Acoustic phase plug with non-circular outlet

Abstract

An acoustic phase plug for a compression driver having a dome diaphragm is provided, the phase plug being formed of two distinct subassemblies, a first subassembly defining an innermost passage and an outermost passage of annular shape, the innermost passage and the outermost passage have an acoustic inlet located at a predetermined modal position and an acoustic outlet arranged adjacent to each other and vertically displaced relative to the inlet, and have equal path lengths from the respective inlet to the outlet, the second subassembly has an annular-shaped acoustic inlet at a terminal end of the innermost passage and the outermost passage, where the second passage extends from the acoustic inlet to a non-circular acoustic outlet.

Description

[0001] Cross-citation of related applications

[0002] This application is a continuation of U.S. Patent Application Serial No. 19 / 034,144, filed January 22, 2025, which claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 709,099, filed October 18, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of acoustic engineering, with a particular focus on the design and development of phase plugs for high-frequency compression drivers. More specifically, this invention addresses the challenges associated with achieving accurate sound directionality and optimal audio output in loudspeaker arrays, while providing loudspeakers with reduced size and simple structure. Background Technology

[0004] In loudspeaker design, particularly for high-frequency applications, achieving precise sound directionality is a key objective. Commonly used methods involve vertically oriented loudspeaker arrays to ensure sound is guided in a controlled and focused manner, thereby enhancing the auditory experience in various environments such as concert halls, auditoriums, and outdoor venues. The ability to control sound directionality is crucial for delivering clear and consistent audio to the intended audience while minimizing sound diffusion into unwanted areas.

[0005] Figure 1 An exemplary array 10 is shown, consisting of a plurality of vertically aligned speakers 12 attached to each other on top to form an array. Figures 2A to 2B A front view and cross-sectional view of one of the loudspeakers 12 are shown. This loudspeaker 12 typically includes a low-frequency transducer 14 and a high-frequency transducer 16. The high-frequency transducer 16 is generally a compression driver provided with a circular acoustic outlet 18. Figure 3A A high-frequency compression driver 16 with a magnetic motor 20 is shown, which drives a concave diaphragm 22 in a compression chamber 23 to generate sound waves that propagate through a phase plug 24 to a circular outlet 18. Figure 3B A similar high-frequency compression driver 16 is shown, which has a convex diaphragm 22 and a circular acoustic outlet 18. However, these circular outlets 18 are naturally unsuitable for achieving the desired sound directivity in a loudspeaker array. The circular shape of the outlets in a vertical or horizontal array can lead to sound diffusion, which is less focused and more susceptible to interference, thus impairing the overall sound quality and directivity.

[0006] To resolve this design mismatch, additional components are typically introduced to convert the circular output of the high-frequency driver into a linear output. Figure 2AThe component shown as reference numeral 26 (often referred to as a waveguide or adapter) is designed to reshape the sound wave as it propagates through the circular acoustic outlet 18 of the compression driver 16, converting it from a circular to a linear form at the linear acoustic outlet 28. While this solution effectively facilitates the necessary directivity, it also presents its own set of challenges. The introduction of this additional component 26 increases the overall size and complexity of the loudspeaker system. This increase in size can be particularly disadvantageous in applications where space is limited or a compact design is desired, such as in portable sound systems or facilities with aesthetic constraints.

[0007] The added component 26 may introduce potential acoustic inefficiencies, such as reflections, diffraction, and undesirable modal behavior that may degrade sound quality. These inefficiencies result in less accurate sound reproduction, affecting the listener's experience. Specifically, the vibration of the curved circular diaphragm 22 (i.e., convex or concave) within the compression chamber 23 may excite acoustic modes within the compression chamber, thereby reducing the quality of the sound output. This problem is not addressed by component 26, but rather by the phase plug within the compression driver. Because component 26 is located behind the phase plug assembly, it cannot address acoustically undesirable effects within the compression chamber. The length of component 26 adversely amplifies the entire loudspeaker and / or causes undesirable acoustic losses, and attempts to address any acoustic problems of the compression driver via component 26 still frequently yield unsatisfactory results. Therefore, the compression chamber acoustic problems persist, and the output quality is not optimal.

[0008] Therefore, there is an urgent need for innovative solutions that can provide the desired linear acoustic output without the drawbacks of increased size and complexity, while also addressing undesirable modal behavior. Such a solution would ideally integrate the conversion from a circular to a linear output within the high-frequency driver itself, thus maintaining a compact design while ensuring optimal sonic directivity and quality. This need for innovation drives ongoing research and development in this field as designers seek to overcome the limitations of current systems and deliver superior audio performance in smaller speaker arrangements. Summary of the Invention

[0009] A phase plug assembly for an electric compression actuator is provided, the phase plug assembly including a first segment and a second segment. The first segment includes: a compression chamber formed by a convex or concave oscillating diaphragm and a boundary surface adjacent to the diaphragm of the phase plug assembly; a central axis of rotation defined within the interior of the phase plug assembly, the central axis of rotation extending from the boundary surface of the compression chamber to a terminal of the phase plug assembly; at least two passages, each passage extending about the central axis and traversing the first segment of the phase plug assembly from the boundary surface to the terminal of the first segment; the at least two passages include an innermost passage and an outermost passage disposed radially outside the innermost passage; wherein the terminal of the first segment of the phase plug is vertically displaced along the central axis relative to the boundary surface of the first segment of the phase plug. The cross-sectional area of ​​each passage in the pathway expands between the corresponding inlet and the end of the first segment at the boundary surface of the first segment of the phase plug assembly; the length of the outermost passage from the inlet at the boundary surface to the end of the first segment is equal to the corresponding length of the inner passage, wherein the length is defined by the path length along the centerline of the passage; at the end of the first segment of the phase plug, the passage is arranged in a plane perpendicular to the central axis and is vertically displaced relative to the compression chamber; and when viewed along the central axis, the shape of the passage defined at the end of the first segment of the phase plug assembly forms a circular ring, an elliptical ring, or an oblong ring.

