EP0691051A1

EP0691051A1 - Mobile communications equipment

Info

Publication number: EP0691051A1
Application number: EP94908477A
Authority: EP
Inventors: Edmond Levi; Rudolf Schaffer
Original assignee: PROFINOR SA
Current assignee: PROFINOR SA
Priority date: 1993-03-16
Filing date: 1994-03-15
Publication date: 1996-01-10
Also published as: CA2158481A1; JPH08508147A; WO1994022234A1; FI954349A; FI954349A0; AU6155894A

Abstract

Telecommunications equipment comprising a portable telephone (1) provided with an antenna and a battery, and mechanically and electronically connected via a single lead (2) to a 'hands free' device (3) and a cigar-lighter power outlet (4). The 'hands-free' device is housed partly in a connector (5) and partly in a housing (3) arranged between the portable phone (1) and the cigar-lighter power outlet (4).

Description

Mobile Communication Equipment

The subject of the present invention is telecommunications equipment and more particularly a pocket telephone which can be carried on board a vehicle.

Many world-renowned manufacturers manufacture and sell all kinds of portable or mobile telephones, all of which have specific advantages but none of which can meet all of the usage situations faced by a user in all of his needs.

Indeed, there are so-called "portable" telephones which are light in weight, compact and therefore easily transportable, but whose autonomy is relatively small and above all which cannot be used when driving a motor car. because we do not know where to fix them in the car, their autonomy, as indicated above, is too weak for long-term use without recharging or changing batteries and above all they are not equipped with a "hands-free" system , that is to say a microphone and a loudspeaker allowing a motorist to drive his car during a telephone conversation without holding one hand said mobile phone. If this is still tolerated at present, it will soon not be the same for obvious safety reasons, the driver already having to concentrate on the content of his telephone conversation cannot yet drive his vehicle carefully and safely if he has only one hand left, the other being necessarily mobilized by holding the portable telephone. The lack of a hands-free system is also a drawback when the equipment is used outside of a car and several people have to take part in the conversation.

There are also automobile car telephones which are permanently installed in a conventional car and which generally have a "hands-free" system. These devices require a fixed installation in the car and therefore cannot be used as mobile phones; these are ultimately fixed telephones assigned to a rolling vehicle. These phones require installation work in the vehicle.

Finally, there are still portable telephone sets which can be used everywhere. They are very bulky, have sufficient autonomy, but are heavy due to the large batteries, most of which do not have a "hands-free" system so that they cannot be used for conferences. to several people and their use by car is problematic, especially since nothing is planned to keep them in place and they are therefore likely to be overturned due to bumps in the road , turns, etc. These devices the size of a small briefcase are bulky and heavy and therefore less and less used if not as a telephone for a second home or as a second "fixed" telephone.

The subject of the present invention is telecommunications equipment and more particularly a telephone for pocket that can be used as a car and conference phone.

It includes an accessory weighing less than 120 grams capable of instantly converting a pocket radio telephone into a "hands-free" car telephone or, just as instantly, transforming the pocket radio radio into an indoor telephone , also "hands-free" for telephoning while taking care of it manually or for holding a teleconference between two working groups distant from each other.

Several unsuccessful attempts have been made to try to add a pocket "handsfree" to a pocket radio telephone. These attempts all failed because they could not successfully miniaturize the hands-free while eliminating the feedback effect it causes.

The present equipment overcomes the drawbacks of the aforementioned devices and is defined by the characteristics of claim 1.

The accompanying drawing illustrates schematically and by way of example several possible embodiments of the telephone equipment according to the invention.

Figure 1 is a perspective of a first embodiment of the telephone equipment and a pocket phone.

FIG. 2 illustrates a block diagram of part of the "hands-free" circuit contained in the multi-function connector or in a support.

FIG. 3 is a block diagram of part of the electronic circuit of the "hands-free" device contained in a housing or support.

FIG. 4 illustrates in perspective a second embodiment of the telephone equipment according to the invention.

FIG. 5 illustrates in perspective a third embodiment of the telephone equipment according to the invention.

FIG. 6 is a block diagram of the electronic circuit contained in the support of the third embodiment illustrated in FIG. 5.

The pocket telecommunication equipment according to the present invention comprises a pocket telephone having a large autonomy, due to a rechargeable battery, comprising all the options offered by a device of this type of high technology. It can be a device of the "Natel C", "Telecom 2000" type or others provided with its antenna.

