Audio transducers for small form factor devices and related devices, systems or methods

Abstract

An audio transducer assembly and an apparatus incorporating the same are disclosed. The assembly includes an audio transducer, comprising a diaphragm and a transducing mechanism, which is substantially encapsulated by a metallic enclosure. The enclosure is an integrally formed unit that provides structural reinforcement to a host apparatus, such as a slender housing of a wearable device. To ensure a durable interface, the enclosure may feature a profiled edge region that facilitates a stress-reducing junction with the housing. In some embodiments, the transducer is an armature-type transducer where the diaphragm is rigidly coupled to a pivoting armature. Apertures in the enclosure provide an acoustic pathway from the diaphragm to an exterior of the housing, allowing the assembly to function as a loudspeaker or a microphone.

Description

[0001] AUDIO TRANSDUCERS FOR SMALL FORM FACTOR DEVICES AND RELATED DEVICES, SYSTEMS OR METHODS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to audio transducers, and to associated devices, systems, or methods.

[0004] BACKGROUND TO THE INVENTION

[0005] Audio transducers are widely used in various audio devices such as smart glasses, hearing aids, in- ear monitors, mobile phones, and other compact audio delivery systems. A significant challenge in these applications is the delivery of high-fidelity sound from a compact form factor, making them a focus for applications where space constraints are a critical consideration.

[0006] In some implementations, such as with armature-type audio transducers, precise control over the diaphragm’s movement can be achieved. However, such devices can still face challenges that impact their performance and reliability.

[0007] One primary issue across various transducer designs is achieving a broad frequency response range. Due to the mechanical and physical constraints of compact components, some transducers may struggle to accurately reproduce relatively low or relatively high frequencies, which can affect the overall sound quality.

[0008] Another problem can be limited volume excursion capability. For open-ear applications like smart glasses, this limitation can make it difficult to achieve satisfactory volume and bass response.

[0009] The physical form factor of the transducer itself is often a key design constraint. Certain transducer architectures may be suboptimal for integration into devices that are required to be exceptionally thin or slender.

[0010] Finally, durability and longevity can be a concern. The delicate nature of the internal moving components in some transducers can make them prone to damage from physical shock or handling. An object of the present invention is to provide an improved audio transducer, assembly or apparatus that overcomes at least some of the limitations of existing systems, or that at least provides the public with an alternative and useful choice.

[0011] SUMMARY OF THE INVENTION

[0012] In a first aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure, a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm directly coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature.

[0013] In a second aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure, a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to and extending from an end of the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature.

[0014] In a third aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure, a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to and extending from a lateral cross-member at an end of the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature.

[0015] In a fourth aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, a structure closely surrounding and directly adjacent an outer peripheral edge of the diaphragm and wherein the outer peripheral edge of the diaphragm is substantially free from physical connection with the surrounding structure.

[0016] In a fifth aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure within the static magnetic field; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration in the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, wherein the magnetic structure comprises a pair of magnetic bodies, each of which comprises a surface opposing the armature and having a plane that is substantially angled relative to a longitudinal axis of the armature.

[0017] In an embodiment, a pair of opposing surfaces either side of the armature are each substantially angled relative to a general, major plane of the armature along which a longitudinal axis of the armature extends.

[0018] In an embodiment, each surface is angled away from the longitudinal axis of the armature toward a terminal end of the armature distal from the coils. In an embodiment, each of the opposing magnetic surfaces is angled such that a gap between the surfaces increases in a direction from an end of the armature proximal to the diaphragm toward an end of the armature distal to the diaphragm.

[0019] In a sixth aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration in the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, wherein the diaphragm is substantially thick in at least a region of the diaphragm, relative to a length and / or width dimension of the diaphragm.

[0020] In a seventh aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration in the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, a hinge pivotally coupling the armature to the transducer base structure, and comprising a flexing element oriented substantially parallel to a general, major plane of the armature in a neutral rotational position of the armature and hinge, wherein the flexing element comprises a thickness substantially smaller than a thickness of the armature measured orthogonally to the major plane.

[0021] In an embodiment the flexing element is substantially coplanar with the general, major plane of the armature when the armature is in the neutral rotational position.

[0022] In an eighth aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure a magnetic structure configured to generate a static magnetic field therebetween; an armature positioned suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, a hinge pivotally coupling the armature to the transducer base structure, and having at least one elongate, flexible, and resilient element coupled to a central region of the armature and extending from the central region along the axis of rotation towards opposing sides of the armature.

[0023] In a ninth aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure a magnetic structure configured to generate a static magnetic field therebetween; an armature positioned suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature; and a hinge pivotally coupling the armature to the transducer base structure, wherein the diaphragm comprises a recess, and the hinge is located at least partially within the diaphragm recess.

[0024] In an embodiment, the hinge comprises at least one elongate, flexible, and resilient element.

[0025] In a tenth aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, wherein at least one magnetic body of the magnetic structure extends substantially beyond a terminal end of the armature distal to the diaphragm.

[0026] In an embodiment, a pair of magnetic bodies of the magnetic structure extend substantially beyond the terminal end of the armature distal to the diaphragm.

[0027] In an embodiment, a terminal end of at least one magnetic body of the magnetic structure, or each of a pair of magnetic bodies of the magnetic structure, extend(s) substantially beyond the corresponding distal terminal end of the armature, in a direction substantially parallel to a longitudinal axis of the armature.

[0028] In an embodiment, at least one magnetic body of the magnetic structure, or each of the pair of magnetic bodies of the magnetic structure, extend(s) significantly beyond the distal terminal end of the armature.

[0029] In an embodiment a terminal end of at least one magnetic body of the magnetic structure, or each of the pair of magnetic bodies of the magnetic structure, extend(s) significantly beyond the corresponding distal, terminal end of the armature, in a direction substantially parallel to the longitudinal axis of the armature.

[0030] In an embodiment, at least one magnetic body of the magnetic structure, or each of the pair of magnetic bodies of the magnetic structure, extend(s) longitudinally beyond the distal terminal end of the armature. In an eleventh aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature; wherein the magnetic structure comprises one or more outer permanent magnets located on an outer side of the armature and extending across a general, major plane of the armature.

[0031] In an embodiment, the one or more outer permanent magnets comprises an axis between north and south poles that is oriented substantially orthogonally to the major plane of the armature.

[0032] Implementations of any one of the first to eleventh aspects of the invention may comprise any of the features of the following embodiments, or any combination of features from two or more of the following embodiments.

[0033] In an embodiment, the diaphragm is rigidly coupled to the armature.

[0034] Transducing Mechanism Features

[0035] In an embodiment, the magnetic structure comprises at least one pair of magnetic bodies configured to generate and / or direct the static magnetic field.

[0036] In an embodiment, the magnetic bodies are rigidly coupled to the transducer base structure. In an embodiment, the magnetic bodies comprise at least one permanent magnet, and preferably a pair of permanent magnets, configured to generate the static magnetic field. Alternatively, or in addition, the magnetic bodies comprise at least one electromagnet, and preferably a pair of electromagnets, configured to generate the static magnetic field.

[0037] In an embodiment, the magnetic bodies comprise at least one pair of ferromagnetic bodies. The ferromagnetic bodies may be coupled to corresponding permanent magnets and / or electromagnets to direct and concentrate the static magnetic field toward a desired region of the transducer.

[0038] In an embodiment, a pair of opposing magnetic pole surfaces of the magnetic bodies locate proximal to, and on either side of the armature. In an embodiment, the magnetic pole surfaces proximal to the armature are rigidly fixed to the transducer base structure.

[0039] In an embodiment, the magnetic pole surfaces proximal to the armature are angled, relative to a general, major plane of the armature.

[0040] In an embodiment, at least one, but preferably both, the magnetic pole surfaces opposing the armature have a plane that is substantially angled relative to a longitudinal axis of the armature.

[0041] In an embodiment, each surface is angled away from a general, major plane of the armature toward a terminal end of the armature distal from the coils.

[0042] In an embodiment, a terminal end of each of the pair of magnetic bodies comprising the pair of magnetic pole surfaces opposing the armature, extends beyond a corresponding terminal end of the armature, along an axis parallel to a longitudinal axis of the armature. Preferably the magnetic bodies extend significantly beyond the terminal end of the armature.

[0043] In an embodiment, the abovementioned magnetic pole surfaces are formed on the ferromagnetic bodies that direct and concentrate the magnetic field.

[0044] In an embodiment, the magnetic structure comprises one or more outer permanent magnets located on an outer side of the armature. Preferably, the one or more outer permanent magnets extends across a general, major plane of the armature. In an embodiment, each outer permanent magnet is spaced from the armature.

[0045] In an embodiment, each outer permanent magnet extends substantially orthogonally relative to the general major plane of the armature.

[0046] In an embodiment, each outer permanent magnet comprises magnetic poles that locate on either side of the general major plane of the armature.

[0047] In an embodiment, the at least one outer permanent magnet comprises an end permanent magnet located opposite a terminal, free edge of the armature distal from the diaphragm.

[0048] In an embodiment, the at least one outer permanent magnet comprises at least one side permanent magnet locating opposite a side edge of the armature, the side edge extending between a diaphragm end of the armature and a free edge of the armature distal from the diaphragm.

[0049] In an embodiment, the at least one outer permanent magnet comprises a pair of side permanent magnets locating opposite a pair of side edges of the armature.

[0050] In an embodiment, the at least one outer permanent magnet further comprises a pair of permanent magnets located opposite a pair of opposing major faces of the armature and extending substantially parallel to the general major plane of the armature.

[0051] In an embodiment, the magnetic structure further comprises a pair of outer ferromagnetic bodies extending substantially parallel to the general major plane of the armature.

[0052] In an embodiment, each of the pair of outer ferromagnetic bodies extends between a corresponding side outer permanent magnet and the end outer permanent magnet.

[0053] In an embodiment, each of the pair of outer ferromagnetic bodies locates opposite a corresponding major face of the armature.

[0054] In an embodiment, the audio transducer comprises an enclosure for housing other components of the audio transducer and the ferromagnetic bodies form at least a part of walls of the enclosure. In an embodiment the magnetic structure is devoid of ferromagnetic bodies along one or more sides of the armature between the outer permanent magnet and at least one outer side permanent magnet.

[0055] In an embodiment the magnetic structure is devoid of ferromagnetic bodies along two sides of the armature between the outer permanent magnet and the two outer side permanent magnets.

[0056] In an embodiment, the audio transducer comprises a first magnetic circuit having one or more permanent magnets. The one or more permanent magnets may be rigidly coupled to the transducer base structure. The first magnetic circuit may further comprise one or more ferromagnetic components that are substantially rigidly coupled to the transducer base structure. The first magnetic circuit may further comprise the movable armature. Preferably the magnetic and ferromagnetic components form a substantially complete first magnetic circuit.

[0057] In an embodiment, the audio transducer comprises a second magnetic circuit having one or more electromagnets. The second magnetic circuit may further comprise one or more ferromagnetic components that are substantially rigidly coupled to the transducer base structure. The second magnetic circuit may comprise the movable armature. Preferably the magnetic and ferromagnetic components form a substantially complete second magnetic circuit.

[0058] In an embodiment, the coil is rigidly coupled to the transducer base structure and is stationary in operation. In an alternative embodiment the coil is rigidly coupled to the armature and moves with the armature during operation.

[0059] In an embodiment, the coil is wound about the armature at or adjacent the axis of rotation of the armature.

[0060] Features relating to coupling between diaphragm and armature

[0061] In an embodiment, the diaphragm is mechanically coupled to and extends from an end of the armature.

[0062] In an embodiment, the diaphragm is mechanically coupled directly adjacent to the end of the armature. In an embodiment, the diaphragm directly couples the armature.

[0063] In an embodiment, a general, major plane of the diaphragm is substantially parallel to a general, major plane of the armature.

[0064] In an embodiment, the general, major plane of the diaphragm is offset from and substantially parallel to a general, major plane of the armature, the offset being defined along an axis that is substantially perpendicular to said general, major planes. Preferably the offset is less than a thickness of the magnetic structure.

[0065] In an embodiment, the general, major plane of the diaphragm is substantially coplanar with the general, major plane of the armature.

[0066] In an embodiment, the diaphragm is mechanically coupled to and extends from a lateral crossmember at an end of the armature.

[0067] In an embodiment, the lateral cross member is substantially orthogonal to a longitudinal axis of a main body of the elongate armature.

[0068] In an embodiment, the lateral cross-member forms a T-shaped connection at an end of the armature for mechanically coupling the diaphragm.

[0069] In an embodiment, the lateral cross-member is substantially rigid. Preferably the lateral-cross member is substantially rigid such that it does not flex during operation.

[0070] In an embodiment, the lateral cross-member is substantially angled relative to the armature. Preferably, the cross-member is substantially orthogonal to the armature.

[0071] In an embodiment, the lateral cross-member comprises a general, major plane that is substantially angled relative to a general, major plane of the armature. Preferably the general, major plane of the armature is substantially orthogonal to the general, major plane of the armature.

[0072] In an embodiment, the lateral cross-member comprises a general, major plane that is substantially angled relative to a general, major plane of the diaphragm. Preferably the general, major plane of the lateral cross-member is substantially orthogonal to the general, major plane of the diaphragm.

[0073] In an embodiment, an end of the diaphragm couples the lateral cross-member.

[0074] In an embodiment, an end face of the diaphragm couples a face of the lateral cross-member.

[0075] In an embodiment, the armature extends from a first side of the cross-member and the diaphragm extends from an opposing, second side of the cross-member.

[0076] In an embodiment, the diaphragm is mechanically coupled to an end of the armature located proximal to the pair of magnetic bodies.

[0077] In an embodiment, the diaphragm is mechanically coupled to the end of the armature that is distal from the pair of magnetic bodies.

[0078] In an embodiment, the diaphragm is mechanically coupled to an end of the armature that is proximal to the axis of rotation.

[0079] In an embodiment, the diaphragm comprises a recess at a base end of the diaphragm for accommodating and rigidly coupling a corresponding projection or end of the armature.

[0080] In an embodiment the diaphragm is substantially rigid in-use.

[0081] In an embodiment, the armature is substantially rigid in use.

[0082] In an embodiment, the diaphragm is rigidly coupled to the armature.

[0083] In an embodiment, the diaphragm extends longitudinally from the end of the armature.

[0084] In an embodiment, the diaphragm extends from an end of the armature proximal to the coil.

[0085] In an embodiment, the diaphragm extends from an end of the armature proximal to the axis of rotation of the armature, in an opposing direction to the armature.

[0086] In an embodiment, the diaphragm is configured to vibrate about an axis of rotation. In an embodiment, the diaphragm is configured to vibrate about the axis of rotation of the armature.

[0087] In an embodiment, the diaphragm and the armature extend in substantially opposing directions from the axis of rotation.

[0088] Diaphragm Surround Features

[0089] In an embodiment, the audio transducer comprises a structure closely surrounding and directly adjacent an outer peripheral edge of the diaphragm and wherein the outer peripheral edge of the diaphragm is substantially free from physical connection with the surrounding structure. Preferably the outer peripheral edge that is substantially free from physical connection with the surrounding structure constitutes at least approximately 20% of an entire perimeter of the diaphragm periphery, more preferably at least approximately 50% of the entire perimeter, and most preferably at least approximately 80% of an entire perimeter.

[0090] In an embodiment, the surrounding structure excludes the diaphragm base structure.

[0091] In an embodiment, a gap formed between the outer peripheral edge and the surrounding structure is substantially narrow. Preferably the gap is less than approximately 0.5mm, more preferably is less than 0.3mm, and most preferably is less than 0.2mm. Preferably the gap is an air gap. Preferably the gap between the outer peripheral edge and the surrounding structure, in a region or side most distal from the axis of rotation, is more than 2 times greater, more preferably more than 3 times greater, and most preferably more than 4 times greater, than an average cell diameter of a core material of the diaphragm in the same region.

[0092] In an embodiment, the audio transducer comprises a housing or enclosure with a cavity for accommodating parts of the magnetic structure, the diaphragm and the armature and wherein a maximum displacement of a terminal end of the diaphragm across a full range of motion of the diaphragm is substantially greater than at least 50 percent of a maximum inner depth or thickness dimension of the cavity, more preferably at least 70%, and most preferably at least 80% percent.

[0093] Diaphragm Features In an embodiment, the diaphragm comprises a radial length from the axis of rotation of the diaphragm that is substantially greater than a radial length of the armature from the axis of rotation of the armature.

[0094] In an embodiment, the radial length of the diaphragm is at least 1.5 times greater, more preferably 2 times greater, and most preferably 2.5 times greater, than a radial length of the armature.

[0095] In an embodiment, the diaphragm comprises a radial length from the axis of rotation of the diaphragm that is substantially greater than the maximum dimensions of the diaphragm in directions orthogonal to the radial length.

[0096] In an embodiment, the radial length of the diaphragm is at least 1.5 times greater, more preferably 2 times greater, and most preferably 2.5 times greater than the maximum dimensions of the diaphragm in directions orthogonal to the radial length.

[0097] In an embodiment, the diaphragm comprises a diaphragm body formed from a composite material. The diaphragm body may comprise an interconnected structure that varies in three- dimensions. The diaphragm body may comprise a substantially low-density matrix. The diaphragm body may be formed from a low-density foam material, such as a polystyrene foam.

[0098] In an embodiment, the diaphragm is substantially thick in at least a region of the diaphragm, relative to a length and / or width dimension of the diaphragm. The diaphragm may comprise a maximum thickness that is greater than 6%, or more preferably 9% or more preferably 11% of a maximum radial length of the diaphragm from the axis of rotation. The diaphragm may comprise a maximum thickness that is greater than 7% or 10% of a greatest dimension, such as a diagonal length, of the diaphragm body.

[0099] In an embodiment, at least an end of the diaphragm is substantially thick relative to a length and / or width dimension of the diaphragm. Preferably the substantially thick end of the diaphragm is mechanically coupled to the end of the armature. Preferably the substantially thick end of the diaphragm is mechanically coupled to the lateral cross-member of the armature. In an embodiment the maximum diaphragm thickness is greater than 30% of the maximum transducer thickness or more preferably greater than 35% of the maximum transducer thickness or most preferably greater than 40% of the maximum thickness of the transducer.

[0100] In an embodiment the maximum diaphragm thickness is greater than 25% of the maximum transducer thickness or more preferably greater than 30% of the maximum transducer thickness or most preferably greater than 35% of the maximum thickness of the transducer excluding components (e.g. casing) that do not contribute to sound generation functions.

[0101] In an embodiment the transducer thickness comprises a majority of the depth dimension of a device incorporating the transducer, at the local region of the transducer.

[0102] In an embodiment the transducer thickness comprises at least 30% of a depth dimension of the device or more preferably at least 350% of a depth dimension of the device or most preferably at least 40% of a depth dimension of the device, at the local region of the transducer.

[0103] In an embodiment the transducer thickness comprises at least 55% of a minimum internal cavity depth dimension of the device or more preferably at least 65% of a minimum internal cavity depth dimension of the device or most preferably at least 75% of a minimum internal cavity depth dimension of the device, at the region where the transducer is located.

[0104] In an embodiment diaphragm excursion is sufficient that, when operating at maximum peak-to- peak excursion, the diaphragm’s major faces at the extremity displace, in combination, at least 30% of a depth dimension of the device or more preferably at least 35% of a depth dimension of the device or most preferably at least 40% of a depth dimension of the device, at the region where the diaphragm is located.

[0105] In an embodiment diaphragm excursion is sufficient that, when operating at maximum peak-to- peak excursion, the diaphragm’s major faces at the extremity displace, in combination, at least 55% of a minimum internal cavity depth dimension of the device or more preferably at least 65% of a minimum internal cavity depth dimension of the device or most preferably at least 75% of a minimum internal cavity depth dimension of the device, at the region where the diaphragm is located. In an embodiment the device is substantially thin.

[0106] In an embodiment the device is substantially thin in the local region of the transducer.

[0107] In an embodiment the device is substantially elongate and slender in the immediate region of the transducer.

[0108] In an embodiment the device thickness is significantly less than a maximum dimension of the device.

[0109] In an embodiment the device is a pair of wearable glasses. In an embodiment the device is a phone. In an embodiment the device is a tablet. In an embodiment the device is a personal computer.

[0110] In an embodiment a maximum transducer dimension is less than 30mm or more preferably is less than 25mm or most preferably is less than 20mm.

[0111] In an embodiment, the diaphragm comprises a diaphragm body having one or more major, radiating faces, and normal stress reinforcement coupled to the diaphragm body, the normal stress reinforcement being coupled adjacent at least one of the major, radiating faces for resisting compression- tension stresses experienced at or adjacent the face of the body during operation. Preferably the normal stress reinforcement is coupled adjacent opposing major radiating faces of the diaphragm body.

[0112] In an embodiment, the normal stress reinforcement may comprise a relatively lower mass, per unit area, in regions of the diaphragm that are distal from a centre of mass of the diaphragm relative to regions that are proximal to the centre of mass.

[0113] In an embodiment, where the diaphragm is configured to rotate relative to the transducer base structure, the normal stress reinforcement may comprise a lower mass, per unit area, in regions of the diaphragm that are distal from an axis of rotation of the diaphragm relative to regions that are proximal to the axis of rotation. In an embodiment, the normal stress reinforcement may comprise a relatively lower mass, per unit area, in regions proximal one end of the diaphragm relative to regions proximal an opposing end.

[0114] In an embodiment, a region of relatively lower normal stress reinforcement mass may comprise recesses or may be devoid of normal stress reinforcement.

[0115] In an embodiment, a region of relatively lower normal stress reinforcement mass may comprise normal stress reinforcement of reduced or reducing thickness, or reduced or reducing width, or both.

