Audio device

Abstract

The embodiment of the present specification discloses an audio device, which includes a piezoelectric assembly that vibrates under the action of a driving voltage, a vibration assembly that is mechanically connected to the piezoelectric assembly to receive the vibration and generate sound, and a resistive element that is connected in series to the piezoelectric assembly to change the frequency response of the vibration assembly so that the difference between the amplitude of the vibration of the vibration assembly at 10 kHz and the amplitude at 1 kHz does not exceed 20 dB. The present specification relates to a resistor element that is connected in series to reduce the amplitude of the vibration of the vibration assembly in the mid-high frequency band, reduce the sensitivity difference in the entire frequency band, and improve the balance of the high and low frequencies of the sound output from the audio device. When the audio device is in the mid-high frequency band, the resistor element connected in series further reduces the current flowing through the piezoelectric assembly in a manner of voltage division, thereby reducing the heat energy generated by the piezoelectric assembly, achieving the effect of temperature control, and improving the operation reliability of the audio device.

Description

Technical Field

[0001] This specification relates to the technical field of acoustics, and particularly to acoustic devices.

Background Art

[0002] An acoustic device generally deforms a piezoelectric assembly by applying electrical energy to the piezoelectric assembly to transmit sound. For example, the acoustic device can apply a driving voltage in the polarization direction of the piezoelectric assembly and emit sound waves to the outside by vibrating due to the inverse piezoelectric effect of the piezoelectric material.

[0003] However, the resonance frequency of the piezoelectric assembly in the acoustic device is generally high, causing the high-frequency sensitivity of the device to be high and the low-frequency sensitivity to be low. As a result, the sound emitted from the acoustic device is harsh, causing an imbalance in the user's auditory sensation at high and low frequencies.

[0004] In addition, after an AC voltage signal is introduced, the piezoelectric assembly generates heat due to the action of the internal resistance of the piezoelectric assembly material. Especially near the resonance frequency, the heat generation is more serious and may be close to or exceed 300°C. On the other hand, since the piezoelectric assembly has piezoelectricity, its operating temperature must be lower than the Curie temperature of the material. Therefore, how to effectively control the operating temperature of the piezoelectric assembly with an AC voltage signal is the key to improving the operating reliability of the acoustic output device driven by the piezoelectric assembly.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, it is necessary to provide an acoustic device with a good balance of sensitivity at high and low frequencies and effectively control heat generation at medium and high frequencies at the same time.

Means for Solving the Problems

[0006] One embodiment of this specification provides an acoustic device. The device includes a piezoelectric assembly that vibrates under the action of a driving voltage, a vibration assembly that is mechanically connected to the piezoelectric assembly to receive vibration and generate sound, and a resistive element that is connected in series with the piezoelectric assembly to change the frequency response of the vibration assembly such that the difference between the amplitude at 10 kHz and the amplitude at 1 kHz of the vibration of the vibration assembly does not exceed 20 dB.

[0007] In some embodiments, the resistive element is connected in series to the positive electrode of the piezoelectric assembly.

[0008] In some embodiments, the resistive element is welded to the positive electrode of the piezoelectric assembly.

[0009] In some embodiments, the resistive element is connected in series to the negative electrode of the piezoelectric assembly.

[0010] In some embodiments, the resistive element is welded to the negative electrode of the piezoelectric assembly.

[0011] In some embodiments, the positive and negative electrodes of the piezoelectric assembly are drawn out from the same side of the piezoelectric assembly.

[0012] In some embodiments, the resistive element includes a wire connected to the piezoelectric assembly.

[0013] In some embodiments, the resistive element includes a conductive adhesive connected to the piezoelectric assembly.

[0014] In some embodiments, the resistive element is disposed on a flexible printed circuit board.

[0015] In some embodiments, the resistive element includes the electrodes of the piezoelectric assembly.

[0016] In some embodiments, at least a part of the material of the electrodes of the piezoelectric assembly is one of the materials such as copper, gold, aluminum, tungsten, iron, or platinum.

[0017] In some embodiments, the effective cross-sectional area of at least a part of the electrodes of the piezoelectric assembly is smaller than the contour cross-sectional area of the electrodes.

[0018] In some embodiments, the cross-section of at least a part of the electrodes of the piezoelectric assembly is a mesh structure or an S-shaped structure.

[0019] In some embodiments, the resistance element has a resistance value of 1 Ω to 1 kΩ.

[0020] In some embodiments, the piezoelectric assembly is a beam structure.

[0021] In some embodiments, the piezoelectric assembly includes at least two piezoelectric ceramic sheets that are electrically connected to each other.

[0022] In some embodiments, the at least two piezoelectric ceramic sheets are alternately laminated with the electrodes of the piezoelectric assembly.

[0023] In some embodiments, in the operating state, the surface temperature of the piezoelectric assembly is lower than its Curie temperature.

[0024] In some embodiments, the vibration assembly includes an elastic element and a mass element, and one end of the elastic element is connected to the piezoelectric assembly and the other end is connected to the mass element.

[0025] In some embodiments, the elastic element includes one of a vibration transmission sheet, rubber, a dome, or a substrate.

[0026] In some embodiments, the mass element includes a housing that houses the piezoelectric assembly and the resistance element.

[0027] In some embodiments, the acoustic device is a bone conduction acoustic device.

[0028] In some embodiments, the acoustic device further includes a voltage boosting system that improves the voltage output from the power supply.

[0029] In the embodiments of this specification, by providing a resistance element and connecting it in series to the piezoelectric assembly for voltage division, the voltage across the piezoelectric assembly is reduced, thereby reducing the amplitude of vibration of the vibration assembly in the medium and high frequency bands, reducing the sensitivity difference across the entire frequency band, and improving the balance of the high and low frequencies of the sound output from the acoustic device.

[0030] When the acoustic device is in the medium and high frequency bands, the series-connected resistance element further reduces the current flowing through the piezoelectric assembly in a voltage division manner, thereby reducing the thermal energy generated by the piezoelectric assembly, achieving the effect of temperature control, and improving the operational reliability of the acoustic device.

[0031] The present specification will be further described by way of exemplary embodiments, and these exemplary embodiments will be described in detail with reference to the drawings. These embodiments are not limiting, and in these embodiments, the same numbers indicate the same structures.

Brief Description of the Drawings

[0032]

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Best Mode for Carrying Out the Invention

[0033] To more clearly explain the technical means of the embodiments of this specification, the drawings necessary for the description of the embodiments will be briefly described below. Obviously, the drawings described below are only some examples or embodiments of this specification, and those skilled in the art can apply this specification to other similar scenarios based on these drawings without creative effort. Unless it is clear from the language environment or otherwise stated, the same numbers in the drawings indicate the same structure or operation.

[0034] It should be understood that the terms "system", "device", "unit" and / or "module" used in this specification are a way to distinguish various assemblies, elements, components, parts or assemblies at different levels. However, other expressions can be used in place of the above terms if other terms can achieve the same purpose.

[0035] As used in this specification and the claims, unless the context clearly indicates otherwise, terms such as "one", "a", "a kind" and / or "the" do not particularly mean the singular form and may include the plural form. Generally, the terms "comprising" and "containing" only present that they include the specifically identified steps and elements, and these steps and elements are not an exclusive listing, and the method or device may also include other steps or elements.

