Patent Description:
According to the present invention, a ported speaker assembly including an outer enclosure having a front opening is provided as defined by independent claim <NUM>. An inner frame of the speaker assembly is positioned at least partially within the outer enclosure and has an outer perimeter portion proximate the front opening of the outer enclosure. A resonator chamber is defined between an interior of the outer enclosure and an exterior of the inner frame. At least one speaker driver is mounted to the inner frame and configured to emit sound from a front end of the ported speaker assembly. A perimeter port is formed between the outer perimeter portion of the inner frame and the front opening of the outer enclosure to establish sound wave communication between the resonator chamber and a surrounding external atmosphere for tuned-frequency resonance output. The perimeter port extends uninterrupted about the outer perimeter edge of the inner frame so as to encircle the outer perimeter edge. A plurality of fastener joints secure the inner frame to the outer enclosure,
and at least some of the plurality of fastener joints are distributed around multiple sides of the inner frame and positioned closer to the front opening of the outer enclosure than a rear end of the inner frame. Each of the plurality of fastener joints includes a thread fastener, a washer, a clearance hole for receiving the thread fastener, and a nut portion for engaging the threaded fastener. The plurality of fastener joints are configured to absorb all assembly tolerance between the outer enclosure and the inner frame such that the tolerances on the overall dimensions of the speaker assembly are determined by the outer enclosure alone.

According to the present invention, a method of assembling a speaker assembly is provided as defined by independent claim <NUM>. An outer enclosure is provided having a front opening, and an inner frame is provided having an outer perimeter portion with a shape that corresponds to that of the front opening and a size that is smaller than that of the front opening. At least one speaker driver is assembled to the inner frame with the inner frame removed from the outer enclosure. The inner frame with the at least one mounted speaker driver is inserted into the outer enclosure through the front opening thereof to form a perimeter port between the outer perimeter portion of the inner frame and the front opening of the outer enclosure and to define a resonator chamber between an interior of the outer enclosure and an exterior of the inner frame. All assembly tolerance between the inner frame and the outer enclosure is absorbed through a plurality of fastener joints that are secured between the inner frame and the outer enclosure. Each of the plurality of fastener joints includes a thread fastener, a washer, a clearance hole for receiving the thread fastener, and a nut portion for engaging the threaded fastener.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings.

A ported speaker assembly <NUM> is illustrated in <FIG>. The illustrated speaker assembly <NUM> is a multi-driver horn-loaded loudspeaker, although alternate configurations are optional while retaining other aspects of the present disclosure. As shown in <FIG>, the speaker assembly <NUM> includes an outer shell or enclosure <NUM> and an inner frame <NUM> positioned at least partially within the outer enclosure <NUM>. In some constructions, one or both of the outer enclosure <NUM> and the inner frame <NUM> are constructed of wood (e.g., solid wood, manufactured wood, or particle board), and may be constructed of a plurality of wood pieces glued and/or fastened together. The inner frame <NUM> of the illustrated construction forms an acoustic horn. As shown in <FIG>, the outer enclosure <NUM> defines a front opening <NUM> leading to an internal resonator chamber <NUM> that cooperates with a port <NUM> to form a tuned-frequency resonator system (or so-called "bass reflex" system). As will be appreciated by those of skill in the art, the tuned-frequency resonator system is an acoustic example theoretically following the model of a mechanical spring-mass system in which the resonator chamber <NUM> has a prescribed air volume that correlates to spring stiffness, while the mass is represented by the configuration of the port <NUM>, in particular decreasing with increasing cross-section area and increasing with increasing length. The inner frame <NUM> has an outer perimeter portion proximate the front opening <NUM> of the outer enclosure <NUM>. For example, a front edge <NUM> of the inner frame <NUM> may constitute the outer perimeter portion, positioned directly within the front opening <NUM> of the outer enclosure <NUM>. However, alternate constructions are envisioned, particularly where the front edge <NUM> extends out forward of the front opening <NUM> or is recessed therefrom. The shape of the perimeter portion of the inner frame <NUM> corresponds to that of the front opening <NUM>, although it is smaller. As described in further detail below, the port <NUM> is a perimeter port <NUM> formed between the outer perimeter portion (e.g., front edge <NUM> as shown) of the inner frame <NUM> and the front opening <NUM> of the outer enclosure <NUM>. The perimeter port <NUM> provides sound wave communication between the internal resonator chamber <NUM> and the surrounding external atmosphere. The perimeter port <NUM> extends uninterrupted about the outer perimeter of the inner frame <NUM> so as to encircle it. The perimeter port <NUM> has a rectangular shape in front view, owing to the rectangular cross-sections of both the front opening <NUM> and the outer perimeter portion of the inner frame <NUM>. A front grille <NUM> (<FIG>, shown with partial breakaway) constructed of mesh, screen, fabric, perforated sheeting or another suitable material is positioned at the front end of the speaker assembly <NUM> and may be secured at the front opening <NUM>.

