Transducer and associated method of operation

Abstract

A transducer is described. The transducer has a static structure having a magnetic gap surrounding an axis and a wall portion extending parallel to and facing the axis; a dynamic structure having a coil body surrounding the axis; a coil wound around the coil body, the coil body being housed in the magnetic gap; a diaphragm extending outwardly from the axis and secured to the coil body, the diaphragm having an outer peripheral edge proximate to the wall portion, the outer peripheral edge being not attached to the wall portion; and a suspension connecting the static structure to the dynamic structure, the suspension limiting a degree of freedom of movement of the dynamic structure relative to the static structure to axial movement along the axis, the suspension biasing the dynamic structure to a rest position, thereby defining a movement span xmax, the span of movement x maximum is axially defined parallel to the axis between an x positive position and an x negative position, and the wall portion covers the span of movement x maximum.

Description

Technical Field

[0001] The present improvements relate to transducers and, more particularly, to audio drivers operable to convert electrical audio signals into sound waves. Background Art

[0002] An audio driver is an electroacoustic transducer that emits sound waves when driven by an electrical audio signal, typically carrying frequencies in the audio frequency range of 20 Hz to 20 kHz. The part that interacts with the fluid (usually air) carrying the sound waves is called the diaphragm. A coil of wire, called a voice coil, is integrated with the diaphragm and movably housed in a magnetic gap. The magnetic gap typically has a ring-shaped configuration that matches the diameter of the voice coil. Circulating the electrical audio signal in the voice coil generates an electromagnetic field, which interacts with the magnetic field in the magnetic gap to drive the movement of the diaphragm. Minimizing the weight of the moving assembly, maximizing the stiffness of the diaphragm, and minimizing parasitic vibration modes can be crucial to achieving high-fidelity sound. In practice, audio driver designs are typically optimized for operation in a specific part of the audio frequency range, with audio drivers designed to reproduce high audio frequencies typically being called tweeters, those designed for intermediate frequencies typically being called mid-range audio drivers, those designed for low frequencies typically being called woofers, and those designed for the lowest audible frequencies typically being called subwoofers. Multiple audio drivers covering different parts of the audible frequency range are combined to form what is commonly referred to as a loudspeaker, although the term "loudspeaker" may also be used to refer to a device having a single audio driver, or to such a single audio driver. While existing audio driver and speaker designs are satisfactory to a certain extent, there is still room for improvement. Summary of the Invention

[0003] In order to limit the weight of the dynamic structure, the diaphragm can be made of a relatively thin layer of material. However, in order to increase its stiffness, a conical or spherical shape can be used. In some embodiments, the audio driver can have two (or more) different suspensions responsible for: i) limiting the relative movement between the static structure and the dynamic structure to the displacement axis, and ii) biasing the dynamic structure to a rest position defined along the displacement axis, thereby limiting the movement of the dynamic structure to a movement span defined relative to the displacement axis. In this field, it is common to refer to the displacement axis as the x-axis and the displacement span as the x-axis. 最大 , that is, the distance from the rest position x 零 The maximum positive movement position x 正 With the maximum negative movement position x 负 The difference between.

[0004] In one embodiment, a first suspension connects the voice coil to the frame and is commonly referred to as a "spider," and a second suspension connects the diaphragm to the frame and is referred to as a "surround." While the spider can be used to support most of the weight of the diaphragm and voice coil, the surround can prevent the outer edge of the diaphragm from rocking side to side and / or hinder undesirable vibration modes, such as artifact modes, and hinder interference that would otherwise occur at the peripheral portion of the diaphragm. Additionally, each side of the diaphragm emits sound waves in opposite phases during use. For example, in-phase sound waves are directed toward the listener while out-of-phase sound waves are directed in opposite directions, in which direction the driver or speaker structure can be configured to attenuate them to a certain extent, however a portion of the out-of-phase sound waves can be reflected and create a source of distortion. In addition to rocking protection, the surround can also prevent such out-of-phase sound waves from interfering with the in-phase sound waves.

[0005] However, despite its great usefulness and widespread use, the surround has also been found to present inconveniences. For example, the axial movement of the diaphragm is dampened by its attachment to the surround. More precisely, the movement of the diaphragm causes the surround to deform repeatedly, thus causing equal reaction forces acting on the peripheral part of the diaphragm. These forces can be transformed into small but non-negligible mechanical deformations at the level of the peripheral part, which would not otherwise be present in a first-order piston response. In addition to the deformations of the surround itself, these deformations can also disturb the wavefront of the co-directional sound waves, thereby causing undesirable behavior of higher-order modes. In addition, the presence of the surround in the audio driver increases the overall volume, as in Figure 1 2, wherein the surround 4 attaches the diaphragm 8 to the outer frame 6 of the audio driver. As the diameter of the diaphragm is represented by diameter D1, it is found that without the presence of the surround, the diaphragm can reach a diameter of up to D2. In this way, in order to obtain a similarly sized audio driver, the size of the diaphragm can be increased to produce even lower frequencies with fewer higher order modes. Alternatively, while maintaining a similarly sized diaphragm, the size of the audio driver can be reduced thereby allowing for a more compact speaker arrangement. For example, if the surround is omitted, then Figure 1 The spacings S1 and S2 shown in can both be reduced.Such spacing is particularly undesirable in a linear array of identical audio drivers, because in such a linear array the sound quality can be inversely proportional to the distance between the individual audio drivers.

