Zoom Lens Four Unit Design Reduces Weight
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Solution Overview
Problem
Conventional zoom lenses face challenges in widening the angle of view while reducing size and weight, maintaining adequate optical performance, and correcting aberrations across the entire imaging range, particularly in professional imaging devices like broadcasting and cinema cameras.
Innovation Solution
A zoom lens configuration with four lens units, including a first unit with positive refractive power, a second unit with negative refractive power that moves during zooming, a third unit with positive refractive power that moves non-linearly, and a fourth unit with positive refractive power that does not move, where specific focal length ratios and imaging magnifications are optimized to achieve a high zoom ratio and reduced size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If lens units with negative refractive power are arranged closer to the object side than the stop to widen the angle, then the angle of view is improved, but the diameter of lens units increases and size/weight reduction becomes difficult
Solution Approach 1:
The first lens unit is divided into three subunits (U11, U12, U13) with different refractive powers and movement characteristics. The negative power subunit U11 remains stationary while positive power subunits move during focusing, segmenting the functions to control diameter and weight while maintaining wide angle capability
Solution Approach 2:
Instead of having negative refractive power lens units closer to the object side (conventional approach), this patent inverts the arrangement by placing positive refractive power lens units in the first lens unit and using a negative power second lens unit, thereby achieving wide angle without increasing diameter
2Duration of action of stationary object
If the third lens unit has strong refractive power to achieve high zoom ratio, then magnification is improved, but the number of lenses increases and size/weight reduction becomes difficult
Solution Approach 1:
The patent optimizes the refractive power parameters of the third lens unit within specific ranges (0.3 < f3/fw < 1.5) rather than using strong refractive power, and combines this with optimized movement trajectories to achieve high zoom ratio without increasing lens count or weight
3Duration of action of stationary object
If the first lens unit configuration is changed to control the principal point for further angle widening, then the angle of view is improved, but the lens diameter increases
Solution Approach 1:
Dividing the first lens unit into three subunits with specific refractive powers and movement characteristics allows precise control of the principal point position without increasing diameter, as each subunit contributes differently to the overall optical function
Solution Approach 2:
The patent makes the first lens unit dynamically adjustable during focusing operations, with subunits U12 moving along a curved trajectory while U11 and U13 remain stationary, allowing principal point control without diameter increase
4Ease of operation
If conventional focus unit configurations are used, then focusing function is provided, but adequate correction of aberration variation and angle of field variation when object distance varies becomes difficult
Solution Approach 1:
The first lens unit is segmented into three subunits with different movement characteristics (U11 stationary, U12 curved trajectory, U13 stationary), allowing independent optimization of focusing function and aberration correction that cannot be achieved with conventional single-unit focus mechanisms
Solution Approach 2:
The patent implements dynamic focusing where the second lens subunit U12 moves along a curved trajectory during focus adjustment, enabling real-time correction of aberration variations and angle of field variations as object distance changes
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 configuration allows for a wide angle of view, high magnification, reduced size and weight, and maintains adequate optical performance by optimizing focal length ratios and movement trajectories of lens units, effectively addressing the limitations of existing technologies.
Implementation Method 1
a first lens unit having positive refractive power, which does not move for zooming
Implementation Method 2
a second lens unit having negative refractive power, which moves during zooming
Implementation Method 3
a third lens unit having positive refractive power, which moves during zooming
Implementation Method 4
a fourth lens unit having positive refractive power, which does not move for zooming
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side: a positive first lens unit; a negative second lens unit; a positive third lens unit; and a positive fourth lens unit, wherein the first lens unit includes a positive first lens subunit, which does not move for focusing, a positive second lens subunit, which moves during the focus adjustment, and a positive third lens subunit, which does not move for focusing; and focal lengths of the first lens unit, the second lens unit, the third lens unit, a magnification of the third lens unit U3 at a wide angle end, focal lengths of the first lens subunit, the second lens subunit appropriately satisfy certain relations.