WO2022227383A1 - 一种利用液压传动放大振幅的发声方法和结构 - Google Patents

一种利用液压传动放大振幅的发声方法和结构 Download PDF

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WO2022227383A1
WO2022227383A1 PCT/CN2021/119668 CN2021119668W WO2022227383A1 WO 2022227383 A1 WO2022227383 A1 WO 2022227383A1 CN 2021119668 W CN2021119668 W CN 2021119668W WO 2022227383 A1 WO2022227383 A1 WO 2022227383A1
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sound
mems
amplitude
diaphragm
hydraulic chamber
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PCT/CN2021/119668
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English (en)
French (fr)
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张百良
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广州博良电子有限公司
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Publication of WO2022227383A1 publication Critical patent/WO2022227383A1/zh

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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
    • H04R19/00—Electrostatic transducers
    • H04R19/02—Loudspeakers
    • 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

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  • the present application relates to the field of acoustics, in particular to sound generators with very small amplitudes.
  • FIG. 1 is a schematic diagram of a prior art MEMS speaker.
  • the sound design of the traditional moving iron speaker is basically similar, the drive shaft connector 11 is the connector of the MEMS sound diaphragm 14 and the diaphragm 15; the MEMS driver 14 is connected by the connector 11 (cylinder or Usound H type).
  • the amplitude of the vibration is transmitted to a diaphragm 15, which drives the diaphragm to vibrate and produce sound.
  • the area of the diaphragm is much larger than that of the MEMS, which amplifies the output sound power.
  • the small amplitude of the MEMS the sound pressure is still very limited.
  • the present application provides a micro speaker in a first aspect.
  • the micro-speaker comprises: a MEMS sound film for generating small amplitude; a hydraulic transmission mechanism for amplifying the small amplitude of the MEMS sound film by means of liquid transmission; and a diaphragm for converting the amplified amplitude into sound waves.
  • the hydraulic transmission mechanism includes: a hydraulic chamber, the hydraulic chamber is filled with liquid; a shaft sleeve is opened in the hydraulic chamber and is opposite to the MEMS sound diaphragm; a drive shaft connector, a shaft connector and a shaft The sleeve is sealed and slipped; wherein, the cross-sectional area of the drive shaft connector is smaller than the cross-sectional area of the sound membrane of the sound generator.
  • the embodiments of the present application provide a sound-emitting structure.
  • the sound-generating structure includes: a sound-generating unit for generating a small amplitude; a hydraulic transmission mechanism for amplifying the small amplitude of the MEMS sound membrane by means of liquid transmission; and a vibrating membrane for converting the amplified amplitude into sound waves.
  • the sound-generating structure is a MEMS speaker, a conventional speaker, an underwater sound-generating mechanism or an underwater sonar.
  • the hydraulic transmission mechanism includes: a hydraulic chamber, the hydraulic chamber is filled with liquid; a shaft sleeve is opened in the hydraulic chamber and is opposite to the MEMS sound diaphragm; a drive shaft connector, a shaft connector and a shaft The sleeve is sealed and slipped; wherein, the cross-sectional area of the drive shaft connector is smaller than the cross-sectional area of the sound membrane of the sound generator.
  • an embodiment of the present application provides a method for producing sound, the method comprising: generating a small amplitude of the MEMS sound film under the action of an acoustic signal; amplifying the small amplitude of the MEMS sound film by means of liquid transmission; The amplified amplitudes are converted into sound waves.
  • Fig. 1 is the design schematic diagram of the MEMS speaker of the prior art
  • Fig. 2 is the schematic diagram of the hydraulic transmission principle of the hydraulic system of two pistons
  • FIG. 3 is a schematic diagram of an embodiment of the present application.
  • FIG. 2 is a schematic diagram of the hydraulic transmission principle of the two-piston hydraulic system.
  • the hydraulic chamber 26 has two pistons 21 and 24 with different cross-sectional areas, and the hydraulic oil 23 is filled therebetween.
  • the piston 24 is on the left and has a larger cross-sectional area, eg 10.
  • the piston 21 is located on the right and has a smaller cross-sectional area, eg 1.
  • the piston 24 moves by, for example, 1 unit length, and the resulting liquid volume change is, for example, 10; and at the same time, when the piston 1 is driven by liquid, it needs to move by, for example, 10 unit lengths to maintain the liquid volume in the hydraulic chamber 26. constant. Therefore, after the movement range of the large sectional area piston 24 is changed by the hydraulic transmission, the movement range of the small piston 21 is increased by 10 times. That is, a hydraulic transmission system composed of two pistons, the ratio of the piston movement amplitude is equal to the reciprocal of the ratio of the piston cross-sectional area.
