Abstract:
A communications device for wireless communication with another device, the communications device having a) a first part having a first housing and a first induction coil for providing an inductive coupling to the other device, and b) a second part having a second induction coil adapted to be inductively coupled to said first induction coil and to said other device when mounted on or near said first housing. Provided is a relatively simple mechanical interface for an inductively coupled link between a communications device and another device. The second part is adapted to be detachably attachable to the first housing. An advantage is that no connector is needed whereby a simpler and more reliable device is provided. The consequences of wear of the connector leading to increased contact resistance and/or failure of the electrical connection is avoided.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a national stage application of PCT/EP2008/002878, filed on 11 Apr. 2008, which claims priority to EP 07105946.3, filed on 11 Apr. 2007, which hereby expressly incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The disclosure relates to a communications device for wireless communication with another device. An embodiment of the present disclosure relates to an intermediate antenna for wirelessly transmitting audio or data signals to a hearing aid. Embodiments of the disclosure may e.g. be useful in applications for the provision of an audio signal selected among a number of audio signals (e.g. including that of a mobile telephone) to a head-worn listening device, e.g. a hearing aid. 
       BACKGROUND ART 
       [0003]    The following account of the art relates to one of the areas of application of the present disclosure, the forwarding of audio signals to a hearing aid. 
         [0004]    Hearing aid systems demand increasing ability to communicate with accessories such as mobile phones, MP3 players, etc. Inductive communication (i.e. communication based on electromagnetic induction as opposed to electromagnetic radiation) between a hearing aid and a mobile telephone or a gateway device capable for converting these types of data in accordance with a standard or proprietary protocol has been proposed, cf. e.g. EP 1 480 492 A2. 
         [0005]    US 2006/0039577 discloses a system comprising a wireless transceiver for enabling a hearing assistance device to communicate with other wireless devices. The wireless transceiver comprises a neck loop integrated with an antenna adapted to communicate with the near field antenna of the hearing assistance device. The neck loop antenna is connected to the wireless transceiver by one or more jack connectors. 
         [0006]    EP 0 789 474 A2 discloses a hands-free arrangement for enabling communication between an earphone, e.g. a hearing aid, and a mobile communications device. The arrangement includes an induction loop to be worn around the neck, a microphone integrated with the induction loop and a cord with a connector which connects the microphone and induction loop to the mobile communication device. 
         [0007]    US 2004/240692 describes an adaptor for use with a mobile cellular telephone, to improve inductive communication from the coil of a speaker of the mobile to the telecoil of a hearing aid. 
         [0008]    US 2005/0244022 describes a removable bezel for use with an audio device, e.g. a mobile telephone, to enhance operation with a hearing aid. The removable bezel has an electromagnetic coil that is coupled to the audio output of the audio device. The electromagnetic coil is either inductively coupled to an acoustic transducer within the audio device or by a direct electrical connection. The electromagnetic coil provides an enhanced magnetic field to a telecoil within the hearing aids. 
       OBJECTS AND SUMMARY 
       [0009]    The problem of the art is that the solutions provided for inductively coupled links between a communications device (e.g. a mobile telephone) and another device (e.g. a hearing aid) are relatively complex and require mechanically vulnerable interfaces. 
         [0010]    An object of the present disclosure is to provide a relatively simple mechanical interface for an inductively coupled link between a communications device and another device. 
         [0011]    The objects of the disclosure are achieved by the inventions described in the accompanying claims and as described in the following. 
         [0012]    In an embodiment, the present disclosure relates to connecting an external antenna, such as a neck loop antenna for a hearing aid system, to a gateway device without the use of a wired connection in the form of an electro-mechanical connector or the like. 
         [0013]    An object of the disclosure is achieved by a communications device for wireless communication with another device, the communications device comprising 
         [0000]    a) a first part comprising a first housing and a first induction coil for providing an inductive coupling to the other device, and
 
b) a second part comprising a second induction coil adapted to be inductively coupled to said first induction coil and to said other device when mounted on or near said first housing. Advantageously, said second part is adapted to be detachably attachable to said first housing.
 
         [0014]    An advantage is that no connector is needed whereby a simpler and more reliable device is provided. The consequences of wear of the connector leading to increased contact resistance and/or failure of the electrical connection is avoided. The wirelessly connected external antenna may avoid some of the disadvantages of wired solutions such as
       Reliability issues of electromechanical connectors   Wear of the electromechanical connector       
 
         [0017]    Embodiments of the disclosure further provide:
       More free and simple mechanical design   Simpler electrical circuit   Galvanic separation       
 
         [0021]    The term ‘inductively coupled’ is in the present context taken to mean that the mutual induction between the two inductance coils in question is larger than 1% of the inductance of the coil having the smallest inductance of the two coils, such as larger than 5%, such as larger than 10%, such as larger than 20%, such as larger than 50%. In an embodiment, the coupling coefficient between the first and second induction coils is larger than 0.05, such as larger than 0.15, such as larger than 0.25. 
