SURROUND ATTACHMENT

BACKGROUND OF THE INVENTION

[0001] The present invention relates to suspension systems for acoustic trai sducers and methods for the manufacture of same. More specifically, the invention relates the attachment of a surround to a diaphragm of an electro-acoustic transducer.

[0002] A surround provides support for an acoustic radiator as the acoustic adiator moves relative to a housing of an acoustic driver. A portion of the surround is attachei to the housing and a second portion of the surround is attached to the acoustic radiator. The s iτound is typically attached to the acoustic radiator by an adhesive applied to a lap joint, fhe repeated cyclic stress experienced by the joint can contribute to a premature failure of th lap joint. Therefore, there remains a need for improved methods of attaching a surround ) the acoustic radiator.

SUMMARY OF THE INVENTION

[0003] A mechanically interlocked acoustic radiator/surround assembly is c sclosed wherein an edge of the acoustic radiator includes a protrusion extending from and/or a c pression in a surface of the acoustic radiator. An elastomeric material is formed around the rotrusion and/or fills the depression forming an radiator/surround interface that is not parallel to he surface of the acoustic radiator.

[0004] One embodiment of the present invention is directed to an assembly comprising: an acoustic radiator having a first surface and an outer portion of the first surface,; ie outer portion having at least one protrusion extending from the first surface, the at least one i otrusion characterized by a protrusion surface; and a surround in contact with the outer nbrtion of the first surface forming a first interface, the surround in contact with the at least one pr trusion forming a second interface, wherein the second interface provides a mechanical interference in a radial direction. In some aspects, the protrusion may be a discrete structure such as, f r example, a

post. In some aspects, the protrusion may be a continuous ridge along an edge f the acoustic radiator. In a further aspect, the acoustic radiator further comprises a second s face opposite the first surface and at least one protrusion extending from the second surface, the t least one protrusion extending from the second surface in contact with the surround and arming a third interface with the surround, the third interface oriented non-parallel to the first nterface. In some aspects, the at least one protrusion extending from the second surface is < fferent from the at least one protrusion extending from the first surface. In some aspects, the ac iustic radiator further comprises a second surface opposite the first surface and at least one dc ression in the second surface, the at least one depression in contact with the surround and for ling a third interface with the surround, the third interface having a non-parallel orientatior to the first interface. In some aspects, the depression may be a discrete structure such as, >r example, a blind hole. In some aspects, the depression is a continuous groove along an ed e of the acoustic radiator.

[0005] Another embodiment of the present invention is directed to an assei bly comprising: an acoustic radiator having an outer portion, the outer portion having a first sui ice and a second surface; a surround in contact with the first and second surface of the outer por on of the acoustic radiator; and a first protrusion extending from the first surface of the i oustic radiator, the first protrusion in contact with the surround. In one aspect, the assembly ft ther comprises a second protrusion extending from the second surface of the acoustic radiator, tl : second protrusion in contact with the surround. In one aspect, the first protrusion is a DSt. In another aspect, the first protrusion is a ridge extending along an edge of the acoustic rai ator. In one aspect, the assembly further comprises a depression in the second surface filled >y the surround. In one aspect, the depression is a groove.

[0006] Another embodiment of the present invention is directed to an asser bly manufactured by a process comprising the steps of: providing an acoustic radiator having an iter portion and at least one protrusion extending laterally from a surface of the outer portion oi he acoustic radiator; placing the outer portion of the acoustic radiator in a mold, the mold c fining a cavity enclosing the outer portion of the acoustic radiator; introducing a thermoplastic elastomer into

invention;

may be circumferentially spaced around the acoustic radiator's perimeter.

may be placed at a different radial position within the outer portion of the aeon :ic radiator than the position shown in Fig. 3. In Fig. 4, the continuous ridge 415 runs along th< ϊdge of the acoustic radiator 410 and is part of the edge of the acoustic radiator.

[0027] Fig. 5 is a cross-sectional side view of another embodiment of the p ssent invention, In Fig. 5, the acoustic radiator 510 includes a positioning ridge 540 to assist ali nment of the acoustic radiator in a surround mold. The positioning ridge 540 may form a cc tinuous ridge on a face of the acoustic radiator. A second positioning ridge may be disposed on he opposite face of the acoustic radiator. The positioning ridge 540 is positioned inward from t : radiator's edge 550 and may be used to define the extent of the surround overlap over the outei portion of the acoustic radiator 510. At least one triangular ridge 530 is disposed on a face o he acoustic radiator between the positioning ridge 540 and the edge 550 of the acoustic rad Jtor 510. The triangular ridge 530 may form a continuous ridge around the circumference of e acoustic radiator. In other embodiments, the triangular ridge may be discontinuous and paced around the circumference of the acoustic radiator. The sides of the triangular ridge 530 pr vide non-parallel radiator/surround interface 535 when the surround is molded to the acoustic raSator 510.

[0028] Fig. 6 is a cross-sectional side view of another embodiment of the p jsent invention, In Fig. 6, a shoulder 660 in the acoustic radiator 610 may be used to position th acoustic radiator 610 in the surround mold and defines the extent of the surround overlap over t outer portion of the acoustic radiator 610. At least one protrusion 630 located in the outer porti n of the acoustic radiator 610 between the shoulder 660 and edge 650 provides a non-parallel in rface 635 to provide a mechanical interference between the acoustic radiator 610 and surrou ά 620.