The present pocket telephone is particularly suitable for being carried on board a vehicle, for being used as a car telephone with “hands-free” equipment, without however requiring fixed installations in the vehicle. It is also particularly well suited to be used for conferences for several people also "without requiring fixed installations.

In the first embodiment illustrated in Figures 1 to 3, this pocket phone 1 is mechanically connected and electrically connected using a multi-function connector 5 and a single cable 2 to a box. ¬ "hands-free" tier 3 and to a low-voltage power outlet 4 generally of the "cigar lighter" type. The body of the "hands-free" device can be presented in particular in the form of a small box of 4 cm x 4 cm by 2 cm approximately, it comprises an electronic printed circuit adapted to the electronics of the pocket radio telephone. This circuit manages and distributes according to an established diagram, the signals between the various elements of the telephone, whose power levels go from 7 to 30 V. According to the possible variants, it has, inside or outside this housing, a system of "ambient audio" allowing to clearly hear its correspondent, when one is within sight of the telephonic apparatus.

The electric cable 2 comprises electrical conductors ensuring the connection between the "cigarette lighter" socket and the pocket telephone 1 for simultaneously supplying power and charging its built-in accumulator.

This electric cable 2 also includes the electrical connections necessary for the connection between the "hands-free" box 3 and the pocket telephone 1.

Finally, this electrical cable 2 simultaneously constitutes the mechanical support of the "hands-free" box 3. For this purpose, this "hands-free" box 3 is located near the "cigarette lighter" socket 4 and the electric cable 2 or at least its sheath in its portion connecting this socket 4 to the "hands-free" box is mechanically strong and relatively rigid. Thus, when the socket 4 is engaged in the "cigarette lighter" socket of a vehicle, this section of rigid cable serves as a support and attachment to the "hands-free" box. On the other hand, the other part of the cable 2, connecting the "hands-free" box to the pocket telephone, is flexible and extensible, as is the custom for ensuring the maneuverability of the pocket telephone 1.

The end of the cable 2 is connected to the pocket telephone 1 using a plug-in connector 5. This connector 5 contains part of the “hands-free” electrical circuit of this equipment, illustrated in FIG. 2, and including in particular a microphone 6 and its associated circuit. When the connector 5 is connected to the pocket telephone apparatus 1, the microphone 6 is automatically put into service while that incorporated in the telephone apparatus is automatically put out of service.

This connector 5 is pluggable by means of connection pins a ... g in the pocket telephone 1 and is connected by the multi-wire cable 2b to the housing 3. The switch S makes it possible to choose the commissioning of d '' an external antenna or the internal antenna of the device.

The pocket phone is also provided with a 'fixing member to be able to fix it on the surface of the dashboard of a vehicle or place it on a seat without it moving. This fixing member can be constituted by a suction cup fixed to the pocket telephone and making it possible to fix it by simple pressure on a smooth surface.

This fastening member can also be formed by a velvet band with hooks fixed to the pocket telephone 1 cooperating with a velvet band with hooks correspon¬ dante fixed where the user so desires. This second strip of velvet with hooks can be affixed to a heavy cous¬ sinet, loaded with shot for example, and one of which surface is non-slip. It is thus possible to "fix" the pocket telephone anywhere simply by placing the said pad and placing the telephone on it.

The assembly formed by the pocket telephone and its power cable comprising the connector, the "hands-free" box and the "cigarette lighter" socket is very compact. It can be stored in a very small volume kit. This would be true even if the user wishes to take with him also a charging and supply device via the network and a device for fixing the telephone, suction cup or pad.

We thus realized the least bulky universal pocket phone.

Thus, this equipment, particularly intended to be taken on board a vehicle without requiring a fixed mon¬ tage, nevertheless allows the use of the pocket telephone alone outside the vehicle.

It is also planned to add to this equipment a 220V / 12V power transformer-rectifier fitted with an electric cord for connection to the 220 Volt sector and a socket identical to a vehicle cigarette lighter.

The user can thus, other than in his vehicle, power his pocket phone 1 and recharge his battery using the power supply unit via this transformer. This pocket phone can therefore be used as a telephone with surround speakers for conferences with several users. It is thus possible to have a "hands-free" telephone with ambient speakers both in the car and in the bathroom. conference or at home.

This device therefore meets all the requirements of a car telephone combined with a pocket telephone with ambient speakers, and does not have any of the drawbacks of existing devices.

This is notably obtained by the physical separation of the loudspeaker HP from the "hands-free" box 3 and from the microphone 6 of the connector 5 and their associated anti-feedback circuits replacing the microphone and the loudspeaker of the telephone 1 itself. even when connected to this equipment.

