# US 10,310,253 B2 · MEMS device with piezoelectric actuation, a projective MEMS system including the MEMS device and related control method

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,310,253 B2
- Document ID: US10310253B2
- Status: Granted
- Kind: B2
- Application number: 15/594,287
- Filed: 2017-05-12
- Published: 2018-06-28
- Granted: 2019-06-04
- Earliest claimed: 2016-12-28
- Assignees: STMicroelectronics S.r.l.
- Applicants: STMicroelectronics S.r.l.
- Inventors: Roberto Carminati; Domenico Giusti; Sonia Constantini
- Web page: https://patentgrep.com/patent/US10310253B2

## CPC

- G02B 26/0858: {the reflecting means being moved or deformed by piezoelectric means}
- B81B 3/0083: {Optical properties}
- G02B 26/105: {with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence)}
- H04N 9/3129: {scanning a light beam on the display screen (scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161)}
- B81B 2201/032: Bimorph and unimorph actuators, e.g. piezo and thermo
- B81B 2203/0118: Cantilevers
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A MEMS device includes a fixed structure and suspended structure including an internal structure and a first arm and a second arm. Each arm has a first end fixed to the fixed structure and a second end fixed to the internal structure. The ends are angularly arranged at a distance apart. Piezoelectric actuators mounted to the arms are driven so as to cause deformation of the arm and produce a rotation of the internal structure. In a resting condition, each of the first and second arms has a respective elongated portion with a respective concavity. The internal structure extends in part within the concavities of the elongated portions of the first and second arms.

## Claims

### Claim 1

A MEMS device, comprising:
a fixed structure delimiting a cavity;
a suspended structure which overlies the cavity, the suspended structure comprising:
an internal structure; and
a first arm and a second arm which are arranged around the internal structure and each of the first and second arms having a respective first end and a respective second end, said first ends being fixed to the fixed structure and being angularly arranged at a distance apart, said second ends being fixed to the internal structure and being angularly arranged at a distance apart and being angularly arranged in a same direction of rotation with respect to the corresponding first ends;
wherein the first arm has a first length and a first width, with the first length being greater than the first width, and wherein the first and second ends of the first arm are located at opposite ends of the first arm and separated by the first length in its entirety;
wherein the second arm has a second length and a second width, with the second length being greater than the second width, and wherein the first and second ends of the second arm are located at opposite ends of the second arm and separated by the second length in its entirety; and
wherein, in a resting condition, each of the first and second arms has a respective elongated portion with a respective concavity, said internal structure extending in part within the concavities of the elongated portions of the first and second arms; and
a plurality of piezoelectric actuators coupled to the first arm and the second arm and configured when driven to cause a deformation of the arm to which the piezoelectric actuator is coupled and a consequent rotation of the internal structure.

### Claim 2 (depends on 1)

The MEMS device according to claim 1, wherein, in the resting condition, said first and second arms extend around the internal structure on angular domains at least in part shifted and extending over an interval from about 65° to about 175°.

### Claim 3 (depends on 2)

The MEMS device according to claim 2, wherein the angular domains of the first and second arms are disjointed.

### Claim 4 (depends on 1)

The MEMS device according to claim 1, wherein the second ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 5 (depends on 1)

The MEMS device according to claim 1, wherein the first ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 6 (depends on 1)

The MEMS device according to claim 1, wherein, in the resting condition, the elongated portions of the first and second arms each form a single concavity.

### Claim 7 (depends on 6)

The MEMS device according to claim 6, wherein each of the first and second elongated portions has a respective line of symmetry having a radius of curvature that varies angularly in a monotonic way.

### Claim 8 (depends on 7)

The MEMS device according to claim 7, wherein a width of each of the first and second elongated portions decreases along a length of the line of symmetry from the first end to the second end.

### Claim 9 (depends on 1)

The MEMS device according to claim 1, wherein each of said piezoelectric actuators is arranged on the elongated portion of the arm to which it is coupled.

### Claim 10 (depends on 1)

The MEMS device according to claim 1, wherein said fixed structure and said internal structure are made at least in part of semiconductor material.

### Claim 11 (depends on 1)

A projective MEMS system, comprising:
a MEMS device according to claim 1;
a reflecting element coupled to the internal structure; and
an optical source configured to generate an optical beam that impinges on the reflecting element.

### Claim 12 (depends on 11)

A portable electronic apparatus, comprising:
a projective MEMS system according to claim 11.

### Claim 13 (depends on 12)

The apparatus according to claim 12, wherein said projective MEMS system is a stand-alone accessory having a package releasably coupled to a respective case of said portable electronic apparatus.

### Claim 14 (depends on 12)

The apparatus according to claim 12, wherein said projective MEMS system is formed in an integrated way within a case of said portable electronic apparatus.