[0036] In this specification, flowcharts are used to describe the operations performed by the system according to the embodiments of this specification. It should be understood that the preceding and subsequent operations are not necessarily executed exactly in order. Instead, each step may be processed in reverse order or simultaneously. Also, other operations may be added to these processes, and one or more operations may be removed from these processes.

[0037] The acoustic device of one or more embodiments of this specification outputs sound by vibrating a piezoelectric assembly, and is applicable to various scenes where audio needs to be played. For example, the acoustic device may be an independent audio output device (such as a sound box, earphone, etc.) that can play audio based on user instructions. Also, the acoustic device may be a module or assembly in a terminal device (such as a mobile phone, computer, etc.) that can play audio based on terminal instructions. In some embodiments, the acoustic device can adjust the deformation of the piezoelectric assembly based on parameters such as the frequency and magnitude of the sound to be output, generate different vibrations, and output different sounds to the vibration assembly based on the different vibrations.

[0038] In some embodiments, the acoustic device may be a bone conduction acoustic device. The vibration assembly in the bone conduction acoustic device fits the user's body tissue, and the sound wave emitted by the vibration assembly can be transmitted to the user's inner ear by the user's bone. In some embodiments, the acoustic device may be other types of acoustic devices such as an air conduction acoustic device, a hearing aid, a cochlear implant, glasses, a helmet, an Augmented Reality (AR) device, a Virtual Reality (VR) device, etc. Or, preferably, the acoustic device may be used to output sound as part of an in-vehicle audio system or an indoor audio system.

[0039] Currently, the resonance frequency of the piezoelectric assembly in the acoustic device is generally high, which causes the high-frequency sensitivity of the device to be high and the low-frequency sensitivity to be low. As a result, the sound emitted from the acoustic device is harsh, and the balance of the user's auditory sensation at high and low frequencies is not good.

[0040] In the embodiments of this specification, an acoustic device is described. In some embodiments, the acoustic device may include a piezoelectric assembly, a vibration assembly, and a resistive element. The piezoelectric assembly can vibrate under the action of a driving voltage. The vibration assembly can receive the vibration from the piezoelectric assembly and generate sound. The resistive element is connected in series with the piezoelectric assembly to change the frequency response of the vibration assembly, so that the difference between the amplitude at 10 kHz and the amplitude at 1 kHz of the vibration of the vibration assembly does not exceed 20 dB.

[0041] The embodiments of this specification provide a resistive element connected in series with the piezoelectric assembly to divide the voltage, thereby reducing the voltage across the piezoelectric assembly, reducing the amplitude of the vibration of the vibration assembly in the medium and high frequency bands, reducing the sensitivity difference across the entire frequency band, and improving the balance between the high and low frequencies of the sound output from the acoustic device.

[0042] When the acoustic device according to the embodiments of this specification is in the medium and high frequency bands, the series-connected resistive element further reduces the current flowing through the piezoelectric assembly in a voltage-dividing manner, thereby reducing the thermal energy generated by the piezoelectric assembly, achieving the effect of temperature control, and improving the operating reliability of the acoustic device.

[0043] FIG. 1 is a block diagram of an acoustic device 100 according to some embodiments of this specification.

[0044] As shown in FIG. 1, the acoustic device 100 may include a vibration assembly 110, a piezoelectric assembly 120, and a resistive element 130. The piezoelectric assembly 120 vibrates under the action of a driving voltage. The vibration assembly 110 is mechanically connected to the piezoelectric assembly 120 to receive the vibration and generate sound. The resistive element 130 is connected in series with the piezoelectric assembly 120 to change the frequency response of the vibration assembly 110 and ensure that the difference between the amplitude at 10 kHz and the amplitude at 1 kHz of the vibration of the vibration assembly 110 does not exceed 20 dB.

[0045] The vibration assembly 110 may be configured as an assembly that transmits vibration to generate sound. In some embodiments, the vibration assembly 110 may include an elastic element, and the elastic element may deform in response to vibration and generate sound waves by changing the sound pressure around itself, thereby realizing the output of sound. Exemplarily, the elastic element can generate density changes in the surrounding air due to its own deformation (e.g., its own vibration, etc.), form longitudinal waves with alternating density and rarefaction, and thereby generate sound waves. In some embodiments, the elastic element may include a vibration transmission sheet, rubber, dome, substrate, etc., or any combination thereof. In some embodiments, the material of the elastic element may be any material having vibration transmission performance. For example, the material of the above elastic element may be silica gel, plastic rubber, rubber, metal, etc., or any combination thereof. In some embodiments, the above vibration assembly 110 further includes a mass element. One end of the elastic element may be connected to the piezoelectric assembly 120, and the other end may be connected to the mass element. In some embodiments, at least a part of the piezoelectric assembly 120 may be connected to the elastic element, and a part of the mass element may be connected to the elastic element. In some embodiments, the mass element may include a mass block, a housing, etc. For example, the housing may accommodate the piezoelectric assembly 120 and the resistance element 130, protect the piezoelectric assembly 120 and the resistance element 130, and extend the service life of the acoustic device 100. In some embodiments, the material of the housing may include one or more materials such as metal, silica gel, rubber, plastic, etc. to achieve the function of buffering and shock absorption. In some embodiments, the vibration assembly 110 may be a membrane structure (e.g., an air conduction vibration membrane, etc.), a plate structure (e.g., a bone conduction vibration panel, etc.), or other structures such as a mesh structure or a layered structure.

[0046] Hereinafter, an exemplary acoustic device 100 is provided to describe a specific implementation manner of the vibration assembly 110.

[0047] FIG. 2 is a schematic configuration diagram of the acoustic device 100 according to some embodiments of the present specification.

[0048] As shown in FIG. 2, one end of the vibration assembly 110 may be connected to the vibration output end 121 of the piezoelectric assembly 120 to receive vibration. The other end of the vibration assembly 110 can output sound. Exemplarily, the vibration assembly 110 can transmit sound waves to the user through one or more media (e.g., air, the user's bone, etc.), thereby allowing the user to hear the sound output from the acoustic device 100.

[0049] The piezoelectric assembly 120 may be configured as an electrical energy conversion device that converts electrical energy into mechanical energy. In some embodiments, the piezoelectric assembly 120 can vibrate by generating different degrees of deformation based on different driving voltages. For specific implementation manners of the piezoelectric assembly 120, reference can be made to the relevant descriptions in FIGS. 6, 11A-11F, 12, and 13A-13F below, so the description is omitted here. In some embodiments, the piezoelectric assembly 120 may be in a shape such as sheet-like, annular, rhombic, cuboid, cylindrical, spherical, etc., or any combination thereof, or other irregular shapes. In some embodiments, the material of the piezoelectric assembly 120 may include piezoelectric materials such as piezoelectric crystals, piezoelectric ceramics, piezoelectric polymers, or any combination thereof. In some embodiments, the piezoelectric crystal may include quartz, sphalerite, boracite, tourmaline, zinc blende, GaAs, barium titanate and its derivative crystals, KH2PO4, NaKC4H4O6·4H2O (Rochelle salt), etc., or any combination thereof. Piezoelectric ceramics are piezoelectric polycrystals obtained by randomly aggregating fine crystal grains obtained by solid-phase reaction and sintering between powders of different materials. In some embodiments, the piezoelectric ceramic material may include barium titanate (BT), lead zirconate titanate (PZT), barium lithium niobate (PBLN), modified lead titanate (PT), aluminum nitride (AIN), zinc oxide (ZnO), etc., or any combination thereof. In some embodiments, the piezoelectric polymer material may include polyvinylidene fluoride (PVDF).

