Erecting Equal-Magnification Lens Array Defect Orientation
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Solution Overview
Problem
Image sensor units with erecting equal-magnification lens arrays that have optically discontinuous portions, such as chips, cracks, or scratches, suffer from degraded optical performance due to unintended scattering, reflection, or refraction, leading to issues like white streaks and reduced contrast in read images.
Innovation Solution
The method involves arranging the erecting equal-magnification lens array such that any optically discontinuous portions are positioned away from the document and towards the linear image sensor, preventing these defects from affecting the optical performance by minimizing light interference and maintaining the intended light path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an erecting equal-magnification lens array with optically discontinuous portions (chips, cracks, scratches) is used, then manufacturing cost increases and fabrication yield decreases, but optical performance degrades due to unintended scattering, reflection, and refraction causing white streaks and reduced contrast
Solution Approach 1:
The patent applies local quality by differentiating the tolerance requirements for optically discontinuous portions based on their location within the lens array. Defects in the first region (near the document) are acceptable, while defects in the second region (near the image sensor) are rejected. This localized differentiation allows higher fabrication yield by accepting defects that would otherwise cause rejection, while maintaining optical performance through selective acceptance criteria.
Solution Approach 2:
The patent implements preliminary action by establishing predetermined first and second regions within the lens array before manufacturing completes. The first region extends from the document side toward the image sensor, and the second region extends from the image sensor side toward the document. This preliminary spatial classification enables quality control decisions to be made in advance during manufacturing, preventing downstream rework and improving overall fabrication yield.
2Reliability
If optically discontinuous portions are present in the lens array, then manufacturing complexity increases due to inspection and sorting requirements, but optical performance is maintained if defects are properly positioned
Solution Approach 1:
The patent segments the lens array into distinct first and second regions based on their optical path characteristics. The first region is defined as extending from the document side toward the image sensor, while the second region extends from the image sensor side toward the document. This segmentation simplifies inspection and sorting processes by providing clear spatial criteria for accepting or rejecting defects, reducing the complexity of quality control compared to uniform inspection approaches.
Solution Approach 2:
The patent applies local quality by differentiating the tolerance requirements for optically discontinuous portions based on their location within the lens array. Defects in the first region (near the document) are acceptable, while defects in the second region (near the image sensor) are rejected. This localized differentiation allows higher fabrication yield by accepting defects that would otherwise cause rejection, while maintaining optical performance through selective acceptance criteria.
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 approach prevents degradation of optical performance, allowing for the production of image sensor units that maintain high image quality even with defects, thereby improving fabrication yield and reducing manufacturing costs by reusing previously rejected products.
Implementation Method 1
an erecting equal-magnification lens array that includes a plurality of single lenses arranged in the main scanning direction and condenses a light reflected from the document
Implementation Method 2
a phenomenon outside the design such as a flare occurs due to unintended scattering, reflection, refraction, etc. at the interface or in the interior of the optically discontinuous portion
Data Source
AI summary
There is provided a method of manufacturing an image sensor unit, the image sensor unit including: a linear light source that illuminates a document along a main scanning direction; a rod lens array that includes a plurality of rod lenses arranged in the main scanning direction and condenses a light reflected from the document; and a linear image sensor that receives a light condensed by the rod lens array. When a rod lens having an optically discontinuous portion on a surface and/or interior of the rod lens is included, the rod lens array is arranged such that the optically discontinuous portion is not located toward the document.