MEMS Resistive Sensor for Mobile Element Position Detection
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Solution Overview
Problem
Existing MEMS devices face limitations in accurately determining the position of a mobile element, particularly in resonant MEMS reflectors, due to saturation issues in amplifiers during driving periods and the need for complex correlation algorithms, which restricts the duration and frequency of electrical pulses.
Innovation Solution
A MEMS device with a fixed supporting body, deformable elements, and a generator that causes a current to flow through these elements to generate an electrical signal proportional to their resistances, indicating the angular position of the mobile element, allowing for continuous position detection and control without additional electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive sensing with derivative detection is used to determine mirror position, then position detection is enabled, but amplifier saturation occurs during driving periods causing detection failure
Solution Approach 1:
The patent replaces capacitive sensing (electrical field-based) with resistive sensing (ohmic law-based). The deformable element's resistance changes with mechanical deformation, providing a direct resistance-position relationship that can be measured without complex derivative calculations and avoids amplifier saturation issues.
Solution Approach 2:
The patent changes the measurement parameter from capacitance derivative to resistance. By using the resistive property of the deformable element, the system obtains position information through resistance measurements that are linear and direct, avoiding the saturation problem inherent in capacitive sensing during high-voltage driving periods.
2Measurement precision
If complex correlation algorithms are used to process capacitive signals, then position determination is achieved, but processing complexity and computational requirements increase
Solution Approach 1:
The patent substitutes complex electrical signal processing (capacitive sensing requiring correlation algorithms) with a simpler resistive measurement approach. The direct resistance-position relationship eliminates the need for complex computational algorithms, reducing processing requirements while maintaining accuracy.
3Power
If high-voltage pulses are applied to drive the mobile element, then actuation effectiveness is improved, but amplifier saturation occurs during monitoring periods
Solution Approach 1:
The patent replaces capacitive sensing (which requires high-voltage pulses for actuation and suffers from amplifier saturation) with resistive sensing. The deformable element's resistance provides a direct position indicator that works independently of the actuation voltage level, allowing continuous operation without saturation.
4Measurement precision
If monitoring periods are inserted to avoid amplifier saturation, then detection is enabled, but the duration of driving periods is limited reducing productivity
Solution Approach 1:
The patent eliminates the need for alternating monitoring and driving periods by using resistive sensing. The resistance-based position detection works continuously without requiring amplifier saturation avoidance, allowing uninterrupted driving and detection operations.
Solution Approach 2:
The patent enables continuous operation by replacing the intermittent monitoring-detection approach with continuous resistive sensing. The deformable element's resistance provides ongoing position information during the entire driving period, eliminating dead time and maximizing productivity.
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 detection and control of the mobile element's position using a resistive sensor, eliminating the need for complex processing units and ADC/DAC converters, and allowing for continuous operation without amplifier saturation.
Implementation Method 1
a generator configured to cause a current to flow through at least one of the first and second deformable elements, so as to generate an electrical position signal proportional to at least one of a first resistance, of the first deformable element, and a second resistance, of the second deformable element
Data Source
AI summary
A MEMS device includes a supporting body, a first deformable element and a second deformable element, and a mobile element set between the first and second deformable elements and rotatable with respect to the fixed supporting body. A generator causes a current to flow through at least one of the first and second deformable elements, which function as resistors, so as to generate an electrical position signal proportional to deformation of the first and second deformable elements and indicative of angular position of the mobile element. The electrical signal is processed to determine mobile element angular position. A drive signal is generated in response to the electrical signal for the purpose of driving oscillation of the mobile element.