Mems device and a method of using the same

Abstract

A method of using a MEMS gyroscope is disclosed herein, wherein the MEMS gyroscope comprised a magnetic sensing mechanism. A magnetic field is generated by a magnetic source, and is detected by a magnetic sensor. The magnetic field varies at the location of the magnetic sensor; and the variation of the magnetic field is associated with the movement of the proof-mass of the MEMS gyroscope. By detecting the variation of the magnetic field, the movement and thus the target angular velocity can be measured.

We claim: 
     
         1 . A method of measuring an angular velocity by using a MEMS gyroscope, the method comprising:
 moving a proof-mass of the MEMS gyroscope in a driving mode using a magnetic driving mechanism;   measuring a background magnetic signal using a reference magnetic sensor;   storing the measurement from the reference magnetic sensor;   generating a target magnetic field that is associated with a movement of a proof-mass of the MEMS gyroscope;   activating a signal magnetic sensor for measuring the background magnetic signal and the generated target magnetic signal;   comparing the measurements from the reference and signal magnetic sensors so as to obtain the target magnetic field; and   extracting the angular velocity from the target magnetic field.   
     
     
         2 . The method of  claim 1 , wherein the step of measuring the background magnetic signal comprises:
 raising the temperature of the reference magnetic sensor above a blocking temperature of the reference sensor such that the reference sensor is capable of detecting the background magnetic field signal.   
     
     
         3 . The method of  claim 2 , wherein the reference sensor comprises a free layer for detecting the background magnetic field signal, wherein the free layer is magnetically pinned by an antiferromagnetic layer when the temperature is blow the blocking temperature. 
     
     
         4 . The method of  claim 2 , wherein the step of generating the magnetic field comprises:
 driving a current through a conductive wire so as to generating the magnetic field.   
     
     
         5 . The method of  claim 4 , wherein the magnetic sensor comprises a spin-valve structure. 
     
     
         6 . The method of  claim 4 , wherein the magnetic sensor comprises a tunneling-magneto-resistor structure. 
     
     
         7 . A method of detecting a target angular velocity, comprising:
 providing a MEMS gyroscope that comprises a movable proof-mass, a magnetic source, and a magnetic sensor, wherein the proof-mass is capable of moving in response to the target angular velocity under the Coriolis effect, and wherein the magnetic source is capable of generating a magnetic field that varies with the movement of the proof-mass, and wherein the magnetic sensor is capable of detecting the magnetic field from the magnetic source;   detecting a background magnetic signal using a reference sensor;   storing the detected background magnetic signal by the reference sensor;   moving a proof-mass of the MEMS gyroscope in a driving mode using a magnetic driving mechanism;   generating the magnetic field by the magnetic source;   detecting a variation of the magnetic field by the magnetic sensor; and   extracting the angular velocity from the variation of the magnetic field.   
     
     
         8 . The method of  claim 7 , wherein the step of measuring the background magnetic signal comprises:
 raising the temperature of the reference magnetic sensor above a blocking temperature of the reference sensor such that the reference sensor is capable of detecting the background magnetic field signal.   
     
     
         9 . The method of  claim 8 , wherein the reference sensor comprises a free layer for detecting the background magnetic field signal, wherein the free layer is magnetically pinned by an antiferromagnetic layer when the temperature is blow the blocking temperature. 
     
     
         10 . The method of  claim 8 , wherein the step of generating the magnetic field comprises:
 driving a current through a conductive wire so as to generating the magnetic field.   
     
     
         11 . The method of  claim 8 , wherein the magnetic sensor comprises a spin-valve structure. 
     
     
         12 . The method of  claim 8 , wherein the magnetic sensor comprises a tunneling-magneto-resistor structure.