Gimbaled scanning micro-mirror apparatus

Abstract

A Micro-Electro-Mechanical Systems (MEMS) device for actuating a gimbaled element, the device comprising a symmetric electromagnetic actuator for actuating one degree of freedom (DOF) and a symmetric electrostatic actuator for actuating the second degree of freedom.

1 .- 22 . (canceled) 
     
     
         23 . The apparatus of  claim 27 , wherein the electromagnetic actuator has a linear electromechanical response, and
 wherein said apparatus is operative to monitor said electromagnetic actuator.   
     
     
         24 .- 25 . (canceled) 
     
     
         26 . A method according to  claim 29 , further comprising micro-electro-mechanically actuating an electromagnetically activated gimbaled mirror comprising said pivoting structural portion for two-dimensional optical scanning; and, the method also comprising:
 mounting an electrostatically actuated resonant mirror on an electromagnetically activated gimbal; and   providing a step-wave shaped input signal to said electromagnetically activated gimbal.   
     
     
         27 . Apparatus for generating controlled pivoting motion, sensing pivoting motion of a pivoting portion of a structural element, the apparatus comprising:
 a pivoting structural portion and first and second flexures, said first flexure having first and second ends,   
       said second flexure being formed of a piezo-resistive material and having at least first and second ends, at least one of which is fixed, 
       said first flexure being operative to twist along at least a first axis, said second flexure being configured and oriented to define an elongate projection about along a second axis perpendicular to said first axis, wherein said pivoting portion is disposed at and fixed relative to said first end of the first flexure and wherein said second end of the first flexure is attached to said second flexure, flexure;
 a piezo-resistive response detector operative for detecting at least one characteristic of a piezo-resistive response of at least a portion of the second flexure to pivoting motion of said pivoting structural portion; 
 an electromagnetic actuator for providing a first angular degree of freedom (DOF) of rotation of said structural portion about said first axis; 
 
       and 
       a pivoting motion generator operative to generate said pivoting motion based on at least one characteristic of said pivoting motion computed from said at least one characteristic of said piezo-resistive response
 a processor operative for computing at least one characteristic of said pivoting motion from said at least one characteristic of said piezo-resistive response. 
 
     
     
         28 . (canceled) 
     
     
         29 . A method for sensing pivoting motion of a pivoting portion of a structural element, the method comprising:
 providing a pivoting structural portion and first and second flexures, said first flexure having first and second ends, said second flexure being formed of a piezo-resistive material and having at least first and second ends, at least one of which is fixed, said first flexure being operative to twist along at least a first axis, said second flexure being configured and oriented to define an elongate projection about along a second axis perpendicular to said first axis, wherein said pivoting portion is disposed at and fixed relative to said first end of the first flexure and wherein said second end of the first flexure is attached to said second flexure, flexure;
 detecting at least one characteristic of a piezo-resistive response of at least a portion of the second flexure to pivoting motion of said pivoting structural portion; 
 using an electromagnetic actuator to provide a first angular degree of freedom (DOF) of rotation of said structural portion about said first axis; 
   and
 computing at least one characteristic of said pivoting motion from said at least one characteristic of said piezo-resistive response. 
   
     
     
         30 . A method according to  claim 29  wherein said detecting comprises measuring the piezo-resistive response at a location along the second flexure which is removed at a non-zero distance from said first axis. 
     
     
         31 . A method according to  claim 29 , further and also comprising:
 providing a pivoting motion generator operative to generate said pivoting motion; and   controlling said pivoting motion generator using said characteristic of said pivoting motion generated in said computing step.   
     
     
         32 . A method according to  claim 29  wherein at least one of said flexures is formed of silicon. 
     
     
         33 . A method according to  claim 32  wherein said silicon comprises single crystal silicon. 
     
     
         34 - 47 . (canceled) 
     
     
         48 . Apparatus according to  claim 27 , further comprising
 A micro-electro-mechanical direct current motor apparatus to repeatedly impart instances of angular motion to an element, wherein said instances of angular motion are temporally interspersed with a sequence of stationary intervals during which said element is stationary, the apparatus comprising:   a stator;   
       wherein said portion comprises a rotor pivoting about said first axis along a route having a length of less than several dozen microns, the rotor comprising a flexure element fixedly associated with the stator, said flexure element comprising a magnetic portion;
 wherein the stator comprises: 
 
       a ferro-magnetic core having a curved configuration which is almost closed other than thereby to define an air-gap closing the curved configuration and having a width exceeding said route length by only a few microns; and 
       a conductive coil wrapped around at least a portion of the almost closed curved configuration of the ferro-magnetic core.
 and wherein at least the magnetic portion of the flexure element is disposed within said air-gap, thereby to generate a first magnetic field in the air-gap; 
 
       and wherein an alternating current flows through the conductive coil thereby to generate a second, alternating magnetic field within said air gap; 
       wherein said magnetic portion is oriented such that the first magnetic field generated thereby in the air-gap, when interacting with the second, alternating magnetic field within the air-gap, generates a moment about said axis. 
     
     
         49 . Apparatus according to  claim 48  wherein the rotor comprises a gimbal. 
     
     
         50 . Apparatus according to  claim 49  and also comprising wherein the structural portion comprises a mirror mounted on said gimbal. 
     
     
         51 . Apparatus according to  claim 27  wherein said structural portion is at least partly formed of silicon. 
     
     
         52 . Apparatus according to  claim 27  wherein said structural portion comprises a gimbal apparatus. 
     
     
         53 . Apparatus according to  claim 52  wherein said structural portion also comprises a mirror apparatus mounted on said gimbal apparatus. 
     
     
         54 . Apparatus according to  claim 53  wherein the mirror apparatus has toothed edges and the gimbal has toothed edges interlaced with the toothed edges of the mirror apparatus. 
     
     
         55 .- 63 . (canceled) 
     
     
         64 . Apparatus according to  claim 27  and also comprising a pivoting motion generator operative to generate said pivoting motion based on at least one output from said processor. 
     
     
         65 . Apparatus according to  claim 48  wherein at least the magnetic portion of the flexure element is disposed within said air-gap, thereby to generate a first magnetic field in the air-gap. 
     
     
         66 . Apparatus according to  claim 65  wherein an alternating current flows through the conductive coil thereby to generate a second, alternating magnetic field within said air gap. 
     
     
         67 . Apparatus according to  claim 66  wherein said magnetic portion is oriented such that the first magnetic field generated thereby in the air-gap, when interacting with the second, alternating magnetic field within the air-gap, generates a moment about said axis 
     
     
         68 . Apparatus for sensing pivoting motion, the apparatus comprising:
 a pivoting structural component that is free to rotate about an internal axis;   a set of two axes perpendicular to the internal axis and including an external axis formed of a Piezo resistive material;   a frame connected to said set of two axes and encircling the pivoting structural component and said internal axis;   a piezo-resistive response detector operative for detecting at least one characteristic of a piezo-resistive response to pivoting motion of the frame and the external axis; and   a processor operative for computing at least one characteristic of said pivoting motion from said at least one characteristic of said piezo-resistive response.