Vibration and force cancelling transducer assembly

An acoustic device comprising an enclosure having an enclosure wall that defines an enclosure volume; a first mass movably coupled to the enclosure, the first mass comprising a sound radiating surface, a voice coil and a first suspension member; a second mass movably coupled to the enclosure, the second mass comprising a magnet assembly and a second suspension member, and wherein the first suspension member couples the first mass to the second mass, the second suspension member couples the magnet assembly to the enclosure wall, and the second suspension member is tuned to reduce enclosure vibrations caused by a movement of the first mass and the second mass relative to the enclosure.

FIELD

An aspect of the disclosure is directed to a vibration and force cancelling transducer assembly including a transducer assembly having tuned stiffnesses and masses for vibration and force cancelling. Other aspects 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 speakers 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. The speakers incorporated within these devices may use a moving coil motor to drive sound output. The moving coil motor may include a diaphragm, voice coil and magnet assembly positioned within a frame. In some cases, however, the force output by the moving coil motor may be transmitted to the device enclosure, causing an undesirable rattling, shaking or hopping of the system.

SUMMARY

An aspect of the disclosure is directed to a transducer assembly (e.g., a loudspeaker), which provides a force-balancing construction to eliminate, or reduce, forces that may be transmitted to the system in which the transducer is installed or integrated, while maximizing the acoustic output. For example, an operating loudspeaker can cause dynamic imbalances that cause the product to excessively vibrate or slide along a surface. This movement may be up and down, to the side, a rotation, or a combination of these movements. The product can literally “hop” and momentarily lose contact with the surface it is on, or it can only lose its grip (but not leave the surface), but instead slide or “walk” over time along a table for example. Sometimes the product's bottom will maintain its position on the table, if for example mounted on soft springs like foam pads/feet, while the enclosure may still be vibrating with large amplitudes. This can also be undesirable because vibrations can interfere with the function of cameras in the product, making it hard to view product displays (appear blurry), or affect the user experience of touching button/controls on the product. Even if the product is turned off, pressing controls on a “squishy” product can hurt the user experience. Alternatively, if a product is mounted to a wall with screws for example, the dynamic imbalance can stress the attachment joints, potentially causing fatigue and failure, or cause the wall to vibrate.

The dynamic imbalances can be either force imbalances, moment imbalances, or both. An example of a force imbalance on the case without a moment imbalance may be a single axisymmetric transducer mounted in the center of a symmetric sealed box enclosure. Because of symmetry, there is no moment applied to the enclosure. An example of a moment imbalance on the case without a force imbalance may be two identical transducers mounted on opposite sides of a sealed box, moving acoustically in phase (mechanically out of phase), but not positioned in-line with each other. This causes a moment/couple, which can lead to rotations/rocking of product.

The instant disclosure is directed to a transducer assembly having a stiffness (or other parameter) that is tuned for reducing or eliminating imbalanced dynamic forces within the system which can cause the product to excessively vibrate or “hop” along a surface. The “stiffness” may be understood herein as referring to the extent to which the object resists deformation in response to an applied force and/or the measure of the resistance offered by the body to deformation. Representatively, in one aspect, the disclosure is directed to a transducer assembly having a spring or other compliant member with a constant k2between the transducer and the case/enclosure. For a sealed box configuration (e.g., no ports, passive radiators, etc), this configuration can perfectly cancel forces on the case at a number of frequencies where the k2and the damping in the spring have particular parameters that depend on other parameters in the speaker (e.g., diaphragm radiating mass (m1), hardware radiating mass (m2), back volume (kbox), m1radiating area (s1), m2radiating area (s2), s1stiffness (k1), damping in other spring and leak). One representative equation for perfect force cancelling may be as follows:

It should be noted that if k2is a complex value (e.g. includes damping/loss), the right side of the equation may also be complex, so that kbox has the same fraction of damping as the k2term. In some aspects, the same performance may be achieved where s2=0, which may allow for a top area of the assembly to be smaller.

In addition, it may be recognized that since a matched k2may depend on stiffness of the kbox, and the stiffness of the kbox may depend on the atmospheric pressure, which may in turn depend on elevation, errors in force canceling may occur from operating the product at a different altitude then the force canceling was optimized for. In addition, if the properties of the mechanical springs with constant k2change with temperature, that may also affect the force canceling performance. Thus, in some aspects, the disclosure further provides for a spring or other compliant member stiffness (k2) that uses an air spring (k2a) and a mechanical spring (k2m) instead of just a mechanical spring (k2=k2m+k2a). In still further aspects the vibration and force cancelling transducer assembly may include ports or passive radiators.

