Projection Lens Assembly with Aspheric Surfaces for Compact High-Resolution Design
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Solution Overview
Problem
Current projection lens assemblies fail to simultaneously achieve miniaturization, high resolution, large aperture, and resistance to environmental temperature changes, which are essential for modern projector requirements.
Innovation Solution
A projection lens assembly comprising multiple lens groups with specific refractive powers and surface configurations, including aspheric and spherical lenses, arranged along an optical axis with a stop between certain lens groups, allowing for adjustable focal lengths and optimized optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the projection lens assembly is miniaturized, then the volume is reduced, but the resolution and aperture may deteriorate
Solution Approach 1:
The projection lens assembly is divided into four lens groups (first lens group with negative refractive power, second lens group with positive refractive power, third lens group with negative refractive power, and fourth lens group with positive refractive power). This segmentation allows each group to be optimized for specific functions, enabling miniaturization while maintaining high resolution through coordinated optical design of individual groups.
Solution Approach 2:
The patent employs aspheric surfaces on specific lens elements (the first lens and fifth lens both have aspheric projection-side surfaces). These curved surfaces enable more efficient light control and focal point convergence within a compact form factor, achieving high resolution without increasing overall volume.
2Illumination intensity
If the aperture is increased to enhance output lumens, then the light gathering capability is improved, but the lens assembly size increases
Solution Approach 1:
The patent optimizes specific parameter ranges including the F-number (0.9 < F ≤ 1.3), focal length ratios (0.2 < f2/f1 < 0.4, 0.3 < f3/f2 < 0.6), and refractive indices (1.8 < Nd2 < 2.1, 1.6 < Nd3 < 1.8, 1.6 < Nd4 < 1.8). These parameter changes enable large aperture for high output lumens while controlling the physical size of the lens assembly through mathematical relationships between optical parameters.
3Measurement precision
If the lens assembly is designed for high resolution, then the image quality is improved, but the complexity of the lens structure increases
Solution Approach 1:
The lens assembly is segmented into four functional groups with alternating positive and negative refractive powers. This segmentation allows complex optical corrections to be distributed across simpler individual groups, achieving high image quality without excessive overall structural complexity.
Solution Approach 2:
Aspheric surfaces are applied to specific lens elements (first and fifth lenses) to correct aberrations and improve image quality. This targeted application of complex surface geometry to only where needed maintains overall structural simplicity while achieving high resolution.
4Adaptability or versatility
If the lens assembly resists temperature changes, then the environmental adaptability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies glass materials with particular refractive index and Abbe number ranges (1.8 < Nd2 < 2.1, 20 < Vd2 < 40; 1.6 < Nd3 < 1.8, 20 < Vd3 < 40; 1.6 < Nd4 < 1.8, 20 < Vd4 < 40). These composite material selections provide thermal stability and resistance to temperature-induced optical property changes, improving environmental adaptability.
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 provides a compact design with enhanced resolution, reduced temperature sensitivity, and improved optical performance, meeting the requirements of miniaturization, high resolution, and large aperture while maintaining excellent image quality across varying conditions.
Implementation Method 1
The first lens group is with negative refractive power
Implementation Method 2
The second lens group is with positive refractive power
Implementation Method 3
The first lens is an aspheric lens
Data Source
AI summary
A projection lens assembly includes a first lens group, a second lens group, a third lens group and a fourth lens group, all of which are arranged in order from a projection side to an image source side along an optical axis. The first lens group is with negative refractive power. The second lens group is with positive refractive power and includes a projection side surface and an image source side surface, wherein both of the projection side surface and the image source side surface are convex surfaces. The third lens group includes a convex surface facing the projection side. The fourth lens group is with positive refractive power and includes a convex surface facing the image source side. The projection lens assembly satisfies: 1.4<F<3.5, wherein F is an F-number of the projection lens assembly.