Acoustic device and holder for flattening frequency response

Abstract

To provide an acoustic device having a flatter frequency response.SOLUTION: An acoustic device includes a first sound producing component and a back cavity structure. The first sound producing component has a first front side and a first back side, where the first sound producing component is a high frequency sound unit, and the first front side faces a sound propagating opening of the acoustic device. The back cavity structure is connected to the first back side of the first sound producing component. The first sound producing component produces a first acoustic wave from the first front side towards the sound propagating opening, and the first sound producing component produces a second acoustic wave from the first back side towards a back cavity of the back cavity structure. The back cavity structure is configured to flatten a peak or dip of a frequency response of the first sound producing component.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] TECHNICAL FIELD This application relates to acoustic devices and holders, and more particularly to acoustic devices and holders capable of flattening frequency responses. [Background technology]

[0002] Acoustic devices including MEMS (microelectromechanical systems) acoustic components (e.g., MEMS sound-generating components or MEMS microphones) have been rapidly developed in recent years because they can be widely used in various electronic devices due to their small size. Usually, the performance of an acoustic device is related to the frequency response of the acoustic device. Therefore, in order to improve the performance of an acoustic device, the acoustic device needs to be designed to have an appropriate frequency response. Summary of the Invention

[0003] SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to provide an acoustic device that has a flatter frequency response.

[0004] One embodiment of the present invention provides an acoustic device including a first sound-generating component and a back cavity structure. The first sound-generating component has a first front side and a first rear side, and the first sound-generating component is a high-frequency sound unit. The first front side faces a sound-propagating opening of the acoustic device. The back cavity structure is connected to the first rear side of the first sound-generating component. The first sound-generating component generates a first acoustic wave from the first front side toward the sound-propagating opening, and the first sound-generating component generates a second acoustic wave from the first rear side toward a back cavity of the back cavity structure. The back cavity structure is configured to flatten peaks or dips in the frequency response of the first sound-generating component.

[0005] Another embodiment of the present invention provides a holder for placement within an acoustic device. The holder includes a back cavity structure formed therein. When the holder is placed within the acoustic device, a first sound-generating component is placed on the holder, and the back cavity structure is connected to a first rear side of the first sound-generating component. The first sound-generating component generates a first acoustic wave from the first front side toward the sound-propagating opening of the acoustic device, and the first sound-generating component generates a second acoustic wave from the first rear side toward the back cavity of the back cavity structure. The first sound-generating component is a high-frequency sound unit. The length of the acoustic path within the back cavity is a half wavelength or a quarter wavelength corresponding to a frequency such that the frequency response of the first sound-generating component at that frequency is flattened.

[0006] These and other objectives of the present invention will no doubt become obvious to those skilled in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a cross-sectional view showing an acoustic device according to an embodiment of a first type of the present invention; [Figure 2] 1 is a schematic diagram showing a back cavity structure of an acoustic device according to an embodiment of the first type of the present invention. [Figure 3] 1 is a schematic diagram showing a back cavity structure of an acoustic device according to an embodiment of the first type of the present invention. [Figure 4] 3 is a schematic diagram of a cross-sectional view showing an acoustic device according to a second type of embodiment of the present invention; FIG. [Figure 5] FIG. 2 is a schematic diagram showing an acoustic device according to a second type of embodiment of the present invention. [Figure 6] 6 is a schematic diagram illustrating the path of an acoustic wave in the acoustic device according to the embodiment shown in FIG. 5. [Figure 7] 10 is a schematic diagram showing a top view of a holder for an acoustic device according to an embodiment of the second type of the present invention; FIG. [Figure 8]FIG. 10 is a schematic diagram showing a bottom view of a holder for an acoustic device according to an embodiment of the second type of the present invention. [Figure 9] FIG. 2 is a schematic diagram showing an acoustic device according to a second type of embodiment of the present invention. [Figure 10] 10 is a schematic diagram illustrating the path of an acoustic wave in the acoustic device according to the embodiment shown in FIG. 9. [Figure 11] FIG. 2 is a schematic diagram illustrating a membrane of a sound-producing component according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] In order to provide those skilled in the art with a better understanding of the present invention, preferred embodiments and typical material or range parameters for important components are detailed in the following description. These preferred embodiments of the present invention are shown in the accompanying drawings with numbered elements to detail the contents and effects to be achieved. Please note that the drawings are simplified schematic diagrams, and the materials and parameter ranges of important components are exemplary based on current technology. Therefore, only the components and combinations associated with the present invention are shown to provide a clearer explanation of the basic structure, implementation, or operation method of the present invention. In reality, the components are more complex, and the ranges of parameters or materials used may develop as technology advances in the future. In addition, for ease of explanation, the components shown in the drawings may not represent their actual number, shape, and dimensions, and details may be adjusted according to design requirements.

[0009] In the following description and in the claims, the terms "include," "comprise," and "have" are used in an open-ended manner and should therefore be interpreted to mean "include, but not limited to...." Thus, when the terms "include," "comprise," and / or "have" are used in describing the invention, they point to the presence of corresponding features, areas, steps, operations, and / or components, but are not limited to the presence of one or more corresponding features, areas, steps, operations, and / or components.

