides a signal indicative of such to an input lOg oE the controller 10. The controller 10 is provided with a counter 31 to enable the controller 10 to monitor the period that the silence detector 30 indicates .
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that no voice or image signal is present on the telephone line 12. When this period exceeds a certain stored predetermined time t2, which may be 6 seconds or more, the controller 10 is adapted t;o enable the facsimile controller 7 and the facsimile device 2 to receive an image message.
The busy detector 30 detects a repetetive tone sent from a telephone exchange when, after communication has been established between telephone or facsimile device of a remote caller and the communication apparatus la, the remote caller disconnects his telephone or facsimile device from the telephone line 12. An ouptut 3Ob provides a signal indicating that a busy tone has been detected to an input lOh of the controller 10. The busy detector 30 may be adapted to detect other signals indicating this break in communication, depending upon the type of signal sent by the telephone exchange to the communication apparatus 1, as will be appreciated by those skilled in the art.
The communication apparatus 1 further comprises a a call annunciator 33, driven from an output lOm of the controller 10, which can be enabled to announce the detection of a call signal on the telephone line 12 to a user of the communication apparatus 1. The call annuniciator 33 may comprise in a conventional manner a bell, vibrator or any other similar device able to produce a characteristic sound, noise or visual indication in response to an annunciation signal from the output lOm.
The controller 10 also comprises a counter 34 for timing the period that the ouput lOm supplies the call annunciator 33 with the annunciation signal.
The recording section 8 is coupled at an input 8a to the input 7b of the facsimile controller 7 which records an incoming analog voice message in response to a record start instruction provided from the controller 10 at an ouput lOn to an input 8b of the recording section 8. The .
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recording section 8 may comprise a recording device such as a tape recorder or other magnetic storage medium or may be constituted by an encoder and a RAM or other suitable recording medium.
The message generator 9 is coupled at an output 9a to the output 7d of the facsimile controller 7. A voice message is generated and provided at the output 9a to inform a caller that the user of the communication apparatus is absent in response to a send message signal at an input 9b from an output 10o of the controller 10.
The controller 10 performs the overall control of the communication apparatus and may be constituted by a microcomputer, containing in a known manner a microprocessor, a RAM for variable data storage, a ROM for the storage of operating instructions and associated input/output ports, control, data and address buses. The counters 31 and 33, recording section 8, message generator 9, I/O ports 10a to 10o and instructions for the operation of the communication apparatus 1 may be embodied as a microcomputer, although those skilled in the art will appreciate that other circuit configurations, including discrete hardwired elements, may also be used.
Referring to figures 2 to 4, the operation of the communication apparatus 1 as shown in figure 1 will now be explained.
In a waiting state in which communication is not established between the communication apparatus 1 and another telephone or facsimile device, and in which no call signals are present on the telephone line 12, the telephone handset of the telephone device 3 is supported so that the hookswitch 3.~ is caused to be in an open position as shown in figure 1. The contacts 24.1 to 27.1 of the switch devices 2~ to 27 are in an open position, so that neither the telephone device 3 nor the facsimile device 2 are switched so as to be connectable to the telephone line 12, although in another embodiment of the - , ~ - " . ~ .

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communication apparatus 1 it may be desirable to have either or both of these devices switched to a connectable position in a waiting mode.
When a call signal is det;ected by the call detector 20 in step al of figure 2 in the waiting state, a call detect signal is sent ~rom its output 20a to the input 10k of the controller 10. The counter 32 is enabled by the controller 10 and in step a2 commences timing the duration of the call signal detected on the telephone line 12.
A value tl corresponding to a predetermined time period is stored in the ROM of the controller 10, and when the call detector 20 no longer detects that a call signal is present on the telephone line 12, the controller 10 in step a3 compares this stored value tl with the value of the counter 32 at that time. If the value of the counter 32 is less than the stored time tl, the controller 10 assumes at step a~ that a telephone or facsimile device, coupled to the telephone line 12 in the manner of the telephone device 11 of figure 1, has been connected to the telephone line 12. The controller 10 at step a5 provides a high level signal from its output 10a to the switch energising ciruit 22, thereby causing the switching transistor 21.1 to conduct and connect the communication apparatus 1 to the telephone line 12. This condition will be explained in detail later.
However, if the controller 10 determines that a call signal is still present on the telephone line 12 after the stored minlmum period, the controller 10 at step a6 assumes that no telephone or facsimile device connected in parallel to the communication apparatus 1 has been connected to the telephone line 12, and the communication apparatus 1 is connected to the t`elephone line 12 as above.
In this condition, the controller 10 also sends a control signal at its output 10e to the switch device 27 so as to thereby cause contact 27.1 to close and switch :" ~ . . .