[0006] It has therefore been found that the use of such peripheral members can be omitted when the construction of the audio driver is modified to address at least some of the previous functions of such peripheral members. A transducer, for example an audio driver, is described herein in which the peripheral edge of the diaphragm is not attached to a wall portion of the frame, which wall portion extends parallel to and faces the displacement axis. The peripheral edge therefore oscillates axially in a frictionless and contactless manner in the immediate vicinity of the wall portion of the frame. It has been found that satisfactory artifact mode reduction and out-of-phase sound wave blocking can still be obtained when the gap between the peripheral edge and the wall portion is sufficiently small. The frictionless and contactless pistonic motion of the peripheral edge can be ensured by ensuring that the peripheral edge is kept away from the wall portion during the entire reciprocating movement of the diaphragm. This can be achieved by holding the dynamic structure in a position with sufficiently small tolerances using a suspension and by using a sufficiently hard material to manufacture the diaphragm. In this way, the suspension can define the movement span x of the peripheral edge 最大 , where the moving span x 最大 is axially defined parallel to the displacement axis at x 正 Position and x 负 Thus, the wall portion covers the movement span x of the peripheral edge during the axial movement of the diaphragm. 最大 By doing so, the peripheral edge of the diaphragm moves over a span x 最大 The inner part moves axially in a reciprocating manner, and the outer peripheral edge moves over the entire span x 最大 The diaphragm is held in close proximity to, surrounded by, and not attached to the wall portion. Thus, the transducer and audio driver described herein can have a reduced footprint compared to existing transducers and audio drivers with similarly sized diaphragms. Such improvements can also result in a more compact audio driver array.

[0007] According to a first aspect of the present invention, there is provided a transducer comprising: a static structure having a magnetic gap surrounding a displacement axis and a wall portion extending parallel to the displacement axis and facing the displacement axis; a dynamic structure having a coil body surrounding the displacement axis; a coil wound around the coil body, the coil body being housed in the magnetic gap; a diaphragm extending outward from the displacement axis and secured to the coil body, the diaphragm having an outer peripheral edge proximate to the wall portion, the outer peripheral edge not being attached to the wall portion; and a suspension connecting the static structure to the dynamic structure, the suspension limiting the freedom of movement of the dynamic structure relative to the static structure to axial movement along the displacement axis, the suspension biasing the dynamic structure to a rest position, thereby defining a travel span x of the outer peripheral edge. 最大 , moving span x 最大 is axially defined parallel to the displacement axis at x 正 Position and x 负 Between the positions, the wall portion covers the peripheral edge over a movement span x max.

[0008] According further to the first aspect of the invention, the diaphragm may, for example, have a peripheral portion protruding from the coil body in a direction away from the displacement axis, the peripheral edge being a peripheral edge of a free end thereof.

[0009] Still further according to the first aspect of the invention, the diaphragm may, for example, have a spherical cap that is concentric with the displacement axis, the peripheral portion may, for example, extend around the spherical cap, the spherical cap may, for example, have a concave surface opposite to the convex surface, and one of the convex and concave surfaces may, for example, face away from the static structure.

[0010] According still further to the first aspect of the invention, the peripheral portion may, for example, have a frustoconical shape around the displacement axis, and the frustoconical shape may, for example, be inclined obliquely relative to the displacement axis.

[0011] According still further to the first aspect of the invention, the peripheral portion may be, for example, a portion of a spherical cap.

[0012] Still further according to the first aspect of the invention, the diaphragm may for example have a central portion surrounded by a peripheral portion, the central portion may for example have a first cross-sectional area defined relative to the displacement axis, the peripheral portion may for example have a second cross-sectional area, the first cross-sectional area being larger than the second cross-sectional area.

[0013] Still further according to the first aspect of the invention, the wall portion may, for example, be circumscribed to a first cross-sectional area defined relative to the displacement axis, and the extension of the diaphragm may, for example, form a second cross-sectional area, which covers at least 95%, preferably at least 97%, of the first cross-sectional area.

[0014] According still further to the first aspect of the invention, the suspension may, for example, have a first suspension component extending radially outwardly between the coil body and the static structure relative to the displacement axis.

[0015] According still further to the first aspect of the invention, the wall portion may, for example, be cylindrical and the peripheral edge rounded.

[0016] According still further to the first aspect of the invention, the transducer may, for example, have a gap defined radially between the peripheral edge and the wall portion, the gap being smaller than 500 μm.

[0017] According still further to the first aspect of the invention, the static structure may, for example, have an annular resonant cavity opened at a gap formed radially between the peripheral edge and the wall portion, the annular resonant cavity may, for example, have a Helmholtz frequency tuned to above the passband of the transducer.

[0018] According still further to the first aspect of the invention, the membrane may be made, for example, of a composite material.

[0019] According still further to the first aspect of the invention, the diaphragm may be made of titanium, for example.

[0020] According still further to the first aspect of the invention, the diaphragm may be made, for example, of plastic, preferably polyetheretherketone (PEEK).

[0021] According still further to the first aspect of the invention, the transducer may, for example, have a horn mounted on the transducer, the diaphragm remaining free of harmonics when operated under the additional pressure exerted by the horn.

[0022] According still further to the first aspect of the invention, the audio driver array may, for example, have a plurality of transducers mounted to each other, the plurality of transducers employing transducers according to the first aspect of the invention.

[0023] According still further to the first aspect of the present invention, the audio driver array may, for example, have an array frame having a plurality of transducer holes spaced apart from each other, the plurality of transducers being respectively mounted to corresponding ones of the plurality of transducer holes.

[0024] According still further to the first aspect of the invention, the array frame may be, for example, a housing having a wall and a cavity inside the housing, the wall containing a plurality of transducer holes exposing the cavity.

[0025] Still further according to the first aspect of the invention, the diaphragms of the plurality of transducers may, for example, together form an emitting surface area, which may, for example, cover at least 65% of the surface area of ​​the wall, preferably at least 70% of the surface area of ​​the wall, and most preferably at least 75% of the surface area of ​​the wall.

