Open-back headphones

Abstract

A flexible arm is positioned between an acoustic module of the open headphones and a battery housing of the open headphones and configured to physically and electrically connect to the acoustic module and the battery housing. The flexible arm includes a flexible printed circuit extending throughout the entire original resting length of the flexible arm and including conductors configured to carry electrical energy between the acoustic module and the battery housing. A first interface structure is coupled to one of the acoustic module and the battery housing. At least one link member is pivotally coupled to the first interface structure. A flexible material encases at least a portion of the flexible printed circuit, at least a portion of the at least one link member, and at least a portion of the first interface structure.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to headphones to be worn on the ear.

[0002] Open-type headphones typically emit sound at a location near the external auditory canal, not inside the external auditory canal. SUMMARY OF THE INVENTION

[0003] All examples and features referred to below may be combined in any technically feasible manner.

[0004] In one aspect, the flexible arm is positioned between an acoustic module of an open-type headphone and a battery housing of the open-type headphone, and is configured to physically and electrically connect the acoustic module and the battery housing. The flexible arm includes a flexible printed circuit that extends through the entire original rest length of the flexible arm and includes a conductor configured to convey electrical energy between the acoustic module and the battery housing. The first interface structure is coupled to one of the acoustic module and the battery housing. At least one link member is pivotally coupled to the first interface structure. The flexible material encloses at least a portion of the flexible printed circuit, at least a portion of the at least one link member, and at least a portion of the first interface structure.

[0005] Implementations may include one of the following features, or any combination thereof.

[0006] In some implementations, the at least one link member is pivotally coupled to the first interface structure via a pivot pin that passes through respective holes in the at least one link member and the first interface structure.

[0007] In certain implementations, the at least one link member suppresses twisting of the flexible arm.

[0008] In some cases, at least one link member includes a plurality of link members that are pivotally connected to one another in series.

[0009] In certain cases, multiple link members are pivotally connected to one another via pivot pins that pass through holes defined by the multiple link members.

[0010] In some embodiments, at least one link member surrounds the flexible printed circuit at least partially.

[0011] In certain embodiments, the flexible arm also includes a guide member coupled to at least one link member. The flexible printed circuit may pass through a channel in the guide member, thereby coupling the flexible printed circuit to at least one link member.

[0012] In some implementations, the guide members are made of silicone.

[0013] In certain implementation configurations, the guide member is coupled to at least one link member via an adhesive.

[0014] In some cases, the flexible arm also includes a second interface structure coupled to the other of the acoustic module and the battery housing. At least one link member may be pivotably coupled to the second interface structure.

[0015] In certain cases, at least one link member includes a plurality of link members that are pivotably connected to one another and arranged in series between a first interface member and a second interface member.

[0016] In some embodiments, at least one link member includes a motion limiting mechanism that restricts the rotational movement of the link member.

[0017] In certain embodiments, at least one link member is made of rigid plastic.

[0018] In some implementations, at least one link member is made of metal (e.g., spring steel).

[0019] In a particular implementation, the flexible material is overmolded onto at least one link member in at least a portion of the flexible printed circuit and at least a portion of the first interface structure.

[0020] In some cases, the flexible material includes the outer layer of the entire flexible arm.

[0021] In certain cases, the original resting position of the flexible arm lies along the curvature axis that defines the simple open curve.

[0022] In some embodiments, the first interface structure includes one or more centering mechanisms to assist in centering the first interface structure within the cavity of the battery housing.

[0023] In certain embodiments, the first interface structure includes one or more guide members that provide rigid stoppers that abut against the battery housing to restrict the inward movement of the first interface structure into the cavity of the battery housing during assembly.

[0024] In some implementations, a flexible material defines a gasket that provides a seal between the first interface member and the acoustic module.