[0116] In an embodiment, a region of relatively higher normal stress reinforcement mass and / or higher diaphragm mass, comprises approximately 30-70% of a surface area of the major face, and a region of relatively lower normal stress reinforcement mass and / or lower diaphragm mass, comprises approximately 30-70% of a surface area of the major face.

[0117] In an embodiment, a region of relatively lower normal stress reinforcement mass and / or lower diaphragm mass may be located within approximately 20% of a length of the diaphragm from an end of the diaphragm that is distal to the centre of mass or that is distal to the axis of rotation of the rotating diaphragm.

[0118] In an embodiment, the diaphragm comprises a diaphragm body having one or more major, radiating faces, and at least one inner reinforcement member embedded within the body and oriented at an angle relative to at least one of said major faces for resisting and / or substantially mitigating shear deformation experienced by the body during operation. There may be a plurality of inner reinforcement members.

[0119] Hinge Features

[0120] In an embodiment, the audio transducer further comprises a hinge for rotatably coupling the armature to the transducer base structure.

[0121] In an embodiment, the hinge rotatably couples the diaphragm to the transducer base structure. In an embodiment, the hinge comprises a flexing element oriented substantially parallel to a general, major plane of the armature in a neutral rotational position of the armature and hinge.

[0122] In an embodiment, the flexing element comprises a smaller thickness relative to a thickness of the armature across the general, major plane of the armature.

[0123] In an embodiment, the flexing element is substantially coplanar to a general, major plane of the armature in a neutral rotational position of the armature and hinge.

[0124] In an embodiment, the flexing element is a substantially thin flexing plate.

[0125] In an embodiment, the plate is oriented substantially parallel to a general, major plane of the armature.

[0126] In an embodiment the flexing element comprises a torsion spring.

[0127] In an embodiment the profile of the torsion spring is substantially compact.

[0128] In an embodiment the torsion spring may comprise a substantially round or square profile.

[0129] In an embodiment the flexing element is substantially resilient.

[0130] In an embodiment, the flexing element is substantially elongate.

[0131] In an embodiment, the flexing element is coupled to a central region of the armature and extends axially towards opposing sides of the armature.

[0132] In an embodiment, the flexing element is coupled to a central region of the armature and extends from the central region along the axis of rotation towards opposing sides of the armature.

[0133] In an embodiment, the flexing element is coupled to a connection tab of the armature and longitudinally extends along the axis of rotation. Preferably the connection tab is substantially centrally located along a width dimension of the armature, along the axis of rotation.

[0134] In an embodiment, the hinge is rigidly coupled to the transducer base structure. In an embodiment the hinge comprises a flexible metal element. Preferably the hinge is a flexible metal spring.

[0135] In an embodiment the hinge is formed by a process comprising stamping and / or pressing of a metal sheet. In an embodiment the hinge is formed by an electrical discharge machining (EDM) process. In an embodiment the hinge surface is modified via powder blasting to improve mechanical properties of the surface.

[0136] In an embodiment the hinge comprises a metal plate that is attached to the armature assembly and / or to the transducer base structure by a process of welding.

[0137] In an embodiment the armature and hinge comprise similar composition to facilitate welding. In an embodiment the armature is annealed. In an embodiment the hinge is hardened. In an embodiment processing of the hinge improves the yield stress.

[0138] In an embodiment the armature primarily comprises iron. In an embodiment the hinge primarily comprises iron. In an embodiment the armature primarily comprises a combination of iron and cobalt. In an embodiment the hinge primarily comprises a combination of iron and cobalt.

[0139] In an embodiment, the diaphragm comprises a recess, and the hinge is located at least partially within the diaphragm recess. In an embodiment, the recess is formed at a base end of the diaphragm.

[0140] In an embodiment, the axis of rotation of the diaphragm is substantially contained in a first imaginary plane that is substantially perpendicular to a second imaginary plane of the diaphragm containing the radial axis of the diaphragm, and that contains / intersects the node axis of the diaphragm, the node axis being a second axis of rotation about which the diaphragm would rotate relative to the transducer base structure if: the diaphragm is effectively substantially unsupported by the diaphragm suspension system, and the diaphragm is subjected to the mechanical force(s) associated with the transducing mechanism, in-use.

[0141] In a twelfth aspect, the invention may broadly be said to consist of an apparatus, comprising: an audio transducer having: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to vibration of the armature; and a body having an enclosure for accommodating the audio transducer; wherein the body of the apparatus comprises a depth dimension, and the audio transducer accommodates at least approximately 50 percent of the depth dimension of the body.

[0142] In an embodiment the audio transducer accommodates at least approximately 60 percent of the depth dimension of the body.

[0143] In an embodiment, the audio transducer accommodates at least approximately 70 percent of a depth dimension of the body.

[0144] In an embodiment, the apparatus comprises a smart glasses device and the body is an arm of the smart glasses device.

[0145] In a thirteenth aspect, the invention may broadly be said to consist of an apparatus, comprising: an audio transducer having: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to vibration of the armature; and a body having an enclosure for accommodating the audio transducer; wherein a thickness of the audio transducer is at least approximately 50 percent of a depth of the body at a region where the audio transducer is located.

[0146] In an embodiment, the thickness of the audio transducer is at least approximately 60 percent of the depth of the body at a region where the audio transducer is located.

[0147] In an embodiment, the thickness of the audio transducer is at least approximately 70 percent of the depth of the body at a region where the audio transducer is located.

[0148] In an embodiment, the apparatus comprises a smart glasses device and the body is an arm of the smart glasses device.

[0149] In a fourteenth aspect, the invention may broadly be said to consist of an apparatus comprising: a spectacles frame with arms extending from either side of the frame; an audio loudspeaker transducer; a vent for air pressure formed in one of the arms to locate proximal to a user’s ear in use; an air channel extending along the arm to direct opposite-phase air pressure generated by the audio transducer away from the ear in use.

[0150] In a fifteenth aspect, the invention may broadly be said to consist of an apparatus comprising: a spectacles frame having an arm; an audio transducer disposed within the arm, the transducer having a first side configured to generate positive-phase sound pressure and an opposing, second side configured to generate opposite-phase sound pressure during operation; a first opening formed in portion of the arm proximal to the audio transducer and fluidly coupled to the first side of the audio transducer; an air channel extending within the arm, the air channel having an inlet fluidly coupled to the second side of the audio transducer and an outlet formed in a portion of the arm distal to the audio transducer.

[0151] Implementations of the audio transducer of the twelfth to fifteenth aspects may comprise any of the features of first to eleventh aspects, or any features of the embodiments relating to any one of the first to eleventh aspects.

[0152] Implementations of any one of the twelfth to fifteenth aspects of the invention may comprise any of the features of the following embodiments, or any combination of features from two or more of the following embodiments.

[0153] In an embodiment, a greatest dimension of the audio transducer is at least approximately 1.5times greater than a smallest dimension of the local region of the body or arm within which the transducer is disposed. More preferably the greatest dimension of the transducer is at least approximately 2 times, or at least 2.5 times, greater than the smallest dimension of the local region of the body or arm.

[0154] In an embodiment, a greatest dimension of the audio transducer is at least approximately 2 times greater than a first and smallest dimension of the local region of the body or arm within which the transducer is disposed, and at least 1.2 times greater than some second dimension of the local region of the body or arm within which the transducer is disposed, where the second dimension is orthogonal to the first dimension. More preferably the greatest dimension of the transducer is at least approximately 1.5 times greater than the second dimension of the local region of the body or arm.

[0155] In an embodiment, a greatest dimension of the audio transducer is at least approximately 2 times greater than a thickness dimension of the audio transducer. More preferably the greatest dimension of the transducer is at least approximately 2.5 times, or at least 3 times, greater than the thickness dimension of the audio transducer.

[0156] In an embodiment, a length of the audio transducer is at least approximately 2 times greater than a thickness of the transducer, and at least 1.5 times greater than a width of the audio transducer.

[0157] In an embodiment the air channel directs opposite-phase air pressure to an opposite side of the user’s pinna in use.

[0158] In an embodiment, the arm comprises a pre-auricular portion configured to be located in front of a user’s ear when the apparatus is worn, and a post-auricular portion configured to extend behind a user’s ear when worn, and wherein the outlet of the air channel is formed in the post-auricular portion of the arm.

[0159] In an embodiment the air channel directs opposite-phase air pressure to an opening / outlet located at least 10mm, and more preferably at least 15mm behind the point of contact between the arm and the top-inner part of an average user’s ear.

[0160] In an embodiment the arm comprises an inward-facing side configured to face a user’s head when worn, and the air channel locates adjacent the inward- facing side of the arm.

[0161] In an embodiment, the air channel is at least partially bounded by an outer wall that forms an outer surface of the arm, and wherein the outer wall has a convex profile.

[0162] In an embodiment, the outlet of the air channel comprises a plurality of apertures or vents distributed along a length of the arm. In an embodiment, a surface area of the apertures progressively increases with increasing distance from the transducer.

[0163] In an embodiment the air channel comprises one or more resistive acoustic elements located at one or more locations along the channel's length. In an embodiment the acoustic resistive element comprises a fibrous pad.

[0164] In an embodiment the diaphragm gets progressively thinner, moving in a direction parallel to the axis of rotation. In an embodiment, an air vent, or part of an air vent, is positioned adjacent to the thinned side region of the diaphragm.

[0165] In an embodiment, a path length across a gap, formed between the diaphragm and a diaphragm surround, varies based on a displacement position of the diaphragm.

[0166] In an embodiment, the path length across the gap increases as the diaphragm moves from a neutral position toward an extreme position of its excursion.

[0167] In an embodiment, the variation in the path length is caused by a shaped profile of the inner peripheral wall of the diaphragm surround and / or the outer peripheral wall of the diaphragm.

[0168] In an embodiment, the outer peripheral edge of the diaphragm and the inner periphery of the diaphragm surround are cooperatively shaped to increase a path length across a gap therebetween as the diaphragm moves from a neutral position toward an extreme position of its excursion.

[0169] In an embodiment, shaping of the tightly fitting diaphragm surround causes the path length across the narrow sealing diaphragm to diaphragm surround gap region to vary as the diaphragm displaces.

[0170] In a sixteenth aspect, the invention may broadly be said to consist of an apparatus comprising: an audio device housing; an audio transducer disposed within the frame, the transducer having a diaphragm, the diaphragm having a first face configured to generate positive-phase sound pressure and an opposing, second face configured to generate opposite-phase sound pressure during operation; a first opening formed in portion of the arm proximal to the audio transducer and fluidly coupled to the first side of the audio transducer; a first metal component or assembly traversing the first face of the diaphragm generating sound pressure; a second metal component or assembly traversing the second face of the diaphragm; where the first and second metal components meet and are joined at at least two sides of the diaphragm.

[0171] In an embodiment the first metal component or assembly comprises a ferromagnetic metal.

[0172] In an embodiment the first metal component or assembly is located substantially proximal to an outside face of the transducer. In an embodiment the first metal component or assembly is located at an outside face of the transducer.

[0173] In an embodiment the first and / or second metal component or assembly / assemblies comprise(s) perforations to permit fluid to pass through.

[0174] In an embodiment the first and second metal components or assemblies are joined via a strong joint capable of sustaining high load comparable to the load sustainable by the first and second components or assemblies. In an embodiment the first and second metal components or assemblies are joined via a strong joint capable of sustaining high load comparable to the load sustainable by the first and second components or assemblies, in the case that a bending load is applied across the maximum length of the transducer.

[0175] In an embodiment the first and second metal components or assemblies form a continuous metal assembly wrapping around the transducer, with the exception of any localised perforations. In an embodiment the first and second metal components or assemblies are joined together by using metal welding process.

[0176] Implementations of the audio transducer of the sixteenth aspect may comprise any of the features of first to eleventh aspects, or any features of the embodiments relating to any one of the first to eleventh aspects.

[0177] Implementations of the sixteenth aspect may comprise any of the features of the twelfth to fifteenth aspects, or any features of the embodiments relating to any of the twelfth to fifteenth aspects.

[0178] In a seventeenth aspect, the invention may broadly be said to consist of an apparatus, comprising: a substantially narrow housing, wherein a length and / or width of the housing is substantially greater than a thickness thereof; a diaphragm, the diaphragm having a first major face configured to generate positivephase sound pressure and an opposing second major face configured to generate opposite-phase sound pressure; a transducing mechanism operatively coupled to the diaphragm and configured to convert between electrical signals and mechanical vibration of the diaphragm; and a metallic enclosure substantially encapsulating at least the diaphragm, wherein the metallic enclosure is an integrally formed unit and defines a cavity shaped to provide a minimal operational clearance sufficient to accommodate a full range of motion of the diaphragm during operation; and wherein the metallic enclosure comprises at least one aperture positioned to align with the first and / or second major face of the diaphragm to provide an acoustic pathway between the diaphragm and an exterior of the enclosure. In an embodiment, the housing comprises a housing aperture aligned with the enclosure aperture to provide an acoustic pathway from the diaphragm to an exterior of the housing.

[0179] In an embodiment, the metallic enclosure and the housing are joined at one or more junction regions, and wherein at least one of said junction regions comprises a progressive decrease in a wall thickness of the housing in a direction towards the metallic enclosure.

[0180] In an embodiment, the progressive decrease in the wall thickness is formed by a plurality of discrete steps.

[0181] In an embodiment, the progressive decrease in the wall thickness is formed by a substantially continuous and smooth taper.

[0182] In an embodiment, a plurality of said junction regions comprise the progressive decrease in the wall thickness of the housing.

[0183] In an embodiment, the metallic enclosure comprises at least one profiled edge region configured to join with the housing at one of the junction region(s), and wherein at least one of the said profiled edge region(s) is shaped to facilitate a progressive decrease in the wall thickness of the housing at the junction.

[0184] In an embodiment, at least one of said profiled edge region(s) is formed by an inwardly angled wall of the metallic enclosure, the wall extending toward the cavity of the metallic enclosure.

[0185] In an embodiment, at least one of said profiled edge region(s) has a variable wall thickness.

[0186] In an embodiment, the variable wall thickness is formed by one or more recesses, creating a stepped profile.

[0187] In an embodiment, the variable wall thickness is formed by a substantially continuous taper.

[0188] In an embodiment, wherein the substantially continuous taper is substantially smooth.

[0189] In an embodiment, the metallic enclosure comprises: a first face-plate positioned adjacent the first major face of the diaphragm; a second face-plate positioned adjacent the second major face of the diaphragm; and at least one side wall extending between and connecting the first and second face-plates.

[0190] In an embodiment, at least one of said profiled edge region(s) is located on at least one of the first face-plate or the second face-plate.

[0191] In an embodiment, at least one said profiled edge region(s) is located on the first face-plate and at least one said profiled edge region(s) is located on the second face-plate.

[0192] In an embodiment, at least one of said at least one profiled edge region is located on the at least one side wall.

[0193] In an embodiment, the at least one side wall comprises a plurality of side walls, and wherein the at least one profiled edge region is located on each of the plurality of side walls.

[0194] In an embodiment, the metallic enclosure comprises two opposing ends defined along a longitudinal axis thereof, and wherein at least one of said at least one profiled edge region is located on at least one of the two opposing ends.

[0195] In an embodiment, the at least one profiled edge region is located on both of the two opposing ends.

[0196] In an embodiment, the metallic enclosure further comprises an extension plate extending longitudinally from a terminal end of the metallic enclosure.

[0197] In an embodiment, the extension plate extends beyond a region occupied by the audio transducer.

[0198] In an embodiment, the extension plate is inwardly angled or curved.

[0199] In an embodiment, one or more parts of the extension plate tapers in width toward a distal end thereof.

[0200] In an embodiment, the at least profiled edge region is formed from a material having a young’s modulus that is greater than 10 GPa. In an embodiment, the at least profiled edge region is formed from a material having a young’s modulus that is greater than 20 GPa.

[0201] In an embodiment, the apparatus housing is formed from a first material adjacent to the transducer assembly, and the metallic enclosure is formed from a second material, and wherein the second material has a higher yield strength than the first material.

[0202] In an embodiment, a young’s modulus of the second material is at least ten times greater than the young’s modulus of the first material.

[0203] In an embodiment, the metallic enclosure has a first bending stiffness, and wherein a portion of the housing adjacent the metallic enclosure has a second bending stiffness that is less than the first bending stiffness.

[0204] In an embodiment, the first bending stiffness is at least five times greater than the second bending stiffness.

[0205] In an embodiment, the apparatus housing comprises a plastics material adjacent the transducer assembly.

[0206] In an embodiment, the apparatus housing has a wall thickness of less than 1.2mm adjacent the transducer assembly.

[0207] In an embodiment, the apparatus housing has a wall thickness of less than 1 mm adjacent the transducer assembly.

[0208] In an embodiment, the apparatus housing has a wall thickness of less than 0.8 mm adjacent the transducer assembly.

[0209] In an embodiment, the metallic enclosure is a single, unitary component.

[0210] In another embodiment, the metallic enclosure comprises at least two separate components metallurgically bonded together.

[0211] In an embodiment, at least a portion of the metallic enclosure comprises a ferromagnetic metal. In an embodiment, the at least one aperture comprises: one or more first apertures positioned to align with the first major face of the diaphragm, and one or more second apertures positioned to align with the second major face of the diaphragm.

[0212] In an embodiment, the metallic enclosure forms a substantially continuous shell, interrupted only by the at least one aperture.

[0213] In an embodiment, the metallic enclosure forms at least a portion of the transducing mechanism.

[0214] In an embodiment, the metallic enclosure forms at least a portion of a magnetic structure of the transducing mechanism.

[0215] In an embodiment, the metallic enclosure is rigidly coupled to and extends from a component of the transducing mechanism.

[0216] In an embodiment, the metallic enclosure and at least a portion of the transducing mechanism are formed as a single, integral component.

[0217] In an embodiment, the axis of rotation of the diaphragm is substantially contained in a first imaginary plane that is substantially perpendicular to a second imaginary plane of the diaphragm containing the radial axis of the diaphragm, and that contains / intersects the node axis of the diaphragm, the node axis being a second axis of rotation about which the diaphragm would rotate relative to the transducer base structure if: the diaphragm is effectively substantially unsupported by the diaphragm suspension system, and the diaphragm is subjected to the mechanical force(s) associated with the transducing mechanism, in-use.

[0218] In an embodiment perforations are arranged so as to preserve structural triangulation. In an embodiment transducer overall thickness generally tapers towards one or more ends. In an embodiment the tapering thickness is associated with a corresponding and / or complementary increase in body wall thickness. In an embodiment the body is substantially formed from a plastics material. In an embodiment the typical body wall thickness over central structural elements of the transducer is less than 1.2mm, more preferably less than 1mm and most preferably less than 0.8mm. In an embodiment, when bending loads are applied to the body, in the region of the transducer, deformation is resisted predominantly by the transducer. In an embodiment, a greatest dimension of the audio transducer is at least approximately 2 times greater than a smallest dimension of the audio transducer. More preferably the greatest dimension of the transducer is at least approximately 2.5 times, or at least 3 times, greater than the smallest dimension of the audio transducer.

[0219] In an embodiment, a length of the audio transducer is at least approximately 2 times greater than a thickness of the transducer, and at least 1.5 times greater than a width of the audio transducer.

[0220] Implementations of the audio transducer of the seventeenth aspect may comprise any of the features of first to eleventh aspects, or any features of the embodiments relating to any one of the first to eleventh aspects.

[0221] Implementations of the seventeenth aspect may comprise any of the features of the twelfth to sixteenth aspects, or any features of the embodiments relating to any of the twelfth to sixteenth aspects.

[0222] In an eighteenth aspect, the invention may broadly be said to consist of an apparatus comprising: an audio transducer; a body having an enclosure for accommodating the audio transducer; wherein the body of the apparatus comprises a depth dimension that, at least in the local region of the transducer, is small relative to a maximum dimension of the body; wherein the audio transducer accommodates at least 30% of a depth dimension of the body, at the local region of the transducer; a wall of the body is attached to the transducer over one or more areas including towards at least a first end of the transducer; overall wall thickness of the body increases towards at least one end of the transducer. In an embodiment, the audio transducer accommodates at least 35% of a depth dimension of the body.

[0223] In an embodiment, the audio transducer accommodates at least 40% of a depth dimension of the body.

[0224] In an embodiment, an overall wall thickness of the body increases towards at least two ends of the transducer.

[0225] In an embodiment, one or more increases in overall wall thickness of the body towards one or more ends of the transducer are associated with a complementary decrease in transducer thickness towards the one or more ends of the transducer, compared to transducer thickness in one or more central regions;

[0226] In an embodiment significant parts of the transducer and body are attached to one-another across regions where the thickness of the body increases towards the end(s) of the transducer.

[0227] In an embodiment the transducer thickness comprises at least 55% of a minimum internal cavity depth dimension of the body or more preferably at least 65% of a minimum internal cavity depth dimension of the body or most preferably at least 75% of a minimum internal cavity depth dimension of the body, at the region where the transducer is located.

[0228] In an embodiment one or more structural components of the audio transducer comprises a Young’s modulus that is significantly higher compared to structural components of the body in the region of the transducer.

[0229] In an embodiment one or more structural components of the audio transducer comprises a metal.

[0230] In an embodiment structural components of the body comprise a plastics material, in the region of the transducer.

[0231] In an embodiment the overall form of the body forms relatively straight outermost surfaces oriented in a direction that is substantially parallel to a maximum dimension of the transducer and / or body. In an embodiment the overall transducer thickness decreases towards at least two ends, compared to in one or more central regions.

[0232] In an embodiment the overall transducer thickness decrease is at least partly associated with an incremental thickness reduction that progresses as one nears said end of the transducer.

[0233] In an embodiment the overall transducer thickness decrease results at least partly from tapering, in a direction perpendicular to the depth dimension, of one or more transducer regions and / or components and / or assemblies, as one nears said end of the transducer.

