Oblique Incident f-Theta Lens for Compact Laser Scanning
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Solution Overview
Problem
The existing light scanning systems for color laser printers are complex and costly due to the need for multiple optical components and defectors, which complicates manufacturing and affects image quality, particularly in achieving desired scan line curvature characteristics.
Innovation Solution
A light scanning system where light beams are obliquely incident on a plane perpendicular to the rotational axis of a deflector, using f-θ lenses with specific curvature radius ratios and eccentricity to reduce field curvature and magnification deviations, and eliminating reflective mirrors between f-θ lenses and photosensitive media to simplify assembly and production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple reflective mirrors and f-θ lenses are disposed in optical paths to direct light beams at different heights, then the light scanning system can scan multiple light beams onto photosensitive drums, but the deflector thickness increases and the f-θ lenses have larger effective surfaces, making it difficult to manufacture the system compactly
Solution Approach 1:
The patent combines multiple optical functions into a single f-θ lens by optimizing its curvature radii. The lens simultaneously performs beam focusing and scan line curvature correction that previously required separate components, thereby reducing the overall system thickness and component count while maintaining the ability to scan multiple light beams onto different photosensitive drums
Solution Approach 2:
The patent applies specific parameter changes to the f-θ lens curvature radii (R1 and R2) to achieve optimal optical performance. By setting R1 between 0.05f and 0.15f and R2 between 0.25f and 0.35f, the lens achieves both compact size and the required scanning functionality for multiple light beams
2Manufacturing precision
If two or more f-θ lenses are disposed in each optical path to reduce and correct scan line curvature, then the curvature correction is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the functions of multiple f-θ lenses into a single optimized lens. By combining beam focusing and scan line curvature correction into one component with specifically designed curvature radii, the system achieves the required manufacturing precision while reducing the number of components and simplifying assembly
Solution Approach 2:
The patent uses parameter changes in the form of optimized curvature radius ratios (R1/R2) to achieve both beam focusing and scan line curvature correction in a single lens, eliminating the need for multiple lenses while maintaining or improving manufacturing precision
3Ease of operation
If a plurality of reflective mirrors are disposed between f-θ lenses and photosensitive drums, then light beams can be directed to corresponding photosensitive drums, but scan lines may be skewed when the mirrors are assembled
Solution Approach 1:
The patent extracts and eliminates the reflective mirrors from the optical path between the f-θ lens and photosensitive drums. By removing these intermediate components, the system avoids the scan line skew problems associated with mirror alignment while maintaining the ability to direct light beams to the correct photosensitive drums through the optimized lens design
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 enhances scan line curvature characteristics, reduces system thickness, and improves manufacturing ease and image quality by minimizing field curvature and magnification deviations, leading to more efficient and cost-effective production of color laser printers.
Implementation Method 1
a deflector to deflect the emitted light
Implementation Method 2
one or more f-θ lenses to focus the deflected light onto a photosensitive medium
Data Source
AI summary
A light scanning system and an image forming apparatus including the same, the light scanning system including: one or more light sources to emit light; a deflector to deflect the emitted light; and one or more f-θ lenses to focus the deflected light onto a photosensitive medium, wherein the light emitted by the one or more light sources is obliquely incident on a plane perpendicular to a rotational axis of the deflector, and the f-θ lens satisfies −0.5<R1/R2<0.2, where R1 is a curvature radius of an entrance surface of the respective f-θ lens in a main-scanning direction and R2 is a curvature radius of an exit surface of the respective f-θ lens in the main-scanning direction.