Projection Lens with Aspherical Elements for Wide-Angle View
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Solution Overview
Problem
Current projector lenses struggle to achieve a wide angle of view while maintaining high performance and miniaturization, particularly in projection systems with reflecting mirrors, where the need for a wider angle of view and fixed focus is increasing due to demands for larger projection images and shorter projector-to-screen distances.
Innovation Solution
A lens system comprising a first lens group with at least eight lenses, including one or more aspherical lenses, and a second lens group with less than four lenses, arranged in a two-group structure with a positive refractive power, where the first lens group has a largest thickness at its peripheral portion, allowing for a half angle of view exceeding 60 degrees and effective aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a projection optical system uses a reflecting mirror to achieve wide angle, then the angle of view increases, but the mirror size becomes larger
Solution Approach 1:
The patent replaces the reflecting mirror system with a fully lens-based projection optical system. Specifically, it uses a two-group lens configuration (first lens group with positive refractive power and second lens group with negative refractive power) to achieve wide-angle projection without requiring large reflecting mirrors, thereby substituting the mechanical mirror system with an optical lens system that achieves the same wide-angle effect while reducing overall device size.
Solution Approach 2:
The projection optical system is divided into two distinct lens groups: a first lens group with positive refractive power and a second lens group with negative refractive power. This segmentation allows each group to perform specific optical functions - the first group provides the primary focusing power while the second group expands the angle of view - enabling the system to achieve wide-angle projection without requiring a single large optical element.
2Area of moving object
If a lens system is designed for wide angle of view, then the angle of view increases, but distortion and aberrations worsen
Solution Approach 1:
The patent applies aspherical surfaces to specific lens elements within the two-group configuration, particularly in the first lens group. This local application of aspherical quality allows for precise correction of spherical aberration and other optical distortions at critical locations in the optical path, while maintaining the overall wide-angle design. The aspherical surfaces provide localized aberration control without requiring the entire system to be overly complex.
Solution Approach 2:
The patent combines different types of lens elements (spherical and aspherical) with different refractive powers (positive and negative) within a unified optical system. This composite approach allows the system to leverage the advantages of each element type - the spherical elements provide basic focusing while the aspherical elements correct distortions - achieving both wide angle of view and high image quality through the synergistic combination of different optical components.
3Manufacturing precision
If the first lens group has more lenses for better performance, then aberration correction improves, but the number of lenses and device complexity increases
Solution Approach 1:
The patent extracts and concentrates the aberration correction function into the second lens group, which contains the aspherical elements. By placing the complex aberration correction task in a dedicated second group rather than distributing it across many lenses in the first group, the system achieves high image quality while keeping the first group relatively simple. This extraction of the correction function allows for more efficient design with fewer total lenses.
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 proposed lens system achieves a wide angle of view exceeding 60 degrees, suppresses distortion, and maintains high performance by optimizing refractive power distribution and lens thickness, enabling miniaturization of projector devices while ensuring effective aberration correction and focusing capabilities.
Implementation Method 1
a first lens group which is constituted of at least eight lenses and has a positive refractive power; an aperture; and a second lens group which is constituted of less than or equal to four lenses and has a positive refractive power, wherein the first lens group includes one or more aspherical lenses
Data Source
AI summary
A lens for projection which is used in an image display device which includes an image display element and projects and displays an image displayed on an image display surface of the image display element as a projection image on a projected surface in an enlarged manner, the lens for projection including in order from an enlargement side to a reduction side, a first lens group which is constituted of at least eight lenses and has a positive refractive power; an aperture; and a second lens group which is constituted of less than or equal to four lenses and has a positive refractive power, wherein the first lens group includes one or more aspherical lenses, and the one or at least one aspherical lens included in the first lens group has a largest thickness at a most peripheral portion of the lens.