Representatively, in one aspect, the disclosure provides an acoustic device including an enclosure having an enclosure wall that defines an enclosure volume; a first mass movably coupled to the enclosure, the first mass comprising a sound radiating surface, a voice coil and a first suspension member; a second mass movably coupled to the enclosure, the second mass comprising a magnet assembly and a second suspension member, and wherein the first suspension member couples the first mass to the second mass, the second suspension member couples the magnet assembly to the enclosure wall, and the second suspension member is tuned to reduce enclosure vibrations caused by a movement of the first mass and the second mass relative to the enclosure. In some aspects, the second suspension member is tuned by balancing a stiffness of the second suspension member relative to a stiffness of the enclosure volume. In some aspects, only the first mass defines a radiating surface area of the transducer assembly. The first suspension member is out of plane relative to the second suspension member. In some aspects, a back volume is formed between the first mass and the second mass, and further comprises a vent port formed through the second mass to vent the back volume to the enclosure volume. The second suspension member may include a mechanical spring component and an air spring component. The mechanical spring component may include a first stiffness and the air spring component comprises a second stiffness that is different from the first stiffness. In some aspects, a ratio of the first stiffness to the second stiffness is less than about 1. In some aspects, the spring component may have a spring volume defined by a spring enclosure fixedly coupled to the enclosure, and the mechanical spring component couples the second mass to the air spring component. In some aspects, the spring volume has a first stiffness, the enclosure volume is isolated from the spring volume and includes a second air stiffness, and both the first air stiffness and the second air stiffness change proportionally in response to atmospheric pressure changes. In some aspects, a vent port is formed through the mechanical spring component to vent the spring volume to an ambient environment. The mechanical spring component may include a piston and a surround coupling the second mass to the spring volume. In some aspects, the air spring component may include a spring volume defined by a bottom portion of the magnet assembly, the enclosure wall and a surround coupling the magnet assembly to the enclosure wall, and wherein the spring volume is isolated from the enclosure volume. In some aspects, the device further includes a vent port formed through the enclosure wall to vent the enclosure volume to an ambient environment. In some aspects, a third suspension member coupling the magnet assembly to the enclosure wall.

In another aspect, the disclosure is directed to a transducer assembly including an enclosure having an enclosure wall that defines an enclosure volume; a transducer positioned within the enclosure volume, the transducer having a sound radiating surface and a voice coil coupled to a magnet assembly by a first suspension member, the first suspension member allows the sound radiating surface and the voice coil to move relative to the magnet assembly along an axis of vibration, and the magnet assembly is coupled to the enclosure by a second suspension member, the second suspension member includes an air spring component that allows the magnet assembly to move relative to the enclosure. In some aspects, the air spring component defines a compliant air volume that is isolated from the enclosure volume, and wherein a stiffness of the compliant air volume and the enclosure volume change proportionally in response to atmospheric pressure changes. In some aspects, the second suspension member includes a piston coupling the magnet assembly to a surround defining a compliant air volume of the air spring component that allows the magnet assembly to move relative to the enclosure. In some aspects, the surround is attached to a spring enclosure fixedly coupled to the enclosure wall, and the surround in combination with the spring enclosure define the compliant air volume. The second suspension member includes a first surround and a second surround that are out of plane relative to one another and couple the magnet assembly to the enclosure, the enclosure volume is between the first and second surround, and a compliant air spring volume of the air spring component is between the second surround and a bottom enclosure wall such that the compliant air spring volume is positioned below the magnet assembly.

In another aspect, the disclosure is directed to a transducer assembly including an enclosure having a bottom enclosure wall and a side enclosure wall that together define an enclosure volume; a first mass movably coupled to the enclosure and defining a first radiating area, the first mass comprising a sound radiating surface, a voice coil and a first suspension member coupling the sound radiating surface to the enclosure such that the sound radiating surface is operable to vibrate relative to the enclosure along an axis of vibration; a second mass movably coupled to the enclosure and defining a second radiating area, the second mass comprising a magnet assembly and a second suspension member coupling the magnet assembly to the enclosure; and a third mass movably coupled to the enclosure and defining a third radiating area, the third mass comprising a passive radiator and a third suspension member coupling the passive radiator to the enclosure, and wherein the first radiating area and the second radiating area have a combined radiating area that is different than the third radiating area and the combined radiating area is balanced relative to the third radiating area to reduce enclosure vibrations caused by a movement of the first mass and the second mass relative to the enclosure. In some aspects, the first suspension member is axially aligned with the second suspension member. In some aspects, an effective radiating area of the second mass is zero. In some aspects, the second suspension member coupling the magnet assembly to the enclosure includes a first surround and a second surround that are out of plane relative to one another. The passive radiator may be a first passive radiator that forms part of the bottom enclosure wall and the assembly may further include a second passive radiator that forms part of the side enclosure wall. The third mass may form part of the bottom enclosure wall and separates the enclosure volume from an ambient environment outside of the enclosure. In some aspects, the enclosure further includes an interior enclosure wall that separates the enclosure volume from a passive volume between the bottom enclosure wall and the passive radiator of the third mass. In some aspects, the passive radiator forms part of the bottom enclosure wall, and the interior enclosure wall further comprises a port between the enclosure volume and the passive volume. In other aspects, the passive radiator may form part of the interior enclosure wall, and the bottom enclosure wall further comprises a port between the passive volume and an ambient environment outside of the enclosure. In some aspects, the passive radiator is a first passive radiator forming part of the bottom enclosure wall, and the assembly further includes a fourth mass defining a fourth radiating area, the fourth mass comprising a second passive radiator and a fourth suspension member coupling the second passive radiator to the interior enclosure wall.

