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Micro speaker based on mems ultrasonic transducer

A micro-speaker and ultrasonic technology, applied in the field of microelectronics, can solve the problems of low sound pressure sensitivity and low energy conversion efficiency of the speaker, and achieve the effects of high energy conversion efficiency, small envelope distortion, and high sound pressure sensitivity

Active Publication Date: 2022-07-12
ROFS MICROSYST TIANJIN CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the different mechanical and electrical characteristics of traditional speakers and micro MEMS speaker systems at different frequency points, it is difficult to achieve a flat frequency response in the entire audio frequency range (generally 20Hz to 20kHz). The typical sound pressure sensitivity curve of traditional micro MEMS speakers like figure 2 At the same time, because the actuator mechanical impedance of the speaker system is much greater than the mechanical impedance of the speaker air load, the sound pressure sensitivity and energy conversion efficiency of the speaker are low

Method used

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  • Micro speaker based on mems ultrasonic transducer
  • Micro speaker based on mems ultrasonic transducer
  • Micro speaker based on mems ultrasonic transducer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] like Figure 8a and Figure 8b shown, where Figure 8b The control circuit part in is omitted and not drawn. Figure 8b Among them, 001 denotes the substrate, and 002 denotes the MEMS ultrasonic transducer. The MEMS ultrasonic transducer 002 is controlled by discrete or approximately discrete electrical signals sent by the control circuit, and emits multiple ultrasonic pulses or wave envelope sound waves. These sound waves are superimposed in the time domain to form a synthetic sound wave envelope, approximating the target audio sound wave. The center frequency or resonant frequency of the MEMS ultrasonic transducer 002 is greater than 20 kHz. The FWHM of the pulse time domain is less than 20μs. The MEMS ultrasonic transducer 002 may be of a piezoelectric type, a capacitive type, an electromagnetic type, or the like. The material of the substrate 001 can be silicon, quartz, lithium niobate, lithium tantalate, gallium arsenide and the like. The MEMS ultrasonic tran...

Embodiment 2

[0047] like Figure 9a and Figure 9b shown, where Figure 9b The control circuit part in is omitted and not drawn. Figure 9b Among them, 001 denotes the substrate, and 002 denotes the MEMS ultrasonic transducer. A plurality of MEMS ultrasonic transducers 002 form an array, including but not limited to linear, 2-dimensional or 3-dimensional forms. Each MEMS ultrasonic transducer 002 acts as an element of the array. Each array element of the transducer array can be the same, which has the advantage of being easy to control and easy to manufacture; the array elements can also be different, for example, have different center frequencies, which can expand the bandwidth of the transducer array. The array element can be controlled digitally, that is, the amplitude is a fixed value when vibrating and sounding, and the size of the ultrasonic pulse signal can be adjusted by controlling the number of sounding array elements, thereby modulating the waveform of the audio sound wave; ...

Embodiment 3

[0049] like Figure 10a and Figure 10b shown, where Figure 10b The control circuit part in is omitted and not drawn. Figure 10b Among them, 001 represents the substrate, 002 represents the MEMS ultrasonic transducer, and 003 represents the impedance matching structure in the ultrasonic frequency band. The acoustic wave matching frequency band of the ultrasonic frequency band impedance matching structure 003 is in the ultrasonic frequency band. After adding the ultrasonic frequency band impedance matching structure 003 to the device, the output sound pressure of the sound wave is larger and the distortion is smaller. The impedance matching structure 003 in the ultrasonic frequency band may be a Helmholtz resonant cavity, a quarter-wavelength matching tube, an acoustic matching layer, etc., and the center frequency of the matching structure is in the ultrasonic frequency band.

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Abstract

The invention discloses a micro-speaker based on a micro-electromechanical system MEMS ultrasonic transducer, comprising single or multiple MEMS ultrasonic transducers, which are used to send out ultrasonic pulses or ultrasonic wave packet sequences according to an input electrical control signal; a control circuit, It is used to output discrete or approximately discrete electrical control signals, wherein the electrical control signals enable ultrasonic pulses or ultrasonic wave packet sequences to be superimposed in the time domain to form an acoustic envelope that approximates the target audio waveform. The micro-speaker based on the micro-electromechanical system MEMS ultrasonic transducer of the present invention has small final synthetic envelope distortion, high sound pressure sensitivity and high energy conversion efficiency.

Description

technical field [0001] The invention relates to the technical field of microelectronics, in particular to a micro speaker based on a MEMS ultrasonic transducer. Background technique [0002] Micro speakers are currently widely used in various miniaturized and miniaturized acoustic devices and electronic devices. The MEMS (Micro Electro Mechanical System) actuator is an important part of the above loudspeaker. Its core working principle is to use the electromechanical effect to realize the coupling and mutual conversion of acoustic energy (mechanical energy) - electrical energy on the micro scale. Specifically, through the piezoelectric effect, Capacitive electrostatic effect or electromagnetic effect converts electrical signals into vibrations of micro-mechanical structures, and generates air vibrations through the vibrations of mechanical structures, and then emits sound waves to generate sound. [0003] At present, no matter what kind of effect the micro MEMS speaker is b...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04R19/02H04R17/00H04R1/40
CPCH04R19/02H04R17/00H04R1/403H04R2201/003
Inventor 张孟伦庞慰
Owner ROFS MICROSYST TIANJIN CO LTD
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