WO2024065905A1 - Mems 压电扬声器 - Google Patents
Mems 压电扬声器 Download PDFInfo
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- WO2024065905A1 WO2024065905A1 PCT/CN2022/126561 CN2022126561W WO2024065905A1 WO 2024065905 A1 WO2024065905 A1 WO 2024065905A1 CN 2022126561 W CN2022126561 W CN 2022126561W WO 2024065905 A1 WO2024065905 A1 WO 2024065905A1
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- piezoelectric
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- 239000000758 substrate Substances 0.000 claims abstract description 22
- 239000002131 composite material Substances 0.000 claims abstract description 16
- 230000002093 peripheral effect Effects 0.000 claims description 6
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 5
- 239000004642 Polyimide Substances 0.000 claims description 4
- 229920001721 polyimide Polymers 0.000 claims description 4
- 239000002861 polymer material Substances 0.000 claims description 4
- 229920001486 SU-8 photoresist Polymers 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 3
- 229920000642 polymer Polymers 0.000 claims description 3
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 2
- 239000011787 zinc oxide Substances 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 98
- 230000006870 function Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000009471 action Effects 0.000 description 4
- 239000002346 layers by function Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- 101001121408 Homo sapiens L-amino-acid oxidase Proteins 0.000 description 1
- 102100026388 L-amino-acid oxidase Human genes 0.000 description 1
- 101100012902 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) FIG2 gene Proteins 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
Definitions
- the invention belongs to the field of acoustic and electrical technology, and in particular relates to a MEMS piezoelectric speaker.
- MEMS piezoelectric speakers are one of the main components of mobile terminals such as mobile phones and tablets. They are mainly used to convert electrical signals into sound signals and are the key to realizing human-computer interaction interfaces. Especially with the emergence of TWS headphones, the demand for miniaturized and high-performance speakers is becoming increasingly urgent. MEMS piezoelectric speakers have become the main components combined with traditional speakers to carry high-frequency vibrations due to their miniaturization, light weight and low power consumption.
- the existing MEMS piezoelectric speaker mainly includes a substrate, a structural layer fixed on the substrate and a piezoelectric functional layer placed on the structural layer.
- the piezoelectric functional layer includes a piezoelectric layer and an electrode layer arranged on opposite sides of the piezoelectric layer. Its working principle is that the piezoelectric functional layer will deform after being energized, thereby driving the overall structure to vibrate and make sound.
- the higher-order high-frequency resonant frequency will also move to a low frequency, resulting in high-order high resonant frequencies appearing within the human hearing range (20Hz ⁇ 20kHz), which will not only reduce the sound pressure level, but also increase the harmonic distortion, affecting the listening experience.
- the technical problem to be solved by the present invention is how to provide a MEMS piezoelectric speaker to solve the problem that the existing MEMS piezoelectric speakers have poor performance of harmonic distortion and sound pressure level due to their structural design.
- the present invention is implemented by providing a MEMS piezoelectric speaker, comprising:
- a vibration structure comprising a structural layer, a piezoelectric composite layer and a flexible layer stacked in sequence on the substrate;
- the structural layer comprises a structural plate, a structural fixing part surrounding the structural plate and spaced apart from the structural plate, and a plurality of structural springs connecting the structural plate and the structural fixing part and having slits; the structural fixing part is supported and fixed to the base, and the positive projections of the structural springs and the structural plate to the base are completely located within the range of the cavity;
- the piezoelectric composite layer includes a piezoelectric film, a first electrode layer formed on a side of the piezoelectric film close to the structural layer, and a second electrode layer formed on a side of the piezoelectric film away from the structural layer; wherein the overlapping areas of the piezoelectric film, the first electrode layer, and the second electrode layer in their respective orthographic projections onto the substrate serve as piezoelectric driving functional areas, and the flexible layer is spaced apart from the structural layer in the stacking direction of the layers of the vibration structure, and its orthographic projection completely covers the slits of the plurality of structural springs.
- the first electrode layer includes a first electrode functional portion fixed to the structural plate, a first electrode fixing portion fixed to the structural fixing portion, and a first electrode spring connecting the first electrode functional portion and the first electrode fixing portion.
- the flexible layer covers the side of the second electrode layer away from the piezoelectric film and at least partially extends to the peripheral sides of the second electrode layer and the piezoelectric film and is fixed to the surface of the first electrode layer away from the structural layer.