[0026] According to a second aspect of the present invention, there is provided a method for driving an audio driver, the method comprising: circulating an audio signal in the form of an electric current along a coil wound around an annular body, thereby generating an electromagnetic field, the annular body carrying a diaphragm; the electromagnetic field interacting with a magnetic field in a magnetic gap, thereby moving the diaphragm back and forth relative to the magnetic gap along a displacement axis, the process of moving the diaphragm comprising moving a peripheral edge of the diaphragm back and forth within a moving span, the peripheral edge remaining in close proximity to, surrounded by, and not attached to a wall portion throughout the moving span.

[0027] According to a third aspect of the present invention, there is provided an audio driver comprising: a static structure having a magnet assembly having a magnetic gap surrounding a displacement axis, the magnetic gap being located at a first position along the displacement axis; and a frame having a wall portion facing the displacement axis, the wall portion being located at a second position along the displacement axis, the second position being offset from the first position along the displacement axis; a dynamic structure having a voice coil having a body surrounding the displacement axis, the body having a first end, the first end being axially opposite to the second end relative to the displacement axis; and a coil wound around the body, the coil being housed in the magnetic gap; and a diaphragm secured to the first end of the body, the diaphragm extending transversely to the displacement axis and having a peripheral portion protruding from the body in a direction away from the displacement axis, the peripheral portion having a free peripheral edge adjacent to the wall portion, the free peripheral edge being not attached to the wall portion; and a suspension connecting the static structure to the voice coil, the suspension extending radially between the voice coil and the static structure relative to the displacement axis, limiting movement of the voice coil to the orientation of the displacement axis, and biasing the voice coil to a rest position.

[0028] According to a fourth aspect of the present invention, there is provided a method for driving an audio driver, the audio driver having a displacement axis, a static structure surrounding the displacement axis, the static structure having a wall portion facing the displacement axis; a dynamic structure surrounding the displacement axis, the dynamic structure having a diaphragm extending transversely to the displacement axis, the diaphragm having an edge adjacent to the wall portion; and a suspension connecting the static structure and the dynamic structure to each other, the method comprising: driving the movement of the diaphragm in a reciprocating motion along the displacement axis while maintaining the edge of the diaphragm unattached to the wall portion, the movement comprising the edge oscillating axially in a frictionless manner adjacent to the wall portion.

[0029] According to a fifth aspect of the present invention, a transducer is provided, comprising: a static structure having a magnetic gap surrounding a displacement axis, and a wall portion facing the displacement axis, the wall portion being offset from the magnetic gap along the displacement axis; a dynamic structure having a coil body surrounding the displacement axis; a coil wound around the coil body, the coil being housed in the magnetic gap; a diaphragm secured to the coil body, the diaphragm extending transversely to the displacement axis, the diaphragm having an edge adjacent to the wall portion, the edge not being attached to the wall portion; and a suspension connecting the static structure to the coil body.

[0030] Many further features and combinations thereof relating to the present improvements will be apparent to those skilled in the art after reading this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In the diagram,

[0032] Figure 1 is a partial top view of an example of a loudspeaker having a vertical array of audio drivers with surround members according to the prior art;

[0033] Figure 2 is an exploded view of an example of an audio driver according to one or more embodiments;

[0034] Figure 2A According to one or more embodiments Figure 2 An oblique view of the audio driver;

[0035] Figure 2B According to one or more embodiments Figure 2 Section 2B-2B of Figure 2A A cross-sectional view of an audio driver;

[0036] Figure 3 According to one or more embodiments Figure 2A A magnified view of the audio driver;

[0037] Figure 4 is an enlarged view of another example of an audio driver shown with an air seal according to one or more embodiments;

[0038] Figure 5 is an audio driver array shown in a column housing having four audio drivers embedded therein according to one or more embodiments;

[0039] Figure 6A 、 6B 6C are cross-sectional views of different examples of transducers shown with a convex diaphragm, a concave diaphragm, and a flat diaphragm, respectively, according to one or more embodiments;

[0040] 6 is a cross-sectional view of an example of an audio driver shown with a speaker mounted on the audio driver, according to one or more embodiments; and

[0041] Figure 7 is a cross-sectional view of another example of a transducer according to one or more embodiments. DETAILED DESCRIPTION

[0042] Figure 2 An exploded view of an example of a transducer 10' is shown. In this embodiment, the transducer 10' is provided in the form of an audio driver 10. Depending on the embodiment, the audio driver 10 can be sized, shaped, and driven to produce low-range frequencies, mid-range frequencies, or high-range frequencies. The audio driver 10 can be part of a tweeter system, a mid-range audio driver system, a woofer system, a subwoofer system, or any other type of speaker system.

[0043] As depicted, audio driver 10 has a static structure 12, a dynamic structure 14, and a suspension 16. In this example, static structure 12 has a magnet assembly 18 and a frame 20, and dynamic structure 14 has a voice coil 22 and a diaphragm 24. As shown, these components are axisymmetrical and concentric with respect to a displacement axis 26.

[0044] Figure 2A An oblique view of the audio driver 10 is shown when assembled. As shown, when the audio driver 10 is driven by an electrical audio signal, in-phase sound waves are generated in a first direction d1 extending along the displacement axis 26, while out-of-phase sound waves are generated in an opposite second direction d2 extending along the displacement axis 26. The in-phase sound waves typically have a 180 degree phase difference relative to the out-of-phase sound waves. The in-phase sound waves are typically directed to the listener L facing the diaphragm 24 of the audio driver 10. However, other components of the audio driver 10, including but not limited to the frame 20, magnet assembly 18, connectors, crown and vent can be found behind the diaphragm 24. As shown in this embodiment, the frame 20 is provided with attachment elements 28 that are distributed circumferentially around the frame 20 and radially outward therefrom. In this embodiment, the attachment elements 28 have through-holes 28' through which the frame 20 can be removably secured to a surface, such as the surface of a speaker system, for example, using fasteners.

