CN107071673B - Silicon-based MEMS array loudspeaker - Google Patents

Silicon-based MEMS array loudspeaker Download PDF

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CN107071673B
CN107071673B CN201710082342.6A CN201710082342A CN107071673B CN 107071673 B CN107071673 B CN 107071673B CN 201710082342 A CN201710082342 A CN 201710082342A CN 107071673 B CN107071673 B CN 107071673B
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sound
micro
silicon
insulating sheet
mems
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CN107071673A (en
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徐波
徐金国
吴逸飞
朱志刚
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Bestar Holding Co ltd
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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
    • H04R2400/00—Loudspeakers
    • H04R2400/11—Aspects regarding the frame of loudspeaker transducers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)

Abstract

The invention relates to a silicon-based MEMS array loudspeaker, which comprises a substrate, a plurality of MEMS micro-sound units and a plurality of MEMS micro-sound units, wherein the MEMS micro-sound units are arrayed on the substrate; the MEMS micro-sound unit comprises a vibrating diaphragm serving as an intermediate electrode, an upper insulating sheet, a lower insulating sheet, an upper conducting plate and a lower conducting plate, wherein the upper insulating sheet and the lower insulating sheet are connected to the upper surface and the lower surface of the vibrating diaphragm, the upper conducting plate is used as an upper electrode, the lower conducting plate is used as a lower electrode, the upper conducting plate is arranged on the upper insulating sheet, the lower conducting plate is arranged on the lower insulating sheet, central holes are formed in the upper insulating sheet and the lower insulating sheet, a plurality of sounding holes communicated with the central holes are formed in the upper conducting plate, and vent holes communicated with the central holes are formed in the lower conducting plate. The invention has the characteristics of thin thickness, good tone quality and the like.