- the piezoelectric film includes a piezoelectric functional portion fixed to the first electrode functional portion, a piezoelectric fixed portion fixed to the first electrode fixed portion, and a piezoelectric spring connecting the piezoelectric functional portion and the piezoelectric fixed portion.
- the piezoelectric film, the first electrode layer and the structural layer have the same shape and structure.
- the flexible layer covers the side of the second electrode layer away from the piezoelectric film and at least partially extends to the peripheral side of the second electrode layer and is fixed to the surface of the piezoelectric film away from the structural layer.
- the structural spring is any one of a U-shaped structure, a ring structure and an S-shaped structure.
- the piezoelectric film is made of any one of aluminum nitride, piezoelectric ceramics and zinc oxide.
- the flexible layer is made of polymer material.
- the polymer is SU-8 photoresist or polyimide.
- the structural plate of the structural layer in the MEMS piezoelectric speaker of the present invention is connected to the structural fixing part through a plurality of structural springs, and the overlapping areas of the piezoelectric film, the first electrode layer and the second electrode layer in the piezoelectric composite layer in their orthographic projections onto the substrate are used as piezoelectric driving functional areas.
- the stress of the piezoelectric composite layer can be released by the elastic action of the structural springs, while ensuring the stiffness of the overall structure without making the stiffness of the overall structure too low, thereby improving the sound pressure level of the MEMS piezoelectric speaker and reducing harmonic distortion, so as to improve the performance of the MEMS piezoelectric speaker.
- FIG1 is a schematic diagram of the structural decomposition of a first MEMS piezoelectric speaker provided by an embodiment of the present invention
- FIG2 is a schematic diagram of the overall structure of a first MEMS piezoelectric speaker provided by an embodiment of the present invention.
- Fig. 3 is a cross-sectional view of line A-A in Fig. 2;
- FIG. 4 is a schematic diagram of the structural decomposition of a second MEMS piezoelectric speaker provided by an embodiment of the present invention.
- FIG. 5 is a schematic diagram of the overall structure of a second MEMS piezoelectric speaker provided by an embodiment of the present invention.
- Fig. 6 is a cross-sectional view of line B-B in Fig. 5;
- FIG7 is a schematic structural diagram of a second structural layer provided in an embodiment of the present invention.
- FIG8 is a schematic structural diagram of a third structural layer provided in an embodiment of the present invention.
- 100 MEMS piezoelectric speaker; 1, substrate; 11, cavity; 2, vibration structure; 21, structural layer; 211, structural plate; 212, structural spring; 213, structural fixing part; 22, piezoelectric composite layer; 221, piezoelectric film; 2211, piezoelectric functional part; 2212, piezoelectric fixing part; 2213, piezoelectric spring; 222, first electrode layer; 2221, first electrode functional part; 2222, first electrode fixing part; 2223, first electrode spring; 223, second electrode layer; 2231, second electrode functional part; 2232, lead; 2233, connecting part; 23, flexible layer; 10, slit.
- An embodiment of the present invention provides a MEMS piezoelectric speaker 100 , which includes a substrate 1 and a vibration structure 2 , as shown in FIGS. 1 to 8 .
- the substrate 1 has a cavity 11 ;
- the vibration structure 2 includes a structural layer 21 , a piezoelectric composite layer 22 and a flexible layer 23 which are sequentially stacked on the substrate 1 .
- the structural layer 21 includes a structural plate 211, a structural fixing portion 213 surrounding the structural plate 211 and spaced apart from the structural plate, and a plurality of structural springs 212 connecting the structural plate 211 and the structural fixing portion 213 and having slits 10; the structural fixing portion 213 is supported and fixed to the base 1, and the positive projections of the structural springs 212 and the structural plate 211 onto the base 1 are completely within the range of the cavity 11.
- each structural spring 212 is connected to the structural plate 211, and the other end is connected to the structural fixing part 213;
- the structural spring 212 is any one of a variety of structures such as a U-shaped structure, a ring structure, and an S-shaped structure.
- Such a setting can strengthen the rigidity of the overall structure through the elastic action of the structural fixing part 213 and the structural spring 212, while not making its rigidity too low, thereby improving the sound pressure level of the MEMS piezoelectric speaker and reducing harmonic distortion, so as to improve the performance of the MEMS piezoelectric speaker.
