electroacoustic transducer

Abstract

A magnetic structure for an air motion transformer (AMT) electroacoustic transducer is provided that includes a diaphragm assembly (7), the magnetic structure including at least one magnet (6) disposed at least partially within the diaphragm assembly (7).

Description

Detailed Description of the Invention

[0001] [Technical Field] The present invention relates to electroacoustic transducers and electroacoustic systems (e.g., loudspeakers and loudspeaker systems), particularly of the air motion transformer (AMT) type, and magnetic motor structures thereof. In particular, the present invention relates to distributed magnet arrays for multilayer thin-film electroacoustic transducers.

[0002] 〔background〕 In the field of loudspeaker transducers, dynamic drivers dominate and can be easily identified by their diaphragm, which is usually cone- or dome-shaped. Despite variations in design, they all operate on the same principle: sound is generated when a voice coil connected to the diaphragm moves through a magnetic gap in a magnet structure due to electromagnetic forces. In this type of transducer, the effective area capable of displacing air corresponds to the visible surface area of the diaphragm.

[0003] However, a group of electroacoustic transducers exists that have a "serpentine" (or "pleated") diaphragm made from insulating thin foil or film, or another type of thin flexible or semi-rigid substrate, carrying conductive traces on its surface. Therefore, a separate voice coil is not required. These so-called "air motion transformers," due to their inherently large active area and small moving mass, provide excellent air coupling, resulting in excellent transient response and very low distortion.

[0004] Several embodiments of air motion transformers (also referred to by those skilled in the art as "AMTs") are described in U.S. Patent No. 3,636,278 by inventor Oskar Heil. The essential operating principle of an AMT is described as multiple substantially parallel vibrating diaphragm layers alternately closed at the front or back (a "serpentine" or "pleated" structure), with semi-enclosed air pockets between the layers, creating acoustic dipoles. Electrical conductors bonded to a membrane substrate are arranged so that the paths of charged particles moving through the conductive traces are substantially perpendicular to the magnetic field created by the motor structure, while currents in adjacent layers flow in opposite directions. The resulting Lorentz force causes adjacent diaphragm layers to move toward or away from each other depending on the direction of the current, thereby producing an acoustic output that is substantially parallel to the diaphragm layers.

[0005] Modified embodiments of the original AMT design are described in numerous other patents, including, for example, the "reinforced" AMT detailed in U.S. Patent No. 8,208,678 B2, in which each ridge in the pleated section of the diaphragm is reinforced with stiffening elements that control parasitic vibrations.

[0006] Another example AMT variation is described in U.S. Patent No. 9,124,964 B2, in which parallel diaphragm layers are curved to control the directionality of the acoustic output, although the main operating principle remains the same: an active element consisting of multilayer thin-film diaphragms placed in a strong magnetic field.

[0007] The aforementioned air motion transformer devices and their magnetic motor structures all share various limitations. Because permanent magnets are dipoles, their magnetic field decays rapidly with distance, following an inverse cube law. Therefore, one of the key challenges in thin-film multilayer transducers is creating a magnetic field strong enough to drive the diaphragm layer, which is difficult due to the large magnetic gap defined by the width of the diaphragm structure. Prior art motors typically combine permanent magnets with magnetic pole pieces made of soft magnetic material placed directly in front of and behind the diaphragm. The purpose of using the magnetic pole pieces is to direct as much magnetic flux as possible across the diaphragm, thereby limiting stray magnetic fields and increasing transducer efficiency. However, arranging the pole pieces in this way blocks the exit of the vibrating diaphragm, reducing acoustic transparency and introducing a cavity effect that adversely affects the high-frequency response of the transducer. Alternatively, omitting the pole piece elements would result in problems with increased stray magnetic field and reduced efficiency of the transducer, limiting the acoustic power that can be generated.

[0008] It is therefore undeniable that there is a need to optimize the configuration of the AMT transducer and its magnetic motor structure in order to fully exploit the advantages that air motion transformers can bring in the field of sound reproduction.

[0009] Summary of the Invention Aspects and embodiments of the invention are set out in the accompanying claims. These and other aspects and embodiments of the invention are described herein.

[0010] An object of the present invention is to provide a novel motor configuration for an AMT transducer, in which multiple magnets are distributed within the boundaries of a diaphragm assembly (e.g., stack) between individual diaphragm layers, thereby placing the magnets in closer proximity to conductive traces. This novel configuration facilitates ironless motor designs for air motion transformers and eliminates the need for additional pole pieces (e.g., made of soft magnetic material). Additionally, the present disclosure provides a solution for removing obstructions from the acoustic output path of an AMT transducer.

[0011] According to a first aspect of the present invention, there is provided a magnetic structure for an air motion transformer (AMT) electroacoustic transducer including a diaphragm assembly, the magnetic structure including at least one magnet disposed at least partially within the diaphragm assembly.

[0012] This has the advantage of allowing the magnetic flux to be directed locally (more efficiently) to the diaphragm layers. As used herein, "disposed within" preferably means disposed within the geometric structure of the diaphragm assembly; this may alternatively be described as being within the same volume (i.e., volume of space) occupied by the diaphragm assembly. This applies to any shape the diaphragm assembly may assume. The entire magnet may or may not be disposed within the diaphragm assembly; thus, one or more magnets may be at least partially disposed within the diaphragm assembly. For example, only a portion of one or more magnets may be within the structure. The relevant portions of the diaphragm assembly may be referred to as the multiple (vibratable) layers of the diaphragm assembly (e.g., the structure formed by the multiple (vibratable) layers of the diaphragm assembly). The multiple (vibratable) layers of the diaphragm assembly may form geometric structures of various shapes (e.g., a "linear" configuration having a generally rectangular parallelepiped shape, or a more complex shape such as a "curved structure"). A "magnetic structure" may alternatively be described in terms of a "magnet structure."

[0013] At least one of the magnets may be at least partially disposed within the bounds of the diaphragm assembly, preferably within the geometric bounds of the diaphragm assembly. As used herein, disposed "within the bounds" preferably means disposed within the boundary or perimeter of the geometric structure of the diaphragm assembly.

[0014] At least one of the magnets may be disposed at least partially within the footprint of the diaphragm assembly. As used herein, the term "at least partially within the footprint" preferably means at least partially within the geometric area projection of the diaphragm assembly in all directions (orientations).

[0015] In a preferred implementation, at least one of the magnets is disposed between adjacent vibratable layers of the diaphragm assembly. This may facilitate direct and efficient magnetic flux across the vibratable layers. Preferably, this refers to a magnet being disposed within a volume defined between adjacent vibratable layers, e.g., a magnet being disposed within a volume defined between the planes of two adjacent vibratable layers. The vibratable layers of the diaphragm assembly may include at least one electrical conductor. The vibratable layers of the diaphragm assembly may be vibratable to propagate sound. At least a portion of the magnet may be disposed between two adjacent layers (the magnet may be disposed at least partially between multiple layers).