[0050] In some embodiments, by adjusting the magnitude of the driving voltage applied to the piezoelectric assembly 120, the amplitude of vibration of the piezoelectric assembly 120 can be adjusted. For example, the amplitude of vibration output from the piezoelectric assembly 120 is related to the magnitude of the applied voltage, and the relationship between the two may be Equation (1).

[0051]

Number

[0052] Here, F is the amplitude output from the piezoelectric assembly 120, V is the driving voltage of the piezoelectric assembly 120, d is the piezoelectric constant of the piezoelectric assembly 120, A is the area of the piezoelectric assembly 120, t is the thickness of the piezoelectric assembly 120, and S E is the elastic compliance constant of the piezoelectric assembly 120. According to Equation (1), the amplitude output from the piezoelectric assembly 120 is directly proportional to the driving voltage of the piezoelectric assembly 120.

[0053] In some embodiments, the vibration frequency of the piezoelectric assembly 120 may be adjusted by adjusting the magnitude of the frequency of the driving voltage applied to the piezoelectric assembly 120. In some embodiments, the vibration generated by the piezoelectric assembly 120 is further related to the piezoelectric constant of the piezoelectric material. For example, when the driving voltage is the same, the greater the piezoelectric constant, the greater the deformation generated by the piezoelectric assembly 120 and the stronger the vibration. In some embodiments, due to differences in piezoelectric constants, the direction of deformation generated in the piezoelectric assembly 120 is different. For example, the piezoelectric constant of the piezoelectric assembly 120 may be the D33 constant or the D31 constant, or other piezoelectric constants. Here, the D33 constant indicates that the electrical direction (i.e., the direction of the electric field) and the mechanical direction (i.e., the direction of deformation) of the piezoelectric assembly 120 are the same, and the D31 constant indicates that the deformation of the piezoelectric assembly 120 mainly occurs in one direction.

[0054] FIG. 3 is a schematic circuit diagram of the piezoelectric assembly 120 according to some embodiments of the present specification.

[0055] In some embodiments, the piezoelectric assembly 120 can be regarded as a component having capacitance characteristics. As shown in FIG. 3, the piezoelectric assembly 120 may be a capacitor C having a capacitance value. p Correspondingly, the impedance Z p of the piezoelectric assembly 120 can be determined by Equation (2).

[0056]

Number

[0057] Here, Z p is the equivalent impedance value of the piezoelectric assembly 120, ω is the angular frequency of the driving voltage, and C p is the equivalent capacitance value of the piezoelectric assembly 120. According to Equation (2), when the resistance element 130 is not provided, as the angular frequency ω of the driving voltage increases, the impedance Z of the piezoelectric assembly 120 p decreases.

[0058] FIG. 4 is a schematic diagram of the impedance-frequency curve of the piezoelectric assembly 120 according to some embodiments of the present specification.

[0059] As shown in FIG. 4, curve 1 is the impedance-frequency curve of the piezoelectric assembly 120. According to curve 1, as the frequency of the driving voltage increases (for example, rises from 100 Hz to 1 kHz), the angular frequency ω of the driving voltage also increases, but the impedance of the piezoelectric assembly 120 decreases (for example, the impedance value Z p1 to the impedance value Z p2 decreases).

[0060] Furthermore, as shown in FIG. 3, when the resistance element 130 is not connected in series and the voltage V of the driving voltage does not change, the decrease in the impedance Z of the piezoelectric assembly 120 p can cause the current flowing through the piezoelectric assembly 120 to increase accordingly. That is, as the angular frequency ω of the driving voltage increases, the impedance Z of the piezoelectric assembly 120 p decreases, causing the current flowing through the piezoelectric assembly 120 to increase.

[0061] FIG. 5 is a schematic diagram of the current-frequency curve of the piezoelectric assembly 120 according to some embodiments of the present specification.

[0062] As shown in FIG. 5, curve 2 is the current-frequency curve of the piezoelectric assembly 120. According to curve 2, as the frequency of the driving voltage increases (for example, rising from 1 kHz to 10 kHz), the angular frequency ω of the driving voltage also increases, and the current flowing through the piezoelectric assembly 120 increases (for example, rising from current value I1 to current value I2). According to Joule's law, that is, Equation (3), when the resistance is constant, the heat generation output P of the electronic device is directly proportional to the square of the current I.

[0063] [Number]

[0064] Therefore, when the resistive element 130 is not connected in series, as the frequency of the driving voltage increases, the current of the piezoelectric assembly 120 increases. When the frequency of the driving voltage is in the medium to high frequency range (for example, greater than 1 kHz), the heat generation output of the piezoelectric assembly 120 gradually increases, thereby increasing the operating temperature of the piezoelectric assembly 120. If it becomes serious, it will be higher than the Curie temperature, which may reduce the piezoelectricity of the piezoelectric assembly 120 and affect the normal operation of the acoustic device 100.

[0065] In some embodiments, the piezoelectric assembly 120 may have a beam structure (for example, a beam structure with one end fixedly connected to the acoustic device and the other end vibrating freely, which can be regarded as a cantilever beam structure). In some embodiments, the fixed end of the piezoelectric assembly 120 with a cantilever beam structure (hereinafter abbreviated as a piezoelectric beam) can receive a voltage signal. The entire piezoelectric beam vibrates, and the vibration is transmitted to the vibration assembly by any position (for example, the free end) on the piezoelectric beam and is perceived by the user's ear. Here, the position where the vibration is output on the piezoelectric beam is referred to as the vibration output end. In some embodiments, the vibration output end may directly output air-conducted sound. In some embodiments, the vibration output end may be connected to a vibration membrane to directly output air-conducted sound. In some embodiments, the vibration output end may be connected to a structure such as a vibration transmission sheet, and the vibration is transmitted to the auditory nerve by tissues such as the user's skin and bone to output bone-conducted sound.

[0066] Exemplarily, as shown in FIG. 2, the fixed end of the cantilever beam structure may be the driving end 122 of the piezoelectric assembly 120, the driving end 122 can receive a driving voltage, and the free end of the cantilever beam structure may be the vibration output end 121 of the piezoelectric assembly 120, and the vibration output end 121 can generate and output vibrations.

[0067] In some embodiments, the piezoelectric assembly 120 may include at least two piezoelectric ceramic sheets electrically connected to each other. The piezoelectric ceramic sheet may be in a sheet shape and be a component having piezoelectric properties. In some embodiments, the piezoelectric ceramic sheet can be mechanically deformed according to the magnitude and frequency of the driving voltage. For example, the piezoelectric ceramic sheet can elongate when the driving voltage is in the positive direction and contract when the driving voltage is in the negative direction. In some embodiments, the polarization directions of different piezoelectric ceramic sheets may be different, so that the deformation directions generated by the action of the same driving voltage may be different. For example, when the driving voltage is in the positive direction, when the polarization directions of piezoelectric ceramic sheet A and piezoelectric ceramic sheet B are different, piezoelectric ceramic sheet A can elongate and piezoelectric ceramic sheet B can contract. In some embodiments, the polarization directions of different piezoelectric ceramic sheets may be the same, so that the deformation directions generated by the action of the same driving voltage may be the same.

