Micromirror Piezoelectric Sensor Placement for Angle Detection Accuracy
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Solution Overview
Problem
Micromirror devices using piezoelectric sensors for angle detection suffer from accuracy deterioration due to noise components from surrounding wiring and signal interference, particularly in high-stress areas like the support portions.
Innovation Solution
The micromirror device incorporates four piezoelectric sensors with line-symmetrical relationships about the axes, strategically positioned on the fixed frame, and connected via metal wiring lines to generate angle detection signals by adding or subtracting voltage signals, reducing noise interference and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the piezoelectric sensor is disposed in the vicinity of the support portion or actuator, then the manufacturing process is simplified and device size is decreased, but the angle detection accuracy deteriorates due to noise components from surrounding wiring and signal interference
Solution Approach 1:
The piezoelectric sensor is extracted from the high-stress support portion and relocated to the fixed frame, separating the sensing function from the actuation region. This extraction eliminates the noise interference from surrounding wiring and signal superposition while maintaining manufacturing simplicity through integrated sensor fabrication on the fixed frame substrate.
Solution Approach 2:
The fixed frame serves as an intermediary platform that hosts the piezoelectric sensor away from the high-stress support portion. This intermediary location provides electrical isolation and mechanical stability, allowing the sensor to detect angular position without interference from actuator wiring and signal noise while maintaining structural integrity.
2Volume of moving object
If the piezoelectric sensor is disposed in the vicinity of the support portion or actuator, then device size is decreased, but the voltage signal contains large amounts of noise components from interference
Solution Approach 1:
The sensor is extracted from the compact support portion region and placed on the fixed frame, which provides sufficient space for sensor placement without increasing overall device volume significantly. This extraction removes the sensor from the high-interference electromagnetic environment near the actuator wiring, eliminating noise components while maintaining compact device dimensions.
Solution Approach 2:
The fixed frame provides a local environment with favorable electrical and mechanical properties for sensor operation. This location offers electrical isolation from actuator wiring and mechanical stability, creating a noise-free zone for voltage signal generation while maintaining the compact overall device structure through efficient space utilization.
3Reliability
If the piezoelectric sensor is disposed in the vicinity of the support portion or actuator, then the sensor can detect stress from mirror portion swinging, but signal component from another axis interferes with detection
Solution Approach 1:
The sensor is extracted from the support portion where multi-axis stress coupling occurs and relocated to the fixed frame. This extraction allows the sensor to detect stress from mirror portion swinging through the support structure while being positioned in a location where signals from different axes do not superimpose, enabling accurate single-axis detection.
Solution Approach 2:
The sensor placement on the fixed frame creates an asymmetric detection configuration relative to the support portion, breaking the symmetry that causes signal superposition from multiple axes. This asymmetric positioning ensures that the sensor responds primarily to stress from the target axis while minimizing interference from orthogonal axis signals.
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 configuration enhances the accuracy of angle detection for the mirror portion by minimizing noise components and improving signal clarity, leading to more precise control of the micromirror's movement.
Implementation Method 1
The piezoelectric sensor converts stress generated by the swinging of the mirror portion into a voltage signal and outputs the signal
Data Source
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AI summary
Provided are a micromirror device and an optical scanning device capable of improving an accuracy of angle detection of a mirror portion. The micromirror device includes: a mirror portion; a pair of first support portions; a pair of movable frames; a pair of second support portions; a driving portion; a fixed frame; a pair of connecting portions that have a thinner thickness than the fixed frame and stretch along a first axis and a second axis to connect the driving portion and the fixed frame; and four piezoelectric sensors in each of which a shape and a position of an upper electrode are in a line-symmetrical relationship about the first axis and the second axis. In a case where a stretching direction of the connecting portion is a first direction, a direction orthogonal to the first direction and located in a plane is a second direction, and a length of a boundary between the fixed frame and the connecting portion in the second direction is denoted by H, at least a part of each of the four piezoelectric sensors is within a range of H/2 in the second direction from an axis parallel to the first direction, out of the first axis and the second axis, and is disposed on the fixed frame.