GB1569270A

GB1569270A - Telephone answering machines

Info

Publication number: GB1569270A
Application number: GB124076A
Authority: GB
Original assignee: Ansafone Ltd
Current assignee: Ansafone Ltd
Priority date: 1976-01-13
Filing date: 1976-01-13
Publication date: 1980-06-11
Also published as: DE2701257A1

Description

(54) IMPROVEMENTS IN OR KELATING I TO TELEPHONE ANSWERING MACHINES (71) We, ANSAFONE LIMITED. a British Company. of 19 Upper Brook Street, London, W1Y 2HS, England, do hereby declare the invention. for which we pray that a Patent may be granted to us, and the method by which it is to be performed.

to be particularly described in and bv the following statement: This invention relates to telephone answering machines.

The invention includes a telephone answering machine comprising sound recording and reproducing means. means for generating coded electrical signals representative of the time. control means adapted.

when the machine is connected to a telephone line and a ringing signal is applied to the line from a remote caller. to actuate the sound recording and reproducing means and the generating means in a predetermined sequence so that a recorded answering text is transmitted to the caller via the line and an incoming message from the caller and a coded electrical signal representing the time at which the incoming message was received are recorded on a sound recording medium.

further control means for actuating the sound recording and reproducing means so that the recorded message and the recorded coded electrical signal are reproduced. and means for applying the coded electrical signal to a display unit which provides a visual display of the time represented by the coded electrical signal.

Suitably, there is provided in combination with a telephone answering machine according to the preceding paragraph a device for remotely controlling the operation of the machine, the remote control device comprising means for generating an audio trie- ger signal for application to the machine via a handset connected to a telephone line.

thereby to cause the machine to reproduce the coded electrical signal and to produce a further electrical signal representing the recorded message and to transmit the coded electrical signal and the further electrical signal to the handset via the line. the handset converting the coded electrical signal and the further electrical signal into audio signals. an audio electrical transducer for re-converting the audio signal derived from the coded electrical signal back into a coded electrical signal. a display device. and means for applying the re-converted coded electrical signal to the display device.

whereby the display device provides a visual display of the time represented by the coded electrical signal.

The invention will now be described, by wav of example. with reference to the accompanying drawings. in which: Figzire 1 is an embodiment of a telephone answering machine according to the Inven- tion: and Figure 2 is a remote control device for use with the machine of Figure 1.

The telephone answering machine shown in Figure I of the drawings is designed for connection to a telephone line L1. L2 in parallel with a subscriber's handset.

In the present machine a telephone interface I is provided for coupling the machine to the line LI. L2 and for generating certain control signals necessarv to the subsequent operation of the machine. An announcement tape unit 3 serves as a first sound recording and reproducing means for transmitting à pre-recorded answering text to a caller at a remote extension and a message tape unit 5 serves as a second sound recording and reproducing means for recording an incoming message from the caller. Also provided in the machine is a clock 7 for generating a coded electrical signal representing the time at which a call is received.This coded signal is applied to the message tape unit 5 via a digital converter 9 and a datairecord read unit 11 and is recorded in the unit 5 whilst the answering text is being transmitted from the announcement tape unit 3. When the message tape unit 5 is operated to reproduce a recorded message a visual display of the time at which the message was recorded is provided on a display unit 13.

The telephone interface 1 of the present machine includes a combined detector and delay unit 15. A pair of inputs to the detector 15 are capacitatively connected to respective conductors of the line L 1. L2 and a pair of outputs from the unit are connected to a winding RL of a relav. The detector 15 is adapted to detect an incoming ringing signal on the line Ll. L2 and to generate an output signal in the winding KL if the incoming signal persists for a predetermined interval of time. determined bv the delay. Associated with the winding RL are a first pair of relav contacts RLl each of which is connected between a respective one of line conductors and a primary winding of a line transformer TX.A further relay contact RL2 is connected between a 12 volts supply and an input to a delay 17. formed by a monostable device.