[0010] The second section of the phase plug assembly includes: an acoustic inlet disposed at the end of the first section of the phase plug; an acoustic outlet vertically displaced relative to the acoustic inlet along a central axis and having a rectangular, rounded rectangular, oblong, or elliptical outlet shape; at least one second section passage extending from the acoustic inlet through the interior of the second section of the phase plug assembly to the acoustic outlet; wherein the acoustic outlet is shaped to radiate acoustic energy from the phase plug assembly into free space, a horn, a waveguide, or other acoustic impedance matching device; wherein the total surface area of ​​the second section passage expands between the acoustic inlet and the acoustic outlet; wherein the propagation delay through the second section of the phase plug is determined along the length of the second section passage to control the acoustic phase of the wavefront radiated from the acoustic outlet. Attached Figure Description

[0011] To gain a more complete understanding of this disclosure, the following brief description will now be given in conjunction with the accompanying drawings and specific embodiments, wherein the same reference numerals denote the same parts, in which: Figure 1 An exemplary array of vertically shifted speakers is shown; Figures 2A to 2B It shows Figure 1 Cross-sectional view and front view of the loudspeaker array; Figures 3A to 3B An example of an acoustic compression driver is shown; Figure 4 This is a perspective view of a speaker assembly in an exemplary embodiment; Figure 5 yes Figure 4 A cross-sectional view of the component taken along axis 2-2; Figure 6 yes Figure 5 A magnified partial view of the cross-section; Figure 7 yes Figure 4 A cross-sectional view of the component taken along axis 1-1; Figures 8 to 9 It shows Figure 4 An exploded view of the speaker assembly; Figures 10 to 12 Various views of a phase plug assembly in an exemplary embodiment are shown; Figures 13 to 14 An exploded view of the phase plug assembly is shown; Figures 15 to 17 These are various views of the outer annular part of the first section of the phase plug assembly; Figures 18 to 19 These are various views of the inner annular part of the first section of the phase plug assembly; Figures 20 to 21 Views of the second section of the phase plug assembly are shown; Figures 22 to 23 This is a view of the housing of the second section of the phase plug assembly; Figures 24 to 26 Various views of the inner wedge element of the second section of the phase plug assembly are provided; Figures 27 to 29 The parametric content related to the dimensions of the inner wedge element in the second section of the phase plug assembly is shown; Figures 30 to 31 Another exemplary embodiment of the second section of the phase plug assembly is shown, having an elongated acoustic outlet and an elliptical acoustic outlet. Figures 32 to 34 A compression driver with a phase plug assembly is shown in another embodiment of the invention, the phase plug assembly having an inner wedge element including a “bent” structure; Figures 35 to 36 A compression driver with a phase plug assembly is shown, the phase plug assembly having a non-bending multi-cavity inner wedge element; Figures 37 to 42 Various views of the inner wedge element of the multi-cavity phase plug assembly are shown; Figures 43 to 45 Various views of a loudspeaker assembly with a phase plug are shown, the phase plug having an inner wedge-shaped element with multiple cavities; Figures 46 to 47Various views of a loudspeaker assembly with a phase plug having a non-multi-cavity inner wedge element are shown; Figures 48 to 51 An alternative implementation of an asymmetric multi-cavity internal wedge element is shown; and Figures 52 to 53 An alternative embodiment of an internal wedge-shaped element with asymmetrical blades and a multi-cavity structure is shown. Detailed Implementation

[0012] Figure 4 A loudspeaker assembly 30 is shown, which includes a dome-shaped electromagnetic compression driver 32 and a phase plug assembly 34 that provides a non-circular acoustic outlet without requiring adapters or additional components as seen in the prior art (see [link]). Figure 2A (element 26 in the middle), and the phase plug assembly addresses undesirable compression chamber modal behavior to provide enhanced acoustic performance.

[0013] refer to Figures 5 to 7 The cross-sectional view shows that the loudspeaker assembly 30 includes a housing 36 that houses a magnetic motor assembly 38 operable to drive a voice coil 40 connected to a dome diaphragm 42. In the illustrated example, when viewed along the central axis of rotation CC of the loudspeaker assembly 30, the dome diaphragm 42 is a convex diaphragm having a generally circular shape. The diaphragm 42 is clamped to the housing 36 at its periphery by an element 44. When the voice coil 40 is driven by the motor 38, the diaphragm 42 vibrates within a compression chamber 46 defined between the diaphragm 42 and the phase plug 34.

[0014] The phase plug 34 is formed by a first segment 48 and a second segment 50, each of which is a separate sub-assembly attached together to form the phase plug 34. The first segment 48 of the phase plug 34 includes a boundary surface 52 positioned adjacent to the diaphragm 42 when the phase plug 34 is mounted on the compression driver 32. A compression chamber 46 is formed on one side by the diaphragm 42 and on the other side by the boundary surface 52 of the first segment 48 of the phase plug 34. A central axis of rotation CC extends from the boundary surface 52 of the first segment 48 of the phase plug assembly 34 to a terminal 54. The terminal 54 is located on the side of the first segment 48 opposite to the boundary surface 52.

[0015] At least two pathways extend through the first segment 48 of the phase plug 34. The example shown includes an innermost pathway 56 and an outermost pathway 58, each extending about the central axis CC and passing from the boundary surface 52 of the first segment 48 through the first segment 48 of the phase plug assembly 34 to the terminal 54. The innermost pathway 56 and the outermost pathway 58 extend circumferentially about the central axis of rotation CC, with the outermost pathway 58 positioned radially outside the innermost pathway 56.

[0016] The terminal 54 of the first segment 48 of the phase plug 34 is vertically displaced by a predetermined distance relative to the boundary surface 52 along the central axis CC. The innermost passage 56 and the outermost passage 58 extend through the first segment 48 of the phase plug 34 in approximately this vertical direction.

[0017] The cross-sectional area of ​​each of the passages 56 and 58 increases between the corresponding inlet at the boundary surface 52 of the first segment 48 of the phase plug assembly 34 and the terminal 54 of the first segment 34. Specifically, the innermost passage 56 includes an inlet 56' located at the compression chamber 46 and an outlet 56'' located at the terminal 54 of the first segment 48 of the phase plug assembly 34. The cross-sectional area of ​​the innermost passage 56 at the inlet 56' is smaller than the cross-sectional area of ​​the innermost passage 56 at the outlet 56''. In a non-limiting example, the cross-sectional area of ​​the innermost passage at the inlet 56' may be approximately 122 mm². 2 The cross-sectional area at the 56'' outlet can be approximately 143 mm². 2 .

[0018] Similarly, the outermost passage 58 includes an inlet 58' located at the compression chamber 46 and an outlet 58'' located at the terminal 54 of the first section 48 of the phase plug assembly 34. The cross-sectional area of ​​the outermost passage 58 at the inlet 58' is smaller than the cross-sectional area of ​​the outermost passage 58 at the outlet 58''. In another non-limiting example, the cross-sectional area of ​​the outermost passage 58 at the inlet 58' may be approximately 258 mm². 2 The cross-sectional area at the 58'' outlet can be approximately 304 mm². 2 .

[0019] When viewed along the central axis of rotation CC, the innermost passage 56 and the outermost passage 58 can be formed into annular, elliptical, or oblong annular shapes at the outlets 56'' and 58''. When viewed along the central axis CC, the innermost passage 56 and the outermost passage 58 can be formed in a shape corresponding to or different from the outlet shape at the inlet 56' and 58'.