[0016] In some implementations, the magnetic structure may further include at least one additional magnet on the outside of the diaphragm assembly, which can further enhance the magnetic flux across the diaphragm assembly. The at least one additional magnet may be disposed adjacent to at least one side of the diaphragm assembly. As used herein, the term "side" preferably refers to all sides of the diaphragm assembly, including "top," "bottom," "end," etc. This may also preferably encompass all sides of a complex shape. The term "side" may also encompass all positions or locations adjacent to any face of the shape. Different portions, sections, or parts of the magnetic structure may utilize different configurations of multiple magnets inside and outside the diaphragm stack. This may, for example, involve configuring different portions, sections, or parts for different frequency ranges.

[0017] In some implementations, the magnetic structure may further include at least one pole piece component, which may assist in directing and enhancing magnetic flux. The at least one pole piece component may be disposed adjacent to the diaphragm assembly, preferably adjacent to at least one side surface of the diaphragm assembly. As defined above, the term "side surface" as used herein preferably encompasses all sides of the diaphragm assembly.

[0018] Preferably, at least one of the magnets is configured such that its magnetic flux is aligned with the plane of the vibratable layers of the diaphragm assembly, which may assist in directing the magnetic flux to the vibratable layers, thereby enhancing the effect of the Lorentz force on the vibratable layers. Preferably, the magnet is configured such that its magnetic flux is perpendicular or at least substantially perpendicular to the electrical conductors (i.e., the direction of current) of the vibratable layers. Alternatively, the magnet may be configured such that its magnetic flux is aligned with the plane of the vibratable layers of the diaphragm assembly, which may assist in promoting the Lorentz force acting perpendicularly on the layers.

[0019] In some implementations, the magnetic structure includes at least two magnets, the magnets arranged such that their magnetic flux is constructively superimposed. The magnetic flux may be aligned with and constructively superimposed on the vibratable layers of the diaphragm assembly and / or may be adjacent to the vibratable layers of the diaphragm assembly. This may enhance the magnetic flux, preferably the magnetic flux aligned with and / or adjacent to the vibratable layers.

[0020] In some implementations, the magnetic structure may include multiple magnets disposed on only one side of the diaphragm assembly. This may facilitate prioritizing acoustic output on one side of the diaphragm assembly. This may be useful, for example, in a loudspeaker configured to emit sound in only one direction. In some examples, the diaphragm assembly may be configured as a pleated structure, with multiple magnets disposed on only one side of the pleated structure. Multiple vibratable layers may be formed by adjacent layers of the pleated structure. As used herein, the term "side" preferably refers to one side of the diaphragm assembly, preferably the side to which sound waves can propagate. For example, the magnets may be disposed only within pleats that are open to one side (the side to which sound waves can propagate). In some implementations, the magnetic structure may include multiple magnets disposed alternately between adjacent vibratable layers of the diaphragm assembly. Where the diaphragm assembly comprises a pleated structure, for example, this may facilitate providing magnets on only one side of the pleated structure.

[0021] In some implementations, the magnetic structure may include multiple magnets disposed on both sides of the diaphragm assembly and / or between successive pairs of adjacent vibratable layers of the diaphragm assembly. In this case, the multiple magnets may further enhance magnetic flux. The multiple magnets may be disposed between every pair of adjacent vibratable layers of the diaphragm assembly, or may be disposed only between some pairs.

[0022] According to a further aspect of the present invention, there is provided an air motion transformer (AMT) electroacoustic transducer including a diaphragm assembly including a plurality of diaphragm layers each including at least one electrical conductor, and a magnetic structure, the magnetic structure including at least one magnet disposed at least partially within the diaphragm assembly.

[0023] The magnetic structure may be a magnetic (or magnet) structure as described above.

[0024] Preferably, the diaphragm assembly may surround and / or contain at least a portion (e.g., at least one portion) of at least one of the magnets. Preferably, the (geometric) volume of the diaphragm assembly may contain at least a portion (e.g., at least one portion) of at least one magnet. Preferably, the multiple (vibratable) layers of the diaphragm assembly may surround and / or contain at least a portion (e.g., at least one portion) of at least one of the magnets. Preferably, the (geometric) volume formed by the multiple (vibratable) layers of the diaphragm assembly may contain at least a portion (e.g., at least one portion) of at least one magnet. This may be contained in the volume occupied by the multiple (vibratable) layers and the spaces between the multiple (vibratable) layers.

[0025] In some implementations, the diaphragm assembly may include multiple vibratable layers, and at least one of the magnets (at least a portion of the magnet) may be disposed between adjacent vibratable layers of the diaphragm assembly. As defined above, at least one of the magnets (at least a portion of the magnet) may be disposed within a volume defined between adjacent vibratable layers, for example, within a volume defined between planes of two adjacent vibratable layers.

[0026] The vibratable layers of the diaphragm assembly may be vibratable via at least one portion made of a flexible material. The flexible material may be resilient and / or elastic. The vibratable layers of the diaphragm assembly may be vibratable via an interface (or mechanism) that facilitates increased excursion (excursion refers to the range or distance the vibratable layers move during vibration). The vibratable layers may be suspended (e.g., elastically and / or vibratably suspended) via the interface (or mechanism). The mechanism may be any mechanism for facilitating elastic suspension.

[0027] In some implementations, the diaphragm assembly may include at least one vibratable layer that includes a rigid or semi-rigid portion. Such a structure may be useful for promoting increased excursion (i.e., vibration over a larger range), which may be beneficial for lower frequencies. The rigid or semi-rigid portion may alternatively be referred to as being stiff or having stiffness. This rigidity or stiffness may promote stability of the larger layer or portion, thereby promoting increased excursion. The rigid or semi-rigid portion may be suspended and vibratable via the portion made of flexible material. For example, the rigid or semi-rigid portion may be connected to a structure via a flexible and / or elastic material, which may help promote vibration. In some implementations, the portion made of flexible material may at least partially surround the rigid or semi-rigid portion.

[0028] In some implementations, the diaphragm assembly may include a first section in which a plurality of the vibratable layers have a first width and a second section in which a plurality of the vibratable layers have a second width, which may be used to configure different sections for different purposes (e.g., for different frequencies).

[0029] The AMT electroacoustic transducer may further include a frame configured to support the diaphragm assembly.

[0030] At least one of the magnets may be mounted on a removable magnet carrier, preferably configured to reversibly retain the at least one magnet at least partially within the diaphragm assembly. In some implementations, the magnet carrier is configured to reversibly engage with a frame or the frame such that the at least one magnet is retained at least partially within the diaphragm assembly. This may facilitate interchange between magnets mounted on one or both sides of the diaphragm assembly and / or between magnets mounted on various sections of the diaphragm assembly.

[0031] The AMT electroacoustic transducer may further include a support adjacent to at least one intersection of adjacent vibrable layers of the diaphragm assembly. The support may be rigid (e.g., a rigid polymer) to provide support and / or structure for the flexible diaphragm. The diaphragm may be formed of a flexible thin film or foil. The diaphragm may include conductive tracks and / or traces for carrying electrical current.