A first output signal from the interface I is obtained via a capacitor from the junction between the relay contact RL2 and the delay 17. This first output signal is a "start announcement" signal which is applied to the announcement tape unit 3. as hereinafter described. A second output signal from the interface l is obtained from the output of the delay 17. The second output signal is a 'write-enable" signal which lasts tor It) seconds and is applied to the message tape unit 5 and to one input of an inhibit gate 19.

as hereinafter described.

Included in the announcement tape unit 3 are storage means (not shown) for an endless loop of magnetic tape '1. a motor M1 for driving the tape 'l around the loop.

and a first sound recording and repro(lucin,y head H1 for replaying messages recorded on the tape 21.

An audio amplifier Al connects the head H1 to a first audio output from the unit 3 and this output is in turn connected to a secondarv winding of the transformer FX in the interface 1.

The motor Ml is connected to an output of a control circuit 23. which has a first.

"start" input connected to the first. "start announcement" output from the interface 1.

When a transitory "start announcement signal is venerated in the interface I and applied tithe "start" input of the circuit 2'l.

the circuit generates a continuous power signal for energising the motor NI 1.

A metal strip NlS is provided on the tape 21 and a pair of contacts 25 which are associated with the strip are mounted alonu- side the loop. One of the contacts 25 is connected to a second, "stop" input to the control circuit 23 and the other contact 25 is connected to earth potential. The strip MS short circuits the contacts 25 each time the tape 21 has been driven round the loop and returned to an initial position.When the contacts 25 are short circuited the "stop" input to the control circuit 23 is connected to earth potential. whereupon the power signal from the circuit is terminated and the motor Ml ceases to drive the tape 21.

The second contact 25 is also connected to a second. "end announcement. start message" output of the unit 3. This second output is connected to an input to the message tape unit 5.

The output of the motor control circuit 23 is connected to a control terminal of the amplifier Al and it is also connected via a third "urite-enable" output of the unit 3 to a second input of the inhibit gate 1C). This eate 19 is an AND-gate and has an output connected to the data record/read unit 11.

The message tape unit t includes supplv and take-up spools for a second magnetic tape '7. a second tape driving motor M2 and a second sound recording and reproducing head 11' for recording messages on the tape '7 and subsequently reproducing recorded messages.

For energising the motor M' a motor drive circuit 29 and an associated memorv circuit 31 are provided in the unit 5. The memory circuit 31 has a first input connected directlv to the above-mentioned second output of the announcement tape unit 3 and a second input connected to the same output from unit 3 via a 3O second timer 33. An output from the timer 33 is also connected to the delay 15 in the interface 1.

The motor drive circuit 29 has an input connected to an output from the memory circuit 31 and an output connected to the motor M2. There is also a direct connection to the input of the drive circuit 29 from the second. "write-enable" output of the interface 1.

The head H2 is connected to an output of an audio amplifier A2 whose input is coupled to the secondarv winding of the line transformer %X in the interflce 1. A control terminal of the amplifier A2 is connected to the second output of the interface 1.

The display unit 13 in the present machine includes a series of four "7-segment" display elements which together provide a visual.

four-figure indication of the time (in hours and minutes). Such units are commonly available in the form of electronic watches and clocks.

Coded eleetneal signals for energising the display unit 13 are venerated bv the clock 7.

which includes an oscillator. a series of divider circuits. a scanner and seven output terminals. the clock 7 generates four sets of hinarv signals. each set consisting of seven parallel coded signals which together represent one of the figures making up the four figure indication of time. Operation of the scanner causes the sets of seven signals to be applied to respective outputs of the clock 7 in sequence.

Each output from the clock 7 is connected to a first, fixed pole of an associated switch and to an associated input of the digital converter 9. A second, movable pole of each of the seven switches is connected to a respective one of seven inputs to the display unit 13. Finally, a third, fixed pole of each switch is connected to an associated output from the digital converter 9.

The seven switches at the output of the clock 7 are ganged together to form a manually operable record/replay switch 35.