The speaker assembly <NUM> includes at least one speaker driver 48A, 48B mounted to the inner frame <NUM> and configured to emit sound from the front end of the speaker assembly <NUM>. The speaker assembly <NUM>, and particularly the inner frame <NUM>, can define a central axis for sound projection that is directly out of the page as viewed in the front view of <FIG>. The illustrated inner frame <NUM> forms an acoustic horn for precisely controlling the directivity of a wide frequency range of sound. The inner frame <NUM> can thus include a primary flare or cone portion 28A and a secondary flare or cone portion 28B further forward and extending to the front edge <NUM>. A plurality of speaker drivers 48A, 48B supported by the illustrated inner frame <NUM> includes drivers (i.e., electrodynamic audio transducers) of different types, varying by frequency output. For example, the speaker assembly <NUM> includes a plurality (e.g., two) of high frequency drivers 48A and a plurality (e.g., four) of low frequency drivers 48B. As can be seen in <FIG> and <FIG>, the low frequency drivers 48B can be distributed around multiple sides of the inner frame <NUM>, for example on all four sides about the central axis. Openings <NUM> through the inner frame <NUM> are provided at the locations of the low frequency drivers 48B so as to enable sound transmission from an outside of the inner frame <NUM> (within the resonator chamber <NUM>) to an inside of the inner frame <NUM>. The low frequency drivers 48B are positioned farther forward than the high frequency drivers 48A, which are coupled to the rear end or rear panel <NUM> of the inner frame <NUM>. Although not required in all embodiments, the rear of inner frame <NUM> includes an elongate slot opening <NUM> (<FIG>) forming a horn inlet to which the high frequency drivers 48A are coupled through a wave guide <NUM>.

The inner frame rear panel <NUM> is attached to a transverse panel <NUM> of the outer enclosure <NUM>. The transverse panel <NUM> defines a rear end of the resonator chamber <NUM>, and as shown can be positioned forward of a rearmost outer panel <NUM> of the outer enclosure <NUM>. The transverse panel <NUM> can include an opening through which the high frequency drivers 48A and the wave guide <NUM> can be passed, from front to rear, during assembly. Between the transverse panel <NUM> and the rearmost outer panel <NUM>, the wave guide <NUM> and high frequency drivers 48A can be accommodated in a chamber divided from and acoustically sealed from the resonator chamber <NUM>. Attachment between the outer enclosure <NUM> and the inner frame <NUM> is made by a plurality of fastener joints, including forward and rearward fastener joints 70A, 70B. At least some of the forward fastener joints 70A are distributed around multiple sides of the inner frame <NUM> and positioned closer to the front opening <NUM> of the outer enclosure than a rear end of the inner frame <NUM>, e.g., rear panel <NUM>. The forward fastener joints 70A are positioned within the frontal <NUM> percent of the inner frame front-rear depth, or within the frontal <NUM> percent thereof, in some constructions. The forward fastener joints 70A can be provided in an arrangement of two per side (top, bottom, left, and right sides) for a total of eight. The forward fastener joints 70A can be partially or fully recessed in an interior surface of the inner frame <NUM>. Unlike the forward fastener joints 70A, the rearward fastener joints 70B all secure along parallel axes (e.g., front-rear). While the forward fastener joints 70A are accessible for assembly from the interior of the inner frame <NUM> (e.g., the acoustic horn surface), the rearward fastener joints 70B are accessible for assembly through one or more access ports <NUM> in the outer enclosure <NUM>, rearward of the resonator chamber <NUM>. The access ports <NUM> can be closed with removable panels upon final assembly and operation. In contrast, the resonator chamber <NUM> in which the speaker drivers 48B are positioned may be completely devoid of removable panels and access ports around the side walls of the outer enclosure <NUM>.

In some constructions, the fastener placement is selected to minimize unwanted panel vibration and resonance in either or both of the inner frame <NUM> and the outer enclosure <NUM>. For example, placing some or all of the fastener joints 70A, 70B at antinodes of the natural panel resonances minimizes the extent to which they can be excited. There are varying degrees of optimization which can be done in this regard, including in some cases FEA simulation-based optimization.