[0032] According to a further aspect of the present invention, an air motion transformer (AMT) electroacoustic transducer assembly may be provided. The AMT electroacoustic transducer assembly includes a diaphragm assembly, a frame for supporting the diaphragm assembly, and a removable magnet carrier for carrying at least one magnet. The frame is configured to reversibly engage the magnet carrier such that the at least one magnet is at least partially retained within the diaphragm assembly. This may facilitate reconfiguration of the magnetic structure (at least one magnet). The frame may be configured to reversibly engage the magnet carrier on both sides of the diaphragm assembly.

[0033] The AMT electroacoustic transducer assembly may include the magnetic structure and / or the AMT electroacoustic transducer (eg, as described above).

[0034] According to a further aspect of the present invention, there is provided an air motion transformer (AMT) electroacoustic transducer including a diaphragm assembly and at least one magnet disposed at least partially within the diaphragm assembly. According to a further aspect of the present invention, there is provided an air motion transformer (AMT) electroacoustic transducer including a diaphragm assembly and a magnetic structure, the magnetic structure including at least one magnet disposed at least partially within the diaphragm assembly. According to a further aspect of the present invention, there is provided an air motion transformer (AMT) electroacoustic transducer assembly including a diaphragm assembly, a frame for supporting the diaphragm assembly, and at least one magnet provided within the diaphragm assembly.

[0035] According to one aspect of the present invention, there is provided a distributed magnet structure or a distributed magnetic structure for the air motion transformer electroacoustic transducer, wherein at least one permanent magnet is arranged within the boundaries of the diaphragm stack or diaphragm assembly, the magnet being arranged between two adjacent vibratable diaphragm layers.

[0036] In some implementations, at least one additional magnet may be positioned outside the boundary of the diaphragm stack or the diaphragm assembly, and the magnet may be positioned proximate to at least one side of the diaphragm stack or the diaphragm assembly.

[0037] In some implementations, at least one additional pole piece element may be added to a magnet section proximate at least one end of the diaphragm stack or the diaphragm assembly.

[0038] According to a further aspect of the present invention, there is provided a distributed magnet structure or a distributed magnetic structure for the air motion transformer electroacoustic transducer, wherein at least one permanent magnet is arranged at least partially within the boundaries of the diaphragm stack or diaphragm assembly, the magnet being arranged at least partially between two adjacent vibratable diaphragm layers.

[0039] In some implementations, at least one additional magnet section may be positioned outside the boundary of the diaphragm stack or the diaphragm assembly, and the magnet may be positioned proximate to at least one side of the diaphragm stack or the diaphragm assembly.

[0040] In some implementations, at least one additional pole piece element may be added to a magnet section proximate at least one end of the diaphragm stack or the diaphragm assembly.

[0041] In some implementations, the AMT transducer may further include a diaphragm stack including multiple diaphragm layers with gaps formed between adjacent layers, wherein at least one magnet of the spatially distributed magnetic structure described is disposed, in whole or in part, in some or all of the gaps.

[0042] In some implementations, an air motion transformer (AMT) array may include a plurality of the described AMT transducers disposed adjacent to one another such that sound generated by the plurality of AMT transducers is emitted from each respective AMT transducer in a selected direction relative to the device.

[0043] In some implementations, the orientation of each respective AMT transducer relative to the device may be different for some or all of the AMT transducers such that a desired acoustic radiation pattern can be achieved.

[0044] As used herein, a "diaphragm assembly" may refer to multiple (at least two) diaphragm layers. As used herein, a "diaphragm stack" may refer to a configuration of multiple (at least two) diaphragm layers (not limited to any orientation).

[0045] The present invention extends to methods and / or apparatus substantially as herein described with reference to the accompanying drawings.

[0046] Any aspect of an apparatus described herein may also be provided as an aspect of a method, and vice versa.

[0047] Features of one aspect of the present invention may be applied to other aspects of the present invention in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some, and / or all features of one aspect may be applied to any, some, and / or all features of any other aspect in any appropriate combination.

[0048] It is also to be understood that the detailed combinations of the various features described and defined in any aspect of the present invention may be implemented and / or provided and / or utilized independently.

[0049] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A (Prior Art) illustrates an example of AMT operating principles, showing a cross-sectional view of a typical AMT transducer with a "classical" motor structure in a "positive" half-wave operating mode.

[0050] FIG. 1B (Prior Art) illustrates an example of the AMT operating principle, showing a cross-sectional view of the "negative" half-wave operating mode using an example of a typical AMT transducer with a "classical" motor structure.

[0051] FIG. 2 (Prior Art) is a longitudinal cross-sectional view of one of the "classical" magnetic motor structure configurations for the AMT transducer shown in FIGS. 1A and 1B.

[0052] FIG. 3 is an ISO diagram showing an example of an AMT in a linear configuration, with the diaphragm stack having the novel distributed magnet structure in a "one-sided" configuration.

[0053] FIG. 4 shows a further ISO view of the diaphragm stack of FIG. 3 with the novel distributed magnet structure in a "double-sided" configuration.

[0054] FIG. 5 is a diagram of the diaphragm stack in a "single-sided" configuration, including a depiction of the direction of current flow through the conductive traces for the "positive" half-wave mode of operation.

[0055] FIG. 6 is a diagram of the diaphragm stack in a "double-sided" configuration, including a depiction of the direction of current flow through the conductive traces for the "positive" half-wave mode of operation.

[0056] FIG. 7 is a longitudinal cross-sectional view of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG. 3 or FIG.

[0057] FIG. 8 is a longitudinal cross-sectional view of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG. 4 or FIG.

[0058] Figure 9 shows an example of a wide-angle AMT configuration with a "serpentine" or "pleated" diaphragm and a novel distributed magnet structure in a "single-sided" configuration. Included is a depiction of the current flow direction through the conductive traces for the "positive" half-wave operating mode.

[0059] Figure 10 shows an example of a wide-angle AMT configuration with a "serpentine" or "pleated" diaphragm and a novel distributed magnet structure in a "double-sided" configuration. Included is a depiction of the current flow direction through the conductive traces for the "positive" half-wave operating mode.

[0060] FIG. 11A is a horizontal cross-sectional view of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG.

[0061] FIG. 11B is a close-up view of a portion of the cross section of FIG. 11A.

[0062] FIG. 12A is a horizontal cross-sectional view of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG.

[0063] FIG. 12B is a close-up view of a portion of the cross section of FIG. 12A.

[0064] FIG. 13 shows an example of a 360 degree AMT configuration with a serpentine shaped diaphragm and the novel distributed magnet structure in a "one-sided" configuration, exhibiting a "positive" half-wave mode of operation.

[0065] FIG. 14 shows an example of a wide-angle AMT configuration with a curved arc diaphragm assembly and a novel distributed magnet structure using multiple rectangular magnets.

[0066] FIG. 15 shows an example of a wide-angle AMT configuration with a curved arc diaphragm assembly and a novel distributed magnet structure using curved radially magnetized magnets.

[0067] Detailed Description of the Invention and Preferred Embodiments The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms "a," "an," and "the" are intended to include the plural as well as the singular, unless the context clearly dictates otherwise. Furthermore, as used herein, it will be understood that the terms "comprises" and / or "comprising" specify the presence of stated structures, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other structures, steps, operations, elements, components, and / or groups thereof.