[0010] In the following description and claims, when "an A1 component is formed by / from B1," B1 is present in the formation of the A1 component or B1 is used in the formation of the A1 component, and does not exclude the presence and use of one or more other features, areas, steps, operations and / or components in the formation of the A1 component.

[0011] In the following description and claims, the term "substantially" generally means that there may or may not be a small deviation. For example, the terms "substantially parallel" and "substantially along" mean that the angle between two components may be equal to or less than a certain angle threshold, for example, 10 degrees, 5 degrees, 3 degrees, or 1 degree. For example, the term "substantially aligned" means that the deviation between two components may be equal to or less than a certain difference threshold, for example, 2 μm or 1 μm. For example, the term "substantially the same" means that the deviation is, for example, within 10% of a given value or range, or within 5%, 3%, 2%, 1%, or 0.5% of a given value or range.

[0012] In this description and the following claims, the term "horizontal direction" generally refers to a direction parallel to a horizontal plane, the term "horizontal surface" generally refers to a plane parallel to direction X and direction Y in the drawing (i.e., direction X and direction Y in the present invention can be considered as the horizontal direction), and the term "vertical direction" generally refers to a direction parallel to direction Z in the drawing and perpendicular to the horizontal, with direction X, direction Y, and direction Z being perpendicular to each other. In this description and the following claims, the term "top view" generally refers to a display result seen along a vertical direction. In this description and the following claims, the term "cross-sectional view" generally refers to a display result seen along a horizontal direction of a structure cut along a vertical direction.

[0013] Terms such as "first," "second," and "third" may be used to describe various components, but such components are not limited by these terms. These terms are used herein only to distinguish one component from another, and unless otherwise specified herein, these terms do not relate to the order of manufacture. The claims may not use the same terms, but instead may use terms such as "first," "second," and "third" in relation to the order in which the elements are claimed. Thus, in the following description, a "first" component may be the "second" component in a claim.

[0014] It should be noted that the technical features in the different embodiments described below can be replaced, rearranged, or mixed with each other to form another embodiment without departing from the spirit of the present invention.

[0015] In the present invention, an acoustic device may include an acoustic transducer configured to perform acoustic transduction, which may convert a signal (e.g., an electrical signal or other suitable type of signal) into an acoustic wave, or may convert an acoustic wave into another suitable type of signal (e.g., an electrical signal). In some embodiments, the acoustic transducer may be, but is not limited to, a sound-generating component, a speaker, a microspeaker, or other suitable device for converting an electrical signal into an acoustic wave. In some embodiments, the acoustic transducer may be, but is not limited to, a sound-measuring device, a microphone, or other suitable device for converting an acoustic wave into an electrical signal. For example, in the following, the acoustic device may be, but is not limited to, an earphone or an earbud, and the acoustic transducer may be, but is not limited to, a sound-generating component.

[0016]

[0023] Referring to Figure 1, Figure 1 is a schematic diagram of a cross-sectional view illustrating an acoustic device according to an embodiment of a first type of the present invention. As shown in Figure 1, the acoustic device 100 includes a first sound-generating component 110, and optionally a second sound-generating component 120, where the first sound-generating component 110 and the second sound-generating component 120 are configured to perform acoustic transduction to convert electrical signals into acoustic waves.

[0017] The frequency ranges of the acoustic waves generated by the first sound-generating component 110 and the second sound-generating component 120 may be designed based on requirement(s). For example, in one embodiment, the first sound-generating component 110 may generate acoustic waves having a frequency higher than a specific frequency to function as a high-frequency sound unit (tweeter), and the second sound-generating component 120 may generate acoustic waves having a frequency lower than another specific frequency to function as a low-frequency sound unit (woofer). That is, the first sound-generating component 110 may generate acoustic waves within a first frequency range, and the second sound-generating component 120 may generate acoustic waves within a second frequency range, where neither the first nor the second frequency range completely covers the human audible frequency range (e.g., 20 Hz to 20 kHz), and the average value of the first frequency range is higher than the average value of the second frequency range, but this is not limiting. It was noted that the particular frequency may be, but is not limited to, a value in the range of 800 Hz to 4 kHz (e.g., 1.44 kHz).

[0018] In one embodiment, the first sound-generating component 110 may be a micro-speaker, and the dimensions (e.g., length or width) of the micro-speaker may be less than 15 mm or even less than 10 mm, and the thickness (height) of the micro-speaker may be less than 2 mm, but is not limited to this. Furthermore, the first sound-generating component 110 may be fabricated via a MEMS (micro-electromechanical systems) fabrication process, but is not limited to this.

[0019] The first sound-generating component 110 may include a first membrane. The membrane design of / for the first sound-generating component 110 is not limited. In one embodiment, the first membrane of the first sound-generating component 110 may have a membrane resonance frequency greater than 13 KHz or 20 KHz and may follow design principles disclosed in, but not limited to, U.S. Pat. Nos. 10,805,751 or 11,057,716.

