US 6,275,325 B1 · Thermally activated microelectromechanical systems actuator

Abstract

A microelectrical mechanical system (MEMS) actuator having coupled members that undergo different amounts of thermal expansion is disclosed for moving micromechanical objects, such as a mirror, toward and away from a surface or a planar substrate. The actuator members are a first elongate member and a second elongate member that are coupled together at their respective distal ends. At their respective proximal ends, the members are mounted onto discrete electrical paths formed on the substrate. Thus, current applied to one electrical pathway is conducted along the first member to the second member, and to the other electrical path. The first member includes a metal conductor that provides a reduced resistivity for electrical current. Thus, when current is applied to the actuator, the second member generates more thermal energy due to its increased resistance and thereby thermally expands a greater amount than the first member. By thermally expanding the second member more than the first member, the distal ends of the first and second members are constrained to move away from the substrate. This movement is used to move a mirror out of the plane of the planar substrate. To accommodate the changing distance and angles between the actuator and the mirror, a sliding hinge is located between the actuator and the mirror.

Claims24

Dependent claims

A microelectrical mechanical actuator, comprising:

(a) a planar substrate;
(b) a first member having first and second ends and wherein the first end of the first member is coupled to the substrate and the first member has a first electrical conductivity;
(c) a second member having first and second ends and wherein the first end of the second member is coupled to the substrate and the second ends of the first and second member are coupled together and the second member has a second electrical conductivity;
and
(d) wherein electrical current is conducted along the first member and the second member causing thermal expansion of the first and second members and the first and second members expand at different rates thereby causing the second ends of the members to move away from the substrate.

2 more elements

A microelectrical mechanical actuator, comprising:

(a) a planar substrate;
(b) a first member having first and second ends and a first elongate portion located there between, wherein the first end is fixedly coupled to the substrate and the first elongate portion is arranged to extend over the substrate such that the longitudinal axis of the first elongate portion is substantially parallel to the plane of the substrate and is located a first distance above the substrate;
and
(c) a second member having first and second ends and a second elongate portion located there between, wherein the first end is fixedly coupled to the substrate and the second elongate portion is arranged to extend over the substrate such that the longitudinal axis of the second elongate portion is substantially parallel to the plane of the substrate and is located a second distance above the substrate, and the second ends of the first and second members are coupled so that electrical current can flow through the first member to and through the second member;
(d) wherein the first distance of the first elongate portion is not equal to the second distance of the second elongate portion;
and
(e) wherein Joule heating occurs when electrical current flows through the first and second members and the first member undergoes a first amount of thermal expansion, and the second member undergoes a second amount of thermal expansion that is not equal to the first amount of thermal expansion of the first member, so that the coupled second ends of the first and second members move relative to the substrate.

4 more elements

An actuator device, comprising:

(a) a planar substrate;
(b) a first and a second actuator;
and
(c) a mirror having a first margin coupled to the first actuator and a second margin coupled to the second actuator so as to locate a first portion of the mirror at a first distance from the substrate;
(d) wherein the first and second actuators each include first and second members having first ends that are fixedly arranged on the substrate and second ends that are electrically and fixedly coupled, whereby current can be selectively applied to the first or second actuator to cause thermal expansion of the actuator members that moves the first portion of the mirror from the first distance to a second distance from the substrate and the first and second distances are not equal.

2 more elements

Dependencies are inferred from the claim text.

Thermally activated microelectromechanical systems actuator

Life of this patent

Thermally activated microelectromechanical systems actuator

Life of this patent

Abstract

Claims24