Piezoelectric speaker
By designing a support unit, a piezoelectric unit, and an additional diaphragm layer in the piezoelectric loudspeaker, the stress distribution was optimized, the problem of limited diaphragm displacement was solved, and the sound pressure level and frequency characteristics of the loudspeaker were improved.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- AAC TECHNOLOGIES PTE LTD
- Filing Date
- 2025-09-04
- Publication Date
- 2026-07-23
AI Technical Summary
In existing silicon-based microelectromechanical loudspeakers, the displacement of the diaphragm is restricted by the organic membrane, resulting in a limited sound pressure level.
A piezoelectric loudspeaker is designed, comprising a substrate, a support unit, a piezoelectric unit, and an additional film layer. By setting slits on the support unit and the piezoelectric unit and using a stress adjustment layer, the stress distribution is optimized, causing the piezoelectric unit to bend downward in the initial state and increasing the displacement of the additional film layer.
It improves sound pressure level (SPL) and frequency response, reduces air leakage, and enhances the maximum sound pressure output of the loudspeaker.
Smart Images
Figure CN2025118971_23072026_PF_FP_ABST
Abstract
Description
piezoelectric loudspeaker Technical Field
[0001] This invention relates to the field of loudspeaker technology, and in particular to a piezoelectric loudspeaker. Background Technology
[0002] In silicon-based microelectromechanical loudspeakers, the use of an organic diaphragm on the diaphragm can prevent air leakage, thereby improving the sound pressure level (SPL) and reducing total harmonic distortion (THD). However, the displacement of the loudspeaker's diaphragm is limited by the organic diaphragm, thus restricting the achievable SPL. Technical issues
[0003] The purpose of this invention is to provide a piezoelectric loudspeaker to solve the technical problems in the prior art. Technical solutions
[0004] This invention provides a piezoelectric loudspeaker, comprising:
[0005] Substrate, wherein a back cavity is provided through the substrate;
[0006] A support unit is disposed on the substrate and covers the back cavity. A first slit is provided through a portion of the support unit to divide the support unit into a first support portion and a second support portion. The second support portion is located on the outer periphery of the first support portion and along the vibration direction of the piezoelectric loudspeaker. The first support portion protrudes further into the back cavity than the second support portion.
[0007] A piezoelectric unit is disposed on the support unit. A second slit is provided through a portion of the piezoelectric unit to divide the piezoelectric unit into a first piezoelectric part and a second piezoelectric part. The second piezoelectric part is located on the outer periphery of the first piezoelectric part. The first piezoelectric part is supported on the first support unit, and the second piezoelectric part is supported on the second support unit. Along the vibration direction of the piezoelectric speaker, the first piezoelectric part protrudes further towards the back cavity than the second piezoelectric part.
[0008] An additional film layer is disposed on the piezoelectric unit and is also formed at a position corresponding to the second slit.
[0009] In the piezoelectric loudspeaker described above, preferably, a stress-adjusting layer is provided between the piezoelectric unit and the additional film layer, the stress-adjusting layer covering the surfaces of the first piezoelectric part and the second piezoelectric part.
[0010] In a piezoelectric loudspeaker as described above, preferably, a portion of the additional diaphragm layer fills the second slit.
[0011] In a piezoelectric loudspeaker as described above, preferably, the additional diaphragm layer is not filled within the first slit.
[0012] In the piezoelectric loudspeaker described above, preferably, the second support portion includes a plurality of sub-support portions disposed around the first support portion and spaced apart from each other by a first partition groove, and the second piezoelectric portion includes a plurality of sub-piezoelectric portions disposed around the first piezoelectric portion and spaced apart from each other by a second partition groove; the sub-piezoelectric portions are disposed in one-to-one correspondence with the sub-support portions, the first slit is connected to the second slit, and the additional film layer only covers the gaps between the plurality of sub-piezoelectric portions and the second slit.
[0013] In the piezoelectric loudspeaker described above, preferably, the plurality of sub-supports are connected to the first support via a first elastic beam disposed in the first slit; the plurality of sub-piezoelectric parts are connected to the first piezoelectric part via a second elastic beam disposed in the second slit.
[0014] In a piezoelectric loudspeaker as described above, preferably, the Young's modulus of the additional diaphragm layer is less than or equal to 2 GPa.
