Reflective Eyepiece Optical System for Head-Mounted Near-to-Eye Display
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Solution Overview
Problem
Existing optical structures for head-mounted display devices face challenges such as heavy weight, low image quality, distortion, insufficient field-of-view, and difficulty in mass production due to complex designs and processing difficulties.
Innovation Solution
A reflective eyepiece optical system is designed with a first lens group and a second lens group that includes an optical reflection surface, where the reflection surface is concave to the human eye viewing direction, and the first optical element reflects light refracted by the first lens group to the second lens group, which then transmits and reflects the light to the human eyes, optimizing focal lengths and sub-lens group combinations to correct aberrations and reduce system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical spherical surfaces and even-order aspherical surfaces are used in reflective optical systems, then image quality can be improved, but the difficulty of implementation and mass production increases greatly
Solution Approach 1:
The optical system is divided into multiple lens groups (first lens group, second lens group, third lens group) with each group containing specific numbers of lenses having defined focal length relationships. This segmentation allows complex optical functions to be distributed across simpler, more manufacturable components while maintaining overall image quality.
Solution Approach 2:
The patent specifies precise parameter relationships between lens groups (focal length ratios, distance ratios) to optimize optical performance. By controlling parameters like f1/fw, f2/fw, and distance ratios within specific ranges, the system achieves high image quality with standard manufacturable surfaces rather than requiring complex free-form surfaces.
2Ease of manufacture
If the optical structure is simplified for mass production, then ease of manufacture improves, but optical performance and field-of-view angle may be insufficient
Solution Approach 1:
The eyepiece optical system is segmented into three lens groups with specific focal length relationships. The first lens group has positive focal length, the second has negative focal length, and the third has positive focal length, with defined ratio relationships. This segmentation enables standard manufacturing processes while achieving high optical performance through coordinated group design.
Solution Approach 2:
Each lens group serves multiple functions: the first lens group corrects spherical aberration and controls field curvature, the second lens group corrects coma and astigmatism, and the third lens group controls distortion and field curvature. This multi-functionality within standardized components achieves high optical performance without requiring complex custom-manufactured elements.
3Area of stationary object
If a relay scheme with free-form surface reflection means is adopted, then field-of-view angle can be increased, but device complexity increases greatly
Solution Approach 1:
The optical system uses three lens groups with specific focal length relationships instead of a single complex free-form surface. The first lens group (positive f1), second lens group (negative f2), and third lens group (positive f3) work together to achieve wide field-of-view while maintaining manufacturability through standard optical surfaces and defined parameter relationships.
Solution Approach 2:
The patent controls the spatial arrangement of lens groups along the optical axis with specific distance ratios (d1/d2, d3/d4) to expand the effective field-of-view. By optimizing the axial positioning and focal length relationships, the system achieves wide angular coverage without requiring complex free-form reflection surfaces.
4Device complexity
If single lens reflection is used, then device complexity is reduced, but the performance ratio of the optical structure is greatly limited
Solution Approach 1:
Instead of using a single reflective lens, the patent divides the optical function into three lens groups with specific focal length relationships. The first lens group (positive f1) handles initial light control, the second lens group (negative f2) provides intermediate correction, and the third lens group (positive f3) completes the imaging function, achieving high performance through coordinated simple components.
Solution Approach 2:
The patent merges multiple lens groups with complementary functions into a unified eyepiece optical system. By combining the positive-focal-length first and third lens groups with the negative-focal-length second lens group in a specific configuration, the system achieves high optical performance that would be difficult to obtain with a single reflective element, while maintaining relative structural simplicity.
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
This configuration enhances image quality, increases the field-of-view, reduces distortion, and simplifies mass production by effectively folding the optical path and correcting aberrations, enabling high-definition, full-frame image display with high liveness and uniformity.
Implementation Method 1
the first optical element reflects the light refracted by the first lens group to the second lens group
Implementation Method 2
transmits the light refracted, reflected, and refracted by the second lens group
Implementation Method 3
the optical reflection surface is concave to a human eye viewing direction
Data Source
AI summary
The present invention relates to a reflective eyepiece optical system and a head-mounted near-to-eye display apparatus. The system includes: a first lens group, and a first optical element and a second lens group for transmitting and reflecting a light from a miniature image displayer. The second lens group includes an optical reflection surface, and the optical reflection surface is an optical surface farthest from a human eye viewing side in the second lens group. The optical reflection surface is concave to a human eye viewing direction. The first optical element reflects the light refracted by the first lens group to the second lens group, and then transmits the light refracted, reflected, and refracted by the second lens group to the human eyes.