[0068] Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and this disclosure, and should not be interpreted in an idealized or overly formal way unless expressly defined in this specification.

[0069] In describing the present invention, it will be understood that many techniques and steps have been disclosed. Each of these has its own advantages and can also be used in combination with one or more (or in some cases, all) of the other techniques disclosed. Therefore, for the sake of clarity, this specification will refrain from unnecessarily repeating all possible combinations of the individual steps. Nevertheless, the specification and claims should be read with the understanding that such combinations are fully encompassed within the scope of the invention and claims.

[0070] This disclosure describes a novel distributed magnet structure or distributed magnetic structure for use in conjunction with AMT transducers, developed to maximize magnetic field strength in a target area while minimizing the volume of magnetic material required to construct an efficient motor. A further advantage of using a distributed magnet array is that it provides perhaps the only way to construct an ironless motor for an air motion transformer-type transducer, thereby eliminating the need for additional pole pieces. Finally, by distributing the magnets within the diaphragm structure, the entire transducer can be contained within the footprint of the diaphragm assembly (e.g., stack) itself, allowing for significant miniaturization of the transducer compared to prior art AMT solutions, opening up countless possibilities for practical applications where space constraints are critical.

[0071] Specific embodiments of the present invention will now be described in detail with reference to the accompanying figures. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details.

[0072] The present disclosure is to be considered as illustrative of the invention and is not intended to limit the invention to the specific embodiments shown in the drawings or the following description.

[0073] To better understand the problems arising from standard motor configurations, the operating principle of an AMT known from the prior art is shown schematically in Figures 1A and 1B. The illustrated embodiment of an AMT transducer includes a "meander-shaped" diaphragm 4 (typically made of a substrate material having conductive traces or tracks on its surface) folded back and forth to form substantially parallel layers 4a, air pockets 5 formed between the layers 4a, a magnet 2, a front pole piece 1, and a rear pole piece 3. Diaphragm 4 can therefore be described as having a "pleated" structure, forming multiple layers 4a (formed from a continuous sheet of substrate) or a stack of layers 4a. FIG. 1A illustrates the "positive" half-wave operation of the diaphragm layer and the corresponding direction of sound wave propagation depending on the direction of current I, and FIG. 1B illustrates the "negative" half-wave operation of the diaphragm layer and the corresponding direction of sound wave propagation depending on the direction of current I. When current I flows along traces in opposite directions in adjacent layers 4a of the diaphragm 4, Lorentz forces act in opposite directions on each adjacent layer 4a (because they are all in the same magnetic field). This creates a "bellows" effect that generates acoustic output. As shown in FIG. 1A, when current flows in a first direction, the "positive" half-wave operation of the diaphragm layer 4a simultaneously expels air through the opening in the front pole piece 1 and draws air in through the opening in the rear pole piece 3. As shown in FIG. 1B, when the current flows in the reverse direction, the "negative" half-wave action of diaphragm layer 4a causes air to be drawn in through the opening in front pole piece 1 and simultaneously expelled through the opening in rear pole piece 3, thus generating an acoustic pressure wave.

[0074] FIG. 2 shows one configuration of a typical motor magnetic structure known from prior art embodiments. A magnet 2 is positioned adjacent to the outermost diaphragm layer 4a, and front and rear pole pieces 1 and 3 encase the diaphragm structure on both sides. The figure also shows magnetic field lines 10 to illustrate the distribution of the magnetic field in the context of the entire transducer assembly. This placement of magnet 2 adjacent to the top and bottom of the diaphragm structure, with pole pieces 1 and 3 positioned at the front and rear of the stack, results in an inefficient configuration. The configuration requires an excessive amount of magnet volume to provide a sufficient magnetic field to enable movement of the diaphragm layer 4a. Furthermore, the use of pole pieces 1 and 3 introduces unnecessary obstacles into the propagation path of sound waves. This results in undesirable distortion due to cavity effects, which degrades sound quality.

[0075] As shown in the examples of Figures 3, 4, 5, 6, 9, 10, 13, 14, and 15, this disclosure describes a configuration in which one or more magnets 6 are positioned directly between multiple diaphragm layers 4a and within the footprint of the diaphragm assembly. This configuration significantly reduces the volume of permanent magnets used compared to prior art solutions, resulting in reduced transducer weight and improved material utilization. This also reduces or eliminates the need for pole pieces, further reducing weight. Additionally, as shown in Figures 7, 8, 11A, 11B, 12A, and 12B, providing magnetic flux 10 in close proximity to conductive traces 11 at precise locations on the diaphragm layers is more targeted and has the added benefit of reducing stray magnetic fields.

[0076] The simplest embodiment of the present invention would consist of two adjacent AMT diaphragm layers 4a with a single magnet 6 or a magnetic array structure of multiple magnets 6 disposed within the air pocket 5 between the two adjacent diaphragm layers 4a. Each diaphragm layer includes a substrate material (flexible foil or thin film) on which conductive tracks or traces 11 are provided. The conductive traces 11 may be bonded onto the diaphragm 4. However, because the air motion transformer diaphragm assembly (e.g., stack) 7 can consist of any number of layers 4a, the improved magnetic structure may have magnets 6 distributed throughout all or part of the air pocket 5 formed by the adjacent diaphragm layers 4a. 4 and 6 show an example of a linear AMT embodiment in which magnets 6 are positioned between each diaphragm layer 4a of a diaphragm assembly (e.g., stack) 7 (i.e., in every gap between layers or between every pair of layers) (while FIGS. 3 and 5 show an embodiment in which magnets 6 are positioned between every other pair of diaphragm layers 4a).

[0077] 3-6 show one configuration in which the diaphragm 4 is folded back and forth to form parallel layers 4a (or at least substantially parallel or nearly parallel layers). The stack of layers 4a is connected by connecting portions 4b on alternating sides (e.g., front, back, front) to form a "serpentine" or "pleated" shape. The layers 4a and connecting portions 4b in the illustrated embodiment are formed from a single, continuous diaphragm 4, because this provides a simpler and more efficient structure. (However, in some alternative embodiments, this may not be the case, as this is not essential to the practice of the present invention.) As shown in FIGS. 3 and 4, the "pleated" shapes may be formed as square wave shapes. In this case, fold lines 4c are present at the intersections between the layers 4a (i.e., at the lines where adjacent layers 4a meet, or where layers 4a and connecting portions 4b meet). These fold lines 4c connect each of the portions of the diaphragm 4 (layers 4a and connecting portions 4b). 5 and 6, the connecting portions 4b may have a more curved cross-section, resulting in curved cross-sections at the intersections between the layers 4a of the diaphragm 4 assembly. The connecting portions 4b of the diaphragm 4 may be pre-formed prior to the assembly process and incorporated into the diaphragm assembly without additional reinforcement, or the connecting portions 4b between adjacent layers 4a may take the form of diaphragms 4 that curve around supports (e.g., struts).

