Gimbaled scanning micro-mirror apparatus
First Claim
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1. A micro-electro-mechanical device for actuating a gimbaled element for two-dimensional optical scanning, the device comprising:
- a. an electro-magnetically activated gimbal operative for electro-magnetically driven rotation about a first axis in accordance with a step-wave shaped input signal;
b. a mirror mounted on said gimbal and operative for electro-statically driven rotation about a second axis, thereby defining two degrees of freedom of motion for said mirror, the mirror comprising at least one rotor electrode and the gimbal comprising at least one stator electrode, where the rotor and stator electrode/s together comprise an electro-static comb-drive and both include respective coplanar portions both manufactured in a single process from a single Si layer, wherein an electrical potential difference between top surfaces of the rotor and stator electrodes is created by fringing fields of electro-static force therebetween causing the rotor electrode/s to rotate about its/their axis; and
c. a mirror motion feedback control loop including;
i. at least one MEMS motor driver clocked by a clock signal and operative to drive the mirror to resonate along the second axis with an actuation frequency, and wherein the gimbal'"'"'s orientation follows said step-wave shaped input signal; and
ii. said electro-static comb-drive which acts as a frequency sensor which is operative;
to sense the resonance frequency of the mirror which due to said electro-statically driven rotation generates a varying capacitance signal according to which said actuation frequency is set to match said resonance frequency andto set said clock signal to the resonance frequency.
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Abstract
Provided is a Micro-Electro-Mechanical Systems (MEMS) device for actuating a gimbaled element, the device including a symmetric electromagnetic actuator for actuating one degree of freedom (DOF) and a symmetric electrostatic actuator for actuating the second degree of freedom.
27 Citations
17 Claims
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1. A micro-electro-mechanical device for actuating a gimbaled element for two-dimensional optical scanning, the device comprising:
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a. an electro-magnetically activated gimbal operative for electro-magnetically driven rotation about a first axis in accordance with a step-wave shaped input signal; b. a mirror mounted on said gimbal and operative for electro-statically driven rotation about a second axis, thereby defining two degrees of freedom of motion for said mirror, the mirror comprising at least one rotor electrode and the gimbal comprising at least one stator electrode, where the rotor and stator electrode/s together comprise an electro-static comb-drive and both include respective coplanar portions both manufactured in a single process from a single Si layer, wherein an electrical potential difference between top surfaces of the rotor and stator electrodes is created by fringing fields of electro-static force therebetween causing the rotor electrode/s to rotate about its/their axis; and c. a mirror motion feedback control loop including; i. at least one MEMS motor driver clocked by a clock signal and operative to drive the mirror to resonate along the second axis with an actuation frequency, and wherein the gimbal'"'"'s orientation follows said step-wave shaped input signal; and ii. said electro-static comb-drive which acts as a frequency sensor which is operative; to sense the resonance frequency of the mirror which due to said electro-statically driven rotation generates a varying capacitance signal according to which said actuation frequency is set to match said resonance frequency and to set said clock signal to the resonance frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification