Erecting Equal-Magnification Lens Array Unit Depth of Field
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Solution Overview
Problem
Erecting equal-magnification optical systems in image reading and forming devices face challenges with narrow depth of field, leading to image blurring when the object is not in close contact with the cover glass, and existing solutions do not adequately meet the requirements for compactness and image quality.
Innovation Solution
An erecting equal-magnification lens array unit is designed with a first and second lens array, where the optical axes overlap, and a light blocking portion with apertures, satisfying specific expressions to expand the depth of field and ensure telecentricity, reducing the influence of foreign material and stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an erecting equal-magnification optical system using Selfoc lenses or rod lenses is used, then the optical system can be made compact, but the depth of field becomes narrow causing image blurring when the object is not in close contact with the cover glass
Solution Approach 1:
The patent divides the optical system into two separate lens arrays (first lens array and second lens array) with a light blocking portion between them. This segmentation allows independent optimization of each array's function while maintaining the overall compact erecting equal-magnification capability, and the light blocking portion helps extend the depth of field by controlling light paths from different object distances
Solution Approach 2:
The light blocking portion with apertures acts as an intermediary element between the two lens arrays. It selectively blocks stray light and foreign material while allowing useful light to pass through, thereby extending the depth of field and improving image quality without compromising the compact design
2Ease of manufacture
If a lens array plate with convex surfaces is used instead of Selfoc lenses, then manufacturing becomes easier, but the erecting equal-magnification optical system characteristics are insufficient
Solution Approach 1:
By dividing the system into two lens arrays with specific functional divisions, the patent achieves both manufacturability (using conventional convex lens surfaces) and optical performance (erecting equal-magnification characteristics). Each array can be manufactured separately with standard techniques while the combined system delivers the required optical properties
Solution Approach 2:
The patent assigns different local functions to different parts of the optical system. The first lens array handles specific optical functions while the second lens array handles complementary functions, with the light blocking portion controlling light paths. This local functional differentiation allows each component to be optimized for its specific role, achieving both ease of manufacture and high optical precision
3Reliability
If the imaging position is positioned between the first lens array and the second lens array, then the depth of field is expanded and image quality is improved, but the device structure becomes more complex
Solution Approach 1:
The patent uses segmentation to create a modular structure with two lens arrays and a light blocking portion. While this increases structural elements, each module serves a specific function that collectively simplifies the overall design compared to attempting to achieve the same depth of field extension in a single lens system. The segmentation enables independent optimization and easier alignment
Solution Approach 2:
The light blocking portion serves multiple functions: it blocks stray light, prevents foreign material from affecting the image, controls light paths to extend depth of field, and maintains the compact form factor. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving improved image quality
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 enhances the depth of field and image quality by positioning the imaging point between the lens arrays, reducing the impact of foreign material and stray light, and maintaining image clarity even when the object is not in close contact with the cover glass.
Implementation Method 1
an optical system formed by each first lens and each second lens with overlapping optical axes is an erecting equal-magnification optical system
Data Source
AI summary
An erecting equal-magnification lens array unit includes a first lens array and a second lens array. The first lens array includes a plurality of first lenses. The second lens array includes a plurality of second lenses. The optical axes of the second lenses overlap with the optical axes of the first lenses. Each first lens and second lens with overlapping optical axes form a unit optical system. Each unit optical system is an erecting equal-magnification optical system. Each unit optical system is substantially telecentric on at least the object side. The imaging position, by each first lens, of an object is positioned between the first lens array and the second lens array.