Rod Lens Array Overlap Degree Optimization for Uniform Illumination
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Solution Overview
Problem
Existing rod lens arrays face challenges in minimizing light quantity unevenness due to assembly errors, aged deterioration, and environmental factors, leading to decreased image brightness and resolution, particularly when the overlap degree exceeds 2.5.
Innovation Solution
A rod lens array is designed with an overlap degree of 2.55 or more and 4 or less, and an aperture angle of 0.1 or more but less than 0.22, along with a lens length of 4 mm or longer and an operation distance 1.1 to 2 times the lens length, to suppress light quantity unevenness and enhance resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the overlap degree of rod lens is increased to suppress light quantity unevenness, then the light quantity unevenness is reduced, but the brightness of the image is decreased
Solution Approach 1:
The patent applies parameter changes by optimizing the overlap degree to a specific range (2.55 ≤ m < 3.50) and controlling the aperture angle within (0.10 ≤ α < 0.22), thereby achieving a balance between suppressing light quantity unevenness and maintaining image brightness through precise parameter control
2Measurement precision
If the overlap degree is set to suppress light quantity unevenness, then the reading accuracy is improved, but assembly errors and environmental factors still cause performance deterioration
Solution Approach 1:
The patent applies preliminary action by pre-optimizing the rod lens array design with specific overlap degree and aperture angle parameters before assembly, creating a robust design that compensates for potential assembly errors and environmental variations, thereby maintaining performance stability without requiring post-assembly correction
Solution Approach 2:
The patent applies beforehand cushioning by designing the rod lens array with optimized parameters that create a margin of tolerance against assembly errors and environmental factors, cushioning the system against performance deterioration before it occurs
3Manufacturing precision
If the overlap degree exceeds 2.5 to improve light quantity uniformity, then the light quantity unevenness is suppressed, but the resolution is decreased
Solution Approach 1:
The patent resolves this contradiction by changing and optimizing two parameters simultaneously: setting the overlap degree in the range 2.55 ≤ m < 3.50 and the aperture angle in the range 0.10 ≤ α < 0.22, which together achieve both high light quantity uniformity and maintained resolution
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 effectively minimizes light quantity unevenness while maintaining high resolution, even under conditions of assembly errors or aged deterioration, by optimizing the overlap degree and aperture angle, ensuring uniform brightness and improved imaging performance.
Implementation Method 1
a technique of allowing light emitted from a light source to irradiate a document and allowing a CCD sensor to receive the reflected light through a rod lens array
Data Source
AI summary
A rod lens array is configured so that when a relation between R and r0 is set to be R≧r0≧0.8R, and the gradient index of the rod lens is approximate to n(r)2=n02{1−(g·r)2}, an overlap degree m, defined by m=X0/2R, is 2.55 or more and 4 or less and an aperture angle of the rod lens, represented by n0·g·r0, is 0.1 or more and less than 0.22. The array is capable of minimizing light quantity unevenness even where there may be assembly error or aged deterioration occurs. An equal-magnification imaging optical apparatus usefully includes a rod lens array.