[0068] In some embodiments, the piezoelectric assembly 120 may have a layered structure. In some embodiments, at least two piezoelectric ceramic sheets may be provided to be laminated. For example, a plurality of piezoelectric ceramic sheets are provided in an overlapping manner, and their positions correspond spatially. In some embodiments, the vibration of the piezoelectric assembly 120 may be related to the number of layers of the piezoelectric ceramic sheet. Exemplarily, the greater the number of layers of the piezoelectric ceramic sheet, the greater the vibration amplitude of the piezoelectric assembly 120.

[0069] In some embodiments, the manner in which at least two piezoelectric ceramic sheets are electrically connected to each other may be related to the polarization direction between the piezoelectric ceramic sheets. For example, when the polarization directions of the piezoelectric ceramic sheets in different layers are in the same direction, the plurality of piezoelectric ceramic sheets may be connected in series such that the deformation directions of the different piezoelectric ceramic sheets are different. For example, two piezoelectric ceramic sheets with the same polarization direction may be stacked and connected in series, and since the driving voltages of the two-layer piezoelectric ceramic sheets are in opposite directions, the deformation directions of the two-layer piezoelectric ceramic sheets are in opposite directions, thereby increasing the deformation strength of the piezoelectric assembly 120 and further increasing the vibration amplitude of the piezoelectric assembly 120.

[0070] In some embodiments, when the polarization directions of the piezoelectric ceramic sheets in different layers are in opposite directions, the plurality of piezoelectric ceramic sheets may be connected in a parallel connection form such that the deformation directions of the different piezoelectric ceramic sheets are different. For example, two piezoelectric ceramic sheets with opposite polarization directions may be stacked and connected in parallel, and since the driving voltages of the two-layer piezoelectric ceramic sheets are in opposite directions, the deformation directions of the two-layer piezoelectric ceramic sheets are in opposite directions, thereby increasing the deformation strength of the piezoelectric assembly 120 and further increasing the vibration amplitude of the piezoelectric assembly 120. Hereinafter, an exemplary piezoelectric assembly 120 is provided to explain a specific implementation manner of the piezoelectric ceramic sheets connected in parallel.

[0071] FIG. 6 is a schematic configuration diagram of a piezoelectric assembly 120 according to some embodiments of the present specification.

[0072] As shown in FIG. 6, the piezoelectric assembly 120 may include a plurality of piezoelectric ceramic sheets 123 provided in a stacked manner. In some embodiments, the plurality of piezoelectric ceramic sheets 123 may be provided in the first layer, the second layer, the third layer, and the fourth layer of the piezoelectric assembly 120, respectively. The polarization directions of the piezoelectric ceramic sheets 123 in the first layer and the second layer may be different from the polarization directions of the piezoelectric ceramic sheets 123 in the third layer and the fourth layer (i.e., the polarization directions of the first layer and the second layer are the same, and the polarization directions of the third layer and the fourth layer are the same). When a driving voltage is applied to the piezoelectric assembly 120, the deformation directions of the first layer and the second layer may be opposite to the deformation directions of the third layer and the fourth layer, thereby increasing the vibration amplitude of the piezoelectric assembly 120.

[0073] In some embodiments, the positive and negative electrodes are respectively provided at both ends of at least two piezoelectric ceramic sheets, so that at least two piezoelectric ceramic sheets are connected in parallel to each other, thereby providing the same driving voltage to the piezoelectric ceramic sheets. In some embodiments, at least two piezoelectric ceramic sheets may be alternately stacked with the electrodes of the piezoelectric assembly 120. The positive and negative electrodes of the piezoelectric assembly 120 may extend between the plurality of piezoelectric ceramic sheets to increase the contact area with the piezoelectric ceramic sheets and improve the driving efficiency.

[0074] Exemplarily, as shown in FIG. 6, in order to achieve the parallel connection of the plurality of piezoelectric ceramic sheets 123, the positive electrode contacts the first end 1231 of the plurality of piezoelectric ceramic sheets 123, and the negative electrode contacts the second end 1232 of the plurality of piezoelectric ceramic sheets 123. The positive electrode may be provided between the first layer and the second layer of the plurality of piezoelectric ceramic sheets 123 and between the third layer and the fourth layer. The negative electrode may be provided on the surface of the plurality of piezoelectric ceramic sheets 123 and between the second layer and the third layer.

[0075] In the embodiments of this specification, the acoustic device 100 vibrates due to the inverse piezoelectric effect of the piezoelectric assembly 120 and emits sound waves to the outside. Compared with conventional electro-dynamic speakers, the acoustic device 100 has advantages such as high electro-mechanical conversion efficiency, low energy consumption, small volume, and high integration. Note that FIG. 6 is only an example, and the piezoelectric assembly 120 may include other numbers of piezoelectric ceramic sheets or be connected to the electrodes in other forms.

[0076] The resistance element 130 may be configured as any electrical device having resistance characteristics or capable of realizing a band-pass adjustment control effect. For example, the resistance element 130 may include components, materials, coatings, adhesives, etc. having resistance properties, or any combination thereof. Also, for example, the resistance element 130 may include a resistance-capacitance (RC) filter having a band-pass adjustment control effect, such as an RC filter in a series connection form, an RC filter in a parallel connection form, an RC filter in a series-parallel connection form, a cascade or multi-dimensional RC filter, a passive or active RC filter, etc., or any combination thereof.

[0077] In some embodiments, the resistance element 130 is connected in series with the piezoelectric assembly 120 to adjust the amplitude difference of the vibration assembly 110. For example, the resistance element 130 changes the amplitude difference at the high and low frequencies of the vibration assembly 110 by adjusting and controlling the voltage or bandwidth across the piezoelectric assembly 120 according to the principle of series connection voltage division.

[0078] FIG. 7 is a schematic circuit diagram of the resistance element 130 and the piezoelectric assembly 120 according to some embodiments of this specification.

[0079] As shown in FIG. 7, the resistance element 130 can be equivalent to a resistance R t and the piezoelectric assembly 120 can be equivalent to a capacitor C p and the resistance R t can be connected in series with the capacitor C p and the driving voltage V is simultaneously applied to the resistance R t and the capacitor Cp A voltage can be provided to p . When the voltage of the driving voltage V does not change and the frequency of the driving voltage V continuously increases, the impedance of the piezoelectric assembly 120 decreases, so the voltage across the resistor element 130 increases, thereby reducing the voltage across the piezoelectric assembly 120.

[0080] FIG. 8 is a schematic diagram of the voltage-frequency curve of the piezoelectric assembly 120 according to some embodiments of the present specification.

[0081] In some embodiments, by adjusting the resistance value of the resistor element 130, the voltage across the piezoelectric assembly 120 can be adjusted. As shown in FIG. 8, curve 3 is the voltage-frequency curve of the piezoelectric assembly 120 when the resistor element 130 is not connected in series (i.e., the resistor element 130 with a resistance value of R1 = 0 is connected in series), curve 4 is the voltage-frequency curve of the piezoelectric assembly 120 when the resistor element 130 with a resistance value of R2 is connected in series, curve 5 is the voltage-frequency curve of the piezoelectric assembly 120 when the resistor element 130 with a resistance value of R3 is connected in series, and curve 6 is the voltage-frequency curve of the piezoelectric assembly 120 when the resistor element 130 with a resistance value of R4 is connected in series. Here, 0 = R1 < R2 < R3 < R4.