[0234] In an embodiment the transducer features one or more regions extending beyond the extent required for sound generation and / or mounting functions. In an embodiment the one or more regions serves a purpose of increasing adhesion area to the body. In an embodiment the one or more regions serves a purpose of minimising stress raisers in the body, in the case that bending or other external loads are applied to the device.

[0235] Overall transducer thickness decrease at at least one end of the transducer is a result of an inwards curving of the outer profile relative to one or more central regions.

[0236] In an embodiment both the body of the apparatus and the transducer are relatively long in a first dimension and thin both in a second dimension, being the depth dimension, and in a third dimension, at least in the local region of the transducer, and the three dimensions are mutually orthogonal.

[0237] In an embodiment the transducer’s dimension decreases in both the second and third dimensions towards a first end of the transducer, where the first end of the transducer faces in a direction parallel to the first dimension. In an embodiment the transducer’s dimension decreases in both the second and third dimensions towards a second end of the transducer, where the second end of the transducer faces in a direction parallel to the first dimension and opposed to the first end.

[0238] Implementations of the audio transducer of the eighteenth aspect may comprise any of the features of first to eleventh aspects, or any features of the embodiments relating to any one of the first to eleventh aspects. Implementations of the eighteenth aspect may comprise any of the features of the twelfth to seventeenth aspects, or any features of the embodiments relating to any of the twelfth to seventeenth aspects.

[0239] In a nineteenth aspect, the invention may broadly be said to consist of an apparatus, comprising: a substantially narrow housing, wherein a length and / or width of the housing is substantially greater than a depth thereof; and an audio transducer assembly disposed within the housing and comprising: a diaphragm, the diaphragm having a first major face configured to generate positive-phase sound pressure and an opposing second major face configured to generate opposite-phase sound pressure; a transducing mechanism operatively coupled to the diaphragm and configured to convert between electrical signals and mechanical vibration of the diaphragm; wherein, the housing comprises a housing aperture aligned with the diaphragm to provide an acoustic pathway from the diaphragm to an exterior of the housing; and wherein, the audio transducer assembly and the housing are joined at one or more junction regions, and wherein at least one of said junction regions comprises a progressive decrease in a wall thickness of the housing in a direction toward the audio transducer assembly.

[0240] Implementations of the audio transducer of the nineteenth aspect may comprise any of the features of first to eleventh aspects, or any features of the embodiments relating to any one of the first to eleventh aspects.

[0241] Implementations of the nineteenth aspect may comprise any of the features of the twelfth to eighteenth aspects, or any features of the embodiments relating to any of the twelfth to eighteenth aspects. In a twentieth aspect, the invention may broadly be said to consist of an audio transducer comprising: a transducer base structure; a diaphragm; a transducing mechanism operatively coupled to the diaphragm and configured to convert between electrical signals and mechanical vibration of the diaphragm; a hinge pivotally coupling the diaphragm to the transducer base structure, and having at least one elongate, flexible, and resilient element extending in a direction substantially parallel to the axis of rotation between attachment points to the armature assembly and to transducer base structure.

[0242] Implementations of the audio transducer of the twentieth aspect may comprise any of the features of first to eleventh aspects, or any features of the embodiments relating to any one of the first to eleventh aspects.

[0243] Implementations of the twentieth aspect may comprise any of the features of the twelfth to nineteenth aspects, or any features of the embodiments relating to any of the twelfth to nineteenth aspects.

[0244] Reference to “any of the features” in the above statements means any combination of one or more of such features.

[0245] The term “comprising” as used in this specification and claims means “consisting at least in part of.” When interpreting each statement in this specification and claims that includes the term “comprising,” features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner. Number Ranges

[0246] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

[0247] As used herein the term “and / or” means “and” or “or,” or both.

[0248] As used herein “(s)” following a noun means the plural and / or singular forms of the noun.

[0249] The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

[0250] BRIEF DESCRIPTION OF THE DRAWINGS

[0251] Various embodiments of the present disclosure will be described by way of example only and with reference to the drawings, in which:

[0252] Figs. 1A & IB are different perspective views of a smart glasses device embodiment incorporating an armature-type audio transducer;

[0253] Fig. 1C shows a perspective view of a part of the device of Fig. 1A accommodating the audio transducer;

[0254] Fig. ID shows an exploded perspective view of the part of the device of Fig. 1C;

[0255] Fig. IE shows a front view of the part of the device incorporating the transducer of Fig. 1C;

[0256] Fig. IF shows a side view of the part of the device incorporating the transducer of Fig. 1C;

[0257] Fig. 1G shows a cross-sectional view across section H-H of Fig. IF; Fig. 1H shows a cross-section view across section A- A of Fig. IE;

[0258] Fig 2A shows a perspective view of a first embodiment audio transducer;

[0259] Fig. 2B shows a side view of the first embodiment audio transducer of Fig. 2A;

[0260] Fig. 2C shows a cross-sectional view across section B-B of Fig. 2B;

[0261] Fig. 2D shows a cross-sectional view across section C-C of Fig. 2B;

[0262] Fig. 2E shows an end view of the first embodiment audio transducer;

[0263] Fig. 2F shows a cross-sectional view across section D-D of Fig. 2E;

[0264] Fig. 2G shows a close-up view of the transducing mechanism shown in Fig. 2F;

[0265] Fig. 2H shows another close-up view of the transducing mechanism shown in Fig. 2H;

[0266] Fig. 21 shows a cross-sectional view across section E-E of Fig. 2E;

[0267] Fig. 2J is an exploded perspective view of the first embodiment audio transducer;

[0268] Figs. 3A & 3B are perspective views of a hinge mechanism coupled to the armature of the first embodiment audio transducer of Fig. 2A;

[0269] Fig. 3C is a bottom view of the hinge mechanism of Fig. 3 A;

[0270] Fig. 3D is a top view of the hinge mechanism of Fig. 3 A;

[0271] Fig. 3E shows a cross-sectional view across section F-F of Fig. 3C;

[0272] Fig. 3F shows a cross-sectional view across section G-G of Fig. 3C;

[0273] Figs 4A & 4B show close up views of an alternative transducing mechanism of a second embodiment audio transducer;

[0274] Fig. 5A is a perspective view of a further exemplary embodiment of an audio transducer assembly of the present disclosure; Fig. 5B is an end view of the audio transducer assembly of Fig. 5A;

[0275] Fig. 5C is a side view of the audio transducer assembly of Fig. 5 A;

[0276] Fig. 5D is a top view of the audio transducer assembly of Fig. 5 A;

[0277] Fig. 6A shows a perspective view of a part of an exemplary apparatus with the transducer assembly of Fig. 5 A embedded therein;

[0278] Fig. 6B is a side view of the part of the apparatus of Fig. 6A;

[0279] Fig. 6C is a cross-sectional view of a part of the apparatus of Fig. 6A;

[0280] Fig. 6D is a close-up view from the cross-section of Fig. 6C;

[0281] Figs. 7A -7F show various views of a further illustrative audio transducer embodiment of the present disclosure; and

[0282] Figs. 8A - 8D show various views of a further illustrative apparatus with the transducer assembly of Figs. 7A-7F embedded therein.

[0283] DETAILED DESCRIPTION

[0284] Various aspects and examples (herein also referred to as “embodiments” or “implementations”) of audio transducers, and associated devices and systems in which they may be incorporated, are described below and illustrated in the associated drawings. Unless otherwise specified, an audio transducer or device in accordance with the present teachings, and / or its various components, may contain any combination of one or more of the structures, components, functionalities, and / or variations described, illustrated, and / or incorporated herein.

[0285] Furthermore, unless specifically excluded, the structures, components, functionalities, and / or variations described, illustrated, and / or incorporated herein in connection with the present teachings may be included in other similar devices and methods, including being interchangeable between disclosed embodiments. The following description of various examples is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. Additionally, the advantages provided by the examples and embodiments described below are illustrative in nature, and not all examples and embodiments provide the same advantages or the same degree of advantages.

[0286] This Detailed Description includes the following sections 1-10, which describe exemplary devices and audio transducers which may be incorporated therein:

[0287] 1. Overview of armature-type audio transducers and small form factor devices incorporating the same

[0288] In each of the audio transducer embodiments herein described the audio transducer comprises a diaphragm that is movably coupled relative to a base (also referred to as a transducer base structure). The base may be integral with or form part of a housing, support or baffle of a device incorporating the transducer in some implementations. In other implementations, it is formed separately and may be coupled to another supporting structure, such as a housing or baffle of a device incorporating the transducer. Unless stated otherwise, the diaphragm is substantially rigid, and remains rigid during operation, and the base is substantially rigid and remains rigid during operation. The base preferably has a relatively higher mass than the diaphragm, or a higher effective mass when rigidly connected or integrated in another structure such as a housing.

[0289] In each of the audio transducer embodiments herein described, the audio transducer further comprises a transducing mechanism, associated with the diaphragm, and configured to receive electrical audio signal(s) and to move the diaphragm in response to the received electrical audio signal(s). In this specification, a transducing mechanism may also be referred to as an excitation mechanism or motor.

[0290] In some of the embodiments herein disclosed, the transducing mechanism is an armature-type, electromagnetic transducing mechanism having a magnetic structure configured to generate a static magnetic field, an armature, and at least one conductive coil wrapped about the armature (herein referred to as “coil”). The armature comprises a ferromagnetic body that comprises a main body component or portion suspended within the static magnetic field. The coil surrounds at least a section of the main body of the armature, and the main body also extends at least partially within the static magnetic field generated by the magnetic structure. The coil is configured to receive electrical audio signals and generate a varying magnetic field through the main body of the armature, causing the armature to interact with the static magnetic field and vibrate therewithin based on the received audio signals. The magnetic structure comprises one or more magnetic bodies configured to generate the static magnetic field, and preferably direct and concentrate the field within a desired region of the audio transducer. The magnetic bodies may comprise permanent magnets and / or ferromagnetic bodies. The diaphragm is mechanically coupled to the armature to oscillate based on the armature’s vibration, and accordingly generate sound pressure representative of the received electrical audio signal. The diaphragm is preferably rigidly coupled to the armature.

[0291] The armature is rotatably coupled relative to the transducer base structure via an armature suspension. The diaphragm is rotatably coupled relative to the transducer base structure via a diaphragm suspension. In some embodiments, the armature and diaphragm oscillate about the same axis of rotation. The armature suspension and diaphragm suspension may be the same or share similar components to achieve the desired effect of rotating both armature and diaphragm about the same axis of rotation. Alternatively, the armature suspension and the diaphragm suspension may be separate suspension systems. In some implementations, the armature and diaphragm may oscillate about different axes of rotation.

[0292] In other embodiments, the transducing mechanism may be a more conventional electromagnetic transducing mechanism. An electromagnetic transducing mechanism typically comprises a magnet or magnetic structure or body configured to generate a magnetic field, and at least one conductive coil (herein referred to as “coil”) configured to locate within the magnetic field and move in response to received electrical signals (in the case of an electroacoustic transducer), or generate electrical signals in response to movement (in the case of an acoustoelectric transducer). As the electromagnetic transducing mechanism does not require physical coupling between the magnet and the coil, generally one part of the mechanism will be coupled to the base, and the other part of the mechanism will be coupled to the diaphragm structure. In some embodiments, the magnet is coupled to, or forms part of the transducer base structure and the coil is coupled to or forms part of the diaphragm structure. In other embodiments, the magnet is coupled to, or forms part of the diaphragm structure and the coil is coupled to or forms part of the transducer base structure. An electromagnetic transducing mechanism will typically comprise magnetic and / or ferromagnetic components coupled to the diaphragm and the transducer base structure.

[0293] In some embodiments, alternative transducing mechanisms such as piezoelectric, electrostatic, magnetostrictive or other suitable mechanisms known in the art, may be incorporated in the audio transducer embodiments described herein.

[0294] In some embodiments, the audio transducer may be accommodated with a housing or surround to form an audio transducer assembly, which may also be integral with a device or part of a device, such as part of an earphone, hearing aid, in ear monitor, a mobile phone, or a smart glasses device. In some embodiments, the transducer base structure may be rigidly connected or integral with the housing or surround of an audio transducer assembly or device.

[0295] The audio transducer embodiments described herein may be incorporated into a wide variety of devices and systems. They are particularly advantageous for applications where space constraints are a significant consideration, such as devices that require a thin, slender, or otherwise compact form factor without compromising on audio performance, such as volume excursion and low or wide frequency response.

[0296] Examples of such devices may include, but are not limited to, wearable electronics and portable consumer electronics. For instance, in wearable devices such as smart glasses, earphones, in-ear monitors, or hearing aids, the compact and lightweight nature of the transducer allows for integration into a device worn on or against a user's head. Similarly, in portable electronic devices like mobile phones, tablets, or laptop computers, the transducer's thin profile is particularly suitable for inclusion within increasingly slender device chassis. An exemplary device, in the form of a smart glasses device incorporating an armature-type audio transducer as described above, will be described in detail herein to illustrate an exemplary implementation of the structural and functional features of one such device.

[0297] The device and audio transducer embodiments described herein each incorporate certain combinations of one or more of various features, structures, assemblies, mechanisms, devices, or systems which may be incorporated in other combinations to form alternative embodiments under the present disclosure. 2. Illustrative smart glasses device Al 00

[0298] Referring to Figs. 1A and IB, an embodiment of a smart glasses device Al 00 of the present disclosure will now be described. The smart glasses device Al 00 may be implemented according to the twelfth and fifteenth aspects described in the summary of invention section of the present disclosure, for instance. Variations of this embodiment may be implemented in accordance with only one of these aspects without departing from the scope of this disclosure.

[0299] The smart glasses device Al 00 comprises an armature-type audio transducer A200 (shown in Fig. 2A) accommodated therein, and having features as described in the overview section of this detailed description. Alternatively, the audio transducer A400 (shown in Fig. 4A) described herein may be implemented in the device Al 00. The smart glasses device Al 00 comprises a frame Al 05 and left and right-side arms with main bodies AlOla and AlOlb extending from the frame A105. The left and right-side arm bodies AlOla and AlOlb provide structural support and housing for the internal components of the smart device A100. Corresponding arm caps A102a, A102b may be configured to couple over the associated left and right-side arm bodies A101, AlOlb to provide a protective enclosure for the internal components housed within the arm bodies A101, AlOlb. In alternative embodiments, each arm body may be formed as a single, unitary enclosure without a separate cap.

[0300] To facilitate the emission of sound, each arm comprises one or more acoustic openings A103, Al 07, Al 08. The acoustic opening may be positioned adjacent the audio transducer A200 and provide a path for the sound pressure generated by the transducer to travel to the user's ear and the surrounding environment.

[0301] In the illustrated embodiment, the acoustic openings are implemented as grilles on multiple surfaces of each arm, including an outer side grille (A103a / b), a top side grille (A107a / b), and a corresponding bottom side grille (A108a / b). It will be appreciated that in other embodiments, the acoustic opening could take other forms, such as a single port or a series of perforations, and may be located on any combination of the arm's surfaces to achieve the desired acoustic performance. For instance, an embodiment may feature a single port or grille on only one surface, such as the outer side grille (A103a / b), while other surfaces of the arm remain substantially closed. In other variations, any combination of top, bottom, and side openings may be implemented to achieve the desired acoustic performance. Venting at the inner-facing side (vent option not shown) and / or bottom facing Al 08 openings may provide aesthetic advantage, being substantially hidden from view in-use. Regardless of the specific configuration, these acoustic openings form the primary outlet for the sound produced by the transducer A200. In some embodiments only one or two of the sides of the base component and top cover comprise the grilles adjacent the transducer A200, with other sides being substantially closed adjacent the transducer A200.

[0302] In the illustrated implementation, the outer-side grille Al 03a, b is integrated into a major side or face of the respective arm, such as the same side as the respective cap Al 02a, Al 02b. The outerside grille Al 03a, b locates at or adjacent the audio transducer incorporated in the corresponding arm body AlOla, AlOlb. As mentioned, this arrangement allows sound to pass directly through and out of the grille Al 03a, Al 03b. Addition of water repellent mesh fabric (not shown) protects the internal components of the corresponding transducer from external elements.

[0303] The main body of each arm AlOla, AlOlb further comprises a top side grille Al 07a, Al 07b, and a bottom side grille Al 08a, Al 08b on the minor opposing surfaces of the arm. These additional grilles allow for further transmission of sound from the internal audio transducer to the environment surrounding the user's ears. It will be appreciated in alternative embodiments any combination of one or more of the grilles A103, A107a / b, A108a / b, and inner-facing side (option not shown) may be implemented in each of the arms of the smart glasses device Al 00.

[0304] In this exemplary implementation, the acoustic openings (e.g., grilles Al 03, A107a / b, A108a / b) locate directly adjacent or directly overlie the corresponding audio transducer. In particular, the acoustic openings Al 03 may locate directly adjacent or directly overlie the diaphragm of the audio transducer to provide a direct and unobstructed path for the sound pressure generated by the diaphragm’s movement to be emitted into the surrounding environment. In an alternative embodiment sound may be transmitted to the listener via a second cavity. In this case it is preferable that the cavity length is not too long, to minimise the number of acoustic resonance modes in the pathway between transducer and user. A terminal free end of each glasses arm Al 04a, Al 04b, is shaped with a downward curve to form an earpiece, which is configured to fit comfortably behind a user's ears and enable a user to wear the smart glasses device Al 00 securely on their head. An opposing front region Al 06a, Al 06b of each glasses arm is coupled to a hinge, which pivotally connects the arm to the front frame Al 05 of the glasses Al 00 and allows the arm to be folded, for example for storage or transport.

[0305] Figs. 1C-1H show a close-up view of one of the arms AlOla, AlOlb, which is herein referenced AlOlto indicate that the features described and shown in the figures apply generally to either one of the arms AlOlb, AlOlb, and preferably to both. The illustrated section of arm A101 comprises an internal cavity for accommodating the audio transducer, such as the audio transducer A200 or A400 of the present disclosure. The acoustic openings Al 03, Al 07 and Al 08 previously described may locate adjacent this internal cavity accommodating the transducer, for instance.

[0306] In this illustrated example, the section of the arm Al 01 incorporating the audio transducer is substantially thin and also slender. Accordingly, the thickness Al l i of device Al 00 is substantially smaller than an overall, maximum dimension of the device A100. This is the case for a pair of glasses as in this embodiment but could also be the case for a device such as a mobile phone, a tablet, or a personal computer. For example, the thickness Al l i in this region may be less than 10% of the overall length of the smart glasses frame or the overall length of the arm Al 01. Likewise the width Al 12 may be less than 50% of the overall length.

[0307] The cross-sectional form factor of this region of the device Al 00 may be minimised in general. For instance, the internal cavity or region of the device body adjacent each transducer may comprise a maximum width Al 12 of approximately 6.2mm and a maximum thickness Al l i of approximately 3.2mm. The device internal cavity, bounded by two side walls of the main body Al 01, may have an internal maximum width Al 14 of approximately 5.7mm and an internal maximum thickness Al 13 of approximately 2.3mm, for example. It will be appreciated that these values are exemplary and can be varied to suit the particular application.

[0308] In this exemplary implementation, the transducer's length?? is maximised relative to the slim profile of the arm Al 01, ensuring that the largest possible motor and diaphragm are integrated into the available space. This is achieved by designing the transducer thickness A221 to constitute a significant portion of both the overall device depth Al l i and the internal cavity depth Al 13 in the region where the transducer is located. For example, the transducer thickness A221 may occupy a majority of the depth dimension Al l i of the device, at the local region of the transducer. Specific implementations may comprise a transducer thickness of at least 30% of a depth dimension of the device, or at least 35% of a depth dimension of the device, or at least 40% of a depth dimension of the device, at the local region of the transducer. Similarly, relative to the minimum internal cavity depth Al 13, the transducer thickness A221 may be at least 55%, or at least 65%, or at least 75%. Such a configuration can maximise acoustic performance, such as volume excursion and low-frequency response, within a slender form factor.

[0309] In this exemplary implementation, the elongated form factor of the transducer A200 is designed for integration within the slender arm Al 01. The greatest dimension of the transducer is substantially greater than the smallest dimension of the local region of the arm, its thickness Al l i. This ratio may be at least 1.5 times, and in some embodiments at least 2.5 times, greater.

[0310] Furthermore, the transducer's length A220 is also substantially greater than the orthogonal cross- sectional dimensions of the internal cavity of the arm. For example, the transducer's length may be at least 2 times greater than the cavity's thickness Al 13, and simultaneously at least 1.2 times greater, or more preferably at least 1.5 times greater, than the cavity's width Al 14.

[0311] An advantage of this exemplary implementation is the capacity for relatively high excursion, allowing for displacement of a large volume of air relative to the compact size. This capability is illustrated in Fig. 1 for instance, which shows dashed lines Al 14 indicating the maximum possible excursion / displacement of the diaphragm tip during operation.

[0312] In this exemplary implementation, a peak-to-peak excursion / displacement Al 15 of the diaphragm’s tip / extremity is substantial relative to the device’s slim profile. For instance, the peak-to-peak displacement (i.e., distance Al 15 between the dashed lines Al 14, which for clarity comprises maximum movement as well as the diaphragm tip region thickness Al 19) may occupy at least 30% of the total depth Al l i of the device at or adjacent the transducer, or at least 35% of the depth dimension Al 11 , or at least 40% of the depth dimension Al l i. Similarly, the peak-to- peak displacement Al 15 may occupy at least 55% of a minimum internal cavity depth Al 13, or at least 65% of the minimum internal cavity depth Al 13, or at least 75% of the minimum internal cavity depth Al 13, at the region where the diaphragm is located. This high ratio of excursion-to- depth enables the transducer to generate high-volume sound output and strong low-frequency performance from a very thin form factor.