[0025] Various aspects of at least one example are discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. These drawings are included to provide illustrations and further understanding of various aspects and examples, are incorporated into and constitute a part of this specification, and are not intended to define the limitations of the present invention. In the drawings, identical or substantially identical components illustrated in different drawings may be denoted by similar characters or numerals. For clarity, not all components in all drawings may necessarily be labeled. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [Figure 1A] It is a side view of the open-type headphone. [Figure 1B] It is a rear view of the open-type headphone. [Figure 1C] It is a cross-sectional view taken along line 1C-1C of FIG. 1B. [Figure 1D] It is a perspective view of the open-type headphone of FIG. 1A. [Figure 2A] It is a front perspective view of an interface structure for a flexible arm. [Figure 2B] It is a rear perspective view of the interface structure for a flexible arm. [Figure 3A] It is a perspective view of the interface structures of FIG. 2A and FIG. 2B engaged with the battery housing of the open-type headphone. [Figure 3B] It is a perspective view of the interface structures of FIG. 2A and FIG. 2B engaged with the battery housing of the open-type headphone. [Figure 4A] These are various perspective views of another interface structure for a flexible arm. [Figure 4B] These are various perspective views of another interface structure for a flexible arm. [Figure 4C] These are various perspective views of another interface structure for a flexible arm. [Figure 5A]These are a perspective view and a rear view of the interface structure shown in Figure 4A, engaged with the acoustic module of open-type headphones, respectively. [Figure 5B] These are a perspective view and a rear view of the interface structure shown in Figure 4A, engaged with the acoustic module of open-type headphones, respectively. [Figure 5C] These are a perspective view and a rear view of the interface structure shown in Figure 4A, engaged with the acoustic module of open-type headphones, respectively. [Figure 6A] These are front perspective and rear perspective views of the link member of the open-type headphones shown in Figure 1A, respectively. [Figure 6B] These are front perspective and rear perspective views of the link member of the open-type headphones shown in Figure 1A, respectively. [Figure 7A] This is a perspective view of open-back headphones with an alternative link member design. [Figure 7B] This is a perspective view of open-back headphones with an alternative link member design. [Figure 8A] These are the front perspective view and rear perspective view of the link member of the open-type headphones shown in Figure 7A, respectively. [Figure 8B] These are the front perspective view and rear perspective view of the link member of the open-type headphones shown in Figure 7A, respectively. [Modes for carrying out the invention]

[0027] Open-back headphones, worn on the ears, must provide high-quality sound, be stable on the ears, comfortable for extended wear, inconspicuous, and stylish in appearance. These objectives have been considered mutually exclusive in several respects, making them difficult to achieve. For example, stability typically leads to clamping onto the outer ear, which can be uncomfortable for prolonged wear and may even be unstylish. Furthermore, for high-quality sound, acoustics must be delivered near the ear canal, rather than inside it, meaning the headphone structure must be worn over the ear, making it clearly visible to others. Also, for optimal sound quality, sound should be delivered near the ear canal opening, rather than inside it.

[0028] The embodiments of open-back headphones considered herein are not limited to those applicable to the configuration details and component arrangements described below or illustrated in the accompanying drawings. The headphones can be implemented in other embodiments and can be practiced or executed in various ways. Specific embodiments are provided herein for illustrative purposes only and are not intended to be limiting. Specifically, any functions, components, elements, and features considered in relation to any one or more embodiments are not intended to be excluded from similar roles in any other embodiments.

[0029] The examples disclosed herein can be combined with other examples in any manner consistent with at least one of the principles disclosed herein, and further, references to “an example,” “some examples,” “an alternate example,” “various examples,” and “one example” are not necessarily exclusive to one another, and are intended to indicate that a particular feature, structure, or characteristic described may be included in at least one example. The appearance of such terms herein does not necessarily refer to the same example.

[0030] Furthermore, the expressions and terminology used herein are for illustrative purposes only and should not be considered limiting. Any singular reference to an example, component, element, action, or function of headphones herein may also encompass embodiments including multiple examples, components, elements, actions, or functions herein, and any plural reference to any example, component, element, action, or function herein may also encompass embodiments including only singular examples. Accordingly, singular or plural references are not intended to limit the systems or methods, their components, actions, or elements of the disclosure. The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof herein means that they encompass the items listed below and their equivalents, as well as other items. References to “or” may be interpreted as comprehensive, so as to whether all terms described in “or” refer to one, two or more, or all of the terms described.

[0031] In some embodiments of this specification, open-type headphones include a flexible arm positioned between an acoustic module and the battery housing of the headphones, and configured to be physically and electrically connected to the acoustic module and the battery housing. The flexible arm defines the original stationary length and position between the acoustic module and the battery housing. The flexible arm includes a flexible printed circuit extending over the entire original stationary length of the flexible arm. The flexible printed circuit includes one or more conductors that carry electrical energy between the acoustic module and the battery housing. An interface structure is coupled to the acoustic module or the battery housing. A flexible material encloses at least a portion of the flexible printed circuit and at least a portion of the interface structure. In some embodiments, the length of the flexible printed circuit within the flexible arm is longer than the original stationary length of the flexible arm. The flexible printed circuit can therefore better adapt to tension or compression on the flexible arm when the flexible arm is bent from its original stationary position.