In another aspect, the disclosure is directed to an acoustic device including an enclosure having a bottom enclosure wall and a side enclosure wall that together define an enclosure volume; a transducer positioned within the enclosure volume, the transducer having a sound radiating surface and a voice coil coupled to a magnet assembly by a first suspension member, the first suspension member allows the sound radiating surface and the voice coil to move relative to the magnet assembly along an axis of vibration, and the magnet assembly is coupled to the enclosure by a second suspension member; a first passive radiator coupled to the enclosure by a third suspension member; and a second passive radiator coupled to the enclosure by a fourth suspension member. In some aspects, the first passive radiator is coupled to the side enclosure wall and provides lateral force cancelling. In some aspects, the first passive radiator is coupled to the bottom enclosure wall and provides axial force cancelling. In some aspects, the first passive radiator is coupled to the side enclosure wall and the second passive radiator is coupled to the bottom enclosure wall. The enclosure may further include an interior enclosure wall that runs parallel to the bottom enclosure wall, and wherein the first passive radiator is coupled to the bottom enclosure wall and the second passive radiator is coupled to the interior enclosure wall. In some aspects, the enclosure further includes an interior enclosure wall that defines a passive volume between the first passive radiator and the bottom enclosure wall, and the interior enclosure wall may include an opening from the passive volume to the enclosure volume. In some aspects, the first passive radiator is coupled to an interior enclosure wall that defines a passive volume between the first passive radiator and the bottom enclosure wall, and wherein the bottom enclosure wall comprises an opening from the passive volume to an ambient environment surrounding the enclosure. The opening may include a channel that is axially aligned with the axis of vibration. The first passive radiator may define a first radiating area and the second passive radiator defines a second radiating area, and the first radiating area is different than the second radiating area. In some aspects, the device may further include a vent port formed through the magnet assembly that couples a back volume of the transducer to the enclosure volume, or through the enclosure and couples the enclosure volume to an ambient environment surrounding the enclosure.

DETAILED DESCRIPTION

In this section we shall explain several preferred aspects of this disclosure with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the aspects are not clearly defined, the scope of the disclosure 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 aspects of the disclosure 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.

FIG.1illustrates a cross-sectional side view of an aspect of a transducer assembly. Transducer assembly100may, for example, include an electro-acoustic transducer that converts electrical signals into audible signals that can be output from a device within which transducer assembly100is integrated. For example, transducer assembly100may include a speaker integrated within any type of audio output acoustic device. Transducer assembly100may be enclosed within a housing or enclosure of the device within which it is integrated.

Transducer assembly100may generally include a first mass102, a second mass104and a third mass106which are movably coupled to one another such that they move relative to one another. The first mass102and the second mass104may, in some aspects, be considered components of an electro-acoustic transducer124. The third mass106may be the enclosure, housing, case or module that the transducer100is coupled to. In some aspects, third mass106is the enclosure, housing, case or module of the device within which the transducer assembly100is integrated. In this aspect, the enclosure, housing, case or module may separate the components coupled thereto from a surrounding ambient environment.

Referring now in more detail to first mass102, first mass102may include a sound radiating surface110, a bobbin112, a voice coil114coupled to bobbin112, and a suspension member116. Although bobbin112is included in this configuration, it should be understood that bobbin112is optional and could be omitted, in which case voice coil114may be directly attached to sound radiating surface110. Sound radiating surface110may be, for example, a speaker diaphragm or another type of flexible membrane (which may include a number of material layers) capable of vibrating in response to an acoustic signal to produce acoustic or sound waves. The sound radiating surface110may include a top surface, face or side that is considered a sound radiating surface, face or side (or top surface, face or side in this view) in that it generates a sound that is output by the transducer assembly100. In some aspects, the top surface, face or side may be acoustically coupled to a front volume chamber and/or an acoustic output port of the transducer assembly100or the device within which the transducer assembly100is integrated. A bottom surface, face or side may be acoustically isolated from the top surface, face or side, and considered an interior facing surface, face or side (or bottom side in this view) of sound radiating surface110, which is acoustically coupled to a back volume (Vb) chamber of transducer assembly100. In some aspects, the back volume (Vb) may be formed between the first mass102and the second mass104and separated from other air volumes within the assembly. In some aspects, back volume (Vb) may also be referred to as an interior volume. The bobbin112and the voice coil114may be attached to the bottom surface, face or side of sound radiating surface110, and they may be suspended from the second mass104by suspension member116. The suspension member116may be a flexible or compliant member (e.g., a membrane) which, in one aspect, is attached near an edge of the sound radiating surface110and allows for vibration of sound radiating surface110in directions parallel to an axis of translation or vibration118. The axis of vibration118may, for example, be parallel to the z-axis of assembly100. In still further aspects, the axis of vibration118may be considered parallel to, or running in the same direction as, the winding height of voice coil114. The axis of vibration118may also be referred to herein as the axis of symmetry for the transducer assembly100. In other words, while only one side of the transducer assembly100is shown, it may be understood as having a second side that is symmetrical, and otherwise identical, to that which is shown.

Referring now in more detail to second mass104, second mass104may include hardware components of the transducer100. For example, second mass104may include a magnet assembly120and a basket122. In some aspects, magnet assembly120may include one or more magnets (e.g., permanent magnets) and a yoke that form a gap within which voice coil114is positioned. The magnets and yoke in combination form a magnetic circuit or magnetic return path for a magnetic field used tp1o drive a movement of voice coil114(and in turn sound radiating surface110) along the axis of vibration118. The magnet assembly120may be coupled basket122and a suspension member126may attach the basket122to third mass106. The suspension member126may be a flexible or otherwise compliant member that allows second mass104(e.g., magnet assembly120and basket122) to move relative to third mass106. In addition, the suspension member116of first mass102may be attached to another portion of basket122such that first mass102moves relative to both second mass104and third mass106. In some aspects, the suspension member116of the first mass102is out of plane and axially aligned with the suspension member126of the second mass104as shown. In this configuration, a radiating surface area of second mass104may be understood as being effectively zero and therefore does not significantly impact the force cancelling performance of the system as will later be described in more detail.

