Rotary Polygon Mirror Asymmetry for Light Scanning
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Solution Overview
Problem
The existing light scanning apparatuses face challenges in identifying the reflection surfaces of rotary polygon mirrors with manufacturing errors, leading to image defects due to varying interior angles, and existing solutions either fail to accurately identify the surfaces or introduce additional defects.
Innovation Solution
A light scanning apparatus is designed with a rotary polygon mirror formed in a four-sided polygon shape, where the difference between diametrically opposed interior angles is greater than 0.03°, and another pair of angles is 0.03° or less, facilitating accurate identification of reflection surfaces and preventing image defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the difference between interior angles of the rotary polygon mirror is increased to facilitate reflection surface identification, then identification is easier, but image defects are caused
Solution Approach 1:
The patent applies asymmetry by making the rotary polygon mirror a non-regular polygon where adjacent interior angles are intentionally made different from each other. This asymmetric design creates a unique BD signal pattern for each reflection surface, enabling reliable identification. The key innovation is that the difference between adjacent interior angles is controlled to be 0.01° or more (facilitating identification) while the difference between diametrically opposed interior angles is kept at 0.03° or less (preventing image defects), thus resolving the technical contradiction through precise asymmetric design.
2Object-affected harmful factors
If the difference between interior angles is small to maintain image quality, then image defects are prevented, but reflection surface identification becomes difficult
Solution Approach 1:
The patent resolves this contradiction by implementing a controlled asymmetric design where the difference between adjacent interior angles is 0.01° or more, which is sufficient for BD signal-based identification, while the difference between diametrically opposed interior angles is constrained to 0.03° or less to prevent image defects. This selective asymmetry enables both identification and image quality maintenance.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the interior angle differences within specific ranges (0.01° or more for adjacent angles, 0.03° or less for opposed angles). By adjusting these angular parameters within defined boundaries, the system achieves both reflection surface identification capability and image defect prevention simultaneously.
3Manufacturing precision
If manufacturing precision is increased to ensure all reflection surfaces have identical optical characteristics, then optical consistency is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent applies parameter changes by accepting controlled variations in interior angles (0.01° or more difference between adjacent angles) rather than requiring identical optical characteristics for all reflection surfaces. This relaxation of manufacturing precision requirements, combined with the asymmetric design, reduces manufacturing complexity and cost while still enabling reliable reflection surface identification through BD signal analysis.
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 enables reliable identification of reflection surfaces and prevents image defects, even with manufacturing errors, by ensuring consistent BD signal periods and reducing the impact of manufacturing errors on image quality.
Implementation Method 1
a rotary polygon mirror configured to deflect the light beam emitted from the light source so that the light beam scans a surface of a photosensitive member
Data Source
AI summary
A light scanning apparatus, including: a light source configured to emit a light beam; and a rotary polygon mirror configured to deflect the light beam emitted from the light source so that the light beam scans a surface of a photosensitive member, wherein the rotary polygon mirror is formed in a four-sided polygon, and wherein a difference between a pair of diametrically opposed interior angles of the rotary polygon mirror is larger than 0.03°, and a difference between another pair of diametrically opposed interior angles of the rotary polygon mirror is 0.03° or less.