[0082] In some embodiments, when the frequency of the driving voltage V is low (for example, the frequency is 10 Hz to 100 Hz), since the impedance of the piezoelectric assembly 120 is large, the effect on the overall impedance of the series-connected resistor element 130 is not obvious, and the influence on the voltage of the piezoelectric assembly 120 is small. When the frequency of the driving voltage V gradually increases to medium and high frequencies (for example, the frequency is 1 k to 10 kHz), the voltage across the piezoelectric assembly 120 decreases. For example, when the frequency of the driving voltage V increases to 10 kHz, the voltage of the piezoelectric assembly 120 of curve 3 is U3, the voltage of the piezoelectric assembly 120 of curve 4 is U4, the voltage of the piezoelectric assembly 120 of curve 5 is U5, and the voltage of the piezoelectric assembly 120 of curve 6 is U6. Here, U3 > U4 > U5 > U6.

[0083] In some embodiments, as the resistance value of the resistance element 130 increases, the frequency point at which the voltage across both ends of the piezoelectric assembly 120 begins to decrease gradually rises. As shown by curves 3-4 in FIG. 8, as the resistance value of the resistance element increases, the frequency point at which the voltage begins to decrease gradually rises. Correspondingly, in some embodiments, by adjusting the resistance value of the resistance element 130, the adjustment control of the acoustic output characteristics of the acoustic device 100 can be realized, and the frequency response characteristics and requirements for the application of the acoustic device 100 can be satisfied.

[0084] In some embodiments, the resistance element 130 is connected in series with the piezoelectric assembly 120, so that the voltage across both ends of the piezoelectric assembly 120 or the bandwidth can be adjusted and controlled, and the frequency response of the vibration assembly 110 can be changed. In some embodiments, the resistance element 130 is connected in series with the piezoelectric assembly 120, and by adjusting the voltage across both ends of the piezoelectric assembly 120, the amplitude difference at high and low frequencies of the vibration assembly 110 can be changed. Hereinafter, in order to describe the specific implementation manner of the resistance element 130, an exemplary frequency response curve of the vibration assembly 110 is provided.

[0085] FIG. 9 is a schematic diagram of the frequency response curve of the vibration assembly according to some embodiments of the present specification. As shown in FIG. 9, curve 7 is the frequency response curve of the vibration assembly 110 when the resistance element 130 is not connected in series to the piezoelectric assembly 120, and curve 8 is the frequency response curve of the vibration assembly 110 when the resistance element 130 is connected in series to the piezoelectric assembly 120. In some embodiments, the effect of connecting the resistance element 130 in series is to suppress the high-frequency output. For example, as shown in FIG. 9, after the resistance element 130 is connected in series, the position of the peak valley of the frequency response curve does not change, and the influence on the low-frequency amplitude is not significant either. However, from a certain frequency (for example, 600 Hz), as the frequency increases, the corresponding frequency amplitude decreases more, indicating a decrease in the amplitude difference between the high- and low-frequency curves, alleviating the "ear-piercing feeling" in the subjective auditory sense, and improving the balance between high and low frequencies. As shown in FIG. 9, the difference D1 between the amplitude at 10 kHz and the amplitude at 1 kHz of curve 8 is smaller than the difference D2 between the amplitude at 10 kHz and the amplitude at 1 kHz of curve 7. In some embodiments, the above difference D2 may not exceed a specific threshold value (for example, 30 dB, 20 dB, 15 dB, etc.). The embodiments of the present specification provide a resistance element 130 and connect it in series to the piezoelectric assembly 120, thereby reducing the sensitivity difference across the entire frequency band of the acoustic device 100, and improving the balance between high and low frequencies of the sound output from the acoustic device 100.

[0086] In some embodiments, when the voltage of the driving voltage V does not change and the frequency of the driving voltage V continuously increases, the impedance of the piezoelectric assembly 120 decreases. Therefore, due to the series-connected resistance element 130, the voltage across the piezoelectric assembly 120 decreases, and the current flowing through the piezoelectric assembly 120 correspondingly decreases. Also, according to Joule's law (Equation (3)), the heat generation output of the piezoelectric assembly 120 is directly proportional to the square of the current. Compared with the case where the resistance element 130 is not connected in series, the heat generation of the piezoelectric assembly 120 also correspondingly decreases, thereby improving the reliability of the device.

[0087] FIG. 10 is a schematic diagram of the current-frequency curve of the piezoelectric assembly 120 according to some embodiments of the present specification.

[0088] In some embodiments, by adjusting the resistance value of the resistance element 130 to adjust the current flowing through the piezoelectric assembly 120, the heat generation of the piezoelectric assembly 120 can be adjusted, and control over temperature can be achieved. As shown in FIG. 9, curve 9 is the current-frequency curve of the piezoelectric assembly 120 when the resistance element 130 is not connected in series (i.e., the resistance element 130 with a resistance value of R9 = 0 is connected in series), and curve 10 is the current-frequency curve of the piezoelectric assembly 120 when the resistance element 130 with a resistance value of R 10 is connected in series, and curve 11 is the current-frequency curve of the piezoelectric assembly 120 when the resistance element 130 with a resistance value of R 11 is connected in series, and curve 12 is the current-frequency curve of the piezoelectric assembly 120 when the resistance element 130 with a resistance value of R 12 is connected in series. Here, 0 = R9 < R 10 < R 11 < R 12 is true.

[0089] When the frequency of the driving voltage V is low (for example, the frequency is 10 to 100 Hz), since the impedance of the piezoelectric assembly 120 is large, the effect on the overall impedance of the series-connected resistance element 130 is not obvious, and the influence on the current flowing through the piezoelectric assembly 120 is small. When the frequency of the driving voltage V gradually increases to medium and high frequencies (for example, the frequency is 1k to 10kHz), the current flowing through the piezoelectric assembly 120 decreases. At the same frequency of the driving voltage, as the resistance value of the resistance element 130 increases, the current flowing through the piezoelectric assembly 120 becomes smaller. For example, when the frequency of the driving voltage V increases to 10 kHz, the current of the piezoelectric assembly 120 in curve 9 is I9, the current of the piezoelectric assembly 120 in curve 10 is I 10 and the current of the piezoelectric assembly 120 in curve 11 is I 11 and the current of the piezoelectric assembly 120 in curve 12 is I 12 and here, I9 > I 10 > I 11 > I 12 is true.

[0090] In some embodiments, the magnitude of the resistors connected in series can be determined based on the overall frequency response characteristics of the formed acoustic device 100. For example, based on the characteristics of the piezoelectric assembly 120, assuming that the high-frequency amplitude is large or shows an upward trend, the magnitude of the resistor element 130 that needs to be connected in series can be determined based on subjective listening. For example, based on the frequency response curve of the piezoelectric assembly 120, it can be determined from which frequency threshold fc the effect that the corresponding amplitude decreases more significantly as the frequency increases can be achieved as the frequency increases. In some embodiments, the frequency threshold fc may be determined based on the vibration characteristics of the specific piezoelectric assembly 120.

[0091] In some embodiments, the capacitance of the piezoelectric sheet of the piezoelectric assembly 120 may be determined by Equation (4).