In the digital converter 9 there are a parallel-serial converter 37 and a serialparallel converter 39. The converter 37 has seven inputs, which are connected to rcspective outputs of the clock 7. and a single output, which is connected to an input of the data record/read unit 11. In the converter 37 each set of seven parallel coded signals is converted into a serial coded signal. The converter 39 has a single input. which is connected to an output from the data record/read unit It. and seven outputs. In the converter 39 serial coded signals. each generated in the data record/read unit II as hereinafter described, are converted into parallel coded form. A memorv device 4() has seven inputs. which are connected to respective outputs from the converter 39.

and seven outputs. which are connected to the third poles of respective switches at the output of the clock 7. Within the memory device 40 there are four sections. each adapted to store a set of seven bits of information applied to respective inputs to the device. The device 4() can therefore store information corresponding to the tour sets of binary signals needed to make up the four-figure indication of time. A strobe unit 42 is provided for causing the four sets of information bits stored in the device 4() to be applied to the outputs of the device in a continuous sequence.

The data record/read unit 11 includes a modulator 41 having an input connected the output of the converter 37 in the digital converter 9 and an output connected to an input of a data amplifier 43. An output of the amplifier 43 is connected to the head H' in the message tape unit 5. A demodulator 45 has an input connected to the output of a data preamplifier 47 and an output con nected to the input of the converter 39 in the digital converter 9. An input to the data amplifier 47 is connected to the head H2.

Each of the data amplifiers 43 and 47 also includes a control terminal. The control terminal of the data amplifier 43 is connected directlv to the ouput of the inhibit gate 19 whilst the control terminal of the amplifier 47 is connected to the output of the gate 19 via an inverter 49.

The modulator 41 is adapted to convert each pulse in the serial coded signals from the converter 37 into a short burst of oscillations. The burst has an envelope which corresponds to the shape of the pulse from converter 37 and the oscillations within the burst have a frequency of 4K Hz. Such modulated signals are suitable for recording on the tape 27 in the message tape unit 5.

The demodulator 45 receives short bursts of oscillations which have been reproduced from the tape 27 and converts each burst into a pulse whose shape corresponds to the envelope of the burst.

A filter 51 and an audio amplifier 53 connect the head H2 in the message tape unit 5 to a loudspeaker 55 for playing back messages recorded on the tape 27. Manually operable controls are provided on the message tape unit 5 to enable the user to play back messages recorded on the tape 27. One of these controls is a rewind control which operates a further motor (not shown) for rewinding the tape 27 from the take-up to the supply spool. A second manual control is a pl'iy hack control which actuates the motor drive circuit 29. therebv energising the motor M2 to drive the tape '7 forward ly. and which also couples the head H2 to the speaker 55 via the filter 51 and the amplifier 53.

When the present machine is in use the telephone interface I is connected to the telephone line LI. L2 at the subscriber's extension. as shown in the drawing. The switch 35 is set to connect the inputs to the display unit 13 to respective outputs from the clock 7.

When a caller at a remote extension dials the subscriber's number an incoming ringing current appears on the line LI, L2 and is applied to the handset and to the detector 15 in the interface 1. If the subscriber does not answer the call by lifting his handset and the rinFine current persists for more than ten seconds. the detector 15 generates an output signal which is applied to the relay winding RL. The output signal energies the relay and causes the pair of contacts RLl and the contacts RL2 to close.

With the contacts RLI closed the line LI.

L2 is "looped". i.e.. the primarv winding of the line transformer TX is connected between the conductors of the line and provides a conductive path for audio and D.C.

sienals. With the contacts RL2 closed a voltage from the 17 volts supply is applied to the delay 17 and to the capacitor connected to the input of the delay.

I he application of 1' volts to one termin I of the capacitor results in a transitory.

"start-announcement" signal at the other terminal. This transitory signal is applied to the start input of the motor control circuit 23 in the announcement tape unit 3 and a continuous power signal is then generated at the output of the circuit. The power signal energises the motor M I and the amplifier Al so that the tape 21 is driven around the loop and the answering text recorded on the tape is reproduced and transmitted to the remote caller via the line transformer TX and the line L1. L2. The power signal is also applied to the second input of the gate 19.

switching this input to a logic 1 condition.