[0020] In one embodiment, the (compact) membrane design disclosed in U.S. Pat. No. 11,172,300 or application Ser. No. 17 / 720,333 may be utilized within the first sound-generating component 110. Specifically, the first sound-generating component 110 may include a first membrane 112, which may include membrane sub-portions 112a and 112b, on which actuators 113a and 113b, respectively, may be disposed, as shown in FIG. 11 , with membrane sub-portion 112a located opposite membrane sub-portion 112b in a top view. Specifically, membrane sub-portion 112a may include a fixed edge AE1 and a release edge RE1, and membrane sub-portion 112b may include a fixed edge AE2 and a release edge RE2. The release edge RE1 may be located opposite release edge RE2 in a top view. In one embodiment, the aspect ratio of the membrane 112 or the aspect ratio of the first sound-generating component 110 may be greater than 2, the aspect ratio being the ratio of its length (corresponding to the longer side) to its width (corresponding to the shorter side).

[0021] The contents of Patent Nos. 10,805,751, 11,057,716, 11,172,300 and Application No. 17 / 720,333 are incorporated herein by reference.

[0022] In one embodiment, the second sound-generating component 120 may be realized by, but is not limited to, a MEMS device / chip, a dynamic driver (DD), or a balanced armature driver (BA).

[0023] For example, in another embodiment, the first sound-generating component 110 and the second sound-generating component 120 may generate acoustic waves having a frequency range that covers the human audible frequency range (e.g., 20 Hz to 20 kHz), but is not limited to this.

[0024] In the present invention, the first sound-generating component 110 may be a MEMS chip or package having a first membrane, and the second sound-generating component 120 may be a MEMS chip or package having a second membrane, and the first membrane and the second membrane are actuated through an actuator to generate acoustic waves. For example, the first sound-generating component 110 may have a first membrane and actuator(s) that actuate the first membrane, and the second sound-generating component 120 may have a second membrane and actuator(s) that actuate the second membrane.

[0025] The first and second membranes may be actuated by any suitable actuation method. In the present invention, the actuator has a monotonic electromechanical transduction function for the movement of the membrane along a certain direction (e.g., the Z direction). In some embodiments, the actuator may include, but is not limited to, a piezoelectric actuator, an electrostatic actuator, a nanoscopic electrostatic drive (NED) actuator, an electromagnetic actuator, or any other suitable actuator. For example, in one embodiment, the actuator may include, but is not limited to, a piezoelectric actuator, which may include, for example, two electrodes and a piezoelectric material layer (e.g., lead zirconate titanate, PZT) disposed between the electrodes, and the piezoelectric material layer may actuate the membrane based on a drive signal (e.g., a drive voltage and / or a drive voltage difference between the two electrodes) received by the electrodes. For example, in another embodiment, the actuator may include, but is not limited to, an electromagnetic actuator (e.g., a planar coil), which may actuate the membrane based on a received drive signal (e.g., a drive current) and a magnetic field (i.e., the membrane may be actuated by electromagnetic force). For example, in yet another embodiment, the actuator may include, but is not limited to, an electrostatic actuator (such as a conductive plate) or an NED actuator, which may actuate the membrane based on a received drive signal (e.g., a drive voltage) and an electrostatic field (i.e., the membrane may be actuated by an electrostatic force). Hereinafter, the actuator may be, for example, a piezoelectric actuator.

[0026] 1 , the acoustic device 100 includes an outer housing structure 150, and the first sound-generating component 110 and the second sound-generating component 120 are disposed within the outer housing structure 150. In FIG. 1 , the outer housing structure 150 has a sound propagation opening 152 configured to provide a sound outlet (i.e., a user hears sound through the sound propagation opening 152), and the first front side 110 a of the first sound-generating component 110 is closer to the sound propagation opening 152 than the first rear side 110 b of the first sound-generating component 110 (i.e., the first front side 110 a and the first rear side 110 b of the first sound-generating component 110 are opposite sides). For example, but not limited to, the first front side 110 a of the first sound-generating component 110 may face the sound propagation opening 152. Optionally, the second front side 120a of the second sound-generating component 120 is closer to the sound propagation opening 152 than the second back side 120b of the second sound-generating component 120 (i.e., the second front side 120a and the second back side 120b of the second sound-generating component 120 are on opposite sides). For example, but not limited to, the second front side 120a of the second sound-generating component 120 may face the sound propagation opening 152.

[0027] In the present invention, the first sound-generating component 110 and the second sound-generating component 120 may be arranged in any suitable manner within the outer housing structure 150. As shown in Figure 1, the acoustic device 100 includes a holder 140 in which the first sound-generating component 110 and the second sound-generating component 120 are arranged, and the holder 140 is arranged within and fixed to the outer housing structure 150 so that the first sound-generating component 110 and the second sound-generating component 120 are arranged within the outer housing structure 150.