[0020] The lengths of the innermost passage 56 and the outermost passage 58 are preferably approximately equal. That is, the length of the outermost passage 58 from its inlet 58' at the boundary surface 52 to its outlet 58'' at the end 54 of the first segment 48 of the phase plug 34 is approximately the same as the corresponding length of the innermost passage 56 from its inlet 56' to its outlet 56''. In one example, this equal length is approximately 9.5 mm. The lengths of the innermost passage 56 and the outermost passage 58 are defined as the path length along the centerline of the respective passage.

[0021] The oscillation of the dome diaphragm 42 within the compression chamber 46 excites at least one acoustic mode within the chamber (e.g., at positions 60 and 62). In most embodiments, the inlet 56' of the innermost passage 56 is aligned with and positioned at the acoustic mode node 60 of the chamber. Similarly, the inlet 58' of the outermost passage 58 is aligned with and positioned at the acoustic mode node 62 of the chamber. This arrangement of the inlets 56' and 58' of passages 56 and 58 reduces modal activation within the compression chamber. The two passage positions correspond to the fact that the second-order acoustic modes of the compression chamber have two physical node positions.

[0022] In contrast, if the diameter of the compression chamber is large, the oscillation of the dome diaphragm 42 can generate more than two compression chamber acoustic modal node positions. In this case, the first segment 48 of the phase plug 34 can be modified to include an additional path that is aligned with the additional compression chamber modal node in the same manner as the inner and outer paths described above.

[0023] Finally, in the specific case where the compression chamber size is very small, the second-order compression chamber mode will be outside the frequency band of interest, and at least two paths are strategically balanced to deactivate the first-order chamber mode which has a single node in a single physical location.

[0024] The outlets 56'' of the innermost passage 56 and 58'' of the outermost passage 58 are aligned in a virtual plane VV extending perpendicular to the central axis CC. At the virtual plane VV, the cross-section of the phase plug 34 gradually transitions from the described axisymmetric dual passages 56, 58 to a rectangular single-slot outlet passage, as further described below. From the compression chamber 46 to the virtual plane VV (which coincides or nearly coincides with the terminal 54 of the first segment of the phase plug 48), the path lengths and expansion rates of the innermost passage 56 and the outermost passage 58 must be similar.

[0025] The second segment 50 of the phase plug assembly 34 includes an acoustic inlet 64 disposed on the side of the second segment 50 adjacent to the terminal 54 of the first segment 48 of the phase plug 34. As shown, the acoustic inlet 64 is aligned with the virtual plane VV. Correspondingly, the second segment 50 includes an acoustic outlet 66 disposed opposite to the acoustic inlet 64, vertically displaced relative to the acoustic inlet 64 along the central axis CC. The acoustic outlet 66 defines a rectangular, rounded rectangular, oblong, or elliptical outlet shape and is configured to radiate acoustic energy from the loudspeaker assembly 30 into free space, a horn, a waveguide, or other acoustic impedance matching device. See also Figure 11 , Figure 30 , Figure 31 wait.

[0026] The second segment 50 of the phase plug assembly 34 also includes a second segment passage 68 that extends from the acoustic inlet 64 through the interior of the second segment 50 to the acoustic outlet 66. The second segment passage 68 includes an expanded surface area between the acoustic inlet 64 and the acoustic outlet 66. The acoustic inlet 64 of the second segment 50 is sized, shaped, and aligned to correspond to the outlets 56'' and 58'' of the innermost passage 56 and the outermost passage 58. That is, at the virtual plane VV, the innermost passage 56 and the outermost passage 58 merge together and engage with the second segment passage 68. Sound waves reaching the virtual plane VV through the innermost passage 56 and the outermost passage 58 propagate through the second segment passage 68 to the non-circular acoustic outlet 66. The length of the second segment passage 68 is designed to determine the propagation delay through the second segment 50 of the phase plug 34 to control the acoustic phase of the wavefront radiated from the acoustic outlet. The length of the second segment passage, measured along its centerline, can be approximately 26.5 mm.

[0027] The first segment 48 of the phase plug 34 includes a first mechanical subassembly that defines an innermost passage 56 and an outermost passage 58 of the first segment 48, and is mechanically discontinuous and separable from the second segment 50 of the phase plug assembly 34. For example, refer to... Figures 13 to 17 The first segment 48 of the phase plug 34 may include an outer annular part 70 having a first side 72 disposed adjacent to the diaphragm 42 and an opposing second side 74 disposed near the second segment 50 of the phase plug 34. The outer annular part 70 includes a mating groove 76 located on the second side 74 to facilitate attachment to the second segment 50 of the phase plug assembly. The first side 72 of the annular part 70 is configured to receive an inner annular part 78, thereby forming the first segment 48 of the phase plug 34.

[0028] Now for specific reference Figure 13 as well as Figures 18 to 19 The inner annular part 78 includes an annular portion 80 and a circular portion 82, each portion having a plurality of mounting feet 84. The annular portion 80 extends around the outer circumference of the circular portion 82 located at the top of the annular portion 80, and the mounting feet 84 extend from the circular portion 82 to the annular portion 80 to mount the circular portion onto the annular portion. These mounting feet 84 define a gap G1 between the annular portion 80 and the circular portion 82, which forms part of the innermost passage 56. The mounting feet 84 on the annular portion 80 are received within mounting orifices 86 formed in the first side 72 of the outer annular part 70. With the mounting feet 84 of the annular portion 80 positioned within the mounting orifices 86 of the outer annular part 70, a gap G2 is defined, which forms part of the outermost passage 58. (See specifically...) Figure 6 ).

[0029] The second segment 50 of the phase plug assembly 34 includes a second mechanical sub-assembly that defines an acoustic inlet 64 and an acoustic outlet 66 of the second segment 50, and is mechanically discontinuous and separable from the first segment 48 of the phase plug assembly 34. For example, as Figures 20 to 21 As shown, the second segment 50 includes a housing 88 and an inner wedge element 90. On one side, at the acoustic inlet 64, the housing 88 includes a circular flange 92 configured to be received within a mating groove 76 of the outer annular part 70 of the first segment 48 of the phase plug 34. On the other side, the housing 88 includes a non-circular acoustic outlet 66. In the example shown, the housing 88 includes a flat surface 94 with a non-circular cutout 96 defining the acoustic outlet 66. The housing 88 may be a single integral part, or as... Figures 22 to 23 As shown, the housing may be composed of two identical halves attached together to form a housing 88. In one embodiment, each half includes a mounting lug 98 and a mounting recess 100. When the two halves are joined together, the mounting lug 98 is received and held within the opposing mounting recess 100 to form the housing 88. Each half of the housing 88 may also include a prong 110 for facilitating engagement with an inner wedge element 90.

