Compact Zoom Lens for Thin Projector Design
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Solution Overview
Problem
Current projector units face challenges in achieving a compact, thin design while maintaining high image quality and the ability to project enlarged images on large screens, especially when used with DMDs, due to limitations in lens aperture and optical system design.
Innovation Solution
A compact zoom lens system comprising multiple lens groups with specific refractive powers and configurations, including meniscus-shaped lens elements, that satisfy conditional expressions for aperture, image circle size, angle of view, and brightness, allowing for miniaturization without compromising image quality or increasing thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the lens aperture is reduced to make the projector thinner, then the thickness is reduced, but the image quality and brightness deteriorate
Solution Approach 1:
The optical system is divided into multiple lens groups (first through fourth lens groups) with alternating positive and negative refractive powers. This segmentation allows each group to contribute differently to light gathering and image formation, enabling compact design while maintaining brightness through optimized light path management across segmented components.
Solution Approach 2:
The patent applies specific conditional expressions that define optimal parameter ranges: 0.85 < Fno/(2ω) < 1.60 for aperture-angle balance, 0.50 < f/Fno < 2.00 for focal length control, and 0.70 < d1/f < 1.30 for first lens group positioning. These parameter optimizations enable thin design while preserving image quality and brightness.
2Volume of moving object
If the lens system is miniaturized to reduce projector size, then the projector becomes more compact, but the ability to project high-quality images on large screens deteriorates
Solution Approach 1:
The patent implements a zoom lens mechanism that dynamically adjusts focal length by moving lens groups relative to each other. The conditional expression 0.30 < (f2-f1)/(f2+f1) < 0.70 ensures optimal zoom range for projecting variable-size images on screens while maintaining image quality throughout the zoom range, enabling high-quality projection from a compact form factor.
Solution Approach 2:
Each lens group comprises multiple lens elements with different refractive powers (positive and negative). This composite structure allows the compact lens system to correct optical aberrations effectively while maintaining small size, ensuring high image quality projection capability.
3Area of stationary object
If the angle of view is increased to project larger images, then the projection coverage is improved, but the brightness and image quality deteriorate
Solution Approach 1:
The patent optimizes the relationship between F-number and angle of view through the conditional expression 0.85 < Fno/(2ω) < 1.60. This parameter balance ensures that as the angle of view increases for larger projection coverage, the F-number is adjusted accordingly to maintain adequate brightness, resolving the trade-off between projection area and illumination intensity.
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 the creation of a thin projector unit capable of projecting high-quality, enlarged images by optimizing the lens system's aperture, image circle, and angle of view, ensuring effective miniaturization and performance.
Implementation Method 1
a zoom lens including an optical system made up of a plurality of lens elements or a plurality of lens groups
Data Source
AI summary
In a thin projector for projecting an image from a light valve such as a DMD, a compact zoom lens comprises, in order, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens-group having a negative refractive power, and a fourth lens group having a positive refractive power. The fourth lens group is fixed while the focal length is being changed. The first and second lens group are movable on an optical axis in a direction from the enlarging side towards the reducing side over a range from a wide angle end to an intermediate range, and are movable on the optical axis in a direction from the reducing side towards the enlarging side over a range from the intermediate range to a telephoto end. The third lens group moves on the optical axis in a direction from the reducing side to the enlarging side over a range from the wide angle end to the telephoto end, whereby the focal length of the whole lens system of the zoom lens is changed.