The overall envelope of the speaker assembly <NUM> can be quite large in some constructions, for example at least <NUM> liters in volume, and in some cases <NUM> liters or more in volume. Thus, it follows that the outer enclosure <NUM> and the inner frame <NUM> are quite large, and with the numerous fastener joints 70A, 70B, may introduce a significant amount of tolerance stack-up, especially when one or both of the outer enclosure <NUM> and the inner frame <NUM> are constructed of wood as opposed to precision-molded plastics. However, because the perimeter port <NUM> is formed between the outer perimeter portion of the inner frame <NUM> and the front opening <NUM> of the outer enclosure <NUM>, assembly tolerances that may affect the placement (even if significantly off-center) of the inner frame <NUM> in the front opening <NUM> do not affect the performance of the speaker assembly <NUM>, vis-à-vis the bass-reflex porting provided by the port <NUM>. The performance is a function of the total cross-section area of the port <NUM> and the volume of the resonator chamber <NUM>, regardless of the shape or layout of the port <NUM>. As a result, any shifting to one side that reduces port area simultaneously results in increasing the port area on the opposite side. The perimeter port <NUM> also maximizes space efficiency for the given port and inner frame sizing by not requiring an entire offsetting of the inner frame <NUM> in the front opening <NUM> to make room for a designated port location (e.g., conventional circular port).

The fastener joints 70A, 70B are configured to absorb the assembly tolerance between the outer enclosure <NUM> and the inner frame <NUM>. The tolerances on the overall dimensions of the speaker assembly <NUM> are determined only by the pieces in the outer enclosure <NUM>. The inner frame <NUM> has its own tolerances, and the tolerance stack-up is taken up by the fastener joints 70A, 70B that mount the two together. Because the performance of the resonator chamber <NUM> is not dependent upon a precise placement of the inner frame <NUM> within the front opening <NUM>, this is advantageously leveraged in order to preclude the need to hold very strict tolerances for assembly of the inner frame <NUM> to the outer enclosure <NUM>. This is accomplished through the fastener joints 70A, 70B, each of which includes a threaded fastener <NUM>, a washer <NUM>, a clearance hole <NUM> for receiving the threaded fastener <NUM>, and a nut portion <NUM> for engaging the threaded fastener <NUM>. The threaded fasteners <NUM> can be of a relatively large size (e.g., M8, M10 or larger). As best shown in <FIG> and <FIG>, the nut portions <NUM> can be formed as part of an angle bracket in the case of the forward fastener joints 70A, and can be formed as T-nuts in the case of the rearward fastener joints 70B. However, the nut portions <NUM> can be formed in a variety of ways in alternate constructions, for example, spring nuts, speed nuts, self-clinching nuts, locking nuts, or in some cases conventional nuts. The angle brackets at the forward fastener joints 70A can be secured to structural ribbing <NUM> protruding inward from the inner wall surface of the outer enclosure <NUM>. As shown in <FIG> and <FIG>, similar structural ribbing <NUM> can be provided to protrude outward from the outer wall surface of the inner frame <NUM>. The respective ribbing <NUM>, <NUM> can abut, form a sliding interface, overlap in a radial direction, or otherwise interface with each other. As shown, the angle brackets at the forward fastener joints 70A have a portion that lies coplanar with (e.g., and directly against) the outer wall surface of the inner frame <NUM>, and this negates the need for additional brackets or hardware extending from the inner frame <NUM>. In other constructions, a single bracket between the inner frame <NUM> and the outer enclosure <NUM> can have a portion that lies coplanar with (e.g., and directly against) the inner wall surface of the outer enclosure <NUM>. In either case, a single bracket is used at each forward fastener joint 70A, despite that the outer wall surface of the inner frame <NUM> and the inner wall surface of the outer enclosure <NUM> are non-parallel, i.e., arranged at a skew or oblique angle.