  • the sound diaphragm 14 of the MEMS (equivalent to the piston 24 in FIG. 2 ) has a diameter of 3 mm and an area of 7 mm 2 ; the maximum amplitude at the center of the diaphragm is 0.1 ⁇ m.
  • the diameter of the diaphragm 25 is 6 mm and the area is 28 mm 2 .
  • the shaft connector 21 has a metallic cylindrical shape. If the shaft connector 21 is directly used to drive the diaphragm 25 to produce sound, the ability to drive the air is the maximum amplitude of the MEMS 0.1 ⁇ m multiplied by 7 mm 2 , that is, 0.0007 mm 3 . And this ability to drive the air determines the output capability of the MEMS speaker's sound power.
  • FIG. 3 is a schematic diagram of an embodiment of the present application. As shown in FIG. 3 , there is a hydraulic chamber 36 in front of the MEMS sound diaphragm 34 , and the hydraulic chamber 36 is filled with the liquid 33 .
  • the liquid 33 may be hydraulic oil, water, etc., preferably hydraulic oil with small volume compressibility and good flow.
  • the hydraulic chamber 36 is provided with a small hole shaft sleeve 32, and a drive shaft connector 31 is arranged therein.
  • the shaft sleeve 32 and the shaft connector 31 can be sealed and slidable.
  • the shaft connector 31 can move up and down in an axial direction perpendicular to the plane where the sound membrane 34 is located.
  • the bushing 32 has a smooth cylindrical shape, and the cross-sectional area of the bushing 32 is much smaller than the area of the MEMS acoustic membrane 34 .
  • the other end of the shaft connector 31 is connected to the diaphragm 35 .
  • the edge of the diaphragm 35 is a raised ring 351, and the ring 351 provides the amplitude of the up and down movement of the diaphragm 35, and also provides lateral support.
  • the diaphragm 35 is fixed on a formed bracket 361 extending upwardly from the hydraulic chamber 36 .
  • the inner opening of the shaft sleeve 32 on the hydraulic chamber 36 is chamfered to avoid sudden changes in area and acute angles, which can improve transient response.
  • the diameter of the hydraulically driven shaft connector 21 (equivalent to the piston 21 in FIG. 2 ) is 0.2 mm. Since the edges of the sound membrane are fixed and the amplitude is zero, the average amplitude of the entire sound membrane is about 0.05 microns.
  • the volume of the liquid pushed by the MEMS sound diaphragm 34 (equivalent to the piston 24 in FIG.
  • it is twice as bad as the hydraulic transmission ratio 225, because in the direct drive, the local maximum amplitude of 0.1 ⁇ m in the center of the MEMS sound membrane is taken, while in this application, the average amplitude of the entire MEMS sound membrane is taken 0.05 microns, the difference is doubled here, so the actual magnification is 225/2 is 112.5 times.
  • the MEMS sound film 34 vibrates up and down, and drives the hydraulic oil 33 . Due to the incompressibility of the liquid, the inner volume of the hydraulic chamber 36 does not change, the MEMS diaphragm 34 moves upward, and the reduced volume is applied to the drive shaft 31 in a pressure manner, so that the shaft 31 moves upward to compensate for the reduced volume.
  • the present application also solves a process problem in designing the structure as shown in FIG. 1 in the prior art: that is, when the connector 1 is connected to the MEMS sound membrane 4 (generally by gluing), since the MEMS sound membrane is very It is thin and fragile. When gluing or moving after gluing or doing other post-processes, it is easy to cause damage to the MEMS sound membrane due to stress. In the present application, however, there is no hard contact between the drive shaft 31 and the MEMS sound diaphragm 34, and the hydraulic oil can be added after the assembly is completed. Thus, the fragile MEMS sound diaphragm 34 is protected from damage, and the assembly yield is improved.
  • the hydraulic chamber, the shaft sleeve and the drive shaft connector constitute a hydraulic transmission mechanism, which amplifies the small amplitude of the MEMS sound diaphragm by means of liquid transmission.
  • the hydraulic transmission mechanism can be varied, such as a combination of a replacement bushing and a drive shaft connector. Other forms of hydraulic transmission are also possible.
  • This application can be used not only for the design of MEMS speakers, but also for traditional piezoelectric ceramic speakers, moving iron, electromagnetic drives, etc. with small amplitudes and indirect drive sound design that needs to amplify the amplitude, especially underwater sound production Institutions and underwater sonar, etc.
  • the use in underwater sonar is the reverse of FIG. 3 , that is, the sound film 34 is the sound collecting plate of the sonar, and the diaphragm 35 is replaced by a sensor such as piezoelectric ceramics.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)