The application of 12 volts to the input of the delay 17 causes a "write-enable" signal of 10 seconds duration to be generated at the output of the delay. The "write-enable" signal is applied to the first input of the gate 19 and to the first input to the message tape unit 5.

With a "write-enable" signal applied to the first input of the gate 19, both inputs to the gate are in a logic 1 condition and the output of the gate is also switched to a logic 1 condition. A voltage corresponding to a logic 1 is therefore applied to the control terminal of the data amplifier 43 and the amplifier is actuated. The voltage from the output of the gate 19 is inverted by the inverter 49 before application to the control terminal of the data preamplifier 47 and amplifier is cut off.

In the message tape unit 5 the "writeenable" signal is applied to the control terminal o the audio amplifier A2, cutting off the amplifier and preventing the answering text transmitted by the unit 3 from being applied to the head H' via the transtormer TX. The "write-enable" signal is also applied to the motor drive circuit 29, causIng the circuit 29 to produce an output signal for energising the motor M2 and causing the tape 27 to be driven from the supply spool towards the take-up spool.The sets ot seven signals representing time. generated by the clock 7. converted to serial form bv the parallel-serial converter 37. modulated by the modulator 41 and amplified by the data amplifier 43. are now applied to the head H2 and recorded on the message tape 27, As indicated above. the four sets of sienals appear at the outputs of the clock 7 in sequence and they are therefore recorded sequentially on the tape 27. Moreover. the signals are continuously updated.

Recording of the time signals continues for ten seconds. At the end of this period the delay 17 operates to cut off the ""'rite- enable" signal. This switches the first input to the gate 19 to a logic 0 condition so that the output of the gate also assumes a logic 0 condition. the data amplifier 43 is switched off and the data preamplifier 47 is switched on. At the same time the motor drive circuit 29 is cut off. de-energising the motor M2 and ending movement of the tape 27. and the audio amplifier A2 is switched on.

When transmission of the answering text has been completed and the tape 31 in the unit 3 has been driven once round the loop the metal strip MS short circuits the contacts 25. This cuts off the power signal from the motor control circuit 23. therebv de energizing the motor N11 and switching off the amplifier Al. and causes an "end announcement. start message" signal to be applied to the message tape unit 5.

The "end announcement, start message" signal is applied directlv to the first input of the memorv 31 in the unit 5 and to the timer 33. 'Ihe memorv 31 produces an output signal which actuates the motor drive circuit 29. A power signal is therefore produced at the output of the circuit 29, the motor M2 is energized and the tape 27 is driven from the supplv spool towards the take-up spool. An incoming mess age from the caller is then transmitted from the line LI, L2 to the head H2. via the line transformer TX and the amplifier A'. and the message is recorded on the tape 27.

I hirtv seconds after commencement of the "end announcement. start message signal the timer 33 operates and applies a signal to the second input to the memory 31.

This cuts off the output signal from the memory 31 so that the power signal at the output of the motor drive circuit 29 is terminated and the motor M2 is de cnereised.

The output signal from the timer 33 is fed to the detector 15 in the interface l and causes the output to be removed from the relay winding RL. The contacts RL1 and RL' are then opened and the machine is in a condition suitable for receiving a further incoming call.

To play back a recorded message the subscriber first operates the switch 35 so that the seven inputs to the display 13 are disconnected from the clock 7 and connected instead to respective outputs of the memory 4t). Next he operates the rewind control on the message tape unit 5 so that the tape 27 is rewound on to the supply spool. Finally. the plav back control is operated. This actuates the motor drive circuit 79 so that the motor M2 is energised to drive the tape '7 forwardly.

As the tape is driven forwardly, the recorded signals representing the time at which the first incoming message was received are reproduced first, These signals are amplified by the preamplifier 47 and demodulated bv the demodulator 45, which produces binary signals in the form of pulses of shape corresponding to the envelope of the hursts of oscillations recorded on the tape '7. Aftcr conversion to parallel form in the serial-parallel converter 3(). the binarv signals are applied to the memorv device.