[0092]

Equation

[0093] Here, ε is the dielectric constant of the piezoelectric sheet, S is the electrode area, and t is the distance between the positive and negative electrodes. Assuming that the dielectric constant ε changes due to the change of the piezoelectric material, and thereby the capacitance changes, it is necessary to re-set the matching resistor according to Equation (5). If the geometric dimensions S and t of the electrodes are changed, the vibration characteristics of the acoustic device 100 will be affected, and it is necessary to determine the specific value of the resistor connected in series based on its frequency response curve and subjective listening.

[0094] For the acoustic devices 100 composed of piezoelectric sheets Cp1 and Cp2 having different capacitance values, assuming that both of these two acoustic devices need to achieve the effect that the frequency response amplitude decreases as the frequency increases from the frequency threshold fc, the resistor elements R1 and R2 that need to be connected in series can be determined by Equation (5).

[0095]

Equation

[0096] In some embodiments, the resistance value of the resistance element 130 is within a certain range (for example, 1 Ω to 1000 Ω, 100 Ω to 10 kΩ, etc.), and by causing the vibration amplitude of the vibration assembly 110 to start decreasing from the frequency threshold value fc (for example, 100 Hz), the difference between the amplitude at 10 kHz and the amplitude at 1 kHz of the vibration assembly 110 is made not to exceed 20 dB. Thereby, the sensitivity difference in the entire frequency band of the acoustic device 100 can be reduced, and the balance between the high and low frequencies of the sound output from the acoustic device 100 can be improved. At the same time, the resistance element 130 can reduce the heat generation of the piezoelectric assembly 120, keep the operating temperature of the piezoelectric assembly 120 lower than the Curie temperature, and ensure the normal operation of the acoustic device 100. For example, with the excitation of a single-frequency of 6 kHz, the surface temperature (for example, 236.9 °C) of the piezoelectric assembly 120 not connected in series is high and can approach its Curie temperature (for example, the Curie temperature of the piezoelectric assembly 120 is 290 °C). When the excitation time increases, the surface temperature of the piezoelectric assembly 120 exceeds its Curie temperature, which may cause a failure of the piezoelectric assembly. On the other hand, with the excitation of a single-frequency signal of 6 kHz, the surface temperature of the piezoelectric assembly 120 with the resistance element 130 connected in series clearly decreases. In some embodiments, the surface temperature of the piezoelectric assembly 120 can be in a state lower than its Curie temperature within 5 minutes after being excited by a single-frequency signal of 6 kHz.

[0097] In some embodiments, the resistance element 130 may be connected in series with the piezoelectric assembly 120 in different connection manners. Hereinafter, taking the piezoelectric assembly shown in FIG. 6 above as an example, several exemplary connection manners of the resistance element 130 and the piezoelectric assembly 120 will be provided respectively to explain the specific implementation manner of the resistance element 130 in detail.

[0098] FIGS. 11A to 11F are schematic diagrams of the connection structures of the piezoelectric assembly 120 and the resistance element 130 according to some embodiments of the present specification.

[0099] In some embodiments, the resistive element 130 may be connected to the electrodes of the piezoelectric assembly 120. In some preferred embodiments, as shown in FIGS. 11A to 11C, the resistive element 130 may be connected in series to the positive electrode of the piezoelectric assembly 120. Correspondingly, the driving voltage may be applied across the entirety formed by the resistive element 130 and the piezoelectric assembly 120.

[0100] In some preferred embodiments, as shown in FIGS. 11D to 11F, the resistive element 130 may be connected in series to the negative electrode of the piezoelectric assembly 120. Correspondingly, the driving voltage may be applied across the entirety formed by the piezoelectric assembly 120 and the resistive element 130. In some embodiments, there may be a plurality of resistive elements 130, and the plurality of resistive elements 130 may be connected in series to the positive electrode and / or the negative electrode of the piezoelectric assembly 120 respectively. For example, one or more of the plurality of resistive elements 130 may be connected in series to the positive electrode of the piezoelectric assembly 120, and the remaining resistive elements 130 may be connected in series to the negative electrode of the piezoelectric assembly 120. Also for example, all of the plurality of resistive elements 130 may be connected in series to the positive electrode or the negative electrode of the piezoelectric assembly 120.

[0101] In some embodiments, the resistive element 130 may be connected to the electrodes of the piezoelectric assembly 120 via a conducting wire. As shown in FIG. 11A, one end of the resistive element 130 may be connected to the positive electrode of the piezoelectric assembly 120 via a conducting wire, and the other end may receive the driving voltage. Further, as shown in FIG. 11D, one end of the resistive element 130 may be connected to the negative electrode of the piezoelectric assembly 120 via a conducting wire, and the other end may receive the driving voltage.

[0102] In some embodiments, the resistive element 130 may be welded to the electrodes of the piezoelectric assembly 120. In some embodiments, the resistive element 130 may be welded to the positive electrode of the piezoelectric assembly 120. As shown in FIGS. 11B to 11C, one end (the welding point shown in the figure) of the resistive element 130 may be welded to the positive electrode of the piezoelectric assembly 120 by the conductive adhesive 131 and electrically connected to the piezoelectric assembly 120. Correspondingly, the driving voltage may be applied across the entire combination of the resistive element 130 and the piezoelectric assembly 120.

[0103] In some embodiments, the resistive element 130 may be welded to the negative electrode of the piezoelectric assembly 120. As shown in FIGS. 11E to 11F, one end of the resistive element 130 may be welded to the negative electrode of the piezoelectric assembly 120 by the conductive adhesive 131 and electrically connected to the piezoelectric assembly 120. Correspondingly, the driving voltage may be applied across the entire combination of the piezoelectric assembly 120 and the resistive element 130.

[0104] In some embodiments, in order to apply a driving voltage to the piezoelectric assembly 120 and the resistive element 130, the positive and negative electrodes of the piezoelectric assembly 120 may be drawn out from different sides of the piezoelectric assembly 120, respectively. As shown in FIGS. 11A to 11B and FIGS. 11D to 11E, for the piezoelectric assembly 120, the positive electrode may be drawn out from the first side 1201 of the piezoelectric assembly 120, and the negative electrode may be drawn out from the second side 1202 of the piezoelectric assembly 120.

[0105] In some embodiments, in order to save the space occupied by the piezoelectric assembly 120 and the resistive element 130, the positive and negative electrodes of the piezoelectric assembly 120 may be drawn out from the same side of the piezoelectric assembly 120. As shown in FIGS. 11C and 11F, for the piezoelectric assembly 120, both the positive and negative electrodes may be drawn out from the third side 1203 of the piezoelectric assembly 120.

[0106] In some embodiments, the resistive element 130 may include one or more resistors connected in series to the piezoelectric assembly 120. In some embodiments, the size of the resistive element 130 can be adjusted by adjusting the number and / or resistance value of the resistors.

[0107] In some embodiments, the resistive element 130 may include a conductive wire connected to the piezoelectric assembly 120. The conductive wire may be a circuit device through which the piezoelectric assembly 120 is electrically connected to other devices. As shown in FIGS. 11A and 11D, the conductive wire can connect the resistive element 130 and the piezoelectric assembly 120. In some embodiments, the conductive wire may include one or a combination of a conductive wire between the piezoelectric assembly 120 and the driving voltage, a conductive wire between the piezoelectric assembly 120 and the resistor, and a conductive wire between the piezoelectric assembly 120 and other devices.

[0108] In some embodiments, the resistance value of the resistive element 130 can be adjusted by adjusting the resistance value of the conductive wire. For example, the resistance value of the resistive element 130 can be adjusted by adjusting parameters of the form of the conductive wire, such as the cross-sectional area, length, meandering shape, etc. of the conductive wire to adjust the resistance value of the conductive wire.

