WO2023283784A1 - Système de haut-parleur mems piézoélectrique - Google Patents

Système de haut-parleur mems piézoélectrique Download PDF

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Publication number
WO2023283784A1
WO2023283784A1 PCT/CN2021/105840 CN2021105840W WO2023283784A1 WO 2023283784 A1 WO2023283784 A1 WO 2023283784A1 CN 2021105840 W CN2021105840 W CN 2021105840W WO 2023283784 A1 WO2023283784 A1 WO 2023283784A1
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WIPO (PCT)
Prior art keywords
piezoelectric mems
speaker
transformer
mems speaker
piezoelectric
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PCT/CN2021/105840
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English (en)
Chinese (zh)
Inventor
张孟伦
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天津大学
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Priority to PCT/CN2021/105840 priority Critical patent/WO2023283784A1/fr
Publication of WO2023283784A1 publication Critical patent/WO2023283784A1/fr

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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

Definitions

  • the present invention relates to the technical field of Micro-Nano Electro-Mechanical System (MEMS, Micro-Electro-Mechanical System), in particular to a piezoelectric MEMS speaker system.
  • MEMS Micro-Nano Electro-Mechanical System
  • Micro-Electro-Mechanical System Micro-Electro-Mechanical System
  • the working principle of the piezoelectric MEMS speaker is to use the piezoelectric effect of the piezoelectric film layer to convert electrical signals into mechanical vibrations, and then generate sound. It has a thin thickness, small size, excellent energy efficiency, fast response, and excellent audio performance, covering the entire frequency range of 20Hz-20kHz. Thanks to modern chip manufacturing technology, the use of silicon materials to develop MEMS speakers has great advantages.
  • the semiconductor material silicon can be processed in large quantities with ultra-microstructures, which is very suitable for speakers, which are very demanding microelectronic devices in the market, and, Also highly cost-effective.
  • the present invention provides a piezoelectric MEMS speaker system with low power consumption.
  • a piezoelectric MEMS speaker system includes: at least one piezoelectric MEMS speaker; and at least one transformer for receiving audio signal input and driving the piezoelectric MEMS speaker.
  • the number of the piezoelectric MEMS speakers is not less than the number of the transformers.
  • the system further includes a moving coil speaker and/or a moving iron speaker.
  • the audio signal input is directly connected to the moving coil speaker and/or the moving iron speaker; or, the audio signal input is indirectly connected to the moving coil speaker and/or the moving iron speaker through the transformer.
  • the primary coil or secondary coil of the transformer is connected in series or in parallel with one or more of the following elements: capacitor, resistor, and inductor.
  • the primary coil of the transformer is connected to the audio signal input
  • the secondary coil of the transformer is connected to the piezoelectric MEMS speaker
  • the number of turns of the primary coil of the transformer is less than or equal to the number of turns of the secondary coil.
  • the side length of the piezoelectric MEMS speaker is less than or equal to 20mm.
  • the transformer is an audio transformer, the area of its largest surface is less than or equal to twice the area of any surface of the piezoelectric MEMS speaker, or its maximum side length is less than or equal to twice the maximum side length of the piezoelectric MEMS speaker .
  • the operating frequency of the piezoelectric MEMS speaker is 20 Hz to 20 kHz.
  • the ratio of the number of turns of the primary coil of the transformer to the number of turns of the secondary coil is 1:1 to 1:10000.
  • the piezoelectric MEMS speaker has a capacitance of 0.1 nF to 1 ⁇ F.
  • the primary inductance of the transformer is 0.01mH to 5H or 0.1mH to 10mH.
  • the input impedance of the system is greater than 20 ohms or greater than 100 ohms.
  • the input impedance at the resonance point fr of the system is greater than 200 ohms or greater than 2000 ohms.
  • the piezoelectric MEMS speaker is of a diaphragm vertical vibration type or a diaphragm plane vibration type.
  • a substrate is also included, and the piezoelectric MEMS speaker and the transformer are arranged on two sides of the substrate.
  • the piezoelectric MEMS speaker includes a piezoelectric film, and includes a silicon substrate or a silicon frame.
  • the electrical resonance point Fr of the system is in the operating frequency band of the piezoelectric MEMS speaker, or the electrical resonance point Fr of the system is between 20 Hz and 20 kHz.
  • the electrical resonance point Fr of the system is smaller than the lowest frequency of the working frequency band of the piezoelectric MEMS speaker, or the electrical resonance point Fr of the system is smaller than 1 kHz.