### Claim 15

A The MEMS device, comprising:
a fixed structure delimiting a cavity;
a suspended structure which overlies the cavity, the suspended structure comprising:
an internal structure; and
a first arm and a second arm which are arranged around the internal structure and each of the first and second arms having a respective first end and a respective second end, said first ends being fixed to the fixed structure and being angularly arranged at a distance apart, said second ends being fixed to the internal structure and being angularly arranged at a distance apart and being angularly arranged in a same direction of rotation with respect to the corresponding first ends;
wherein, in a resting condition, the first and second arms respectively have first and second elongated portions having respective single concavities, said internal structure extending in part within the concavities of the first and second elongated portions; and
a plurality of piezoelectric actuators coupled to the first arm and the second arm and configured when driven to cause a deformation of the arm to which the piezoelectric actuator is coupled and a consequent rotation of the internal structure;
wherein the first and second elongated portions form, respectively, the first ends of the first and second arms;
wherein the first and second arms further comprise, respectively, a first terminal portion and a second terminal portion, which form, respectively, the second ends of the first and second arms; and
wherein the first and second terminal portions connect, respectively, to corresponding parts of the first and second elongated portions and form curved projections with single concavity, with concavity facing the internal structure, said curved projections projecting radially with respect to said parts of the first and second elongated portions.

### Claim 16 (depends on 15)

The MEMS device according to claim 15, wherein each of the first and second elongated portions has a respective line of symmetry having a radius of curvature that varies angularly in a monotonic way.

### Claim 17 (depends on 16)

The MEMS device according to claim 16, wherein a width of each of the first and second elongated portions decreases along a length of the line of symmetry from the first end to the second end.

### Claim 18 (depends on 15)

The MEMS device according to claim 15, wherein, in the resting condition, said first and second arms extend around the internal structure on angular domains at least in part shifted and extending over an interval from about 65° to about 175°.

### Claim 19 (depends on 18)

The MEMS device according to claim 18, wherein the angular domains of the first and second arms are disjointed.

### Claim 20 (depends on 15)

The MEMS device according to claim 15, wherein the second ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 21 (depends on 15)

The MEMS device according to claim 15, wherein the first ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 22

A MEMS device, comprising:
a fixed structure delimiting a cavity;
a suspended structure which overlies the cavity, the suspended structure comprising:
an internal structure; and
a first arm and a second arm which are arranged around the internal structure and each of the first and second arms having a respective first end and a respective second end, said first ends being fixed to the fixed structure and being angularly arranged at a distance apart, said second ends being fixed to the internal structure and being angularly arranged at a distance apart and being angularly arranged in a same direction of rotation with respect to the corresponding first ends;
wherein, in a resting condition, each of the first and second arms has a respective elongated portion with a respective concavity, said internal structure extending in part within the concavities of the elongated portions of the first and second arms; and
a plurality of piezoelectric actuators coupled to the first arm and the second arm and configured when driven to cause a deformation of the arm to which the piezoelectric actuator is coupled and a consequent rotation of the internal structure;
wherein each of said piezoelectric actuators is arranged on the elongated portion of the arm to which it is coupled; and
wherein the plurality of piezoelectric actuators comprises a first piezoelectric actuator, a second piezoelectric actuator, a third piezoelectric actuator, and a fourth piezoelectric actuator, the first and third piezoelectric actuators being arranged on the elongated portion of the first arm, the second and fourth piezoelectric actuators being arranged on the elongated portion of the second arm, in a way symmetrical, respectively, to the first and second piezoelectric actuators.

### Claim 23 (depends on 22)

The MEMS device according to claim 22, further comprising a drive circuit configured to apply to the first and fourth piezoelectric actuators a first control signal and to apply to the second and third piezoelectric actuators a second control signal, wherein the second control signal is phase-shifted by 180° with respect to the first control signal.

### Claim 24 (depends on 22)

The MEMS device according to claim 22, wherein, in the resting condition, said first and second arms extend around the internal structure on angular domains at least in part shifted and extending over an interval from about 65° to about 175°.

### Claim 25 (depends on 24)

The MEMS device according to claim 24, wherein the angular domains of the first and second arms are disjointed.

### Claim 26 (depends on 22)

The MEMS device according to claim 22, wherein the second ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 27 (depends on 22)

The MEMS device according to claim 22, wherein the first ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 28

A MEMS device, comprising:
a fixed structure delimiting a cavity;
a suspended structure which overlies the cavity, the suspended structure comprising:
an internal structure; and
a first arm and a second arm which are arranged around the internal structure and each of the first and second arms having a respective first end and a respective second end, said first ends being fixed to the fixed structure and being angularly arranged at a distance apart, said second ends being fixed to the internal structure and being angularly arranged at a distance apart and being angularly arranged in a same direction of rotation with respect to the corresponding first ends;
wherein, in a resting condition, each of the first and second arms has a respective elongated portion with a respective concavity, said internal structure extending in part within the concavities of the elongated portions of the first and second arms;
a plurality of piezoelectric actuators coupled to the first arm and the second arm and configured when driven to cause a deformation of the arm to which the piezoelectric actuator is coupled and a consequent rotation of the internal structure; and
a third arm and a fourth arm, each of third and fourth arms comprising a respective elongated portion having a concavity; and wherein, in the resting condition, the elongated portions of the first and second arms extend at least in part within the concavities formed, respectively, by the elongated portions of the third and fourth arms.

