Grilles for acoustic transducers

Abstract

For example, a grille (102) for an acoustic transducer unit, the tweeter, has a configuration of holes whereby, when the configuration of holes is projected onto a conceptual plane, a pattern of holes (104) is formed by repeating tiled cells (106). The repeating cells include holes of a first shape (114) and holes of a second shape (116). The second shape (116) can have convex regions opposite concave regions (128) of the first shape (114). At least one of the shape, size, and orientation of the first shape can differ from the shape, size, and orientation of the second shape. Adjacent holes in the pattern are separated from one another by one or more walls (112), which extend along non-linear paths between the holes.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 481,150, filed January 23, 2023, and entitled "GRILLE FOR AN ACOUSTIC TRANSDUCER." This application claims the benefit of UK Patent Application No. 2,300,981, filed January 23, 2023, and entitled "GRILLE FOR AN ACOUSTIC TRANSDUCER." The entire contents of each of the above-identified applications are incorporated herein by reference and made a part of this specification for all that they disclose.

[0002] The present disclosure relates to grilles for acoustic transducers. More particularly, but not exclusively, the present disclosure relates to loudspeaker grilles such as those used with speaker drivers (e.g., tweeter units) forming part of loudspeakers (e.g., high-fidelity loudspeakers). The present disclosure also relates to methods of making such loudspeaker grilles. [Background technology]

[0003] Loudspeaker grilles for loudspeakers, such as high-end hi-fi loudspeakers, generally perform the function of protecting the loudspeaker diaphragm from damage while attempting to avoid or minimize adverse effects on the reproduction quality of the sound emitted by the loudspeaker. While various loudspeaker grilles are known, there remains a need for improved loudspeaker grilles. Summary of the Invention [Problem to be solved by the invention]

[0004] It is an object of the present disclosure to provide improved grilles, such as high performance grilles for acoustic transducers, as a replacement for grilles that currently form the prior art. It is an alternative or additional object of the present disclosure to provide improved grilles, particularly improved tweeter grilles, for acoustic transducers. [Means for solving the problem]

[0005] For illustrative purposes, certain exemplary embodiments are outlined below. The embodiments are not limited to the particular implementations described herein. The embodiments may include several novel features, none of which are solely responsible for desired attributes or are essential to the embodiments.

[0006] The present disclosure provides a grille for an acoustic transducer unit, the grille having an arrangement of holes such that, when the arrangement of holes is projected onto a conceptual plane, a pattern of at least 20 holes (possibly at least 50 or more holes and possibly at least 150 holes, or any value or range therebetween) is present. The pattern is formed by repeating tiled cells including at least one hole of a first shape (hereinafter referred to as the first hole) and at least one hole of a second shape (hereinafter referred to as the second hole), the tiled cells being tiled in a linear pattern adjacent to one another. According to a first aspect of the disclosure, the second shape can have a convex region opposite a concave region of the first shape.

[0007] When applied to, for example, tweeter grilles, embodiments have been found to perform better than comparable grilles of other types. Without being limited by theory, this is believed to be a result of the hole shapes used in the tiling pattern and the configuration of the inter-hole structures. The structure (e.g., mesh) defining the holes / apertures can have sufficient structural integrity to provide physical protection against inadvertent damage to the acoustic transducer, while being sufficiently open (e.g., the total hole area per unit area is large enough) to allow good sound transmission through the grille across the operating frequency range. Having holes with concave portions can allow for more complex patterns than those proposed by the prior art, and therefore, such patterns have the potential to improve performance. A pattern in which convex areas of a second shape face concave areas of a first shape can allow for more efficient use of material (e.g., less material per unit area) and / or allow for larger holes / apertures per unit area.

[0008] The holes in a 3-D grille (corresponding to the holes in the 2-D pattern) can be defined by a structure surrounding the holes. This structure is sometimes referred to as a mesh. The mesh is sometimes considered to be formed only by walls, which define the holes. In three dimensions, the tweeter grille can have walls and holes (corresponding to the holes, but possibly with a slightly distorted shape as a result of conversion to a 3-D shape). The hole (and wall) pattern is primarily referred to herein in the context of a two-dimensional pattern formed by projection onto a conceptual plane (e.g., essentially preserving the shape and relative configuration of the 3-D pattern of holes). A projection is a mathematical projection used to convert a 3-D pattern into a 2-D pattern, such as a mathematical projection that approximates a stereographic projection. If there is a repeating pattern of shapes in a 3-D grille, regardless of distortion, etc., the projection can be one that maps the pattern of holes onto a conceptual plane (2-D), where each pattern of holes in such 3-D is mapped onto a tiled cell with an identical configuration, each cell having a hole configuration that corresponds to the stereographic projection of the hole pattern closest to the center of the grille.

[0009] The first hole can be a different shape than the second hole, the first hole can be a different size than the second hole, e.g., have a different area than the second hole, e.g., a larger area than the second hole, the first hole can have a different orientation than the second hole, e.g., have the same shape but rotated to a different angular position.

[0010] The first hole has a first area and a first orientation, and the second hole has a second area and a second orientation, whereby at least one of the shape, size, and orientation of the first hole may differ from the corresponding shape, size, and orientation of the second hole. The first shape may have an area that exceeds the area of ​​the second shape, for example, at least twice, preferably at least about 5 times, about 7 times, or in some cases, more than about 10 times, the area of ​​the second shape, or any value or range therebetween. In some embodiments, the area of ​​the first shape is at least about 17.5 times the area of ​​the second shape (but in some cases up to about 30 times, and in some cases in the range of about 10 times to about 25 times). The second shape may have an area that is greater than about 3% of the area of ​​the first shape. The second shape may have an area that is about 2%, about 3%, about 4%, about 5%, about 7%, about 10%, about 15%, or about 20% of the area of ​​the first shape, or any value or range between these percentages, although other designs are possible. The smallest hole area in a repeating cell is about 0.1 mm 2 The area of ​​the second shape may be greater than about 0.1 mm 2 exceeding 0.15 mm in some cases. 2 More than (in some cases, about 1 mm 2 The maximum hole area in a repeating cell can be approximately 2 mm 2 More than 3 mm in some cases 2 (In some cases, it can exceed 4 mm 2 and / or in some cases, approximately 10 mm 2 The area of ​​the first shape is 2 mm 2 More than 3 mm in some cases 2 More than (in some cases, 4 mm 2 and / or in some cases, 10 mm 2 The largest hole in the repeating cell may have the same area as the first shape (they may be the same hole). The smallest hole in the repeating cell may have the same area as the second shape (they may be the same hole).

[0011] The percent open area of ​​the packed cells (defined as the area of ​​the holes expressed as a percentage of the total area of ​​the cells) can be greater than about 50%, and in some cases, about 50% to about 70%, such as about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, or more, or any value or range therebetween, although other designs can be used. Preferably, the hole pattern in the cells as designed (i.e., before fabrication, and thus before etching, machining, application of coatings, etc.) has an open area greater than about 57%, and in some cases, about 58% or greater, depending on the pattern. The walls can have a width at their narrowest point greater than about 1 / 4 mm, preferably greater than about 1 / 3 mm (in some cases, less than about 2 mm, in some cases, less than about 1 mm), or any value or range therebetween, although other designs are possible.

[0012] The pattern may include walls such that adjacent holes in the pattern are separated from one another by one of the walls. The presence of a concave region and a corresponding convex region may mean that the walls extending between such regions, and in some cases extending from and / or to other portions of the pattern, extend along non-linear paths. Additionally or alternatively, there may be walls (e.g., walls of substantially constant width) that extend along non-linear paths between the concave region and the corresponding convex region, thereby defining the shape of the concave region and the corresponding convex region. Having walls that do not follow a straight line (when viewed as a 2-D pattern) may enable improved acoustic performance.