         [0022]    The first and second induction coils (each coil comprising an electrical conductor) are spaced apart, i.e. no part of a conductor of the first coil is in direct physical (and thus electrical) contact with a part of a conductor of the second coil). The term ‘near said housing’ is in the present context taken to mean less than 1 m from, such as less than 50 cm from, such as less than 20 cm from, such as less than 5 cm from, such as less than 1 cm from. In an embodiment, a wall of the housing of the first part and/or of the second part separate(s) the first and second coils. In an embodiment, the wall of the housing separating the first and second inductive coils is made of a material that is adapted to let the magnetic flux from the first induction coil through without substantial loss. In an embodiment, the wall material is an essentially dielectric material. In an embodiment, the wall material is a plastic material. 
         [0023]    The first and second parts are distinct separate parts that only cooperate electromagnetically via the inductive connection between them. No wired connections (or connectors) exist between the two parts. The first part is adapted to communicate directly (inductively) with the other device without involving the second part, in case of sufficient coupling between the first induction coil and the other device (comprising an appropriate antenna, e.g. an inductive coil). 
         [0024]    An advantage is that no connector is needed for the coupling between the first and second parts, whereby a simpler and more reliable device is provided. The consequences of wear of the connector leading to increased contact resistance and/or failure of the electrical connection is avoided. 
         [0025]    In an embodiment, the second part comprises a tuning circuit for adapting the second induction coil to a specific preferred frequency range. 
         [0026]    In an embodiment, the second part consists essentially of a second induction coil. In an embodiment, the second part consists essentially of a second induction coil and a safety release member (optionally comprising a tuning circuit). 
         [0027]    In an embodiment the first part is adapted to engage with the second induction coil (or the second part or an attachment member of the second part), e.g. via one or more grips or hooks or pinching profiles or the like protruding from or indented in and appropriately positioned on the housing of the first part and adapted to provide a good coupling between the first and the second coil, when the second coil (or the second part or an attachment member whereto the second coil is attached) is mounted in the grips or hooks or pinching profiles or the like (so that the second coil or part can be releasably mounted in the grips or hooks or pinching profiles or the like). 
         [0028]    In an embodiment, the first part comprises an attachment member for attaching the second part to the housing of the first part. 
         [0029]    In general the second part can be attached to the first part in any appropriate way leading to a reasonable coupling between the first and second coils and which provides a relatively easy attachment and detachment of the two parts. In an embodiment, the second part is attached to the first housing by a string or an elastic member e.g. an elastic tape or band. In an embodiment, the second part is attached to the first housing by tapes of cooperating hook and loop fasteners (such as e.g. Velcro™ tape) or some other means (e.g. elastic ‘click on’ members) allowing an easy attachment and detachment to be performed. 
         [0030]    In an embodiment, the second part comprises an attachment member to which at least a part of the second induction coil is attached (either fixed or detachable), the attachment member being detachably attachable to the first housing. Detachment (or release) can e.g. be dependent on an activator (such as a mechanical activator). In an embodiment, no activator is necessary to release the attachment member. In an embodiment, the attachment member is adapted to be ‘clicked on’ to the housing of the first part. In an embodiment, the attachment member and the housing of the first part comprises one or more protruding members on the one part (e.g. grips or hooks or pinching profiles) adapted to engage with one or more cooperating indentations on the other part. In an embodiment, the attachment member can be detached from the first part simply by twisting the attachment member relative to the housing of the first part. 
         [0031]    In an embodiment, the mutual induction between the first and second induction coils can be modified (i.e. is (reversibly) adjustable) whereby the quality of the inductive communication between the first part and the second part and thereby between the first part and the other device can be modified, e.g. optimized to a given situation. In an embodiment, this is simply achieved by changing the length (and/or the form) of the part of the second induction coil located near the housing (and thus the first induction coil) of the first part. In an embodiment, the second part (e.g. an attachment member thereof) can be slidably moved along the length of the housing of the first part, thereby modifying the amount of magnetic flux entering the second coil from the first coil and/or the ‘effective length’ of the neck strap constituted by the loop antenna. In an embodiment, the attachment member has several possible positions along the first part whereto it can be detachably attached. 
