Light Deflector Elastic Member Rigidity Gradient
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Solution Overview
Problem
Micromachining-based light deflectors face issues with dynamic distortion of reflective surfaces due to increased kinetic energy at higher scan rates, leading to deterioration in beam spot shape, which existing solutions like Japanese Patent No. 5168659 attempt to address by using a twisting beam with ribs to suppress stress-induced distortion.
Innovation Solution
A light deflector design featuring a movable unit with a reflective surface supported by elastic members that have continuous-rigidity connection segments, where the rigidity changes between the movable unit and the supporter, preventing stress concentration and deformation by confining inertial forces within the elastic members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scan rate is increased, then the productivity is improved, but the dynamic distortion of the reflective surface increases causing deterioration in beam spot shape
Solution Approach 1:
The elastic member is designed with non-uniform cross-sectional dimensions, where the width and thickness vary along its length. Specifically, the width gradually increases from the movable unit side toward the supporter side, and the thickness is greater near the movable unit. This creates localized rigidity variations that suppress dynamic distortion at critical areas while maintaining the overall flexibility needed for high-speed scanning.
Solution Approach 2:
The patent modifies the physical parameters of the elastic member by making the width and thickness non-uniform along its length. This parameter variation optimizes the balance between flexibility (for high scan rates) and rigidity (for maintaining beam spot shape), resolving the contradiction between productivity and manufacturing precision.
2Productivity
If the scan rate is increased, then the productivity is improved, but the kinetic energy increases causing stress-induced distortion
Solution Approach 1:
The elastic member features localized variations in cross-sectional dimensions, with greater thickness near the movable unit and gradually increasing width toward the supporter. This creates regions of different rigidity that effectively manage stress distribution under high kinetic energy conditions, preventing stress-induced distortion while enabling high scan rates.
Solution Approach 2:
The elastic member can be formed as a single piece or by joining multiple pieces together, creating a composite structure with optimized stress distribution. This composite approach allows different sections to have tailored mechanical properties that collectively resist stress-induced distortion during high-speed operation.
3Manufacturing precision
If ribs are added to suppress distortion, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent integrates the distortion suppression function directly into the elastic member's geometry by making its cross-sectional dimensions non-uniform. This merges the structural support function with the distortion control function into a single component, eliminating the need for separate ribs or additional structural elements, thus improving manufacturing precision without increasing device complexity.
4Manufacturing precision
If the elastic member has high rigidity, then the manufacturing precision is improved, but the scan rate decreases due to increased stress
Solution Approach 1:
The elastic member is designed with spatially varying rigidity through non-uniform width and thickness. This creates a gradient of stiffness that provides sufficient rigidity to maintain beam spot shape while allowing enough flexibility to achieve high scan rates, resolving the contradiction between manufacturing precision and speed.
Solution Approach 2:
The elastic member's design optimizes the dynamic response by varying its cross-sectional dimensions along its length. This dynamic structural optimization allows the member to flex appropriately during high-speed scanning while maintaining positional accuracy, enabling both high scan rates and manufacturing precision.
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 design effectively suppresses deformation and increases the torsional rigidity of the elastic members, enhancing the scanning rate while preventing breakage, thus maintaining the shape of the beam spot and improving the light deflector's performance.
Implementation Method 1
an elastic member that supports the movable unit in a tiltable manner about a tilting axis
Implementation Method 2
a movable unit having a reflective surface... to change the direction of light reflected at the reflective surface
Data Source
AI summary
A light deflector includes a movable unit having a reflective surface, an elastic member that supports the movable unit in a tiltable manner about a tilting axis, and a supporter that supports the elastic member. The elastic member has a first connection segment whose rigidity changes continuously, and is connected to the movable unit at the first connection segment. The rigidity changes continuously between the elastic member and the movable unit via the first connection segment. The elastic member includes a linear segment having a substantially fixed width, the elastic member has a second connection segment that is provided between the linear segment and the supporter and that connects the linear segment and the supporter, a width of the second connection segment gradually increases toward the supporter, and a maximum width of the first connection segment is greater than a maximum width of the second connection segment.