Abstract

一种利用液压传动放大振幅的发声方法和结构，利用液压传动的液体体积不可压缩性，及活塞的振幅与活塞截面积的反比例关系，实现振幅放大。

Description

一种利用液压传动放大振幅的发声方法和结构 技术领域
本申请涉及声学领域，具体涉及振幅很小的发声器。
背景技术
目前微型扬声器需求大增，MEMS扬声器是目前最薄的发声技术，国外已经有见到两间公司推出初步产品。图1是现有技术的MEMS扬声器的示意图。在图1中，与传统的动铁扬声器发声设计基本相仿，驱动轴连接器11是MEMS音膜14和振膜15的连接器；利用连接器11(圆柱或Usound的H型)把MEMS驱动器14的振幅传递到一个振膜15上，驱动振膜振动发声。振膜的面积比MEMS的面积大不少，把输出声功率放大了，但由于MEMS的振幅很小，但是声压还是很有限。
发明内容
本申请在第一方面提供一种微型扬声器。该微型扬声器包括：MEMS音膜，用于产生小的振幅；液压传动机构，用于通过液体传动方式把MEMS音膜的小振幅放大；振膜，用于将放大后的振幅转换为声波。
在一个可能的实现方式中，液压传动机构包括：液压腔，所述液压腔内充满了液体；轴套，开设在液压腔并且在MEMS音膜的对面；驱动轴连接器，轴连接器和轴套密封滑配；其中，驱动轴连接器的截面积小于发声器音膜的截面积。
在第二方面，本申请实施例提供一种发声结构。发声结构包括：发声单元，用于产生小的振幅；液压传动机构，用于通过液体传动方式把MEMS音膜的小振幅放大；振膜，用于将放大后的振幅转换为声波。
在一个可能的实现方式中，发声结构是MEMS扬声器，传统扬声器，水下发声机构或水下声呐。
在一个可能的实现方式中，液压传动机构包括：液压腔，所述液压腔内充满了液体；轴套，开设在液压腔并且在MEMS音膜的对面；驱动轴连接器，轴连接器和轴套密封滑配；其中，驱动轴连接器的截面积小于发声器音膜的截面积。
在第三方面，本申请实施例提供一种发声方法，所述方法包括：MEMS 音膜在声信号的作用下产生小振幅；通过液体传动方式把MEMS音膜的微小振幅放大；利用振膜将放大后的振幅转换为声波。
附图说明
图1是现有技术的MEMS扬声器的设计示意；
图2是两个活塞的液压系统的液压传动原理的示意图；
图3是本申请实施例的示意图。
具体实施方式
为了更好的理解本设计，下面给出具体的实施例，但这里不是对本设计的限制，仅是提供可能的多种实施方式的举例说明。
本申请提出了一个利用液压传动的变比原理进行振幅放大的方法和结构。液压传动时可以通过活塞截面积的变比实现轴向运动幅度的变比放大，其原理就是液体的体积不可压缩性。图2是两个活塞的液压系统的液压传动原理的示意图。如图2所示，液压腔26有两个截面积不同的活塞21和24，其间充满了液压油23。活塞24位于左侧，具有较大的截面积，例如为10。活塞21位于右侧，具有较小的截面积，例如为1。
活塞24作例如1个单位长度的运动，带来的液体体积变化量例如为10；而同时活塞1在受到液体传动时，需要运动例如10个单位长度，以维持液压腔26内的液体体积的不变。因而大截面积活塞24的运动幅度经过液压传动变比后，小活塞21的运动幅度变大了10倍。即两个活塞构成的液压传动系统，活塞运动幅度的变比等于活塞截面积变比的倒数。
参看图1，在一个例子中，MEMS的音膜14(相当于附图2中的活塞24)直径为3毫米，面积为7mm 2；振膜中心的最大振幅为0.1微米。振膜25的直径为6毫米，面积为28mm 2。轴连接器21具有金属圆柱形状。如果直接用轴连接器21驱动振膜25发声，驱动空气的能力就是MEMS的最大振幅0.1微米乘于7mm 2，即0.0007mm 3。而这个驱动空气的能力就决定了MEMS扬声器声功率的输出能力。
图3是本申请实施例的示意图。如图3所示，在MEMS音膜34前有一个液压腔36，液压腔36内充满了液体33。液体33可以是液压油或水等，优选为体积压缩性小，流动好的液压油。