         [0032]    In an embodiment, the first part is part of a mobile telephone (specifically adapted), such as a DECT-telephone or such as a telephone connected to a switched telecommunications network, e.g. a GSM-telephone. 
         [0033]    In an embodiment, the first part is a portable communications device, such as an audio selection device in the form of a portable, body-worn communications device for wireless audio and data transmission to a head-worn listening device, e.g. a hearing aid. In an embodiment, the communications device comprises a microphone, e.g. for picking up the voice of a user of the other device, e.g. a hearing aid. In an embodiment, the microphone is located on the first part of the communications device. Alternatively, the microphone could be located on the second part, e.g. located on the second induction coil or on an attachment member. In an embodiment, the first part is adapted for communicating with other devices providing an audio input (wired or wirelessly, e.g. according to the BlueTooth standard), including with a mobile telephone. Examples of such devices are e.g. described in EP 1 460 769 A1 and WO 2006/117365 A1. 
         [0034]    In the present context, a hearing aid (also termed a hearing instrument) may be of any appropriate kind, such as an in-the-ear (ITE), such as an in-the-canal (ITC), such as a completely-in-canal (CIC), such as a behind-the-ear (BTE), or such as a receiver-in-the-ear (RITE) hearing aid. 
         [0035]    In an embodiment, the second induction coil is in the form of a closed loop comprising one or more turns, such as 1 or 2 or 3 or 4 or 5-10 or more than 10 turns. Increasing the number of turns has the advantage of increasing the magnetic field, whereby a more robust communication can be established. 
         [0036]    The first induction coil, which is the exciting coil providing (or rather relaying) the signal to be communicated to the other device, can in general be of any kind and size appropriate for the application (dimensions, frequency, etc.). The first induction coil is coupled to transmitter circuitry for generating the signal to be communicated to the other device. 
         [0037]    In an embodiment, the first induction coil is adapted, such as solely tailored, to communicate inductively with the other device. Preferably, the first induction coil and the transmitter circuitry to which it is connected is specifically adapted to communicate directly (inductively) with the other device (i.e. without involving the second induction coil). The adaptation relates to design properties such as the intended range of communication (power consumption), frequency range, dimensions, number of turns and orientation of the first induction coil relative to the other device when located in an operational condition. Typically, the only task of the first induction coil is (together with transmitter circuitry) to generate the magnetic field that forms basis of the inductive coupling to the other device directly or via the second inductive coil (i.e. the first inductive coil does not form part of another circuit or component, additionally having another purpose). 
         [0038]    In an embodiment, the first induction coil comprises a core of a (magnetically) soft magnetic material (such as a core comprising iron and/or nickel, e.g. an iron alloy or a ceramic material, such as a ferrite material). 
         [0039]    In an embodiment, the first coil is adapted for inductively transmitting an electrical signal (e.g. comprising an audio signal) to the other device. In an embodiment, the first and second coils are adapted to communicate with a near field antenna (e.g. a coil, optionally comprising a core of a magnetic material) of the other device. 
         [0040]    In an embodiment, the second part comprising the second induction coil is adapted to improve the signal quality of the inductive communication between the first part of the communications device and the other device. 
         [0041]    In an embodiment, the inductive coupling between the communications device and the other device is optimized to a predefined frequency range, e.g. by adapting the loop length, the number of turns, the values of a capacitor and/or a resistor of a resonance circuit formed by the coil, the capacitor and/or the resistor to provide a specific preferred frequency range for the inductive communication. Such optimization is preferably performed for each of the coil circuits of the involved devices (including the first and second coils and an antenna of the other device). The communication between the communications device and the other device may in principle be in any frequency range, e.g. in an audio frequency range (e.g. between DC and 20 kHz) or in the RF-range. In an embodiment, the communications device and the other device is adapted to inductive communication at audio frequencies (e.g. between 20 Hz and 8 kHz). In an embodiment, the preferred range is in the MHz-range (e.g. in the range between 1 MHz and 30 MHz or between 10 MHz and 100 MHz). In an embodiment, the tuning circuit is a parallel coupling of the induction coil and a resistor and/or a capacitor. In an embodiment, the second part comprises a tuning circuit for the second induction coil, the tuning circuit e.g. comprising a resistor and/or a capacitor. In an embodiment, the second part comprises a printed circuit board (PCB) whereon at least some of the tuning component(s), e.g. a resistor and/or a capacitor, of a tuning circuit for the second inductive coil is/are mounted. In an embodiment, the attachment member of the second part comprises the PCB with the tuning component(s). In an embodiment, the tuning circuit for the second induction coil comprises a capacitor of 68 pF, a resistor of 6.8 kΩ and an inductance comprising 4 turns of wire each of a length of 85 cm, providing a resonance frequency around 3.84 MHz. 
