Zoom Lens Focusing Mechanism with Coordinated Lens Units
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving high optical performance over various object distances while maintaining fast focusing speed, as they often result in larger movement amounts of lens units, increased driving noise, and slower autofocus due to the heavy load on actuators, especially when focusing on close distances or at telephoto ends.
Innovation Solution
A zoom lens design that includes multiple lens units with negative and positive refractive powers, where specific lens units move in coordinated directions during focusing, optimizing the movement to minimize aberration variations and reduce the load on actuators, allowing for high-speed autofocus across all object distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the first lens unit (with the longest effective diameter and heaviest weight) is moved during focusing, then focusing coverage is achieved, but focusing speed becomes slower and driving noise becomes louder
Solution Approach 1:
The focusing function is segmented across multiple lens units. Instead of moving only the first lens unit, the patent divides the focusing action between the first lens unit (positive refractive power) and the fifth lens unit (negative refractive power). Both units move simultaneously during focusing, with their movement amounts coordinated to achieve the desired focusing effect while reducing the burden on any single lens unit.
Solution Approach 2:
The patent merges the focusing function across multiple lens units. The first lens unit and the fifth lens unit work together to achieve focusing, combining their refractive powers and movement effects. This distributed approach allows the system to achieve the same focusing coverage with reduced individual movement amounts, thereby improving focusing speed and reducing driving noise.
2Ease of operation
If the fifth lens unit is moved during focusing, then focusing is achieved, but variation of optical performance becomes larger and optical performance decreases when focusing to close distance objects
Solution Approach 1:
The optical performance correction function is segmented between multiple lens units. The first lens unit and the fifth lens unit each contribute to maintaining optical performance during focusing. By distributing the correction function across these units, the patent reduces the variation in optical performance that would occur if only the fifth lens unit moved.
Solution Approach 2:
Different lens units are assigned different roles in the focusing process. The first lens unit (with positive refractive power) and the fifth lens unit (with negative refractive power) have complementary functions. The first lens unit helps maintain optical performance at close distances, while the fifth lens unit contributes to overall focusing. This local specialization of functions ensures consistent optical performance across all focusing ranges.
3Device complexity
If only one lens unit moves during focusing, then device complexity is reduced, but variation of optical performance by focusing becomes larger
Solution Approach 1:
The focusing function is segmented between the first lens unit and the fifth lens unit. Instead of moving a single heavy lens unit, the patent divides the focusing action into two coordinated movements. This segmentation maintains relatively simple device complexity while significantly improving optical performance consistency during focusing.
4Reliability
If the fourth lens unit and sixth lens unit are moved during focusing, then optical performance is maintained, but movement amount of focus lens unit becomes larger at telephoto side
Solution Approach 1:
The patent applies local quality by assigning specific roles to lens units based on their refractive power and position. The first lens unit (positive) and fifth lens unit (negative) are configured with specific movement characteristics that optimize performance at different zoom ranges. This local optimization reduces the movement amount at telephoto sides while maintaining optical performance consistency.
Data Source
AI summary
A zoom lens includes a lens unit Lv positioned at the most object side of a plurality of lens units having the negative refractive power, a lens unit Lp positioned at the most object side of lens units having a positive refractive power, the lens units being positioned at an image side of the lens unit Lv, and lens units Fp and Fn respectively having a positive and a negative refractive power positioned at an image side of the lens unit Lp, the lens units Fp and Fn being configured to move during focusing. During focusing from infinity to minimum object distance, the lens unit Fp and the lens unit Fn move in the same direction in a wide angle range, and the lens unit Fp moves to an object side and the lens unit Fn moves to an image side in a telephoto range.