Zoom Lens Compact Design Using Reflector and Plastic Lenses
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Solution Overview
Problem
Conventional zoom lenses face challenges in achieving a balance between compact size, high zoom ratio, and good image quality while maintaining low costs, particularly due to the limitations of plastic lenses in terms of moisture and light absorption.
Innovation Solution
A zoom lens design comprising six lens groups with specific refractive powers, including aspheric and free-form lenses, where the second, fourth, and fifth lens groups are moved along the optical axis for zooming, combined with a stop and filter for light flux control, and a reflector to optimize compactness and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic lenses are used to reduce cost, then manufacturing cost is reduced, but image quality deteriorates due to moisture and light absorption
Solution Approach 1:
The patent employs a composite lens structure where a plastic lens is combined with a reflective element (mirror or prism). The plastic lens handles the bulk of light focusing at low cost, while the reflective element compensates for chromatic aberrations and light absorption issues, achieving both cost reduction and maintained image quality
Solution Approach 2:
A reflective intermediary element is introduced between the plastic lens and the image sensor. This intermediary reflects light back through the plastic lens, effectively correcting optical path defects and reducing the impact of plastic material limitations on image quality
2Reliability
If the number of lens groups is increased to improve image quality, then image quality is improved, but device complexity increases
Solution Approach 1:
The optical system is divided into distinct functional segments: plastic lenses for cost-effective focusing, a reflective element for aberration correction, and a minimal number of additional glass lenses only where absolutely necessary. This segmentation allows each component to perform its specific function efficiently without unnecessary complexity
Solution Approach 2:
The reflective element is extracted from the traditional all-refractive lens group structure. By taking out the function of chromatic aberration correction from the lens groups and assigning it to a separate reflective component, the overall lens group complexity is reduced while maintaining or improving image quality
3Volume of moving object
If compact size is reduced for portability, then device size is reduced, but zoom ratio capability deteriorates
Solution Approach 1:
The reflective element is nested within the compact lens assembly, utilizing the same optical path space. The mirror or prism is positioned to reflect light back through the existing plastic lenses, effectively doubling the optical path length within a compact form factor, thereby achieving high zoom ratio in a small volume
Solution Approach 2:
The reflective element introduces a dimensional change in the light path by folding it back through the lens system. This creates an effective increase in optical path length without increasing the physical length of the lens assembly, enabling high zoom ratio in a compact design
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 results in a zoom lens with a compact size, lower cost, and improved image quality, meeting conditions for a high zoom ratio and minimizing aberrations and distortion.
Implementation Method 1
a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group having positive refractive power
Implementation Method 2
a reflector to optimize compactness and image quality
Data Source
AI summary
An embodiment of this invention provides a zoom lens, which primarily includes, in order from an object side to an image-forming side, a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; a fifth lens group having negative refractive power; and a sixth lens group having positive refractive power; wherein the first lens group comprises a prism, and the second lens group, the fourth lens group, and the fifth lens group are moved toward the third lens group along an optical axial for zooming from a wide-angle end to a telephoto end.