Abstract:
A method for manufacturing a loudspeaker includes creating a dual-layered fabric having an acoustic resistance by attaching a first fabric having a first acoustic resistance to a second fabric having a second acoustic resistance lower than the first acoustic resistance. The method further includes applying a coating material to a first portion of the dual-layered fabric. The coating material forms a pattern on the first portion of the dual-layered fabric that changes the acoustic resistance of the dual-layered fabric along at least one of: a length and radius of the dual-layered fabric.

Description:
BACKGROUND 
       [0001]    This disclosure relates to a method for manufacturing a loudspeaker. 
         [0002]    Loudspeakers generally include a diaphragm and a linear motor. When driven by an electrical input signal, the linear motor moves the diaphragm to cause vibrations in air, thereby generating sound. Various techniques have been used to control the directivity and radiation pattern of a loudspeaker, including acoustic horns, pipes, slots, waveguides, and other structures that redirect or guide the generated sound waves. In some of these structures, an opening in the horn, pipe, slot or waveguide is covered with an acoustically resistive material to improve the performance of the loudspeaker over a wider range of frequencies. 
       SUMMARY 
       [0003]    In general, in some aspects a method for manufacturing a loudspeaker includes creating a dual-layered fabric having an acoustic resistance by attaching a first fabric having a first acoustic resistance to a second fabric having a second acoustic resistance lower than the first acoustic resistance. The method further includes applying a coating material to a first portion of the dual-layered fabric. The coating material forms a pattern on the first portion of the dual-layered fabric that changes the acoustic resistance of the dual-layered fabric along at least one of: a length and radius of the dual-layered fabric. 
         [0004]    Implementations may include any, all or none of the following features. The first acoustic resistance may be approximately 1,000 Rayls. The first fabric may be a monofilament fabric. The second fabric may be a monofilament fabric. The first fabric may be attached to the second fabric using at least one of: a solvent and an adhesive. 
         [0005]    Applying a coating material to a first portion of the dual-layered fabric may include masking a second portion of the dual-layered fabric, the second portion being adjacent to the first portion. Applying a coating material to a first portion of the dual-layered fabric may further include applying the coating material to an unmasked portion of the dual-layered fabric. Applying a coating material to a first portion of the dual-layered fabric may include selectively depositing the coating material to form the pattern on the first portion of the dual-layered fabric. Applying a coating material to a first portion of the dual-layered fabric may include attaching a pre-cut sheet of material to the first portion of the dual-layered fabric. The coating material may include at least one of: paint, an adhesive, and a polymer. 
         [0006]    The method may further include thermoforming the dual-layered fabric into at least one of: a spherical shape, a semi-spherical shape, a conical shape, a toroidal shape, and a shape comprising a section of a sphere, cone or toroid. 
         [0007]    The method may further include attaching the dual-layered fabric to an acoustic waveguide. 
         [0008]    The method may further include attaching an electro-acoustic driver to the acoustic waveguide. 
         [0009]    In general, in some aspects a method of manufacturing a loudspeaker includes providing a fabric having an acoustic resistance and applying a coating material to a first portion of the fabric. The coating material forms a pattern on the first portion of the fabric that changes the acoustic resistance of the fabric along at least one of: a length and radius of the fabric. 
         [0010]    Implementations may include any, all or none of the following features. The acoustic resistance may be approximately 1,000 Rayls. The fabric may include a monofilament fabric. 
         [0011]    Applying a coating material to a first portion of the fabric may include masking a second portion of the fabric, the second portion being adjacent to the first portion. Applying a coating material to a first portion of the fabric may further include applying the coating material to an unmasked portion of the fabric. Applying a coating material to a first portion of the fabric may include selectively depositing the coating material to form the pattern on the first portion of the fabric. Applying a coating material to a first portion of the fabric may include attaching a pre-cut sheet of material to the first portion of the fabric. The coating material may include at least one of: paint, an adhesive, and a polymer. 
         [0012]    The method may further include thermoforming the fabric into at least one of: a spherical shape, a semi-spherical shape, a conical shape, a toroidal shape, and a shape comprising a section of a sphere, cone or toroid. 
         [0013]    The method may further include attaching the fabric to an acoustic waveguide. 