- the piezoelectric composite layer 22 includes a piezoelectric film 221, a first electrode layer 222 formed on the side of the piezoelectric film 221 close to the structural layer 21, and a second electrode layer 223 formed on the side of the piezoelectric film 221 away from the structural layer 21; wherein, the overlapping areas of the piezoelectric film 221, the first electrode layer 222, and the second electrode layer 223 in their respective orthographic projections onto the substrate 1 serve as piezoelectric driving functional areas, and the flexible layer 23 is spaced apart from the structural layer 21 in the stacking direction of the layers of the vibration structure 2, and its orthographic projection completely covers the slits 10 of the multiple structural springs 212.
- the flexible layer 23 is spaced apart from the structural layer 21 in the stacking direction of the layers of the vibration structure 2 and its orthographic projection completely covers the slits 10 between the plurality of structural springs 212 , so that air can be prevented from leaking outward from the slits 10 .
- the piezoelectric film 221 is made of any one of piezoelectric materials including aluminum nitride (AlN), piezoelectric ceramics (PZT) and zinc oxide (ZnO). Of course, it can also be made of other materials according to actual needs, which will not be illustrated here one by one.
- the flexible layer 23 is made of a polymer material, and the polymer is SU-8 photoresist or polyimide (PI).
- the flexible layer 23 can also be made of other polymer materials, which will not be illustrated one by one here.
- the first electrode layer 222 includes a first electrode function portion 2221 fixed to the structure plate 211 , a first electrode fixing portion 2222 fixed to the structure fixing portion 213 , and a first electrode spring 2223 connecting the first electrode function portion 2221 and the first electrode fixing portion 2222 .
- the end surface of the substrate 1 is a portion of one end of the substrate 1 surrounding the cavity 11 , and is also equivalent to a plane area of one end of the substrate 1 .
- first electrode springs 2223 there are multiple first electrode springs 2223 and they are arranged around the first electrode functional portion 2221, and two adjacent ones are arranged at intervals.
- the first electrode layer 222 may not be provided with the first electrode fixing portion 2222 and the first electrode spring 2223, or the first electrode fixing portion 2222 may be provided as a point portion, and the first electrode spring 2223 may be provided as one.
- the piezoelectric film 221 includes a piezoelectric functional portion 2211 fixed to the first electrode functional portion 2221, a piezoelectric fixing portion 2212 fixed to the first electrode fixing portion 2221, and a piezoelectric spring 2213 connecting the piezoelectric functional portion 2211 and the piezoelectric fixing portion 2212.
- This arrangement can enhance the rigidity of the overall structure through the elastic action of the piezoelectric fixing portion 2212 and the piezoelectric spring 2213, while not making the rigidity too low, thereby improving the sound pressure level of the MEMS piezoelectric speaker and reducing harmonic distortion, so as to improve the performance of the MEMS piezoelectric speaker.
- the piezoelectric film 221 may also be provided with only the piezoelectric functional portion 2211, without the piezoelectric fixing portion 2212 and the piezoelectric spring 2213.
- the rigidity of the overall structure can be further reduced, so as to adjust the first resonant frequency of the MEMS piezoelectric speaker 100 within a certain range, thereby expanding the available audio frequency range.
- the piezoelectric fixing portion 2212 may be a ring structure, and the corresponding piezoelectric spring 2213 may be multiple and arranged around the piezoelectric fixing portion 2212.
- the structure of the piezoelectric film 221 is similar to or the same as the structural layer 21.
- the piezoelectric fixing portion 2212 may also be a point portion, and the piezoelectric spring 2213 may also be one and the structure is similar to or the same as the structure spring 212.
- the piezoelectric film 221 , the first electrode layer 222 and the structural layer 21 have the same shape and structure.
- the second electrode layer 223 includes a second electrode function portion 2231 fixed to a side of the piezoelectric function portion 2211 away from the first electrode function portion 2221, a lead 2233 extending outward from the periphery of the second electrode function portion 2231, and a connection portion 2233 formed by an end of the lead 2233 away from the second electrode function portion 2231. In this way, it is convenient to introduce an electrical signal into the second electrode layer 223.
- the second electrode fixing portion 2231 has the same shape and structure as the first electrode functional portion 2221 .
- the flexible layer 23 covers the side of the second electrode layer 223 away from the piezoelectric film 221 and at least partially extends to the peripheral side of the second electrode layer 223 and is fixed to the surface of the piezoelectric film 221 away from the structural layer 21 .
