Compact Zoom Lens Design with Segmented Units
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving a compact size while maintaining high optical performance and being robust to manufacturing errors, with issues such as long overall lens length and difficulty in moving large prism elements, particularly in wide-angle areas.
Innovation Solution
A zoom lens design comprising four or more lens units with specific refractive powers and configurations, including a first lens unit with three or less lenses, a second lens unit with a spherical and cemented lens, and a third lens unit, where distances between lens units vary during zooming to correct aberrations and reduce size, and a diaphragm to control the light beam, satisfying specific conditions for refractive power and surface shape factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zoom lens uses a conventional design with multiple lens units to achieve high optical performance, then the optical performance is improved, but the overall lens length becomes long and the size increases
Solution Approach 1:
The zoom lens is divided into multiple lens units (first lens unit with positive refractive power, second lens unit with negative refractive power, third lens unit with positive refractive power, and fourth lens unit with positive refractive power). Each lens unit is responsible for specific optical functions, allowing the system to achieve high optical performance while maintaining a compact overall structure through functional segmentation.
Solution Approach 2:
The patent employs a complex zooming mechanism where distances between lens units vary in different dimensions during zooming. Specifically, the distance between the first and second lens units widens while the distance between the second and third lens units narrows, creating a multi-dimensional movement pattern that achieves high magnification variation ratio (7.1×) within a compact form factor.
2Adaptability or versatility
If the first lens unit includes a large prism element to achieve high magnification and thin thickness, then the magnification is improved, but the first lens unit becomes difficult to move and the overall lens length increases in wide-angle area
Solution Approach 1:
The patent extracts the prism element from the first lens unit and relocates it to the second lens unit. This extraction allows the first lens unit to consist of only three or less lenses, making it lightweight and easy to move during zooming and focusing operations, while the second lens unit handles the prism element for achieving the high magnification variation ratio (7.1×).
Solution Approach 2:
The patent changes the refractive power distribution among lens units, with the second lens unit having a strong negative refractive power and the fourth lens unit having a strong positive refractive power. This parameter optimization allows the system to achieve high magnification variation ratio without requiring a large prism element in the first lens unit, improving its movability.
3Length of moving object
If the zoom lens is designed to be compact with fewer lenses, then the size is reduced, but the robustness to manufacturing errors decreases
Solution Approach 1:
The patent employs composite lens designs, particularly in the second lens unit which includes a cemented lens formed by cementing a negative lens and a positive lens. This composite structure provides degrees of freedom for aberration correction and improves robustness to manufacturing errors. The fourth lens unit also uses a cemented lens structure with specific refractive index and Abbe number requirements to enhance manufacturing tolerance.
Solution Approach 2:
The patent designs the zoom lens with dynamic adjustment capabilities where distances between lens units vary during zooming. The first lens unit moves during zooming, and the fourth lens unit moves during focusing, allowing the system to dynamically compensate for manufacturing errors and maintain high optical performance across the zoom range despite compact dimensions.
4Reliability
If the second lens unit includes a cemented lens with negative and positive power lenses, then the aberration correction is improved, but the device complexity increases
Solution Approach 1:
The cemented lens in the second lens unit serves multiple functions simultaneously: it corrects spherical aberration, coma, and chromatic aberration, while also contributing to the overall negative refractive power of the second lens unit. This multi-functionality reduces the need for additional separate correction elements, balancing aberration correction with device complexity.
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 design results in a compact zoom lens that corrects spherical aberration and coma effectively, is robust to manufacturing errors, and maintains high optical performance across the zoom range, ensuring a small size and high magnification variation ratio.
Implementation Method 1
a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side, first, second and third lens units having positive, negative and positive refractive powers. The first lens unit moves during zooming. During zooming from a wide-angle end to a telephoto end, a distance between the first and second lens units widens, and a distance between the second and third lens units narrows. The first lens unit consists of three or less lenses. The second lens unit consists of, in order from the object side to the image side, a first single lens as a spherical lens having a negative refractive power, a cemented lens in which a lens having a negative refractive power and a lens having a positive refractive power are cemented, and a second single lens as a spherical lens having a negative refractive power. A predetermined condition is satisfied.