Optical Scanning Device Multi-Tier Polygon Mirror Common Light Source
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Solution Overview
Problem
Conventional tandem-compatible image forming apparatuses with multiple photoconductors require an increase in light sources, leading to color drift, increased costs, and higher failure probabilities due to semiconductor laser deterioration, while attempts to reduce light sources limit scanning speed and increase in the number of deflecting mirrors.
Innovation Solution
An optical scanning device utilizing a common light source with a deflecting unit featuring multi-facet reflecting mirrors on a common rotation axis, where beams are split and directed to scan different surfaces by shifting the tiers of mirrors, satisfying specific angle conditions to achieve efficient scanning without increasing the number of light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple light sources are used in a tandem system, then scanning speed and productivity are improved, but color drift occurs due to wavelength differences and cost increases due to more components
Solution Approach 1:
The patent combines multiple light sources (red, green, blue lasers) into a single integrated light source unit that emits multiple wavelengths simultaneously. This single unit uses a shared optical path and common scanning mechanism (polygon mirror), merging what would traditionally be separate scanning systems into one unified device, thereby maintaining high scanning speed while reducing component count and eliminating color drift
Solution Approach 2:
The patent creates a universal light source and scanning system that handles multiple colors (wavelengths) through a single apparatus. The common light source unit is designed to emit multiple wavelengths, and the single polygon mirror deflects all wavelengths to scan multiple photoconductors, making the system multi-functional rather than requiring separate dedicated systems for each color
2Adaptability or versatility
If multiple light sources are used, then scanning different surfaces is enabled, but failure probability increases due to semiconductor laser deterioration
Solution Approach 1:
By merging multiple light sources into a single integrated unit with a shared scanning mechanism, the patent reduces the total number of independent components that could fail. The single polygon mirror and common optical path eliminate multiple potential failure points, thereby improving reliability while maintaining the ability to scan different photoconductor surfaces
3Device complexity
If a common light source is used with deflecting mirrors, then the number of light sources is reduced, but the number of deflecting mirror faces is limited to two at maximum
Solution Approach 1:
The patent transitions from a two-dimensional arrangement (single plane of mirrors) to a three-dimensional configuration by stacking multiple polygon mirrors in different tiers or layers. This vertical stacking allows more than two mirror faces to be utilized while maintaining a compact structure, thereby increasing scanning speed without requiring additional light sources
4Adaptability or versatility
If polygon mirrors are overlapped in two tiers with phases shifted, then scanning different surfaces is enabled, but ghost light is generated
Solution Approach 1:
The patent applies different local qualities to different parts of the optical system: specific mirror surface treatments (e.g., selective reflectivity or absorption coatings) are applied to different tiers of polygon mirrors, and aperture stops or beam shutters are positioned at specific locations to block ghost light paths. This localized control eliminates harmful ghost light while preserving the multi-surface scanning capability
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 allows for high-speed scanning with reduced component count, lower failure probabilities, and improved recyclability, while maintaining image quality and reducing ghost light generation, enabling efficient scanning of multiple photoconductors with a single light source.
Implementation Method 1
a deflecting unit (7) having a plurality of tiers of multi-facet reflecting mirrors on a common rotation axis
Implementation Method 2
a light flux splitting unit that splits beams from the common light source and makes the split beams incident on mutually different tiers of reflecting mirrors
Implementation Method 3
a scanning optical system that guides the beams made to scan from the deflecting unit to the surfaces to be scanned
Data Source
AI summary
A light flux emitted from a light source is split into two by a light flux splitting unit, and these are respectively made incident on upper and lower tiers of polygon mirrors of a deflecting unit which coaxially rotates two polygon mirrors one on the other while being shifted in angles from each other. The respective light fluxes that have been deflected for scanning at mutually different timings by the deflecting unit respectively reach individual photodetectors through a first scanning lens, mirrors, and a second scanning lens as a predetermined light system and carry out main scanning.