[0028] 1 , the first sound-generating component 110 is disposed on a first holding side 142 of the holder 140, and the second sound-generating component 120 is disposed on a second holding side 144 of the holder 140, the second holding side 144 being opposite the first holding side 142. For example, but not limited to, the first back side 110b of the first sound-generating component 110 may face the first holding side 142 of the holder 140, and the second front side 120a of the second sound-generating component 120 may face the second holding side 144 of the holder 140.

[0029] Holder 140 may include any suitable material and may be formed by any suitable method. For example, holder 140 may include a polymer, a metal, any other suitable material, or a combination thereof. For example, but not limited to, holder 140 may be formed by a molding process.

[0030] 1, the outer housing structure 150 has a first cavity CB1 and a second cavity CB2. The first cavity CB1 is located between the sound propagation opening 152 and the second cavity CB2. The first sound-generating component 110 and the second sound-generating component 120 are located between the first cavity CB1 and the second cavity CB2. For example, but not limited to, the holder 140 may be disposed between the first cavity CB1 and the second cavity CB2. For example, the first front side 110a of the first sound-generating component 110 is closer to the first cavity CB1 than the first rear side 110b of the first sound-generating component 110, and the second front side 120a of the second sound-generating component 120 is closer to the first cavity CB1 than the second rear side 120b of the second sound-generating component 120. For example, but not limited to, the first front side 110a of the first sound-generating component 110 and the second front side 120a of the second sound-generating component 120 may face the first cavity CB1, and the first back side 110b of the first sound-generating component 110 and the second back side 120b of the second sound-generating component 120 may face the second cavity CB2.

[0031] In the present invention, as shown in FIG. 1 , the first sound-generating component 110 generates a first acoustic wave AW1 from the first front side 110a toward the sound-propagating opening 152, and the first sound-generating component 110 generates a second acoustic wave AW2 from the first back side 110b, where the phase difference between the first acoustic wave AW1 and the second acoustic wave AW2 may be 180 degrees. In some embodiments, the first acoustic wave AW1 and the second acoustic wave AW2 are simultaneously generated by the first membrane of the first sound-generating component 110. In FIG. 1 , the first acoustic wave AW1 may pass through the first front side 110a of the first sound-generating component 110, the first cavity CB1, and the sound-propagating opening 152 in order. In the present invention, the second membrane of the second sound-generating component 120 generates a third acoustic wave AW3 from the second front side 120a towards the sound-propagating opening 152, and the third acoustic wave AW3 passes through the first cavity CB1 and the sound-propagating opening 152 in sequence.

[0032] 1 , the third acoustic wave AW3 propagates toward the sound propagation opening 152, and therefore the third acoustic wave AW3 must pass through the holder 140. In some embodiments, the holder 140 may include at least one air passage AP (e.g., the air passage AP is shown in FIGS. 2 and 3 ) connected between the first holding side 142 and the second holding side 144, and the third acoustic wave AW3 may pass through the air passage AP from the second holding side 144 toward the first holding side 142, resulting in the third acoustic wave AW3 propagating toward the sound propagation opening 152. Thus, as shown in FIG. 1 , the first acoustic wave AW1 propagates from the first holding side 142 of the holder 140 toward the sound propagation opening 152, and the third acoustic wave AW3 propagates from the second holding side 144 through the air passage AP toward the sound propagation opening 152.

[0033] 1, the acoustic device 100 includes a back cavity structure 130 connected to a first back side 110b of the first sound-generating component 110, with a back cavity 130i present within the back cavity structure 130. Because the back cavity structure 130 is connected to the first back side 110b of the first sound-generating component 110, the first sound-generating component 110 generates a second acoustic wave AW2 from the first back side 110b toward the back cavity 130i.

[0034] The position of the back cavity structure 130 can be designed based on requirement(s). In Fig. 1, the back cavity structure 130 can be, but is not limited to, between the first sound-generating component 110 and the second sound-generating component 120 (can be formed in the holder 140). For example, but not limited to, the back cavity structure 130 can be between the first back side 110b of the first sound-generating component 110 and the second front side 120a of the second sound-generating component 120.

[0035] In the present invention, the back cavity structure 130 may be realized in any suitable manner. In some embodiments, as shown in FIG. 1, the holder 140 may have the back cavity structure 130, and the back cavity 130i is an empty space within the holder 140, but is not limited thereto.

[0036] In principle, the frequency response of a sound-generating component is related to the performance and operation of the sound-generating component. If the frequency response of a sound-generating component has at least one obvious (or extreme) peak and / or at least one obvious (or extreme) dip, the operation of the sound-generating component requires that the signal provided to the sound-generating component to generate acoustic waves having a wavelength corresponding to the peak or dip be specially designed to avoid obvious (or extreme) high or low sound pressure levels (SPLs). In this state, the sound-generating component will be difficult to operate and will be less likely to achieve high performance in its sound-generating frequency range. Conversely, if the frequency response of a sound-generating component does not have obvious (or extreme) peaks and obvious (or extreme) dips, the sound-generating component will be easier to operate and will be more likely to achieve high performance in its sound-generating frequency range.