- the flexible layer 23 covers the side of the second electrode layer 223 away from the piezoelectric film 221 and at least partially extends to the peripheral side of the second electrode layer 223 and the piezoelectric film 221 and is fixed to the surface of the first electrode layer 222 away from the structural layer 21 .
- the structural plate 211 of the structural layer 21 in the MEMS piezoelectric speaker 100 of this embodiment is connected to the structural fixing part 213 through a plurality of structural springs 212, and the overlapping areas of the piezoelectric film 221, the first electrode layer 222 and the second electrode layer 223 in the piezoelectric composite layer 22 in the orthographic projection to the substrate 1 are used as the piezoelectric driving functional area, so that the stress of the piezoelectric composite layer 22 can be released by the elastic action of the structural spring 212, while ensuring the stiffness of the overall structure without making the stiffness of the overall structure too low, thereby improving the sound pressure level of the MEMS piezoelectric speaker and reducing harmonic distortion, so as to improve the performance of the MEMS piezoelectric speaker.
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- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Piezo-Electric Transducers For Audible Bands (AREA)
Abstract
本发明提供了一种MEMS压电扬声器，其包括：基底，具有空腔；振动结构，包括结构层、压电复合层以及柔性层；结构层包括结构板、结构固定部以及具有狭缝的多个结构弹簧；压电复合层包括压电薄膜以及第一电极层和第二电极层；其中，压电薄膜、第一电极层以及第二电极层分别向基底的正投影中相互重合的区域作为压电驱动功能区，柔性层在振动结构的各层的叠设方向上与结构层间隔设置且其正投影完全覆盖多个结构弹簧的狭缝。本发明通过结构弹簧的弹性作用可以释放压电复合层的应力，同时保证整体结构的刚度且不会使整体结构的刚度过低，从而提升MEMS压电扬声器声压级且减少谐波失真，以提升MEMS压电扬声器的性能。
Description
本发明属于声电技术领域，尤其涉及一种MEMS压电扬声器。
MEMS压电扬声器作为手机及平板电脑等移动终端的主要元器件之一，其主要是用于将电信号转换成声音信号，是实现人机交互接口的关键。尤其是TWS耳机的出现，小型化及高性能的扬声器需求日渐迫切，MEMS压电扬声器因其小型化、轻量化及低功耗等特点，成为了与传统扬声器组合并承载高频段振动的主要元器件。
现有的MEMS压电扬声器主要包括基底、固定在基底上的结构层及置于结构层上的压电功能层，压电功能层包括压电层和设置于压电层相对两侧的电极层，其工作原理是压电功能层通电后会产生形变，从而带动整体结构振动发声。
