MEMS Micro-Mirror Evaluation Using Multiplexed Capacitance Sensing
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Solution Overview
Problem
Existing methods for evaluating Micro-ElectroMechanical System (MEMS) devices, such as electrostatic microactuators, are limited in their ability to assess specific components and ensure proper operation, particularly in terms of phase and amplitude characteristics.
Innovation Solution
A MEMS apparatus is designed with mechanical, electro-mechanical, and capacitive portions, including terminals for signal stimulation and processing circuitry to measure changes in capacitance, and uses frequency division multiplexing and quadrature signal processing to facilitate real-time analysis of phase and amplitude, enabling independent measurement of individual electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If lock-in amplifiers are used to measure MEMS device displacements, then measurement capability is provided, but the ability to assess specific components and their phase/amplitude characteristics is limited
Solution Approach 1:
The patent divides the measurement task into separate frequency channels using frequency division multiplexing. Different electrodes and their capacitance changes are measured at distinct frequencies, allowing specific components to be assessed independently while maintaining overall measurement precision
Solution Approach 2:
The patent introduces frequency division multiplexing and quadrature signal processing as intermediary techniques between the MEMS device and measurement system. These intermediaries enable the extraction of phase and amplitude characteristics of specific components by processing signals at different frequencies
2Measurement precision
If frequency division multiplexing and quadrature signal processing are used to enable independent measurement of individual electrodes, then measurement precision for specific components is improved, but device complexity increases
Solution Approach 1:
The measurement system is segmented into multiple frequency channels, with each channel dedicated to measuring specific electrodes or capacitance changes. This segmentation enables independent measurement while organizing the complexity into manageable frequency-separated modules
Solution Approach 2:
The patent employs universal signal processing techniques (frequency division multiplexing and quadrature processing) that can measure multiple electrodes and capacitance changes simultaneously through a single integrated system, reducing overall complexity despite the enhanced measurement precision
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
The solution allows for accurate and efficient evaluation of MEMS devices by determining angular and linear positions of mechanical components, enhancing the field of view and system speed through modulation of drive signals, applicable in LIDAR, laser microscopy, and head-mounted displays.
Implementation Method 1
filtering and processing circuitry configured and arranged to filter and process information derived from the produced output and generate therefrom a signal indicative of changes in capacitance related to the second terminal of the MEMS device
Data Source
AI summary
Aspects are directed to MEMS-type devices. In specific example, a MEMS device is to become actuated at least in part by an input signal and is coupled to or integrated with: a control circuit including at least one micro-mirror to provide a field of view; modulation circuitry to modulate the input signal via signal modulation, wherein in response to the input signal, as modulated, driving the MEMS apparatus, the field of view changes based on the operation of the control circuit. Such a MEMS device may be further configured to operate as a separate unit and/or with another device provide input signals, and to derive a signal indicative of nonlinearities or of changes in capacitance related to the MEMS device.