It can be used both as a car station or as a pocket phone without requiring any particular installation for any of its uses. The device which weighs only 120 grams is infinitely lighter and of course much less bulky than a mobile phone, while retaining all the faculties and all the ease of use. When the pocket telephone is detached from the “hands-free” device in question, it will regain its original weight, will preserve the integrity of its functions and all its mobility as a pocket telephone; in a car it does not require any fixed installation on the vehicle, has a "hands-free" system and special anti-feedback circuits, and has a simple and original holding or fixing device, for example a suction cup or a pad. In addition, it can be powered by the "cigarette lighter" socket of a vehicle simultaneously ensuring the charging of the accumulator, so that the total capacity of the rechargeable battery of the pocket telephone is always available. when used separately. When used in a conference room, it can be connected to the 220V network via an auxiliary transformer.

For the individual user, this equipment also has the advantage of being able to be acquired in any store, retailer, large area, etc. since it requires no assembly and is immediately ready for use as soon as a call number is assigned to it by the competent administration, which could even be done in the future at moment of purchase.

In the case of car rental companies, with fleets of several thousand units, this device is even more advantageous. It is out of the question for these companies to equip all their cars with the "hands-free" system or even telephones, so the customer can only rent a very expensive luxury car equipped with a telephone, if it is still available.

With the equipment offered by this invention (pocket radio phone + pocket hands-free), it rented separately regardless of the rental of the car, will be instantly placed in the luxury car or utility vehicle chosen by the customer.

1. A complete "hands-free" telephone system, which it will connect to the "cigar-lighter" power supply of the car to immediately have the free disposal of a global telephone network, clear and tidy, without any cost d 'installation, nor purchase of additional accessories. 2. He could instantly, without the help of a technician, change cars and continue to use his telephone just as safely in another car, or anywhere outside his car.

3. If he plans to travel on foot, by train, taxi or boat, he will take his pocket phone, possibly with an additional battery in his luggage, and a small conventional power socket to recharge them in time to other.

4. Finally, the range that a car rental company can offer to its customers will be very wide and free because it will give them the possibility of choosing any car in the fleet, and nevertheless of having mobile phone without the cars being equipped with any fixed equipment. For a car rental company, this advantage would translate into savings of around 80% of the cost of installing and equipping a standard "fixed hands-free" system. in each vehicle.

5. The user can also, by connecting the pocket telephone to the 220V network using the auxiliary transformer, have a telephone with ambient speakers in any office or local.

In the embodiment illustrated in Figures 1 to 3, the assembly constituting the portable telecommunication equipment consists of a pocket telephone 1 and a low-voltage and "hands-free" power supply device. This low-voltage and "hands-free" power supply device comprises a "cigar-lighter" plug 4 intended to be connected to a low-voltage power outlet, a "hands-free" device 3 and an electrical cable. ¬ plate 2 connecting on the one hand the pocket telephone 1 to the "hands-free" box 3 via the multi-function connector 5 containing the "hands-free" microphone and its associated circuit and on the other hand this box "hands-free" 3 to the low-voltage power plug 4. This electric cable comprises a first relatively rigid and short part 2a between the plug 4 and the "hands-free" box 3 and a second flexible, extensible and re ¬ long long 2b between the "hands-free" device 3 and the connector 5.

This set allows the user of a pocket radio phone to converse without having to place the mono-block handset against his ear. The user can leave the handset on its support as long as it is within direct sight of his mouth.

This was made possible thanks to the use of a sophisticated electronic circuit comprising several high quality filters and various low noise amplifier circuits, the whole being connected to a specific speaker and microphone, housed respectively in the housing 3 and connector 5. Although miniaturi¬ se, the device could be produced without any trace of Larsen effect, in order to obtain a clear and clear communication, in both directions in 100% duplex.

FIG. 2 illustrates this electronic circuit housed in the housing 3 which comprises two stages of amplifiers here making use of integrated amplifiers U1 and U2 of type 082, the BFIN input of which receives the low frequency signals coming from the pocket telephone 1. The output of this chain of amplifiers feeds via an adjustable potentiometer P1 a filtering circuit comprising in particular an integrated circuit U3 of the MC 34019 type supplying the loudspeaker HP. This electronic circuit makes it possible to avoid and eliminate any snagging or interference between the loudspeaker and the microphone incorporated in the connector 5.