         [0042]    In an embodiment, the other device is adapted to be body-worn. In an embodiment, the other device is adapted to be head-worn. In an embodiment, the other device is a hearing aid or a head set or a pair of head phones. WO 2005/055654 and WO 2005/053179 describe various aspects of a hearing aid comprising an induction coil for inductive communication with other units. 
         [0043]    In an embodiment, the communications device is adapted to be body-worn. In an embodiment, the second coil (or at least a part of it) has the form of a neck strap adapted to be worn around the neck of a person. In an embodiment, the neck strap comprising the second coil is adapted to communicate with a hearing aid or another head-worn device. Thereby, the second part of the communications device serves the combined function of improving the communication between the communications device and the other device AND that of providing an arrangement for wearing the communications device on the body of a person. 
         [0044]    In an embodiment, the effective length of the second induction coil can be modified to adapt it to a particular size and constitution of a person wearing it. Thereby a microphone of the first part of the communications device can be positioned properly in relation to a wearers&#39; mouth, when the second induction coil is worn as a neck loop. Such regulation can be achieved by simply making a knot on the neck loop to adjust the length of the loop around the neck. Alternatively a regulation piece, e.g. a piece that closes off a part of the loop length and which can be moved along the loop to divide the loop in two parts one of which (the one to which the first part is attached) is taken over the head of the wearer. In an embodiment, an attachment member of the second part is adapted to allow such regulation of the length of the loop part that is to be hanged around the neck. 
         [0045]    In an embodiment, the second coil comprises a safety mechanism or unit adapted to break or release at a predefined tensile load (e.g. corresponding to a few kg load, e.g. 5 kg or 10 kg) to minimize damage to the wearer in case of an accident when the second coil is used as a neck strap. In an embodiment, the safety mechanism is recoverable in the sense that it can be joined again after a release. In an embodiment, the safety mechanism comprises two parts that are adapted to connectingly engage with each other and are adapted to break or release at a predefined tensile load, such as corresponding to a few kg of load. In an embodiment, the safety mechanism comprises a pair of cooperating electrical conductors, e.g. in the form of an electrical connector, connecting the two parts of the induction loop (the electrical connector e.g. being implemented as corresponding male and female connectors). In an embodiment, the safety mechanism comprises two parts adapted to separate at a predefined tensile load. In an embodiment the wires constituting the second coil comprise a section that is deliberately made mechanically weak and which break at a tensile load smaller than what is necessary for releasing or breaking the two parts of the safety mechanism. In an embodiment, the safety mechanism comprises a printed circuit board (PCB) whereon the wire(s) of the second antenna are formed over a short length, e.g. of the order of 1 or 2 cm or less, the PCB comprises a part that is mechanically weak, e.g. by being relatively narrow and adapted to break at a predefined tensile load. In an embodiment, the PCB of the safety mechanism contains electronic components (e.g. a resistor and/or a capacitor) for tuning the inductive circuit to a predefined frequency range. 
         [0046]    In an aspect, use of a communications device as described above, in the detailed description and in the claims is provided. 
         [0047]    In an aspect, a hearing aid system is provided, the system comprising a communications device as described above, in the detailed description and in the claims and another device, wherein the other device is adapted to communicate inductively with the communications device. In an embodiment, the other device is a head-worn listening device, such as a hearing aid (or a pair of hearing aids) or a head set or a pair of headphones. 
         [0048]    In an aspect, a second part of a communications device comprising a second induction coil adapted to be inductively coupled to a first induction coil of a first part of a communications device and to another device, when mounted on or near a first housing of the first part, is provided, wherein the second part is adapted to be detachably attachable to the first housing. 
         [0049]    In an embodiment, the second induction coil (or at least a part of it) has the form of a neck strap adapted to be worn around the neck of a person. In an embodiment, the neck strap comprising the second coil is adapted to communicate with another device in the form of a hearing aid or another head-worn device. Thereby, the second part serves the combined function of improving the communication between the communications device and the other device AND that of providing an arrangement for wearing the communications device on the body of a person. 