Description

Silicon-based MEMS array loudspeaker
Technical Field
The invention relates to the technical field of speakers, in particular to a silicon-based MEMS array speaker.
Background
At present, the loudspeakers in the market are usually moving coil loudspeakers, moving iron loudspeakers, piezoelectric loudspeakers and electrostatic loudspeakers, and the demands of the market for thinner loudspeakers and clearer sound quality are increasing increasingly, most of products are digitalized and miniaturized in the whole electronic industry, and the demands of the electronic industry are not met by the existing loudspeakers.
Disclosure of Invention
In view of the above technical problems, the present invention provides a silicon-based MEMS array speaker for solving the above problems.
The technical scheme for realizing the invention is as follows:
a silicon-based MEMS array loudspeaker comprises a substrate, a plurality of MEMS micro-sound units and a plurality of MEMS micro-sound units, wherein the MEMS micro-sound units are arrayed on the substrate;
the MEMS micro-sound unit comprises a vibrating diaphragm serving as an intermediate electrode, an upper insulating sheet, a lower insulating sheet, an upper conducting plate and a lower conducting plate, wherein the upper insulating sheet and the lower insulating sheet are connected to the upper surface and the lower surface of the vibrating diaphragm, the upper conducting plate is used as an upper electrode, the lower conducting plate is used as a lower electrode, the upper conducting plate is arranged on the upper insulating sheet, the lower conducting plate is arranged on the lower insulating sheet, central holes are formed in the upper insulating sheet and the lower insulating sheet, a plurality of sounding holes communicated with the central holes are formed in the upper conducting plate, and vent holes communicated with the central holes are formed in the lower conducting plate.
Further, the shape of the single MEMS micro-acoustic unit is an equilateral hexagon.
Further, the vibrating diaphragm comprises a regular hexagonal edge part and a round middle part, wherein the middle part is positioned at the center of the edge part, and the middle part is connected with the edge part through an S-shaped suspension wire.
Further, the S-shaped suspension wires are four.
Further, the vibrating diaphragm and the suspension wires are made of silicon films.
Further, there are 1024 MEMS micro-acoustic units.
The sound pressure level setting comprises the following algorithm;
s1, obtaining the resonant frequency F0 of a vibrating diaphragm of a single MEMS micro-sound unit as X through comsol simulation;
s2, presetting the resonant frequency F0 of the silicon-based MEMS array loudspeaker as Y;
s3, then the sound pressure level of F0 point at 1m of the silicon-based MEMS array loudspeaker
Figure BDA0001226279160000021
I.e. sound pressure level of a single micro-sound unit +.>
Figure BDA0001226279160000022
S4, verifying the SPL in S3 1 The diaphragm with charges is subjected to the alternating electric field of the upper polar plate and the lower polar plate, and the unit motion on the diaphragm meets the vibration equation:
Figure BDA0001226279160000023
m is unit mass, c is damping, k is rigidity, u is displacement vector, t is time, and f (t) is electric field force load;
the diaphragm vibrates reciprocally with the amplitude of 20um to drive the surrounding air to move, and the sound wave is transmitted from near to far, so that the wave equation is satisfied:
Figure BDA0001226279160000024
wherein the wave number is
Figure BDA0001226279160000025
w is the angular frequency of the light beam,co is the sound velocity, p (x) is the sound pressure in the propagation direction x,
taking the reference sound pressure as po=2×10-5Pa, and the sound pressure level Lp at any place in the space is:
Figure BDA0001226279160000026
calculating the sound pressure SPLa of the micro-sound unit at 1cm, and then passing through the formula
Figure BDA0001226279160000027
(La is the distance at a and Lb is the distance at b) to obtain the micro-sound unit SPL 1 And (5) performing verification.
By adopting the scheme, the upper electrode (upper conducting plate) of the micro-sound unit is connected with an ultrasonic alternating current signal positive signal, the lower electrode (lower conducting plate) is connected with an ultrasonic alternating current signal negative signal, the middle electrode is set to be in direct current bias, the positive signal of the upper electrode and the positive charge of the middle electrode repel each other during working, the negative signal of the lower electrode and the positive charge of the middle electrode attract each other, the middle electrode (vibrating diaphragm) moves up and down along with the alternating signal, and the middle electrode (vibrating diaphragm) moves up and down to push air to sound, and the air is emitted into the air through the upper electrode (upper sound emitting hole) to be heard by human ears. And then the volume and frequency of the MEMS array loudspeaker are regulated by controlling the sounding quantity and time of 1024 micro-sound units through software, so that the tone quality is improved, and people can hear graceful music. The loudspeaker of the invention has thinner thickness and clearer tone quality, the pronunciation of the loudspeaker is generated directly by digital signals without analog signal conversion, the distortion brought in the signal conversion process is greatly reduced, the synthesized loudspeaker is flatter than the traditional loudspeaker in frequency response by a plurality of micro-sound units, the tone quality is more perfect, and the push-pull design of the upper electrode and the lower electrode and the pressure difference design of the upper hole and the lower hole lead the MEMS loudspeaker to have higher sound pressure level than other MEMS.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a schematic diagram of the structure of a MEMS micro-acoustic unit;
FIG. 3 is a schematic diagram of a diaphragm mechanism;
fig. 4 is a graph of sound pressure level versus resonant frequency.
Detailed Description
The invention will be further described with reference to the drawings and specific examples.
As shown in fig. 1 to 3, a silicon-based MEMS array speaker includes a substrate 1, 1024 MEMS micro-acoustic units 2, a plurality of MEMS micro-acoustic units are arrayed on the substrate, and the shape of a single MEMS micro-acoustic unit is an equilateral hexagon;
the MEMS micro-sound unit comprises a vibrating diaphragm 21 serving as an intermediate electrode, an upper insulating sheet 22 and a lower insulating sheet 23 connected to the upper surface and the lower surface of the vibrating diaphragm, an upper conducting plate 24 serving as an upper electrode and a lower conducting plate 25 serving as a lower electrode, wherein the upper conducting plate is arranged on the upper insulating sheet, the lower conducting plate is arranged on the lower insulating sheet, central holes 26 are formed in the upper insulating sheet and the lower insulating sheet, a plurality of sounding holes 27 communicated with the central holes are formed in the upper conducting plate, and vent holes 28 communicated with the central holes are formed in the lower conducting plate.
The diaphragm 21 includes a regular hexagonal edge portion 211 and a circular middle portion 212, the middle portion is located at the center of the edge portion, the middle portion is connected with the edge portion through four S-shaped suspension wires 213, and the diaphragm and the suspension wires are made of silicon films.
Setting the F0 and sound pressure level of the silicon-based MEMS array loudspeaker, which is preset to be 800Hz, the sound pressure SPL of the silicon-based MEMS array loudspeaker is 70dB at the position of 1m, and the F0 of each micro-sound unit is 22046Hz through simulation, so that the sound pressure level of the F0 point of the silicon-based MEMS array loudspeaker at the position of 1m
Figure BDA0001226279160000041
That is to say the sound pressure level of a single micro-sound unit +.>
Figure BDA0001226279160000042
The diaphragm with charges is subjected to the alternating electric field of the upper polar plate and the lower polar plate, and the unit motion on the diaphragm meets the vibration equation:
Figure BDA0001226279160000043
m is unit mass, c is damping, k is rigidity, u is displacement vector, t is time, and f (t) is electric field force load;
the diaphragm vibrates reciprocally with the amplitude of 20um to drive the surrounding air to move, and the sound wave is transmitted from near to far, so that the wave equation is satisfied:
Figure BDA0001226279160000044
wherein the wave number is
Figure BDA0001226279160000045
w is the angular frequency, co is the sound velocity, p (x) is the sound pressure in the propagation direction x,
taking the reference sound pressure as po=2×10-5Pa, and the sound pressure level Lp at any place in the space is:
Figure BDA0001226279160000046
then calculating the sound pressure SPL of the micro-sound unit at 1cm through the comsol software f0＝22046 =78 dB, as in fig. 4, again by the formula +.>
Figure BDA0001226279160000047
Deriving a micro-acoustic unit SPL 1 =38db, substantially meeting the design requirements.
Regarding the gap setting of MEMS micro-acoustic units, we need the sound pressure level SPL of the MEMS micro-acoustic units 1 =38.6 dB, back-pushing the sound pressure of a single micro-sound unit
Figure BDA0001226279160000051
Its amplitude
Figure BDA0001226279160000052
(p is sound pressure, r is distance, S is area of diaphragm, f is frequency), that is, each micro-acoustic unit requires a gap of at least 26 um. />

