VCSEL Optical Scanning Curvature Correction
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Solution Overview
Problem
Conventional methods for correcting curvature in the sub-scanning direction of scanning lines in multi-beam optical scanning devices, such as those using VCSELs, fail to accurately address differences in curvature values between laser beams, leading to color misregistration and reduced image quality.
Innovation Solution
An optical scanning device equipped with a curvature value detection unit and a curvature correction unit that detects and corrects curvature values for each scanning line, allowing for precise curvature correction in the sub-scanning direction, reducing data storage needs, and shortening correction time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the number of laser beams is increased to several ten to meet high speed and high resolution demands, then the scanning speed and resolution are improved, but the laser beams distribute widely in the sub-scanning direction causing curvature differences between scanning lines
Solution Approach 1:
The patent applies local quality by detecting and correcting curvature values individually for each laser beam (each scanning line) rather than applying a uniform correction. The curvature value detection unit measures curvature for each scanning line, and the curvature correction unit adjusts each line's curvature according to its specific characteristics, allowing different scanning lines to have customized correction parameters that account for their specific positions and aberrations.
2Device complexity
If conventional mechanical mirror bending or uniform curvature correction is used, then the correction process is simple, but the difference in curvature value between scanning lines cannot be eliminated leading to color misregistration
Solution Approach 1:
The patent segments the curvature correction process into individual scanning line corrections. Instead of treating all scanning lines uniformly, the system divides the correction task by detecting curvature values for each scanning line separately and applying specific corrections to each line. This segmentation allows precise control over each scanning line's curvature while maintaining overall system simplicity through automated detection and correction.
Solution Approach 2:
The patent implements feedback by using the curvature value detection unit to measure actual curvature deviations and feed this information back to the curvature correction unit. The detection unit measures curvature for each scanning line, provides this data as feedback, and the correction unit uses this feedback to adjust the scanning lines accordingly, creating a closed-loop system that continuously refines curvature correction accuracy.
3Manufacturing precision
If curvature correction is performed for all scanning lines individually, then color misregistration is eliminated, but data storage requirements and correction time increase
Solution Approach 1:
The patent applies partial action by detecting curvature values for a representative sample of scanning lines (such as scanning lines at specific positions like center and edges) rather than measuring all scanning lines exhaustively. The curvature correction unit then uses these partial measurements to infer and correct curvature for all scanning lines, reducing the total data storage requirements while maintaining adequate correction accuracy for color registration.
Data Source
AI summary
An optical scanning device which forms a plurality of scanning lines in parallel in a main scanning direction on a photosensitive member by a plurality of laser beams detects the curvature values in the sub-scanning direction of the scanning lines, and corrects a curvature value in the sub-scanning direction corresponding to each of the scanning lines. When detecting the curvature value, the optical scanning device detects the curvature values in the sub-scanning direction of two scanning lines, and calculates the curvature value in the sub-scanning direction of a scanning line between the two scanning lines based on the detected curvature values in the sub-scanning direction of the two scanning lines. With this arrangement, the curvatures in the sub-scanning direction of scanning lines are corrected effectively with high accuracy for all laser beams in a multi-beam optical scanning device using a VCSEL or the like.