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the facsimile controller 7, CNG detector 28, silence detector 29 and busy detector 30 to the telephone line 12.
When the connecting switch 21 is closed, the CNG detector 28, silence detector 29 and busy detector 30 commence monitoring the telephone line 12. If a CNG signal is detected at step bl of figure 3, the controller determines at step b2 that a facsimile message is to follow and sends a facsimile start instruction at its output lOi to the input 7a of the facsimile controller 7 to enable the facsimile controller 7 to send the image signals received at its input 7b to the inputjouput 2a of the facsimile device 2 for printing at step b3.
If no CNG signal is detected at step bl, the controller 10 at step b4 checks if any messages are stored at the recording section 8 which have not been replayed by the user of the communication apparatus 1. If such messages exist, the controller 10 assumes that the user is absent and at step b8 sends a control signal from the ouput lOd to the switch device 26 so as to close the contact 26.1. The controller 10 then sends a send message signal from the output lOo to the message generator 9 which sends an outgoing message and beep to the caller via the telephone line 12 If no unchecked messages are found to be stored in the recording section 8 at step b4, the controller at step b5 sends a ring signal from its output lOm to the call annunciator 33 so as to thereby announce the reception of the call signal to the user of the communication apparatus 1.
comparison is made at step b6 between the value of the counter 34 and a predetermined value t3 stored in the ROM of the controller 10. If the controller 10 detects that the handset of the telephone device 3 is raised, causing the hookswitch 3.4 to close, before the stored time t3 has elapsed, the telephone device 3 is switched to the telephone line 12. Thus the controller at step b7 ;

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sends a control signal at each of its outputs 10b and 10c to the switch devices 24 and 25 so as to cause the contacts 24.1 and 25.1 to close and enable the user of the communication apparatus 1 to transmit and receive voice messages via the transmitter 3.3 and the receiver 3.2 respectively.
If the handset of the the telephone device 3 is not raised from its support so that the hookswitch 3.4 remains in an open position after the predetermined time t3, the controller 10 at step b8 again assumes that the user of the communication apparatus 1 is absent and sends a send message signal from its output 10a to the message generator 9 as explained above.
If the silence detector 29 does not indicate that a predetermined period t2 of silence is detected at step b9 and the busy detector 30 does not detect a busy tone on the telephone line 12, the controller 10 at step bll sends a record start instruction from its output 10a to the recording unit 8 and the voice message sent by the caller is recorded for later playback by the user of the communication apparatus 1. The steps b9 to bll are repeated until either the predetermined period t2 of silence is detected, or a busy tone is detected indicating the the caller has hung-up and disconnected his telephone or facsimile device from the telephone line 12. In the case of the latter, the controller 10 at step bl2 sends a low level signal from its output 10a to the switch energising circuit 22 in order to cause the switching transistor 21.1 to cease conducting and disconnect the communication apparatus 1 from the telephone line 12. The controller 10 thereafter returns the communication apparatus 1 to the waiting state for reception of a further call signal.
If, however, a period of silence is detected at step b9 which is greater than the predetermined time t2 stored in the ROM of the controller 10, any signals following are . .