As described above, four sets of binary signals are used to represent the time at anv instant. The information represented by each of these sets is stored in a respective one of the four sections in the memory device 40 and the sections are strobed so that sets of binary signals, each set representing information from one of the sections, appear at the outputs of the device 4() in sequence. From the device 4í) the sets of binary signals are applied to the display 13.

where the four seven-segment display cle- ments in the display 13 are energized to provide a visual indication of the time. The time recorded on the tape 27 is up-dated during the ten seconds of the "write-enable" signal, as mentioned above. and the time displayed on the display 13 is up-dated accordingly. The memorv device 4() ensures that the time recorded immediatelv before the end of the "write-enable" signal remains displayed on the display 13 throughout the subsequent playback of the first message.

It will be appreciated that the filter 51 is designed to prevent the bursts of 4K Hz oscillations from producing an unwanted audio signal in the speaker 55 At the end of the ten seconds devoted to playing back recorded time signals the first message recorded on the tape 27 is reproduced by the head H2 and is applied vi' the filter 51 and the audio amplifier 53 to the speaker 55.

Subsequent time signals and recorded messages are then reproduced in sequence.

In modifications of the machine shown in Figure 1 a coded signal representing the time of an incoming call is recorded on the message tape before the answering text is transmitted, after transmission of the text has been completed but before the incoming message is recorded. or even after the incoming message has been recorded and the caller has disconnected. A further embodiment of a machine according to the invention employs a single tape upon which answering texts and incoming messages are recorded.Again. a coded signal representing the time of each call is recorded before or after transmission of the answering text or after the caller has finished recording. In a further machine an incoming message is recorded on a first track of a tape. using a first head, whilst a coded signal representing time is recorded on a second track of the same tape. via a second head.

A further embodiment of a telephone answering machine according to the invention includes a decoder device and is qssoci- ated with a coder device for use in remotely controlling the machine. both coder and decoder devices bering of the form disclosed in our Specification No. l.523.2l.

Ihe present machine includes means for generating a coded electrical signal repre senting the time at which an incoming message is received and means for recording the coded signal on a tape. as described above in connection with Figure 1.

Refen'ing to Figure 2, the coder device includes an oscillator hl. means 63 for generating coded voltages for application to the oscillator 61, and an electrical audio transducer í h5 coupled to the output of the oscillator. l'he coded voltages from the generating means 63 cause the oscillator to generate coded electrical access and command signals which are converted into audio signals by the transducer 65. These audio signals are sensed by the caller's handset 67.

converted into electrical signals, and transmitted to the machine via the telephone line LI, L2. In the telephone answering machine the decoder device decodes the access and command signals received from the coder device and generates signals which cause the appropriate operations to be performed by the machine.

When the caller operates the remote control device of Figure 7 so that a "playback" command signal is transmitted, the decoder device in the telephone answering machine generates a control signal which causes the machine to play back information recorded on a message tape in the machine.

Included in this information are recorded messages. which are transmitted to the handset 67 via the line LI. L2 and are heard by the caller in the usual manner. Additionally. coded signals representing time are transmitted via the line LI . L2 and reproduced bv the handset 67 is short bursts of audio frequencies.

The speaker 65, used in transmitting access and command signals is also used as a microphone for detecting the audio frequencies from the handset. A data preamplifier 6') couples the speaker 65 to a demodulator 71 and the demodulator in turn is coupled via a serial-parallel converter 73 to a display unit 75.

the data preamplifier 69 amplifies the signils from the speaker 65 and the ampli fied signals are then demodulated in the demodulator 71. converted from serial to parallel form by the converter 73 and applied to the display unit 75. In the result, a visual display of the time is provided on the unit 75 whilst the incoming message received at that time is being reproduced by the handset 67.

WHA'I WE CLAIM IS: I . A telephone answering machine com- prising sound recording and reproducing means. means tor generating coded electrical signals representative of the time. control means adapted. when the machine is con necied to a telephone line and a ringing

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

the serial-parallel converter 3(). the binarv signals are applied to the memorv device.