[0078] The "length" of the stack of layers 4a can be considered to be the direction in which the layers 4a are stacked (this can also be considered to be the overall or average direction of motion of the "serpentine" or pleated structure - thus, it can be straight or curved). The "height" of the stack of layers 4a can be considered to be the dimension parallel to the intersections between the layers 4a (e.g., fold lines 4c). The "width" can be said to be the dimension perpendicular to the length and height as defined herein. The magnet 6 is oriented so that the magnetic flux 10 is substantially perpendicular to the direction of the conductive traces (as is necessary for the generation of the Lorentz force). In the configurations of FIGS. 3-6, as shown in particular in FIGS. 5 and 6, the conductive traces are arranged parallel to the intersections (e.g., fold lines 4c) of the diaphragm layers 4a, with the north pole of the magnet 6 adjacent to the intersection on one side (e.g., the front side) and the south pole adjacent to the intersection 4c on the opposite side (e.g., the rear side); in other words, the north and south poles of the magnets extend from one intersection (e.g., the fold line 4c) to the next and are therefore perpendicular to the intersections (e.g., the fold line 4c). The north and south poles of the magnets can be said to extend along the width (as defined above) of the diaphragm 4 assembly. In this implementation, the conductive traces 11 can also be described as extending parallel to the "height" of the stack of multiple layers 4a. Conductive traces 11 are typically implemented to meander or bend across diaphragm 4 so that current flows in opposite directions on each adjacent layer 4a and then makes a complete turn (e.g., 180 degrees, or at least approximately 180 degrees) as it travels into the next layer 4a. For example, conductive trace 11 may extend along the length of each layer 4a, then make a 90° turn, pass through end section 4b, and continue onto the next layer 4a, before turning back 90° and meandering upward in the opposite direction along the length of the adjacent layer 4a. Thus, in effect, conductive trace 11 travels a path spanning a 180° angle between adjacent layers 4a. In this manner, conductive trace 11 carries current in opposite directions on adjacent layers 4a.

[0079] Although the magnet 6 used in the examples shown in Figures 3-6 and 9-10 is a single bar magnet, each layer of the magnetic structure may consist of multiple individual magnets. The permanent magnets used may be of any type (e.g., neodymium, ferrite, or ceramic) and may have any shape dictated by design requirements (e.g., rod, cube, arc, cylinder, or irregular shape). Furthermore, Figures 5 and 6, as well as Figures 9 and 10, show an exemplary implementation in which a single conductive trace extends along the diaphragm 4 assembly. However, it should be understood that the conductive path may consist of multiple conductors (conductive traces), which typically extend parallel or nearly parallel to one another.

[0080] Because of its dipole nature, the AMT can be used by utilizing acoustic output from both sides of the transducer (e.g., when used in an "open" configuration) or by favoring only one side of the transducer. If only one side is favored, the acoustic output on the other side can either be absorbed or redirected—these concepts will be familiar to those skilled in the art. In either of these cases, magnets can be placed on both sides of the diaphragm so that there is a magnet between every pair of adjacent diaphragm layers 4a (a "double-sided" configuration), or magnets can be placed on only one side of the diaphragm so that there is a magnet between every other pair of adjacent diaphragm layers 4a (a "single-sided" configuration).

[0081] In a "single-sided" configuration, the present invention accommodates a preferred configuration in which magnets 6 can be placed between every other pair of layers 4a. This configuration allows sound pressure waves to propagate unimpeded on one side of the transducer. Examples of such configurations are shown in Figures 3, 5, and 13, in which magnetic structures 6 are placed only in air gaps 5 open on one side (e.g., the rear side), while air gaps 5 open on the other side (e.g., the front side) remain unobstructed. As a result, the effects of introducing unwanted acoustic cavities are eliminated. In contrast, Figures 4 and 6 show a "double-sided" configuration in which magnets 6 are placed between every pair of layers 4a.

[0082] To illustrate how the present invention facilitates various modes of AMT operation, such as "single-sided" and "double-sided" configurations, Figures 7 and 8 show example magnet distributions and resulting spread of magnetic field 10 for the AMT configurations shown in Figures 3 and 5, and the AMT configurations shown in Figures 4 and 6, respectively.

[0083] The proposed magnet placement and orientation exploits the symmetry of the magnetic field 10 between adjacent magnets 6, resulting in a structural overlap of the magnetic field 10 between adjacent magnets 6 at the location of the diaphragm layer 4a. This provides the added benefit of straightening the magnetic flux lines 10 at the location of the moving diaphragm layer 4a. In the "single-sided" configuration shown in FIGS. 3 and 5, distributing the magnets between every other air pocket 5 (i.e., between every other pair of layers 4a) results in a slightly weaker magnetic field 10 (as shown in FIG. 7) than in the "double-sided" configuration shown in FIGS. 4 and 6 (as shown in FIG. 8). However, this allows all undesired objects to be removed from the acoustic path on one side of the device's output, thereby minimizing (or eliminating) the problem of acoustic cavity effects. This approach may provide additional opportunities for transducer optimization, for example, by reducing the distance between certain diaphragm layers 4a to improve efficiency and further reduce the overall volume of the diaphragm assembly 7 (a stack of multiple layers 4a). However, if the most efficient motor structure is a priority for a selected application, a "double-sided" configuration can be implemented in which magnets occupy the entire air gap 5 between the diaphragm layers 4a, as shown in Figures 4 and 6 (with the magnetic field shown in Figure 8). Depending on the desired use case and target specifications, a more preferred motor embodiment (or combination thereof) can be selected accordingly. Furthermore, the gap between the magnets 6 and the diaphragm layers 4a can be fine-tuned to promote maximum displacement of the diaphragm layers 4a while optimizing the magnetic field strength and, preferably, avoiding the formation of high particle velocity regions at the duct exits of adjacent diaphragm layers 4a.

[0084] This solution can easily accommodate diaphragms of any shape or curved profile (e.g., circular, elliptical, or irregular), including a full 360-degree circle, a straight profile with no curve, and any selected angle in between. Examples of such implementations with improved magnetic structures in various types of air motion transformers are shown in Figures 3, 4, 5, 6, 9, 10, 13, 14, and 15. In particular, Figures 3-6 show "straight" configurations, while Figures 9, 10, 14, and 15 show arcs, and Figure 13 shows a circular configuration.

[0085] Similar to the linear profile embodiment, preferred "single-sided" and "double-sided" magnet configurations for the wide-angle "arcuate" variation of the AMT are shown in Figures 9 and 10, respectively. This radial AMT structure is based on a serpentine-shaped or pleated diaphragm 4, which may be contained within the footprint of a complete circle, a circular segment of any selected angle, or any curved path. In this implementation, each of the multiple layers 4a may be slightly tilted relative to the adjacent layer 4a so that the footprint of the diaphragm 4 forms an overall curve at the required angle.

