Rotary Polygon Mirror Protrusion Design for Deformation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional rotary polygon mirrors in light deflectors experience static surface deformation due to press-fitting and shrinkage, leading to image deterioration and increased wind noise during high-speed rotation, particularly when formed using resin molding.
Innovation Solution
A rotary polygon mirror design featuring a protruded portion with a fitting portion that is coaxial with the shaft, allowing for a clearance fit and reducing static surface deformation without compromising the quietness of the light deflector, by providing a space between the protrusion and the flange portion to absorb radial stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rotary polygon mirror is formed by resin molding with a large diameter hole portion and reduced flange portion diameters, then manufacturing complexity is reduced, but manufacturing precision deteriorates due to difficulty in forming the structure by resin molding and potential axial misalignment
Solution Approach 1:
A positioning protrusion is added as an intermediary element that mediates between the hole portion and the flange portion. This protrusion with a positioning groove ensures precise alignment during assembly, preventing axial misalignment while maintaining the resin molding manufacturing method.
Solution Approach 2:
The hole portion is segmented into multiple functional zones: an upper hole portion for motor insertion, a lower hole portion for positioning, and a protrusion with positioning groove. This segmentation allows each part to fulfill its specific function, ensuring both ease of manufacture and high precision.
2Manufacturing precision
If protruded portions are pressed onto the flange portion with recesses in the rotational axis direction, then static surface deformation is suppressed, but wind noise increases during high-speed rotation
Solution Approach 1:
The harmful recesses that cause wind noise are extracted/removed from the design. Instead, a positioning protrusion with a positioning groove is used to achieve surface deformation control without creating the wind noise problem associated with recesses.
3Strength
If the rotation shaft is press-fitted into the flange portion, then the rotary polygon mirror is securely mounted, but static surface deformation occurs due to axial misalignment
Solution Approach 1:
Alignment is performed preliminarily through the positioning protrusion and positioning groove before the press-fitting operation. This preliminary positioning action ensures that the shaft and flange portion are perfectly aligned, preventing static surface deformation during secure mounting.
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 solution effectively reduces static surface deformation of the reflecting surfaces by about 40% compared to conventional designs, thereby improving image quality and maintaining the quiet operation of the light deflector.
Implementation Method 1
the protruded portion includes a fitting portion in which a portion continued from a surface forming the hole portion is protruded toward the center of the rotation more than the surface forming the hole portion, and is fitted to the shaft portion or the support member
Data Source
AI summary
A light deflector includes a rotary polygon mirror and a motor to rotate the rotary polygon mirror. The rotary polygon mirror includes reflecting surfaces to reflect light emitted from a light source and a hole portion provided in a rotational axis direction. The motor includes a shaft portion in the hole portion and a support member supporting the rotary polygon mirror. The support member is fixed to, and coaxial with, the shaft portion, and includes an insertion portion in the hole portion. The rotary polygon mirror includes a protruded portion near the hole portion and protruding from at least one reflecting surface orthogonal to the rotational axis direction. The protruded portion includes a fitting portion fitted to the shaft portion or the support member and in which a portion continued from a hole portion surface is protruded toward the rotation center more than the surface forming the hole portion.