PATENT DOCUMENT

Publication Number: US-10299032-B2
Application Number: US-201715701335-A
Country: US
Kind Code: B2

Title: Front port resonator for a speaker assembly

Abstract:
A micro-speaker assembly including an enclosure having an enclosure wall separating a surrounding environment from an encased space, wherein the enclosure wall defines an acoustic port from the encased space to the surrounding environment; a sound radiating surface positioned within the encased space and dividing the encased space into a front volume chamber and a back volume chamber, wherein the front volume chamber is acoustically coupled to a first surface of the sound radiating surface and the acoustic port, and the back volume chamber acoustically coupled to a second surface of the sound radiating surface; and a resonator acoustically coupled to the front volume chamber, wherein the resonator comprises a neck acoustically coupled to an acoustic cavity, and an opening to the neck is positioned at a distance from the acoustic port that corresponds to a quarter wavelength resonance of the front volume chamber.

Claims:
What is claimed is: 
     
       1. A micro speaker assembly comprising:
 an enclosure having an enclosure wall separating a surrounding environment from an encased space, wherein the enclosure wall defines an acoustic port from the encased space to the surrounding environment; 
 a sound radiating surface positioned within the encased space and dividing the encased space into a front volume chamber and a back volume chamber, wherein the front volume chamber is acoustically coupled to a first surface of the sound radiating surface and the acoustic port, and the back volume chamber acoustically coupled to a second surface of the sound radiating surface; 
 a resonator acoustically coupled to the front volume chamber, wherein the resonator and the acoustic port are positioned along different sides of the sound radiating surface, and the resonator comprises a neck acoustically coupled to a closed acoustic cavity, and an opening to the neck is positioned at a distance from the acoustic port that corresponds to a quarter wavelength resonance of the front volume chamber; 
 a voice coil extending from the second surface of the sound radiating surface; and 
 a magnet assembly having a magnetic gap aligned with the voice coil. 
 
     
     
       2. The micro speaker assembly of  claim 1  wherein the distance from the acoustic port that corresponds to the quarter wavelength resonance is greater than a distance from the acoustic port to a center axis of the sound radiating surface, and the resonator is on a different side of the center axis than the acoustic port. 
     
     
       3. The micro speaker assembly of  claim 1  wherein the resonator is tuned to resonate at a same frequency as a quarter wave resonance of the front volume chamber such that it extends a frequency bandwidth of a sound generated by the sound radiating surface. 
     
     
       4. The micro speaker assembly of  claim 1  wherein the neck of the resonator comprises a narrower cross-section than the closed acoustic cavity. 
     
     
       5. The micro speaker assembly of  claim 1  wherein the opening to the neck of the resonator faces a different direction than the acoustic port. 
     
     
       6. The micro speaker assembly of  claim 1  wherein the neck of the resonator defines a tortuous acoustic pathway. 
     
     
       7. The micro speaker assembly of  claim 1  wherein the closed acoustic cavity defines a tortuous acoustic pathway. 
     
     
       8. The micro speaker assembly of  claim 1  wherein the resonator is positioned within the enclosure and the closed acoustic cavity occupies a portion of the back volume chamber within the encased space. 
     
     
       9. The micro speaker assembly of  claim 1  wherein the closed acoustic cavity is acoustically isolated from the back volume chamber. 
     
     
       10. The micro speaker assembly of  claim 1  wherein the enclosure wall comprises a top wall that is parallel to a bottom wall, and a side wall connecting the top wall to the bottom wall, and wherein the resonator is formed in part by at least one of the top wall, the bottom wall of the side wall. 
     
     
       11. The micro speaker assembly of  claim 1  wherein the enclosure wall comprises a top wall that is parallel to a bottom wall, and a side wall connecting the top wall to the bottom wall, and wherein the acoustic port is positioned within the side wall. 
     
     
       12. A micro speaker assembly comprising:
 an enclosure having an enclosure wall separating a surrounding environment from an encased space, wherein the enclosure wall defines an acoustic port from the encased space to the surrounding environment; 
 a sound radiating surface positioned within the encased space and dividing the encased space into a front volume chamber acoustically coupled to a first surface of the sound radiating surface and a back volume chamber acoustically coupled to a second surface of the sound radiating surface, and wherein the front volume chamber is acoustically coupled to the acoustic port; 
 a Helmholtz resonator acoustically coupled to the front volume chamber and the acoustic port, and wherein a closed cavity of the Helmholtz resonator is positioned within the back volume chamber and is not acoustically coupled to the back volume chamber; 
 a voice coil extending from the second surface of the sound radiating surface; and 
 a magnet assembly having a magnetic gap aligned with the voice coil. 
 
     
     
       13. The micro speaker assembly of  claim 12  wherein the Helmholtz resonator is operable to extend a frequency bandwidth of a sound generated by the sound radiating surface in comparison to a micro speaker assembly without a Helmholtz resonator. 
     
     
       14. The micro speaker assembly of  claim 12  wherein the Helmholtz resonator is tuned to resonate at a same frequency as a quarter wave resonance of the front volume chamber. 
     
     
       15. The micro speaker assembly of  claim 12  wherein an opening to the Helmholtz resonator is positioned at a pressure maximum of a quarter wave resonance of the front volume chamber. 
     