  • the piezoelectric MEMS speaker is driven based on the transformer. Since the transformer is a passive device, compared with the active solution of the traditional power amplifier, its power consumption is extremely low, and it has the advantages of The structure is simple, and it is suitable for integrating miniaturized devices and the like. At the same time, the transformer and passive components can be used to adjust the electrical input of the piezoelectric MEMS speaker, so that the overall power consumption of the speaker system can be further reduced.
  • Figure 1a and Figure 1b are the cross-sectional view and top view of the diaphragm vertical vibration type piezoelectric MEMS loudspeaker, respectively;
  • Fig. 1c is a perspective view of a piezoelectric MEMS loudspeaker with vertical diaphragm vibration
  • Figure 1d is a perspective view of the fins in the diaphragm vertical vibration type piezoelectric MEMS speaker
  • FIGS. 2a to 2f are schematic diagrams of the working process of the piezoelectric MEMS speaker system according to the first to sixth embodiments of the present invention.
  • FIG. 3 is a schematic cross-sectional view of a piezoelectric MEMS speaker system according to an embodiment of the present invention.
  • Fig. 4 is the schematic structural view of the transformer and the piezoelectric MEMS loudspeaker connected in a basic manner according to the embodiment of the present invention
  • Fig. 5 is an impedance Z curve diagram corresponding to the structure shown in Fig. 4;
  • Fig. 6 is the sound pressure SPL curve diagram corresponding to the structure shown in Fig. 4;
  • Fig. 7 is a power consumption P curve diagram corresponding to the structure shown in Fig. 4;
  • FIGS 8a to 8h are structural schematic diagrams of transformers and piezoelectric MEMS speakers connected in different improved ways
  • Fig. 9 is a curve diagram of power consumption P of a transformer connected in an improved manner and a piezoelectric MEMS speaker.
  • the patent of the present invention proposes a piezoelectric MEMS speaker system based on transformer-driven piezoelectric MEMS speakers. Since the transformer is a passive device, it consumes very little power compared to an active solution such as a power amplifier. After optimization, the design of the transformer in the speaker system ensures the frequency response performance in the working frequency band. At the same time, the transformer and passive components are used to adjust the electrical input of the piezoelectric MEMS speaker so that its resonant frequency is between 20Hz and 20kHz, and the input impedance is between 20Hz and 20kHz. The resonance point reaches the maximum, reducing the power consumption of the speaker.
  • a piezoelectric MEMS speaker system may include: an audio signal input; at least one piezoelectric MEMS speaker; and at least one transformer, which is used to receive an audio signal from outside the piezoelectric MEMS speaker system , and driving piezoelectric MEMS speakers.
  • the side length of the piezoelectric MEMS speaker can be less than or equal to 20mm
  • the area of the largest surface of the transformer is less than or equal to twice the area of any side of the piezoelectric MEMS speaker
  • the maximum side length of the transformer is less than or equal to 2 times the maximum side length of the piezoelectric MEMS speaker.
  • Piezoelectric MEMS speakers can operate at frequencies from 20Hz to 20kHz.
  • This transformer is an audio transformer.
  • Piezoelectric MEMS speakers can be divided into two types: the vertical vibration type of the diaphragm and the planar vibration type of the diaphragm.
  • FIG. 1a and FIG. 1b are respectively a cross-sectional view and a top view of a piezoelectric MEMS loudspeaker 100 with vertical diaphragm vibration.
  • the diaphragm vertical vibration structure piezoelectric MEMS speaker 100 includes:
  • silicon substrate the material can be single crystal silicon or polycrystalline silicon
  • the material can be molybdenum, aluminum and other materials
  • the material can be piezoelectric materials such as ALN, ZnO, PZT, etc., and the thickness is less than 20 microns;
  • the top electrode the material can be molybdenum, gold, aluminum and other materials;
  • FIG. 1 c is a perspective view of a piezoelectric MEMS speaker 110 with a vertical vibration membrane
  • FIG. 1 d is a perspective view of a fin 112 in a piezoelectric MEMS speaker 110 with a vertical vibration of a diaphragm.
  • the diaphragm vertical vibration type piezoelectric MEMS speaker 110 is shown in FIG. 1c, and may include:
  • the surrounding frame the material can be silicon
  • Fins as shown in Figure 1d, specifically may include:
  • Silicon-based framework the material can be single crystal silicon or polycrystalline silicon;
  • Piezoelectric film layer the material can be AlN, doped AlN, PZT and other common piezoelectric film materials;
  • the material can be Mo, Pt, Au, Al and other commonly used electrode materials.
  • the number of piezoelectric MEMS speakers is not less than the number of transformers. This means that each transformer can drive one or more loudspeakers.
  • the piezoelectric MEMS speaker system may also include conventional moving coil speakers and/or moving iron speakers. Dynamic and/or moving iron speakers are better at low frequencies and can be paired with piezoelectric MEMS speakers that perform well at high frequencies.