[0013] The pattern may include walls such that adjacent holes in the pattern are separated from one another by one of the walls. The walls may extend along non-linear paths between the holes. The walls may each have a minimum width. The walls may be configured such that it is not possible to distinguish three straight lines (in a 2-D pattern) such that (a) each line has a constant width that is about 75% of the minimum width of the wall (or sometimes about 50% or sometimes about 85% of the minimum width of the wall, or any value or range between these values), (b) each line extends completely through at least three cells, (c) each line is angled such that it is separated from each of the other two lines by an angle greater than about 30°, and (d) each line is entirely contained within the boundary of the wall. In other words, the pattern has at least some walls that deviate significantly from a linear path. Some meshes have 2-D patterns of holes such that non-linearities exist, but such patterns are generally observed in meshes where the shapes forming the holes are all the same shape, size, and orientation (e.g., all hexagonal) and / or the cells are not tiled in a linear fashion (e.g., radial / circular patterns of holes).

[0014] Some embodiments of the present disclosure may have the advantage that although the walls are non-linear, the first shape of the holes in the tiled cell pattern does not necessarily have a concave region opposite the convex region of the second shape of the holes. Thus, according to a second aspect of the present disclosure, the holes of a first shape have a first area and a first orientation, and the holes of a second shape have a second area and a second orientation, wherein at least one of the shape, size, and orientation of the first shape differs from the corresponding shape, size, and orientation of the second shape, and the pattern includes walls such that adjacent holes in the pattern are separated from each other by one of the walls, and the walls each have a minimum width and extend along a non-linear path between the holes so that it is not possible to distinguish three straight lines, such that (a) each straight line has a constant width that is approximately 75% of the minimum width of the wall, (b) each straight line extends completely through at least three cells, (c) each straight line is angled away from each of the other two lines by an angle greater than approximately 30°, and (d) each straight line can be configured to be entirely contained within the boundaries of the wall.

[0015] The following description will address features of the first and / or second aspects of the disclosure, with it being understood that features described with respect to one aspect may apply to the other aspect.

[0016] The tiled cells may have the minimum number of holes that allow tiled cells.

[0017] The tiled cells may be tiled in adjacent lines, e.g., such that the cells are staggered between adjacent lines. For example, every other adjacent line of cells may have aligned cells. The tiled cells may be diamond shaped. It will be understood that the tiled cells may only have full holes (no partial holes).

[0018] The first shape may have six-fold symmetry. The first shape may have at least three recessed regions (e.g., six recessed regions), each of which may face a corresponding convex region of a second shape in the pattern. The first hole may have the general form of an 18-sided polygon, with six equally spaced outer edges tangent to a notional circle, each joined to the next by two edges that abut the interior of the notional circle at an angle of about 100° to about 140° (possibly about 110° to about 130°) to form a recessed region. Preferably, the joints between adjacent edges are rounded to avoid sharp corners, and in some cases, each edge is substantially the same size (e.g., ±50% of the average size). The corners may be rounded such that no portion of the periphery of the corresponding hole in the grille has a radius of curvature smaller than about 0.1 mm (e.g., the radius is about 1 / 10 mm to about 1 / 4 mm). The rounded corners of the hole / aperture shapes in the grille may be formed at least in part as a result of applying one or more coatings to otherwise less rounded corners.

[0019] Each cell may include at least three holes, e.g., one first shape and at least two second shapes. The number of holes in a cell may be fewer than 10, and in some cases, five or less. Some embodiments may have only three holes per cell and only two different shapes (e.g., a large first shape and two smaller second shapes).

[0020] The grille can be made from a sheet of material, e.g., a sheet of material that is perforated when flat and then bent to form a predetermined shape. The sheet material can have a substantially constant thickness, e.g., before and / or after being bent to form a predetermined shape. The thickness of the sheet (and thus, e.g., the thickness of the mesh walls) can be about 0.1 mm or more, and in some cases at least about 0.2 mm. The thickness of the sheet can be about 2 mm or less, and in some cases about 1 mm or less. The grille (e.g., when forming a grille for a tweeter) can have a maximum dimension (generally the diameter of the grille) of about 100 mm or less, e.g., about 25 mm to 80 mm, although other sizes are possible.

[0021] The grille may have a dome shape or may include a dome-shaped portion, e.g., having a generally rounded shape when viewed from the front. The dome-shaped portion of the grille is referred to as a dome. The center of the dome may coincide with the hole in the first shape, particularly when the first shape is larger than the second shape. The dome may have a depth of at least about 10 mm, and in some cases, about 10 mm to about 30 mm. In such cases, the radius of curvature of the dome at its smallest portion may be in the range of about 10 mm to about 50 mm. In some embodiments, the dome may have a shallower profile, e.g., the radius of curvature of the dome at its smallest portion may be in the range of about 50 mm to about 100 mm. In such cases, the grille may have a lip, e.g., a cylindrical flange, extending rearward from the rearmost portion of the dome-shaped portion of the grille. The depth of the dome-shaped portion may be in the range of about 2 mm to about 10 mm. The depth of the lip may be in the range of about 2 mm to about 10 mm. The depth of the shallower grill features may range from about 5 mm to about 20 mm.

[0022] The grilles may have different sizes to suit different applications. The grilles may be used on midrange drive units or bass drive units. The grilles are preferably configured for use with acoustic transducer units that are high-fidelity quality drive units for high-fidelity loudspeakers. The loudspeaker grilles may be used, for example, for headphone applications, in which case the grilles may be relatively flat. It will be appreciated that if the grille is already flat, the hole configuration (in 3-D) may be the same as the hole pattern (in that the projection onto a conceptual plane is redundant as a result of the already flat pattern being the same in 3-D and 2-D).

[0023] The first hole may have a generally round shape. The first hole may have an outer periphery that defines the boundary of the hole in 2-D. The first hole may have a maximum diameter and a corresponding maximum radial distance from the center of the hole to the outer periphery of the hole. The first hole may have a minimum diameter and a corresponding minimum radial distance from the center of the hole to the outer periphery of the hole. The maximum diameter may or may not be exactly twice the maximum radial distance, and / or the minimum diameter may or may not be exactly twice the minimum radial distance. The first hole may have a generally round shape in that it is not elongated and / or pointed like a pointed star. For example, the maximum diameter of the first hole may be no more than about 60% larger (and in some cases, may be 10% to 50% larger) than the minimum diameter of the first hole. At least 20% of the length of the outer periphery of the first hole may be at least 90% of the maximum radial distance from the center of the hole. At least 20% of the circumference of the first hole may be at least 95% of the maximum radial distance from the center of the hole. At least 50% of the circumference may be at least 85% of the maximum radial distance from the center of the hole. About 15%, about 20%, about 25%, about 30%, about 40%, about 50%, about 60%, about 70%, or more (including any value or range therebetween) of the circumference of the first hole may be at least 95% of the maximum radial distance from the center of the hole. About 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or more (including any value or range therebetween) of the circumference may be at least 85% of the maximum radial distance from the center of the hole.

[0024] About 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70% or more (including any value or range therebetween) of the periphery length of the first hole can be at a distance of at least 95% of the maximum radial distance from the center of the hole. About 15%, about 20%, about 25%, about 30%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70% or more (including any value or range therebetween) of the periphery length of the first hole can be at a distance of at least 90% of the maximum radial distance from the center of the hole. About 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, or more (including any value or range therebetween) of the circumference can be at a distance of at least 85% of the maximum radial distance from the center of the hole.

[0025] The second hole may be, for example, generally round in shape, having a minimum diameter and a maximum diameter, with the maximum diameter being no more than about 30% larger (in some cases, less than about 20%) than the minimum diameter. The second hole may be, for example, rounded hexagonal. The second hole may have a maximum diameter that is about 10%, about 15%, about 20%, about 25%, or about 30% larger than its minimum diameter, or any value or range therebetween.

[0026] The grille may have a total of at least 300 holes, and in some cases, 500 or more holes (each hole corresponding to a hole in the pattern formed by the repeating tiled cells). The grille may be configured such that there are at least 100 holes of the first shape, in some cases, at least 150 holes, and in some cases, more than 200 holes. The (2-D) pattern of holes may be shaped such that for any selected 90° arc of the circle, a conceptual circle can be drawn around at least 50 holes, such that the circle intersects the holes.

