Compact Projection Lens Design for Wide Angle View
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Solution Overview
Problem
Existing small projection lenses for portable devices have limitations in reducing size and increasing image size at short distances while maintaining high portability and projection performance, with challenges in achieving a wide angle of view and preventing excessive lens diameter.
Innovation Solution
A small projection lens system with specific structural configurations, including non-circular lens shapes and optimized refractive powers, that satisfies conditional expressions for reducing lens size, increasing image size, and ensuring high portability and projection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the lens diameter is reduced to improve portability, then the device size is reduced, but the angle of view becomes narrow and image size cannot be increased at short distances
Solution Approach 1:
The projection lens is divided into multiple lens elements (first lens L1, second lens L2, third lens L3, fourth lens L4) with different functions. The first lens has positive refractive power for light convergence, the second lens has negative refractive power for light divergence and wide angle achievement, the third lens has positive refractive power for image formation, and the fourth lens has positive refractive power for final focusing. This segmentation allows each element to be optimized for its specific function, achieving both compact size and wide angle of view.
Solution Approach 2:
The patent specifies precise refractive power parameters for each lens element (positive for L1, L3, L4; negative for L2) and establishes conditional expressions for the optical system. By carefully controlling these optical parameters and the arrangement of lens elements, the system achieves a wide angle of view (60 degrees or more) while maintaining a compact form factor suitable for portable devices.
2Adaptability or versatility
If the lens diameter is increased to achieve wide angle of view, then the angle of view increases, but the device size and weight increase
Solution Approach 1:
The patent employs asymmetric lens design where the second lens L2 has negative refractive power and is positioned to specifically address the wide angle requirement. This asymmetric arrangement of positive and negative power lenses allows the system to achieve wide angle coverage without requiring all lenses to have large diameters, thus maintaining compact overall device size while achieving 60 degrees or more angle of view.
3Volume of moving object
If the light valve size is reduced to improve portability, then the device becomes more portable, but the projection performance and image quality deteriorate
Solution Approach 1:
The optical system is designed with dynamic light path management using the specific arrangement of positive and negative power lenses. This allows the system to efficiently utilize the light from the reduced-size light valve, directing and concentrating the light rays to maintain bright and clear projection images even with a compact light valve, thus preserving projection performance while improving portability.
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, high-performance projection lens system with a wide angle of view and increased image size at short distances, effectively addressing the limitations of existing technologies.
Implementation Method 1
a first lens L1 having a positive refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a fourth lens L4 having a positive refractive power arranged in this order from the magnification side
Data Source
AI summary
A small projection lens includes a first lens, which is a biconvex lens, an aperture, an aperture diaphragm (or an aperture), a second lens, which is a negative meniscus lens having a concave surface facing a magnification side, a third lens, which is a positive meniscus lens having a convex surface facing a reduction side, and a fourth lens, which is a biconvex lens having aspheric surfaces at both sides on an optical axis, arranged in this order from the magnification side. A minimum portion of the length of all lens elements of the small projection lens in a diametric direction vertical to the optical axis is equal to or less than 15 mm, and the small projection lens satisfies the following conditional expression: 2.5<&bgr;/S<10.0 (where S indicates the maximum length of a magnification-side image (inch) and &bgr; indicates a magnifying power).