     
       16. The micro speaker assembly of  claim 12  wherein the Helmholtz resonator is acoustically coupled to the front volume chamber at a location that is farther from the acoustic port than a center axis of the sound radiating surface. 
     
     
       17. The micro speaker assembly of  claim 12  wherein the Helmholtz resonator comprises an interior damping member that forms a tortuous acoustic pathway within the Helmholtz resonator. 
     
     
       18. The micro speaker assembly of  claim 12  wherein a perimeter of the sound radiating surface is defined by four sides, and the Helmholtz resonator is positioned along a side of the sound radiating surface that is different than the acoustic port. 
     
     
       19. An electroacoustic transducer assembly comprising:
 an enclosure separating a surrounding environment from an encased space, wherein the enclosure comprises a top wall, a bottom wall and a side wall connecting the top wall to the bottom wall, and an acoustic port formed within the side wall and connecting the encased space to the surrounding environment; 
 a driver positioned within the encased space, the driver comprising a sound radiating surface dividing the encased space into a front volume chamber and a back volume chamber, wherein the front volume chamber is acoustically coupled to the acoustic port and defined in part by the top wall and a first surface of the sound radiating surface that faces the top wall, and the back volume chamber is defined in part by the bottom wall and a second surface of the sound radiating surface; and 
 a resonator acoustically coupled to the front volume chamber, wherein the resonator comprises an acoustic channel having one end open to the front volume chamber and another end open to a closed acoustic cavity, and wherein the closed acoustic cavity is positioned within the back volume chamber. 
 
     
     
       20. The electroacoustic transducer assembly of  claim 19  wherein the one end of the acoustic channel is open to the front volume chamber at a location that is a distance from the acoustic port that corresponds to a quarter wavelength resonance of the front volume chamber, the only acoustic pathway to the closed acoustic cavity is through the another open end of the acoustic channel, and the closed acoustic cavity is positioned between the second surface of the sound radiating surface and the bottom wall.

