Patent Application
20170188134
This document relates to enclosures for transducers, in particular, designs for improving acoustical performance of ported transducer array enclosures.
Loudspeakers can be considered as including at least two primary components: a transducer that converts electrical signals into mechanical motion, and an enclosure designed to convert mechanical motion into radiated sound. While some enclosures are sealed, another enclosure design includes a port that allows air to pass between the interior and exterior of the enclosure. By incorporating a port, smaller enclosures can be produced that are efficient (in terms of the sound radiated for a given electrical power input), and more sensitive (in terms of the sound radiated for a given electrical signal input) relative to sealed enclosures.
The disclosure provides a technique to improve the acoustical characteristics of a ported transducer enclosure with an array of transducers. By introducing an acoustic resistive element, acoustical characteristics (e.g., modes) of the port can be attenuated. Through the use of such a resistive element (or multiple elements), unwanted acoustic effects (e.g., spectral peaks of the port's signature appearing within the frequency band of the played content) can be reduced to improve the output sound produced by the individual speakers, beams formed by the speaker array, etc.
In one aspect, an apparatus includes an array of transducers for converting electrical signals into steered audible signals. The apparatus also includes an enclosure that includes each transducer in the array of transducers. The apparatus also includes one or more structures within the enclosure defining a port having one end located within the enclosure and another end that is external to the enclosure. The apparatus also includes an acoustic resistive element located in the one of the one or more structures, the acoustic resistive element being capable of reducing effects of the acoustic characteristics of the port for audible signals being produced by the array of transducers.
Implementations may include one or more of the following features. The acoustic resistive element may be configured to change the acoustical signature of one or more channels included in the port. The acoustic element may be shared by the port and another port included in the enclosure. The port may include a first channel portion and a second channel portion, the resistive element being located in a wall structure being shared by the first and second channel portions. The resistive element may be located in a wall structure being shared by a channel included in the port and the exterior of the enclosure. The acoustic resistance element may include a single layer. The acoustic resistance element may include multiple layers. The acoustic resistance element may include a layer of fabric material. The acoustic resistance element may include a metallic mesh. The acoustic resistance element may be generally rectangular in shape.
In another aspect, an apparatus includes an array of transducers for converting electrical signals into steered audible signals. The apparatus also includes an enclosure that includes each transducer in the array of transducers. The apparatus also includes one or more structures within the enclosure defining a port having one end located within the enclosure and another end that is external to the enclosure. The apparatus also includes an acoustic resistive element located in the one of the one or more structures, the acoustic resistive element being capable of reducing effects of the acoustic characteristics of the port for audible signals being produced by the array of transducers.
Implementations may include one or more of the following features. The acoustic resistive element may be configured to change the acoustical signature of one or more channels included in the port. The acoustic element may be shared by the port and another port included in the enclosure. The port may include a first channel portion and a second channel portion, the resistive element being located in a wall structure being shared by the first and second channel portions. The resistive element may be located in a wall structure being shared by a channel included in the port and the exterior of the enclosure. The acoustic resistance element may include a single layer. The acoustic resistance element may include multiple layers. The acoustic resistance element may include a layer of fabric material. The acoustic resistance element may include a metallic mesh. The acoustic resistance element may be generally rectangular in shape.
Other features and advantages will be apparent from the description and drawings, and from the claims.
Like reference symbols in the various drawings indicate like elements.
Referring to
In general, ports can have undesirable acoustical attributes that enclosure designs may address (e.g., minimize) to provide appropriate performance and still be relatively small in size. By allowing air flow through the port, unwanted noise and distortion can be produced. For example, the geometry of the port (e.g., port channel length) can produce acoustic standing waves that may alter the desired frequency response of the loudspeaker by introducing resonances, reinforcing noise and/or distortion, etc. through excitation of the standing waves. In arrangements in which the volume of the port is a considerable portion of the entire enclosure volume (e.g., port volume is 50% or more of the enclosure volume), standing waves in the port can occur at frequencies that are within the operating band of the loudspeaker (that includes the port and the transducer(s)). Through controlling techniques (e.g., damping), their corrupting effects can be reduced. Additionally, by properly dampening of such standing waves, the waves and/or resonances can be exploited to improve (e.g., increase) the output, efficiency, etc. of the loudspeaker.