As described above, four sets of binary signals are used to represent the time at anv instant. The information represented by each of these sets is stored in a respective one of the four sections in the memory device 40 and the sections are strobed so that sets of binary signals, each set representing information from one of the sections, appear at the outputs of the device 4() in sequence. From the device 4í) the sets of binary signals are applied to the display 13.

where the four seven-segment display cle- ments in the display 13 are energized to provide a visual indication of the time. The time recorded on the tape 27 is up-dated during the ten seconds of the "write-enable" signal, as mentioned above. and the time displayed on the display 13 is up-dated accordingly. The memorv device 4() ensures that the time recorded immediatelv before the end of the "write-enable" signal remains displayed on the display 13 throughout the subsequent playback of the first message.

It will be appreciated that the filter 51 is designed to prevent the bursts of 4K Hz oscillations from producing an unwanted audio signal in the speaker 55 At the end of the ten seconds devoted to playing back recorded time signals the first message recorded on the tape 27 is reproduced by the head H2 and is applied vi' the filter 51 and the audio amplifier 53 to the speaker 55.

Subsequent time signals and recorded messages are then reproduced in sequence.

In modifications of the machine shown in Figure 1 a coded signal representing the time of an incoming call is recorded on the message tape before the answering text is transmitted, after transmission of the text has been completed but before the incoming message is recorded. or even after the incoming message has been recorded and the caller has disconnected. A further embodiment of a machine according to the invention employs a single tape upon which answering texts and incoming messages are recorded.Again. a coded signal representing the time of each call is recorded before or after transmission of the answering text or after the caller has finished recording. In a further machine an incoming message is recorded on a first track of a tape. using a first head, whilst a coded signal representing time is recorded on a second track of the same tape. via a second head.

A further embodiment of a telephone answering machine according to the invention includes a decoder device and is qssoci- ated with a coder device for use in remotely controlling the machine. both coder and decoder devices bering of the form disclosed in our Specification No. l.523.2l.

Ihe present machine includes means for generating a coded electrical signal repre senting the time at which an incoming message is received and means for recording the coded signal on a tape. as described above in connection with Figure 1.

Refen'ing to Figure 2, the coder device includes an oscillator hl. means 63 for generating coded voltages for application to the oscillator 61, and an electrical audio transducer í h5 coupled to the output of the oscillator. l'he coded voltages from the generating means 63 cause the oscillator to generate coded electrical access and command signals which are converted into audio signals by the transducer 65. These audio signals are sensed by the caller's handset 67.

converted into electrical signals, and transmitted to the machine via the telephone line LI, L2. In the telephone answering machine the decoder device decodes the access and command signals received from the coder device and generates signals which cause the appropriate operations to be performed by the machine.

When the caller operates the remote control device of Figure 7 so that a "playback" command signal is transmitted, the decoder device in the telephone answering machine generates a control signal which causes the machine to play back information recorded on a message tape in the machine.

Included in this information are recorded messages. which are transmitted to the handset 67 via the line LI. L2 and are heard by the caller in the usual manner. Additionally. coded signals representing time are transmitted via the line LI . L2 and reproduced bv the handset 67 is short bursts of audio frequencies.

The speaker 65, used in transmitting access and command signals is also used as a microphone for detecting the audio frequencies from the handset. A data preamplifier 6') couples the speaker 65 to a demodulator 71 and the demodulator in turn is coupled via a serial-parallel converter 73 to a display unit 75.

the data preamplifier 69 amplifies the signils from the speaker 65 and the ampli fied signals are then demodulated in the demodulator 71. converted from serial to parallel form by the converter 73 and applied to the display unit 75. In the result, a visual display of the time is provided on the unit 75 whilst the incoming message received at that time is being reproduced by the handset 67.

WHA'I WE CLAIM IS: I . A telephone answering machine com- prising sound recording and reproducing means. means tor generating coded electrical signals representative of the time. control means adapted. when the machine is con necied to a telephone line and a ringing

signal is applied to the line from a remote caller, to actuate the sound recording and reproducing means and the generating means in a predetermined sequence so that a recorded answering text is transmitted to the caller via the line and an incoming message from the caller and a coded electrical signal representing the time at which the incoming message was received are recorded on a sound recording medium.

further control means for actuating the sound recording and reproducing means so that the recorded message and the recorded coded electrical signal are reproduced. and means for applving the coded electrical signal to a display unit which provides a visual display of the time represented by the coded electrical signal.