在MEMS音膜34的对面，液压腔36开有一个小孔的轴套32，内有一个驱动轴连接器31。轴套32和轴连接器31可以密封滑配。轴连接器31 可以在垂直于音膜34所在平面的轴向上下运动。在一个例子中，轴套32具有光滑的圆柱的形状，轴套32的截面积远小于MEMS音膜34的面积。
在背离液压腔36的外侧，轴连接器31的另一端连接振膜35。振膜35的边缘是凸起的折环351，折环351提供振膜35上下运动的振幅，同时提供横向的支撑。振膜35固定在液压腔36向上延伸的形成的支架361上。在一个例子中，为了更好的流体力学特性，液压腔36上的轴套32的内侧开口有倒角，避免面积突变和锐角，可以改善瞬变响应。
在操作中，假设MEMS音膜34中心的最大振幅同样为0.1微米，液压传动的轴连接器21(相当于图2中的活塞21)的直径取0.2毫米。因为音膜边缘是固定的，振幅为零，因而整个音膜的平均振幅约为0.05微米。MEMS音膜34(相当于图2中的活塞24)每次运动推动的液体体积约为：7mm 2×0.05微米，相应地，轴连接器31的振幅为：7mm 2×0.05微米÷(3.14×0.1 2mm 2)＝11.25微米；其中，0.1mm为轴套32的半径。这个变比系数就是MEMS的音膜直径与活塞轴1的直径的平方比(也就是活塞截面积的变比的倒数)，即：3 2/0.2 2＝225。如果用来驱动直径6毫米的振膜，驱动空气的能力就是11.25微米×28mm 2＝0.315mm 3，与不采用活塞结构的相比放大了112.5倍。请注意，这里比液压传动变比225差了一倍，这是因为直接驱动中取的是MEMS音膜中心的局部最大振幅0.1微米，而在本申请中，要取整个MEMS音膜的平均振幅0.05微米，此处差了一倍，所以实际放大倍数就是225/2为112.5倍。
当馈入信号后，MEMS音膜34产生上下振动，驱动液压油33。由于液体的不可压缩性，液压腔36的内容积不变，MEMS音膜34向上运动，并且减少的容积以压力方式被施加于驱动轴31上，使得轴31向上运动弥补减少的容积。假如MEMS音膜直径为3毫米，驱动轴1的直径取0.2毫米，则面积比为0.25π×3 2/(0.25π×0.2 2)＝225。因而MEMS音膜34的平均振幅为0.05微米时，驱动轴1的振幅为11.25微米。如此一来，MEMS发声的振幅小的技术难题就解决了。
在一个例子中，本申请也同时解决现有技术设计如图1中的结构的一个工艺难题：即在把连接器1连接到MEMS音膜4上时(一般采用胶合)，由于MEMS音膜很薄很脆弱，胶合时或胶好后移动或做其它后期工序时，很容易发生MEMS音膜受力而损伤。而在本申请中，驱动轴31与MEMS音膜34不存在硬接触，而液压油可以在装配完成后才加入。从而保护脆弱的MEMS音膜34不受损伤，提高装配良品率。
在上文的实施例中，液压腔、轴套和驱动轴连接器构成了一种液压传 动机构，通过液体传动方式把MEMS音膜的小振幅放大。本领域的技术人员意识到，液压传动机构可以是多种多样的，比如可以替换轴套和驱动轴连接器的组合。其它形式的液压传动机构也是可行的。
本申请不仅可以用于MEMS扬声器的设计，也可以用于传统的压电陶瓷发声的扬声器和动铁、电磁驱动等各种振幅微小，需要放大振幅的间接驱动发声的设计，尤其是水下发声机构和水下声呐等。在水下声纳里的使用是图3的反向使用，即音膜34是声纳的声音采集板，而振膜35代替为压电陶瓷等传感器。
以上的具体实施方式，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上仅为本发明的具体实施方式而已，并不用于限定本发明的保护范围，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (6)