[0045] Now refer to Figure 2B , which shows a cross-sectional view of the audio driver 10. As shown, the static structure 12 has a magnetic gap 30 surrounding the displacement axis 26, and a wall portion 32 extending parallel to and facing the displacement axis 26. In this particular example, the magnetic gap 30 is part of the magnet assembly 18 and the wall portion 32 is part of the frame 20. As shown, the magnetic gap 30 is located at a first position L1 along the displacement axis 26. The wall portion 32 is located at a second position L2 along the displacement axis, where the second position L2 is axially offset from the first position L1 along the displacement axis 26.

[0046] As depicted, the dynamic structure 14 has a coil body 34 (or "body 34") that surrounds the displacement axis 26. The body 34 has a first end 34a that is axially opposite a second end 34b relative to the displacement axis 26. The dynamic structure 14 is also equipped with a coil 36 that is wound around the body 34 and housed in the magnetic gap 30 of the magnet assembly 18. In this embodiment, the coil body 34 and the coil 36 form the voice coil 22. The diaphragm 24 is fastened to the coil body 34, and more specifically, to the first end 34a of the body 34 in this embodiment. As shown, the diaphragm 24 extends outward from the displacement axis 26. The diaphragm 24 has a peripheral edge 42 that is adjacent to the wall portion 32. The peripheral edge 42 is not attached to the wall portion 32. In this particular embodiment, the diaphragm 24 has a peripheral portion 40 that protrudes from the body 34 in a direction away from the displacement axis 26, and the peripheral edge 42 is a free peripheral edge 42' of the peripheral portion 40. Typically, the diaphragm 24 is axisymmetric, and all moving parts are coaxially and concentrically arranged relative to the displacement axis 26 .

[0047] The suspension 16 connects the static structure 12 to the dynamic structure 14. More specifically, in this embodiment, the suspension 16 extends radially outward between the coil body 34 and the static structure 12 relative to the displacement axis 26. The suspension 16 thus connects the static structure 12, e.g., the frame 20, to the voice coil 22. In this embodiment, the suspension 16 extends radially between the voice coil 22 and the static structure 12 relative to the displacement axis 26. Thus, the suspension 16 limits the movement of the voice coil 22 to the orientation of the displacement axis 26 and biases the voice coil 22 into a rest position. More specifically, the suspension 16 limits the freedom of movement of the dynamic structure 14 relative to the static structure 12 to axial movement along the displacement axis 26. The suspension 16 biases the dynamic structure 14 into the rest position, thereby defining a travel span x of the peripheral edge 42. 最大 , moving span x 最大 is defined axially, parallel to the displacement axis 26, and at x 正 Position and x 负 Thus, the wall portion 32 covers the movement span x of the peripheral edge 42. 最大 .

[0048] It is intended that the driving of the audio driver 10 comprises the steps of driving the movement of the diaphragm 24 in a reciprocating motion along the displacement axis 26 while maintaining the peripheral edge 42 of the diaphragm 24 unattached to the wall portion 32. Thus, during the driving of the audio driver 10, the peripheral edge 42 oscillates axially in a frictionless, contactless and pistonic manner in the immediate vicinity of the wall portion 32. During the pistonic movement of the diaphragm 24, the peripheral edge 42 of the diaphragm 24 moves over a span x 最大 The outer peripheral edge 42 moves back and forth in the entire moving span x最大 The inner retainer is immediately adjacent to, surrounded by, and not attached to the wall portion 32 .

[0049] The audio driver 10 can be driven by an electrical audio signal by circulating the electrical audio signal into the coil 36 of the voice coil 22. By doing so, the circulating current generates a magnetic field around the coil 36, with some of the magnetic field lines being directed axially along the displacement axis 26 within the coil 36. Because the electrical audio signal is an alternating current (AC) signal, the polarity of the electrical audio signal alternates over time. When the polarity is positive, the magnetic field lines are directed toward a first direction along the displacement axis 26, which causes the magnet assembly to axially repel (or attract) the energized coil 36. When the polarity becomes negative, then the magnetic field lines are directed toward an opposite, second, reverse switching direction along the displacement axis 26, which causes the magnet assembly to axially attract (or repel) the energized coil 36. The magnetic interaction between the magnet assembly 18 and these direction-changing magnetic lines causes the dynamic structure 14 to move in an axial reciprocating motion when driven by the AC signal. Thus, during actuation of the audio driver 10, the suspension 16 constrains the movement of the voice coil 22 to an orientation of the displacement axis 26, which prevents the voice coil 22 from contacting the inner wall of the magnetic gap 30. Preferably, the suspension 16 ensures that the coil 36 is housed in a frictionless and contactless manner within the magnetic gap 30. When actuation is interrupted, the suspension 16 biases the voice coil 22 back to the rest position.

[0050] As shown, the wall portion 32 circumscribes a first cross-sectional area A1 defined laterally relative to the displacement axis 26. Similarly, the diaphragm covers a second cross-sectional area A2 laterally relative to the displacement axis 26. In some embodiments, the second cross-sectional area A2 covers at least 95% of the first cross-sectional area A1, preferably covers at least 97% of the first cross-sectional area A1, and most preferably covers at least 99% of the first cross-sectional area A1. Thus, for a similarly sized diaphragm, the audio driver 10 can have a substantially smaller footprint compared to the footprint of an audio driver with a surround. Alternatively or additionally, for an audio driver of a similar footprint, the audio driver 10 can emit sound waves at a lower frequency than an audio driver with a surround due to the presence of the surround and, necessarily, the smaller diaphragm.