In addition, a low voltage power supply is integrated so that the pocket telephone can also be supplied when it is connected to the "hands-free" device, thereby reducing the number of connections required for the use of a multi-function connector. 5 between the part 2b of the electric cable 2 and the pocket telephone 1. This supply simultaneously allows the supply of the electronic circuit of the "hands-free" and the recharging of the accumulators of the pocket radio-telephone 1 so that it is always ready for use without an external power source.

This low voltage power supply is connected to the "cigarette lighter" plug by two conductors V BAT IN and the earth and delivers a first voltage + V for supplying the pocket telephone and the integrated circuit U3. as well as a second voltage + V / 2 supplying the "hands-free" electronic circuit.

This embodiment allows, as can be seen, to limit the number of electrical conductors in the cable 2 to two conductors in part 2a and three in part 2b of this cable 2.

The entire "hands-free" and power supply electronic circuit as well as the loudspeaker are housed in a small, rigid housing.

In the example illustrated, a multi-function connector 5 allows the connection of the “hands-free” and power supply device 2,3,4 to the pocket telephone 1 and incorporates the microphone and its associated circuit.

In summary, the "hands-free" equipment proposed comprises: a) a molded connector, which is perfectly suited to a mobile cellular telephone. This contains an anti-feedback circuit, a pre-amplifier and filters. There is also incorporated a microphone suspended in a mem¬ brane of injected silicone, specially designed to stop the transmission of vibrations which without this device would result in buzzing noise. b) a compact molded box, containing a "system management" printed circuit, a "fast recharge" circuit (from 0 to 90% in 1 hour), a loudspeaker with its amplifier and a potentiometer adjustable by means of a small toothed wheel, protruding by 2mm, one side of the box. c) a car cigarette lighter connector. d) a light spiral cable which leaves part 5, passes through part 3 and ends in part 4.

FIG. 4 illustrates a second embodiment of the telecommunications equipment according to the invention. In this version, even more compact and easier to use than the first, the mobile phone or pocket phone 1 is pluggable into a support 10 which can be fixed to any element or wall of a dashboard of a vehicle for example by an adhesive tape, self-adhesive, or a strip of velvet with hooks. This support 10 comprises in its lower part a connector corresponding to that of the radio telephone and allowing it to be plugged in for its operation, its power supply and the recharging of its own batteries or rechargeable batteries by the cigarette lighter socket of a vehicle. The lower part of this support 10 comprises, like the connector 5 of the first embodiment, a microphone 11 which, when the radio telephone is plugged in, is automatically activated while that incorporated in the pocket phone is put out of service.

The upper part of the support 10 includes the speaker 12 which in the first embodiment was placed in the housing 3.

Electronic charging and anti-feedback circuits similar to those illustrated in FIGS. 2 and 3 are in this embodiment incorporated, molded or embedded in the mass forming the support 10.

A spiral cord 13 connects the support, its electronic circuits, the connector, the microphone 11 and the loudspeaker to a cigar-lighter plug 14.

This second embodiment is even more practical for the user because the support 10 can be permanently fixed, removably or not, in a vehicle, plugged into the cigarette lighter and the user has more than plugging his pocket phone into the holder when get into his car.

Thus, in this second more compact and easy to use embodiment, the equipment notably includes a microphone, an anti-feedback circuit, an amplifier and a rapid charger for accumulator (from 0 to 90% in 1h) housed in a support. This system allows a harmonious proximity of the loudspeaker with the microphone, which favors the miniaturization of the system while avoiding any Larsen effect. The molded support in one piece contains the system and measures at most 15 x 6.5 x 4 cm and depending on the model may be further reduced. It will be connected to the cigar light by means of a continuous spiral cord. Its total weight is around 200 grs (with its spiral cord and its connector connecting it to the car cigarette lighter). In each of the different versions required, the equipment is also perfectly compatible with the most recent handheld mobile handsets.

This equipment eliminates nuisance noise, feedback, whistling, snoring and other background noise, it transmits and reproduces, simply and faithfully, to the same qualitative degree, all the sounds that are received or emitted by the cellular telephone to which it is connected.

The third embodiment illustrated in FIGS. 5 and 6 of the telecommunications equipment which is the most sophisticated and the preferred solution comprises a mobile telephone 20 pluggable into a support 21 connected by an extensible wire 22 to a plug 23, here a cigarette lighter plug, making it possible to connect it electrically to a source of electrical energy either directly, in the case of the use of a cigarette lighter socket of a vehicle cule, or via a transformer in the case of a connection to the electrical distribution network.