[0029] A non-parallel interface may also be created using depressions or g >oves in the acoustic radiator. Fig. 7 is a cross-sectional side view of another embodiment ( the present invention. In Fig. 7, a mechanical interference between an acoustic radiator 71 and a surround 720 is created by a depression 730 in a face of the acoustic radiator 710. The c pression 730 is filled with the surround material during molding, creating a non-parallel interfa e 735. Depression 730 may be a continuous groove in an outer portion of the acoustiq idiator 710

extending circumferentially around the acoustic radiator 710. Depression 730 iay also include grooves that extend circumferentially over only a portion of the acoustic radiat r 710.

[0030] Fig. 8 is a cross-sectional side view of another embodiment of the p esent invention, Fig. 8 illustrates a combination of protrusions and depressions may be used to echanically interlock the surround to the acoustic radiator. In Fig. 8, the acoustic radiator 0 includes a protrusion 830 on a first surface of the acoustic radiator 810. The protrusion 8 0 may be a discrete structure such as, for example, a post. Alternatively, the protrusion m be a continuous ridge encircling the acoustic radiator 810. In Fig. 8, the acoustic radiator 810 i; eludes a depression 880 on a second surface of the acoustic radiator 810. Depression 8! ) may be a continuous circumferential groove encircling the acoustic radiator 810. Altem ively, depression 880 may be a discrete structure such as, for example, a blind hole. The non-pai illel interface 885 of the depression 880 may be oriented to the parallel interface 820 at a differen angle than the orientation of the non-parallel interface 835 of the protrusion 830.

[0031] Fig. 9 is an exploded perspective view of an embodiment of the pre :nt invention, Fig. 9 illustrates an example where the acoustic driver is a passive radiator am he acoustic radiator is a plate. In Fig. 9, an acoustic radiator 910 is attached to a surround 20 along the surround' s inner perimeter 923. The outer perimeter 927 of the surround 920 ii attached to a mounting ring 930. The mounting ring 930 enables the radiator/surround/ring > isembly to be formed in a separate manufacturing step before being attached to a housing 94(

[0032] The assembly may be formed by any of the manufacturing methods nown to the skilled artisan. For example, the assembly may be formed by first placing an o ter portion of the radiator and the outer ring in a mold having a cavity defining the surround. In )me embodiments, the outer portion of the acoustic radiator may be chemically or ri :chanically surface treated to promote material adhesion to the acoustic radiator. The sum ind is formed by flowing an elastomer, preferably a thermoplastic elastomer, into the mold and i owing the elastomer to set. The thermoplastic elastomer may any elastomeric material s able for the surround such as, for example, silicone rubber, polyurethane rubber, or fiber re forced rubber

composites. When the elastomer is flowed into the mold, the elastomer fills ai depressions in the surround and flows around any protrusions 915 in the surround to form int faces that serve to mechanically lock the surround to the radiator. After the elastomer sets, the ssembly may be attached to the housing 940 by, for example, ultrasonically welding the mounti g ring 930 to the housing 940. Alternative methods include pour casting into a mold using, for [ample, a two- part thermosetting elastomer.

[0033] Fig. 1 Oa illustrates the inner surface of a bottom portion of a two-p< t mold used to form the radiator/surround/ring assembly illustrated in Fig. 9. Fig. 10b illustra s the inner surface of a top portion of a two-part mold shown in Fig. 10a. In Fig. 10a, a fi t groove 1010 positions the acoustic radiator in the mold. A second groove 1020 positions th mounting ring in the mold. The top portion of the two-part mold is positioned over the bottom irtion to form a cavity 1030. An elastomeric material is flowed into the mold, filling the cavit) 1030 to form the surround. After setting the elastomeric material, the mold is struck and the radiator/surround/ring assembly is removed. The mold in Figs. 10a and 10b fo' n two assemblies per mold but molds capable of making any number of assemblies per mold are nderstood to be within the scope of the present invention.

[0034] Having thus described at least illustrative embodiments of the invei on, various modifications and improvements will readily occur to those skilled in the art at i are intended to be within the scope of the invention. For example, protrusions may have a uni rm or non- uniform height. The protrusions can have a variety of shapes. For example, a irtical cross- section of a protrusion may be symmetrical such as a rectangle, a triangle, or a apezoid, or may be asymmetrical such as a truncated right triangle. Similarly, a horizontal cros section of a protrusion, parallel to a surface of the outer portion of the acoustic radiator, ma be symmetrical such as a circle, a rectangle, a triangle, or a wedge or may be asymmetrical. A Otrusion having an azimuthal extent much greater than its radial extent is referred to herein as a idge wherein the terms azimuthal and radial refer to a cylindrical coordinate reference frame wh e the cylindrical axis is collinear with the acoustic radiator axis defining the reciprocal motion c the acoustic radiator relative to a housing of the acoustic transducer. A ridge may be a cont uous ridge that

extends completely around the acoustic radiator. A ridge may be discontinuoυ and circumfcrentially extend only a fraction of a full rotation about the acoustic rad ator axis, Placement of protrusions may be placed anywhere on the outer portion of the £ oustic radiator that is overlapped by the surround. For example, a spiral ridge may be formed y monotonically varying the radial position of the ridge as a function of the azimuthal position, t should be understood that the aforementioned examples illustrate some of the many confi durations that would occur to a skilled artisan reading this disclosure and is not intended to 1! liitt the scope of the present invention.

[0035] Accordingly, the foregoing description is by way of example only a d is not intended as limiting. The invention is limited only as defined in the following claims ai the equivalents thereto.