[0313] As illustrated in Fig. 1H, significant rotational movement within a compact profile is achieved in this exemplary implementation. For instance, the maximum travel path of the diaphragm tip A201a, defined by dimension Al 15, may be approximately about 1.3mm. The corresponding maximum travel path of the armature end A208c of the transducer A200, illustrated by dashed lines Al 16, and defined by dimension Al 17, may be approximately 0.6mm.

[0314] These dimensions are advantageous when considered as a ratio relative to the overall transducer thickness Al 13. The ratio of diaphragm excursion to transducer thickness Al 15 / A113 may be approximately 0.56 in this exemplary embodiment, for instance. The diaphragm excursion ratio may be greater than 15% in some implementations. This may be indicative of the transducer's ability to produce high volume output from a very thin device.

[0315] As can be conceptualised with reference to the general arrangement shown in FIG. IF and ID, the diaphragm A201 of the embedded transducer A200 may be designed with a non-uniform thickness profile. In one such embodiment, the diaphragm body is made progressively thinner from the axis of rotation Al 09 toward the terminal end distal from the axis of rotation, one or more acoustic vents, such as a portion of the side grilles Al 07 or Al 08, may be implemented on one or both sides of the housing, directly adjacent to this thinned, side region of the diaphragm. The area of the acoustic vents may progressively decrease with the diaphragm thickness in a direction away from the axis of rotation as shown in Fig. IF for grilles 107 and 108.

[0316] In this exemplary implementation, to minimise or mitigate acoustic cancellation between the positive and opposite-phase (negative) sound pressure generated by the transducer A200 or A400, the arm Al 01 incorporates a dual-path acoustic management system, as best illustrated in the views of FIGS. 1C-1H. The desired, positive-phase sound pressure is emitted towards the user's ear through one or more acoustic openings, such as the grilles Al 03, Al 07, and Al 08. As shown in Fig. IB, these openings may be formed in a pre-auricular portion of the arm, which is the section configured to be located in front of a user's ear when the device is worn. Conversely, the opposite-phase (negative) sound pressure generated by the transducer may be managed by a dedicated air channel Al 10, formed at the bottom of the internal cavity in this implementation, as shown in FIGS. IE, 1G and 1H. The channel Al 10 has an inlet fluidly coupled to a rear side of the transducer. The channel Al 10 extends longitudinally along the arm, directing the opposite-phase (negative) pressure away from the user’s ear (in any direction) to an outlet located at a distal point. In the embodiment shown, the outlet may be formed in the post-auricular portion of the arm, for each near the terminal end Al 04a. This structural separation ensures that the oppositephase pressure is vented behind the user's pinna, which acts as a natural acoustic barrier.

[0317] To maximise the acoustic separation between the desired sound and the vented opposite-phase pressure, the outlet may be located at least 10mm, and more preferably at least 15mm, behind the typical point of contact between the arm and the top-inner part of an average user’s ear. This placement uses the pinna as an effective acoustic shield, significantly reducing sound cancellation and enhancing the perceived bass response.

[0318] Alternatively, or in addition, an outlet or vent fluidly connected to the channel Al 10 may be located at the front region Al 06 of glasses arm near the frame. The outlet may be used to vent the negative sound pressure as previously mentioned. By routing the desired positive-phase sound pressure through the acoustic openings (Al 03, Al 07, Al 08) near the ear, while simultaneously routing the opposite-phase pressure through the dedicated air channel (Al 10) to a distal outlet, cancellation between positive and negative air pressure may be minimised, thereby increasing the overall sound pressure level experienced by the user. As mentioned above, an outlet at the terminal end A 104 of the glasses arm has an advantage in that, in situ, the ear pinna provides an obstacle for the sound which means that, in terms of air pressure experienced at the ear canal, the negative sound pressure vented at the end of the glasses arm Al 04 has greater distance to travel compared to the more direct route of positive air pressure from grilles Al 03, Al 07 and Al 08 to the ear canal, leading to attenuation and reduced cancellation. As shown in Fig. IE, the air channel Al 10 may be further defined by a concavely curved inner wall and a convexly curved outer wall. The wall may be configured to locate opposite one of the major radiating faces of the diaphragm. Location of the convexly curved outer wall adjacent to the user’s head may minimise subjective impact of the associated volume In some implementations, the channel Al 10 may also be configured to accommodate electrical wiring (e.g., carrying the audio signal) for operating the transducer A200 and / or other electronic components, in an assembled state of the device Al 00.

[0319] In some alternative embodiments, the length of the air channel Al 10, and in particular the distance between the inlet and outlet of the channel may be reduced. For example, the channel outlet may be positioned to vent negative air pressure immediately behind / adjacent to the user’s pinna, as opposed to extending to the terminal end Al 04 of the glasses arm Al 01. While this configuration may decrease the acoustic path length difference between positive and oppositephase (negative) pressure waves, it offers the advantage of being less susceptible to internal air resonances that can occur within a longer channel.

[0320] Alternatively, or in addition, the air channel's outlet may be configured as a distributed venting system to provide a more controlled release of the opposite-phase air pressure. In this configuration, the outlet of the air channel Al 10 comprises a plurality of apertures or vents that are distributed along a length of the arm., connecting the channel’s Al 10 interior volume to the outside air. These apertures may be approximately 0.5mm in diameter for instance. They may be distributed at various spaced-out locations between the transducer and the most distal vents (such as those located at regions Al 04 and Al 06 of the glasses arm). The additional apertures may provide a benefit of reducing the impact of and / or improve damping of unwanted air resonance modes. These resonance modes may occur due to the length of channel Al 10 or its interaction with the other internal cavities of the device, and the venting of these air spaces to the outside air.

[0321] The size and spacing of these intermediate apertures may be varied along the channel's length to target specific resonance frequencies. For instance, the arrangement may be further refined such that the surface area of the individual apertures progressively increases with their increasing distance from the transducer. This graded sizing may create a more uniform pressure release along the channel, with smaller apertures near the transducer presenting a higher acoustic impedance and larger apertures further away providing a lower impedance path. This can help minimise turbulence and can be tuned to provide specific acoustic damping properties, improving overall audio fidelity.

[0322] Regardless of size and spacing, in some implementations, the entire series of distributed apertures may be located to ensure the opposite-phase pressure is vented effectively away from the ear canal. For example, the plurality of apertures may be formed in the post-auricular portion of the arm, ensuring that the venting occurs behind a wearer’s pinna. To maximise the acoustic separation between the desired sound and the vented opposite-phase pressure, the first aperture in this distributed series may be located at least 10mm, and more preferably at least 15mm, behind the typical point of contact between the arm and the top-inner part of an average user’s ear. This placement uses the pinna as an effective acoustic shield, significantly reducing sound cancellation and enhancing the perceived bass response.

[0323] In some implementations, to further control the acoustic properties of the air channel Al 10, particularly to mitigate unwanted resonances, the channel may incorporate one or more resistive elements. These elements are configured to introduce acoustic resistance and damp pressure oscillations within the channel. Such resistive elements may take the form of acoustic mesh, opencell foam, or felt materials strategically placed at one or more locations along the channel's length. The specific placement and resistive properties of these elements can be selected to target and suppress particular resonance modes, leading to a smoother frequency response and improved overall audio fidelity.

[0324] The structural components of the arm, including the main body Al 01 of the glasses arm Al 01 and / or the glasses arm cap Al 02, can be constructed from a variety of materials selected to optimise for properties such as weight, strength, and form factor. For example, plastics such as acetate or polycarbonate offer manufacturing flexibility and low weight. To enhance rigidity where needed, these plastics can be reinforced with composite materials, including chopped glass or carbon fibres.

[0325] Alternatively, for applications requiring maximum strength and durability, the components may be made from metals, such as titanium, or from amorphous metal alloys such as Liquidmetal and Vitreloy. An advantage of these materials is their ability to achieve high strength and durability, with a smaller wall thickness, which facilitates an even sleeker form factor of the device.

[0326] Furthermore, portions of the arm Al 01 may incorporate flexible materials, such as thermoplastic elastomers (TPE), to improve comfort and fit. These materials can also provide favourable acoustic damping, helping to mechanically decouple the transducer from the main frame and reduce unwanted resonances.

[0327] While the smart glasses device Al 00 is an exemplary application, the broader system architecture, which includes the acoustic management system, may be adapted for use in other portable audio devices. Specifically, the features of the enclosure — such as the internal cavity designed to accommodate a high-excursion transducer within a slim profile, and the dual-path acoustic system — can be implemented in other form factors. For example, in a hearing aid or in-ear monitor, the body of the device could incorporate a similar acoustic management system. A primary sound port would direct the desired, positive-phase pressure towards the ear canal. Simultaneously, a separate, integrated channel, analogous to the air channel Al 10, could extend along the body of the hearing aid or earphone to vent the opposite-phase pressure to an external surface, away from the primary sound port.

[0328] In a mobile phone, this system could be used to create a powerful micro-speaker. The phone's chassis would house the transducer, with a main speaker grille on the front or bottom edge, while an internal channel routes the opposite-phase pressure to a vent on the back or top edge of the device.

[0329] In all these applications, the implementation of this system architecture (the transducer plus its housing and venting) can overcome traditional limitations of small speakers. It may allow these devices to achieve a richer low-frequency response and higher volume output, particularly in unsealed or open-air configurations where preventing acoustic cancellation is a significant design challenge.

[0330] Other exemplary embodiments of the device Al 00 are also described in the Summary of Invention section of this disclosure. An illustrative audio transducer A200 embedded in the device Al 00 will now be described. It will be appreciated however, that alternative audio transducers may be embedded in the device, such as exemplary transducer A400, A500 or A700 also described herein.

[0331] 3. First Illustrative Audio Transducer A200

[0332] Referring to Fig. 2A-2J, an embodiment of an audio transducer A200 of the present disclosure will now be described. The following description illustrates how various inventive features of the present disclosure may be combined in a single implementation. It is to be understood that a broader invention can be defined by the general aspects outlined in the Summary of the Invention section. The audio transducer A200 is one specific example, and alternative embodiments may be constructed that incorporate the features of any single aspect (and optionally any combination of its related embodiments), or any combination of two or more aspects (and optionally any combination of their related embodiment), as described herein.

[0333] The audio transducer A200 is configured to receive electrical audio signals and convert / transduce the audio signals into mechanical vibrations to produce sound representative of the signals. The audio transducer A200 comprises a diaphragm A201 that is rotatably coupled to a transducer base structure A202 via a diaphragm suspension. The diaphragm A201 is also operatively coupled to a transducing mechanism configured to convert electrical audio signals into rotational motion of the diaphragm A201. In this embodiment, the transducing mechanism is an armature-type, electromagnetic mechanism comprising a conductive coil A210, a corresponding magnetic structure, and an armature A208. The magnetic structure generates a static magnetic field within which the armature A208 is suspended. The armature is pivotally coupled to the transducer base structure. The coil A210 is wound about the armature A208 such that it induces a varying magnetic field within the armature in response to the received electrical audio signals, in turn inducing vibration in the armature within the static magnetic field. A connection between the armature and the diaphragm causes the diaphragm to vibrate in response to vibration of the armature.

[0334] In this illustrative example, the audio transducer A200 is designed to be substantially compact. In various embodiments, a maximum overall dimension of the transducer is less than 30mm, with preferred implementations being less than 25mm, and in some cases less than 20mm, to facilitate integration into highly space-constrained devices.

[0335] Illustrative diaphragm and armature suspensions

[0336] Referring to Figs. 2H, 21 and 2J, in this exemplary implementation, the diaphragm A201 is mechanically coupled to and extends from an end of the armature A208. The diaphragm A201 is rigidly coupled to the armature. The diaphragm A201 is mechanically coupled directly adjacent to the end of the armature A208 forming a compact and efficient interface. The term “directly adjacent” in this context is intended to encompass both direct, integral connection between the armature A208 and the diaphragm, and implementations where an intermediate member, such as cross -member A209, is used to join the armature A208 and diaphragm A201 , provided that the member maintains a minimal distance therebetween. The diaphragm A201 extends from the end of the armature A208 along an axis that is substantially parallel to, or coaxial with, a longitudinal axis A222 of the armature’s main body A208a. The diaphragm extends from an end of the armature proximal to the coil. This geometric arrangement establishes a robust, unified moving assembly that is capable of pivoting as a single unit.

[0337] In this exemplary implementation, as shown in Fig. 2G, a general, major plane A223 of the diaphragm A201 is preferably substantially parallel to a general, major plane A224 of the armature main body A208a. In this specification, unless stated otherwise, reference to a general, major plane of a body (such as the diaphragm A201 or the armature A208, or armature main body A208a) refers to a plane that is aligned with the body’s most prominent dimensions, typically its length and width, and represents its general orientation. The plane typically intersects the body and divides it into two distinct and generally proportional or symmetrical segments. For a body with substantially parallel opposing surfaces, such as in the case of the armature main body, this major plane is oriented parallel to those surfaces. For a component with a tapered or wedge-shaped crosssection where the major surfaces are not parallel, such as in the case of some implementations of diaphragm A201, this major plane is understood to be the plane that centrally bisects the opposing major surfaces. In this exemplary implementation, the general, major plane A223 of the diaphragm A201 is substantially parallel but offset from a general, major plane A224 of the armature main body A208. This offset is defined across an axis that is substantially perpendicular to the general, major planes A223, A224. The offset may be minimal to maintain the overall compact profile of the transducer; for instance, it may be less than the overall thickness of the magnetic structure.

[0338] In alternative configurations, the general, major plane A223 of the diaphragm A201 may be substantially parallel to and aligned with the general, major plane A224 of the armature main body A208a; such that they are coplanar.

[0339] Both the offset and aligned configurations result in a compact transducer, with respect to its overall thickness, without compromising on high excursion capability of the diaphragm A201.

[0340] In this exemplary implementation and best shown in the exploded view of Fig. 2J, the diaphragm A201 is mechanically coupled to the armature A208 via an intermediate lateral cross-member A209. The diaphragm A201 extends from the lateral cross-member A209 at an end of the armature A208. The cross member A209 may be integrally formed with the armature A208, or it may be a separate component that is rigidly coupled to the main body A208a. The lateral cross member A209 is substantially angled, and preferably substantially orthogonal, to a longitudinal axis A222 of the main body A208a of the armature A208. In other words, the lateral crossmember A209 comprises a general, major plane that is substantially angled relative to a general, major plane A224 of the armature main body A208a and preferably, the general, major plane of the armature is substantially orthogonal to the general, major plane of the armature main body A208a. The diaphragm, in turn, couples the cross-member A209 such that its general, major plane A223 is substantially angled, and preferably substantially orthogonal to, the general, major plane of the lateral cross-member A209.

[0341] As best shown in Figs. 2G and 2H, the cross-member A209 is configured to form a T-shaped connection at an end of the armature A208. This provides a stable mounting interface for mechanically coupling with a corresponding face or surface on the base region A201f of the diaphragm A201. This structural configuration enhances the strength and rigidity of the connection between the diaphragm A201 and armature A208, ensuring that the two components move as a single, unified structure during operation.

[0342] A fundamental principle of the design is the substantial rigidity of the entire moving assembly. The lateral cross-member A209 is preferably substantially rigid, such that it does not flex during operation. The diaphragm is also substantially rigid in use, and the armature is substantially rigid in use. This ensures that the assembly moves as a single, unified body, minimising energy loss or acoustic distortion that could arise from internal flexing.

[0343] The geometric arrangement of the moving assembly is defined relative to the axis of rotation Al 09. The cross-member A209 provides the connection interface at or near this axis, joining the armature A208 and the diaphragm A201. From this interface, the armature body A208a and the diaphragm A201 extend in substantially opposing directions. In other words, the armature main body A208a extends from one side of the cross-member A209 and the diaphragm A201 extends from an opposing side of the cross-member A209. This cantilevered, seesaw-like configuration allows the small, precise pivoting motion of the armature A208 on one side of the axis to be translated into a large, sweeping motion of the diaphragm on the other side, which assists in achieving relatively high-volume excursion.

[0344] In this exemplary embodiment, as best shown in FIGS. 2F and 2G, the base region A201f of the diaphragm A201 comprises a recess A201g. This recess is shaped to accommodate both the armature's connection tab A208b and the lateral cross-member A209, allowing for a direct and rigid coupling within the diaphragm's structure.

[0345] As shown in Fig. 2F and 2G, the audio transducer A200 comprises a diaphragm suspension that flexibly and rotatably mounts the diaphragm A201 relative to a transducer base structure. The audio transducer A200 also comprises an armature suspension that flexibly and rotatably mounts the armature A208 to a transducer base structure.

[0346] In this exemplary embodiment, the suspension system for both the diaphragm A201 and the armature A208 is unified into a common hinge A211. This single hinge structure provides the flexible and rotatable mounting for the entire moving assembly relative to the transducer base structure. An advantage of this common hinge structure is that it establishes a common axis of rotation A 109 for both the armature and the diaphragm, ensuring they pivot together as a single, perfectly coordinated unit.

[0347] From this common axis of rotation Al 09, the diaphragm and armature extend in opposing directions. In alternative embodiments, the armature suspension and the diaphragm suspension may be separate and / or may comprise separate or independent hinge systems with the same or potentially different axes of rotation. It will be appreciated that the location of the mechanical coupling between the diaphragm A201 and the armature A208 may be varied in alternative embodiments. While the exemplary configuration shows the diaphragm coupled to the end of the armature proximal to the axis of rotation Al 09, it is also contemplated that the coupling could be defined relative to other components. For instance, the diaphragm may be coupled to the end of the armature that is proximal to the main magnetic bodies A204a, A204b.

[0348] In a further alternative embodiment, the positions could be inverted, with the diaphragm A201 being mechanically coupled to the distal end of the armature A208 (i.e., the free-swinging end, A208c). In such a configuration, the hinge A211 would be located at the end of the armature proximal to the coil and magnetic bodies, and the armature's main body A208a would extend between the hinge and the diaphragm.

[0349] Referring to Figs. 3A-3F, in this exemplary embodiment, the hinge A211 comprises a main flexible and resilient hinge element configured to enable rotation of the diaphragm A201, relative to a transducer base structure about a primary axis of rotation Al 09. The flexible hinge element A211 is primarily flexible along its length and substantially rigid along other dimensions, including the width and thickness of the element. In this embodiment, the element is formed as a substantially thin flexing plate resulting in a torsion spring hinge.

[0350] The flexible hinge is made from a metal such as steel, titanium, or an amorphous metal alloy such as Liquidmetal and Vitreloy, or an iron / cobalt blend. These materials are selected for their high strength, durability, resistance to creep, and are suitable for attachment methods such as spot or laser welding.

[0351] The hinge A211 may be formed by various manufacturing processes. In addition to stamping and / or pressing of a metal sheet, the hinge may also be formed by a precision process such as electrical discharge machining (EDM). Following its formation, the hinge surface can be modified, for example via powder blasting, to improve its mechanical properties and fatigue resistance.

[0352] To facilitate a robust welded connection, the armature A208 and hinge A211 may be selected to have similar primary material compositions. For instance, both components may primarily comprise iron, or in other high-performance embodiments, a combination of iron and cobalt such as Hiperco or Hiper co HS. However, since there may be different combinations of engineering objectives for each part some composition differences may be desirable. Pole pieces and armature A204 should exhibit acceptable ferromagnetic behaviour and, in some cases, sufficient structural strength, the hinge should exhibit high yield stress and fatigue resistance, and, in some cases at least, frame components such as surround A207 might require some sufficient structural strength and / or low ferromagnetism. It may be desirable for interweldability between permutations of these components.

[0353] The components may also undergo different treatments to optimise their distinct functions. The armature A208 may be annealed to enhance its soft magnetic properties for efficient flux guidance. Conversely, the hinge A211 may be hardened, for example through heat treatment or work hardening, to increase its yield stress and improve its resilience and spring-like characteristics.

[0354] For example, annealed Hiperco may be preferable for the Armature and pole pieces, due to improved ferromagnetic properties, and non-annealed Hiperco HS may be more suitable for the hinge due to improved yield stress and fatigue resistance, yet interweldability of these parts may be acceptable. Non-magnetic 310L stainless steel may be suitable for frame materials if these need to be welded to pole pieces, for example.

[0355] In some configurations, the hinge may also incorporate flexible materials like thermoplastic elastomers (TPE), to provide favourable acoustic damping and / or decoupling of unwanted resonances. For example, a thin layer of thermoplastic polyurethane (TPU) can be used as an adhesive interface where the hinge connects to the transducer base structure. To mitigate potential material creep when using such materials, the design may provide an increased surface area of connection between the hinge and the transducer base structure, thereby distributing stress over a wider area.

[0356] The hinge A211, as shown in Figs. 3A-3F comprises a widened central region A211a and a pair of elongate regions A211b, A211c on either side, which terminate in lateral connection tabs A211d, A211e. The connection tabs A211d, A211e are configured to connect either side of the hinge to a transducer base structure. The connection may be made using a method such as laser or spot welding. The central region A21 la, and the two elongate regions A21 lbA211c together form the flexing element of the hinge. In this embodiment, the flexing element is substantially planar. The flexing element is oriented substantially parallel to a general, major plane A224 of the armature A208 in a neutral rotational position of the armature and hinge. It is preferably also coplanar with the plane A224. Although an offset orientation is also possible. This hinge design simplifies manufacturability and lowers cost of the transducer A200, particularly when a common hinge is used for both the armature suspension and the diaphragm suspension. Functionally, the flexing element comprises a substantially smaller thickness relative to a thickness of the armature across the major plane A224.

[0357] The widened central region A211a of the hinge forms a connection plate for connecting to a corresponding tab or protrusion A208b of the armature A208. The central hinge region A21 la may be attached to the tab A208b via laser or spot welding. Alternatively, they may be adhered using an adhesive such as epoxy glue. The tab A208b extends from the main body A208a of the armature A208 at an end of the body, configured to locate adjacent the diaphragm A201. The tab A208b extends substantially orthogonally through an opening A209a of the lateral cross member A209 to couple the armature A208 to the cross member A209. As shown in Fig. 3E, a major plane or axis of the tab A208b is offset relative to a similar major plane or axis of the main armature body A208a, thereby forming a step A208d that connects the main body A208a to the tab A208b. The step A208d maintains the position of the cross-member A209 between the main body A208a and the connection tab A208b of the armature A208.