[0032] In some embodiments, the original resting position of the flexible arm is along the curvature axis. In one embodiment, the curvature axis defines a simple open curve. In one embodiment, the curvature axis is roughly "C" shaped. In one embodiment, the curvature axis bisects the flexible arm, and different portions of the first surface of the flexible printed circuit are located on different sides of the curvature axis. In one embodiment, the flexible printed circuit defines at least one simple open curve along the length of the flexible printed circuit within the flexible arm. In one embodiment, the flexible printed circuit defines both multiple upward and downward simple open curves along the length of the flexible printed circuit within the flexible arm. In one embodiment, each downward simple open curve is adjacent to one or more upward simple open curves.

[0033] In various embodiments, the flexible arm may also include a series of pinned links positioned between a first interface structure and a second interface structure, and pivotably attached to them. Flexible printed circuitry may be passed through internal channels formed in the links, which can provide support and protection for the flexible printed circuitry in the region between the interface members. The links may also resist torsional motion, for example, to prevent twisting of the flexible arm. The links may be formed from plastic (e.g., cast urethane) or metal (e.g., spring steel) and may be formed in a molding or stamping operation.

[0034] Figure 1A is a side view of the open-type headphones 100, Figure 1B is a rear view, Figure 1C is a cross-sectional view cut along line 1C-1C, and Figure 1D is a perspective view. The headphones 100 are configured to be worn on the user's ear such that the distal sound delivery end 102 of the headphone's acoustic module 104 is positioned within the concha of the ear, and the battery housing 106 is positioned behind the ear. The flexible arm 108 is configured to pass over the outer upper part of the helix, antihelix, and / or lobule of the ear. The arm 108 has an original or stationary position and length illustrated in Figures 1A to 1D. In some embodiments, the original position defines a roughly "C" shape, as shown in these figures. The arm 108 is configured to flex at least along its length so that the space between the acoustic module 104 and the battery housing 106 can be slightly increased. This allows the headphones 100 to be put on and taken off without having to push them over the outer ear, and further helps to hold the headphones 100 in place over the ear by providing a light clamping force to the ear as the user's head moves. Note that Figures 1A to 1D illustrate some interference between the acoustic module 104 and the battery housing 106. However, in most embodiments, there is actually space between these two, as disclosed in the patent incorporated by reference, for example. In some embodiments, this interference is modeled so that the arm 108 will try to "rest" in this position if it is molded into this shape. This modeling helps to create some preload on the arm.

[0035] Electrical signals need to be carried through arm 108. In some embodiments, the electrical signals include or complete power from battery 110 in battery housing 106 to any motorized circuits and components in acoustic module 104 and acoustic transducer 112. In some embodiments, the electrical signals also include audio signals from radio receiving and processing circuits (not shown) which may be located in one or more of arm 108, battery housing 106, and acoustic module 104. In some embodiments, these electrical signals are carried by conductors in flexible printed circuit 114. The flexible printed circuit needs to be able to flex when arm 108 flexes, but at the same time, it needs to carry the necessary electrical signals.

[0036] The flexible printed circuit 114 delivers power from the battery 110 to the data receiving and processing circuits on the printed circuit board 116. Power and audio signals are supplied from the board 116 to the transducer 112. The transducer 112 generates sound pressure within the front acoustic cavity 118 and the rear acoustic cavity 120. The openings / ports of the acoustic module housing 122 are pathways for sound to escape from the housing 122. The flexible printed circuit 114, the arm interface structures 124 and 126, and the flexible overmolding material 128 are described further below.

[0037] Further details of open-back headphones, including but not limited to details of their structure, operation, and acoustic performance, are disclosed in U.S. Patent No. 11,140,469, the entire disclosure of which is incorporated herein by reference for all purposes. The embodiments of the open-back headphones disclosed herein are not further described herein.

[0038] In some embodiments, the flexible arm 108 includes one or more interface structures 124, 126. The interface structures are configured to mechanically connect the arm to one or both of the battery housing and / or the acoustic module. In some embodiments, the interface structures are relatively rigid but have some flexibility. The interface structures can be made from engineering plastics such as nylon or acrylonitrile butadiene styrene (ABS), or from rubber or a rubber-like material. In some embodiments, the interface structures are manufactured by injection molding or machining or stamping or 3D printing. In some embodiments, the interface structure is a single component. The interface structure helps to hold the arm in its curved stationary position and provides reinforcement to the arm. In some embodiments, the interface structure also helps to anchor a relatively flexible overmolde that covers the entire arm. In some embodiments, the overmolde also covers at least a portion of the battery housing.