         [0050]    In an embodiment, the mutual induction between the first and second induction coils can be modified by modifying the length of the part of the second induction coil located near the housing of the first part, when the second part is mounted on the first part. In an embodiment, the communications device is adapted to allow an adjustable change of length of a part of the second induction coil intended for being worn around the neck, thereby facilitating the adjustment of the position of a microphone on the communications device relative to a wearer&#39;s mouth dependent upon the size of the person. 
         [0051]    In an embodiment, the other device is a head-worn listening device, such as a hearing aid (or a pair of hearing aids) or a head set or a pair of headphones. In an embodiment, the first part comprises a portable communications device, such as a mobile telephone, such as a DECT-telephone or such as a telephone connected to a switched telecommunications network, e.g. a GSM-telephone. In an embodiment, the first part comprises an audio selection device in the form of a portable, body-worn communications device for wireless audio and data transmission to another device in the form of a head-worn listening device, e.g. a hearing aid. 
         [0052]    In an aspect, a body-worn communications device adapted for inductively communicating with another device and comprising a first part and a second part as described above, in the detailed description and in the claims is furthermore provided. 
         [0053]    Further objects of the disclosure are achieved by the embodiments defined in the dependent claims and in the detailed description of the preferred embodiments. 
         [0054]    As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0055]    The disclosure will be explained more fully below in connection with a preferred embodiment and with reference to the drawings in which: 
           [0056]      FIG. 1  shows an embodiment of a body-worn hearing aid system according to the present disclosure,  FIG. 1   a  illustrating a situation where a first part of a communications device communicates inductively with a head-worn listening device, and  FIG. 1   b  illustrating a situation where a first part of a communications device communicates inductively with a head-worn listening device via an intermediate, second part of a communications device in the form of an inductance loop, 
           [0057]      FIG. 2  shows an embodiment of a communications device according to the disclosure,  FIG. 2   a  illustrating a second part of a communications device in the form of an inductance loop and an attachment member to which at least a part of the inductance loop is attached and  FIG. 2   b  illustrating a first part a communications device comprising a first induction coil with a ferrite core adapted for inductively communicating with another device, and  FIG. 2   c  illustrating the second part (cf.  FIG. 2   a ) mounted on the first part (cf.  FIG. 2   b ), 
           [0058]      FIG. 3  shows a first embodiment of a second part of a communications device according to the disclosure, 
           [0059]      FIG. 4  shows a second embodiment of a second part of a communications device according to the disclosure; 
           [0060]      FIG. 5  shows various embodiments of a second part of a communications device according to the disclosure providing loop length adjustment; 
           [0061]      FIG. 6  shows an embodiment of a second part of a communications device according to the disclosure comprising a pair of electrical connectors in the second induction coil; 
           [0062]      FIG. 7  shows an embodiment of a second part of a communications device according to the disclosure comprising a microphone; and 
           [0063]      FIG. 8  shows an embodiment of a first part of a communications device according to the disclosure comprising a microphone. 
       
    
    
       [0064]    The figures are schematic and simplified for clarity, and they just show details which are essential to the understanding of the disclosure, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts. 
         [0065]    Further scope of applicability of the present disclosure will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0066]      FIG. 1  shows an embodiment of a body-worn hearing aid system  10  according to the present disclosure.  FIG. 1   a  shows a first part  11  of a communications device worn on the body of a person  15 , inductively communicating  14  with a listening device  13  worn on the head  151  of the person  15 . The listening device  13  (here schematically shown as a hearing aid) comprises an induction coil  131  for inductive communication  14  with the first induction coil  112  of the first part  11  of the communications device, the first induction coil  112  being enclosed in the housing  111  of the first part  11 .  FIG. 1   b  shows a situation where the first part  11  of the communications device communicates inductively with the head-worn listening device  13  via an intermediate, second part  12  of a communications device in the form of an inductance loop  121  and an attachment member  122 .  FIG. 1   b  shows the same part as  FIG. 1   a , except that the inductive communication between coil  112  of the first part  11  and coil  131  of the other device  13  is adapted to be via the inductance loop  121  of the second part  12 . In other words, coil  112  of the first part  11  is inductively coupled  141  to inductance loop  121  of the second part  12 , which is inductively coupled  142  to coil  131  of the other device  13 . The communications device  11 ,  12  comprises first part  11  and second part  12 , where second part  12  is mounted on the housing  111  of the first part, here in that the attachment member  122  is detachably attached to the housing  111  in such a way that the second induction coil  121  is inductively coupled to the first induction coil  112  when the attachment member  122  is mounted on the housing  111 . The attachment member  122  can e.g. comprise a string or an elastic member, e.g. an elastic tape or band, or tapes of cooperating hook and loop fasteners. In the present embodiment, the ‘neck-loop antenna’  121  serves the combined function of improving the communication  141 ,  142  between the communications device  11 ,  12  and the other device  13  AND that of providing an arrangement for wearing the (first part  11  of) communications device on the body of the person  15 . 