[0358] The pair of elongate side regions A21 lb and A211c extend from the widened central connection plate A211a toward their respective side connection tabs A211d and A211e. This entire arrangement (of a connection tab A208b extending from an end of the armature to connect the hinge A211 and the diaphragm A201 to one another and to the armature A208) forms a compact and robust structure for the moving assembly. Although, other direct rigid connection mechanisms between the diaphragm and armature may be utilised in alternative embodiments.

[0359] During operation, the elongate plates A21 lb, A211c are configured to resiliently flex along their length during operation. In the primary operational mode of this embodiment, these plates flex substantially in torsion. While the illustrated embodiment shows a flat plate profile, this torsion spring could be realised with other compact profiles, such as a substantially round or square profile, to achieve the desired resilient torsional flex.

[0360] This torsion spring may provide benefits such as high rotational excursion capability, increased fatigue life, improved robustness in drop scenarios and reduced fundamental resonance frequency for improved low-frequency extension.

[0361] The torsion spring design described herein is applicable to standard balanced armature transducers commonly used in hearing aid and earphone devices, where it may potentially confer the same advantages.

[0362] Alternatively, the flexing regions of the hinge mechanism could be realised in other geometries. For example, torsional flexing members may also extend in a similar direction and location to regions A21 lb,c but have alternate cross-sections such as:

[0363] An elongate rectangle, forming a leaf spring similar to A211b and A211c but orientated orthogonally to the general imaginary plane A224 of the main body A208a of the armature A208 in a neutral rotational position of the armature, a circle, forming a rod, a V-shape, for example, formed by folding a flat spring, a “C-section, for example, formed by curving a flat spring.

[0364] These are examples of hinge elements that flex substantially in torsion. Alternatively, a hinge element may be configured to flex substantially in bending. One method of achieving this would be to have a leaf spring orientated in a coplanar manner to the general major plane A224 of the main body A208a of the armature A208 in a neutral rotational position of the armature. This leaf spring would be atached to the armature A208 and / or the lateral cross member A209, along a first edge in a direction parallel to the axis of rotation Al 09, and attach it to a new rigid member, (itself rigidly connected to the transducer base structure), along a second edge also in a direction parallel to the first edge, and at a distance from the first edge. The leaf spring between the two edges would flex in bending during operation, allowing rotation of the diaphragm and armature assembly about the axis of rotation Al 09. In such configurations, the connection tab A208b may be shortened or eliminated. The new rigid member may extend partially through each side of or right through the recess A201g in the diaphragm body A201.

[0365] Referring back to Figs. 2F and 2G, as previously described, the diaphragm A201 is coupled to the armature A208 via the cross-member A209, extending laterally at an end of the armature A208. The lateral cross member A209 is oriented substantially orthogonal to a longitudinal axis of the main body A208a of the armature A208. In combination with the connection tab A208b, the lateral cross-member A209 forms a robust T-shaped connection interface, at an end of the armature A208 for mechanically coupling the diaphragm A201. To accommodate this interface, the base end A201f of the diaphragm A201 comprises a recess A201g shaped to receive the T-shaped connection, for connection to the lateral cross-member A209 and connection tab A208b. The recess A201g also provides clearance to the hinge flexing regions A21 lb and A211c.

[0366] This integrated design allows the hinge mechanism A211 to be located at least partially, and in some embodiments significantly, within the diaphragm recess. Locating the hinge inside the diaphragm's profile in this manner provides several distinct advantages:

[0367] -Minimised rotational inertia: locating the hinge axis of rotation Al 09 close to the centre of mass A212 of the diaphragm assembly, reduces the rotational inertia of the diaphragm about the axis. This can increase transducer sensitivity. Dimension A225 shows the distance between axis of rotation A109 and centre of mass A212.

[0368] -Optimised packaging: The recessed hinge location does not interfere with other critical components of the transducing mechanism, such as the coil windings A210 and the armature core A208. Furthermore, it does not increase the overall width (A219) or thickness (A221) of the transducer, which is beneficial for meeting form factor requirements of compact devices like the smart glasses Al 00.

[0369] -Cost effectiveness: making space to form a recess A201g is cost effective.

[0370] -Structural integrity: The recess A201g also provides necessary clearance for the free movement of the hinge's flexing regions A211b and A211c. While creating a recess might theoretically impact the diaphragm's stiffness, the overall rigidity of the T-shaped connection and the diaphragm ensures that the moving structure remains robust.

[0371] The same recessed hinge geometry is also applicable in conventional balanced armature transducers, albeit with the diaphragm connected to a pushrod at the other end of the armature, the hinge would in this case not be recessed inside the diaphragm. In this case many of the same advantages may be achieved, again within a compact form factor.

[0372] Furthermore, in this exemplary embodiment, the hinge system rotatably mounts the diaphragm to the transducer base structure and enables rotation of the diaphragm about an axis of rotation, wherein the axis of rotation of the diaphragm is substantially contained in a first imaginary plane that is substantially perpendicular to a second imaginary plane of the diaphragm containing the radial axis of the diaphragm, and that contains / intersects the node axis of the diaphragm. Preferably the primary axis of rotation of the diaphragm is substantially parallel to the diaphragm node axis. Preferably the primary axis of rotation of the diaphragm and the diaphragm node axis are substantially coaxial. The node axis is a second axis of rotation about which the diaphragm would rotate relative to the transducer base structure if: the diaphragm is effectively substantially unsupported by the diaphragm suspension system, and the diaphragm is subjected to the mechanical force(s) associated with the transducing mechanism, in-use.

[0373] The node axis in this exemplary embodiment is coaxial with the diaphragm axis of rotation Al 09. The node axis may be predetermined or may be determined during manufacture / installation of the device. The diaphragm node axis Al 09 is primarily dependent on the mass distribution of the diaphragm Al 01, and the force vector(s) experienced by the diaphragm from the transducing mechanism during operation. As is described in detail in WO / 2020 / 035812, the diaphragm node axis is the primary axis about which the diaphragm Al 01 would rotate if it was effectively substantially unsupported and subject to the same operational forces as applied by the transducing mechanism. The description relating to the diaphragm node axis of WO 2020 / 035812 is hereby incorporated by reference.

[0374] Diaphragm structure

[0375] Referring to Fig. 2A, in this exemplary embodiment, the diaphragm A201 comprises a main diaphragm body that is substantially rigid and lightweight. The main body is formed from a composite material. The composite material may comprise an interconnected structure that varies in three-dimensions to enhance rigidity. In this embodiment, the composite material comprises a substantially low-density matrix. For instance, the diaphragm body may be formed from a low- density foam material, such as a Polymethacrylimide (PMI) foam or polystyrene foam.

[0376] The diaphragm is preferably substantially thick to resist bending and prevent modal breakup at high frequencies. The diaphragm is preferably at least thick in one region of the diaphragm. In this embodiment, the maximum thickness A216 of the diaphragm is significant relative to its other dimensions, such as its radial length A217, and / or its width dimension A218. In various embodiments, the maximum thickness A216 may be greater than approximately 6%, or greater than approximately 9%, or greater than approximately 11% of the radial length A217 of the diaphragm. The radial length in this context means the length of the diaphragm from the axis of rotation Al 09 to a most distal, terminal edge A201a of the diaphragm A201. In various embodiments, the maximum thickness A216 may be greater than approximately 6%, or approximately 10%, of a greatest dimension of the diaphragm, which may be a diagonal length A226 of the diaphragm body (measured from one corner or edge at a base end of the diaphragm to an opposing corner or edge at the distal, terminal edge of the diaphragm).

[0377] In various embodiments, the maximum thickness A216 may be greater than approximately 50%, or greater than approximately 65%, or greater than approximately 75%, of the maximum thickness of the transducer A221. The maximum thickness of the transducer in this context excludes components (e.g. casing) that do not contribute to sound generation functions. In some configurations, the diaphragm A201 may be designed with a high aspect ratio, wherein its radial length A217 is substantially greater than its maximum dimension in directions orthogonal to that length, such as its width A218. In some embodiments, this ratio of radial length to width is at least 1.5, and may be 2, 2.5, or greater.

[0378] This elongated shape creates significant mechanical leverage. The radial length of the diaphragm A217 is substantially greater than the effective radial length of the armature A208 from the axis of rotation Al 09. This ratio, which may be at least 1.5 and in some cases greater than 2.5, allows the small, precise rotational movement of the armature to be amplified into a large-displacement, sweeping motion at the diaphragm's distal tip A201a, which is beneficial for generating high volume excursion in slim form factor devices, such as the smart glasses embodiment described herein.

[0379] In the illustrated embodiment, at least the base end of the diaphragm A201 is substantially thick, to facilitate with mechanical coupling of the base end to the armature A208 and hinge A211 as previously described. The thickness of the diaphragm body tapers along the radial length of the diaphragm A201 and reduces towards the terminal edge A201a. This lowers the average mass per unit area of the diaphragm in regions that are distal from the axis of rotation Al 09, relative to regions that are near the axis of rotation Al 09. In alternative designs, the diaphragm body may have a uniform thickness. The mass distribution may be (optionally) controlled by varying the density of the core material in such a configuration, by varying the density of the core material along the length of the diaphragm. For example, the density may be reduced along the length of the diaphragm from the base region to the distal region.

[0380] To further enhance rigidity, in this illustrative embodiment, the main diaphragm body further normal stress reinforcement A203a and A203b coupled on or adjacent the opposing, major radiating faces A201d and A201e of the diaphragm. In this embodiment, a normal stress reinforcement member or plate A203a, A203b is coupled to each of the major faces A201d, A201e. These reinforcement members are rigidly attached to the base frame cross-member A209 via angled surfaces A209b and A209c. In some variations, reinforcement may be coupled to only one of the faces A201d, A201e. In yet another alternative embodiment, there may be no normal stress reinforcement coupled to the diaphragm body. In this illustrative example, the normal stress reinforcement A203 comprises a relatively lower average mass, per unit area, in regions of the diaphragm that are distal from the axis of rotation A109 relative to regions that are proximal to the axis A109. For example, in the embodiment shown, each normal reinforcement member A203a, A203b comprises a recess A203c,d formed at an end that is distal from the diaphragm's base region or the axis of rotation Al 09. In this manner, the average mass per unit area of the reinforcement member A203a, A203b is reduced in the recessed end, further optimising the diaphragm's dynamic performance.

[0381] In an embodiment, where the diaphragm is configured to rotate relative to the transducer base structure, the normal stress reinforcement may comprise a lower mass, per unit area, in regions of the diaphragm that are distal from an axis of rotation of the diaphragm relative to regions that are proximal to the axis of rotation. The average mass per unit area may alternatively or additionally be reduced by reducing thickness or reduced or reducing a width of the normal stress reinforcement members, or both in alternative configurations. In other configurations, the average mass per unit area of the normal stress reinforcement may be uniform across the corresponding major face A201d,e of the diaphragm A201.

[0382] A region of relatively higher normal stress reinforcement mass and / or higher diaphragm mass, may comprise approximately 30-70% of a surface area of the corresponding major face, and a region of relatively lower normal stress reinforcement mass and / or lower diaphragm mass, comprises approximately 30-70% of a surface area of the major face. Whereas a region of relatively lower normal stress reinforcement mass and / or lower diaphragm mass may be located within approximately 20% of a length of the diaphragm from an end of the diaphragm that is distal to the centre of mass or that is distal to the axis of rotation of the rotating diaphragm.

[0383] Each normal stress reinforcement member A203a,b should preferably be rigidly attached to the base frame cross-member A209 of the diaphragm. This has angled surfaces A209b and A209c for attachment to each normal stress reinforcement member A203a and A203b, respectively.

[0384] The diaphragm body A201 may be shaped to facilitate effective acoustic performance within a device, such as the glasses device Al 00. For instance, in this illustrative embodiment, the diaphragm body A201 has recesses A201a,d which provide clearance for air movement through the acoustic grilles Al 07 and Al 08, as the diaphragm rotates about the axis Al 09. This benefit is more significant if the outer grill Al 03 is not incorporated in the device Al 00, and is blocked up, because as the diaphragm body rotates about axis Al 09, the sides of the diaphragm body A201 would significantly block the air flow through the grilles Al 07 and Al 08. The first and second peripheral edges A201h,i of the diaphragm A201 are configured to maintain at least a small thickness (for example >0.3mm) to facilitate a close seal with the sides A207a,b of the surround A207, preventing the cancellation of positive sound pressure by negative sound pressure.

[0385] Alternatively, or additionally, the diaphragm A201 may comprise one or more other features to achieve a substantially rigid construction, as described in WO 2017 / 046716, for example, which is hereby incorporated by reference. For instance, the normal stress reinforcement may comprise struts instead of solid plates. In an embodiment, the diaphragm may comprise at least one inner reinforcement member embedded within the body and oriented at an angle relative to at least one of said major faces for resisting and / or substantially mitigating shear deformation experienced by the body during operation. There may be a plurality of inner reinforcement members.

[0386] Transducing mechanism

[0387] Referring to Figs. 2F and 2G, as previously described, the audio transducer A200 comprises an electromagnetic, armature-type transducing mechanism. The transducing comprises a magnetic structure configured to generate a static magnetic field within a target region of the transducer A200, an armature A208 having a main body A208a suspended within the static magnetic field, and being at least magnetically coupled to a coil configured to receive an electrical audio signal.

[0388] During operation, an electrical signal received by the coil A210 induces a corresponding varying magnetic flux within the armature. This interaction with the static field causes the main body A208a of the armature to pivot or vibrate within the static magnetic field about its axis of rotation. This mechanical vibration is then transferred to the rigidly coupled diaphragm A201, causing it to oscillate and produce sound waves representative of the original audio signal.

[0389] Unless specified, the term “magnet” as used in this specification may mean a permanent magnet or a direct current electromagnet, or any combination thereof. Unless stated otherwise, the phrase “magnetic body” refers to a material or component that exhibits magnetic properties, including the ability to attract or repel other magnetic materials. This can include ferromagnetic, paramagnetic, or diamagnetic substances, which may be composed of metals, alloys, or composite materials. A magnetic body is capable of generating a magnetic field or becoming magnetized when exposed to an external magnetic field, thereby influencing the behaviour of other magnetic objects in its vicinity. A magnetic body may be used to guide, shape, or concentrate magnetic flux within the transducer, and includes components such as the pole pieces and the armature.

[0390] The magnetic structure is a multi-part assembly. In this exemplary embodiment, the magnetic structure comprises two magnetic bodies A205a, A205b configured to generate a static magnetic field therebetween. As shown in Fig. 2C, permanent magnets A205a and A205b locate opposite one another and generate a static magnetic field therebetween. It will be appreciated that any combination of two or more magnets could be positioned in opposition of one another to generate the required magnetic flux density and to appropriately distribute the static magnetic field within the target region of the transducer. Further, any one or more of the permanent magnets A205a, A205b could be replaced with an electromagnet.

[0391] The magnetic bodies A205a, A205b in combination with the remainder of the magnetic structure, are configured to impart an equal and opposing magnetic force on the armature A208. This balanced magnetic field suspends the armature in a neutral position when no electrical signal is applied to the coil A210. While permanent magnets are shown, one or more of these could be replaced with electromagnets.

[0392] The magnetic bodies A205a and A205b are rigidly coupled or integral to the transducer base structure.

[0393] As shown in Figs. 2C and 2G, in this exemplary embodiment, the magnetic structure further comprises a second pair of magnetic bodies A204a and A204b, each magnetically coupling between the first pair of magnetic bodies A205a and A205b. The second pair of magnetic bodies preferably also rigidly couple the first pair of magnetic bodies. The second pair of magnetic bodies A204a and A205b is configured to direct and concentrate the static magnetic field generated by the magnetic bodies A205a and A205b across the target region of the transducer A200, within which the main armature body A208a extends. The second pair of magnetic bodies A204a and A205b are formed from ferromagnetic materials in this embodiment. They are preferably nonpermanent magnets to enable them to be shaped in a desired manner.

[0394] In this exemplary embodiment, an end magnet A206 and the cross-member A209 may also contribute to guiding the magnetic flux.

[0395] Furthermore, to ensure the armature remains within a strong magnetic field throughout its full range of motion, the pole pieces A204a, A204b (and the end magnet A206) extend longitudinally beyond the distal end A208c of the armature.

[0396] Each of the ferromagnetic bodies A204a, A204b comprises an internally facing surface A204e / A204f that faces the main body A208a of the armature A208. The plane of each surface is substantially angled relative to a longitudinal axis of the armature A222. The plane of each surface is also substantially angled relative to a radial axis of the diaphragm A201 in this embodiment. This creates a tapered gap that widens from the proximal (pivot) end of the armature towards its distal (free) end A208c. This tapered design increases the excursion capability of the armature by providing greater clearance at its free end, while simultaneously maximising the strength of the static magnetic field. In an alternative configuration, these surfaces may be substantially parallel, providing a uniform gap along the armature's length. As previously mentioned, this structure increases the excursion capability of the armature.

[0397] Specifically, each surface A204e, A204f is preferably angled away from the longitudinal axis of the armature A222 to increase a distance between the surfaces A204E and A204f at a terminal end A208c of the armature, relative to an end of the armature proximal to the diaphragm A201. In this manner, the surfaces A204e and A204f taper away from one another along the main body A208a of the armature A208, from the diaphragm-end of the armature toward the terminal end A208c. In alternative embodiments, the internal surfaces A204E and A204f of the ferromagnetic bodies A204a and A204b may not taper away from one another along the main body of the armature A208. Instead, the distance between the internal surfaces may be substantially uniform along the length of the main body A208a of the armature A208. The pole surfaces of the ferromagnetic bodies A204a and A204b are configured to direct and concentrate the static magnetic field within a target region (within which the armature main body is suspended).

[0398] In some embodiments, the magnetic structure may be simplified and could be devoid of the pair of ferromagnetic bodies A204a and A204b. Instead, the permanent magnets A205a and A205b, or one or more other permanent magnets, may replace the ferromagnetic bodies A204a and A204b. Such permanent magnets may similarly be shaped to taper away from another as explained above in relation to ferromagnetic bodies A204a, A204b, or alternatively they may substantially nontapered at their internally facing surfaces such that the distance between them remains substantially uniform along the length of the main body A208a of the armature A208. In such a design, the magnetic field would be shaped primarily by the outer permanent magnets themselves.

[0399] The pair of outer permanent magnets A205a and A205b are positioned on an outer side of the armature A208 and extending across a general, major plane A224 of the armature. Each outer permanent magnet A205a, A205b is preferably spaced from the armature A208. The outer permanent magnet preferably also extends substantially orthogonally relative to the general major plane of the armature and comprises magnetic poles that locate on either side of the general major plane of the armature A208.

[0400] The outer permanent magnets A205a and A205b each locate opposite a corresponding side edge of the armature, the side edge extending between a diaphragm end A208b of the armature and a free edge A208c of the armature A208 distal from the diaphragm A201.

[0401] In this embodiment, the magnetic structure comprises a pair of outer ferromagnetic bodies A204a, A204b rigidly coupled to the permanent magnets A205a, A205b and extending substantially parallel to the general major plane of the armature. Alternatively, the pair of outer permanent magnets may locate opposite a pair of opposing major faces of the armature body A208a and extend substantially parallel to the general major plane A224 of the armature A208. The ferromagnetic bodies A204a A204b (or permanent magnets in the alternative configuration) may form walls of an enclosure of the audio transducer. In addition to their magnetic function, the ferromagnetic bodies A204a, A204b may also serve a structural purpose, forming part of an enclosure that protects less robust components of the transducer, such as the coil and hinge assembly.

[0402] As best shown in Fig. 2G, the magnetic structure further comprises end magnetic body A206 positioned adjacent the terminal end A208c of the armature A208, and magnetically coupling between the ferromagnetic bodies A204a and A204b. The end magnetic body A206 is preferably a further outer permanent magnet, but alternatively may be an outer electromagnet, located outside the armature, and preferably spaced from the armature. The end magnet A206 couples between the relatively large air gap formed between the ends of the ferromagnetic bodies A204a and A204b and accordingly facilitates in reinforcing and strengthening the magnetic field generated by the magnetic circuit within the target region of the transducer A200. The end magnetic body A206 is rigidly coupled to a frame or other base structure of the transducer . Each of the magnetic bodies A204a and A204b each comprise an internally facing wall A204c, A204d at a terminal end of the body having a complementary profile to an adjacent wall of the magnetic body A206 to enhance the magnetic interaction between them. For instance, in this embodiment, the internally facing wall A204c and A204d of each magnetic body A204a and A204b is substantially planar to correspond to the corresponding, adjacent, and planar outer wall of the magnetic body A206. In some embodiments these walls may be curved. Further, a distance between the internally facing walls of the magnetic bodies A204a and A204b at the magnetic body A206 may be greater than a corresponding dimension of the magnetic body A206, to maintain a substantially narrow air gap between the magnetic body A206 and each of the magnetic bodies A204a and A204b.

[0403] The outer end permanent magnet A206 preferably also extends across the general, major plane A224 of armature main body A208a, preferably substantially orthogonally thereto, such that the poles of the magnet are on either side of the plane. Each of the pair of outer ferromagnetic bodies A204a, A204b extend between a corresponding side outer permanent magnet A205a, A205b and the end outer permanent magnet A206.

[0404] The magnetic structure is devoid of ferromagnetic bodies along one or more sides of the armature A208 between the outer end permanent magnet A206 and at least one outer side permanent magnet A205a, A205b, and preferably along both sides of the armature corresponding to the location of permanent magnets A205a and A250b.

