Optical Deflector Cover with Phase-Canceling Acoustic Design
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Solution Overview
Problem
Conventional optical deflectors with non-closed covers suffer from noise leakage due to the rotation of the rotary polyhedron, which is mitigated by minimizing the opening size, but this compromises the efficiency of light scanning.
Innovation Solution
The optical deflector design features a cover member with an opening where the distance between the circumscribed circle of the rotary polyhedron and the inner peripheral surface of the cover is maximized at both ends, allowing for a larger clearance that reduces noise by phase-canceling sound waves generated during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the opening size is minimized to reduce noise leakage, then noise reduction is improved, but light scanning efficiency deteriorates
Solution Approach 1:
The cover member is designed with non-uniform thickness, creating local variations in the air column properties. The thickness is greater at specific locations (e.g., opposite to the opening or at predetermined angular positions) to create acoustic impedance variations that generate phase-canceling sound waves, while maintaining a sufficiently large opening for efficient light scanning.
Solution Approach 2:
The invention converts the harmful noise generated by rotary polyhedron rotation into beneficial phase-canceling sound waves. By strategically designing the cover member thickness distribution, the air column within the cover generates sound waves that are phase-shifted relative to the noise from the rotary polyhedron, causing destructive interference and noise reduction at the opening.
2Productivity
If the cover is made non-closed to improve light scanning, then light scanning efficiency is improved, but noise leakage increases
Solution Approach 1:
The cover member maintains a non-closed structure with an opening for efficient light scanning, but incorporates local thickness variations that create acoustic control zones. These localized structural modifications enable noise reduction through phase cancellation without compromising the overall openness required for light scanning operations.
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 effectively reduces noise levels while maintaining efficient light scanning, even with a non-sealed cover type, by ensuring consistent pressure variations and phase-shifted sound waves cancel each other out.
Implementation Method 1
the distance between a circumscribed circle of the rotary polyhedron centered on the axis of the rotary polyhedron and an inner peripheral surface of a peripheral wall of the cover member in a radial direction of the rotary polyhedron is largest at both of circumferential ends of the opening... ensures consistent pressure variations and phase-shifted sound waves cancel each other out
Data Source
AI summary
An optical deflector is configured such that a distance between a circumscribed circle of a rotary polyhedron centered on an axis of the rotary polyhedron and an inner peripheral surface of a peripheral wall of a cover member in a radial direction of the rotary polyhedron is largest at both of circumferential ends of an opening of the cover member.