Three-Lens Imaging System with Aspheric Surfaces for Shutter Integration
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Solution Overview
Problem
Existing imaging lenses with three lenses face challenges in reducing size while maintaining high aberrational performance and securing sufficient spacing for a shutter mechanism, especially with increasing pixel density, as the optical aperture stop needs to be close to the object for telecentricity but poses difficulties for shutter arrangement.
Innovation Solution
A three-lens imaging lens configuration with a first positive refractive lens, a second negative refractive lens with a concave surface, and a third positive meniscus lens, featuring at least one aspheric surface, optimized by conditional expressions for focal lengths and Abbe numbers to ensure telecentricity, size reduction, and high aberrational performance, allowing for a shutter mechanism between the first and second lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical aperture stop is arranged close to the object to secure telecentricity, then telecentricity is improved, but the space for arranging a shutter mechanism is reduced
Solution Approach 1:
The imaging lens is divided into three separate lenses (first lens with positive refractive power, second lens with negative refractive power, and third lens with positive refractive power), allowing the aperture stop to be positioned close to the object for telecentricity while creating sufficient internal space between lenses for shutter mechanism arrangement
Solution Approach 2:
The shutter mechanism is positioned in the internal space between the first and second lenses, utilizing the third dimension (depth along optical axis) rather than only lateral space, thereby accommodating the shutter without compromising telecentricity
2Volume of moving object
If the overall lens size is reduced for compact imaging apparatus, then size reduction is improved, but the spacing between lenses for shutter arrangement is reduced
Solution Approach 1:
The patent optimizes specific parameters including the focal lengths of individual lenses (f1, f2, f3) and the spacing between them (D2) through conditional expressions, achieving compact overall size while maintaining sufficient internal spacing for shutter mechanism
Solution Approach 2:
The lens system uses a composite configuration combining positive and negative refractive power lenses with specific aspheric surface designs, achieving compact size while maintaining optical performance and internal spacing
3Measurement precision
If pixel density is increased for higher imaging performance, then imaging performance is improved, but the requirement for telecentricity and aberrational performance becomes more stringent
Solution Approach 1:
The patent employs aspheric surfaces on the lenses (specifically the first lens having a convex object-side surface and aspheric image-side surface, and the third lens having a meniscus form) to correct aberrations and maintain high imaging performance with increased pixel density
Solution Approach 2:
The lens system assigns different refractive powers and surface characteristics to each lens element, with the first lens providing positive refractive power with convex object-side surface, the second lens providing negative refractive power with concave object-side surface, and the third lens providing positive refractive power with meniscus form, optimizing aberrational performance for high pixel density imagers
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 configuration achieves a compact high-performance lens system with optimized power distribution and sufficient spacing for a shutter mechanism, maintaining high aberrational performance compatible with increased pixel density and ensuring telecentricity.
Implementation Method 1
a first lens having a positive refractive power; a second lens having a negative refractive power whose concave surface faces to the object; and a third lens having a positive refractive power
Data Source
AI summary
An imaging lens comprises, in order from an object side:a first lens having a positive refractive power;a second lens having a negative refractive power whose concave surface faces to the object; anda third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens;wherein the first, second and third lenses have at least one aspheric surface, andwherein the imaging lens satisfies conditional expressions given below:0.7<f1/f<1.3 (1)0.3<D2/f<0.5 (2)1.0<|f2/f|<3.0 (3)1.2<f3/f<4.0 (4)wheref: a focal length of an overall system,f1: a focal length of the first lens,f2: a focal length of the second lens,f3: a focal length of the third lens, andD2: a spacing, on the optical axis, between the first lens and the second lens.