Optical Scanning Device Elastic Layer Fatigue Resistance
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Solution Overview
Problem
The existing optical scanning devices with a metal film on the torsion bar face issues with increased thickness, reduced width, and decreased maximum deflection angle, leading to a hard spring effect and potential reliability concerns due to metal film deterioration.
Innovation Solution
The optical scanning device incorporates a reflector, a rotator, first and second torsion beams, support parts, and elastic layers made of materials with higher fatigue life than metal, which reduces the hard spring effect and maintains a high maximum deflection angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal film is superposed on the torsion bar, then the thickness dimension of the torsion bar increases and the width dimension is curbed, but the hard spring effect increases and the maximum deflection angle decreases
Solution Approach 1:
The patent changes the material parameter of the elastic layer from metal to a material with higher fatigue life (such as silicon or silicon nitride). This material substitution maintains the structural thickness needed to curb width increase while avoiding the hard spring effect and material deterioration associated with metal films, thereby preserving maximum deflection angle and improving long-term reliability
Solution Approach 2:
The patent employs composite structure where the elastic layer is made of non-metallic material (such as silicon-based materials) instead of metal film. This composite approach combines the benefits of maintaining dimensional stability (thickness control) while avoiding the detrimental effects of metal fatigue and hard spring effect, achieving both reliability improvement and performance maintenance
2Shape
If a metal film is superposed on the torsion bar, then the thickness dimension increases, but the width dimension is curbed, however stress from rotation repeatedly applied to the metal film causes deterioration
Solution Approach 1:
The patent changes the material parameter from metal to materials with higher fatigue life (such as silicon, silicon nitride, or other ceramic materials). This substitution maintains the required thickness dimension for structural integrity while eliminating the fatigue deterioration problem inherent in metal films subjected to repeated rotational stress
Solution Approach 2:
The patent replaces durable metal films with materials specifically selected for their superior fatigue resistance properties. These materials (such as silicon-based materials) are engineered to withstand repeated stress cycles without the deterioration issues of metal, effectively creating a more reliable long-term solution despite potential differences in material characteristics
3Device complexity
If the metal film is used in the torsion bar, then the structure is compact, but the hard spring effect increases making peak frequency higher
Solution Approach 1:
The patent changes the material parameter of the elastic layer to non-metallic materials (such as silicon or silicon nitride) that have different mechanical properties compared to metal. This substitution reduces the hard spring effect and lowers the peak frequency while maintaining the compact structural design, achieving a balance between compactness and dynamic performance
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 hard spring effect, maintains a high maximum deflection angle, and enhances the long-term reliability of the optical scanning device by using elastic materials that withstand stress better than metal.
Implementation Method 1
a material of the first elastic layer and the second elastic layer is an elastic material higher in fatigue life than metal
Implementation Method 2
an elastic material higher in fatigue life than metal
Data Source
AI summary
An optical scanning device includes a reflector, a rotator, a first torsion beam and a second torsion beam, a first support part, a second support part, a first elastic layer, and a second elastic layer. The first elastic layer is superposed on the first torsion beam. The second elastic layer is superposed on the second torsion beam. A vertical dimension of an active layer is smaller than a horizontal dimension of the active layer in a cross section orthogonal to a direction in which the rotator is interposed between the first torsion beam and the second torsion beam. A material of the first elastic layer and the second elastic layer is higher in fatigue life than metal.