         [0067]      FIG. 2  shows an embodiment of a communications device according to the disclosure.  FIG. 2   a  shows a second part  12  of a communications device in the form of an inductance loop  121  and an attachment member  122  to which at least a part of the inductance loop  121  is attached.  FIG. 2   b  shows a first part  11  of a communications device comprising a first induction coil  112  with a ferrite core  113  adapted for inductively communicating  14 ,  141  (cf.  FIG. 1 ) with another device (e.g. hearing aid  13  in  FIG. 1 ).  FIG. 2   c  shows the second part  12  (of  FIG. 2   a ) mounted on the first part  11  (of  FIG. 2   b ). The attachment member  122  of the second part  12  (to which the induction loop  121  is attached, e.g. fixed or alternatively detachably) is detachably attached to the housing  111  of the first part  11 . Attachment member  122  is further described in connection with  FIGS. 3 and 4  below. As schematically illustrated in  FIG. 2   c  the inductance loop  121  is (via the location of attachment member  122 ) positioned relative to the magnetic field  141  of first inductance coil  112  (amplified by a core  113  of a soft magnetic material) to provide an inductive coupling between the two coils  112 ,  121  (in that a substantial part of the magnetic flux lines from the first induction coil is enclosed by the second induction coil  121 ). 
         [0068]      FIG. 3  shows a first embodiment of a second part of a communications device according to the disclosure.  FIG. 3   a  shows a perspective view of an embodiment of an attachment member  122  comprising two protruding gripping members  1221  adapted to provide a detachable attachment to opposing sides of a housing of a first part of a communications device. The attachment member  122  further has inlet and outlet holes for induction loop  121  (induction loop only partly shown). The electrical conductor(s) of the induction loop  121  is/are routed in the attachment member to provide a good inductive coupling to a first induction coil, when the attachment member is attached to the housing of the first part of a communications device.  FIG. 3   b  shows a front view and  FIG. 3   c  shows a side view of the attachment member  122  (including a part of the induction coil  121  attached to the attachment member) with gripping members  1221 .  FIG. 3   d  is a top view of the attachment member  122  with gripping members  1221 . In this view, protrusions  1222  (here) located at each end of gripping members  1221  adapted to cooperate with corresponding indentations in (opposite sides of) a housing to allow a ‘click-on’ fastening of the attachment member to the housing (cf. housing  111  of first part  11  in  FIG. 3   j ) are visible. The construction allows the attachment member to be relatively easily twisted off the housing without damage to either of the attachment member or housing. In an embodiment, the attachment member (or at least the gripping members) is made of a plastic material having appropriate mechanical properties in respect of one or more of flexibility, rigidity, toughness, impact resistance, heat resistance and processing/production parameters. In an embodiment, the attachment member comprises PC/ABS (a PolyCarbonate, Acrylonitrile Butadiene Styrene “blend”). Preferably the geometries of the housing of the first part and the attachment member are adapted to each other, thereby creating a geometric lock between them. In an embodiment, the attachment member is resilient or comprises a resilient part. 