Referring now in more detail to third mass106, as previously discussed, third mass106may be the enclosure, housing, case or module of the device that the first mass102and second mass104are coupled to and/or within which the transducer assembly100is integrated. In this aspect, where the third mass106is the enclosure, it may have a side enclosure wall106A and a bottom enclosure wall106B that together define an enclosure volume (Vbox). The enclosure volume (Vbox) may be a volume of air that is separated from the surrounding ambient environment by the enclosure walls106A,106B. In addition, the enclosure volume (Vbox) may be separated from the back or interior volume (Vb) by the second mass104. The enclosure volume (Vbox) may have a pressure (P) which may be a parameter than can impact a movement of the second mass104within the enclosure volume (Vbox). Said another way, the enclosure volume (Vbox) may be considered an air spring in that it may have a compliance or stiffness that can impact a movement of the second mass104. In some aspects, an air vent or leak port or opening132may be formed between enclosure volume (Vbox) and interior volume (Vb), or an air vent or leak port or opening134may be formed between the enclosure volume (Vbox) and the ambient environment. The vents or leak ports132,134may decrease a pressure within the interior volume (Vb) or enclosure volume (Vbox), which in turn may make the volume more compliant (or less stiff) as desired.

In some aspects, the third mass106may be understood as the part of the transducer assembly100subject to undesirable movements, vibrations, hopping, etc. due to force imbalances within the system and which can be made stationary by the force cancellation achieved herein. Representatively, in some aspects, one or more of the components of the system may be balanced or tuned to reduce a vibration of third mass106caused by, for example, a movement of the first mass102and second mass104relative to third mass106. For example, in one aspect, a stiffness of the suspension member126coupling the second mass104to the third mass106may be considered balanced or tuned relative to the stiffness of the enclosure volume to reduce the vibration of the third mass106.

Representatively, as previously discussed, for a sealed box configuration (e.g., no ports, passive radiators, etc), forces on the case at a number of frequencies can be cancelled where the k2and the damping in the spring (e.g., the suspension member) are tuned or otherwise balanced. One representative equation for perfect force cancelling and tuning K2may be as follows:

Representatively, in the context of assembly100ofFIG.1, first mass102(m1), may be understood as having a diameter defining a first radiating area (s1). In addition, the suspension member116of first mass102(m1) acts like a spring and may have a constant k1(e.g., stiffness) between the first mass102(m1) and the second mass104(m2). Second mass104(m2), may in some aspects, further have a diameter defining a second radiating area (s2). In the configuration illustrated inFIG.1, however, the second radiating area (s2) may be considered zero and therefore second mass104in this configuration may be considered as having effectively no surface radiating area (s2). Therefore, in this aspect, only the first mass102(m1) defines a radiating area (s1) of the assembly100. The suspension member126of second mass104(m2) may further act like a spring and have a constant k2(e.g., stiffness) between the second mass104(m2) and the third mass106(m3). The constant k2can be selected (e.g., tuned or balanced) based on the previously discussed equation. For example, the stiffness of the suspension member (k2) relative to the enclosure volume stiffness (kbox) can be tuned so that all the forces that are acting on the mass (m3) are effectively cancelled. Said another way, if the stiffness is selected so that the forces acting on first mass102(m1) and second mass104(m2) are equal and opposite, than the case displacement will be equal to zero. In addition, it should be recognized that since in this configuration, the second radiating area (s2) of second mass104is zero, the top radiating area may be smaller without impacting performance.

Referring now toFIG.2AandFIG.2B,FIG.2AandFIG.2Billustrate a transducer assembly200similar in some aspects to the assembly100ofFIG.1. Transducer assembly200, however, includes an air spring that can help minimize an impact of temperature or pressure changes on the balanced or tuned assembly. Representatively, when the transducer assembly is tuned as previously discussed at one elevation, but then changes elevation, the air stiffness of the enclosure volume (Vbox) changes proportionally to the resulting atmospheric pressure change, while the stiffness (k2) of the mechanical spring component (e.g., suspension member126) remains the same. This may, in turn, result in an assembly imbalance. In addition, different temperatures can impact the stiffness (k2) of the mechanical spring component (e.g., the spring may be stiffer at lower temperatures and less stiff at higher temperatures). Transducer assembly200solves this issue by incorporating an air spring having an air volume with a stiffness that can change similar to the enclosure volume (Vbox), and proportionally with the air/temperatures changes.