[0037] In the present invention, the frequency response of the first sound-producing component 110 is a measurement of the first acoustic wave AW1 in a frequency response measurement process.

[0038] In the present invention, the back cavity structure 130 is configured to flatten peaks and / or dips in the frequency response of the first sound generating component 110, and any suitable design may be applied to the back cavity structure 130 to flatten peaks and / or dips in the frequency response of the first sound generating component 110. Hereinafter, the combined structure of the first sound generating component 110 and the back cavity structure 130 will be referred to as a compensated sound producing component CPC, and the frequency response of the compensated sound producing component CPC is the measurement result of the compensated sound producing component CPC in a frequency response measurement process.

[0039] In other words, if the back cavity structure 130 is not disposed on the first rear side 110b, the frequency response of the first sound-generating component 110 may have a peak or a dip at a particular frequency. If the frequency response has a dip at a particular frequency, disposing the back cavity structure 130 (suitably designed, for example, with a half-wavelength λ / 2 acoustic path) on the first rear side 110b of the first sound-generating component 110 will increase the acoustic energy at the particular frequency. Therefore, disposing the back cavity structure on the rear side of the first sound-generating component will flatten the frequency response at the particular frequency (compared to when the back cavity structure is not disposed). On the other hand, if the frequency response has a peak at a particular frequency, disposing the back cavity structure 130 (suitably designed, for example, with a quarter-wavelength λ / 4 acoustic path) on the first rear side 110b of the first sound-generating component 110 will decrease the acoustic energy at the particular frequency. Therefore, by placing the back cavity structure on the rear side of the first sound generating component, the frequency response will be flattened at certain frequencies (compared to when there is no back cavity structure).

[0040] According to the frequency response of the first sound generating component 110, the back cavity structure 130 may be designed to be associated with at least one target peak wavelength corresponding to the target peak(s) desired to be flattened and / or at least one target dip wavelength corresponding to the target dip(s) desired to be flattened. In a comparison between the frequency response of the first sound generating component 110 and the frequency response of the compensation sound generating component CPC, the target peak(s) and / or target dip(s) of the frequency response of the first sound generating component 110 are flattened.

[0041] It should be noted that when the target peak in the frequency response of the first sound generating component 110 is flattened, the magnitude corresponding to the target peak wavelength in the frequency response of the compensation sound generating component CPC is smaller than the magnitude of the peak corresponding to the target peak wavelength in the frequency response of the first sound generating component 110, or the peak in the frequency response of the compensation sound generating component CPC related to the target peak in the frequency response of the first sound generating component 110 is smaller (lower) than the target peak in the frequency response of the first sound generating component 110.

[0042] It should be noted that when the target dip in the frequency response of the first sound generating component 110 is flattened, the magnitude corresponding to the target dip wavelength in the frequency response of the compensation sound generating component CPC is higher than the magnitude of the dip corresponding to the target dip wavelength in the frequency response of the first sound generating component 110, or the dip in the frequency response of the compensation sound generating component CPC related to the target dip in the frequency response of the first sound generating component 110 is smaller (shallower) than the target dip in the frequency response of the first sound generating component 110.

[0043] In some embodiments, due to the presence of the back cavity structure 130, peaks and / or dips may not be as evident or extreme in the frequency response of the compensation sound generating component CPC compared to the frequency response of the first sound generating component 110.

[0044] As shown in FIG. 1, the back cavity structure 130 flattens peaks and / or dips in the frequency response of the first sound-generating component 110 as the second acoustic wave AW2 propagates from the first rear side 110b towards the back cavity 130i.

[0045] 1 , in the back cavity structure 130 of the first type TP1, the back cavity structure 130 resonates to flatten the peaks and / or dips in the frequency response of the first sound-generating component 110. When the second acoustic wave AW2 propagates towards the back cavity 130i, the back cavity structure 130 resonates at the target peak wavelength and / or target dip wavelength, causing the peaks and / or dips to be flattened by the resonance of / within the back cavity structure 130.

[0046] Similarly, when the back cavity structure 130 resonates at the target wavelength, a first compensation wave having the target wavelength is generated, which has a phase delay with respect to the first acoustic wave AW1, and interference occurs between the first compensation wave and the first acoustic wave AW1. Thus, peaks and / or dips in the frequency responses of the first sound generating component 110 and the compensation sound generating component CPC are flattened by the interference between the first compensation wave and the first acoustic wave AW1.

[0047] The value of the phase delay of the first compensating wave determines the flattening effect of the peaks and / or dips. In the present invention, the phase delay of the first compensating wave may be greater than 0 and less than the target wavelength (λ) relative to the first acoustic wave AW1. For example, when the phase delay of the first compensating wave is half the target wavelength (λ / 2) relative to the first acoustic wave AW1 (i.e., a 180-degree phase delay), the best flattening effect is achieved (e.g., destructive interference is achieved), and the peaks and / or dips are significantly flattened. For example, when the phase delay of the first compensating wave is substantially one-quarter the target wavelength (λ / 4) (i.e., a 90-degree phase delay), a significant flattening effect is achieved, and the peaks and / or dips are flattened and mitigated.