[0015] In a piezoelectric loudspeaker as described above, preferably, the additional diaphragm layer is an elastomer. Beneficial effects
[0016] Compared to existing technologies, this invention adjusts the stress of the support unit, piezoelectric unit, and additional film layer or stress-adjusting layer to cause the piezoelectric unit to bend downwards (towards the back cavity) in its initial state. This optimizes the stress of each layer during displacement, resulting in greater displacement of the additional film layer and effectively improving the SPL (Special Purity Level). Furthermore, by providing a stress-adjusting layer between the piezoelectric unit and the additional film layer, both the support unit and the piezoelectric unit can bend downwards in their initial state. Attached Figure Description
[0017] Figure 1 is a cross-sectional schematic diagram of the piezoelectric loudspeaker according to an embodiment of the present invention;
[0018] Figure 2 is an exploded structural diagram of the piezoelectric loudspeaker according to an embodiment of the present invention;
[0019] Figure 3 is a top view of the support unit according to an embodiment of the present invention;
[0020] Figure 4 is a top view of the piezoelectric unit according to an embodiment of the present invention;
[0021] Figure 5 is a top view of the additional membrane layer in an embodiment of the present invention.
[0022] Explanation of reference numerals in the attached figures:
[0023] 10-Substrate, 11-Back cavity, 12-First silicon layer, 13-First oxide layer;
[0024] 20-Support unit, 201-First support part, 202-Second support part, 2021-Sub-support part, 2022-First elastic beam; 21-Second silicon layer, 22-Second oxide layer, 23-First slit, 24-First partition groove;
[0025] 30-Piezoelectric unit, 301-First piezoelectric part, 302-Second piezoelectric part, 3021-Sub-piezoelectric part, 3022-Second elastic beam, 31-First electrode layer, 32-Piezoelectric layer, 33-Second electrode layer, 34-Second slit, 35-Second partition groove;
[0026] 40 - Additional membrane layer, 41 - First opening, 42 - Second opening, 43 - Curved portion;
[0027] 50 - Stress-regulating layer;
[0028] 60 - First metal pad;
[0029] 70 - Second metal pad. The best embodiment of the present invention
[0030] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0031] As shown in Figures 1 to 5, an embodiment of the present invention provides a piezoelectric loudspeaker. The piezoelectric loudspeaker includes a substrate 10, a support unit 20, a piezoelectric unit 30, an additional film layer 40, and a stress-adjusting layer 50, wherein:
[0032] The substrate 10 includes a first silicon layer 12 and a first oxide layer 13 stacked sequentially along the vibration direction of the piezoelectric loudspeaker. Referring to FIG1, the first silicon layer 12 and the first oxide layer 13 are stacked sequentially from bottom to top. A back cavity 11 is formed within the substrate 10. Preferably, the inner contour surface of the back cavity 11 is a circular groove structure. The back cavity 11 passes through the first silicon layer 12 and the first oxide layer 13 sequentially. In one feasible embodiment, the first oxide layer 13 of SiO2 material is formed on the first silicon layer 12 using methods such as vapor deposition, thermal oxidation, or chemical vapor deposition (CVD).
[0033] A support unit 20 is disposed on the substrate 10 and covers the back cavity 11. The support unit 20 includes a second silicon layer 21 and a second oxide layer 22 stacked sequentially along the vibration direction of the piezoelectric loudspeaker. Referring to FIG1, the second silicon layer 21 and the second oxide layer 22 are stacked sequentially from bottom to top. At least a portion of the second silicon layer 21 is exposed on the back cavity 11 side. The piezoelectric unit 30 is formed on the second oxide layer 22, and the second silicon layer 21 is formed on the first oxide layer 13 by means of bonding a silicon wafer to the first oxide layer 13. Regarding the second oxide layer 22, at least one second oxide layer 22 can be grown on the second silicon layer 21 by applying thermal oxidation, vapor deposition or CVD to the surface of the second silicon layer 21. The material of the second silicon layer 21 can be the same as that of the first silicon layer 12. The first oxide layer 13 is located below the second silicon layer 21 and has a significantly lower etching rate compared to the second silicon layer 21. When etching to form a slit or back cavity 11, it ensures that the etching stops accurately at the junction of the first oxide layer 13 and the second silicon layer 21.