Representatively, similar to transducer assembly100, transducer assembly200may include first mass102, second mass104and third mass106. As illustrated byFIG.2A, in the absence of force cancelling as disclosed herein, the displacement (x1) of first mass102and the displacement (x2) of second mass104may cause a displacement (x3) of the third mass106. The displacement (x3) can, however, be reduced to zero when forces on first mass102and second mass104are equal and opposite. Referring now in more detail to assembly200, mass102may include sound radiating surface110, bobbin112and voice coil114coupled to second mass104by suspension member116. First mass102may have a diameter defining a radiating surface area (s1) and suspension member116may have a stiffness (k1), as previously discussed. Second mass104may include magnet assembly120and basket122that are coupled to third mass106by suspension member126. In some aspects, an optional suspension member202may further be used to couple second mass104to third mass106. The optional suspension member202may, for example, be out of plane to the suspension member126. For example, suspension member126may be near a top of second mass104and optional suspension member202may be near a bottom of second mass104to provide added stability. Third mass106may be an enclosure, case or housing having a side enclosure wall106A and a bottom enclosure wall106B that together define the enclosure volume (Vbox). In some cases, the enclosure volume (Vbox) may be vented to the back volume (Vb) of first mass102by a port or vent132or the ambient environment by a port or vent134in an enclosure wall (e.g. side enclosure wall106A). The ports or vents132,134may help to open the back volume (Vb) or enclosure volume (Vbox) and decreases back pressure, which in turn makes the space more compliant (e.g., less stiff). In addition, in some aspects, an optional passive radiator204may be formed in one of the walls of enclosure106.

Referring now in more detail to suspension member126in transducer assembly200, suspension member126includes both a mechanical component and an air spring component that allow a stiffness of suspension member126to change similar to the enclosure volume (Vbox), and proportionally with the air/temperatures changes. Representatively, suspension member126includes a spring enclosure206fixedly mounted to third mass106and a surround208which together enclose and define an air spring volume (v2). The air spring volume (v2) may define a separate air volume from the enclosure volume (Vbox). The air spring volume (v2) may have a stiffness than can change similar to the enclosure volume (Vbox) as previously discussed. A piston210is fixedly coupled at one end to the second mass104and another end to the surround208. This, in turn, movably couples the second mass104to the third mass106. In particular, the compliance of the air spring volume (v2) allows the second mass104to move relative to the third mass106. In addition, changes in the compliance or stiffness of the air spring volume (v2) are proportional to the changes in the atmosphere or temperature, and therefore the suspension member126remains tuned even at different elevations and/or temperatures.

Representatively, in referring to the previously discussed force cancelling equation and as illustrated inFIG.2A, first mass102may have a diameter defining a first radiating surface area (s1) and second mass104may have an annulus defining a second radiating surface area (s2). In addition, suspension member126may have a stiffness (k2), an annulus defining a radiating surface area (s4) and an air spring volume (v2). The stiffness (k2) is made up of an air spring (k2a) and a mechanical spring (k2m) instead of just a mechanical spring (k2=k2m+k2a). In some aspects, the mechanical component (k2m) is made small relative to the air spring component (k2a). Representatively, the mechanical component (k2m) may be just stiff enough to keep the transducer secure during operation and drop tests, as the lower the ratio of k2m/k2a, the less susceptible the force canceling performance is to elevation and temperature changes. For example, the ratio of k2m/k2amay be less than about 1 in order to gain significant robustness benefits against elevation changes, with a ratio of 0.2 being even more robust. In some aspects, the mechanical component may be made up of the piston210, surround208and spring enclosure206. The air spring component may be made up of the air spring volume (v2) and have stiffness k2a. Since the air spring volume (v2) has a stiffness (e.g., first stiffness) that changes with altitude and temperature the same way the enclosure volume (Vbox) stiffness (e.g., a second stiffness) changes, the force canceling performance will be more robust to changes in the environment. In addition, it is possible to better match the damping terms in the equation for perfect force canceling.

In some aspects, damping can be controlled by matched acoustic resistances (controlled resistive leaks) between the spring volume (v2) and external or ambient air, and between the enclosure volume (Vbox) and the external or ambient air. For example, a vent or port212may be formed through piston210such that the spring volume (v2) is vented to the external air. In addition, as previously discussed, a vent or port134may be formed through a wall of enclosure106(e.g., one of walls106A or106B) to vent the enclosure volume (Vbox) to the ambient environment. The vents or ports212,132,134may also include an acoustic mesh or screen132A to control the acoustic resistance. In still further aspects, although not shown, a vent or port may be provided between the spring volume (v2) and the enclosure volume (Vbox) (e.g., through the spring enclosure206), as well as the enclosure volume (Vbox) and the outside ambient environment, instead of between the spring volume (V2) and the ambient environment. In the disclosed configuration, force cancelling can be achieved based on the following:

FIG.3illustrates a cross-sectional side view of a transducer assembly300. Transducer assembly300is similar to transducer assembly200ofFIG.2A-Bin that it includes a first mass102, a second mass104and a third mass106. The first mass102is coupled to the second mass104by suspension member116as previously discussed. The second mass104is coupled to the third mass106by a suspension member126having both a mechanical component and an air spring component. Representatively, the suspension member126includes a spring enclosure306fixedly mounted to third mass106, a surround308A and a surround308B. The surround308A and surround308B together couple the second mass104to the third mass106. Surround308A may be out of plane to surround308B for added stability. For example, surround308A may be attached to a top portion of second mass104and surround308B may be attached to a bottom portion of second mass104. The other side of surrounds308A,308B may be attached to the side enclosure wall106A. The spring enclosure306and the surround308B in combination may enclose and define an air spring volume (v2) that is below the second mass104. The air spring volume (v2) may define a separate air volume from the enclosure volume (Vbox). The enclosure volume (Vbox) may be along a side of second mass104and between surround308A and surround308B. The air spring volume (v2) may have a stiffness and pressure (P2) that can change similar to the enclosure volume (Vbox) stiffness and pressure (P1) as previously discussed. In this aspect, the compliance of the air spring volume (v2) allows the second mass104to move relative to the third mass106. In addition, changes in the compliance or stiffness of the air spring volume (v2) are proportional to the changes in the atmosphere or temperature, and therefore the suspension member126remains tuned even at different elevations and/or temperatures.