The support 21 may include fixing means for fixing it on the dashboard of a vehicle or on a conference table. It comprises the usual electrical connections or contacts, cooperating with those of the plug-in mobile telephone 20 to ensure the charging functions of the battery of the mobile telephone 20 and to switch off the speaker and the microphone incorporated in the mobile telephone by replacing them with a speaker 24 and two microphones 25, 26 mounted in said support 21, when the mobile telephone 20 is plugged into support 21

The geometric and / or spatial arrangement of the microphones 25, 26 with respect to the loudspeaker 24 is very important. A symmetrical arrangement is essential assu¬ rant a transmission of sound signals from the speaker 24 to each microphone with a practically equal intensity.

The microphones 25, 26 are moreover arranged or shaped so as to perceive the ambient noises in a directive or selective manner, the microphone 25 being much more sensitive to the sounds coming from the left of the support while the microphone 26 is much more sensitive to sounds coming from the right of support 21.

The electronic circuit of this third embodiment is illustrated diagrammatically in FIG. 6.

The two microphones 25,26 are connected to the terminals M1 +, M1- and M2 +, M2- while the terminals FL3, FL4, FL6, Bat + and Bat- are connected to the contacts of the support 21 intended to cooperate with the contacts of the mobile telephone 20 when the latter is plugged into the support 21.

We see that the signals from microphones 25,26 are delivered to the inputs of a differential amplifier IC4A, L 833N, the output signal of which corresponds to the difference of the signals delivered by microphones 25,26.

Thus when these microphones 25, 26 are requested by the loudspeaker 24, their output signals are practically canceled out since they are arranged symmetrically with respect to this loudspeaker 24. On the other hand, when they deliver signals from of the user of the telephone, which is never centered on the support 21, the difference between the signals of the microphones 25, 26 gives a signal of sufficient value for the operation of the telephone equipment.

Thus, by the symmetrical arrangement of two microphones relative to the loudspeaker and the use of a differential amplifier, all of the problems of hooking and Larsen effect have been practically eliminated in a simple, elegant and effective manner.

The operation of this third embodiment is as follows:

When inserting the mobile telephone 20 into the support 21, a switching provided for this purpose causes the loudspeaker 24 and the external microphones 25,26 to be put into service. A fast charger is also put into service and thus allows charging of the battery incorporated in the mobile phone if necessary. Electronic circuits adapt the ne- the correct functioning of said electronics. To facilitate the description of the device, three main parts must be considered:

1. Reception circuit of the correspondent:

The signal supplied by the mobile telephone 20 corresponding to the message being received is brought by appropriate connections to the circuit IC5 which is an important component. The main function of this element is to prevent the loop comprising the microphones of the device, the signal transmission circuit of the user, the receiving circuit of the correspondent as well as his speaker, then the microphone of this same cor- respodnant and all the circuits up to the loudspeaker of the user of the device, do not enter into oscillation (ac¬ hooking or Larsen effect) when the overall gain of the described loop will have a sufficient value. After a treatment, and after an amplification carried out by the circuit IC3, this signal is used to actuate the loudspeaker HP which will provide sufficient acoustic power for the desired purpose.

2. Signal processing circuit:

In order to be able to describe the operation of this circuit, it must be considered that the device can be in a given instant in one of the following three states: a) transmission (the user speaks) b) reception (the correspondent speaks) c) standby (neither the correspondent nor the user speak)

Each of these states will correspond to certain internal conditions in the processing circuit. To simplify, the amplification of the microphones will be at the maximum during the transmission state; to this maximum gain "microphones" will correspond a minimum amplification "loudspeaker" for the signal of the correspondent. Likewise, when the device is in the reception state, the amplification of the correspondent's signal will be at most up to the loudspeaker and this maximum "loudspeaker" gain will correspond to a minimum amplification of the signal " user microphones. In the standby state, intermediate amplification levels are defined, always with the aim of not having a snag or feedback effect.

The use of two microphones, mounted symmetrically with respect to the loudspeaker as well as with respect to the front face of the device, brings several advantages in the context of this use:

1) The acoustic signals transmitted by the loudspeaker will be picked up in a substantially identical manner by each microphone. A differential preamplifier makes it possible to attenuate, or even eliminate, the common component originating from the loudspeaker, hence a very significant reduction in the signal which would have been the cause, inter alia, of a catch. 2) A certain attenuation of the ambient noise is also obtained in this way.

3) Due to the position of the microphones, use by the front passengers will be perfect.

4) The equipment can be used indifferently for a vehicle with left or right-hand drive and this without modification.

