Lissajous Microscanner Central Spring Suspension
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Solution Overview
Problem
Microscanners face challenges in achieving high scanning frequencies, large mirror diameters, and minimal power consumption while maintaining optical resolution and compact design, as these requirements often conflict with each other, leading to trade-offs in performance and manufacturing costs.
Innovation Solution
A microscanner design featuring a deflection element suspended by inwardly directed springs on a central support structure, allowing for large scanning angles and frequencies, compact size, and reduced spring stress, with optional features like rotational symmetry, recessed deflection plates, and encapsulation for enhanced performance and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the mirror is suspended on outwardly directed springs from an outer frame, then the mirror can be supported structurally, but the mass moment of inertia increases and scanning frequencies are limited
Solution Approach 1:
The patent inverts the conventional spring arrangement by directing springs inward toward a central support structure instead of outward to an outer frame. This inversion relocates the suspension points to the center of the mirror, significantly reducing the mass moment of inertia and enabling higher scanning frequencies while maintaining structural support.
Solution Approach 2:
The patent transitions from a two-dimensional outer frame suspension system to a three-dimensional central support structure. The springs extend vertically from a central support element to the mirror, creating a new spatial dimension for suspension that reduces the effective moment of inertia and improves scanning performance.
2Measurement precision
If the mirror diameter is increased to improve optical resolution, then scanning accuracy improves, but the device size and spring stress increase
Solution Approach 1:
By inverting the spring direction to point inward toward the center, the patent reduces the lever arm length for spring stress calculation. The springs experience lower stress for the same mirror diameter because the suspension points are closer to the mirror's center of rotation, enabling larger mirror diameters without excessive stress.
Solution Approach 2:
The patent changes the geometric parameters of the suspension system by relocating spring attachment points to the central support structure. This parameter change reduces the effective spring length and stress for a given mirror size, allowing optimization of mirror diameter for optical resolution without proportional increases in spring stress.
3Measurement precision
If the mirror diameter is increased to improve optical resolution, then scanning accuracy improves, but the device becomes less compact
Solution Approach 1:
The patent merges the central support structure with the spring suspension system, eliminating the need for a separate outer frame. This integration consolidates structural elements into a compact central assembly that supports larger mirror diameters while maintaining a small overall device footprint suitable for portable applications.
Solution Approach 2:
The inverted spring arrangement with inwardly directed springs creates a more compact device architecture. The central support structure serves as both the suspension anchor and the structural core, reducing the overall device volume compared to conventional outer frame designs that require additional structural elements.
4Length of moving object
If resonant operation is used to achieve greater oscillation amplitudes, then scanning range improves, but power consumption increases
Solution Approach 1:
The patent employs resonant mechanical vibration of the mirror at its natural frequency to achieve large oscillation amplitudes with minimal drive force. The inwardly directed spring suspension optimizes the mirror's natural frequency characteristics, enabling resonant operation that provides large scanning amplitudes while minimizing power consumption compared to non-resonant operation.
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 achieves high scanning frequencies and large scanning angles with reduced mass moment of inertia, lower manufacturing costs, and minimized power consumption, while maintaining high optical resolution and compactness, suitable for applications like augmented reality and laser projection displays.
Implementation Method 1
a spring device comprising one or more springs, by means of which the deflection element is suspended on the support structure in an oscillating manner
Data Source
AI summary
A microscanner has: a deflection element for deflecting an incident electromagnetic beam; a support structure; and a spring device comprising one or more springs, by means of which the deflection element is suspended on the support structure in an oscillating manner in such a way that it can simultaneously carry out a first rotational oscillation around a first oscillation axis and a second rotational oscillation around a second oscillation axis orthogonal thereto relative to the support structure, in order to be able to effectuate a Lissajous projection in an observation field by reflection of an electromagnetic beam incident on the deflection element during the simultaneous oscillations. The support structure has a spring support structure and the spring device has a number N of first springs, wherein N≥1 and each of the N first springs is attached to at least one assigned attachment point on the spring support structure, is coupled to the deflection element at at least one assigned coupling point, and extends between this attachment point and this coupling point. There are three points on the deflection element, which in its rest position define a Euclidean auxiliary plane and therein span a surface or straight-line section enclosed by the connecting straight line between the three points, on which each of the attachment points, or their respective perpendicular projection on the auxiliary plane, lies.