         [0014]    The method may further include attaching an electro-acoustic driver to the acoustic waveguide. 
         [0015]    In general, in some aspects a method of manufacturing a loudspeaker includes creating a dual-layered fabric having an acoustic resistance by attaching a first fabric having a first acoustic resistance to a second fabric having a second acoustic resistance lower than the first resistance. The method further includes altering the acoustic resistance of the dual-layered fabric along at least one of: a length and radius of the dual-layered fabric by fusing a first portion of the dual-layered fabric to form a substantially opaque pattern on the first portion of the dual-layered fabric. 
         [0016]    Implementations may include any, all or none of the following features. The first acoustic resistance may be approximately 1,000 Rayls. The first fabric and the second fabric may each include a monofilament fabric. The first fabric may be attached to the second fabric using at least one of: a solvent and an adhesive. Fusing a first portion of the dual-layered fabric may include heating the dual-layered fabric. 
         [0017]    The method may further include thermoforming the dual-layered fabric into at least one of: a spherical shape, a semi-spherical shape, a conical shape, a toroidal shape, and a shape comprising a section of a sphere, cone or toroid. 
         [0018]    The method may further include attaching the dual-layered fabric to an acoustic waveguide. 
         [0019]    The method may further include attaching an electro-acoustic driver to the acoustic waveguide. 
         [0020]    Implementations may include one of the above and/or below features, or any combination thereof. Other features and advantages will be apparent from the description and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    For purposes of illustration some elements are omitted and some dimensions are exaggerated. For ease of reference, like reference numbers indicate like features throughout the referenced drawings. 
           [0022]      FIG. 1A  is perspective view of a loudspeaker. 
           [0023]      FIG. 1B  is front view of the loudspeaker of  FIG. 1A . 
           [0024]      FIG. 1C  is a back view of the loudspeaker of  FIG. 1A . 
           [0025]      FIG. 2  shows a flow chart of a method for manufacturing the loudspeaker of  FIGS. 1A through 1C . 
           [0026]      FIG. 3  shows a flow chart of an alternative method for manufacturing the loudspeaker of  FIGS. 1A through 1C . 
           [0027]      FIG. 4  shows a flow chart of an alternative method for manufacturing the loudspeaker of  FIGS. 1A through 1C . 
           [0028]      FIG. 5  shows a flow chart of an alternative method for manufacturing the loudspeaker of  FIGS. 1A through 1C   
           [0029]      FIG. 6  shows a flow chart of a step that may be used in the methods for manufacturing shown in  FIGS. 2 and 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    A loudspeaker  10 , shown in  FIGS. 1A through 1C , includes an electro-acoustic driver  12  coupled to an acoustic waveguide  14 . The acoustic waveguide  14  is coupled to a resistive screen  16 , on which an acoustically resistive pattern  20  is applied. The acoustically resistive pattern  20  may be a substantially opaque and impervious layer that is applied to or generated on the resistive screen  16 . The electro-acoustic driver  12 , acoustic waveguide  14 , and resistive screen  16  together may be mounted onto a base section  18 . The base section  18  may be formed integrally with the acoustic waveguide  14  or may be formed separately. The loudspeaker  10  may also include a plurality of mounting holes  22  for mounting the loudspeaker  10  in, for example, a ceiling, wall, or other structure. One such loudspeaker  10  is described in U.S. patent application ______, titled “Directional Acoustic Device” filed on Mar. 31, 2015, the entire contents of which are incorporated herein by reference. 
         [0031]    The electro-acoustic driver  12  typically includes a motor structure mechanically coupled to a radiating component, such as a diaphragm, cone, dome, or other surface. Attached to the inner edge of the cone may be a dust cover or dust cap, which also may be dome-shaped. In operation, the motor structure operates as a linear motor, causing the radiating surface to vibrate along an axis of motion. This movement causes changes in air pressure, which results in the production of sound. The electro-acoustic driver  12  may be a mid-high or high frequency driver, typically having an operating range of 200 Hz to 16 kHz. The electro-acoustic driver  12  may be of numerous types, including but not limited to a compression driver, cone driver, mid-range driver, full-range driver, and tweeter. Although one electro-acoustic driver is shown in  FIGS. 1A through 1C , any number of drivers could be used. In addition, the one or more electro-acoustic drivers  12  could be coupled to the acoustic waveguide  14  via an acoustic passage or manifold component, such as those described in U.S. Patent Publication No. 2011-0064247, the entire contents of which are incorporated herein by reference. 