[0048] 1, in the structure of the back cavity structure 130 of the first type TP1, the back cavity structure 130 has a connection port 132 connected to the first sound-generating component 110, and a back cavity 130i is connected to the outside of the back cavity structure 130 only through the connection port 132, and the back cavity 130i can be considered to be (in the form of) a sealed back volume for the first sound-generating component 110, i.e., the back cavity structure 130 includes a sealed back volume. That is, the back cavity structure 130 is hermetically sealed except for the connection port 132. For example, the back cavity structure 130 is a resonant chamber.

[0049] The value of the phase delay of the first compensating wave may be designed based on requirement(s), and the value of the phase delay of the first compensating wave is related to the design of the back cavity structure 130. In the back cavity structure 130 having the first type TP1, at least a part of the size of the back cavity structure 130 may be designed to be related to a target wavelength (e.g., a target peak wavelength corresponding to the target peak or a target dip wavelength corresponding to the target dip) so that the target peak and / or target dip can be flattened by the back cavity structure 130.

[0050] In some embodiments, the back cavity structure 130 may include at least one sub-portion 134, and a connection port 132 is connected between the sub-portion 134 and the first sound-generating component 110, and the size of the sub-portion 134 is related / corresponding to a target wavelength / frequency. The number of the sub-portion(s) 134 and the shape of the sub-portion 134 may be designed based on the requirement(s), and the shape of the sub-portion 134 may be polygonal (i.e., rectangular or rectangular with chamfer), a shape with curved edges, or other suitable shapes.

[0051] The value of the phase delay of the first compensating wave is equal to the fractional target wavelength corresponding to the size (e.g., length) of the subportion 134. That is, at the target wavelength, the value of the phase delay of the first compensating wave is proportional to the size (e.g., length) of the subportion 134. For example, the size (e.g., length) of the subportion 134 may correspond to (e.g., be equal to) one-half (λ / 2) of the target wavelength or one-quarter (λ / 4) of the target wavelength. When the size (e.g., length) of the subportion 134 corresponds to (e.g., be equal to) one-half (λ / 2) of the target wavelength, the phase delay of the first compensation wave is one-half (λ / 2) of the target wavelength (i.e., a 180-degree phase delay) relative to the first acoustic wave AW1. When the size (e.g., length) of the subportion 134 corresponds to (e.g., be equal to) one-quarter (λ / 4) of the target wavelength, the phase delay of the first compensation wave is one-quarter (λ / 4) of the target wavelength (i.e., a 90-degree phase delay) relative to the first acoustic wave AW1. Note that λ=c / f, where c is the speed of sound and f is the corresponding target frequency.

[0052] In FIG. 1, the back cavity structure 130 may include a first sub-portion 134a and a second sub-portion 134b, and the size (e.g., length) of the first sub-portion 134a may be different from the size (e.g., length) of the second sub-portion 134b, such that the first sub-portion 134a and the second sub-portion 134b may be associated with different target wavelengths / frequencies.

[0053] As shown in Figure 2, which shows an embodiment of the back cavity structure 130 of the first type TP1 (Figure 1), the size (i.e., length) of the first sub-portion 134a is larger than the size (i.e., length) of the second sub-portion 134b, and the shapes of the first sub-portion 134a and the second sub-portion 134b are, but are not limited to, rectangular. In Figure 2, the shape of the back cavity structure 130 is, but is not limited to, rectangular.

[0054] As shown in Figure 3, which shows another embodiment of the back cavity structure 130 of the first type TP1 (Figure 1), the back cavity structure 130 may further include a third sub-portion 134c and a fourth sub-portion 134d, where the sizes (i.e., lengths) of the four sub-portions 134 are different and the shapes of the four sub-portions 134 are, but are not limited to, strip shapes with curved edges. In Figure 3, the shape of the back cavity structure 130 is, but is not limited to, a spiral (or the shapes of the sub-portions (e.g., 134a-134d) are spiral) to reduce the lateral size of the back cavity structure 130 in the horizontal direction.

[0055] The acoustic device 100 may further include any suitable structure and / or any suitable component based on requirement(s). For example, in FIG. 1, the outer housing structure 150 has, but is not limited to, an air vent 154 connected to the first cavity CB1 to improve sound quality.

[0056] As a result, in an acoustic device 100 having the first type TP1, the final acoustic wave propagating towards the outside of the acoustic device 100 is formed by the superposition of the first acoustic wave AW1, the first compensating wave, and the third acoustic wave AW3.

