Lissajous Scanner Deflection Device with Simplified Spring Suspension
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Solution Overview
Problem
Conventional gimbal-suspended, biaxial resonant MEMS scanners face challenges with high resolution requirements, leading to increased size, mechanical overcoupling, sensitivity to vibrations, inefficient torque generation, parasitic eigenmodes, and thermal instability, which compromise image quality and sturdiness.
Innovation Solution
A deflection device with a micromirror oscillating in two axes, using a simplified suspension mount with one or multiple springs attached to a stationary frame, and a control device that adjusts control frequencies to maintain resonance within predefined limits, reducing the need for a gimbal and minimizing parasitic eigenmodes, while ensuring effective image overlap and scanning resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gimbal-suspended biaxial resonant MEMS scanner is used to achieve high scanning resolution, then the scanning resolution is improved, but the size of the scanner increases and mechanical overcoupling occurs
Solution Approach 1:
The patent removes the outer gimbal frame from the scanner structure, extracting the unnecessary moving frame that caused mechanical overcoupling and increased size. Only the essential inner gimbal and mirror assembly remain, directly reducing the scanner's overall volume while preserving scanning resolution through the simplified suspension system.
Solution Approach 2:
The scanner is divided into functionally independent segments: the inner gimbal handling one scanning axis and the mirror plate handling the other axis. This segmentation allows each component to be optimized independently for its specific scanning function, reducing overall mechanical complexity and size while maintaining high resolution capabilities.
2Measurement precision
If a gimbal-suspended biaxial resonant MEMS scanner is used to achieve high scanning resolution, then the scanning resolution is improved, but mechanical overcoupling and sensitivity to vibrations increase
Solution Approach 1:
By removing the outer gimbal frame, the patent eliminates the source of mechanical overcoupling between scanning axes. The simplified structure with only the inner gimbal and direct mirror suspension reduces vibration sensitivity and improves sturdiness, as there are fewer moving parts that could couple mechanical disturbances between axes.
3Measurement precision
If a gimbal-suspended biaxial resonant MEMS scanner is used to achieve high scanning resolution, then the scanning resolution is improved, but parasitic eigenmodes and thermal fluctuations increase
Solution Approach 1:
The removal of the outer gimbal frame eliminates parasitic eigenmodes associated with the complex gimbal structure. The simplified two-component system (inner gimbal + mirror) has fewer natural frequencies, removing harmful parasitic modes that would interfere with the desired scanning motion and image quality.
4Volume of moving object
If a simplified suspension mount with springs is used, then the scanner size is reduced and sturdiness is enhanced, but the complexity of controlling resonance frequencies increases
Solution Approach 1:
The control device uses feedback mechanisms to continuously monitor and adjust the resonance frequencies of the spring suspension system. By detecting actual oscillation characteristics and modifying drive signals accordingly, the system maintains precise resonance control despite the simplified mechanical structure, managing control complexity through intelligent feedback rather than mechanical 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 configuration reduces the size of the scanner, minimizes mechanical overcoupling, enhances sturdiness, and maintains image quality by allowing for precise control of resonance frequencies, reducing parasitic eigenmodes and thermal fluctuations, resulting in a more compact and stable scanning system.
Implementation Method 1
a suspension mount with one or multiple springs, wherein the micromirror is suspended by the springs
Implementation Method 2
a control device for generating oscillation signals for a resonant operation of the micromirror in the two axes
Data Source
AI summary
A deflection device for a scanner with Lissajous scanning includes a micromirror that oscillates in at least two deflection axes and that includes a frame and a mirror plate that is movably arranged via a suspension mount. The deflection device also includes a control device for generating control signals for a resonant operation of the micromirror in the at least two deflection axes. The suspension mount includes at least one spring connected at one end to the mirror plate and at the other end to the frame. The frequencies of the control signals for the resonant operation of the micromirror are substantially equal in the at least two deflection axes, but differ at least in terms of the predefined scanning repetition rate. The levels of the resonance frequencies of the deflection axes and control signals are determined by a predefined scanning resolution and a predefined scanning repetition rate.