[0405] In some embodiments, the magnetic body A206 may not be incorporated to further reinforce and concentrate the static magnetic field on the target region. Alternatively, multiple magnetic bodies A206 may be positioned across the gap between the magnetic bodies A204a and A204b, at an end of the bodies A204a and A204b.

[0406] Further magnetic bodies or components may be incorporated in the audio transducer A200 to concentrate or direct the magnetic field toward the target region. For example, the cross-member A209 may be formed from a ferromagnetic material and positioned in a manner that facilitates in the direction and concentration of the static magnetic field generated by the magnetic circuit as shown in Fig. 2G. In this embodiment, the cross-member A209 is shown coupled at an end of the main body A208a of the armature A208 adjacent the diaphragm A201, with sides of the crossmember extending adjacent to the ferromagnetic bodies A204A and A204b. In alternative embodiments the cross-member may not facilitated in directing or concentrating the static magnetic field generated by the magnetic circuit.

[0407] The audio transducer A200 forms at least one magnetic circuit, and preferably two magnetic circuits A214 and A215.

[0408] As previously mentioned, the electromagnetic transducing mechanism of the audio transducer A200 further comprises a coil A210, configured to receive an electrical audio signal and induce a varying magnetic field in the main body A208a of the armature A208. The coil A210 is wound about a region of the main body A208a that is proximal to the diaphragm A201, and preferably at or adjacent the axis of rotation of the armature, or of the diaphragm, or both. The coil A210 is wound about a primary longitudinal axis A222 of the main body A208a of the armature A208. In this embodiment, the coil A210 locates directly adjacent but is separated from the main body A208A of the armature A208. The coil A210 rigidly coupled along the short sides A210c and A210d to a transducer surround A207, which may be rigidly coupled to the magnetic structure or otherwise rigidly coupled to or forms an integral part of an enclosure or housing of a device incorporating the audio transducer A200, such as smart glasses device Al 00. During operation, an electrical audio signal received by the coil A210 induces a corresponding varying magnetic field in the main body A208a of the armature A208, causing the armature A208 to vibrate within the static magnetic field generated by the magnetic circuit. The diaphragm A201, being mechanically coupled to the armature A208, is caused to rotatably oscillate in response to the armature's vibration, which in turn generates sound corresponding to the electrical audio signal received by the coil A210.

[0409] Fig. 2G shows exemplary magnetic field lines of a static magnetic field generated by a first magnetic circuit of the transducer A200 based on the above construction. The first magnetic circuit comprises the permanent magnet A206a, rigidly coupled to the transducer base structure and the pair ferromagnetic bodies A204a, A204b that are also substantially rigidly coupled to the transducer base structure. The first magnetic circuit may further comprise the movable armature body A208a. As shown, this arrangement can form a substantially complete first magnetic circuit.

[0410] Fig. 2H shows exemplary magnetic field lines of a static magnetic field generated by a second magnetic circuit of the transducer A200 based on the above construction. The second magnetic circuit comprises one or more electromagnets being the coils A210a, A210b. The second magnetic circuit further comprises the ferromagnetic bodies A204a and A204b that are substantially rigidly coupled to the transducer base structure. The lateral cross member A209 may also form part of the circuit. The second magnetic circuit may also comprise the movable armature A208. As shown, this arrangement can form a second complete magnetic circuit.

[0411] Fig. 2G is the same as Fig. 2H except that Fig. 2G shows flux lines A214 and has “(N)” and (S)” indicating possible north and south poles induced in the pole pieces A204a,b due to the magnetic circuit created by end magnet A206, and that Fig. 2H shows flux lines A215 and has “(N)” and (S)” indicating possible north and south poles induced in the armature core A208a due to the magnetic circuit created by the coil A210, when audio signal electrical current is flowing in a clockwise direction when viewed from the tip of the diaphragm side such as in view Fig. 2D. (i.e. into the page at A21 Oa and out of the page at A21 Ob as viewed in Fig. 2G). This direction of current flow induces a magnetic north polarity towards the end A208c of the armature core A208a, which in turn is repelled by the static magnetic field north polarity in pole piece A204a and attracted to the south polarity in pole piece A204b as induced by magnets A205a,b and A206 and as shown by the flux circuits A213a,b and A214. This creates an anticlockwise torque on the armature A208 about axis of rotation Al 09.

[0412] Transducer base structure

[0413] Referring to Fig. 2A, the audio transducer A200 comprises a transducer base structure to which the diaphragm is rotatably coupled, and which remains stationary relative to the diaphragm A201 during operation.

[0414] In this exemplary embodiment, the transducer base structure is an integrated assembly that comprises the entire magnetic structure, comprising the magnetic bodies A204a, A204b, A205a, A205b and A206. In an assembled state, one end of the transducer base structure is recessed to accommodate the base end A201f of the diaphragm A201 and the associated diaphragm hinge system, comprising flexing hinge member A211.

[0415] The transducer base structure A202 is substantially rigid. Parts of the transducer base structure may be integrally formed with a housing, enclosure or other part of a device incorporating the transducer A200, such as smart glasses device Al 00. Alternatively, it may be a standalone component that is coupled to housing or other part of the audio device, via a separate coupling system.

[0416] Diaphragm surround

[0417] Referring to the cross-sectional views of Figs. 2H and 21, the audio transducer A200 further comprises a structural diaphragm surround A207. This surround is configured to closely envelop and extend about the sides and terminal edge of the diaphragm A201, without physically connecting to them in at least one region of the diaphragm periphery.

[0418] In this exemplary embodiment, the surround comprises a pair of opposing side walls A207a and A207b, and an end wall A207c connecting the side walls A207a and A207b. The end wall A207c is configured to locate directly adjacent, but physically separated from, the terminal, radiating edge A201a, of the diaphragm A201. Accordingly, this wall A207c may comprise a height dimension that substantially surrounds the terminal edge A201a of the diaphragm across the full range of excursion of the diaphragm A201 during operation. The side walls A207a and A207b may comprise a similar height dimension or as shown in this embodiment, they could alternately have a tapering height dimension that gradually increases from a region proximal to the base end A201f of the diaphragm A201 toward the end wall A207c. The side walls are preferably substantially planar or have a substantially planar inner periphery facing the respective diaphragm edges. The end wall A207c comprises a substantially concavely curved inner periphery to maintain a substantially uniform gap between the radiating terminal edge A201a of the diaphragm A201 and the end wall A207c, across the full range of excursion of the diaphragm A201 during operation. In other embodiments, the inner periphery of the end wall A207c may be substantially planar.

[0419] The surround A207 further comprises a pair of connection blocks A207e and A207d configured to rigidly couple the transducer base structure in an assembled state of the transducer A200. The surround A207 rigidly couples the magnetic structure in this embodiment. In some embodiments, the surround A207 may additionally or alternatively rigidly couple or be formed integrally with a housing or enclosure of a device incorporating the audio transducer A200, such as one of the arm bodies AlOla or AlOlb of smart glasses device A100. In some embodiments, the surround A207 may be integrally formed or rigidly coupled to the housing or enclosure of a device incorporating the transducer A200 (e.g., AlOla or AlOlb or smart glasses device A100), and is not rigidly coupled to the transducer base structure of the audio transducer A200, thereby forming part of the device rather than part of the audio transducer A200.

[0420] The transducer comprises a "free-edge" interface between the diaphragm A201 and the surround A207. As illustrated in Fig. 2F and 21, in an assembled state, the surround A207 extends about and is closely associated with the diaphragm A201 but is separated from the outer periphery of the diaphragm A201 by a small air gap.

[0421] In the illustrated embodiment, the entire outer periphery of the diaphragm that moves during operation, including outer peripheral edges A201h and A201i and the terminal peripheral edge A201a are entirely uncoupled and free from physical connection with the surround A207.

[0422] In alternative embodiments, only a part of the outer periphery of the diaphragm may be uncoupled and free from physical connection with the surround A207. For example, at least 20% of the entire perimeter of edges A201a, A201h and A201i, or at least 50% of the entire perimeter, and at least 80% of the entire perimeter may be free from connection. Sections of the diaphragm periphery that are coupled to the surround may include a flexible coupling such as a soft plastics connection.

[0423] In this embodiment, the surrounding structure A207 excludes the diaphragm base structure.

[0424] An air gap between the outer peripheral edge of the diaphragm and the surrounding structure is substantially narrow. For example, the gap may be less than approximately 0.5mm, or less than approximately 0.3 mm, or less than approximately 0.2mm.

[0425] Furthermore, a specific geometric relationship may be defined between the air gap and the cellular structure of the diaphragm's core material. In a region distal from the axis of rotation, the width of the air gap is designed to be substantially larger than the average cell diameter of the core material. For example, the gap between the outer peripheral edge of the diaphragm A201 and the surrounding structure A207, in a region or side most distal from the axis of rotation, may be more than 2 times greater, more than 3 times greater, or in some cases more than 4 times greater, than an average cell diameter of the core material of the diaphragm in the same region.

[0426] The surround A207 may be constructed from materials selected for high strength and rigidity, which allows for a small wall thickness and facilitates the transducer's sleek form factor. In some embodiments, the surround A207 is formed from a metallic material, such as 304 stainless steel, titanium, or an amorphous metal alloy such as Liquidmetal and Vitreloy. Alternatively, high- strength plastics may also be suitable. The surround A207 can also be integrally formed as part of the larger device, for instance as part of the arm body Al 01 or arm cap Al 02.

[0427] In this exemplary embodiment, the audio transducer A200 is designed to be compact and to have a high-aspect-ratio, or "slender," form factor. Its maximum overall dimension is typically less than 30mm, with some embodiments being less than 25mm, or less than 20mm.

[0428] An exemplary embodiment of the transducer A200 (or the alternative transducer A400) has overall dimensions of approximately 1.5mm in thickness A221, 5.6mm in width A219 and 14mm in length A220. A driver with such small cross-sectional dimensions (such as 1.5mm by 5.6mm) is particularly advantageous for integration in very slim devices, such as the smart glasses device Al 00 or modern mobile phones. This results in a transducer where its greatest dimension is substantially greater than its smallest dimension (the thickness A221). For instance, this ratio of greatest-to-smallest dimension may be at least 2 times greater, and in some embodiments at least 3 times greater. More specifically, the transducer's length A220 may be at least 2 times greater than its thickness A221, and simultaneously at least 1.5 times greater than its width A219. This elongated shape is an enabler for its integration into thin and narrow devices.

[0429] Despite the small dimensions, , the transducer A200 (or A400) achieves a relatively high-volume excursion. This is due to the combination of a significant diaphragm area (approximately 44mm2), a long diaphragm radius A217 (approximately 11mm), and a large peak-to-peak angle of excursion (approximately 4.8 degrees), resulting in a peak-to-peak volume displacement of about 20mm3. This high excursion capability within a slim form factor is a key advantage, enabling the transducer to produce a deeper bass response than would be expected from a driver of its size.

[0430] . In embodiments of the present disclosure where diaphragm A201 is not directly and / or rigidly attached to the armature A208 (but other features of the first to eleventh aspects are implemented), the diaphragm A201 may be mechanically coupled to the armature A208 via an intermediate component such as a drive rod, and may extend above the transducing mechanism of the audio transducer A200.

[0431] The high excursion capability of the transducer can also be characterised by the ratio of the diaphragm's maximum displacement to the depth of the cavity within its housing. In various embodiments, the maximum displacement of the terminal end of the diaphragm A201a across its full range of motion is substantially greater than the internal depth of the cavity that accommodates it. For instance, this displacement may be at least 50% of the maximum inner depth dimension of the cavity. In high-performance embodiments, this ratio may be at least 70%, and in some cases at least 80%, demonstrating the design's exceptional ability to maximize air movement within a highly constrained volume.

[0432] In some implementations, the interaction between the diaphragm A201 and the surround A207 can be further refined to provide non-linear mechanical control. By shaping the profile of the diaphragm's outer peripheral edge and / or the inner periphery of the surround, the path length across the narrow sealing gap between these two components can be made to vary as the diaphragm displaces through its range of motion. As used herein, the "path length” across the gap refers to the shortest distance an air particle must travel along the boundary surfaces of the diaphragm's outer peripheral edge and the surround's inner periphery to move from the region of higher acoustic pressure on one side of the diaphragm to the region of lower acoustic pressure on the other side. This path length directly influences the acoustic impedance of the gap.

[0433] For example, a curved or chamfered diaphragm edge moving within a specifically shaped surround can cause the effective path length of the gap to increase at the extremes of the diaphragm's excursion. This change in path length alters the acoustic impedance of the gap, providing a nonlinear damping effect. This can help to "softly" limit the diaphragm's movement at maximum excursion, thereby preventing hard contact or collision with the surround and reducing potential distortion at high output levels.

[0434] The audio transducer A200 as described herein may be implemented in any one of the apparatuses Al 00, A600 or A800 also described herein.

[0435] 4. Second Illustrative Audio transducer A400

[0436] Figs. 4A and 4B show a cross-sectional view of alternate audio transducer A400, as viewed from the same cross-sectional view as Fig. 2G. Audio transducer A400 is similar to audio transducer as A200 except that:

[0437] 1. Alternate outer pole pieces A404a,b replaces outer pole pieces A204a,b;

[0438] 2. Additional magnets A401 and A402 are incorporated;

[0439] 3. Alternate armature A408 is implemented, replacing armature A208; and

[0440] 4. Alternate coil winding A410 is implemented replacing coil winding A210

[0441] Fig. 4A is the same as Fig. 4B except that Fig. 4A shows flux lines A414 and has “(N)” and (S)” indicating possible north and south poles induced in the pole pieces A404a,b due to the magnetic circuit created by end magnet A206. Whereas Fig. 4B shows flux lines A415 and has “(N)” and (S)” indicating possible north and south poles induced in the armature core A408a due to the magnetic circuit created by the coil, when current is flowing in a clockwise direction when viewed from the tip of the diaphragm side. (i.e. into the page at A410a and out of the page at A410b as viewed in Fig. 4B).

[0442] The audio transducer A400 has the coil winding rigidly coupled to and wound around the armature A408, and is detached from the transducer base structure. This has advantages, for example in terms of:

[0443] 1. eliminating the air gap between the coil and the armature A408 meaning that the performance of the coil with respect to generating flux in the magnetic circuit A415 may be improved.

[0444] 2. The coil mass is rigidly attached to and is part of the moving diaphragm assembly. This means that the distance dimension A425 from the centre of mass A412 of the diaphragm assembly to the axis of rotation Al 09 is increased, which may improve balancing and / or lead to improved driver sensitivity, despite the additional moving mass of coil that requires additional torque generation to overcome.

[0445] Features that differ from transducer A200 will be described only for the sake of brevity. Unless stated otherwise, all other features of transducer A400 remain the same as the corresponding feature in transducer A200. Accordingly, new references are only included for the features that differ, and the same feature reference numeral is used for features that remain the same as in transducer A200.

[0446] The fixed coil configuration of audio transducer A200 on the other hand has an advantage over the moving coil driver A400 being that as the coil is not moving, the wires are not moving relative to the transducer base structure, and so are less likely to break or fail due to fatigue.

[0447] Coil A410 has angled surface A410c along long side A410a and angled surface A410dc along long side A410b to improve the maximum rotational excursion of the diaphragm A201.

[0448] Audio transducer A400 has additional magnets A401 and A402 with the orientation of the magnetic poles being in an opposite direction to the magnets A205a,b and A206. The inside surfaces A401a and A402a of magnets A401 and A402 are angled to accommodate the rotational excursion required of the armature A408. Regions A408b, A408d and plane A424 may be the same as A208b, A208d and A224 respectively, but with respect to armature A408 instead of A208.

[0449] The outer pole pieces A404a,b has material removed where magnets A401 and A402 are located, compared to outer pole pieces A204a,b. This means that these parts are completely flat and are easier to manufacture.

[0450] The armature A408 has an additional mass of material added the terminal end region A408c. Surfaces A408e and A408f protrude from the armature body A408a to create the additional mass. Alternatively, an additional mass of material may be adhered, or spot welded to the terminal end region A408c. The additional mass is preferably a high-density material such as steel or tungsten. Surfaces A408e and A408f are angled slightly to improved rotational excursion of these areas about the axis of rotation Al 09. The magnets A402 and A401 are reduced in a length direction parallel to the longitudinal axis A222 of the armature A408 such that there is a gap between these magnets and magnet A206, which allows the additional steel of end A408c to rotate further about axis Al 09 during operation. The magnets A402 and A401 strengthen the magnetic flux circuit A414 shown in Fig. 4A and also the similar circuit through side magnets A205a,b, through outer pole pieces A404a,b and through magnets A402 and A401, so transducer sensitivity may be improved.

[0451] The audio transducer A400 as described herein may be implemented in any one of the apparatuses Al 00, A600 or A800 also described herein.

[0452] 5. Illustrative audio device incorporating audio transducer A200 or A400

[0453] Referring back to Figs. 1C-1H, a housing or enclosure for incorporating an armature type audio transducer, such as audio transducer A200 or A400, is shown.

[0454] When the audio transducer is accommodated within a housing or enclosure having a cavity for the transducer, as per the device Al 00 having a transducer cavity for transducer A200 or A400 for example, a maximum displacement of a terminal end A201a of the diaphragm A201 across a full range of motion of the diaphragm is preferably substantially greater than at least 50 percent a maximum inner depth dimension of the cavity, more preferably at least 70%, and most preferably at least 80% percent.

[0455] The housing or enclosure forms part of the smart glasses device Al 00 in this embodiment. However, it could form part of another device incorporating an armature type audio transducer. Preferably the device is substantially compact and portable. The device may be configured to be worn, like an earphone or hearing aid, or otherwise held up against a user’s head in use like a mobile phone.

[0456] 6. Illustrative audio transducer assembly A500

[0457] In some devices there may be a problem where external loads applied in-use may result in deformation of internal components and risk of failure. This may be exacerbated in cases where the housing is formed from a relatively lower-modulus material compared to modulus of parts of the internal component, as well as in thin and / or slender components particularly where internal components may comprise a higher proportion of the device’s thickness since this can contribute to the proportion of macro-device loading that is transmitted through the component rather than through the device housing or frame. Long, slender device bodies, such as a glasses arm, may put internal components at particularly high risk, since components may potentially resist significant bending loading in two orientations, as well as torsion, and the significant length dimension of the arm means that occasional high loadings are likely across a device’s lifespan. Transducers that are long relative to thickness and / or width may also be at higher risk of damage due to increased leverage that can be applied along the length meaning that external loads can potentially deform the component in bending and / or twisting directions.

[0458] Referring to Figs 5A-6C, an alternative embodiment of an audio transducer assembly A500 is shown. This assembly provides a self-contained, robust unit designed for integration into a host device, such as the substantially narrow housing of a spectacles arm, where a length and width are substantially greater than its thickness. The assembly comprises a transducing mechanism operatively coupled to a diaphragm A504, which is in turn protected by a metallic enclosure. The transducing mechanism is configured to convert between electrical signals and mechanical vibration of the diaphragm. The diaphragm A504 has a first major face for generating positive- phase sound pressure and an opposing second major face for generating opposite-phase sound pressure.

[0459] The assembly A500 comprises a metallic enclosure that substantially encapsulates at least the diaphragm A504. This enclosure is an integrally formed unit that defines an internal cavity, which is shaped to provide a minimal operational clearance sufficient to accommodate the full range of motion of the diaphragm A504 during operation.

[0460] In the embodiment shown, the enclosure is constructed from at least two separate components metallurgically bonded together, such as by welding. A first component, the steel frame A501, forms a first face-plate, and a second component, the steel plate A502, forms a second face-plate. These are joined by side walls extending from either one of the first or second face-plates. In alternative embodiments, the enclosure could be a single, unitary component.

[0461] The metallic enclosure is formed from a material (e.g., steel) having a high Young's Modulus, typically greater than 10 GPa, and in preferred embodiments greater than 20 GPa. When installed in a housing of the host device made of a material (e.g., a plastics material), the enclosure's material has a higher yield strength. The metallic enclosure material preferably has a first bending stiffness that is substantially greater than the second bending stiffness of the adjacent housing portion. This ratio of stiffness may be at least five times greater, meaning internal housing loads may be relatively lower, allowing the housing to be designed with a very thin wall, for instance less than 1.2mm, and in some cases less than 1mm or even less than 0.8mm, without compromising structural integrity.

[0462] In some exemplary implementations, at least a portion of the metallic enclosure comprises a ferromagnetic metal. As shown for this embodiment, the outer pole piece A503 is ferromagnetic and forms at least a portion of the magnetic structure of the transducing mechanism. In this manner, the enclosure comprises the transducing mechanism, with the enclosure and a portion of the mechanism being effectively a single, integral component. In this embodiment driver is aided if steel frame A501 and steel plate A502 are not significantly ferromagnetic. To ensure structural integrity, preferably the metal types of steel frame A501, steel plate A502 and pole piece A503 have compositions facilitating at least reasonable welding or other metallurgical connection compatibility.

[0463] For example, steel frame A501 and steel plate A502 may be made from 516L stainless steel, and pole piece A503 may be made from Hiperco 50 or Hiperco 50 HS. Alternatively steel frame A501 and steel plate A502 may be made from 510L stainless steel and pole piece A503 may be made from mild steel. Laser welding may be one suitable joining method.

[0464] The metallic enclosure forms a substantially continuous shell, interrupted only by at least one aperture that provides an acoustic pathway. Specifically, the assembly comprises one or more first apertures A501c positioned on the first face-plate A501 to align with the first major face of the diaphragm, and one or more second apertures A502c, A502d on the second face-plate A502 to align with the second major face. These apertures are further aligned with corresponding housing apertures when the assembly is installed.