[0027] As mentioned above, the grille may be an acoustic grille used in hi-fi applications of a variety of different sizes. The grille may offer particular advantages when in the form of a grille for a tweeter loudspeaker. In such cases, the grille may have a diameter of about 30 mm to about 100 mm, for example, about 40 mm to about 80 mm.

[0028] The grille may be attached to a drive unit, for example, a tweeter drive unit, for a high-fidelity loudspeaker. Accordingly, the present disclosure further provides a tweeter drive unit having a grille attached thereto according to any aspect of the present disclosure described herein. The tweeter drive unit may be a high-fidelity tweeter drive unit used in or mounted as part of a high-fidelity loudspeaker. The tweeter may be a carbon dome tweeter and / or a diamond-coated tweeter or a diamond dome tweeter. The tweeter unit may have its own body and / or its own dedicated housing.

[0029] The present disclosure further provides a high-fidelity loudspeaker comprising a tweeter drive unit according to any aspect of the present disclosure described herein. The high-fidelity loudspeaker may comprise an enclosure housing a mid-range loudspeaker driver and / or a bass loudspeaker driver. The same enclosure may house the tweeter drive unit. The tweeter unit (which may have its own body) may alternatively be mounted on the loudspeaker enclosure.

[0030] Also provided is a method of making a loudspeaker grill (e.g., for a tweeter unit) according to any aspect of the disclosure described herein, comprising bending or otherwise deforming a metal sheet (e.g., a flat metal sheet) to form a dome-shaped region, wherein the metal sheet has a pattern of at least 20 holes formed therein. The hole pattern may be machined from the sheet, for example, by cutting, drilling, or other machining techniques. The hole pattern may be formed in the sheet, for example, by forming the sheet with holes by molding techniques, additive manufacturing (e.g., 3-D printing), or similar methods.

[0031] Of course, features described with respect to one aspect of the present disclosure may be incorporated into other aspects of the present disclosure, e.g., a disclosed method may incorporate any of the features described with reference to a disclosed apparatus, and a disclosed apparatus may incorporate any of the features described with reference to a disclosed method.

[0032] Some embodiments will now be described in detail with reference to the following figures. Like reference numerals refer to like features throughout the figures. These figures are provided for illustrative purposes, and the embodiments are not limited to the particular implementation shown. Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying schematic drawings. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 2 is a schematic diagram showing one embodiment of a tweeter grille. [Figure 2] FIG. 2 is a schematic diagram showing one embodiment of a tweeter grille. [Figure 3] FIG. 2 is a schematic diagram showing one embodiment of a tweeter grille. [Figure 4] FIG. 2 is a schematic diagram showing one embodiment of a tweeter grille. [Figure 5] FIG. 2 is a schematic diagram showing one embodiment of a tweeter grille. [Figure 6]FIG. 2 is a schematic diagram showing one embodiment of a tweeter grille. [Figure 7] FIG. 2 is a schematic diagram showing one embodiment of a tweeter grille. [Figure 8] 4A and 4B are diagrams showing mesh hole patterns for a tweeter grill according to the first embodiment. [Figure 9] FIG. 9 is a diagram showing a part of the pattern of FIG. 8. [Figure 10] FIG. 9 shows a single hole of the pattern of FIG. 8. [Figure 11] 1 shows a loudspeaker incorporating a tweeter unit and a grille according to a first embodiment; FIG. [Figure 12] FIG. 12 is a diagram showing the tweeter unit of FIG. 11. [Figure 13] FIG. 2 is a side view of the grill of the first embodiment. [Figure 14a] 9 is a −6 dB frequency response contour plot comparing the performance of a tweeter unit according to the first embodiment using the pattern of FIG. 8 and a tweeter unit using the pattern of FIG. 5 . [Figure 14b] 10 is a −1.76 dB contour plot comparing the performance of the tweeter unit according to the first embodiment using the pattern of FIG. 8 and the tweeter unit using the pattern of FIG. 5 . [Figure 15] 17 is a sound pressure contour plot showing the performance of an example tweeter unit using the pattern of FIG. 5 with variable frequency and measurement position (in degrees) for comparison with FIG. 16. [Figure 16] 16 is a plot similar to FIG. 15 but showing the performance of a tweeter unit according to the first embodiment using the pattern of FIG. 8. [Figure 17] 9 is a power spectrum plot from 3 kHz to 6 kHz comparing the performance of the tweeter unit according to the first embodiment using the pattern of FIG. 8 and the tweeter unit using the pattern of FIG. 5. [Figure 18] 9 is a power spectrum plot covering 20 kHz to 35 kHz comparing the performance of the tweeter unit according to the first embodiment using the pattern of FIG. 8 and the tweeter unit using the pattern of FIG. 5. [Figure 19] 9 shows a loudspeaker incorporating a tweeter unit and a grille used to test an embodiment of the grille, also using the pattern of FIG. 8. [Figure 20] 10 shows a variation of the hole pattern according to a further embodiment (one different pattern, hence the second embodiment). FIG. [Figure 21] 10 shows a variation of the hole pattern according to a further embodiment (one different pattern, hence the third embodiment). FIG. [Figure 22] FIG. 10 shows a variation of the hole pattern according to a further embodiment (one different pattern, hence the fourth embodiment). [Figure 23] FIG. 10 shows a variation of the hole pattern according to a further embodiment (one different pattern, hence the fifth embodiment). [Figure 24] FIG. 10 shows a variation of the hole pattern according to a further embodiment (one different pattern, hence the sixth embodiment). [Figure 25] FIG. 10 shows variations in the hole pattern according to a further embodiment (one different pattern, hence the seventh embodiment). [Figure 26] FIG. 10 shows a variation of the hole pattern according to a further embodiment (one different pattern, hence the eighth embodiment). [Figure 27] FIG. 10 shows variations in hole patterns according to a further embodiment (one different pattern, hence the ninth embodiment). [Figure 28] FIG. 10 shows variations in hole patterns according to a further embodiment (one different pattern, hence the tenth embodiment). [Figure 29] FIG. 11 shows variations in the hole pattern according to a further embodiment (one different pattern, hence the eleventh embodiment). [Figure 30] FIG. 16 shows variations in hole patterns according to a further embodiment (one different pattern, hence the twelfth embodiment). [Figure 31] FIG. 13 shows variations in hole patterns according to a further embodiment (one different pattern, hence the thirteenth embodiment). [Figure 32] FIG. 14 shows variations in hole patterns according to a further embodiment (one different pattern, hence the fourteenth embodiment). [Figure 33] FIG. 15 shows variations in hole patterns according to a further embodiment (one different pattern, hence the fifteenth embodiment). [Figure 34] FIG. 16 shows variations in hole patterns according to a further embodiment (one different pattern, hence the sixteenth embodiment). [Figure 35] FIG. 17 shows variations in hole patterns according to a further embodiment (one different pattern, hence the seventeenth embodiment). [Figure 36] FIG. 18 shows variations in hole patterns according to a further embodiment (one different pattern, hence the 18th embodiment). [Figure 37] FIG. 19 shows variations in hole patterns according to a further embodiment (one different pattern, hence the nineteenth embodiment). [Figure 38] FIG. 10 shows an example of how a 3-D pattern of holes can be projected as a pattern of holes on a flat 2-D surface. [Figure 39] FIG. 20 shows a loudspeaker incorporating a tweeter unit and grille according to a twentieth embodiment. [Figure 40] FIG. 20 is a side view of the grill of the twentieth embodiment. [Figure 41] 21 is a flowchart showing steps for making a loudspeaker according to a twenty-first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0034] The various features and advantages of the systems, devices, and methods of the technology described herein will become more fully apparent from the following description of illustrated examples. These examples are intended to illustrate the principles of the present disclosure and should not limit the disclosure to only the illustrated examples. Those skilled in the art may modify, combine, delete, and / or substitute features of the illustrated examples as would become apparent upon consideration of the principles disclosed herein.