[0086] The magnet placements presented follow the same general rules as the linear-profile embodiments, with magnetic material 6, for example, positioned between every pair of diaphragm layers 4 a in FIG. 10 or between every other pair of diaphragm layers 4 a in FIG. 9. While a single magnet is shown between layers 4 a in FIGS. 9 and 10, an array of multiple separate magnets may alternatively be used. The magnetic field distribution corresponding to the configuration of FIG. 9 (a "single-sided" configuration) is shown in FIG. 11A, with a partial close-up shown in FIG. 11B for clarity. Similarly, the magnetic field distribution corresponding to the configuration of FIG. 10 (a "double-sided" configuration) is shown in FIG. 12A, with a partial close-up shown in FIG. 12B for clarity.

[0087] Conductive traces 11 run up and down each layer 4a of the diaphragm such that current flows perpendicular to the magnetic field and in opposite directions between adjacent layers 4a. In the example shown in Figures 9 and 10, as in the embodiment shown in Figures 3-6, current flows parallel to the intersections between the layers 4a. This can be said to be parallel to the normal to a plane containing the "curved" footprint of the diaphragm assembly 7, or equivalently, parallel to the axis of curvature (i.e., the axis from which the radius of curvature extends perpendicularly, or equivalently, the axis of a cylinder where the arc is a portion of the cylinder). It should be understood that while Figures 9 and 10 show specific conductive trace configurations, alternative arrangements and configurations could be used.

[0088] 13 shows an alternative implementation in which the conductors 11 follow paths that are substantially parallel to the top and bottom edges of the diaphragm 4 (rather than meandering back and forth in opposite directions along the multiple diaphragm layers 4a). In this illustrated example, the diaphragm assembly 7 has a circular structure, and thus the "serpentine" or "pleated" structure forms a circular footprint. While the example shown in FIG. 13 shows a simplified configuration of a single conductive trace 11, the conductive path may consist of multiple conductors that run parallel or nearly parallel to one another.

[0089] In the configuration shown in FIG. 13, the magnet 6 is positioned so that its north pole is at the bottom end (base) of the diaphragm 4 and its south pole is at the top end of the diaphragm 4, so that the conditions necessary for the generation of the Lorentz force are maintained. Of course, these poles could be reversed. In other words, the north and south poles of the magnet are aligned with the height of the diaphragm assembly 7 (where the height is aligned with the axis of curvature, which is the axis from which the radius of curvature extends perpendicularly, or equivalently, the axis of the cylinder formed by the diaphragm assembly 7). While FIG. 13 shows a single bar magnet positioned alternately between the diaphragm layers 4a in a "one-sided" configuration, each portion of the magnetic structure may consist of multiple separate magnets 6, and the magnetic structure 6 may be positioned between all of the diaphragm layers 4a for a "two-sided" configuration.

[0090] These configurations may be implemented by providing a frame that supports the diaphragm 4 and magnet 6. As an example, the frame may include a top frame and a bottom frame that are provided on top and bottom of the diaphragm 4 and magnet 6. Thus, in the curved configurations shown in FIGS. 9 and 10, these frame pieces (i.e., the top and bottom frame pieces) are curved (corresponding to the overall curvature of the footprint of the diaphragm 4 and the footprint of the diaphragm assembly 7). In the linear configurations shown in FIGS. 3-6, these frame pieces are linear. In some examples, additional supports are provided extending between these frame pieces, extending adjacent each intersection (e.g., fold, apex, or curved shape) between adjacent layers 4a. The supports may be configured according to the configuration of the layers 4a and diaphragm assembly 7. The supports may have structures configured to accommodate the folds and / or curves and may have various shapes, such as curved or angular (e.g., right-angled) cross sections.

[0091] In some examples, one or more magnets 6 may be provided on a substructure (e.g., a magnet carrier) that can be fitted between multiple diaphragm layers 4a. These magnet carriers can be held in place by a frame and, in some examples, are reversibly insertable and removable. They can be held in place by fitting into corresponding grooves in the top and / or bottom frame pieces. These magnet carriers may be reversibly fitted into the frame to change the number and / or position of magnets used. For example, in this manner, a user can change from a "single-sided" configuration to a "double-sided" configuration, or vice versa. Magnet carriers are typically formed of a rigid polymer to provide structural support without adding unnecessary weight.

[0092] Alternative configurations of the diaphragm 4 and support may also be used. Depending on the variation and specific structure of the AMT transducer, the diaphragm stack may include support elements 8 disposed between adjacent layers to secure them in place. Examples of such AMT variations are shown in FIGS. 14 and 15. The diaphragm 4 is configured as an arc-shaped section containing conductive traces, with each layer 4a of the diaphragm extending the entire length of the assembly (in this example, a curved arc). In this case, the conductive traces extend along the (curved) length of each layer 4a, fold back at the ends, and extend along the length of the adjacent layer 4a. As a result, current flows in opposite directions in adjacent layers 4a of this folded assembly (or stack). Therefore, in contrast to the embodiments shown in FIGS. 9 and 10 above, the direction of current is along the arc of the curve (rather than parallel to the normal to the plane containing the curve, or equivalently, parallel to the axis of curvature). In contrast to the embodiment shown in FIG. 13 above, the diaphragm layer 4a is not radially disposed but rather curves to follow the footprint. The magnets 6 are disposed between the layers 4a so that their magnetic field is perpendicular to the direction of the current flowing through the conductive traces. In this example, the north pole is oriented radially outward relative to the curve, and the south pole is oriented radially inward (although the reverse would also be possible). The support elements 8 could be designed to have the secondary purpose of securing the proposed novel magnet structure in place. Alternatively, dedicated fixtures could be designed to serve the purpose of attaching the magnets in place. The support elements 8 are typically formed from a rigid polymer, as this provides support while keeping weight relatively low.

[0093] In FIG. 14 , multiple magnets 6 are distributed between the curved diaphragm layers 4 a. For illustrative purposes, we may refer to the cross-sectional view of a diaphragm segment in FIG. 7 and convert it to the curved shapes shown in FIGS. 14 and 15 . As with the previous examples, the diaphragm assembly (e.g., stack) 7 in a curved embodiment may include the presented magnet structure between each diaphragm layer (a “double-sided” configuration), between every other diaphragm layer (a “single-sided” configuration), or any combination of the two. Furthermore, FIG. 14 shows a magnet array consisting of multiple discrete rectangular magnets oriented radially along the curvature of the diaphragm 4. However, the implementation could include different magnet configurations with magnets of any shape (e.g., including a single curved magnet as shown in FIG. 15 , or multiple curved magnets). Furthermore, the configurations of FIG. 13 , 14 , or 15 could be provided in linear implementations.

[0094] Further Embodiments, Alternatives and Possible Implementations The presented embodiments of the invention may include numerous variations depending not only on design requirements but also on the nature of the operating environment, desired frequency response, transducer size, output capabilities, and / or acceptable distortion levels, among other factors. The illustrated and described example embodiments are merely a selection of preferred configurations and do not constitute an exhaustive list of all possible combinations.

[0095] Although the described and illustrated embodiments utilize a (at least substantially) flat diaphragm layer, it is entirely possible to impart corrugations to the diaphragm structure. This can be achieved, for example, by thermoforming. Corrugations can, for example, have a beneficial effect on mechanical break-up characteristics and potentially extend the available frequency range.