         [0032]    The electro-acoustic driver  12  is coupled to an acoustic waveguide  14  which, in the example of  FIGS. 1A through 1C , guides the generated sound waves in a radial direction away from the electro-acoustic driver  12 . The loudspeaker  10  could be any number of shapes, including but not limited to circular, semi-circular, spherical, semi-spherical, conical, semi-conical, toroidal, semi-toroidal, rectangular, and a shape comprising a section of a circle, sphere, cone, or toroid. In examples where the loudspeaker  10  has a non-circular or non-spherical shape, the acoustic waveguide  14  guides the generated sound waves in a direction away from the electro-acoustic driver  12 . The acoustic waveguide  14  may be constructed of a metal or plastic material, including but not limited to thermoset polymers and thermoplastic polymer resins such as polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE). Moreover, fibers of various materials, including fiberglass, may be added to the polymer material for increased strength and durability. The acoustic waveguide  14  could have a substantially solid structure, as shown in  FIGS. 1A through 1C , or could have hollow portions, for example a honeycomb structure. 
         [0033]    Before the generated sound waves reach the external environment, they pass through a resistive screen  16  coupled to an opening in the acoustic waveguide  14 . The resistive screen  16  may include one or more layers of a mesh material or fabric. In some examples, the one or more layers of material or fabric may each be made of monofilament fabric (i.e., a fabric made of a fiber that has only one filament, so that the filament and fiber coincide). The fabric may be made of polyester, though other materials could be used, including but not limited to metal, cotton, nylon, acrylic, rayon, polymers, aramids, fiber composites, and/or natural and synthetic materials having the same, similar, or related properties, or a combination thereof. In other examples, a multifilament fabric may be used for one or more of the layers of fabric. 
         [0034]    In one example, the resistive screen  16  is made of two layers of fabric, one layer being made of a fabric having a relatively high acoustic resistance compared to the second layer. For example, the first fabric may have an acoustic resistance ranging from 200 to 2,000 Rayls, while the second fabric may have an acoustic resistance ranging from 1 to 90 Rayls. The second layer may be a fabric made of a coarse mesh to provide structural integrity to the resistive screen  16 , and to prevent movement of the screen at high sound pressure levels. In one example, the first fabric is a polyester-based fabric having an acoustic resistance of approximately 1,000 Rayls (e.g., Saatifil® Polyester PES 10/3 supplied by Saati of Milan, Italy) and the second fabric is a polyester-based fabric made of a coarse mesh (e.g., Saatifil® Polyester PES 42/10 also supplied by Saati of Milan, Italy). In other examples, however, other materials may be used. In addition, the resistive screen  16  may be made of a single layer of fabric or material, such as a metal-based mesh or a polyester-based fabric. And in still other examples, the resistive screen  16  may be made of more than two layers of material or fabric. The resistive screen  16  may also include a hydrophobic coating to make the screen water-resistant. 
         [0035]    The resistive screen  16  also includes an acoustically resistive pattern  20  that is applied to or generated on the surface of the resistive screen  16 . The acoustically resistive pattern  20  may be a substantially opaque and impervious layer. Thus, in the places where the acoustically resistive pattern  20  is applied, it substantially blocks the holes in the mesh material or fabric, thereby creating an acoustic resistance that varies as the generated sound waves move radially outward through the resistive screen  16  (or outward in a linear direction for non-circular and non-spherical shapes). For example, where the acoustic resistance of the resistive screen  16  without the acoustically resistive pattern  20  is approximately 1,000 Rayls over a prescribed area, the acoustic resistance of the resistive screen  16  with the acoustically resistive pattern  20  may be approximately 10,000 Rayls over an area closer to the electro-acoustic driver  12 , and approximately 1,000 Rayls over an area closer to the edge of the loudspeaker  10  (e.g., in areas that do not include the acoustically resistive pattern  20 ). The size, shape, and thickness of the acoustically resistive pattern  20  may vary, and just one example is shown in  FIGS. 1A through 1C . 