### Claim 29 (depends on 28)

The MEMS device according to claim 28, wherein, in the resting condition, said first and second arms extend around the internal structure on angular domains at least in part shifted and extending over an interval from about 65° to about 175°.

### Claim 30 (depends on 29)

The MEMS device according to claim 29, wherein the angular domains of the first and second arms are disjointed.

### Claim 31 (depends on 28)

The MEMS device according to claim 28, wherein the second ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 32 (depends on 28)

The MEMS device according to claim 28, wherein the first ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 33

A MEMS device, comprising:
a fixed structure delimiting a cavity;
a suspended structure which overlies the cavity, the suspended structure comprising:
an internal structure; and
a first arm and a second arm which are arranged around the internal structure and each of the first and second arms having a respective first end and a respective second end, said first ends being fixed to the fixed structure and being angularly arranged at a distance apart, said second ends being fixed to the internal structure and being angularly arranged at a distance apart and being angularly arranged in a same direction of rotation with respect to the corresponding first ends;
wherein, in a resting condition, each of the first and second arms has a respective elongated portion with a respective concavity, said internal structure extending in part within the concavities of the elongated portions of the first and second arms; and
a plurality of piezoelectric actuators coupled to the first arm and the second arm and configured when driven to cause a deformation of the arm to which the piezoelectric actuator is coupled and a consequent rotation of the internal structure;
wherein said internal structure comprises:
a nested structure; and
an outer frame of an annular shape, which surrounds the nested structure, and fixed to which are the second ends of the first and second arms; and
wherein the nested structure comprises:
an inner frame; and
a first secondary arm and a second secondary arm arranged around the inner frame and each of the first and second secondary arms having a respective first end and a respective second end, said first ends the first and second secondary arms being fixed to the outer frame and being angularly arranged at a distance apart, said second ends the first and second secondary arms being fixed to the inner frame and being angularly arranged at a distance apart and being arranged angularly in a same direction of rotation with respect to the corresponding first ends; and
a further plurality of piezoelectric actuators coupled to the first secondary arm and the second secondary arm and configured when driven to cause a deformation of the secondary arm to which the piezoelectric actuator is coupled and a consequent rotation of the inner frame;
wherein each of the first and second secondary arms comprises a respective elongated portion with a respective concavity; and wherein, in the resting condition, said inner frame extends in part within the concavities of the elongated portions of the first and second secondary arms.

### Claim 34 (depends on 33)

The MEMS device according to claim 33, wherein, in the resting condition, said first and second arms extend around the internal structure on angular domains at least in part shifted and extending over an interval from about 65° to about 175°.

### Claim 35 (depends on 34)

The MEMS device according to claim 34, wherein the angular domains of the first and second arms are disjointed.

### Claim 36 (depends on 33)

The MEMS device according to claim 33, wherein the second ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 37 (depends on 33)

The MEMS device according to claim 33, wherein the first ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 38

A MEMS device, comprising:
a fixed structure delimiting a cavity;
a suspended structure which overlies the cavity, the suspended structure comprising:
an internal structure; and
a first arm and a second arm which are arranged around the internal structure and each of the first and second arms having a respective first end and a respective second end, said first ends being fixed to the fixed structure and being angularly arranged at a distance apart, said second ends being fixed to the internal structure and being angularly arranged at a distance apart and being angularly arranged in a same direction of rotation with respect to the corresponding first ends;
wherein, in a resting condition, each of the first and second arms has a respective elongated portion with a respective concavity, said internal structure extending in part within the concavities of the elongated portions of the first and second arms;
a plurality of piezoelectric actuators coupled to the first arm and the second arm and configured when driven to cause a deformation of the arm to which the piezoelectric actuator is coupled and a consequent rotation of the internal structure; and
at least one first strain gauge and one second strain gauge, which are mechanically coupled, respectively, to the first and second arms, in symmetrical positions.

### Claim 39 (depends on 38)

The MEMS device according to claim 38, wherein, in the resting condition, said first and second arms extend around the internal structure on angular domains at least in part shifted and extending over an interval from about 65° to about 175°.

### Claim 40 (depends on 39)

The MEMS device according to claim 39, wherein the angular domains of the first and second arms are disjointed.

### Claim 41 (depends on 38)

The MEMS device according to claim 38, wherein the second ends of the first and second arms are arranged at an angular distance of 180°.

### Claim 42 (depends on 38)

The MEMS device according to claim 38, wherein the first ends of the first and second arms are arranged at an angular distance of 180°.