[0465] Since the transducer is designed to be able to be integrated into devices having lower-modulus housing, such as a plastic glasses frame or a plastic mobile phone, for example, and since the Young’s modulus of the enclosure is quite high, a significant proportion of external loads applied to the device in-use may be resisted by the transducer, and the transducer may potentially sustain the majority of many of such loads. Some plastic housing designs may comprise metal reinforcing, for example a glasses arm may comprise a reinforcing wire, however even in this case, such reinforcing may sometimes be too thin and / or inappropriately located to sufficiently resist external loads to a degree required to protect internal componentry.

[0466] For this reason, the enclosure walls are thicker than might be strictly necessary if the transducer's purpose was confined to audio reproduction. The thickness of 0.5mm may be governed by the degree of external load applied to the device that a designer wishes to be able to resist without failure, and / or by the maximum load bearing capability of all parts of the body located in reasonably close proximity to the transducer. Looking at the example of a glasses arm, there may be little point making a transducer handle a load 10 times greater than the maximum load that an adjacent part of the glasses arm can handle without breakage. The fact that the transducer may potentially resist a significant proportion of externally applied loads is also an underlying reason for the first face plate and second face plate being welded or metallurgically connected, as opposed to a weaker adhesive bond, for example. In an alternative an adhesive bond may be employed, and the first face plate and second face plate may be designed such that there is significant overlap to improve bond strength. Preferably any such overlap comprises a significant proportion of the thickness and / or side wall dimension.

[0467] In many consumer electronics devices, a key engineering trade-off is that between device compactness, which is affected by the transducer’s volume, and the volume of air that the transducer can displace in-use, which affects low frequency extension.

[0468] Another potential issue is stress raisers in a device housing associated with a transducer or component, which may potentially comprise higher Young’s modulus, bonded into a housing wall. The stress raiser may be associated with both geometry and / or with differential in Young’s modulus, and may result in elevated stresses, typically proximal to a sharp boundary edge of the component.

[0469] The device helps to optimise both of these issues through features such as thicker, load-bearing- capable transducer enclosure geometry and bonding method, as well as geometrical features at transducer edges designed to facilitate robust transfer of loads between the transducer and immediately adjacent parts of the housing located where the transducer terminates. This in turn facilitates reduced wall thickness, e.g. 0.85mm A619 and 0.64mm A620 in Fig. 6C, of the plastic housing parts A601 and A602 respectively in the region of the transducer compared to wall thickness either side of the transducer, e.g. 1.73mm A616 and 1.44mm A617 in plastic part A601 in Fig. 6C. This achieves a larger transducer delivering low frequency extension and / or a more compact device, without sacrificing device strength or, worse, creating a relative weakening of the device housing proximal to the transducer termination. Again, referring to Fig. 6C, the cavity depth A814 of 3mm in the region in the region of the transducer is 89% greater compared to the cavity depth A621 of 1.59mm adjacent to the transducer.

[0470] To ensure a durable and seamless integration with a surrounding device housing, the enclosure features at least one profiled edge region at its junction points. This profile facilitates a progressive decrease in the overall wall thickness of the transducer’s housing in a direction toward the enclosure, which can be achieved via a substantially continuous and smooth taper or by a plurality of discrete steps.

[0471] As shown in FIG. 5A, the profiled edge regions can be formed in several ways. The regions A503c are examples of inwardly angled walls of the enclosure facilitating a gradual decrease in wall thickness of the housing. Alternatively, a profile can be created by a variable wall thickness, for instance by forming one or more recesses (A503a) to create a stepped profile that progressively widens, or by a continuous taper to create a smooth edge.

[0472] These profiled edge regions are located on both the first face-plate A501 and the second face-plate A502, as well as on the side walls A503b, thereby providing a smooth transition on all sides and both opposing ends of the enclosure in this embodiment. But it will be appreciated that any combination of one or more profiled edge regions may be on any combination of one or more of the first and second face-plates and / or side wall.

[0473] In this exemplary implementation, the enclosure further comprises an extension plate, formed by a protrusion A502a, that extends longitudinally from a terminal end of the main enclosure body. This plate extends beyond the region occupied by the audio transducer. As shown, the extension plate has an inwardly angled or curved profile to facilitate a gradual reduction in wall thickness of the housing at the junction with the enclosure. The extension plate also tapers in width toward its distal end, further facilitating the gradual reduction in housing wall thickness at the junction.

[0474] In these cases, an overall goal of providing a progressive decrease in the overall wall thickness of the transducer’s housing in a direction toward the enclosure is to increase the wall thickness of the potentially weaker device housing so that there is significant overlap between these thicker parts and the transducer. This facilitates load transfer between transducer and adjacent parts of the device housing without undue reliance on adhesive bonding and / or creation of stress raisers in the device housing.

[0475] Another feature that may help to optimise the trade-off between transducer size and / or performance and device compactness is dual-purposing of transducer components, which, in conjunction with other features facilitating high load bearing by the transducer and / or features that facilitate effective load transfer to and from the transducer, may result in space savings as well as potentially reduced component count.

[0476] Referring to Fig. steel plate A502 and parts of steel frame A501 serve purposes of grill protection supports as well as structural load bearing elements. Note that triangulation in these components means that grill perforations do not greatly compromise structural integrity across a wide range of external load types including various bending and torsion loads.

[0477] Likewise, driver outer pole piece A503 guides magnetic fields for the motor and contributes to structural load-bearing capability. This is made possible partly by structurally strong weld joints connecting steel frame A501, steel plate A502 and pole piece A503 . Regions A503a that are not covered provide significant glue-bond area connecting to a thicker-wall device housing that progressively widens approaching the transducer’s terminal end.

[0478] As described in relation to transducer Al 00, in this exemplary embodiment, the hinge system rotatably mounts the diaphragm to the transducer base structure and enables rotation of the diaphragm about an axis of rotation, wherein the axis of rotation of the diaphragm is substantially contained in a first imaginary plane that is substantially perpendicular to a second imaginary plane of the diaphragm containing the radial axis of the diaphragm, and that contains / intersects the node axis of the diaphragm. Preferably the primary axis of rotation of the diaphragm is substantially parallel to the diaphragm node axis. Preferably the primary axis of rotation of the diaphragm and the diaphragm node axis are substantially coaxial. The node axis is a second axis of rotation about which the diaphragm would rotate relative to the transducer base structure if: the diaphragm is effectively substantially unsupported by the diaphragm suspension system, and the diaphragm is subjected to the mechanical force(s) associated with the transducing mechanism, in-use.

[0479] The node axis in this exemplary embodiment is also coaxial with the diaphragm axis of rotation A607. The node axis may be predetermined or may be determined during manufacture / installation of the device. The diaphragm node axis A607 is primarily dependent on the mass distribution of the diaphragm, and the force vector(s) experienced by the diaphragm from the transducing mechanism during operation. As is described in detail in WO / 2020 / 035812, the diaphragm node axis is the primary axis about which the diaphragm would rotate if it was effectively substantially unsupported and subject to the same operational forces as applied by the transducing mechanism.

[0480] The housing and metallic enclosure may be moulded to one another to create a seamless and robust junction.

[0481] Upon cooling and solidification, the process yields a single, composite component where the plastic housing is moulded in intimate, void-free contact with the metallic enclosure. The inner surface of the housing becomes a direct and complementary replication of the enclosure's outer profile. This moulding process inherently creates the desired progressive decrease in the housing's wall thickness at the junction, as the plastic forms a graduated transition onto the enclosure's tapered, stepped or otherwise profiled edges. This eliminates the need for adhesives or mechanical fasteners and creates a mechanically interlocked part with high structural integrity and no sharp stress-raisers at the material interface.

[0482] The audio transducer A500 as described herein may be implemented in any one of the apparatuses Al 00, A600 or A800 also described herein.

[0483] 7. Illustrative Audio transducer A700 and device A800

[0484] Referring to FIGs 7A-7F, an alternative embodiment of an audio transducer assembly A700 is shown. This assembly provides a self-contained, robust unit specifically designed to address the challenges mentioned in section 6 of the present disclosure, and is suitable for integration into a host device, such as the substantially narrow housing of the glasses arm A800 shown in Figs 8A- 8E. For this reason the transducer, too, is long and slender, which, combined with the fact that it comprises materials having high Young’s modulus, puts it at potential risk of bending deformation and therefore failure in-use when mounted in a housing such as a plastic glasses arm comprised of a lower Young’s modulus material such as plastic.

[0485] The assembly comprises a transducing mechanism operatively coupled to a diaphragm A703, which is in turn protected by a metallic enclosure. The transducing mechanism is configured to convert electrical signals into a linear, pistonic mechanical vibration of the diaphragm. The diaphragm A703 has a bottom face A703a for generating positive-phase sound pressure and top face A703b for generating opposite-phase sound pressure. A suspension A702 connects the periphery of the diaphragm to a surround A709.

[0486] The assembly A700 features a metallic enclosure that substantially encapsulates the internal components, including the coil windings A704, inner magnets A707a,b, and outer magnet ring A708. This enclosure is an integrally formed unit, created by metallurgically bonding several components, such as by welding. In the embodiment shown, the enclosure comprises a nonmagnetic top plate / grille A701, a non-magnetic frame surround A709, and a ferromagnetic bottom pole piece plate A710.

[0487] This metallic enclosure is formed from a material with a high Young's Modulus (e.g., >20 GPa) and acts as a primary structural element. When the assembly A700 is disposed within the plastic housing of the glasses arm A800, its geometry, high bending stiffness and strength, and features that facilitate load transfer to surrounding parts, mean that it can provide significant reinforcement. In order to help facilitate effective load transfer t is preferable that the assembly A700 is strongly adhered to the housing of the glasses arm A800, for example using an adhesive, such as epoxy. A significant proportion of external loads applied to the device are resisted by the transducer assembly itself, allowing the plastic housing walls to be designed with a very thin profile. As shown in FIG. 8E, the housing wall thickness can optionally be less than 1mm (e.g., A808 at 0.85mm and A807 at 0.64mm) without compromising structural integrity.

[0488] The transducing mechanism comprises a top outer pole piece plate A705 and top inner pole pieces A706a,b which, along with the bottom pole piece plate A710, form part of the magnetic circuit. These may form part of the enclosure. This dual-purposing of components as both magnetic guides and structural load-bearing elements results in significant space savings and a reduced component count.

[0489] The enclosure forms a substantially continuous shell, interrupted by apertures that provide distinct acoustic pathways. A first set of apertures, the slot hole A710a in the bottom pole piece plate, aligns with a slot between the two inner magnets A807a,b, and a slot between the two top inner pole pieces A706a,b to align with the bottom face A703a of the diaphragm allowing positive-phase sound pressure to exit. These apertures are aligned with a corresponding housing aperture, the slot vent A801a in the body of the glasses arm A801.

[0490] A second set of apertures, the grille holes A701a in the top plate, are positioned to align with the top face A703b of the diaphragm, As shown in FIG. 8B, this allows the opposite-phase sound pressure to be directed via path A808 into a dedicated vent tube A804 within the glasses arm, where it is then expelled through a distal vent hole A804a. This separation of acoustic paths prevents cancellation and improves audio performance.

[0491] For a durable and seamless integration with the surrounding plastic housing of the arm A801, the enclosure features several profiled edge regions. These profiles facilitate a progressive change in the wall thickness of the housing at the junction to reduce stress concentration and / or reliance on adhesive bond strength over insufficient bond areas. For example, the top plate A701 features protrusions A701c at its base end, and the bottom plate A710 features corresponding protrusions A710b. As shown in FIG. 8E, these features create a stepped interface, where the housing wall thickness gradually decreases (e.g., from A809 at 1.21mm) to A808 at 0.64mm ) to smoothly transition onto the rigid metallic structure. A similar graduated transition is shown at the tip region of the transducer, where the housing wall thickness decreases (for example from A810 (1.45mm) and A811 (1.53mm) to A807 (0.64mm)) to accommodate the enclosure's tip regions A701b and A709a.

[0492] It will be appreciated that many of the structural and functional features described herein in relation to the audio transducer assembly A500 and its integration into a host device may be equally and advantageously implemented in the linear-action transducer assembly A700 and its corresponding device A800.

[0493] For instance, the specific geometries of the profiled edge regions, the use of triangulated structures for stiffening, the dynamic air gap impedance features, the specific material compositions and treatments, and the methods of manufacture, such as over-mowlding, are not limited to the rotational transducer embodiment and are fully contemplated for application to the linear-action transducer embodiment A700 and other similar configurations. The foregoing descriptions are therefore to be read as complementary, with features being interchangeable between embodiments unless structurally incompatible.

[0494] The audio transducer A700 as described herein may be implemented in any one of the apparatuses Al 00, A600 or A800 also described herein.

[0495] 8. Illustrative combinations and other examples

[0496] Additional aspects and features of audio transducers, audio transducer assemblies, and systems and apparatuses are described in the series of paragraphs in the Summary of Invention section, some of which may be numerically designated for clarity and efficiency. Each of these paragraphs can be combined with one or more other paragraphs, and / or with disclosure from elsewhere in this application, in any suitable manner. Some of the paragraphs further limit other paragraphs, providing without limitation examples of some of the suitable combinations.

[0497] 9. Advantages

[0498] Some advantages specifically relating to the first to thirteenth aspects of the present disclosure will now be described briefly to highlight certain non-exclusive and non-exhaustive advantages attributed to the combination of features of each of these general aspects. Other embodiments of the invention may be constructed in accordance with any one of these aspects, or any combination of two or more of the aspects. Furthermore, embodiments may also be constructed in accordance with any combination of one or more aspects and one or more embodiments as described in the summary of invention section, and optionally including any one or more of the features described in this specification. Some exemplary embodiments of this nature and their associated advantages are also briefly described at the end of this section. Other embodiments and advantages may be construed in a similar fashion without departing from the scope of this disclosure.

[0499] As best shown in Fig. 2F, the diaphragm A201 of the audio transducer A200 is directly coupled to the armature A208 as described for the first aspect. In a preferred implementation, the audio transducer A200 is mechanically coupled to and extends from an end of the armature A208 as described in the second aspect. The armature A208 is substantially rigid in use and the diaphragm A201 is substantially rigid in-use. The direct connection between the diaphragm A201 and armature provides a more compact cross-section geometry for the transducer A200, compared to a traditional armature audio transducer that connects the diaphragm to the armature via an elongated rod.

[0500] As shown in Fig. 21, to facilitate direct connection between the armature A208 and diaphragm A201, a cross-member A209 extends laterally from an end A208b of the armature A208 and provides a connection interface for a corresponding base end of the diaphragm A201, as described in the third aspect. The lateral cross-member A209 preferably comprises a substantially planar surface for connecting to the diaphragm A201. This interface strengthens the connection between the diaphragm A201 and the armature A208. The use of the rigid cross member as part of the balanced armature configuration may also provide improved sensitivity for the transducer.

[0501] Referring to Figs. 2F and 21, the audio transducer A200 further comprises a surround structure A207 closely surrounding the diaphragm A201, and that locates directly adjacent an outer peripheral edge of the diaphragm. The outer peripheral edge A201a, A201g and A201h of the diaphragm is substantially free from physical connection with the surrounding structure A207 as per the fourth aspect. At least partially mitigating flexible connections between the diaphragm and the surround can help increase diaphragm excursion and low-frequency response / bandwidth within thin and / or narrow form factor applications, and also improves high-frequency resonance characteristics and bandwidth.

[0502] Referring to Fig. 2G, the magnetic structure comprises a pair of magnetic bodies A204a and A204b that concentrate the static magnetic field across armature A208. Each magnetic body A204a, A204b comprises an internally facing surface A204e / A204f that opposes the armature A208. The plane of each surface is substantially angled relative to a longitudinal axis of the armature A222 as described in the fifth aspect. This angled form increases the excursion capability of the armature and / or maximises the strength of the static magnetic field. Each surface is preferably angled away from the longitudinal axis of the armature A222 toward a terminal end A208c of the armature distal from the diaphragm A201.

[0503] As shown in Fig. 2F, the diaphragm A201 is substantially thick in at least a base region of the diaphragm A201 (as per diaphragm thickness dimension A216) relative to a radial length dimension A217 and / or width dimension A218 of the diaphragm A201, as described for the sixth aspect. This increased thickness provides rigidity to the diaphragm which, in combination with an armature type mechanism, allows use of a larger diaphragm for increased volume excursion capability and / or reduced resonance at higher frequencies, all else being equal. This is without undue reduction in armature displacement and / or efficiency associated with increased diaphragm mass, since armatures usually comprise a high proportion of the combined mass of the moving elements. This is particularly useful given the context of a relatively strong, efficient, and easily miniaturisable motor system.

[0504] In the case of the transducer A200 where the diaphragm A201 extends from the armature as per the first, second or third aspects of the disclosure, there is further synergistic benefit whereby the rigid armature provides, via the direct connection, a mechanically robust base for attachment of the thick diaphragm, providing an overall rigid diaphragm / armature assembly, leading to a further improved resonance characteristic at higher frequencies in spite of a potentially larger diaphragm potentially leading to an increase in volume excursion capability. As is well-known in the art improved resonance characteristic at higher frequencies may provide improved subjective audio experience, and may also lead to improved bandwidth and / or potentially improved higher- frequency efficiency compared to designs where unwanted resonance leads to some regions of the diaphragm surface moving in opposition to other regions. Another benefit, at least in a context of applications such as glasses or phones, may be a thinner and / or more slender form factor.

[0505] Fig. 3A shows a hinge structure for pivotally coupling the armature A208, to the transducer base structure. The hinge comprises a flexing hinge element A211 oriented in a substantially parallel or coplanar manner to a general, major plane A224 of the main body A208a of the armature A208 in a neutral rotational position of the armature A208, as described in relation to the seventh aspect. Additionally, the hinge element A211 is oriented in a substantially parallel or coplanar manner to the coronal plane A223 of the diaphragm A201. The benefit of this includes increased rigidity of the suspension system in directions that are important for drop protection involving the sides and tip of the diaphragm potentially contacting the surround. For example, the rigidity of diaphragm translations in the coronal plane and in rotation about an axis orthogonal to the coronal plane A223 of the diaphragm A201. As shown in Fig. 3E, the flexing element A211 comprises a substantially smaller thickness than a thickness of the armature across the imaginary plane, as described in relation to the seventh aspect. The benefit of having a separated, thinner hinge component include: more scope for a designer to tailor and reduce fundamental resonance frequency by balancing restoring force to negative rotational stiffness inherent in the motor system ; potential to increase diaphragm excursion capability through geometry features such as alignment of the flexing length along and / or subtantially parallel to the axis of rotation, optionally in location proximal to the axis of rotation (torsion bar) ; Ability to increase diaphragm excursion for improved low-frequency performance and improved volume excursion and / or reduce risk of hinge deformation in a drop scenario ; Ability to tailor the hinge stiffness profile in different rotational and translational directions, for example in the audio transducer A200 embodiment, 3 flexing element A211 is oriented substantially parallel to a coronal plane A223 of the diaphragm A201, which may provide increased stiffness against diaphragm rotations and translations that might lead to displacements of the diaphragm within the coronal plane A223 which might present particularly high risk of damage to the diaphragm periphery due to the necessity for a narrow air gap associated with the free periphery design (which in turn is useful for increased volume excursion) ; Conversely, this geometry and orientation of flexing element A211 may reduce stiffness against translations and rotations associated with displacements in directions perpendicular to a coronal plane A223 of the diaphragm A201, which may provide advantages including improved decoupling of the diaphragm from transverse resonances of the glasses frame (or other device as the case may be) having a component in a direction perpendicular to a coronal plane A223 of the diaphragm A201, since such resonances may present increased risk of transferring to and being amplified by the lightweight diaphragm due to the impedance mismatch.

[0506] The flexing and resilient hinge element A211 is preferably substantially elongate and coupled to a central region of the armature, and extends axially towards opposing sides of the armature A208 as described in relation to the eight aspect. This structure allows for greater excursion of the diaphragm, and lowers the chance of damage under high excursion, yet remains compact for small form-factor applications. As shown in Fig. 2G, the diaphragm A201 comprises a recess A201g and the hinge is preferably located within this recess, as described in relation to the ninth aspect. As per the eighth aspect, this structure also independently can allow for greater excursion of the diaphragm, and lowers the chance of damage under high excursion, yet remains compact for small form-factor applications.

[0507] As per the tenth aspect, the magnetic structure preferably comprises a pair of magnetic bodies A204a and A204b which extend beyond a corresponding terminal, free edge A208c of the armature A208, along an axis parallel to the longitudinal axis A222 of the armature A208. This arrangement strengthens a magnetic circuit A214 and the static magnetic field within which the armature body A208a is suspended, which maintaining a compact design.

[0508] As shown in Fig. 2C and 2G, the magnetic structure further comprises one or more outer permanent magnets A205a, A205b and A206, which locate on an outer side of the armature and cross the general, major plane A224 of the armature A208, as described in relation to the eleventh aspect. In this embodiment, three permanent magnets are located and oriented in this manner, but any number of one or more permanent magnets may otherwise be implemented in this manner. This arrangement strengthens a magnetic circuit A214 and the static magnetic field within which the armature body A208a is suspended, which maintaining a compact design.

[0509] As shown in Figs. ID and IE, in accordance with the twelfth aspect of the disclosure, the smart glasses device Al 00 comprises a body Al 01 having an enclosure for accommodating the audio transducer A200. The body A101 of the device A100 comprises a depth dimension Al l i, and the audio transducer A200 accommodates at least approximately 70 percent of this depth dimension. In the case of a smart glasses device Al 00 as per this embodiment, the body Al 01 is one of the arms AlOla, AlOlb of the device A100. Both arms preferably comprise this feature. This arrangement is advantageous in terms of maximising compactness without compromising on performance of audio transducer A200.