         [0036]    The material used to generate the acoustically resistive pattern  20  may vary depending on the material or fabric used for the resistive screen  16 . In the example where the resistive screen  16  comprises a polyester fabric, the material used to generate the acoustically resistive pattern  20  may be paint (e.g., vinyl paint), or some other coating material that is compatible with polyester fabric. In other examples, the material used to generate the acoustically resistive pattern  20  may be an adhesive or a polymer. In still other examples, rather than add a coating material to the resistive screen  16 , the acoustically resistive pattern  20  may be generated by transforming the material comprising the resistive screen  16 , for example by heating the resistive screen  16  to selectively fuse the intersections of the mesh material or fabric, thereby substantially blocking the holes in the material or fabric. 
         [0037]      FIG. 2  shows a flow chart of a method  100  for manufacturing the loudspeaker  10  of  FIGS. 1A through 1C  in the example where the resistive screen  16  is made of two layers of fabric, and a coating material is applied to the resistive screen  16  to form the acoustically resistive pattern  20 . Although steps  102 - 112  of  FIG. 2  are shown as occurring in a certain order, it should be readily understood that the steps  102 - 112  could occur in a different order than is shown. Moreover, although steps  102 - 112  of  FIG. 2  are shown as occurring separately, it should be readily understood that certain of the steps could be combined and occur at the same time. As shown in  FIG. 2 , to begin formation of the resistive screen  16 , a first fabric is attached to a second fabric in step  102 . The two fabrics may be attached by, for example, using a layer of solvent, adhesive, or glue that joins the two layers of fabric. Alternatively, the fabrics may be heated to a temperature that permits the two fabrics to be joined to each other. For example, the fabrics may be placed in mold that heats the fabrics to a predetermined temperature for a predetermined length of time until the fabrics adhere to each other, or a laser (or other heat-applying apparatus) may be used to selectively apply heat to portions of the fabrics until those portions adhere to each other. Alternatively, the fabrics could be joined by thermoforming, pressure forming and/or vacuum forming the fabrics. 
         [0038]    In step  104 , a coating material (such as paint, an adhesive or a polymer) is applied to the resistive screen  16  to form the acoustically resistive pattern  20 . In one example, as shown in  FIG. 6 , the coating material could be applied using a mask. In that example, a portion of the fabric could be masked (in step  120 ), and the coating material could be applied to the unmasked portion of the fabric (in step  122 ), by, for example, spraying or otherwise depositing the coating material onto the unmasked portion of the fabric. In some examples, after the mask has been applied, a coating material (e.g., adhesive beads or polymer beads) could be deposited on the unmasked portion of the fabric, and then melted onto the fabric via the application of heat. The coating material could be applied to the resistive screen  16  using other methods besides a mask, however. For example, the coating material could be pre-cut (for example, using a laser cutter or die cutter), and could then be ironed-on to the fabric or attached using an adhesive. For example, the coating material could comprise a sheet of polymer plastic, metal, paper, or any substantially opaque material having the same, similar, or related properties (or any combination thereof) that is pre-cut into the desired acoustically resistive pattern  20 . The sheet could then be attached to the fabric via the application of heat or an adhesive. In yet another example, the coating material could be deposited directly onto the fabric, using a machine that can draw out the desired pattern  20 , thereby selectively applying the coating material only to the portion of the fabric that should have the acoustically resistive pattern  20 . In addition, the coating material could be applied to the resistive screen  16  using other known methods, including but not limited to a silkscreen, spray paint, ink jet printing, etching, melting, electrostatic coating, or any combination thereof. 
         [0039]    Optionally, in step  106 , the coating material may be cured, by, for example, baking the assembly at a predetermined temperature, applying ultraviolet (UV) light to the coating material, exposing the coating material to the air, or any combination thereof. If a coating material is selected that does not need to be cured, step  106  would be omitted. In some examples, steps  102 ,  104  and  106  could be combined into a single step. For example, the first and second layers of fabric could be placed on top of each other, and a UV-curable adhesive could be deposited onto one layer of the fabric in the desired acoustically resistive pattern  20 . The adhesive could then be cured via the application of UV light, which would also result in adhering the two layers of fabric. 