[0035] A loudspeaker grille may be able to affect at least some aspects of the quality of sound reproduction. Some aspects of sound reproduction quality may be evaluated, for example, by making objective measurements of a loudspeaker's performance when the loudspeaker is operated with an amplified test signal in an anechoic chamber. Some aspects of sound reproduction quality may be evaluated by a panel of appropriately qualified listening experts who can judge the performance of one type of configuration versus another. Quality may be measured or compared, for example, using a combination of such evaluations. The performance of a loudspeaker grille may be judged in terms of clarity of reproduction across the audible spectrum, perceived resolution of sound, and imaging of sources across the sound stage (accuracy of stereo sound reproduction), as well as other factors. When judging the quality of sound reproduced by a tweeter and its associated grille, attention may generally be focused on the higher frequencies in the audible range and how clear or crisp the sound reproduction is. Both the quality perceived by a listener or group of listeners and the objective assessment that can be made using acoustic measurement equipment can be used to aid in the design and manufacture of acoustic equipment such as tweeters and their grilles (e.g., hi-fi acoustic equipment).

[0036] Loudspeaker grilles, particularly those for tweeters, may often have a curvature that defines a partial spherical or dome-shaped form that generally appears concave when viewed from in front of the tweeter (facing the sound-emitting front of the tweeter).

[0037] Loudspeaker grilles can be designed to have a certain level of acoustic transparency while still providing sufficient protection against unexpected damage to the loudspeaker below. Without proper protection, such damage could occur from impacts to objects or people, such as a poking finger or an overly curious pet. The grille can be made of fabric. In some cases, such as those involving tweeters, the grille can be an open mesh, with open air holes allowing sound to pass more freely. The mesh can be a relatively rigid structure formed by a solid material that defines the holes. The mesh can be initially fabricated as a flat structure and then bent / stretched / deformed into the desired 3-D shape.

[0038] Various patterns of mesh can be used as the basis for patterns for loudspeaker (e.g., tweeter) grilles. While patterns can become more complex in three dimensions as a result of the curvature of the grilles referenced above, in some cases a basic regular / repeating pattern in two dimensions can be discerned from the 3D pattern actually seen. When mapped to a 2-D surface, such patterns can be characterized as tessellated patterns of holes having identical shapes (e.g., each hole is a regular polygon). For example, FIG. 1 shows a pattern of square holes 4. It will be appreciated that there is structure in the form of a mesh 2 (e.g., a metal wire mesh in the case of FIG. 1) between the holes to define the holes 4 as distinct shapes. Such a pattern can be considered in terms of its tessellation as formed by repeating tessellated cells 6 (depicted separately in FIG. 2 as dashed lines) with square holes. The mesh forming the pattern may be made by interweaving a first set of parallel, spaced apart wires with a second set of parallel, spaced apart wires that extend in a direction perpendicular to the first set of wires.

[0039] Another 2-D pattern of holes for a loudspeaker grille is shown in FIG. 3, which shows a pattern of hexagonal holes 4 formed by a mesh 2 and repeating tiled cells 6 (shown separately in FIG. 4) with a single hexagonal hole. The mesh forming the pattern may be made from a flat metal sheet that is etched or machined to remove material and form the desired pattern of holes. Further patterns are shown in FIGS. 5 and 6, which schematically show the 2-D patterns of holes on tweeter grilles used in 800 Series Diamond™ loudspeakers (e.g., the 801D4 speaker) and 600 Series Anniversary Edition loudspeakers (e.g., the 606 S2 Anniversary Edition) (albeit on tweeter grilles with different three-dimensional shapes), all of which are manufactured and sold by a company known as Bowers & Wilkins®. This pattern can be seen to be formed by repeating tiled cells 6 (see Figure 6) with a single hexagonal hole 8 and two smaller triangular holes 10. Similar to the patterns in Figures 1 and 3, the tiled cells 6 are tiled in adjacent linear fashion to form the pattern. The mesh 2 can be formed by etching the holes 6 from a flat sheet and then deforming the flat sheet as needed to form the desired three-dimensional shape for the tweeter grille. The mesh 2 can be viewed as having holes 4 separated by walls 12. As shown in Figure 7, the pattern of holes 4 and walls 12 can be formed by three separate sets of parallel, spaced-apart linear walls, whereby each wall in one set is at ±60° to each of the other two sets of walls. In the world of high-end hi-fi equipment, improved performance is always desired.Given the high level of discrimination in the hi-fi market, even relatively small improvements in the performance of one or more parts of a particular hi-fi setup, as measured with scientific equipment, can be perceived by the human ear as a noticeable improvement in performance.

[0040] FIG. 8 shows a 2-D pattern of holes 104 used on a tweeter grill 102 for a loudspeaker (e.g., a hi-fi loudspeaker), which may have a curved shape in three dimensions. The hole pattern may be defined by a metal mesh. The metal mesh may be formed from a 0.5 mm thick carbon steel plate by a process of creating a blank workpiece from the steel plate and then etching away a 2-D pattern of holes according to the 2-D pattern shown in FIG. 8. Other thicknesses and materials may be used. The plate may be approximately 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, or any value or range therebetween, although other configurations are possible. The workpiece is then deformed and cut into the desired 3-D shape, for example, by stamping using a press, which may be a two-step process. The workpiece then undergoes a coating process, which may include depositing a primer layer of approximately 15 μm on each side of the workpiece, for example, by using an electrophoretic deposition (ED) process, followed by spraying an outer coating layer (wet-sprayed) on each side to a thickness of 20 μm ± 5 μm on each side. Thus, the coating may form a coating finish to a thickness of approximately 30-40 microns on each side. Many variations are possible. For example, one or both of the primer layer and coating layer may be omitted or may be applied to only one side. The primer layer and / or coating layer may have a variety of suitable thicknesses, such as approximately 10 microns, approximately 15 microns, approximately 20 microns, approximately 25 microns, approximately 30 microns, or more, or any value or range between any of these values.

[0041] From Figure 8, it can be seen that this example has a pattern of holes 104 formed by repeating tiled cells 106 (shown separately in Figure 9). The cells 106 have a single larger hole 114 and two smaller holes 116. The cells are shown as diamond-shaped in Figures 8 and 9, but could alternatively be formed by tiled cells of different shapes (e.g., similar to the shape of the cells in Figure 6). The holes are separated by walls 112 that form the structure of the mesh. In this implementation, the tiled cells 106 are tiled in adjacent linear fashion to form the pattern.

[0042] In this and other embodiments, the larger hole 114 can have rotational symmetry. In the examples of Figures 8 and 9, the larger hole 114 has six-fold symmetry, but other examples can have three-, four-, eight-, or more-fold rotational symmetry. The larger hole 114 can have a shape similar to that shown in Figure 10, which shows a circle 120 with six lenticular curved cutouts 122 removed. The larger hole 114 can have a minimum diameter of 1.9 mm and a maximum diameter (dimension 124) of about 2.5 mm (i.e., about 30% larger). In some implementations, the larger hole 114 can have a dimension 124 across the widest part of the opening that can be about 1 mm, about 1.2 mm, about 1.4 mm, about 1.6 mm, about 1.8 mm, about 2 mm, about 2.2 mm, about 2.4 mm, about 2.6 mm, about 2.8 mm, about 3 mm, or more, or any value or range between any of these sizes (e.g., 1.8 mm to 2.6 mm). Dimension 124 can extend through the center of the larger hole 114. FIG. 10 shows an arc 126 drawn at a radius that is 90% of half the maximum diameter. It will be appreciated that approximately half the hole's circumference (and certainly more than a quarter of the circumference) is outside the 90% radial distance. The shape of the larger hole 114 can have an outer portion of its circumference (e.g., outside of arc 126 in FIG. 10 ) that is spaced apart from the center by a distance that exceeds 90% of the maximum distance from the center to the circumference of the larger hole 114. The outer portion of the circumference can be about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, or more of the total circumference, or any value or range between any of these percentages, although other designs are possible.

[0043] The shape of the larger hole 114 has 18 distinct, substantially straight sides, six of which lie substantially on the circumference of a notional circle having a diameter of the largest diameter. The other 12 sides are divided into six pairs, with each pair of sides abutting the interior of the notional circle at an angle of approximately 120°, thus forming six recessed regions 128. The corners where adjacent sides abut are each rounded with a radius of curvature of approximately 0.1 mm to approximately 0.2 mm (e.g., approximately 0.15 mm). Many variations are possible, such as shapes similar to FIG. 10 but having four, five, eight, ten, twelve, or more recessed regions.