[0030] The inner wedge element 90 includes a receiving end 102 on one side and a linear peak 104 on the other side. In the embodiment shown in the figures, the receiving end 102 of the inner wedge element is circular when viewed along the central axis CC. However, in other embodiments, the receiving end 102 may have a different shape, such as elliptical or oblong. The inner wedge element 90 also includes two opposing primary surfaces 106 and two opposing secondary surfaces 108, all of which extend from the circular receiving end 102 to the linear peak 104. The primary surfaces 106 extend along the linear peak 104, while the secondary surfaces 108 intersect the linear peak 104 in a generally perpendicular manner. The cross-sectional area of ​​all primary surfaces 106 and secondary surfaces 108 increases in a direction away from the circular receiving end 102 and towards the linear peak 104. The inner wedge element 90 also includes a receiving aperture 112 for receiving and retaining the toothed portion 110 of the housing to secure the wedge element 90 within the housing 88.

[0031] When the second section 50 of the phase plug 34 is assembled, the inner wedge element 90 is received within the housing 88 such that the linear peak 104 is positioned within a non-circular cutout 96 on the flat surface 94 of the housing 88 to define a non-circular acoustic outlet 66. See, for example... Figure 20 The circular flange 92 of the outer casing 88 and the circular receiving end 102 of the inner wedge element 90 are aligned in a planar arrangement to facilitate connection with the first segment 48 of the phase plug assembly 34. See, for example... Figure 21As described above, the circular flange 92 of the housing 88 is received within the mating groove 76 of the outer annular part 70 of the first section 48. Furthermore, the circular receiving end 102 of the inner wedge element 90 includes a mounting aperture 86 for receiving and retaining the mounting feet 84 of the circular portion 82 of the inner annular part 78 of the first section 48 of the phase plug 34. Figure 18 That is, as described above, when the inner annular part 78 is placed inside the outer annular part 70, the circular portion 82 and its support leg 84 extend into the opening at the center of the outer annular part 70, where the support leg 84 is received by the mounting hole 86 of the inner wedge element 90. In this way, the inner wedge element 90 is connected to the inner annular part 78, the housing 88 is arranged to receive the inner wedge element 90, and the circular flange 92 of the housing 88 is fixed in the mating groove 76 of the outer annular part 70, such that the first section 48 of the phase plug assembly 34 is fixed to the second section 50.

[0032] As described above, passage 68 extends from acoustic inlet 64 through the second section 50 of phase plug 34 to acoustic outlet 66. Figure 5 and Figure 7 The passage 68 is formed on one side by the inner surface of the housing 88 and on the other side by the outer surface of the inner wedge element 90. That is, the inner wedge element 90 is disposed within the housing 88 to define the second section passage 68. The inner wedge element 90 is essentially a shield disposed within the second section 50 of the phase plug 34, and the passage 68 is defined by the outer wall of the shield 90 and the inner wall of the second section 50.

[0033] As described above, the innermost passage 56 and the outermost passage 58 extend from the boundary surface 52 of the first segment 48 through the first segment 48 of the phase plug 34 to the terminal 54. The innermost passage 56 and the outermost passage 58 are formed by placing an inner annular part 78 within an outer annular part 70. Again, the inner annular part 78 is essentially a shielding element disposed within the annular part 70 to form the desired acoustic path. Specifically, refer to... Figures 16 to 18 The outer surface A of the ring portion 80 and the inner surface B of the ring part 70, together with the gap G2, define the outermost passage 58. The inner surface C of the ring portion 80, the outer surface D of the circular portion 82, and the gap G1 define the innermost passage 56.

[0034] In one embodiment, the cross-sectional area of ​​the passage 68 of the second segment 50 of the phase plug 34 at the acoustic inlet 64 is approximately 75% of the cross-sectional area of ​​the second segment passage 68 at the acoustic outlet 66.

[0035] The size and dimensions of the inner wedge element can be varied and determined based on specific needs or applications. (Reference) Figure 27To achieve a ultimately flat wavefront at acoustic outlet 66, one method for design parameterization to optimize the acoustic output involves relating the inner and outer radii of the wedge element to its length and width according to the following formula:

[0036] in

[0037] Furthermore, the angle α is chosen based on the desired outcome.

[0038] Figures 27 to 29 This represents the air volume surrounding the inner wedge element and depicts schematic wavefront details of the wedge, rather than the structure of the wedge itself. That is, Figures 27 to 29 This is a simulation diagram depicting the negative structure (inverted structure) of the wedge structure to illustrate its acoustic wavefront behavior. The exemplary wavefront shown is curved and consistent with the implementation of the curved inner wedge element 120 described below.

[0039] The phase plug 34 described herein may include a second mechanical subassembly that includes additional mechanical structures to further control the shape of the wavefront at the wavelength of interest. This additional mechanical structure is an obstruction that can be added within the assembly described herein to further control the acoustic waves in a second segment of the phase plug 34. Depending on the requirements of the specific end application, the desired wavefront shape (pressure distribution) at the acoustic outlet 66 may be planar or curved.

[0040] So far, the acoustic outlet 66 of the phase plug assembly 34 has been shown as rectangular. See, for example... Figures 10 to 11 Of course, this is merely an example. The acoustic outlet 66 can be any non-circular shape as desired for the specific needs of the speaker assembly 30.

[0041] For example, Figures 30 to 31 Another embodiment of the phase plug 34 is depicted, wherein the acoustic outlet 66 is oblong and elliptical, respectively. This can be easily achieved by reshaping the non-circular cutout 96 as desired to achieve the correspondingly shaped acoustic outlet 66. Within the broad scope of the invention, other non-circular shapes for the acoustic outlet 66 are conceivable. Figures 30 to 31The phase plug shown includes an internal septum, which is described in more detail below. This "multi-cellular" form of the phase plug can include an acoustic outlet of the shown oblong or elliptical shape, or an acoustic outlet of the shown rectangular shape. Similarly, the "non-multi-cellular" form of the phase plug without an internal septum discussed above can include an acoustic outlet of the shown rectangular shape, or... Figures 30 to 31 The shape shown is either oblong or elliptical.

[0042] As disclosed herein, the second segment 50 of the phase plug assembly 34 includes a housing 88 and an inner wedge element 90. See, for example... Figures 20 to 21 The inner wedge element 90 is described herein as comprising a circular receiving end 102 on one side and a linear peak 104 on the other side. See, for example... Figures 24 to 26 The primary surface 106 extends planarly from the circular receiving end 102 to the linear peak 104, while the secondary surface 108 extends in a curved manner from the circular receiving end 102 to the opposite ends of the linear peak 104. The result is a generally wedge-shaped or axe-shaped element with a peak 104 extending linearly across the upper boundary opposite the circular receiving end 102.

[0043] Of course, this is merely one exemplary implementation of the inner wedge element. The broad scope of the invention contemplates other implementations of this inner wedge element within the phase plug assembly 34.

[0044] For example, as described above, the shape of the receiver 102 can be non-circular. That is, as needed, the receiver 102 can be oval, oblong, elliptical, rounded square, etc., to help define the geometry of the virtual transition plane VV between the terminal 54 of the first segment of the phase plug and the path 68 of the second segment of the phase plug 34.