Claims

1. Telecommunication equipment, characterized in that it consists of an assembly comprising a pocket radio telephone and a power supply and "hands-free" device for this pocket radio telephone; this device comprises an electric cable connecting both mechanically and electrically the "hands-free" device on the one hand to a low-voltage power plug and on the other hand to the pocket telephone.

2. Equipment according to claim 1, characterized in that the power plug is of the "cigar lighter" type.

3. Equipment according to claim 1 or claim 2, characterized in that the electric cable is connected to the pocket telephone by a multi-function connector containing a microphone and its associated "hands-free" circuit.

4. Equipment according to one of the preceding claims, characterized in that it comprises a housing containing a loudspeaker and the associated "hands-free" electronic circuit as well as a supply circuit.

5. Equipment according to claim 4, characterized in that the electric cable comprises a first rigid part of short length mechanically connecting the plug to the box and electrically this plug to the power circuit housed in this box.

6. Equipment according to claim 5, characterized by the fact that the electric cable comprises a second flexible and extensible part connecting mechanically said box to the pocket telephone and electrically the "hands-free" and power supply electrical circuits. pocket phone.

7. Equipment according to claim 1, characterized by the fact that it comprises a fixing member constituted by a strip of velvet with hooks fixed on the pocket telephone cooperating with a strip "corresponding strip of velvet with cro¬ chets" fixed on a support.

8. Equipment according to claim 7, characterized in that the support is a heavy pad, filled with shot, one side of which is non-slip and another provided with said velvet band with corresponding hooks.

9. Equipment according to claim 8, characterized in that the bearing comprises a fixing member comprising a link provided with at least one suction cup.

10. Equipment according to one of the preceding claims, characterized in that it comprises a 220V / 12V transformer-rectifier provided with a cable for connection to an electrical distribution network and a standard socket. "cigar lighter" to which the low voltage power plug can be connected.

11. Equipment according to one of claims 1 or 2, ca¬ characterized by the fact that the electrical cable of the spi¬ rale type is connected to a support containing a multiple connector for plugging in the radio telephone, at least one microphone and a loudspeaker and the necessary feed and anti-feedback circuits.

12. Equipment according to claim 11, characterized in that the support comprises means making it possible to fix it removably or not on a surface, wall or part of a dashboard of a vehicle.

13. Equipment according to claim 11 or claim 12, characterized in that the plugging in of the radio telephone causes the deactivation of its loudspeaker and its own microphone and the putting into service of the loudspeaker and at least one auxiliary microphone mounted in the holder.

14. Equipment according to one of claims 11 to 13, ca¬ characterized in that the support comprises a speaker and two microphones arranged symmetrically with respect to the speaker and with respect to the front face of the support.

15. Equipment according to claim 14, characterized in that the output signals from the microphones lie the inputs of a differential amplifier whose output signal is used as a "microphone" signal.

16. Equipment according to claim 15, characterized in that the microphones are directional.

17. Power supply device and "hands-free" for en¬ seems telecommunications according to one of the preceding claims, characterized in that it comprises an electric cable connecting both mechanically and electrically the device "hands- free "on the one hand to a low-voltage power plug and on the other hand to a multi-function switch connectable to a pocket telephone.

18. Device according to claim 17, characterized in that it comprises a housing containing the "hands-free" electronic circuit associated with a loudspeaker and the supply circuit.

19. Device according to claim 18, characterized in that the multi-function connector contains a microphone and its associated electrical circuit.

20. Device according to one of claims 17 to 19, ca¬ characterized by the fact that the electric cable comprises a first rigid part of short length mechanically connecting the plug to the housing and electrically this plug to the supply circuit housed in this box and a flexible and extensible second part mechanically connecting said box to the pocket telephone and electrically the "hands-free" electronics and power supply to the pocket phone.

21. Device according to one of claims 17 to 19, ca¬ characterized by the fact that when it is connected to a pocket tele¬ the microphone and the speaker integrated in this phone are switched off.

22. Device according to claim 14 or 21, caractéri¬ se in that the electric cable is spiral, that it has a cigarette lighter plug at one end and that it is connected at its other end mechanically to a sup¬ port and electrically to a connector, at least a micro¬ phone, a loudspeaker and appropriate supply and anti-feedback circuits all mounted or molded in the sup¬ port.

23. Device according to claim 22, characterized in that the microphones are arranged symmetrically with respect to the loudspeaker and to the front face of the support and by the fact that they supply the inputs of a differential amplifier .