Mirror Positioning in Optical Scanning Apparatus
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Solution Overview
Problem
In optical scanning apparatuses using electrophotographic methods, the accuracy of the seating surfaces in resin molded optical boxes can deteriorate due to molding variations, leading to unstable mirror orientations and shifts in the laser beam irradiation position, resulting in image quality deterioration.
Innovation Solution
The optical scanning apparatus employs a mirror with a length greater than its width, housed in an optical box with a first positioning portion having two seating surfaces and a second positioning portion with one seating surface, utilizing a first urging member with a greater pressure force than a second urging member to ensure the mirror is securely positioned and reduce vibration-induced shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mirror is positioned on a seating surface of a resin molded optical box by being urged by a spring, then the mirror can be easily positioned, but the accuracy of the seating surface deteriorates due to molding variation, making the mirror orientation unstable
Solution Approach 1:
The patent divides the single seating surface into multiple seating surfaces (first seating surface, second seating surface, third seating surface) arranged in a triangular pattern. This segmentation allows the mirror to be supported at multiple discrete points, compensating for molding variations in any single area and maintaining stable orientation despite resin molding inaccuracies.
Solution Approach 2:
The patent positions the three seating surfaces at specific locations around the mirror's support point, creating non-uniform local support qualities. The triangular arrangement ensures that at least three points maintain proper contact with the mirror base, providing stable orientation even when local seating surface accuracy varies due to molding processes.
2Reliability
If the seating surfaces are not parallel due to molding variation, then gaps are generated between the mirror and seating surfaces, but increasing the spring force to close the gaps causes rotational motion of the mirror
Solution Approach 1:
The patent uses a triangular arrangement of three seating surfaces to counterbalance the rotational moments generated by uneven spring forces. When gaps exist due to non-parallel seating surfaces, the distributed support points create opposing moments that balance each other, preventing net rotational motion of the mirror while maintaining contact stability.
Solution Approach 2:
The multiple seating surfaces are pre-positioned to accommodate potential gaps before they become problematic. The triangular configuration provides redundant support paths, so if one seating surface has a gap, the other two can maintain contact and prevent mirror instability, cushioning against the effects of molding variations.
3Manufacturing precision
If gaps are generated between the mirror and seating surfaces, then the mirror orientation becomes unstable, but the spring force may be insufficient to close the gaps
Solution Approach 1:
The patent segments the mirror support function across three separate seating surfaces instead of relying on a single seating surface. This distribution allows the total spring force to be divided among multiple contact points, ensuring that each individual spring can exert sufficient force to close gaps at its location without requiring excessive total force that would cause rotation.
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 the shift amount of the laser beam irradiation position due to mirror vibrations, maintaining stable image quality even when seating surface accuracy is compromised during molding.
Implementation Method 1
a mirror 11 having a length greater than a width and reflecting the laser beam LB
Implementation Method 2
a first urging member 18R configured to urge the mirror 11 toward the first positioning portion 13 and a second urging member 18L configured to urge the mirror 11 toward the second positioning portion 53
Data Source
AI summary
In an optical scanning apparatus, a first positioning portion has two seating surfaces that hold a mirror and a second positioning portion has only one seating surface that holds the mirror. A force of pressure of a first urging member is greater than a force of pressure of a second urging member, thereby preventing a vibration of the mirror.