[0044] The smaller holes 116 can be rounded. The smaller holes 116 can be in the form of a rounded hexagon. In some cases, the smaller holes 116 can be nearly circular. In some implementations, any corners in the holes 114, 116, which are otherwise defined by two straight edges meeting at an angle, are formed by rounded edges, for example, having a radius of curvature of about 0.1 mm to about 0.2 mm (e.g., about 0.15 mm). The larger holes 114 can have a diameter or width of about 1 mm to about 3 mm (e.g., about 2.5 mm), and the smaller holes 116 can have a diameter or width of about 0.2 mm to about 1 mm (e.g., about 0.5 mm). The width of the walls separating the holes can be about 0.2 mm or about 0.4 mm to about 1 mm (e.g., about 0.5 mm, although narrower wall widths are possible with stronger materials and / or greater thicknesses). As a result, the percentage of open area defined by the mesh can be about 60% (about 58% in the embodiment of Figures 8-10). In other configurations, the open area defined by the mesh can be about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, or any value or range between any of these percentages, although other designs are possible. The total area of ​​the packed cells is about 8 mm. 2 The total area of ​​the mesh is approximately 4,000 mm 2and the hole pattern covers most (>75%) of this area. Thus, there are about 500 tiled cells, which equates to about 1,500 holes in the mesh. Thus, counting from one side of the grille (at the perimeter of the pattern) across the diameter of the grille to the other side, there may be a line of 15 to 40 large holes (e.g., about 25). Other cell sizes, mesh sizes, and grille sizes can be used.

[0045] As best seen in Figure 8, each larger hole 114 can be considered to be surrounded by six smaller holes 116, and each smaller hole 116 can be considered to be surrounded by its three immediate larger holes 114. The smaller holes 116 are convex, thus having a convex portion that opposes the nearest concave region of each of its neighboring larger holes 114. Also seen in Figure 8, four notional lines are depicted, including a thin line 130 at 30° to the vertical that is generally contained within the boundary of the wall between the holes, and three translucent thick lines 132, 134, 136, each having a thickness of approximately 0.25 mm (approximately one-half the thickness of the wall 112). Lines 132 and 134 are depicted adjacent to each other, are perpendicular, and span the distance between adjacent larger holes 114 side by side. Lines 136 are drawn parallel to the thin lines 130 to illustrate that it is not possible to position a straight line of a constant width of 50% (let alone 75%) of the wall width so that it is entirely contained within the boundary of the wall. Even at 50% thickness, lines 136 cut off the sides of various holes 104. This is because the walls 112 that define the shape of the holes are not straight and therefore deviate from a straight line as they extend from one tiled cell 106 to the next. The pattern can be configured so that a line having a thickness over a threshold amount cannot extend between an arrangement of larger holes 114 and smaller holes 116 without overlapping one or more of the holes 114 or 116. The threshold thickness can be about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75% of the thickness of the wall 112 or the distance between adjacent holes, or any value or range between any percentage thereof, although other designs are possible.

[0046] A mesh having the pattern of FIG. 8 was formed into a tweeter grille 102 used on the 805 D4 loudspeaker of the 800 Series Diamond™ loudspeaker series commercially available from Bowers and Wilkins. Forming such a grille using this mesh involves bonding a plastic retaining ring mechanism to the metal mesh. The finished grille has a 3-D shape. The 2-D pattern shown in FIG. 8 is deformed by a stamping process, which stretches the 2-D workpiece into the desired 3-D shape. Therefore, the hole pattern in 3-D differs from the 2-D pattern resulting from this deformation. To identify the 2-D pattern formed by a repeating tile of holes, each cell having the same shape, the 3-D pattern of holes seen in the 3-D mesh of the grille is conceptually projected onto a flat 2-D surface to invert the deformation caused by the deformation (e.g., stamping).

[0047] The 805 D4 speaker (shown diagrammatically in FIG. 11) is a two-way loudspeaker designed to be mounted on a stand, with a 25 mm tweeter housed within its own unit 140 mounted on a front-ported enclosure 142 that houses a single midrange / bass driver unit 144. The tweeter unit 140 is shown in plan view in FIG. 12, which shows the tweeter grille 102 mounted on the front of the unit. The dome shape of the tweeter grille can be seen separately in FIG. 13. The dome has a diameter d of approximately 60 mm and a height h of approximately 20 mm. Various other sizes and configurations of the grille can be used, depending, for example, on the driver to be covered.

[0048] An 805 D4 loudspeaker having a tweeter grille according to the first embodiment (e.g., using the pattern of FIG. 8) was compared to the same speaker fitted with a tweeter grille made from a mesh etched using the patterns shown in FIGS. 5 and 6 and then stamped and coated / painted in the same manner as the present embodiment. Prior to coating / painting, the area of ​​the smaller holes in the mesh using the pattern of FIG. 5 was approximately 25% larger than the smaller holes in the mesh using the pattern of FIG. 8, and the area of ​​the larger holes in the mesh using the pattern of FIG. 5 was approximately 0.5% smaller than the larger holes in the mesh using the pattern of FIG. 8, with approximately the same wall widths. As a result, the open area as a percentage of the total area covered by the pattern was approximately 0.5% smaller for the mesh using the pattern of FIG. 5 than for the mesh using the pattern of FIG. 8.

[0049] First, objective testing was performed, comparing the frequency response of loudspeakers with grilles using the pattern in Figure 8 and those using the pattern in Figure 5. Frequency response measurements were performed in an anechoic chamber. This chamber approximates free-field conditions, i.e., no or minimal reflections from walls, ceiling, or floor. This distinguishes the room's influence on measurements above a specific cutoff frequency, in this case, approximately 100 Hz. The system's frequency response was measured to create a directivity map showing the frequency response for different beam angles. Measurements were taken in the front hemisphere, 1.65 m from the front of the tweeter dome, from -90° to +90° in the horizontal plane at 5° intervals (0° being the on-axis response). All measurements were taken at the same vertical height, which is the same height as the tweeter dome's midpoint. The results are shown in the graphs in Figures 14a through 18.

[0050] FIG. 14a is a -6 dB frequency response contour plot with frequency along the horizontal axis (as a logarithmic scale from 200 Hz to 40 kHz) and angle along the vertical axis (as a linear scale from -90° to +90°). The plot shows four -6 dB contours, one on each side of the 0° position for a grill using the pattern of FIG. 5 and a corresponding contour on each side for an embodiment using the pattern of FIG. 8, indicating a -6 dB drop in frequency response. All contours are normalized to 0°. Black area 146 is the boundary on one side with the closest of the two -6 dB contours, and light gray area 147 is the boundary for the other of the two -6 dB contours. Areas where the mesh of FIG. 5 falls off at wider angles than the mesh of FIG. 8 are indicated by white shading 148, while areas where the mesh of FIG. 8 falls off at wider angles than the mesh of FIG. 5 are indicated by dark gray shading 150. This indicates that the grille using the pattern of Figure 8 has better symmetry in response to deviations from the 0° listening position (on-axis) compared to the grille using the pattern of Figure 5.

[0051] Figure 14b is a contour plot for -1.76 dB degradation comparing a design with a grille using the pattern of Figure 8 (solid line) and a similar grille using the pattern of Figure 5 (dashed line). Looking at 1.315 kHz (within the region of peak sensitivity for the average listener), Figure 14b shows a significant reduction in the deviation between the left and right listening positions for the pattern of Figure 8 (approximately 1°, the difference in height between the solid arrows) compared to the pattern of Figure 5 (approximately 6°, the difference in height between the dashed arrows). Ideally, the contour plots for both sides of the 0° position would be symmetrical, resulting in zero deviation.