  1. 一种微型扬声器，包括：
    MEMS音膜(34)，用于产生小的振幅；
    液压传动机构，用于通过液体传动方式把MEMS音膜的小振幅放大；
    振膜(35)，用于将放大后的振幅转换为声波。
  2. 如权利要求1所述的微型扬声器，其中，液压传动机构包括：
    液压腔(36)，所述液压腔内充满了液体；
    轴套，开设在液压腔并且在MEMS音膜(34)的对面；
    驱动轴连接器(31)，轴连接器和轴套密封滑配；其中，驱动轴连接器的截面积小于发声器音膜的截面积。
  3. 一种发声结构，包括：
    发声单元，用于产生小的振幅；
    液压传动机构，用于通过液体传动方式把MEMS音膜的小振幅放大；
    振膜，用于将放大后的振幅转换为声波。
  4. 如权利要求3所述的发声结构，其特征还在于，发声结构是MEMS扬声器，传统扬声器，水下发声机构或水下声呐。
  5. 如权利要求4所述的发声结构，其特征还在于，，液压传动机构包括：
    液压腔(36)，所述液压腔内充满了液体；
    轴套，开设在液压腔并且在MEMS音膜(34)的对面；
    驱动轴连接器(31)，轴连接器和轴套密封滑配；其中，驱动轴连接器的截面积小于发声器音膜的截面积。。
  6. 一种发声方法，所述方法包括：
    MEMS音膜在声信号的作用下产生小振幅；
    通过液体传动方式把MEMS音膜的微小振幅放大；
    利用振膜将放大后的振幅转换为声波。
PCT/CN2021/119668 2021-04-28 2021-09-22 一种利用液压传动放大振幅的发声方法和结构 WO2022227383A1 (zh)

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