Eyepiece Optical System with Folded Path for Near-Eye Display
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Solution Overview
Problem
Conventional head-mounted display devices lack an optical system that can achieve a large field-of-view in a small size with high optical resolution and long-term comfort, as existing systems suffer from significant chromatism, aberrations, and discomfort due to short exit pupil positions and large size.
Innovation Solution
An eyepiece optical system comprising a first lens, a reflection unit, and a third lens group with aspheric surfaces, where the lenses are arranged coaxially and successively along the optical axis, with specific focal length ratios and configurations to minimize aberrations and maximize field-of-view, using a combination of spherical and aspherical lenses made of glass or plastic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional optical systems are used in head-mounted display devices, then the structure is simple, but the field-of-view is small and chromatism is serious
Solution Approach 1:
The optical system is divided into multiple lens groups (first positive lens group, second negative lens group, third positive lens group) with specific functions. Each group contributes differently to field-of-view expansion and aberration correction, allowing the system to achieve large field-of-view while maintaining manageable complexity through functional segmentation.
Solution Approach 2:
The patent introduces a reflection unit that folds the optical path, effectively adding a spatial dimension to the optical system design. This allows the system to achieve a large field-of-view (24° to 30°) within a compact form factor by utilizing the reflected optical path rather than a straight-line configuration.
2Device complexity
If conventional optical systems are used in head-mounted display devices, then the structure is simple, but chromatism is greater than 0.5 mm between C-line and F-line
Solution Approach 1:
Different lens groups are designed with specific local optical properties: the first positive lens group has positive focal length to converge light, the second negative lens group has negative focal length to diverge light and correct aberrations, and the third positive lens group provides additional convergence. Each group's specific refractive index and curvature are optimized to correct chromatism locally, achieving overall chromatism less than 0.5 mm between C-line and F-line.
Solution Approach 2:
The optical system uses composite lens design with different glass or plastic materials having different refractive indices and dispersion properties. By combining materials with complementary optical characteristics across multiple lens groups, the system achieves superior chromatism correction that would be impossible with a single material or simple lens design.
3Manufacturing precision
If existing optical systems are used, then the exit pupil position is short, but the system cannot achieve high optical resolution
Solution Approach 1:
The optical system is designed with adjustable components that allow the exit pupil position to be dynamically optimized for different viewing conditions. The specific arrangement of lens groups with different focal lengths enables the system to maintain high optical resolution while providing an ergonomic exit pupil position suitable for head-mounted display applications.
4Duration of action of moving object
If existing optical systems are used, then the system size is large, but the system cannot achieve long-term viewing without visual fatigue
Solution Approach 1:
The optical system employs a nested arrangement where lens groups are positioned and sized to fit within each other's optical paths. The first, second, and third lens groups are arranged in a compact sequence with the reflection unit folding the path, creating a nested-like structure that minimizes overall system volume while maintaining the optical path length necessary for comfortable viewing and reduced visual fatigue.
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 eyepiece optical system achieves a compact structure with high optical resolution, low distortion, and reduced chromatism, enabling a larger field-of-view angle of 24° to 30°, improving image quality and user comfort by eliminating system aberrations such as astigmatism and field curvature.
Implementation Method 1
a first lens, a reflection unit, a second lens, and a third lens group arranged coaxially and successively along an optical axis direction from an eye viewing side to a miniature image displayer side
Implementation Method 2
the second lens and the third lens have optical aspheric face shapes
Data Source
AI summary
An eyepiece optical system for a near-eye display, and a head-mounted display device are disclosed. The eyepiece optical system has a first lens, a reflection unit, a second lens, and a third lens group. An optical axis of the second lens and an optical axis of the third lens group are coaxially with each other and coaxially with an optical axis of the first lens when they are reflected by the reflection unit. The third lens group has a third lens. An optical surface of the first lens proximate to the eye viewing side is convex to an eye viewing direction, and an optical surface of the second lens proximate to the miniature image displayer side is concave to a miniature image displayer direction. The present eyepiece optical system has advantages such as compact structure, small size, high optical resolution and so on, which gives the best visual experience.