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interpretted by the controller 10 at step bl3 as being part of a manually transmitted facsimile message (no CNG
signal is transmitted). At step bl4 the thus received facsimile message is printed and a facsimile communication end signal is sent by the facsimile controller 7 from its input/output 7a to the controller 10.
Referring back to step b6 now, if the handset of the telephone device 3 was raiseci from its support and the hookswitch 3.4 closed before the stored period t3, the controller 10 sends a control signal from each of its outputs lOb and lOc to the switch devices 24 and 25 to close the contacts 24.1 and 25.1 and thereby enables the user to transmit and receive voice messages by using the telephone device 3. Whilst the telephone handset remains raised, the detection of either a CNG signal by the CNG
detector at step bl5 or a period of silence greater than the time t3 (as in step b9) by the silence detector 29 at step bl6, respectively identifies the message following as a automatically transmitted facsimile message at step bl7 or an manually transmitted facsimile at step bl8. The thus identified facsimile message is printed at steps bl9 or b20.
After the transmission and printing of the facsimile message by the facsimile device 2, the user may continue to use the telephone device 3 to send and receive voice messages via the telephone line 12, or receive and transmit facsimile messages using the facsimile device 2, without disconnecting the communication apparatus 1 from the telephone line 12 until a busy tone is detected at step b21 indicating that the caller has hung-up. The controller 10 then disconnects the communication apparatus 1 from the telephone line 12 at step bl2 as explained above.
With reference now to figures 2 and 4, when the telephone device 11 coupled to the telephone line 12 separately from the communication apparatus 1 is used to .
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respond to a call signal on the telephone line 12, the connection of the separate telephone device 11 causes the transmission of the call signals from the telephone exchange to cease. AS explained above, when these call signals cease to be detected by the call detector 20 before a certain predetermined time tl has passed, the controller 10 assumes that the telephone device 11 has been connected to the telephone line 12 in step a8 and also connects the communication apparatus 1 to the telephone line 12 in step a5.
The controller 10 sends a control signal at its output 10e to the switch device 27 to close the contact 27.1 and thereby enable the communication apparatus 1 to monitor the telephone line 12 via the CNG detector 28, the silence detector 29 and the busy detector 30. If a CNG
signal is detected at step cl identifying an automatically transmitted facsimile message at step c2, the facsimile controller 10 sends a facsimile start instruction from its input/output 10i to the facsimile controller 7. The facsimile signals received at the input 7b of the facsimile controller 7 are then transmitted to the facsimile device 2 for printing at step c3.
Similarly, if a period of silence is detected which is greater than the predetermined time t2 stored in the ROM of the controller 10 at step c4, the signals following from the telephone line 12 are identified as being part of a manually transmitted facsimile message at step c5. The controller 10 then sends a facsimile start instruction to the facsimile controller 7 to enable it to send the received facsimile signals to the facsimile device 2 for printing at step c6.
Once the facsimile message has been printed, a facsimile communication end signal is sent from the facsimile controller 7 to the controller 10 so that signals on the telephone line 12 are no longer sent by the facsimile controller 7 to the facsimile device 2. However, , - ., ~ i;

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2~3~ 1 the outputs lOa and lOe of the controller 10 remain in a state whereby the coMmunication apparatus 1 stays connected to the telephone line 12. A user may thus continue to use the telephone device 11, after the transmission of a facsimile message, to send and receive voice signals; in this case, the communication apparatus 1 remains connected to the telephone line 12 and continues to monitor the telephone line 12 for a CNG signal or a period of silence greater than the stored value t2. If a further CNG signal or period of silence greater than the time t2 is detected, the controller 10 again sends a facsimile start instruction to the facsimile controller 7 and the facsimile message is printed by the facsimile device 2. In this manner, a user may alternate between facsimile message reception/transmision on the communication apparatus 1 and voice message reception/transmission on the separate telephone device 11 even though the call signal was responded to by using the separate telephone device 11.
As shown in figure 1 then, when a user responds to an incoming call signal on the telephone line 12 by using the separate telephone device 11 at step a8, he may hear a facsimile message being transmitted to the communication apparatus 1 at step a9. He may then at step alO hang-up and disconnect the telephone device 11 from the telephone line 12 or wait until the facsimile communication is finished and conduct a telephone conversation. Similarly, if he hears a period of silence at step all when he enables the connection of the telephone device 11 to the telephone line 12, he may at step 12 hang-up or wait until the facsimile communication has finished and conduct a telephone conversation. In the latter case he should remain silent or mute the receiver of the telephone handset in use so that a period of silence identifying a manually transmitted facsimile message may be successfully received by the communication apparatus 1.

