A sound-generating device

Abstract

The present invention relates to a sound-generating device, comprising a base having a cavity and a plurality of cantilever diaphragms fixed on the base, each cantilever diaphragm comprising a fixed end fixed to the base and a free end extending from the fixed end to be suspended above the cavity, the free end comprising a first surface and a second surface arranged opposite to each other; the free end is spaced apart from the base or other free ends to form a gap, and the sound-generating device further comprises a first dielectric elastomer driver arranged on the first surface, a second dielectric elastomer driver arranged on the second surface, and a flexible connector fixed to the periphery of the gap to completely cover the gap. The present invention utilizes the dielectric elastomer drivers on the upper and lower sides to act on the cantilever diaphragms together, which can improve the linearity of the sound-generating device; and since there is no complex structure such as a voice coil and a magnetic circuit system, a thinner sound-generating device can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of electroacoustic conversion, and in particular relates to a sound-generating device. Background Art

[0002] Existing sound-generating devices usually include a vibration system and a magnetic circuit system. The vibration system includes a diaphragm and a voice coil. The voice coil is used to drive the diaphragm to vibrate to produce sound, resulting in a complex structure and a large-size structure. Currently, micro speakers using MEMS (micro-electromechanical system) technology usually adopt a piezoelectric structure. Although it has a simpler structure and can be made thinner and smaller than electromagnetic speakers, piezoelectric materials are expensive, resulting in higher costs. Summary of the invention

[0003] The purpose of the present invention is to solve the deficiencies in the prior art to at least a certain extent and to provide a sound-generating device.

[0004] To achieve the above-mentioned objectives, the present invention provides a sound-generating device, comprising a base having a cavity and a plurality of cantilever diaphragms fixed on the base, each of the cantilever diaphragms comprising a fixed end fixed to the base and a free end extending from the fixed end to be suspended in the cavity, the free end comprising a first surface and a second surface arranged opposite to each other; the free end is spaced from the base or the other free end to form a gap, the sound-generating device further comprising a first dielectric elastomer driver arranged on the first surface, a second dielectric elastomer driver arranged on the second surface, and a flexible connector fixed on the periphery of the gap to completely cover the gap.

[0005] Optionally, the first dielectric elastomer driver includes a first electrode layer, a first dielectric elastomer film, and a second electrode layer stacked sequentially on the first surface; the second dielectric elastomer driver includes a third electrode layer, a second dielectric elastomer film, and a fourth electrode layer stacked sequentially on the second surface.

[0006] Optionally, the cantilever diaphragm is made of metal or polymer compound; when the cantilever diaphragm is made of conductive metal material, a first insulating layer is further provided between the first surface and the first electrode layer, and a second insulating layer is further provided between the second surface and the second electrode layer.

[0007] Optionally, the cantilever diaphragm is made of a conductive metal material, and the first dielectric elastomer driver includes a first dielectric elastomer film and a second electrode layer stacked sequentially on the first surface; the second dielectric elastomer driver includes a second dielectric elastomer film and a fourth electrode layer stacked sequentially on the second surface.

[0008] Optionally, the flexible connector is integrally formed with the first dielectric elastomer films of a plurality of the first dielectric elastomer drivers.

[0009] Optionally, the second dielectric elastomer films of a plurality of the second dielectric elastomer actuators are interconnected to form a whole.

[0010] Optionally, the flexible connecting member is a flat plate or arch-shaped structure, and is spaced apart from the first dielectric elastomer driver.

[0011] Optionally, the driving voltage of the first dielectric elastomer driver and the driving voltage of the second dielectric elastomer driver are alternating voltages with the same period and a phase difference of 180°.

[0012] Optionally, a plurality of the cantilever diaphragms are symmetrically distributed about a central axis, and a free end of the cantilever diaphragm extends toward the center of the cavity in a tapered manner.

[0013] Optionally, the Young's modulus of the first dielectric elastomer film and the second dielectric elastomer film is 1 kPa to 100 MPa.