  • the audio signal input may be directly connected to the moving coil speaker and/or the moving iron speaker; or, the audio signal input is indirectly connected to the moving coil speaker and/or the moving iron speaker through a transformer. A number of examples are listed below for illustration.
  • Fig. 2a shows a piezoelectric MEMS speaker system 10 and an external audio signal source 3 according to the first embodiment of the present invention.
  • the piezoelectric MEMS speaker system 10 includes: a piezoelectric MEMS speaker 1 and a transformer 2 .
  • the signal provided by the external audio signal source 3 is amplified by the transformer 2, and then drives the piezoelectric MEMS speaker 1 to produce sound. This method takes up little space and is suitable for the application of small-sized speaker systems (such as earphones).
  • Fig. 2b shows a piezoelectric MEMS speaker system 10 and an external audio signal source 3 according to a second embodiment of the present invention.
  • the piezoelectric MEMS speaker system 10 includes: two identical or different piezoelectric MEMS speakers 1 and a transformer 2 .
  • the signal provided by the external audio signal source 3 is amplified by the transformer 2, and then connected to two piezoelectric MEMS speakers 1, which can increase the output sound pressure.
  • Fig. 2c shows a piezoelectric MEMS speaker system 10 and an external audio signal source 3 according to a third embodiment of the present invention.
  • the piezoelectric MEMS speaker system 10 includes: two piezoelectric MEMS speakers 1 and two transformers 2 . Signals provided by an external audio signal source 3 are amplified by two transformers 2 connected in parallel, and then connected to two piezoelectric MEMS speakers 1 respectively. This embodiment is applicable to the situation that the wire diameter of the transformer 2 is small and cannot carry an excessive current.
  • Fig. 2d shows a piezoelectric MEMS speaker system 10 and an external audio signal source 3 according to a fourth embodiment of the present invention.
  • the piezoelectric MEMS speaker system 10 includes: a piezoelectric MEMS speaker 1 , a transformer 2 , and a dynamic coil speaker 5 .
  • the external audio signal source 3 provides two channels of signals, one of which is amplified by the transformer 2 to drive the piezoelectric MEMS speaker 1 , and the other is directly output by the external audio signal source 3 to drive the dynamic coil speaker 5 .
  • the purpose of this embodiment is to combine the piezoelectric MEMS speaker that needs to be driven by a higher voltage and the dynamic speaker that needs to be driven by a higher current to obtain better audio signal energy distribution and audio output.
  • the moving coil speaker 5 can also be replaced by a moving iron speaker.
  • Fig. 2e shows a piezoelectric MEMS speaker system 10 and an external audio signal source 3 according to a fifth embodiment of the present invention.
  • the piezoelectric MEMS speaker system 10 includes: a piezoelectric MEMS speaker 1 , a transformer 2 , a moving coil speaker 5 and a moving iron speaker 6 .
  • the signal provided by the external audio signal source 3 is amplified by the transformer 2 to drive the piezoelectric MEMS speaker 1 , while driving the dynamic coil speaker 5 and the moving iron speaker 6 without amplification.
  • This embodiment can improve the sound quality by combining the performances of the three loudspeakers in different frequency bands, and at the same time distribute the audio signal energy more reasonably.
  • Fig. 2f shows the piezoelectric MEMS speaker system 10 and the external audio signal source 3 according to the sixth embodiment of the present invention.
  • the piezoelectric MEMS speaker system 10 includes: a piezoelectric MEMS speaker 1 , a transformer 2 , a moving coil speaker 5 and a moving iron speaker 6 .
  • the signal provided by the external audio signal source 3 is amplified by the transformer 2 to drive the piezoelectric MEMS speaker 1 and the moving iron speaker 6 , while driving the moving coil speaker 5 without amplifying.
  • This embodiment shows that the sound pressure of two kinds of loudspeakers is simultaneously driven by the transformer 2, so as to balance the sound quality of the whole frequency range. It should be noted that the connection modes of the moving coil speaker 5 and the moving iron speaker 6 can be interchanged.
  • the piezoelectric MEMS speaker system may further include a substrate, and the piezoelectric MEMS speaker and the transformer may be arranged on both sides of the substrate. Adopting such a rear installation method can reduce the overall volume.
  • the piezoelectric MEMS loudspeaker may also include a housing with a sound hole to facilitate the sound wave transmission.
  • the transformer 2 is installed on the back of the substrate 8, and then connected to the piezoelectric MEMS speaker 1 on the front through the via hole on the substrate 8, and the housing 7 of the piezoelectric MEMS speaker 1 has an acoustic hole . This method can reduce volume and area, and is easy to integrate into small devices.