[0045] In another example, Figures 32 to 34 An alternative embodiment of a speaker assembly 30 is shown, which has a curved inner wedge element 120 including a circular receiving end 102 described previously relative to inner wedge element 90, and a primary surface 106 and a secondary surface 108. However, instead of the linear peak 104 of inner wedge element 90, the curved inner wedge element 120 includes a curved upper surface 122 that extends along the primary surface 106 from a secondary surface 108 to an opposing secondary surface 108.

[0046] The curved inner wedge element 120 may be a single piece, an integrally formed element. Alternatively, element 120 may include two or more separate elements that are mechanically attached together, or that may be adhered or fastened together.

[0047] Similar to the inner wedge element 90, a curved inner wedge element 120 is disposed in the second section 50 of the phase plug assembly 34. That is, when the second section 50 of the phase plug 34 is assembled, the curved inner wedge element 120 is received within the housing 88 such that the curved upper surface 122 is disposed within a non-circular cutout 96 on the flat surface 94 of the housing 88 to form a non-circular acoustic outlet 66. The circular flange 92 of the housing 88 and the circular receiving end 102 of the curved inner wedge element 120 are aligned in a planar arrangement to facilitate connection with the first section 48 of the phase plug assembly 34. See, for example... Figure 16 and Figure 21 As previously described, the circular flange 92 of the housing 88 is received within the mating groove 76 of the outer annular part 70 of the first segment 48. Furthermore, the circular receiving end 102 of the curved inner wedge element 120 may include a mounting aperture for receiving and retaining the mounting leg 84 of the circular portion 82 of the inner annular part 78 of the first segment 48 of the phase plug 34. That is, as described above, when the inner annular part 78 is positioned within the outer annular part 70, the circular portion 82 and its leg 84 extend into an opening at the center of the outer annular part 70, where the leg 84 is received by the mounting aperture 86 of the curved inner wedge element 120. In this way, the curved inner wedge element 120 is connected to the inner annular part 78, the housing 88 is arranged to receive the curved inner wedge element 120, and the circular flange 92 of the housing 88 is secured within the mating groove 76 of the outer annular part 70, such that the first segment 48 of the phase plug assembly 34 is secured to the second segment 50.

[0048] like Figures 32 to 34 As shown, the apex of the curved upper surface 122 of the curved inner wedge element 120 is aligned with and approximately tangent to the flat surface 94 of the outer housing 88 of the second segment 50 of the phase plug 34. In another arrangement, all or part of the curved surface 122 may protrude from a non-circular cutout 96 on the flat surface 94 of the housing 88. Alternatively, the housing may be truncated, such that all or part of the curved surface 122 and the arcuate body 124 may protrude from the housing to form a non-circular acoustic outlet 66.

[0049] The curved inner wedge element 120 is configured to achieve a curved wavefront at the output of the phase plug 34. This curved configuration produces high-frequency broadening, but may result in some loss of angular uniformity in mid-to-high frequency directional control. This mid-to-high frequency problem can be mitigated by using a multi-cavity curved element discussed below and / or by moderately reducing the horn angle to maintain consistent directivity throughout the spectrum.

[0050] In another embodiment, such as Figures 35 to 41As shown, the loudspeaker assembly 30 may include a multi-cavity curved inner wedge element 124. Here, the wedge element 124 has an axe shape similar to the inner wedge element 90 described above, having a circular receiving end 102, a linear peak 104, a primary planar surface 104, and a curved subsurface 106. However, compared to... Figure 10 Unlike the inner wedge element 90 (where the linear peak 104 is aligned with the non-circular cutout 96 at the flat surface 94 of the second segment 50 of the phase plug), the linear peak 104 of the inner wedge element 124 of the multi-cavity structure is embedded in the housing 88 and vertically offset from the flat surface 94 along the axis CC. The inner wedge element 124 of the multi-cavity structure is characterized by being defined by internal spacers, as discussed further below. The curved inner wedge element 124 of the multi-cavity structure provides enhanced mid-to-high frequency control. Specifically, the multi-cavity configuration described herein is designed to control the rate of expansion of sound waves in the passage 68 of the second segment 50 of the phase plug 34. For certain problematic frequencies (where, for example, diffraction effects affect the uniformity of sound diffusion), the multi-cavity structure guides the wavefront in the correct manner.

[0051] In this context, a multi-cavity generally refers to an additional structural element within the second section 50 of the phase plug 34. In one embodiment, a plurality of blades 126 are disposed between the main surface 106 of the inner wedge element 124 of the multi-cavity and the inner wall of the housing 88.

[0052] For example, Figures 35 to 38 The housing 88 (see front reference) is shown. Figures 20 to 23 (Detailed discussion) An embodiment of the curved multi-cavity inner wedge element 124 is described. This embodiment of the curved multi-cavity inner wedge element 124 includes blades 126 that traverse the main surface 106 of the wedge 124 and extend from the linear peak 104 generally in the direction of the axis CC. In the illustrated embodiment, the blades 126 include two central blades 126' and two outer blades 126''. The two inner blades 126' are equidistant from the axis CC. Similarly, the two outer blades 126'' are equidistant from the axis CC. The distance between the outer blades 126'' and the axis CC is greater than the distance between the inner blades 126' and the axis CC. All blades 126 are angled away from the axis CC. For example, as... Figure 39 As schematically shown, the inner blade 126' is positioned at approximately 1 / 3 of the horn angle β, while the outer blade 126'' is positioned at approximately 2 / 3 of the horn angle β.

[0053] The blade 126 extends between the main surface 106 of the inner wedge element 124 of the multi-cavity housing and the inner wall of the housing 88, effectively dividing the second segment passage 68 within the phase plug 34 into a plurality of channels 128. In the illustrated embodiment, the inner blade 126' and the outer blade 126'' form five channels 128. The blade 126 may be integrally formed with the inner wedge element 124 of the multi-cavity housing and extend from the inner wedge element of the multi-cavity housing to engagely contact the inner surface of the housing 88, thereby forming the channels 128. Alternatively, the blade 126 may be an integral part of the housing 88 and extend from the inner wall to engagely contact the main surface 106 of the inner wedge element 124 of the multi-cavity housing, thereby forming the channels 128. Further alternatively, some blades 126 may be integrally formed with the housing 88, while other blades are integrally formed with the inner wedge element 124 of the multi-cavity housing. In another alternative, the blade can be configured as a separate part from the inner wedge element 124 of the multi-cavity housing and the outer housing 88, and can be inserted between them by friction fit or fixed with adhesive or fastener, thereby forming the channel 128.