[0014] Compared with the related art, the sound-generating device of the present invention utilizes the dielectric elastomer drivers on the upper and lower sides of the cantilever diaphragm to jointly act on the cantilever diaphragm to achieve vibration sound generation, which can improve the linearity of the sound-generating device; and because there are no complex structures such as voice coils and magnetic circuit systems, the structure of the sound-generating device is simpler and the assembly is more convenient. The thickness of the entire vibration component can be as low as 20um or less, resulting in a thinner sound-generating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 It is a structural schematic diagram of a first embodiment of a sound-generating device of the present invention;

[0017] Figure 2 This is a schematic diagram of the principle of the dielectric elastomer driver of the present invention;

[0018] Figure 3 for Figure 1 The signal connection diagram of the sound generating device shown;

[0019] Figure 4 for Figure 1 A schematic diagram of the vibration state of the sound-generating device shown;

[0020] Figure 5 It is a structural schematic diagram of Embodiment 2 of the sound-generating device of the present invention;

[0021] Figure 6 A schematic diagram of the structure of a third embodiment of the sound-generating device of the present invention;

[0022] Figure 7 Another structural schematic diagram of the third embodiment of the sound-generating device of the present invention;

[0023] Figure 8 It is a structural schematic diagram of a fourth embodiment of the sound-generating device of the present invention;

[0024] Fig. 9 A top plan view of the sound-generating device of the present invention. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention. All other embodiments obtained by ordinary technicians in the field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] See also Figure 1 Embodiment 1 of the present invention provides a sound-generating device, including a substrate 10 having a cavity 11 and a plurality of cantilever diaphragms 20 fixed on the substrate 10, each cantilever diaphragm 20 includes a fixed end 21 fixed to the substrate 10 and a free end 22 extending from the fixed end 21 to be suspended above the cavity 11, the free end 22 includes a first surface (i.e., an upper surface) and a second surface (i.e., a lower surface) arranged opposite to each other; the free end 22 is spaced apart from another free end 22 to form a gap 23, and a flexible connector 50 is used to seal the gap 23.

[0028] A first electrode layer 31 , a first dielectric elastomer film 32 , and a second electrode layer 33 are sequentially stacked on the first surface, and a third electrode layer 41 , a second dielectric elastomer film 42 , and a fourth electrode layer 43 are sequentially stacked on the second surface.

[0029] It should be understood that the first to fourth electrode layers are preferably flexible electrodes made of materials such as graphite powder or carbon-based conductive glue; the first dielectric elastomer film 32 and the second dielectric elastomer film 42 are made of polymer compounds, preferably with a thickness of 0.1um to 1000um. The stiffness and linear range of the dielectric elastomer film within this thickness range are more moderate, and the Young's modulus is 1kPa to 100MPa. The elasticity and stiffness of the dielectric elastomer film within this film thickness range are good, and the polarization of the sound-emitting device is small.

[0030] That is to say, the first electrode layer 31, the first dielectric elastomer film 32 and the second electrode layer 33 above the cantilever diaphragm 20 together form a first dielectric elastomer actuator 30 (Dielectric Elastomers Actuators--DEA). In this embodiment, the flexible connector 50 and the first dielectric elastomer films 32 of several first dielectric elastomer actuators 30 are an integrally formed structure. At this time, the flexible connector 50 serves as a part of the first dielectric elastomer film 32, that is, several first dielectric elastomer actuators 30 share one first dielectric elastomer film 32, and the first dielectric elastomer film 32 is used to seal the top of the gap 23.

[0031] The third electrode layer 41 , the second dielectric elastomer film 42 and the fourth electrode layer 43 below the cantilever diaphragm 20 together form a second dielectric elastomer driver 40 .