[0096] Additionally, while the embodiments described above have diaphragms made from thin films or foils, the diaphragm (or portions of its components) may alternatively be made from other types of flexible, semi-rigid, or rigid substrates. Rigid or semi-rigid diaphragms may offer the advantage of increased stiffness, allowing the pistonic motion of the diaphragm to be maintained over a wider frequency range.

[0097] Additionally, the structure of some or all of the diaphragm layer may include a suspension, which may, for example, facilitate increased excursion of the diaphragm layer. As used herein, the term suspension preferably refers to any means for mounting or connecting a diaphragm so that the diaphragm can vibrate. Such a suspension may be achieved, for example, by thermoforming or by adding a separate flexible mounting interface made, for example, of rubber, foam-like material, etc. As an example, a rigid or semi-rigid diaphragm portion may be surrounded (or at least partially surrounded) by a rubber connecting interface, which allows the rigid or semi-rigid diaphragm portion to vibrate.

[0098] It will be apparent to those skilled in the art that the magnetic poles in the embodiments shown in Figures 3, 4, 5, 6, 9, 10, 13, 14, and 15 could be reversed, resulting in a 180° phase shift in the acoustic output, while otherwise preserving all operational capabilities of the transducer. Alternatively, the magnetic poles could be rotated 90° or 270° if the conductors bonded onto the diaphragm substrate material were reconfigured so that the direction of current traveling through them is substantially perpendicular to the magnetic field lines.

[0099] The curved embodiment described and illustrated is configured as a single arc. However, the present invention may be implemented in a variety of shapes. For example, it may be configured as a single arc, a full 360° circle, or an irregular shape containing curves and / or vertices. It may be formed from a series of arcs (e.g., four arcs of 90° each, or three arcs of 120° each), which may be arranged in combination to form a full or partial circular configuration.

[0100] The present invention can provide good sound directionality. Therefore, the present invention can generally be advantageously implemented in a variety of scenarios. The curved implementation of the present invention can be configured to direct sound inward, toward the center of the effective circle formed by the speaker. This could be utilized, for example, for headphones. The efficient use of materials provided by the present invention can provide more efficient sound reproduction at a lighter weight, thereby improving comfort. Furthermore, the efficient use of materials provided by the present invention allows for more creative design of such headphones. In an alternative implementation, sound may be directed outward from the curved speaker configuration, for example, for implementation in a standalone speaker unit. As an example, the "one-sided" configuration described above may be implemented and configured appropriately to prioritize unobstructed sound output in a particular direction (e.g., radially inward for headphones, radially outward for loudspeakers).

[0101] In some implementations, in addition to the magnets provided within the diaphragm assembly, additional magnets may be provided outside the diaphragm assembly. In one such implementation, the present invention can be utilized to augment the magnetic field provided by a "classical" motor design (with magnets provided at the adjacent ends of the diaphragm assembly) by adding a novel distributed magnet structure within the diaphragm assembly, further enhancing the magnetic field at some or all locations on the vibratable diaphragm.

[0102] In some implementations, the present invention can be combined with prior art solutions by utilizing both types of magnet configurations in a single transducer. For example, a "classical" motor structure (with magnets located outside the diaphragm assembly) can be applied to a portion of the diaphragm assembly (e.g., a diaphragm section designed to reproduce high frequencies). In such a section, the diaphragm width is small, and therefore providing a magnetic field strength sufficient to promote Lorentz force generation using the "classical" motor structure is practical due to the small magnetic gap. In another section of the diaphragm assembly, for example, a diaphragm section designed to reproduce low and / or mid-range frequencies, the novel distributed motor structure can be applied to a diaphragm section with a larger diaphragm width. In this section configured for low and / or mid-range frequencies, the magnetic gap of a "classical" motor would be too large, requiring an excessive amount of magnet volume to provide a magnetic field strength sufficient to promote Lorentz force generation. Therefore, implementing a novel distributed magnetic structure would be preferable. One such configuration provides a transducer that is configured to provide good output at a variety of frequencies.

[0103] It should be understood that the present invention has been described above by way of example only, and that modifications of detail may be made within the scope of the present invention. While the present invention has been shown and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those skilled in the art that other embodiments and examples may perform a similar function and / or achieve similar results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are contemplated therefor, and are intended to be encompassed by the following claims.

[0104] Each feature disclosed in this specification, and (where appropriate) the claims and drawings, may be provided independently or in any appropriate combination.

[0105] Any reference signs appearing in the claims are for illustrative purposes only and shall not be deemed to limit the scope of the claims.

[0106] Further aspects of the present disclosure are described in the following clauses: 1. A distributed magnetic structure for an air motion transformer electroacoustic transducer, wherein at least one permanent magnet is disposed within the boundaries of said diaphragm stack, said magnet being disposed between two adjacent vibratable diaphragm layers.

[0107] 2. A distributed magnetic structure as described in clause 1, wherein at least one additional magnet is positioned outside the boundary of the diaphragm stack, the magnet being positioned in close proximity to at least one side of the diaphragm stack.

[0108] 3. A distributed magnetic structure as described in clause 2, wherein at least one additional pole piece element is added to a magnet section proximate at least one end of the diaphragm stack.

[0109] 4. A distributed magnetic structure for an air motion transformer electroacoustic transducer, wherein at least one permanent magnet is disposed at least partially within the boundaries of said diaphragm stack, said magnet being disposed at least partially between two adjacent vibratable diaphragm layers.

[0110] 5. A distributed magnetic structure as described in clause 4, wherein at least one additional magnet section is positioned outside the boundary of the diaphragm stack, the magnet being positioned in close proximity to at least one side of the diaphragm stack.

[0111] 6. A distributed magnetic structure as described in clause 5, wherein at least one additional pole piece element is added to a magnet section proximate at least one end of said diaphragm stack. [Brief explanation of the drawings]

