Radial Gradient Index Lens for VR Focal Length Reduction
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Solution Overview
Problem
Current optical lens modules for virtual reality devices have a long focal length, resulting in a large volume and heavy weight, which negatively impacts user experience due to the increased distance between the display screen and the optical lens, making the devices cumbersome and difficult to wear.
Innovation Solution
An optical lens module with a lens assembly featuring transflective layers on both the light incident and emitting sides, combined with a radial gradient index lens structure that includes a central region with a lower refractive index surrounded by annular regions with sequentially increasing refractive indices, and optionally magnifying lenses such as plano-convex or liquid crystal lenses, to reduce focal length and enhance light convergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional optical lens module with uniform refractive index is used, then the device structure is simple and easy to manufacture, but the focal length is long resulting in large volume and heavy weight
Solution Approach 1:
The patent applies local quality by creating a radial gradient index lens where the refractive index varies spatially - the central region has a different refractive index than the annular regions. This non-uniform refractive index distribution allows different parts of the lens to contribute differently to light focusing, enabling shorter focal length and reduced back focal distance without requiring a complex multi-element lens system.
Solution Approach 2:
The patent changes the refractive index parameter across the lens radius, creating a gradient from the central region to the annular regions. This parameter variation enables the lens to achieve superior optical performance with shorter focal length while maintaining a simple single-element structure that is easy to manufacture.
2Length of stationary object
If the focal length of the optical lens module is reduced, then the back focal length and device size are reduced, but the light convergence capability must be enhanced
Solution Approach 1:
The radial gradient index structure creates local quality variations where the central region and annular regions have different refractive indices. This enables enhanced light convergence capability by optimizing the refractive index at different radial positions, allowing the lens to maintain strong focusing power with a shorter back focal length.
Solution Approach 2:
The lens is constructed with composite material regions having different refractive indices - a central region with one refractive index and surrounding annular regions with different refractive indices. This composite structure enables the lens to achieve both short back focal length and strong light convergence capability simultaneously.
3Use of energy by moving object
If transflective layers are added to the lens assembly, then light utilization efficiency is improved, but the device complexity increases
Solution Approach 1:
The transflective layers serve multiple functions simultaneously: they reflect light back through the lens assembly to improve light utilization efficiency, and they are integrated into the existing radial gradient index lens structure without requiring separate complex optical elements. This multi-functionality approach enhances performance while avoiding excessive complexity.
Solution Approach 2:
The transflective layers are merged with the radial gradient index lens assembly, combining the refractive index gradient function with the light reflection function in a single integrated structure. This merging reduces the need for separate optical components and simplifies the overall device architecture.
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 results in a lighter, thinner, and more compact virtual reality device with a shorter focal length, improved user experience through reduced size and weight, and increased viewing angle, while maintaining ease of mass production.
Implementation Method 1
the lens assembly includes a central region and at least one annular region surrounding the central region; and wherein the central region has a refractive index smaller than that of the at least one annular region
Data Source
AI summary
The present disclosure discloses an optical lens module and a virtual reality device. The optical lens module includes: a lens assembly, and transflective layers attached to surfaces on a light incident side and a light emitting side of the lens assembly. The lens assembly includes a central region and at least one annular region surrounding the central region. The central region has a refractive index smaller than the at least one annular region. When more than one annular region is provided, the annular regions are sequentially arranged layer by layer, the annular region located on the outermost side has the maximum refractive index, and for any other annular region, the refractive index is smaller than that of the annular region located outside thereof.