[0032] The dielectric elastomer driver is a new type of soft driver with good scalability, good output performance, stability and easy control. The first dielectric elastomer driver 30 above the cantilever diaphragm 20 is used as an example. Figure 2 As shown, when a certain potential difference is applied to the second electrode layer 33 and the first electrode layer 31, the generated electric field force causes the two electrodes to attract each other and move closer to each other, so as to squeeze the first dielectric elastomer film 32 in the middle, so that the thickness of the first dielectric elastomer film 32 is reduced while the in-plane area is increased, resulting in elongation in the length direction, that is, the length changes from L0 to L1. At this time, since the elongation of the first dielectric elastomer driver 30 is limited by the first surface of the cantilever diaphragm 20, stress is introduced on the first surface, causing the cantilever diaphragm 20 to bend toward the second surface.

[0033] Since the electric field force of the dielectric elastomer actuator is proportional to the square of the applied voltage (F∝V 2), if the dielectric elastomer driver is only arranged on one surface of the cantilever diaphragm 20, serious nonlinear problems will occur. Therefore, in the embodiment of the present invention, the first dielectric elastomer driver 30 and the second dielectric elastomer driver 40 are respectively arranged on the upper and lower surfaces of the cantilever diaphragm 20, and the driving voltage of the first dielectric elastomer driver 30 and the driving voltage of the second dielectric elastomer driver 40 are alternating voltages with the same period and a phase difference of 180°, so that the cantilever diaphragm 20 repeatedly vibrates the air in the up and down directions to generate sound.

[0034] Specific use Figure 3 The driving signal shown, that is, the electric field force generated by the first dielectric elastomer driver 30 is: F 1 ∝(V 0 +V(t)) 2 , the electric field force generated by the second dielectric elastomer driver 40 is: F 2 ∝(V 0 -V(t)) 2 , where V 0 is the DC bias, V(t) is the audio signal, F 1 and F 2 The direction of the action on the cantilever diaphragm 20 is opposite, so the final vibration direction is determined by F 1 -F 2 Decision, such as Figure 4 As shown, after calculation, we know that F 1 -F 2 ∝4*V 0 *V(t), that is, the driving force is linearly related to the audio signal, which can greatly improve the linearity of the sound-generating device.

[0035] In this embodiment, the second dielectric elastomer film 42 of several second dielectric elastomer drivers 40 is an integrally formed structure and completely covers the bottom of the gap 23; therefore, the first dielectric elastomer film 32 and the second dielectric elastomer film 42 can serve as the elastic layer of the dielectric elastomer driver, and can also directly cover the gap between adjacent cantilever diaphragms 20 to ensure that there is no sound leakage, making the structure simpler.

[0036] Furthermore, the cantilever diaphragm 20 preferably uses a polymer compound, for example, it can be any one of polyimide, polyetherimide, polyetheretherketone, polyphenylene sulfide, and thermoplastic elastomer. The cantilever diaphragm 20 can also be a composite of the above-mentioned multiple material layers. Those skilled in the art can choose according to actual needs, and the present application does not limit this.

[0037] Preferably, the cantilever diaphragm 20 can also be made of metal material, for example, it can be any one of aluminum, copper, and stainless steel; and when the cantilever diaphragm 20 is made of metal material, a first insulating layer 61 is also provided between the first surface and the first electrode layer 31 to isolate the connection between the first electrode layer 31 and the metal cantilever diaphragm 20; a second insulating layer 62 is also provided between the second surface and the third electrode layer 41 to isolate the connection between the third electrode layer 41 and the metal cantilever diaphragm 20; thereby avoiding the short circuit problem caused by the direct connection between the electrode of the dielectric elastomer driver and the metal cantilever diaphragm 20.

[0038] The Young's modulus of the cantilever diaphragm 20 is preferably 1 MPa to 500 GPa. Within this Young's modulus range, the cantilever diaphragm 20 has good elasticity and rigidity, so that the polarization of the sound-generating device is small.

[0039] The cavity 11 can be divided into one or more vibration areas, and at least two cantilever diaphragms 20 can be arranged in each vibration area. In the present embodiment, two cantilever diaphragms 20 are arranged in one vibration area, and the two cantilever diaphragms 20 are symmetrically arranged with each other, that is, the free ends 22 of the two cantilever diaphragms 20 are spaced relative to each other to form a gap 23, and the first dielectric elastomer drivers 30 on the upper sides of the two cantilever diaphragms 20 share a first dielectric elastomer film 32, and the second dielectric elastomer drivers 40 on the lower sides of the two cantilever diaphragms 20 share a second dielectric elastomer film 42. This optimizes the structure of the sound-generating device, facilitates the assembly of the sound-generating device, and improves the connection strength of each component.