Description:
FIELD 
     This application relates generally to a speaker having a resonator, more specifically a micro speaker having a resonator that is acoustically coupled to a front port to extend a frequency bandwidth of the micro speaker, and therefore improve a quality of sound emitted from the micro speaker system. Other embodiments are also described and claimed. 
     BACKGROUND 
     In modern consumer electronics, audio capability is playing an increasingly larger role as improvements in digital audio signal processing and audio content delivery continue to happen. In this aspect, there is a wide range of consumer electronics devices that can benefit from improved audio performance. For instance, smart phones include, for example, electro-acoustic transducers such as speakerphone loudspeakers and earpiece receivers that can benefit from improved audio performance. Smart phones, however, do not have sufficient space to house much larger high fidelity sound output devices. This is also true for some portable personal computers such as laptop, notebook, and tablet computers, and, to a lesser extent, desktop personal computers with built-in speakers. Many of these devices use what are commonly referred to as “micro speakers.” Micro speakers are a miniaturized version of a loudspeaker, which use a moving coil motor to drive sound output. The moving coil motor may include a diaphragm (or sound radiating surface), voice coil and magnet assembly positioned within a frame. The input of an electrical audio signal to the moving coil motor causes the diaphragm to vibrate and output sound. The sound may be output from the sound output surface of the diaphragm to a sound output port through a front volume chamber that acoustically couples the sound output face to the output port. A back volume chamber may further be formed around the opposite face of the diaphragm to enhance sound output quality. Due to increasing demands for relatively low profile devices, particularly in the z-height dimension, however, it is becoming increasingly difficult to maximize a sound output of the system. 
     SUMMARY 
     In one embodiment, the invention is directed to a transducer assembly having a front port resonator configured to widen a working or fundamental frequency bandwidth of the transducer. The term “fundamental” is intended to refer to the first resonance frequency of the acoustic pathway, channel or chamber through which the sound travels to the surrounding environment, and can also be referred to as the quarter wavelength. More specifically, due to cosmetic requirements and size constraints, for example in micro speaker enclosures, the sound radiating surface of the speaker may not be positioned next to the cosmetic opening (e.g. sound outlet) of the device. The sound waves generated by the sound radiating surface must therefore travel though an acoustic pathway before exiting the device. This pathway is constrained by a certain shape, which may change the amplitude of the sound waves at geometry dependent frequencies. In particular, every open-ended air channel, or a tube, has a fundamental frequency or quarter wavelength that is linked to the length of the channel or tube. This length may be the length at which only a quarter of the wavelength can occur in that length of tube. When the wavelength of the frequency, generated by the speaker, coincides with the quarter wavelength of the air channel length, the radiated sound loudness may increase. The frequency at which this occurs may be referred to as the Quarter Wave Resonance (QWR) of the tube. In addition, wave equation dictates that, at resonance, the phase shifts by 180 degrees. A 180 degree phase shift means the sound waves traveling inside the acoustic channel are out of phase with the speaker, therefore after this resonance, the loudness of the speaker diminishes significantly. Loss of high frequency loudness also has other implications in human perception of sound quality. The quality of a sound system is measured by the amount of frequencies it can cover without losing a certain amount of sound pressure level (SPL), also called the frequency bandwidth. This limit is defined to be −3 decibel (dB) and the aim is to keep it as wide as possible. Thus, the speaker assembly disclosed herein addresses the above-noted phenomenon by coupling a resonator to the front volume chamber and front port of the speaker. The resonator is tuned to resonate at a same frequency as a quarter wave resonances of the chamber and positioned at a particular location with respect to the front port such that it can increase the frequency bandwidth of the sound system by only acoustical means, and without changing the components of the driver (e.g., magnet, diaphragm, surround, coil, etc.). 
     Representatively, in one embodiment, the invention is directed to a micro speaker assembly including an enclosure having an enclosure wall separating a surrounding environment from an encased space, wherein the enclosure wall defines an acoustic port from the encased space to the surrounding environment. The assembly further includes a sound radiating surface positioned within the encased space and dividing the encased space into a front volume chamber and a back volume chamber. The front volume chamber may be acoustically coupled to a first surface of the sound radiating surface and the acoustic port, and the back volume chamber may be acoustically coupled to a second surface of the sound radiating surface. In addition, a resonator acoustically coupled to the front volume chamber is provided. The resonator may include a neck acoustically coupled to an acoustic cavity, and an opening to the neck positioned at a distance from the acoustic port that corresponds to a quarter wavelength resonance of the front volume chamber. The assembly may further include a voice coil extending from the second surface of the sound radiating surface and a magnet assembly having a magnetic gap aligned with the voice coil. In some embodiments, the distance from the acoustic port that corresponds to the quarter wavelength