  • FIG. 4 is a schematic structural diagram of a transformer and a piezoelectric MEMS speaker connected in a basic manner according to an embodiment of the present invention.
  • the primary coil of the transformer is connected to the audio signal input
  • the secondary coil of the transformer is connected to the piezoelectric MEMS speaker
  • the number of turns of the primary coil of the transformer is less than or equal to the number of turns of the secondary coil.
  • the input impedance Z is shown in FIG. 5
  • the output sound pressure SPL is shown in FIG. 6
  • the system power consumption P is shown in FIG. 7 .
  • the transformer Since the transformer is connected to the piezoelectric MEMS speaker, the transformer modulates the input impedance profile of the piezoelectric MEMS speaker, especially at the frequency fr to create a parallel electrical resonance. This resonance is generated by the piezoelectric MEMS speaker and the primary coil of the transformer, and depends on the capacitance value of the piezoelectric MEMS speaker, the inductance value of the transformer primary coil, and the turns ratio of the transformer primary coil to the secondary coil.
  • the electrical resonance point fr can be placed in the working frequency band of the speaker, that is, f1 ⁇ fr ⁇ f2, f1 and f2 is the lowest frequency (such as 20Hz) and the highest frequency (such as 20kHz) of the working frequency band.
  • the input impedance of the transformer/speaker system is maximized at fr, which can greatly reduce power dissipation at this frequency and in nearby frequency bands.
  • f1 ⁇ fr ⁇ f2 the power consumption of the speaker can be greatly reduced.
  • fr when fr ⁇ f1, the power consumption of the speaker can also be reduced to a certain extent; for example, when f1 is 1kHz, fr can be less than 1kHz.
  • fr can be adjusted by adjusting the turns ratio of the primary and secondary coils of the transformer, the capacitance value of the speaker, and the inductance value of the primary coil of the transformer.
  • the ratio of primary coil turns to secondary coil turns of the transformer can be 1:1 to 1:10000.
  • Capacitance values for piezoelectric MEMS speakers can range from 0.1nF to 1 ⁇ F.
  • the primary inductance of the transformer can be 0.01mH to 5H or 0.1mH to 10mH.
  • the system input impedance Z can be greater than 20 ohms or greater than 100 ohms, and the input impedance at the resonance point fr of the system can be greater than 200 ohms or greater than 2000 ohms. ohm.
  • the primary coil or secondary coil of the transformer can also be connected in series or in parallel with one or more of the following components: capacitor, resistor, and inductor to further increase impedance and reduce power. consumption, especially at f1 and/or fr.
  • connecting the primary coil with a capacitor in series increases its impedance in the low frequency range, which can not only adjust the resonance point, improve the sound quality, but also reduce the power consumption in the low frequency range.
  • connecting the primary coil with resistors in series increases the impedance of the entire frequency band, thereby improving the power consumption performance in each frequency band.
  • connecting the primary coil to the inductor in series can play a role in adjusting the resonance point, so that the resonance point moves to a lower frequency band, thereby changing the power consumption in the low frequency band.
  • the high-frequency impedance is increased, and the power consumption of high-frequency is also reduced.
  • connecting the secondary coil with a capacitor in series can increase the impedance of the low frequency band, thereby reducing the power consumption of the low frequency band.
  • connecting the primary coil with a capacitor in parallel can reduce the frequency of the resonance point, improve low-frequency sound quality, and reduce low-frequency power consumption.
  • the primary coil is connected in series with a capacitor and a resistor.
  • the capacitor can increase the low frequency impedance
  • the resistor can increase the full frequency impedance, thereby improving the power consumption performance of the full frequency band.
  • connecting the secondary coil in series with the resistor can increase the impedance of the whole frequency band, thereby reducing the power consumption of the whole frequency band.
  • connecting the secondary coil in series with the inductor can effectively increase the impedance at high frequency, thereby reducing the power consumption at high frequency.
  • the piezoelectric MEMS speaker system is improved using the methods shown in Figures 8a to 8h.
  • the improved power consumption performance is shown in Figure 9, which can greatly reduce power consumption, especially in low-frequency bands below the fr frequency.
  • the piezoelectric MEMS speaker is driven based on the transformer. Since the transformer is a passive device, compared with the active solution of the traditional power amplifier, its power consumption is extremely low. Simple, suitable for integrating miniaturized devices and other advantages.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)

