Reflective Wide-Angle Lens for Ultra-Short-Throw Projection
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Solution Overview
Problem
Current ultra-short-focus projection lenses face challenges in achieving a projection ratio of less than 0.2 due to increased spherical aberration, coma, and distortion, requiring complex manufacturing processes and multiple lenses, which complicates mass production.
Innovation Solution
A reflective wide-angle lens design with a large aperture, comprising a front lens group, a second lens group, and a curved mirror, where the ratio of the second focal length to the first focal length is between 0.7 and 1.3, and the total lens length to the front lens group length is between 1.8 and 2.2, using aspherical and cemented lenses to minimize aberrations and simplify assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large aperture projection lens is used to increase brightness and achieve a smaller projection ratio, then the brightness is improved, but spherical aberration, coma, astigmatism and distortion increase
Solution Approach 1:
The optical system is divided into three lens groups with specific functions: the first lens group (positive refraction) for light collection, the second lens group (negative refraction) for aberration correction, and the third lens group (positive refraction) for final focusing. This segmentation allows each group to address specific optical challenges independently.
Solution Approach 2:
Different lens groups are designed with specific refractive properties tailored to their functions. The first lens group uses positive refraction for light collection, the second uses negative refraction for aberration correction, and the third uses positive refraction for focusing. Each lens group has optimized parameters (focal lengths, curvatures, thicknesses) for its specific role in the optical system.
2Object-generated harmful factors
If more lenses are used to eliminate aberrations, then the image quality is improved, but the device complexity and manufacturing process increase
Solution Approach 1:
The patent combines multiple lens elements into three integrated lens groups, where each group contains multiple lens elements cemented or mounted together. This merging approach reduces the total number of separate components while maintaining the necessary aberration correction capabilities.
Solution Approach 2:
The patent optimizes specific parameters of each lens group, including focal lengths (f1, f2, f3), curvatures, thicknesses, and spacing distances. By carefully selecting these parameters within specific ranges, the system achieves effective aberration correction with a controlled number of lens groups, avoiding the need for excessive complexity.
3Manufacturing precision
If ultra-short-focus lenses are assembled with fine tuning, then the image clarity is improved, but the manufacturing process becomes complicated and less suitable for mass production
Solution Approach 1:
The lens groups are pre-assembled with integrated mounting structures and predetermined spacing relationships during manufacturing. The optical elements are pre-positioned and secured within each group, so that during final assembly, the groups only need to be positioned relative to each other without requiring complex fine-tuning adjustments. This preliminary assembly simplifies the final manufacturing process for mass production.
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 design achieves a projection ratio of 0.2 with fewer lenses, simplified assembly, and reduced manufacturing complexity, enabling clear focusing across a wide range of projection sizes with minimal distortion and aberration.
Implementation Method 1
a rear lens group comprising a curved mirror for reflecting light passing from the display element through the first lens group and the second lens group
Implementation Method 2
a first lens group for receiving light from the display element, the first lens group having a first focal length; a second lens group for receiving light from the first lens group
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
The present invention provides a reflective wide-angle lens having a large aperture (for example, FNO 1.7) and a small projection ratio (for example, TR ≦ 0.2). The reflective wide-angle lens reduces lens size and reduces the number of lenses required while achieving a clear focus on a wide range of screen sizes. The reflective wide-angle lens comprises a front lens group and a rear lens group. The front lens group comprises a first lens group and two second lens group. The rear lens group comprises a curved mirror. The first lens group comprises at least a triple cemented lens, an aspherical lens, and two spherical lenses. The second lens group comprises at least two aspherical lenses and two spherical lenses. The curved mirror is a concave optical symmetric aspheric mirror.