[0039] Figures 2A and 2B illustrate a first interface structure 124. The interface structure 124 is a one-piece molded plastic component defining a body 202 extending between a proximal end 204 and a distal end 206, with a pair of pivot arms 208 positioned along the distal end 206 of the body 202. Each of the pivot arms 208 includes a hole 209 for accommodating a pivot pin 130 (Figure 1C). The body 202 defines an opening 210 extending through its length between the proximal end 204 and the distal end 206. The opening 210 accommodates a flexible printed circuit 114, thereby allowing the flexible printed circuit 114 to pass through the first interface structure 124 and enter the battery housing 106.

[0040] The interface structure 124 is configured to connect the flexible arm 108 to the battery housing 106 and to help support and guide the flexible printed circuit 114. As shown in Figures 3A and 3B, the body 202 is configured to connect to the battery housing 106. In some embodiments, the body 202 is received in a complementary shaped cavity 302 (Figure 3B) within the battery housing 106, and / or the battery housing 106 may be made from two (or more) parts that are snapped together around the body 202 or otherwise mated together. Adhesives (such as pressure-sensitive adhesives) may be used to permanently attach the interface structure 124 to the battery housing 106.

[0041] A pair of guide members 212, represented in the form of protruding bars, are provided along the opposing outer surfaces of the main body 202. The guide members 212 provide rigid stops that abut against the battery housing 106, preventing further inward movement during assembly. The guide members 212 provide reference surfaces that help ensure the interface structure 124 is properly positioned during assembly with the battery housing 106. The interface structure 124 further includes a plurality of centering mechanisms 214, represented in the form of protruding ridges extending outward from the outer surface of the main body 202. These centering mechanisms 214 engage with the surface of the battery housing 106 within the cavity 302, helping to ensure that the main body 202 is centered within the cavity 302.

[0042] The second interface structure 126 (Figures 4A-4C) connects the flexible arm 108 to the acoustic module 104. The interface structure 126 is a single-piece molded plastic part that defines a main body 402, a narrow intermediate section 404, and an enlarged end section 406. The main body 402 defines a recess 410 for housing the flexible printed circuit 114.

[0043] The interface structure 126 is configured to connect the flexible arm 108 to the acoustic module 104, to help support and guide the flexible printed circuit, and to anchor the overmolding. The terminal extension portion 406 is configured to connect to the acoustic module 104 as shown in Figure 5A (only a portion of the acoustic module is shown in Figures 5A-5C). In some embodiments, portion 406 is received in a complementary shaped cavity (not shown) within the acoustic module 104, and / or the acoustic module 104 is fabricated from two (or more) parts snapped together around portion 402 or otherwise mated together. In some embodiments, an adhesive (such as a pressure-sensitive adhesive) is used to permanently attach the interface structure 126 to the acoustic module 104.

[0044] The interface structure 126 defines a guide 410 for the flexible printed circuit 114. The guide 410 has approximately the same width and thickness as the flexible printed circuit, and as a result, the flexible printed circuit is guided into the acoustic module through a slot 412 that extends through a middle narrow portion 404 and a terminal wide portion 406. The guide 410 helps to properly center, align, and support the flexible printed circuit. The guide 410 includes a flat surface formed by a recess formed on the surface of the body 402.

[0045] In some embodiments of this specification, the overmolding material 128 surrounds and encloses the flexible printed circuit along at least a large portion, preferably all, of the original stationary length of the flexible arm, as well as a portion, preferably all, of any internal support and interface structures. In some cases, a sleeve (not shown) may be provided to cover the link member 600 before overmolding the overmolding material 128. The sleeve can help prevent the overmolding material 128 (e.g., silicone) from entering the link or coming into direct contact with the link.

[0046] Before assembly with the acoustic module 104 (only a portion of the acoustic module is shown in Figures 5A-5C), the interface structure 126 is overmolded with a flexible overmolding material 128 (Figures 5B and 5C). For illustrative purposes, the interface structure 126 is shown in Figure 5A without the overmolding material 128. The overmolding material 128 forms a gasket 502 (Figures 5B and 5C) around the intermediate narrow portion 404, which engages with the acoustic module 104 to form a seal between them, preventing, for example, the entry of liquid or debris into the internal cavity of the acoustic module 104.