         [0069]      FIG. 3   e  shows an embodiment of the second part  12  of the communications device in full. The part of the induction loop  121  not covered by the attachment member  122  is visible. The induction loop comprises a safety member  123  adapted to provide that the loop breaks mechanically, in case of a tensile load larger than a predefined value, to avoid damage to a wearer of the induction loop in case the loop—by accident—is exposed to a large tensile force.  FIG. 3   f  shows a closer view of an embodiment of a safety member  123  comprising 2 parts (here halves)  1231 ,  1232 , here plastic parts enclosing the conductor(s) of the induction loop. In general, the electrical conductors of the induction loop  121  are embedded in a jacket of an electrically insulating material, e.g. a plastic material. Typically, an induction loop for being used as a neck strap has a length adapted to this purpose (child, grown up, large, medium, small, i.e. to ensure that it can be easily taken over the head of a person), e.g. having a length between 50 cm and 150 cm, e.g. in the range from 75 cm to 125 cm. In the safety member  123  (and/or possibly in the attachment member  122 ) the insulating jacket may be removed to weaken the tensile strength of the induction loop over a certain length of the loop (and/or to route the conductor(s) to a tuning circuit comprising electronic components).  FIG. 3   g  shows an embodiment of the safety member  123 , comprising two cooperating parts  1231 ,  1232 , each comprising two protruding members  12312 ,  12321 , adapted to releasably engage with corresponding indentations  12311 ,  12322  (protrusions  12312  of first safety part  1231  adapted to click into indentations  12322  of second safety part  12322  and protrusions  12321  of second safety part  1232  adapted to click into indentations  12311  of first safety part  1231 ). The top part of  FIG. 3   g  shows the full safety unit  123  (partially disengaged to illustrate the locking mechanism) and the bottom part focusing on the locking mechanism between the two parts of the safety unit  123 . The first and second parts  1231 ,  1232  of safety member  123  are adapted to disengage (without being damaged) at a predefined tensile load (e.g. larger than 5 kg or larger than 10 kg). Here the conductors of the induction loop are routed on a printed circuit board comprising a weak (narrow) section  1236 . Over a relatively small length, the PCB is weakened (here by routing the conductors over a relatively narrow (small width) part of the PCB) to enable mechanical failure at a predefined tensile load smaller than that of the first and second safety parts  1231 ,  1232 . As an alternative to the PCB, the wire(s) of the second induction loop can be joined by a connector, thereby providing a safety mechanism that is recoverable after a release (i.e. can be joined again). In an embodiment, the connector constitutes the safety mechanism (cf. e.g.  FIG. 6 ).  FIG. 3   h  shows an embodiment of the second part, where the upper enclosure of the attachment member  122  is omitted, so that a PCB  1223 , whereon the conductor(s) (cf.  1215  of close-up in  FIG. 3   i ) of the loop coil  121  are routed, can be viewed.  FIG. 3   i  shows a close-up of the attachment member  122  in a cross section displaying the PCB  1223 . Here, the induction coil  121  comprises four electrical conductors  1211 ,  1212 ,  1213 ,  1214 , which are terminated (on entering and exiting the attachment member  122 ) in termination pads  1224 . The conductors  1215  are routed on the PCB between inlet and outlet pads and connected to a tuning circuit comprising one or more electronic components  1225  (here in the form of resistors and capacitors) to tune the resonance frequency of the loop to a predefined frequency range.  FIG. 3   j  illustrates an embodiment of a communications device according to the disclosure comprising a first part  11  with a housing  111  where an attachment member  122  of a second part (comprising second induction coil  121 , partly shown) is detachably attached to the housing  11  via gripping members  1221 , which engage with cooperating members formed on each side of the housing  111 .  FIG. 3   k  shows a full perspective view of a communications device according to an embodiment of the disclosure. In an embodiment, the second part can be moved along the length of the housing  111  of the first part  11  (here) by sliding attachment member  122  along the housing from one end to the other or by making a number of cooperating members along the length of the housing for engaging with gripping members  1221 , thereby allowing a modification of the loop to adapt the position of the first part relative to a wearers head when carried around the neck. In this case the corresponding gripping means of housing  111  are preferably adapted to allow such sliding. In an embodiment, the housing  111  of the first part comprises grips at one end of the housing to allow attachment of opposing ‘sides’ of the induction loop to the housing, when attachment member  122  is slid towards the other end of the housing, thereby controlling the form of that part of the loop available for having around the neck (and thus the location of a microphone e.g. located in the top part of the first part relative to a wearers&#39; mouth). 