         [0040]    In step  108 , the fabric is formed into the desired shape for the loudspeaker  10 . For example, the fabric may be formed to be a semi-circle, circle, sphere, semi-sphere, rectangle, cone, toroid, or a shape comprising a section of a circle, sphere, cone, toroid and/or rectangle. The loudspeaker  10  may also be bent and/or curved along its length, as described, for example, in U.S. Pat. No. 8,351,630, the entire contents of which are incorporated herein by reference. These various shapes may be created by thermoforming the fabric (i.e., heating it to a pliable forming temperature and then forming it to a specific shape in a mold) and/or vacuum or pressure forming the fabric. Although  FIG. 2  shows step  108  as occurring after the coating material has been applied to the resistive screen  16 , in other examples, the fabric could be formed into the desired shape before the coating material is applied. Moreover, step  108  could be combined with step  102 , so that the forming process also joins the two layers of fabric. 
         [0041]    In step  110 , the resistive screen  16  is attached to the acoustic waveguide  14  via an adhesive, double-sided tape, a fastener (e.g., a screw, bolt, clamp, clasp, clip, pin or rivet), or other known methods. And in step  112 , the electro-acoustic driver  12  is attached to the acoustic waveguide  14 . The electro-acoustic driver  12  could be secured to the acoustic waveguide  14  via a fastener or other known methods. Although  FIG. 2  shows step  112  as occurring after the fabric has been attached to the acoustic waveguide, in other examples, the electro-acoustic transducer could be attached to the waveguide before the fabric is attached. The acoustic waveguide  14  could be constructed via compression molding, injection molding, plastic machining, or other known methods. 
         [0042]      FIG. 3  shows a flow chart of an alternative method  200  for manufacturing the loudspeaker  10  of  FIGS. 1A through 1C  in the example where the resistive screen  16  is made of a single layer of fabric, and a coating material is applied to the resistive screen  16  to form the acoustically resistive pattern  20 . Although steps  201 - 212  of  FIG. 3  are shown as occurring in a certain order, it should be readily understood that the steps  201 - 212  could occur in a different order than is shown. Moreover, although steps  201 - 212  of  FIG. 2  are shown as occurring separately, it should be readily understood that certain of the steps could be combined and occur at the same time. As shown in  FIG. 3 , to begin formation of the resistive screen  16 , a fabric is provided in step  201 . In step  204 , a coating material (such as paint, an adhesive or a polymer) is applied to the fabric to form the acoustically resistive pattern  20 . The coating material could be applied using the methods previously described in connection with  FIG. 2  (e.g., via a mask, a pre-cut sheet of material, by depositing the coating material directly onto the fabric in the desired pattern  20 , or via a silkscreen, spray paint, ink jet printing, etching, melting, electrostatic coating, or any combination thereof). 
         [0043]    Optionally, in step  206 , the coating material may be cured, by, for example, the methods previously described in connection with  FIG. 2  (e.g., baking the assembly at a predetermined temperature, applying UV light to the coating material, exposing the coating material to the air, or any combination thereof). If a coating material is selected that does not need to be cured, step  206  would be omitted. As with the example shown in  FIG. 2 , steps  201 ,  204  and  206  could be combined into a single step. 
         [0044]    In step  208 , the fabric is formed into the desired shape for the loudspeaker  10 . As with the example of  FIG. 2 , the fabric may be formed to be a semi-circle, circle, sphere, semi-sphere, rectangle, cone, toroid, or a shape comprising a section of a circle, sphere, cone, toroid and/or rectangle. The loudspeaker  10  may also be bent and/or curved along its length, as described, for example, in U.S. Pat. No. 8,351,630. These various shapes may be created by thermoforming the fabric (i.e., heating it to a pliable forming temperature and then forming it to a specific shape in a mold) and/or vacuum or pressure forming the fabric. Although  FIG. 3  shows step  208  as occurring after the coating material has been applied to the resistive screen  16 , in other examples, the fabric could be formed into the desired shape before the coating material is applied. 