[0109] In some embodiments, the resistive element 130 may include a conductive adhesive connected to the piezoelectric assembly 120. The conductive adhesive may be a circuit device through which the piezoelectric assembly 120 is electrically connected to other devices. As shown in FIGS. 11B, 11C, 11E or 11F, the conductive adhesive 131 can connect the resistive element 130 and the piezoelectric assembly 120. In some embodiments, the material of the conductive adhesive may include one or a combination of metals (such as gold, silver, copper, aluminum, zinc, iron, nickel), graphite, epoxy resin, acrylate resin, polyurethane, and may also include other conductive compounds. In some embodiments, the resistance value of the resistive element 130 can be adjusted by adjusting the material and usage amount of the conductive adhesive to adjust the resistance value of the conductive adhesive.

[0110] In some embodiments, the resistance element 130 may include one or more combinations of one or more resistors, a conductive wire connecting the piezoelectric assembly 120, and a conductive adhesive connecting the piezoelectric assembly 120, and may also include other devices having resistance characteristics. In some embodiments, the resistance value of the entire resistance element 130 may be adjusted by adjusting the resistance values of one or more devices in the resistance element 130.

[0111] FIG. 12 is a schematic configuration diagram of a printed circuit board according to some embodiments of the present specification.

[0112] In some embodiments, in order to save the volume of the acoustic device 100, the resistance element 130 may be disposed on a flexible printed circuit (abbreviated as FPC). As shown in FIG. 12, two resistors R t are respectively connected to the positive and negative electrodes of the piezoelectric assembly 120 and may be disposed on the conductive wires in the flexible printed circuit board 200 drawn from the electrodes of the piezoelectric assembly 120. The resistance element 130 may include the resistor R t , conductive wires, and conductive adhesives, etc. The resistance value of the resistance element 130 can be determined based on the resistance value of the resistor R t , the form of the conductive wire (for example, cross-sectional area, length, meandering shape, etc.) and the resistance value of the conductive adhesive.

[0113] In some embodiments, the resistance element 130 may include the electrodes of the piezoelectric assembly 120. For the positive and negative electrodes of the piezoelectric assembly 120 and the installation relationship of the piezoelectric assembly 120, reference may be made to the related content shown in FIG. 6 above, so the description is omitted here.

[0114] In some embodiments, since the electrodes also have certain resistance properties, the resistance value of the entire resistance element 130 can be adjusted by adjusting the resistance value of the electrodes of the piezoelectric assembly 120. The resistance value of the electrodes can be determined by Equation (6).

[0115]

Equation

[0116] Here, R p is the resistance value of the electrode, ρ is the resistivity of the electrode, L is the length of the electrode, and S is the cross-sectional area of the electrode. In some embodiments, the resistance value of the electrode can be adjusted by adjusting parameters such as the material, shape, and length of the electrode.

[0117] In some embodiments, at least a part of the material of the electrode of the piezoelectric assembly 120 may be one of the materials such as copper, gold, aluminum, tungsten, iron, or platinum, or other materials with appropriate resistivity. For example, by replacing a part of the material in the electrode of the piezoelectric assembly 120 from silver to copper, the resistivity changes, and the resistance value of the electrode also changes accordingly, thereby adjusting the resistance value of the resistance element 130.

[0118] In some embodiments, at least a part of the effective cross-sectional area of the electrode of the piezoelectric assembly 120 may be smaller than the contour cross-sectional area of the electrode, thereby increasing the resistance value of the resistance element 130 and adjusting the voltage and heat generation output of the piezoelectric assembly 120. Here, the effective cross-sectional area of the electrode is the cross-sectional area actually used when the electrode operates, and the contour cross-sectional area may be the cross-sectional area composed of the outermost edge lines of the electrode. In some embodiments, by controlling at least a part of the effective cross-sectional area of the electrode to be smaller than the contour cross-sectional area, the resistance value of the electrode can be increased to adjust the resistance value of the resistance element 130. In some embodiments, the shape of the effective cross-section of the electrode is adjusted, for example, by controlling the cross-section of the electrode to exhibit a net shape (for example, the lattice shape is other irregular shapes such as triangular, square, polygonal, circular, elliptical, etc.), the effective cross-sectional area of the electrode can be reduced.

[0119] FIGS. 13A to 13F are schematic views of the electrodes of the piezoelectric assembly according to some embodiments of the present specification.

[0120] In some embodiments, at least a partial cross-section of the electrodes of the piezoelectric assembly 120 may have a mesh structure or an S-shaped structure. As shown in FIGS. 13A to 13C, electrode a is the original rectangular electrode, electrodes b and c are mesh electrodes, and electrode d is an S-shaped electrode. The effective cross-sectional area is the area of the gray part, and the contour cross-sectional area is the rectangular area. That is, the effective cross-sectional area of electrode a is equal to the contour cross-sectional area of the electrode. Since the effective cross-sectional areas of electrodes b and c exhibit a mesh shape, the effective cross-sectional area is smaller than the contour cross-sectional area. Since the effective cross-sectional area of electrode d exhibits an S-shaped structure, the effective cross-sectional area is smaller than the contour cross-sectional area. In this way, under the conditions of the same material and the same length, the resistance value of electrode d is larger than the resistance values of electrodes b and c, and the resistance values of electrodes b and c are larger than the resistance value of electrode a.

[0121] In some embodiments, the local cross-sectional area of the electrodes of the piezoelectric assembly 120 may be changed to change the resistance value of the electrodes. For example, as shown in FIG. 13D, by reducing the cross-sectional area of the lead portions of the rectangular electrodes 310 and 320 to a circular shape, the resistance value of the electrodes can be changed, and further the resistance value of the resistance element 130 can be changed.

[0122] In some embodiments, the resistance value of the electrodes of the piezoelectric assembly 120 may be adjusted by changing the length of the electrodes, and the resistance value of the resistance element 130 may be adjusted. As shown in FIG. 13E, by increasing the length of the lead portions of the positive and negative electrodes of the piezoelectric assembly 120, the resistance value of the electrodes can be increased, and further the resistance value of the resistance element 130 can be increased.

[0123] In some embodiments, the resistance value of the electrodes of the piezoelectric assembly 120 may be adjusted by changing the thickness of the electrodes, and the resistance value of the resistance element 130 may be adjusted. As shown in FIG. 13F, compared with the thickness of the electrodes of the piezoelectric assembly 120 shown in FIG. 6, by increasing the thickness of the electrodes of the piezoelectric assembly 120 shown in FIG. 13F, the resistance value of the electrodes is increased, and further the resistance value of the resistance element 130 is increased.

[0124] In some embodiments, the acoustic device 100 may be a bone conduction acoustic device. Correspondingly, the vibration assembly 110 fits to the user's body tissue, and the sound waves emitted by the vibration assembly 110 are transmitted to the user's inner ear by the user's bone, enabling the propagation of sound. In some embodiments, the acoustic device 100 may further include a voltage boosting system. The voltage boosting system can improve the voltage output from a power source (e.g., a battery).