现有的MEMS压电扬声器主要有两种结构：一种是直接将整块结构层和压电功能层依次叠设于基底上，这种方式由于工艺及各层结构的应力限制，会导致较大的谐波失真（THD），且声压级（SPL）的提升能力也有限；另一种是将压电供能层的中部驱动区直接设置于与基底连接的柔性膜上，这种方式会降低导致整个器件的刚度，使扬声器的一阶谐振频率向低频处移动，相应的，更高阶的高频谐振频率也会向低频处移动，从而导致高阶的高谐振频率出现在人耳听觉范围（20Hz~20kHz）范围内，不光使声压级降低，还会使谐波失真增大，影响听感。
本发明要解决的技术问题是如何提供一种MEMS压电扬声器，以解决现有MEMS压电扬声器由于其结构设计而存在谐波失真及声压级的性能较差的问题。
本发明是这样实现的，提供了一种MEMS压电扬声器，包括：
基底，所述基底具有空腔；
振动结构，所述振动结构包括依次叠设于所述基底上方的结构层、压电复合层以及柔性层；
所述结构层包括结构板、环绕所述结构板且与所述结构板间隔的结构固定部以及连接所述结构板和所述结构固定部且具有狭缝的多个结构弹簧；所述结构固定部支撑固定于所述基底，所述结构弹簧及所述结构板向所述基底的正投影完全位于所述空腔的范围内；
所述压电复合层包括压电薄膜以及形成于所述压电薄膜靠近所述结构层一侧的第一电极层和形成于所述压电薄膜远离所述结构层一侧的第二电极层；其中，所述压电薄膜、所述第一电极层以及所述第二电极层分别向所述基底的正投影中相互重合的区域作为压电驱动功能区，所述柔性层在所述振动结构的各层的叠设方向上与所述结构层间隔设置且其正投影完全覆盖多个所述结构弹簧的所述狭缝。
更进一步地，所述第一电极层包固定于所述结构板的第一电极功能部、固定于所述结构固定部的第一电极固定部以及连接所述第一电极功能部和所述第一电极固定部的第一电极弹簧。
更进一步地，所述柔性层覆盖所述第二电极层远离所述压电薄膜的一侧且至少部分延伸至所述第二电极层和所述压电薄膜的周侧并固定于所述第一电极层远离所述结构层一侧的表面。
更进一步地，所述压电薄膜包括固定于所述第一电极功能部的压电功能部、固定于所述第一电极固定部的压电固定部以及连接所述压电功能部和所述压电固定部的压电弹簧。
更进一步地，所述压电薄膜、所述第一电极层和所述结构层的形状结构均相同。
更进一步地，所述柔性层覆盖所述第二电极层远离所述压电薄膜的一侧且至少部分延伸至所述第二电极层的周侧并固定于所述压电薄膜远离所述结构层一侧的表面。
更进一步地，所述结构弹簧为U形结构、环形结构以及S形结构中的任意一种结构。
更进一步地，所述压电薄膜由氮化铝、压电陶瓷以及氧化锌中的任意一种材料制成。
更进一步地，所述柔性层由高聚物材料制成。
更进一步地，所述高聚物为SU-8光刻胶或聚酰亚胺。
与现有技术相比，本发明的MEMS压电扬声器中结构层的结构板通过多个结构弹簧与结构固定部连接，同时将压电复合层中压电薄膜、第一电极层以及第二电极层分别向基底的正投影中相互重合的区域作为压电驱动功能区，这样便可以通过结构弹簧的弹性作用释放压电复合层的应力，同时保证整体结构的刚度且不会使整体结构的刚度过低，从而提升MEMS压电扬声器声压级且减少谐波失真，以提升MEMS压电扬声器的性能。
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明实施例提供的第一种MEMS压电扬声器的结构结构分解示意图；
图2是本发明实施例提供的第一种MEMS压电扬声器的整体结构示意图；
图3是图2中A-A线的剖视图；
图4是本发明实施例提供的第二种MEMS压电扬声器的结构结构分解示意图；
图5是本发明实施例提供的第二种MEMS压电扬声器的整体结构示意图；
图6是图5中B-B线的剖视图；
图7是本发明实施例提供的第二种结构层的结构示意图；
图8是本发明实施例提供的第三种结构层的结构示意图；
其中：100、MEMS压电扬声器；1、基底；11、空腔；2、振动结构；21、结构层；211、结构板；212、结构弹簧；213、结构固定部；22、压电复合层；221、压电薄膜；2211、压电功能部；2212、压电固定部；2213、压电弹簧；222、第一电极层；2221、第一电极功能部；2222、第一电极固定部；2223、第一电极弹簧；223、第二电极层；2231、第二电极功能部；2232、引线；2233、连接部；23、柔性层；10、狭缝。
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
本发明实施例提供了一种MEMS压电扬声器100，结合图1至图8所示，其包括基底1以及振动结构2。
具体地，基底1具有空腔11；振动结构2包括依次叠设于基底1上方的结构层21、压电复合层22以及柔性层23。
具体地，结构层21包括结构板211、环绕结构板211且与结构板间隔的结构固定部213以及连接结构板211和结构固定部213且具有狭缝10的多个结构弹簧212；结构固定部213支撑固定于基底1，结构弹簧212及结构板211向基底1的正投影完全位于空腔11的范围内。