[0510] As shown in Figs. 1C and ID, in accordance with the thirteenth aspect of the disclosure, the device Al 00 further comprises a vent Al 07 for releasing air pressure, the vent Al 07 being formed in an arm Al 01 and configured to locate proximal to a user’s ear in use. The device Al 00 further comprises an air channel Al 10 extending along the arm Al 01 to direct oppositephase air pressure generated by the audio transducer A200 away from the ear in use. This arrangement is advantageous in terms of increasing sound pressure experienced by a user of the device Al 00. The air channel Al 10 preferably directs opposite-phase air pressure to an opposite side of the user’s pinna in use. When the device Al 00 is worn by a user for instance, the air channel Al 10 locates proximal to a side of the arm Al 01 that faces a user’s head, in use. The air channel Al 01 preferably has a convex profile at an outer wall of the air channel Al 01. The air channel Al 01 preferably also comprises multiple exit air vents Al 07 distributed along the length of the arm Al 01. In an embodiment a surface area of the vents increases in regions more distal from the diaphragm relative to regions proximal to the diaphragm of the audio transducer A200. Both arms AlOla and AlOlb preferably comprise these feature.

[0511] Negative stifjhess transducing mechanism + thin hinge + rigid diaphragm

[0512] The transducing mechanism of a balanced armature motor has negative stiffness, and so requires an armature suspension system to overcome the negative stiffness and “balance” the armature in the neutral position. In the A200 transducer, the armature suspension system is also the diaphragm hinge system, comprising flexing hinge member A211. If the flexing elements of member A211 are made thinner, then the fundamental resonance of the transducer is reduced, providing an advantage of a wider bandwidth of operation. The use of the combination of a negative stiffness transducing mechanism with a flexing hinge member is advantageous in that, all else being equal, the hinge member may be made stiffer. This can lead to advantages such as

[0513] I. being more robust in a drop scenario, which is of particular importance for a. free-edge diaphragm transducers similar to A200, b. mobile devices such as smart glasses Al 00, and / or c. when used with a thick and rigid diaphragm structures such as used in driver A200,

[0514] II. when used with a thick and rigid diaphragm structures such as used in driver A200 the lowest resonant modes of the suspension system defined by the hinge member (such as A211) with the exception of the fundamental rotational mode of the diaphragm about the axis of rotation Al 09, may be increased. This raises the frequency of the resonance modes above the mid-range frequencies which are commonly regarded as more critical for sound quality and human voice recognition, preferably above the audible frequency range of human hearing.

[0515] III. being easier to manufacture long and rigid diaphragm + free edge +rigid attachment to armature + rotating

[0516] The use of a long and rigid diaphragm A201 with a peripheral edge free of attachment to a surround, rigidly attached to armature A208, with the whole diaphragm assembly rotating about a single axis Al 09 may provide many other advantages such as:

[0517] 1. lower fundamental frequency of operation, improving bass bandwidth,

[0518] 2. improved breakup performance, improving sound quality,

[0519] 3. thin and narrow form factor suitable for small devices

[0520] 4. high volume excursion capability, improving bass performance.

[0521] Free edge diaphragm related advantages

[0522] The free diaphragm periphery design provides various advantages such as a possibility to increase diaphragm excursion and low-frequency response / bandwidth within a thin and / or narrow form factor, and also to improve high-frequency resonance characteristics and bandwidth. The free edge feature therefore synergistically complements features such as 1) a diaphragm having a substantially thick body relative to a radial length and / or width of the body, 2) a diaphragm having a substantially long radial length 3) a diaphragm extending directly from the rigid armature for thinner overall form and increased diaphragm extremity and volume excursion, combined with a strong, efficient, simple and miniaturisable motor system. There is further synergy with a balanced armature motor having features such as a shifting of magnet(s) to one or more edges of the armature, for compactness, and / or with hinge systems featuring thinned and / or separated flexing elements, for improved excursion angle, and / or with flexing elements that extend in the diaphragm axis direction for improved excursion angle.

[0523] A free edge diaphragm extending from a balanced armature motor design may provide another benefit whereby a more robust flexing hinge system may be employed, leading to improved robustness against potential damage from diaphragm displacement into surround such as in an uncontrolled impact or drop. At the same time positive stiffness of the robust hinge system may be partially cancelled by “negative stiffness” inherent in the magnet / armature design reducing the restriction to low-frequency bandwidth associated with stiffer suspension. This may be beneficial in case of a thick diaphragm and / or a larger and / or heavier and / or outer reinforced diaphragm where drop-scenario displacements may increase and / or impact with surround may be more likely to result in damage.

[0524] The combination of free edge diaphragm design with a balanced armature motor is also beneficial in a contact of small transducers having one or more dimensions less than 7mm, or more preferably less than 5mm and / or in applications where the transducer is located proximal to the ear, since at small scale and with correspondingly especially narrow air gaps diaphragm protection via stoppers becomes difficult to manufacture at low cost, as are many other motor and lower-stiffness diaphragm suspension systems.

[0525] 10. Conclusion

[0526] Methods of construction of audio transducers, devices or any of the various structures, assemblies, mechanisms, devices, or systems are described herein for some but not all embodiments for the sake of conciseness. The application of such methods to other embodiments are not intended to be excluded from the scope of this invention. The invention is also intended to cover methods of transducing audio signals using the principles of operation and / or audio transducer features described herein.

[0527] The disclosure set forth above may encompass multiple distinct examples with independent utility. Although each of these has been disclosed in its preferred form(s), the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense, because numerous variations are possible. Modifications may be made thereto without departing from the scope of the disclosure as defined in the accompanying claims.

[0528] To the extent that section headings are used within this disclosure, such headings are for organizational purposes only. The subject matter of the disclosure includes all novel and nonobvious combinations and sub combinations of the various elements, features, functions, and / or properties disclosed herein.

Claims

1. CLAIMS1. An apparatus, comprising: a substantially narrow housing, wherein a length of the housing is substantially greater than a width and a thickness thereof; an audio transducer assembly disposed within the housing, the assembly comprising: a diaphragm, the diaphragm having a first major face and an opposing second major face; a transducing mechanism operatively coupled to the diaphragm and configured to convert between electrical signals and mechanical vibration of the diaphragm; and a metallic enclosure substantially encapsulating at least the diaphragm, wherein the metallic enclosure is an integrally formed unit and defines a cavity shaped to provide a minimal operational clearance sufficient to accommodate a full range of motion of the diaphragm; wherein the metallic enclosure comprises at least one enclosure aperture providing an acoustic pathway from the diaphragm.

2. The apparatus of claim 1, wherein the housing comprises a housing aperture aligned with the enclosure aperture to provide an acoustic pathway from the diaphragm to an exterior of the housing.

3. The apparatus of claim 1 or claim 2, wherein the metallic enclosure and the housing are joined at one or more junction regions, and wherein at least one of said junction regions comprises a progressive decrease in a wall thickness of the housing in a direction toward the metallic enclosure.

4. The apparatus of claim 3, wherein the progressive decrease in the wall thickness is formed by a plurality of discrete steps.

5. The apparatus of claim 3 or claim 4, wherein the progressive decrease in the wall thickness is formed by a substantially continuous and smooth taper.

6. The apparatus of any one of claim 3 to claim 5, wherein a plurality of said junction regions comprise the progressive decrease in the wall thickness of the housing.

7. The apparatus of any one of claim 1 to claim 6, wherein the metallic enclosure and the housing are joined at one or more junction regions, and wherein at least one of said junction regions comprises a progressive increase in a wall thickness of the housing in a direction toward the metallic enclosure.

8. The apparatus of any one of claim 1 to claim 7, wherein the metallic enclosure comprises at least one profiled edge region configured to join with the housing.

9. The apparatus of claim 8, wherein at least one of said profiled edge regions is formed by an inwardly angled wall of the metallic enclosure, the wall extending toward the cavity.

10. The apparatus of either one of claim 8 or claim 9, wherein at least one of said profiled edge regions has a variable wall thickness.

11. The apparatus of claim 10, wherein the variable wall thickness is formed by one or more recesses, creating a stepped profile.

12. The apparatus of claim 10 or claim 11, wherein the variable wall thickness is formed by a substantially continuous and smooth taper.

13. The apparatus of any one of claim 1 to claim 12, wherein the metallic enclosure comprises: a first face-plate positioned adjacent the first major face of the diaphragm; a second face-plate positioned adjacent the second major face of the diaphragm; and at least one side wall extending between the first and second face-plates.

14. The apparatus of claim 13, wherein at least one profiled edge region is located on at least one of the first face-plate or the second face-plate.

15. The apparatus of claim 13 or claim 14, wherein at least one profiled edge region is located on the at least one side wall.

16. The apparatus of any one of claim 1 to claim 15, wherein the metallic enclosure further comprises an extension plate extending longitudinally from a terminal end thereof.

17. The apparatus of claim 16, wherein the extension plate extends beyond a region occupied by the transducing mechanism.

18. The apparatus of claim 16 or claim 17, wherein the extension plate is inwardly angled or curved.

19. The apparatus of any one of claim 15 to claim 18, wherein the extension plate tapers in width toward a distal end thereof.

20. The apparatus of any one of claim 1 to claim 19, wherein the housing comprises a plastics material.

21. The apparatus of any one of claim 1 to claim 20, wherein the housing is formed from a first material and the metallic enclosure is formed from a second material, and wherein the second material has a higher yield strength than the first material.

22. The apparatus of claim 21, wherein a Young's Modulus of the second material is at least ten times greater than a Young's Modulus of the first material.

23. The apparatus of any one of claim 1 to claim 22, wherein the metallic enclosure has a first bending stiffness, and wherein a portion of the housing adjacent the metallic enclosure has a second bending stiffness that is less than the first bending stiffness.

24. The apparatus of claim 23, wherein the first bending stiffness is at least five times greater than the second bending stiffness.

25. The apparatus of any one of claim 1 to claim 24, wherein the metallic enclosure is formed from a material having a Young's Modulus of at least 10 GPa.

26. The apparatus of claim 25, wherein the material has a Young's Modulus of at least 20 GPa.

27. The apparatus of any one of claim 1 to claim 26, wherein the housing has a wall thickness of less than 1.2mm adjacent the audio transducer assembly.

28. The apparatus of claim 27, wherein the wall thickness is less than 0.8mm.

29. The apparatus of any one of claim 1 to claim 28, wherein the metallic enclosure is a single, unitary component.

30. The apparatus of any one of claim 1 to claim 29, wherein the metallic enclosure comprises at least two separate components metallurgically bonded together.

31. The apparatus of any one of claim 1 to claim 30, wherein at least a portion of the metallic enclosure comprises a ferromagnetic metal.

32. The apparatus of any one of claim 1 to claim 31, wherein the metallic enclosure forms at least a portion of the transducing mechanism.

33. The apparatus of claim 32, wherein the metallic enclosure forms at least a portion of a magnetic structure of the transducing mechanism.

34. The apparatus of any one of claim 1 to claim 33, wherein the at least one enclosure aperture comprises one or more first apertures positioned to align with the first major face of the diaphragm, and one or more second apertures positioned to align with the second major face of the diaphragm.

35. The apparatus of any one of claim 1 to claim 34, wherein the metallic enclosure comprises perforations arranged to preserve structural triangulation.

36. The apparatus of any one of claim 1 to claim 35, wherein a length of the audio transducer assembly is at least 2 times greater than a thickness of the audio transducer assembly, and at least 1.5 times greater than a width of the audio transducer assembly.

37. The apparatus of any one of claim 1 to claim 36 wherein the apparatus is a smart glasses device, and the housing is an arm of the device.

38. The apparatus of any one of claim 1 to claim 37 wherein the transducing mechanism is an armature-type mechanism comprising: a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and39. The apparatus of claim 38 wherein the diaphragm is directly coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature.

40. The apparatus of claim 39, wherein the diaphragm is mechanically coupled to and extends from an end of the armature.

41. The apparatus of claim 40, wherein the diaphragm, the armature, and the mechanical coupling therebetween are substantially rigid, forming a unified moving assembly.

42. The apparatus of claim 40 or 41, wherein a major plane of the diaphragm is substantially parallel to a major plane of the armature.

43. The apparatus of claim 42, wherein the major plane of the diaphragm is offset from the major plane of the armature.

44. The apparatus of claim 43, wherein the offset is defined along an axis perpendicular to said major planes and is less than a thickness of the magnetic structure.

45. The apparatus of claim 42, wherein the major plane of the diaphragm is substantially coplanar with the major plane of the armature.

46. The apparatus of any one of claim 39 to 45, wherein the diaphragm and the armature extend in substantially opposing directions from the axis of rotation.

47. The apparatus of claim 39 to 46, wherein the diaphragm is mechanically coupled to the armature via a lateral cross-member.

48. The apparatus of claim 47, wherein the lateral cross-member is substantially orthogonal to a longitudinal axis of the armature.

49. The apparatus of claim 48, wherein the lateral cross-member and a connection tab of the armature form a T-shaped connection.

50. The apparatus of claim any one of claim 47 to 49, wherein an end face of the diaphragm is coupled to a face of the lateral cross-member.

51. The apparatus of any one of claim 47 to 50, wherein the armature extends from a first side of the cross-member and the diaphragm extends from an opposing, second side of the cross-member.

52. The apparatus of any one of claim 39 to 51, wherein the diaphragm is mechanically coupled to an end of the armature located proximal to the axis of rotation.

53. The apparatus of any one of claim 39 to 52, wherein the diaphragm is mechanically coupled to an end of the armature located distal to the axis of rotation.

54. The apparatus of claim any one of claim 39 to 53, wherein the diaphragm comprises a recess at a base end thereof, the recess being shaped to accommodate a corresponding portion of the armature for the mechanical coupling.

55. The apparatus of any one of claim 1 to claim 54, wherein the audio transducer assembly further comprises a hinge rotatably coupling the armature to a transducer base structure.

56. The apparatus of claim 55, wherein the hinge comprises a substantially elongate and resilient flexing element.

57. The apparatus of claim 56, wherein the flexing element is a substantially thin flexing plate.

58. The apparatus of claim 56 or 57, wherein the flexing element is oriented substantially parallel to a major plane of the armature when the armature is in a neutral rotational position.

59. The apparatus of any one of claim 56 to 58, wherein the flexing element comprises a torsion spring.

60. The apparatus of any one of claim 56 to 59, wherein the flexing element is coupled to a central region of the armature and extends from the central region along the axis of rotation toward opposing sides of the armature.

61. The apparatus of any one of claim 56 to 60, wherein the flexing element is coupled to a connection tab of transducer assembly.

62. The apparatus of any one of claim 55 to 61, wherein the diaphragm comprises a recess at a base end thereof, and wherein the hinge is located at least partially within the diaphragm recess.

63. The apparatus of any one claim 55 to 62, wherein the hinge comprises a flexible metal element.

64. The apparatus of claim 63, wherein the flexible metal element is a flexible metal spring.

65. The apparatus of claim 63 or 64, wherein the flexible metal element primarily comprises iron or a combination of iron and cobalt.

66. An audio transducer comprising: a transducer base structure, a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; anda diaphragm directly coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature.

67. An audio transducer comprising: a transducer base structure, a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure ; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to and extending from an end of the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature.

68. An audio transducer comprising: a transducer base structure, a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to and extending from a lateral cross-member at an end of the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature.

69. An audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, the armature being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, a structure closely surrounding and directly adjacent an outer peripheral edge of the diaphragm and wherein the outer peripheral edge of the diaphragm is substantially free from physical connection with the surrounding structure.

70. An audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field ; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure within the static magnetic field; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration in the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, wherein the magnetic structure comprises a pair of magnetic bodies, each of which comprises asurface opposing the armature and having a plane that is substantially angled relative to a longitudinal axis of the armature.

71. An audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field, and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration in the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, wherein the diaphragm is substantially thick in at least a region of the diaphragm, relative to a length and / or width dimension of the diaphragm.

72. An audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration in the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature,a hinge pivotally coupling the armature to the transducer base structure, and comprising a flexing element oriented substantially parallel to a general, major plane of the armature in a neutral rotational position of the armature and hinge, wherein the flexing element comprises a thickness substantially smaller than a thickness of the armature measured orthogonally to the major plane.

73. An audio transducer comprising: a transducer base structure a magnetic structure configured to generate a static magnetic field therebetween; an armature positioned suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, a hinge pivotally coupling the armature to the transducer base structure, and having at least one elongate, flexible, and resilient element coupled to a central region of the armature and extending from the central region along the axis of rotation towards opposing sides of the armature.

74. An audio transducer comprising: a transducer base structure a magnetic structure configured to generate a static magnetic field therebetween; an armature positioned suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure ;a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature; and a hinge pivotally coupling the armature to the transducer base structure, wherein the diaphragm comprises a recess, and the hinge is located at least partially within the diaphragm recess.

75. An audio transducer comprising: a transducer base structure; a magnetic structure configured to generate a static magnetic field ; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure ; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature, wherein at least one magnetic body of the magnetic structure extends substantially beyond a terminal end of the armature distal to the diaphragm.

76. An audio transducer comprising: a transducer base structure;a magnetic structure configured to generate a static magnetic field ; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure ; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to the vibration of the armature; wherein the magnetic structure comprises one or more outer permanent magnets located on an outer side of the armature and extending across a general, major plane of the armature.

77. An apparatus, comprising: an audio transducer having: a transducer base structure; a magnetic structure configured to generate a static magnetic field ; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure ; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to vibration of the armature; and a body having an enclosure for accommodating the audio transducer;wherein the body of the apparatus comprises a depth dimension, and the audio transducer accommodates at least approximately 50 percent of the depth dimension of the body.

78. An apparatus, comprising: an audio transducer having: a transducer base structure; a magnetic structure configured to generate a static magnetic field ; an armature suspended within the static magnetic field and being capable of pivoting about an axis of rotation relative to the transducer base structure ; a conductive coil surrounding at least a portion of the armature and configured to generate a varying magnetic field in response to a received electrical audio signal to induce vibration of the armature about the axis of rotation; and a diaphragm mechanically coupled to the armature, configured to vibrate relative to the transducer base structure and produce sound waves in response to vibration of the armature; and a body having an enclosure for accommodating the audio transducer; wherein a thickness of the audio transducer is at least approximately 50 percent of a depth of the body at a region where the audio transducer is located.

79. An apparatus comprising: a spectacles frame with arms extending from either side of the frame ; an audio loudspeaker transducer; a vent for air pressure formed in one of the arms to locate proximal to a user’s ear in use;an air channel extending along the arm to direct opposite-phase air pressure generated by the audio transducer away from the ear in use.

80. An apparatus comprising: a spectacles frame having an arm; an audio transducer disposed within the arm, the transducer having a first side configured to generate positive-phase sound pressure and an opposing, second side configured to generate opposite-phase sound pressure during operation; a first opening formed in portion of the arm proximal to the audio transducer and fluidly coupled to the first side of the audio transducer; an air channel extending within the arm, the air channel having an inlet fluidly coupled to the second side of the audio transducer and an outlet formed in a portion of the arm distal to the audio transducer.

81. An apparatus comprising: an audio device housing ; an audio transducer disposed within the frame, the transducer having a diaphragm, the diaphragm having a first face configured to generate positive-phase sound pressure and an opposing, second face configured to generate opposite-phase sound pressure during operation; a first opening formed in portion of the arm proximal to the audio transducer and fluidly coupled to the first side of the audio transducer; a first metal component or assembly traversing the first face of the diaphragm generating sound pressure; a second metal component or assembly traversing the second face of the diaphragm;where the first and second metal components meet and are joined at at least two sides of the diaphragm.

82. An apparatus, comprising: a substantially narrow housing, wherein a length and / or width of the housing is substantially greater than a thickness thereof; a diaphragm, the diaphragm having a first major face configured to generate positivephase sound pressure and an opposing second major face configured to generate opposite-phase sound pressure; a transducing mechanism operatively coupled to the diaphragm and configured to convert between electrical signals and mechanical vibration of the diaphragm; and a metallic enclosure substantially encapsulating at least the diaphragm, wherein the metallic enclosure is an integrally formed unit and defines a cavity shaped to provide a minimal operational clearance sufficient to accommodate a full range of motion of the diaphragm during operation; and wherein the metallic enclosure comprises at least one aperture positioned to align with the first and / or second major face of the diaphragm to provide an acoustic pathway between the diaphragm and an exterior of the enclosure.

83. An apparatus comprising: an audio transducer; a body having an enclosure for accommodating the audio transducer; wherein the body of the apparatus comprises a depth dimension that, at least in the local region of the transducer, is small relative to a maximum dimension of the body; wherein the audio transducer accommodates at least 340% of a depth dimension of the body, at the local region of the transducer;a wall of the body is attached to the transducer over one or more areas including towards at least a first end of the transducer; overall wall thickness of the body increases towards at least one end of the transducer.

84. An apparatus, comprising: a substantially narrow housing, wherein a length and / or width of the housing is substantially greater than a depth thereof; and an audio transducer assembly disposed within the housing and comprising: a diaphragm, the diaphragm having a first major face configured to generate positive-phase sound pressure and an opposing second major face configured to generate opposite-phase sound pressure; a transducing mechanism operatively coupled to the diaphragm and configured to convert between electrical signals and mechanical vibration of the diaphragm; wherein, the housing comprises a housing aperture aligned with the diaphragm to provide an acoustic pathway from the diaphragm to an exterior of the housing; and wherein, the audio transducer assembly and the housing are joined at one or more junction regions, and wherein at least one of said junction regions comprises a progressive decrease in a wall thickness of the housing in a direction toward the audio transducer assembly.

85. An audio transducer comprising: a transducer base structure; a diaphragm; a transducing mechanism operatively coupled to the diaphragm and configured to convert between electrical signals and mechanical vibration of the diaphragm;a hinge pivotally coupling the diaphragm to the transducer base structure, and having at least one elongate, flexible, and resilient element extending in a direction substantially parallel to the axis of rotation between attachment points to the armature assembly and to transducer base structure.

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