Abstract

L'invention concerne un système de haut-parleur MEMS piézoélectrique (10), comprenant : au moins un haut-parleur MEMS piézoélectrique (1) ; et au moins un transformateur (2), le transformateur (2) étant utilisé pour recevoir une entrée de signal audio et pour entraîner le haut-parleur MEMS piézoélectrique (1). Dans le système de haut-parleur MEMS piézoélectrique (10), le haut-parleur MEMS piézoélectrique (1) est entraîné par le transformateur (2). Le transformateur (2) étant un dispositif passif, par comparaison avec une solution active d'un amplificateur de puissance classique, le système de haut-parleur MEMS piézoélectrique a une faible consommation d'énergie et une structure simple, et est applicable à un dispositif miniaturisé intégré.
PCT/CN2021/105840 2021-07-12 2021-07-12 Système de haut-parleur mems piézoélectrique WO2023283784A1 (fr)

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS585100B2 (ja) * 1980-08-21 1983-01-29 福廣 安修 製砂機
EP0883326A2 (fr) * 1997-06-03 1998-12-09 Murata Manufacturing Co., Ltd. Transformateur pour haut-parleur piézoélectrique et haut-parleur piézoélectrique fonctionnant avec ce transformateur
WO1999005885A1 (fr) * 1997-07-23 1999-02-04 Shinsei Corporation Systeme d'enceinte acoustique
US5901231A (en) * 1995-09-25 1999-05-04 Noise Cancellation Technologies, Inc. Piezo speaker for improved passenger cabin audio systems
US6345102B1 (en) * 1996-10-16 2002-02-05 New Transducers Limited Vehicle loudspeakers
CN201042075Y (zh) * 2007-04-29 2008-03-26 瑞声声学科技(常州)有限公司 压电扬声器
US20100086151A1 (en) * 2005-12-07 2010-04-08 Tpo Displays Corp. Piezoelectric Speaker
CN203482389U (zh) * 2013-09-18 2014-03-12 中兴通讯股份有限公司 一种压电扬声器驱动装置
CN207010973U (zh) * 2017-08-07 2018-02-13 感至源电子科技（上海）有限公司 聚丙烯压电薄膜扬声装置
CN207427469U (zh) * 2017-09-29 2018-05-29 广州千艺电子制造有限公司 新型压电陶瓷式高音扬声器

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS585100B2 (ja) * 1980-08-21 1983-01-29 福廣 安修 製砂機
US5901231A (en) * 1995-09-25 1999-05-04 Noise Cancellation Technologies, Inc. Piezo speaker for improved passenger cabin audio systems
US6345102B1 (en) * 1996-10-16 2002-02-05 New Transducers Limited Vehicle loudspeakers
EP0883326A2 (fr) * 1997-06-03 1998-12-09 Murata Manufacturing Co., Ltd. Transformateur pour haut-parleur piézoélectrique et haut-parleur piézoélectrique fonctionnant avec ce transformateur
WO1999005885A1 (fr) * 1997-07-23 1999-02-04 Shinsei Corporation Systeme d'enceinte acoustique
US20100086151A1 (en) * 2005-12-07 2010-04-08 Tpo Displays Corp. Piezoelectric Speaker
CN201042075Y (zh) * 2007-04-29 2008-03-26 瑞声声学科技(常州)有限公司 压电扬声器
CN203482389U (zh) * 2013-09-18 2014-03-12 中兴通讯股份有限公司 一种压电扬声器驱动装置
CN207010973U (zh) * 2017-08-07 2018-02-13 感至源电子科技（上海）有限公司 聚丙烯压电薄膜扬声装置
CN207427469U (zh) * 2017-09-29 2018-05-29 广州千艺电子制造有限公司 新型压电陶瓷式高音扬声器

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