[0054] As in Figures 37 to 38 As can be seen, the inner blade 126' extends further than the outer blade 126'' in the direction of the axis CC. That is, the inner blade 126' extends to the flat surface 94 of the housing 88, or at least close to it. The outer blade 126'' does not extend to the surface 94, but terminates at approximately the midpoint between the linear peak 104 of the inner wedge element 124 of the multi-cavity housing and the surface 94. This has the effect of creating an effective curved exit 130 for the channel 128, which mimics... Figure 34 The curved upper surface 122 of the curved inner wedge element 120. The curved upper surface 122 and the effective curved outlet 130 together enable the corresponding phase plug 34 to propagate the curved acoustic wavefront.

[0055] Figures 40 to 41 An embodiment of the multi-cavity inner wedge element 124 is shown, wherein each blade 126 includes a first portion 132 extending from a circular receiving end 102 and a second portion 134 extending from the first portion 132 toward a linear peak of the multi-cavity inner wedge element 124. The first portion 132 extends at least partially across the subsurface 108 of the multi-cavity inner wedge element 124, and the second portion 134 extends on the main surface 106. (As shown in...) Figure 41 As can be seen, the blades 126 are spaced about 30° apart around the axis CC.

[0056] The description of the multi-cavity inner wedge element 124 provided so far is merely exemplary. The invention contemplates variations and arrangements of the parameters forming the wedge element 124. The number of blades 126, the specific arrangement of the blades within the housing 88, the extension length of the linear peak 104 of the blades relative to the inner wedge element 124, and the angles of the blades relative to the axis CC and relative to each other are described herein by way of example only and can be varied and modified as desired for specific applications.

[0057] As mentioned above, Figures 30 to 31 A phase plug 34 with an acoustic outlet 66 of optional shape is shown. It should be noted that these embodiments of the phase plug 34 also include blades 126 that divide the second segment passage into a plurality of channels 128. However, the phase plug according to this disclosure can include any combination of various internal wedge geometries (with or without blades) with various acoustic outlet shapes, as desired for a particular application.

[0058] Figure 42 An alternative embodiment of the multi-cavity inner wedge element 124 is shown, which has a linear peak 104 and a plurality of blades 126 extending parallel to the axis CC, wherein all blades extend to and terminate at the flat surface 94 of the housing 88. As a result, the channel 128, which is substantially aligned with the axis CC, thus presents a planar waveform at the acoustic outlet of the phase plug 34. Figures 43 to 45 A view of a phase plug 34 is shown, which has a multi-cavity inner wedge element 124 attached to a horn 136 to form a loudspeaker assembly 30. The horn 136 is shaped and configured to direct sound propagating from an acoustic outlet 66 in a direction away from the loudspeaker assembly 30. The horn 136 may be an integral part of the housing 88 or a separate structure. Figure 43 The diagram shows a curved outlet 130 formed by inner blades 126' and outer blades 126'' of different lengths. Figure 44 A partially enlarged view of the housing 88 of the second section 50 of the multi-cavity inner wedge element 124 and phase plug 34 is shown. Figure 45 A view of the speaker 136 is provided, in which the acoustic outlet 66 of the phase plug 34, the multi-cavity inner wedge element 124, the blade 126, and the channel 128 can be seen.

[0059] Figures 46 to 47 An embodiment of a non-curved and non-multi-cavity loudspeaker assembly 30 is shown. That is, the assembly 30 shown includes a non-curved inner wedge element 90 without blades 126, which is disposed within the outer housing 88 attached to the speaker 136.

[0060] To date, various inner wedge elements 90, 120, 124 have been described and shown as symmetrically formed around the central axis CC of the phase plug 34. However, in other embodiments of the invention, the phase plug 34 may comprise an asymmetrical inner wedge element. For example, Figures 48 to 49 A curved, asymmetrical, multi-cavity inner wedge element 138 is shown. As described above, the inner wedge element has a curved upper surface 122 and a plurality of blades 126 including inner blades 126' and outer blades 126''. As shown, the blades 126 are arranged symmetrically about a central axis CC, but the volume forming the wedge 138 is asymmetrically distributed about the axis CC. Figures 50 to 51 An inner wedge element 140 with an asymmetric multi-cavity structure having a linear peak 104 described above relative to the inner wedge element 90 is shown. Here again, the blades 126 are symmetrically distributed around the central axis CC, but the wedge element 140 itself is asymmetrically shaped around the axis CC.

[0061] The blades 126 of the various multi-cavity inner wedge elements 124, 138, 140 have been described herein as symmetrically radiating around the central axis CC of the phase plug 34. However, in an alternative embodiment, one or more blades of 126, 126', 126'' may be arranged asymmetrically around the axis CC.

[0062] For example, Figures 52 to 53 An alternative embodiment of the multi-cavity inner wedge element 142 with a linear peak 104 is shown, wherein the blades 126 are arranged asymmetrically about a central axis of rotation CC. In these configurations, the angular spacing between adjacent blades can vary, wherein some blades 126 are positioned at an angle corresponding to a fraction of the horn opening angle β. For example, in Figure 52 In this configuration, the inner blade 126' can be positioned relative to the central axis CC at an angle ranging from β / 2 to β / 4, while the outer blade 126'' can be positioned at an angle ranging from β / 2 to 3 / 4β. Figure 53 In this implementation, the inner blade 126' can be positioned at an angle of β / 4, β / 3, or β / 2 relative to the central axis CC, while the outer blade 126'' is arranged at β / 2, β / 3, or 3 / 4β. These asymmetrical arrangements are advantageous for optimizing acoustic performance and controlling the directionality pattern in specific applications. Figures 52 to 53 As shown, the shape of the wedge element 142 is symmetrical about the non-curved linear peak 104. However, in other embodiments, the wedge element 142 may be asymmetrically shaped and may include the linear peak 104 of the curved upper surface 122 of the wedge in a curved form.

[0063] Figures 48 to 51The asymmetrical shapes of the inner wedges 138 and 140 and Figures 52 to 53 The asymmetrical arrangement of the blades 126 in the middle allows the diffusion angles above and below the centerline axis of the second section of the phase plug to be different. That is, the midpoint angle of the vertical diffusion will be pointing only horizontally, without having to physically mount the driver to the horn flare, where the mounting surface of the horn throat will compress the driver to be placed at an angle above or below the horizontal plane.

[0064] The phase plug assembly described herein provides a useful non-circular acoustic outlet in vertical or horizontal loudspeaker arrays without the need for an intermediate element or adapter 26 extending between the phase plug of the compression driver and the acoustic outlet, and also resolves and mitigates undesirable compression chamber modal behavior, thereby overcoming the problems of the prior art and ensuring optimal sound directivity and quality in a compact and simplified structure.