[0051] In some embodiments, the diaphragm 24 has a central portion provided in the form of a spherical cap 44 positioned concentrically with the displacement axis 26. In this manner, a peripheral portion 40 extends around the spherical cap 44. In some embodiments, the spherical cap 44 and the peripheral portion 40 may be molded or otherwise provided as a monolithic unit. However, in some other embodiments, the spherical cap 44 and the peripheral portion 40 may be separate parts that are permanently or removably attached to each other. As shown in this embodiment, the diaphragm 24 has a curved portion 46 extending between the spherical cap 44 and the peripheral portion 40. While the curved portion 46 is shown within the body 34 of the voice coil 22, in some other embodiments, the curved portion 46 defining the spherical cap 44 from the peripheral portion 40 may be positioned radially outside of or connected to the voice coil 22. As shown, the spherical cap 44 has a concave surface 44a opposite a convex surface 44b. In the example shown here, the convex surface 44b faces the listener L, away from the static structure 12. However, in some other embodiments, the spherical cap 44 may be upside down, with the concave surface 44 a facing the listener L, away from the static structure 12 .

[0052] In some embodiments, the peripheral portion 40 of the diaphragm 24 may be provided in the form of a frustoconical shape 50 that is annularly disposed about the displacement axis 26 and surrounds the spherical cap 44. The frustoconical shape 50 is inclined with respect to the displacement axis 26. The frustoconical shape 50 may be gradually narrowed in both directions of the displacement axis 26. For example, as in Figure 2B , the frustoconical shape 50 tapers toward the static structure 12 and thereby assumes an inverted frustoconical shape. Depending on the embodiment, the spherical cap 44 can have a surface area that is greater than, equal to, or less than the surface area of ​​the frustoconical shape 50 of the peripheral portion 40. However, it has been found preferable to oversize the spherical cap 44 relative to the frustoconical shape 50, such as shown in the illustrated embodiment. In other words, the spherical cap 44 can have a surface area that is greater than the surface area of ​​the frustoconical shape 50. The surface area of ​​the spherical cap can be greater than 45%, preferably 55%, and most preferably 60% of the surface area of ​​the frustoconical shape 50. In these embodiments, the larger surface area of ​​the spherical cap 44 can provide enhanced structure and rigidity to the overall diaphragm 24, which can conveniently help maintain frictionless motion between the peripheral edge 42 and the wall portion 32. Thus, the smaller portion of the frustoconical shape 50 that extends outside of the voice coil 22 is shaped so that there is no mode activity in the operating bandwidth of the audio driver 10 and no surrounding parts interfere with the balance of the diaphragm. Therefore, conical shaking and left-right non-axial movement of the diaphragm 24 can be eliminated.

[0053] Now refer to Figure 3, the audio driver 10 is shown as having a gap C extending between the peripheral edge 42 and the wall portion 32. In some embodiments, the gap C is less than 500 μm, preferably less than 400 μm, and most preferably less than 250 μm. In some embodiments, the gap C is configured to prevent air flow from circulating between the peripheral edge 42 and the wall portion 32. Considering that in this embodiment the wall portion 32 is cylindrical and the diaphragm 24 is circular, the gap C extends annularly around the displacement axis. Therefore, the annular gap C can prevent out-of-phase sound waves, which should be reflected within the audio driver 10, from interfering with in-phase sound waves. In addition, the annular gap C can also attenuate artifact patterns and interferences that may appear at the free peripheral portion edge 42 of the diaphragm 24 adjacent to the wall portion 32. Such artifact patterns and interferences formed at the annular gap C can be less significant than those that would form at the periphery of existing audio drivers. The diaphragm 24 is made of a hard material. For example, the diaphragm 24 can be made of a composite material, titanium, graphite, a hard plastic such as polyetheretherketone (PEEK), or a combination thereof. In these embodiments, the stiffness of the diaphragm 24 can prevent it from rocking from side to side during actuation of the audio driver 10. In addition, the lightness and stiffness of the diaphragm material can facilitate a first-order pistonic response over a substantial portion of the audio driver's bandwidth. However, in some embodiments, higher-order modal behavior in the upper portion of the audio driver's bandwidth can be acceptable due to structural and material limitations. Many high-strength, high-stiffness materials can be used to produce a lightweight, rigid diaphragm 24 and frame 20.

[0054] In some embodiments, the peripheral edge 42 and the wall portion 32 have circular geometries that are concentric with each other relative to the displacement axis. In this way, air circulation that may occur across the annular gap C may be constant all the way around the displacement axis, which may further hinder pattern artifacts and interference that would otherwise occur at the annular gap C.

[0055] In some embodiments, the audio driver 10 has an annular resonant cavity 51 circumscribed by the wall portion 32 , the suspension 16 , the body 34 , and the peripheral portion 40 . The cavity 51 is exposed and open at an annular gap C extending between the peripheral edge 42 and the wall portion 32 . In these embodiments, the annular resonant cavity 51 has a Helmholtz frequency that can be tuned to a frequency away from the passband of the audio driver 10 through appropriate selection of parameters such as the size and geometry of the cavity 51 . For example, in some embodiments, the Helmholtz frequency can be tuned above the passband of the audio driver 10 , while in other embodiments, the Helmholtz frequency can be tuned below the passband of the audio driver 10 . Consequently, out-of-phase sound waves generated by the diaphragm and propagating within the annular resonant cavity 51 may not excite a Helmholtz resonant mode of the annular resonant cavity 51 . This can be preferable because, in some embodiments where the Helmholtz frequency is within the audio frequency of the audio driver, energy from the sound waves can excite a Helmholtz resonance, which can adversely affect the performance of the audio driver 10 . In some embodiments, the annular resonator 51 is configured to discard or absorb out-of-phase sound waves by absorption. In some other embodiments, out-of-phase sound waves generated within the annular resonator 51 by the diaphragm 24 can be reflected and phase-shifted to beneficially interfere with the in-phase sound waves for reinforcement toward the listener L.