Representatively, similar to the transducer assembly200ofFIGS.2A-B, first mass102may have a diameter defining a first radiating surface area (s1) and second mass104may have an annulus defining a second radiating surface area (s2). In addition, suspension member126may have a stiffness (k2), an annulus defining a radiating surface area (s4) and an air spring volume (v2). The stiffness (k2) may be made up of an air spring (k2a) and a mechanical spring (k2m) instead of just a mechanical spring (k2=k2m+k2a), as previously discussed. In some aspects, the mechanical component (k2m) is made small relative to the air spring component (k2a). In addition, in this configuration, both surrounds308A,308B are included in the mechanical spring component (k2m). In addition, in some aspects, the assembly300may further include a leak or port132from the back volume (Vb) to the enclosure volume (Vbox) and/or a leak or port312from the air spring volume (v2) through the bottom enclosure wall106B to the ambient environment. The vents or ports132,312may also include an acoustic mesh or screen to control the acoustic resistance as previously discussed. In the disclosed configuration, force cancelling can be achieved based on the following:

It should be understood that any of the previously discussed configurations can provide force canceling for, in some aspects, sealed enclosure configurations (e.g., sealed boxes). In the case of systems with passive radiators or ports (e.g., vented boxes), different configurations may be used to achieve force cancelling. Some representative vented box configurations will now be described in reference toFIG.4,FIG.5,FIG.6,FIG.7andFIG.8.

FIG.4illustrates a cross-sectional side view of a transducer assembly400including a passive radiator. Similar to the previously discussed transducer assemblies, transducer assembly400includes a first mass102, a second mass104and a third mass106. Each of the first mass102, second mass104and third mass106include the same components as previously discussed in reference to transducer assembly100ofFIG.1. Representatively, first mass102includes sound radiating surface110, bobbin112and voice coil114connected to second mass104by suspension member116. Second mass104includes magnet assembly120and basket122connected to third mass106by suspension member126. Suspension member116and suspension member126may be out of plane and axially aligned similar to the arrangement previously discussed in reference toFIG.1. Third mass106may be, for example, an enclosure, housing or case having a side enclosure wall106A and bottom enclosure wall106B that define an enclosure volume (Vbox). Each of the first mass102, second mass104and third mass106can move relative to one another. It is desired that third mass106, however, remain stationary therefore the assembly may be tuned as previously discussed to cancel forces causing any undesired movement of third mass106.

Transducer assembly400further includes a fourth mass408(m4) coupled to the bottom enclosure wall106B. Fourth mass408may be, in some aspects, a passive radiator (PR) that is movably coupled to bottom enclosure wall106B by suspension member410. Fourth mass408may have a diameter defining a radiating surface area (s4) that is in mutual opposition to the radiating surface area (s1) of first mass102(previously discussed in reference toFIG.1). In some aspects, the radiating surface area (s1) of first mass102is different than the radiating surface area (s4) of fourth mass408. Due to the arrangement, a radiating surface area of second mass104may be effectively zero. Suspension member126may be a spring with constant k2as previously discussed, and suspension member410may be a spring with constant k3. The k2, k3of the suspension members126,410may be tuned so that vibration-reaction forces of the first mass102, second mass104and/or fourth mass408on the third mass106(e.g., the enclosure) are effectively cancelled.

FIG.5illustrates a cross-sectional side view of a transducer assembly500including a passive radiator. Similar to the previously discussed transducer assemblies, transducer assembly500includes a first mass102, a second mass104and a third mass106. Each of the first mass102, second mass104and third mass106include the same components as previously discussed in reference to transducer assembly100ofFIG.1. Representatively, first mass102includes sound radiating surface110, bobbin112and voice coil114connected to second mass104by suspension member116. Second mass104includes magnet assembly120and basket122connected to third mass106by suspension member126. In this configuration, however, suspension member116and suspension member126may be in plane relative to one another similar to the arrangement previously discussed in reference toFIG.2A-B. Third mass106may be, for example, an enclosure, housing or case having a side enclosure wall106A and bottom enclosure wall106B that define an enclosure volume (Vbox). Each of the first mass102, second mass104and third mass106can move relative to one another.

Similar to transducer assembly300, transducer assembly400further includes a fourth mass408coupled to the bottom enclosure wall106B. Fourth mass408may be, in some aspects, a passive radiator (PR1) that is movably coupled to bottom enclosure wall106B by suspension member410. Fourth mass408may have a diameter defining a radiating surface area (s4) that is in mutual opposition to the radiating surface area (s1) of first mass102(previously discussed in reference toFIG.1) and the radiating surface area (s2) of second mass104(previously discussed in reference toFIG.2A). In some aspects, the radiating surface area (s1) of first mass102and radiating surface area (s2) of second mass together may be the same or different than the radiating surface area (s4) of fourth mass408. Suspension member126may be a spring with constant k2as previously discussed, and suspension member410may be a spring with constant k3. The k2, k3of the suspension members126,410may be tuned so that vibration-reaction forces of the first mass102, second mass104and/or fourth mass408on the third mass106(e.g., the enclosure) are effectively cancelled.