The introduction of computer-aided modeling and design, computational analysis (e.g., finite element analysis), advanced manufacturing processes and materials, etc. have allowed ported enclosures to be designed with higher levels of quality and improved frequency responses compared to sealed enclosure designs. Along with the layout of the enclosure itself (e.g., transducer location, etc.) and other design parameters (e.g., enclosure size, materials employed such as wall linings, etc.), the design of the port to allow air flow (to and from the enclosure's interior) can affect the overall performance of the loudspeaker.
As mentioned above, the port 112 can contribute to noise being added output of the loudspeaker (that includes the enclosure 100 and the transducer 110). In particular, both the port interface 114 and the port channel 116 can cause the introduction of resonances, standing waves, etc. that may be considered noise sources. For example, resonant tones may be excited by the port interface's structure, the structure of the port channel, etc. Such noise tones can be particularly distracting to a listener when the spectral range of the audible content being played-back by the speaker includes the frequencies of the resonant tones. For example, the bass tones of the content may be affected by the tonal resonance, standing waves, etc. and thereby corrupt playback. Along with affecting the performance of a single transducer enclosure, the performance of an enclosure containing multiple transducers may be degraded. Other types of enclosures may also be affected in similar manners. For example, waveguide type enclosures can be considered as a port that consumes nearly the entire volume of the enclosure (e.g., a small percentage of an enclosure, 10%, is used by the transducer or transducer in the enclosure). Similar to the illustrated enclosure, standing waves may form in waveguide enclosures and potentially corrupt the output of the loudspeaker. Examples of such waveguides are described in U.S. Pat. No. 7,565,948, entitled “Acoustic Waveguiding,” and U.S. Pat. No. 8,295,525, entitled “Low Frequency Enclosure for Video Display Devices,” both of which are incorporated by reference in their entirety, herein.
Referring to
Similar to the single transducer enclosure shown in
Referring to
In this illustrated example, a single acoustic resistive element is incorporated into the wall structure 324; however additional elements may similarly be incorporated into the wall. Also, one or more resistive elements may be incorporated into other structures of the port channel 318; for example, one or multiple resistive elements may be included in a wall structure shared by the port channel and another portion of the enclosure 300. In one arrangement, one or more elements can be incorporated into an exterior wall structure (e.g., wall 326) that is shared with the port channel 318. Similar positions on each wall structure may be selected for incorporating such resistive elements, or, different position locations may be selected for multiple elements.
Various types of design parameters of the elements may be adjusted to reduce the acoustical characteristics of a port (e.g., port interface, port channel, etc.). For example, the size and shape of one or more elements may be adjusted. Similarly the orientation of the elements (as embedded in wall structures) may be adjusted (e.g., translated, rotated, etc.) individually or in concert (e.g., to create particular patterns) to address certain resonance effects.
Various types of structures may be employed for producing one or more acoustic resistive elements. For example, a single layer element (e.g., a single layer screen) or a multi-layer element (e.g., stacked screens) may be designed and used. For a multi-layer resistive element, one or more separation distances may be employed for the design. Further, air may be allowed to flow between the multiple layers, or, one or more materials may be used to create structures between the screens. For example, different patterns (e.g., ridges, channels, etc.) may be incorporated into structures positioned between screen pairs. Such screens can also incorporate one or more geometries (e.g., generally rectangular shapes, etc.).
Various types of materials may be used for producing resistive elements to dampen the effects of the acoustical characteristics of the port interfaces and channels. For example, one or more screens included in the resistive element 322 may be metallic in composition and include one or more metals (along with other types of materials in some arrangements). A substantially solid metal layer (or layers) may be used to produce a screen. Meshes and other types of pattern designs may be employed in one or more screens. One or more fabrics may be employed in the resistive element; for example, a relatively stiff fabric may be used that is capable to withstanding the environmental effects (e.g., temperatures, sound pressures, vibrations, etc.) of the transducer array enclosure 300. Composite materials may also be used to create a screen, a screen frame, or other structural components of the resistive element 322. Combinations of different materials may also be used for producing components of the resistive element 322; for example, one or more composites (e.g., plastics) and metals may be employed.