[0057] Referring to FIG. 4, FIG. 4 is a schematic cross-sectional view illustrating an acoustic device according to a second type embodiment of the present invention. The difference between the first type TP1 shown in FIG. 1 and the second type TP2 shown in FIG. 4 is the design of the back cavity structure 130. As shown in FIG. 4, in the acoustic device 200 of the second type TP2, it can be seen that the back cavity structure 130 is or includes an air channel 232, and the back cavity 130i is formed as the air channel 232. In the air channel 232 of the back cavity structure 130, one end of the air channel 232 is connected to the first rear side 110b of the first sound-generating component 110, and the other end of the air channel 232 faces the sound-propagating opening 152. For example, the air channel 232 of the back cavity structure 130 has an appropriate shape (e.g., a U-shape).

[0058] The air channel 232 is associated with and corresponds to a target wavelength (e.g., a target peak wavelength corresponding to a target peak or a target dip wavelength corresponding to a target dip) so that a portion of the second acoustic wave AW2 corresponding to the target wavelength (hereinafter, this portion will be referred to as the second compensation wave CW2) passes through the air channel 232 and propagates toward the sound propagation opening 152.

[0059] In the back cavity structure 130 having the second type TP2, the air channels 232 of the back cavity structure 130 can be designed so that the second compensating wave CW2 has a phase delay of 180 degrees relative to the original second acoustic wave AW2. Since the phase difference between the first acoustic wave AW1 and the original second acoustic wave AW2 is 180 degrees and the second compensating wave CW2 has a phase delay of 180 degrees relative to the original second acoustic wave AW2, the phase difference between the second compensating wave CW2 and the first acoustic wave AW1 is 360 degrees or substantially 0. Therefore, when the second compensating wave CW2 propagates out of the air channels 232 of the back cavity structure 130, interference (e.g., constructive interference) occurs between the second compensating wave CW2 and the first acoustic wave AW1. For example, if the first acoustic wave AW1 has a target dip corresponding to the target dip wavelength, the phase difference between the second compensation wave CW2 having the target dip wavelength and the first acoustic wave AW1 is 0, so the SPL caused by the second compensation wave CW2 having the target dip wavelength and the SPL caused by the first acoustic wave AW1 having the target dip wavelength will be added together, resulting in an increase in the SPL at the target dip wavelength and flattening the dip in the frequency response of the first sound generating component 110.

[0060] The number of air channel(s) 232 may be designed based on requirement(s). Different air channels 232 may correspond to different target wavelengths to flatten dip(s) and / or peak(s) in the frequency response of the first sound-generating component 110, and different air channels 232 induce different second compensation waves CW2 with different target wavelengths.

[0061] Similar to the first type TP1, the holder 140 of the second type TP2 embodiment may include at least one air passage AP (the air passage AP is shown in Figures 5 to 10) connected between the first holding side 142 and the second holding side 144, and the third acoustic wave AW3 may pass through the air passage AP from the second holding side 144 towards the first holding side 142, so that the third acoustic wave AW3 propagates towards the sound propagation opening 152.

[0062] As a result, in an acoustic device 200 having the second type TP2, the final acoustic wave propagating towards the outside of the acoustic device 200 is formed by the superposition of the first acoustic wave AW1, the second compensation wave CW2, and the third acoustic wave AW3.

[0063] 5 and 6, FIG. 5 is a schematic diagram showing an acoustic device according to a second type of embodiment of the present invention, and FIG. 6 is a schematic diagram showing the path of an acoustic wave in the acoustic device according to the embodiment shown in FIG. 5. It should be noted that the structure of the acoustic device 200_1, the shape of the outer housing structure 150, and the arrangement of components within the acoustic device 200_1 are not limited by FIGS. 5 and 6. In FIGS. 5 and 6, the hollow portion between the air passage AP and the first sound-generating component 110 may be an empty space or a solid structure. For example, the hollow portion in FIGS. 5 and 6 is a solid structure contained in the holder 140.

[0064] As shown in FIG. 6, three paths of acoustic waves are shown. The first path P1 of the first acoustic wave AW1 is shown by a thin line in FIG. 6, the second path P2 of the second compensating wave CW2 (part of the second acoustic wave AW2) is shown by a thin dashed line in FIG. 6, and the third path P3 of the third acoustic wave AW3 is shown by a thick line in FIG. 6. The first path P1 passes through the first front side 110a of the first sound-generating component 110 and the sound-propagating opening 152. The second path P2 passes through the first rear side 110b of the first sound-generating component 110, the back cavity structure 130 (i.e., the air channel 232), and the sound-propagating opening 152. The third path P3 passes through the second front side 120a of the second sound-generating component 120, the air passage AP, and the sound-propagating opening 152.

[0065] 6, the air channel 232 of the back cavity structure 130 includes a connecting passage CTP and at least a portion of the air passage AP, and the connecting passage CTP is connected between the first back side 110b of the first sound-generating component 110 and the air passage AP. Therefore, the second compensating wave CW2 propagates toward the sound-propagating opening 152 by passing through the connecting passage CTP and the air passage AP.