[0056] As shown in this embodiment, the wall portion 32 is preferably cylindrical about the displacement axis, however, the wall portion 32 does not need to be perfectly cylindrical. Such a cylindrical shape of the wall portion 32 helps maintain the air flow circulating across the annular gap C constant regardless of the position of the diaphragm 24 during the cyclic reciprocating motion. In other words, the air flow circulating across the annular gap C is relatively similar when the diaphragm 24 is in both its maximum axial position, i.e., the position closest to the static structure 12, and its position farthest from the static structure 12.

[0057] In some embodiments, the frame 20 has a collar portion 52 that extends between the wall portion 32 and the static edge 16a of the suspension 16. Preferably, the peripheral portion 40 of the diaphragm 24 clears the collar portion 52 during its axial reciprocating motion. In these embodiments, the shape of the collar portion 52 is defined by matching or otherwise corresponding to the shape of the peripheral portion 40 of the diaphragm 24. For example, in the illustrated embodiment, the collar portion 52 has an oblique shape 52' that extends obliquely relative to the wall portion 32. This oblique shape 52' is sized and shaped to maintain the frustoconical shape 50 free of the peripheral portion 40 during the reciprocating motion of the diaphragm 24.

[0058] As shown in this example, the suspension 16 can be provided in the form of a spider 56. Thus, the suspension 16 can provide structural support for the mass of the dynamic structure 14, rigid lateral alignment of the voice coil 22 within the magnetic gap 30, and sufficient axial movement of the diaphragm 24. Depending on the embodiment, the suspension 16 can extend radially and / or axially. In addition, the suspension 16 can extend inwardly from the coil body toward the pole pieces of the magnet assembly and, alternatively, extend outwardly from the coil body toward the frame. In this embodiment, the suspension 16 has a static edge 16a that is connected to the inner face of the frame 20. However, in some other embodiments, the static edge 16a of the suspension 16 can be connected to the inner face of the magnet assembly 18. In addition, the suspension 16 has a dynamic edge 16b that is connected to the body 34 of the voice coil 22. As shown, the dynamic edge 16b of the suspension 16 is connected to the first end 34a of the body 34. It should be understood that the dynamic edge 16b of the suspension 16 does not have to be connected to the edge portion 34c of the body 34, but can be anywhere adjacent to the first end 34a of the body 34, such as at Figure 3 As shown in .

[0059] Figure 4 An enlarged view of another example of a transducer 10' is shown. As shown, the suspension 16 connects the outer face of the coil body 34 to the frame 20, thereby defining a travel span x of the peripheral edge 42. 最大 More precisely, the moving span x 最大 is defined axially parallel to the displacement axis 26 and at x 正 Position and x 负 In this example, the displacement axis 26 is referred to as the x-axis, and the span of movement of the peripheral edge 42 of the diaphragm 24 is labeled x. 最大 . Moving span x 最大 is defined as the distance from the rest position x 零 The maximum positive movement position x 正 With the maximum negative movement position x 负 The difference between x 最大 =x 正 -x 负 Thus, the wall portion 32 covers the travel span x of the peripheral edge 42 during its piston reciprocating axial movement. 最大 As shown, it should be understood that the frame 20 can extend axially beyond the wall portion 32. For example, and as illustrated, the frame 20 can have an extending wall portion 49 that is higher and / or lower than the wall portion 32. The extending wall portion 49 can share the same shape as the wall portion 32. However, the extending wall portion 49 may not cover the travel span x of the diaphragm 24. 最大In some other embodiments, the overhanging wall portion 49 may have a shape different from that of the wall portion 32. As shown in this embodiment, the frame 20 has a collar portion 52 having an oblique shape 52' extending obliquely relative to the wall portion 32. As shown, the oblique shape 52' is oblique relative to the moving span x 最大 offset and well below the maximum negative displacement position x 负 In some embodiments, transducer 10' is equipped with an air seal 64 that connects peripheral portion 40 to angled shape 52' of frame 20. As shown, the air seal can be connected to peripheral edge 42 of the diaphragm. For example, air seal 68 can be made of a resilient foam to prevent contaminants from reaching magnetic gap 30.

[0060] In some embodiments, an audio driver array is provided. In these embodiments, the audio driver array includes several audio drivers that are mounted directly or indirectly to each other. In some embodiments, each of the audio drivers can correspond to the audio driver 10 described above. Depending on the embodiment, the audio drivers of the audio driver array can vary in size and shape. It is intended that in some embodiments the audio drivers can be mounted directly to each other. In these embodiments, their outer frames can have matching features that allow the audio drivers to be mounted directly to each other. For example, the audio drivers can be mounted directly to each other to form audio driver arrays that form rows and / or columns of audio drivers. Alternatively or additionally, the audio drivers can be mounted to each other indirectly via an array frame. In these embodiments, the array frame has spaced-apart transducer holes in which the audio drivers can be mounted. Depending on the embodiment, the array frame can be an open frame or a closed enclosure. Such arrays are often referred to as column speakers and their historical focus has been in the field of speech reproduction. As these arrays become more advanced, they can be used for music as well as speech. Mounting the audio drivers in a closed enclosure is useful for creating low frequencies to support the "speech range" performance of the audio driver array in the mid-range. For example, having holes in the magnet assembly can also help the diaphragm excite the vibration modes of the enclosure.

