Optical Deflector Polygon Mirror Fixing Jitter Reduction
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Solution Overview
Problem
Conventional scanning optical devices using rotatable polygon mirrors face issues with jitter and surface inclination due to uneven urging force distribution, leading to image defects, as the spring's urging force does not act evenly on the mirror, causing deformation and accuracy differences among reflecting surfaces.
Innovation Solution
An optical deflector configuration with a rotatable polygon mirror, a driving unit, an urging member with an annular shape and radially extending arm portions, and a restricting member to securely fix the mirror, ensuring even force distribution and minimizing deformation across reflecting surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring is used to fix the rotatable polygon mirror to the pedestal, then the mirror is securely fixed, but the urging force is not distributed evenly causing deformation and surface inclination
Solution Approach 1:
The urging member is divided into multiple arm portions (at least three) that radially extend from an annular shape portion. Each arm portion applies urging force at different locations around the rotatable polygon mirror, distributing the total urging force evenly across the mirror surface. This segmentation prevents localized deformation and maintains reflecting surface accuracy while securing the mirror to the pedestal.
2Manufacturing precision
If the urging force of the spring is reduced to suppress deformation, then surface deformation is minimized, but the mirror may deviate from the pedestal during rotation increasing jitter
Solution Approach 1:
By dividing the urging force into multiple segments (arm portions) distributed around the mirror, each arm portion can apply a smaller, more localized force. The cumulative effect of all arm portions provides sufficient total urging force to prevent deviation during rotation, while the distributed nature of the force prevents localized deformation and maintains surface accuracy.
3Manufacturing precision
If frictional force between the spring and rotatable polygon mirror is reduced, then surface deformation is suppressed, but the urging force is not effectively transmitted to fix the mirror
Solution Approach 1:
The segmented arm portions contact the rotatable polygon mirror at multiple discrete points around its circumference. This distribution of contact points allows the urging force to be transmitted effectively to the mirror structure as a whole without requiring high friction at any single contact point. The cumulative effect of multiple contact points ensures stable fixing while minimizing localized deformation from friction.
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 stabilizes the rotatable polygon mirror, reduces jitter and surface inclination, and maintains high reflecting surface accuracy, resulting in improved image definition by evenly distributing the urging force and preventing eccentricity.
Implementation Method 1
an urging member configured to urge the rotatable polygon mirror toward the driving unit to fix the rotatable polygon mirror to the driving unit
Implementation Method 2
a restricting member configured to press the urging member and restrict movement of the urging member with respect to a rotational axis direction of the rotatable polygon mirror
Implementation Method 3
a rotatable polygon mirror including a plurality of reflecting surfaces for reflecting light
Data Source
AI summary
An optical deflector includes a rotatable polygon mirror and an urging member to urge the rotatable polygon mirror toward a driving unit to fix the rotatable polygon mirror to the driving unit. The urging member includes an annular shape portion having an annular shape surface contacting the rotatable polygon mirror and a plurality of arm portions integrally formed with the annular shape portion. The plurality of the arm portions radially extend from an outer circumference of the annular shape portion, are disposed at equal intervals with respect to a rotational direction with a rotation center of the rotatable polygon mirror, and are pressed by a restricting member.