[0034] A piezoelectric unit 30 is formed on the support unit 20. The piezoelectric unit 30 includes a first electrode layer 31, a piezoelectric layer 32, and a second electrode layer 33 stacked sequentially along the vibration direction of the piezoelectric loudspeaker. Referring to FIG1, from bottom to top, the first electrode layer 31, the piezoelectric layer 32, and the second electrode layer 33 are stacked sequentially. Wherein:
[0035] The first electrode layer 31 is formed on the second oxide layer 22 by physical vapor deposition (PVD) (electron beam vapor deposition or magnetron sputtering). Additionally, the first electrode layer 31 is patterned using photolithography. The first electrode layer 31 is connected to the bottom electrode pad (not shown) via bottom electrode leads (not shown). The material of the first electrode layer 31 can be one or more of Al, Mo, W, Pt, Cu, Ag, Au, and ZrN, or other materials with good conductivity. In one feasible embodiment, the material of the first electrode layer 31 is platinum (Pt) or molybdenum (Mo).
[0036] A piezoelectric layer 32 is deposited on the first electrode layer 31. The piezoelectric layer 32 is mechanically vibrated by an alternating electric field. The piezoelectric layer 32 can be made of lead zirconate titanate, aluminum nitride, barium titanate, or any other piezoelectric material. In one feasible embodiment, the piezoelectric layer 32 is made of lead zirconate titanate (PZT).
[0037] The second electrode layer 33 is formed on the piezoelectric layer 32 by PVD (e.g., electron beam vapor deposition or magnetron sputtering) and patterned by photolithography. The second electrode layer 33 is connected to the top electrode pad (not shown) through a top electrode lead (not shown). The material of the second electrode layer 33 can be one or more of Al, Mo, W, Pt, Cu, Ag, Au, and ZrN, or other materials with good conductivity. In one feasible embodiment, the material of the second electrode layer 33 is platinum (Pt) or molybdenum (Mo).
[0038] An additional film layer 40 is disposed on the piezoelectric unit 30 and on the side between the first piezoelectric part 301 and the second piezoelectric part 302 forming the piezoelectric unit 30. The additional film layer 40 functions as a vibrating plate (partition).
[0039] A stress-regulating layer 50 is disposed between the piezoelectric unit 30 and the additional film layer 40, and the stress-regulating layer 50 covers the surfaces of the first piezoelectric part 301 and the second piezoelectric part 302. The stress-regulating layer 50 also serves a passivation function. The stress-regulating layer 50 relates to compressive stress, and its material is, for example, composed of SiN, Al2O3, or TiO2.
[0040] A through hole is provided in the substrate 10 to form a back cavity 11.
[0041] A first slit 23 is provided through a plurality of first elastic beams 2022 (described later) on the support unit 20, dividing the support unit 20 into a first support portion 201 and a second support portion 202 separated by the plurality of first elastic beams 2022. The first support portion 201 is located in the central part of the support unit 20, and the second support portion 202 is located on the outer periphery of the first support portion 201. The first support portion 201 and the second support portion 202 are initially located on different planes due to the action of the additional membrane layer 40 and the stress adjustment layer 50. Therefore, along the vibration direction of the piezoelectric loudspeaker, the first support portion 201 is configured to protrude into the back cavity 11.
[0042] A piezoelectric unit 30 has multiple first elastic beams 3022 (described later) and a second slit 34 extending through it, dividing the piezoelectric unit 30 into a first piezoelectric section 301 and a second piezoelectric section 302 separated by the multiple first elastic beams 3022. The first piezoelectric section 301 is located in the center of the piezoelectric unit 30, and the second piezoelectric section 302 is located on the outer periphery of the first piezoelectric section 301. The first piezoelectric section 301 is supported on the first support section 201, and the second piezoelectric section 302 is supported on the second support section 202. The first piezoelectric section 301 and the second piezoelectric section 302 are initially located on different planes due to the additional film layer 40 and the stress adjustment layer 50. Therefore, along the vibration direction of the piezoelectric loudspeaker, the first piezoelectric section 301 and the first support section 201 protrude together toward the back cavity 11. Due to the presence of the second slit 34, the overall stiffness of the piezoelectric unit 30 can be adjusted, thereby improving the maximum sound pressure output and frequency response of the loudspeaker.
