Compact Zoom Lens Design for Mirrorless Cameras
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lenses for mirror-less cameras face challenges in miniaturization and cost reduction due to increased outer diameters and complexity, particularly in the second lens group, which affects the total length and performance.
Innovation Solution
A compact zoom lens design comprising a first lens group with negative refractive power, a second lens group with positive refractive power and a stop, and a third lens group with positive refractive power, where only the first and second lens groups are moved to change magnification, utilizing a specific configuration of lenses with concave and convex surfaces and a cemented lens with aspherical surfaces to correct aberrations and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the most-image-side lens of the second lens group is a positive lens, then the refractive powers of the positive lenses are reduced, but the effective diameter of the second lens group enlarges, increasing outer diameters
Solution Approach 1:
The patent changes the type of the most-image-side lens from positive to negative, fundamentally altering the optical parameters of the second lens group. This parameter change allows the positive lenses within the group to maintain higher refractive powers while the negative lens on the image side compensates to control the overall effective diameter, thus resolving the contradiction between refractive power distribution and diameter enlargement.
2Device complexity
If the principal point of the second lens group is positioned at the image side, then the optical design is simplified, but the distance between the first and second lens groups must be increased, preventing total length reduction
Solution Approach 1:
The patent changes the position parameter of the principal point from the image side to the object side by modifying the lens configuration (making the most-image-side lens negative). This parameter change allows for a reduced distance between the first and second lens groups while maintaining proper optical function, thus enabling total length reduction without excessive simplification of the optical design.
3Adaptability or versatility
If the third lens group is moved to change magnification, then the zoom range is extended, but air flow around the imaging surface increases, causing dust adhesion
Solution Approach 1:
The patent extracts the magnification-changing function from the third lens group and assigns it exclusively to the first and second lens groups. By removing the movement of the third lens group, the harmful air flow that causes dust adhesion is eliminated, while the zoom range is maintained through the coordinated movement of the first and second lens groups.
4Ease of manufacture
If lenses are not cemented together, then manufacturing is simplified, but lens holding accuracy deteriorates, reducing overall performance
Solution Approach 1:
The patent merges two lenses into a cemented lens structure where the most-image-side negative lens is cemented to the preceding lens. This merging provides mechanical support and precise positioning for the negative lens, improving lens holding accuracy without significantly complicating the manufacturing process, thus resolving the contradiction between ease of manufacture and manufacturing precision.
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 achieves a compact and cost-effective zoom lens with improved aberration correction and reduced size, enabling miniaturization while maintaining performance across the zoom range.
Implementation Method 1
an L24 negative lens with a convex surface toward the image side, having at least one aspherical surface
Implementation Method 2
a cemented lens having a positive refractive power as a whole which is formed by an L22 positive lens with a convex surface toward the object side and an L23 negative lens with a concave surface toward the image side together
Implementation Method 3
a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power
Data Source
AI summary
A zoom lens substantially consists of a negative first lens group, a positive second lens group, and a positive third lens group; whereinthe first lens group substantially consists of a two negative lenses with concave surfaces toward the image side and a positive lens with a convex surface toward the object side;the second lens group substantially consists of a stop; a positive lens with a convex surface toward the object side; a positive cemented lens, which is formed by a positive lens with a convex surface toward the object side and a negative lens with a concave surface toward the image side together; and a negative aspherical lens with a convex surface toward the image side; andthe third lens group substantially consists of a positive lens.