Biased Substrate Capacitance Sensing in LiDAR Mirror Assemblies
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Solution Overview
Problem
Existing LiDAR systems face accuracy issues in capacitance sensing due to parasitic capacitance, which affects the precise control of optical beam directions, hindering the performance in applications like autonomous driving and high-definition map surveys.
Innovation Solution
A mirror assembly with a biased substrate is introduced to reduce the effect of parasitic capacitance by applying a bias voltage, allowing the substrate to operate in accumulation or depletion mode, thereby stabilizing parasitic capacitance and improving capacitance sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance sensing is used to control mirror position in LiDAR systems, then the system can achieve precise optical beam direction control, but parasitic capacitance degrades the sensing accuracy
Solution Approach 1:
The patent applies a bias voltage to the substrate to change its electrical state, operating it in accumulation or depletion mode. This parameter change stabilizes the parasitic capacitance value, allowing the capacitance sensing system to accurately measure mirror position despite the presence of parasitic capacitance. The bias voltage transforms the substrate's electrical characteristics to minimize its harmful capacitive effects.
2Measurement precision
If a bias voltage is applied to the substrate, then parasitic capacitance is stabilized and sensing accuracy improves, but additional electrical components and complexity are introduced
Solution Approach 1:
The substrate serves multiple functions: it provides mechanical support for the mirror structure and simultaneously acts as an electrical element whose capacitance can be controlled and measured. By applying bias voltage to the substrate, the same component performs both structural and electrical sensing functions, reducing the need for separate dedicated elements and minimizing overall system complexity.
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
This solution enhances the accuracy of capacitance sensing, leading to improved controllability and performance of the optical sensing system with increased scanning accuracy, precision, and speed, suitable for applications in autonomous driving and high-definition map surveys.
Implementation Method 1
the accuracy of capacitance sensing is hindered by parasitic capacitance
Implementation Method 2
a bias voltage source electrically coupled to the substrate to bias the substrate with a bias voltage
Implementation Method 3
The oscillation of the mirror can be controlled based on sensing changes in capacitance caused by the movement of the mirror
Implementation Method 4
Existing LiDAR systems generally use electrostatic-, piezoelectric-, or magnetic-based actuators
Data Source
AI summary
Embodiments of the disclosure provide a mirror assembly for controlling optical directions in an optical sensing system. The mirror assembly may include a substrate and a micro mirror suspended over the substrate by at least one beam. The at least one beam may be mechanically coupled to the substrate. The mirror assembly may also include an actuator configured to tilt the micro mirror with respect to the substrate. The mirror assembly may further include a position sensor configured to detect a position of the micro mirror. Moreover, the mirror assembly may include a bias voltage source electrically coupled to the substrate to bias the substrate with a bias voltage.