[0061] In some other embodiments, the frame array may be provided in the form of a closed housing, e.g. Figure 5. This figure shows an example of an audio driver array 100 according to an embodiment. As shown, the audio driver array 100 has a housing 102 having a front wall 104 and a cavity 106 inside the housing 102. The front wall 104 has a number of spaced apart transducer holes 108 that expose the cavity 106. In this example, a plurality of audio drivers 10 similar to the audio driver 10 are mounted to corresponding ones of the transducer holes 108. Although the transducer holes 108 are positioned vertically in this example to provide a column speaker arrangement, the transducer holes 108 can also be positioned in any other suitable manner around the housing 102. In this embodiment, the frames 20 of the audio drivers 10 are sized and shaped so as to be in close proximity to each other in the most space-efficient manner possible. In this way, having the audio drivers 10 closer together can increase coherence, through which sound waves propagate toward the listener. For example, the frame 20 has a thinner flanged portion 60 where the frame is in close proximity. Due to the thin annular gap extending between the wall portion of the frame and the free peripheral edge of the diaphragm, each audio driver can have a smaller footprint. In addition, the ratio of emitting surface to non-emitting surface can be increased in a manner that allows more audio drivers to be stacked per unit of housing surface area, and / or a smaller housing to be used for a similar number of emitting surfaces. For example, in the embodiment shown, the diaphragms 24 of the audio drivers 10 collectively form an emitting surface area (covering the four blacked-out areas A b ), the emitting surface area covers at least 65%, preferably at least 70%, and most preferably at least 75% of the surface area Aw of a given wall 104. If one were to calculate similar figures for a conventional audio driver with a surround, the emitting surface area of ​​the conventional audio driver may cover no more than about 60% of the surface area of ​​a given wall due to the non-emitting surface being occupied by the surround.

[0062] Figure 6A 、 6B and 6C show different examples of transducers 10' according to some other embodiments. As depicted, transducers 10' each have a static structure 12 having a magnetic gap 30 surrounding a displacement axis 26; and a wall portion 32 extending parallel to and facing displacement axis 26. Transducers 10' each have a dynamic structure 14 having a coil body 34 surrounding displacement axis 26, a coil 36 wound around coil body 34, coil body 34 being housed in magnetic gap 30; and a diaphragm 24 extending outward from displacement axis 26 and secured to coil body 34. In these embodiments, diaphragms 24', 24" and 24'" each have a peripheral edge 42 proximate to wall portion 32, the peripheral edge 42 not being attached to wall portion 32. As shown, transducers 10' each have a suspension 16 connecting static structure 12 to dynamic structure 14.

[0063] Now specifically refer to Figure 6A , the diaphragm 24' has a spherical cap 44 with a convex surface 44b facing the listener L and away from the static structure 12. In this embodiment, the peripheral portion 40 of the diaphragm 24 is also part of the spherical cap 44, because it extends both radially outwards from the body 34 and also obliquely towards the static structure 12 in such a way that the convexity is continuous up to the edge 42. The opposite is also possible, for example in Figure 6B In this embodiment, the diaphragm 24" has a spherical cap 44 with a concave surface 44a facing the listener L away from the static structure 12. In this embodiment, the peripheral portion 40 is also part of the spherical cap 44, as it extends both radially outward from the body 34 and also extends obliquely away from the static structure 12 in such a way that the concavity is continuous up to the edge 42. Figure 6C In some embodiments, the diaphragm 24'" is neither convex nor concave but rather flat, which may be convenient in at least some applications. In these embodiments, the frame 20 is sized and shaped to provide suitable placement of the wall portion 32. In other words, regardless of the axial position of the edge 42 relative to the static structure 12, the frame 20 is configured to bring the wall portion 32 closer to or further away from the static structure 12 to allow frictionless oscillation of the edge 42 proximate to the wall portion 32.

[0064] In some embodiments, the audio driver 10 is equipped with a speaker 70, for example Figure 7 . In these embodiments, the diaphragm 24 remains free of harmonics when operating under the additional pressure applied by the speaker 70. This is in contrast to conventional speaker-loaded audio drivers, where the surround can be damaged due to the additional pressure applied by the speaker. Thus, existing audio drivers placed in speaker-loaded applications can have increased deflection of the surround itself due to the increased pressure at the face of the diaphragm. This sound deflection introduces harmonics not found when existing audio drivers are operated in a direct emitter configuration, which can create sufficient pressure on the surround to cause it to rupture or other types of damage. At least some of these inconveniences can be overcome by using Figure 7 audio drivers to alleviate this.

[0065] Figure 8An example of a transducer 10' is shown according to another embodiment. In this example, transducer 10' includes a static structure 12 having a magnetic gap 30 surrounding a displacement axis 26; and a wall portion 32 extending parallel to and facing displacement axis 26. Transducer 10' includes a dynamic structure 14 having a coil body 34 surrounding displacement axis 26, a coil 36 wound around coil body 34, and coil body 34 housed in magnetic gap 30; and a diaphragm 24 extending outward from displacement axis 26 and secured to coil body 34. Diaphragm 24 includes an outer peripheral edge 42 proximate to wall portion 32, and is not attached to wall portion 32. In this particular embodiment, diaphragm 24 is shown without an outer peripheral portion protruding outward from coil body 34. In effect, outer peripheral edge 42 joins the coil body in a manner that allows for frictionless piston motion adjacent to outer peripheral edge 42 of wall portion 32. In this particular embodiment, outer peripheral edge 42 forms a corner portion with coil body 34. As can be appreciated, in this particular example, peripheral edge 42 is not free but instead is secured to a portion of coil body 34. Such a configuration has been found to be desirable for audio drivers operating in the high-frequency range, i.e., tweeter systems, in at least some applications. Transducer 10' also includes a suspension 16 connecting static structure 12 to dynamic structure 14. The suspension is not limited to a connection between the outer frame of transducer 10' and coil body 34 but can also be provided inwardly from coil body 34. As depicted, suspension 16 can connect coil body 34 to pole piece 62 of magnet assembly 18 of static structure 12. It should be understood that suspension 16 can be a first suspension component, and transducer 10' can include other suspension components, such as a second suspension component, as long as the suspension component does not connect wall portion 32 to peripheral edge 42. The first suspension component connects the inner surface of coil body 34 to pole piece 62 in a manner that extends radially outwardly between coil body 34 and static structure 12 relative to displacement axis 26. In some embodiments, the second suspension component can connect the frame 20 of the static structure 12 to the outer surface of the coil body 34 in such a manner that the second suspension component extends radially inward between the coil body 34 and the pole pieces of the static structure 12. Thus, depending on the embodiment, the suspension can extend radially or axially. Other suspensions or suspension types may be included in other embodiments.