         [0070]      FIG. 4  shows a second embodiment of a second part of a communications device according to the disclosure providing easy adjustment of the length of the part of the second induction coil intended to be worn around the neck of a person. In this embodiment, as shown in  FIG. 4   a , the attachment member  122  comprises a planar part with four holes for fixing the induction loop by simply routing an end of the loop (before attachment to the safety unit  123 ) through a first hole from a first side to a second side of the planar part of the attachment member and then through the second hole from the second side to the first side of the planar part and so on.  FIG. 4   b  shows the second part  12  with a cross section of the safety member  123  where a printed circuit board  1233 , whereon the electrical conductors of the induction loop are routed, is visible.  FIG. 4   c  shows details of the safety unit  123  comprising PCB  1233  whereon the electrical conductors (here two)  1211 ,  1212  of the induction loop are terminated and routed (looped through). Here, the conductors  1211 ,  1212  on the PCB are connected to a tuning circuit comprising a capacitor  1234  and a resistor  1235  in parallel. As illustrated by dotted ellipses  1236 , the PCB comprises narrow parts adapted to mechanically fail when subject to a predefined tensile load. The safety unit comprises two enclosing parts  1231 ,  1232  (e.g. of made of a plastic material) for protecting the PCB and the safety arrangement. Enclosing parts  1231 ,  1232  may e.g. be embodied as first and second safety parts as shown in  FIG. 3   g .  FIGS. 4   d  and  4   e  show perspective top and bottom view photos of an embodiment of a second part  12  according to the disclosure comprising second induction coil  121  (only partly shown) and attachment member  122 . Protruding gripping members  1221  for detachably attaching the attachment member  122  to the housing of a first part (cf.  FIG. 4   f ) are shown together with planar part  1223  comprising holes for attaching the induction loop  121  to the attachment member  122 .  FIG. 4   f  illustrates a full perspective view of an embodiment of a communications device according to the disclosure, where a second part  12  is attached to a first part  11  in that attachment member  122  of the second part is detachably attached to housing  111  of the first part of the communications device. As illustrated (cf. difference between  FIG. 4   e  and  FIG. 4   f ), a part of the second induction coil  121  can be modified in length and form on or near the housing  111  of the first part  11  to modify the length of the part of the loop being available for taking over the head and/or for modifying the mutual induction between the first and second coils, the first coil of the first part e.g. being located along one of the long sides of the housing  111  of the first part  11  (cf. e.g.  FIG. 2 ). In the simple construction of  FIG. 4 , the distribution of the loop between the two sides of the attachment member  122  can simply be modified by drawing the second induction loop through the holes of the attachment member  122 , thereby e.g. providing a larger or smaller part of the loop to be available for being carried around the neck and thus adapted according to the size of the wearer. 
         [0071]      FIG. 5  shows various embodiments of a second part  12  of a communications device according to the present disclosure for modifying the length of the part  121 ′ of the loop coil determining the position of the first part  11  of a communications device (e.g. comprising a microphone, cf.  114  in  FIG. 8 ) relative to a wearers head (when the relevant part of the loop coil is mounted around the neck of the wearer, cf. e.g.  FIG. 1   b ). The loop coil of  FIG. 5   a  comprises a length regulating member  124  (e.g. of a plastic material) comprising one or two holes through which the loop coil is led, thereby providing a regulating mechanism for dividing the loop in two parts  121 ′,  121 ″, one (the primary part)  121 ′ comprising an attachment member  122  (or the part of the second induction loop adapted for being attached to a first part  11  of a communications device) for being taken over the head, the other 121″ for just hanging loose. A blocking member  125  is shown with the purpose of avoiding that the length regulating member slides off the induction loop in the case that it contains only one hole, instead of two.  FIG. 5   b  illustrates an embodiment, where the length regulating mechanism, comprising two holes through which the induction loop is led, is a part of attachment member  122 , the joining part  126  possibly comprising a tuning circuit and/or a safety mechanism. In the embodiment in  FIG. 5   c , the attachment member  122  comprises a hole  1226  through which the loop coil can be drawn to either side thereby modifying the relative sizes of the two loop parts  121 ′,  121 ″. The second part  12  further comprises a drawing member  127  for facilitating the rearrangement of the relative sizes of the two parts  121 ′,  121 ″ of the loop coil. 
         [0072]      FIG. 6  illustrates a second part  12  of a communications device according to the present disclosure comprising an electrical connector (comprising matching male and female connector parts  128 ′,  128 ″, respectively) for electrically closing the loop of the second induction coil. In an embodiment, the electrical connector  128 ′,  128 ″ is adapted to provide a security mechanism, which releases when subject to a predetermined tensile load. 
         [0073]      FIG. 7  shows an embodiment of a second part  12  of a communications device according to the present disclosure comprising a microphone  129 , here located appropriately on the induction loop  121  relative to a wearer&#39;s head (when worn around the neck). Alternatively a microphone may be located in connection with an attachment member  122 . In an embodiment, the microphone  129  is wirelessly connected with the first part of the communications device. 
         [0074]      FIG. 8  shows an embodiment of a first part  11  of a communications device according to the disclosure comprising a microphone  114  at one end of the housing  111  of the first part, preferably on the end of the first part intended to be closest to a wearers&#39; mouth for picking up the voice of the wearer, cf. e.g.  FIG. 1   b.    
         [0075]    Embodiments of the disclosure defined by the features of the independent claim(s). Preferred embodiments are defined in the dependent claims. Any reference numerals in the claims are intended to be non-limiting for their scope. 
         [0076]    Some preferred embodiments have been shown in the foregoing, but it should be stressed that the disclosure is not limited to these, but may be embodied in other ways within the subject-matter defined in the following claims. 
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