MEMS Micro-Mirror Rotation Control via Resistance Feedback
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Solution Overview
Problem
The precision control of micro-mirrors in light steering systems, such as LiDAR modules, is limited due to variations in fabrication processes and non-idealities, leading to non-uniform rotation angles and reduced imaging/ranging resolution.
Innovation Solution
An adaptive control system that measures the electrical resistance of connection structures within micro-mirror assemblies to determine actual rotation angles and adjusts control signals to achieve target angles, improving precision and uniformity through feedback loops and actuator adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fabrication process variations are reduced, then manufacturing precision of micro-mirror assemblies is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a feedback control system where the controller measures the actual rotation angle of each micro-mirror and adjusts the drive signal accordingly. The controller determines a first signal based on a target rotation angle, applies it to the actuator, measures the actual rotation angle, determines a second signal based on the relationship between target and actual angles, and transmits the second signal to achieve the target rotation angle. This closed-loop feedback mechanism compensates for fabrication variations without requiring higher manufacturing precision.
2Manufacturing precision
If fabrication process variations are reduced, then manufacturing precision of micro-mirror assemblies is improved, but production cost increases
Solution Approach 1:
The feedback control system allows the use of standard fabrication processes with inherent variations while achieving uniform micro-mirror rotation through software-based compensation. The controller measures actual rotation angles and adjusts drive signals to achieve target angles, eliminating the need for expensive precision fabrication processes or individual calibration of each micro-mirror assembly.
Solution Approach 2:
The system changes the control parameter (drive signal characteristics) based on the measured actual rotation angle to achieve the target rotation angle. By adjusting electrical parameters rather than mechanical dimensions, the system avoids costly precision manufacturing while achieving the desired rotational uniformity.
3Measurement precision
If control precision of micro-mirrors is improved, then imaging and ranging resolution is improved, but device complexity increases
Solution Approach 1:
The controller uses feedback from the measured actual rotation angle to adjust the drive signal. By determining a second signal based on the relationship between the target rotation angle and the actual rotation angle, the system achieves precise rotation angle control through a relatively simple feedback loop that compensates for non-idealities without requiring complex control mechanisms.
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
Enhances the control precision and uniformity of micro-mirror rotations, reducing light dispersion and improving the imaging and ranging resolution in light steering applications.
Implementation Method 1
the measurement circuit being configured to measure an electrical resistance of at least one of the first connection structure or the second connection structure
Implementation Method 2
the micro-mirror can be rotated by a rotation angle to reflect (and steer) light from a light source towards a target direction
Data Source
AI summary
In one example, a semiconductor integrated circuit is provided. The semiconductor integrated circuit includes a microelectromechanical system (MEMS), a substrate on which the MEMS is formed, and a controller, the MEMS including one or more micro-mirror assemblies, each micro-mirror assembly including: a micro-mirror comprising a first connection structure and a second connection structure, the first connection structure being connected to the substrate at a first pivot point, the second connection structure being connected to the substrate at a second pivot point; an actuator configured to rotate the micro-mirror; and a measurement circuit configured to measure an electrical resistance of at least one of the first connection structure or the second connection structure. The controller is configured to control the actuator of each of the one or more micro-mirror assemblies based on the electrical resistance measurements from the measurement circuits.