[0047] Referring to Figures 6A and 6B, one or more link members 600 are positioned between the first interface structure 124 and the second interface structure 126 and are pivotally coupled to them. Each link member 600 includes a plurality of link arms 602 and one or more bridge members 604 extending between them. In the illustrated embodiment, the bridge member 604 is positioned to define a channel 606 for housing the flexible printed circuit 114 between the link arms 602.

[0048] Each of the link arms 602 includes a hole 612 for receiving a pivot pin 130 (Figure 1C) for connecting the link members 600 to each other and to the first and second interface structures. In the embodiment shown in Figure 1D, which includes a plurality of link members 600 arranged in series, a link arm 602 positioned along the distal end 610 of a link member 600 is configured to fit around a link arm 602 positioned along the proximal end 608 of an adjacent link member of the link member 600. Link arms 602 positioned along the proximal ends 608 of a series of first link members 600 are configured to fit between pivot arms 208 (Figures 2A and 2B) on the first interface structure 124, and a link arm 602 positioned along the distal end 610 of the last link member 600 in the series is configured to fit around a pair of pivot arms 414 on the second interface structure 126. A pivot pin 130 (Figure 1C) extends through a hole in the link arm 602, pivotably connecting the link members 600 together. Similarly, the pivot pin 130 extends through holes in the first and last link members 600 and the first and second interface structures 124, 126, respectively, pivotably connecting the link members 600 to the battery housing 106 and the acoustic module 104. In some cases, each of the link members 600 may also include a motion limiting mechanism, such as a protrusion or wedge, extending outward from one of the bridge members 606, providing a mechanical limit to the rotation of the link members 600. The links can be formed from plastic (e.g., cast urethane).

[0049] Figures 1C and 1D illustrate how the flexible printed circuit 114 interfaces with the link member 600, the interface structure 124, and the interface structure 126. The first end 132 of the flexible printed circuit 114 is configured to interface with a printed circuit board connected to two terminals of the battery 110 (Figure 1C) in the battery housing 106, while the second end 136 is configured to interface with a printed circuit board in the acoustic module 104 (such as the printed circuit board 116 in Figure 1C). To adapt to the deflection of the arm 108 while reducing stress on the flexible printed circuit 114, the flexible printed circuit 114 may have a length in the arm 108 that is longer than the nominal stationary length of the arm 108. The additional length can be achieved by one or more curves in the flexible printed circuit held within the flexible arm 108. Such additional length can be accommodated in the curved portion formed in the flexible printed circuit 114. In some embodiments, the curved portion 138 is held in place via associated pivot pins of the pivot pins 130. The link member 600 serves to surround and protect the flexible printed circuit board 114. In addition, the link member 600 suppresses twisting of the flexible arm 108. The link member 600 can be manufactured by injection molding, machining, or stamping.

[0050] Other implementation forms Different mounting configurations of the link member are shown in Figures 7A, 7B, 8A, and 8B. The link member 800 can be manufactured by injection molding, machining, or stamping. In some embodiments, the link member 800 may be formed from spring steel (e.g., by stamping). The link member 800 includes a pair of link arms (a first link arm 802 and a second link arm 804) connected to each other via a bridge member 806. A third link arm 808 extends from the middle portion of the bridge member 806. The link arms 802, 804, and 808 are provided with holes 814 for receiving a pivot pin 130. The third link arm 808 is configured to fit between the first link arm 802 and the second link arm 804 of an adjacent link member 800. The pivot pin 130 pivotably connects the link member 800. The link arms 802, 804, and 808 can similarly be pivotably coupled to the pivot arms 208 and 414 on the first and second interface structures 124 and 126 via the pivot pin 130.

[0051] The link member 800 may also include a motion limiting mechanism 820 that restricts the amount of relative rotational motion. This can help prevent hyperextension of the flexion joint. In the embodiments shown in Figures 8A and 8B, the motion limiting mechanism 820 is in the form of a tab extending outward from a bridge member between the first link arm 802 and the second link arm 804.

[0052] The link members 800 can rotate freely relative to each other before the limiting mechanism 820 comes into contact with an adjacent link member 800. When the limiting mechanism 820 on each link comes into contact with an adjacent link member 800, any further rotation will cause bending of the link member 800, thereby providing the user with relatively firm resistance as feedback to prevent (e.g., avoid) any additional rotation that could damage other plastic parts or flexible printed circuits 114.