[0043] Due to the action of the additional film layer 40 of the first support portion 201 and the stress adjustment layer 50 of the first piezoelectric portion 301, a bent portion 43 is formed at the position corresponding to the second slit 34. The bent portion 43 has an inner first end and an outer second end. Along the vibration direction of the piezoelectric speaker, the first end of the bent portion 43 protrudes further towards the back cavity 11 than the second end of the bent portion 43. The portion of the additional film layer 40 connected to the first end of the bent portion 43 is located above the first piezoelectric portion 301, and the portion of the additional film layer 40 connected to the second end of the bent portion 43 is located above the second piezoelectric portion 302. The bent portion 43 effectively covers the gap between the first support portion 201 and the first piezoelectric portion 301 and the second support portion 202 and the second piezoelectric portion 302, preventing air leakage during vibration, thereby effectively improving SPL.
[0044] By providing a stress-adjusting layer 50 between the piezoelectric unit 30 and the additional film layer 40, the additional film layer 40 can bulge downwards, significantly improving the SPL (Special Power Proportion). Furthermore, initially, since both the first piezoelectric part 301 and the first support part 201 are concave relative to the second piezoelectric part 302 and the second support part 202, when deformed in the tensile direction by an electric field applied by the piezoelectric film 32, the support unit 20, the piezoelectric unit 30, and the additional film layer 40 are in an upward-bending state. This increases the movement (displacement) of the additional film layer 40, effectively improving the SPL. Although in this invention, the downward bulge is achieved by combining the stress-adjusting layer 50 with the action of the additional film layer 40, it is possible to omit the stress-adjusting layer 50 if the additional film layer 40 can be adjusted to bulge downwards.
[0045] In the embodiments provided by the present invention, a portion of the additional film layer 40 fills the second slit 34 but not the first slit 23. The additional film layer 40 partially fills the second slit 34, thereby reducing sound pressure loss caused by air leakage due to the second slit 34 and increasing the adhesion of the additional film layer 40. Furthermore, since it does not fill the first slit 23, the restriction on the movement of the first support portion 201 and the first piezoelectric portion 301 is reduced.
[0046] Referring to Figures 3 and 4, the second support portion 202 includes a plurality of sub-support portions 2021 disposed around the first support portion 201 and spaced apart from each other by a first partition groove 24 extending from the first support portion 201 to near the end of the second support portion 202. Because the second support portion 202 and the first support portion 201 are disposed at certain intervals based on a first elastic beam 2022 between the sub-support portions 2021, the maximum sound pressure level output and frequency response of the loudspeaker are improved.
[0047] The second piezoelectric section 302 includes a plurality of sub-piezoelectric sections 3021 disposed around the first piezoelectric section 301 and spaced apart from each other by a second partition groove 35 extending from the first piezoelectric section 301 to near the end of the second piezoelectric section 302. Because the second piezoelectric section 302 and the first piezoelectric section 301 are disposed at a certain interval based on a second elastic beam 3022 between the sub-piezoelectric sections 3021, the maximum sound pressure level output and frequency response of the loudspeaker are improved.
[0048] Sub-piezoelectric units 3021 and sub-support units 2021 are arranged in a one-to-one correspondence. The first slit 23 and the second slit 34 are connected. The additional film layer 40 covers at least the second partition groove 35 and its vicinity near the end of the first piezoelectric unit 301 extending from the multiple sub-piezoelectric units 3021 to the second piezoelectric unit 302, as well as the second slit 34 and the second elastic beam 3022 and their vicinity, thereby reducing the restriction on the movement of the piezoelectric unit 30. When the first piezoelectric unit 301 undergoes bending deformation, its periphery is not excessively restricted, further improving SPL and structural reliability.
[0049] Referring to Figures 3 and 4, the multiple sub-supports 2021 are connected to the first support 201 by a first elastic beam 2022. The first elastic beam 2022 is disposed in the first slit 23. By providing the first elastic beam 2022, the overall stiffness of the second support 202 is reduced.
[0050] Multiple sub-piezoelectric units 3021 are connected to the first piezoelectric unit 301 via a second elastic beam 3022, which is disposed in the second slit 34. By providing the second elastic beam 3022, the overall stiffness of the second piezoelectric unit 302 is reduced.
[0051] Preferably, the Young's modulus of the additional film layer 40 is less than or equal to 2 GPa. Additionally, the additional film layer 40 possesses a certain degree of flexibility. Based on these factors, restrictions on the movement of the piezoelectric element 30 are reduced.
[0052] In one feasible embodiment, the additional film layer 40 is composed of an elastomer, specifically, of epoxy resin or silicone rubber (e.g., PDMS (polydimethylpolysiloxane)). Methods for forming and shaping the additional film layer 40 may include spin coating, roll forming, photolithography, or patterning by peeling.
