Segmented Lens Unit for Rapid Focusing Weight Reduction
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Solution Overview
Problem
Existing optical systems for digital cameras face challenges in achieving rapid focusing while maintaining high optical performance, especially when the shortest image-pickup distance is shortened and the focal length is lengthened, due to difficulties in reducing the weight of the first lens unit and minimizing the moving amount during focusing.
Innovation Solution
The optical system consists of a first lens unit with positive refractive power that moves during focusing and a second lens unit with negative refractive power that remains stationary, divided into subunits with specific refractive powers to optimize weight reduction and aberration correction, ensuring high optical performance and rapid focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shortest image-pickup distance is shortened and the focal length is made longer, then the optical performance is improved, but the weight of the first lens unit increases and rapid focusing becomes difficult
Solution Approach 1:
The first lens unit is divided into three subunits (first subunit with positive refractive power, second subunit with negative refractive power, and third subunit with positive refractive power) separated by largest and second largest intervals. This segmentation allows each subunit to be optimized independently, reducing the overall weight of the first lens unit while maintaining the required optical performance for short image-pickup distances and long focal lengths.
2Reliability
If the shortest image-pickup distance is shortened and the focal length is made longer, then the optical performance is improved, but the moving amount during focusing increases and rapid focusing becomes difficult
Solution Approach 1:
By dividing the first lens unit into three subunits with specific refractive powers and intervals, the patent enables more efficient focusing motion. The segmented structure allows for reduced moving amount during focusing while maintaining high optical performance, as each subunit can be optimized for its specific function within the overall focusing mechanism.
Solution Approach 2:
Each subunit within the first lens unit is assigned a specific refractive power (positive, negative, positive) to optimize local optical properties. This local optimization allows the system to achieve both short image-pickup distance and long focal length performance while controlling the moving amount during focusing.
3Reliability
If the aperture ratio is made larger, then the optical performance is improved, but the weight of the first lens unit increases
Solution Approach 1:
The first lens unit is segmented into three subunits with alternating refractive powers, allowing the aperture ratio to be increased for better optical performance while the segmented structure keeps the weight manageable. Each subunit can be optimized for its specific role in handling the increased aperture.
Solution Approach 2:
By assigning different refractive powers to different subunits (positive, negative, positive), the patent optimizes local optical properties to handle larger aperture ratios efficiently. This local optimization allows increased aperture for better performance without proportionally increasing the weight of the first lens unit.
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 enables rapid focusing with high optical performance by reducing the weight of the first lens unit and minimizing its moving amount, while maintaining correction of various aberrations through the second lens unit, thus addressing the limitations of existing systems.
Implementation Method 1
a first lens unit having positive refractive power, and a second lens unit having negative refractive power arranged in order from the object side to the image side
Data Source
AI summary
An optical system includes, in order from an object side to an image side, a first lens unit having positive refractive power, and a second lens unit having negative refractive power, wherein the first lens unit moves and the second lens unit does not move during focusing, wherein the first lens unit includes a positive lens arranged closest on the object side of the first lens unit, wherein the second lens unit includes three or more lenses including at least two negative lenses, wherein the first lens unit consists of a first subunit having positive refractive power, a second subunit having negative refractive power, and a third subunit having positive refractive power arranged in order from the object side to the image side, and wherein predetermined conditional expressions are satisfied.