resonance is greater than a distance from the acoustic port to a center axis of the sound radiating surface. In addition, the resonator may be tuned to resonate at a same frequency as a quarter wave resonance of the front volume chamber such that it extends a frequency bandwidth of a sound generated by the sound radiating surface. Still further, the neck of the resonator may have a narrower cross-section than the acoustic cavity. In addition, the opening to the neck of the resonator may face a different direction than the acoustic port. Still further, the neck or the acoustic cavity of the resonator may have a tortuous acoustic pathway. In some embodiments, the resonator may be positioned within the enclosure and the acoustic cavity may occupy a portion of the back volume chamber within the encased space. The acoustic cavity may further be a closed acoustic cavity that is acoustically isolated from the back volume chamber. In some embodiments, the enclosure wall may have a top wall that is parallel to a bottom wall, and a side wall connecting the top wall to the bottom wall, and the resonator may be formed in part by at least one of the top wall, the bottom wall or the side wall. In addition, in some embodiments, the acoustic port may be positioned within the side wall. 
     In another embodiment, the invention is directed to a micro speaker assembly including an enclosure having an enclosure wall separating a surrounding environment from an encased space and which defines an acoustic port from the encased space to the surrounding environment. The assembly may further include a sound radiating surface positioned within the encased space and dividing the encased space into a front volume chamber acoustically coupled to a first surface of the sound radiating surface and a back volume chamber acoustically coupled to a second surface of the sound radiating surface, and the front volume chamber may be acoustically coupled to the acoustic port. In addition, a Helmholtz resonator acoustically coupled to the front volume chamber and the acoustic port may further be provided. The Helmholtz resonator may be positioned within the back volume chamber. In addition, the assembly may include a voice coil extending from the second surface of the sound radiating surface and a magnet assembly having a magnetic gap aligned with the voice coil. The Helmholtz resonator may be operable to extend a frequency bandwidth of a sound generated by the sound radiating surface in comparison to a micro speaker assembly without a Helmholtz resonator. For example, the Helmholtz resonator may be tuned to resonate at a same frequency as a quarter wave resonance of the front volume chamber. An opening to the Helmholtz resonator may be positioned at a pressure maximum of a quarter wave resonance of the front volume chamber. The Helmholtz resonator may be acoustically coupled to the front volume chamber at a location that is farther from the acoustic port than a center axis of the sound radiating surface. The Helmholtz resonator may further include an interior damping member that forms a tortuous acoustic pathway within the Helmholtz resonator. In some embodiments, a perimeter of the sound radiating surface is defined by four sides, and the Helmholtz resonator is positioned along a side of the sound radiating surface that is different than the acoustic port. 
     In other embodiments, the invention is directed to an electroacoustic transducer assembly including an enclosure separating a surrounding environment from an encased space, and which includes a top wall, a bottom wall and a side wall connecting the top wall to the bottom wall, and an acoustic port formed within the side wall and connecting the encased space to the surrounding environment. A driver may be positioned within the encased space and include a sound radiating surface dividing the encased space into a front volume chamber and a back volume chamber, wherein the front volume chamber is acoustically coupled to the acoustic port and defined in part by the top wall and a first surface of the sound radiating surface that faces the top wall, and the back volume chamber is defined in part by the bottom wall and a second surface of the sound radiating surface. A resonator acoustically coupled to the front volume chamber may further be provided. The resonator may include an acoustic channel having one end open to the front volume chamber and another end open to a closed acoustic cavity, and the closed acoustic cavity may be positioned within the back volume chamber. In addition, in some embodiments, one end of the acoustic channel is open to the front volume chamber at a location that is a distance from the acoustic port that corresponds to a quarter wavelength resonance of the front volume chamber, and the only acoustic pathway to the closed acoustic cavity is through the other open end of the acoustic channel. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. 
         FIG. 1  illustrates a cross-sectional side view of one embodiment of a transducer assembly. 
         FIG. 2  illustrates a simplified schematic cross-sectional view of the transducer assembly of  FIG. 1 . 
         FIG. 3  illustrates one embodiment of a graph showing an enhanced frequency bandwidth achieved using the resonator of  FIG. 1  and  FIG. 2 . 
         FIG. 4  illustrates a simplified schematic top plan view of the transducer assembly of  FIG. 1 . 
         FIG. 5  illustrates a simplified schematic top plan view of another embodiment of a transducer assembly. 
         FIG. 6  illustrates a simplified schematic top plan view of another embodiment of a resonator. 
         FIG. 7  illustrates a simplified schematic top plan view of another embodiment of a resonator. 
         FIG. 8  illustrates one embodiment of a simplified schematic view of one embodiment of an electronic device in which one or more embodiments may be may be implemented. 
         FIG. 9  illustrates a block diagram of some of the constituent components of an embodiment of an electronic device in which one or more embodiments may be implemented. 
     