[0053] In some cases, the guide member 822 may be provided on one or more of the link members 800. The guide member 822 defines a channel 824 (Figure 8B) for receiving and supporting the flexible printed circuit 114. The guide member 822 may be formed from silicone and may be fixed to the link member 800, for example, via an adhesive or mutual locking mechanical features.

[0054] While several embodiments relating to at least one example have been described, it will be understood that various changes, modifications, and improvements are readily conceivable to those skilled in the art. Such changes, modifications, and improvements are intended to be part of this disclosure and within the scope of the invention. Accordingly, the foregoing description and drawings are merely illustrative, and the scope of the invention should be determined from the appropriate configuration of the appended claims and their equivalents.

Claims

1. A flexible arm positioned between the acoustic module and the battery housing of open-back headphones, and configured to be physically and electrically connected to the acoustic module and the battery housing, A flexible printed circuit comprising a conductor that extends throughout the entire original stationary length of the flexible arm and is configured to transport electrical energy between the acoustic module and the battery housing, A first interface structure coupled to one of the acoustic module and the battery housing, At least one link member pivotably coupled to the first interface structure, The system comprises a flexible material that encloses at least one link member, at least a portion of the flexible printed circuit, and at least a portion of the first interface structure, A flexible arm comprising at least one link member, which includes a plurality of link members that are pivotably connected to each other in series.

2. A flexible arm positioned between the acoustic module and the battery housing of open-back headphones, and configured to be physically and electrically connected to the acoustic module and the battery housing, A flexible printed circuit comprising a conductor that extends throughout the entire original stationary length of the flexible arm and is configured to transport electrical energy between the acoustic module and the battery housing, A first interface structure coupled to one of the acoustic module and the battery housing, At least one link member pivotably coupled to the first interface structure, The system comprises a flexible material that encloses at least one link member, at least a portion of the flexible printed circuit, and at least a portion of the first interface structure, The system further comprises a second interface structure coupled to the other of the acoustic module and the battery housing, wherein at least one link member is pivotally coupled to the second interface structure. A flexible arm comprising a plurality of link members arranged in series between the first interface structure and the second interface structure, wherein at least one link member is pivotally connected to one another.

3. The flexible arm according to claim 1 or 2, wherein the at least one link member is pivotably coupled to the first interface structure via pivot pins passing through the at least one link member and respective holes in the first interface structure.

4. The flexible arm according to claim 1 or 2, wherein the at least one link member suppresses twisting of the flexible arm.

5. The flexible arm according to claim 1, wherein the plurality of link members are pivotably connected to each other via pivot pins passing through holes defined by the plurality of link members.

6. The flexible arm according to claim 1 or 2, wherein the at least one link member surrounds the flexible printed circuit at least partially.

7. The flexible arm according to claim 1 or 2, further comprising a guide member coupled to the at least one link member, wherein the flexible printed circuit passes through a channel in the guide member, thereby coupling the flexible printed circuit to the at least one link member.

8. The flexible arm according to claim 7, wherein the guide member is made of silicone.

9. The flexible arm according to claim 7, wherein the guide member is connected to the at least one link member via an adhesive.

10. The flexible arm according to claim 1 or 2, wherein the at least one link member is equipped with a motion limiting mechanism that limits the rotational movement of the link member.

11. The flexible arm according to claim 1 or 2, wherein at least one link member is made of rigid plastic.

12. The flexible arm according to claim 1 or 2, wherein at least one link member is made of metal.

13. The flexible arm according to claim 1 or 2, wherein the flexible material is overmolded onto the at least one link member, at least a portion of the flexible printed circuit, and at least a portion of the first interface structure.

14. The flexible arm according to claim 1 or 2, wherein the flexible material includes the outer layer of the entire flexible arm.

15. The flexible arm according to claim 1 or 2, wherein the original resting position of the flexible arm is along a curvature axis defining a simple open curve.

16. The flexible arm according to claim 1 or 2, wherein the first interface structure comprises one or more guide members that provide rigid stop portions that abut against the battery housing to restrict the inward movement of the first interface structure into the cavity of the battery housing during assembly.

17. The flexible arm according to claim 1 or 2, wherein the flexible material defines a gasket that provides a seal between the first interface structure and the acoustic module.

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