Claims (5)

1. A silicon-based MEMS array speaker, characterized by:
comprising a substrate and a plurality of layers of metal layers,
the MEMS micro-sound units are arrayed on the substrate, and 1024 MEMS micro-sound units are arranged;
the MEMS micro-sound unit comprises a vibrating diaphragm serving as an intermediate electrode, an upper insulating sheet, a lower insulating sheet, an upper conducting plate and a lower conducting plate, wherein the upper insulating sheet and the lower insulating sheet are connected to the upper surface and the lower surface of the vibrating diaphragm;
the sound pressure level of the single MEMS micro-sound unit is set through the following algorithm:
s1, obtaining the resonant frequency F0 of a vibrating diaphragm of a single MEMS micro-sound unit as X through comsol simulation;
s2, presetting the resonant frequency F0 of the silicon-based MEMS array loudspeaker as Y;
s3, then the sound pressure level of F0 point at 1m of the silicon-based MEMS array loudspeaker
Figure QLYQS_1
In the formula, a is the single number of MEMS micro-sound units, b is the total number of MEMS micro-sound units in the MEMS array loudspeaker, namely the sound pressure level of the single micro-sound unit +.>
Figure QLYQS_2
；
S4, verifying the SPL in S3 1 The diaphragm with charges is subjected to the alternating electric field of the upper polar plate and the lower polar plate, and the unit motion on the diaphragm meets the vibration equation:
Figure QLYQS_3
，
m is unit mass, c is damping, k is rigidity, u is displacement vector, t is time, and f (t) is electric field force load;
satisfies the wave equation:
Figure QLYQS_4
，
wherein the wave number is
Figure QLYQS_5
W is the angular frequency, C 0 Is the sound velocity, p (x) is the sound pressure in the propagation direction x,
taking the reference sound pressure as po=2×10-5Pa, and the sound pressure level Lp at any place in the space is:
Figure QLYQS_6
wherein p is the sound pressure at the position;
calculating the sound pressure SPLa of the micro-sound unit at 1cm, and then passing through the formula
Figure QLYQS_7
L in the formula a For the distance at a, L b For the distance at b, a micro-sound unit SPL is derived 1 And (5) performing verification.
2. A silicon-based MEMS array speaker as claimed in claim 1 wherein: the shape of the individual MEMS micro-acoustic units is an equilateral hexagon.
3. A silicon-based MEMS array speaker as claimed in claim 1 wherein: the vibrating diaphragm comprises a regular hexagonal edge part and a round middle part, wherein the middle part is positioned at the center of the edge part, and the middle part is connected with the edge part through an S-shaped suspension wire.
4. A silicon-based MEMS array speaker as claimed in claim 3 wherein: four S-shaped suspension wires are arranged.
5. A silicon-based MEMS array speaker as claimed in claim 3 wherein: the vibrating diaphragm and the suspension wires are made of silicon films.
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CN105282671A (en) * 2014-07-24 2016-01-27 北京卓锐微技术有限公司 Silicon capacitor microphone capable of working at high sound pressure level

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US9774959B2 (en) * 2015-03-25 2017-09-26 Dsp Group Ltd. Pico-speaker acoustic modulator

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CN105282671A (en) * 2014-07-24 2016-01-27 北京卓锐微技术有限公司 Silicon capacitor microphone capable of working at high sound pressure level

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