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At step al3, the user may receive and transmit voice messages via the telephone line 12, following which he may send or receive a facsimile message at step al4 on the facsimile device 2 as the communication apparatus is also connected to the telephone line 12.
The steps cl and c4 are repeated until the user disconnects the telephone device 11 at step al5. When the communication device 1 detects a busy signal on the telephone line 12, the communication apparatus 1 is disconnected from the telephone line 12 in step c8 and returns to the waiting state.
Finally, it is to be understood that various modifications and/or additions may be made to the communication apparatus without departing from the ambit of the present invention as defined in the claims appended hereto.

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Claims

1. A communication apparatus for use with a separate telephone device (11) connectable to a communication line (12), comprising communication means (2) for receiving and transmitting an image signal on said communication line (12), call detecting means (20) provided between said communication line (12) and said communication means (2) for detecting a call signal on said communication line (12), a connecting switch (21) for connecting said communcation apparatus to said communication line (12) to thereby enable communication between said communication means (2) and said communication line (12), signal identification means (6) for detecting an image signal identifier from said communication line (12), said image signal identifier preceding an image signal, and control means (10) for enabling said image signal to be received by said communication means (2) upon detection of said image signal identifier, characterised in that said communication apparatus further comprises means (20,32) to detect the connection of said separate telephone device (11) to said communication line (12) in response to said call signal, such that upon the detection of said connection, said connecting switch (21) is caused to close and thereby enable said signal identification means (6) to monitor said communication line (12) for said image signal identifier without disconnecting said separate telephone device (11) from said communication line (12), said connection detecting means (20,32) having a call signal timer (32) for timing the duration of said call signal, and comparing means (10) for comparing said duration of said call signal with a predetermined stored time (t1), wherein said connecting switch (21) is caused to connect said communication apparatus to said communication line (12) when said call signal duration is less than said predetermined stored time (t1).

2. A communication apparatus according to claim 1, and further comprising a call annunciator (33) for announcing the detection of a call signal by said call detector (20), characterised in that said detected call signal is not announced by said call annunciator (33) unless said call signal duration is greater than said predetermined stored time (t1).

3. A communication apparatus according to claim 2.
characterised in that said connecting switch (21) is closed to connect said communication apparatus to said communication line (11) when said call signal duration is greater than said predetermined stored time (t1).

4. A communication apparatus according to any one of the preceding claims, characterised in that said signal identification means (6) comprises a CNG
detector (28) for detecting a CNG signal on said communication line (12).

5. A communication apparatus according to any one of the preceding claims, characterised in that said signal identification means (6) comprises a silence detector (29) for detecting the absence of voice and image signals on said communication line (12) during a predetermined period (t2).

6. A communication apparatus according to claim 5, characterised in that said predetermined period (t2) is at least 6 seconds.

7. A communication apparatus according to any one of the preceding claims, characterised in that said communication apparatus further comprises a busy signal detector (30) for detecting a busy signal on the communication line (12), wherein said connecting switch (21) is caused to open and thereby disconnect said communication apparatus from said communication line (12) upon detection of said busy signal.

8. A communication apparatus according to any one of the preceding claims, characterised in that said communication apparatus further comprises a dedicated telephone device (3) for receiving and transmitting a voice signal on said communication line (12), and switching means (5) for switching said dedicated telephone device (3) and said communication means (2) to said communcation line (12).

9. A communication apparatus according to claim 8, characterised in that said communication apparatus further comprises a recording section (8) for recording said received voice signal for later playback.

10. A communication apparatus according to any one of the preceding claims, characterised in that said communication means (2) comprises a facsimile device.