In some aspects, assembly500may further include a fifth mass508movably coupled to a side enclosure wall106A by suspension member510. Fifth mass508, in some aspects, may be a passive radiator (PR2) used to provide lateral force cancelling for added stability. It should further be understood that, although not explicitly shown, a side wall passive radiator508similar to that shown in assembly500may be included in any of the previously discussed transducer assembly configurations to provide lateral force cancelling.

FIG.6illustrates a cross-sectional side view of a transducer assembly600including a passive radiator. Similar to the previously discussed transducer assemblies, transducer assembly600includes a first mass102, a second mass104, a third mass106, a fourth mass408and optional fifth mass508. Each of the first mass102, second mass104, third mass106, fourth mass408and optional fifth mass508include the same components as previously discussed in reference to transducer assembly500ofFIG.5. Representatively, first mass102includes sound radiating surface110, bobbin112and voice coil114connected to second mass104by suspension member116. Second mass104includes magnet assembly120and basket122connected to third mass106by suspension member126. Third mass106may be, for example, an enclosure, housing or case having a side enclosure wall106A and bottom enclosure wall106B that define an enclosure volume (Vbox). Fourth mass408may be a passive radiator (PR1) movably coupled to the bottom enclosure wall106B by a suspension member410. Fifth mass508may be a passive radiator (PR2) movably coupled to the side enclosure wall106A by a suspension member510. Each of the first mass102, second mass104, third mass106, fourth mass408and optional fifth mass508can move relative to one another to provide axial/vertical force cancelling and/or lateral/horizontal force cancelling.

Transducer assembly600further includes an interior enclosure wall106C that defines a port602in front of fourth mass408. Representatively, port602may be an opening, channel or tube that is formed by the interior enclosure wall106C and connects a passive radiator volume (Vp) having a pressure (P2) with the enclosure volume (Vbox) having a pressure (P1).

Similar to the previously discussed configurations, each of the moving components may define a radiating surface area and/or stiffness that can be balanced or tuned to cancel forces on the enclosure or third mass106. Representatively, first mass102defines a radiating surface area (s1), second mass104defines a radiating surface area (s2), fourth mass408defines a radiating surface area (s4), the interior enclosure wall106C defines a fifth radiating surface area (s5), the portion of the third mass106between suspension126and the side enclosure wall106A may define a radiating surface area (s6), the annulus between the suspension member410and bottom enclosure wall106B may define a radiating surface area (s7) and the port602may have a radiating surface area (s8). The force on the third mass106(e.g., the case) may be considered balanced when the following conditions are met and the forces from k2and k3are equal and opposite, or considered approximately balanced when the following conditions are met and the forces from k2and k3are negligible:
(P1−P2)S5+P2ST=P1S6

FIG.7illustrates a cross-sectional side view of a transducer assembly700including a passive radiator. Similar to the previously discussed transducer assemblies, transducer assembly700includes a first mass102, a second mass104, a third mass106, a fourth mass408and may further include an optional fifth mass (e.g, a side passive radiator). Each of the first mass102, second mass104, third mass106, and fourth mass408may include the same components as previously discussed in reference to transducer assembly600ofFIG.6. Representatively, first mass102includes sound radiating surface110, bobbin112and voice coil114connected to second mass104by suspension member116. Second mass104includes magnet assembly120and basket122connected to third mass106by suspension member126. Third mass106may be, for example, an enclosure, housing or case having a side enclosure wall106A and bottom enclosure wall106B that define an enclosure volume (Vbox).

In this aspect, however, fourth mass408may be a passive radiator (PR1) movably coupled to the interior enclosure wall106C, instead of the bottom enclosure wall106B, by a suspension member410. Each of the first mass102, second mass104, third mass106, and fourth mass408can move relative to one another to provide axial/vertical force cancelling.

Transducer assembly600further includes a port702that is behind or below the fourth mass408. Representatively, port702may be an opening, channel or tube that is formed by the bottom enclosure wall106B and connects a passive radiator volume (Vp) having a pressure (P2) with an ambient environment outside of the enclosure.

Similar to the previously discussed configurations, each of the moving components may define a radiating surface area and/or stiffness that can be balanced or tuned to cancel forces on the enclosure or third mass106. Representatively, first mass102defines a radiating surface area (s1), second mass104defines a radiating surface area (s2), fourth mass408defines a radiating surface area (s8), the interior enclosure wall106C defines a radiating surface area (s5), the portion of the third mass106between suspension126and the side enclosure wall106A may define a radiating surface area (s6), the annulus between the port702and side enclosure wall106A may define a radiating surface area (s7) and the port702may have a radiating surface area (s4). The force on the third mass106(e.g., the case) may be considered balanced when the following conditions are met and the forces from k2and k3are equal and opposite, or considered approximately balanced when the following conditions are met and the forces from k2and k3are negligible:
(P1−P2)S5+P2S7=P1S6