[0053] Furthermore, the additional film layer 40 is not filled within the second slit 34 nor within the first slit 23. This makes the deformation of the additional film layer 40 more compliant, reducing the restriction on the vibration of the piezoelectric unit 30. When the piezoelectric unit 30 undergoes bending deformation, its periphery is not excessively restricted, further improving SPL and structural reliability.
[0054] In the embodiments provided by the present invention, the piezoelectric loudspeaker has a first opening 41 and a second opening 42. Wherein:
[0055] The first opening 41 sequentially penetrates the additional film layer 40, the second electrode layer 33, and the piezoelectric layer 32. The through-hole formed through this penetration is coated with, for example, the same material as the stress-adjusting layer 50. Then, the first opening 41 reaching the first electrode layer 31 is formed again on the through-hole in a manner that avoids contact with the second electrode layer 33, etc. A first metal pad 60 is disposed on the first electrode layer 31 located at the first opening 41 for electrical connection with the first electrode layer 31. In one feasible embodiment, a patterned hard mask is fabricated on a portion of the additional film layer 40 other than the location of the first opening 41. The first opening 41 is etched sequentially through the additional film layer 40, the second electrode layer 33, and the piezoelectric layer 32 using dry etching or wet etching, exposing a portion of the first electrode layer 31. The exposed first metal pad 60 is then deposited on the first electrode layer 31 to form an electrical connection.
[0056] The second opening 42 penetrates the additional film layer 40 and the stress adjustment layer 50. A second metal pad 70 is stacked on the second electrode layer 33 located at the second opening 42 for electrical connection with the second electrode layer 33. In one feasible embodiment, a patterned hard mask is fabricated on the portion of the additional film layer 40 other than the location of the second opening 42. The second opening 42 is etched into the additional film layer 40 and the stress adjustment layer 50 by dry etching or wet etching, exposing a portion of the second electrode layer 33. The exposed second metal pad 70 is then deposited on the second electrode layer 33 to form an electrical connection.
[0057] Regarding the aforementioned piezoelectric loudspeaker, the present invention also provides a preferred manufacturing method, which includes the following steps:
[0058] S101: Provide a substrate 10, specifically, provide a first silicon layer 12, and prepare a first oxide layer 13 of SiO2 material on the first silicon layer 12 of silicon material by means of thermal oxidation, vapor deposition or CVD.
[0059] S102: A second silicon layer 21 is formed on the first oxide layer 13 using methods such as bonding a silicon wafer or CVD. The material of the second silicon layer 21 can be the same as that of the first silicon layer 12, and a second oxide layer 22 is formed on the second silicon layer 21. Specifically, a second oxide layer 22 is sputtered onto the surface of the second silicon layer 21 by thermal oxidation.
[0060] S103: A first electrode layer 31, a piezoelectric layer 32, and a second electrode layer 33 are sequentially deposited on top of the second oxide layer 22 along the vibration direction of the piezoelectric speaker. The first electrode layer 31 is formed on the second oxide layer 22 by electron beam vapor deposition or magnetron sputtering, and patterned using photolithography. The first electrode layer 31 is connected to the bottom electrode pad via a bottom electrode lead. The piezoelectric layer 32 leaves a portion that forms the first opening 41 and is deposited on the first electrode layer 31. The second electrode layer 33 leaves a portion that forms the first opening 41 and is formed on the piezoelectric layer 32 by electron beam vapor deposition or magnetron sputtering, and patterned using photolithography. The second electrode layer 33 is connected to the top electrode pad via a top electrode lead.
[0061] S104: A second slit 34 is formed by etching on the second electrode layer 33. The second slit 34 passes through the first electrode layer 31, the piezoelectric layer 32 and the second electrode layer 33 in sequence. Specifically, the second slit 34 is formed by etching on the second electrode layer 33 by dry etching or wet etching.
[0062] S105: A stress-adjusting layer 50 is formed at a given location on the second electrode layer 33. The stress-adjusting layer 50 is formed on the surface of the second electrode layer 33, the inner wall of the second slit 34, and the side wall of the first opening 41.
[0063] S106: An additional film layer 40 is formed on the stress-adjusting layer 50. When epoxy resin is used for the additional film layer 40, it is formed by spin coating or roll forming and patterned by photolithography. When silicone rubber is used for the additional film layer 40, it is formed by spin coating or roll forming and patterned by peeling. Part of the additional film layer 40 fills the second slit 34, while the first slit 23 is not filled with the additional film layer 40.