[0052] Figures 15 and 16 are frequency response plots for a grill using the pattern of Figure 5 (Figure 15) and a grill using the pattern of Figure 8 (Figure 16). These contour plots are sound pressure contour plots (different shades of gray indicate steps from 66 dB to 94 dB) as a function of frequency (values ​​along the horizontal axis, logarithmic scale from 200 Hz to 40 kHz) and angle (values ​​along the vertical axis, linear scale from -90° to +90°). It can be seen that around the 4 kHz region (marked by circle 152 in FIGS. 15 and 16 ) where human hearing is most sensitive, there is a slight dip (loss of energy) in the frequency response present in the pattern of FIG. 5 (see the 86 dB region between the two 88 dB regions at 0° within circled region 152 in FIG. 15 ) that is filled in the corresponding frequency response in the embodiment (note the absence of the dip from the 88 dB region along 0° within circled region 152 in FIG. 16 ). A smoother response is also seen in the dispersion and in the on-axis and power spectral responses (compare FIG. 16 with FIG. 15 ). The 4.7 kHz peak 154 (observed in FIG. 15 ) present in the pattern of FIG. 5 is also attenuated, resulting in improved smoothness and tonal balance in that region in the embodiment using the pattern of FIG. 8 (the peak is absent in FIG. 16 ).

[0053] FIG. 17 is a power spectrum plot from 3 kHz to 6 kHz averaged over all measured angles, comparing the performance of an embodiment using the pattern of FIG. 8 (solid line 156) with the performance of the pattern of FIG. 5 (dashed line 158). The smoother performance of the embodiment using the pattern of FIG. 8 is clearly seen, boosting the level from 3.8 to 4.4 kHz by approximately 0.2 dB. FIG. 18 is a similar graph to FIG. 17, but shows a power spectrum plot at higher frequencies from 20 kHz to 35 kHz. These frequencies are generally outside the normal hearing range, as sound contains energy only at or above these frequencies, but are nevertheless considered important to the quality of sound reproduction at the high end of the normal hearing range. Again, the performance of the embodiment using the pattern of FIG. 8 is shown using the solid line 156, and the performance of the version using the pattern of FIG. 5 is shown using the dashed line 158. The embodiment using the pattern of FIG. 8 boosts the sound level by up to 0.3 dB from 20 kHz to 34 kHz, thus improving performance at these higher frequencies.

[0054] Thus, the grille embodiment using the pattern of Figure 8 exhibits objectively superior performance compared to the grille using the pattern of Figure 5. The grille using the pattern of Figure 5 does not have holes with concave areas opposing convex holes. The grille using the pattern of Figure 5 has a pattern of holes formed (in 2-D) by three sets of parallel, straight walls, each set at 60° to the other sets.

[0055] Listening tests were also conducted to compare the performance of the embodiment using the pattern of FIG. 8 with the version using the pattern of FIG. 5. Listening tests were conducted on multiple occasions with a panel of trained and untrained listeners to evaluate the perceived performance of the embodiment and the prior art tweeter grilles. In this case, the comparison was made using a pair of 801 D4 loudspeakers commercially available from Bowers & Wilkins, each having a tweeter grille according to the embodiment using the pattern of FIG. 8, and a pair of the same speakers fitted with a tweeter grille using the pattern of FIG. 5. The tweeter grille used was the same type of tweeter grille used in the objective comparison. A schematic diagram of the 801 D4 loudspeaker is shown in FIG. 19. The loudspeaker was a three-way bass-reflex loudspeaker with a main floor-standing enclosure 142 containing two 10-inch (25 cm) woofers 143, atop which was a single 6-inch (15 cm) midrange unit 145 housed in a separate housing (called a "turbine head" by Bowers and Wilkins), and a 1-inch (25 mm) tweeter housed in its own unit 140. The listening environment was an acoustically matched listening room. Additional listening sessions were also conducted with trained listeners on 700S3 Series products utilizing a "tweeter-on-top" configuration.

[0056] There was good evidence from listeners that the embodiment using the pattern of Figure 8 outperformed the version using the pattern of Figure 5. The overall improvement in audio quality as indicated by listeners was as follows: ○ Improved clarity across the audible spectrum. ○ Lower noise floor for improved resolution at the top end. o Increased perceived soundstage depth due to increased "air" (also associated with a lower noise floor). ○ Improved imaging of sources in the soundstage. o Increased perceived soundstage width. Increased "snap" without introducing sharpness, resulting in a more realistic and natural perception of instruments. ○ Improved overall tonal balance. ○ Reduced fatigue for easier listening over longer periods of time.

[0057] Experiments were conducted to evaluate whether other patterns of holes possessed the characteristics of (a) large holes each having multiple concave regions paired with smaller convex holes, and / or (b) holes defined by walls that deviate from a straight line in at least one of the walls' major directions. Other such patterns are shown in Figures 20-37. In each figure, the tiled cells are outlined with dashed lines, and in some figures, semi-transparent lines approximately 75% of the wall thickness are included to indicate that the walls are non-linear in certain directions (which may not be obvious). Thus, it can be seen that the patterns in Figures 20-26, 34, and 35 are each formed by repeating tiled cells with holes having convex regions that oppose the concave regions of another hole. However, Figures 27-33 and 36-37 do not possess this characteristic. It can be seen that all patterns in Figures 20-37 are defined by non-linear walls (e.g., whereby it is not possible to identify or draw straight lines at three different angles and within the boundaries of the walls, each straight line having a constant width of 75% of the wall width and extending completely through at least three cells). Based on subjective testing, patterns with better performance tended to be more similar to the pattern in Figure 8 (e.g., Figures 20-23), but also included the patterns in Figures 27, 29, 32, 34, 35, and 37. It is noteworthy that while Figures 32, 35, and 37 each contain only one shape of hole, the tiled cells contain the same shape (and same size) in three different orientations (Figure 32), the same shape (and same size) in four different orientations (Figure 35), and the same shape (and same size) in two different orientations (Figure 37). Figure 36 has a cell in which the two holes are the same shape and orientation, but different sizes.

[0058] It will be appreciated that the holes (corresponding to holes) in the 3-D grille are defined by a mesh surrounding the holes. The mesh can be considered to be formed only by the walls, which define the holes. In three dimensions, the tweeter grille has walls and holes (corresponding to the holes shown in Figures 8 and 20-37), possibly with a slightly deformed shape as a result of the transformation that transforms the flat etched plate into a 3-D mesh shape. It may be obvious that the 3-D mesh is created using a specific 2-D pattern of tiled cells of holes. The hole (and wall) pattern is referred to herein primarily in the context of such a 2-dimensional pattern. To understand the 2-D pattern of holes that forms the 3-D pattern of holes, it may be necessary to use a projection of the 3-D pattern onto a conceptual plane. The projection may be a mathematical projection used to transform the 3-D pattern into a 2-D pattern. For grilles originally made by forming a regular pattern of holes on a flat sheet and then shaping the flat sheet into a 3-D shape (typically by deforming each portion of the flat structure by different amounts), the projection (mathematical or otherwise) used to identify the properties of the 2-D pattern of holes may be one that mirrors as closely as possible the deformation that occurs when physically shaping the 2-D sheet into the 3-D grille. If repeating patterns of holes extending across the grille along substantially parallel paths (in 3-D) appear on the 3-D grille, and the number, layout, size, and orientation of holes in one pattern are substantially the same as the number, layout, size, and orientation of holes in the next pattern (despite slight differences as a result of different local geometries of the grille's 3-D shape), the projection is preferably one that maps the pattern of holes onto the flat 2-D surface, and each such pattern of holes in 3-D onto a tiled cell having an identical configuration, each cell having a configuration of holes that corresponds to the stereographic projection of the hole pattern closest to the center of the grille.38, a stereographic projection of the hole pattern closest to the center of the grille can be formed by projecting the 3-D pattern onto a 2-D plane 160 that is tangent to the center of the forward-facing surface (the surface that smoothly covers the front of the mesh of grille 102). The stereographic projection has a projection center 162 that is vertically rearward from the intersection of the 2-D plane with the forward-facing surface of the grille a distance equal to twice the radius of curvature of the forward-facing surface at that intersection (e.g., a circle having that radius of curvature is shown in FIG. 38 using dashed line 164).