其中，每个结构弹簧212的一端与结构板211连接，另一端则与结构固定部213连接；结构弹簧212为U形结构、环形结构以及S形结构等多种结构中的任意一种结构。这样设置可以通过结构固定部213和结构弹簧212的弹性作用加强整体结构的刚度，同时不会使其刚度过低，从而提升MEMS压电扬声器声压级且减少谐波失真，以提升MEMS压电扬声器的性能。
具体地，压电复合层22包括压电薄膜221以及形成于压电薄膜221靠近结构层21一侧的第一电极层222和形成于压电薄膜221远离结构层21一侧的第二电极层223；其中，压电薄膜221、第一电极层222以及第二电极层223分别向基底1的正投影中相互重合的区域作为压电驱动功能区，柔性层23在振动结构2的各层的叠设方向上与结构层21间隔设置且其正投影完全覆盖多个结构弹簧212的狭缝10。
其中，柔性层23在振动结构2的各层的叠设方向上与结构层21间隔设置且其正投影完全覆盖多个结构弹簧212之间的狭缝10，这样设置可以避免空气由狭缝10向外泄露。
本实施例中，压电薄膜221由氮化铝（AlN）、压电陶瓷（PZT）以及氧化锌（ZnO）中的任意一种压电材料制成，当然，根据实际需求，其还可以由其它的材料制成，在此不一一举例说明。
本实施例中，柔性层23由高聚物材料制成，高聚物为SU-8光刻胶或聚酰亚胺（PI）。当然，根据实际需求，柔性层23还可以由其它的高聚物材料制成，在此不一一举例说明。
具体地，第一电极层222包括固定于结构板211的第一电极功能部2221、固定于结构固定部213的第一电极固定部2222以及连接第一电极功能部2221和第一电极固定部2222的第一电极弹簧2223。
其中，基底1的端面为基底1的一端中环绕空腔11的部分，也相当于基底1一端的平面区域。
本实施例中，第一电极弹簧2223为多个且环绕第一电极功能部2221布置，相邻的两个还间隔设置。当然，根据实际需求，第一电极层222也可以不设置第一电极固定部2222和第一电极弹簧2223，或者将第一电极固定部2222设置为一个点部，将第一电极弹簧2223设置为一个。
具体地，压电薄膜221包括固定于第一电极功能部2221的压电功能部2211、固定于第一电极固定部2221的压电固定部2212以及连接压电功能部2211和压电固定部2212的压电弹簧2213。这样设置可以通过压电固定部2212和压电弹簧2213的弹性作用加强整体结构的刚度，同时不会使其刚度过低，从而提升MEMS压电扬声器声压级且减少谐波失真，以提升MEMS压电扬声器的性能。
当然，根据实际需求，压电薄膜221也可以只设置压电功能部2211，不设置压电固定部2212和压电弹簧2213。这样由于其除了压电驱动功能区的其它位置并不设置其它结构，从而可以进一步降低整体结构的刚度，以在一定范围内调节MEMS压电扬声器100的第一谐振频率，使可用的音频频率范围扩大。
其中，压电固定部2212可以为环形结构，相应的压电弹簧2213可以为多个且环绕压电固定部2212布置，此时，压电薄膜221的结构则与结构层21类似或相同。当然，根据实际需求，压电固定部2212还可以为一个点部，而压电弹簧2213还可以为一个且与结构弹簧212的结构类似或相同。
本实施例中，压电薄膜221、第一电极层222和结构层21的形状结构均相同。
具体地，第二电极层223包括固定于压电功能部2211远离第一电极功能部2221的一侧的第二电极功能部2231、由第二电极功能部2231的周缘向外引出的引线2233以及由引线2233远离第二电极功能部2231的一端形成的连接部2233。这样可以方便为第二电极层223引入电信号。
本实施例中，第二电极固定部2231与第一电极功能部2221的形状结构相同。
本实施例中，如图3所示，柔性层23覆盖第二电极层223远离压电薄膜221的一侧且至少部分延伸至第二电极层223的周侧并固定于压电薄膜221远离结构层21一侧的表面。
在另一实施例中，如图6所示，柔性层23覆盖第二电极层223远离压电薄膜221的一侧且至少部分延伸至第二电极层223和压电薄膜221的周侧并固定于第一电极层222远离结构层21一侧的表面。
具体地，结构层21还可以包括多个依次叠设的层数，如二层、三层、四层等；压电复合层22也可以包括多个依次叠设的层数，如两层、三层、五层等。
与现有技术相比，本实施例的MEMS压电扬声器100中结构层21的结构板211通过多个结构弹簧212与结构固定部213连接，同时将压电复合层22中压电薄膜221、第一电极层222以及第二电极层223分别向基底1的正投影中相互重合的区域作为压电驱动功能区，这样便可以通过结构弹簧212的弹性作用释放压电复合层22的应力，同时保证整体结构的刚度且不会使整体结构的刚度过低，从而提升MEMS压电扬声器声压级且减少谐波失真，以提升MEMS压电扬声器的性能。即可以得到更大的升压级，更宽频率范围下的可用音频；释放压电复合层22的应力，降低应力对谐波失真的影响以及器件的功耗；同时不会有过多的高阶谐振频率出现在可听频率范围内，还降低过小刚度带来的谐波失真增大。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。