[0064] S107: Etch the additional film layer 40 and the stress-adjusting layer 50 to allow the first opening 41 and the second opening 42 to penetrate, thereby exposing the first electrode layer 31 and the second electrode layer 33. Dry etching or wet etching is preferred.
[0065] S108: A first metal pad 60 is formed by depositing metal on the first electrode layer 31 exposed from the first opening 41, and a second metal pad 70 is formed by depositing metal on the second electrode layer 33 exposed from the second opening 42. Specifically, the first metal pad 60 is formed by depositing metal on the first electrode layer 31 by electron beam vapor deposition or magnetron sputtering to form an electrical connection, and the second metal pad 70 is formed by depositing metal on the second electrode layer 33 by electron beam vapor deposition or magnetron sputtering to form an electrical connection.
[0066] S109: A back cavity 11 is formed by etching at the bottom of the first silicon layer 12. The back cavity 11 sequentially penetrates the first silicon layer 12 and the first oxide layer 13. The second silicon layer 21 is exposed through the back cavity 11. The bottom of the second silicon layer 21 is then etched to form a second slit 34. The second slit 34 sequentially penetrates the second silicon layer 21 and the second oxide layer 22.
[0067] The piezoelectric loudspeaker prepared by the above method has a piezoelectric unit 30 and an additional film layer 40, and a stress adjustment layer 50 is provided as needed, so that the additional film layer 40 and the piezoelectric unit 30 are initially bent downwards. In addition, as long as the additional film layer 40 can be formed to initially bulge downwards by adjusting the additional film layer 40, the stress adjustment layer 50 may not be provided.
[0068] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.
Claims
1. A piezoelectric loudspeaker, characterized in that, include: Substrate, wherein a back cavity is provided through the substrate; A support unit is disposed on the substrate and covers the back cavity. A first slit is provided through a portion of the support unit to divide the support unit into a first support portion and a second support portion. The second support portion is located on the outer periphery of the first support portion and along the vibration direction of the piezoelectric loudspeaker. The first support portion protrudes further into the back cavity than the second support portion. A piezoelectric unit is disposed on the support unit. A second slit is provided through a portion of the piezoelectric unit to divide the piezoelectric unit into a first piezoelectric part and a second piezoelectric part. The second piezoelectric part is located on the outer periphery of the first piezoelectric part. The first piezoelectric part is supported on the first support unit, and the second piezoelectric part is supported on the second support unit. Along the vibration direction of the piezoelectric speaker, the first piezoelectric part protrudes further towards the back cavity than the second piezoelectric part. An additional film layer is disposed on the piezoelectric unit and is also formed at a position corresponding to the second slit.
2. The piezoelectric loudspeaker according to claim 1, characterized in that, A stress-adjusting layer is provided between the piezoelectric unit and the additional film layer, and the stress-adjusting layer covers the surfaces of the first piezoelectric part and the second piezoelectric part.
3. The piezoelectric loudspeaker according to claim 1, characterized in that, Part of the additional membrane layer is filled within the second slit.
4. The piezoelectric loudspeaker according to claim 3, characterized in that, The additional membrane layer was not filled in the first slit.
5. The piezoelectric loudspeaker according to claim 1, characterized in that, The second support portion includes a plurality of sub-support portions arranged around the first support portion and spaced apart from each other by a first partition groove; the second piezoelectric portion includes a plurality of sub-piezoelectric portions arranged around the first piezoelectric portion and spaced apart from each other by a second partition groove; the sub-piezoelectric portions are arranged in a one-to-one correspondence with the sub-support portions; the first slit is connected to the second slit; the additional film layer only covers the gaps between the plurality of sub-piezoelectric portions and the second slit.
6. The piezoelectric loudspeaker according to claim 5, characterized in that, The plurality of sub-supports are connected to the first support via a first elastic beam, which is disposed in the first slit; the plurality of sub-piezoelectric parts are connected to the first piezoelectric part via a second elastic beam, which is disposed in the second slit.
7. The piezoelectric loudspeaker according to any one of claims 1 to 6, characterized in that, The Young's modulus of the additional membrane layer is less than or equal to 2 GPa.
8. The piezoelectric loudspeaker according to claim 7, characterized in that, The additional membrane layer is an elastomer.