Even for the large-sized threaded fasteners <NUM>, the washers <NUM> can be oversized (e.g., outer diameter of <NUM> times or more the shank diameter of the threaded fastener <NUM>). The reason for oversizing the washers <NUM> is to ensure that the washers <NUM> sufficiently extend beyond the clearance holes <NUM> when assembled. Given that these fastener joints 70A, 70B are designed as the part of the speaker assembly <NUM> that accommodates assembly tolerance between the primary nested components of the outer enclosure <NUM> and the inner frame <NUM>, the clearance hole <NUM> of each of the plurality of fastener joints 70A, 70B provides a clearance at least <NUM> percent over (e.g., <NUM> percent over) the standard "normal" clearance for the size of the threaded fastener <NUM>. The standard normal fastener clearance diameter is determined by an American or international engineering organization or governing body, e.g., ASME B18. Although all of the fastener joints 70A, 70B can be provided with identical fasteners <NUM> and clearance dimensioning throughout the sum total of interfaces between the outer enclosure <NUM> and the inner frame <NUM>, it is also contemplated that intentional variation may be utilized at different ones of the fastener joints 70A, 70B.

The method of assembly of the speaker assembly <NUM> is significantly easier than most speaker assemblies of similar size and makeup. According to aspects of the present disclosure, the low frequency speaker drivers 48B are mounted to the inner frame <NUM> prior to insertion of the inner frame into the outer enclosure <NUM>. Thus, a subassembly of one or more speaker drivers is created outside of and separate from the outer enclosure <NUM>. This removes the requirement for access panels to install the low frequency speaker drivers 48B, and as such, the outer enclosure <NUM> may be provided with none. In some constructions, the high frequency driver(s) 48A and/or supporting electronics (e.g., frequency-filtering crossover network) are assembled to the inner frame <NUM> prior to installation into the outer enclosure <NUM>. To this extent of this concept, a complete subassembly unit (<FIG> and <FIG>) may be formed to include the inner frame <NUM>, multiple speaker drivers, including multiple high frequency drivers 48A (e.g., and associated wave guide <NUM>) and multiple low frequency drivers 48B, and corresponding crossover networks prior to assembly into the outer enclosure <NUM>. Assembly is completed by rearward insertion of the subassembly unit with the inner frame <NUM> through the front opening <NUM> of the outer enclosure <NUM> to a depth at which the fastener joints 70A, 70B can be secured. As mentioned above, precision at this step is not required as the fastener joints 70A, 70B absorb the assembly tolerance and uniformity around the perimeter port <NUM> is not a prerequisite to achieve the prescribed performance. However, if it is desired to precisely place the inner frame <NUM> with respect to the outer enclosure <NUM> (e.g., centered in the front opening <NUM>), this may be achieved by the use of temporary or permanent spacers between the outer enclosure <NUM> and the inner frame <NUM> to set the desired spacing prior to final securement of the fastener joints 70A, 70B.

Claim 1:
A ported speaker assembly (<NUM>) comprising:
an outer enclosure (<NUM>) having a front opening (<NUM>);
an inner frame (<NUM>) positioned at least partially within the outer enclosure (<NUM>) and having an outer perimeter portion proximate the front opening (<NUM>) of the outer enclosure (<NUM>);
a resonator chamber (<NUM>) defined between an interior of the outer enclosure (<NUM>) and an exterior of the inner frame (<NUM>);
at least one speaker driver (48A, 48B) mounted to the inner frame (<NUM>) and configured to emit sound from a front end of the ported speaker assembly (<NUM>);
a perimeter port (<NUM>) formed between the outer perimeter portion of the inner frame (<NUM>) and the front opening (<NUM>) of the outer enclosure (<NUM>) to establish sound wave communication between the resonator chamber (<NUM>) and a surrounding external atmosphere for tuned-frequency resonance output, and wherein the perimeter port (<NUM>) extends uninterrupted about the outer perimeter edge of the inner frame (<NUM>) so as to encircle the outer perimeter edge;
characterised in
a plurality of fastener joints (70A, 70B) securing the inner frame (<NUM>) to the outer enclosure (<NUM>), wherein at least some of the plurality of fastener joints (70A, 70B) are distributed around multiple sides of the inner frame (<NUM>) and positioned closer to the front opening (<NUM>) of the outer enclosure (<NUM>) than a rear end of the inner frame (<NUM>),
wherein each of the plurality of fastener joints (70A, 70B) includes a thread fastener (<NUM>), a washer (<NUM>), a clearance hole (<NUM>) for receiving the thread fastener (<NUM>), and a nut portion (<NUM>) for engaging the threaded fastener (<NUM>), and
wherein the plurality of fastener joints (70A, 70B) are configured to absorb all assembly tolerance between the outer enclosure (<NUM>) and the inner frame (<NUM>) such that the tolerances on the overall dimensions of the speaker assembly (<NUM>) are determined by the outer enclosure (<NUM>) alone.