Ultrathin Eyepiece Optical System for VR Headsets
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Solution Overview
Problem
Existing VR head-mounted display devices with larger screens require eyepiece optical systems with long axial distances, which fail to meet the demands for lighter and thinner devices.
Innovation Solution
An ultrathin eyepiece optical system is achieved using a positive lens and a negative lens arranged sequentially and coaxially, where the light incident surface of the positive lens is a planar Fresnel surface and the light emergent surface is a convex surface, and the light incident surface of the negative lens is a concave surface with a convex emergent surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a larger display screen (2-5 inches) is used in VR head-mounted display devices, then the display area and visual field are improved, but the axial distance of the eyepiece optical system increases, making the device thicker and heavier
Solution Approach 1:
The eyepiece optical system is divided into multiple lens elements (first lens element, second lens element, third lens element) arranged in sequence. Each lens element has specific optical properties that collectively achieve the desired optical effect while reducing the overall axial distance. The segmentation allows complex optical functions to be distributed across multiple simpler components.
Solution Approach 2:
The patent specifies precise parameter ranges for each lens element including focal lengths (f1, f2, f3), curvature radii (r1, r2, r3, r4, r5, r6), and thickness values (d1, d2, d3, d4). By optimizing these parameters within defined ranges, the optical system achieves compact design with reduced axial distance while maintaining compatibility with larger display screens and correcting optical aberrations.
2Reliability
If traditional eyepiece optical systems are used with larger display screens, then the optical performance is maintained, but the device weight and thickness increase
Solution Approach 1:
The patent defines specific parameter ranges for lens elements including focal lengths, curvature radii, and thickness values. By optimizing these parameters, the optical system maintains good imaging performance and aberration correction while significantly reducing the axial distance and overall weight of the eyepiece assembly.
Solution Approach 2:
The eyepiece optical system uses multiple lens elements with different optical properties (positive and negative focal lengths) combined in a specific configuration. This composite approach allows the system to achieve superior optical performance through aberration correction while keeping each individual lens element compact and lightweight.
3Length of stationary object
If the axial distance of the eyepiece is reduced for lighter and thinner devices, then device portability is improved, but it becomes difficult to accommodate larger display screens and maintain optical performance
Solution Approach 1:
The optical system is segmented into multiple lens elements with specific functions. The first lens element (positive focal length), second lens element (negative focal length), and third lens element (positive focal length) work together to achieve compact design. This segmentation allows the system to reduce axial distance while maintaining compatibility with larger display screens by distributing optical functions across multiple components.
Solution Approach 2:
The patent specifies optimized parameter ranges for each lens element including focal lengths, curvature radii, and spacing distances. These parameter changes enable the eyepiece to achieve ultrathin design with reduced axial distance while maintaining the ability to accommodate larger display screens and preserve optical performance through precise optical design.
4Ease of manufacture
If simpler lens structures are used to reduce thickness, then manufacturing ease and cost are improved, but optical performance and aberration correction may deteriorate
Solution Approach 1:
The eyepiece uses a composite optical system with multiple lens elements having different focal lengths and optical properties. The first lens element (positive focal length), second lens element (negative focal length), and third lens element (positive focal length) are combined to achieve aberration correction. This composite structure maintains good optical performance while keeping the design relatively simple and manufacturable.
Solution Approach 2:
The patent defines specific parameter ranges for each lens element that balance manufacturing feasibility with optical performance. By specifying reasonable ranges for focal lengths, curvature radii, and thickness values, the design achieves good optical performance and aberration correction while remaining practical for manufacturing with standard processes.
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 reduces the thickness of the lenses, enabling a miniaturized and lighter head-mounted display device while maintaining good optical performance and correcting aberrations.
Implementation Method 1
a light incident surface of the positive lens is a planar Fresnel surface
Implementation Method 2
the light to be observed is incident on the light incident surface of the negative lens, and is refracted by the negative lens to the light incident surface of the positive lens and emitted by the positive lens
Implementation Method 3
the light incident surface of the negative lens is a concave surface, and the light emergent surface of the negative lens is a convex surface
Data Source
Figure 1A
Figure 1B~2A
Figure 2B~3
AI summary
There are provided in the present disclosure an eyepiece and a head-mounted display device, where the eyepiece includes: a positive lens and a negative lens arranged sequentially and coaxially; where a light incident surface of the positive lens is a planar Fresnel surface, and a light emergent surface of the positive lens is a convex surface; a light incident surface of the negative lens is a concave surface, and a light emergent surface of the negative lens is a convex surface; and the light to be observed is incident on the light incident surface of the negative lens and refracted by the negative lens to the light incident surface of the positive lens, and enters human eyes after being refracted by the positive lens. The eyepiece and head-mounted display device provided by the present disclosure realize an ultrathin eyepiece optical system and facilitate a miniaturized and lighter head-mounted display device.