[0112] [Figure 1A] 1 shows an example of AMT operating principles, using an example of a typical AMT transducer with a "classical" motor structure, showing a "positive" half-wave operating mode in cross section. [Figure 1B] An example of the AMT operating principle is shown using an example of a typical AMT transducer with a "classical" motor structure, showing a cross-sectional view of the "negative" half-wave operating mode. [Figure 2] FIG. 2 is a longitudinal cross-sectional view of one of the "classical" magnetic motor structure configurations for the AMT transducer shown in FIGS. 1A and 1B. [Figure 3] 1 is an ISO diagram showing an example of an AMT in a linear configuration, with the diaphragm stack having the novel distributed magnet structure in a "one-sided" configuration. [Figure 4] 4 shows a further ISO view of the diaphragm stack of FIG. 3 with the novel distributed magnet structure in a "double-sided" configuration. [Figure 5] FIG. 10 is a diagram of a diaphragm stack in a "single-sided" configuration, including a depiction of the direction of current flow through the conductive traces for a "positive" half-wave mode of operation. [Figure 6] FIG. 10 is a diagram of a diaphragm stack in a "double-sided" configuration, including a depiction of the direction of current flow through the conductive traces for a "positive" half-wave mode of operation. [Figure 7] 6 is a longitudinal cross-sectional view of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG. 3 or FIG. 5. [Figure 8] FIG. 7 is a longitudinal cross-sectional view of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG. 4 or FIG. 6. [Figure 9] An example of a wide-angle AMT configuration with a "serpentine" or "pleated" diaphragm and a novel distributed magnet structure in a "single-sided" configuration is shown, including a depiction of the current flow direction through the conductive traces for the "positive" half-wave operating mode. [Figure 10]An example of a wide-angle AMT configuration with a "serpentine" or "pleated" diaphragm and a novel distributed magnet structure in a "double-sided" configuration is shown, including a depiction of the current flow direction through the conductive traces for the "positive" half-wave operating mode. [Figure 11A] FIG. 10 is a horizontal cross-sectional view of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG. [Figure 11B] FIG. 11B is a close-up view of a portion of the cross section of FIG. 11A. [Figure 12A] 11 is a horizontal cross-section of the magnetic structure and resulting magnetic field lines for the transducer shown in FIG. 10. [Figure 12B] FIG. 12B is a close-up view of a portion of the cross section of FIG. 12A. [Figure 13] 1 shows an example of a 360 degree AMT configuration with a serpentine-shaped diaphragm and a novel distributed magnet structure in a "one-sided" configuration, exhibiting a "positive" half-wave mode of operation. [Figure 14] An example of a wide-angle AMT configuration is shown, which has a curved arc diaphragm assembly and a novel distributed magnet structure using multiple rectangular magnets. [Figure 15] An example of a wide-angle AMT configuration is shown with a curved arc-shaped diaphragm assembly and a novel distributed magnet structure using curved radially magnetized magnets.

Claims

1. 1. A magnetic structure for an air motion transformer (AMT) electroacoustic transducer including a diaphragm assembly, comprising: The magnetic structure includes at least one magnet disposed at least partially within the diaphragm assembly.

2. 10. The magnetic structure of claim 1, wherein at least one of the magnets is at least partially disposed within the boundaries of the diaphragm assembly, preferably within the geometric boundaries of the diaphragm assembly.

3. 3. The magnetic structure of claim 1, wherein at least one of the magnets is disposed at least partially within the footprint of the diaphragm assembly.

4. 4. A magnetic structure according to claim 1, wherein at least one of the magnets is disposed between adjacent vibratable layers of the diaphragm assembly.

5. further comprising at least one additional magnet external to said diaphragm assembly; 5. A magnetic structure according to any one of claims 1 to 4, wherein the at least one further magnet is preferably provided adjacent the assembly, preferably adjacent at least one side of the diaphragm assembly.

6. further comprising at least one pole piece component; 6. A magnetic structure according to any preceding claim, wherein at least one of the pole piece components is preferably provided adjacent the diaphragm assembly, preferably adjacent at least one side of the diaphragm assembly.

7. A magnetic structure according to any preceding claim, wherein at least one of the magnets is configured such that magnetic flux is aligned with a plurality of vibratable layers of the diaphragm assembly.

8. the magnetic structure includes at least two magnets; The magnetic structure according to any one of claims 1 to 7, wherein the plurality of magnets are arranged so that their magnetic fluxes are structurally overlapped.

9. 9. The magnetic structure of claim 8, wherein the magnetic flux is aligned with and structurally overlapped to a plurality of vibratable layers of the diaphragm assembly and / or is proximate to and structurally overlapped to a plurality of vibratable layers of the diaphragm assembly.

10. a plurality of magnets disposed on only one side of the diaphragm assembly; The magnetic structure according to any one of claims 1 to 9, wherein the diaphragm assembly is preferably configured as a pleated structure, and the plurality of magnets are provided on only one side of the pleated structure.

11. 11. A magnetic structure according to any preceding claim, comprising a plurality of magnets arranged in alternating pairs between adjacent vibratable layers of the diaphragm assembly.

12. a plurality of magnets disposed on either side of the diaphragm assembly; and / or 10. A magnetic structure according to any one of claims 1 to 9, wherein a plurality of the magnets are provided between successive pairs of adjacent vibratable layers of the diaphragm assembly, preferably a plurality of the magnets are provided between each pair of adjacent vibratable layers of the diaphragm assembly.

13. An air motion transformer (AMT) electroacoustic transducer, comprising: a diaphragm assembly including a plurality of diaphragm layers with at least one electrical conductor; a magnetic structure; Including, The magnetic structure includes at least one magnet disposed at least partially within the diaphragm assembly.

14. 14. An AMT electroacoustic transducer according to claim 13, wherein the magnetic structure is a magnetic structure according to any one of claims 1 to 12.

15. 15. An AMT electroacoustic transducer as claimed in claim 13 or 14, wherein the diaphragm assembly surrounds at least one of the magnets.

16. the diaphragm assembly includes a plurality of vibratable layers; 16. An AMT electroacoustic transducer according to any one of claims 13 to 15, wherein at least one of the magnets is provided between adjacent vibratable layers of the diaphragm assembly.

17. the plurality of vibratable layers of the diaphragm assembly are vibratable via at least one portion made of a flexible material; Preferably, the vibratable layers of the diaphragm assembly are vibratable via an interface (or mechanism) that facilitates increased excursion; More preferably, an AMT electroacoustic transducer according to any one of claims 13 to 16, wherein a plurality of said vibratable layers are suspended via said interface (or mechanism).

18. the diaphragm assembly includes at least one vibratable layer including a rigid or semi-rigid portion; Preferably, the rigid or semi-rigid part is suspended and vibrable via the part made of flexible material; More preferably, the portion made of flexible material at least partially surrounds the portion that is rigid or semi-rigid.

19. The diaphragm assembly includes: a first section of a plurality of said vibratable layers having a first width; a second section in which a plurality of the vibratable layers have a second width; 19. An AMT electroacoustic transducer according to any one of claims 1 to 18, comprising:

20. The AMT electroacoustic transducer of any one of claims 1 to 19, further comprising a frame configured to support the diaphragm assembly.

21. the at least one magnet is mounted on a removable magnet carrier; Preferably, the magnet carrier is configured to reversibly retain at least one of the magnets at least partially within the diaphragm assembly; More preferably, the magnet carrier is configured to reversibly engage with a frame or the frame such that at least one of the magnets is retained at least partially within the diaphragm assembly.

22. a support disposed adjacent at least one intersection of adjacent vibratable layers of the diaphragm assembly; Preferably, the support is rigid; More preferably, the support is a hard polymer.

23. 1. An air motion transformer (AMT) electroacoustic transducer assembly comprising: a diaphragm assembly; a frame for supporting the diaphragm assembly; a removable magnet carrier for carrying at least one magnet; Including, The frame is configured to reversibly engage the magnet carrier such that at least one of the magnets is retained at least partially within the diaphragm assembly.

24. 24. The AMT electroacoustic transducer assembly of claim 23, wherein the frame is configured to reversibly engage the magnet carrier on either side of the diaphragm assembly.

25. An AMT electroacoustic transducer assembly according to claim 23 or 24, comprising a magnetic structure according to any one of claims 1 to 12 and / or an AMT electroacoustic transducer according to any one of claims 13 to 22.

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