[0059] A further embodiment (the twentieth embodiment) is shown in FIG. 39 and utilizes a tweeter grille 202 with a shallower profile and a hole pattern on the tweeter grille with a slightly smaller diameter. The tweeter grille 202 can be used on speakers similar to the existing 603 S2 loudspeaker from the 600 Series Anniversary Edition loudspeakers available from Bowers and Wilkins. The 603 loudspeaker (shown diagrammatically in FIG. 39) is a three-way floorstanding loudspeaker with an enclosure 242 containing two woofers 243, a single midrange unit 245, and a tweeter unit 240 on top. The dome shape of the tweeter grille 202 for the tweeter unit 240 can be seen separately in FIG. 40. The dome has a diameter d of 57 mm, a height h of 10 mm, and is formed by a domed region 266 with a radius of curvature of approximately 90 mm, and a lip in the form of a cylindrical flange 268 with a depth of 5 mm. In this case, each large hole has a diameter of about 2.6 mm, while the small holes have a diameter of about 0.7 mm. The width of the walls separating them is about 0.5 mm at their narrowest point. The mesh has at least, very approximately, about 800 holes. In other embodiments, there may be, for example, up to 1,000 or more holes in total. Various other grill sizes and configurations can be used.

[0060] FIG. 41 shows a flowchart illustrating a method for manufacturing a loudspeaker unit through a series of steps. The loudspeaker being fabricated is a loudspeaker having a tweeter drive unit with its own housing mounted on a loudspeaker enclosure (i.e., a "tweeter-on-top" configuration). As a first step (represented by box 371), a flat metal sheet is provided. This may be pre-cut to size. Then, as a next step (represented by box 372), a pattern of holes is etched from the sheet to form a pattern (e.g., a pattern like that shown in FIG. 8). The metal sheet is then bent to form a 3-D dome (represented by box 373), in this case by stamping. Additional steps (not shown) of cutting around the edges (perimeter) and / or one or more further shaping steps may then be required, if necessary. A step of adding one or more coatings (e.g., electrophoretic deposition and / or spray painting) to one or both sides of the grille may also be required. The grille is then secured to the tweeter drive unit (step represented by box 374). As mentioned above, the tweeter drive unit may have its own housing, which in this embodiment may comprise a machined aluminum body with a plastic bezel attached. As a preliminary part of this step 374, a retaining ring may be adhered to a metal mesh to form a tweeter grille assembly consisting of the metal mesh and the retaining ring. This grille assembly may then be attached to the tweeter housing, with the grille assembly making contact with the housing and the plastic bezel. Attaching the grille assembly to the tweeter housing may be performed before or after securing the tweeter unit to the rest of the loudspeaker enclosure (step represented by box 375).

[0061] While the present disclosure has been described and illustrated with reference to particular embodiments, those skilled in the art will appreciate that the present disclosure is susceptible to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

[0062] The holes in the mesh need not extend to the periphery of the grille. For example, there may be an annular rim without such holes. Other shapes of grille may be used.

[0063] These embodiments may have application for other acoustic devices such as speakers for televisions, laptops, etc., for headphones or earphones (with appropriate scaling) and / or grilles for microphones.

[0064] The holes can be etched in 2-D with the pattern including some pre-distortion (in the pattern) so that when transformed into a 3-D shape, they form with a higher degree of similarity than would otherwise be the case.

[0065] It is possible to form the 3-D shape of the grille and then etch away material to form the pattern of holes. It may also be possible to 3-D print the desired pattern onto the mesh.

[0066] Different metal materials and different coatings may be used. In some cases, it may be possible to eliminate the wet painting process, especially when using materials with higher corrosion resistance. An alternative metal material is, for example, ferritic stainless steel (e.g., Grade 430). In some cases, other materials, such as non-metallic materials, may be used. The coating on the product may be thicker than the coating described above and may have a thickness of at least 50 microns on each side. Other dimensions may also be varied.

[0067] The method shown in Figure 41 may be adapted for tweeter drive units housed in a main loudspeaker housing (i.e., configurations in which the tweeter is mounted to the front baffle of the loudspeaker enclosure). In such cases, a grill mesh may be attached to the plastic bezel of the tweeter drive unit, in which case there may be a step of attaching a forward-facing trim ring that surrounds the grill and fits into a gap that would otherwise exist between the perimeter of the grill and the peripheral portion of the enclosure's front baffle.

[0068] While the above description refers to integers, values, or elements that have known, obvious, or predictable equivalents, such equivalents are incorporated herein as if individually set forth. The reader of this specification will understand that integers, values, or features of the present disclosure described as preferred, advantageous, convenient, or the like are optional and do not limit the scope of all embodiments of the present disclosure. Furthermore, it will be understood that such optional integers, values, or features may be advantageous in some embodiments, but may be undesirable in other embodiments and, therefore, may not be present.

[0069] Unless the context clearly requires, throughout the description and claims, words such as "comprise," "comprising," "include," "including," and the like should be construed in an inclusive sense, i.e., "including, but not limited to," rather than an exclusive or exhaustive sense. The words "coupled" or "connected," as generally used herein, refer to two or more elements, which may be directly connected or connected via one or more intermediate elements. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to particular portions of this application. Where the context allows, words in the detailed description using the singular or plural can also include the plural or singular, respectively. The word "or" referring to a list of two or more items is intended to cover all interpretations of this word: any of the items in the list, all of the items in the list, and any combination of the items in the list. All numerical values ​​provided herein are intended to include similar values ​​within the measurement error.

[0070] While the present disclosure includes several embodiments and examples, those skilled in the art will understand that the scope extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses and obvious modifications and their equivalents. Additionally, while several variations of the embodiments have been shown and described in detail, other modifications will be readily apparent to those skilled in the art based on this disclosure. Various combinations or subcombinations of specific features and aspects of the embodiments may be made, and such combinations are nevertheless contemplated to be within the scope of the present disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another to form various modes of embodiment. Any method disclosed herein need not be performed in the order described. Therefore, it is not intended that the scope be limited by the specific embodiments described above.

[0071] Conditional statements, especially "can," "could," "might," or "may," are generally intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not, unless otherwise specified or understood within the context in which they are used. Thus, such conditional statements are generally not intended to imply that features, elements, and / or steps are in any way required by one or more embodiments, or that one or more embodiments necessarily include logic for determining whether these features, elements, and / or steps are included in or performed in any particular embodiment, with or without user input or prompting. Any headings used herein are for the convenience of the reader only and are not intended to limit the scope.

[0072] Furthermore, while the devices, systems, and methods described herein may be susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are described in detail herein. However, it should be understood that the disclosure should not be limited to the particular forms or methods disclosed; on the contrary, the disclosure covers all modifications, equivalents, and alternatives within the spirit and scope of the various implementations described. Furthermore, any particular feature, aspect, method, characteristic, attribute, quality, attribute, element, etc., disclosed herein in connection with an implementation or embodiment can be used in all other implementations or embodiments described herein. Any method disclosed herein need not be performed in the order described. While the methods disclosed herein may include specific actions taken by a skilled person, the methods may also include any third-party instructions for those actions, whether express or implied.

