Scanning micromirror with improved performance and related electronic device

Patent metadata

Field	Value
Publication number	US-9678333-B2
Application number	US-201514702833-A
Country	US
Kind code	B2
Filing date	May 4, 2015
Priority date	May 7, 2014
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A micromechanical mirror includes a mobile mass carrying a mirror element and provided in a body including semiconductor material. A driving structure is coupled to the mobile mass to cause a scanning movement thereof. The driving structure is configured to generate a combination of a two or more sinusoidal resonant modes in the micromechanical mirror at respective resonant frequencies. This combination approximates a scanning pattern of the mobile mass defined by a linear function which may, in particular, be a triangular shaped function.

First claim

What is claimed is:

1. A micromechanical mirror, comprising:
a mobile mass carrying a mirror element and provided in a body including semiconductor material; and
a driving structure coupled to the mobile mass and configured to cause a scanning movement thereof;
wherein the driving structure is configured to generate a combination of a plurality of sinusoidal resonant modes in the micromechanical mirror at respective plural resonant frequencies, said combination approximating a scanning pattern of said mobile mass defined by a linear function;
wherein the driving structure includes a plurality of distinct driving groups corresponding in number to the plurality of sinusoidal resonant modes;
wherein each of said driving groups includes:
a respective pair of driving arms arranged on opposite sides of the mobile mass with respect to a rotation axis thereof and carrying mobile electrodes;
a respective fixed portion carrying fixed electrodes in a position facing and combfingered with the mobile electrodes; and
elastic elements coupled between the driving arms.

2. The micromechanical mirror according to claim 1 , wherein the linear function is a triangular shaped function.

3. The micromechanical mirror according to claim 1 , wherein the plurality of sinusoidal resonant modes correspond to respective harmonics of a frequency transform of the linear function of said scanning pattern.

4. The micromechanical mirror according to claim 1 , wherein said plurality of sinusoidal resonant modes is equal to two or three, and said plurality of sinusoidal resonant modes correspond to the first two or three harmonics of a series Fourier transform of the linear function of said scanning pattern.

5. The micromechanical mirror according to claim 1 , wherein the elastic elements are of a torsional type.

6. The micromechanical mirror according to claim 1 , wherein the pair driving arms of a first driving group are integrally coupled to the mobile mass; and wherein the pair of driving arms of a second driving group are coupled to anchorages fixed to the body through respective elastic elements.

7. The micromechanical mirror according to claim 1 , wherein the fixed portions carry first contact pads for biasing of the respective fixed electrodes at a respective one of different driving signals.

8. The micromechanical mirror according to claim 7 , wherein the driving signals are sinusoidal signals at the resonant frequencies of the respective resonant modes.

9. The micromechanical mirror according to claim 1 , wherein mechanical parameters of the driving arms and elastic elements of the driving groups define the resonant frequencies of said resonant modes.

10. The micromechanical mirror according to claim 9 , wherein said mechanical parameters comprise: a spring constant of the elastic elements and a moment of inertia of the driving arms.

Assignees

• St Microelectronics Int Nv

Inventors

• Goren Nir

Classifications

• G02B26/0833 Primary

  the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B) · CPC title

• G02B26/0841 Primary

  the reflecting element being moved or deformed by electrostatic means · CPC title

• G02B26/10

  Scanning systems · CPC title

• B81B3/0045

  Improve properties related to angular swinging, e.g. control resonance frequency · CPC title

• G02B26/105

  with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence) · CPC title