    
    
     DETAILED DESCRIPTION 
     In this section we shall explain several preferred embodiments of this invention with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the invention is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments of the invention may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like may be used herein for ease of description to describe one element&#39;s or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising” specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. 
     The terms “or” and “and/or” as used herein are to be interpreted as inclusive or meaning any one or any combination. Therefore, “A, B or C” or “A, B and/or C” mean “any of the following: A; B; C; A and B; A and C; B and C; A, B and C.” An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive. 
       FIG. 1  illustrates a cross-sectional side view of one embodiment of a transducer. Transducer  100  may be, for example, an electroacoustic driver or transducer that converts electrical signals into audible signals that can be output from a device within which transducer  100  is integrated. For example, transducer  100  may be a micro speaker such as a speakerphone speaker or an earpiece receiver found within a smart phone, or other similar compact electronic device such as a laptop, notebook, tablet computer or portable time piece. Transducer  100  may be enclosed within a housing or enclosure of the device within which it is integrated. In some embodiments, transducer  100  may be a 10 mm to 75 mm driver, or 10 mm to 20 mm driver (as measured along the diameter or longest length dimension), for example, a micro speaker. 
     Transducer  100  may include an enclosure  102 , which is made up of an enclosure wall  104  that separates a surrounding environment from an encased space  106 . Each of the components of transducer  100 , for example components of a speaker assembly as will be discussed herein, may be positioned within encased space  106  and therefore enclosed within enclosure wall  104 . In some embodiments, enclosure wall  104  may include a wall  104 A, a wall  104 B and walls  104 C- 104 D, which form a top side (or top wall), a bottom side (or bottom wall) and side walls, respectively, of enclosure  102 . The wall  104 A may be substantially parallel to the wall  104 B, and walls  104 C- 104 D may be perpendicular to the other walls, and connect wall  104 A to wall  104 B. In addition, at least one of the wall  104 A or the wall  104 B, and in some cases side walls  104 C- 104 D (alone, in combination, or in combination with another encased transducer component) may form all, or a portion of, an acoustic channel or port  108 . For example, the acoustic channel or port  108  may be formed between walls  104 A- 104 B, or otherwise through a side wall  104 D of enclosure  102 , such that the transducer is considered a “side firing” device or system. The acoustic channel or port  108  may acoustically connect the encased space  106  to the surrounding environment. For example, in the case of a micro speaker, the acoustic channel or port  108  may be a port (or elongated channel) that is acoustically coupled to a sound radiating component of the transducer and outputs sound (S) produced by transducer  100  to the surrounding environment. In addition, in some embodiments, a protective barrier  138  may be positioned at an end of acoustic port or channel  108  to protect transducer  100  from particle or fluid ingress. In this aspect, sound (S) may travel through protective barrier  138  before reaching the surrounding environment. 
     In one embodiment, one of the components of transducer  100  (e.g., speaker assembly components) positioned within the encased space  106  may include a sound radiating surface (SRS)  110 . The SRS  110  may also be referred to herein as an acoustic radiator, a sound radiator or a diaphragm. SRS  110  may be any type of flexible membrane capable of vibrating in response to an acoustic signal to produce acoustic or sound waves. SRS  110  may include a top face  110 A, which generates sound to be output to a user, and a bottom face  110 B, which is acoustically isolated from the top face  110 A, so that any acoustic or sound waves generated by the bottom face  110 B do not interfere with those from the top face  110 A. The top face  110 A may be considered the “top” face because it faces, or includes a surface substantially parallel to, the top or first enclosure wall  104 A. Similarly, the bottom face  110 B may be considered a “bottom” face because it faces, or includes a surface substantially parallel to, the bottom or second enclosure wall  104 B. SRS  110  may have an out-of-plane region as shown (e.g. for geometric stiffening) or be substantially planar. 
     In some embodiments, SRS  110  may be suspended within enclosure  102  by a suspension member  116 , which may be connected to enclosure  102  by a support member  118 . Representatively, suspension member  116  may be a flexible membrane connected to a perimeter of SRS  110  along one side, and support member  118  along another side. In addition, in some embodiments, suspension member  116  may extend from one support member  118  to another, and SRS  110  may be a stiffening layer positioned on a top surface of suspension member  116 . The support member  118  may be connected to, for example, the bottom or enclosure wall  104 B. The support member  118  may be an additional wall, for example an interior wall, of enclosure  102 . Support member  118  may be a separate structure that is attached to, for example an interior surface of enclosure wall  104 B, or a structure that is integrally formed with enclosure wall  104 . 
     As illustrated in  FIG. 1 , SRS  110  (in combination with suspension member  116  and/or support member  118 ), may divide the encased space  106  into a first acoustic chamber  112  and a second acoustic chamber  114 . The first acoustic chamber  112  may be acoustically isolated from the second acoustic chamber  114 . For example, the first acoustic chamber  112  may acoustically connect the top face  110 A of SRS  110  to acoustic channel or port  108 , and therefore be considered a front volume chamber. In this aspect, the first acoustic chamber  112  (or front volume chamber) may be considered between, and formed in part by, the top face  110 A of the SRS  110  and first enclosure wall  104 A, and in some cases a side wall of enclosure wall  104 . The second acoustic chamber  114  may be acoustically coupled to the bottom face  110 E and therefore be considered a back volume chamber. The second acoustic chamber  114  is therefore considered between, and formed in part by, the bottom face  110 E of SRS  110  and wall  104 B, and in some cases wall  104 C (or other side walls). 