[0073] Ranges disclosed herein also encompass all overlaps, subranges, and combinations of those ranges. Phrases such as "up to," "at least," "greater than," "less than," "between," and the like, are inclusive of the recited numbers. Numbers preceded by terms such as "about" or "approximately" are inclusive of the recited number and should be interpreted according to the context (e.g., as precisely as reasonably possible under the circumstances, e.g., ±5%, ±10%, ±15%, etc.). For example, "about 3.5 mm" includes "3.5 mm." Phrases preceded by terms such as "substantially" are inclusive of the recited phrase and should be interpreted according to the context (e.g., as reasonably possible under the circumstances). For example, "substantially constant" includes "constant." Unless otherwise specified, all measurements are taken under standard conditions, including ambient temperature and pressure. [Explanation of symbols]

[0074] 2 mesh 4 holes 6 Repeatedly tiled cells 8 single hexagonal holes 10 Two smaller triangular holes 12 Wall 102 Tweeter Grill 104 holes 106 Repeatedly Laid Cells 112 Wall 114 Bigger Hole 116 smaller holes 120 yen 124 Dimensions 126 arc 128 Concave area 130 Thin Lines 132, 134, 136 thick lines 140 units 142 Enclosure 143 Woofer 144 Midrange / Bass Drive Unit 145 midrange unit 146 Black Area 147 Light Gray Area 148 White Shading 150 dark gray shading 152 yen 154 Peak 156 solid line 158 dashed line 160 2-D plane 162 Projection Center 164 dashed line 202 Tweeter Grill 240 tweeter unit 242 Enclosure 243 Woofer 245 midrange unit 266 Dome-shaped Area 268 Cylindrical flange

Claims

1. A grille for an acoustic transducer unit, said grille having a hole configuration whereby when said hole configuration is projected onto a notional plane there is a pattern of at least 20 holes; the pattern is formed by a repeating tile of cells comprising at least one hole of a first shape and at least one hole of a second shape, whereby the second shape has a convex region opposite a concave region of the first shape; A grill, wherein the cells are arranged in a linear pattern adjacent to each other.

2. 10. The grille of claim 1, wherein the pattern includes walls whereby adjacent holes in the pattern are separated from one another by one of the walls, the walls extending along non-linear paths between the holes.

3. Each of the walls has a minimum width and is configured such that it is not possible to distinguish three straight lines, whereby each straight line has a constant width that is 75% of the minimum width of the wall; Each line extends completely through at least three cells; each line is angled more than 30° away from each of the other two lines; 3. The grille of claim 2, wherein each straight line is contained entirely within the boundary of the wall.

4. 4. The grill of claim 1, wherein the first shape has a first area and the second shape has a second, smaller area.

5. 5. A grille as claimed in any one of claims 1 to 4, wherein the first shape has a first orientation and the second shape has a second, different orientation or is a different shape.

6. 1. A grille for an acoustic transducer, said grille comprising: A grill comprising a mesh having an arrangement of holes, the arrangement of holes forming a pattern when the arrangement of holes is projected onto a notional plane by repeating tiled cells having at least one hole having a first shape and at least one hole having a second shape, whereby the second shape is arranged to have a convex region opposite a concave region of the first shape.

7. 7. The grille of claim 6, wherein the tiled cells are tiled in adjacent linear fashion.

8. 8. A grille as claimed in claim 6 or 7, wherein the pattern includes a plurality of walls, whereby adjacent holes in the pattern are separated from one another by one of the walls, the walls extending along a non-linear path between the holes.

9. Each of the walls has a minimum width and extends along a path between the holes, whereby it is not possible to identify a straight line, whereby the straight line has a constant width that is 75% of the minimum width of the wall; the straight line extends completely through at least three of the tiling cells; 9. The grille of claim 8, wherein the straight line is contained entirely within the boundary of the wall.

10. Each of the plurality of walls has a minimum width and is configured such that it is not possible to distinguish three straight lines, thereby each straight line has a constant width that is 75% of the minimum width of the wall; Each line extends completely through at least three cells; each line is angled more than 30° away from each of the other two lines; 9. The grille of claim 8, wherein each straight line is contained entirely within the boundary of the wall.

11. 11. The grill of any one of claims 6 to 10, wherein the first shape has a first area and the second shape has a second area that is smaller than the first area.

12. 12. The grille of any one of claims 6 to 11, wherein the first shape has a first orientation and the second shape has a second, different orientation.

13. 13. The grill of any one of claims 6 to 12, wherein the second shape has a different shape than the first shape.

14. A grille for an acoustic transducer unit, said grille having a hole configuration whereby when said hole configuration is projected onto a notional plane there is a pattern of at least 20 holes; the pattern is formed by a repeating tile of cells comprising at least one hole of a first shape having a first area and a first orientation, and at least one hole of a second shape having a second area and a second orientation, whereby at least one of the shape, size, and orientation of the first shape is different from a corresponding shape, size, and orientation of the second shape; The cells are arranged linearly adjacent to each other, the pattern includes walls, whereby adjacent holes in the pattern are separated from one another by one of the walls, each of the walls having a minimum width and extending along a non-linear path between the holes, whereby it is not possible to distinguish three straight lines, whereby each straight line has a constant width that is 75% of the minimum width of the wall; Each line extends completely through at least three cells; each line is angled more than 30° away from each of the other two lines; Each straight line is entirely contained within the boundary of said wall, grille.

15. 1. A grille for an acoustic transducer, said grille comprising: a hole configuration, the pattern being formed by repeating tiled cells that, when projected onto a notional plane, comprise at least one hole that is a first shape having a first area and a first orientation, and at least one hole that is a second shape having a second area and a second orientation, whereby at least one of the first shape, first area, and first orientation of the first shape differs from a corresponding second shape, second area, and second orientation of the second shape; walls, and adjacent holes in the pattern are separated from each other by one of the walls, each of the walls having a minimum width and extending along a path between the holes, so that it is not possible to identify a straight line, and so that the straight line has a constant width that is 75% of the minimum width of the wall; the straight line extends completely through at least three of the tiling cells; a wall, wherein the straight line is contained entirely within the boundary of the wall.

16. 16. The grille of claim 15, wherein the tiled cells are tiled in adjacent linear fashion.

17. The wall is configured such that it is not possible to distinguish three straight lines, whereby each straight line has a constant width that is 75% of the minimum width of the wall; Each line extends completely through at least three cells; each line is angled more than 30° away from each of the other two lines; 17. A grille as claimed in claim 15 or 16, wherein each straight line is contained entirely within the boundary of said wall.

18. 18. A grille according to any one of the preceding claims, wherein the tiled cells are tiled in adjacent straight lines, whereby the cells are staggered between adjacent lines.

19. 19. A grille as claimed in any one of the preceding claims, wherein the first shape has six-fold symmetry.

20. 20. The grille of any one of claims 1 to 19, wherein the first shape has at least three recessed areas, each of the recessed areas facing a corresponding raised area of ​​the second shape in the pattern.

21. 21. A grille according to any one of the preceding claims, wherein each cell comprises at least three holes.

22. 22. The grill of any one of claims 1 to 21, wherein the grill is made from a sheet of material having a thickness in the range of about 0.1 mm to about 2 mm.

23. 23. The grill of any one of claims 1 to 22, wherein the grill is made from a sheet of material having a thickness in the range of about 0.2 mm to about 1 mm.

24. 24. A grille according to any one of the preceding claims, having a maximum dimension of less than about 100mm.

25. 25. The grille of any one of claims 1 to 24, wherein the grille is dome-shaped, the center of the dome coinciding with the first shaped hole.

26. 26. The grille of any one of claims 1 to 25, wherein the holes of the first shape have a minimum diameter and a maximum diameter, the maximum diameter being no more than about 50% larger than the minimum diameter.

27. 27. The grille of any one of claims 1 to 26, wherein the holes of the first shape have a maximum diameter corresponding to a maximum radial distance from a center of the hole, and an outer periphery, at least about 20% of the length of the outer periphery being at a distance that is at least about 90% of the maximum radial distance from the center of the hole.

28. A grille according to any one of the preceding claims, wherein the grille is for a tweeter loudspeaker and has a diameter of between about 30 mm and about 100 mm.

29. 29. A method of making a loudspeaker grille, the method comprising bending or otherwise deforming a metal sheet to form a dome-shaped region, the metal sheet having a pattern of at least 20 holes formed therein, the pattern corresponding to the pattern of at least 20 holes of any one of claims 1 to 28.

30. 29. A loudspeaker drive unit fitted with a grille according to any one of claims 1 to 28.

31. 31. A loudspeaker drive unit according to claim 30, wherein the loudspeaker drive unit is a hi-fi tweeter drive unit.

32. 32. A hi-fi loudspeaker comprising a drive unit according to claim 30 or 31.

33. 32. A loudspeaker comprising a drive unit according to claim 30 or 31, the drive unit being a tweeter drive unit, the tweeter drive unit having its own body mounted on a separate enclosure of the loudspeaker, the enclosure housing one or more of a mid-range loudspeaker driver and a bass loudspeaker driver.

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