Referring to
To reduce the effects of one or more standing waves that form based upon the acoustical characteristics of the port 413, a resistive acoustic element 428 is incorporated into the shared wall structure 422 to reduce the acoustic resonant features of the port interface 414, the port channel (e.g., segments 416, 420), etc. that could affect the performance of the transducer array 402.
In this example, a single acoustic resistive element is incorporated into the wall 422; however additional elements may similarly be incorporated into the wall. Also, one or more resistive elements may be incorporated into other structures of the port channel segments; for example, one or multiple resistive elements may be included in other wall structures. For example, one or more elements can be incorporated into wall structure 418 that is shared by the port channel segment 416 and the exterior environment of the enclosure 400. In another example, one or more elements may be embedded in the wall structure 424 that is shared by port channel segment 420 and the cavity 426 (within which the transducer array 402 is mounted). Similar positions on each wall structure may be selected for incorporating such resistive elements, or, different position locations may be selected for two or more elements. As mentioned above, different geometries, materials, features (e.g., single layer, multi-layer, etc.), and other designs may be employed in the acoustic resistive elements.
Referring to
In this arrangement, to reduce the acoustic effects of the ports (e.g., port 502 and port 504), the cavities (e.g., cavities 516 and 518), etc., one or more acoustic resistive elements can be embedded in structures (e.g., wall structures) within the enclosure 500. In this particular example, acoustic resistive elements are incorporated into respective wall structures of the two ports 502 and 504. In particular, one resistive element 534 is incorporated into a wall structure 536 that is shared by port channel 510 and cavity 516, and, another resistive element 538 is incorporated into a wall structure 540 that is shared by port channel 512 and cavity 518. By being embedding in these respective locations, each resistive element is capable of reducing the sound pressure differential between the respective port channel and cavity. Such acoustic elements may be positioned in other locations within the transducer array enclosure 500; for example as mentioned above one or more elements may be embedded in other structures. In some arrangements, an element (or elements) may be incorporated into a wall structure 542 that is shared by a port channel (e.g., port channel 510) and the environment external to the enclosure 500. Similarly elements may be positioned in wall structures that are shared between the cavities (e.g., wall structure 514), positioned in a wall structure shared by a cavity and the exterior of the enclosure 500 (e.g., wall structure 544, 546, etc.), etc.
As illustrated in the figure, two ports 510 and 512 are employed to allow air flow between the exterior of the enclosure 500 and the enclosure's interior. In some designs, a single port or more than two ports may be used to provide air flow path(s). Such designs can produce noise sources that may corrupt the sound out of the enclosure. To reduce potentially corrupting acoustics, one or more lossy material acoustic resistive elements may be incorporated into one or more structures (e.g., wall structures) of these designs. Similar to previously described designs, to reduce such affects the resistive element may be a screen, a stack of screens (e.g., a multi-screen design), etc. that is embedded to be substantially flush to the surfaces of both sides of the wall structure. As mentioned above, the resistive element may incorporate a variety of designs, use various design parameters (e.g., geometries, materials, orientations, positioning), etc. For example, a resistive element may be provided by (or incorporated into) a three dimensional design (e.g., a tubular structure) that connects portions of an enclosure that do not share a structure (e.g., wall structure). While one resistive element may be incorporated into a wall structure (e.g., a shared wall structure), additional resistive elements can be incorporated into the wall; for example, multiple resistive elements (e.g., oriented in a particular pattern) can be embedded in the wall. Along with at least one resistive element being incorporated into a shared wall structure (or other types of structural component shared by the ports), multiple resistive elements may be incorporated at other locations of the transducer array enclosure; for example, resistive elements into wall structures 514, 542, 544, 546, etc. to reduce the potential corrupting of the output of the transducers included in the enclosure 500 (e.g., the transducer array). Similarly, different designs, design parameters, etc. may be used to reduce acoustical modes caused by the ports, cavities and other enclosure portions that may affect the content being played by a transducer array.
Many other implementations other than those described may be employed, and may be encompassed by the following claims.