[0040] Preferably, combined Fig. 9As shown, in this embodiment, six cantilever diaphragms 20 are arranged in the cavity 11 of the substrate 10, and the six cantilever diaphragms 20 are symmetrically distributed about the central axis, and the free ends 22 of the cantilever diaphragms 20 extend toward the center of the cavity 11 in a tapered manner. In other words, the cantilever diaphragm 20 is roughly trapezoidal in shape, including a first side fixedly connected to the substrate 10, a second side opposite to the first side, and two oblique sides connected to the first side and the second side, and the length of the first side is greater than the length of the second side. A gap 23 is formed between two adjacent oblique sides between two cantilever diaphragms 20, that is, a total of six gaps 23 are formed, and the six second sides of the six cantilever diaphragms 20 together form a hexagonal hollow area connected to the six gaps 23. A first electrode layer 31 is provided on the upper side of each cantilever diaphragm 20, and an integral first dielectric elastomer film 32 is provided on the upper surface of the six first electrode layers 31, and corresponding second electrode layers 33 are provided on the upper surface of the first dielectric elastomer film 32 at positions corresponding to the first electrode layers 31; a third electrode layer 41 is provided on the lower side of each cantilever diaphragm 20, and an integral second dielectric elastomer film 42 is provided on the lower surface of the six third electrode layers 41, and corresponding fourth electrode layers 43 are provided on the lower surface of the second dielectric elastomer film 42 at positions corresponding to the third electrode layers 41. The projection contours of the first to fourth electrode layers in the vibration direction are the same as the projection contours of the corresponding cantilever diaphragm 20 in the vibration direction, or the projection contours of the first to fourth electrode layers are located within and similar to the projection contours of the cantilever diaphragm 20.

[0041] See also Figure 5 As shown, a sound-generating device provided in the second embodiment of the present invention is different from the above-mentioned first embodiment in that the cantilever diaphragm 20 in this embodiment is made of metal material, and the first electrode layer, the third electrode layer and the two insulating layers are omitted, so that the cantilever diaphragm 20 serves as a common electrode function, that is, the first dielectric elastomer film 32 and the second electrode layer 33 are directly stacked in sequence on the upper surface of the cantilever diaphragm 20, and the cantilever diaphragm 20, the first dielectric elastomer film 32 and the second electrode layer 33 together form a first dielectric elastomer driver 30; the second dielectric elastomer film 42 and the fourth electrode layer 43 are directly stacked in sequence on the lower surface of the cantilever diaphragm 20, and the cantilever diaphragm 20, the second dielectric elastomer film 42 and the fourth electrode layer 43 together form a second dielectric elastomer driver 40, thereby optimizing the assembly structure and simplifying the circuit connection, so as to obtain a thinner and smaller sound-generating device.

[0042] See also Figure 6 and Figure 7As shown, a sound-generating device provided by the third embodiment of the present invention is different from the first embodiment described above in that the first dielectric elastomer driver 30 and the second dielectric elastomer driver 40 on the upper and lower sides of the cantilever diaphragm 20 in this embodiment are independent structures, that is, each dielectric elastomer driver has its own dielectric elastomer film. The sound-generating device of this embodiment also includes a flexible connector 50 fixed to the periphery of the gap 23 to completely cover the gap 23. The flexible connector 50 is fixed to the upper surface of the cantilever diaphragm 20 and is spaced apart from the first dielectric elastomer driver 30. The flexible connector 50 is preferably made of Figure 6 The arch-shaped structure shown in FIG. 1 can reduce the stiffness and increase the amplitude; Figure 7 The flat plate structure shown is not limited to this invention.