     The assembly may further include a resonator  120  connected to first chamber  112  to increase the frequency bandwidth of the sound (S) generated by the SRS  110 . Resonator  120  may be considered a “front port resonator” in that it is acoustically coupled to, or in acoustic communication with, first chamber  112 , which is considered a front volume chamber because it provides an acoustic channel for the sound (S) to travel to acoustic port  108 . Resonator  120  may be any type of hollow chamber or cavity dimensioned to resonate at particular frequencies (e.g., resonance frequencies), with greater amplitude than at others. For example, in some embodiments, resonator  120  may be a Helmholtz resonator. More specifically, resonator  120  may include a channel or neck  122  and an acoustic cavity  124 . The channel or neck  122  may have an opening  122 A at one end to the first chamber  112 , and an opening  122 B at another end to an acoustic cavity  124 . In this aspect, channel or neck  122  may define an acoustic pathway through which a sound (S) generated by SRS  110  may travel to and/or from acoustic cavity  124 . Resonator  120  may further be positioned within the encased space  106  defined by enclosure  102  such that it is entirely contained within enclosure  102 . For example, in some embodiments, resonator  120  may be formed by one or more walls that are interior to enclosure walls  104 A- 104 C, or formed by one or more of enclosure walls  104 A- 104 C. Acoustic cavity  124  may further be positioned within, and occupy a portion of, second chamber  114  (e.g., a back volume chamber). Acoustic cavity  124  may, however, be a closed cavity in that it includes only one opening, namely the opening  122 B at one end of neck  122  to first chamber  112 , and ultimately acoustic port  108 . In this aspect, although acoustic cavity  124  is positioned within second chamber  114 , its interior volume is acoustically isolated from, or is otherwise not shared with, second chamber  114 . To achieve an increased frequency bandwidth, resonator  120  may be tuned to a resonate at a same frequency as a quarter wave resonance of first chamber  112 , and be located at a particular location with respect to acoustic port  108 , as will be discussed in more detail in reference to  FIG. 2 - FIG. 3 . 
     Returning now to the interior components of transducer  100 , transducer  100  may also include a voice coil  126  positioned along a bottom face  110 E of SRS  110  (e.g., a face of SRS  110  facing magnet assembly  128 ). For example, in one embodiment, voice coil  126  includes an upper end directly attached to the bottom face  110 B of SRS  110 , such as by chemical bonding or the like, and a lower end. In another embodiment, voice coil  126  may be formed by a wire wrapped around a former or bobbin and the former or bobbin is directly attached to the bottom face  110 E of SRS  110 . In one embodiment, voice coil  126  may have a similar profile and shape to that of SRS  110 . For example, where SRS  110  has a square, rectangular, circular or racetrack shape, voice coil  126  may also have a similar shape. For example, voice coil  126  may have a substantially rectangular, square, circular or racetrack shape. 
     Transducer  100  may further include a magnet assembly  128 . Magnet assembly  128  may include a magnet  130  (e.g., a NdFeB magnet), with a top plate  132  and a yoke  134  for guiding a magnetic circuit generated by magnet  130 . Magnet assembly  128 , including magnet  130 , top plate  132  and yoke  134 , may be positioned such that voice coil  126  is aligned with magnetic gap  136  formed by magnet  130 . For example, magnet assembly  128  may be below SRS  110 , and in some cases, between SRS  110  and the bottom, or second enclosure wall  104 B. In addition, in some embodiments, top plate  132  may be specially designed to accommodate an out-of-plane region (e.g., a concave or dome shaped region) of SRS  110 . For example, top plate  132  may have a cut-out or opening within its center that is aligned with the out-of-plane region of SRS  110 . In this aspect, the additional space created below the out-of-plane region of SRS  110  allows SRS  110  to move or vibrate up and down (e.g., pistonically) without contacting top plate  132 . In this aspect, the opening may have a similar size or area as the out-of-plane region. In addition, although a one-magnet embodiment is shown here, although multi-magnet motors are also contemplated. 
     In addition, although not shown, transducer  100  my include circuitry (e.g., an application-specific integrated circuit (ASIC)) or other external components electrically connected to transducer  100  to, for example, drive current through the voice coil  126  to operate the transducer  100 . 
       FIG. 2  illustrates a simplified cross-sectional schematic diagram of the transducer and resonator of  FIG. 1 . In particular, as can be seen from  FIG. 2 , first chamber  112 , which may be formed by enclosure wall  104 A and the top face  110 A of SRS  110 , is essentially an acoustic channel or tube through which sound (S) can travel to acoustic port  108 . As previously discussed, every open-ended air channel, or a tube, has a fundamental frequency or quarter wavelength that is linked to the length of the channel or tube (e.g., only a quarter of the wavelength can occur in that length of tube). Thus, first chamber  112  has a quarter wavelength  202  that corresponds to its length (L). When the wavelength of the frequency, generated by SRS  110 , coincides with the quarter wavelength, the radiated sound loudness increases. This frequency may be referred to as the Quarter Wave Resonance (QWR) of the first chamber  112 . To influence this QWR (e.g., increase a frequency bandwidth), resonator  120  is, in turn, tuned to resonate at the same frequency as the QWR of first chamber  112 . Representatively, the resonator cavity volume (V), neck opening area or width (W) and/or neck length (L 1 ) of resonator  120  may be calibrated, tuned, or otherwise selected, so that resonator  120  resonates at the same frequency as the QWR of first chamber  112 . For example, neck  122  may have an area or opening width (W) that is relatively narrow, for example narrower than the area or width (W 1 ) of acoustic cavity  124 , and that is tuned with respect to the neck length (L 1 ), cavity width (W 1 ) or volume (V) to achieve the desired resonance. In addition, in order to influence the QWR, the opening  122 A to resonator  120  should be positioned at a distance from acoustic port  108  corresponding to at least the length (L) corresponding to the quarter wavelength or the pressure maximum of first chamber  112 . In particular, when resonator  120  is positioned at this particular location, resonator  120  can spread the energy of the QWR towards lower and higher frequencies to extend the frequency bandwidth of the transducer. 
     To further illustrate this improved bandwidth,  FIG. 3  shows a graph comparing transducer systems with and without the resonator disclosed herein. In particular, the dashed line  302  of graph  300  shows the frequency bandwidth of a system without a front port resonator as disclosed herein, and the solid line  304  shows the frequency bandwidth of a system with the front port resonator. As can be seen from line  302 , in a transducer without a front port resonator, when the wavelength of the frequency generated by the speaker coincides with the QWR of the air channel length, the radiated sound loudness increases, as illustrated by peak  306 . In addition, after this increase, the loudness diminishes significantly. These irregularities in sound loudness can be perceived by the user as poor sound quality. As can be seen from line  304 , however, the presence of the front port resonator disclosed herein helps to flatten the frequency response at the QWR (as illustrated by arrow  308 ), bring each frequency to equal loudness levels, and also extend the frequency bandwidth (as illustrated by arrow  310 ). This increase in the efficiency of the transducer outside the QWR improves sound quality for the user. 
