Polygon Mirror Cover Ribs for Scanning Optics Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The generation of loud wind noise, or rotation sound, in scanning optical devices due to vortex flow and fluid fluctuation caused by the high-speed rotation of rotational polygon mirrors is not adequately addressed by existing rib configurations, leading to increased noise levels.
Innovation Solution
A scanning optical device with a cover member featuring a plurality of ribs disposed symmetrically around the rotational polygon mirror, offset from imaginary lines, to divide and rectify the vortex flow and suppress wind blowing against the mirror's edge portion, thereby reducing turbulence and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ribs are added to block vortex flow, then quietness is improved, but fluid fluctuation increases and rotation sound increases
Solution Approach 1:
The patent applies local quality by making the ribs have different lengths at different radial positions. The ribs are longer at the outer end and shorter at the inner end, creating a gradient structure that locally adapts to the vortex flow characteristics at different distances from the rotation axis, thereby reducing fluid fluctuation while maintaining quietness
Solution Approach 2:
The patent employs asymmetry by configuring ribs with non-uniform lengths along their longitudinal direction. This asymmetric length distribution allows the ribs to effectively break up vortex flow at multiple radial positions simultaneously, addressing the contradiction between blocking vortex flow and reducing fluid fluctuation
2Productivity
If rotational polygon mirror rotates at high speed, then productivity is improved, but rotation sound increases
Solution Approach 1:
The patent segments the vortex flow into multiple smaller flow paths by introducing multiple ribs with rotational symmetry. This segmentation breaks the large-scale vortex flow into smaller eddies that dissipate more efficiently, reducing rotation sound while allowing high-speed operation
Solution Approach 2:
The ribs serve as intermediary elements between the rotating polygon mirror and the surrounding air. They act as flow modifiers that intercept and redirect the vortex flow, reducing the harmful acoustic effects while allowing the mirror to rotate at high speeds for maintained productivity
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 proposed configuration effectively reduces noise levels by approximately 40% compared to conventional designs, achieving improved quietness and reducing dust accumulation on optical elements.
Implementation Method 1
a light beam emitted from a semiconductor laser is deflected and scanned by a rotational polygon mirror
Implementation Method 2
air flow circulating in an annular shape (hereinafter referred to as vortex flow) about a rotational axis of the rotational polygon mirror, which is generated when the rotational polygon mirror is rotated
Implementation Method 3
suppressing wind blowing against an edge portion of the rotational polygon mirror... reducing turbulence and noise
Data Source
AI summary
A scanning optical device includes a polygon mirror, an optical box accommodating the polygon mirror, and a cover covering an opening of the optical box. On an opposite surface of the cover, a plurality of ribs projected toward the polygon mirror are formed. As viewed in a rotational axis direction of the polygon mirror, the ribs are disposed so as to have rotational symmetry about a rotational axis, extended from the axis toward a circumscribing circle of the polygon mirror, and disposed at positions apart from a distance in upstream or downstream side in the rotational direction to imaginary lines, of the same number as that of the ribs, having rotational symmetry about the rotational axis. Each of ribs has a lengthy shape parallel to the corresponding imaginary line, one end portion thereof is disposed outside and the other end portion thereof is disposed inside the circumscribing circle.