[0065] At least two paths are arranged in the first section of the phase plug assembly, wherein the cross-sectional area of ​​each path expands from the boundary surface to the terminal. This ensures that the at least two paths have equal path lengths and similar acoustic impedances when they intersect at the virtual plane VV, and minimizes modal behavior within the compression chamber. Modal activity is suppressed by aligning the entrance of the path with the node of the axial mode of the compression chamber, thereby improving sound quality. The use of a circular, elliptical, or oblong annular shape at the terminal provides flexibility to customize the acoustic output, control the directivity, and reduce unwanted fluctuations in the angular diffusion of sound waves for specific applications. This design eliminates the need for additional component 26, thereby reducing the overall size and complexity of the loudspeaker system while maintaining high acoustic performance. Further benefits can be seen in the reduction of distortion within the loudspeaker due to the reduced path distance from the compression chamber to the mouth of the phase plug attachment to the radiating waveguide or other impedance matching components.

[0066] The second section of the phase plug assembly has an acoustic inlet aligned with the end of the first section and an acoustic outlet shaped as a rectangle, rounded rectangle, oblong, or ellipse, which facilitates the transformation of the wavefront into the desired non-circular shape. This transformation allows for precise control of sound directivity, particularly in vertical or horizontal loudspeaker arrays. The enlarged surface area of ​​the second section path ensures efficient acoustic energy transfer while minimizing reflection and diffraction effects that could cause changes in directionality. The propagation delay introduced by the varying length of the shield along the second section path allows for fine-tuning of the acoustic phase, thereby ensuring that the wavefront radiated from the acoustic outlet is optimized for the intended application. This integrated design eliminates the need for external adapters, reduces acoustic inefficiencies, and maintains a compact loudspeaker configuration.

[0067] The phase plug assembly presented herein features a curved exit formed by inner and outer blades with varying diffusion angles and termination points, introducing a controlled curvature to the wavefront at the acoustic exit. The curved exit, created by the different lengths of the inner and outer blades, alters the propagation path of the sound waves, thereby generating a curved wavefront at the acoustic exit. When coupled to a specific loudspeaker, this curvature enhances the directivity of the sound waves, allowing for improved sound diffusion and coverage in applications such as vertical or horizontal loudspeaker arrays. The varying blade lengths create a gradual transition in the wavefront shape, reducing abrupt changes in acoustic impedance and minimizing reflection and diffraction losses within the phase plug, resulting in a more coherent and uniform sound output. The curved wavefront generated by the curved exit improves control over high-frequency sound propagation, enabling precise tuning of the sound output to match the requirements of specific applications, such as concert halls or outdoor venues, and this curved wavefront alleviates mid-frequency issues by optimizing the geometry of the shield and the exit configuration. This curved outlet configuration enables a compact design while maintaining high acoustic performance, eliminating the need for additional external components such as waveguides or adapters, and minimizing the overall size and complexity of the speaker system. This makes the design suitable for space-constrained applications while maintaining sound quality.

[0068] Various embodiments of the invention are described herein with reference to the accompanying drawings. Alternative embodiments may be designed without departing from the scope of the invention. It should be noted that various connections and positional relationships (e.g., above, below, adjacent, etc.) between elements are depicted in the specification and drawings. Unless otherwise stated, these connections and / or positional relationships may be direct or indirect, and the invention is not intended to be limiting in this respect. Thus, the connection of entities may refer to direct or indirect connections, and the positional relationship between entities may be direct or indirect positional relationship.

[0069] The term "exemplary" is used herein to mean "serving as an example, illustration, or description." Any implementation or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations or designs. The terms "at least one" and "one or more" should be understood to include any integer greater than or equal to 1, i.e., 1, 2, 3, 4, etc. The term "multiple" should be understood to include any integer greater than or equal to 2, i.e., 2, 3, 4, 5, etc. Terms such as "connected to" or "attached to" can include both indirect "connection" and direct "connection."

[0070] Various embodiments of the invention have been described for illustrative purposes, but are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and concept of the described embodiments. The terminology used herein has been chosen to best explain the principles of the embodiments, their practical application, or technical improvements to technologies found in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0071] Figure Labels

