Bent Optical Path Zoom Lens for Compact High Ratio Imaging
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Solution Overview
Problem
Conventional zoom lenses with a bent optical path face challenges in achieving a compact size and high zoom ratio while maintaining optical performance, particularly in reducing decentering aberrations and ensuring sufficient brightness, especially at wide and telephoto ends.
Innovation Solution
The design incorporates a zoom lens with a reflecting member and four lens units, including a first lens unit with negative refractive power, a second lens unit with positive refractive power, a third lens unit with negative refractive power, and a fourth lens unit with positive refractive power, where the second lens unit moves closer to the first lens unit, and the third and fourth lens units adjust their distances to satisfy specific conditional expressions, optimizing the axial distances and focal lengths to minimize aberrations and enhance magnification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a zoom lens with a bent optical path is designed to achieve a high zoom ratio and compact size, then the device size is reduced and zoom capability is improved, but decentering aberrations increase and optical performance deteriorates
Solution Approach 1:
The patent employs dynamic movement of the third lens unit during zooming, where the axial distance between the second and third lens units changes non-linearly. The third lens unit moves closer to the second lens unit at intermediate focal lengths and farther at telephoto end, dynamically compensating for decentering aberrations that occur at different zoom positions while maintaining a compact overall structure.
Solution Approach 2:
The patent optimizes specific parameter relationships including the axial distances D23W and D34W at wide angle end, and the focal lengths f2 and f3 of the second and third lens units. By satisfying the conditional expression 0.05 < f3/|f2| < 0.2 and optimizing distance ratios, the design achieves high zoom ratio with reduced decentering aberrations through precise parameter control.
2Volume of moving object
If the axial distance between lens units is reduced to make the zoom lens compact, then the device size is reduced, but brightness and optical performance at wide and telephoto ends deteriorate
Solution Approach 1:
The patent uses dynamic adjustment of the third lens unit position during zooming to maintain sufficient brightness. The axial distance D23 between the second and third lens units is optimized to change during zooming, ensuring adequate light transmission and image brightness at both wide angle and telephoto ends while keeping the overall lens compact.
Solution Approach 2:
The patent employs asymmetric optical design with a negative lead configuration (first lens unit has negative refractive power) and asymmetric movement patterns. The third lens unit moves differently at wide angle versus telephoto end, with the axial distances optimized asymmetrically to maintain brightness performance across the zoom range in a compact form.
3Manufacturing precision
If the zoom lens is designed with multiple lens units to correct aberrations, then optical performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent divides the zoom lens into four functional lens units with specific refractive powers (negative, positive, negative, positive). This segmentation allows each unit to perform specific optical functions, achieving effective decentering aberration correction and maintaining compact size through optimized individual unit designs rather than requiring a larger number of elements.
Solution Approach 2:
The third lens unit serves multiple functions: it acts as a decentering aberration correction mechanism during zooming, contributes to focal length adjustment, and helps maintain brightness. This multi-functionality reduces the need for additional dedicated correction elements, simplifying the overall design while maintaining high optical performance.
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 results in a compact zoom lens with improved optical performance, reduced decentering aberrations, and sufficient brightness across the wide and telephoto ends, achieving a high zoom ratio while maintaining a small size and low manufacturing costs.
Implementation Method 1
a reflecting member having a reflecting surface that bends the optical path
Implementation Method 2
a first lens unit including the reflecting member and having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power
Implementation Method 3
an image pickup element disposed on the image side of the zoom lens and having an image pickup surface that receives an image formed by the zoom lens and converts it to an electrical signal
Data Source
AI summary
A zoom lens with a bent optical path includes, in order from the object side to the image side, a first lens unit including the reflecting member and having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power. During zooming from the wide angle end to the telephoto end, the second lens unit moves closer to the first lens unit only toward the object side, the third lens unit moves in such a way that it becomes closest to the second lens unit at an intermediate focal length position in the course of zooming as compared to the state at the wide angle end and the state at the telephoto end, and the fourth lens unit moves. The zoom lens satisfies a certain condition.