Image-Reading Lens Aberration Correction via Group Segmentation
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Solution Overview
Problem
Existing image-reading lenses with a smaller number of lenses, like those described in Japanese Patent Number 3939908, are limited to a maximum 45° angle of view and struggle to correct various aberrations effectively, especially in miniaturized devices with high-speed image reading requirements.
Innovation Solution
An image-reading lens system with a front-group and rear-group lens system, each comprising fewer than 6 lenses, where the rear-group lens system has a negative lens on the image side, allowing for an angle of view of 56° or more, with adjustable focal length and image plane changes to correct aberrations efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of lenses is reduced to fewer than 6 lenses, then the device complexity is reduced and miniaturization is achieved, but the ability to correct various aberrations deteriorates
Solution Approach 1:
The lens system is divided into two distinct groups: a front-group lens system (with 1-5 lenses) and a rear-group lens system (with 1-2 lenses). This segmentation allows each group to be optimized for specific functions - the front group for primary image formation and the rear group for aberration correction - achieving effective aberration correction with fewer total lenses
Solution Approach 2:
The patent applies local quality by assigning different optical characteristics to different parts of the lens system. The rear-group lens system specifically uses a negative lens on the image side with particular curvature radius relationships (satisfying conditional expressions [2] and (3)) to provide localized aberration correction where it is most needed, while the front group handles primary focusing
2Adaptability or versatility
If the angle of view is increased to 56° or more, then the field of view is expanded, but the difficulty of correcting various aberrations increases
Solution Approach 1:
The patent employs dynamic adjustment mechanisms that allow the lens system to adapt its optical characteristics. The front-group and rear-group lens systems can be adjusted relative to each other, enabling the system to maintain optimal aberration correction across the expanded 56° or greater angle of view by dynamically compensating for aberrations that arise at wider angles
Solution Approach 2:
The patent changes key optical parameters to achieve wider angle of view while maintaining aberration correction. Specifically, it uses a negative lens on the image side of the rear-group system with controlled curvature radii (Rb and Rc satisfying expression (2), and Ra/Rb satisfying expression (3)), which allows the system to expand the angle of view to 56° or more while the parameter relationships ensure aberrations remain corrected
3Adaptability or versatility
If the focal length is made adjustable, then the versatility of the image-reading lens is improved, but the device complexity increases
Solution Approach 1:
The patent merges the focusing and aberration correction functions into a unified lens system architecture. The front-group and rear-group lens systems work together as an integrated unit where adjusting the distance between groups simultaneously achieves focal length adjustment and maintains aberration correction, avoiding the need for separate adjustment mechanisms and reducing overall complexity
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
The solution enables a high-performance image-reading lens with a wider angle of view and effective aberration correction, maintaining miniaturization and high image quality while reducing the number of lenses compared to Gauss-type lenses.
Implementation Method 1
an image-reading lens for reading a manuscript image... an optical image of a manuscript to be read is reduced and formed by an image-reading lens
Data Source
AI summary
An image-reading lens includes front-group and rear-group lens systems which are arranged on an object side and an image side, respectively. The front-group lens system includes equal to or less than 5 lenses which include at least one positive lens and at least one negative lens, and the rear-group lens system includes one negative lens. An angle of view of an entire system of the image-reading lens is equal to or more than 56°. The front-group and rear-group lens systems are structured such that with respect to a change in a distance between the front-group and rear-group lens systems, a change in a focal length of the entire system of the image-reading lens is small, and a change in an image plane is large, and by adjusting the distance between the front-group and rear-group lens systems, a required lens performance is obtained.