# US 2023/0054412 A1 · Active piezoelectric sheet with piezoelectric microstructures

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- Number: US 2023/0054412 A1
- Document ID: US20230054412A1
- Status: Published application
- Kind: A1
- Application number: 17/508,133
- Filed: 2021-10-22
- Published: 2023-02-23
- Earliest claimed: 2021-08-20
- Assignees: Massachusetts Institute of Technology
- Applicants: Massachusetts Institute of Technology
- Inventors: Jinchi HAN; Jeffrey H. LANG; Vladimir BULOVIC
- Web page: https://patentgrep.com/patent/US20230054412A1

## CPC

- H04R 1/40: by combining a number of identical transducers {(specially adapted for hearing aids H04R25/405)}
- H04R 17/025: {using a piezoelectric polymer}
- B06B 1/0622: {on one surface}
- B06B 1/0688: {with foil-type piezoelectric elements, e.g. PVDF}
- G10K 9/125: with a plurality of active elements
- H04R 1/403: {loud-speakers}
- H04R 1/406: {microphones}
- H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)}
- H04R 7/127: {dome-shaped}
- H10N 30/084: by moulding or extrusion
- H10N 30/883: {Additional insulation means preventing electrical, physical or chemical damage, e.g. protective coatings}
- G10K 11/34: using electrical steering of transducer arrays, e.g. beam steering {(constructional aspects B06B1/0607, B06B1/085)}
- G10K 2200/10: Beamforming, e.g. time reversal, phase conjugation or similar
- H04R 2201/401: 2D or 3D arrays of transducers
- H04R 2203/12: Beamforming aspects for stereophonic sound reproduction with loudspeaker arrays
- H04R 2400/01: Transducers used as a loudspeaker to generate sound aswell as a microphone to detect sound
- H10N 39/00: Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R)
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

An active acoustic system includes a thin-film sheet having an array of piezoelectric microstructures embossed in the film. Each piezoelectric microstructure may act as a speaker and/or a microphone. A control circuit is configured to individually address the piezoelectric microstructures to provide a separate voltage signal to, or receive a separate voltage signal from, each piezoelectric microstructure.

## Claims

### Claim 1

An active acoustic system comprising:
a piezoelectric substrate comprising an array of piezoelectric microstructures, each piezoelectric microstructure having at least two terminals; and
a control circuit having output terminals coupled to at least one terminal of each piezoelectric microstructure, the control circuit configured to address one or more piezoelectric microstructures in the array of piezoelectric microstructure to provide one or more voltage signals to the piezoelectric microstructures to control the piezoelectric microstructures in the array of piezoelectric microstructures.

### Claim 2 (depends on 1)

The active acoustic system of claim 1 further comprising a protective layer disposed on one side of the substrate, the protective layer comprising an array of through-holes, each through-hole in the array of through-holes positioned over a piezoelectric microstructure of the array of piezoelectric microstructures.

### Claim 3 (depends on 1)

The active acoustic system of claim 1 wherein the substrate comprises protrusions that form the piezoelectric microstructures.

### Claim 4 (depends on 3)

The active acoustic system of claim 3 wherein at least one of the protrusions is dome-shaped.

### Claim 5 (depends on 3)

The active acoustic system of claim 3 wherein at least one of the protrusions has a concave surface.

### Claim 6 (depends on 1)

The active acoustic system of claim 1 comprising an encapsulation layer disposed on one side of the substrate.

### Claim 7 (depends on 1)

The active acoustic system of claim 1 wherein the control circuit is configured to drive an AC voltage across at least one of the piezoelectric microstructures to cause the piezoelectric microstructures to produce an acoustic sound.

### Claim 8 (depends on 7)

The active acoustic system of claim 7 wherein the acoustic sound is ultrasonic.

### Claim 9 (depends on 1)

The active acoustic system of claim 1 wherein the control circuit is configured to receive a voltage signal from at least one of the piezoelectric microstructures to detect an acoustic sound from an acoustic source in an external environment.

### Claim 10 (depends on 9)

The active acoustic system of claim 9 wherein the control circuit is configured to use beamforming techniques to detect a location of the acoustic source.

### Claim 11 (depends on 1)

The active acoustic system of claim 1 wherein the substrate is flexible.

### Claim 12 (depends on 1)

The active acoustic system of claim 1 wherein the substrate is rigid.

### Claim 13 (depends on 1)

The active acoustic system of claim 1 wherein the substrate is formed from polyvinylidene fluoride (PVDF), a piezoelectric polymer, a piezoelectric composite, a piezoelectric ceramic, and/or a piezoelectric single-crystal material.

### Claim 14 (depends on 1)

The active acoustic system of claim 1 wherein the piezoelectric substrate comprises two or more conductive traces, each coupled to one or more piezoelectric microstructures.

### Claim 15 (depends on 14)

The active acoustic system of claim 14 wherein the control circuit is configured to address individual piezoelectric microstructures by activating at least two of the conductive traces.

### Claim 16 (depends on 15)

The active acoustic system of claim 15 wherein the control circuit is configured to address a block of piezoelectric microstructures by activating at least two of the conductive traces.

### Claim 17

An active acoustic surface comprising:
a substrate having an array of piezoelectric microstructures, each piezoelectric microstructure having at least one electrical terminal for coupling to a driver circuit; and
a protective layer disposed on one side of the substrate, the protective layer comprising an array of through holes, each through hole in the array of through holes positioned over a piezoelectric microstructure of the array of piezoelectric microstructures.

### Claim 18 (depends on 17)

The active acoustic surface of claim 17 wherein the substrate comprises protrusions that form the piezoelectric microstructures.

### Claim 19 (depends on 18)

The active acoustic surface of claim 18 wherein at least one of the protrusions is dome-shaped.

### Claim 20 (depends on 18)

The active acoustic surface of claim 18 wherein at least one of the protrusions has a concave surface.

### Claim 21 (depends on 18)

The active acoustic surface of claim 18 comprising an encapsulation layer disposed on one side of the substrate.

### Claim 22 (depends on 17)

The active acoustic surface of claim 17 wherein at least one piezoelectric microstructure is coupled to the driver circuit, and the driver circuit is configured to drive an AC voltage across at least one of the piezoelectric microstructures to cause the piezoelectric microstructures to produce an acoustic sound and/or receive a voltage signal from the piezoelectric microstructure to representing an acoustic sound detected by the piezoelectric microstructure.

### Claim 23 (depends on 17)

The active acoustic surface of claim 17 wherein the substrate is flexible.

### Claim 24 (depends on 17)

The active acoustic surface of claim 17 wherein the substrate is rigid.

### Claim 25 (depends on 17)

The active acoustic surface of claim 17 wherein the substrate is formed from polyvinylidene fluoride (PVDF), a piezoelectric polymer, a piezoelectric composite, a piezoelectric ceramic, and/or a piezoelectric single-crystal material.