Asymmetric Correction Lens for Laser Scanning Curvature Adjustment
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Solution Overview
Problem
Conventional light scanning devices experience significant shifting of the scanning line in the sub-scanning direction due to inaccuracies in component assembly, leading to curvature issues on the photoconductive drum, which affects image quality.
Innovation Solution
A light scanning device with a third optical system incorporating a correction lens that has different curvature radii for its incident and outgoing side surfaces, allowing rotation about an axis parallel to the main scanning direction and passing through the intersection of the optical axis and the surface with the smaller curvature radius, thereby adjusting the curvature of the laser scanning line while minimizing shifting in the sub-scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the fθ lens is rotated about its center to adjust the curving of the laser scanning line, then the curving accuracy is improved, but the scanning line shifts largely in the sub-scanning direction
Solution Approach 1:
The patent applies asymmetry by configuring the correction lens with asymmetric curvature radii where the incident side surface has a different curvature radius than the outgoing side surface. This asymmetric design allows the lens to correct scanning line curving while minimizing unwanted shifts in the sub-scanning direction when rotated for adjustment.
Solution Approach 2:
The patent utilizes parameter changes by varying the curvature radii of the lens surfaces. By setting specific curvature radius values for the incident and outgoing surfaces, the lens achieves optimal performance in correcting scanning line curving while maintaining stability in the sub-scanning direction during rotation.
2Manufacturing precision
If the correction lens is rotated to adjust curving of the laser scanning line, then the scanning line curvature is corrected, but the scanning line position shifts in the sub-scanning direction
Solution Approach 1:
The correction lens is designed with asymmetric curvature characteristics where the incident side surface and outgoing side surface have different curvature radii. This asymmetric configuration enables the lens to effectively correct scanning line curving while minimizing position shifts in the sub-scanning direction during rotation, thereby maintaining scanning line position stability.
Solution Approach 2:
The patent applies local quality by giving different curvature properties to different surfaces of the correction lens. The incident side surface and outgoing side surface are designed with specific, different curvature radii to optimize both curving correction and position stability in their respective functional areas.
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 precise adjustment of the laser scanning line curvature on the photoconductive drum while suppressing large shifts in the sub-scanning direction, ensuring accurate and stable image formation.
Implementation Method 1
a correction lens whose incident side surface and outgoing side surface in a cross section in the sub-scanning direction perpendicular to the main scanning direction have respective curvature radii different from one another
Data Source
AI summary
A rotational multifaceted mirror (24) deflects a laser light outgoing from a semiconductor laser (21), so that the light scanning device (2) which scans the photoconductive drum (131) has a third optical system (25) having a correction lens (5) whose curvature radii are different on the incident side surface (5a) and the outgoing side surface (5b) in a cross section in the sub-scanning direction which is perpendicular to the main scanning direction. The correction lens (5) is so configured as to be rotatable about a line (L2) which passes through an intersection “a” between an optical axis (L1) of the correction lens (5) and a surface having a curvature radius which is smaller among the surfaces (5a, 5b) and is rotatable about a line (L2) parallel to the main scanning direction.