[0066] As can be appreciated, the examples described and illustrated above are not intended to be merely exemplary. For example, while audio drivers may be used in audio applications such as those described above and other audio applications, the transducers described herein may also be used in non-audio applications or applications that generate longitudinal pressure waves having frequencies outside the sound frequency range. The diaphragm may be provided with a suitable shape, including but not limited to, conical, curved conical, spherical, dome-shaped, or a dome of revolution derived from any arc. Although cylindrical and annular shapes have circular cross-sections, it should be understood that the cylindrical and annular shapes described herein are intended to cover circular and elliptical cross-sections. The scope is indicated by the appended claims.

Claims

1. A transducer comprising: a static structure having a magnetic gap surrounding a displacement axis, and a wall portion extending parallel to and facing the displacement axis; a dynamic structure having a coil body surrounding the displacement axis; a coil wound around the coil body, the coil body being received in the magnetic gap; a diaphragm extending outwardly from the displacement axis and secured to the coil body, the diaphragm having a peripheral edge proximate the wall portion, the peripheral edge being unattached to the wall portion; as well as a suspension connecting the static structure to the dynamic structure, the suspension limiting the freedom of movement of the dynamic structure relative to the static structure to axial movement along the displacement axis, the suspension biasing the dynamic structure into a rest position, thereby defining a travel span x of the peripheral edge 最大 , the moving span x 最大 is parallel to the displacement axis and axially defined at x 正 Position and x 负 The wall portion covers the movement span x of the peripheral edge between the positions 最大 . 2 . The transducer according to claim 1 , wherein the diaphragm has a peripheral portion protruding from the coil body in a direction away from the displacement axis, the peripheral edge being a peripheral edge of a free end thereof.

3. The transducer of claim 2 , wherein the diaphragm has a spherical cap concentric with the displacement axis, the peripheral portion extends around the spherical cap, the spherical cap having a concave surface opposite to a convex surface, one of the convex surface and the concave surface facing away from the static structure. 4 . The transducer according to claim 3 , wherein the peripheral portion has a frustoconical shape around the displacement axis, the frustoconical shape being inclined obliquely with respect to the displacement axis. The transducer of claim 3 , wherein the peripheral portion is a portion of the spherical cap.

6. A transducer according to any one of claims 2 to 5, wherein the diaphragm has a central portion surrounded by the peripheral portion, the central portion having a first cross-sectional area defined relative to the displacement axis, the peripheral portion having a second cross-sectional area, the first cross-sectional area being larger than the second cross-sectional area.

7. A transducer according to any one of claims 1 to 6, wherein the wall portion is circumscribed to a first cross-sectional area defined relative to the displacement axis, and the extension of the diaphragm forms a second cross-sectional area, which covers at least 95%, preferably at least 97%, of the first cross-sectional area.

8. A transducer according to any one of claims 1 to 7, wherein the suspension comprises a first suspension member extending radially outwardly between the coil body and the static structure relative to the displacement axis.

9. A transducer according to any one of claims 1 to 8, wherein the wall portion is cylindrical and the peripheral edge is circular.

10. The transducer according to any one of claims 1 to 9, further comprising a gap formed radially between the peripheral edge and the wall portion, the gap being smaller than 500 μm.

11. The transducer according to claim 9, wherein the static structure has an annular resonant cavity opened at a gap formed radially between the outer peripheral edge and the wall portion, the annular resonant cavity having a Helmholtz frequency tuned to be higher than a passband of the transducer.

12. A transducer according to any one of claims 1 to 11, wherein the diaphragm is made of a composite material.

13. A transducer according to any one of claims 1 to 11, wherein the diaphragm is made of titanium.

14. A transducer according to any one of claims 1 to 11, wherein the diaphragm is made of plastic, preferably polyetheretherketone (PEEK).

15. The transducer of any one of claims 1 to 14, further comprising a horn carried on the transducer, the diaphragm remaining free of harmonics when operated under additional pressure applied by the horn.

16. An audio driver array comprising: A plurality of transducers mounted on each other, the plurality of transducers employing the transducer according to any one of claims 1 to 15.

17. The audio driver array of claim 16, further comprising an array frame having a plurality of transducer holes spaced apart from each other, the plurality of transducers being respectively mounted to corresponding ones of the plurality of transducer holes.

18. The audio driver array of claim 17, wherein the array frame is a housing having walls and a cavity within the housing, the walls containing the plurality of transducer apertures exposing the cavity.

19. An audio driver array according to claim 18, wherein the diaphragms of the plurality of transducers collectively form an emitting surface area that covers at least 65% of the surface area of ​​the wall, preferably at least 70% of the surface area of ​​the wall, and most preferably at least 75% of the surface area of ​​the wall.

20. A method for driving an audio driver, the method comprising: an audio signal in the form of an electric current circulating along a coil wound around a toroidal body carrying the diaphragm, thereby generating an electromagnetic field; as well as The electromagnetic field interacts with the magnetic field in the magnetic gap, thereby moving the diaphragm back and forth relative to the magnetic gap along a displacement axis, and the process of moving the diaphragm includes moving the outer peripheral edge of the diaphragm back and forth within a moving span, and the peripheral edge remains adjacent to the wall portion, surrounded by the wall portion, and not attached to the wall portion throughout the moving span.

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