     Referring now to  FIG. 4 ,  FIG. 4  illustrates a simplified schematic diagram of a top plan view of the transducer and front port resonator described in reference to  FIG. 1 . Representatively, from this view, it can be seen that in one embodiment, resonator  120  is positioned within second chamber  114  of enclosure  102 . In addition, the opening  122 A from resonator  120  to first chamber  112  is located at a distance from the acoustic port  108  that corresponds to the quarter wavelength of first chamber  112 , or length (L) as described in reference to  FIG. 2 . This location of opening  122 A corresponding to length (L) may also be considered a pressure maximum of first chamber  112 . Therefore the location of opening  122 A may also be defined as being at the pressure maximum of first chamber  112 . This length (L) may be greater than a distance from the acoustic port  108  to a center axis  404  of sound radiating surface  110 . Therefore the location of resonator opening  122 A may further be defined with respect to center axis  404 . For example, the location of opening  122 A may be considered to be one that is at a distance from the acoustic port  108  that is greater than a distance from the acoustic port  108  to center axis  404 . 
     In addition, from this view it can be seen that in one embodiment, the sound radiating surface  110  may be defined by four sides  402 A,  402 B,  402 C and  402 D which connect to form a square shaped sound radiating surface  110 . The opening  122 A to resonator  120  may be along one side  402 C of sound radiating surface  110  while the acoustic port  108  is positioned along another side  402 A of sound radiating surface  110 . Thus, resonator  120  may also be described as having a position in which opening  122 A is along a side of sound radiating surface  110  different from that of acoustic port  108 , for example opening  122 A may be along an opposite side  402 C to that of acoustic port  108  as shown. In addition, in some embodiments, the neck  122  of resonator  120  may be positioned such that opening  122 A opens, or otherwise faces, a same direction as illustrated by arrow  406 , as acoustic port  108 . Said another way, opening  122 A may open, or otherwise face a direction that is perpendicular to the center axis  404  of sound radiating surface  110 . 
     Other resonator configurations, however, are contemplated. For example,  FIG. 5  shows a simplified schematic top plan view of another embodiment in which resonator  120  is positioned at the quarter wavelength, length (L), of first chamber  112 , however, along a different side of sound radiating surface  110  than what is illustrated in  FIG. 4 . Representatively, in this embodiment, resonator  120  is shown positioned along a side  402 D that is adjacent to the side  402 A that acoustic port  108  is formed along. It is contemplated, however, that resonator  120  could also be positioned along side  402 B, as shown by dashed lines. The opening  122 A to resonator  120 , however, is still positioned at the quarter wavelength, length (L), of first chamber  112 . In this case, however, opening  122 A to first chamber  112  faces or opens in a direction  502  that is parallel to center axis  404  of sound radiating surface  110 . Said another way, opening  122 A faces or opens in a different direction than acoustic port  108 , for example, a direction that is perpendicular to acoustic port  108 . It can also be seen that in this embodiment, although resonator  120  opens to first chamber  112  via opening  122 A, acoustic cavity  124  is still positioned within second chamber  114 , and within the encased space formed by enclosure wall  104 . 
     Referring now to  FIG. 6  and  FIG. 7 ,  FIG. 6  and  FIG. 7  illustrate simplified cross-sectional schematic views of one embodiment of a resonator. Representatively,  FIG. 6  shows resonator  120  including an acoustic channel, duct or neck  122  that opens to acoustic cavity  124 , as previously discussed. As previously discussed, neck  122  may have a width (W) and length (L 1 ), and define an acoustic pathway between acoustic cavity  124  and first chamber  112  of enclosure  102 . Acoustic cavity  124  may also have a width (W 1 ) and define an acoustic volume (V). In some embodiments, the width (W) of neck  122  may be smaller, or narrower, than the width (W 1 ) of acoustic cavity  124 . Opening  122 A to first chamber  112  and/or opening  122 B to acoustic cavity  124 , may therefore be considered relatively narrow with respect to the size of acoustic cavity  124  and/or first chamber  112 . One or more of the neck width (W) and/or length (L 1 ) and acoustic volume (V) of acoustic cavity  124  may be calibrated, or tuned, so that resonator  120  resonates at a same frequency as the quarter wave resonance of first chamber  112 . 
     In addition, in some embodiments, resonator  120  may include a damping feature, which can help to reduce a magnitude of the peak (e.g. peak  306  in  FIG. 3 ) in close proximity to the resonance and amplify frequencies outside the resonance frequency bands. Representatively, in one embodiment, neck  122  may include at least one damping member  602 , for example a barrier, that creates a tortuous flow path  604  through neck  122 . Damping member  602  may, for example, be positioned along the interior surface of neck  122  and extend into, or otherwise partially occlude, a portion of the acoustic pathway defined by neck  122 . In this aspect, neck  122  may be considered to have an interior width that varies between regions having a width (W) as previously discussed, and narrower regions having a width (W 2 ). Damping member  602  may be a structure and/or material of any shape and size suitable for creating a tortuous pathway within neck  122 . For example, damping member  602  could be an interior wall integrally formed with the same material as neck  122  (e.g., a plastic), or could be a different material than neck  122 , for example, a damping material. It should further be understood that damping member  602  need not be an additional structure or protrusion extending from the interior surface of neck  122 , but instead should be broadly understood as representing any bend, turn, zig-zag or similar configuration that an interior surface of neck  122  may have to create a tortuous pathway. For example, damping member  602  may represent one or more of the bends defining the tortuous pathway created by the bending or meandering neck  122  shown in  FIG. 1  and  FIG. 2 . 
       FIG. 7  illustrates another embodiment of a resonator similar to that of  FIG. 6 , except in this embodiment, the acoustic cavity  124  also includes a damping member  702 . Representatively, damping member  702  may similar to damping member  602  described in reference to  FIG. 6  except that it extends from the interior surface of acoustic cavity  124 , and creates a tortuous flow path  704  through acoustic cavity  124 . In this aspect, acoustic cavity  124  may also have an interior width that varies between regions having a width (W 1 ) as previously discussed, and regions having a narrower width (W 2 ). 
       FIG. 8  illustrates one embodiment of a simplified schematic view of one embodiment of an electronic device in which a transducer (e.g., a micro speaker), such as that described herein, may be implemented. As seen in  FIG. 8 , the transducer may be integrated within a consumer electronic device  802  such as a smart phone with which a user can conduct a call with a far-end user of a communications device  804  over a wireless communications network; in another example, the speaker may be integrated within the housing of a tablet computer  806 . These are just two examples of where the speaker described herein may be used, it is contemplated, however, that the speaker may be used with any type of electronic device in which a transducer, for example, a loudspeaker or microphone, is desired, for example, a tablet computer, a desk top computing device or other display device. 