[0066] 6, the third acoustic wave AW3 propagates toward the sound propagation opening 152 by passing through the air passage AP, so that the third acoustic wave AW3 passes through at least a portion of the air channel 232 of the back cavity structure 130. Therefore, the third path P3 of the third acoustic wave AW3 may overlap with a portion of the second path P2 of the second compensation wave CW2.

[0067] 7 and 8, Fig. 7 is a schematic diagram showing a top view of a holder for an acoustic device according to an embodiment of the second type of the present invention, and Fig. 8 is a schematic diagram showing a bottom view of the holder for an acoustic device according to an embodiment of the second type of the present invention. Fig. 7 shows a first holding side 142 of the holder 140, and Fig. 8 shows a second holding side 144 of the holder 140.

[0068] As shown in FIG. 7 , the first sound-generating component 110 is disposed in the first notch N1, and the first back side 110b of the first sound-generating component 110 faces the first holding side 142 of the holder 140. The second acoustic wave AW2 propagates through the back cavity structure 130 (air channel 232) toward the sound-propagating opening 152. The back cavity structure 130 (air channel 232) includes a connecting passage CTP (e.g., a U-shaped connecting passage) and a portion of the air passage AP, one end of which is a hole HL in the first notch N1, and the other end of which is connected to the middle of the air passage AP. In FIGS. 7 and 8 , the connecting passage CTP can be, but is not limited to, between the first holding side 142 and the second holding side 144. In FIGS. 7 and 8 , the air passage AP can be, but is not limited to, a through-hole.

[0069] As shown in FIG. 8, the second sound-generating component 120 is positioned in the second notch N2, the second front side 120a of the second sound-generating component 120 faces the second holding side 144 of the holder 140, and the third acoustic wave AW3 propagates through the air passage AP toward the sound-propagating opening 152.

[0070] The holder 140 may include any suitable structure based on requirement(s). For example, two third notches N3 may be disposed in the first notch N1, and a conductive wire may be disposed in the third notch N3 for electrical connection between the first sound-generating component 110 and an external device. For example, a fourth notch N4 may be disposed adjacent to the first notch N1. For example, another through-hole TH connecting between the first holding side 142 and the second holding side 144 may be disposed adjacent to the first notch N1.

[0071] 9 and 10, Fig. 9 is a schematic diagram showing an acoustic device according to a second type of embodiment of the present invention, and Fig. 10 is a schematic diagram showing paths of acoustic waves in the acoustic device according to the embodiment shown in Fig. 9. Compared with the embodiment shown in Fig. 5 and Fig. 6, in the acoustic device 200_2, a fourth path P4 of another second compensation wave CW2' (another part of the second acoustic wave AW2) is shown by a thin dashed line in Fig. 10, and the second compensation wave CW2 propagated along the second path P2 and the another second compensation wave CW2' propagated along the fourth path P4 have different target wavelengths. The second path P2 passes through the first rear side 110b of the first sound-generating component 110, a portion of the back cavity structure 130 (i.e., the first air channel 232a), and the sound propagation opening 152, and the fourth path P4 passes through the first rear side 110b of the first sound-generating component 110, another portion of the back cavity structure 130 (i.e., the second air channel 232b), and the sound propagation opening 152.

[0072] 10 , the first air channel 232a of the back cavity structure 130 includes a first connecting passage CTP1 and at least a part of the air passage AP, and the first connecting passage CTP1 is connected between the first back side 110b of the first sound-generating component 110 and the air passage AP. Therefore, the second compensating wave CW2 propagates toward the sound-propagating opening 152 by passing through the first connecting passage CTP1 and the air passage AP.

[0073] 9 and 10 , the second air channel 232b of the back cavity structure 130 includes a second connecting passage CTP2, which is connected between the first back side 110b of the first sound-generating component 110 and the first cavity CB1 of the outer housing structure 150. Therefore, another second compensating wave CW2′ propagates toward the sound-propagating opening 152 by passing through the second connecting passage CTP2.

[0074] It should be noted that the structure of the acoustic device 200_2, the shape of the outer housing structure 150, and the arrangement of components within the acoustic device 200_2 are not limited by FIGS.

[0075] That is, with the back cavity structure design, the acoustic device has a flatter frequency response for easy operation and high performance.

[0076] Those skilled in the art will readily recognize that numerous modifications and variations of the apparatus and method may be made while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

1. A holder disposed or to be disposed within an acoustic device, a back cavity structure formed in the holder; when the holder is placed in the acoustic device, a first sound-generating component is placed on the holder, the back cavity structure is connected to a first rear side of the first sound-generating component, the first sound-generating component generates a first acoustic wave from a first front side toward a sound propagation opening of the acoustic device, and the first sound-generating component generates a second acoustic wave from the first rear side toward a back cavity of the back cavity structure; the first sound generating component is a high frequency sound unit; the length of the acoustic path within the back cavity is a half wavelength or a quarter wavelength corresponding to a particular frequency having a dip or a peak in the frequency response of the first sound generating component, such that the frequency response of the first sound generating component at that particular frequency is flattened; Holder.

2. The holder of claim 1 , wherein the back cavity structure includes a sealed back volume.

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