Claims (10)
- 一种MEMS压电扬声器，其特征在于，包括：基底，所述基底具有空腔；振动结构，所述振动结构包括依次叠设于所述基底上方的结构层、压电复合层以及柔性层；所述结构层包括结构板、环绕所述结构板且与所述结构板间隔的结构固定部以及连接所述结构板和所述结构固定部且具有狭缝的多个结构弹簧；所述结构固定部支撑固定于所述基底，所述结构弹簧及所述结构板向所述基底的正投影完全位于所述空腔的范围内；所述压电复合层包括压电薄膜以及形成于所述压电薄膜靠近所述结构层一侧的第一电极层和形成于所述压电薄膜远离所述结构层一侧的第二电极层；其中，所述压电薄膜、所述第一电极层以及所述第二电极层分别向所述基底的正投影中相互重合的区域作为压电驱动功能区，所述柔性层在所述振动结构的各层的叠设方向上与所述结构层间隔设置且其正投影完全覆盖多个所述结构弹簧的所述狭缝。
- 如权利要求1所述的MEMS压电扬声器，其特征在于，所述第一电极层包括固定于所述结构板的第一电极功能部、固定于所述结构固定部的第一电极固定部以及连接所述第一电极功能部和所述第一电极固定部的第一电极弹簧。
- 如权利要求2所述的MEMS压电扬声器，其特征在于，所述柔性层覆盖所述第二电极层远离所述压电薄膜的一侧且至少部分延伸至所述第二电极层和所述压电薄膜的周侧并固定于所述第一电极层远离所述结构层一侧的表面。
- 如权利要求2所述的MEMS压电扬声器，其特征在于，所述压电薄膜包括固定于所述第一电极功能部的压电功能部、固定于所述第一电极固定部的压电固定部以及连接所述压电功能部和所述压电固定部的压电弹簧。
- 如权利要求3或4所述的MEMS压电扬声器，其特征在于，所述压电薄膜、所述第一电极层和所述结构层的形状结构均相同。
- 如权利要求4所述的MEMS压电扬声器，其特征在于，所述柔性层覆盖所述第二电极层远离所述压电薄膜的一侧且至少部分延伸至所述第二电极层的周侧并固定于所述压电薄膜远离所述结构层一侧的表面。
- 如权利要求1所述的MEMS压电扬声器，其特征在于，所述结构弹簧为U形结构、环形结构以及S形结构中的任意一种结构。
- 如权利要求1所述的MEMS压电扬声器，其特征在于，所述压电薄膜由氮化铝、压电陶瓷以及氧化锌中的任意一种材料制成。
- 如权利要求1所述的MEMS压电扬声器，其特征在于，所述柔性层由高聚物材料制成。
- 如权利要求9所述的MEMS压电扬声器，其特征在于，所述高聚物为SU-8光刻胶或聚酰亚胺。
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| CN110052391A (zh) * | 2019-05-28 | 2019-07-26 | 浙江大学 | 双谐振模式耦合的微机械压电超声波换能器 |
| CN111147998A (zh) * | 2020-04-08 | 2020-05-12 | 共达电声股份有限公司 | Mems微型扬声器、mems微型扬声器的制备方法及电子设备 |
| CN111182430A (zh) * | 2019-12-17 | 2020-05-19 | 安徽奥飞声学科技有限公司 | 一种mems结构 |
| CN211656372U (zh) * | 2019-12-31 | 2020-10-09 | 瑞声声学科技(深圳)有限公司 | 一种mems扬声器 |
| US20210204067A1 (en) * | 2019-12-27 | 2021-07-01 | xMEMS Labs, Inc. | Sound producing device |
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| CN110052391A (zh) * | 2019-05-28 | 2019-07-26 | 浙江大学 | 双谐振模式耦合的微机械压电超声波换能器 |
| CN111182430A (zh) * | 2019-12-17 | 2020-05-19 | 安徽奥飞声学科技有限公司 | 一种mems结构 |
| US20210204067A1 (en) * | 2019-12-27 | 2021-07-01 | xMEMS Labs, Inc. | Sound producing device |
| CN211656372U (zh) * | 2019-12-31 | 2020-10-09 | 瑞声声学科技(深圳)有限公司 | 一种mems扬声器 |
| CN111147998A (zh) * | 2020-04-08 | 2020-05-12 | 共达电声股份有限公司 | Mems微型扬声器、mems微型扬声器的制备方法及电子设备 |
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