       FIG. 9  illustrates a block diagram of some of the constituent components of an embodiment of an electronic device in which one or more embodiments may be implemented. Device  900  may be any one of several different types of consumer electronic devices. For example, the device  900  may be any transducer-equipped mobile device, such as a cellular phone, a smart phone, a media player, or a tablet-like portable computer. 
     In this aspect, electronic device  900  includes a processor  912  that interacts with camera circuitry  906 , motion sensor  904 , storage  908 , memory  914 , display  922 , and user input interface  924 . Main processor  912  may also interact with communications circuitry  902 , primary power source  910 , speaker  918  and microphone  920 . Speaker  918  may be a micro speaker such as that described in reference to  FIG. 1 . The various components of the electronic device  900  may be digitally interconnected and used or managed by a software stack being executed by the processor  912 . Many of the components shown or described here may be implemented as one or more dedicated hardware units and/or a programmed processor (software being executed by a processor, e.g., the processor  912 ). 
     The processor  912  controls the overall operation of the device  900  by performing some or all of the operations of one or more applications or operating system programs implemented on the device  900 , by executing instructions for it (software code and data) that may be found in the storage  908 . The processor  912  may, for example, drive the display  922  and receive user inputs through the user input interface  924  (which may be integrated with the display  922  as part of a single, touch sensitive display panel). In addition, processor  912  may send an audio signal to speaker  918  to facilitate operation of speaker  918 . 
     Storage  908  provides a relatively large amount of “permanent” data storage, using nonvolatile solid state memory (e.g., flash storage) and/or a kinetic nonvolatile storage device (e.g., rotating magnetic disk drive). Storage  908  may include both local storage and storage space on a remote server. Storage  908  may store data as well as software components that control and manage, at a higher level, the different functions of the device  900 . 
     In addition to storage  908 , there may be memory  914 , also referred to as main memory or program memory, which provides relatively fast access to stored code and data that is being executed by the processor  912 . Memory  914  may include solid state random access memory (RAM), e.g., static RAM or dynamic RAM. There may be one or more processors, e.g., processor  912 , that run or execute various software programs, modules, or sets of instructions (e.g., applications) that, while stored permanently in the storage  908 , have been transferred to the memory  914  for execution, to perform the various functions described above. 
     The device  900  may include communications circuitry  902 . Communications circuitry  902  may include components used for wired or wireless communications, such as two-way conversations and data transfers. For example, communications circuitry  902  may include RF communications circuitry that is coupled to an antenna, so that the user of the device  900  can place or receive a call through a wireless communications network. The RF communications circuitry may include a RF transceiver and a cellular baseband processor to enable the call through a cellular network. For example, communications circuitry  902  may include Wi-Fi communications circuitry so that the user of the device  900  may place or initiate a call using voice over Internet Protocol (VOIP) connection, transfer data through a wireless local area network. 
     The device may include a microphone  920 . Microphone  920  may be an acoustic-to-electric transducer or sensor that converts sound in air into an electrical signal. The microphone circuitry may be electrically connected to processor  912  and power source  910  to facilitate the microphone operation (e.g., tilting). 
     The device  900  may include a motion sensor  904 , also referred to as an inertial sensor, that may be used to detect movement of the device  900 . The motion sensor  904  may include a position, orientation, or movement (POM) sensor, such as an accelerometer, a gyroscope, a light sensor, an infrared (IR) sensor, a proximity sensor, a capacitive proximity sensor, an acoustic sensor, a sonic or sonar sensor, a radar sensor, an image sensor, a video sensor, a global positioning (GPS) detector, an RF or acoustic doppler detector, a compass, a magnetometer, or other like sensor. For example, the motion sensor  904  may be a light sensor that detects movement or absence of movement of the device  900 , by detecting the intensity of ambient light or a sudden change in the intensity of ambient light. The motion sensor  904  generates a signal based on at least one of a position, orientation, and movement of the device  900 . The signal may include the character of the motion, such as acceleration, velocity, direction, directional change, duration, amplitude, frequency, or any other characterization of movement. The processor  912  receives the sensor signal and controls one or more operations of the device  900  based in part on the sensor signal. 
     The device  900  also includes camera circuitry  906  that implements the digital camera functionality of the device  900 . One or more solid state image sensors are built into the device  900 , and each may be located at a focal plane of an optical system that includes a respective lens. An optical image of a scene within the camera&#39;s field of view is formed on the image sensor, and the sensor responds by capturing the scene in the form of a digital image or picture consisting of pixels that may then be stored in storage  908 . The camera circuitry  906  may also be used to capture video images of a scene. 
     Device  900  also includes primary power source  910 , such as a built in battery, as a primary power supply. 
     While certain embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that the invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. For example, the various speaker components described herein could be used in an acoustic-to-electric transducer or other sensor that converts sound in air into an electrical signal, such as for example, a microphone. The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20170911
Publication Date: 20190521
Grant Date: 20190521
Priority Date: 20170911
Inventors: GRAZIAN, ANTHONY P.
WILK, CHRISTOPHER
NOTARANGELO, Claudio
TAO, HONGDAN
NEWMAN, MICHAEL J.
ILKORUR, ONUR I.
TSANG, THOMAS H.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R9/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2201/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2811", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/2811", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/2811", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/021", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2499/15", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R9/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2201/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R9/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/021", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2499/15", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 63734549