[0072] G1 gap

[0073] G2 gap

[0074] CC center plane

[0075] VV Virtual Plane

[0076] A. Surface of the outer ring part

[0077] B. Surface of the inner ring part

[0078] C. Surface of the inner ring part

[0079] Surface of D inner ring part

[0080] β Horn Angle

[0081] 10-speaker vertical array

[0082] 12 speakers

[0083] 14 Low-frequency transducers

[0084] 16 High-frequency transducers

[0085] 18 Circular Exits

[0086] 20 Magnetic Motors

[0087] 22 Diaphragm

[0088] 23 Compression Chamber

[0089] 24-phase plug

[0090] 26 Adapters

[0091] 28 Linear Exit

[0092] 30 speaker assembly

[0093] 32 drives

[0094] 34 Phase plugs

[0095] 36. Shell

[0096] 38 Magnetic Motor Assembly

[0097] 40 voice coil

[0098] 42 Dome Diaphragm

[0099] 44 Elastic elements

[0100] 46 Compression Chamber

[0101] 48 First Section

[0102] 50 Second Section

[0103] 52 Boundary Surface

[0104] 54. Terminal of the first section of the phase plug

[0105] 56 innermost passage

[0106] 56' Entrance

[0107] 56'' Export

[0108] 58 outermost passage

[0109] 58' entrance

[0110] 58'' Export

[0111] 60 First Mode

[0112] 62 Second Mode

[0113] 64 Acoustic entrance, second section

[0114] 66 Acoustic Exit, Second Section

[0115] 68 Second Section Road

[0116] 70 Outer ring parts

[0117] 72 First side

[0118] 74 Second side

[0119] 76. Fitting groove

[0120] 78 Inner Ring Parts

[0121] 80 rings

[0122] 82 Circular section

[0123] 84 Install support legs

[0124] 86 mounting holes

[0125] 88. Outer shell

[0126] 90 Inner wedge element

[0127] 92 Circular flange

[0128] 94 Planar Surface

[0129] 96 Non-circular cut

[0130] 98 Install lugs

[0131] 100 mounting recess

[0132] 102 Circular Receiver

[0133] 104 linear peaks

[0134] 106 Main Surface

[0135] 108 surface

[0136] 110 plug

[0137] 112 Receiver port

[0138] 120° curved inner wedge element

[0139] 122 Curved upper surface

[0140] 124 Multi-cavity internal wedge element

[0141] 126 blades

[0142] 126' inner blade

[0143] 126'' outer blade

[0144] 128 channels

[0145] 130-degree curved exit

[0146] 132 Part One

[0147] 134 Part Two

[0148] 136 loudspeakers

[0149] 138. Curved, asymmetrical, multi-cavity internal wedge element

[0150] 140 Linear Asymmetric Multi-cavity Internal Wedge Element

[0151] 142 Linear symmetrical multi-cavity internal wedge element

Claims

1. A phase plug assembly for an electrically driven compression drive, comprising a first section and a second section, wherein, The first segment includes: a. A compression chamber formed by a convex or concave oscillating diaphragm and the boundary surface of the phase plug assembly adjacent to the oscillating diaphragm; b. A central axis of rotation, defined within the interior of the phase plug assembly, the central axis of rotation extending from the boundary surface of the compression chamber to the end of the phase plug assembly; c. At least two pathways, each of the at least two pathways extending about the central rotation axis and traversing the first segment of the phase plug assembly from the boundary surface to the terminal of the first segment, the at least two pathways including an innermost pathway and an outermost pathway disposed radially outside the innermost pathway; d. Wherein, the terminal of the first segment of the phase plug assembly is vertically displaced along the central rotation axis relative to the boundary surface of the first segment of the phase plug assembly; e. Wherein, the cross-sectional area of ​​each of the at least two pathways expands between the corresponding inlet at the boundary surface of the first segment of the phase plug assembly and the terminal of the first segment; f. Wherein, the length of the outermost path from the entrance at the boundary surface to the terminal of the first segment is equal to the corresponding length of the inner path, wherein the length is defined by the path length along the centerline of the path; g. Wherein, at the end of the first section of the phase plug assembly, the at least two passages are arranged in a plane perpendicular to the central axis of rotation and are vertically displaced relative to the compression chamber; h. Wherein, when viewed along the central axis of rotation, the shape of the at least two passages defined at the end of the first segment of the phase plug assembly forms a circular ring, an elliptical ring, or an oblong ring.

2. The phase plug assembly according to claim 1, wherein, The second section includes: a. An acoustic inlet, located at the end of the first section of the phase plug assembly; b. An acoustic outlet, vertically displaced relative to the acoustic inlet along the central axis of rotation, and having an outlet shape that is rectangular, rounded rectangular, oblong, or elliptical; c. At least one second-segment passage extending from the acoustic inlet through the interior of the second segment of the phase plug assembly to the acoustic outlet; d. Wherein, the acoustic outlet is configured to radiate acoustic energy from the phase plug assembly into free space, a horn, a waveguide, or other acoustic impedance matching device; e. Wherein, the total surface area of ​​the second section of the passage increases between the acoustic inlet and the acoustic outlet; f. Wherein, the propagation delay of the second segment through the phase plug assembly is determined along the length of the second segment path in order to control the acoustic phase of the wavefront radiated from the acoustic outlet.

3. The phase plug assembly according to claim 1, wherein, The first segment includes a first mechanical sub-assembly that defines the at least two pathways of the first segment and is mechanically discontinuous and separable from the second segment of the phase plug assembly.

4. The phase plug assembly according to claim 2, wherein, The second section includes a second mechanical sub-assembly that defines the acoustic inlet and the acoustic outlet of the second section and is mechanically discontinuous and separable from the first section of the phase plug assembly.

5. The phase plug assembly according to claim 1, wherein, The oscillating diaphragm includes a rotation axis that coincides with the central rotation axis of the phase plug assembly.

6. The phase plug assembly according to claim 2, wherein, The at least one second segment passage through the phase plug assembly is defined by a shield disposed inside the second segment of the phase plug assembly, the at least one second segment passage being defined by the outer wall of the shield and the inner wall of the second segment.

7. The phase plug assembly according to claim 4, wherein, The second mechanical sub-assembly includes an additional mechanical structure for further controlling the shape of the wavefront at frequencies where the vertical diffusion pattern narrows or widens.

8. The phase plug assembly according to claim 1, wherein, The entrances of the innermost and outermost passages at the boundary surface of the first segment of the phase plug assembly are located at the node positions of the axial acoustic mode of the compression chamber.

9. The phase plug assembly according to claim 2, wherein, The cross-sectional area of ​​the second section passage at the acoustic inlet is approximately 75% of the cross-sectional area of ​​the second section passage at the acoustic outlet.

10. The phase plug assembly of claim 6, wherein, The shield is wedge-shaped and includes a circular receiving end positioned near the acoustic inlet of the second section.

11. The phase plug assembly of claim 10, wherein, The shielding element includes a linear peak, which is located at the acoustic outlet of the second section opposite to the circular receiving end.

12. The phase plug assembly of claim 11, wherein, The outer wall of the shield includes opposing principal plane surfaces that extend from the circular receiving end to the linear peak, and that extend along the linear peak from a first end to a second end of the linear peak.

13. The phase plug assembly according to claim 12, wherein, The outer wall of the shield also includes opposing secondary curved surfaces that extend from the circular receiving end to the first and second ends of the linear peak, respectively.

14. The phase plug assembly of claim 10, wherein, The shield includes a curved upper surface disposed at the acoustic outlet of the second section and opposite to the circular receiving end.

15. The phase plug assembly according to claim 6, wherein, The shielding body includes a multi-cavity structure.

16. The phase plug assembly of claim 15, wherein, The multi-cavity structure includes a plurality of blades extending between the outer wall of the shield and the inner wall of the second section.

17. The phase plug assembly of claim 16, wherein, The plurality of blades extend from the acoustic inlet through the second section passage to the acoustic outlet.

18. The phase plug assembly of claim 17, wherein, The multiple blades divide the second section of the passage into multiple channels.

19. The phase plug assembly of claim 18, wherein, The shield is wedge-shaped and has generally planar opposing main surfaces and generally curved opposing secondary surfaces, the surface area of ​​the opposing main surfaces being greater than the surface area of ​​the opposing secondary surfaces, wherein the plurality of blades extend across the opposing main surfaces.

20. The phase plug assembly of claim 19, wherein, The shielding body includes a circular receiving end disposed near the acoustic inlet of the second section and a linear peak disposed at the acoustic outlet of the second section and opposite to the circular receiving end, the linear peak being formed by the intersection of the opposing main surfaces.

21. The phase plug assembly of claim 20, wherein, The plurality of blades includes two inner blades and two outer blades. The inner blades are arranged radially inside the outer blades relative to the central rotation axis. The inner blades extend a first distance from the linear peak to the acoustic outlet, and the outer blades extend a second distance from the linear peak to the acoustic outlet. The first distance is greater than the second distance.

22. The phase plug assembly of claim 21, wherein, The shield includes a curved exit defined by the inner blade and the outer blade.

23. The phase plug assembly according to claim 6, wherein, The shield is symmetrically shaped around the central axis of rotation.

24. The phase plug assembly of claim 6, wherein, The shield is asymmetrically shaped around the central axis of rotation.

25. The phase plug assembly of claim 19, wherein, The shield includes a circular receiving end disposed near the acoustic inlet of the second section and a curved upper edge disposed at the acoustic outlet of the second section and opposite to the circular receiving end, the curved upper edge being formed by the intersection of the opposing main surfaces.

26. The phase plug assembly according to claim 8, wherein, The innermost and outermost pathways are positioned at their entrances at the boundary surface of the first segment of the phase plug assembly to suppress the first-order axial acoustic mode of the compression chamber.

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