Piezoelectric MEMS Mirror Circuit with Time-Shared Sensing
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Solution Overview
Problem
MEMS devices, such as laser beam scanners, require dedicated sensors for feedback to adjust the scan pattern, which consume on-die space and increase manufacturing costs, necessitating a design that provides sensing functionality while minimizing space and cost.
Innovation Solution
A microelectromechanical (MEMS) device utilizing a piezoelectric actuator that functions as both an actuator and sensor, with control circuitry that includes mirror drive and sense circuitry, and a multiplexing circuit to share time between driving and sensing, allowing the piezoelectric actuator to deflect the rotor during one portion of the movement cycle and provide sense signals during another, using current-to-voltage conversion for feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated sensors are used for feedback, then measurement precision is improved, but device complexity and area increase
Solution Approach 1:
The piezoelectric actuator is designed to perform dual functions: serving as both the actuator that deflects the mirror and as the sensor that provides feedback on its position. The same piezoelectric material and electrical connections are used for both actuation and sensing, eliminating the need for separate dedicated sensors and reducing device complexity while maintaining measurement precision
Solution Approach 2:
The patent combines the actuator and sensor functions into a single integrated component. The piezoelectric actuator's electrical connections are shared between drive circuitry and sense circuitry, merging previously separate functional elements into one unified structure that reduces overall device complexity and component count
2Measurement precision
If dedicated sensors are used for feedback, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The piezoelectric actuator serves dual purposes as both actuator and sensor, eliminating the need to manufacture and assemble separate dedicated sensors. This multi-functionality reduces component count and assembly steps, thereby lowering manufacturing costs while maintaining the necessary feedback capability for scan pattern accuracy
Solution Approach 2:
By merging the actuator and sensor functions into a single piezoelectric component with shared electrical connections, the patent simplifies the manufacturing process. Fewer discrete components mean reduced material costs, assembly costs, and testing requirements, making the device more cost-effective to produce
3Measurement precision
If dedicated sensors are used for feedback, then measurement precision is improved, but area of stationary object increases
Solution Approach 1:
The piezoelectric actuator is designed to perform dual functions: serving as both the actuator that deflects the mirror and as the sensor that provides feedback on its position. The same piezoelectric material and electrical connections are used for both actuation and sensing, eliminating the need for separate dedicated sensors and reducing device complexity while maintaining measurement precision
Solution Approach 2:
The patent combines the actuator and sensor functions into a single integrated component. The piezoelectric actuator's electrical connections are shared between drive circuitry and sense circuitry, merging previously separate functional elements into one unified structure that reduces overall device complexity and component count
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate adjustment of the scan pattern without dedicated sensors, saving space and reducing costs by utilizing the same piezoelectric actuator for both functions, while maintaining the necessary feedback for optimal performance.
Implementation Method 1
A microelectromechanical (MEMS) device utilizes a piezoelectric actuator that functions as both an actuator and sensor
Implementation Method 2
the same piezoelectric actuator for both functions
Data Source
AI summary
Disclosed herein is a microelectromechanical (MEMS) device, including a rotor and a first piezoelectric actuator mechanically coupled to the rotor. The first piezoelectric actuator is electrically coupled between a first signal node and a common voltage node. A second piezoelectric actuator is mechanically coupled to the rotor, and is electrically coupled between a second signal node and the common voltage node. Control circuitry includes a drive circuit configured to drive the first and second piezoelectric actuators, a sense circuit configured to process sense signals generated by the first and second pizeoelectric actuators, and a multiplexing circuit. The multiplexing circuit is configured to alternate between connecting the drive circuit to the first piezoelectric actuator while connecting the sense circuit to the second piezoelectric actuator, and connecting the drive circuit to the second piezoelectric actuator while connecting the sense circuit to the first piezoelectric actuator.