2. A telephone answering machine as claimed in claim 1. wherein the sound recording and reproducing means comprise first sound recording and reproduced means for reproducing the answering text from a first sound recording medium and second sound recording and reproducing means for recording the incoming message and the coded electrical signal on a second sound recording medium. and the control means are adapted to actuate the second sound recording and reproducing means so that the coded electrical signal is recorded on the second sound recording medium whilst the answering text is beine repro duced from the first sound recordng medium and transmitted to the caller.

3. A telephone answering machine as claimed in claim 2. wherein the control means are adapted to actuate the second sound recording means for a predetermined interval of time which is less than the time taken for reproduction and transmission of the answering text.

4. A telephone answering machine as claimed in claim 1. wherein the control means are adapted to actuate the sound recording and reproducing means so that the coded electrical signal is recorded before the answering text is transmitted to the caller.

5. A telephone answering machine as claimed in anv one of claims 2 to A. wherein the means for applying the coded electrical signal to the display unit include a memory device which serves to maintain a display ot the time represented bV the coded electrical signal on the unit whilst the recorded message is bering reproduced.

6. A telephone answering machine as claimed in claim 1. wherein the control means are adapted to actuate the sound recording and reproducine means so that the coded electrical signal is recorded after the incoming message has been recorded.

7. A telephone answering machine as claimed in claim 1. wherein the sound recording and repn)ducing means comprise a first sound recording and reproducing means for recording an incoming message on a first track of a sound recording medium. and a second sound recording and reprc,ducinr means for recording the coded electrical signal on a second track of the said sound recording medium. and the control means are adapted to actuate the first and second sound recording and reproducing meons so that the coded electrical signal is recorded on the said sound recording medium whilst the incoming message is being recorded.

S. A telephone answering machine as claimed in any one of the preceding claims.

wherein the generating means comprise means for generating a carrier signal coded to represent the time at which the incoming signal was received. and means for modulating the coded carrier signal. and the means for 'applying the coded electrical signal to the display unit comprise means for demod latin' the modulated signal reproduced from the sound recording medium.

9. A telephone answering machine as claimed in claim 8. wherein the modulating means are adapted to modulate the carrier signal with electrical oscillations at an audio frequency. and the sound recording and repn)ducing means include an electro-audio transducer for reprodueillg the incoming message and filter means adapted to effect a substantial reduction in the amplitude of oscillations at the said audio frequency applied to the transducer.

lo. A telephone answering machine as claimed in any one of the preceding claims.

wherein the generating means are adapted to generate a parallel coded signal and means are provided for converting the parallel coded signal to a serial coded signal prior to recording on the sound recording medium. and the means for applying the 1 coded electrical signal to the display unit include means for convelting the recorded serial coded signal into a parallel coded si9nal.

I I. A telephone answering machine as claimed in any one of the preceding claims.

N herein the display unit comprises a plural itv of seven-segment display elements. and the coded electrical signals comprise a plureality ot sets of signals. each set comprising seven bits of information.

12. A telephone answering machine as claimed in any one ot the preceding claims in combination with a device for remotely contlollinçg the machine. the remote control device comprising means for generating an audio trigger signal for application to the machine via a handset connected to a telephone line. therebv to cause the machine to reproduce the coded electrical signal and to prOdUCe a further electrical signal representing the recorded message and to transmit the coded electrical signal and the further electrical signal to the handset via the line. the handset converting the coded electrical signal and the further electrical signal into audio signals, an audio electrical transducer for re-converting the audio signal derived from the coded clcctrical signal back into a coded electrical signal.

a display device, and means for applying the re-converted coded electrical signal to the display device. wherebv the display device provides a visual display of the time represented by the coded electrical signal.

13. A telephone answering machine constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in. the accompanying drawings.