         [0045]    As with the example of  FIG. 2 , in step  210 , the resistive screen  16  is attached to the acoustic waveguide  14  via an adhesive, double-sided tape, a fastener (e.g., a screw, bolt, clamp, clasp, clip, pin or rivet) or other known methods; and in step  212 , the electro-acoustic driver  12  is attached to the acoustic waveguide  14  via a fastener or other known methods. Although  FIG. 3  shows step  212  as occurring after the fabric has been attached to the acoustic waveguide, in other examples, the electro-acoustic transducer could be attached to the waveguide before the fabric is attached. As with the example of  FIG. 2 , the acoustic waveguide  14  could be constructed via compression molding, injection molding, plastic machining, or other known methods. 
         [0046]      FIG. 4  shows a flow chart of an alternative method  300  for manufacturing the loudspeaker  10  of  FIGS. 1A through 1C  in the example where the resistive screen  16  is made of two layers of fabric, and the acoustically resistive pattern  20  is formed by fusing the intersections of the fabric, thereby substantially blocking the holes in the fabric. Although steps  302 - 312  of  FIG. 4  are shown as occurring in a certain order, it should be readily understood that the steps  302 - 312  could occur in a different order than is shown. Moreover, although steps  302 - 312  of  FIG. 4  are shown as occurring separately, it should be readily understood that certain of the steps could be combined and occur at the same time. As shown in  FIG. 4 , to begin formation of the resistive screen  16 , a first fabric is attached to a second fabric in step  302 . The first fabric could be attached to the second fabric using the methods previously described in connection with  FIG. 2  (e.g., via a layer of solvent, adhesive or glue, or via heating, thermoforming, pressure forming, vacuum forming, or any combination thereof). 
         [0047]    In step  303 , the fabric is fused to form the acoustically resistive pattern  20 , such that the holes in the fabric are substantially blocked, thereby creating a substantially opaque and impervious layer on the fabric. The fabric could be fused by, for example, applying heat to the portions of the fabric that should have the acoustically resistive pattern  20 , or by selectively applying chemical bonding elements to the portions of the fabric that should have the acoustically resistive pattern  20 . 
         [0048]    As with the examples of  FIGS. 2 and 3 , in step  308 , the fabric is formed into the desired shape for the loudspeaker  10  (e.g., via thermoforming, vacuum forming and/or pressure forming); in step  310 , the resistive screen  16  is attached to the acoustic waveguide  14 ; and in step  312 , the electro-acoustic driver  12  is attached to the acoustic waveguide  14 . These steps could be completed using the methods previously described in connection with  FIGS. 2 and 3 . 
         [0049]      FIG. 5  shows a flow chart of an alternative method  400  for manufacturing the loudspeaker  10  of  FIGS. 1A through 1C  in the example where the resistive screen  16  is made of a single layer of fabric, and the acoustically resistive pattern  20  is formed by fusing the intersections of the fabric, thereby substantially blocking the holes in the fabric. Although steps  401 - 412  of  FIG. 5  are shown as occurring in a certain order, it should be readily understood that the steps  401 - 412  could occur in a different order than is shown. Moreover, although steps  401 - 412  of  FIG. 5  are shown as occurring separately, it should be readily understood that certain of the steps could be combined and occur at the same time. As shown in  FIG. 5 , to begin formation of the resistive screen  16 , a fabric is provided in step  401 . 
         [0050]    In step  403 , the fabric is fused to form the acoustically resistive pattern  20 , such that the holes in the fabric are substantially blocked, thereby creating a substantially opaque and impervious layer on the fabric. The fabric could be fused by, for example, applying heat to the portions of the fabric that should have the acoustically resistive pattern  20 , or by selectively applying chemical bonding elements to the portions of the fabric that should have the acoustically resistive pattern  20 . 
         [0051]    As with the examples of  FIGS. 2 through 4 , in step  408 , the fabric is formed into the desired shape for the loudspeaker  10  (e.g., via thermoforming, vacuum forming and/or pressure forming); in step  410 , the resistive screen  16  is attached to the acoustic waveguide  14 ; and in step  412 , the electro-acoustic driver  12  is attached to the acoustic waveguide  14 . These steps could be completed using the methods previously described in connection with  FIGS. 2 through 4 . 
         [0052]    A number of implementations have been described. Nevertheless, it will be understood that additional modifications may be made without departing from the scope of the inventive concepts described herein, and, accordingly, other embodiments are within the scope of the following claims.