FIG.8illustrates a cross-sectional side view of a transducer assembly800including a passive radiator. Similar to the previously discussed transducer assemblies, transducer assembly800includes a first mass102, a second mass104, a third mass106, a fourth mass408and a fifth mass508. Each of the first mass102, second mass104, third mass106, fourth mass408and fifth mass508may include the same components as previously discussed in reference to transducer assembly600ofFIG.6. Representatively, first mass102includes sound radiating surface110, bobbin112and voice coil114connected to second mass104by suspension member116. Second mass104includes magnet assembly120and basket122connected to third mass106by suspension member126. Third mass106may be, for example, an enclosure, housing or case having a side enclosure wall106A and bottom enclosure wall106B that define an enclosure volume (Vbox). Fourth mass408may be a passive radiator (PR1) movably coupled to the bottom enclosure wall106B by a suspension member410. Fifth mass508may be a passive radiator (PR2) movably coupled to the interior enclosure wall106C, instead of the bottom enclosure wall106B, by a suspension member510having a stiffness (k4). A passive radiator volume (Vp) having a pressure (p2) may be defined between the passive radiator (PR1) and the passive radiator (PR2) as shown. The passive radiator volume (Vp) may be separated from the enclosure volume (Vbox) by the interior enclosure wall106C and passive radiator (PR2) coupled to wall106C. Each of the first mass102, second mass104, third mass106, fourth mass408and fifth mass508can move relative to one another to provide axial/vertical force cancelling.

Similar to the previously discussed configurations, each of the moving components may define a radiating surface area and/or stiffness that can be balanced or tuned to cancel forces on the enclosure or third mass106. Representatively, first mass102defines a radiating surface area (s1), second mass104defines a radiating surface area (s2), fourth mass408defines a radiating surface area (s4), the interior enclosure wall106C defines a radiating surface area (s5), the portion of the third mass106between suspension126and the side enclosure wall106A may define a radiating surface area (s6), the annulus between the suspension410and side enclosure wall106A may define a radiating surface area (s7) and the fifth mass508including passive radiator (PR2) may define a radiating surface (s8). The force on the third mass106(e.g., the case) may be considered balanced when the following conditions are met and the forces from k2, k3and k4cancel, or considered approximately balanced when the following conditions are met and the forces from k2, k3, and k4are negligible:
(P1−P2)S5+P2S7=P1S6

FIG.9illustrates a simplified schematic perspective view of an exemplary electronic device in which a transducer assembly as described herein, may be implemented. As illustrated inFIG.9, the transducer assembly may be integrated within a consumer electronic device902such as a smart phone with which a user can conduct a call with a far-end user of a communications device904over a wireless communications network; in another example, the transducer assembly may be integrated within the housing of a tablet computer906. These are just two examples of where the transducer assembly described herein may be used; it is contemplated, however, that the transducer assembly may be used with any type of electronic device, for example, a home audio system, any consumer electronics device with audio capability, or an audio system in a vehicle (e.g., an automobile infotainment system).

FIG.10illustrates a block diagram of some of the constituent components of an electronic device in which the transducer assembly disclosed herein may be implemented. Device1000may be any one of several different types of consumer electronic devices, for example, any of those discussed in reference toFIG.9.

In this aspect, electronic device1000includes a processor1012that interacts with camera circuitry1006, motion sensor1004, storage1008, memory1014, display1022, and user input interface1024. Main processor1012may also interact with communications circuitry1002, primary power source1010, speaker1018and microphone1020. Speaker1018may be the transducer assembly described herein, for example, a micro speaker assembly. The various components of the electronic device1000may be digitally interconnected and used or managed by a software stack being executed by the processor1012. 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 processor1012).

The processor1012controls the overall operation of the device1000by performing some or all of the operations of one or more applications or operating system programs implemented on the device1000, by executing instructions for it (software code and data) that may be found in the storage1008. The processor1012may, for example, drive the display1022and receive user inputs through the user input interface1024(which may be integrated with the display1022as part of a single, touch sensitive display panel). In addition, processor1012may send an audio signal to speaker1018to facilitate operation of speaker1018.

Storage1008provides 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). Storage1008may include both local storage and storage space on a remote server. Storage1008may store data as well as software components that control and manage, at a higher level, the different functions of the device1000.

In addition to storage1008, there may be memory1014, 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 processor1012. Memory1014may include solid state random access memory (RAM), e.g., static RAM or dynamic RAM. There may be one or more processors, e.g., processor1012, that run or execute various software programs, modules, or sets of instructions (e.g., applications) that, while stored permanently in the storage1008, have been transferred to the memory1014for execution, to perform the various functions described above.

The device1000may include communications circuitry1002. Communications circuitry1002may include components used for wired or wireless communications, such as two-way conversations and data transfers. For example, communications circuitry1002may include RF communications circuitry that is coupled to an antenna, so that the user of the device1000can 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 circuitry1002may include Wi-Fi communications circuitry so that the user of the device1000may 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 speaker1018. Speaker1018may be a transducer assembly such as that described in reference toFIGS.1-9. Speaker1018may be an electric-to-acoustic transducer or sensor that converts an electrical signal input (e.g., an acoustic input) into sound. The circuitry of the speaker may be electrically connected to processor1012and power source1010to facilitate the speaker operations as previously discussed (e.g, diaphragm displacement, etc).

The device1000may further include a motion sensor1004, also referred to as an inertial sensor, that may be used to detect movement of the device1000, camera circuitry1006that implements the digital camera functionality of the device1000, and primary power source1010, such as a built in battery, as a primary power supply.

While certain aspects have been described and shown in the accompanying drawings, it is to be understood that such aspects are merely illustrative of and not restrictive on the broad disclosure, and that the disclosure 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. The description is thus to be regarded as illustrative instead of limiting. In addition, to aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.