Projector Shaft Section Recess Design for Stress Reduction
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Solution Overview
Problem
Existing optical devices with movable sections connected via shafts suffer from torsional stress, leading to instability and decreased image quality due to insufficient torque and rigidity, particularly when thickening the shaft section results in inadequate rotational torque and excessive flexion.
Innovation Solution
The optical device features a shaft section with a cross-sectional shape having multiple inward recesses, which reduces stress concentration and improves durability by increasing the number of protrusions for stress dispersion, allowing precise pixel shifting and enhanced image quality without increasing rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the shaft section is thickened to ensure rigidity, then rigidity is improved, but torque for rotating the movable section becomes insufficient
Solution Approach 1:
The patent changes the geometric parameters of the shaft section by introducing recesses in its cross-sectional shape. This modifies the distribution of material without changing the overall size, achieving both rigidity and torque requirements through optimized parameter configuration rather than simple thickening.
Solution Approach 2:
The shaft section employs a composite cross-sectional geometry combining protruding portions and recessed portions. This composite shape allows different regions to serve different functions: protruding portions provide torque transmission while recessed portions reduce stress concentration, achieving both force transmission and structural strength.
2Strength
If the shaft section is thickened to ensure rigidity, then rigidity is improved, but the cross-sectional shape becomes less optimized for stress distribution
Solution Approach 1:
The patent optimizes the stress distribution by changing the geometric parameters of the shaft cross-section. The recesses are strategically positioned and sized to create a shape that naturally distributes stress more evenly during rotation, reducing peak stress concentrations while maintaining overall rigidity.
Solution Approach 2:
The recessed portions of the shaft cross-section feature curved surfaces rather than sharp corners. This curvature helps to distribute stress more uniformly by eliminating stress concentration points that would occur at sharp internal corners, while still maintaining the structural integrity and rigidity of the shaft.
3Strength
If the shaft section is thickened to ensure rigidity, then rigidity is improved, but the movable section becomes less stable due to excessive flexion
Solution Approach 1:
The patent achieves the right balance between rigidity and flexibility by optimizing the geometric parameters of the shaft cross-section. The recesses are designed with specific dimensions and positions that provide sufficient rigidity to prevent excessive flexion while maintaining stability of the movable section during operation.
Solution Approach 2:
The shaft cross-section exhibits local quality variations through the strategic placement of recesses in specific regions. This allows different parts of the shaft to have different mechanical properties - areas with recesses provide stress relief and controlled flexibility, while other areas maintain higher rigidity, achieving overall stability without excessive flexion.
Data Source
AI summary
A projector includes a light outputting apparatus that outputs video light, a projection system that enlarges and projects the video light, and an optical device disposed between the light outputting apparatus and the projection system. The optical device includes a movable section including a glass plate (optical section) having a light incident surface on which the video light is incident, a shaft section that swingably supports the movable section around a first swing axis, and an actuator that causes the movable section to swing. The cross-sectional shape of the shaft section viewed in the direction along the first swing axis is a shape having a plurality of recesses recessed inward.