Projection Zoom Lens Inversion for Compact Telephoto Operation
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Solution Overview
Problem
Current projection zoom lenses face challenges in achieving a high zoom ratio, small F number, and compact size while maintaining favorable projection performance, particularly in realizing telephoto operation and miniaturization simultaneously.
Innovation Solution
A projection zoom lens configuration with six lens groups, including a fixed negative first lens group and a positive sixth lens group, with four moving lens groups in between, where the second lens group moves towards the magnification side during zoom, and specific refractive power distributions and focal length relationships are optimized to satisfy conditional formulas for telecentric reduction, miniaturization, and high zoom ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the second lens group moves toward the reduction side when changing magnification from wide angle end to telephoto end, then telephoto operation can be realized, but the lens diameter increases and miniaturization becomes difficult
Solution Approach 1:
The patent inverts the conventional movement direction of the second lens group. Instead of moving toward the reduction side (conventional approach), the second lens group moves toward the magnification side when changing from wide angle to telephoto. This inversion enables telephoto operation while suppressing lens diameter increase, resolving the contradiction between telephoto capability and miniaturization.
2Adaptability or versatility
If three positive lenses are sequentially provided toward the reduction side to achieve high zoom ratio, then telephoto operation is improved, but the F number increases and compactness deteriorates
Solution Approach 1:
The patent changes the refractive power distribution and movement parameters of lens groups. Specifically, the second lens group is configured with positive refractive power and moves toward the magnification side, while the fifth lens group uses a negative lens toward the reduction side. This parameter optimization achieves high zoom ratio while maintaining a small F number, avoiding the need for three sequential positive lenses.
3Adaptability or versatility
If the lens configuration is optimized for telephoto operation, then zoom ratio increases, but the structure becomes more complex and miniaturization becomes difficult
Solution Approach 1:
The patent implements dynamic lens group configuration where the second, third, fourth, and fifth lens groups move when changing magnification, while the first and sixth lens groups remain fixed. This dynamic arrangement enables high zoom ratio and telephoto operation without requiring excessive structural complexity, as the movement of fewer lens groups is optimized to achieve the desired optical performance.
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 solution enables a compact, versatile projection zoom lens with a high zoom ratio, small F number, and improved projection performance, effectively addressing the limitations of existing lenses in terms of telephoto operation and miniaturization.
Implementation Method 1
a first lens group having a negative refractive power, second through fifth lens groups that move when changing magnification, and a sixth lens group having a positive refractive power
Data Source
AI summary
A projection zoom lens has a negative first lens group which is fixed when changing magnification, second through fifth lens groups that move when changing magnification, and a positive sixth lens group which is fixed when changing magnification, in this order from a magnification side. The reduction side is telecentric. When changing magnification from a wide angle end to a telephoto end, the second lens group moves toward the magnification side. The first and second lenses from the reduction side of the fifth lens group are a positive lens and a negative lens, respectively. The sixth lens group is constituted by a single positive lens. The projection zoom lens satisfies a predetermined Conditional Formula.