[0125] In some embodiments, the acoustic device 100 may further include a connecting component that connects the housing to the human body. In some embodiments, the connecting component may be a wearable device that fits the housing to the user. Exemplarily, the connecting component is a glasses frame, and the housing may be provided on the temple of the glasses frame. When the user wears the glasses frame, the housing contacts the human body, enabling the acoustic device 100 to transmit sound to the user. Also, for example, the connecting component is a headband, and the housing may be provided at one end of the headband. When the user wears the headband, the housing contacts the human body, enabling the acoustic device 100 to transmit sound to the user.

[0126] The beneficial effects according to the embodiments of this specification include, but are not limited to, the following (1) to (2). (1) By providing a resistance element and connecting it in series to the piezoelectric assembly for voltage division, the voltage across the piezoelectric assembly is reduced, thereby reducing the amplitude of the vibration of the vibration assembly in the medium and high frequency bands, reducing the sensitivity difference across the entire frequency band, and improving the balance of the high and low frequencies of the sound output from the acoustic device. (2) When the acoustic device is in the medium and high frequency bands, the series-connected resistance element further reduces the current flowing through the piezoelectric assembly in a voltage division manner, thereby reducing the thermal energy generated by the piezoelectric assembly, achieving the effect of temperature control, and improving the operational reliability of the acoustic device.

[0127] Although the basic concepts have been described above, it is obvious to those skilled in the art that the above detailed disclosure is merely presented as an example and does not limit this specification. Although not explicitly described in this specification, those skilled in the art can make various changes, improvements, and modifications to this specification. Since these changes, improvements, and modifications are intended to be suggested by this specification, they are within the spirit and scope of the exemplary embodiments of this specification.

[0128] Furthermore, to explain the embodiments of this specification, specific terms are used in this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" mean specific features, structures, or characteristics related to at least one embodiment of this specification. Therefore, it should be emphasized and understood that two or more references to "an embodiment" or "one embodiment" or "one alternative embodiment" in various parts of this specification do not necessarily all refer to the same embodiment. Also, specific features, structures, or characteristics in one or more embodiments of this specification may be appropriately combined.

[0129] Also, unless explicitly stated in the claims, the recited order of processing elements or sequences, the use of alphanumerics, or the use of other names in this specification does not limit the order of the procedures and methods in this specification. In the above disclosure, various useful embodiments of the invention that are currently considered are described through various examples, but such details are for illustrative purposes only. The appended claims are not limited to the disclosed embodiments, but rather are intended to cover all modifications and equivalent combinations within the spirit and scope of the embodiments of this specification. For example, the system assembly described above may be implemented by a hardware device, but may also be implemented by a software-only solution, for example, by installing the system described in an existing server or mobile device.

[0130] Similarly, in the foregoing description of the embodiments of this specification, for the purpose of simplifying this specification and facilitating the understanding of the embodiments of one or more inventions, it should be understood that various features may be grouped together in one embodiment, drawing, or its description. However, such a disclosure method should not be construed as reflecting an intention that the claimed subject matter requires more features than those recited in each claim. In fact, the features of an embodiment may sometimes be fewer than all the features of the single embodiment disclosed above.

[0131] In some embodiments, numbers are used to describe the number of components and attributes, and it should be understood that the numbers for describing such embodiments are modified by the modifier "about", "substantially", or "essentially" in some examples. Unless otherwise specified, "about", "substantially", or "essentially" indicates that the above numbers are allowed to vary by ±20%. Thus, in some embodiments, the numerical parameters used in the specification and claims are all approximate values that may vary according to the characteristics required by individual embodiments. In some embodiments, for numerical parameters, the defined number of significant digits should be considered and the normal rounding method should be applied. In some embodiments of this specification, although the numerical ranges and parameters for determining the range are approximate values, in specific embodiments, such numerical values are set as accurately as possible.

[0132] All patents, patent applications, published patent publications, and other materials such as papers, books, specifications, publications, documents, etc. referred to in this specification are incorporated herein by reference in their entirety, except for those application process documents that do not match or conflict with the content of this specification and those documents that may have a limiting effect on the broadest scope of the claims of this specification (currently or later related to this specification). In addition, if the explanations, definitions, and / or uses of terms in the attached materials of this specification do not match or conflict with the content described in this specification, the explanations, definitions, and / or uses of terms in this specification shall prevail.

[0133] Finally, it should be understood that the examples described in this specification are merely to illustrate the principles of the examples in this specification. Other variations may also be within the scope of this specification. Therefore, without limitation, by way of example, alternative configurations of the examples in this specification may be considered to be in accordance with the teachings of this specification. Thus, the examples in this specification are not limited to the examples clearly introduced and described in this specification.

Description of Reference Numerals

[0134] 100 Acoustic device 110 Vibration assembly 120 Piezoelectric assembly 123 Piezoelectric ceramic sheet 130 Resistive element 1231 First end 1232 Second end 1201 First side 1202 Second side 1203 Third side

Claims

1. A piezoelectric assembly that vibrates under the action of a driving voltage, A vibration assembly that is mechanically connected to the piezoelectric assembly, receives the vibration, and generates sound, A resistive element that is connected in series to the piezoelectric assembly to change the frequency response of the vibration assembly, such that the difference between the amplitude at 10 kHz and the amplitude at 1 kHz of the vibration of the vibration assembly does not exceed 20 dB, An acoustic device comprising: The piezoelectric assembly includes a plurality of piezoelectric ceramic sheets, The plurality of piezoelectric ceramic sheets are laminated, The plurality of piezoelectric ceramic sheets are respectively disposed in the first layer, second layer, third layer, and fourth layer of the piezoelectric assembly, An acoustic device, wherein the polarization directions of the piezoelectric ceramic sheets in the first layer and the second layer are different from the polarization directions of the piezoelectric ceramic sheets in the third layer and the fourth layer, The resistive element includes the electrodes of the piezoelectric assembly.

2. The acoustic device according to claim 1, wherein the resistive element is connected in series to the positive electrode of the piezoelectric assembly.

3. The acoustic device according to claim 2, wherein the resistive element is welded to the positive electrode of the piezoelectric assembly.

4. The acoustic device according to claim 1, wherein the resistive element is connected in series to the negative electrode of the piezoelectric assembly.

5. The acoustic device according to claim 4, wherein the resistive element is welded to the negative electrode of the piezoelectric assembly.

6. The acoustic device according to claim 4, wherein the positive electrode and the negative electrode of the piezoelectric assembly are drawn out from the same side of the piezoelectric assembly.

7. The acoustic device according to claim 1, wherein the resistive element includes a conductive wire connected to the piezoelectric assembly.

8. The acoustic device according to claim 1, wherein the resistive element includes a conductive adhesive connected to the piezoelectric assembly.

9. The acoustic device according to claim 1, wherein the resistive element is disposed on a flexible printed circuit board.

10. The acoustic device according to claim 1, wherein an effective cross-sectional area of at least a part of the electrodes of the piezoelectric assembly is smaller than a contour cross-sectional area of the electrodes.

11. The acoustic device according to claim 1, wherein the resistive element has a resistance value of 1 Ω to 1 kΩ.

12. The acoustic device according to claim 1, wherein in an operating state, the surface temperature of the piezoelectric assembly is lower than its Curie temperature.

13. The vibration assembly includes an elastic element and a mass element, and The acoustic device according to claim 1, wherein one end of the elastic element is connected to the piezoelectric assembly and the other end of the elastic element is connected to the mass element.

14. The acoustic device according to any one of claims 1 to 13, which is a bone conduction acoustic device.

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