Compact Zoom Lens with Aspherical Positive Element
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Solution Overview
Problem
Current zoom optical systems for mobile devices face challenges in miniaturization due to large moving distances of lens groups, high error sensitivity, and difficulty in producing compact, high-performance lenses with precise plane and curvature requirements, making them unsuitable for integration in personal digital assistants (PDAs) without compromising image quality or durability.
Innovation Solution
A zoom optical system comprising a first lens group with negative optical power and a second lens group with positive optical power, both composed of three or less lens elements, where the second lens group includes a positive lens element with a refractive index of 1.7 or more and at least one aspherical surface, satisfying specific conditional formulae to minimize moving distances and reduce error sensitivity, enabling compact and high-performance imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the number of lens elements in the second lens group is increased to achieve miniaturization, then the optical system size is reduced, but the load to the driving section increases and error sensitivity due to decentering increases
Solution Approach 1:
The patent changes the parameter of lens element count in the second lens group from 4 elements (prior art) to 3 or fewer elements (invention). This parameter change reduces the moving mass and complexity of the second lens group, thereby reducing the load on the driving section and minimizing error sensitivity to decentering during zooming operations, while still achieving the required optical performance and compact size.
2Adaptability or versatility
If the moving distance of lens groups is increased to achieve zooming function, then the zoom ratio is improved, but the optical system length increases and miniaturization becomes difficult
Solution Approach 1:
The patent employs dynamic zooming by moving only the second lens group (with positive optical power) along the optical axis, while keeping the first lens group (negative power) and third lens group (positive power) relatively fixed or moving minimally. This dynamic configuration achieves a zoom ratio of approximately 2.5x or 3x while maintaining a compact optical system length suitable for mobile devices, avoiding the need for large moving distances that would increase system length.
3Volume of moving object
If the optical system is designed for compact size, then the device portability is improved, but the image quality and manufacturing precision become difficult to maintain
Solution Approach 1:
The patent applies local quality by using aspherical surfaces specifically on the object-side surface of the positive lens element in the second lens group. This localized application of aspherical design corrects off-axis aberrations and maintains high image quality in the compact configuration without requiring excessive manufacturing precision across all lens surfaces. The aspherical surface is strategically placed where it provides maximum benefit for the given compact form factor.
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 achieves a compact, high-performance zoom optical system with reduced moving distances and suppressed error sensitivity, allowing for efficient zooming and improved image quality, suitable for integration in mobile devices like PDAs while maintaining mechanical precision and durability.
Implementation Method 1
The positive lens element has at least one aspherical surface
Data Source
AI summary
A zoom optical system has lens groups, and performs zooming by varying distances between the respective lens groups in an optical axis direction thereof. The zoom optical system has two or more lens groups having a negative optical power and a positive optical power in this order from an object side. The first lens group (Gr1) and the second lens group (Gr2) each have three or less lens elements. The second lens group (Gr2) includes a positive lens element having a refractive index of 1.7 or more. The positive lens element has at least one aspherical surface. With this arrangement, provided are a compact and superfine zoom optical system with a zoom ratio of about two to three times, an imaging lens device incorporated with the zoom optical system, and a digital apparatus loaded with the imaging lens device.