[0043] See also Figure 8 As shown, a sound-generating device provided in Embodiment 4 of the present invention is different from Embodiment 1 described above in that, in this embodiment, a support portion 12 is formed on the base 10 protruding from the inner side of the cavity 11 toward the cantilever diaphragm 20, and a gap 23 is formed between the support portion 12 and the free end 22 of the cantilever diaphragm 20, and a flexible connector 50 is provided on the free end 22 of the cantilever diaphragm 20 and the support portion 12 to completely cover the gap 23, or the first dielectric elastomer film 32 of the first dielectric elastomer driver 30 is extended and fixed on the support portion 12 to completely cover the gap 23.

[0044] Compared with the related art, the sound-generating device of the present invention utilizes the dielectric elastomer drivers on the upper and lower sides of the cantilever diaphragm 20 to jointly act on the cantilever diaphragm 20 to achieve vibration sound generation, which can improve the linearity of the sound-generating device; and because there are no complex structures such as voice coils and magnetic circuit systems, the structure of the sound-generating device is simpler and the assembly is more convenient. The thickness of the entire vibration component (i.e., the thickness between the second electrode layer 33 and the fourth electrode layer 43) can be as low as less than 20um, thereby obtaining a thinner sound-generating device.

[0045] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0046] The above is a description of the technical solution provided by the present invention. For those skilled in the art, according to the ideas of the embodiments of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A sound-generating device, comprising a substrate having a cavity and a plurality of cantilever diaphragms fixed on the substrate, each of the cantilever diaphragms comprising a fixed end fixed to the substrate and a free end extending from the fixed end to be suspended in the cavity, the free end comprising a first surface and a second surface arranged opposite to each other; characterized in that: The free end is spaced from the base or other free ends to form a gap, and the sound-generating device also includes a first dielectric elastomer driver arranged on the first surface, a second dielectric elastomer driver arranged on the second surface, and a flexible connector fixed on the periphery of the gap to completely cover the gap, the first dielectric elastomer driver includes a first dielectric elastomer film arranged on the first surface, and the flexible connector is integrally formed with the first dielectric elastomer films of several of the first dielectric elastomer drivers.

2. The sound generating device according to claim 1, characterized in that: The first dielectric elastomer driver also includes a first electrode layer and a second electrode layer, and the first electrode layer, the first dielectric elastomer film and the second electrode layer are stacked in sequence on the first surface; the second dielectric elastomer driver includes a third electrode layer, a second dielectric elastomer film and a fourth electrode layer stacked in sequence on the second surface.

3. The sound-generating device according to claim 2, characterized in that: The cantilever diaphragm is made of metal or polymer compound; when the cantilever diaphragm is made of conductive metal material, a first insulating layer is further provided between the first surface and the first electrode layer, and a second insulating layer is further provided between the second surface and the third electrode layer.

4. The sound generating device according to claim 1, characterized in that: The cantilever diaphragm is made of a conductive metal material, the first dielectric elastomer driver also includes a second electrode layer, the first dielectric elastomer film and the second electrode layer are sequentially stacked on the first surface; the second dielectric elastomer driver includes a second dielectric elastomer film and a fourth electrode layer sequentially stacked on the second surface.

5. The sound generating device according to any one of claims 2 to 4, characterized in that: The second dielectric elastomer films of a plurality of the second dielectric elastomer actuators are connected to each other to form a whole.

6. The sound generating device according to claim 1, characterized in that: The flexible connecting member is a flat plate or arch-shaped structure and is spaced apart from the first dielectric elastomer driver.

7. The sound generating device according to claim 1, characterized in that: The driving voltage of the first dielectric elastomer driver and the driving voltage of the second dielectric elastomer driver are alternating voltages with the same period and a phase difference of 180°.

8. The sound generating device according to claim 1, characterized in that: The plurality of cantilever diaphragms are symmetrically distributed about the central axis, and the free ends of the cantilever diaphragms extend toward the center of the cavity in a tapered manner.

9. The sound-generating device according to any one of claims 2 to 4, characterized in that: The Young's modulus of the first dielectric elastomer film and the second dielectric elastomer film is 1 kPa to 100 MPa.

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