Micromirror Support Geometry for Stable Two-Dimensional Scanning
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Solution Overview
Problem
Micromirror devices experience crosstalk between axes during resonant driving, leading to shifts in resonance frequency and instability in two-dimensional optical scanning, particularly affecting deflection angles and scan stability.
Innovation Solution
A micromirror device design with specific geometric relationships between support and actuator components, including a distance ratio of ⅔<A/L, where A is the distance between the second axis and a straight line on the second support portion, and L is the total length of the second support portion, to suppress resonance frequency shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the micromirror device is driven resonantly to increase deflection angle, then the scan angle is improved, but crosstalk between axes causes resonance frequency shift and reduces scanning stability
Solution Approach 1:
The patent applies preliminary anti-action by designing the second support portion with a specific geometric relationship (2/3 < A/L) that preemptively counteracts the crosstalk-induced resonance frequency shift. The support portion is configured to reduce the coupling between first and second axes before the crosstalk can significantly affect scanning stability, thereby maintaining stable resonance frequency during resonant driving.
2Speed
If the driving frequency is swept to increase deflection angle, then the scan area is improved, but the feedback phenomenon from crosstalk prevents frequency adjustment and limits deflection angle increase
Solution Approach 1:
The geometric configuration of the second support portion (2/3 < A/L) serves as a preliminary anti-action measure that reduces crosstalk coupling before it can create problematic feedback phenomena. This allows the driving frequency to be swept effectively to increase deflection angle without encountering the feedback phenomenon that would otherwise prevent frequency adjustment.
3Force
If the micromirror device uses piezoelectric actuator for high torque, then the scan angle is improved, but the crosstalk between axes becomes more significant
Solution Approach 1:
The patent designs the second support portion with the geometric relationship 2/3 < A/L to preemptively counteract the crosstalk generated by the piezoelectric actuator. This configuration reduces the coupling between axes before the high torque from the piezoelectric actuator can induce significant crosstalk, allowing high torque operation with minimal crosstalk interference.
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 design effectively reduces resonance frequency shifts and stabilizes two-dimensional scanning, enhancing scan stability and deflection angles while maintaining low power consumption.
Implementation Method 1
a piezoelectric drive method using deformation of a piezoelectric body
Implementation Method 2
a reflecting surface for reflecting incident light is formed
Data Source
AI summary
The micromirror device includes: a mirror portion; a first support portion that swingably supports the mirror portion around a first axis; a pair of movable frames that face each other across the first axis; a second support portion that swingably supports a movable portion around a second axis; a driving portion that surrounds the movable portion and has a gap with the second support portion on the second axis; a coupling portion that couples the second support portion and the driving portion; and a fixed frame, in which, in a state where the mirror portion rotates around the first axis and an absolute value of a rotation angle is larger than 0 degrees, assuming that, in a plane orthogonal to the first axis and including the second axis, a distance between an intersection between the second axis and a straight line located on a surface of the second support portion and including each end point of the second support portion and an end part of the second support portion on a mirror portion side in a stationary state is denoted by A, and a total length of the second support portion in a direction of the second axis is denoted by L, a relationship of ⅔<A/L is satisfied.